WorldWideScience

Sample records for clam bivalvia mollusca

  1. Comparative genomics of vesicomyid clam (Bivalvia: Mollusca chemosynthetic symbionts

    Directory of Open Access Journals (Sweden)

    Girguis Peter R

    2008-12-01

    Full Text Available Abstract Background The Vesicomyidae (Bivalvia: Mollusca are a family of clams that form symbioses with chemosynthetic gamma-proteobacteria. They exist in environments such as hydrothermal vents and cold seeps and have a reduced gut and feeding groove, indicating a large dependence on their endosymbionts for nutrition. Recently, two vesicomyid symbiont genomes were sequenced, illuminating the possible nutritional contributions of the symbiont to the host and making genome-wide evolutionary analyses possible. Results To examine the genomic evolution of the vesicomyid symbionts, a comparative genomics framework, including the existing genomic data combined with heterologous microarray hybridization results, was used to analyze conserved gene content in four vesicomyid symbiont genomes. These four symbionts were chosen to include a broad phylogenetic sampling of the vesicomyid symbionts and represent distinct chemosynthetic environments: cold seeps and hydrothermal vents. Conclusion The results of this comparative genomics analysis emphasize the importance of the symbionts' chemoautotrophic metabolism within their hosts. The fact that these symbionts appear to be metabolically capable autotrophs underscores the extent to which the host depends on them for nutrition and reveals the key to invertebrate colonization of these challenging environments.

  2. Fauna Europaea: Mollusca - Bivalvia.

    Science.gov (United States)

    Araujo, Rafael; de Jong, Yde

    2015-01-01

    Fauna Europaea provides a public web-service with an index of scientific names (including important synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. For the Mollusca-Bivalvia, data from 5 families (Margaritiferidae, Unionidae, Sphaeriidae, Cyrenidae, Dreissenidae) containing 55 species are included in this paper. European freshwater bivalves belong to the Orders Unionoida and Cardiida. All the European unionoids are included in the superfamily Unionoidea, the freshwater mussels or naiads. The European cardiids belong to the following three superfamilies: Cardioidea, Cyrenoidea and Dreissenoidea. Among the Unionoidea there are the most imperilled animal groups on the planet while the Cardioidea includes the cosmopolitan genus Pisidium, the Cyrenoidea the Asiatic clam (Corbiculafluminea) and the Dreissenoidea the famous invasive zebra mussel (Dreissenapolymorpha). Basic information is summarized on their taxonomy and biology. Tabulations include a complete list of the current estimated families, genera and species.

  3. Cryptic species of deep-sea clams (Mollusca: Bivalvia: Vesicomyidae) from hydrothermal vent and cold-water seep environments

    Science.gov (United States)

    Vrijenhoek, Robert C.; Schutz, Steven J.; Gustafson, Richard G.; Lutz, Richard A.

    1994-08-01

    A protein-electrophoretic analysis of six putative morphospecies in the bivalve family Vesicomyidae from eight deep-sea hydrothermal vent sites in the eastern Pacific, three cold-water seep sites in the eastern Pacific and the Gulf of Mexico, and one whale-carcass site off Southern California revealed electromorph patterns diagnostic of 10 vesicomyid species. Electrophoretic patterns for 14 enzymes encoded by 17 presumptive gene loci were scored in all 10 species. The pairwise genetic distances (Nei's D) for these 10 species ranged from 0.857 to 2.792, values within the range expected for distinct species and genera. However, the degree of genetic divergence among these taxa could not be used for phylogenetic inferences because allozyme differences had in many cases reached evolutionary saturation. Notwithstanding, the present results revealed a significant problem with current morphospecies identifications of these clams and with applications of the current generic names Calyptogena and Vesicomya. Given the cryptic nature of these taxa, we suggest that subsequent studies simply refer to these clams as "vesicomyids" until careful morphological analyses and molecular studies are completed and systematic relationships are clarified.

  4. Fauna Europaea: MolluscaBivalvia

    Directory of Open Access Journals (Sweden)

    Rafael Araujo

    2015-07-01

    European freshwater bivalves belong to the Orders Unionoida and Cardiida. All the European unionoids are included in the superfamily Unionoidea, the freshwater mussels or naiads. The European cardiids belong to the following three superfamilies: Cardioidea, Cyrenoidea and Dreissenoidea. Among the Unionoidea there are the most imperilled animal groups on the planet while the Cardioidea includes the cosmopolitan genus Pisidium, the Cyrenoidea the Asiatic clam (Corbicula fluminea and the Dreissenoidea the famous invasive zebra mussel (Dreissena polymorpha. Basic information is summarized on their taxonomy and biology. Tabulations include a complete list of the current estimated families, genera and species.

  5. Analysis of trace elements in the shells of short-necked clam Ruditapes philippinarum (Mollusca: Bivalvia) with respect to reconstruction of individual life history

    International Nuclear Information System (INIS)

    Strontium (Sr) concentration in the shells of short-necked clams collected at different locations (Shirahama, warm area and Maizuru, cold area, Japan) was analyzed by two methods, PIXE and EPMA. The Sr concentration of external surface of shell umbo, which was made during short term at early benthic phase, was analyzed by PIXE, and was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length (SL) in individuals with SL < 31 mm, whereas clams collected at Maizuru did not show significant correlation. This result may be caused from the difference of the spawning seasons between two areas. The Sr concentration of cross section of shell umbo, which develops thicker continuously during their life to form faint stratum structure, was analyzed by EPMA along the line across the stratum structure. Some surges and long term waving patterns of the Sr concentration were observed. These results suggest that the life histories of individual clams could be recorded in the shell umbo cross sections as variations of trace elements and analyses of trace elements could clarify the histories of individual clams. (author)

  6. Analysis of trace elements in the shells of short-necked clam Ruditapes philippinarum (Mollusca: Bivalvia) with respect to reconstruction of individual life history

    Energy Technology Data Exchange (ETDEWEB)

    Arakawa, Jumpei; Sakamoto, Wataru [Division of Applied Biosciences, Graduate School of Agriculture, Kyoto Univ., Kyoto (Japan)

    1998-07-01

    Strontium (Sr) concentration in the shells of short-necked clams collected at different locations (Shirahama, warm area and Maizuru, cold area, Japan) was analyzed by two methods, PIXE and EPMA. The Sr concentration of external surface of shell umbo, which was made during short term at early benthic phase, was analyzed by PIXE, and was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length (SL) in individuals with SL < 31 mm, whereas clams collected at Maizuru did not show significant correlation. This result may be caused from the difference of the spawning seasons between two areas. The Sr concentration of cross section of shell umbo, which develops thicker continuously during their life to form faint stratum structure, was analyzed by EPMA along the line across the stratum structure. Some surges and long term waving patterns of the Sr concentration were observed. These results suggest that the life histories of individual clams could be recorded in the shell umbo cross sections as variations of trace elements and analyses of trace elements could clarify the histories of individual clams. (author)

  7. Seasonal Variation in the Biochemical Constituents, Percentage Edibility and Condition Index of the Estuarine Clam, Soletellina diphos (Linnaeus, 1771 (Mollusca: Bivalvia: Veneroida: Psammobiidae

    Directory of Open Access Journals (Sweden)

    Vishwajeet M. Lagade

    2015-01-01

    Full Text Available A variety of biochemical analyses and condition indices have been employed by various authors all over the world to assess the chemical and health index of bivalves. In order to understand the effect of seasonal climate change on the nutritive value and physiological fitness of an estuarine population of the psammobiid Soletellina diphos on the West coast of India. The present study was under-taken in order to determine the seasonal fluctuations of the biochemical constituents in different parts of the body and the percentage edibility and condition index. This study has shown that seasonality is related to significant alterations in the biochemical constituents, percentage edibility and condition index (pS. diphos. These changes could be due to the clam’s seasonal activities, particularly those related to its reproductive cycle. Higher values of the protein and lipid contents were recorded during the post-monsoon period, whereas maximum concentrations of glycogen were detected during the winter season. On the other hand, the lowest protein and glycogen contents were recorded during summer, while minimal lipid contents were observed during the winter season. The Percentage Edibility (PE and Condition Index (CI significantly fluctuated during the annual cycle, with maximum values occurring during the post-monsoon period (September-October 2008 and the lowest values during winter (November-December 2008. Therefore, it seems that the best nutritive season for S. diphos is in the post-monsoon period (September-October, when the highest values of its biochemical composition, percentage edibility and condition index occur. However, during the summer season (April-May, the lowest levels of the organic constituents, the percentage edibility and the condition index were recorded. Hence, that season is not ideal from the nutritive point of view. The study concludes that the physiological activity, the nutritive value and the meat quality of the clam S

  8. 帘蛤科贝类rDNA内转录间隔区序列的研究%Study on Sequences of Ribosomal DNA Internal Transcribed Spacers of Clams Belonging to the Veneridae Family (Mollusca: Bivalvia)

    Institute of Scientific and Technical Information of China (English)

    程汉良; 夏德全; 吴婷婷; 孟学平; 吉红九; 董志国

    2006-01-01

    spacer (ITS1 and ITS2) regions of the ribosomal DNA from four species,Meretrix meretrix L., Cyclina sinensis G., Mercenaria mercenaria L., and Protothaca jedoensis L., belonging to the family Veneridae were amplified by PCR and sequenced. The size of the ITS 1 PCR amplification product ranged from 663 bp to 978 bp,with GC contents ranging from 60.78% to 64.97%. The size of the ITS1 sequence ranged from 585 bp to 900 bp, which is the largest range reported thus far in bivalve species, with GC contents ranging from 61.03% to 65.62%. The size of the ITS2 PCR amplification product ranged from 513 bp to 644 bp, with GC contents ranging from 61.29% to 62.73%. The size of the ITS2sequence ranged from 281 bp to 412 bp, with GC contents ranging from 65.21% to 67.87%. Extensive sequence variation and obvious length polymorphisms were noted for both regions in these species, and sequence similarity of ITS2 was higher than that of ITS1 across species. The complete sequences of 5.8S ribosomal RNA gene were obtained by assembling ITS1 and ITS2 sequences,and the sequence length in all species was 157 bp. The phylogenetic tree of Veneridae clams was reconstructed using ITS2-containing partial sequences of both 5.8S and 28S ribosomal DNA as markers and the corresponding sequence information in Arctica islandica as the outgroup. Tree topologies indicated that P. jedoensis shared a close relationship with M. mercenaria and C.sinensis, a distant relationship with other species.

  9. New records of Protobranchia (Mollusca: Bivalvia in the Peruvian Sea

    Directory of Open Access Journals (Sweden)

    Carlos Paredes

    2014-06-01

    Full Text Available The following species of Bivalvia have been recorded for the first time for Peruvian waters: Nucula (Nucula iphigenia (Dall, 1908; Ennucula cardara (Dall, 1916; Nuculana (Nuculana extenuata (Dall, 1897; Orthoyoldia panamensis (Dall, 1908. These bivalves were collected in the platform and continental slope down to depths of 864 meters.

  10. Complete mitochondrial genome of Coelomactra antiquata (Mollusca: Bivalvia): The first representative from the family Mactridae with novel gene order and unusual tandem repeats.

    Science.gov (United States)

    Meng, Xueping; Zhao, Nana; Shen, Xin; Hao, Jue; Liang, Meng; Zhu, Xiaolin; Cheng, Hanliang; Yan, Binlun; Liu, Zhaopu

    2012-06-01

    The complete mitochondrial genome plays an important role in the accurate inference of phylogenetic relationships among metazoans. Mactridae, also known as trough shells or duck clams, is an important family of marine bivalve clams in the order Veneroida. Here we present the complete mitochondrial genome sequence of the Xishishe Coelomactra antiquata (Mollusca: Bivalvia), which is the first representative from the family Mactridae. The mitochondrial genome of C. antiquata is of 17,384bp in length, and encodes 35 genes, including 12 protein-coding, 21 transfer RNA, and 2 ribosomal RNA genes. Compared with the typical gene content of animal mitochondrial genomes, atp8 and tRNAS(2) are missing. Gene order of the mitochondrial genome of C. antiquata is unique compared with others from Veneroida. In the mitochondrial genome of the C. antiquata, a total of 2189bp of non-coding nucleotides are scattered among 26 non-coding regions. The largest non-coding region contains one section of tandem repeats (99 bp×11), which is the second largest tandem repeats found in the mitochondrial genomes from Veneroida. The phylogenetic trees based on mitochondrial genomes support the monophyly of Veneridae and Lucinidae, and the relationship at the family level: ((Veneridae+Mactridae)+(Cardiidae+Solecurtidae))+Lucinidae. The phylogenetic result is consistent with the morphological classification. Meanwhile, bootstrap values are very high (BP=94-100), suggesting that the evolutionary relationship based on mitochondrial genomes is very reliable.

  11. Sublethal foot-predation on Donacidae (Mollusca: Bivalvia)

    Science.gov (United States)

    Salas, Carmen; Tirado, Cristina; Manjón-Cabeza, Maria Eugenia

    2001-08-01

    nipping amounts to more than 20% in most of the size classes. There was an increase from the small sizes to the largest ones, in which it reaches 37%, with a positive correlation ( r=0.84; p<0.005) between size class and loss of biomass. Possible predators responsible for the foot nipping are crabs. Crab species usually found together with the donacids were Portumnus latipes (Pennant, 1777) Liocarcinus vernalis (Risso, 1816) and Atelecyclus undecimdentatus (Herbst, 1783). In aquarium experiments, they demonstrated an ability to nip the foot of clams. Portumnus latipes was the most active foot nipper, but left alive all the damaged clams. Therefore, we conclude that crabs are the most likely foot-nipping predators in the field.

  12. The identity of Isocrassina, Laevastarte and Ashtarotha (Mollusca, Bivalvia, Astartidae) and their representatives from beaches and estuaries in The Netherlands and Pliocene strata in Belgium

    NARCIS (Netherlands)

    Pouwer, R.

    2009-01-01

    The identity of the subgenera Isocrassina Chavan, 1950, Laevastarte Hinsch, 1952, and Ashtarotha Dall, 1903, of the genus Astarte Sowerby, 1816 in the family Astartidae (Mollusca, Bivalvia) is discussed. Isocrassina has been widely used for Pliocene species in the North Sea Basin. Here it is demonst

  13. Molecular phylogeny of pearl oysters and their relatives (Mollusca, Bivalvia, Pterioidea)

    OpenAIRE

    Tëmkin Ilya

    2010-01-01

    Abstract Background The superfamily Pterioidea is a morphologically and ecologically diverse lineage of epifaunal marine bivalves distributed throughout the tropical and subtropical continental shelf regions. This group includes commercially important pearl culture species and model organisms used for medical studies of biomineralization. Recent morphological treatment of selected pterioideans and molecular phylogenetic analyses of higher-level relationships in Bivalvia have challenged the tr...

  14. Molecular phylogenetic analysis supports a Gondwanan origin of the Hyriidae (Mollusca: Bivalvia: Unionida) and the paraphyly of Australasian taxa.

    Science.gov (United States)

    Graf, Daniel L; Jones, Hugh; Geneva, Anthony J; Pfeiffer, John M; Klunzinger, Michael W

    2015-04-01

    The freshwater mussel family Hyriidae (Mollusca: Bivalvia: Unionida) has a disjunct trans-Pacific distribution in Australasia and South America. Previous phylogenetic analyses have estimated the evolutionary relationships of the family and the major infra-familial taxa (Velesunioninae and Hyriinae: Hyridellini in Australia; Hyriinae: Hyriini, Castaliini, and Rhipidodontini in South America), but taxon and character sampling have been too incomplete to support a predictive classification or allow testing of biogeographical hypotheses. We sampled 30 freshwater mussel individuals representing the aforementioned hyriid taxa, as well as outgroup species representing the five other freshwater mussel families and their marine sister group (order Trigoniida). Our ingroup included representatives of all Australian genera. Phylogenetic relationships were estimated from three gene fragments (nuclear 28S, COI and 16S mtDNA) using maximum parsimony, maximum likelihood, and Bayesian inference, and we applied a Bayesian relaxed clock model calibrated with fossil dates to estimate node ages. Our analyses found good support for monophyly of the Hyriidae and the subfamilies and tribes, as well as the paraphyly of the Australasian taxa (Velesunioninae, (Hyridellini, (Rhipidodontini, (Castaliini, Hyriini)))). The Hyriidae was recovered as sister to a clade comprised of all other Recent freshwater mussel families. Our molecular date estimation supported Cretaceous origins of the major hyriid clades, pre-dating the Tertiary isolation of South America from Antarctica/Australia. We hypothesize that early diversification of the Hyriidae was driven by terrestrial barriers on Gondwana rather than marine barriers following disintegration of the super-continent.

  15. GENETIC DIVERSITY OF FIVE FRESHWATER MUSSELS IN GENUS ANODONTA (MOLLUSCA: BIVALVIA) REVEALED BY RAPD ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Unionidae(Bivalvia)are distributed infreshwaters,and represent a significanttaxonof benthic community[1].In China,freshwater mussels are abundant resources[2].Since1949,substantial investigations onthe unionidfau-na had been undertakenin China[3—8].Withreference tooverseas research[9,10],a preliminary reorganization onthe Unionidae was performed accordingtosome classifica-tion characteristics such as shell shape,larvae character-istics,and breeding habit[11].Due tothe serious conver-gence of freshwater muss...

  16. Growth estimats of the Argentinean surf clam Donax hanleyanus (Bivalvia: Donacidae) derived from fluorescent marking

    OpenAIRE

    Herrmann, Marko; Laudien, Jürgen; Arntz, Wolf; Penchaszadeh, P. E.

    2007-01-01

    RESUMENMicro-growth increments of the Argentinean surf clam Donax hanleyanus were measured at the exposed sandy beach Mar Azul. After marking the shells with the fluorescence marker Calcein, animals were allowed to grow in situ for 36 days. The majority of the marked specimens showed a distinct fluorescent band reflecting the calcein staining time and allowing for growth estimates.Palabras llaves: growth rate, fluorescent marking, Calcein, surf clam, Donax hanleyanusINTRODUCCIÓNGrowth rate is...

  17. Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae)

    OpenAIRE

    Miguel Mies; Felipe Braga; Marcello Santos Scozzafave; Daniel Eduardo Lavanholi de Lemos; Paulo Yukio Gomes Sumida

    2012-01-01

    Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibi...

  18. REVIEW: Symbiosis between the Giant Clams (Bivalvia: Cardiidae and Zooxanthellae (Dinophyceae

    Directory of Open Access Journals (Sweden)

    UDHI EKO HERNAWAN

    2008-01-01

    Full Text Available Giant clams are the largest bivalves in the world that maintain a mutual relationship with zooxanthellae. Individual giant clam can harbor heterogeneous zooxanthellae, at least four taxa in genus Symbiodinium. The Symbiodinium lives in the zooxanthellal tubular system, a tube structure arising from one of the diverticular duct of the clam’s stomach. Since the numbers of zooxanthellae is the one of some significant factors contributing to the clams growth and survival, the giant clams need to adjust the number of zooxanthellae for physiological reason with unclear mechanism. The important role of the symbiotic relationship to the clams can be seen on the survival, growth and nutrition of the clams. There are at least two significant factors determining the symbiosis, i.e. water temperature in related with level of light intensities and ammonium-phosphate rate. Some topic is still unclear, i.e. the determination of species in genus Symbiodinium, the mechanism for adjusting the population numbers of the algae and what kind of environmental factors determining the symbiosis. Thereby further research is still needed to clarify those missing.

  19. The aquatic molluscs (Mollusca: Gastropoda and Bivalvia of Vrachanski Balkan Nature Park

    Directory of Open Access Journals (Sweden)

    DILIAN GEORGIEV

    2016-05-01

    Full Text Available Till now 13 species of aquatic molluscs are known to inhabit the park area: 11 species of snails and 2 species of clams. Even included in the list the species of Grossuana and Radix balthica has to be studied anatomically for sure identification. Nine species are of conservation statute classified as "Least Concern" or "Vulnerable", and four does not have any statute. Three stygobiotic snail species are local endemics.

  20. Genetic diversity of European populations of the invasive soft-shell clam Mya arenaria (Bivalvia)

    NARCIS (Netherlands)

    Lasota, R.; Hummel, H.; Wolowicz, M.

    2004-01-01

    The genetic diversity of the soft-shell clam Mya arenaria from seven locations in Europe (two stations in the southern Baltic Sea (the Gulf of Gdansk) and two in the North Sea (Veerse Meer and Oosterschelde), and three additional stations in the Denmark Straits and Bay of Biscay) was determined usin

  1. Molecular phylogeny of pearl oysters and their relatives (Mollusca, Bivalvia, Pterioidea

    Directory of Open Access Journals (Sweden)

    Tëmkin Ilya

    2010-11-01

    Full Text Available Abstract Background The superfamily Pterioidea is a morphologically and ecologically diverse lineage of epifaunal marine bivalves distributed throughout the tropical and subtropical continental shelf regions. This group includes commercially important pearl culture species and model organisms used for medical studies of biomineralization. Recent morphological treatment of selected pterioideans and molecular phylogenetic analyses of higher-level relationships in Bivalvia have challenged the traditional view that pterioidean families are monophyletic. This issue is examined here in light of molecular data sets composed of DNA sequences for nuclear and mitochondrial loci, and a published character data set of anatomical and shell morphological characters. Results The present study is the first comprehensive species-level analysis of the Pterioidea to produce a well-resolved, robust phylogenetic hypothesis for nearly all extant taxa. The data were analyzed for potential biases due to taxon and character sampling, and idiosyncracies of different molecular evolutionary processes. The congruence and contribution of different partitions were quantified, and the sensitivity of clade stability to alignment parameters was explored. Conclusions Four primary conclusions were reached: (1 the results strongly supported the monophyly of the Pterioidea; (2 none of the previously defined families (except for the monotypic Pulvinitidae were monophyletic; (3 the arrangement of the genera was novel and unanticipated, however strongly supported and robust to changes in alignment parameters; and (4 optimizing key morphological characters onto topologies derived from the analysis of molecular data revealed many instances of homoplasy and uncovered synapomorphies for major nodes. Additionally, a complete species-level sampling of the genus Pinctada provided further insights into the on-going controversy regarding the taxonomic identity of major pearl culture species.

  2. Comparative morphology among representatives of main taxa of Scaphopoda and basal protobranch Bivalvia (Mollusca

    Directory of Open Access Journals (Sweden)

    Luiz Ricardo L. Simone

    2009-01-01

    Full Text Available This study deals with detailed morphology and anatomy of 4 species of Scaphopoda and 5 species of protobranch Bivalvia. Both classes are traditionally grouped in the taxon Diasoma, which has been questioned by different methodologies, such as molecular and developmental. This study is developed under a phylogenetic methodology with the main concern in performing it in an intelligible and testable methodology. The analyzed Scaphopoda species came from the Brazilian coast and belong to the family Dentaliidae [(1 Coccodentalium carduus; (2 Paradentalium disparile] and Gadiliidae; [(3 Polyschides noronhensis, n. sp. from Fernando de Noronha Archipelago; (4 Gadila braziliensis]. These species represent the main branches of the class Scaphopoda. From protobranch bivalves, representatives of the families Solemyidae [(5 Solemya occidentalis, from Florida; S. notialis, n. sp. from S.E. Brazil], Nuculanidae [(6 Propeleda carpentieri from Florida], and Nuculidae [(7 Ennucula puelcha, from south Brazil] are included. These species represent the main branches of the basal Bivalvia. The descriptions on the anatomy of S. occidentalis and of P. carpentieri are published elsewhere. The remaining are included here, for which a complete taxonomical treatment is performed. Beyond these species, representatives of other taxa are operationally included as part of the ingroup (indices are then shared with them, as a procedure to test the morphological monophyly of Diasoma. These taxa are: two lamellibranch bivalves [(8 Barbatia - Arcidae; (9 Serratina - Tellinidae; both published elsewhere;, and Propilidium (10 Patellogastropoda, and (11 Nautilus, basal Cephalopoda, based on basal taxa. The effective outgroups are (12 Neopilina (Monoplacophora and (13 Hanleya (Polyplacophora. The phylogenetic analysis based on morphology revealed that the taxon Diasoma is supported by 14 synapomorphies, and is separated from Cyrtosoma (Gastropoda + Cephalopoda. Although they are not

  3. Complete sequence and polymorphisms of female Ruditapes philippinarum (Mollusca: Bivalvia) mitochondria genome.

    Science.gov (United States)

    Hwang, Jae Yeon; Han, Geon Goo; Park, Jung Youn; Kim, Eun-Mi; An, Cheul Min; Kang, Jung-Ha; Choi, Yun-Jaie; Kim, Eun Bae

    2016-09-01

    Mitogenome of female Ruditapes philippinarum organism was sequenced, and genomic variation and phylogeny were examined in this study. Length of the mitogenome was 22 089 bp showing 94.28% of sequence identity with previously reported sequence. Total 707 single nucleotide polymorphisms, SNPs, were detected and 50 residues were non-synonymous SNPs among the 202 SNPs in protein-coding genes. Deleted genomic fragments with of 265 bp and 322 bp were observed in non-coding regions, ND2 to ND4L and ND4L to tRNA(Ile), respectively. Phylogenic analysis confirmed that used organisms were female R. philippinarum, and the species has closer evolutionary distance with genus Paphia rather than genus Meretrix. Our finding will be help to set an insight for population and evolutionary genomics of Veneroida clams as well as application to marine industry. PMID:26248000

  4. Complete sequence and polymorphisms of female Ruditapes philippinarum (Mollusca: Bivalvia) mitochondria genome.

    Science.gov (United States)

    Hwang, Jae Yeon; Han, Geon Goo; Park, Jung Youn; Kim, Eun-Mi; An, Cheul Min; Kang, Jung-Ha; Choi, Yun-Jaie; Kim, Eun Bae

    2016-09-01

    Mitogenome of female Ruditapes philippinarum organism was sequenced, and genomic variation and phylogeny were examined in this study. Length of the mitogenome was 22 089 bp showing 94.28% of sequence identity with previously reported sequence. Total 707 single nucleotide polymorphisms, SNPs, were detected and 50 residues were non-synonymous SNPs among the 202 SNPs in protein-coding genes. Deleted genomic fragments with of 265 bp and 322 bp were observed in non-coding regions, ND2 to ND4L and ND4L to tRNA(Ile), respectively. Phylogenic analysis confirmed that used organisms were female R. philippinarum, and the species has closer evolutionary distance with genus Paphia rather than genus Meretrix. Our finding will be help to set an insight for population and evolutionary genomics of Veneroida clams as well as application to marine industry.

  5. Reproductive Cycle of Hard Clam, Meretrix lyrata Sowerby, 1851 (Bivalvia: Veneridae) from Sarawak, Malaysia

    OpenAIRE

    Hamli, Hadi; Idris, Mohd Hanafi; Rajaee, Amy Halimah; Kamal, Abu Hena Mustafa

    2015-01-01

    A study of the reproductive cycle of the hard clam, Meretrix lyrata, was documented based on histological observation and Gonad Index (GI). Samples were taken from estuarine waters of the Buntal River in Sarawak, Malaysia. The gonad of M. lyrata started to develop in September 2013. Gametogenesis continued to develop until the maturation and spawning stage from February to April 2014. The GI pattern for a one-year cycle showed a significant correlation with chlorophyll a. The corresponding GI...

  6. Cytogenetics of Anodonta cygnea (Mollusca: Bivalvia) as possible indicator of environmental adversity

    Science.gov (United States)

    Carrilho, J.; Leitão, A.; Vicente, C.; Malheiro, I.

    2008-11-01

    Anodonta cygnea is a freshwater clam, belonging to the Unionidae family, which can be found in rivers and lagoons all over Europe and Northern America. As they appear as important case studies for ecological damage assessments, the various species of the Unionidae family have been submitted to a sort of recent studies on their chromosomal or cytogenetic status. In this study we confirmed the diploid chromosome number of 2 n = 38 for this species, and established for the first time the karyotype, which comprised six metacentric, 12 submetacentric and one subtelocentric chromosome pairs. We also found a high percentage of cells with an abnormal number of chromosomes. Considering that karyotype disturbances in Unionids have been previously related with exposure to chemicals, either natural or produced by human activity, we determined the aneuploidy index for our population. The aneuploidy index is an excellent marker for pollutant presence/effect. The animals acclimatized in tap water and in natural water from the lake where the individuals were collected showed different levels of aneuploidy. The higher values were found in tap water. Chromosome analysis techniques seem a suitable tool to study the impact of contaminants referred above, and making A. cygnea a suitable organism for assessment of an eugenic damage in aquatic systems. On the other hand, our results also point out to the importance of doing the acclimatizing process of the collected animals in their own natural water.

  7. Influence of the invasive Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) on estuarine epibenthic assemblages

    Science.gov (United States)

    Ilarri, M. I.; Souza, A. T.; Antunes, C.; Guilhermino, L.; Sousa, R.

    2014-04-01

    One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2, with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.

  8. Molecular phylogenetics and historical biogeography amid shifting continents in the cockles and giant clams (Bivalvia: Cardiidae).

    Science.gov (United States)

    Herrera, Nathanael D; Ter Poorten, Jan Johan; Bieler, Rüdiger; Mikkelsen, Paula M; Strong, Ellen E; Jablonski, David; Steppan, Scott J

    2015-12-01

    Reconstructing historical biogeography of the marine realm is complicated by indistinct barriers and, over deeper time scales, a dynamic landscape shaped by plate tectonics. Here we present the most extensive examination of model-based historical biogeography among marine invertebrates to date. We conducted the largest phylogenetic and molecular clock analyses to date for the bivalve family Cardiidae (cockles and giant clams) with three unlinked loci for 110 species representing 37 of the 50 genera. Ancestral ranges were reconstructed using the dispersal-extinction-cladogenesis (DEC) method with a time-stratified paleogeographic model wherein dispersal rates varied with shifting tectonics. Results were compared to previous classifications and the extensive paleontological record. Six of the eight prior subfamily groupings were found to be para- or polyphyletic. Cardiidae originated and subsequently diversified in the tropical Indo-Pacific starting in the Late Triassic. Eastern Atlantic species were mainly derived from the tropical Indo-Mediterranean region via the Tethys Sea. In contrast, the western Atlantic fauna was derived from Indo-Pacific clades. Our phylogenetic results demonstrated greater concordance with geography than did previous phylogenies based on morphology. Time-stratifying the DEC reconstruction improved the fit and was highly consistent with paleo-ocean currents and paleogeography. Lastly, combining molecular phylogenetics with a rich and well-documented fossil record allowed us to test the accuracy and precision of biogeographic range reconstructions. PMID:26234273

  9. Molecular phylogenetics and historical biogeography amid shifting continents in the cockles and giant clams (Bivalvia: Cardiidae).

    Science.gov (United States)

    Herrera, Nathanael D; Ter Poorten, Jan Johan; Bieler, Rüdiger; Mikkelsen, Paula M; Strong, Ellen E; Jablonski, David; Steppan, Scott J

    2015-12-01

    Reconstructing historical biogeography of the marine realm is complicated by indistinct barriers and, over deeper time scales, a dynamic landscape shaped by plate tectonics. Here we present the most extensive examination of model-based historical biogeography among marine invertebrates to date. We conducted the largest phylogenetic and molecular clock analyses to date for the bivalve family Cardiidae (cockles and giant clams) with three unlinked loci for 110 species representing 37 of the 50 genera. Ancestral ranges were reconstructed using the dispersal-extinction-cladogenesis (DEC) method with a time-stratified paleogeographic model wherein dispersal rates varied with shifting tectonics. Results were compared to previous classifications and the extensive paleontological record. Six of the eight prior subfamily groupings were found to be para- or polyphyletic. Cardiidae originated and subsequently diversified in the tropical Indo-Pacific starting in the Late Triassic. Eastern Atlantic species were mainly derived from the tropical Indo-Mediterranean region via the Tethys Sea. In contrast, the western Atlantic fauna was derived from Indo-Pacific clades. Our phylogenetic results demonstrated greater concordance with geography than did previous phylogenies based on morphology. Time-stratifying the DEC reconstruction improved the fit and was highly consistent with paleo-ocean currents and paleogeography. Lastly, combining molecular phylogenetics with a rich and well-documented fossil record allowed us to test the accuracy and precision of biogeographic range reconstructions.

  10. Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae

    Directory of Open Access Journals (Sweden)

    Miguel Mies

    2012-06-01

    Full Text Available Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibiotics to avoid culture contamination. Larvae were fed twice with the microalga Isochrysis galbana and zooxanthellae were also offered twice during the veliger stage (days 4 and 6. Larval length was measured using a digitizing tablet coupled to a microcomputer. Larval mortality was exponential during the first 48 hours of life declining significantly afterwards. Mean growth rate was 11.3 μm day-1, increasing after addition of symbionts to 18.0 μm day-1. Survival increased to ca. 75% after the addition of zooxanthellae. The results describe the growth curve for T. crocea larvae and suggest that the acquisition of symbionts by larvae may be useful for larval growth and survival even before larvae have attained metamorphosis.Bivalves tridacnídeos são habitantes conspícuos dos recifes da região do Indo-Pacífico e são cultivados e comercializados para os mercados alimentício e aquarista. No estudo apresentado foram determinadas as taxas de crescimento diário durante a primeira semana de vida da larva do bivalve ornamental Tridacna crocea. As matrizes foram induzidas à desova por meio de uma injeção intragonadal de serotonina realizada através do orifício bissal. Após desova, ovócitos foram coletados, fertilizados e mantidos em béqueres de vidro e tanques de fluxo contínuo tratados com antibióticos para evitar contaminação. Larvas foram alimentadas em duas ocasiões com a microalga Isochrysis galbana e zooxantelas foram oferecidas também por

  11. Exotic molluscs (Mollusca, Gastropoda et Bivalvia in Santa Catarina State, Southern Brazil region: check list and regional spatial distribution

    Directory of Open Access Journals (Sweden)

    A. Ignacio Agudo-Padrón

    2011-06-01

    Full Text Available A total of twenty-one exotic mollusc taxa were assessed for Santa Catarina State (SC, fifteen Gastropoda andsix Bivalvia (twelve terrestrial, five limnic/freshwater - three gastropods and two bivalves, and four marinebivalves. Of these, fourteen are confirmed as invasive species (nine terrestrial, three limnic/freshwater, andtwo marine.

  12. The influence of fish cage culture on δ{sup 13}C and δ{sup 15}N of filter-feeding Bivalvia (Mollusca)

    Energy Technology Data Exchange (ETDEWEB)

    Benedito, E.; Takeda, A.M., E-mail: eva@nupelia.uem.br [Universidade Estadual de Maringa (UEM), PR (Brazil). Nucleo de Pesquisas em Limnologia, Ictiologia e Aquicultura; Figueroa, L. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Ecologia de Ambientes Aquaticos Continentais; Manetta, GI. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Biologia Comparada

    2013-11-15

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ{sup 13}C and δ{sup 15}N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filter C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ{sup 13}C and δ{sup 15}N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ{sup 13}C and δ{sup 15}N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem. (author)

  13. Phylogeny and androgenesis in the invasive Corbicula clams (Bivalvia, Corbiculidae in Western Europe

    Directory of Open Access Journals (Sweden)

    Descy Jean-Pierre

    2011-05-01

    Full Text Available Abstract Background The genus Corbicula is one of the most invasive groups of molluscs. It includes both sexual and androgenetic lineages. The present study re-assessed the different morphotypes and haplotypes of West European Corbicula in order to clarify their taxonomic identification and phylogenetic relationships with American and Asian Corbicula clams. We studied several populations from West European river basins (Meuse, Seine, Rhine and Rhône through an "integrative taxonomy" approach. We combined morphology, partial mitochondrial COI and cyt b sequences and eleven microsatellite loci. Furthermore, we looked for discrepancies between mtDNA and nrDNA/morphology, indicative of androgenesis between lineages. Results There are three Corbicula morphotypes in Western Europe associated to three mitochondrial lineages and three genotypes. Form R shares the same COI haplotype as the American form A and the Japanese C. leana. Form S and the American form C have the same haplotype, although their morphologies seem divergent. The European form Rlc belongs to the same mitochondrial lineage as both the American form B and the Asian C. fluminea. Interestingly, within each haplotype/genotype or lineage, no genetic diversity was found although their invasive success is high. Moreover, we detected rare mismatches between mtDNA and nrDNA/morphology, indicative of androgenesis and mitochondrial capture between form R and form S and therefore challenging the phylogenetic relatedness and the species status within this genus. The global phylogenetic analysis revealed that the sexual Corbicula lineages seem restricted to the native areas while their androgenetic relatives are widespread and highly invasive. Conclusions We clarified the discrepancies and incongruent results found in the literature about the European morphotypes of Corbicula and associated mitochondrial lineages. The three West European morphotypes belong to three distinct nuclear and

  14. Systematic notes on the Mesodesmatidae (Mollusca, Bivalvia), and descriptions of a new species and a new subspecies

    NARCIS (Netherlands)

    Rooij-Schuiling, de L.A.

    1972-01-01

    In 1959, Mr. A. Hoogerwerf obtained a number of small Mollusca from the gizzard of a godwit (Limosa spec.) shot near Koerik, West Irian, New Guinea, that eventually came into my hands for identification. Though the specimens clearly belonged to a species of the genus Mesodesma (Mactracea, fam. Mesod

  15. [On the controversial questions of the taxonomy of Bivalvia (Mollusca): too many species or too few characters?].

    Science.gov (United States)

    Rizhinashvili, A L

    2011-01-01

    Problems emerging in the course of taxonomic studies and species diagnostics of freshwater bivalves are discussed by the example of one of the bivalve groups (the family Unionidae). It is shown that one of the causes of the current, diametrically opposing views on specific and generic systematics of Bivalvia is the fact that researchers revising taxonomic groups ignore complex analysis of several independent characters (conchological, anatomical, biochemical, genetic, etc.).

  16. The linked units of 5S rDNA and U1 snDNA of razor shells (Mollusca: Bivalvia: Pharidae).

    Science.gov (United States)

    Vierna, J; Jensen, K T; Martínez-Lage, A; González-Tizón, A M

    2011-08-01

    The linkage between 5S ribosomal DNA and other multigene families has been detected in many eukaryote lineages, but whether it provides any selective advantage remains unclear. In this work, we report the occurrence of linked units of 5S ribosomal DNA (5S rDNA) and U1 small nuclear DNA (U1 snDNA) in 10 razor shell species (Mollusca: Bivalvia: Pharidae) from four different genera. We obtained several clones containing partial or complete repeats of both multigene families in which both types of genes displayed the same orientation. We provide a comprehensive collection of razor shell 5S rDNA clones, both with linked and nonlinked organisation, and the first bivalve U1 snDNA sequences. We predicted the secondary structures and characterised the upstream and downstream conserved elements, including a region at -25 nucleotides from both 5S rDNA and U1 snDNA transcription start sites. The analysis of 5S rDNA showed that some nontranscribed spacers (NTSs) are more closely related to NTSs from other species (and genera) than to NTSs from the species they were retrieved from, suggesting birth-and-death evolution and ancestral polymorphism. Nucleotide conservation within the functional regions suggests the involvement of purifying selection, unequal crossing-overs and gene conversions. Taking into account this and other studies, we discuss the possible mechanisms by which both multigene families could have become linked in the Pharidae lineage. The reason why 5S rDNA is often found linked to other multigene families seems to be the result of stochastic processes within genomes in which its high copy number is determinant. PMID:21364693

  17. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae)

    OpenAIRE

    Alexander Turra; Maíra Pombo; Marcelo Petracco; Eduardo Siegle; Mariana Fonseca; Denadai, Márcia R.

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying ...

  18. Plasticity of symbiont acquisition throughout the life cycle of the shallow-water tropical lucinid Codakia orbiculata (Mollusca: Bivalvia).

    Science.gov (United States)

    Gros, Olivier; Elisabeth, Nathalie H; Gustave, Sylvie D D; Caro, Audrey; Dubilier, Nicole

    2012-06-01

    In marine invertebrates that acquire their symbionts from the environment, these are generally only taken up during early developmental stages. In the symbiosis between lucinid clams and their intracellular sulfur-oxidizing bacteria, it has been shown that the juveniles acquire their symbionts from an environmental stock of free-living symbiont forms, but it is not known if adult clams are still competent to take up symbiotic bacteria from the environment. In this study, we investigated symbiont acquisition in adult specimens of the lucinid clam Codakia orbiculata, using transmission electron microscopy, fluorescence in situ hybridization, immunohistochemistry and PCR. We show here that adults that had no detectable symbionts after starvation in aquaria for 6 months, rapidly reacquired symbionts within days after being returned to their natural environments in the field. Control specimens that were starved and then exposed to seawater aquaria with sulfide did not reacquire symbionts. This indicates that the reacquisition of symbionts in the starved clams returned to the field was not caused by high division rates of a small pool of remaining symbionts that we were not able to detect with the methods used here. Immunohistochemistry with an antibody against actin, a protein involved in the phagocytosis of intracellular bacteria, showed that actin was expressed at the apical ends of the gill cells that took up symbionts, providing further evidence that the symbionts were acquired from the environment. Interestingly, actin expression was also observed in symbiont-containing cells of untreated lucinids freshly collected from the environment, indicating that symbiont acquisition from the environment occurs continuously in these clams throughout their lifetime. PMID:22672589

  19. Phylogenetic analysis of four nuclear protein-encoding genes largely corroborates the traditional classification of Bivalvia (Mollusca).

    Science.gov (United States)

    Sharma, Prashant P; González, Vanessa L; Kawauchi, Gisele Y; Andrade, Sónia C S; Guzmán, Alejandra; Collins, Timothy M; Glover, Emily A; Harper, Elizabeth M; Healy, John M; Mikkelsen, Paula M; Taylor, John D; Bieler, Rüdiger; Giribet, Gonzalo

    2012-10-01

    Revived interest in molluscan phylogeny has resulted in a torrent of molecular sequence data from phylogenetic, mitogenomic, and phylogenomic studies. Despite recent progress, basal relationships of the class Bivalvia remain contentious, owing to conflicting morphological and molecular hypotheses. Marked incongruity of phylogenetic signal in datasets heavily represented by nuclear ribosomal genes versus mitochondrial genes has also impeded consensus on the type of molecular data best suited for investigating bivalve relationships. To arbitrate conflicting phylogenetic hypotheses, we evaluated the utility of four nuclear protein-encoding genes-ATP synthase β, elongation factor-1α, myosin heavy chain type II, and RNA polymerase II-for resolving the basal relationships of Bivalvia. We sampled all five major lineages of bivalves (Archiheterodonta, Euheterodonta [including Anomalodesmata], Palaeoheterodonta, Protobranchia, and Pteriomorphia) and inferred relationships using maximum likelihood and Bayesian approaches. To investigate the robustness of the phylogenetic signal embedded in the data, we implemented additional datasets wherein length variability and/or third codon positions were eliminated. Results obtained include (a) the clade (Nuculanida+Opponobranchia), i.e., the traditionally defined Protobranchia; (b) the monophyly of Pteriomorphia; (c) the clade (Archiheterodonta+Palaeoheterodonta); (d) the monophyly of the traditionally defined Euheterodonta (including Anomalodesmata); and (e) the monophyly of Heteroconchia, i.e., (Palaeoheterodonta+Archiheterodonta+Euheterodonta). The stability of the basal tree topology to dataset manipulation is indicative of signal robustness in these four genes. The inferred tree topology corresponds closely to those obtained by datasets dominated by nuclear ribosomal genes (18S rRNA and 28S rRNA), controverting recent taxonomic actions based solely upon mitochondrial gene phylogenies.

  20. Effects of anthracene on filtration rates, antioxidant defense system, and redox proteomics in the Mediterranean clam Ruditapes decussatus (Mollusca: Bivalvia).

    Science.gov (United States)

    Sellami, Badreddine; Khazri, Abdelhafidh; Louati, Héla; Dellali, Mohamed; Driss, Mouhamed Ridha; Aïssa, Patricia; Mahmoudi, Ezzeddine; Hamouda, Beyrem; Coelho, Ana Varela; Sheehan, David

    2015-07-01

    This study aimed at analyzing the impact of a toxic polyaromatic hydrocarbon (PAH), anthracene (ANT), on Ruditapes decussatus collected from a Tunisian coastal lagoon (Bizerte Lagoon). Filtration rates, several antioxidant enzymes--superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione transferase (GST)--as well as indices of protein oxidation status were determined in various tissues of this bivalve. Specimens were exposed to 100 μg/L of ANT for 2 days. ANT levels were evaluated using HPLC and were detected in the gill and digestive gland at different amounts. ANT exposure altered the behavior of bivalves by changing the siphon movement and decreasing filtration rate significantly. The enzymatic results indicated that ANT exposure affected the oxidative stress status of the gills of R. decussatus. In addition, modification of proteins was detected in the gills using redox proteomics after ANT treatment. Three protein spots were successfully identified by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-MS). These proteins can be roughly related to muscle contraction function. In contrast, no significant modification of enzymatic and protein responses was detected in the digestive gland after ANT treatment. These data demonstrate that combined behavioral and biochemical analyses are a powerful tool to provide valuable insights into possible mechanisms of toxicity of anthracene in R. decussatus. Additionally, the results highlight the potential of the gill as a valuable candidate for investigating PAH toxicity. PMID:25779113

  1. Free amino acids in the clam Macoma balthica (L.) (Bivalvia, Mollusca) from brackish waters of southern Baltic Sea

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Hummel, H.

    2003-01-01

    Fourteen acidic and neutral free amino acids (FAA) were investigated in soft tissue of Macoma balthica from different depth zones of the Gulf of Gdansk (Baltic Sea) over a full seasonal cycle. The dry weight of the bivalves and physico-chemical parameters of overlying bottom water and surface sedime

  2. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae).

    Science.gov (United States)

    Turra, Alexander; Pombo, Maíra; Petracco, Marcelo; Siegle, Eduardo; Fonseca, Mariana; Denadai, Márcia R

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced) or dead (closed valves were easily opened). Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population.

  3. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae).

    Science.gov (United States)

    Turra, Alexander; Pombo, Maíra; Petracco, Marcelo; Siegle, Eduardo; Fonseca, Mariana; Denadai, Márcia R

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced) or dead (closed valves were easily opened). Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population. PMID:26745804

  4. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae.

    Directory of Open Access Journals (Sweden)

    Alexander Turra

    Full Text Available Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced or dead (closed valves were easily opened. Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population.

  5. Filtration and respiration rates of the short-necked clam Paphia undulata (Born, 1778 (Mollusca, Pelecypoda: Veneridae under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Laureen Morillo Manalo

    2010-12-01

    Full Text Available The filtration and respiration rates of various size classes (35-39.99, 40-44.99,45-49.99, 50-54.99 and 55-59.99 mm of the short-necked clam Paphia undulata were measured in the laboratory. The effects of three light regimes (0 lux, 172.22 lux and 645.83 lux, three microalgal species (Isochrysis galbana, Tetraselmis tetrahele and Chaetoceros calcitrans and four microalgal concentrations (10, 25, 50 and 100 x 104 cells ml-1 on filtration rates were investigated. Mean filtration rate was highest (0.57 ± 0.04 Lh-1ind.-1 under total darkness. This can be attributed to the natural environment of this species which is characterized by silty substrate and low visibility. Filtration was also highest in the microalga Isochrysis galbana (0.67 ± 0.05. Rates initially increased from low to moderate microalgal concentrations (25 x 104 cells ml-1 and decreased at higher concentrations. Filtration generally decreased with increase in clam size. Light intensity, microalgal species and microalgal concentration showed significant effects on filtration. Respiration of fed clams was higher (0.138 ± 0.026 ml O2h-1ind.-1 than unfed clams (0.053± 0.025 ml O2h-1 nd.-1 and increased with clam size.

  6. Effect of heavy metals (Cu, Cd and Pb) on aspartate and alanine aminotransferase in Ruditapes philippinarum (Mollusca: Bivalvia)

    Energy Technology Data Exchange (ETDEWEB)

    Blasco, J.; Puppo, J. [Instituto de Ciencias Marinas de Andalucia, Campus Univ. Rio S. Pedro, 11510 Puerto Real, Cadiz (Spain)

    1999-02-01

    The accumulation of cadmium, copper and lead and their effects on aspartate and alanine aminotransferases in digestive gland, gills, foot and soft body in the clam Ruditapes philippinarum were examined. The animals were exposed to different concentrations: Cd (200-600 {mu}g{center_dot}l{sup -1}), Pb (350-700 {mu}g{center_dot}l{sup -1}) and Cu (10-20 {mu}g{center_dot}l{sup -1}) for 7 days. The highest concentrations were found in digestive gland for cadmium and copper, and in gills for lead, and the lowest values were observed in the foot. Aspartate aminotransferase activity (AST), in general, was not inhibited by cadmium, lead or copper during the exposure. Only in clams exposed to cadmium (600 {mu}g{center_dot}l{sup -1}, 7 days) and copper (20 {mu}g{center_dot}l{sup -1}, 5 days) were observed significant differences (P<0.05) in foot and gills, respectively, with respect to control. In the case of alanine aminotransferase activity (ALT), significant differences were observed for cadmium and lead in treated animals with respect to control. With regard to copper, a decrease in ALT was observed in gills and foot exposed to 20 {mu}g{center_dot}l{sup -1}. A significant correlation (P<0.05) was observed between ALT and metal accumulation for cadmium, copper and lead in gills. In the case of soft body, only cadmium and lead showed a significant correlation. In summary, R. philippinarum can be considered a bioindicator species for cadmium and lead accumulation and ALT could be useful as biomarker of sublethal stress for these metals in soft tissues and gills. Only gills can be considered an adequate target tissue for copper. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Population biology and secondary production of the stout razor clam Tagelus plebeius (Bivalvia, Solecurtidae on a sandflat in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Jolnnye R. Abrahão

    2010-02-01

    Full Text Available The population biology and production of the stout razor clam Tagelus plebeius Lightfoot, 1786 were investigated on an intertidal sandflat on the southeast coast of Brazil (Enseada Beach, São Sebastião, state of São Paulo between April 1997 and April 1998. Two rectangular sites of 50 X 10 m parallel to the waterline were established, site A (upper intertidal level and site B (middle intertidal level, where the samples were taken in an 0.5 x 0.5 m quadrat. High abundances were recorded in winter and spring, with no significant differences between the sites. The high bivalve abundances were related to the presence of very fine homogeneous sediment with low salinities. Tagelus plebeius had negative allometric growth, characteristic of deep burrowers for the relationships DM/SL and AFDM/SL. Parameters of the modified von Bertalanffy growth function were: L∞ = 67.01 mm, K = 1.73 year-1, t0 = -0.11 year, C = 0.43, WP = 0.96. The instantaneous mortality (Z was 3.12 year-1, relatively high in comparison to other tropical bivalve populations. Secondary production was 1.53 g AFDM m-2 year-1, with a P/B ratio reaching 1.37 year-1. This high turnover ratio (P/B was related to a rapid population replacement, connected with the short life span and high mortality of the species.

  8. Evaluation of the levels of Br, Cl, K, Mg, Mn and V in Perna perna mussels (Linnaeus, 1758: Mollusca Bivalvia) collected in the coast of Sao Paulo state, Brazil; Avaliacao dos teores de Br, Cl, K, Mg, Mn e V em mexilhoes Perna perna (Linnaeus, 1758: Mollusca Bivalvia) coletados no litoral do estado de Sao Paulo, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Daniele

    2012-07-01

    The coastal environment has been heavily altered by multiple environmental impacts of human activities, such as disposal of sewage from urban areas, the release of numerous chemical industries, agriculture and the flow of vessels, which can lead to accidental spills of oil and oil products, fuels and other products transported by sea. In this context, a means of determining concentrations of these potentially toxic substances in the sea water is the biomonitoring by means of different types of bivalves, which have been used by various researchers, in Brazil and other countries. With regard to bivalve mollusks, particularly mussels, their use in monitoring the marine contamination is mainly due to their wide geographic distribution, sessile habit and ability to concentrate toxic metals to 102-105 times in relation to the concentrations detected in water. In the present study, we employed the passive biomonitoring using the Perna perna bivalve mollusk with respect to the elements Br, Cl, K, Mg, Mn and V. These elements were chosen since they can be determined by INAA method (Instrumental Neutron Activation Analysis), by means of short irradiation which provides faster analyzes and also due to their importance from the standpoint of environmental or nutritional studies. The aim of this study was to evaluate the content of Br, Cl, K, Mg, Mn and V in samples of Perna perna mussels (Linnaeus, 1758: Mollusca, Bivalvia) collected in coastal regions of Sao Paulo subject to anthropogenic contamination (Ponta de Itaipu and Palmas Island, in Santos), comparing the values obtained in sites potentially impacted with the values of the control site in Praia da Cocanha, in Caraguatatuba. The collection points located in Sao Paulo coast are located in the geographical areas 23 Masculine-Ordinal-Indicator 37'S - 45 Degree-Sign 24' W (Caraguatatuba) and 23 Masculine-Ordinal-Indicator 57'S - 46 Masculine-Ordinal-Indicator 20' W (Santos). The collection of organisms

  9. Simbiontes associados com Anomalocardia brasiliana (Gmelin (Mollusca, Bivalvia, Veneridae na Ilha de Santa Catarina e região continental adjacente, Santa Catarina, Brasil Symbionts associated with Anomalocardia brasiliana (Gmelin (Mollusca, Bivalvia, Veneridae on Santa Catarina Island and adjacent continental region, Santa Catarina, Brazil

    Directory of Open Access Journals (Sweden)

    Guisla Boehs

    2004-12-01

    Full Text Available Berbigões, Anomalocardia brasiliana (Gmelin, 1791, de bancos naturais da Ilha de Santa Catarina e região continental adjacente (SC, Brasil, foram examinados quanto a presença de simbiontes. Holothuriophilus tomentosus (Ortmann, 1894 (Brachyura, Sphenia antillensis Dall & Simpson, 1901 (Bivalvia e poliquetos espionídeos (Polychaeta foram observados macroscopicamente. A análise das secções histológicas evidenciou esporocistos de trematódeos (Digenea, um metacestóide (Cestoda e dois ciliados (Ciliophora.Pointed venus, Anomalocardia brasiliana (Gmelin, 1791, from natural beds of Santa Catarina Island and adjacent continental region (SE Brazil were examined in respect of symbiotic associations. Holothuriophilus tomentosus (Ortmann, 1894 (Brachyura, Sphenia antillensis Dall & Simpson, 1901 (Bivalvia, and polychaete worms (Polychaeta were found by macroscopic diagnosis. By analysis of histological sections, it was noted trematode sporocysts (Digenea, a metacestode (Cestoda and two ciliates (Ciliophora.

  10. First European record of the invasive brackish water clam Rangia cuneata (G.B. Sowerby I, 1831) (Mollusca: Bivalvia)

    OpenAIRE

    Verween, A; Kerckhof, F; Vincx, M.; Degraer, S.

    2006-01-01

    A population of Rangia cuneata (G.B. Sowerby I, 1831), an estuarine bivalve, has been recorded in the harbour of Antwerp, Belgium. This species is new to the European brackish water fauna. After initially finding only a few small individuals in August 2005, R. cuneata was encountered frequently in the pipes of the cooling water system of an industrial plant from February 2006 onwards. Before this present record, R. cuneata was only known from the Gulf of Mexico and the Atlantic coast of North...

  11. The Rho GTPase Family Genes in Bivalvia Genomes: Sequence, Evolution and Expression Analysis

    OpenAIRE

    Xue Li; Ruijia Wang; Xiaogang Xun; Wenqian Jiao; Mengran Zhang; Shuyue Wang; Shi Wang; Lingling Zhang; Xiaoting Huang; Xiaoli Hu; Zhenmin Bao

    2015-01-01

    Background Rho GTPases are important members of the Ras superfamily, which represents the largest signaling protein family in eukaryotes, and function as key molecular switches in converting and amplifying external signals into cellular responses. Although numerous analyses of Rho family genes have been reported, including their functions and evolution, a systematic analysis of this family has not been performed in Mollusca or in Bivalvia, one of the most important classes of Mollusca. Result...

  12. Taxonomy, distribution and population structure of invasive Corbiculidae (Mollusca, Bivalvia in the Suquía River basin, Córdoba, Argentina

    Directory of Open Access Journals (Sweden)

    Paola B. Reyna

    2013-06-01

    Full Text Available Invasive species are one of the most significant causes of biodiversity loss and changes in ecosystem services, which underlines the importance of their detection and their study. The Asian clams (Corbiculidae are invasive organisms that accidentally entered the La Plata River, Argentina, presumably in the 1960s. The objectives of the present study were to identify the corbiculid species and to determine their distribution at several locations along the Suquía River basin, an extended area in central Argentina. In addition, population structure was evaluated monthly during one year, at a site in the city of Córdoba that is characterized by high human influence. The presence of Corbicula fluminea (Müller, 1774 and Corbicula largillierti (Philippi, 1844 in the Suquía River basin is reported for the first time. The former species was found only in a lentic environment (San Roque reservoir, while the latter was also found along the tributary rivers and brooks of the basin. Corbicula largillierti showed variations in average density between the different sites and also in biomass and size classes throughout the study period at the site at Córdoba city. The relative composition of the sediments, flow fluctuation and human pollution may be responsible for the observed differences.

  13. Evaluation of the levels of Br, Cl, K, Mg, Mn and V in Perna perna mussels (Linnaeus, 1758: Mollusca Bivalvia) collected in the coast of Sao Paulo state, Brazil

    International Nuclear Information System (INIS)

    The coastal environment has been heavily altered by multiple environmental impacts of human activities, such as disposal of sewage from urban areas, the release of numerous chemical industries, agriculture and the flow of vessels, which can lead to accidental spills of oil and oil products, fuels and other products transported by sea. In this context, a means of determining concentrations of these potentially toxic substances in the sea water is the biomonitoring by means of different types of bivalves, which have been used by various researchers, in Brazil and other countries. With regard to bivalve mollusks, particularly mussels, their use in monitoring the marine contamination is mainly due to their wide geographic distribution, sessile habit and ability to concentrate toxic metals to 102-105 times in relation to the concentrations detected in water. In the present study, we employed the passive biomonitoring using the Perna perna bivalve mollusk with respect to the elements Br, Cl, K, Mg, Mn and V. These elements were chosen since they can be determined by INAA method (Instrumental Neutron Activation Analysis), by means of short irradiation which provides faster analyzes and also due to their importance from the standpoint of environmental or nutritional studies. The aim of this study was to evaluate the content of Br, Cl, K, Mg, Mn and V in samples of Perna perna mussels (Linnaeus, 1758: Mollusca, Bivalvia) collected in coastal regions of São Paulo subject to anthropogenic contamination (Ponta de Itaipu and Palmas Island, in Santos), comparing the values obtained in sites potentially impacted with the values of the control site in Praia da Cocanha, in Caraguatatuba. The collection points located in São Paulo coast are located in the geographical areas 23º 37'S - 45° 24' W (Caraguatatuba) and 23º 57'S - 46º 20' W (Santos). The collection of organisms was performed in all seasons of the year, beginning in spring 2008 and ending in winter 2009. The samples

  14. Mollusca contagiosa

    OpenAIRE

    Husar, Karmela; Skerlev, Mihael; Husar, Darko

    2009-01-01

    Mollusca contagiosa (MC) definiramo kao čestu virusnu infekciju kože uzrokovanu Molluscipox virusom (MCV) koja se viđa u djece i odraslih. Klinički se manifestira u obliku malih, umbiliciranih papula voštana sjaja. Dok su MC relativno česta u djece od 1. do 5. godine i mogu biti smještene bilo gdje na tijelu, njihova pojavnost u odraslih uglavnom se smatra spolno prenosivom infekcijom (engl. sexually transmitted infection, STI). MCV se može prenositi direktno s osobe na osobu ili autoinokulac...

  15. Sequence analysis of 18S rRNA gene of six Veneridae clams (Mollusca: Bivalvia)%6种帘蛤科贝类18S rRNA基因全序列比较分析

    Institute of Scientific and Technical Information of China (English)

    程汉良; 彭永兴; 王芳; 孟学平; 阎斌伦; 董志国

    2008-01-01

    对文蛤(Meretrix meretrix)、青蛤(Cyclina sinensis)、江户布目蛤(Protothaca jedoensis)、薄片镜蛤(Dosinia corrugata)、紫石房蛤(Saxidomus purpuraus)和菲律宾蛤仔(Ruditapes philippinarum)6种帘蛤科(Veneridae)贝类的18S rRNA基因序列进行了PCR扩增并测序,以期获得这一序列的基本特征,评估其种间变异程度,探讨这一序列在种类鉴定和分子系统发育等研究中的应用价值.测序结果表明,文蛤、青蛤、江户布目蛤、薄片镜蛤、紫石房蛤和菲律宾蛤仔18S rRNA基因序列全长分别为1 900bp、1 838bp、1 831 bp、1 831 bp、1 829bp和1 833bp.序列中A、T、C和G碱基的平均含量分别为24.0%、24.0%、24.2%和27.8%.用MEGA软件对6种帘蛤18S rRNA基因全序列进行了分析,对位排列后的总长度1 906bp,其中变异位点210个,简约信息位点28个,si/sv=1.4(46/32).从GenBank下载了7种帘蛤科贝类18S rDNA全序列,与本研究实测的6种帘蛤一起用MegAlign软件对其18S rDNA序列进行了比对,物种间序列相似百分比为88.7%~99.7%.文蛤与其他12物种间序列差异较大,序列差异百分比均超过了10%,其他各物种间序列差异百分比不超过3%.以异韧带亚纲(Anomalodesmata)笋螂目(Pholadomyoida)的Lyonsia floridana和Cardiomya costellata为外群,采用相邻连接法(NJ)和最大简约法(MP)构建了帘蛤科贝类的系统发育树,其拓扑结构显示雪蛤亚科(Chioninae)、帘蛤亚科(Venerinae)和镜蛤亚科(Dosiniinae)的种类首先聚在一起,形成一个聚类簇;缀锦蛤亚科(Tapetinae)、卵蛤亚科(Pitarinae)、仙女蛤亚科(Callistinae)、青蛤亚科(Cyelininae)和文蛤亚科(Meretricinae)的种类先后分别单独聚成一枝;最后所有帘蛤科物种聚为一枝,与外群相区别,说明18S rDNA序列适合作为帘蛤科系统发育研究的分子标记.

  16. Sequence analysis of the ribosomal DNA internal transcribed spacer region in some clam species (Mollusca: Bivalvia: Veneroida)%几种帘形目贝类rDNA ITS序列的比较

    Institute of Scientific and Technical Information of China (English)

    刘相全; 包振民; 胡景杰; 王师; 方建光; 王如才

    2007-01-01

    扩增并测序了4种帘形目和1种蚶目贝类(外群)核糖体DNA的转录间隔区(ITS)序列.帘形目贝类序列长度在874bp到1466bp之间,GC含量在62%到67%之间,ITS序列在相近的3种帘蛤科贝类之间表现出长度保守性和碱基组成的相似性.采用ITS1,ITS2,以及ITS1与ITS2的连接序列进行聚类,结果表明:2种蛤仔聚为一枝,表现出较近的亲缘关系,帘蛤科的3种贝类聚在一起,再与同属帘形目的缢蛏相聚.研究的结果揭示了帘形目贝类的系统发生关系.

  17. Allozymic variation in the clam genus Eurhomalea (Bivalvia: Veneriidae) along southern South American coast Variación alozímica en el género de almejas Eurhomalea (Bivalvia: Veneriidae) a lo largo de la costa sur de Sudamérica

    OpenAIRE

    M.H GALLARDO; González, C; Mena, C; Lomovasky, B.; Morriconi, E.; E CLASING

    2003-01-01

    The correspondence between allozymic variation and specific differentiation was studied in four populations corresponding to the three nominal, allopatric species of clam genus Eurhomalea (E. rufa, E. lenticularis, E. exalbida) described for southern South America. Allozyme variation scored in 12 loci was high as indicated by heterozygosity levels (15.8-20.7 %) and by the presence of only three monomorphic loci (Hk-2, Icd-2, and Xdh-1). These high estimates of allelic variability were influen...

  18. Molecular classification and morphological traits of two species of Meretrix ( Mollusca, Bivalvia)%浙江和广西两种文蛤的分子鉴定及形态特征分析

    Institute of Scientific and Technical Information of China (English)

    董迎辉; 姚定余; 林志华; 姚韩韩; 陆荣茂

    2011-01-01

    以文蛤如东群体(RD)和北海群体(BH)为对照群,利用线粒体CO Ⅰ基因序列分析技术对苍南文蛤(CN)和北海白壳文蛤(BW)进行了分子鉴定.结果表明,苍南文蛤和斧文蛤的碱基组成非常相似,通过文蛤属贝类基因序列同源性比对和分子系统聚类分析发现,苍南文蛤CN1、CN2与斧文蛤的同源性分别达到100.0%、99.2%,在依据遗传距离构建的系统进化树上,2个苍南文蛤也与斧文蛤单独聚为一支,据此将苍南文蛤确定为斧文蛤,此结果将斧文蛤的分布区域向北扩展到了浙江南部沿海,修正了现有文献中记载的仅在我国南海诸省分布的说法;而自壳文蛤与其它6种文蛤的基因序列同源性都不高(79.6%~85.3%),在系统进化树上单独分出一支,明显是独立于这些文蛤之外的新种.斧文蛤、白壳文蛤与文蛤群体COⅠ基因的遗传多样性分析显示,文蛤BH群体的变异位点数、单倍型数和核苷酸多样性指数均最大,斧文蛤其次,而白壳文蛤10条基因序列完全相同,未发生任何核苷酸位点变异,说明其遗传多样性很低.应用方差分析和Tukey多重比较,分析了斧文蛤、白壳文蛤与文蛤群体的形态差异,发现斧文蛤的壳长明显大于壳高,且SMW/TW、IW/TW 2个参数与文蛤、白壳文蛤群体差异显著(P<0.05);而白壳文蛤的壳宽指数大、壳型相对膨胀,SW/SL和SW/SH值均最大,与文蛤和斧文蛤群体差异显著(P<0.05).本研究结果可为文蛤属贝类种间鉴别、种质资源保护及系统进化研究提供基础资料.%Although many species of the genus Meretrix are commercially-important cultured bivalves,the taxonomy of Meretrix is still in argument over several discrepancies among scientists in the world. Compared with the groups of Meretrix meretrix (RD & BH) ,two groups of Meretrix clam( CN & BW), collected from Cangnan and Beihai, were phylogenetically analyzed and molecularly classified

  19. Use of Population Parameters in Examining Changes in the Status of the Short-Necked Clam Paphia undulata Born, 1778 (Mollusca, Pelecypoda: Veneridae in Coastal Waters of Southern Negros Occidental

    Directory of Open Access Journals (Sweden)

    Anabelle del Norte Campos

    2010-06-01

    Full Text Available Growth, recruitment, mortality and exploitation rate of the short-necked clam Paphia undulata (Born, 1778 were studied in southern Negros Occidental waters between August 2007 and July 2008 from length-frequency data derived from catches of divers, to be able to compare with earlier data derived and analyzed 13 years ago by Agasen et al. (1998. Both sets of data were analyzed using the FiSAT software (Gayanilo & Pauly, 1997. The asymptotic shell length (S¥ = 79 mm derived from the present data proved to be smaller compared to the earlier data (SL¥ = 81.5 mm due to the lack of bigger sizes in the present samples. The growth constant (K = 1.0 yr-1 was however comparable indicating it to be a more species-characteristic parameter. Two recruitment pulses for each study were derived and were found to be correlated with the spawning pattern in the species. The value of natural mortality (M = 1.57 yr-1 derived from bivalve literature, is deemed more appropriate compared to the earlier estimate (M = 2.89 yr-1 based on Pauly’s (1980 empirical equation developed for fish. Total mortality (Z values for both studies were comparable, but a higher level of fishing mortality (F = 4.61 yr-1 was estimated for the present data set, thus resulting likewise in a higher exploitation rate (E = 0.75. These, together with fishery information from an accompanying paper (Villarta & del Norte-Campos, 2010, not only validate the earlier findings of overexploitation due to lack of management, but reveal a worsening condition of the stock, most likely as a result of growth overfishing. Overexploitation can only be mitigated by imposing stringent restrictions in terms of the minimum size for exploitation (45 mm shell length and closed seasons during the spawning peak (August-November.

  20. Mollusca (terrestrial and marine Gastropods et Bivalvia from Morocco

    Directory of Open Access Journals (Sweden)

    Atanas Irikov

    2013-12-01

    Full Text Available Fifteen samples with molluscs are collected from various habitats and regions of Morocco, located in the seashore zone, as well as the central and the eastern parts of the country. We recorded 21 terrestrial and 15 marine species of molluscs. New localities and new species for the fauna of Morocco and the African continent are reported for the first time.

  1. Morphological and molecular diversity of Unionidae (Mollusca, Bivalvia from Portugal

    Directory of Open Access Journals (Sweden)

    Reis, J.

    2013-06-01

    Full Text Available Freshwater mussels from the family Unionidae are known to exhibit a high level of ecological phenotypic plasticity that is reflected in their shell shape. This variation has caused uncertainty on systematics and taxonomy of the group. Several naiad populations from nine river basins from Portugal were analyzed genetically, using two mitochondrial gene fragments (16SrRNA and Cytochrome Oxidase I and morphologically, using ANOVA analyses of shell dimmensions. Molecular phylogenetic analyses were used to revise the systematics and to infer an evolutionary hypothesis for the family at the western-most Atlantic Iberian Peninsula. Genetic and morphological data were in agreement and supported the occurrence of 5 species in the region: Anodonta anatina, Anodonta cygnea, Potomida littoralis, Unio tumidiformis and Unio delphinus. The differentiation of all these species, except A. cygnea, is thought to have taken place during the isolation of the Iberian Peninsula and formation of the current river basins in the Tertiary. The possibility of A. cygnea being a relatively recent introduction is discussed. Basic morphometric measures of the shell proved to be useful to separate Unio species, but also seem to be strongly affected by environmental conditions. The high intra-specific morphologic variation was partially related to the species’ high level of phenotypic plasticity, but seems to have an important role in evolutionary processes.Las náyades de la familia Unionidae tienen gran plasticidad fenotípica, lo que se refleja en la forma de su concha. Esta variabilidad morfológica ha sido causa de gran confusión en la taxonomía y sistemática del grupo. Se han estudiado, genética y morfológicamente, numerosas poblaciones de náyades provenientes de nueve cuencas hidrográficas portuguesas. Para ello se han analizando dos fragmentos de genes mitocondriales (ARNr 16S y Citocromo Oxidasa I así como diferentes variables morfológicas de la concha. Se han realizado además análisis filogenéticos para conocer la sistemática de la familia e inferir una hipótesis evolutiva de su distribución en el oeste de la península Ibérica. Los datos genéticos y morfológicos sugieren la existencia de cinco especies: Anodonta anatina, Anodonta cygnea, Potomida littoralis, Unio tumidiformis y Unio delphinus. La diferenciación de estas especies, con la excepción de A. cygnea, ha ocurrido durante el aislamiento de la península Ibérica y posterior formación de las actuales cuencas hidrográficas en el Terciario. Se discute la posibilidad de que la presencia de A. cygnea se deba a una introducción reciente. Los datos morfométricos analizados pueden ser útiles para separar las especies del género Unio, pero son también dependientes de las condiciones ambientales. La elevada variabilidad morfológica dentro de cada especie está relacionada con su plasticidad fenotípica, pero tiene a su vez un importante papel en el proceso evolutivo.

  2. Allozymic variation in the clam genus Eurhomalea (Bivalvia: Veneriidae along southern South American coast Variación alozímica en el género de almejas Eurhomalea (Bivalvia: Veneriidae a lo largo de la costa sur de Sudamérica

    Directory of Open Access Journals (Sweden)

    M.H GALLARDO

    2003-09-01

    Full Text Available The correspondence between allozymic variation and specific differentiation was studied in four populations corresponding to the three nominal, allopatric species of clam genus Eurhomalea (E. rufa, E. lenticularis, E. exalbida described for southern South America. Allozyme variation scored in 12 loci was high as indicated by heterozygosity levels (15.8-20.7 % and by the presence of only three monomorphic loci (Hk-2, Icd-2, and Xdh-1. These high estimates of allelic variability were influenced by the low levels of interspecific genetic similarity (I = 0.64 and for the high conspecific values of genetic identity observed. The high estimates of substructuring found at the species level (F ST = 0.39 contrasted with the low differentiation (F ST = 0.027 and high migration rate (Nm = 9 existing among conspecific samples. Diagnostic allele fixation coinciding with specific recognition was recorded at locus Hk-1 whereas nearly-fixed differences at loci (Adh, alpha-Gpd, Icd-1, Ldh, Odh, Pgm-3 differed sharply in frequency among species. The Wagner procedure and the neighbor-joining algorithm produced a similar tree topology highly related to the geographic distance and to their taxonomic recognition. The lack of coincidence between patterns of allozymic variation and the two distinctive shell morphs (flat and globoid occurring in E. exalbida from Ushuaia bay do not support their taxonomic recognition.Se estudió la correspondencia entre la variación bioquímica y la diferenciación específica en cuatro poblaciones correspondientes a las tres especies nominales y alopátricas en las almejas del género Eurhomalea (E. rufa, E. lenticularis, E. exalbida descritas para la zona sur de Sudamérica. La variación alozímica registrada en 12 loci fue alta como lo indican los altos niveles de heterocigosidad (15,8-20,7 % y por la presencia de solo tres loci monomórficos (Hk-2, Icd-2 y Xdh-1. Esta alta estimación de variabilidad alélica influyó en los bajos

  3. The Rho GTPase Family Genes in Bivalvia Genomes: Sequence, Evolution and Expression Analysis.

    Directory of Open Access Journals (Sweden)

    Xue Li

    Full Text Available Rho GTPases are important members of the Ras superfamily, which represents the largest signaling protein family in eukaryotes, and function as key molecular switches in converting and amplifying external signals into cellular responses. Although numerous analyses of Rho family genes have been reported, including their functions and evolution, a systematic analysis of this family has not been performed in Mollusca or in Bivalvia, one of the most important classes of Mollusca.In this study, we systematically identified and characterized a total set (Rho, Rac, Mig, Cdc42, Tc10, Rnd, RhoU, RhoBTB and Miro of thirty Rho GTPase genes in three bivalve species, including nine in the Yesso scallop Patinopecten yessoensis, nine in the Zhikong scallop Chlamys farreri, and twelve in the Pacific oyster Crassostrea gigas. Phylogenetic analysis and interspecies comparison indicated that bivalves might possess the most complete types of Rho genes in invertebrates. A multiple RNA-seq dataset was used to investigate the expression profiles of bivalve Rho genes, revealing that the examined scallops share more similar Rho expression patterns than the oyster, whereas more Rho mRNAs are expressed in C. farreri and C. gigas than in P. yessoensis. Additionally, Rho, Rac and Cdc42 were found to be duplicated in the oyster but not in the scallops. Among the expanded Rho genes of C. gigas, duplication pairs with high synonymous substitution rates (Ks displayed greater differences in expression.A comprehensive analysis of bivalve Rho GTPase family genes was performed in scallop and oyster species, and Rho genes in bivalves exhibit greater conservation than those in any other invertebrate. This is the first study focusing on a genome-wide characterization of Rho GTPase genes in bivalves, and the findings will provide a valuable resource for a better understanding of Rho evolution and Rho GTPase function in Bivalvia.

  4. Processing clam meat into pickles

    OpenAIRE

    P. K. Vijayan; Perigreen, P.A.; Surendran, P.K.; K. K. Balachandran

    1982-01-01

    Methods have been worked out for the production of pickles from clam (Velorita sp.) meat. The bacteriological quality of the clam meat at different stages of processing was studied. The clam pickles packed in glass bottles and sealed air tight remained in good condition for six months at ambient temperatures.

  5. Fluorescent amplified fragment length polymorphism (fAFLP)analysis of population genetic diversity and species relationships of four species of cultured clams in family Veneridae (Mollusca: Bivalvia)%帘蛤科4种养殖蛤群体遗传多样性和种间关系的fAFLP分析

    Institute of Scientific and Technical Information of China (English)

    彭永兴; 程汉良; 夏德全; 吴婷婷; 孟学平; 吉红九; 董志国

    2008-01-01

    利用荧光标记扩增片段长度多态性(fAFLP)技术对文蛤(Meretrix meretrix)、青蛤(Cyclina sinensis)、菲律宾蛤仔(Ruditapes philippinarum)和硬壳蛤(Mercenaria mercenaria)4种帘蛤科贝类的群体遗传多样性和种间关系进行了研究.选择EcoR Ⅰ/Mse Ⅰ进行酶切,使用6个E+3/M+3引物组合进行扩增,共获得1096个位点,多态位点比率95.1%,片段长度50~456 bp.其中,文蛤、青蛤、菲律宾蛤仔和硬壳蛤分别得到681,715,702和694个位点,相应的多态位点比率为76.8%,81.7%,83.0%和75.1%,得到17个种特异性位点,可作为4物种特征标记.分析了群体遗传相似系数和遗传多样性指数以及种间遗传相似系数.结果表明,硬壳蛤群体遗传相似系数最高(0.670 9),遗传多样性指数最低(0.236 0);菲律宾蛤仔群体遗传相似系数最低(0.592 5),遗传多样性指数最高(0.261 8);根据遗传相似系数采用UPGMA法构建了4物种32个体的聚类图,表明文蛤与菲律宾蛤仔遗传关系最近,青蛤与其他3物种遗传关系较远.

  6. Sequence analysis of mitochondrial COI gene fragment of six Veneridae clams ( Mollusca: Bivalvia) and four populations of Meretrix meretrix%6种帘蛤科贝类及4个地理种群文蛤线粒体COI基因片段序列分析

    Institute of Scientific and Technical Information of China (English)

    程汉良; 夏德全; 吴婷婷; 孟学平; 吉红九; 董志国; 陈淑吟

    2007-01-01

    对文蛤(Meretrix meretrix L,1758)、青蛤(Cyclina sinensis G.,1791)、硬壳蛤(Mercenaria mercenaria L,1758)、江户布目蛤(Protothaca jedoensis L,1874)、薄片镜蛤(Dosinia corrugata R.,1850)和菲律宾蛤仔(Ruditapes philippinarum A.,1850)6种帘蛤科贝类和4个地理种群文蛤(大连、连云港、湛江、防城港)的细胞色素c氧化酶亚基Ⅰ(COI)基因片段的核苷酸序列进行了分析,以探讨这一序列在种质鉴定、种群遗传结构和分子系统发生研究中的应用价值.测序结果表明,所有物种扩增片段长度均为709 bp,序列A+T含量(62.2%~67.6%)明显高于GC含量.物种间共有变异位点311个,其中简约信息位点202个;文蛤4个地理种群间共有变异位点46个,其中简约信息位点2个.此区段共编码235个氨基酸,种间共有氨基酸变异位点85个;文蛤种群间只有1个氨基酸变异位点.以COI基因片段序列为标记,用大竹蛏(Solen grandis)作外群,构建了帘蛤科贝类的系统发生树,其拓扑结构显示4个地理种群文蛤首先聚为1个单元,然后与青蛤聚在一起,最后所有帘蛤科物种聚为一枝,与外群相区别,其结果与传统形态分类基本一致,说明COI基因适合作为该科贝类种群遗传结构和系统发生研究的分子标记.

  7. Ocorrência do bivalve exótico Mytilopsis leucophaeta (Conrad (Mollusca, Bivalvia, no Brasil Occurrence of exotic bivalve Mytilopsis leucophaeta (Conrad (Mollusca, Bivalvia, in Brazil

    Directory of Open Access Journals (Sweden)

    José R. B. de Souza

    2005-12-01

    Full Text Available O molusco Mytilopsis leucophaeta (Conrad, 1831, natural da América do Norte, foi localizado no litoral de Pernambuco, Brasil, em 2004, trazido provavelmente por água de lastro de navios. Na região, sua distribuição atualmente abrange zonas estuarinas adjacentes ao Porto do Recife. Os organismos foram encontrados restritos à região entre-marés, formando agregados densos com até 176.800 ind./m².The mussel Mytilopsis leucophaeta (Conrad, 1831 is native to North America. It was found at Pernambuco Coast, northeastern Brazil, in 2004, probably brought by ships' ballast water. The distribution of this species has been now spread to estuarial area near Recife Harbour. They showed a clumped distribution with a maximum of 176,800 ind./m² only in the intertidal zone.

  8. Phylogenetic analysis of Pectinidae (Bivalvia) based on the ribosomal DNA internal transcribed spacer region

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The ribosomal DNA internal transcribed spacer (ITS) region is a useful genomic region for understanding evolutionary and genetic relationships. In the current study, the molecular phylogenetic analysis of Pectinidae (Mollusca: Bivalvia) was performed using the nucleotide sequences of the nuclear ITS region in nine species of this family. The sequences were obtained from the scallop species Argopecten irradians, Mizuhopecten yessoensis, Amusium pleuronectes and Mimachlamys nobilis, and compared with the published sequences of Aequipecten opercularis, Chlamys farreri, C. distorta, M. varia, Pecten maximus, and an outgroup species Perna viridis. The molecular phylogenetic tree was constructed by the neighbor-joining and maximum parsimony methods. Phylogenetic analysis based on ITS1, ITS2, or their combination always yielded trees of similar topology. The results support the morphological classifications of bivalve and are nearly consistent with classification of two subfamilies (Chlamydinae and Pectininae) formulated by Waller. However, A. irradians, together with A. opercularis made up of genera Amusium, evidences that they may belong to the subfamily Pectinidae. The data are incompatible with the conclusion of Waller who placed them in Chlamydinae by morphological characteristics. These results provide new insights into the evolutionary relationships among scallop species and contribute to the improvement of existing classification systems.

  9. [Mollusc diversity in an Arca zebra (Mollusca: Bivalvia) community, Chacopata, Sucre, Venezuela].

    Science.gov (United States)

    Prieto, A S; Ruiz, L J; García, N; Alvarez, M

    2001-06-01

    The diversity of a subtidal epifaunal mollusk community was studied from September, 1990 to September, 1991 in Chacopata, Sucre State, Venezuela. There were 40 species (24 bivalves and 16 gastropods). The diversity indexes (H' = 2.087, J' = 0.392, 1/D = 0.528) were low when compared with other tropical zones. Monthly diversity reached its maximum in September, 1990 (1.63 bits/ind.) and July, 1991 (1.60 bits/ind.); minimum diversity occurred in June, 1991 (0.52 bits/ind.). A Log series model applied to species abundance data showed a straight line with a diversity index alpha of 5.56. Of 40 species identified, the turkeywing Arca zebra was dominant (69% in number of individuals and 72% of biomass) followed by Pinctada imbricata, Modiolus squamosus, Chama macerophyla and Anadara notabilis. The predatory snails Phyllonotus pomum, Chicoreus brevifrons and Murex recurvirostris seemed to have trophic relationships with A. zebra. The total mean biomass in wet weight (469.20 +/- 263 g m-2, shell included) was high which indicates that A. zebra, a species with a rapid growth rate, occupies a central role in the assemblage as an efficient filter feeder that converts planktonic food into available biomass, supporting one of the most important fisheries in Venezuela. PMID:11935909

  10. Toxicological aspects associated with the ecology of Donax trunculus (Bivalvia, Mollusca) in a polluted environment

    International Nuclear Information System (INIS)

    This study provides data on the ecology and toxicology observed in the population of Donax trunculus, a sand dwelling mussel, in the shallow subtidal of Haifa Bay (Mediterranean Sea, Israel). The studied population of the mussel forms a dominant fraction in a community of sand-dwelling molluscs in a zone located 5-25 m from the shoreline, and at depths of 20-120 cm, numbering up to 2000 per m2. Samples of the mussel were collected from three sites, located within 9 km of shore in Haifa Bay. These included a clean site (Akko), a site polluted by a chemical PVC-polymer industry (Frutarom), and a site polluted with oil and waste from the petrochemical industry (Qiryat Yam). Metal analysis indicated site-dependent variations in levels of cadmium, lead, copper and mercury in the mussel soft tissues. Copper levels were similar in the bivalves collected from all the sites. Levels of mercury were significantly higher in specimens from the PVC-polluted site (Frutarom) while levels of cadmium were higher in Akko and Qiryat Yam compared to Frutarom. Lead residues were found only in Donax from Akko. The residual contents of mercury, copper and cadmium were relatively high in the young and noticeably low in Donax of medium body size. The main site of deposition of metals was in the soft tissues of the bivalve, but bioaccumulation of metals was also found in the shells. A marked increase in permeability of gills and mantle to the fluorescent anionic dye-fluorescein (FLU) was detected in Donax from Qiryat Yam and especially Frutarom, compared to the bivalves sampled from Akko. Multiple foci of enhanced permeability (multiple fluorescent spots) were detected in all the individuals sampled from Frutarom but none in the bivalve samples from Akko. Lysosomal accumulation of the metachromatic fluorescent cationic probe, acridine orange - (AO), was significantly decreased in the tissues of D. trunculus from polluted sites, especially polluted by the PVC factory. This decrease correlated with lysosomal enlargement and the formation of secondary lysosomes. D. trunculus appears to possess the most effective biochemical and physiological defense mechanisms enabling it to survive in habitats of polluted shallow waters, where other sand dwelling mollusc species were absent or found only in waters deeper then 2.5 m. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  11. The Recent Pectinoidea of the New Zealand region (Mollusca: Bivalvia: Propeamussiidae, Pectinidae and Spondylidae)

    NARCIS (Netherlands)

    H.H. Dijkstra; B.A. Marshall

    2008-01-01

    The Recent Pectinoidea of the New Zealand region are reviewed. Eight new species are described from the New Zealand Exclusive Economic Zone: Parvamussium cancellorum, Cyclochlamys austrina, Cc. delli, Cc. irregularis, Cc. munida, Cc. pileolus, Cyclopecten fluctuosus, and Catillopecten tasmani. Nine

  12. Systematic reviews on the Mesodesmatidae (Mollusca, Bivalvia) I. The Genus Monterosatus Beu, 1971

    NARCIS (Netherlands)

    Rooij-Schuiling, de L.A.

    1977-01-01

    In trying to identify a small Mesodesma from West Irian, New Guinea, much material in the collections of several museums was studied. As a guide for the identification I at first used the revision of the Mesodesmatidae by Lamy (1914), which is based exclusively on the collections of the Parisian mus

  13. Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia) specimens

    OpenAIRE

    Sonia Maria Lima Santos; Claudia Helena Tagliaro; Colin Robert Beasley; Horacio Schneider; Iracilda Sampaio; Carlos Santos Filho; Ana Cláudia de Paula Müller

    2005-01-01

    The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested. Phylogenetic trees support the grouping of Bankia fimbriatula with Nausitora fusticula and of Neoteredo reynei w...

  14. Clarifying phylogenetic relationships and the evolutionary history of the bivalve order Arcida (Mollusca: Bivalvia: Pteriomorphia).

    Science.gov (United States)

    Combosch, David J; Giribet, Gonzalo

    2016-01-01

    The systematics of the bivalve order Arcida constitutes an unresolved conundrum in bivalve systematics. The current definition of Arcida encompasses two superfamilies: Limopsoidea, which includes the recent families Philobryidae and Limopsidae, and Arcoidea, which encompasses the families Arcidae, Cucullaeidae, Noetiidae, Glycymerididae and Parallelodontidae. This classification, however, is controversial particularly with respect to the position and taxonomic status of Glycymerididae. Previous molecular phylogenies were limited either by the use of only a single molecular marker or by including only a few limopsoid and glycymeridid taxa. The challenging nature of Arcida taxonomy and the controversial results of some of the previous studies, prompted us to use a broad range of taxa (55 species), three nuclear markers (18S rRNA, 28S rRNA and histone H3) and a wide range of algorithmic approaches. This broad but stringent approach led to a number of results that differ significantly from previous studies. We provide the first molecular evidence that supports the separation of Arcoidea from Limopsoidea, although the exact position of Glycymerididae remains unresolved, and the monophyly of Limopsoidea is algorithm-dependent. In addition, we present the first time-calibrated evolutionary tree of Arcida relationships, indicating a significant increase in the diversification of arcidan lineages at the beginning of the Cretaceous, around 140Ma. The monophyly of Arcida, which has been supported previously, was confirmed in all our analyses. Although relationships among families remain somehow unresolved we found support for the monophyly of most arcidan families, at least under some analytical conditions (i.e., Glycymerididae, Noetiidae, Philobryidae, and Limopsidae). However, Arcidae, and particularly Arcinae, remain a major source of inconsistency in the current system of Arcida classification and are in dire need of taxonomic revision.

  15. The Marine Mollusca of Suriname (Dutch Guiana) Holocene and recent Part II. Bivalvia and Scaphopoda

    NARCIS (Netherlands)

    Regteren Altena, van C.O.

    1971-01-01

    "The student must know something of systematic work. This is populary supposed to be a dry-as-dust branch of zoology. In fact, the systematist may be called the dustman of biology, for he performs a laborious and frequently thankless task for his fellows, and yet it is one which is essential for the

  16. Phylogeny and evolution of ontogeny of the family Oxytomidae Ichikawa, 1958 (Mollusca: Bivalvia)

    Science.gov (United States)

    Lutikov, O. A.; Temkin, I. E.; Shurygin, B. N.

    2010-08-01

    We described ontogenies and reconstructed morphogeneses of hinges in some supraspecific taxa of the bivalve family Oxytomidae Ichikawa, 1958 from the Mesozoic of Russia. The phylogeny of the family is reconstructed using evolutionary and cladistic methods. The appearance of the endemic genus Arctotis Bodylevsky, 1960 in the epicontinental seas of Siberia can be explained in terms of gradual transformations of the ligament and byssal apparatus in the Northern Siberian members of Praemeleagrinella Lutikov et Shurygin, 2009 and Praearctotis Lutikov et Shurygin, 2009.

  17. On the identity of broad-shelled mussels (Mollusca, Bivalvia, Mytilus) from the Dutch delta region

    NARCIS (Netherlands)

    Groenenberg, D.S.J.; Wesselingh, F.P.; Rajagopal, S.; Jansen, J.M.; Bos, M.M.; Velde, van der G.; Gittenberger, E.; Hoeksema, B.W.; Raad, H.; Hummel, H.

    2011-01-01

    Late Quaternary (Eemian) deposits of the Netherlands contain shells that resemble those of living Mytilus galloprovincialis. Similar broad-shelled mytilids also occur in estuaries of the southwestern Netherlands together with slender individuals typical of M. edulis. We sampled living mussels along

  18. Size-differential feeding in Pinna nobilis L. (Mollusca: Bivalvia): Exploitation of detritus, phytoplankton and zooplankton

    Science.gov (United States)

    Davenport, John; Ezgeta-Balić, Daria; Peharda, Melita; Skejić, Sanda; Ninčević-Gladan, Živana; Matijević, Slavica

    2011-04-01

    The endangered fan shell Pinna nobilis is a large bivalve mollusc (animals has implications for future trophic studies of this endangered species. This study also provides the first demonstration of predation on zooplankton by P. nobilis.

  19. Thyasira ockelmanni (Mollusca: Bivalvia: Veneroidea, A new species of Thyasiridae from the Norwegian Sea

    Directory of Open Access Journals (Sweden)

    Rozemarijn Keuning

    2010-12-01

    Full Text Available 800x600 Normal 0 21 false false false NO-BOK X-NONE X-NONE MicrosoftInternetExplorer4 A new species of Thyasiridae, Thyasira ockelmanni n.sp. is described from the abyssal depths of the Norwegian Sea. The generic assignment is tentative and possible alternatives are discussed. The new species has some resemblance to Thyasira subovata (Jeffreys, 1881 and Adontorhina similis Barry & McCormack, 2007, but the posterior outline is rounded and not angulate or truncate as in these species.

  20. Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia specimens

    Directory of Open Access Journals (Sweden)

    Sonia Maria Lima Santos

    2005-03-01

    Full Text Available The current taxonomy of the Teredinidae (shipworms is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested. Phylogenetic trees support the grouping of Bankia fimbriatula with Nausitora fusticula and of Neoteredo reynei with Psiloteredo healdi, but the genetic distances do not justify the classification of these species into two distinct subfamilies. The results show that B. fimbriatula, N. reynei and P. healdi specimens from the coast of the Brazilian state of Pará have five distinct 16S rRNA haplotypes, with one N. reynei haplotype differing from the other haplotypes in respect to at least seven sequences sites, indicating the existence of two very distinct sympatric lineages.

  1. Sinanodonta woodiana (Mollusca: Bivalvia: Unionidae: Isolation and Characterization of the First Microsatellite Markers

    Directory of Open Access Journals (Sweden)

    Elena Iulia Iorgu

    2011-08-01

    Full Text Available Sinanodonta woodiana (Lea, 1834 is a large Unionid species with a real invasion success. It colonized Europe, Central America, the Indonesian Islands and recently North America. The species life cycle involves a larval parasitic stage on freshwater fish species which contributes to the spread of the mussel. In this paper we describe, for the first time, eight polymorphic microsatellite loci for the species Sinanodonta woodiana. The genetic screening of individuals confirmed that all loci were highly polymorphic. The number of alleles per locus ranged from 7 to 14 and the observed heterozygosity ranged from 0.650 to 0.950. These loci should prove useful to study the species population genetics which could help to infer important aspects of the invasion process.

  2. Toxicological aspects associated with the ecology of Donax trunculus (Bivalvia, Mollusca) in a polluted environment

    Energy Technology Data Exchange (ETDEWEB)

    Fishelson, L.; Manelis, R. [Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv (Israel); Bresler, V.; Zuk-Rimon, Z.; Dotan, A.; Yawetz, A. [Institute for Nature Conservation Research, Faculty of Life Sciences, Tel Aviv University, Tel Aviv (Israel); Hornung, H. [Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa (Israel)

    1999-02-09

    This study provides data on the ecology and toxicology observed in the population of Donax trunculus, a sand dwelling mussel, in the shallow subtidal of Haifa Bay (Mediterranean Sea, Israel). The studied population of the mussel forms a dominant fraction in a community of sand-dwelling molluscs in a zone located 5-25 m from the shoreline, and at depths of 20-120 cm, numbering up to 2000 per m{sup 2}. Samples of the mussel were collected from three sites, located within 9 km of shore in Haifa Bay. These included a clean site (Akko), a site polluted by a chemical PVC-polymer industry (Frutarom), and a site polluted with oil and waste from the petrochemical industry (Qiryat Yam). Metal analysis indicated site-dependent variations in levels of cadmium, lead, copper and mercury in the mussel soft tissues. Copper levels were similar in the bivalves collected from all the sites. Levels of mercury were significantly higher in specimens from the PVC-polluted site (Frutarom) while levels of cadmium were higher in Akko and Qiryat Yam compared to Frutarom. Lead residues were found only in Donax from Akko. The residual contents of mercury, copper and cadmium were relatively high in the young and noticeably low in Donax of medium body size. The main site of deposition of metals was in the soft tissues of the bivalve, but bioaccumulation of metals was also found in the shells. A marked increase in permeability of gills and mantle to the fluorescent anionic dye-fluorescein (FLU) was detected in Donax from Qiryat Yam and especially Frutarom, compared to the bivalves sampled from Akko. Multiple foci of enhanced permeability (multiple fluorescent spots) were detected in all the individuals sampled from Frutarom but none in the bivalve samples from Akko. Lysosomal accumulation of the metachromatic fluorescent cationic probe, acridine orange - (AO), was significantly decreased in the tissues of D. trunculus from polluted sites, especially polluted by the PVC factory. This decrease correlated with lysosomal enlargement and the formation of secondary lysosomes. D. trunculus appears to possess the most effective biochemical and physiological defense mechanisms enabling it to survive in habitats of polluted shallow waters, where other sand dwelling mollusc species were absent or found only in waters deeper then 2.5 m. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  3. Results of the Rumphius Biohistorical Expedition to Ambon : Part 6. Mollusca, Bivalvia, Pectinidae

    NARCIS (Netherlands)

    Dijkstra, H.H.

    1997-01-01

    During the Rumphius Biohistorical Expedition (1990) to Ambon 17 Pectinidae species were collected, nine of which were described by Rumphius (1705) and five illustrated by Rumphius. One species, viz. Decatopecten plica (Linnaeus, 1758), illustrated in Rumphius (1705: pl. 44, fig. O), has not been ref

  4. The sensorial structures of Spondylus americanus Hermann,1781 (Mollusca: Bivalvia, Spondylidae

    Directory of Open Access Journals (Sweden)

    Marina Gomes Viana

    2007-09-01

    Full Text Available Adult animals of Spondylus americanus were analyzed and specialized sensorial structures, the sensorial papillae and the eyes, were characterized. The sensorial papillae were projections on the edge of the mantle in form of light brown fingers which had function of percepting stimulus coming from the medium. They were constituted by loose conjunctive tissues with longitudinal muscular fibers and externally covered by ciliated cubic epithelium, which presented high amount of melanocytes that gave the coloration of the papillae. The eyes were more complex, being on small stalks histologically similar to the papillae. They exhibited a circular formate and had a metallic blue color. Theses structures were constituted by a corneo epithelium, cornea, lens, retina, basal stalk, periocular band and optical nerve. The eyes were distributed asymmetrically to both valves related with the sedentarism of the species. Right valve presented a smaller number of eyes when compared to left one.Foram examinados exemplares adultos de Spondylus. americanus Hermann, 1781 e estruturas especializadas na percepção de estímulos foram caracterizadas: as papilas sensoriais e os ocelos. As papilas sensoriais são projeções do bordo manto em forma de dedos de cor castanha e com a função de perceber estímulos vindo do meio, são constituídas por tecido conjuntivo frouxo contendo fibras musculares longitudinais e revestidas externamente por epitélio cúbico ciliado, o qual apresenta grande quantidade de melanócitos, que dão a coloração das papilas. Os ocelos são mais complexos, estando sobre pequenos pedúnculos histologicamente semelhante às papilas, têm formato circular e possui cor azul metálica. Constituí-se por um epitélio córneo, córnea, lente, retina, pedúnculo basal, banda periocular e nervo óptico. Os ocelos distribuem-se assimetricamente por ambas as valvas, o que está relacionado com o sedentarismo da espécie. A valva direita apresenta menor número de ocelos quando comparada a esquerda.

  5. Redescription of Hiatella meridionalis d'Orbigny, 1846 (Mollusca, Bivalvia, Hiatellidae from Argentina

    Directory of Open Access Journals (Sweden)

    Luiz Ricardo L. Simone

    2008-01-01

    Full Text Available The redescription of Hiatella meridionalis (d’Orbigny, 1846 is provided as first attempt to improve the systematics of the genus in the regions of Atlantic and western Pacific. This reanalysis is based on specimens collected in the vicinity of the type localities and is based on detailed morphology of samples that some researches consider a single, wide ranging species. From the morphological characters, the more interesting are: a high quantity of papillae at incurrent siphon; the retractor muscles of siphon divided in two bundles; the small size of the palps; the muscular ring in the stomach; and the zigzag fashion of the short intestinal loops. These characters distinguish the species from the other hiatellids so far examined. Type material of the species was examined, by first time illustrated, and the lectotype is designated.A redescrição de Hiatella meridionalis (d’Orbigny, 1846 é realizada como primeiro passo na melhoria da sistemática do gênero das regiões atlântica e pacífica oeste. Esta re-análise é baseada em espécimes coletados nas vizinhanças da localidade tipo e em morfologia detalhada de amostras que alguns pesquisadores consideram pertencer a uma única espécie de ampla distribuição. Dos caracteres anatômicos, os mais interessantes são: uma grande quantidade de papilas no sifão inalante; o músculo retrator dos sifões dividido em duas porções; o tamanho pequeno dos palpos; um anel muscular transversal no estomago; e um padrão em zigzag no curto intestino. Estes caracteres distinguem a espécie dos demais hiatelídeos até então examinados. Os sintipos da espécie foram também examinados e pela primeira vez ilustrados; o lectótipo é designado.

  6. De weekdieren van de Nederlandse brakwatergebieden (Mollusca)

    NARCIS (Netherlands)

    Kuijper, W.J.

    2000-01-01

    The molluscs of the brackish waters in the Netherlands (Mollusca) The Netherlands is a river delta rich in brackish waters. The organisms in these waters need to be adapted to extreme conditions, especially large fluctuations in chlorinity. However, several species occur optimally in this habitat. I

  7. The effect of temperature and body size on filtration rates of Limnoperna fortunei (Bivalvia, Mytilidae under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Débora Pestana

    2009-02-01

    Full Text Available The golden mussel (Limnoperna fortunei, Mollusca: Bivalvia is an invasive species that has been causing considerable environmental and economic problems in South America. In the present study, filtration rates of L. fortunei were determined in the laboratory under different temperatures (10, 15, 20, 25, 28, and 30 ºC and two types of food (Algamac-2000® and the chlorophycean alga Scenedesmus sp.. There was a statistically significant relationship between time and filtration rates in the experiment using Scenedesmus sp., regardless of temperature. However, this pattern was absent in the experiment using Algamac, suggesting that the relationship between filtration rates and temperature might depend on the size of the filtered particles. In addition, there was no correlation between filtration rates and either shell size or condition index (the relationship between the weight and the length of a mussel. The filtration rate measured in the present study (724.94 ml/h was one of the highest rates recorded among invasive bivalves to date. Given that the colonies of the golden mussel could reach hundreds of thousands of individuals per square meter, such filtration levels could severely impact the freshwater environments in its introduced range.

  8. Direct evidence for maternal inheritance of bacterial symbionts in small deep-sea clams (Bivalvia: Vesicomyidae)

    Science.gov (United States)

    Szafranski, Kamil M.; Gaudron, Sylvie M.; Duperron, Sébastien

    2014-05-01

    Bacterial symbiont transmission is a key step in the renewal of the symbiotic interaction at each host generation, and different modes of transmission can be distinguished. Vesicomyidae are chemosynthetic bivalves from reducing habitats that rely on symbiosis with sulfur-oxidizing bacteria, in which two studies suggesting vertical transmission of symbionts have been published, both limited by the imaging techniques used. Using fluorescence in situ hybridization and transmission electron microscopy, we demonstrate that bacterial symbionts of Isorropodon bigoti, a gonochoristic Vesicomyidae from the Guiness cold seep site, occur intracellularly within female gametes at all stages of gametogenesis from germ cells to mature oocytes and in early postlarval stage. Symbionts are completely absent from the male gonad and gametes. This study confirms the transovarial transmission of symbionts in Vesicomyidae and extends it to the smaller species for which no data were previously available.

  9. Molecular phylogeny of Pholadoidea Lamarck, 1809 supports a single origin for xylotrophy (wood feeding) and xylotrophic bacterial endosymbiosis in Bivalvia.

    Science.gov (United States)

    Distel, Daniel L; Amin, Mehwish; Burgoyne, Adam; Linton, Eric; Mamangkey, Gustaf; Morrill, Wendy; Nove, John; Wood, Nicole; Yang, Joyce

    2011-11-01

    The ability to consume wood as food (xylotrophy) is unusual among animals. In terrestrial environments, termites and other xylotrophic insects are the principle wood consumers while in marine environments wood-boring bivalves fulfill this role. However, the evolutionary origin of wood feeding in bivalves has remained largely unexplored. Here we provide data indicating that xylotrophy has arisen just once in Bivalvia in a single wood-feeding bivalve lineage that subsequently diversified into distinct shallow- and deep-water branches, both of which have been broadly successful in colonizing the world's oceans. These data also suggest that the appearance of this remarkable life habit was approximately coincident with the acquisition of bacterial endosymbionts. Here we generate a robust phylogeny for xylotrophic bivalves and related species based on sequences of small and large subunit nuclear rRNA genes. We then trace the distribution among the modern taxa of morphological characters and character states associated with xylotrophy and xylotrepesis (wood-boring) and use a parsimony-based method to infer their ancestral states. Based on these ancestral state reconstructions we propose a set of plausible hypotheses describing the evolution of symbiotic xylotrophy in Bivalvia. Within this context, we reinterpret one of the most remarkable progressions in bivalve evolution, the transformation of the "typical" myoid body plan to create a unique lineage of worm-like, tube-forming, wood-feeding clams. The well-supported phylogeny presented here is inconsistent with most taxonomic treatments for xylotrophic bivalves, indicating that the bivalve family Pholadidae and the subfamilies Teredininae and Bankiinae of the family Teredinidae are non-monophyletic, and that the principle traits used for their taxonomic diagnosis are phylogenetically misleading.

  10. ClamWin Free Antivirus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    ClamWin是在自由软件基金会(Free Software Foundation)支持下的一个杀毒软件开发项目。因此软件使用与传播均是免费的(当然传播要遵从GNL协议了)。杀毒软件的目前版本是0.88,实际上还处于较为初级的阶段,但查杀病毒这一主体功能是值得信赖的。软件没有采用添加到系统服务的自启动方式,这样做的一个好处是系统资源占用率极低,在监视状态下仅开启一个两、三兆大小的进程。软件杀毒时速度较慢,并且没有“加速”选项可设置。

  11. Response of the Asiatic clam, Corbicula manilensis, to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tilly, L.J.; Corey, J.C.; Bibler, N.E.

    1977-01-01

    When heat exchangers for reactors were plugged by the Asiatic clam, acute gamma radiation was considered as a possible control. Clams were collected and sorted by size; during irradiation the clams were submerged in natural water. Clams of both sizes survived large doses with no radiation damage evident in 30 days. Mortality rose steeply at doses of 2.4 x 10/sup 4/ Rad and above; smaller clams showed a greater resistance than large ones. The feasibility of using periodic exposure to gamma radiation as a means for controlling corbicula infestations is discussed. (HLW)

  12. First record of Corbicula fluminalis (Müller, 1774) in Lake Garda (Italy), living in sympatry with Corbicula fluminea (Müller, 1774)

    OpenAIRE

    Cappelletti, Cristina; Francesca CIUTTI

    2009-01-01

    The first record of Corbicula fluminalis (Müller, 1774) (Mollusca: Bivalvia: Veneroidea: Corbiculidae) in Lake Garda (Italy) is presented. This clam was observed in July 2008 along the lake shore, with a high number of shells; sampling of lake sediment revealed the presence of live specimens. C. fluminea (Müller, 1774) has already been recorded in Lake Garda since 2002. The need for further studies on the presence and the spread of the two clams and the biodiversity of the invertebrate commun...

  13. First record of Corbicula fluminalis (Müller, 1774 in Lake Garda (Italy, living in sympatry with Corbicula fluminea (Müller, 1774

    Directory of Open Access Journals (Sweden)

    Cristina CAPPELLETTI

    2009-02-01

    Full Text Available The first record of Corbicula fluminalis (Müller, 1774 (Mollusca: Bivalvia: Veneroidea: Corbiculidae in Lake Garda (Italy is presented. This clam was observed in July 2008 along the lake shore, with a high number of shells; sampling of lake sediment revealed the presence of live specimens. C. fluminea (Müller, 1774 has already been recorded in Lake Garda since 2002. The need for further studies on the presence and the spread of the two clams and the biodiversity of the invertebrate community of the lake is underlined, in relation to recent records of other invasive species, such as Dikerogammarus villosus (Sowinsky, 1894.

  14. Investigation of the Diversity of Mollusca and Evaluation of Water Quality in Hengyang Reach of Xiangjiang River%湘江衡阳段软体动物多样性调查和水质生物学评价

    Institute of Scientific and Technical Information of China (English)

    刘俊; 吴彦琼; 李静; 胡劲松; 李鹏; 刘运莲

    2011-01-01

    The species and diversity and faunal and distribution of molluscas in Hengyang reach of Xiangjiang River were studied after many years of dayuandu hydropower station built; and in virtue of diversity indexes of molluscas, water quality were evaluated. The result of the research showed that there were 45 species of mollusca in Hengyang reaches of Xiang River, which belong to 2 classes and 9 families and 18 genera. 30 species belonging to 11 genera in 6 families of Gastropoda were found, 15 specieses belonging to 7 genera in 3 families of Bivalvia were found. The mollusca was in Oriental realm. 26 species were endemic species in China, and Mekonia hunanensis was in endangered status (It has been listed in China Species Red List as an extinct species). Shannon index was used to evaluate water quality of Hengyang reaches of Xiang River. The result showed that the water quality in Dongzhou ialand and Hengshan county town belonged to clean water, the other 8 sampling sites water had been polluted slightly.%对衡山大源渡电站蓄水多年后的湘江衡阳段软体动物的种类组成、区系分布以及多样性进行了调查,并用生物多样性指数对湘江衡阳段水质进行了评价.调查结果表明,湘江衡阳段计有软体动物45种,分别隶属于2纲9科18属,其中腹足纲6科11属30种,双壳纲3科7属15种,其区系成分主要为东洋界类型;其中26种为中国特有种,且湖南湄公螺为濒危物种(被定为灭绝的物种).用软体动物的Shannon-Wiener多样性指数(H')对湘江衡阳段进行水质生物学评价,研究结果表明,湘江衡阳段的水质除东洲岛和衡山县城为清洁水外,其余8个采样点的水质均受到了轻度污染.

  15. The interference of methods in the collection of teredinids (Mollusca, Bivalvia in mangrove habitats Interferência de métodos na coleta de teredinídios (Mollusca, Bivalvia em habitats de manguezais

    Directory of Open Access Journals (Sweden)

    Rosa M. V. Leonel

    2006-03-01

    Full Text Available In the estuary of the Mamanguape River (Paraíba, Brazil, a new collection technique was developed and applied with virgin poles of mangrove trees Avicennia schaueriana (Verbenaceae, Rhizophora mangle (Rhizophoraceae, and Laguncularia racemosa (Combretaceae, taking into account wood preference, water salinity and depth influence during teredinid larval settlement. Sets of poles were vertically fixed in the riverbed at three sites along a decreasing salinity gradient, where they stayed for four months. The poles were collected and divided into upper, median, and lower segments, in agreement with different immersion regimes. An increase of 239% was obtained in the number of individuals when compared to a previous study in the same area using a different methodology. The species Teredo bartschi (Clapp, 1923, Nausitora fusticula (Jeffreys, 1860 and Bankia fimbriatula Moll & Roch, 1931 were registered in both studies, and the species Psiloteredo healdi (Bartsch, 1931 is here registered for the first time as occurring in that estuary. The species Neoteredo reynei (Bartsch, 1920, previously registered on tree branches of the mangrove habitat, was not found in the present work. Bankia fimbriatula, the most abundant species, did not show preference for any substratum but occurred significantly on the lower segment of the poles. N. fusticula, second in abundance, preferred to settle on poles of A. schaueriana and on any of the three segments. Aiming to assess the habitat variations, a more accurate study on teredinids diversity in mangrove ecosystems should be performed through a concomitant analysis from tree branches of the mangrove habitat, as well as from poles of mangrove trees or panels made of pine wood or mangrove trees wood. These collection devices should be maintained along a decreasing salinity gradient exposed to different tide levels.Contemplando a preferência pelo tipo de madeira, a influência da profundidade e da salinidade durante assentamento larval de teredinídeos, uma nova técnica de coleta foi aplicada e desenvolvida no estuário do rio Mamanguape (Paraíba, Brasil, utilizando varas virgens de três espécies de árvores do manguezal: Avicennia schaueriana (Verbenaceae, Rhizophora mangle (Rhizophoraceae e Laguncularia racemosa (Combretaceae. Em três estações demarcadas ao longo do gradiente decrescente de salinidade, conjuntos de varas foram verticalmente fixados nas margens do rio. Após quatro meses, as varas eram coletadas e divididas em três segmentos (superior, médio e inferior, de acordo com os regimes de imersão a que foram submetidas. Comparativamente aos dados obtidos por um estudo anterior na mesma área, com outras metodologias de coleta, foi obtido um aumento de 239% no número de indivíduos coletados com a nova técnica. Embora as espécies Teredo bartschi (Clapp, 1923, Nausitora fusticula (Jeffreys, 1860 e Bankia fimbriatula Moll & Roch, 1931 tenham ocorrido nos dois estudos, o teredinídeo Psiloteredo healdi (Bartsch, 1931 tem sua presença registrada pela primeira vez neste estuário. Tendo sido previamente registrada em ramos de árvores do manguezal, Neoteredo reynei (Bartsch, 1920 não foi coletada no presente trabalho. Sendo a espécie mais abundante, B. fimbriatula não mostrou preferência de assentamento em nenhum dos substratos, ocorrendo significativamente associada ao segmento inferior das varas. Como segunda espécie mais abundante, N. fusticula mostrou preferência significativa de assentamento em A. schaueriana, ocorrendo indistintamente nos três segmentos das varas. Visando contemplar as variações do habitat e obter maior precisão de resultados, é recomendável que em estudos sobre a diversidade de teredinídeos, sejam incluídas análises concomitantes de troncos e ramos das árvores, com o uso de varas de árvores do manguezal ou de coletores artificiais feitos com pinho ou madeira de árvores do manguezal. Os coletores devem ser mantidos ao longo do gradiente de salinidade e expostos aos diferentes níveis das marés.

  16. Gloquídio de Diplodon martensi (lhering (Mollusca, Bivalvia, Hyriidae e seu ciclo parasitário The glochidium of Diplodon martensi (lhering (Mollusca, Bivalvia, Hyriidae and its parasitic cycle

    Directory of Open Access Journals (Sweden)

    Maria Cristina Dreher Mansur

    1999-01-01

    Full Text Available Conchological and anatomical studies of the glochidium of Diplodon martensi (lhering, 1893 were performed on samples collected in a small river, tributary from the Caí River, that belong to the Jacuí River sub-basin in south-eastern Brazil. The parasitic development of the glochidium was observed in laboratory on a small cichlid fish Gymnogeophagus gymnogenys (Hensel, 1870.

  17. Biomonitoring study of an estuarine coastal ecosystem, the Sacca di Goro lagoon, using Ruditapes philippinarum (Mollusca: Bivalvia)

    International Nuclear Information System (INIS)

    Coastal lagoons are constantly subjected to releases of chemical pollutants, and so organisms may be exposed to such toxicants. This study investigated through a multivariate approach the physiological status of bivalve Ruditapes philippinarum, farmed in Sacca di Goro lagoon. Biomarkers at different levels of biological organization (catalase, superoxide dismutase, genotoxicity, reburrowing behavior) were evaluated at three sites exposed to different environmental conditions. A seasonal trend was observed, and micronucleus frequency was significantly lowest at the relatively pristine reference site. Enzymatic activity toward oxyradicals be quite efficient since variations in responsiveness were not consistent. However, behavioral impairment was observed in reburrowing rates. Sediment concentrations showed low PAH levels and high natural levels of trace metals Cr and Ni. DistLM statistical analysis revealed a non-significant relationship between selected biomarkers and xenobiotics. Therefore other potentially toxic compounds in admixture at low doses may be involved in driving differing spatial distribution of physiological impairment. -- Highlights: ► Health status assessment of bivalve Ruditapes philippinarum, from lagoon of Sacca di Goro. ► Multiparametric approach (chemical analysis, biochemical and behavioral biomarkers). ► Impairments of burrowing kinetics in the contaminated site. ► Micronucleus genotoxicity test to detect effects of contaminants complex mixture. ► Multiple stress of chemicals in estuarine costal ecosystem. -- The bivalve Ruditapes philippinarum as a bioindicator in monitoring pollution of estuaries

  18. New lucinid bivalves from shallow and deeper water of the Indian and West Pacific Oceans (Mollusca, Bivalvia, Lucinidae

    Directory of Open Access Journals (Sweden)

    John Taylor

    2013-08-01

    Full Text Available Four new species and a new genus of lucinid bivalves are described from shallow and deeper waters in the Indian and West Pacific Oceans. The new genus Scabrilucina (subfamily Lucininae includes the little-known S. victorialis (Melvill, 1899 from the Arabian Sea and S. vitrea (Deshayes, 1844 from the Andaman Sea as well as a new species S. melvilli from the Torres Strait off northeastern Australia. Ferrocina brunei new species (Lucininae was recovered from 60 m near oil drilling activities off Borneo; its anatomy confirmed the presence of symbiotic bacteria. Two unusual deeper water species of Leucosphaerinae are described, both species included in on-going molecular analyses; Gonimyrtea ferruginea from 400–650 m in the southwest Pacific and Myrtina reflexa from 200–825 m off Zanzibar and Madagascar.

  19. Anatomy and systematics of Anodontites Elongatus (Swainson from Amazon and Parana Basins, Brazil (Mollusca, Bivalvia, Unionoida, Mycetopodidae

    Directory of Open Access Journals (Sweden)

    Luiz Ricardo L Simone

    1997-12-01

    Full Text Available The anatomy of Anodontiies elongatus (Swainson, 1823, a rare species restricted to the Amazon and Parana Basins, is described by first time, showing a group of conchological and anatomical characters exclusive of this species that may be analyzed to identify it. Diagnosis of A. elongatus: shell long antero-posteriorly, umbones prominent, periostracum opaque and smooth, two posterior radial striae; middle fold of mantle edge veiy tall; gill long antero-posteriorly and short dorso-ventrally, extending about a half of it total length beyond visceral mass; palps proportionally small, several furrows in its outer surface; stomach without esophageal transversal ridjp, dorsal hood and gastric shield poorly developed, major typhlosole entering in ddd , posterior pouch of sa³ very-long; style sac reduced, without crystalline style; distal region of intestine and rectum with a well developed typhlosole, "T" in section, other intestinal regions without folds; gonad gonochoristic.

  20. Immunochemical localization of ribulose-1,5-bisphosphate carboxylase in the symbiont-containing gills of Solemya velum (Bivalvia : Mollusca)

    NARCIS (Netherlands)

    Cavanaugh, Colleen M.; Abbott, Marilyn S.; Veenhuis, Marten

    1988-01-01

    The distribution of the Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase (RbuP2Case; EC 4.1.1.39) was examined by using two immunological methods in tissues of Solemya velum, an Atlantic coast bivalve containing putative chemoautotrophic symbionts. Antibodies elicited by the purified large

  1. A preliminary study for establishing Perna viridis (Mollusca:Bivalvia) as a biological monitor for pollution in Karachi coastal water

    OpenAIRE

    Zehra, Itrat; Naz, Huma; Naqvi, Iftikhar Imam

    1996-01-01

    Adverse effects of toxic substances on the environmental quality have become a subject of concern in recent years. Toxicity of heavy metals has never been in dispute and therefore their presence in our natural environment is undesirable. This study was undertaken to establish the capability of Perna viridis as a monitor for pollution in the Manora channel. Accumulation of Zinc, Copper, Iron and Manganese by marine mussels, sampled from Manora channel, was determined. Metal load varied markedl...

  2. Mytilus antiquorum J. Sowerby, 1821 and other Pliocene mussels (Mollusca, Bivalvia) from the Southern North Sea Basin

    NARCIS (Netherlands)

    Vervoenen, M.; Wesselingh, F.P.; Nieulande, van F.A.D.

    2000-01-01

    Mytilus antiquorum J. Sowerby, 1821, is recorded from the Coralline Crag Formation of East Anglia (UK) and the Lillo Formation (Oorderen, Kruisschans and Merksem members) of the Antwerp area (Belgium). The species is diagnosed on the basis of newly collected material and differentiated from modern E

  3. Mytilus antiquorum J. Sowerby, 1821 and other Pliocene mussels (Mollusca, Bivalvia) from the Southern North Sea Basin

    OpenAIRE

    Vervoenen, M.; Wesselingh, F.P.; Nieulande, van, F.A.D.

    2000-01-01

    Mytilus antiquorum J. Sowerby, 1821, is recorded from the Coralline Crag Formation of East Anglia (UK) and the Lillo Formation (Oorderen, Kruisschans and Merksem members) of the Antwerp area (Belgium). The species is diagnosed on the basis of newly collected material and differentiated from modern European mussel species. The presence of M. antiquorum in the southern North Sea Basin is restricted to the Middle (Piacenzian) and early Late Pliocene (Gelasian). A possible occurrence of the speci...

  4. First molecular phylogeny of the circumtropical bivalve family Pinnidae (Mollusca, Bivalvia): evidence for high levels of cryptic species diversity.

    Science.gov (United States)

    Lemer, Sarah; Buge, Barbara; Bemis, Amanda; Giribet, Gonzalo

    2014-06-01

    The family Pinnidae Leach, 1819, includes approximately 50 species of large subtidal and coastal marine bivalves. These commercially important species occur in tropical and temperate waters around the world and are most frequently found in seagrass meadows. The taxonomy of the family has been revised a number of times since the early 20th Century, the most recent revision recognizing 55 species distributed in three genera: Pinna, Atrina and Streptopinna, the latter being monotypic. However, to date no phylogenetic analysis of the family has been conducted using morphological or molecular data. The present study analyzed 306 pinnid specimens from around the world, comprising the three described genera and ca. 25 morphospecies. We sequenced the mitochondrial genes 16S rRNA and cytochrome c oxidase subunit I, and the nuclear ribosomal genes 18S rRNA and 28S rRNA. Phylogenetic analysis of the data revealed monophyly of the genus Atrina but also that the genus Streptopinna is nested within Pinna. Based on the strong support for this relationship we propose a new status for Streptopinna Martens, 1880 and treat it as a subgenus (status nov.) of Pinna Linnaeus, 1758. The phylogeny and the species delimitation analyses suggest the presence of cryptic species in many morphospecies displaying a wide Indo-Pacific distribution, including Pinna muricata, Atrina assimilis, A. exusta and P. (Streptopinna) saccata but also in the Atlantic species A. rigida. Altogether our results highlight the challenges associated with morphological identifications in Pinnidae due to the presence of both phenotypic plasticity and morphological stasis and reveal that many pinnid species are not as widely distributed as previously thought.

  5. Multi-locus fossil-calibrated phylogeny, biogeography and a subgeneric revision of the Margaritiferidae (Mollusca: Bivalvia: Unionoida).

    Science.gov (United States)

    Bolotov, Ivan N; Vikhrev, Ilya V; Bespalaya, Yulia V; Gofarov, Mikhail Y; Kondakov, Alexander V; Konopleva, Ekaterina S; Bolotov, Nikita N; Lyubas, Artyom A

    2016-10-01

    The taxonomy and biogeographic history of the bivalve family Margaritiferidae are controversial because previous molecular studies did not provide a well-resolved phylogenetic framework for these enigmatic freshwater mussels that have extensive but disjunct distribution in North America, Eurasia and North Africa. In this study, we present a new, fossil-calibrated phylogenetic hypothesis based on five molecular markers (∼4kb of total length) for ten species. Our results indicate that all recent margaritiferids are in the single genus, Margaritifera Schumacher, 1816. Additionally, we identified three relatively well-supported phylogenetic clades that are valid subgenera, i.e., Margaritifera s. str. (Holarctic), Margaritanopsis (=Cumberlandia) (southeast North America-southeast Asia disjunct) and Pseudunio (Mediterranean). We suggest that the crown lineage of the Margaritiferidae most likely originated in the Cretaceous (mean age 93Ma, 95% CI 66-126Ma). The combined results of ancestral area reconstructions based on the three different approaches (S-DIVA, DEC and S-DEC) showed that ancient vicariance events could have played an important role in speciation within the family. The rates of mitochondrial evolution of margaritiferids are notably slow, which may be associated with their longevity, long generation time and low metabolic rates. Our findings highlight the complex biogeographic history of the Margaritiferidae as an intermixing of ancient vicariance and dispersal events, which were most likely associated with some inland barriers, continental movements and a sea level dynamic.

  6. Where’s Waldo? A new commensal species, Waldo arthuri (Mollusca, Bivalvia, Galeommatidae), from the Northeastern Pacific Ocean

    OpenAIRE

    Paul Valentich-Scott; Diarmaid O'Foighil; Jingchun Li

    2013-01-01

    Abstract A galeommatid bivalve mollusk, representing a new species, is described from off the coasts of California and Vancouver Island, British Columbia. The new bivalve has a commensal relationship with the heart urchin, Brisaster latifrons . It has been observed crawling between the oral spines of this urchin, frequently near the peristome. The bivalve has been recorded from 80 (Vancouver Island) to 444 (southern California) meters depth, in muddy sediments. In common with other galeommato...

  7. Bivalvia (Mollusca) of Nansha Islands, China%中国南沙群岛的双壳纲贝类

    Institute of Scientific and Technical Information of China (English)

    蔡英亚; 刘桂茂

    2004-01-01

    报道了中国南沙群岛的双壳纲贝类141种,分隶于5亚纲8目36科77属.从种类的组成中,帘蛤科有18种,蚶科15种,扇贝科11种,鸟蛤科10种,锉蛤科8种,贻贝科、海菊蛤科和樱蛤科各7种,砗磲科6种,其他各科的种类均在5种以内.按种的性质而论,大多数属于和珊瑚礁有密切联系的热带种或亚热带种,区系性质为印度-西太平洋区的印尼-马来亚区.

  8. 栉江珧生殖细胞的发生%Gametogenesis in Atria pectinata Linnaeus (Mollusca, Bivalvia)

    Institute of Scientific and Technical Information of China (English)

    王梅芳; 余祥勇; 王如才

    2000-01-01

    通过观察栉江珧(Atrina pectinata linnaeus)的未分化生殖细胞,精原细胞和卵原细胞,精母细胞和卵母细胞,精子和卵子的形态结构与分布状况及核仁在卵成熟过程中的变化,对栉江珧生殖细胞发生及成熟过程的有关问题进行了探讨.

  9. Recrutamento larval e crescimento de teredinidae (mollusca-bivalvia em região entremarés de manguezais

    Directory of Open Access Journals (Sweden)

    Sônia Godoy Bueno Carvalho Lopes

    1997-01-01

    Full Text Available O recrutamento larval e o crescimento de Teredinidae na região entremarés do manguezal da Praia Dura, Ubatuba, SP, foi acompanhado durante doze meses (08/84 a 08/85 utilizando coletores construídos com madeira de mangue. O tempo decorrido para se detectar a presença dos primeiros Teredinidae foi de aproximadamente sete meses após o início do experimento e o número de indivíduos por coletor foi muito reduzido no período de amostragem. Esses resultados contrastam com os obtidos por outros autores que instalaram coletores em ambiente marinho, mas são semelhantes aos obtidos por autores que instalaram coletores em regiões estuarinas do litoral brasileiro. Essas diferenças nos resultados talvez possam ser explicadas pelo fato da salinidade ser mais baixa e mais variável nos estuários que no ambiente marinho. A análise dos dados sobre o recrutamento larval, permite concluir que a espécie mais abundante foi Nausitora fustieula (Jeffreys, 1860, com principal época de instalação em março e taxa inicial de crescimento de 1,86 mm/day. As outras espécies de Teredinidae, Bankiaflmbriatula Moll & Roch, 1931, Bankia roehi Moll, 1931 e Neoteredo reynei (Bartsch, 1920, apresentaram pequeno número de indivíduos e em função disso, não foi possível determinar suas épocas de instalação e respectivas taxas de crescimento.The larval settlement and growth of Teredinidae in the intertidal region of the Praia Dura mangrove, Ubatuba, SP, were undertaken during one year (08/84 to 08/85 using colectors made from mangrove wood. The presence of the first Teredinidae was detected approximately seven month after the inicial experiment and the number of specimens per coletor was small during the sampling period. These results contrast with those obtained by other authors working in a marine environment, but are similar to those obtained in experiments developed in Brazilian estuaries. The differences between data obtained in marine and estuarine environments, might be explained by the lower and more variable salinity gradient in estuaries. Larval settlement data revealed that the most abundant species was Nausitora fustieula (Jeffreys,1860, which settles on wood prefrerably in March, and has an initial growth rate of 1.86 mm/day. The other Teredinidae species Banida fimbriatula Moll & Roch, 1931, Bankia rochi Moll, 1931 and Neoteredo reynei (Bartsch, 1920, occurred in a very small number of specimens and therefore, their time of settlement and growth rates could not be determined.

  10. Isolation and Characterization of the First Microsatellite Markers for the Endangered Relict Mussel Hypanis colorata (Mollusca: Bivalvia: Cardiidae

    Directory of Open Access Journals (Sweden)

    Luis Ovidiu Popa

    2011-01-01

    Full Text Available Hypanis colorata (Eichwald, 1829 (Cardiidae: Lymnocardiinae is a bivalve relict species with a Ponto-Caspian distribution and is under strict protection in Romania, according to national regulations. While the species is depressed in the western Black Sea lagoons from Romania and Ukraine, it is also a successful invader in the middle Dniepr and Volga regions. Establishing a conservation strategy for this species or studying its invasion process requires knowledge about the genetic structure of the species populations. We have isolated and characterized nine polymorphic microsatellite markers in H. colorata. The number of alleles per locus ranged from 4 to 28 and the observed heterozygosity ranged from 0.613 to 1.000. The microsatellites developed in the present study are highly polymorphic and they should be useful for the assessment of genetic variation within this species.

  11. The Effects of Mercury Exposure on the Surface Morphology of Gill Filaments in Perna perna (Mollusca: Bivalvia)

    Energy Technology Data Exchange (ETDEWEB)

    Gregory, M.A.; George, R.C.; Marshall, D.J.; Anandraj, A.; McClurg, T.P

    1999-01-01

    This study investigated the possibility that changes in the surface morphology of mussel (Perna perna) gill filaments may be used to indicate the relative toxicity of pollutants in the marine environment. Healthy, adult P. perna were collected and immersed in 2 free-flow tanks. Mercury was added to seawater as it entered tank 1 to achieve a constant level of 50 {mu}g/l{sup -1} over 24 days. Uncontaminated seawater was circulated over the mussels in tank 2 (control) for the same period. A 25 mm{sup 2} area of gill filament was removed from each of the 5 specimens before and after 24 days immersion in tank 2, and after immersion for 1, 2, 4, 8, 16 and 24 days in tank 1. These were examined using a scanning electron microscope. The remaining soft tissues from each animal were analysed for mercury using an atomic absorption spectrometer. Mercury concentration increased from 0.13 (pre-immersion) to 87 {mu}g/g after day 24. Surface morphology remained normal for all animals in tank 2 and for those exposed to Hg for up to 8 days. However, from 16 to 24 days exposure there was a gradual increase in the diameters of microvilli, a depletion of abfrontal cilia, an increase in abnormal, perhaps necrotic cells and an unusual increase in the number of cilia on the lateral surfaces. These results confirm that P. perna is an efficient bio-accumulator and suggest that their gill pathomorphology may be a useful indicator of toxicity.

  12. Relationship between element concentrations and body size in the Lake Maggiore population of Unio pictorum mancus (Mollusca, Bivalvia

    Directory of Open Access Journals (Sweden)

    Ilenia CATTANI

    2011-08-01

    Full Text Available The study focused on using a fresh-water mussel (Unio pictorum mancus as a bioindicator of various pollutants, and particularly metals. The elements considered were: Al, As, Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn. This research was carried out at a site where various other studies have been conducted on important characteristics of the same population of Unio. This site is a small bay called "Sabbie d’Oro" located on the south-east coast of Lake Maggiore. Our study involved quantifying the capacity of this mollusc to concentrate large amounts of metal in its body without evident consequences by using detoxification mechanisms. We analysed not only element concentrations, but also their variability (expressed as CV% in the soft tissues and in the shell, for two main reasons: i the sampling design should include a preliminary analysis to determine how many specimens is necessary collect to ensure a specified level of precision; ii the sample variability value may be combined with the value of analytical precision (BCR to obtain an estimate of the "experimental" precision. In soft tissue, Ca accumulation tended to increase with size, and Al accumulation decreased with size. In shell, Ca and Ni were stored more than in soft tissue, but not proportionally to size. V, Cr and Mo tended to accumulate in the shell progressively over the years, whereas Co and Al are "diluted" during growth, or are absorbed mainly during the juvenile stage. Partition between shell and soft tissue resulted roughly the same in the juvenile and adult stages for the following elements: Fe, Al, Co, As, Pb. The relationships among the various elements were schematized in a hierarchical tree plot.

  13. Comparative studies on the histology and ultrastructure of the siphons of two species of Tellinidae (Mollusca: Bivalvia from Brazil

    Directory of Open Access Journals (Sweden)

    João E.V.V. Vitonis

    2012-06-01

    Full Text Available Despite the great importance of the siphons for infaunal bivalves, only a few studies have examined their tissues using histology techniques or scanning electron microscopy. In the present study, the siphons of Tellina lineata Turton, 1819 and Macoma biota Arruda & Domaneschi, 2005 were investigated. The siphon walls are composed by a series of muscle sheets of longitudinal ("L", circular ("C" and radial ("R" fibers, with a clear pattern common to both species: there is a main median longitudinal layer (Lm, and two peripheral circular layers, one inner (Ci and one outer (Co, near the epithelia. A median circular layer (Cm separates an internal (Lmi from an outer (Lmo median longitudinal layer. Further, the Co is split by a thin outer longitudinal layer (Lo, forming Coi and Coo layers, the former being obliquely oriented. Thin radial fibers (R delimit clear packages of Lmi and Lmo fibers. In each siphon, there are six longitudinal nerve cords, running within the Lmi layer, adjacent to the Cm. The inhalant and exhalant siphons of M. biota are very similar in structure, but the Lmo of the exhalant siphon is almost twice as thick as its Lmi, while in the inhalant siphon these layers have similar thicknesses; the Coi is very thick, especially in the exhalant siphon. The inhalant siphon of T. lineata is very similar to that of M. biota, differing only with respect to the thickness of the Coi, which in the former species is not as well developed as in the latter. The Lmo of the exhalant siphon of T. lineata is by far the most developed layer, with the Lmi represented only by uniseriate small cells; in the vicinities of the nerve cords, the Cm is split in two layers. The epithelia of both siphons of M. biota and T. lineata bear ciliated receptors, which were difficult to observe as they were frequently covered with mucus. It was possible to observe that cilia are present in both species, differing in length and in the number per receptor between the inhalant and exhalant siphons, and between the species. Detailed comparisons among the siphons of M. biota and T. lineata and other bivalve species are very difficult, because of at least two reasons. First, each investigator has used different methods to prepare and observe the siphons through histological sections; and second, different nomenclatural schemes are used to describe the musculature of the siphons, causing confusion when the same layers are compared among different species. In order to unify the nomenclature of tissue layers of the bivalve siphons, we now propose a scheme to name these layers based on topological homology.

  14. New records and a new species of bivalve (Mollusca: Bivalvia) from Miocene hydrocarbon seep deposits, North Island, New Zealand.

    Science.gov (United States)

    Saether, Kristian P; Jingeng, Sha; Little, Crispin T S; Campbell, Kathleen A

    2016-01-01

    Fourteen bivalve taxa belonging to 11 families are present in at least 13 early to middle Miocene hydrocarbon seep deposits in the East Coast Basin, North Island, New Zealand. Among these are at least three new species, one of which, Semeloidea (s. l.) bexhavenensis sp. nov. (Lasaeidae), is described here. New distribution data are recorded for bivalve species in the families Limidae, Propeamussiidae, Malleidae and Solemyidae. Additional morphological details of Gigantidas coseli (Mytilidae) and Pratulum quinarium (Cardiidae) are provided based upon previously unrecorded internal shell features. Palaeoecological analysis indicates that bivalves utilized a broad range of modes of life and niches within the New Zealand Miocene seep environment, and no more than ca. 30% of these bivalve species were likely to have been obligate to seeps. PMID:27615822

  15. A new genus and species of Thyasiridae (Mollusca, Bivalvia from deep-water, Beaufort Sea, northern Alaska

    Directory of Open Access Journals (Sweden)

    Paul Valentich-Scott

    2014-12-01

    Full Text Available Bivalve mollusk shells were collected in 2350 m depth in the Beaufort Sea, Arctic Ocean off northern Alaska. Initial identification suggested the specimens were a member of the bivalve family Thyasiridae, but no known eastern Pacific or Arctic living or fossil thyasirid resembled these deep-water specimens. Comparisons were made with the type of the genera Maorithyas Fleming, 1950, Spinaxinus Oliver & Holmes, 2006, Axinus Sowerby, 1821, and Parathyasira Iredale, 1930. We determined the Beaufort Sea species represents a new genus, herein described as Wallerconcha. These specimens also represent a new species, herein named Wallerconcha sarae. These new taxa are compared with known modern and fossil genera and species of thyasirds.

  16. Cytogenetic characterisation of the razor shells Ensis directus (Conrad, 1843) and E. minor (Chenu, 1843) (Mollusca: Bivalvia)

    Science.gov (United States)

    González-Tizón, Ana M.; Rojo, Verónica; Vierna, Joaquín; Jensen, K. Thomas; Egea, Emilie; Martínez-Lage, Andrés

    2013-03-01

    The European razor shell Ensis minor (Chenu 1843) and the American E. directus (Conrad 1843) have a diploid chromosome number of 38 and remarkable differences in their karyotypes: E. minor has four metacentric, one metacentric-submetacentric, five submetacentric, one subtelocentric and eight telocentric chromosome pairs, whereas E. directus has three metacentric, two metacentric-submetacentric, six submetacentric, six subtelocentric and two telocentric pairs. Fluorescent in situ hybridisation (FISH) using a major ribosomal DNA probe located the major ribosomal genes on one submetacentric chromosome pair in both species; FISH with a 5S ribosomal DNA (5S rDNA) probe rendered one chromosomal (weak) signal for E. minor and no signal for E. directus, supporting a more dispersed organisation of 5S rDNA compared to the major ribosomal genes. The vertebrate telomeric sequence (TTAGGG) n was located on both ends of each chromosome, and no interstitial signals were detected. In this work, a comparative karyological analysis was also performed between the four Ensis species analysed revealing that the three European species studied so far, namely E. minor, E. siliqua (Linné 1758) and E. magnus Schumacher 1817 show more similarities among them than compared to the American species E. directus. In addition, clear karyotype differences were found between the morphologically similar species E. minor and E. siliqua.

  17. Analysis of Hongdao Clam Industrial Structure Based on Industry Chain

    Institute of Scientific and Technical Information of China (English)

    Jiang; Xianqiong

    2014-01-01

    The vertical and transverse structures of Hongdao clam industry are described and analyzed objectively based on the perspective of industry chain. On the basis of field investigation,the key nodes of Hongdao clam industry chain,including nursery,breeding,processing,transportation and sale,are analyzed. It can be concluded that the development of clam industry chain is unbalanced,especially the deep-processing capacity is not strong,and the development of supporting industy lags behind. The horizontal industry chain of clam needs to be further improved. The corresponding suggestions are put forward: strengthening research on new nursery technology in later period,further extending the horizontal industry chain of clam,mining the depth of clam-related leisure industry,and upgrading service level of leisure travel.

  18. Overwinteringsgedrag van de nauwe korfslak Vertigo angustior (Mollusca)

    NARCIS (Netherlands)

    Boesveld, A.

    2005-01-01

    Overwintering habits of the land snail Vertigo angustior (Mollusca) During a mollusc survey in 2004 en 2005 in the province of Zuid-Holland special attention was paid to Vertigo angustior. The species was observed overwintering in large groups, up to hundreds of specimens together, between mosses (e

  19. De nauwe korfslak Vertigo angustior in Nederland (Mollusca: Gastropoda)

    NARCIS (Netherlands)

    Bruyne, de R.

    2002-01-01

    The narrow whorlsnail Vertigo angustior in the Netherlands (Mollusca: Gastropoda) In June and July 2001, a special survey was held in several coastal areas in the province of Zuid- Holland, the Netherlands. The main objective was retrieving additional data on the occurrence of Vertigo angustior Jeff

  20. The Pacific clam Nutricola tantilla (Bivalvia:Veneridae) has separate sexes and makes use of brood protection and sperm storage

    DEFF Research Database (Denmark)

    Lützen, Jørgen; Jespersen, Åse; Russell, Michael P.

    2015-01-01

    Et morfologisk studie af en NW Amerikansk blødbunds-musling Nutricola tantilla viste at den er særkønnet og ikke, som tidligere rapporteret, protandrisk hermafrodit. Vi baserer denne konklusion på at små hanner har højt specialiserede kirtelholdige spermiodukter, mens større hunner har simple ovi...

  1. The Early Development of the Short-Necked Clam, Paphia undulata (Born 1778 (Mollusca, Pelecypoda: Veneridae in the Laboratory

    Directory of Open Access Journals (Sweden)

    Annabelle del Norte Campos

    2010-12-01

    Full Text Available The population of Paphia undulata in Negros Occidental waters continues to decline due to unregulated harvesting because of the increasing demand for this resource. One potential effort to mitigate this problem is reseeding or stock enhancement of the natural population. For these efforts to be effective however, successful laboratory rearing and breeding of this species is a prerequisite. Thus, this study was conducted to describe the embryonic and larval development of P. undulata to provide information on laboratory larval rearing. Broodstock were collected during the natural spawning peak from Hinigaran, Negros Occidental and were maintained in a static system with a mean salinity and temperature of 36 ppt. and 26.7 OC, respectively and were fed with Isochrysis galbana, Chaetoceros calcitrans, and Tetraselmis tetrahele. Fertilized eggs started to divide 30 minutes after fertilization. Ciliated swimming blastulas were observed after 1.5 hours with an average shell length (SL of 40 µm. These further developed into trocophore larvae (average SL 60µm after 7 hours and into D-veliger (average SL 80 µm after 12 hours. Fully developed D-larvae (average SL 90 µm were attained after 17 hours. Larvae with completely developed umbo were observed on day 9 with an average SL of 140 µm. On day 13, larvae (average SL 220 µm started to settle and metamorphose. Spontaneous spawning was observed during the peak of reproductive activities of P. undulata showing that collection of broodstock must be conducted during the peak of reproductive season to ensure successful spawning and production of viable gametes under laboratory conditions. Further experiments should be conducted to determine optimum conditions to improve survival rates of the larvae during settlement. The results corroborate other studies and help explain the derived information on the species' population and reproductive biology.

  2. Manila clam Venerupis philippinarum as a biomonitor to metal pollution

    Institute of Scientific and Technical Information of China (English)

    WU Huifeng; JI Chenglong; WANG Qing; LIU Xiaoli; ZHAO Jianmin; FENG Jianghua

    2013-01-01

    The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology.Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however,little attention has been paid to potential biological differences between these two pedigrees.In this study,we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology.Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities.In addition,we found that hypotaurine,malonate and homarine were relatively high in white clam gills,while alanine,arginine,glutamate,succinate,4-aminobutyrate,taurine and betaine were high in zebra clam gills.Zebra clam gills were also more sensitive to a mixture of Cd and Zn,as shown by antioxidant enzyme activities and metabolic profiles,but white clam gills could accumulate more Zn.Therefore,we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution,whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.

  3. Razor clam to RoboClam: burrowing drag reduction mechanisms and their robotic adaptation

    International Nuclear Information System (INIS)

    Estimates based on the strength, size, and shape of the Atlantic razor clam (Ensis directus) indicate that the animal's burrow depth should be physically limited to a few centimeters; yet razor clams can dig as deep as 70 cm. By measuring soil deformations around burrowing E. directus, we have found the animal reduces drag by contracting its valves to initially fail, and then fluidize, the surrounding substrate. The characteristic contraction time to achieve fluidization can be calculated directly from soil properties. The geometry of the fluidized zone is dictated by two commonly-measured geotechnical parameters: coefficient of lateral earth pressure and friction angle. Calculations using full ranges for both parameters indicate that the fluidized zone is a local effect, occurring between 1–5 body radii away from the animal. The energy associated with motion through fluidized substrate—characterized by a depth-independent density and viscosity—scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For E. directus, this translates to a 10X reduction in the energy required to reach observed burrow depths. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce energy costs associated with digging. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to find optimal digging kinematics, RoboClam has achieved localized fluidization burrowing performance comparable to that of the animal, with a linear energy-depth relationship, in both idealized granular glass beads and E. directus' native cohesive mudflat habitat. (paper)

  4. Types of Cenozoic Mollusca from Java in the Martin Collection of Naturalis

    NARCIS (Netherlands)

    Leloux, J.; Wesselingh, F.P.

    2009-01-01

    An updated type catalogue of the Martin Collection (fossil Mollusca, predominantly from the Cenozoic of Java, Indonesia) is presented. Type specimen data, updated locality data, and illustrations are given.

  5. Land snails (Mollusca: Gastropoda) of India: status, threats and conservation strategies

    OpenAIRE

    Sen, S.; Ravikanth, G; N.A. Aravind

    2012-01-01

    Land snails form an important component in the forest ecosystem. In terms of number of species, the phylum Mollusca, to which land snails belong, is the largest phylum after Arthropoda. Mollusca provide unique ecosystem services including recycling of nutrients and they provide a prey base for small mammals, birds, snakes and other reptiles. However, land snails have the largest number of documented extinctions, compared to any other taxa. Till date 1,129 species of land snails are recorde...

  6. Bioeconomic modelling of hard clam growout in Florida: the replacement decision

    OpenAIRE

    Holiman, Stephen G.; Weldon, Richard N.; Thunberg, Eric M.; Adams, Charles B.; Thomas H. Spreen

    1995-01-01

    A decision to undertake hard clam growout aquaculture in Florida, therefore, requires knowledge of appropriate production systems, sources of operation risk, the effects of risk on operation design and replacement scheduling, and estimates of the costs and returns of hard clam growout under risk. The specific objectives of this research project were: 1. Develop a bioeconomic model of Florida hard clam growout. 2. Generate cost and return estimates of hard clam growout under dif...

  7. Toxicity of a traditional molluscicide to asian clam veligers

    Science.gov (United States)

    Layhee, Megan J.; Miho Yoshioka; Miho Yoshioka; Bahram Farokhkish; Bahram Farokhkish; Gross, Jackson A.; Sepulveda, Adam J.

    2014-01-01

    Aquaculture and hatchery industries are in need of effective control methods to reduce the risk of spreading aquatic invasive species, such as the Asian clam Corbicula fluminea, through aquaculture and hatchery activities. The planktonic nature of Asian clam veligers enables this life stage to enter water-based infrastructure undetected, including hatchery trucks used to stock fish. Once in hatchery trucks, veligers can disperse overland and establish in previously uninvaded habitats. As a result, there is a need to develop techniques that result in veliger mortality but do not harm fish. In September 2012, we conducted laboratory trials to determine if a molluscicide (750 mg/L potassium chloride and 25 mg/L formalin) commonly used to kill zebra mussel (Dreissena polymorpha) veligers in hatchery trucks can also effectively kill Asian clam veligers. We exposed Asian clam veligers to this molluscicide for 1, 3, and 5 h in each of two water types: deionized water and filtered lake water. We found ,20% mortality at the 1-h exposure period and 100% mortality at both the 3-h and 5-h exposure periods, regardless of water type. This laboratory study represents an important step toward reducing the spread of Asian clams by aquaculture facilities.

  8. An efficient method of noroviruses recovery from oysters and clams

    Science.gov (United States)

    Zhou, Deqing; Ma, Liping; Zhao, Feng; Yao, Lin; Su, Laijin; Li, Xinguang

    2013-03-01

    Noroviruses (NoVs) are widespread causes of nonbacterial gastroenteritis. Outbreaks of NoVs caused diseases are commonly ascribed to the consumption of contaminated shellfish. The concentration and RNA extraction of NoVs are crucial steps of detecting NoVs in shellfish. This study aimed to select a simple, rapid and highly efficient recovery method of NoVs detection with real-time RT-PCR. Four methods of recovering GI.3 and GII.4 NoVs from spiked digestive tissues of oysters and clams, respectively, were compared, of them, the method involving proteinase K and PEG 8000 was found the most efficient. With this method, 9.3% and 13.1% of GI.3 and GII.4 NoVs were recovered from oysters and 9.6% and 12.3% of GI.3 and GII.4 NoVs were recovered from clams, respectively. This method was further used to detect NoVs in 84 oysters ( Crassostrea gigas) and 86 clams ( Ruditapes philippinarum) collected from 10 coastal cities in China from Jan. 2011 to Feb. 2012. The NoVs isolation rates were 10.47% of clams (9/86) and 7.14% of oysters (6/84). All the detected NoVs belonged to genotype GII. The NoVs recovery method selected is efficient for NoVs detection in oysters and clams.

  9. An Efficient Method of Noroviruses Recovery from Oysters and Clams

    Institute of Scientific and Technical Information of China (English)

    ZHOU Deqing; MA Liping; ZHAO Feng; YAO Lin; SU Laijin; LI Xinguang

    2013-01-01

    Noroviruses (NoVs) are widespread causes of nonbacterial gastroenteritis.Outbreaks of NoVs caused diseases are commonly ascribed to the consumption of contaminated shellfish.The concentration and RNA extraction of NoVs are crucial steps of detecting NoVs in shellfish.This study aimed to select a simple,rapid and highly efficient recovery method of NoVs detection with real-time RT-PCR.Four methods of recovering GI.3 and GII.4 NoVs from spiked digestive tissues of oysters and clams,respectively,were compared,of them,the method involving proteinase K and PEG 8000 was found the most efficient.With this method,9.3% and 13.1% of GI.3 and GII.4 NoVs were recovered from oysters and 9.6% and 12.3% of GI.3 and GII.4 NoVs were recovered from clams,respectively.This method was further used to detect NoVs in 84 oysters (Crassostrea gigas) and 86 clams (Ruditapes philippinarum) collected from 10 coastal cities in China from Jan.2011 to Feb.2012.The NoVs isolation rates were 10.47% of clams (9/86) and 7.14% of oysters (6/84).All the detected NoVs belonged to genotype GII.The NoVs recovery method selected is efficient for NoVs detection in oysters and clams.

  10. A phylogenetic backbone for Bivalvia: an RNA-seq approach.

    Science.gov (United States)

    González, Vanessa L; Andrade, Sónia C S; Bieler, Rüdiger; Collins, Timothy M; Dunn, Casey W; Mikkelsen, Paula M; Taylor, John D; Giribet, Gonzalo

    2015-02-22

    Bivalves are an ancient and ubiquitous group of aquatic invertebrates with an estimated 10 000-20 000 living species. They are economically significant as a human food source, and ecologically important given their biomass and effects on communities. Their phylogenetic relationships have been studied for decades, and their unparalleled fossil record extends from the Cambrian to the Recent. Nevertheless, a robustly supported phylogeny of the deepest nodes, needed to fully exploit the bivalves as a model for testing macroevolutionary theories, is lacking. Here, we present the first phylogenomic approach for this important group of molluscs, including novel transcriptomic data for 31 bivalves obtained through an RNA-seq approach, and analyse these data with published genomes and transcriptomes of other bivalves plus outgroups. Our results provide a well-resolved, robust phylogenetic backbone for Bivalvia with all major lineages delineated, addressing long-standing questions about the monophyly of Protobranchia and Heterodonta, and resolving the position of particular groups such as Palaeoheterodonta, Archiheterodonta and Anomalodesmata. This now fully resolved backbone demonstrates that genomic approaches using hundreds of genes are feasible for resolving phylogenetic questions in bivalves and other animals.

  11. Effect of Surface Preparation on CLAM/CLAM Hot Isostatic Pressing diffusion bonding joints

    Science.gov (United States)

    Li, C.; Huang, Q.; Zhang, P.

    2009-04-01

    Surface preparation is essential for the Hot Isostatic Pressing (HIP) diffusion bonding of RAFM steels. Hot Isostatic Pressing (HIP) diffusion bonding experiments on China Low Activation Martensitic (CLAM) steel was performed to study the effect of surface preparation. A few approaches such as hand lapping, dry-milling and grinding etc., were used to prepare the faying surfaces of the HIP joints. Different sealing techniques were used as well. The HIP parameters were 150 MPa/3 h/1150 °C. After post HIP heat treatment (PHHT), the tensile and Charpy impact tests were carried out. The results showed that hand lapping was not suitable to prepare the faying surfaces of HIP diffusion bonding specimens although the surface roughness by hand lapping was very low.

  12. The complete mitochondrial genome of Scutopus ventrolineatus (Mollusca: Chaetodermomorpha) supports the Aculifera hypothesis

    OpenAIRE

    Osca, David; Irisarri, Iker; Todt, Christiane; Grande, Cristina; Zardoya, Rafael

    2014-01-01

    Background With more than 100000 living species, mollusks are the second most diverse metazoan phylum. The current taxonomic classification of mollusks recognizes eight classes (Neomeniomorpha, Chaetodermomorpha, Polyplacophora, Monoplacophora, Cephalopoda, Gastropoda, Bivalvia, and Scaphopoda) that exhibit very distinct body plans. In the past, phylogenetic relationships among mollusk classes have been contentious due to the lack of indisputable morphological synapomorphies. Fortunately, rec...

  13. Development status of CLAM steel for fusion application

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qunying, E-mail: qunying.huang@fds.org.cn

    2014-12-15

    The China low activation martensitic (CLAM) steel is being developed at the Institute of Nuclear Energy Safety Technology (INEST) under wide collaboration within China. Significant R and D work on CLAM steel was carried out to help make it suitable for industrial applications. The effect of refining processes and thermal aging on composition, microstructures and mechanical properties were investigated. Material properties before irradiation including impact, fracture toughness, thermal aging, creep and fatigue properties etc. were assessed. A series of irradiation tests in the fission reactor HFETR in Chengdu up to 2 dpa and in the spallation neutron source SINQ in Paul Scherrer Institute up to 20 dpa were performed. PbLi corrosion tests for more than 10,000 h were done in the DRAGON-I and PICOLO loops. Fabrication techniques for a test blanket module (TBM) are being developed and a 1/3 scale TBM prototype is being fabricated with CLAM steel. Recent progresses on the development status of this steel are presented here. The code qualification of CLAM steel is under plan for its final application in ITER-TBM and DEMO in the future.

  14. Scanning electron microscopic structure of the prismatic layer in the Bivalvia

    Institute of Scientific and Technical Information of China (English)

    Iwao KOBAYASHI

    2008-01-01

    The shell structure of the Bivalvia has been observed with the use of optical and electron microscopes since the early 1900's. The prismatic structure is one of the more attractive shell structures in bivalved mollusks. This structure is composed of the aggregation of polygonal prisms arranged densely. Each prism is made of small calcite crystallites arranged perpendicular to a growth shell surface. Organic materials, named organic sheaths, accumulate around prisms and stain well with heamatox-ylin-eosin.The Bivalvia, which make prismatic structures, are divided into two groups. One group has the inner shell layer made up of a nacreous structure, and the other has the inner shell layer made up of a foliated structure. The aragonite prismatic layer and the prismatic layer are clo-sely related to each other, as is the aragonite prismatic layer to the composite prismatic one.

  15. Evolutionary Patterns in Pearl Oysters of the Genus Pinctada (Bivalvia: Pteriidae)

    OpenAIRE

    Cunha, Regina L.; Blanc, Francoise; Bonhomme, Francois; Arnaud-Haond, Sophie

    2011-01-01

    Pearl oysters belonging to the genus Pinctada (Bivalvia: Pteriidae) are widely distributed between the Indo-Pacific and western Atlantic. The existence of both widely distributed and more restricted species makes this group a suitable model to study diversification patterns and prevailing modes of speciation. Phylogenies of eight out of the 11 currently recognised Pinctada species using mitochondrial (cox1) and nuclear (18S rRNA) data yielded two monophyletic groups that correspond to shell s...

  16. Threatened freshwater and terrestrial molluscs (Mollusca, Gastropoda et Bivalvia of Santa Catarina State, Southern Brazil: check list and evaluation of regional threats

    Directory of Open Access Journals (Sweden)

    2011-06-01

    Full Text Available A total of nineteen continental native mollusc species are confirmed for the Santa Catarina State (SC(organized in ten Genera and seven Families, one aquatic Prosobranchia/Caenogastropoda (Ampullariidae,six Pulmonata terrestrial gastropods (one Ellobiidae, three Megalobulimidae and two micro-snails –Charopidae and Streptaxidae and twelve freshwater mussels (eight Mycetopodidae and four Hyriidae. Thesespecies are designated by the International Union for Conservation of the Nature – IUCN as follows: seven as"Vulnerable", six "In Danger" and six “Without Category Established”. The general regional threats that thesespecies are subjected to are briefly analyzed.

  17. Bioaccumulation and elimination of 60 Co and 137 Cs by Anomalocardia brasiliana (Gmelin, 1791) (Mollusca bivalvia). Remobilization of 60 Co, retained in marine sediment by microbial activity

    International Nuclear Information System (INIS)

    It was studied the capacity of a bi valve mollusc Anomalocardia brasiliana, which lives in the local bottom sediment, to remobilize 60 Co previously sorbed in the sediment. Laboratory experiments demonstrated that the transference of 60 Co from the sediment to the animal was insignificant (bioaccumulation factor (BF) of the order of 10-3). At the same time, the capacity of microorganisms, present in the bottom sediment, to remobilize 60 Co was studied. The results showed that this via of transference was important, considering the much greater microorganism biomass in relation to the biomass of bentonic organisms, as a whole. For 137 Cs the determined BF from water to the animal was 2.2. and, as in the case of 60 Co, the soft tissues concentrated more 137 Cs than shell. Remaining viscera showed the highest BFs. In another series of experiments, the loss of 60 Co or 137 Cs, previously accumulated by A. brasiliana, was followed in aquaria with or without sediment and the respective biological half-lives were calculated. Soft tissues retained 60 Co longer (biological half-life = 117 days) than shells, whereas for 137 Cs the opposite was observed and shells showed a biological half life of 38.5 days. The low values of 60 Co and 137 Cs BFS do not allow to classify A. brasiliana as good biological indicator for pollution by there radionuclides. However since A brasiliana is consumed by the local population and is commercialized to other areas, it was recommended that its contamination by 60 Co or 137 Cs should be monitored. (author)

  18. Evaluation of magnesium and manganese in Perna perna mussels (Linnaeus, 1758: mollusca, bivalvia) collected in the cost of the state of Sao Paulo, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Daniele; Vasconcellos, Marina B.A.; Saiki, Mitiko; Cathartino, Marilia G.M.; Moreira, Edson G., E-mail: mbvascon@ipen.b, E-mail: mitiko@ipen.b, E-mail: emoreira@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sousa, Eduinetty C.P.M. de, E-mail: edvinett@usp.b [Universidade de Sao Paulo (IO/USP), SP (Brazil). Inst. Oceanografico. Lab. de Ecotoxicologia Marinha e Microfitobentos

    2011-07-01

    The objective of the present study was to evaluate magnesium and manganese concentrations in Perna perna mussels by applying instrumental neutron activation analysis (INAA). The mussels were collected seasonally from September 2008 to July 2009 at Cocanha Beach in the city of Caraguatatuba (clean region), and at two sites in Santos Bay (Ponta de Itaipu and Palmas Island). The mussel samples were cleaned, grinded, homogenized, lyophilized and then analyzed by INAA. The INAA procedure consisted in the irradiation of the samples and synthetic elemental standards for 10 s, under a thermal neutron flux of 6.6 x 10{sup 12} n cm{sup -2} s{sup -1} in the nuclear research reactor of IPEN-CNEN/SP. The measurements of the gamma radioactivity of the samples and standards were carried out using a hyperpure semiconductor Ge detector, coupled to Digital Spectral Analyzer. The elemental concentrations were calculated by the comparative method. For quality control of analytical results, certified reference materials NIST SRM 1566b oyster tissue and NRC DORM-2 Dogfish Muscle were analyzed and their results indicated good accuracy. The element concentrations in mussels on dry mass basis varied from 2734 {+-} 205 to 5138 {+-} 507 mg kg{sup -1} for Mg and from 7.35{+-}0.57 to 29.06{+-}3.35 mg kg{sup -1} for Mn. The results obtained in mussel analysis indicated that the samples collected in Itaipu in the winter season presented higher accumulation of Mg than the other sites. For Mn, the highest concentrations were obtained for the mussels collected in Palmas in summer time. (author)

  19. Large Vesicomyidae (Mollusca: Bivalvia) from cold seeps in the Gulf of Guinea off the coasts of Gabon, Congo and northern Angola

    Science.gov (United States)

    von Cosel, Rudo; Olu, Karine

    2009-12-01

    Two new genera and three new species of large Vesicomyidae are described from cold-seep sites on pockmarks and other sulfide-rich environments in the Gulf of Guinea (tropical east Atlantic) off Gabon, Congo (Brazzaville) and northern Angola, from 500 to 4000 m depth: " Calyptogena" (s.l.) regab n. sp., Wareniconcha (n.g.) guineensis (Thiele and Jaeckel 1931), Elenaconcha guiness n.g. n. sp., and Isorropodon atalantae n. sp. For two other species already taken by the R/V Valdivia in 1898, Calyptogena valdiviae (Thiele and Jaeckel 1931) and Isorropodon striatum (Thiele and Jaeckel 1931) new localities were discovered, and the species are rediscussed. E. guiness n.g. n.sp. is also recorded from off Banc d'Arguin, Mauritania, collected by commercial fishing vessels. The vesicomyid species here treated were encountered in different depth ranges along the Gabon-Congo-Angola margin, between 500 and 4000 m depth, and it was found that, in comparison with the dredge samples taken by the Valdivia expedition off southern Cameroon and off Rio de Oro (both at 2500 m), the same species occur in other depth ranges, in some cases with a vertical difference of more than 1000 m. .That means that the species are not confined to a given depth thought being typical for them and that the characteristics of the biotope are likely to play a major role in the distribution of the vesicomyids associated to cold seeps or other reduced environments along the West African margin.

  20. [Lipid and fatty acid profile of Perna viridis, green mussel (Mollusca: Bivalvia) in different areas of the Eastern Venezuela and the West Coast of Trinidad].

    Science.gov (United States)

    Koftayan, Tamar; Milano, Jahiro; D'Armas, Haydelba; Salazar, Gabriel

    2011-03-01

    The species Perna viridis is a highly consumed species, which fast growth makes it an interesting aquaculture alternative for Venezuelan and Trinidad coasts. With the aim to contribute with its nutritional value information, this study analyzed lipid and fatty acid contents from samples taken in five locations from Eastern Venezuela and three from Trinidad West Coast. Total lipids were extracted and quantified, from a pooled sample of 100 organisms per location, by standard gravimetric methods, and their identification and quantification was done by TLC/FID (Iatroscan system). Furthermore, the esterified fatty acids of total lipid, phospholipids and triacylglycerols were identified and quantified by gas chromatography. Eastern Venezuela samples from Los Cedros, La Brea and Chaguaramas showed the highest total lipid values of 7.92, 7.74 and 7.53, respectively, and the minimum values were obtained for La Restinga (6.08%). Among lipid composition, Chacopata samples showed the lowest phospholipid concentration (48.86%) and the maximum values for cholesterol (38.87%) and triacylglycerols (12.26%); besides, La Esmeralda and Rio Caribe samples exhibited maximum phospholipids (88.71 and 84.93 respectively) and minimum cholesterol (6.50 and 4.42%) concentrations. Saturated fatty acids represented between 15.04% and 65.55% within total lipid extracts, with maximum and minimum values for La Esmeralda and Chacopata, respectively. Polyunsaturated results resulted between 7.80 and 37.18%, with higher values in La Brea and lower values in La Esmeralda. For phospholipids, saturated fatty acids concentrations varied between 38.81 and 48.68% for Chaguaramas and Chacopata samples, respectively. In the case of polyunsaturated fatty acids, these varied between non detected and 34.51%, with high concentrations in Los Cedros (27.97%) and Chaguaramas (34.51%) samples. For the triacylglycerols, the saturated fatty acids composition oscillated between 14.27 and 53.80% with low concentrations for Chacopata and high concentration for La Restinga; the polyunsaturated fatty acids were between 4.66 and 35.55% with lower values for Chacopata and higher values for Chaguaramas samples. P. viridis is recommended for human being consumption, according to the high content of unsaturated fatty acids found for this species.

  1. Morphological and genetic diversity of the wood-boring Xylophaga (Mollusca, Bivalvia: new species and records from deep-sea Iberian canyons.

    Directory of Open Access Journals (Sweden)

    Chiara Romano

    Full Text Available Deep-sea bivalves of the Xylophagaidae, a poorly known group, are obligate wood-borers. Deployment of wood in three submarine canyons off the Iberian coast, the Blanes and La Fonera Canyons (Mediterranean Sea and the Avilés Canyon (Cantabric Sea, Bay of Biscay, lead to the discovery of four xylophagaid species in our samples. Xylophaga dorsalis (the dominant species, X. atlantica, X. cf. anselli and the new species X. brava, were identified on the basis of morphological data, and supported by a phylogenetic reconstruction based on the nuclear genes 18S rDNA and 28S rDNA and including several genus of Xylophagaidae. Genetic divergence between species of Xylophaga varied between genes, ranging from 0.5 to 4.0% for the 18SrDNA and from 4.1 to 16.6% for the 28SrDNA. Xylophaga brava sp. nov. appeared to be restricted to the Mediterranean and morphologically resembled the closely related X. cf. anselli from the Cantabrian Sea. However, they clearly diverged in two well-supported clades. Low levels of intraspecific variability and higher interspecific divergence between species also supported the existence of these two different species. Morphologically they differ in the number of cirri at the siphon openings, in the shape of the posterior shell and in the size of prodissoconch II. The new species is characterized by having weak, poorly mineralized mesoplax and siphons united throughout, covered by a periostracal, non-calcified tube; distinct proximal and distal siphons, the former translucent and soft, the latter muscular, with concentric rings. Xylophaga atlantica, previously known only from the western Atlantic, is reported for the first time in the Mediterranean Sea. Whether its presence in the Mediterranean indicates its natural distribution or reflects its recent introduction is unknown. Although xylophagaids have been previously reported to recruit heavily to wood deposited on the seabed, these four species colonized wood suspended 30 m above the seafloor.

  2. Mytilus antiquorum J. Sowerby, 1821, and other Pliocene mussels (Mollusca, Bivalvia) from the southern North Sea Basin

    OpenAIRE

    Vervoenen, M.; Wesselingh, F.P.; van Nieulande, F.A.D.

    2000-01-01

    Mytilus antiquorum J. Sowerby, 1821, is recorded from the Coralline Crag Formation of East Anglia (UK) and the Lillo Formation ( Oorderen, Kruisschans and Merksem members) of the Antwerp area (Belgium). The species is diagnosed on the basis of newly collected material and differentiated from modem European mussel species. The presence of M. antiquorum in the southern North Sea Basin is restricted to the Middle (Piacenzian) and early Late Pliocene (Gelasian). A possible occurrence of the spec...

  3. Analysis of Isozyme Diversities in Atrina pectinata Linnaeus (Mollusca,Bivalvia)%栉江珧同工酶多态性的分析

    Institute of Scientific and Technical Information of China (English)

    余祥勇; 王梅芳; 杨书婷; 桂建芳

    2005-01-01

    采用垂直板聚丙烯酰胺梯度凝胶电泳对栉江珧(Atrina pectinata Linnaeus)消化盲囊进行了5种酶(SOD、EST、MDH、ME、LDH)的同工酶分析.结果表明不同个体的同工酶表达呈现多态现象,个体间酶带带型既有相一致的共同特征谱带,又有较多的变异,5种酶均可把样品大致区分为差异明显的2种或3种类型,而且酶谱类型与形态类型基本对应,同工酶表达上的多样性表明栉江珧种内在生化遗传上存在较大的变异,具有较丰富的遗传多态性.

  4. 越南沿海的双壳纲软体动物%Studies on the Bivalvia (Mollusca) of the Vietnam Coast

    Institute of Scientific and Technical Information of China (English)

    蔡英亚; 李海燕

    2002-01-01

    报道了越南沿海的双壳纲软体动物320种,隶属3亚纲、6目、26总科、41科、148属.从种类的组成中,帘蛤科有57种,蚶科32种,樱蛤科29种,贻贝科25种,鸟蛤科16种,牡蛎科14种,蛤蜊科13种,珍珠贝科和扇贝科各12种,紫云蛤科11种,竹蛏科10种,其他各科的种类均在7种以内.按种的性质而论,越南沿海主要是由热带种和亚热带种类组成,还有与珊瑚礁紧密联系的热带种.就越南沿海双壳纲软体动物分类区系而论,应属印度-西太平洋区的印尼-马来亚区.

  5. Evaluation of the levels of Br, Cl, K, Mg, Mn and V in Perna perna Mussels (Linnaeus, 1758: Mollusca, Bivalvia) collected in coast of Sao Paulo, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Daniele; Vasconcellos, Marina B.A.; Saiki, Mitiki; Catharino, Marilia G.M.; Moreira, Edson G., E-mail: danyseo@uol.com.br, E-mail: mbvascon@ipen.br, E-mail: mitiko@ipen.br, E-mail: mgcatharino@uol.com.br, E-mail: emoreira@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sousa, Eduinetty C.P.M. de, E-mail: edvinett@usp.br [Universidade de Sao Paulo (IO/USP), Sao Paulo, SP (Brazil). Instituto Oceanografico. Laboratorio de Ecotoxicologia Marinha e Microfitobentos

    2013-07-01

    In this study the content of Br, Cl, K, Mg, Mn and V was evaluated in samples of Perna perna mussels collected in coastal regions of Sao Paulo (Ponta de Itaipu and Palmas Island, in Santos) subjected to anthropogenic contamination, to compare these values with those of mussels from reference site of Cocanha Beach (in Caraguatatuba). The mussels were collected seasonally from September 2008 to July 2009. They were cleaned, ground, homogenized, lyophilized and then analyzed by Instrumental Neutron Activation Analysis (INAA). The INAA procedure consisted in the irradiation of the samples and synthetic elemental standards for 8 and 10 s, under a thermal neutron flux of 6.6 x 10{sup 12} n cm{sup -2} s{sup -1} in the IEA-R1 nuclear research reactor. For quality control of analytical results, certified reference materials NIST 1566b Oyster Tissue and NIST 2876 Mussel Tissue were analyzed and their results indicated good accuracy. The ranges of concentrations (dry basis) of the elements obtained in mussels collected for the four seasons of the year were: 173.80 to 358.99 mg kg{sup -1} for Br; 45658 ± 1811 to 109166 ± 824 mg kg{sup -1} for Cl; 7043 ± 856 to 12506 ± 675 mg kg{sup -1} for K; 2774 ± 211 to 5691 ± 717 mg kg{sup -1} for Mg; 7.01 ± 0.30 to 29.74 ± 3.32 mg kg{sup -1} for Mn and 0.77 ± 0.02 to 3.43 ± 0.28 mg kg{sup -1} for V. The seasonal and spatial variations of these element concentrations were in this study. (author)

  6. 湘江长沙段的双壳类软体动物%Bivalvia Mollusca in the Changsha Section of Xiang River

    Institute of Scientific and Technical Information of China (English)

    胡自强; 杨海明; 胡少锋

    2004-01-01

    报道了湘江长沙段双壳类软体动物的调查结果,计有双壳类24种及3亚种(其中椭圆背角无齿蚌和橄榄蛏蚌为湖南省新记录种),分别隶属于双壳纲3科17属,其中主要是蚌科珠蚌亚科的种类.并对它们的种类组成、区系、分布、种群大小及栖息环境进行了分析,叙述了优势种的经济价值及利用前景.

  7. Mitochondrial phylogenomics of the Bivalvia (Mollusca: searching for the origin and mitogenomic correlates of doubly uniparental inheritance of mtDNA

    Directory of Open Access Journals (Sweden)

    Bogan Arthur E

    2010-02-01

    Full Text Available Abstract Background Doubly uniparental inheritance (DUI is an atypical system of animal mtDNA inheritance found only in some bivalves. Under DUI, maternally (F genome and paternally (M genome transmitted mtDNAs yield two distinct gender-associated mtDNA lineages. The oldest distinct M and F genomes are found in freshwater mussels (order Unionoida. Comparative analyses of unionoid mitochondrial genomes and a robust phylogenetic framework are necessary to elucidate the origin, function and molecular evolutionary consequences of DUI. Herein, F and M genomes from three unionoid species, Venustaconcha ellipsiformis, Pyganodon grandis and Quadrula quadrula have been sequenced. Comparative genomic analyses were carried out on these six genomes along with two F and one M unionoid genomes from GenBank (F and M genomes of Inversidens japanensis and F genome of Lampsilis ornata. Results Compared to their unionoid F counterparts, the M genomes contain some unique features including a novel localization of the trnH gene, an inversion of the atp8-trnD genes and a unique 3'coding extension of the cytochrome c oxidase subunit II gene. One or more of these unique M genome features could be causally associated with paternal transmission. Unionoid bivalves are characterized by extreme intraspecific sequence divergences between gender-associated mtDNAs with an average of 50% for V. ellipsiformis, 50% for I. japanensis, 51% for P. grandis and 52% for Q. quadrula (uncorrected amino acid p-distances. Phylogenetic analyses of 12 protein-coding genes from 29 bivalve and five outgroup mt genomes robustly indicate bivalve monophyly and the following branching order within the autolamellibranch bivalves: ((Pteriomorphia, Veneroida Unionoida. Conclusion The basal nature of the Unionoida within the autolamellibranch bivalves and the previously hypothesized single origin of DUI suggest that (1 DUI arose in the ancestral autolamellibranch bivalve lineage and was subsequently lost in multiple descendant lineages and (2 the mitochondrial genome characteristics observed in unionoid bivalves could more closely resemble the DUI ancestral condition. Descriptions and comparisons presented in this paper are fundamental to a more complete understanding regarding the origins and consequences of DUI.

  8. Distribución del género Diplodon (Mollusca: Bivalvia: Hyriidae en territorio Argentino mediante el uso de Colecciones Biológicas

    Directory of Open Access Journals (Sweden)

    Santiago Hernán Torres

    2013-10-01

    Full Text Available Los bivalvos nacaríferos dulciacuícolas (“náyades”, son especies infaunales, endémicas de la RegiónNeotropical, pertenecientes a las familias Hyriidae (Swaison, 1840 y Etheriidae (Swaison, 1840. La alteración del ambiente y la competencia con especies invasoras como Corbicula fluminea (Müller, 1774 y Limnoperna fortunei (Dunker, 1857, impactan sobre las poblaciones naturales. En esta comunicación, se presenta el inicio de un Proyecto de investigación sobre la distribución geográfica de las especies del género Diplodon en la Argentina. Estas especies son un componente importante de la infauna de los cuerpos lóticos y lénticos, viviendo en fondos limosos, limo-arenosos, excepcionalmente en sustratos duros, con un régimen nutricio filtrador, teniendo un papel importante como recicladores de materia orgánica. Conocer la distribución de los bivalvos pertenecientes al género Diplodon en el territorio Argentino permitirá el reconocimiento de potenciales áreas prioritarias para su conservación. Sobre la base de la bibliografía disponible y los ejemplares de las especies del genero Diplodon depositados en la Colección Malacológica del Museo de La Plata (FCNyM-UNLP, se confeccionó una matriz de datos que incluye la identificación del ejemplar, la colección en que se encuentra depositado, el número de catálogo, la localidad y la fecha de colecta. Cada localidad fue ubicada mediante el uso de cartas geográficas de Argentina y revisiones bibliográficas en imágenes satelitales de GoogleEarth, asignando las coordenadas para cada punto. Como resultado del trabajo se obtiene la distribución de estas especies nativas y se discute el grado de solapamiento con las dos especies de bivalvos invasores y el impacto de actividades humanas. 

  9. Current knowledge on population studies on five continental molluscs (Mollusca, Gastropoda et Bivalvia of Santa Catarina State (SC, Central Southern Brazil region

    Directory of Open Access Journals (Sweden)

    A. Ignacio Agudo-Padrón

    2011-03-01

    Full Text Available Although still very scarce, available knowledge on population studies on continental (land and freshwatermolluscs in the territory of Santa Catarina State is shortly analyzed and discussed. Based on the IUCN“Restricted Distribution” criterion, a total of 54 nominal species, including 31 terrestrial gastropods, 15freshwater gastropods and 8 limnic bivalves, were considered strong candidates as threatened taxa. Out of allthese endangered species, only 5 limnic forms (2 gastropods and 3 bivalves were previously analysed, in someway, at population level.

  10. Evaluation of 4-nonylphenol toxicity in the clam Tapes philippinarum

    International Nuclear Information System (INIS)

    Lethal and sub lethal effects of 4-nonylphenol (NP) were investigated in the clam Tapes philippinarum from the Lagoon of Venice. In a 96-h lethality test, bivalves were exposed to the following NP concentrations: 0, 0+acetone, .19, 0.38, 0.75, 1.5, and 3.0 mg NP/L. The 96-h LC50 value was 1.12 mg P/L. No mortality was observed at 0.19 mg NP/L, whereas at 1.5 and 3.0 mg P/L both siphons and foot of clams were often cut-off, the animals being unable to withdraw them before shell closure, suggesting the possible narcotic effect of NP. Lower concentrations (0, 0+acetone, 0.025, 0.05, 0.1, nd 0.2 mg NP/L) were then used to evaluate sub lethal NP effects on clearance rate (CR), respiration rate (RR), scope for growth (SFG), and survival in ir. Following a 7-day exposure, decreased RRs were found at all NP concentrations tested. Significant decreases in the CR and SFG were only observed at the two highest NP concentrations (0.1 and 0.2 mg/L), with SFG reductions reaching 54% and 71%, respectively. Last, the highest concentrations tested significantly decreased the resistance of clams to exposure to air and enhanced the mortality rate. As the lowest effective NP concentrations are similar to environmentally realistic levels, a condition of potential risk for the well-being of clam populations in estuarine areas is highlighted

  11. Holoplanktonic Mollusca: development in the Mediterranean Basin during the last 30 million years and their future

    NARCIS (Netherlands)

    A.W. Janssen; K.T.C.A. Peijnenburg

    2014-01-01

    A short introduction is given to the systematics and morphology of pelagic Gastropoda (Mollusca: Heteropoda and Pteropoda), also explaining some details of the animals’ particular way of life. The fossil record of these invertebrates is discussed briefly, followed by an overview of existing literatu

  12. Molecular phylogeny and shell microstructure of Fungiacava eilatensis Goreau et al. 1968, boring into mushroom corals (Scleractinia: Fungiidae), in relation to other mussels (Bivalvia: Mytilidae)

    NARCIS (Netherlands)

    Owada, M.; Hoeksema, B.W.

    2011-01-01

    Research on the evolution of the symbiosis between the boring mussel Fungiacava eilatensis (Bivalvia: Mytilidae) and its mushroom coral hosts (Scleractinia: Fungiidae), which requires phylogenetic reconstructions of both the Mytilidae and the Fungiidae, contributes to the understanding of the comple

  13. Clamming up: environmental forces diminish the perceptive ability of bivalve prey.

    Science.gov (United States)

    Smee, Delbert L; Weissburg, Marc J

    2006-06-01

    The lethal and nonlethal impacts of predators in marine systems are often mediated via reciprocal detection of waterborne chemical signals between consumers and prey. Local flow environments can enhance or impair the chemoreception ability of consumers, but the effect of hydrodynamics on detection of predation risk by prey has not been investigated. Using clams as our model organism, we investigated two specific questions: (1) Can clams decrease their mortality by responding to predators? (2) Do fluid forces affect the ability of clams to detect approaching predators? Previous research has documented a decrease in clam feeding (pumping) in response to a neighboring predator. We determined the benefits of this behavior to survivorship by placing clams in the field with knobbed whelk or blue crab predators caged nearby and compared mortality between these clams and clams near a cage-only control. Significantly more clams survived in areas containing a caged predator, suggesting that predator-induced alterations in feeding reduce clam mortality in the field. We ascertained the effect of fluid forces on clam perception of predators in a laboratory flume by comparing the feeding (pumping) behavior of clams in response to crabs and whelks in flows of 3 and 11 cm/s. Clams pumped significantly less in the presence of predators, but their reaction to blue crabs diminished in the higher velocity flow, while their response to whelks remained constant in both flows. Thus, clam reactive distance to blue crabs was affected by fluid forces, but hydrodynamic effects on clam perceptive distance was predator specific. After predators were removed, clams exposed to whelks took significantly longer to resume feeding than those exposed to blue crabs. Our results suggest that prey perception of predators can be altered by physical forces. Prey detection of predators is the underlying mechanism for trait-mediated indirect interactions (TMIIs), and recent research has documented the

  14. A honeycomb composite of mollusca shell matrix and calcium alginate.

    Science.gov (United States)

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering.

  15. Changing collecting strategies of the clam Donax serra Röding (Bivalvia: Donacidae) during the Pleistocene at Pinnacle Point, South Africa.

    Science.gov (United States)

    Jerardino, Antonieta; Navarro, René A; Galimberti, Mariagrazia

    2014-03-01

    South Africa's Middle Stone Age (MSA) coastal sites have played a prominent role in documenting early evidence of systematic shellfish collection and adaptation to aquatic environments in the context of anatomically modern humans. Pinnacle Point 13B cave is important among these MSA sites not only because it holds the earliest yet known evidence for human use of marine resources (∼162 ka [thousands of years ago]), but because shellfish observations have been integrated more fully into discussions of MSA adaptations. This is particularly the case of Donax serra procurement on sandy beaches, where skills that are usually indicative of an aspect of behavioural modernity (in the context of hunting) were apparently used. In this paper, D. serra from 110 to 91 ka old assemblages are studied in detail by way of metrical analyses and relevant biological and ecological literature of this species. Existing seasonality studies derived from oxygen isotope analyses on the same molluscs are incorporated into this reconstruction. Shellfish appear to have been collected in winter over many millennia when D. serra are most nutritious due to high gonad content. A dramatic change in collection strategies took place during the same millennia-long period. Earliest systematic collection of D. serra consisted of mostly unselective procurement of animals in terms of shell size along the tidal gradient and beach depth. In later visits, people collected mostly larger individuals by narrowing their collection to the mid-intertidal. This change increased the efficiency of D. serra collection, which reflects a positive adaptive behaviour that endured into Later Stone Age (LSA) times.

  16. Environmental context and trophic trait plasticity in a key species, the tellinid clam Macoma balthica L

    DEFF Research Database (Denmark)

    Törnroos, Anna; Nordström, M. C.; Aarnio, K.;

    2015-01-01

    and that clams in the exposed site showed stable isotope values linked to a diet of suspended particulate organic material, while values of individuals in the sheltered site corresponded to an uptake of sediment-bound organic material. Clams transplanted between these two environmental settings were gradually...

  17. Microplastic Ingestion by Wild and Cultured Manila Clams (Venerupis philippinarum) from Baynes Sound, British Columbia.

    Science.gov (United States)

    Davidson, Katie; Dudas, Sarah E

    2016-08-01

    Microplastics, plastic particles Baynes Sound, British Columbia were chosen to examine the microplastic concentrations in wild and cultured Manila clams. Microplastics were isolated using a nitric acid digestion technique and enumerated from 54 clams (27 farmed and 27 non-farmed). Qualitative attributes, such as colour and microplastic type (fiber, fragment, or film) also were recorded. There was no significant difference (F = 1.29; df = 1,4; P = 0.289) between microplastic concentrations in cultured and wild clams. Microplastic concentrations ranged from 0.07 to 5.47 particles/g (from reference beach and shellfish farm clams, respectively). Fibers were the dominant microplastic (90 %); colourless and dark gray fibers were the most common colours observed (36 and 26 %, respectively). Although this indicates that microplastics are definitely present in seafood consumed by humans, shellfish aquaculture operations do not appear to be increasing microplastic concentrations in farmed clams in this region.

  18. Infestation of the clam Chione fluctifraga by the burrowing worm Polydora sp. nov. in laboratory conditions.

    Science.gov (United States)

    Tinoco-Orta, Gissel Dalila; Cáceres-Martínez, Jorge

    2003-07-01

    Burrowing worms that belong to Polydora spp. infest marine mollusks cultured worldwide, causing problems for production and marketing. The clam Chione fluctifraga is semi-cultured in Bahía Falsa, Baja California, NW Mexico, and some clams harbor burrowing worms. The present study was carried out to determine the identity of the worm species infesting the clam, the infesting process by cohabitation of infested and non-infested clams in aquaria with a variety of substrates (fine sand, gross sand, plastic bag used for clam culture, and aquarium without substrate) and turbulence conditions, and the occurrence of architomy phenomena in connection with infestation of the clam. The burrowing worm was considered as a nova species due to its singular limbate neurosetae and notosetae in the setiger 5, hooks in the setiger 6, eyes not present, and general pigmentation, among other characteristics. Infestation was similar in all substrates and turbulence conditions, but it was more abundant on clams previously infested than on those free of worms, showing a preferential settlement of worm infesting stages on pre-infested clams. Regeneration was observed in all segments of the worm: anterior (metastomium), medium, and posterior (prostomium); the complete regeneration time occurred in 40 days. This is the first record of architomy in a species of Polydora and this phenomenon could account for the increase of infestation intensity in pre-infested clams at the end of the study period. Infestation of clams by settling polichaete in the conditions studied, and the architomy process in this worm species, shows its great infesting capacity. PMID:12877826

  19. Assessment of clam ruditapes philippinarum as Heavy metal bioindicators using NMR-based metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoli; Zhang, Linbao; You, Liping [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); The Graduate School of Chinese Academy of Sciences, Beijing (China); Yu, Junbao; Cong, Ming; Wang, Qing; Li, Fei; Li, Lianzhen; Zhao, Jianmin; Li, Chenghua; Wu, Huifeng [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China)

    2011-08-15

    There are mainly distributed three pedigrees (White, Liangdao Red, and Zebra) of Manila clam Ruditapes philippinarum in Yantai population along the Bohai marine and coast. However, the biological differences to environmental stressors have been ignored in toxicology studies, which could lead to the distortion of biological interpretations of toxicological effects induced by environmental contaminants. In this study, we applied a system biology approach, metabolomics to compare the metabolic profiles in digestive gland from three pedigrees of clam and characterize and compare the metabolic responses induced by mercury in clam digestive gland tissues to determine a sensitive pedigree of clam as a preferable bioindicator for metal pollution monitoring and toxicology research. The most abundant metabolites, respectively, included branched-chain amino acids, alanine, and arginine in White samples, glutamate, dimethylglycine, and glycine in Zebra clams and acetylcholine, betaine, glucose, and glycogen in Liangdao Red clams. After 48 h exposure of 20 {mu}g L{sup -1} Hg{sup 2+}, the metabolic profiles from the three pedigrees of clams showed differentially significant changes in alanine, glutamate, succinate, taurine, hypotaurine, glycine, arginine, glucose, etc. Our findings indicate the toxicological effects of mercury exposure in Manila clams including the neurotoxicity, disturbances in energetic metabolisms and osmoregulation in the digestive glands and suggest that Liangdao Red pedigree of clam could be a preferable bioindicator for the metal pollution monitoring based on the more sensitive classes of metabolic changes from digestive glands compared with other two (White and Zebra) pedigrees of clams. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Biodeposition, respiration, and excretion rates of an introduced clam Mercenaria mercenaria in ponds with implications for potential competition with the native clam Meretrix meretrix in Shuangtaizi estuary, China

    Science.gov (United States)

    Zhang, Anguo; Yuan, Xiutang; Hou, Wenjiu; Li, Xiaodong; Zhao, Kai; Chen, Weixin; Su, Xiurong

    2016-05-01

    This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of M. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates of M. mercenaria were 0.06-0.37 g/ (ind.·d), and the respiration rates were 0.31-14.66 mg/(ind.·d). The ammonia and phosphate excretion rates were 0.18-36.70 and 1.44-14.87 μg/(ind.·d), respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1×105 t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×103 t O2 from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food if M. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.

  1. Bioaccumulation of gasoline in brackish green algae and popular clams

    Directory of Open Access Journals (Sweden)

    Gihan A. El-Shoubaky

    2016-03-01

    Full Text Available The green algae (Ulva lactuca and Enteromorpha clathrata and the clams (Tapes decussates and Venerupis aurea grow together in Timsah Lake, Suez Canal, Egypt. Our ultimate goal is to validate the bioaccumulation of gasoline in the marine organisms and their behavior after exposure to the pollutant, experimentally. These species were treated with a serial treatment of gasoline (1000, 4000, 16,000 and 64,000 μl in aquaria with brackish sea-water for 72 h. The tested green algae and clams were taken for an analysis of total hydrocarbon accumulation daily. The statistical analysis showed significant differences between the four species and also between the duration of exposure. The accumulation of gasoline in U. lactuca and E. clathrata reached their maximum after 48 h at 1000 and 4000 μl. The highest absorption was registered after 24 h only at 16,000 and at 64,000 μl. U. lactuca recorded complete mortality in 64,000 μl at 72 h whereas E. clathrata registered death at 48 h and 72 h in the same treatment. V. aurea was more sensitive than T. decussates. The accumulation of gasoline reached its maximum in V. aurea after only 24 h in the first treatment while it retarded to 48 h in T. decussates with a lesser accumulation. However, both clam species accumulated the highest amount of petroleum hydrocarbons during the first hour of exposure at the first treatment. In the third and fourth treatments, clams did not accumulate gasoline but began to dispose it from their tissues till it became less than that in the control. Mortality gradually increased with time in each treatment except the last one (64,000 μl in which 100% death of the specimens was observed. In general, the bioaccumulation of gasoline level was in a descending order as follows: U. lactuca > E. clathrata > V. aurea > T. decussates. Their behavior changed from accumulation to detoxification with time and with the increase in pollutant concentration. Generally, these

  2. Anti-ulcer potentials of phylum mollusca (tropical snail) slime

    Institute of Scientific and Technical Information of China (English)

    Nwodo NJ; Okonta J M; Ezugwu CO; Attama AA

    2009-01-01

    Objective:The effectiveness of the slimy substance in snail to regenerate and repair damaged areas on its body/shell lead to this investigation.Methods:The anti-ulcer'property of snail slime extracted from phylum mollusca (tropical snail)from the giant African snail Archachatina marginata (Fam.Arionidae)was investi-gated using histamine,stress and indomethacin-induced ulcers.The solubility profile of extract was investiga-ted in different solvents and at different temperatures.Chemical analysis was carried out to determine the types of constituents present in the slim,while acute toxicity test was carried out to evaluate its profile of toxicity. The effect of the snail slim on gastrointestinal motility was investigated in mice,while the guinea pig ileum was used to study the effect of the extract on contraction produced by acetylcholine and histamine.The snail slime contained copious quantity of protein,with varying amounts of simple sugars,carbohydrates and fats.The slime was not soluble in most common solvents and increases in temperature,did not appear to increase its sol-ubility.Results:The result further indicated that although the snail slime exhibited significant (P <0.05)an-ti-ulcer induced by stress and histamine,it was most potent against ulcer induced by indomethacin.The snail slime potently inhibited gastrointestinal movement in mice in a dose-dependent manner;however,it was not a-ble to inhibit contraction induced by acetylcholine and histamine in guinea pig ileum.Conclusion:The snail mucin possesses potent antiulcer properties without any toxic effect.The mechanism responsible for the anti-ul-cer property may not be postulated with certainty but cytoprotective and anti-spasmodic activities are most likely to be involved.

  3. The antioxidant potential of the New Zealand surf clams.

    Science.gov (United States)

    Odeleye, Tinu; Li, Yan; White, William Lindsey; Nie, Shaoping; Chen, Shuping; Wang, Junqiao; Lu, Jun

    2016-08-01

    The antioxidant action of three New Zealand surf clams was evaluated for the first time. Aqueous (cd) and ethanolic extracts from Diamond shell - Crassula aequilatera, Storm shell - Mactra murchisoni, and Tua tua - Paphies donacina were studied for their antioxidant potentials using two in vitro assays. The ethanolic extracts were further fractioned into four parts; petroleum ether (pe), ethyl acetate (ea), n-butanol (nb), and the final aqueous fraction (w). Comparing among all fractions tested, the ea fraction of P. donacina showed the strongest free radical scavenging power, with a radical scavenging activity of 76.14% at 20μg/mL. The ea fraction of C. aequilatera had the highest copper reducing activity with an absorbance of 1.596 at 20μg/mL. Results from this study suggest that some bioactive compounds with significant antioxidant effects may exist in the New Zealand surf clams, and could potentially reduce oxidative stress to deliver health benefits or to produce functional foods. PMID:26988487

  4. Land snails (Mollusca: Gastropoda of India: status, threats and conservation strategies

    Directory of Open Access Journals (Sweden)

    S. Sen

    2012-09-01

    Full Text Available Land snails form an important component in the forest ecosystem. In terms of number of species, the phylum Mollusca, to which land snails belong, is the largest phylum after Arthropoda. Mollusca provide unique ecosystem services including recycling of nutrients and they provide a prey base for small mammals, birds, snakes and other reptiles. However, land snails have the largest number of documented extinctions, compared to any other taxa. Till date 1,129 species of land snails are recorded from Indian territory. But only basic information is known about their taxonomy and little is known of their population biology, ecology and their conservation status. In this paper, we briefly review status, threats and conservation strategies of land snails of India.

  5. Ciclo gametogênico e comportamento reprodutivo de Iphigenia brasiliana (Mollusca, Bivalvia, Donacidae no estuário do rio Subaé, Baía de Todos os Santos, Bahia, Brasil Gametogenic cycle and reproductive behavior of Iphigenia brasiliana (Mollusca, Bivalvia, Donacidae in the Subaé river estuary, Todos os Santos Bay, Bahia, Brazil

    Directory of Open Access Journals (Sweden)

    Patrícia P. Silva

    2012-12-01

    Full Text Available Este estudo teve como objetivos descrever o ciclo gametogênico e o comportamento reprodutivo da população de Iphigenia brasiliana (Lamarck,1818 no estuário do rio Subaé, Baía de Todos os Santos, Bahia. Os bivalves foram coletados de novembro de 2001 a novembro de 2002. Um total de 244 espécimes foi medido (eixo anteroposterior, eviscerado, fixado, desidratado e incluído em parafina. O estudo histológico das gônadas foi realizado através de cortes seriados do tecido gonadal, de 5 mm de espessura, e corados pela HE. O tamanho médio mínimo da primeira maturação sexual (Lpm foi estimado a partir da distribuição das frequências relativas de jovens e adultos, por classe de comprimento dos indivíduos. As frequências relativas dos sexos em cada estádio de desenvolvimento foram consideradas conjuntamente para a análise do comportamento reprodutivo da população, e, em separado, para avaliar a sincronia do ciclo sexual entre machos e fêmeas. Foi observada uma variação de tamanhos entre 9,1 e 66,6 mm, com comprimento médio de 50,2 mm. O estudo não demonstrou diferença significativa entre os tamanhos de machos e fêmeas. Não foi possível observar a diferenciação de sexos em 2,1% dos indivíduos analisados. 51,6% dos indivíduos foram identificados como machos (M e 46,3% como fêmeas (F, não sendo constatadas diferenças significativas entre o número médio de machos e fêmeas, resultando numa proporção de M:F de 1,1:1. O Lpm foi estimado em 11,4 mm, mas apenas ao alcançarem comprimento médio de 34,4 mm, todos os indivíduos foram considerados adultos. Foram caracterizados quatro estádios de evolução do desenvolvimento gonadal em fêmeas e machos. A análise dos diferentes estádios permitiu a observação dos fenômenos de atresia e inversão sexual em fêmeas. O ciclo reprodutivo apresentou eliminação contínua de gametas, com maiores intensidades reprodutivas nos meses de novembro de 2001 a abril de 2002 e, também, no mês de outubro de 2002.This study aimed to describe the gametogenic cycle and reproductive behavior of the population of Iphigenia brasiliana (Lamarck, 1818 in the estuary of the Subaé river, Todos os Santos Bay, Bahia. The bivalves were collected from November 2001 to November 2002. A total of 244 specimens was measured (anteroposterior axis, gutted, fixed, dehydrated and embedded in paraffin. The histology of the gonads was performed by 5 mm thick serial sections of gonadal tissue, and stained with HE. The length at the beginning of gonadal maturation (Lpm was estimated from the distribution of the relative frequencies of youth and adults, by length class of individuals. The relative frequencies of the sexes at each stage of development were considered together for the analysis of the reproductive behavior of the population, and, separately, to assess the sexual cycle synchrony between males and females. We observed a variation of sizes between 9.1 and 66.6 mm, with a mean length of 50.2 mm. The study showed no significant difference between the sizes of males and females. There was no evidence of gender differentiation in 2.1% of subjects analyzed. 51.6% of subjects were identified as males (M and 46.3% as females (F, without significant differences among average number of male and female, resulting in the proportion of M:F ratio of 1,1:1. Lpm was estimated at 11.4 mm, but only to achieve average length of 34.4 mm, all subjects were considered adults. We characterized four stages of evolution of gonadal development in females and males. Analysis of different stages allowed the observation of the atresia phenomena and sex reversal in females. The reproductive cycle presents continuous elimination of gametes, with higher reproductive intensities in the months of November 2001 to April 2002 and also in October 2002.

  6. PHYSIOLOGICAL RESPONSES OF THE BROWN MUSSEL Perna perna (MOLLUSCA, BIVALVIA EXPOSED TO THE ANIONIC SURFACTANT LINEAR ALKYLBENZENE SULPHONATE (LAS = RESPOSTAS FISIOLÓGICAS DE MEXILHÃO Perna perna (MOLLUSCA, BIVALVIA EXPOSTO AO SURFACTANTE ANIÔNICO ALQUILBENZENO SULFONATO LINEAR (LAS

    Directory of Open Access Journals (Sweden)

    Marina Freitas Stefanoni

    2011-01-01

    Full Text Available The effects of the Linear Alkylbenzene Sulphonate (LAS were evaluated on the mussel Perna perna, using physiological and genotoxic biomarkers. The Micronuclei (MN assay was used to estimate effects at nuclear level, whereas the physiological effects were evaluated by measuring the oxygen consumption and ammonia excretion rates. Significant effects were observed for the MN assay and the ammonia excretion rate, even in low concentrations. The oxygen consumption was not affected in the tested concentrations. For MN and ammonia excretion, the animals exposed to intermediate concentrations were not affected, but responded to the higher concentrations, indicating the existence of compensatory mechanisms at physiological level. However, parallel to this study other authors indicate the presence of progressive effects at the cellular level, suggesting that the organisms are not capable to recover of such increasing effects. Additionally, the results show that the levels of LAS observed for Brazilian coastal waters may chronically affect the biota. = Os efeitos do Alquilbenzeno Sulfonato de Sódio Linear sobre o mexilhão Perna perna foram avaliados por meio do uso de biomarcadores genotóxicos e fisiológicos. O ensaio da taxa de micronúcleos (MN foi conduzido para estimar o efeito ao nível nuclear, enquanto os efeitos fisiológicos foram avaliados através da medição da taxa de consumo de oxigênio e de excreção de amônia. Efeitos significativos foram observados para o ensaio do MN e para a taxa de excreção de amônia, mesmo em baixas concentrações. O consumo do oxigênio não foi afetado pelas concentrações dos ensaios. Para MN e excreção de amônia, os animais expostos às concentrações intermediárias não foram afetados, mas responderam às maiores concentrações, sugerindo a existência de mecanismos compensatórios em nível fisiológico. Contudo, paralelamente ao presente estudo, outros autores demonstraram haver efeitos progressivos em nível celular, sugerindo que os organismos não conseguem se recuperar dos efeitos crescentes da exposição. Os resultados ainda mostram que níveis de LAS presentes na costa brasileira podem afetar cronicamente a biota.

  7. Avaliação da infestação e diversidade de Teredinidae (Mollusca - Bivalvia ao longo da costa do estado do Rio de Janeiro, Brasil Evaluation of the infestation and diversity of Teredinidae (Mollusca - Bivalvia along the coast of Rio de Janeiro State, Brazil

    Directory of Open Access Journals (Sweden)

    Andrea de O. R. Junqueira

    1989-01-01

    Full Text Available In order to evaluate the diversity and infestation level of Teredinidae wood-boring molluscs, ten satations were chosen along the coast of Rio de Janeiro State. Using five pine-wood panels in each station, it was possible to distinguish five areas according to species dominance. Ilha Grande Bay is characterized by the dominance of Lyrodus floridanus (Bartsch, 1922; Sepetiba Bay, by Bankia fimbriatula Moll & Roch, 1931, Tijuca Lagoon by Teredo navalis Linnaeus, 1758; Guanabara Bay by Notoredo knoxi (Bartsch, 1917 and Araruama Lagoon by Teredo furcifera Martens, 1894. Specific composition and dominance of these species were due mainly to abiotic factors such as salinity whereas infestation level was associated not only to salinity but also to other factors such as the quantity and quality of fouling, the presence of larval dispersion focus and the wood supply in each area.

  8. Avaliação da infestação e diversidade de Teredinidae (Mollusca - Bivalvia) ao longo da costa do estado do Rio de Janeiro, Brasil Evaluation of the infestation and diversity of Teredinidae (Mollusca - Bivalvia) along the coast of Rio de Janeiro State, Brazil

    OpenAIRE

    Junqueira, Andrea O. R.; Sergio Henrique G. da Silva; Maria Júlia M. Silva

    1989-01-01

    In order to evaluate the diversity and infestation level of Teredinidae wood-boring molluscs, ten satations were chosen along the coast of Rio de Janeiro State. Using five pine-wood panels in each station, it was possible to distinguish five areas according to species dominance. Ilha Grande Bay is characterized by the dominance of Lyrodus floridanus (Bartsch, 1922); Sepetiba Bay, by Bankia fimbriatula Moll & Roch, 1931, Tijuca Lagoon by Teredo navalis Linnaeus, 1758; Guanabara Bay by Notoredo...

  9. PHYSIOLOGICAL RESPONSES OF THE BROWN MUSSEL Perna perna (MOLLUSCA, BIVALVIA) EXPOSED TO THE ANIONIC SURFACTANT LINEAR ALKYLBENZENE SULPHONATE (LAS) = RESPOSTAS FISIOLÓGICAS DE MEXILHÃO Perna perna (MOLLUSCA, BIVALVIA) EXPOSTO AO SURFACTANTE ANIÔNICO ALQUILBENZENO SULFONATO LINEAR (LAS)

    OpenAIRE

    Marina Freitas Stefanoni; Denis Moledo de Souza Abessa

    2011-01-01

    The effects of the Linear Alkylbenzene Sulphonate (LAS) were evaluated on the mussel Perna perna, using physiological and genotoxic biomarkers. The Micronuclei (MN) assay was used to estimate effects at nuclear level, whereas the physiological effects were evaluated by measuring the oxygen consumption and ammonia excretion rates. Significant effects were observed for the MN assay and the ammonia excretion rate, even in low concentrations. The oxygen consumption was not affected in the tested ...

  10. What explains the invading success of the aquatic mud snail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)?

    OpenAIRE

    Alonso, A.; Castro-Diez, P.

    2008-01-01

    The spread of non-native species is one of the most harmful and least reversible disturbances in ecosystems. Species have to overcome several filters to become a pest (transport, establishment, spread and impact). Few studies have checked the traits that confer ability to overcome these steps in the same species. The aim of the present study is to review the available information on the life-history and ecological traits of the mud snail, Potamopyrgus antipodarum Gray (Hydrobiidae, Mollusca),...

  11. First record of Okenia pellucid Burn, 1967 (Mollusca: Nudibranchia from India

    Directory of Open Access Journals (Sweden)

    V. Bhave

    2012-11-01

    Full Text Available There are very few records of opisthobranchs in comparison to the vastness of Indian coasts. The published records are very patchy and limited to a few areas such as Gulf of Kutch, Gulf of Mannar, Lakshadweep and Andaman Nicobar Islands. The present paper records Okenia pellucida Burn, 1967 (Mollusca: Opisthobranchia for the first time from India on the south-western coast of Maharashtra. This nudibranch is known to be associated with fouling bryozoans Zoobotryon verticillatum.

  12. Field and laboratory transmission studies of haemic neoplasia in the soft-shell clam, Mya arenaria, from Atlantic Canada.

    Science.gov (United States)

    Mateo, D R; MacCallum, G S; Davidson, J

    2016-08-01

    A two-year laboratory and field study was initiated in 2001 in response to mass mortalities associated with haemic neoplasia (HN) in 1999 in Prince Edward Island (PEI) soft-shell clams, Mya arenaria. A laboratory proximity experiment (cohabitation) and an inoculation challenge were conducted with clams and mussels (Mytilus edulis). Three field exposure experiments were also conducted, in which naive clams were held in sediment (in trays) or out of sediment (in mesh bags) at three high HN prevalence sites on PEI. There was a conversion to HN positive in clams in the proximity experiment and in clams injected with whole blood and cell-free homogenate, but not at statistically significant levels. No mussels or control clams became HN positive. There was a significant conversion to HN positive in as little as 24 and 58 days after transfer with clams held out of sediment and in sediment, respectively. The laboratory and field experiments' results suggest that HN-infected clams are spreading the disease through water from infected clams to naïve individuals and via transplantation from affected to unaffected sites. Some environmental conditions (e.g. abnormally high water temperature and hypoxia-induced sea lettuce [Ulva lacteus] invasion) may make clams susceptible to infections or exacerbate the proliferation of HN. PMID:26687447

  13. Habitat Preferences and Growth of Ruditapes bruguieri (Bivalvia: Veneridae at the Northern Boundary of Its Range

    Directory of Open Access Journals (Sweden)

    Alla V. Silina

    2014-01-01

    Full Text Available This work is the first attempt to study growth and some morphological parameters of the clam Ruditapes bruguieri, as well as its habitat preferences. It is found that R. bruguieri lives on bottom sediments including pebble and coarse- and medium-grained sand with a slight admixture of silt. At the study area, this bivalve inhabits sea waters with good aeration, stable oceanic water salinity, and a high oxygen concentration. The annual fluctuations of the water temperature from 13-14°C (in winter to 22–29°C (in summer are close to the threshold temperature values, within which the species can exist. Near the boundary of the species range, along the Jeju Island coasts, south of Republic of Korea, 83.8% of all clams die during the coldest period of the year. Here, annual rings are formed on R. bruguieri shells during winter. The maximum age of R. bruguieri, determined during the study, is 6.5 years, but the clam samples contain mainly individuals at 3.0–3.5 years of age (34%. The largest clam dimensions are 36.0 × 26.5 mm (length × height of shell. At the study area, a usual shell length is 20.0–32.0 mm (75% of all the collected individuals.

  14. Biodiesel Production from Castor Oil by Using Calcium Oxide Derived from Mud Clam Shell

    Directory of Open Access Journals (Sweden)

    S. Ismail

    2016-01-01

    Full Text Available The catalytic potential of calcium oxide synthesized from mud clam shell as a heterogeneous catalyst for biodiesel production was studied. The mud clam shell calcium oxide was characterized using particle size analyzer, Fourier transform infrared spectroscopy, scanning electron microscopy, and BET gas sorption analyzer. The catalyst performance of mud clam shell calcium oxide was studied in the transesterification of castor oil as biodiesel. Catalyst characterization and transesterification study results of synthesized catalyst proved the efficiency of the natural derived catalyst for biodiesel production. A highest biodiesel yield of 96.7% was obtained at optimal parameters such as 1 : 14 oil-to-methanol molar ratio, 3% w/w catalyst concentration, 60°C reaction temperature, and 2-hour reaction time. Catalyst reusability test shows that the synthesized calcium oxide from mud clam shell is reusable up to 5 times.

  15. Assessment of immune parameters of manila clam Ruditapes philippinarum in different physiological conditions using flow cytometry

    Science.gov (United States)

    Park, Kyung-Il; Donaghy, Ludovic; Kang, Hyun-Sil; Hong, Hyun-Ki; Kim, Young-Ok; Choi, Kwang-Sik

    2012-03-01

    Cellular and humoral immune parameters are often used as biomarkers to trace environmental and physiological stresses in marine bivalves. In this study, we compared various immune parameters of Manila clams ( Ruditapes philippinarum) under normal conditions and under a high level of desiccation, using flow cytometry. The immune parameters analyzed included, total hemocyte count, hemocyte mortality, hemocyte DNA damage, reactive oxygen species (ROS) production, and phagocytosis activity. Total hemocyte count, hemocyte DNA damage, and hemocyte mortality were significantly elevated among clams under high desiccation stress, while phagocytosis activity and spontaneous ROS production were significantly lower compared to those parameters of the control clams ( pimmune parameters analyzed in this study well reflect the physiological status of clams.

  16. Population Dynamics of the Giant Clam, Tridacna maxima, at Rose Atoll

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — There is a paucity of knowledge on the population dynamics of the giant clams of the family Tridacnidae. Such information on population dynamics is necessary for...

  17. Geographic distribution of mercury in asiatic clams, Corbicuia plumihea, from the North Fork Holston River, Virginia

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A study was conducted quantifying mercury concentrations in the Asiatic clam, Corbicula fluminea, from the North Fork Holston River, Virginia. The purpose of this...

  18. Contaminant assessment of fish, rangia clams, and sediments in the Lower Pamlico River, North Carolina

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Samples of sediment, rangia clams (Rangia cuneata), gizzard shad (Dorosoma cepedianum), and longnose gar (Lepisosteus osseus) were collected from five sites in the...

  19. Fisheries ecology: hunger for shark fin soup drives clam chowder off the menu.

    Science.gov (United States)

    Brierley, Andrew S

    2007-07-17

    Removal by fishing of large sharks has reduced predation-pressure on shark prey and, via a trophic cascade, caused clam populations to crash. This indirect response illustrates why fisheries should be managed in a whole-ecosystem context.

  20. Population characteristics of the mangrove clam Polymesoda (geloina) erosa (solander, 1786) in the Chorao mangrove, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Naik, S.; Furtado, R.; Ansari, Z.A.; Chatterji, A.

    in the Indo-Pacific region. This unique but fragile ecosystem has been providing firewood, charcoal, pole, tannin and some traditional medicine to the people of coastal areas. Edible marine bivalves (clams, mussels and oysters) are widely distributed and form...

  1. An investigation on the disruptive effect of pollution in cold- and warm- adapted clam populations

    Directory of Open Access Journals (Sweden)

    F Gagné

    2009-11-01

    Full Text Available The purpose of this study was to examine the relationship between mitochondrial activity and gonad lipid stores in clams exposed to anthropogenic pollution at cold- and warm-water sites. The balance between energy expenses and energy reserves was measured by mitochondrial electron transport (MET activity and lipid content in the gonad. The activity of malate dehydrogenase (MDH was measured as an intermediary between energy production and the production of lipids in gonadal tissues. The results revealed that intertidal clam populations at warm-water sites under no source of pollution had less heavy metal content (Ag, As, Cr, Hg and Ni, lower MDH activity and temperature-dependent MET than clams from cold-water sites. However, MDH activity measured at 6 oC was higher at the warm-water sites. Lipid peroxidation in the gonad was higher in clams from the cold-water sites. The impacts of pollution differed among the study sites, clams from cold-water sites having increased MDH activity, temperature-dependent MET activity, higher lipid content and DNA strand breaks; clams from the warm-water sites had increased temperature-dependent MDH activity and lower gonadal lipid reserves. A multiple regression analysis revealed that gonad lipid reserves were positively correlated with MDH activity and negatively correlated with its temperature-dependent activity, suggesting that increased temperature sensitivity was negatively related to gonad energy reserves. The data show that pollution increases temperature sensitivity at the MET level in clams in cold water, while temperature sensitivity in MDH activity was observed in clams from warm-water sites. Discriminate function analysis revealed that pollution stress shows a tendency to be closer to clams adapted to warmer temperatures. In conclusion, pollution could increase MDH activity in cold-adapted clams which can lead to increased lipid stores in the gonad, oxidative stress and genotoxicity while pollution

  2. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria) in Response to Salinity Challenges.

    Science.gov (United States)

    Lin, Chia-Hao; Yeh, Po-Ling; Lee, Tsung-Han

    2016-01-01

    Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan) have not been determined. In this study, we examined the effect of exposure to hypo (10‰)- and hyper (35‰)-osmotic salinity on hard clams raised at their natural salinity (20‰). The osmolality, [Na(+)], and [Cl(-)] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na(+), K(+)-ATPase (NKA) activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT) is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore the

  3. The importance of turbulent kinetic energy on transport of juvenile clams (Mya arenaria)

    OpenAIRE

    Redjah, I.; Olivier, Frederic; Tremblay, R.; Myrand, B.; Pernet, Fabrice; Neumeier, U.; Chevarie, L.

    2010-01-01

    Soft-shell clam, Mya arenaria, culture on the east coast of Canada is characterized by high loss following seeding. To evaluate the importance of passive transport due to currents, an experimental flume study was designed. The purpose was to measure the effects of hydrodynamic conditions, substrate, and clam size on dispersal in controlled laboratory condition and to interpret these results in relation to field measurements. Unidirectional currents with gradual increasing velocities (0 to 60 ...

  4. Immune- and Pollution-mediated DNA Damage in Two Wild Mya arenaria Clam Populations

    OpenAIRE

    François Gagné; M. Laura Martín-Díaz; Christian Blaise

    2009-01-01

    In aquatic environments, genotoxicity results from the effects of pollution combined with the inflammatory response triggered by the immune system. Indeed, the production of nitrosylated DNA and proteins are though to arise from the production of peroxinitrite during phagocytosis and inflammation. The purpose of this study was to examine new DNA biomarkers that differentiate between immune- and pollution-mediated genotoxicity in wild clam populations. Intertidal clam populations were sampled ...

  5. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria) in Response to Salinity Challenges.

    Science.gov (United States)

    Lin, Chia-Hao; Yeh, Po-Ling; Lee, Tsung-Han

    2016-01-01

    Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan) have not been determined. In this study, we examined the effect of exposure to hypo (10‰)- and hyper (35‰)-osmotic salinity on hard clams raised at their natural salinity (20‰). The osmolality, [Na(+)], and [Cl(-)] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na(+), K(+)-ATPase (NKA) activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT) is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore the

  6. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria in Response to Salinity Challenges

    Directory of Open Access Journals (Sweden)

    Chia-Hao Lin

    2016-08-01

    Full Text Available Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan have not been determined. In this study, we examined the effect of exposure to hypo (10‰- and hyper (35‰-osmotic salinity on hard clams raised at their natural salinity (20‰. The osmolality, [Na+], and [Cl-] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na+,K+-ATPase (NKA activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore

  7. Growth performance of the clam, Meretrix meretrix, breeding-selection populations cultured in different conditions

    Institute of Scientific and Technical Information of China (English)

    WANG Chao; CHAI Xueliang; WANG Hongxia; TANG Baojun; LIU Baozhong

    2013-01-01

    A breeding-selection program for the clam, Meretrix meretrix, was conducted since 2004. Two of the selec-tion populations were generated with the shell color pattern as an additional selection criterion and named as SP (purple stripes) population and SB (black dots) population. The third-generation SP and SB popula-tions (08G3SP and 08G3SB, respectively) were cultured at two commercial clam farms and a nursery pond and their shell lengths were compared. 08G3SB clams had significantly larger sizes than 08G3SP clams at commercial clam farms (p<0.05), yet 08G3SB individuals were significantly smaller than 08G3SP individ-uals at the nursery pond (p <0.05). Then, we examined the growth of the fourth-generation SP and SB populations (10G4SP and 10G4SB, respectively) at a commercial farm, and found that the shell lengths of the 10G4SB clams increased at a significantly higher growth rate than the 10G4SP clams (p <0.05) from May to September, when the water temperature was between 24.2-27.5◦C, while 10G4SB lost the growth advantage in the other months. These results indicated that SP and SB populations responded differently to environmental factors, so it is beneficial for the clam farmers to select a suitable population according to the culture environment. Furthermore, a diallel mating of the SB and SP populations was designed to investigate whether their hybrid population would show heterosis. However, the heterosis was not shown in this study, which might result from the slight genetic divergence between SB and SP populations.

  8. Abnormal features of Macoma balthica (Bivalvia) in the Baltic Sea: alerting symptoms of environmental adversity?

    Energy Technology Data Exchange (ETDEWEB)

    Sokolowski, Adam; Wolowicz, Maciej; Hummel, Herman; Smolarz-Gorska, Katarzyna; Fichet, Denis; Radenac, Gilles; Thiriot-Quievreux, Catherine; Namiesnik, Jacek

    2004-07-01

    Recent studies of the Baltic clam Macoma balthica (L.) from the southern Baltic (the Gulf of Gdansk) have revealed striking morphological, histological and cytogenetic features. Strong deformation of the shell, including elongation of the posterior end and the appearance of an easily visible flexure in this part, has been recorded. The population contribution of the deformed blunt shelled ('irregular') clams ranged from 0% to 65% and tended to increase with depth. The morphologically 'irregular' clams had higher accumulated tissue concentrations of trace metals (As, Ag, Cd, Pb, Cu and Zn), indicating a different metal handling ability. Adverse conditions in deeper water regions of the Gulf (e.g. hypoxia, hydrogen sulphide, elevated bioavailability of contaminants) have been suggested as inducers of the phenotypical changes (morphological deformation) in part of the population and, in parallel, of the specific physiological adaptations that result in higher metal accumulation in the 'irregular' clams. Cytogenetic and histological analyses showed the presence of tumours in gill cells and digestive system of the affected clams, the prevalence of disseminated neoplasia ranging from 0% to 94% depending on the site. The disease was manifested by a modified karyotype (i.e. an abnormal number and morphology of chromosomes), a higher activity of nucleolar organizer regions (AgNORs), and tissue lesions (enlarged cells, actively proliferative with pleomorphic nuclei). Bottom sediments showed acute toxicity and have been proposed as a source of an initialising carcinogenic factor. However, none of the ecotoxicological studies provided was successful in the clear demonstration of a single (or multifactorial) agent that can account for the disseminated neoplasia.

  9. Dimethylsulfoniopropionate in six species of giant clams and the evolution of dimethylsulfide after death

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.W.; Hill, S.D. [Michigan State Univ., East Lansing, MI (United States). Dept. of Zoology; Dacey, J.W.H. [Woods Hole Oceanographic Inst., Woods Hole, MA (United States). Dept. of Biology; Edward, A. [Micronesia College, Pohnpei (Micronesia, Federated States); Hicks, W.A. [Michigan State Univ., East Lansing, MI (United States). Dept. of Bioichemistry and Molecular Biology

    2004-05-01

    Dimethylsulfoniopropionate (DMSP) could accumulate in large concentrations in animals living symbiotically with algae. The giant clam family Tridacnidae accumulates DMSP because they have a symbiotic relationship with dinoflagellates (or zooxanthellae). In this study, well preserved clam tissues from the western Pacific Islands were analyzed to provide definitive evidence of DMSP in the tissues. Six of the common species in the Tridacnidae family were examined. The objective was to test the hypothesis that dimethyl sulfide (DMS) is released from clam tissues soon after death due to the breakdown of DMSP tissue. In particular, it determined if DMS is responsible for the problem of potent odours and off-taste that have hindered the commercial success of giant clams mariculture. Gas chromatography and mass spectrometry was used in this study to measure DMSP concentrations in siphonal mantle, byssal mantle, adductor muscle and gill tissues. The formation of DMS by tissues after death was documented. It was suggested that since giant clams associate with dinoflagellates, they could accumulate DMSP to high concentrations which could affect multiple properties and functions. It was concluded that the perishability of giant clam tissues is most likely due to the high concentrations of DMS produced one day post mortem. 15 refs., 2 tabs., 4 figs.

  10. Growth and survival of endangered angelwing clam, Pholas orientalis fed different algal diets

    Directory of Open Access Journals (Sweden)

    M. Shirley M. Golez

    2011-12-01

    Full Text Available Mature angelwing clam, Pholas orientalis were collected from the wild and transported tothe laboratory for broodstock development. They were fed with mixed algal cultures of Isochrysisgalbana, Chaetoceros sp., and Tetraselmis sp. for a period of two months and a half to determine theeffects of these algal cultures on growth and survival of the broodstock. Growth in terms of length wasnot significantly different among the treatment groups, whereas, there was significant reduction in theweight of the clams in the group fed with a mixture of Isochrysis galbana, Chaetoceros sp., andTetraselmis sp. Survival of the clams decreased after two months of feeding with algal diets, withsignificant mortality observed in groups fed with a mixture of Isochrysis galbana and Tetraselmis sp. aswell as with the mixture of the three microalgae. All the water quality parameters in the rearing tankswere within the optimum levels required for optimum growth of the clams. These results showed thatmixed algal diets for broodstock development in angelwing clam have no direct effect on growth butmoderate effect on survival. Future studies are aimed towards determining other factors that willcontribute to better growth and survival of angelwing clam broodstock in captivity as well as for thesearch of alternative algal diets for angelwing broodstock, particularly by exploring the microalgae thatare found in their natural habitat.

  11. Microplastic Ingestion by Wild and Cultured Manila Clams (Venerupis philippinarum) from Baynes Sound, British Columbia.

    Science.gov (United States)

    Davidson, Katie; Dudas, Sarah E

    2016-08-01

    Microplastics, plastic particles microplastics are small, they are available to many filter-feeding organisms, which can then be consumed by higher trophic level organisms, including humans. This study documents the quantity of microplastics present in wild and cultured Manila clams (Venerupis philippinarum). Three active shellfish farms and three reference beaches (i.e., non-shellfish farm sites) in Baynes Sound, British Columbia were chosen to examine the microplastic concentrations in wild and cultured Manila clams. Microplastics were isolated using a nitric acid digestion technique and enumerated from 54 clams (27 farmed and 27 non-farmed). Qualitative attributes, such as colour and microplastic type (fiber, fragment, or film) also were recorded. There was no significant difference (F = 1.29; df = 1,4; P = 0.289) between microplastic concentrations in cultured and wild clams. Microplastic concentrations ranged from 0.07 to 5.47 particles/g (from reference beach and shellfish farm clams, respectively). Fibers were the dominant microplastic (90 %); colourless and dark gray fibers were the most common colours observed (36 and 26 %, respectively). Although this indicates that microplastics are definitely present in seafood consumed by humans, shellfish aquaculture operations do not appear to be increasing microplastic concentrations in farmed clams in this region. PMID:27259879

  12. Empirical Analysis of the Typical Breeding Pattern of Clam in Hongdao Town and the Preliminary Estimates of Costs and Benefits

    Institute of Scientific and Technical Information of China (English)

    Xijuan; YANG; Shijun; ZHANG

    2014-01-01

    Based on the survey data about clam breeding farmers in Hongdao Town in August 2011,this paper analyzes the production and operation of typical clam breeding pattern,and estimates the costs and benefits. Through the analysis of operation conditions and economic conditions of Hongdao clam breeding,this paper aims to explore a more reasonable and effective breeding pattern so as to reduce breeding costs and market risks,and increase breeding farmers’ income.

  13. [Are the contours of the frontal section of shell valves in Bivalvia specific?].

    Science.gov (United States)

    Voroshilova, I S

    2013-01-01

    The diagnostic importance of the character of curvature of the frontal section of shell valves in Bivalvia on the basis of determining the constant angle of the logarithmic spiral is discussed. The contours of the frontal section of shell valves in several species of mollusks of the families Margaritiferidae and Sphaeriidae have been analyzed. It is shown that in different species of the family Sphaeriidae, the values of constant angles coincide. While performing graphic constructions, it was established that the contours of the frontal section of all studied species of pearl mussels and some spheriids do not correspond to the segment of the logarithmic spiral. It was noted that the hypothesis of the species specificity of this character was not confirmed; therefore, the curvature of the frontal section of shell valves cannot be used as the main character for the systematics and species identification of bivalves.

  14. Distribution patterns of the Jurassic ostreids (Bivalvia) from Tanggula of China

    Institute of Scientific and Technical Information of China (English)

    沙金庚

    2001-01-01

    Distribution of the Jurassic ostreids (Bivalvia) from Tanggula area of China includes three patterns, which are (1) Tethys: containing Liostrea birmanica and Eligmus rollandi, (2) western Europe and northern Tethys: consisting of Gryphaea (Bilobissa) bilobata; and (3) Global: composed of Actinostreon gregareum and Nanogyra nana. However, they are all limited between palaeolatidudes 60° South and North. Actinostreon gregareum originated in the Sinemurian of northern Chile and it entered Kenya and Madagascar in the Toarcian, but there is no reliable Si-nemurian-Toarcian A. gregareum fossil record in continental margins between Chile and Kenya and Madagascar. Such distribution patterns and dispersal processes have demonstrated that (1) during the Jurassic all seas and oceans were connected to each other; (2) the Tethys and the western European epicontinental seas did produce some endemic taxa; (3) the distribution of these ostreids was most likely controlled by latitudes and creature ecology; and (4) A, gr

  15. Temperature- and parasite-induced changes in toxicity and lethal body burdens of pentachlorophenol in the freshwater clam Pisidium amnicum.

    Science.gov (United States)

    Heinonen, J; Kukkonen, J V; Holopainen, I J

    2001-12-01

    Seasonal variation in abiotic and biotic environments may modify the toxicity of organic chemicals for aquatic organisms. In present study, survival of the freshwater clam Pisidium amnicum was studied in laboratory exposures to pentachlorophenol (PCP) in April (at 5 degress C) and July (at 19 degress C). Behavioral responses, mean survival times (MSTs), and the lethal body burdens (LBBs) of PCP for uninfected clams and for clams infected by digenean trematodes were determined separately in two PCP concentrations, 100 and 300 microgram/L. Analysis of data revealed reduced behavioral activity of the clams in the PCP exposure compared to that in the control. The time needed for toxic responses was greatly affected by temperature; MSTs were 5 to 15 times longer in winter than at summer temperatures. Unexpectedly, the infected clams in summer were more tolerant to PCP than the uninfected clams. Despite the differences in survival times, the LBBs between the seasons were constant. However, in summer, the infected clams had significantly higher LBBs than the uninfected clams. The differences in survival and LBBs between the infected and uninfected clams are suggested to be caused by the high lipid contents found in parasites, which may change the internal distribution of PCP. PMID:11764161

  16. Inventarisatie van de landslakken van de Zeeuwse kust, met de nadruk op de nauwe korfslak Vertigo angustior (Mollusca: Gastropoda).

    NARCIS (Netherlands)

    Boesveld, A.

    2006-01-01

    The distribution of the land snails of the province of Zeeland, with special emphasis on Vertigo angustior (Mollusca: Gastropoda) In 2005 the land snail fauna of the coast of the province of Zeeland was mapped. In total 98 soil and litter samples were taken and on 54 localities records were gathered

  17. The mitochondrial genome of the sipunculid Phascolopsis gouldii supports its association with Annelida rather than Mollusca

    Energy Technology Data Exchange (ETDEWEB)

    Boore, Jeffrey L.; Staton, Joseph

    2001-09-01

    We have determined the sequence of about half (7470 nts) of the mitochondrial genome of the sipunculid Phascolopsis gouldii, the first representative of this phylum to be so studied. All of the 19 identified genes are transcribed from the same DNA strand. The arrangement of these genes is remarkably similar to that of the oligochaete annelid Lumbricus terrestris. Comparison of both the inferred amino acid sequences and the gene arrangements of a variety of diverse metazoan taxa reveals that the phylum Sipuncula is more closely related to Annelida than to Mollusca. This requires reinterpretation of the homology of several embryological features and of patterns of animal body plan evolution.

  18. Record of Phyllidiella zeylanica (Mollusca: Gastropoda: Opisthobranchia after 42 years from Gujarat, India

    Directory of Open Access Journals (Sweden)

    M. Matwal

    2011-07-01

    Full Text Available There are few studies available on Opisthobranch fauna of Gujarat coast. Field surveys were carried out along the Mithapur reef under the “Coral reef restoration programme” of Wildlife Trust of India funded by Tata chemicals and supported by Gujarat State Forest Department and Marine National Park authorities. A species of nudibranch Phyllidiella zeylanica (Mollusca: Gastropoda: Opisthobranchia was recorded for Gujarat after 42 years. This species was last reported by Narayanan in 1968 at Pirotan Islands, Gulf of Kutch Gujarat.

  19. Blastopirellula cremea sp. nov., isolated from a dead ark clam.

    Science.gov (United States)

    Lee, Hae-Won; Roh, Seong Woon; Shin, Na-Ri; Lee, Jina; Whon, Tae Woong; Jung, Mi-Ja; Yun, Ji-Hyun; Kim, Min-Soo; Hyun, Dong-Wook; Kim, Daekyung; Bae, Jin-Woo

    2013-06-01

    Strain LHWP2(T), a novel, aerobic, budding, motile and ovoid bacterium belonging to the phylum Planctomycetes, was isolated from a dead ark clam (Scapharca broughtonii) from the south coast of Korea. Strain LHWP2(T) grew optimally at 30 °C, in the presence of 4% (w/v) NaCl, and at pH 7. The predominant cellular fatty acids were C16:0, C18:1ω7c and/or C18:1ω6c (summed feature 8) and C18:1ω9c. The major isoprenoid quinone was menaquinone-6 (MK-6). The dominant polar lipid was identified as phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain was most closely related to Blastopirellula marina DSM 3645(T), with a 16S rRNA gene sequence similarity of 94.1%. The genomic DNA G+C content of strain LHWP2(T) was 49.5 mol%. Strain LHWP2(T) was distinguished from B. marina DSM 3645(T) based on its optimum salinity, acid production from substrates, assimilation of substrates and DNA G+C content. Overall, these phenotypic, genotypic and phylogenetic data suggest that strain LHWP2(T) should be classified as a novel species belonging to the genus Blastopirellula, for which the name Blastopirellula cremea sp. nov. is proposed. The type strain is LHWP2(T) (=KACC 15559(T)=JCM 17758(T)).

  20. Ornithinibacillus scapharcae sp. nov., isolated from a dead ark clam.

    Science.gov (United States)

    Shin, Na-Ri; Whon, Tae Woong; Kim, Min-Soo; Roh, Seong Woon; Jung, Mi-Ja; Kim, Young-Ok; Bae, Jin-Woo

    2012-01-01

    A novel Gram-positive, aerobic, motile, hemolytic, endospore-forming and rod-shaped bacterium TW25(T) was isolated from a dead ark clam during a mass mortality event on the South coast of Korea. The strain grew optimally at 30°C, at pH 8-9, and with 1% (w/v) NaCl. The 16S rRNA gene sequence analysis indicated that strain TW25(T) was associated with the genus Ornithinibacillus and that it was most closely related to the type strain of Ornithinibacillus californiensis (98.5% similarity). The dominant cellular fatty acids were iso-C15:0, anteiso-C15:0 and C16:0. The peptidoglycan amino acid type was A4β, containing L: -ornithine and D: -aspartic acid. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, four unidentified phospholipids, two unidentified aminolipids and two unidentified lipids. The major respiratory quinone was menaquinone-7 (MK-7). The G + C content of genomic DNA was 36.7 mol%. DNA-DNA hybridization experiments with related strains revealed lower than 11 ± 3% relatedness. Based on this polyphasic taxonomic study, strain TW25(T) represents a novel species in the genus Ornithinibacillus, for which the name Ornithinibacillus scapharcae sp. nov. is proposed. The type strain is TW25(T) (=KACC 15116(T) = JCM 17314(T)).

  1. Transcriptomic responses to low temperature stress in the Manila clam, Ruditapes philippinarum.

    Science.gov (United States)

    Nie, Hongtao; Jiang, Liwen; Huo, Zhongming; Liu, Lianhui; Yang, Feng; Yan, Xiwu

    2016-08-01

    The Manila clam, Ruditapes philippinarum, is an economically important shellfish in marine aquaculture, with a broad thermal tolerance. The ability to cope with cold stress is quite important for the survival of aquatic species under natural conditions. A cold-tolerant clam that can survive the winter at temperatures below 0 °C might extend our understanding of the mechanisms underlying the response to cold stress. In this study, the transcriptional response of the Manila clam to cold stress (-1 °C) was characterized using RNA sequencing. The transcriptomes of a cold-treatment (O) group of clams, which survived under cold stress, and the control group (OC2), which was not subjected to cold stress, were sequenced with the Illumina HiSeq platform. In all, 148,593 unigenes were generated. Compared with the unigene expression profile of the control group, 1760 unigenes were up regulated and 2147 unigenes were down regulated in the O group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that signal transduction, mitochondrial metabolism, cellular component organization or biogenesis, and energy production processes were the most highly enriched pathways among the genes that were differentially expressed under cold stress. All these pathways could be assigned to the following biological functions in the cold-tolerant Manila clam: signal response to cold stress, antioxidant response, cell proliferation, and energy production. PMID:27288255

  2. Immune- and Pollution-mediated DNA Damage in Two Wild Mya arenaria Clam Populations

    Directory of Open Access Journals (Sweden)

    François Gagné

    2009-01-01

    Full Text Available In aquatic environments, genotoxicity results from the effects of pollution combined with the inflammatory response triggered by the immune system. Indeed, the production of nitrosylated DNA and proteins are though to arise from the production of peroxinitrite during phagocytosis and inflammation. The purpose of this study was to examine new DNA biomarkers that differentiate between immune- and pollution-mediated genotoxicity in wild clam populations. Intertidal clam populations were sampled and analyzed for gonadal DNA strand breaks, DNA nitrosylation and xanthine oxidoreductase (XOR activity (purine salvage pathway. The clam weight-to-shell-length ratio, the gonado-somatic index (GSI, age status, lipid peroxidation, xenobiotic conjugation activity (glutathione S-transferase (GST and phagocytic activity were examined to shed light on their relationships with the observed genotoxic endpoints. XOR activity and DNA strand breaks were generally elevated at polluted sites and correlated significantly with clam weight-to-shell-length ratios and DNA nitrosylation. DNA nitrosylation was also higher at some sites and correlated significantly with phagocytic activity and with DNA strand breaks. This study showed that DNA strand breaks were associated with both immune- and pollution-mediated effects. This suggests that there is a loss of DNA repair capacity due to the combined effects of aging, pollution and immune response in wild clam populations that are impacted by anthropogenic activity.

  3. Impediment to symbiosis establishment between giant clams and Symbiodinium algae due to sterilization of seawater.

    Directory of Open Access Journals (Sweden)

    Takeo Kurihara

    Full Text Available To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment ("symbiosis rate" is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-µm filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds.

  4. Change in metallothionein phosphorylation state in Mya arenaria clams: implication in metal metabolism and oxidative stress

    Directory of Open Access Journals (Sweden)

    F Gagné

    2010-01-01

    Full Text Available The contamination of the benthic environment poses a threat to long-lived sessile organisms such as clams. The purpose of this study was to investigate metal contamination in tissues and changes in metallothioneins (MT in respect to its redox status in Mya arenaria clams collected at three polluted sites. The phosphorylation state of MT was also investigated to determine whether this state is changed in clams collected at heavy-metal contaminated site and its involvement in cytoprotective signaling during stress contamination. The results show that clams collected at least one of the three polluted sites presented significantly higher concentrations of silver (Ag, arsenic (As, cobalt (Co, copper (Cu, mercury (Hg, nickel (Ni, tin (Sn and lead (Pb in tissues. In the visceral tissue, total MT levels and the reduced, metal-binding form of the protein were significantly induced at the sites. The phosphorylation of MT and mitochondrial activity, as determined by electron transport and cytochrome c oxidase activities, were also significantly reduced at the contaminated sites. Reduced phosphate levels in MT were negatively correlated with total MT levels, suggesting that decreased phosphorylation was involved in kinase-mediated signaling during cellular stress and could possibly alter the protein’s affinity to confer cytoprotection against heavy metal contamination. These preliminary investigations revealed that the phosphorylation state could change in polluted environment and provide some clues on the modulation of binding affinities during heavy-metal and oxidative stress in clams.

  5. Transcriptomic responses to low temperature stress in the Manila clam, Ruditapes philippinarum.

    Science.gov (United States)

    Nie, Hongtao; Jiang, Liwen; Huo, Zhongming; Liu, Lianhui; Yang, Feng; Yan, Xiwu

    2016-08-01

    The Manila clam, Ruditapes philippinarum, is an economically important shellfish in marine aquaculture, with a broad thermal tolerance. The ability to cope with cold stress is quite important for the survival of aquatic species under natural conditions. A cold-tolerant clam that can survive the winter at temperatures below 0 °C might extend our understanding of the mechanisms underlying the response to cold stress. In this study, the transcriptional response of the Manila clam to cold stress (-1 °C) was characterized using RNA sequencing. The transcriptomes of a cold-treatment (O) group of clams, which survived under cold stress, and the control group (OC2), which was not subjected to cold stress, were sequenced with the Illumina HiSeq platform. In all, 148,593 unigenes were generated. Compared with the unigene expression profile of the control group, 1760 unigenes were up regulated and 2147 unigenes were down regulated in the O group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that signal transduction, mitochondrial metabolism, cellular component organization or biogenesis, and energy production processes were the most highly enriched pathways among the genes that were differentially expressed under cold stress. All these pathways could be assigned to the following biological functions in the cold-tolerant Manila clam: signal response to cold stress, antioxidant response, cell proliferation, and energy production.

  6. Assessment of thermo-mechanical behavior in CLAM steel first wall structures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Fubin, E-mail: liufubin_1216@126.com [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China); Yao Man, E-mail: yaoman@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer China Low Activation Martensitic steel (CLAM) as FW the structural material. Black-Right-Pointing-Pointer The thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating. Black-Right-Pointing-Pointer The temperature dependence of the material physical properties of CLAM is summarized. - Abstract: The temperature and strain distributions of the mockup with distinct structural material (SS316L or China Low Activation Martensitic steel (CLAM)) in two-dimensional model were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2 MW/m{sup 2}. The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating.

  7. Impediment to Symbiosis Establishment between Giant Clams and Symbiodinium Algae Due to Sterilization of Seawater

    Science.gov (United States)

    Kurihara, Takeo; Yamada, Hideaki; Inoue, Ken; Iwai, Kenji; Hatta, Masayuki

    2013-01-01

    To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment (“symbiosis rate”) is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-µm filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds. PMID:23613802

  8. Quantitative Real-Time PCR Assay for QPX (Thraustochytriidae), a Parasite of the Hard Clam (Mercenaria mercenaria)▿

    OpenAIRE

    Liu, Qianqian; Allam, Bassem; Collier, Jackie L.

    2009-01-01

    We developed a real-time quantitative PCR (qPCR) assay targeting the rRNA internal transcribed spacer region of the hard clam pathogen QPX. The qPCR assay was more sensitive than was histology in detecting clams with light QPX infections. QPX was detected in 4 of 43 sediment samples but in none of 40 seawater samples.

  9. Toxicological evaluation of two pedigrees of clam Ruditapes philippinarum as bioindicators of heavy metal contaminants using metabolomics.

    Science.gov (United States)

    Ji, Chenglong; Cao, Lulu; Li, Fei

    2015-03-01

    Heavy metal pollution has been of great concern in the Bohai marine environment. Manila clam Ruditapes philippinarum has been used as a bioindicator in marine toxicology. In this study, NMR-based metabolomics was used to ascertain whether there were significant biological differences between two dominant pedigrees (White and Zebra) of clam and evaluate the suitability of two pedigrees for marine environmental toxicology, together with antioxidant enzymatic analysis. Our results indicated that there were significant biological differences between White and Zebra clams based on the metabolic profiles and antioxidant enzyme activities. In details, the metabolic profiles showed higher levels of amino acids and succinate in Zebra clam digestive glands and higher levels of ATP in White clam digestive glands, respectively. The superoxide dismutase activities in control White and Zebra clam samples were significantly different. Additionally, White clam was more sensitive to Cd based on the significant accumulation of Cd, antioxidant enzymatic alterations and sensitive metabolic changes. Overall, we concluded that White clam could be a preferable bioindicator for marine environmental toxicology. PMID:25681705

  10. Biocenosis de Bivalvia y Polyplacophora del intermareal rocoso en playa Tlacopanocha, Acapulco, Guerrero, México Polyplacophora and Bivalvia biocenosis at rocky intertidal Tlacopanocha beach, Acapulco, Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    Lizeth Galeana-Rebolledo

    2012-11-01

    Full Text Available El Estado de Guerrero, México, tiene regiones marinas prioritarias para la conservación de su biodiversidad y la información acerca de la diversidad de moluscos es escasa, por lo que es necesario realizar inventarios de especies, estudios de ecología de poblaciones y comunidades. Este estudio se efectuó en el intermareal rocoso de la playa Tlacopanocha. Los objetivos fueron: determinar la riqueza, densidad y diversidad de especies; analizar la composición de especies y estructura de tallas. El área de muestreo fue de 10 m² y la unidad de muestreó fue de 1 m². Se identificaron 35 especies, de las cuales tres son nuevos registros para el intermareal rocoso de Guerrero: las familias mejor representadas en riqueza de especies fueron Ischnochitonidae y Arcidae, y en abundancia Chitonidae y Chamidae; la densidad fue de 31,60 ind m-2. Polyplacophora presentó 42,9% de especies dominantes y Bivalvia 19,0%. Chama corallina presentó la mayor talla en longitud y Chama sordida en ancho. La riqueza de especies de moluscos registrada se considera alta y corresponde a lo esperado para un sustrato rocoso en zona tropical. Polyplacophora presentó alta composición de especies, que podría ser resultado de la adaptación de los organismos a las condiciones dinámicas del intermareal rocoso. Los nuevos registros indican la importancia de los inventarios de especies y también del conocimiento de las poblaciones y comunidades de la fauna marina de Guerrero.The State of Guerrero, Mexico, has priority marine areas for conservation of its biodiversity, but information concerning diversity of mollusks is limited, so it is convenient to carry out species inventories, studies of populations and community ecology. This study was conducted in the intertidal rocky beach Tlacopanocha. The objectives were to determine richness, density and species diversity, analyze the species composition and size structure. The sampling area was 10 m² and the sampling unit was

  11. Review on the Risk Assessment of Heavy Metals in Malaysian Clams.

    Science.gov (United States)

    Hossen, Md Faruk; Hamdan, Sinin; Rahman, Md Rezaur

    2015-01-01

    The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight) of these heavy metals ranged around 0.18-8.51, 0.13-17.20, 2.17-7.80, 0.84-36.00, 24.13-368.00, and 177.82-1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985), about 30% and more than 50% sites are safe from Cd and Pb contamination, respectively, and also the clam species from the other populations studied were safe for consumption. PMID:26060840

  12. Review on the Risk Assessment of Heavy Metals in Malaysian Clams

    Directory of Open Access Journals (Sweden)

    Md. Faruk Hossen

    2015-01-01

    Full Text Available The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight of these heavy metals ranged around 0.18–8.51, 0.13–17.20, 2.17–7.80, 0.84–36.00, 24.13–368.00, and 177.82–1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985, about 30% and more than 50% sites are safe from Cd and Pb contamination, respectively, and also the clam species from the other populations studied were safe for consumption.

  13. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Razor clams are often exposed to coastal eutrophication. • The bioaccumulation of Fe, Ni, V, and As was promoted by eutrophication. • Bionic gastrointestinal tract was used for metal oral bioavailability assessment. • Eutrophication decreased oral bioavailability of Fe and Pb but enhanced for V. • The daily maximum allowable intakes are controlled by eutrophication levels. - Abstract: As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams

  14. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Tengxiu [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing, E-mail: lishunxing@mnnu.edu.cn [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China); Chen, Lihui [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Zheng, Fengying; Huang, Xu-Guang [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China)

    2014-10-15

    Graphical abstract: - Highlights: • Razor clams are often exposed to coastal eutrophication. • The bioaccumulation of Fe, Ni, V, and As was promoted by eutrophication. • Bionic gastrointestinal tract was used for metal oral bioavailability assessment. • Eutrophication decreased oral bioavailability of Fe and Pb but enhanced for V. • The daily maximum allowable intakes are controlled by eutrophication levels. - Abstract: As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams.

  15. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    Science.gov (United States)

    Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-01

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  16. Code aus einem Forschungskontext mit CLAM in einen Web-Service verwandeln

    OpenAIRE

    Matteo Romanello

    2016-01-01

    Poster bei dem von CLARIN-D veranstaltetem CA3 Forum im Hamburg. Der Computational Linguistics Application Mediator (CLAM) ist ein im Rahmen von CLARIN-NL entwickeltes Python Tool, das darauf abzielt, die Transformation von Code aus einem Forschungskontext in einen Web-Service zu vereinfachen (van Gompel & Reynaert 2014). Während der HandsOn Session wird die CLAM Anwendung am Beispiel des für meine Promotion entwickelte Programms vorge...

  17. Review on the Risk Assessment of Heavy Metals in Malaysian Clams

    OpenAIRE

    Md. Faruk Hossen; Sinin Hamdan; Md. Rezaur Rahman

    2015-01-01

    The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight) of these heavy metals ranged around 0.18–8.51, 0.13–17.20, 2.17–7.80, 0.84–36.00, 24.13–368.00, and 177.82–1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985), ab...

  18. Systematics and distribution of Cristaria plicata (Bivalvia, Unionidae) from the Russian Far East

    Science.gov (United States)

    Klishko, Olga K.; Lopes-Lima, Manuel; Froufe, Elsa; Bogan, Arthur E.; Abakumova, Vera Y.

    2016-01-01

    Abstract The number of anodontine bivalve species placed in the genus Cristaria (Bivalvia, Unionidae) from the Russian Far East is still not stable among authors. Some recognize only one valid species Cristaria plicata (Leach, 1815) while others accept two additional species, Cristaria tuberculata Schumacher, 1817 and Cristaria herculea (Middendorff, 1847). In the present study, these taxonomic doubts are addressed using analyses of mitochondrial DNA sequences and shell morphometry. No significant differences have been revealed by the COI DNA sequences or the main statistical morphometric indices from the three Cristaria forms. In the specimens analysed, changes in shell morphometry with age suggest that original descriptions of the different forms may be attributed solely to differences in age and sex. We consider that Cristaria plicata, Cristaria tuberculata and Cristaria herculea from the Russian Far East should be considered as a single species, namely Cristaria plicata (Leach, 1815), with Cristaria tuberculata and Cristaria herculea as junior synonyms. The geographic range of Cristaria plicata and its conservation status are also presented here. PMID:27110206

  19. Multidrug-resistant and epidemic clones of Escherichia coli from natural beds of Venus clam.

    Science.gov (United States)

    Vignaroli, C; Di Sante, L; Leoni, F; Chierichetti, S; Ottaviani, D; Citterio, B; Biavasco, F

    2016-10-01

    Epidemic Escherichia coli clones have been recovered in marine sediment along the coast of Marche, an Adriatic region in central Italy. In the present study, E. coli strains from the clam Chamelea gallina, sampled from seven natural beds in the same area, were detected. Selected E. coli isolates from all sampling sites were screened for antimicrobial susceptibility, genetic diversity and correlation. The majority (60%) belonged to phylogroups A or B1, 31% to the other groups (B2, C, D, E, F), 8% to cryptic clades, and 1% were untypable. Moreover, 33.3% of isolates were resistant to at least one drug and 11% were multidrug resistant (MDR). The most common resistance was to tetracycline, ampicillin, and streptomycin. No clonality was detected, but the strains' high genetic heterogeneity pointed at multiple sources of microbiological contamination. MLST analysis found potentially pathogenic and even epidemic MDR strains in clams collected in class A (ST746 and ST46) and class B (ST393, ST58 and ST131) areas, indicating that strains of clinical origin are detectable in clams. These data highlight that eating raw or lightly cooked clams may pose a health risk if purification is not performed or is ineffective. PMID:27375238

  20. Habitat Descriptionof the Threatened Freshwater Clam, Galatea paradoxa (Born 1778 at the Volta Estuary, Ghana

    Directory of Open Access Journals (Sweden)

    K.A. Obirikorang

    2013-12-01

    Full Text Available This research was conducted to at two of the few remaining habitats of the threatened freshwater clam (Galatea paradoxa at the Volta Estuary in Ghana to describe the current state of the clam habitat with respect to the physicochemical water parameters and the characterize the bottom sediment on which they thrive. The research was carried out over an 18-month period with the aim of facilitating the transplanting of juvenile clams from their natural habitats to portions of the estuarine environments with similar physicochemical and characteristics which will consequently lead to the conservation of the clampopulation and expansion of the clam habitat. The measured physicochemical water parameters were fairly similar at the two locations and exhibited temporal fluctuations which could be attributed to seasonal changes as well as anthropogenic activities within the catchment of the sampling locations.The results of the grain size analyses revealed very low sedimentological diversity and it was observed that the estuarine sediments fall under the sandy textural group (>95% which characterized both sampling locations in the Estuary.

  1. Microstructures and Mechanical Properties of Laser Welding Joint of a CLAM Steel with Revised Chemical Compositions

    Science.gov (United States)

    Chen, Shuhai; Huang, Jihua; Lu, Qi; Zhao, Xingke

    2016-05-01

    To suppress the tendency to form delta ferrite in weld metal (WM) of China low activation martensitic (CLAM) steel joint, a CLAM steel with revised chemical compositions was designed. Laser welding of the CLAM steel was investigated. The microstructures of the WM and heat-affected zone were analyzed. The impact toughness of the WM was evaluated by a Charpy impact test method with three V notches. The influence of temper temperature on mechanical properties was analyzed. It was found that the delta ferrite was eliminated almost completely in laser WM of CLAM steel with revised chemical compositions which has lower tendency to form delta ferrite than original chemical compositions. The joint has higher tensile strength than the parent metal. With increasing the heat input, the impact toughness of the joint is approximatively equal with that of parent metal first and then decreases obviously. Temper treatment could effectively improve mechanical property of the joint. When the temper temperature exceeds 600 °C, the impact toughness of the joint is higher than that of the parent metal.

  2. Effect of Epinephrine on the Settlement and Metamorphosis of Manila Clam Larvae

    Institute of Scientific and Technical Information of China (English)

    LU Sumin; BAO Zhenmin; LIU Hui; FANG Jianguang

    2006-01-01

    Chemical inducement and DDRT-PCR (differential display reverse transcription PCR) are adopted to investigate the effect of epinephrine (EPI) on the settlement and metamorphosis of Manila clam larvae. Chemical inducement shows that EPI has an effect to some extent on the metamorphosis of Manila clam larvae at all concentrations and in all treatments designed. The most significant result of inducement is obtained at the concentration of 10-6 molL-1 and for 4 h. DDRT-PCR using six primer pairs shows that the gene expression pattern is quite different between EPI treatment and the control. Three hundred and forty-three amplification bands are obtained in total, among which, 67 (19.53%) are differentially appeared.Therefore, EPI has an effect on the gene expression of the eye spot larval Manila clam. It can be hypothesized that EPI is a settlement and metamorphosis inducer for Manila clam. EPI may lead to larvae settlement and metamorphosis by binding to the receptors on the membrane and then changing the gene expression of larvae cells.

  3. CLAM - CoLlAborative eMbedded networks for submarine surveillance: An overview

    NARCIS (Netherlands)

    Meratnia, Nirvana; Havinga, Paul J.M.; Casari, Paolo; Petrioli, Chiara; Grythe, Knut; Husoy, Thor; Zorzi, Michele

    2011-01-01

    This paper provides an overview of the CLAM project, which aims at developing a collaborative embedded monitoring and control platform for submarine surveillance by combining cutting edge acoustic vector sensor technology and 1D, 2D, 3D sensor arrays, underwater wireless sensor networks protocol des

  4. The clam (Chamelea gallina: evaluation of the effects of solids suspended in seawater on bivalve molluscs

    Directory of Open Access Journals (Sweden)

    Salvatora Angela Angioni

    2010-03-01

    Full Text Available The study was designed to evaluate the effects of solids in suspension in seawater on clams (Chamelea gallina. The aim was to investigate the possible correlation between the widespread deaths of clams in the coastal waters of the central and northern Adriatic in the last five years and increased concentrations of solids in suspension. The research involved conducting 96-hour tests on clams farmed in aquariums containing filtered seawater. The tests were preceded by a 7-day adaptation stage to allow the molluscs to acclimatise. During this period, the clams were fed on unicellular seaweed (Dunaliella tertiolecta. The molluscs were exposed to particles of solids in suspension consisting of pools of silica gel (SiO2 granules of various sizes, similar to those constituting silt, whose presence and suspension in the sea considerably increase after heavy rain and heavy seas. The study established that the number of deaths caused by solids suspended in seawater at the concentrations used in the tests was not statistically significant.

  5. First molluscan antimicrobial peptide hydramacin in Manila clam:molecular characterization and expression analysis

    Institute of Scientific and Technical Information of China (English)

    Youngdeuk Lee; Saranya Revathy K; Sukkyoung Lee; Ilson Whang; Chulhong Oh; Do-Hyung Kang; Gee-Wook Shin; Jehee Lee; Mahanama De Zoysa

    2014-01-01

    Objective:To investigate molecular characterization and the immune responses of Manila clam hydramacin (Rp-hdmc). Methods:cDNA sequence of hydramacin was isolated from Manila clam transcriptome database. Molecular characterization of hydramacin cDNA was performed by BLAST and SWISS-MODEL bioinformatics programs. Tissue-specific expression and transcriptional regulation after Vibrio tapetis challenge was done by quantitative real time PCR. Results:Rp-hdmc has 291 bp open reading frame (ORF), encoding 97 amino acids with a mature hydramacin consisting of 77 amino acid residues. In un-challenged clam, Rp-hdmc was constitutively expressed in all tested tissues and the highest expression level was detected in gill. After pathogenic bacteria Vibrio tapetis challenge, Rp-hdmc mRNA was up-regulated in gill and hemocytes. Conclusions: We identified hydramacin cDNA (Rp-hdmc) from mollusk Manila clam that shows the characteristic features of hydramacin sequence. It has eight cysteine residues with four disulfide linkages, three helices and twoβ-strands in secondary structure. Expression results after V. tapetis challenges suggest that Rp-hdmc is involved in immune response against pathogenic bacteria.

  6. Native and introduced clams biochemical responses to salinity and pH changes.

    Science.gov (United States)

    Velez, Catia; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

    2016-10-01

    By the end of year 2100 physiological and biochemical performance of aquatic organisms are expected to become strongly affected by salinity and pH shifts, which in turn may favor the conditions for introduced species to invade new ecosystem areas. Given this, we evaluated the effects of salinity and pH changes in native Ruditapes decussatus and introduced Ruditapes philippinarum clams, by measuring different biomarkers related to oxidative stress, metabolic activity and osmoregulation capacity. Results showed that extreme salinities induced mortality in both species, while all clams survived under low pH (7.3). Both species mobilized glycogen as a source of energy towards cells protection mechanisms under extreme salinities. The native species presented higher lipid peroxidation levels while the introduced species was able to prevent oxidative damages through the induction of antioxidant enzymes at most extreme salinities. R. philippinarum also induced CA activity to balance the ion homeostasis at extreme salinities. In contrast, low pH induced oxidative damages, an increase of antioxidant (catalase), detoxification (glutathione S-transferases) and osmoregulation (carbonic anhydrase) mechanisms in R. philippinarum compared to the native clams. Overall, salinity and pH changes can alter physiological and biochemical status of native and introduced clam species. PMID:27220103

  7. Accumulation and tissue distribution of radioiodine (131I) from algal phytoplankton by the freshwater clam Corbicula manilensis

    International Nuclear Information System (INIS)

    Radioactive wastes discharged from establishments involved in the use of radioisotopes such as nuclear-powered industries, tracer research and nuclear medicine are a potential public health hazard. Such wastes contain radionuclides, particularly Iodine-131 (131I), produced in fission with a yield of about 3%. Radionuclides in waste waters are known to be taken up by molluscs such as mussels, oysters, and clams. This study aims to determine the uptake of 131I from algal phytoplankton (Chroococcus dispersus) fed to the freshwater clam Corbicula manilensis as well as the organ/tissue distribution. The results will be compared with a previous study on 131I uptake from water by the same clams

  8. Characterization of brevetoxin metabolism in Karenia brevis bloom-exposed clams (Mercenaria sp.) by LC-MS/MS.

    Science.gov (United States)

    Abraham, Ann; Wang, Yuesong; El Said, Kathleen R; Plakas, Steven M

    2012-11-01

    Brevetoxin metabolites were identified and characterized in the hard clam (Mercenaria sp.) after natural exposure to Karenia brevis blooms by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal brevetoxins BTX-1 and BTX-2 produced by K. brevis were not detectable in clams. Metabolites of these brevetoxins found in clams included products of oxidation, reduction, hydrolysis and amino acid/fatty acid conjugation. Of highest abundance were cysteine and taurine conjugates. We also found glutathione, glycine-cysteine, and γ-glutamyl-cysteine conjugates. A series of fatty acid derivatives of cysteine-brevetoxin conjugates were also identified. PMID:22884629

  9. On the establishment of two more alien mollusca (Chama aspersa Reeve, 1846 and Chama asperella Lamarck, 1819 in the eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    P. OVALIS

    2012-12-01

    Full Text Available The Indo-Pacific bivalvia Chama aspersa Reeve, 1846 and Chama asperella Lamarck, 1819 are recorded for the first time in Greek waters. These findings represent a considerable expansion in the eastern Mediterranean. Ship fouling is assumed as the most probable transportation means. However, natural dispersal via the Suez Canal is feasible as well.

  10. Molecular phylogenetics in 2D: ITS2 rRNA evolution and sequence-structure barcode from Veneridae to Bivalvia.

    Science.gov (United States)

    Salvi, Daniele; Mariottini, Paolo

    2012-11-01

    In this study, we analyzed the nuclear ITS2 rRNA primary sequence and secondary structure in Veneridae and comparatively with 20 Bivalvia taxa to test the phylogenetic resolution of this marker and its suitability for molecular diagnosis at different taxonomic levels. Maximum likelihood and Bayesian trees based on primary sequences were congruent with (profile-) neighbor-joining trees based on a combined model of sequence-structure evolution. ITS2 showed higher resolution below the subfamily level, providing a phylogenetic signal comparable to (mitochondrial/nuclear) gene fragments 2-5 times longer. Structural elements of the ITS2 folding, such as specific mismatch pairing and compensatory base changes, provided further support for the monophyly of some groups and for their phylogenetic relationships. Veneridae ITS2 folding is structured in six domains (DI-VI) and shows five striking sequence-structure features. Two of them, the Basal and Apical STEMs, are common to Bivalvia, while the presence of both the Branched STEM and the Y/R stretches occurs in five superfamilies of the two Heterodonta orders Myoida and Veneroida, thus questioning their reciprocal monophyly. Our results validated the ITS2 as a suitable marker for venerids phylogenetics and taxonomy, and underlined the significance of including secondary structure information for both applications at several systematic levels within bivalves.

  11. Accumulation of petroleum hydrocarbons and heavy metals in clams (Ruditapes philippinarum) in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    MA Haiqing; SONG Qian; WANG Xuchen

    2009-01-01

    Accumulation and distributions of aliphatic and polyaromatic hydrocarbons (PAHs) and heavy metals were measured in tissues of the clam Ruditapes philippinarum collected from 5 sites in Jiaozhou Bay, Qingdao, China. The concentrations of total aliphatic hydrocarbon and PAHs ranged from 570 to 2 574 ng/gdw (gram dry weight) and from 276 to 939 ng/gdw, in the most and least polluted sites, respectively. The bio-accumulation of hydrocarbons and PAHs in the clams appeared to be selective. Aliphatic hydrocarbons were predominantly represented by short chain (clams was probably related to the physiological and bio-kinetic processes that were energetically favorable for uptake of compounds with fewer rings. Accumulation of the metals Cd, Cu, Zn, Pb, Cr, Hg, and As in the clam tissues also showed high variability, ranging from 0.043 to 87μg/gdw. Among the 7 detected metals, Zn, Cd, Cu, and As had a particularly high potential of accumulation in R. philippinarum. In general, a positive correlation was found between the tissue concentrations and sediment concentrations of hydrocarbons and of some metals. Our study suggests that moderate contamination with polyaromatic hydrocarbons, and low to moderate contamination with metals, currently exists for clam R. philippinarum in Jiaozhou Bay, in comparison with other regional studies. A long-term monitoring program is certainly needed for assessment of the potential ecological influence and toxicity of these contaminants of R. philippinarum in Jiaozhou Bay.

  12. Gene transcription and biomarker responses in the clam Ruditapes philippinarum after exposure to ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Milan, Massimo; Pauletto, Marianna; Patarnello, Tomaso; Bargelloni, Luca [Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell' Universita 16, Legnaro (Padova) (Italy); Marin, Maria Gabriella [Department of Biology, University of Padova, Via Ugo Bassi 58/B, 35131 Padova (Italy); Matozzo, Valerio, E-mail: matozzo@bio.unipd.it [Department of Biology, University of Padova, Via Ugo Bassi 58/B, 35131 Padova (Italy)

    2013-01-15

    Pharmaceuticals are a class of emerging environmental contaminants that continuously enter aquatic environments. Presently, little information is available about the effects of these substances on non-target organisms, such as bivalves. We investigated the effects of ibuprofen (IBU) on the clam Ruditapes philippinarum. Clams were exposed for 1, 3, 5 and 7 days to 0, 100 and 1000 {mu}g IBU/L, and established biomarker responses (haemolymph lysozyme, gill acetylcholinesterase and digestive gland superoxide dismutase activities) as well as digestive gland transcriptome were evaluated. A two-way ANOVA revealed significant effects of both 'IBU concentration' and 'exposure duration' on biomarker responses. Overall, the enzyme activities were generally lower in IBU-exposed clams than in controls. Although limited knowledge of the mollusc transcriptome makes it difficult to interpret the effects of IBU on clams, the gene transcription analysis using DNA microarrays enabled the identification of the putative molecular mode of action of the IBU. The functional analysis of differentially transcribed genes suggests that IBU can interfere with various signalling pathways in clams, such as arachidonic acid metabolism, apoptosis, peroxisomal proliferator-activated receptors, and nuclear factor-kappa B. In addition, several genes involved in the metabolism of xenobiotics (e.g., glutathione S-transferase, sulfotransferase, cytochrome P450) were also found to be significantly affected by IBU exposure. In summary, the integrated approach of gene transcription analysis and biomarker responses facilitated the elucidation of the putative mechanisms of action of IBU in non-target species.

  13. Transcriptome sequencing and microarray development for the Manila clam, Ruditapes philippinarum: genomic tools for environmental monitoring

    Directory of Open Access Journals (Sweden)

    Patarnello Tomaso

    2011-05-01

    Full Text Available Abstract Background The Manila clam, Ruditapes philippinarum, is one of the major aquaculture species in the world and a potential sentinel organism for monitoring the status of marine ecosystems. However, genomic resources for R. philippinarum are still extremely limited. Global analysis of gene expression profiles is increasingly used to evaluate the biological effects of various environmental stressors on aquatic animals under either artificial conditions or in the wild. Here, we report on the development of a transcriptomic platform for global gene expression profiling in the Manila clam. Results A normalized cDNA library representing a mixture of adult tissues was sequenced using a ultra high-throughput sequencing technology (Roche 454. A database consisting of 32,606 unique transcripts was constructed, 9,747 (30% of which could be annotated by similarity. An oligo-DNA microarray platform was designed and applied to profile gene expression of digestive gland and gills. Functional annotation of differentially expressed genes between different tissues was performed by enrichment analysis. Expression of Natural Antisense Transcripts (NAT analysis was also performed and bi-directional transcription appears a common phenomenon in the R. philippinarum transcriptome. A preliminary study on clam samples collected in a highly polluted area of the Venice Lagoon demonstrated the applicability of genomic tools to environmental monitoring. Conclusions The transcriptomic platform developed for the Manila clam confirmed the high level of reproducibility of current microarray technology. Next-generation sequencing provided a good representation of the clam transcriptome. Despite the known limitations in transcript annotation and sequence coverage for non model species, sufficient information was obtained to identify a large set of genes potentially involved in cellular response to environmental stress.

  14. Winter distribution, density and size of Mesodesma mactroides (Bivalvia, Mactracea in Monte Hermoso beach (Argentina

    Directory of Open Access Journals (Sweden)

    Sandra Marcela Fiori

    2004-03-01

    Full Text Available The yellow clam Mesodesma mactroides (Deshayes, 1854 is a seasonal migrant that moves in spring to the sandy upper intertidal level. In this paper we analyze the spatial distribution of density and mean shell size of the yellow clam population in Monte Hermoso beach (Argentina in winter 1995, i.e., three months before the mass mortality occurred in November 1995. Sampling covered 32 km of beach, with a regular design of 22 transects. The major environmental gradient in the beach was determined using principal component analysis (PCA on the correlation matrix of the environmental data (beach morphology, slope, and sand granulometry. Correlation analysis was used to assess the relationship between the score of a site (transect on the first and second principal component, and clam mean density and mean shell size. Most of the beach seems to be habitable for clams, their spatial heterogeneity not having been explained by the measured variables since, although the first axis of the PCA has demonstrated an E-W physical gradient, clam density was not in correlation with it. Density was maximum near the piers, even though these are points with high tourist activity. It seems that non-extractive touristic activities do not affect population density but rather mean shell size, probably due to reduction of growth rates. The abundance of the winter population, as compared with the assessment done after the mass mortality of November, strongly suggests that a great part of the population was overwintering in the intertidal fringe.O molusco Mesodesma mactroides (Deshayes, 1854 é uma espécie migrante sazonal que na primavera move-se para o nível entremarés superior da praia. Neste estudo, analisamos a distribuição espacial da densidade e o tamanho médio da população do bivalve na praia de Monte Hermoso (Argentina no inverno de 1995, i. é, três meses antes da mortalidade massiva desses moluscos, acontecida em novembro de 1995. A amostragem cobriu 32

  15. Intersex in the clam Scrobicularia plana (Da Costa): Widespread occurrence in English Channel estuaries and surrounding areas.

    Science.gov (United States)

    Pope, N D; Childs, K; Dang, C; Davey, M S; O'Hara, S C M; Langston, K; Minier, C; Pascoe, P L; Shortridge, E; Langston, W J

    2015-06-30

    Estuarine clams Scrobicularia plana were sampled from 108 intertidal locations around the English Channel and adjacent areas. Although S. plana is believed to be a strict gonochorist, 58% of the populations sampled included intersexed individuals (described as male clams exhibiting ovotestis). Over the entire region, on average, 8.6% of male clams exhibited intersex, although proportions of affected males ranged from 0% to 53% depending on location. The severity of intersex was assessed using a simple classification scale, with the majority of individuals showing low levels of impact. Sex ratios were significantly skewed at some sites. There were no significant relationships between incidence or severity of intersex; or with size or parasitism of individual clams. Intersex in S. plana is a useful tool to assess endocrine disruptive effects in estuaries, although mechanisms of impact and causative agents remain uncertain. PMID:25837773

  16. Giant clams and rising CO2: light may ameliorate effects of ocean acidification on a solar-powered animal

    OpenAIRE

    Sue-Ann Watson

    2015-01-01

    Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and ...

  17. Soft-shell clam (Mya arenaria) p53: A structural and functional comparison to human p53

    OpenAIRE

    Holbrook, Lauren A.C.; Butler, Rondi A.; Cashon, Robert E.; Van Beneden, Rebecca J.

    2008-01-01

    The tumor suppressor p53 regulates genes involved in progression through the cell cycle, DNA repair, senescence or apoptosis in response to cell stress. Dysregulation of p53 can result in uncontrolled cellular proliferation. Invertebrate homologues to human p53 (Hsp53) have been identified, including a putative p53 gene (Map53) from the soft-shell clam (Mya arenaria). Predicted sequences for human and clam p53 proteins exhibit conservation in key domains. In light of this similarity, and the ...

  18. Influence of environmental variables on the abundance of estuarine clam Meretrix casta (Chemnitz, 1782 in Trang Province, Southern Thailand

    Directory of Open Access Journals (Sweden)

    Prasert Tongnunui

    2011-02-01

    Full Text Available The estuarine clam Meretrix casta (Chemnitz, 1782 is an edible bivalve that burrows into bottom sediment to protectitself from environmental fluctuations and predation. This study examined the relationship between clam populations andabiotic environmental conditions in order to develop an understanding of the biological and ecological processes that couldbe used to improve their management and exploitation. The study site was located in the estuary of the Palian River, KantangDistrict, Trang Province, on the Andaman coast of Thailand. Six zones were established along the estuary. Data werecollected from January 2008 to December 2008. The results showed that salinity (Sal and concentrations of total suspendedsolids (TSS were the water quality parameters most closely related to population densities of estuarine clams. The combinationof those variables gave the strongest correlation to clam densities (Spearman rank correlation, pw = 0.504. Among bottomsediment parameters, pH and ferrous and ferric iron concentrations gave the strongest correlations to clam densities(Spearman rank correlation, pw = 0.716. The result revealed that the water quality (Sal and TSS and the bottom sediment(pH, ferrous and ferric iron were the main significant parameters influencing the abundance of estuarine clam M. casta.

  19. Factors driving changes in freshwater mussel (Bivalvia, Unionida) diversity and distribution in Peninsular Malaysia.

    Science.gov (United States)

    Zieritz, Alexandra; Lopes-Lima, Manuel; Bogan, Arthur E; Sousa, Ronaldo; Walton, Samuel; Rahim, Khairul Adha A; Wilson, John-James; Ng, Pei-Yin; Froufe, Elsa; McGowan, Suzanne

    2016-11-15

    Freshwater mussels (Bivalvia, Unionida) fulfil important ecosystem functions and are one of the most threatened freshwater taxa globally. Knowledge of freshwater mussel diversity, distribution and ecology in Peninsular Malaysia is extremely poor, and the conservation status of half of the species presumed to occur in the region has yet to be assessed. We conducted the first comprehensive assessment of Peninsular Malaysia's freshwater mussels based on species presence/absence and environmental data collected from 155 sites spanning all major river catchments and diverse habitat types. Through an integrative morphological-molecular approach we recognised nine native and one widespread non-native species, i.e. Sinanodonta woodiana. Two species, i.e. Pilsbryoconcha compressa and Pseudodon cambodjensis, had not been previously recorded from Malaysia, which is likely a result of morphological misidentifications of historical records. Due to their restriction to single river catchments and declining distributions, Hyriopsis bialata, possibly endemic to Peninsular Malaysia, Ensidens ingallsianus, possibly already extinct in the peninsula, and Rectidens sumatrensis, particularly require conservation attention. Equally, the Pahang, the Perak and the north-western river catchments are of particular conservation value due to the presence of a globally unique freshwater mussel fauna. Statistical relationships of 15 water quality parameters and mussel presence/absence identified acidification and nutrient pollution (eutrophication) as the most important anthropogenic factors threatening freshwater mussel diversity in Peninsular Malaysia. These factors can be linked to atmospheric pollution, deforestation, oil-palm plantations and a lack of functioning waste water treatment, and could be mitigated by establishing riparian buffers and improving waste water treatment for rivers running through agricultural and residential land. PMID:27473771

  20. Vesicomyinae (Bivalvia: Vesicomyidae) of the Kuril-Kamchatka Trench and adjacent abyssal regions

    Science.gov (United States)

    Krylova, Elena M.; Kamenev, Gennady M.; Vladychenskaya, Irina P.; Petrov, Nikolai B.

    2015-01-01

    Representatives of the subfamily Vesicomyinae (Bivalvia, Vesicomyidae) are tiny deep-sea molluscs distributed worldwide and reaching huge abundances of hundreds and thousands of specimens in trawl catches. During the German-Russian deep-sea expedition KuramBio (R/V Sonne, 2012) for the first time two vesicomyin species were collected from the abyssal plain adjacent to the Kuril-Kamchatka Trench from the depths of 4861-5787 m, Vesicomya pacifica (Smith, 1885) and "Vesicomya" filatovae sp.n. Two species of vesicomyins, V. sergeeviFilatova, 1971 and V. profundiFilatova, 1971, which were previously reported from the hadal of the Kuril-Kamchatka Trench, were not collected at the abyssal depth despite of the close geographical proximity of the sampling area to their distribution ranges. Altogether nine species of vesicomyins are recorded now from the West and Indo-West Pacific; data on distribution and morpho-anatomical characters of these species are provided. Taxonomic description of V. pacifica is revised including information on its soft part anatomy, new localities and COI sequences. For the first time for a vesicomyin bivalve molecular data is given for a species with an explicit morphological description and unambiguous taxonomic affiliation. Molecular analysis of 160 published COI sequences of vesicomyids and newly obtained molecular data on V. pacifica showed that V. pacifica and two undescribed vesicomyin species forming a monophyletic clade which exhibits sister relationships with the Pliocardiinae, the group of chemosymbiotic vesicomyids. "Vesicomya" filatovae sp.n. is provisionally assigned to the genus Vesicomya (s.l.) until additional morphological and molecular data are obtained. It differs from Vesicomya s.s. by a broader hinge margin with more radiating teeth and the presence of only one pair of demibranchs.

  1. Growth and production of Donax striatus (Bivalvia: Donacidae) from Las Balsas beach, Gibara, Cuba.

    Science.gov (United States)

    Ocaña, Frank A

    2015-09-01

    Clams of the genus Donax are worldwide the dominating group of the invertebrate community on sandy beaches. They are primary consumers that provide a significant abundance and biomass to the ecosystem. In the Caribbean, Donax striatus has an important role for nature and human, nonetheless studies on the population dynamics of this beach clam are scarce and no information exists on secondary production of this species. Growth parameters and secondary production of D. striatus were estimated from February 2008 to November 2009 at Las Balsas beach, Northeastern Cuba, in order to provide basic information for management purposes. In each month 45 samples were taken by means of a PVC corer of 0.025 m2 area and sieved with a 1 mm mesh. Animals were measured and weighted with and without shell. A total of 5 471 specimens were collected during the sampling period. Shell length ranged from 2.7-33.3 mm. Growth parameters estimated from length frequency data were L∞ = 36.1 mm, K= 0.8/yr and t0= 0.2/yr. The growth performance resulted in values of Φ'= 3.02. Life span was 2.4 yrs and mortality rate was 3.07 /yr. In 2008, mean abundance of D. striatus ranged between 17.1 - 770.7 ind./m2. In 2009 the lowest mean abundance was 34.4 and the highest was 892.5 ind./m2. During 2009 biomass and production was more than twice higher in comparison with 2008. Individual production showed highest values in the 24 mm shell size (3.74 g/m2.yr) and 25 mm (0.71 g/m2.yr), considering mass with shell and without shell, respectively. During 2009 abundance of individuals with 15 mm shell length or more increased resulting in higher biomass and production, compared to 2008. Using the conversion factor of wet mass to ash free dry mass (AFDM), annual production ranged between 2.87-6.11 g AFDM/m2.yr, resulting in a turnover rate (P/B) between 5.11 and 3.47 in 2008 and 2009, respectively. The rapid growth and high turnover rate of D. striatus suggest a rapid recovery of the population. These

  2. Growth and production of Donax striatus (Bivalvia: Donacidae) from Las Balsas beach, Gibara, Cuba.

    Science.gov (United States)

    Ocaña, Frank A

    2015-09-01

    Clams of the genus Donax are worldwide the dominating group of the invertebrate community on sandy beaches. They are primary consumers that provide a significant abundance and biomass to the ecosystem. In the Caribbean, Donax striatus has an important role for nature and human, nonetheless studies on the population dynamics of this beach clam are scarce and no information exists on secondary production of this species. Growth parameters and secondary production of D. striatus were estimated from February 2008 to November 2009 at Las Balsas beach, Northeastern Cuba, in order to provide basic information for management purposes. In each month 45 samples were taken by means of a PVC corer of 0.025 m2 area and sieved with a 1 mm mesh. Animals were measured and weighted with and without shell. A total of 5 471 specimens were collected during the sampling period. Shell length ranged from 2.7-33.3 mm. Growth parameters estimated from length frequency data were L∞ = 36.1 mm, K= 0.8/yr and t0= 0.2/yr. The growth performance resulted in values of Φ'= 3.02. Life span was 2.4 yrs and mortality rate was 3.07 /yr. In 2008, mean abundance of D. striatus ranged between 17.1 - 770.7 ind./m2. In 2009 the lowest mean abundance was 34.4 and the highest was 892.5 ind./m2. During 2009 biomass and production was more than twice higher in comparison with 2008. Individual production showed highest values in the 24 mm shell size (3.74 g/m2.yr) and 25 mm (0.71 g/m2.yr), considering mass with shell and without shell, respectively. During 2009 abundance of individuals with 15 mm shell length or more increased resulting in higher biomass and production, compared to 2008. Using the conversion factor of wet mass to ash free dry mass (AFDM), annual production ranged between 2.87-6.11 g AFDM/m2.yr, resulting in a turnover rate (P/B) between 5.11 and 3.47 in 2008 and 2009, respectively. The rapid growth and high turnover rate of D. striatus suggest a rapid recovery of the population. These

  3. Filter-feeding, food utilization, and nutrient remineralization by Corbicula fluminea (bivalvia) and its contribution to nutrient cycling in a North Carolina River

    International Nuclear Information System (INIS)

    The introduced Asiatic clam Corbicula fluminea is quite prolific, and since it is a filter-feeder, it can be expected to influence the cycling of nutrients within its habitat as a result of its feeding and excretory activities. Factors affecting filtration rates, food utilization, and excretion of metabolic wastes (ammonia and phosphate) were determined by laboratory experiments, and these physiological processes were then extrapolated to field estimates of Corbicula found in the upper Chowan River, N.C., to obtain an estimate of the potential impact the clams can have on nutrient cycling in the river. Clam filtration rates of four different 14C-labeled algae species (two greens, a blue-green, and a diatom) were similar, although partitioning of the ingested isotope showed significant differences between the algal foods. The diatom species was the most efficiently utilized by the clams, with more than 80% of the isotope ingested recovered in clam tissues. Corbicula freshly collected from the Chowan River excreted substantially more ammonia than phosphate, and rates of excretion of both nutrients were highest in summer. Clam excretion rates were much higher than sediment fluxes, and as a source of recycled nutrients, these clams could provide about one third of the nitrogen and phosphate requirements of the phytoplankton in the upper Chowan

  4. Determination of protein-carbonyls and ubiquitin-mediated proteolysis as biomarkers of oxidative-stress in bivalvia and anthozoa

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Stephen Thomas

    2002-07-01

    This study describes the investigation of biomarkers of oxidative-stress in the bivalves Mytilus edulis and Dosinia lupinus, together with host and symbiont tissues of the scleractinian Anthozoa Agaricia agaricites. The biomarkers used were assay of total (via spectrophotometry) and individual (via Western blotting; Oxyblot kit) protein-carbonyls (PC=Os) and content of ubiquitin protein conjugates (UPC) via Western blotting (Bivalvia and Anthozoa) and immunohistochemistry (Anthozoa only). Additional assays for Bivalvia were Trolox equivalent antioxidant capacity (TEAC); and post {gamma}-irradiation survival rates. Experimental stressors for Bivalvia were increased seawater temperature, H{sub 2}O{sub 2} and {sup 60}Co {gamma}-radiation (latter two were used in vivo and in vitro). Comparisons of clean and polluted marine sites are included. Stressors used for Anthozoa were increased solar irradiation concomitant with elevated seawater temperature. Results and conclusions were as follows: individual samples showed considerable variation, pooling of samples improved consistency. Controls for both biomarkers had detectable background levels in each phylum, against which relatively small differences were assessed. In M. edulis, no measurable differences in PC=Os could be determined when elevated seawater temperature or dilute H{sub 2}O{sub 2} (<30% v/v) stressors were used, nor with between-site comparisons. Concentrated H{sub 2}O{sub 2} (30% v/v) produced a small difference. {sup 60}Co {gamma}-radiation produced clearer differences via Oxyblot and spectrophotometric assays. Comparison of four different tissues from the two bivalves found considerable species-specific and tissue-specific differences. Post-irradiation mortality between species was significantly different (<0.001), D. lupinus was more susceptible than M. edulis. TEAC values generally showed a decrease following irradiation (except for digestive gland). UPCs were clearly different between tissues and

  5. Molecular phylogeny and shell microstructure of Fungiacava eilatensis Goreau et al. 1968, boring into mushroom corals (Scleractinia: Fungiidae), in relation to other mussels (Bivalvia: Mytilidae)

    OpenAIRE

    Owada, M; Hoeksema, B.W.

    2011-01-01

    Research on the evolution of the symbiosis between the boring mussel Fungiacava eilatensis (Bivalvia: Mytilidae) and its mushroom coral hosts (Scleractinia: Fungiidae), which requires phylogenetic reconstructions of both the Mytilidae and the Fungiidae, contributes to the understanding of the complexity of coral reef ecosystems. Previously, Fungiacava was regarded as a genus that had descended from Leiosolenus or as belonging to the subfamily Crenellinae, but no phylogenetic support has been ...

  6. Intersex related gene expression profiles in clams Scrobicularia plana: Molecular markers and environmental application.

    Science.gov (United States)

    Ciocan, Corina M; Cubero-Leon, Elena; Langston, William J; Pope, Nick; Cornelius, Keith; Hill, E M; Alvarez-Munoz, Diana; Indiveri, Paolo; Lerebours, Adelaide; Minier, Christophe; Rotchell, Jeanette M

    2015-06-30

    Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction. PMID:25746199

  7. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Boyu [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Bo, E-mail: bo.huang@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Chunjing; Liu, Shaojun; Xu, Gang [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhao, Yanyun; Huang, Qunying [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2014-12-15

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150–230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε-dot{sub min}) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  8. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    Science.gov (United States)

    Zhong, Boyu; Huang, Bo; Li, Chunjing; Liu, Shaojun; Xu, Gang; Zhao, Yanyun; Huang, Qunying

    2014-12-01

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150-230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε˙min) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  9. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    Science.gov (United States)

    Shen, Hui; Thrush, Simon F; Wan, Xihe; Li, Hui; Qiao, Yi; Jiang, Ge; Sun, Ruijian; Wang, LiBao; He, Peimin

    2016-09-15

    Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm(-2), physical disturbance depth of 16.4cm, bacterial density of 0.18Lm(-2), and polychaetes biomass of 0.16kgm(-2), respectively. These results emphasize the value of combining different species in field-based bioremediation. PMID:27371956

  10. In vivo exposure of the marine clam Ruditapes philippinarum to zinc oxide nanoparticles: responses in gills, digestive gland and haemolymph.

    Science.gov (United States)

    Marisa, Ilaria; Matozzo, Valerio; Munari, Marco; Binelli, Andrea; Parolini, Marco; Martucci, Alessandro; Franceschinis, Erica; Brianese, Nicola; Marin, Maria Gabriella

    2016-08-01

    Potential nanoparticle (NP) toxicity poses a growing concern in marine coastal environments. Among NPs, zinc oxide nanoparticles (nZnO) are widely used in many common products that ultimately become deposited in coastal habitats from multiple non-point sources. In this study, we evaluated the in vivo effects of nZnO in the clam Ruditapes philippinarum. Animals were exposed to nZnO (1 and 10 μg/L) and ZnCl2 (10 μg/L) for 7 days. ZnCl2 was used to compare the effects of the NPs to those of Zn(2+) and to ascertain whether nZnO toxicity is attributable to the release of ions into the aquatic medium. At differing time intervals during the exposure, several biochemical and cellular responses were evaluated in the clam gills, digestive gland, and haemolymph. The results showed that nZnO, at concentrations close to the predicted environmental levels, significantly affected various parameters in clam tissues. Significant increases in catalase and superoxide dismutase activities and a decreasing trend of glutathione S-transferase activity indicated the involvement of oxidative stress in nZnO toxicity. In clams exposed to ZnCl2, slight variations in antioxidant enzyme activities were detected with respect to nZnO-treated clams. However, no damage to lipids, proteins or DNA was revealed in all exposure conditions, suggesting a protection of antioxidant enzymes in the tissues. Of the various haemolymph parameters measured, haemocyte proliferation increased significantly, in ZnCl2-treated clams in particular. Under nZnO (10 μg/L) and ZnCl2 exposure, DNA damage in haemocytes was also revealed, but it was lower in clams exposed to ZnCl2. A decreasing trend in gill AChE activity of treated clams proposed a possible role of zinc ions in nZnO toxicity. However, the dissimilar modulation of the responses in the nZnO- and ZnCl2-exposed clams suggested different mechanisms of action, with nZnO toxicity possibly depending not only on the release of zinc ions but also on NP

  11. Acute and chronic exposure in mussel (aulacomya ater) and clam (semelle solida) with Cs137

    International Nuclear Information System (INIS)

    Two of the most common Peruvian benthonic molluscs, have been shown to be effective concentrators of Cesium-137 and have also proven useful as indicators of that radionuclide in their natural environment, according with results in this paper. However the clam is a better indicator, when determining environmental acute release of Cesium-137 due to reactor accidents, nuclear tests, accidents in nuclear ships, submarines and radioactive material transport, and the mussel for a continuous monitoring of environmental radio contaminant levels. (author). 11 refs

  12. Enzyme responses and lipid peroxidation in gills and hepatopancreas of clam Mactra vereformis, following cadmium exposure

    Institute of Scientific and Technical Information of China (English)

    WANG Xiaoyu; YANG Hongsheng; LIU Guangbin; WANG Qing

    2011-01-01

    To assess the toxicity of heavy metal pollution to marine intertidal shellfish,enzymatic responses and lipid peroxidation were investigated in the clam Mactra vereformis exposed to cadmium under laboratory conditions.Three antioxidant enzymes (superoxide dismutase,SOD; catalase,CAT;glutathione peroxidase,GPx),two immune defense enzymes (acid phosphatase,ACP; alkaline phosphatase,ALP),and one lipid peroxidation product (malondialdehyde,MDA) were measured in the gills and the hepatopancreas of the clam exposed to 0,25,75,and 125 μg/L cadmium for 0,1,3,5,and 7 d.The results show that the concentrations of antioxidant enzymes in the organs soared to a peak value on the first day and then decreased afterwards in most cases.CAT and GPx activities in the hepatopancreas were higher than in the gills,but the SOD activity was lower in the bepatopancreas.ACP activity was unchanged until Day 3 in the hepatopancreas and until Day 5 in gills,when it began to increase.ALP activity showed no significant relationship with Cd treatment.MDA concentrations increased in the two tissues after Cd exposure,peaked on Day 3 in gills,and on Day 5 in hepatopancreas.These observations show that changes in the activities of antioxidant enzymes and ACP reflect the time course of oxidative stress in the clam caused by Cd,and could be used as potential biomarkers for ecotoxicological bioassays of heavy metals.

  13. Changes in fatty acid composition in the giant clam Tridacna maxima in response to thermal stress

    Science.gov (United States)

    Dubousquet, Vaimiti; Gros, Emmanuelle; Berteaux-Lecellier, Véronique; Viguier, Bruno; Raharivelomanana, Phila; Bertrand, Cédric; Lecellier, Gaël J.

    2016-01-01

    ABSTRACT Temperature can modify membrane fluidity and thus affects cellular functions and physiological activities. This study examines lipid remodelling in the marine symbiotic organism, Tridacna maxima, during a time series of induced thermal stress, with an emphasis on the morphology of their symbiont Symbiodinium. First, we show that the French Polynesian giant clams harbour an important proportion of saturated fatty acids (SFA), which reflects their tropical location. Second, in contrast to most marine organisms, the total lipid content in giant clams remained constant under stress, though some changes in their composition were shown. Third, the stress-induced changes in fatty acid (FA) diversity were accompanied by an upregulation of genes involved in lipids and ROS pathways. Finally, our microscopic analysis revealed that for the giant clam's symbiont, Symbiodinium, thermal stress led to two sequential cell death processes. Our data suggests that the degradation of Symbiodinium cells could provide an additional source of energy to T. maxima in response to heat stress. PMID:27543058

  14. Interaction of CLAM Steel with Plasma in HT-7 Tokamak During High Parameter Operation

    Institute of Scientific and Technical Information of China (English)

    LI Chunjing; HUANG Qunying; FENG Yan; LI Jiangang; KONG Mingguang

    2007-01-01

    A Plasma Surface Interaction(PSI)experiment on China Low Activation Martensitic(CLAM)steel was done to check if CLAM steel could be used as a Plasma Facing Material (PFM).A specimen with a diameter of 45 mm was exposed to 897 shots of deuterium plasmas with a total duration of 712 sec at a minor radius of 30 cm in HT-7 tokamak.During the exposure experiment,no observable influence Was found on plasma performance.After exposure,the surface of the specimen seemed as smooth as before but with some colour change at the margin of the specimen.Even though some micro-damage,such as dense blisters,melting,splashing,depositions,and dust,Was found on local surfaces with Scanning Electron Microscopic(SEM)observation.The reflectivity of the specimen decreased only slightly.All of these shows CLAM steel has good stability and irradiation resistance.With further optimization,it could possibly be used as the first mirror material for plasma diagnostics in tokamaks.

  15. Intersex related gene expression profiles in clams Scrobicularia plana: Molecular markers and environmental application

    International Nuclear Information System (INIS)

    Highlights: • Expression of intersex-related genes was analysed in clam gonads sampled from the Channel. • Genes were differentially expressed at sites with varying levels of intersex and contaminants. • Correlations between gene expressions, key contaminants and sampling sites were identified. • No single gene expression studied correlated with intersex incidence. - Abstract: Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction

  16. Irradiation control of pathogenic bacteria and their growth during storage in short neckde clam

    International Nuclear Information System (INIS)

    The growth of pathogenic bacteria during storage and their D10 values by irradiation in short necked clam were evaluated. The results showed that the D10 values of the total bacteria count, E. coli, Vibrio parahaemolyticus in short necked clam at 0 degree C ∼ 4 degree C condition were 0.70, 0.56, 0.20kGy, respectively. The results showed that total bacteria count in vacuum packaged short necked clam sample was 4.46 log (CFU/g) after 3kGy 60Co γ-irradiation and 28 days stored under 0 degree C ∼ 4 degree C, which could meet the requirement of related aquatic product standards, the E. coli and Vibrio parahaemolyticus would not detected after 0.4kGy irradiation and 7 days storage at 0 degree C ∼ 4 degree C. Therefore, micro-organisms could be controled effectively by 3 kGy irradiation and its shelf-life could extend to 28 days. (authors)

  17. Comparison between the mercury contamination in populations of Unio pictorum mancus (Mollusca, Bivalvia from two lakes of different trophic state: the oligo-mesotrophic Lake Maggiore and the eutrophic Lake Candia

    Directory of Open Access Journals (Sweden)

    Nicoletta RICCARDI

    2009-08-01

    Full Text Available This research was designed to evaluate the influence of mussel (Unio pictorum mancus size on mercury concentration in mussel soft tissues. It also evaluated the relationships between calcium, mercury and selenium in the mussel tissues. The mussel populations from the deep, meso-oligotrophic Lake Maggiore and the shallow, eutrophic Lake Candia were analyzed. The mean concentration of mercury in the tissues was 0.075 mg kg-1 in Lake Maggiore mussels and 0.033 mg kg-1 in Lake Candia mussels. The local mercury content in the mussel biomass per surface unit was about eleven-fold higher in Lake Maggiore (5.99 μg Hg m-2 than in Lake Candia (0.55 μg Hg m-2. This wide difference was due firstly to the larger population density (46.86 vs 6.93 ind m-2 and secondly to the higher individual content (0.128 vs 0.079 μg Hg ind-1 in Lake Maggiore than in Lake Candia. These differences in population density and individual mercury content are the result of both biological and environmental characteristics. Lake trophy and water renewal affect population density and individual growth rate, and ultimately determine their impact on biogeochemical cycles by regulating the mussel standing stock. The relationships between mercury, calcium and selenium were taken into account.

  18. Dinâmica da População de Anomalocardia brasiliana (Mollusca, Bivalvia, Veneridae no Estuário do Rio Paciência, no Município da Raposa, Estado do Maranhão

    Directory of Open Access Journals (Sweden)

    Juan Jethro Silva Santos

    2014-01-01

    Full Text Available A presença de moluscos no litoral maranhense é significativa, servindo de fonte de renda e subsistência para muitas comunidades. Um exemplo de molusco relacionado com esse potencial é a espécie Anomalocardia brasiliana (Gmelin 1791, que possui grande importância para a população do município da Raposa, na ilha do Maranhão. A presente pesquisa objetivou analisar a dinâmica dessa espécie em lotes naturais do próprio município, nos períodos locais caracterizados como seco e chuvoso. Coletas mensais foram realizadas no período de agosto a dezembro de 2010 e março a junho de 2011, onde foram efetuados levantamentos de informações importantes como variáveis biométricas, fator de condição e densidade. Os resultados encontrados mostraram que os organismos durante todo o período de coleta, exceto o mês de agosto, apresentaram tamanho satisfatório para o consumo, com média acima de 20 mm. Para outro caso, observou-se uma diminuição do fator de condição nos meses de agosto e dezembro, podendo estar relacionado com algum estresse no meio como: período de desova da espécie em questão ou pressão antrópica na região, tendo em vista que, esse organismo sofre forte extração local de forma não sustentável. A densidade dos organismos mostrou-se alta, em termos de biomassa, apresentando uma média de 3,16 toneladas em uma área de 6.007,5 m², que comparada com uma criação de gado extensiva, dependendo do manejo, torna-se mais produtiva, econômica e ecológica.

  19. Genetic diversity of the biofilm covering Montacuta ferruginosa (Mollusca, bivalvia) as evaluated by denaturing gradient gel electrophoresis analysis and cloning of PCR-Amplified gene fragments coding for 16S rRNA

    NARCIS (Netherlands)

    Gillan, D.C.; Speksnijder, Arjen; Zwart, G.; De Ridder, C.

    1998-01-01

    The shell of the bivalve Montacuta ferruginosa, a symbiont living in the burrow of an echinoid, is covered with a rust- colored biofilm, This biofilm includes different morphotypes of bacteria that are encrusted with a mineral rich in ferric ion and phosphate, The aim of this research was to determi

  20. 我国重要帘蛤科(Veneridae)贝类的16S rRNA序列系统学分析%MOLECULAR PHYLOGENY OF VENERIDAE (MOLLUSCA, BIVALVIA) BASED ON 16S rRNA SEQUENCES

    Institute of Scientific and Technical Information of China (English)

    赵婷; 吴琪; 潘宝平

    2013-01-01

    本文对我国隶属于帘蛤科(Veneridae)10个亚科、17个属、20种贝类的16S rRNA基因片段进行了系统学分析,上述动物的16S rRNA片段长度在438-648bp之间,利用PAUP软件包在对序列比对基础上构建了邻接系统树(NJ)和最大拟然系统树(ML).16S rRNA数据显示,我国帘蛤科贝类由三个主要分支组成,美女蛤亚科中的加夫蛤属(Gafrarium)可能是一个单型属,该属与美女蛤属合并为加夫蛤属比较恰当.帘蛤亚科与雪蛤亚科应属于不连续的分类单元.另外,青蛤亚科与仙女蛤亚科均应作为独立的亚科存在.本文的研究结论与修订后的帘蛤科形态分类观点一致.

  1. O Gênero Pholadomya Sowerby, 1823 (Mollusca: Bivalvia na Formação Jandaíra (Cretáceo Superior, Bacia Potiguar: Implicações Paleoecológicas e Paleogeográficas.

    Directory of Open Access Journals (Sweden)

    Natalia Pereira Benaim

    2008-06-01

    Full Text Available Pholadomya Sowerby, 1823 is an anomalodesmatan bivalve that dispersed during Mesozoic, like other Mollusks,colonizating the South Atlantic shallow seas, between Brazil and Africa. On brazilian Cretaceous the sources ofPholadomya are scarce, occurring in outcrops from Algodões Formation, Gramame Formation and Jandaíra Formation,where occurs the species Pholadomya baixaleitensis. Based on specimens from new outcrops of Jandaíra Formation,a new occurrence of P. cf. adversa and P. baixaleitensis are shown and a new morfotype for the genus is described. Itwas possible to infer that the species studied presented deep endobentonic habits, and burrowed slowly the sediment,probably living their whole life into the same cavity. During Campanian Pholadomya is known from Cameroon, France,Poland, Austria, Germany and other localities in United States of America, occurring in association with other tethyanmollusks. The records of the genus in the marginal equatorial basins enhance the fossil bivalve diversity, and agree withthe hypotesis of a south latitudinal range for the Tethyan Realm during Upper Cretaceous.

  2. 广东海陵岛沿海软体动物的分布%DISTRIBUTION OF CLASS BIVALVIA AND GASTROPODA MOLLUSCA IN THE INSHORE REGIONS OF HAILING ISLAND OF GUANGDONG

    Institute of Scientific and Technical Information of China (English)

    唐以杰; 林炜; 陈明旺; 钟诚; 杜晓捷

    2005-01-01

    对海陵岛沿海软体动物进行了采集调查,共鉴定180种,分属 60科. 其中双壳纲20科86种,占总数47.77%,腹足纲38科92种,占总数51.11%,多板纲1科1种,占总数0.56%,头足纲1科1种,占总数0.56%. 分析表明,其区系特点以南海亚热带-热带种和东海-南海亚热带种为主要成分.

  3. Phylogenetic Analysis of Veneridae (Mollusca: Bivalvia) based on Mitochondrial 16S rDNA%基于16S rDNA序列的帘蛤科贝类分子系统发育研究

    Institute of Scientific and Technical Information of China (English)

    程汉良; 周旻纯; 陈冬勤; 彭永兴; 董志国; 易乐飞; 孟学平; 申欣

    2012-01-01

    对21种帘蛤科贝类线粒体16S rRNA基因片段的核苷酸序列进行了分析,以探讨这一序列在种质鉴定、分子系统发育研究中的应用价值.试验结果表明,所有物种扩增片段长度504~642 bp,具有明显的长度多态性,序列A+T含量59.2%~69.0%,明显高于GC含量.物种间共有变异位点447个,其中简约信息位点351个.以16S rDNA片段序列为标记,以中国蛤蜊做外群,构建了帘蛤科贝类的系统发生树,拓扑结构显示,帘蛤科贝类形成3个明显类群,缀锦蛤亚科的13个种形成一个单系群,其结点自展值为93%.第二类群由雪蛤亚科、帘蛤亚科和镜蛤亚科的种类组成,结点自展值为87%.第三类群由仙女蛤亚科、青蛤亚科、楔形蛤亚科和文蛤亚科的种类组成,结点自展值为100%.结合拓扑结构分析和序列比对分析,本研究支持将短文蛤和丽文蛤订为文蛤的同物异名的观点,建议将丽文蛤和短文蛤订为文蛤的地理亚种;支持将薄片镜蛤和Dosinia angulosa订为2个独立种的观点;宜将波纹巴非蛤和织锦巴非蛤订为2个独立种.

  4. Ciclo gametogênico e comportamento reprodutivo de Iphigenia brasiliana (Mollusca, Bivalvia, Donacidae no estuário do rio Subaé, Baía de Todos os Santos, Bahia, Brasil

    Directory of Open Access Journals (Sweden)

    Patrícia P. Silva

    2012-12-01

    Full Text Available Este estudo teve como objetivos descrever o ciclo gametogênico e o comportamento reprodutivo da população de Iphigenia brasiliana (Lamarck,1818 no estuário do rio Subaé, Baía de Todos os Santos, Bahia. Os bivalves foram coletados de novembro de 2001 a novembro de 2002. Um total de 244 espécimes foi medido (eixo anteroposterior, eviscerado, fixado, desidratado e incluído em parafina. O estudo histológico das gônadas foi realizado através de cortes seriados do tecido gonadal, de 5 mm de espessura, e corados pela HE. O tamanho médio mínimo da primeira maturação sexual (Lpm foi estimado a partir da distribuição das frequências relativas de jovens e adultos, por classe de comprimento dos indivíduos. As frequências relativas dos sexos em cada estádio de desenvolvimento foram consideradas conjuntamente para a análise do comportamento reprodutivo da população, e, em separado, para avaliar a sincronia do ciclo sexual entre machos e fêmeas. Foi observada uma variação de tamanhos entre 9,1 e 66,6 mm, com comprimento médio de 50,2 mm. O estudo não demonstrou diferença significativa entre os tamanhos de machos e fêmeas. Não foi possível observar a diferenciação de sexos em 2,1% dos indivíduos analisados. 51,6% dos indivíduos foram identificados como machos (M e 46,3% como fêmeas (F, não sendo constatadas diferenças significativas entre o número médio de machos e fêmeas, resultando numa proporção de M:F de 1,1:1. O Lpm foi estimado em 11,4 mm, mas apenas ao alcançarem comprimento médio de 34,4 mm, todos os indivíduos foram considerados adultos. Foram caracterizados quatro estádios de evolução do desenvolvimento gonadal em fêmeas e machos. A análise dos diferentes estádios permitiu a observação dos fenômenos de atresia e inversão sexual em fêmeas. O ciclo reprodutivo apresentou eliminação contínua de gametas, com maiores intensidades reprodutivas nos meses de novembro de 2001 a abril de 2002 e, também, no mês de outubro de 2002.

  5. COⅠ -BASED DNA BARCODING IN MYTILIDAE SPECIES (MOLLUSCA: BIVALVIA)%基于线粒体COⅠ的DNA条形码技术在贻贝科种类鉴定中的应用

    Institute of Scientific and Technical Information of China (English)

    刘君; 李琪; 孔令锋; 陈军; 郑小东; 于瑞海

    2011-01-01

    DNA条形码(DNA barcoding)技术作为近年来发展起来的物种鉴定的一门新兴技术,已引起越来越多的关注.其原理是利用一段短DNA标准序列(对动物而言一般为线粒体细胞色素c氧化酶亚单位I,mitochondrial cytochrome c oxidase subunit Ⅰ,COⅠ)来实现物种鉴定[1].它的两大主要目的是鉴定已知种和发现新种[2,3].

  6. MOLECULAR PHYLOGENY OF TAPETINAE (MOLLUSCA, BIVALVIA) BASED ON MTDNA SEQUENCE%缀锦蛤亚科(Tapetinae)贝类线粒体DNA序列的系统学分析

    Institute of Scientific and Technical Information of China (English)

    潘鹤婷; 袁媛; 吴琪; 张素萍; 潘宝平

    2008-01-01

    采用线粒体16S rRNA和COI序列扩增和测序方法,对隶属于缀锦蛤亚科5属7种动物进行了系统学分析.经Clustal x多重比对和PAuP 4.10 软件分析,得到种间序列的遗传距离并构建了邻接(NJ)系统树.实验数据显示,缀锦蛤亚科为遗传连续的同源类群,其中的浅蛤属(Gomphina)、缀锦蛤属(Tapes)和蛤仔属(Ruditapes)亲缘关系较近,结果与Fischer-Piette等(1971)的缀锦蛤亚科的分类方案基本一致.另外,菲律宾蛤仔R.philippinarum 和杂色蛤仔 R.variegata是蛤仔属在印度洋和太平洋海区的一个组群,尽管两种贝类有明显的重叠分布区和相近的贝壳形态,但二者间的16S rRNA 和COI序列遗传距离均达到了物种间差别.结果支持庄启谦(2001)有关菲律宾蛤仔与杂色蛤仔的形态分类及分布区划分的观点.

  7. The Upper Miocene of the Rostov Dome (Eastern Paratethys: Implication of the chronostratigraphy and bivalvia-based biostratigraphy

    Directory of Open Access Journals (Sweden)

    Ruban Dmitry A.

    2005-01-01

    Full Text Available The Rostov Dome is located in the south of the Russian Platform. In the Late Miocene this area was embraced by the Eastern Paratethys. The implications of a recently developed Neogene chronostratigraphy to the studied area are discussed. The Sarmatian regional stage corresponds to the upper part of the Langhian, the entire Serravalian and the lower part of the Tortonian global stages; the Maeotian regional stage corresponds to the upper part of the Tortonian and the lowermost horizons of the Messinian global stages; the Pontian regional stage corresponds to most of the Messinian and the lowermost Zanclean global stages. A first Bivalvia-based bio-stratigraphic framework is proposed for the territory of the Rostov Dome. Five biozones were established within the Serravalian-Messinian: Tapes vitalianus, Cerastoderma fittoni-Cerastoderma subfittoni, Congeria panticapaea, Congeria amygdaloides navicula and Monodacna pseudocatillus-Prosodacna schirvanica.

  8. Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal.

    Directory of Open Access Journals (Sweden)

    Sue-Ann Watson

    Full Text Available Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are 'solar-powered' animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2 (control ~400, mid ~650 and high ~950 μatm and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1. Elevated CO2 projected for the end of this century (~650 and ~950 μatm reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals.

  9. Die verspreiding en habitat van Chambardia wahlbergi en Chambardia petersi (Bivalvia: Iridinidae in Suid-Afrika

    Directory of Open Access Journals (Sweden)

    Kenné N. de Kock

    2012-03-01

    Full Text Available Die verspreiding en habitat van Chambardia wahlbergi en C. petersi, soos weerspieël deur data in die databasis van die Nasionale Varswaterslakversameling (NVWSV word weergegee en bespreek. Alhoewel die verspreiding van hierdie twee spesies grootliks in die Limpopo- en Mpumalangaprovinsie oorvleuel, kom C. wahlbergi, anders as wat in die literatuur gerapporteer is, ook in die Noordwes- en Vrystaatprovinsie in die wesvloeiende Vaalrivier en in verskeie lokaliteite in die Gautengprovinsie voor. Die meerderheid monsters van beide spesies is in riviere en damme en in watertoestande wat as standhoudend, staande, helder en vars beskryf is, versamel. Multivariansie-analises het temperatuur, hoogte bo seevlak en waterliggame as faktore uitgewys wat betekenisvol tot hul geografiese verspreiding bygedra het. Min is oor die bewaringstatus van hierdie twee spesies bekend, maar die opgedateerde IUCN Rooidata-lys (Seddon et al. 2011 dui albei as nie-bedreig aan. Die meerderheid rekords van beide spesies in die databasis van die NVWSV spruit uit werk tydens die vorige eeu in die Nasionale Krugerwildtuin (NKW. Meer onlangse versamelings deur die outeurs in die NKW dui egter op ‘n afname in die aantal plekke van voorkoms, asook die getalle per versamelpunt wat aan die hand doen dat daar tog rede tot kommer oor hul voortbestaan mag wees. Die feit dat besonder groot eksemplare van C. wahlbergi tot so onlangs soos 2007 meestal toevallig in die Vaalrivier aangetref is, beklemtoon die behoefte om weer omvattende opnames van varswater Mollusca, soortgelyk aan dié van die vorige eeu, van stapel te stuur om die gedokumenteerde verspreiding op te dateer en ook die vordering van eksotiese indringerspesies te moniteer.

  10. Recorders of reef environment histories: stable isotopes in corals, giant clams, and calcareous algae

    Science.gov (United States)

    Aharon, Paul

    1991-06-01

    Time-series δ18O and δ13C records from cohabiting massive coral Porites australiensis and giant clam Tridacna gigas from the Great Barrier Reed of Australia, and from calcareous green algae in a core through modern Halimeda bioherm accreting in the eastern Java Sea, provide insights into the complex links between environmental factors and stable isotopes imprinted in these reef skeletal materials. The aragonitic coral and giant clam offer 20 years and 15 years of growth history, respectively. The giant clam yields mean δ18O and δ13C values of-0.5±0.5‰ and 2.2±0.2‰ ( n=67), which agree well with the predicted equilibrium values. The coral yields mean δ18O and δ13C values of-5.6±0.5‰ and-1.8±0.7‰ ( n=84), offering a striking example of kinetic and metabolic fractionation effects. Although both the coral and giant clam harbor symbionts and were exposed to a uniform ambient environment during their growth histories, their distinct isotopic compositions demonstrate dissimilar calcification pathways. The δ18O records contain periodicities corresponding to the alternating annual density bands revealed by X-radiography and optical transmitted light. Attenuation of the δ18O seasonal amplitudes occurring in the giant clam record 8 years after skeletal growth commenced is attributed to a changeover from fast to slow growth rates. Extreme seasonal δ18O amplitudes of up to 2.2‰ discerned in both the coral and giant clam records exceed the equivalent seasonal temperature contrast in the reef environment, and are caused by the combined effect of rainfall and evaporation during the monsoon and dry seasons, respectively. Thus in addition of being useful temperature recorders, reef skeletal material of sufficient longevity, such as Porites and Tridacna, may also indicate rainfall variations. Changing growth rates, determined from the annual growth bands, may exert a primary control on the coral δ13C record which shows a remarkable negative shift of 1.7

  11. Bioaccumulation of polychlorinated biphenyls and metals from contaminated sediment by freshwater prawns, Macrobrachium rosenbergii and clams, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Tatem, H.E.

    1986-02-01

    Freshwater prawns, Macrobrachium rosenbergii, and clams, Corbicula Fluminea, were exposed for 48 or 50 days to three concentrations of a river sediment that contained environmental contaminants such as polychlorinated biphenyls (PCBs) and metals. The PCB sediment bioaccumulation factors (BAF) for prawns ranged from 0.11 to 0.90 for 1242 and 0.20 to 2.40 for 1254, and were highest for animals exposed to 10% sediment. Exposed clams also accumulated PCBs (1242 + 1254) from the sediment. Sediment BAFs for clams were 0.54 to 12.52 and were highest for animals exposed to 10% sediment. Analyses of clams for metals showed lead (Pb) in exposed animals at higher concentrations compared with controls. Bioaccumulation of Pb differed from PCB in that the Pb concentrations did not increase over time and concentrations were higher among animals exposed to 10% sediment compared to animals exposed to 100% sediment. Sediment 11-80 contained 99 mg/kg of Pb while exposed animals, at 48 days, contained approximately 2.2 mg/kg Pb. Analysis of clams for cadmium (Cd) showed exposed animals contained less Cd than controls.

  12. Purification and Characterization of Hemagglutinating Proteins from Poker-Chip Venus (Meretrix lusoria and Corbicula Clam (Corbicula fluminea

    Directory of Open Access Journals (Sweden)

    Chin-Fu Cheng

    2012-01-01

    Full Text Available Hemagglutinating proteins (HAPs were purified from Poker-chip Venus (Meretrix lusoria and Corbicula clam (Corbicula fluminea using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358 kDa and 380 kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26 kDa and 29 kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32 kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4°C–10°C or the salinity was less than 0.5‰, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam.

  13. Hard and soft anatomy in two genera of Dondersiidae (Mollusca, Aplacophora, Solenogastres).

    Science.gov (United States)

    Scheltema, Amélie H; Schander, Christoffer; Kocot, Kevin M

    2012-06-01

    Phylogenetic relationships and identifications in the aplacophoran taxon Solenogastres (Neomeniomorpha) are in flux largely because descriptions of hard parts--sclerites, radulae, copulatory spicules--and body shape have often not been adequately illustrated or utilized. With easily recognizable and accessible hard parts, descriptions of Solenogastres are of greater use, not just to solenogaster taxonomists, but also to ecologists, paleontologists, and evolutionary biologists. Phylogenetic studies of Aplacophora, Mollusca, and the Lophotrochozoa as a whole, whether morphological or molecular, would be enhanced. As an example, morphologic characters, both isolated hard parts and internal anatomy, are provided for two genera in the Dondersiidae. Five species are described or redescribed and earlier descriptions corrected and enhanced. Three belong to Dondersia: D. festiva Hubrecht, D. incali (Scheltema), and D. namibiensis n. sp., the latter differentiated unambiguously from D. incali only by sclerites and copulatory spicules. Two species belong to Lyratoherpia: L. carinata Salvini-Plawen and L. californica (Heath). Notes are given for other species in Dondersiidae: L. bracteata Salvini-Plawen, Ichthyomenia ichthyodes (Pruvot), and Heathia porosa (Heath). D. indica Stork is synonymized with D. annulata. A cladistic morphological analysis was conducted to examine the utility of hard parts for reconstructing solenogaster phylogeny. Results indicate monophyly of Dondersia and Lyratoherpia as described here.

  14. Two new species of Naticidae (Mollusca ,Gastropoda) from the coast of China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Suping

    2008-01-01

    Two new species of Naticidae (Mollusca,Gastropoda) collected from the coast of China are described:Cryptonaitca huanghaien- sis sp.nov.and Sinum vittatum sp.nov.The morphological characteristics between the new species were described and the relat- ed information was provided.The similarities and differences between the new species and related species were also compared and discussed.The new species Cryptonaitca huanghaiensis differed from Cryptonaitca hirasei and Cryptonaitca andoi in outer shape, operculum and radula.The new species Sinum vittatum is similar to Sinum japonicum (Lischke,1869),but the shell of the for- mer is flat-elliptical in shape,spire very small,slightly convex.While the latter is flat-globular in shape,apex light brown in col- or,without a brown band on the body whorl.The comparison results revealed that Cryptonaitca huanghaiensis and Sinum vittatum were two new species from the coast of China.Specimens studied were obtained from collections in the Marine Biological Museum, Chinese Academy of Sciences.

  15. A review of the non-bulimulid terrestrial Mollusca from the Region of Atacama, northern Chile

    Science.gov (United States)

    Araya, Juan Francisco; Catalán, Ricardo

    2014-01-01

    Abstract Terrestrial mollusca are sparsely studied in Chile and, for the first time, a formal record of the diversity of land snails in northern Chile is reported. Coastal and desertic areas in the Region of Atacama, in the border of the Atacama desert and the Pacific Ocean, were surveyed with the aim to describe the presence and distribution of this poorly known fauna. Of the fourteen species recorded, the geographic distribution records for nine species are extended, and some taxa are recorded for the first time since their original descriptions. All, except one, of the fourteen terrestrial molluscan species occurring in the area are endemic to Chile; they are all terrestrial species, most of them have a restricted geographic distribution, and none of them is currently protected by law. The results reveal that the region of Atacama has one of the most diverse terrestrial snail biodiversity in Chile, ranking only after the Juan Fernandez Archipelago. Distribution records of all the studied species and a taxonomic key are also provided. PMID:24715800

  16. NMR-Based Metabolomic Investigations on the Differential Responses in Adductor Muscles from Two Pedigrees of Manila Clam Ruditapes philippinarum to Cadmium and Zinc

    Directory of Open Access Journals (Sweden)

    Junbao Yu

    2011-09-01

    Full Text Available Manila clam Ruditapes philippinarum is one of the most important economic species in shellfishery in China due to its wide geographic distribution and high tolerance to environmental changes (e.g., salinity, temperature. In addition, Manila clam is a good biomonitor/bioindicator in “Mussel Watch Programs” and marine environmental toxicology. However, there are several pedigrees of R. philippinarum distributed in the marine environment in China. No attention has been paid to the biological differences between various pedigrees of Manila clams, which may introduce undesirable biological variation in toxicology studies. In this study, we applied NMR-based metabolomics to detect the biological differences in two main pedigrees (White and Zebra of R. philippinarum and their differential responses to heavy metal exposures (Cadmium and Zinc using adductor muscle as a target tissue to define one sensitive pedigree of R. philippinarum as biomonitor for heavy metals. Our results indicated that there were significant metabolic differences in adductor muscle tissues between White and Zebra clams, including higher levels of alanine, glutamine, hypotaurine, phosphocholine and homarine in White clam muscles and higher levels of branched chain amino acids (valine, leucine and isoleucine, succinate and 4-aminobutyrate in Zebra clam muscles, respectively. Differential metabolic responses to heavy metals between White and Zebra clams were also found. Overall, we concluded that White pedigree of clam could be a preferable bioindicator/biomonitor in marine toxicology studies and for marine heavy metals based on the relatively high sensitivity to heavy metals.

  17. Norovirus recognizes histo-blood group antigens on the gastrointestinal cells of clams, mussels and oysters: a possible mechanism of bio-accumulation

    Science.gov (United States)

    In this study, a set of HBGA-specific monoclonal antibodies (MAbs) was used to detect the expression of HBGA in three oyster species consumed commonly (pacific, virginica, and kumamato), and manila clams, and blue mussels. rNVLPs were applied to plate coated with oyster, mussel or clam GI homogena...

  18. Polyplacophora (Mollusca from reef ecosystems and associations with macroalgae on the Coast of Alagoas, Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Monica Dorigo Correia

    2015-08-01

    Full Text Available ABSTRACT Brazilian marine molluscs, especially Gastropoda and Bivalvia, are relatively well studied. However, information on the class Polyplacophora is more scarce, particularly on reef-dwelling forms. This study aimed to qualitatively and quantitatively analyze aspects of polyplacophorans from reef ecosystems and their associations with macroalgae on the coast of Maceió (state of Alagoas, Brazilian Northeast. The study area included five coral reefs at Ipioca, Ponta do Prego, Ponta do Meirim, Riacho Doce and Ponta Verde, as well as two sandstone reefs, located in Guaxuma and Sereia. The samples were obtained by snorkelling along the intertidal and subtidal reef zones to a depth of up to five meters during low tides, between 2009 and 2011. In addition, the chitons associated with three macroalgae of the Ponta Verde coral reef were studied based on collections made over 12 years (from the summer of 1998 to the winter of 2009. Three replicates with an area of 25 cm2 were collected from each of the following species of macroalgal phytals: Amphiroa fragilissima (Rhodophyta, Caulerpa racemosa (Chlorophyta and Dictyota cervicornis (Phaeophyta. A total of 715 individuals (110 juveniles and 605 adults were identified, including Acanthochitona terezae Guerra, 1983, Ischnochiton striolatus (Gray, 1828 and Ischnoplax pectinata (Sowerby II, 1840. Acanthochitona terezae was found for the first time in the area. Ischnochiton striolatus was the most abundant species in the reef ecosystem and in association with macroalgae. The greatest number of individuals of all three polyplacophorans identified (adults and juveniles was found on the phytal A. fragilissima.

  19. 基于CO Ⅰ的中国西施舌DNA条形码%DNA Barcodes of Clam Coelomactata antiquata (Bivalvia: Veneroida)in China Based on CO Ⅰ Gene

    Institute of Scientific and Technical Information of China (English)

    孟学平; 高如承; 申欣; 郑雯雯; 赵娜娜; 程汉良; 田美

    2011-01-01

    以我国大连(DL)、日照(RZ)、启东(QD)、长乐(CL)、漳州(ZZ)和北海(BH)6个野生群体西施舌为研究对象,用引物LCO1490和HCO2198扩增线粒体细胞色素C氧化酶亚基Ⅰ(COⅠ)基因片段序列,PCR产物双向测序,用ClustalX进行DNA序列比对,用MEGA4.1和PhyML软件构建NJ树和ML树,用Arlequin3.11软件进行分子方差分析,研究CO Ⅰ这一特定基因区段作为DNA条形码在识别西施舌地理群体的可行性和有效性.结果获得658 bp的CO Ⅰ核苷酸片段,其T、C、A、G含量分别为42.4%、14.8%、21.8%、21.0%,A+T(64.2%)含量明显高于G+C含量.变异位点占15.3%(101/658),其中简约信息位点占14.1%.群体内遗传距离为0.0020~0.0043,群体间遗传距离为0.0024~0.0883.群体间氨基酸序列无变异.长乐、漳州群体(DH组)与其他群体(HB组)间有显著的遗传分化(FST=0.956~0.970).NJ树和ML树显示长乐、漳州群体聚为一支,北方的大连、日照、启东群体和南方的北海群体聚为置信度较高的另一支(BPN=99),2支间的遗传距离为0.0837,是2支内群体间遗传距离的17.8~23.5倍.本研究结果表明,CO Ⅰ基因片段序列作为鉴定福建西施舌条形码是可行的,但不能将其余群体区别开来.

  20. Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Kyle B.; Poston, Ted M.; Tiller, Brett L.

    2008-01-31

    The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed.

  1. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yanyun [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Chunjing, E-mail: chunjing.li@fds.org.cn [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Bo; Liu, Shaojun [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Qunying [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2014-12-15

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  2. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    Science.gov (United States)

    Zhao, Yanyun; Li, Chunjing; Huang, Bo; Liu, Shaojun; Huang, Qunying

    2014-12-01

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding.

  3. Size-dependent effects of low level cadmium and zinc exposure on the metabolome of the Asian clam, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Spann, Nicole, E-mail: nicole.spann@web.de [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Aldridge, David C., E-mail: da113@cam.ac.uk [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Griffin, Julian L., E-mail: jlg40@mole.bio.cam.ac.uk [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom); Jones, Oliver A.H., E-mail: o.jones@gmail.com [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom)

    2011-10-15

    Highlights: Small and large Corbicula fluminea were exposed to cadmium and zinc spiked sediment. Metabolomic changes in the freshwater clams were determined by NMR and GC-MS. Metabolic perturbations were related to amino acid and energy related metabolism. Small and large clams were differentiated by their metabolic composition. Size classes showed opposite responses to metal stress. - Abstract: The toxic effects of low level metal contamination in sediments are currently poorly understood. We exposed different sized Asian clams, Corbicula fluminea, to sediment spiked with environmentally relevant concentrations of either zinc, cadmium or a zinc-cadmium mixture for one week. This freshwater bivalve is well suited for sediment toxicity tests as it lives partly buried in the sediment and utilises sediment particles as a food resource. After one week, the whole tissue composition of low molecular weight metabolites was analysed by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS). The condition index (ratio of tissue dry weight to volume inside the shell valves) was also measured. Small and large clams were clearly differentiated by their metabolic composition and the two size classes showed opposite responses to the mixture spiked sediment. No effects of zinc alone on the metabolome were found and cadmium only influenced the smaller size class. The main perturbations were seen in amino acid and energy metabolism, with small clams using amino acids as an energy resource and larger clams primarily drawing on their larger storage reserves of carbohydrates. Our study demonstrates that metabolomics is a useful technique to test for low level toxicity which does not manifest in mortality or condition index changes. The differing effects between the two size classes stress that it is important to consider age/size when conducting metabolomic and ecotoxicology assessments, since testing for the effects on only one size class makes

  4. Lipid remodeling in wild and selectively bred hard clams at low temperatures in relation to genetic and physiological parameters.

    Science.gov (United States)

    Pernet, Fabrice; Tremblay, Réjean; Gionet, Chantal; Landry, Thomas

    2006-12-01

    A temperature decrease usually induces an ordering effect in membrane phospholipids, which can lead to membrane dysfunction. Poikilotherms inhabiting eurythermal environments typically counteract this temperature effect by remodeling membrane lipids as stipulated in the homeoviscous adaptation theory (HVA). Hard clams, Mercenaria mercenaria, can suffer high overwintering mortalities in the Gulf of St Lawrence, Canada. The selectively bred M. mercenaria var. notata can have higher overwintering mortalities than the wild species, thus suggesting that the two varieties have different degrees of adaptation to low temperatures. The objective of this study was to investigate the changes in lipid composition of soft tissues in wild and selected hard clams in relation to their metabolic and genetic characteristics. Clams were placed at the northern limit of their distribution from August 2003 to May 2004; they were exposed to a gradual temperature decrease and then maintained at <0 degrees C for 3.5 months. This study is the first to report a major remodeling of lipids in this species as predicted by HVA; this remodeling involved a sequential response of the phospholipid to sterol ratio as well as in levels of 22:6n-3 and non-methylene interrupted dienoic fatty acids. Hard clams showed an increase in 20:5n-3 as temperature decreased, but this was not maintained during overwintering, which suggests that 20:5n-3 may have been used for eicosanoid biosynthesis as a stress response to environmental conditions. Selectively bred hard clams were characterized by a higher metabolic demand and a deviation from Hardy-Weinberg equilibrium at several genetic loci due to a deficit in heterozygote frequency compared with wild clams, which is believed to impose additional stress and render these animals more vulnerable to overwintering mortality. Finally, an intriguing finding is that the lower metabolic requirements of wild animals coincide with a lower unsaturation index of their lipids

  5. The endocrine-disrupting effect and other physiological responses of municipal effluent on the clam Ruditapes decussatus.

    Science.gov (United States)

    Mezghani-Chaari, Sawssan; Machreki-Ajmi, Monia; Tremolet, Gauthier; Kellner, Kristell; Geffard, Alain; Minier, Christophe; Hamza-Chaffai, Amel

    2015-12-01

    In order to document the potential endocrine disrupting and toxic effect of the municipal wastewater effluents discharged into the Sfax coastal area (South of Tunisia), specimens of clam R. decussatus were collected from a reference site and were in vivo exposed to treated sewage effluent for 30 days. To this end, estrogenic and androgenic activities were measured in the gills to assess potential accumulation and regulation of active compounds. After effluent exposure androgenic activity in organic extracts increased up to fivefold compared to controls and remained elevated, while estrogenic activity was not significantly affected by exposure. As a consequence, remarkable disruptions in the gametogenesis activity, glycogen content, and Vitellogenin-like protein levels in male clams were observed. A parallel analysis of heavy metals in clam tissues was determined. A significant uptake of Ni, Zn, and Pb in soft tissues of exposed clams was observed. The significant increase of malondialdehyde (MDA) concentrations as a function of exposure time implies that clams have been exposed to an oxidative stress probably due to the presence of high metal concentrations in sewage effluent. Correlation analysis has revealed a statistically significant and positive relationship between MDA levels and metal concentrations in clams' tissues. The acetylcholinesterase activity was not significantly affected by exposure. Altogether, these results showed that a short-term exposure to a mixture of chemical compounds released by the Sfax wastewater treatment plant induce adverse physiological and reproductive effects in R. decussatus. Further studies are underway in order to evaluate its long-term impacts on aquatic wildlife in the gulf of Gabes area. PMID:26278908

  6. Fases larvais do mexilhão dourado Limnoperna fortunei (Dunker (Mollusca, Bivalvia, Mytilidae na Bacia do Guaíba, Rio Grande do Sul, Brasil Larval stages of the golden mussel Limnoperna fortunei (Dunker (Bivalvia, Mytilidae in Guaíba Basin, Rio Grande do Sul State, Brazil

    Directory of Open Access Journals (Sweden)

    Cíntia P. dos Santos

    2005-09-01

    Full Text Available Desde o final de 1998, um pequeno bivalve invasor, o "mexilhão dourado", Limnoperna fortunei (Dunker, 1857, oriundo do sudeste asiático, está presente no sul do Brasil. Foi provavelmente transportado, não intencionalmente, através de água de lastro para a Bacia do Guaíba, Rio Grande do Sul, Brasil. Em nosso meio, este molusco vem causando problemas de "macrofouling" com grandes prejuízos econômicos e danos à fauna e flora. As coletas foram qualitativas e quantitativas quinzenais no período de um ano, no lago Guaíba, Praia do Veludo (30°12'35"S, 51°11'68"W, ao sul do município de Porto Alegre. Utilizou-se rede de plâncton com abertura de malha equivalente a 36 mm, filtrando-se a quantidade de 30 litros de água. Descrevem-se brevemente as diferentes fases larvais com parâmetros do comprimento. Primeiramente reconhece-se um estágio ciliado, desenvolvendo-se em trocófora (comprimento de 80 µm a 125 µm com quatro fases distintas, e valvadas com a larva "D" (120 µm a 150 µm, o veliger de charneira reta (150 µm a 190 µm, o veliger umbonado (190 µm a 220 µm e o pediveliger (220 µm a 250 µm. Quando pós-larvas ou plantígradas (comprimento em torno de 300 µm, começam a secretar o fio de bisso, permitindo a fixação ao substrato. Constatou-se a presença de larvas durante todos os meses amostrados, com picos nos meses de outubro a dezembro.Since the end of 1998 a small invasive bivalve, the golden mussel Limnoperna fortunei (Dunker, 1857, originating from Southeast Asia, is present in Southern Brazil. It was probably brought not intentionally in ballast water to the Guaíba Basin in Rio Grande do Sul State. In this environment, the golden mussel is causing macrofouling very rapidly with grate financial loss and damages to the native fauna and flora. Quali-quantitative samplings twice a month were performed during one year in the Guaíba lake, at Veludo Beach (30°12'35"S, 51°11'68"W southward of the municipality of Porto Alegre. Each time, 30 litters of water were filtered through plankton net with a mash opening of 36 mm. The different larval stages with the length parameters were briefly described. Different stages were recognized: five without valves and four valved. The first one recognized as a ciliated stage develops into the trocophora (length from 80 µm to 125 µm with four distinct stages. The valved stages include: the "D" - shaped (length 120 µm to 150 µm, the straight-hinged veliger (length 150 µm to 190 µm, umbonated-veliger (length 190 µm to 220 µm and pediveliger (length 220 µm to 250 µm. When pos-larvae or plantigrades (length about 300 µm, they secrete the byssus thread that permit fixation on the subtract. Larvae were present during all the samplings with strong October-December peaks.

  7. Molecular Cytogenetics in Trough Shells (Mactridae, Bivalvia: Divergent GC-Rich Heterochromatin Content

    Directory of Open Access Journals (Sweden)

    Daniel García-Souto

    2016-08-01

    Full Text Available The family Mactridae is composed of a diverse group of marine organisms, commonly known as trough shells or surf clams, which illustrate a global distribution. Although this family includes some of the most fished and cultured bivalve species, their chromosomes are poorly studied. In this work, we analyzed the chromosomes of Spisula solida, Spisula subtruncata and Mactra stultorum by means of fluorochrome staining, C-banding and fluorescent in situ hybridization using 28S ribosomal DNA (rDNA, 5S rDNA, H3 histone gene and telomeric probes. All three trough shells presented 2n = 38 chromosomes but different karyotype compositions. As happens in most bivalves, GC-rich regions were limited to the nucleolus organizing regions in Spisula solida. In contrast, many GC-rich heterochromatic bands were detected in both Spisula subtruncata and Mactra stultorum. Although the three trough shells presented single 5S rDNA and H3 histone gene clusters, their chromosomal locations differed. Regarding major rDNA clusters, while Spisula subtruncata presented a single cluster, both Spisula solida and Mactra stultorum showed two. No evidence of intercalary telomeric signals was detected in these species. The molecular cytogenetic characterization of these taxa will contribute to understanding the role played by chromosome changes in the evolution of trough shells.

  8. Low Genetic Diversity and High Invasion Success of Corbicula fluminea (Bivalvia, Corbiculidae (Muller, 1774 in Portugal.

    Directory of Open Access Journals (Sweden)

    Cidália Gomes

    Full Text Available The Asian clam, Corbicula fluminea, is an invasive alien species (IAS originally from Asia that has spread worldwide causing major ecological and economic impacts in aquatic ecosystems. Here, we evaluated C. fluminea genetic (using COI mtDNA, CYTb mtDNA and 18S rDNA gene markers, morphometric and sperm morphology variation in Portuguese freshwater ecosystems. The COI marker revealed a single haplotype, which belongs to the Asian FW5 invasive lineage, suggesting a common origin for all the 13 Portuguese C. fluminea populations analysed. Morphometric analyses showed differences between the populations colonizing the North (with the exception of the Lima River and the Centre/South ecosystems. The sperm morphology examination revealed the presence of biflagellate sperm, a distinctive character of the invasive androgenetic lineages. The low genetic variability of the Portuguese C. fluminea populations and the pattern of sperm morphology have been illuminating for understanding the demographic history of this invasive species. We hypothesize that these populations were derived from a unique introductory event of a Corbicula fluminea FW5 invasive androgenic lineage in the Tejo River, which subsequently dispersed to other Portuguese freshwater ecosystems. The C. fluminea asexual reproductive mode may have assisted these populations to become highly invasive despite the low genetic diversity.

  9. Novel Microsatellite Markers of Meretrix petechialis and Cross-species Amplification in Related Taxa (Bivalvia: Veneroida

    Directory of Open Access Journals (Sweden)

    Hyun-Sook Ko

    2012-11-01

    Full Text Available The Asian hard clam, Meretrix petechialis, is an economically important bivalve, but its catch and population sizes are decreasing rapidly, owing to many factors, including large-scale reclamation of its natural habitat on the western coast of the Korean peninsula. Attempts to restore the resources and production of this species require genetic structure and diversity information. In this study, we developed 15 microsatellite markers from a partial genomic library enriched in GT repeats. Nine of these markers were polymorphic, with an average allele number of six, and six were monomorphic in 95 tested individuals. No linkage disequilibrium was found between any pair of loci (p > 0.05, and deviations from the Hardy–Weinberg equilibrium (HWE test showing excess of heterozygotes was observed in only one of nine loci. In addition, no null alleles or genetic differentiation between two tested populations were detected. A cross-species amplification in 12 species of four families resulted in two M. petechialis-specific loci and three possible universal markers. This information will be useful in the future development of high-quality artificial seedlings and sustainable resource management.

  10. Molecular Cytogenetics in Trough Shells (Mactridae, Bivalvia): Divergent GC-Rich Heterochromatin Content.

    Science.gov (United States)

    García-Souto, Daniel; Pérez-García, Concepción; Kendall, Jack; Pasantes, Juan J

    2016-01-01

    The family Mactridae is composed of a diverse group of marine organisms, commonly known as trough shells or surf clams, which illustrate a global distribution. Although this family includes some of the most fished and cultured bivalve species, their chromosomes are poorly studied. In this work, we analyzed the chromosomes of Spisula solida, Spisula subtruncata and Mactra stultorum by means of fluorochrome staining, C-banding and fluorescent in situ hybridization using 28S ribosomal DNA (rDNA), 5S rDNA, H3 histone gene and telomeric probes. All three trough shells presented 2n = 38 chromosomes but different karyotype compositions. As happens in most bivalves, GC-rich regions were limited to the nucleolus organizing regions in Spisula solida. In contrast, many GC-rich heterochromatic bands were detected in both Spisula subtruncata and Mactra stultorum. Although the three trough shells presented single 5S rDNA and H3 histone gene clusters, their chromosomal locations differed. Regarding major rDNA clusters, while Spisula subtruncata presented a single cluster, both Spisula solida and Mactra stultorum showed two. No evidence of intercalary telomeric signals was detected in these species. The molecular cytogenetic characterization of these taxa will contribute to understanding the role played by chromosome changes in the evolution of trough shells. PMID:27537915

  11. Paralytic shellfish poisoning toxins accumulation in purple clam Hiatula rostrata and toxic effect on milkfish Chanos chanos larval fish.

    Science.gov (United States)

    Chen, C Y

    2001-11-01

    In an attempt to feed purple clams (Hiatula rostrata) with dinoglagellate Alexandrium minutum, the maximal accumulation toxicity of paralytic shellfish poisoning (PSP) toxins reached 40.6 MU/g on day 5 of feeding. Subsequently, the toxicity increased no further, although purple clams ingested more toxic algae. Furthermore, when milkfish (Chanos chanos) larvae were treated with toxic, nontoxic A. minutum or PSP toxin-containing extract in the water medium, it was found that the mortality of fish increased with the increasing concentrations of toxic algae. PSP toxin-containing extract did not show any toxic effect on milkfish larvae.

  12. Effects of burial by the disposal of dredged materials from the Columbia River on Pacific razor clams (Siliqua patula)

    Energy Technology Data Exchange (ETDEWEB)

    Vavrinec, John; Kohn, Nancy P.; Hall, Kathleen D.; Romano, Brett A.

    2007-05-07

    Annual maintenance of the Columbia River navigation channel requires the U.S. Army Corps of Engineers (Corps) to dredge sediment from the river and dispose of the sediment in coastal areas at the mouth of the Columbia River. Some of these disposal areas can be as shallow as 12 m deep in waters off the coastal beaches, and dredged material disposal activities have therefore raised concerns of impacts to local razor clam (Siliqua patula) populations that are prevalent in the area. The Corps’ Portland District requested that the Marine Sciences Laboratory of the U.S. Department of Energy’s Pacific Northwest National Laboratory conduct laboratory experiments to evaluate the potential impacts of burial by dredged material to razor clams during disposal. Prior modeling of disposal events indicates three stresses that could have an impact on benthic invertebrates: convective descent and bottom encounter (compression forces due to bottom impact), dynamic collapse and spreading (surge as material washes over the bottom), and mounding (burial by material). Because the razor clam is infaunal, the effects of the first two components should be minimal, because the clams should be protected by substrate that is not eroded in the event and by the clams’ rapid digging capabilities. The mound resulting from the disposal, however, would bury any clams remaining in the footprint under as much as 12 cm of new sediment according to modeling, and the clams’ reaction to such an event and to burial is not known. Although the literature suggests that razor clams may be negatively affected by siltation and therefore perhaps by dredging and disposal activity, as well, impacts of this type have not been demonstrated. The primary purpose of this study was to evaluate the potential impacts of dredge material disposal on adult subtidal razor clam populations at the mouth of the Columbia River. Using the parameters defined in a previous model, a laboratory study was created in which a

  13. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Franco, E-mail: baldi@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Gallo, Michele; Marchetto, Davide [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Faleri, Claudia [Department of Environmental Science ‘G. Sarfatti’, University of Siena, 53100 Siena (Italy); Maida, Isabel; Fani, Renato [Dipartimento di Biologia Evoluzionistica, Via Romana, 17, University of Florence, 50125 Florence (Italy)

    2013-08-15

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified

  14. Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard-shell clams, Mercenaria mercenaria.

    Science.gov (United States)

    Dickinson, Gary H; Matoo, Omera B; Tourek, Robert T; Sokolova, Inna M; Beniash, Elia

    2013-07-15

    Ocean acidification due to increasing atmospheric CO2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21 weeks of exposure to different levels of CO2 (~395, 800 and 1500 μatm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated PCO2. Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated PCO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated PCO2 (~800-1500 μatm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800 μatm PCO2) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high PCO2 (~1500 μatm). Mechanical properties of the shell (measured as microhardness and

  15. Oxidative DNA damage levels and catalase activity in the clam Ruditapes decussatus as pollution biomarkers of Tunisian marine environment.

    Science.gov (United States)

    Jebali, Jamel; Banni, Mohamed; de Almeida, Eduardo Alves; Boussetta, Hamadi

    2007-01-01

    Levels of the oxidative DNA damage 7, 8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) and catalase (CAT) activity were measured in the digestive gland and gills of clams Ruditapes decussatus, related to the presence of pollutants along Tunisian marine environment. Increased levels of CAT were observed in tissues of clams from all the sites studied, compared to control values, and elevated 8-oxodG levels were observed at specific sites. Results obtained in this work indicate that the measurement of 8-oxodG levels and CAT activity in tissues of R. decussatus is promising in pollution monitoring studies of the Tunisian marine environment. PMID:16897518

  16. Development and application of a new material for control of asiatic clams

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, L.A.; Austin, D.M.; Post, R.M.; McClellan, E.

    1988-01-01

    Asiatic-clam-related macrofouling has been estimated to cost US industry more than $1 billion annually. These costs are related flow restrictions, reduced cooling efficiency, maintenance expenses, replacement of damaged equipment, and forced outages. The vulnerability of fire protection systems and safety-related systems in nuclear-fueled generating stations has aroused special concerns. In the spring of 1987, Philadelphia Electric was approached by Betz Laboratories to consider an application of their recently developed molluscicide at the Peach Bottom Atomic Station. The molluscicide was first applied in December 1987 to the high-pressure service water systems. Results are summarized.

  17. Development and application of a new material for control of asiatic clams

    International Nuclear Information System (INIS)

    Asiatic-clam-related macrofouling has been estimated to cost US industry more than $1 billion annually. These costs are related flow restrictions, reduced cooling efficiency, maintenance expenses, replacement of damaged equipment, and forced outages. The vulnerability of fire protection systems and safety-related systems in nuclear-fueled generating stations has aroused special concerns. In the spring of 1987, Philadelphia Electric was approached by Betz Laboratories to consider an application of their recently developed molluscicide at the Peach Bottom Atomic Station. The molluscicide was first applied in December 1987 to the high-pressure service water systems. Results are summarized

  18. Expression of cyp1a protein in the freshwater clam Corbicula fluminea (Müller

    Directory of Open Access Journals (Sweden)

    Vranković Jelena

    2011-01-01

    Full Text Available We investigated the expression of CYP1A in the foot, gill and visceral mass of the freshwater clam Corbicula fluminea in relation to polychlorinated biphenyls (PCBs exposure. Different PCBs congeners were found in the foot and visceral mass, while the expression of CYP1A was observed only in the visceral mass. However the level of CYP1A expression in the visceral mass was not related to the level of PCBs present in the tissue. Our results indicate a higher rate of biotransformation and lower threshold of CYP1A induction in the visceral mass compared with other tissues.

  19. Contaminant assessment of fish, rangia clams, and sediments in the lower Pamlico River, North Carolina

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-01

    Samples of sediment, rangia clams (Rangia cuneata), gizzard shad (Dorosoma cepedianum), and longnose gar (Lepisosteus osseus) were collected from five sites in the lower Pamlico River and analyzed for elemental contaminants, organochlorines, aliphatic hydrocarbons, and polynuclear aromatic hydrocarbons. Most sample concentrations were either beneath the detection limit or too low to be associated with biological impacts. However, sediment sample concentrations of cadmium and fluoride were observed at levels that could be associated with biological impacts at one of the sites which was located near the discharge from a large phosphate mining operation.

  20. Gastropoda-Bivalvia Fauna And Neogene-Quaternary Stratigraphy of the Southwest of Dardanelles (Çanakkale-NWAnatolia)

    Science.gov (United States)

    Kapan, Sevinç; Kabasakal, Sinem

    2016-04-01

    Gastropoda-Bivalvia Fauna And Neogene-Quaternary Stratigraphy of the Southwest of Dardanelles (Çanakkale-NWAnatolia) Sevinç KAPAN, Sinem KABASAKAL, Çanakkale Onsekiz Mart University, Engineering Faculty, Geological Engineering Department sevinckapan_yesilyurt@hotmail.com In this study, paleontology and stratigraphy of Neogene and Quaternary units around south of the Dardanelles have been examined using Gastropoda and Bivalvia fauna. In the investigation area, the base of the sediments that belongs to Neogene, consist of the volcanics which are formed with basalts, andesites and tuff. Neogene begins unconformity with basal conglomerate which are formed with basalt and tuff gravels. The measurable thickness of the Neogene sediments is approximately 200meters in total. First fossiliferius level which consist of Lymnocardium (Euxinicardium) nobile Sabba has showed similarities with the Pontian (Late Miocene) fauna of the Eastern Paratethys. The existence of Melanopsis and Psidium species indicate that the basin has been brackish water feeding by fresh water in the Early Pliocene. Theodoxus fluviatilis (Linne), Theodoxus (Calvertia) aff. imbricata Brusina, Theodoxus (Calvertia) licherdopoli scriptus (Stefanescu), Viviparus mammatus (Stefanescu), Valvata (Valavata) sulekiana Brusina, Valvata (Cincinna) crusitensis Fontannes, Hydrobia cf grandis Cobalcescu, Hydrobia ventrosa Monfort, Melanopsis (Melanopsis) cf. bergeroni Stefanescu, , Melanopsis (Melanopsis) sandbergeri rumana Tournouer, Melanopsis (Canthidomus) hybostoma anili Taner, Melanopsis (Canthidomus) hybostoma amaradica Fontannes, Melanopsis (Canthidomus) lanceolata Neumayr, Amphimelania fossariformis (Tournouer), Melanoides tuberculata monolithica (Bukowski), Radix (Radix) peregra (Müller), Planorbarius thiollierei (Michaud), Potamida (Potamida) craiovensis craiovensis (Tournouer), Potamida (Potamida) berbestiensis (Fontannes), Unio pristinus davilai Porumbaru, Unio subexquisitus Jatzko, Anadonta zmaji

  1. The Complete Sequence of the Mitochondrial Genome of the Chamberednautilus (Mollusca: Cephalopoda)

    Energy Technology Data Exchange (ETDEWEB)

    Boore, Jeffrey L.

    2005-12-01

    Background: Mitochondria contain small genomes that arephysically separate from those of nuclei. Their comparison serves as amodel system for understanding the processes of genome evolution.Although complete mitochondrial genome sequences have been reported formore than 600 animals, the taxonomic sampling is highly biased towardvertebrates and arthropods, leaving much of the diversity yetuncharacterized. Results: The mitochondrial genome of a cephalopodmollusk, the Chambered Nautilus, is 16,258 nts in length and 59.5 percentA+T, both values that are typical of animal mitochondrial genomes. Itcontains the 37 genes that are typical for animal mtDNAs, with 15 on oneDNA strand and 22 on the other. The arrangement of these genes can bederived from that of the distantly related Katharina tunicata (Mollusca:Polyplacophora) by a switch in position of two large blocks of genes andtranspositions of four tRNA genes. There is strong skew in thedistribution of nucleotides between the two strands. There are an unusualnumber of non-coding regions and their function, if any, is not known;however, several of these demark abrupt shifts in nucleotide skew,suggesting that they may play roles in transcription and/or replication.One of the non-coding regions contains multiple repeats of a tRNA-likesequence. Some of the tRNA genes appear to overlap on the same strand,but this could be resolved if the polycistron were cleaved at thebeginning of the downstream gene, followed by polyadenylation of theproduct of the upstream gene to form a fully paired structure.Conclusions: Nautilus sp. mtDNA contains an expected gene content thathas experienced few rearrangements since the evolutionary split betweencephalopods and polyplacophorans. It contains an unusual number ofnon-coding regions, especially considering that these otherwise often aregenerated by the same processes that produce gene rearrangements. Thisappears to be yet another case where polyadenylation of mitochondrialtRNAs restores

  2. Homology and homoplasy of swimming behaviors and neural circuits in the Nudipleura (Mollusca, Gastropoda, Opisthobranchia).

    Science.gov (United States)

    Newcomb, James M; Sakurai, Akira; Lillvis, Joshua L; Gunaratne, Charuni A; Katz, Paul S

    2012-06-26

    How neural circuit evolution relates to behavioral evolution is not well understood. Here the relationship between neural circuits and behavior is explored with respect to the swimming behaviors of the Nudipleura (Mollusca, Gastropoda, Opithobranchia). Nudipleura is a diverse monophyletic clade of sea slugs among which only a small percentage of species can swim. Swimming falls into a limited number of categories, the most prevalent of which are rhythmic left-right body flexions (LR) and rhythmic dorsal-ventral body flexions (DV). The phylogenetic distribution of these behaviors suggests a high degree of homoplasy. The central pattern generator (CPG) underlying DV swimming has been well characterized in Tritonia diomedea and in Pleurobranchaea californica. The CPG for LR swimming has been elucidated in Melibe leonina and Dendronotus iris, which are more closely related. The CPGs for the categorically distinct DV and LR swimming behaviors consist of nonoverlapping sets of homologous identified neurons, whereas the categorically similar behaviors share some homologous identified neurons, although the exact composition of neurons and synapses in the neural circuits differ. The roles played by homologous identified neurons in categorically distinct behaviors differ. However, homologous identified neurons also play different roles even in the swim CPGs of the two LR swimming species. Individual neurons can be multifunctional within a species. Some of those functions are shared across species, whereas others are not. The pattern of use and reuse of homologous neurons in various forms of swimming and other behaviors further demonstrates that the composition of neural circuits influences the evolution of behaviors. PMID:22723353

  3. The complete mitochondrial genome of Galba pervia (Gastropoda: Mollusca, an intermediate host snail of Fasciola spp.

    Directory of Open Access Journals (Sweden)

    Guo-Hua Liu

    Full Text Available Complete mitochondrial (mt genomes and the gene rearrangements are increasingly used as molecular markers for investigating phylogenetic relationships. Contributing to the complete mt genomes of Gastropoda, especially Pulmonata, we determined the mt genome of the freshwater snail Galba pervia, which is an important intermediate host for Fasciola spp. in China. The complete mt genome of G. pervia is 13,768 bp in length. Its genome is circular, and consists of 37 genes, including 13 genes for proteins, 2 genes for rRNA, 22 genes for tRNA. The mt gene order of G. pervia showed novel arrangement (tRNA-His, tRNA-Gly and tRNA-Tyr change positions and directions when compared with mt genomes of Pulmonata species sequenced to date, indicating divergence among different species within the Pulmonata. A total of 3655 amino acids were deduced to encode 13 protein genes. The most frequently used amino acid is Leu (15.05%, followed by Phe (11.24%, Ser (10.76% and IIe (8.346%. Phylogenetic analyses using the concatenated amino acid sequences of the 13 protein-coding genes, with three different computational algorithms (maximum parsimony, maximum likelihood and bayesian analysis, all revealed that the families Lymnaeidae and Planorbidae are closely related two snail families, consistent with previous classifications based on morphological and molecular studies. The complete mt genome sequence of G. pervia showed a novel gene arrangement and it represents the first sequenced high quality mt genome of the family Lymnaeidae. These novel mtDNA data provide additional genetic markers for studying the epidemiology, population genetics and phylogeographics of freshwater snails, as well as for understanding interplay between the intermediate snail hosts and the intra-mollusca stages of Fasciola spp..

  4. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yucheng [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Xiao, Chengwen, E-mail: emoryxiao@163.com [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Xu; Yue, Jiajia; Zhu, Qiang [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-06-15

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile.

  5. Real-Time Mesoscale Forecast Support During the CLAMS Field Campaign

    Institute of Scientific and Technical Information of China (English)

    WANG Donghai; P. MINNIS; T. P. CHARLOCK; D. K. ZHOU; F. G. ROSE; W. L. SMITH; W. L. SMITH Jr.; L. NGUYEN

    2007-01-01

    This paper reports the use of a specialized, mesoscale, numerical weather prediction (NWP) system and a satellite imaging and prediction system that were set up to support the CLAMS (Chesapeake Lighthouse and Aircraft Measurements for Satellites) field campaign during the summer of 2001. The primary objective of CLAMS was to validate satellite-based retrievals of aerosol properties and vertical profiles of the radiative flux, temperature and water vapor. Six research aircraft were deployed to make detailed coincident measurements of the atmosphere and ocean surface with the research satellites that orbited overhead. The mesoscale weather modeling system runs in real-time to provide high spatial and temporal resolution for forecasts that are delivered via the World Wide Web along with a variety of satellite imagery and satellite location predictions. This system is a multi-purpose modeling system capable of both data analysis/assimilation and multi-scale NWP ranging from cloud-scale to larger than regional scale. This is a three-dimensional, nonhydrostatic compressible model in a terrain-following coordinate. The model employs advanced numerical techniques and contains detailed interactive physical processes. The utility of the forecasting system is illustrated throughout the discussion on the impact of the surface-wind forecast on BRDF (Bidirectional Reflectance Distribution Function) and the description of the cloud/moisture forecast versus the aircraft measurement.

  6. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    International Nuclear Information System (INIS)

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile

  7. Development of molecular resources for an intertidal clam, Sinonovacula constricta, using 454 transcriptome sequencing.

    Directory of Open Access Journals (Sweden)

    Donghong Niu

    Full Text Available BACKGROUND: The razor clam Sinonovacula constricta is a benthic intertidal bivalve species with important commercial value. Despite its economic importance, knowledge of its transcriptome is scarce. Next generation sequencing technologies offer rapid and efficient tools for generating large numbers of sequences, which can be used to characterize the transcriptome, to develop effective molecular markers and to identify genes associated with growth, a key breeding trait. RESULTS: Total RNA was isolated from the mantle, gill, liver, siphon, gonad and muscular foot tissues. High-throughput deep sequencing of S. constricta using 454 pyrosequencing technology yielded 859,313 high-quality reads with an average read length of 489 bp. Clustering and assembly of these reads produced 16,323 contigs and 131,346 singletons with average lengths of 1,376 bp and 458 bp, respectively. Based on transcriptome sequencing, 14,615 sequences had significant matches with known genes encoding 147,669 predicted proteins. Subsequently, previously unknown growth-related genes were identified. A total of 13,563 microsatellites (SSRs and 13,634 high-confidence single nucleotide polymorphism loci (SNPs were discovered, of which almost half were validated. CONCLUSION: De novo sequencing of the razor clam S. constricta transcriptome on the 454 GS FLX platform generated a large number of ESTs. Candidate growth factors and a large number of SSRs and SNPs were identified. These results will impact genetic studies of S. constricta.

  8. Zoosporulation of a new Perkinsus species isolated from the gills of the softshell clam Mya arenaria

    Directory of Open Access Journals (Sweden)

    Mclaughlin S.M.

    2000-06-01

    Full Text Available A gill-associated Perkinsus sp. isolated from the softshell clam (Mya arenaria is described as a new species, P. chesapeaki sp. nov. Examination of the parasite in seawater cultures revealed life cycle stages and zoosporulation processes similar to those described for other species of the genus Perkinsus. Prezoosporangia developed thickened cell walls upon contraction of the cytoplasm and development of a distinctive clear area between the cell wall and the protoplast. Successive bipartition of the protoplast led to the formation of hundred's of zoospores within mature sporangia. Zoospores were released into seawater through one or more discharge tubes. Ultrastructural studies revealed an oblong zoospore possessing two flagella that arose from a concave side located in the upper third of the zoospore body. The anterior flagellum possessed a unilateral array of hair-like structures. A large anterior vacuole and basolateral nucleus dominated the cytoplasm of the zoospore body. The presence of a rudimentary apical complex including on open-sided conoid, rhoptries, micronemes, and subpellicular microtubules were also discerned. Differences in zoospore morphology, and sequence analyses of two genes previously reported, support the designation of the gill-associated Perkinsus from the softshell clam as a new species

  9. Fishery of the short-necked clam Paphia undulata in Southern Negros Occidental, Central Philippines

    Directory of Open Access Journals (Sweden)

    Karen A. Villarta

    2010-06-01

    Full Text Available This study documents the fishery of the short-necked clam Paphia undulata in coastal waters of southern Negros Occidental. Catch and effort estimates were determined based on daily records of compressor divers gathered between February-July 2008 in Himamaylan City and July 2008-May 2009 in the town of Hinigaran. Fishing and marketing practices in both areas were also documented and population biology information noted.Compared to earlier conditions, present fishing patterns show a worsened stage of overexploitation primarily characterized by collection of predominantly small and immature (mostly <45 mm shell lengths sizes. Intensity/duration and location of fishing also varied due to both abundance and demand factors.The difference in sizes of clams and the varying fishing durations in each area suggest a non-uniform pattern of settlement resulting most likely from differential larval recruitment, the likely factors causing the local boom and bust fishery. The larger and long term extent of the effect of these factors can only be further investigated by parallel 2-3 year fishery-dependent and -independent surveys

  10. Studies on molluscan glycosaminoglycans (GAG) from backwater clam Donax cuneatus (Linnaeus)

    Institute of Scientific and Technical Information of China (English)

    P Vijayabaskar; ST Somasundaram

    2012-01-01

    Objective: To investigate the potent and specific anticoagulant activity of molluscan glycosaminoglycans (GAGs) isolated from whole clam tissue Donax cuneatus (D. cuneatus). Methods: Purification of few milligram quantities of GAGs from this tissue sample permitted a thorough examination of its anticoagulant activity characterization, which was partially purified by fractionation by anion exchange chromatography using DEAE cellulose column. The isolated crude and partially purified fractionated sample was showing metachromatic shift while using azure-A. The sample also exhibited prominent of biological and anti-fXa anticoagulant activity assays. Mobility was analyzed by two different buffer systems using agarose gel electrophoresis.Results:The fractionated molluscan GAG was also found to have similar peaks as that of standard heparin when assessed by the FT-IR spectrum. Finally molecular weight was determined by the gradient PAGE for crude and fractionated-II GAG, which were found to be 65 000 Da and 50 000 Da, respectively. Conclusions: The bivalve GAG was subjected to fractionation for further purification and its chemical components were analyzed. The fractionated clam heparin also showed substantial in vitro anticoagulant activity than that of commercial heparins.

  11. Crustaceans associated with Cnidaria, Bivalvia, Echinoidea and Pisces at São Tomé and Príncipe islands.

    Directory of Open Access Journals (Sweden)

    Wirtz, P.

    2008-01-01

    Full Text Available Symbiotic crustaceans were searched for at sea anemones (Actiniaria, encrusting anemones (Zoantharia, horny coral (Gorgonaria, black coral (Antipatharia, bivalves (Bivalvia, and sea urchins (Echinoidea at São Tomé and Príncipe Islands (Gulf of Guinea, eastern central Atlantic. Sixteen species of crustaceans were found in association with these invertebrate hosts; eleven of them were new records for the area and two species, belonging to the genera Hippolyte and Heteromysis, were new for science. The thalassinid Axiopsis serratifrons was occasionally associated with an undescribed species of gobiid fish.

  12. Sodium Gill Potential as a Tool to Monitor Valve Closure Behavior in Freshwater Clam Corbicula fluminea in Response to Copper

    Directory of Open Access Journals (Sweden)

    Wei-Yu Chen

    2008-09-01

    Full Text Available Valve closure behavior in freshwater clam Corbicula fluminea is a biologically sensitive endpoint. The purpose of this paper was to derive an electrophysiological response model of C. fluminea to assess copper (Cu-sodium (Na interactions in gill membrane, whereby valve closure behavior and Cu toxicity could be monitored. The proposed model was based on the integration of Cu bioavailability, Na and Cu internalizations, and electrochemically-based gill potentials. Based on Na active transport under non-equilibrium conditions, predicted gill potential of -8.2 mV agreed reasonably well with published the measured transepithelial potential of -7 mV in C. fluminea. Our proposed framework captured the general features observed in model applications including: (i 50% inhibitory Cu2+ activities for Na membrane potential (ENa and uptake rate (JNa were estimated to be 0.072 and 0.043 mM, respectively, with a stoichiometry of 3Cu2+: 1ENa and 1JNa; (ii the external Cu2+-dependent internal Na concentration could be parsimoniously estimated, and (iii the site-specific clam gill potentials could be monitored. Here we provided a new approach to monitor waterborne metal toxicity to reduce the nationwide economic losses due to bans on harvesting of contaminated clam and the potential risks to the health of clams.

  13. Induction of a multixenobiotic resistance protein (MXR) in the Asiatic clam Corbicula fluminea after heavy metals exposure.

    Science.gov (United States)

    Achard, M; Baudrimont, M; Boudou, A; Bourdineaud, J P

    2004-05-12

    Multixenobiotic resistance mechanisms (MXR) related to the mammalian P-glycoprotein multidrug transporter protein (P-gp) are known to occur in several marine invertebrates. In the present work, we report on the induction of an MXR protein by various heavy metals in the gills of the freshwater clam Corbicula fluminea. The evaluation of the MXR protein level was assessed by Western blot using a specific monoclonal antibody raised against the human P-gp (C219). A field transplantation experiment, where clams were caged in a gradient relative to an industrial site, demonstrated a positive relationship between MXR levels and (a) metal pollution (Cd and Zn) in the environment and (b) metal bioaccumulation in the gills. To establish this correlative relationship, clams were exposed to different levels of cadmium (15-60 microg l(-1)) for up to 15 days in a controlled laboratory experiment. MXR protein levels increased in time for all treatments (including the control). However, the highest levels of MXR protein titer were expressed in clams that had been exposed to the lowest dose of cadmium. The causes for this observed inverse relationship between the exposure dose and the MXR induction is discussed. MXR protein titer was also shown to be induced by other heavy metals (zinc, inorganic mercury, and copper). PMID:15084411

  14. Effect of strain rate on the mechanical properties of CLAM steel in liquid PbLi eutectic

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing; Huang, Qunying [University of Science and Technology of China, Hefei, Anhui 230031 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Jiang, Zhizhong, E-mail: zhizhong.jiang@fds.org.cn [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhu, Zhiqiang; Li, Mingyang [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2013-10-15

    Highlights: • The mechanical properties of CLAM steel in liquid PbLi eutectic were studied firstly. • Tensile tests of RAFMs in liquid PbLi were conducted at a higher temperature of 480 °C. • No obvious liquid metal embrittlement (LME) was found in the given test conditions. -- Abstract: The liquid PbLi blanket is one of the most promising designs for fusion reactors and under extensive research in the world. China Low Activation Martensitic (CLAM) steel has been chosen as the primary candidate structural material for PbLi blanket in China. The effect of strain rate on mechanical properties of CLAM steel with and without liquid PbLi under Ar atmosphere has been investigated with slow strain rate tensile (SSRT) test at 480 °C. SEM observation showed the specimens tested in both environments exhibited ductility fracture with dimpled behavior. The primary tensile results tested with and without PbLi indicated that the uniform elongation of CLAM specimens was independent of strain rate, whereas the total elongation decreased with increasing strain rate. The strength properties tested with liquid PbLi under Ar increased with strain rate from 8.33 × 10{sup −6} s{sup −1} to 4.17 × 10{sup −4} s{sup −1}, but which decreased at 8.33 × 10{sup −4} s{sup −1}.

  15. Rangia and Marsh Clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, in Eastern México: Distribution, Biology and Ecology, and Historical Fisheries

    OpenAIRE

    Wakida-Kusunoki, Armando T.; MacKenzie, Jr., Clyde L.

    2004-01-01

    Rangia and marsh clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, occur in brackish waters along México’s eastern coast from the northern State of Tamaulipas to the southern State of Campeche. The clams were important to the prehispanic people in the southern part of the State of Veracruz, where they were used as food and as construction material. In modern times, they are harvested for food. The fishermen wade in shallow water and harvest the clams in soft sediments by hand...

  16. The effects of clam fishing on the properties of surface sediments in the lagoon of Venice, Italy

    Directory of Open Access Journals (Sweden)

    R. J. Aspen

    2004-01-01

    Full Text Available Harvesting of clams(Tapes philippinarum has important socio-economic and environmental implications for the Venice lagoon area, Italy. Clam harvesting disrupts the structure of benthic communities but the effects upon sediment stability and surface structure remain unclear. The effect of clam fishing on the sediment properties of the lagoon bed was investigated at two different sites, a heavily fished site (San Angelo and an infrequently fished site (San Giaccomo. Both sites were assessed for immediate impacts of fishing, using indicators of biogenic sediment stabilisation. Samples were taken at three points along three 100 m linear transects at each site prior to and post fishing. Paired samples were also taken parallel to each transect at a distance of 5m, to allow for temporal variation. Sediment stability, measured with a cohesive strength meter (CSM, was significantly higher at the less impacted site (F1,34 = 6.23, p a (chl a, colloidal-S carbohydrate and dry bulk density were observed on the transect after fishing but not adjacent to the fishing path. At the heavily impacted site, clam fishing by trawling had, in general, no significant effect on the biological and physical properties (although chl a did decrease significantly after fishing. The lack of a significant impact from fishing at the impacted site was attributed to the higher frequency of fishing occurring in this area. Hence, frequent fishing of the lagoon prevents establishment of biotic communities, preventing biostabilisation and thus reduces the stability of the surface sediment. Keywords: clam harvesting, erosion threshold, microphytobenthos, sediment, stability

  17. Quantitative determination of gymnodimine-A by high performance liquid chromatography in contaminated clams from Tunisia coastline.

    Science.gov (United States)

    Marrouchi, Riadh; Dziri, Faten; Belayouni, Nawel; Hamza, Asma; Benoit, Evelyne; Molgó, Jordi; Kharrat, Riadh

    2010-10-01

    Quantitative determination by high performance liquid chromatography (HPLC) was performed for gymnodimine-A (GYM-A), a phycotoxin responsible for the contamination of Tunisian clams. This study demonstrates a rapid and reproducible HPLC-ultraviolet (UV) method for extraction, detection and quantification of GYM-A in toxic clams. The extraction of GYM-A from the digestive gland of clams in acetone, subsequent clean-up with diethyl ether and extraction with dichloromethane is the more valid protocol. Chromatography analyses were performed using a gradient of acetonitrile-water (10:90 to 90:10), containing trifluoroacetic acid (0.1%) for 20 min at 1 mL/min rate with a C18 column. Recovery rates exceeded 96%, and limits of detection and quantification were 5 ng/mL and 8 ng/g digestive gland, respectively. Repeatability and reproducibility were tested for various samples containing different levels of GYM-A. A significant correlation was observed between toxicity level of samples and the determined amount of GYM-A. Also, the persistence of GYM-A in contaminated clams from Boughrara lagoon was demonstrated. The kinetics discharge study of GYM-A in controlled medium, during 1 month, showed that the process of depuration was biphasic with an exponential discharge of 75% of the total amount of sequestered GYM-A during the first 12 days followed by a slow discharge (>10%) for the subsequent days up to the seventeenth day. This is the first time that a quantitative study of GYM-A in clams from Tunisian coasts is performed through the development of a new method for detection and quantify of this phycotoxin. We found HPLC-UV a reliable and suitable alternative to the mouse bioassay.

  18. Comparative studies on the morphometry and physiology of European populations of the lagoon specialist Cerastoderma glaucum (Bivalvia

    Directory of Open Access Journals (Sweden)

    Katarzyna Tarnowska

    2009-09-01

    Full Text Available Seasonal changes in the morphometric and physiological parameters of the cockle Cerastoderma glaucum (Bivalvia from the Baltic Sea (GD, the North Sea (LV, and the Mediterranean Sea (BL were investigated. The cockles from GD were much smaller than those from other populations due to osmotic stress. The female to male ratios did not differ significantly from 1:1. The northern populations (GD, LV had a monocyclic reproductive pattern, whereas the southern population (BL seemed to reproduce throughout the year. Seasonal changes in the contents of biochemical components appeared to be correlated with changes in trophic conditions and the reproductive cycle. Protein content was the highest in spring for all the populations. The highest lipid contents and lowest carbohydrate contents were noted in GD and BL in spring, while no marked differences were noted among seasons in LV (probably because the data from both sexes were pooled. Respiration rates in GD were the highest among the populations, which could have been due to osmotic stress. High metabolic rates expressed by high respiration rates in GD and LV in spring and autumn could have resulted from gamete development (in spring and phytoplankton blooms (in spring and autumn.

  19. Chinese pond mussel Sinanodonta woodiana (Lea, 1834 (Bivalvia: origin of the Polish population and GenBank data

    Directory of Open Access Journals (Sweden)

    Marianna Soroka

    2014-05-01

    Full Text Available DDNA sequences of the mitochondrial cox1 gene were analysed in 4 new local populations of Sinanodonta woodiana (Bivalvia in Poland, in the first reported Polish population, and in a population from Hungary. The gene sequences of Polish specimens were identical to those of specimens from Hungary, Italy and Ukraine, but different from those of Romanian specimens (data from GenBank. According to fish farm documentation, S. woodiana had spread in Poland by 2 routes: i direct import of fish infected by glochidia of S. woodiana from Hungary; and ii indirectly, by the major distributor of thermophilous fish in Poland, Gosławice Fish Farm, which started to import Hungarian fish in the 1960s. The genetic analysis and available documentation unambiguously confirm that Polish populations of S. woodiana derive from a source population in Hungary. In addition, we noticed doubtful identification of this species in GenBank data and further research is needed to resolve this problem. 

  20. Wavelength-specific forward scattering of light by Bragg-reflective iridocytes in giant clams.

    Science.gov (United States)

    Ghoshal, Amitabh; Eck, Elizabeth; Gordon, Michael; Morse, Daniel E

    2016-07-01

    A surprising recent discovery revealed that the brightly reflective cells ('iridocytes') in the epithelia of giant clams actually send the majority of incident photons 'forward' into the tissue. While the intracellular Bragg reflectors in these cells are responsible for their colourful back reflection, Mie scattering produces the forward scattering, thus illuminating a dense population of endosymbiotic, photosynthetic microalgae. We now present a detailed micro-spectrophotometric characterization of the Bragg stacks in the iridocytes in live tissue to obtain the refractive index of the high-index layers (1.39 to 1.58, average 1.44 ± 0.04), the thicknesses of the high- and low-index layers (50-150 nm), and the numbers of pairs of layers (2-11) that participate in the observed spectral reflection. Based on these measurements, we performed electromagnetic simulations to better understand the optical behaviour of the iridocytes. The results open a deeper understanding of the optical behaviour of these cells, with the counterintuitive discovery that specific combinations of iridocyte diameter and Bragg-lamellar spacing can produce back reflection of the same colour that is also scattered forward, in preference to other wavelengths that are scattered at higher angles. We find for all values of size and wavelength investigated that more than 90% of the incident energy is carried by the photons that are scattered in the forward direction; while this forward scattering from each iridocyte shows very narrow angular dispersion (ca ±6°), the multiplicative scattering from a layer of ca 20 iridocytes broadens this dispersion to a cone of approximately ±90°. This understanding of the complex biophotonic dynamics enhances our comprehension of the physiologically, ecologically and evolutionarily significant light environment inside the giant clam, which is diffuse and nearly white at small tissue depths and downwelling, relatively monochromatic, and can be the same colour as

  1. Conchological Variability of Anadara Inaequivalvis (Bivalvia, Arcidae In the Black–Azov Sea Basin

    Directory of Open Access Journals (Sweden)

    Anistratenko V. V.

    2014-10-01

    Full Text Available Конхологическая изменчивость Anadara inaequivalvis (Bivalvia, Arcidae в Азово-Черноморском бассейне. Анистратенко В. В., Анистратенко О. Ю., Халиман И. А. - Показан широкий диа- пазон изменчивости раковины Anadara inaequivalvis (Bruguiere, 1789 - вида-вселенца в Азово- Черноморском бассейне. В изученном материале (более 900 створок выделены 6 основных форм комиссурального просвета раковины, которые, однако, не являются дискретными состояниями. Наличие промежуточных вариантов свидетельствует о плавной (непрерывной изменчивости и принадлежности всех изученных популяций к одному виду. Обсуждается варьирование некото- рых других признаков раковины Anadara: количество и скульптированность рёбер на поверхно- сти створок, количество шевронов на лигаментной площадке, форма замочного края и количество зубов замка. Сопоставление морфологических характеристик раковины Anadara из Чёрного и Азовского морей и A. inaequivalvis из юго-восточной Индии подтверждает, что границы и харак- тер изменчивости моллюсков рода Anadara, обитающих в азово-черноморском бассейне, вполне соответствуют изменчивости A. inaequivalvis из типовой

  2. Substantial changes in hemocyte parameters of Manila clam Ruditapes philippinarum two years after the Hebei Spirit oil spill off the west coast of Korea.

    Science.gov (United States)

    Hong, Hyun-Ki; Donaghy, Ludovic; Kang, Chang-Keun; Kang, Hyun-Sil; Lee, Hee-Jung; Park, Heung-Sik; Choi, Kwang-Sik

    2016-07-15

    Two years after the Hebei Spirit oil spill occurred off the west coast of Korea, we determined sub-lethal effects of the spilled oil on hemocyte parameters of Ruditapes philippinarum in the damaged areas. Clams in the spilled sites displayed unusually high proportion of granulocytes, which may result in higher phagocytosis capacity and reactive oxygen species production. Hemocytes in clams from the polluted sites also displayed less DNA damage and mortality than in the control site, possibly due to a faster phagocytosis of the impaired cells. Glycogen, the major energetic reserve, was depleted in clams from the spilled sites, potentially due to energetic consumption for maintenance of a large pool of granulocytes, detoxification processes and oxidative stress. Modified hemocyte parameters in clams in the spilled area, may reflect sub-lethal physiological stresses caused by the residual oils in the sediment, in conjunction with environmental modifications such as food availability and pathogens pattern. PMID:27132991

  3. Substantial changes in hemocyte parameters of Manila clam Ruditapes philippinarum two years after the Hebei Spirit oil spill off the west coast of Korea.

    Science.gov (United States)

    Hong, Hyun-Ki; Donaghy, Ludovic; Kang, Chang-Keun; Kang, Hyun-Sil; Lee, Hee-Jung; Park, Heung-Sik; Choi, Kwang-Sik

    2016-07-15

    Two years after the Hebei Spirit oil spill occurred off the west coast of Korea, we determined sub-lethal effects of the spilled oil on hemocyte parameters of Ruditapes philippinarum in the damaged areas. Clams in the spilled sites displayed unusually high proportion of granulocytes, which may result in higher phagocytosis capacity and reactive oxygen species production. Hemocytes in clams from the polluted sites also displayed less DNA damage and mortality than in the control site, possibly due to a faster phagocytosis of the impaired cells. Glycogen, the major energetic reserve, was depleted in clams from the spilled sites, potentially due to energetic consumption for maintenance of a large pool of granulocytes, detoxification processes and oxidative stress. Modified hemocyte parameters in clams in the spilled area, may reflect sub-lethal physiological stresses caused by the residual oils in the sediment, in conjunction with environmental modifications such as food availability and pathogens pattern.

  4. Neuromuscular development of Aeolidiella stephanieae Valdéz, 2005 (Mollusca, Gastropoda, Nudibranchia

    Directory of Open Access Journals (Sweden)

    Klussmann-Kolb Annette

    2010-01-01

    Full Text Available Abstract Background Studies on the development of the nervous system and the musculature of invertebrates have become more sophisticated and numerous within the last decade and have proven to provide new insights into the evolutionary history of organisms. In order to provide new morphogenetic data on opisthobranch gastropods we investigated the neuromuscular development in the nudibranch Aeolidiella stephanieae Valdéz, 2005 using immunocytochemistry as well as F-actin labelling in conjunction with confocal laser scanning microscopy (cLSM. Results The ontogenetic development of Aeolidiella stephanieae can be subdivided into 8 stages, each recognisable by characteristic morphological and behavioural features as well as specific characters of the nervous system and the muscular system, respectively. The larval nervous system of A. stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum, foot and posterior, visceral part of the larva. The first serotonergic and FMRFamidergic neural structures appear in the apical organ that exhibits an array of three sensory, flask-shaped and two non-sensory, round neurons, which altogether disappear prior to metamorphosis. The postmetamorphic central nervous system (CNS becomes concentrated, and the rhinophoral ganglia develop together with the anlage of the future rhinophores whereas oral tentacle ganglia are not found. The myogenesis in A. stephanieae begins with the larval retractor muscle followed by the accessory larval retractor muscle, the velar or prototroch muscles and the pedal retractors that all together degenerate during metamorphosis, and the adult muscle complex forms de novo. Conclusions Aeolidiella stephanieae comprises features of the larval and postmetamorphic nervous as well as muscular system that represent the ground plan of the Mollusca or even the Trochozoa (e. g. presence of the prototrochal or velar muscle ring. On the one hand

  5. Use of antioxidant enzymes of clam Ruditapes philippinarum as biomarker to polycyclic aromatic hydrocarbon pollution

    Science.gov (United States)

    Zhu, Lin; Tang, Xuexi; Wang, Ying; Sui, Yadong; Xiao, Hui

    2016-03-01

    The typical organic pollutant polycyclic aromatic hydrocarbon (PAH) anthracene was selected as a contaminant to investigate its effects on the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum (visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.

  6. Fluctuations of sulfate, S-bearing amino acids and magnesium in a giant clam shell

    Directory of Open Access Journals (Sweden)

    T. Yoshimura

    2014-01-01

    Full Text Available We used micro-X-ray fluorescence combined with X-ray photoabsorption spectroscopy to investigate speciation-specific sulfur profiles in the inner shell layer of a giant clam (Hippopus hippopus. The sulfate, S-bearing amino acids, and total sulfur profiles indicated that inorganic sulfate was the dominant component in the shell of this bivalve. Sulfur profiles in the inner shell layer showed clear annual fluctuations that varied by more than one order of magnitude, from K-edge XANES and comparison of Mg and S-bearing amino acids profiles indicated that a pronounced effect of the organic fraction or disordered phases were observed in aragonitic shell of H. hippopus rather than regulated substitution into the aragonite crystal lattice.

  7. Comparative Study of the Accumulation of Ni in Different Tissues of Mussels and Soft Clams

    Directory of Open Access Journals (Sweden)

    Chalkiadakis O.

    2013-04-01

    Full Text Available Two bivalves, the mussel Mytilus galloprovincialis, and the soft clam Callista chione were exposed to various Ni concentrations for a total period of 20 days, and then a depuration period of 10 days followed. Nickel accumulation in gills, mantle and the remaining body of the animals was measured after 5, 10, 15 and 20 days of exposure to Ni-contaminated seawater. The two organisms showed different behavior regarding Ni accumulation in all three tissues examined. In all concentrations, Ni accumulation increased with time in all three tissues of Mytilus galloprovincialis with gills being the most effective accumulator per dry mass. On the other hand, Callista chione showed an initial response to Ni contamination the first 5 days, followed by stabilization or even a slight decrease of Ni accumulation.

  8. Recruitment constraints in Singapore's fluted giant clam (Tridacna squamosa population--a dispersal model approach.

    Directory of Open Access Journals (Sweden)

    Mei Lin Neo

    Full Text Available Recruitment constraints on Singapore's dwindling fluted giant clam, Tridacna squamosa, population were studied by modelling fertilisation, larval transport, and settlement using real-time hydrodynamic forcing combined with knowledge of spawning characteristics, larval development, behaviour, and settlement cues. Larval transport was simulated using a finite-volume advection-diffusion model coupled to a three-dimensional hydrodynamic model. Three recruitment constraint hypotheses were tested: 1 there is limited connectivity between Singapore's reefs and other reefs in the region, 2 there is limited exchange within Singapore's Southern Islands, and 3 there exist low-density constraints to fertilisation efficacy (component Allee effects. Results showed that connectivity among giant clam populations was primarily determined by residual hydrodynamic flows and spawning time, with greatest chances of successful settlement occurring when spawning and subsequent larval dispersal coincided with the period of lowest residual flow. Simulations suggested poor larval transport from reefs located along the Peninsular Malaysia to Singapore, probably due to strong surface currents between the Andaman Sea and South China Sea combined with a major land barrier disrupting larval movement among reefs. The model, however, predicted offshore coral reefs to the southeast of Singapore (Bintan and Batam may represent a significant source of larvae. Larval exchange within Singapore's Southern Islands varied substantially depending on the locations of source and sink reefs as well as spawning time; but all simulations resulted in low settler densities (2.1-68.6 settled individuals per 10,000 m(2. Poor fertilisation rates predicted by the model indicate that the low density and scattered distribution of the remaining T. squamosa in Singapore are likely to significantly inhibit any natural recovery of local stocks.

  9. Clam dredging effects and subsequent recovery of benthic communities at different depth ranges.

    Science.gov (United States)

    Constantino, R; Gaspar, M B; Tata-Regala, J; Carvalho, S; Cúrdia, J; Drago, T; Taborda, R; Monteiro, C C

    2009-03-01

    This study aimed to assess the potential effects of clam dredging and the subsequent recovery of the benthic environment. Two experimental areas located at 6 and 18m depth were established in order to analyse whether impacts and recovery of benthic environment are depth-related. Study areas were located within an area closed to dredging and two different plots were established at both depths. One of the plots was subjected to intense clam dredge-fishing, while the other was undisturbed and therefore used as control. Sampling followed a BACI design, with samples for macrobenthic, meiobenthic and sediment particle size analysis being taken by SCUBA divers from both areas before and after fishing stress. For both depths, impacts on the benthic environment were very low resulting in high recovery rates. Nevertheless, at shallower depths communities demonstrated a faster recovery. It was shown that depending on the faunal component used as a bioindicator, different results can be observed. Generally deposit-feeding organisms with scales or chitinous plates and vermiform shape (mainly crustaceans, polychaetes and ophiuroids), without external protection, were the most affected by dredging, while some polychaetes without external protection and with a carnivorous feeding mode seemed to be enhanced by fishing. The low level of perturbations induced by the dredging activities was comparable to the impact of surface waves on the bottom, as experiments were undertaken in wave-dominated environments. The coexistence of storm events during the study period proved to have similar or even more deleterious effects on the benthic environment. It appears that communities from hydrodynamic fishing grounds that are well adapted to natural physical stress are not highly affected by dredging. PMID:19131099

  10. Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting.

    Science.gov (United States)

    Gray, Charles A

    2016-01-01

    Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches. PMID:26731102

  11. Effects of Freshwater Clam Extract Supplementation on Time to Exhaustion, Muscle Damage, Pro/Anti-Inflammatory Cytokines, and Liver Injury in Rats after Exhaustive Exercise

    OpenAIRE

    Kuang-Wen Liao; Ru-Ping Lee; Bang-Gee Hsu; Yi-Han Chiu; Tai-Chu Peng; Fwu-Lin Yang; Wen-Tien Wu; Kuo-Chin Huang

    2013-01-01

    The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea) have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE) supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC); SC group with FCE supplementation (SC+FCE); exhaustive exercis...

  12. Effects of elevated carbon dioxide concentrations on survivorship in zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea)

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, R.F.; Matthews, M.A.; Shaffer, L.R.; Johnson, P.D. [Univ. of Texas, Arlington, TX (United States)

    1995-06-01

    In order to determine their tolerance to elevated concentrations of carbon dioxide, Asian clams and zebra mussels were collected. Subsamples of both species were acclimated to 25{degrees}C>14 days and then exposed in water at 25{degrees}C to various concentrations of CO{sub 2} and survivorship recorded. Zebra mussels were allowed to byssally attach prior to testing. Media CO{sub 2} concentrations were maintained by continuous bubbling with appropriate gas mixtures. Gas treatment included: (1) anoxia; (2) hypercapnic anoxia; and (3) hypercapnic normoxia. Deaths were recorded in subsamples of both species every 12-24 h until 100% mortality was achieved. No significant mortality occurred among specimens of either species in air bubbled control media in any experiment. Mortality time of zebra mussels exposed to anoxia under 100% N{sub 2} was 103.7 h and of Asian clams, 349.7 h. Mortality was more rapid among samples of both species exposed to anoxia under 100% CO{sub 2}, mean time to death being 43.6 h for zebra mussels and 46.3 h for Asian clams. There was no difference in the survivorship of samples of either species under atmospheres of either 5% CO{sub 2} and 95% N{sub 2} or 100% N{sub 2}, however, Asian clams survived anoxia under either atmosphere 4 to 5 times longer than did zebra mussels. There was no significant mortality among Asian clam or zebra mussel samples after a 39 day exposure to hypercapnic normoxia. While exposure to hypercapnic normoxia under an atmosphere of 5% CO{sub 2}:19% O{sub 2}:76% N{sub 2} did not induce mortality in zebra mussel samples, it completely suppressed all byssal thread production after 7 days of exposure and induced all sampled individuals to release from their byssal attachments within 10 days of exposure. These results indicate that CO{sub 2} injection may be an easily applied, cost-effective, environmentally acceptable molluscicide for mitigation and control of raw water system macrofouling by Asian clams and zebra mussels.

  13. Developmental Transcriptome Analysis and Identification of Genes Involved in Larval Metamorphosis of the Razor Clam, Sinonovacula constricta.

    Science.gov (United States)

    Niu, Donghong; Wang, Fei; Xie, Shumei; Sun, Fanyue; Wang, Ze; Peng, Maoxiao; Li, Jiale

    2016-04-01

    The razor clam Sinonovacula constricta is an important commercial species. The deficiency of developmental transcriptomic data is becoming the bottleneck of further researches on the mechanisms underlying settlement and metamorphosis in early development. In this study, de novo transcriptome sequencing was performed for S. constricta at different early developmental stages by using Illumina HiSeq 2000 paired-end (PE) sequencing technology. A total of 112,209,077 PE clean reads were generated. De novo assembly generated 249,795 contigs with an average length of 585 bp. Gene annotation resulted in the identification of 22,870 unigene hits against the NCBI database. Eight unique sequences related to metamorphosis were identified and analyzed using real-time PCR. The razor clam reference transcriptome would provide useful information on early developmental and metamorphosis mechanisms and could be used in the genetic breeding of shellfish. PMID:26921240

  14. The MIRACLE Project: An integrated approach to understanding biogeochemical cycling of mercury and its relationship with lagoon clam farming

    Science.gov (United States)

    Covelli, Stefano

    2012-11-01

    The "MIRACLE" Project was aimed at two specific issues: understanding Hg biogeochemical cycling in the Marano and Grado Lagoon and testing the coexistence of clam farming with Hg contamination in the sediments. Mercury contamination was measured in several matrices (water, sediment, biota) and its mobility was tested along with its speciation in relation to biogeochemical processes occurring in the lagoon environment, where bacterial communities have a primary role in converting Hg to its more toxic form, methylmercury (MeHg). Bioaccumulation of the Hg species was investigated on natural and seeded clams (Ruditapes philippinarum), the most important commercial bivalves in the Lagoon. The Editorial summarizes the main results obtained from this multidisciplinary study and reported in the Special Issue.

  15. Developmental Transcriptome Analysis and Identification of Genes Involved in Larval Metamorphosis of the Razor Clam, Sinonovacula constricta.

    Science.gov (United States)

    Niu, Donghong; Wang, Fei; Xie, Shumei; Sun, Fanyue; Wang, Ze; Peng, Maoxiao; Li, Jiale

    2016-04-01

    The razor clam Sinonovacula constricta is an important commercial species. The deficiency of developmental transcriptomic data is becoming the bottleneck of further researches on the mechanisms underlying settlement and metamorphosis in early development. In this study, de novo transcriptome sequencing was performed for S. constricta at different early developmental stages by using Illumina HiSeq 2000 paired-end (PE) sequencing technology. A total of 112,209,077 PE clean reads were generated. De novo assembly generated 249,795 contigs with an average length of 585 bp. Gene annotation resulted in the identification of 22,870 unigene hits against the NCBI database. Eight unique sequences related to metamorphosis were identified and analyzed using real-time PCR. The razor clam reference transcriptome would provide useful information on early developmental and metamorphosis mechanisms and could be used in the genetic breeding of shellfish.

  16. Microstructure and microhardness of CLAM steel irradiated up to 20.8 dpa in STIP-V

    Science.gov (United States)

    Peng, Lei; Ge, Hongen; Dai, Yong; Huang, Qunying; Ye, Minyou

    2016-01-01

    Specimens of China low activation martensitic (CLAM) steel were irradiated in the fifth experiment of SINQ target irradiation program (STIP-V) up to 20.8 dpa/1564 appm He. Microhardness measurements and transmission electron microscope (TEM) observations have been performed to investigate irradiation induced hardening effects. The results of CLAM steel specimens show similar trend in microhardness and microstructure changes with irradiation dose, compared to F82H/Optimax-A steels irradiated in STIP-I/II. Defects and helium bubbles were observed in all specimens, even at a very low dose of 5.4 dpa. For defects and bubbles, the mean size and number density increased with increasing irradiation dose to 13 dpa, and then the mean size increased and number density decreased with the increasing irradiation dose to 20.8 dpa.

  17. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    International Nuclear Information System (INIS)

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  18. De novo assembly and characterization of two transcriptomes reveal multiple light-mediated functions in the scallop eye (Bivalvia: Pectinidae.

    Directory of Open Access Journals (Sweden)

    Autum N Pairett

    Full Text Available BACKGROUND: The eye has evolved across 13 separate lineages of molluscs. Yet, there have been very few studies examining the molecular machinary underlying eye function of this group, which is due, in part, to a lack of genomic resources. The scallop (Bivalvia: Pectinidae represents a compeling molluscan model to study photoreception due to its morphologically novel and separately evolved mirror-type eye. We sequenced the adult eye transcriptome of two scallop species to: 1 identify the phototransduction pathway components; 2 identify any additional light detection functions; and 3 test the hypothesis that molluscs possess genes not found in other animal lineages. RESULTS: A total of 3,039 contigs from the bay scallop, Argopecten irradians and 26,395 contigs from the sea scallop, Placopecten magellanicus were produced by 454 sequencing. Targeted BLAST searches and functional annotation using Gene Ontology (GO terms and KEGG pathways identified transcripts from three light detection systems: two phototransduction pathways and the circadian clock, a previously unrecognized function of the scallop eye. By comparing the scallop transcriptomes to molluscan and non-molluscan genomes, we discovered that a large proportion of the transcripts (7,776 sequences may be specific to the scallop lineage. Nearly one-third of these contain transmembrane protein domains, suggesting these unannotated transcripts may be sensory receptors. CONCLUSIONS: Our data provide the most comprehensive transcriptomic resource currently available from a single molluscan eye type. Candidate genes potentially involved in sensory reception were identified, and are worthy of further investigation. This resource, combined with recent phylogenetic and genomic data, provides a strong foundation for future investigations of the function and evolution of molluscan photosensory systems in this morphologically and taxonomically diverse phylum.

  19. Population dynamics of freshwater oyster Etheria elliptica (Bivalvia: Etheriidae in the Pendjari River (Benin-Western Africa

    Directory of Open Access Journals (Sweden)

    Akélé G.D.

    2015-01-01

    Full Text Available Etheria elliptica (Bivalvia: Etheriidae is the only freshwater oyster occurring in Africa. The current study provides the first data on the population structure, growth, age, mortality and exploitation status of this species in the Pendjari River. E. elliptica length-frequency data were collected monthly from January to December 2009 and analyzed with FiSAT software. Population parameters including the asymptotic length (L∞ and growth coefficient (K were assessed to evaluate the stock status. The recruitment pattern was modeled with a FiSAT routine. The asymptotic length (L∞ was 14.75 cm, while the growth coefficient (K was 0.38 year-1. The growth performance index (ø′ reached 1.92. Specimens of Etheria elliptica reached a mean size of 4.66 cm and 6.41 cm at the end of one year and 1.5 years, respectively. We estimated total mortality (Z, natural mortality (M and fishing mortality (F to be 2.90 year-1, 1.16 year-1 and 1.74 year-1, respectively. The recruitment pattern was continuous over the year with one major peak event during the rainy season (July. The exploitation rate (E = 0.60 revealed that the freshwater oyster was probably facing overexploitation due to lack of a minimum limit size and also due to an increase in the harvesting effort. Therefore, efficient management methods were urgently required to conserve the species. The return of empty shells into the water to increase the recruitment surface, rotation planning among harvesting sites and the imposition of a minimum limit size were recommendations made in order to ensure the sustainable exploitation of wild stocks.

  20. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta

    OpenAIRE

    Yun Li; Sadiq, Faizan A.; Li Fu; Hui Zhu; Minghua Zhong; Muhammad Sohail

    2016-01-01

    Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans T3 proteases hydrolysate (37.84%) and alcalase (30.55%). The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibit...

  1. Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum.

    Science.gov (United States)

    Kang, Hee Yoon; Lee, Young-Jae; Choi, Kwang-Sik; Park, Hyun Je; Yun, Sung-Gyu; Kang, Chang-Keun

    2016-01-01

    The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG) were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C) and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L(-1)). Physiological rates were standardized by using the mean (480 mg) of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100-200 mg L(-1) at 18-23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L(-1)), with the highest level being recorded at 18°C and 100-200 mg L(-1) SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a wide variety

  2. Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum.

    Directory of Open Access Journals (Sweden)

    Hee Yoon Kang

    Full Text Available The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L(-1. Physiological rates were standardized by using the mean (480 mg of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100-200 mg L(-1 at 18-23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L(-1, with the highest level being recorded at 18°C and 100-200 mg L(-1 SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a

  3. Reproductive Biology of the Short-Necked Clam, Paphia undulata (Born 1778 from Southern Negros Occidental, Central Philippines

    Directory of Open Access Journals (Sweden)

    Fenelyn M. Nabuab

    2010-12-01

    Full Text Available The short-necked clam, Paphia undulata, occurs in coastal muddy bottoms of Hinigaran, Binalbagan, and Himamaylan, Negros Occidental where it has an important contribution to fisheries. However, stocks in these areas are dwindling and in order to formulate sound management strategies, information on the reproductive biology of this species is a prerequisite. Also, knowledge on the reproduction of this species is a prelude to its laboratory breeding and rearing. Reproductive biology of the short-necked clam from the three areas was studied over an annual cycle. Short-necked clams were collected monthly from catches of compressor divers. Five gonad stages were described based on histological examinations: developing, mature, partially spawned, redeveloping, and spent. Immature or indeterminate gonads were also noted. Although occasional presence of hermaphrodite gonads was observed this species is still functionally dioecious with 1.00M: 1.02F sex ratio. Sexual maturity is attained at 42.6 mm for males and 44.8 mm for females. Short-necked clams have continuous breeding season. However, peak of spawning activities is on the months of August to November which coincide with the monsoon transition months probably due to the decrease in salinity and nutrient influx during these months. Organisms smaller than 45mm must not be collected and collection must be regulated during peaks of spawning activities to leave a portion of reproductively mature individuals to ensure sustainability of fisheries. However, in terms of laboratory breeding and rearing of this species, it is fundamental to consider the spawning peaks and size at sexual maturity to ensure successful spawning in the laboratory. Hence, broodstock to be used in the experiments must be sexually mature (>45mm and collected during peaks of spawning activities.

  4. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhan, Q., E-mail: qzhan@mater.ustb.edu.cn [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Fu, Z.Y.; Wei, Y.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Y.M. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wang, F.M. [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Ohnuki, S. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wan, F.R. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-11-15

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He{sup +} ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed.

  5. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    International Nuclear Information System (INIS)

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He+ ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed

  6. Effect of cage design on growth of transplanted Asian clams: implications for assessing bivalve responses in streams.

    Science.gov (United States)

    Hull, Matthew S; Cherry, Donald S; Merricks, Timothy C

    2004-01-01

    This study was designed to determine whether survivorship and growth of Asian clams (Corbicula fluminea [Müller]) differed significantly between two types of field enclosures. Enclosures were either flexible mesh bags or rigid cages (hereto after referred as bioboxes) designed to homogenize substrate among study sites and accommodate Asian clam feeding mechanisms. For 96d, cages remained at 12 Clinch River (CR), Hurricane Fork (HF), and Dump's Creek (DC) sites upstream and downstream of a coal-fired power plant discharge, coal mining effluent, and coal combustion-related disposal facilities in Carbo, Virginia. Although survivorship was not significantly different between cage types, mean growth of clams in bioboxes was significantly greater overall (p = 0.0157). Despite the difference in growth between the two cage types, both confirmed significant reductions of survivorship and growth directly below the power plant discharge. Additionally, coefficient of variance values for biobox growth data were reduced at most study sites (averages of 16% for bioboxes versus 19% for mesh bags). Our results have implications toward strengthening weight-of-evidence approaches used to link impairment of transplanted bivalves to environmental contaminants. More importantly, these results suggest that ecotoxicological impairment of bivalves transplanted downstream of the coal-fired power plant discharge functioned independently of site-specific substrate provisions. PMID:15327146

  7. Toxicological effects induced by cadmium in gills of Manila clam ruditapes philippinarum using NMR-based metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Linbao; Liu, Xiaoli; You, Liping; Zhou, Di [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); The Graduate School of Chinese Academy of Sciences, Beijing (China); Yu, Junbao; Zhao, Jianmin; Wu, Huifeng [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); Feng, Jianghua [Department of Electronic Science, Fujian Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen (China)

    2011-11-15

    Cadmium (Cd) has become an important heavy metal contaminant in the sediment and seawater along the Bohai Sea and been of great ecological risk due to its toxic effects to marine organisms. In this work, the toxicological effects caused by environmentally relevant concentrations (10 and 40 {mu}g L{sup -1}) of Cd were studied in the gill tissues of Manila clam Ruditapes philippinarum after exposure for 24, 48, and 96 h. Both low (10 {mu}g L{sup -1}) and high (40 {mu}g L{sup -1}) doses of Cd caused the disturbances in energy metabolism and osmotic regulation and neurotoxicity based on the metabolic biomarkers such as succinate, alanine, branched chain amino acids, betaine, hypotaurine, and glutamate in clam gills after 24 h of exposure. However, the recovery of toxicological effects of Cd after exposure for 96 h was obviously observed in clam to Cd exposures. Overall, these results indicated that NMR-based metabolomics was applicable to elucidate the toxicological effects of heavy metal contaminants in the marine bioindicator. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Sea otter studies in Glacier Bay National Park and Preserve: Aerial surveys, foraging observations, and intertidal clam sampling

    Science.gov (United States)

    Bodkin, J.L.; Kloecker, K.A.; Esslinger, G.G.; Monson, D.H.; DeGroot, J.D.

    2001-01-01

    Following translocations to the outer coast of Southeast Alaska in 1965, sea otters have been expanding their range and increasing in abundance. We began conducting surveys for sea otters in Cross Sound, Icy Strait and Glacier Bay, Alaska in 1994, following initial reports of their presence in Glacier Bay in 1993. Since 1995, the number of sea otters in Glacier Bay proper has increased from about 5 to more than 500. Between 1993 and 1997 sea otters were apparently only occasional visitors to Glacier Bay, but in 1998 long-term residence was established as indicated by the presence of adult females and their dependent pups. Sea otter distribution is limited to the Lower Bay, south of Sandy Cove, and is not continuous within that area. Concentration occur in the vicinity of Sita Reef and Boulder Island and between Pt. Carolus and Rush Pt. on the west side of the Bay (Figure 1). We describe the diet of sea otters in Glacier Bay and south Icy Strait through visual observations of prey during >4,000 successful forage dives. In 2,399 successful foraging dives observed in Glacier Bay proper, diet consisted of 40% clam, 21% urchins, 18% mussel, 4% crab, 5% other and 12% unidentified. Most prey recovered by sea otters are commercially, socially, or ecological important species. Species of clam are primarily Saxidomus gigantea, Protothaca staminea, and Serripes groenlandicus. Urchins are primarily Strongylocentrotus droebachiensis while both mussles, Modiolus modiolus and Mytilus trossulus, are taken. Crabs include species of Cancer, Chinoecetes, Paralithodes, and Telmessus. Although we characterize diet at broad geographic scales, we found diet to vary between sites separated by as little as several hundred meters. Dietary variation among and within sites can reflect differences in prey availability and individual choice. We estimated species composition, density, biomass, and sizes of intertidal clams at 59 sites in Glacier Bay, 14 sites in Idaho Inlet, 12 sites in Port

  9. Assessment of wet weather impact on clam (Chamelea gallina faecal contamination in the district of San Benedetto del Tronto (Italy

    Directory of Open Access Journals (Sweden)

    Piero Capocasa

    2013-02-01

    Full Text Available Since 1998 clams (Chamelea gallina from the production areas of the district of San Benedetto del Tronto (South Marche - Italy have been periodically monitored to check the microbiological quality by the detection of the faecal indicator E. coli (MPN method. Results have been inconstant. They were not directly related to contamination sources identified by means of a Sanitary Survey. This one included a desk-based study of the physical, geographic, demographic and urban features of the district above and a shoreline survey to confirm or update previously identified sources. With regard to this, several authors found out that meteoric events, in particular rainfalls, increase faecal loading in marine coastal water. This study investigated the impact of rainfalls on E. coli values in clams from the district of San Benedetto del Tronto according to the sampling plan from 2002 to 2011. The study focused on rainfalls occurred until 4 days before mollusc sampling and set up E. coli values into satisfactory and unsatisfactory levels compared to the food safety limit of 230 MPN/100 g. Data were processed by a statistical tool, the Fisher’s exact test. Results revealed the association between precipitations and exceeding values of E. coli in clams collected from coastal waters of most populous areas to be statistically significant.

  10. Study of the toxic effects of flame retardant PBDE-47 on the clam Chamelea gallina (Linnaeus, 1758

    Directory of Open Access Journals (Sweden)

    Salvatora Angela Angioni

    2013-03-01

    Full Text Available The purpose of the study is to evaluate the effects of 2,2',4,4'-tetrabromodiphenylether (PBDE-47 on the Chamelea gallina clam (according to current commercial regulations: Venus gallina. PBDEs, which are used as flame retardants in various industrial products, are classed as hazardous substances by Directive 2011/65/EU. They are bioaccumulative compounds, considered to be endocrine disruptors, genotoxic, neurotoxic and practically ubiquitous, and their concentration in the environment has considerably increased in recent years. The aim of this study is to establish the effects of PBDE-47 on Chamelea gallina: toxic power and any harmful effects on the gonads, bioaccumulation capacity in the tissues, and possible entry into the food chain. The research used 96-hour and 21-day experimental tests on clams housed in filtered seawater. The tests were preceded by a period of acclimatisation of the molluscs lasting five to seven days. The clams were fed on seaweed (Dunaliella tertiolecta. The choice of the toxic compound PBDE-47 was based on the high concentration, among the congeners of PBDE, found in some aquatic species. The study demonstrated that the concentration of the contaminant used did not alter the vital functions, cause significant levels of mortality or lead to evident alteration in the gonads of Chamelea gallina. However, the research demonstrated the bioaccumulation capacity of the bivalve mollusc, allowing PBDE-47 to enter the food chain.

  11. A preliminary assessment of oxygen isotope fractionation and growth increment periodicity in the estuarine clam Rangia cuneata

    Science.gov (United States)

    Andrus, C. Fred T.; Rich, Kelley Whatley

    2008-10-01

    Rangia cuneata is an upper estuarine clam common in the coastal regions of the Gulf of Mexico. Limited data exist regarding oxygen isotope fractionation and microstructural increment periodicity in this species. As these clams were recently identified as an invasive species in other regions, such data may be useful for environmental management purposes. Additionally, the shell of this clam is common in archeological middens, and thus may serve as a paleoenvironmental proxy. In order to assess these aspects of the species' natural history, samples were collected from the upper Mobile Bay, Alabama, USA. A stable oxygen isotope profile was generated from one of these valves, and compared to growth increments seen in thin section. Time-series water temperature data from near the collection site were used to construct idealized models of oxygen isotope variation, assuming equilibrium fractionation, constant shell growth, and stable water δ18O values. Comparison of the modeled and measured data suggest the shell was precipitated in, or near oxygen isotope equilibrium with ambient water, and that the microstructural increments in the shell were precipitated in response to tidal cycles.

  12. A coupled lake-atmosphere model (CLAM) and its application to Lake Kinneret

    Science.gov (United States)

    Pan, Hai

    1999-08-01

    Kinneret is a 166-km2 lake located in Northern Israel, in the central part of the Jordan Valley, a corridor running from north to south, between the Galilee hills in the west and the Golan Heights in the east. Both the Galilee hills and the Golan Heights reach an elevation of about 400 m above mean sea level (MSL), and the lake is about -210 m (MSL). North of the lake is the mountainous area of the Hermon, culminating at about 2800 m (MSL). About 120 km south of it is the Dead Sea, which is about -410 m (MSL), and about 45 km west of it is the Mediterranean Sea. The complexity of the terrain, combined with relatively arid soil and various ground covers surrounding the lake, results in a very complicated system of atmospheric and lake processes. To understand this system, especially the processes affecting the atmosphere and lake dynamics and thermodynamics, and their effects on Lake Kinneret evaporation, a coupled lake-atmosphere model (CLAM) was developed and applied to the lake region. The CLAM is based on the Regional Atmospheric Modeling System (RAMS) and the oceanic S-coordinate Rutgers University Model (SCRUM). Energy, mass, and momentum are conserved at the interface between the atmosphere and the lake, and appropriate balance equations are applied there. In the atmospheric module, two nested grids are employed to simulate Northern Israel at a resolution of 4 x 4 km2, and the near-lake region at a resolution of 1 x 1 km 2. Synoptic conditions obtained from the National Meteorological Center (NMC) reanalysis are assimilated by the model. Soil moisture, which appears to have a significant impact on atmospheric circulation in this region, was transformed from the normalized difference vegetation index (NDVI). Observations collected during two summers above and inside the lake emphasize the good capability of CLAM to simulate surface fluxes and other microclimatic conditions, as well as lake temperature and currents. Although the lake is small (about 12-km wide

  13. Accumulation and depuration profiles of PSP toxins in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Alexandrium catenella.

    Science.gov (United States)

    Samsur, Mohamad; Yamaguchi, Yasunaga; Sagara, Takefumi; Takatani, Tomohiro; Arakawa, Osamu; Noguchi, Tamao

    2006-09-01

    A toxic dinoflagellate responsible for paralytic shellfish poisoning (PSP), Alexandrium catenella (Ac) was fed to the short-necked clam Tapes japonica, and the accumulation and depuration profiles of PSP toxins were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested more than 99% of the Ac cells (4 x 10(7)cells) supplied once at the beginning of experiment, and accumulated a maximal amount of toxin (185 nmol/10 clams) after 12h. The rate of toxin accumulation at that time was 23%, which rapidly decreased thereafter. Composition of the PSP toxin accumulated in the clams obviously different from that of Ac even 0.5h after the cell supply, the proportion of C1+2 being much higher than in Ac, although the reason remains to be elucidated. In contrast, a higher ratio of gonyautoxin (GTX)1+4 than in Ac was detected in the toxin profiles of clam excrements. The variation in toxin composition derived presumably from the transformation of toxin analogues in clams was observed from 0.5h, such as reversal of the ratio of C1 to C2, and appearance of carbamate (saxitoxin (STX), neoSTX and GTX2, 3) and decarbamoyl (dc) derivatives (dcSTX and dcGTX2, 3), which were undetectable in Ac cells. The total amount of toxin distributed over Ac cells, clams and their excrements gradually declined, and only 1% of supplied toxin was detected at the end of experiment. PMID:16887162

  14. Chemical Characterization of the Aerosol During the CLAMS Experiment Using Aircraft and Ground Stations

    Science.gov (United States)

    Castanho, A. D.; Martins, J.; Artaxo, P.; Hobbs, P. V.; Remer, L.; Yamasoe, M.; Fattori, A.

    2002-05-01

    During the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment Nuclepore filters were collected in two ground stations and aboard the University of Wasghington's Convair 580 Reserarch Aircraft. The two ground stations were chosen in strategic positions to characterize the chemical composition, the mass concentration, black carbon (BC) content, and the absorption properties of the aerosol particles at the surface level. One of the stations was located at the Cheasapeake lighthouse (25 km from the coast) and the other one was located at the Wallops Island. Aerosol particles where collected in two stages, fine (d2.5um) and coarse mode (2.5CLAMS Experiment area. Some of the filters were also submitted to Scanning Electron Microscopy analysis. The particulate matter mass for all the samples were obtained gravimetrically. The concentration of black carbon in the fine filters was optically determined by a broadband reflectance technique. The spectral (from UV to near IR) reflectance in the fine and coarse mode filter were also obtained with a FieldSpec ASD spectrometer. Aerosol elemental characterization (Na through Pb) was obtained by the PIXE (Particle induced X ray emission) analyses of the nuclepore filters. The sources of the aerosol measured at the ground stations were estimated by principal component analyses mainly in the Wallops Island, where a longer time series was collected. One of the main urban components identified in the aerosol during the experiment was sulfate. Black carbon

  15. On some Indo-Pacific boring endolithic Bivalvia species introduced into the Mediterranean Sea with their host – spread of Sphenia rueppelli A. Adams, 1850

    Directory of Open Access Journals (Sweden)

    A. ZENETOS

    2012-12-01

    Full Text Available The study of the endolithic molluscs found on/in living alien Spondylusshells collected in the Gulf of Iskenderun (Turkey brought to light three more alien bivalvia species namely Petricola hemprichi, Gastrochaena cymbium and Sphenia rueppelli. The presence of Sphenia rueppellideserves attention as it constitutes the first record of this species as living in the Mediterranean Sea. The definitive establishment and spreading of these bivalves in the basin seems to be also attested by careful analysis of specimens sampled in other southern Turkish localities and previously retained in local private collections. The present records raise some questions on the vector of arrival of the species in the Mediterranean Sea that could be strictly connected with their hosts.

  16. Overfishing population characteristics of razor clam, Ensis macha, from Independencia Bay, Peru, in 2004 year

    Directory of Open Access Journals (Sweden)

    Juan Tarazona

    2011-05-01

    Full Text Available Quantitative monthly samplings, in 2004, were carried out to estimate the density and biomass of Ensis macha (Molina 1782, from Morro Quemado area, Bay Independence, Pisco. The present study analyzes biometric relationships, growth parameters and somatic production using the ELEFAN I routine and the Crisp’s method. During the year 2004 the rate of exploitation (E= 0.69 y-1 was significantly bigger than the values of 2003 and the monthly landings (maximum of 335 t and fishing effort (maximum of 848 trips were twice increased. These changes induced in the same year a significant decrease of population mean density (D= 54.13 ind. m-2 and the halfway reduction of somatic production (P= 81.99 gAFDW m-2 y-1 and P/B rate (0.38 y-1 values, regarding the values of the previous year. Also, a significant increment of total mortality rate (2.84 y-1 and the fishing mortality rate (1.97 y-1 were twice increased, regarding the previous year. It is assumed that the population of razor clams already was a overfishing commercial resource in the 2003 and that the increment of fishing pressure in the 2004, particularly during the second semester, intensified its overfishing resource condition.

  17. Complement C3 gene: Expression characterization and innate immune response in razor clam Sinonovacula constricta.

    Science.gov (United States)

    Peng, Maoxiao; Niu, Donghong; Wang, Fei; Chen, Zhiyi; Li, Jiale

    2016-08-01

    Complement component 3 (C3) is central to the complement system, playing an important role in immune defense, immune regulation and immune pathology. Several C3 genes have been characterized in invertebrates but very few in shellfish. The C3 gene was identified from the razor clam Sinonovacula constricta, referred to here as Sc-C3. It was found to be highly homologous with the C3 gene of Ruditapes decussatus. All eight model motifs of the C3 gene were found to be included in the thiolester bond and the C345C region. Sc-C3 was widely expressed in all healthy tissues with expression being highest in hemolymph. A significant difference in expression was revealed at the umbo larvae development stage. The expression of Sc-C3 was highly regulated in the hemolymph and liver, with a distinct response pattern being noted after a challenge with Micrococcus lysodeikticus and Vibrio parahemolyticus. It is therefore suggested that a complicated and unique response pathway may be present in S. constricta. Further, serum of S. constricta containing Sc-C3 was extracted. This was activated by LPS or bacterium for verification for function. The more obvious immune function of Sc-C3 was described as an effective membrane rupture in hemocyte cells of rabbit, V. parahemolyticus and Vibrio anguillarum. Thus, Sc-C3 plays an essential role in the immune defense of S. constricta. PMID:27231190

  18. Seasonal dynamics of biomarkers in infaunal clam Macoma balthica from the Gulf of Riga (Baltic Sea)

    Science.gov (United States)

    Barda, Ieva; Purina, Ingrida; Rimsa, Elina; Balode, Maija

    2014-01-01

    Biomarkers are often regarded as “early warning” signals of environmental pollution; however seasonal changes are mentioned as one of the most important factor that influences the activity of biomarkers. The aim of our study was to assess the importance of seasonal variation of selected contaminant biomarkers in Macoma balthica to provide background information for further environmental surveys in the Gulf of Riga. Seasonal variation of biomarkers (acetylcholinesterase (AChE), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST)) was measured in infaunal clam M. balthica from the southern part of the Gulf of Riga. The majority of biomarkers (GST, CAT and GR) showed strong seasonal variability; however only CAT and GR were found to be significantly related to environmental factors (near-bottom oxygen, salinity and temperature). Integrated biomarker response (IBR) index indicated that the most stressed condition of M. balthica is during August and May. The highest values of IBR were found near the mouth of the River Daugava, suggesting the impact of environmental pollution on the benthic animals.

  19. Shell matrix proteins of the clam, Mya truncata: Roles beyond shell formation through proteomic study.

    Science.gov (United States)

    Arivalagan, Jaison; Marie, Benjamin; Sleight, Victoria A; Clark, Melody S; Berland, Sophie; Marie, Arul

    2016-06-01

    Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective.

  20. Rhodopirellula rosea sp. nov., a novel bacterium isolated from an ark clam Scapharca broughtonii.

    Science.gov (United States)

    Roh, Seong Woon; Lee, Hae-Won; Yim, Kyung June; Shin, Na-Ri; Lee, Jina; Whon, Tae Woong; Lim, Na-Lae; Kim, Daekyung; Bae, Jin-Woo

    2013-06-01

    A novel Gram-negative, motile, and ovoid-shaped strain, LHWP3(T), which belonged to the family Planctomycetaceae in the phylum Planctomycetes, was isolated from a dead ark clam Scapharca broughtonii collected during a mass mortality event on the south coast of Korea. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the isolate was most closely related to the type strain of Rhodopirellula baltica, with a shared 16S rRNA gene sequence similarity of 94.8%. The isolate grew optimally at 30°C in 4-6% (w/v) NaCl, and at pH 7. The major isoprenoid quinone was menaquinone-6 (MK-6). The dominant polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, and unidentified polar lipids. The predominant cellular fatty acids were C16:0, C18:1 ω9c, and C18:0. The genomic DNA G+C content of strain LHWP3(T) was 53.0 mol%. Based on polyphasic taxonomic analyses, strain LHWP3(T) should be classified as a novel species in the genus Rhodopirellula in the family Planctomycetaceae, for which the name Rhodopirellula rosea sp. nov. is proposed. The type strain is LHWP3(T) (=KACC 15560(T) =JCM 17759(T)). PMID:23812809

  1. Shell matrix proteins of the clam, Mya truncata: Roles beyond shell formation through proteomic study.

    Science.gov (United States)

    Arivalagan, Jaison; Marie, Benjamin; Sleight, Victoria A; Clark, Melody S; Berland, Sophie; Marie, Arul

    2016-06-01

    Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective. PMID:27068305

  2. Physical proximity may promote lateral acquisition of bacterial symbionts in vesicomyid clams.

    Directory of Open Access Journals (Sweden)

    Carole Decker

    Full Text Available Vesicomyid clams harbor intracellular sulfur-oxidizing bacteria that are predominantly maternally inherited and co-speciate with their hosts. Genome recombination and the occurrence of non-parental strains were recently demonstrated in symbionts. However, mechanisms favoring such events remain to be identified. In this study, we investigated symbionts in two phylogenetically distant vesicomyid species, Christineconcha regab and Laubiericoncha chuni, which sometimes co-occur at a cold-seep site in the Gulf of Guinea. We showed that each of the two species harbored a single dominant bacterial symbiont strain. However, for both vesicomyid species, the symbiont from the other species was occasionally detected in the gills using fluorescence in situ hybridization and gene sequences analyses based on six symbiont marker genes. Symbiont strains co-occurred within a single host only at sites where both host species were found; whereas one single symbiont strain was detected in C. regab specimens from a site where no L. chuni individuals had been observed. These results suggest that physical proximity favored the acquisition of non-parental symbiont strains in Vesicomyidae. Over evolutionary time, this could potentially lead to genetic exchanges among symbiont species and eventually symbiont displacement. Symbiont densities estimated using 3D fluorescence in situ hybridization varied among host species and sites, suggesting flexibility in the association despite the fact that a similar type of metabolism is expected in all symbionts.

  3. Study of the microstructure and mechanical properties of white clam shell.

    Science.gov (United States)

    Liang, Yunhong; Zhao, Qian; Li, Xiujuan; Zhang, Zhihui; Ren, Luquan

    2016-08-01

    The microstructure and mechanical properties of white clam shell were investigated, respectively. It can be divided into horny layer, prismatic layer and nacreous layer. Crossed-lamellar structure was the microstructural characteristic. The extension direction of lamellae in prismatic layer was different from that in nacreous layer, which formed an angle on the interface between prismatic layer and nacreous layer. The phase component of three layers was CaCO3 with crystallization morphology of aragonite, which confirmed the crossed-lamellar structural characteristic. White calm shell exhibited perfect mechanical properties. The microhardness values of three layers were 273HV, 240HV and 300HV, respectively. The average values of flexure and compression strength were 110.2MPa and 80.1MPa, respectively. The macroscopical cracks crossed the lamellae and finally terminated within the length range of about 80μm. It was the microstructure characteristics, the angle on the interface between prismatic and nacreous layer and the hardness diversity among the different layers that enhanced mechanical properties of white calm shell.

  4. Capillary crystallization and molecular-replacement solution of haemoglobin II from the clam Lucina pectinata

    International Nuclear Information System (INIS)

    The haemoglobin II from the clam L. pectinata has been crystallized using counter-diffusion in single capillary in the presence of agarose to improve crystal quality. Initial phases have been obtained by molecular replacement. Haemoglobin II is one of three haemoglobins present in the cytoplasm of the Lucina pectinata mollusc that inhabits the Caribbean coast. Using HBII purified from its natural source, crystallization screening was performed using the counter-diffusion method with capillaries of 0.2 mm inner diameter. Crystals of HbII suitable for data collection and structure determination were grown in the presence of agarose at 0.1%(w/v) in order to improve their quality. The crystals belong to the tetragonal space group P42212, with unit-cell parameters a = b = 73.92, c = 152.35 Å, and diffracted X-rays to a resolution of better than 2.0 Å. The asymmetric unit is a homodimer with a corresponding Matthews coefficient (VM) of 3.15 Å3 Da−1 and a solvent content of 61% by volume

  5. Food sources of the Manila clam Ruditapes philippinarum in intertidal areas: evidence from stable isotope analysis

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liqiang; YAN Xiwu; YANG Feng

    2013-01-01

    Based on stable isotope analysis,we characterized the dietary regime of the Manila clam Ruditapesphilippinarum inhabiting intertidal areas along the Liaodong Peninsula,Northern China.Samples,including particulate organic matter (POM; n=30),benthic microalgae (BMI; n=30) and R.philippinarum (n=60),were collected from six sampling sites displaying the same ecological conditions.Of the two primary food sources,POM was more depleted in δ13C (-20.61‰ to-22.89‰) than BMI was (-13.90‰ to-16.66‰).With respect to 15N,BMI was more enriched (2.90‰ to 4.07‰) than POM was (4.13‰ to 5.12‰).The δ13C values of R.philippinarum ranged from-18.78‰ to-19.35‰ and the δ15N values from 7.96‰ to 8.63‰,which were intermediate between the POM and BMI values.In a two-source isotope mixing model,we estimated the relative contributions of POM and BMI to the diet of R.philippinarum to be 74.2% and 25.8%,respectively.We conclude that R.philippinarum feeds mainly on POM,and BMI is also an important supplemental food source in intertidal areas.

  6. Rhodopirellula rosea sp. nov., a novel bacterium isolated from an ark clam Scapharca broughtonii.

    Science.gov (United States)

    Roh, Seong Woon; Lee, Hae-Won; Yim, Kyung June; Shin, Na-Ri; Lee, Jina; Whon, Tae Woong; Lim, Na-Lae; Kim, Daekyung; Bae, Jin-Woo

    2013-06-01

    A novel Gram-negative, motile, and ovoid-shaped strain, LHWP3(T), which belonged to the family Planctomycetaceae in the phylum Planctomycetes, was isolated from a dead ark clam Scapharca broughtonii collected during a mass mortality event on the south coast of Korea. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the isolate was most closely related to the type strain of Rhodopirellula baltica, with a shared 16S rRNA gene sequence similarity of 94.8%. The isolate grew optimally at 30°C in 4-6% (w/v) NaCl, and at pH 7. The major isoprenoid quinone was menaquinone-6 (MK-6). The dominant polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, and unidentified polar lipids. The predominant cellular fatty acids were C16:0, C18:1 ω9c, and C18:0. The genomic DNA G+C content of strain LHWP3(T) was 53.0 mol%. Based on polyphasic taxonomic analyses, strain LHWP3(T) should be classified as a novel species in the genus Rhodopirellula in the family Planctomycetaceae, for which the name Rhodopirellula rosea sp. nov. is proposed. The type strain is LHWP3(T) (=KACC 15560(T) =JCM 17759(T)).

  7. Toxicity and the fractional distribution of trace metals accumulated from contaminated sediments by the clam Scrobicularia plana exposed in the laboratory and the field

    Energy Technology Data Exchange (ETDEWEB)

    Kalman, J., E-mail: judit.kalman@uca.es [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bonnail-Miguel, E. [Department of Physical-Chemistry, University of Cadiz, Poligono Industrial Rio San Pedro s/n, 11,510 Puerto Real, Cadiz (Spain); Smith, B.D. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bury, N.R. [Division of Diabetes and Nutritional Science, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Rainbow, P.S. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2015-02-15

    The relationship between the subcellular distribution of accumulated toxic metals into five operational fractions (subsequently combined into presumed detoxified and non-detoxified components) and toxicity in the clam Scrobicularia plana was investigated under different laboratory exposures. Clams were exposed to metal contaminated media (water and diet) and analysed for the partitioning of accumulated As, Cu and Zn into subcellular fractions. In general, metallothionein-like proteins, metal-rich granules and cellular debris in different proportions acted as main storage sites of accumulated metals in the clam soft tissues for these three metals. No significant differences were noted in the accumulation rates of As, Cu and Zn of groups of individuals with or without apparent signs of toxicity after up to 30 days of exposure to naturally contaminated sediment mixtures. There was, however, an increased proportional accumulation of Cu in the non-detoxified fraction with increased Cu accumulation rate in the clams, suggesting that the Cu uptake rate from contaminated sediments exceeded the combined rates of elimination and detoxification of Cu, with the subsequent likelihood for toxic effects in the clams. - Highlights: • Scrobicularia plana accumulated As, Cu and Zn from naturally toxic sediments. • Toxic metals were accumulated in detoxified and non-detoxified components. • Cu accumulation in the non-detoxified pool increased with increased Cu uptake rate. • Cu uptake rate exceeded combined loss and detoxification rates to cause toxicity.

  8. Nutrients and clam contamination by Escherichia coli in a meso-tidal coastal lagoon: Seasonal variation in counter cycle to external sources

    International Nuclear Information System (INIS)

    Highlights: • Sources of nutrients and E. coli in Ria Formosa linked to tourism in summer. • Lower nutrient values and clam contamination by E. coli in summer. • Bactericide effect of temperature and solar radiation causes lower E. coli. • Higher biological consumption of nutrients in warmer periods. • Results mirror possible effects of climate changes on coastal lagoons. - Abstract: The clam Ruditapes decussatus was transplanted from a natural recruitment area of Ria Formosa to three sites, surveyed for nutrients in water and sediments. Specimens were sampled monthly for determination of Escherichia coli, condition index and gonadal index. Higher nutrient values in low tide reflect drainage, anthropogenic sources or sediment regeneration, emphasising the importance of water mixing in the entire lagoon driven by the tide. Despite the increase of effluent discharges in summer due to tourism, nutrient concentrations and E. coli in clams were lower in warmer periods. The bactericide effect of temperature and solar radiation was better defined in clams from the inlet channel site than from sites closer to urban effluents. High temperature in summer and torrential freshwater inputs to Ria Formosa may anticipate climate change scenarios for south Europe. Seasonal variation of nutrients and clam contamination may thus point to possible alterations in coastal lagoons and their ecosystem services

  9. Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum.

    Science.gov (United States)

    Samsur, Mohamad; Takatani, Tomohiro; Yamaguchi, Yasunaga; Sagara, Takefumi; Noguchi, Tamao; Arakawa, Osamu

    2007-02-01

    The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment. PMID:17370612

  10. New Mediterranean Biodiversity Records (June 2012

    Directory of Open Access Journals (Sweden)

    A. NICOLAIDOU

    2012-12-01

    Full Text Available The present work reports on the extended distribution of nineteen species in the Mediterranean. These are: Upeneus pori(Fish:Turkey, Bursatella leachii (Mollusca, Opisthobranchia: eastern coast of Spain, Sparisoma cretense (Fish: Ionian coastof Greece, Pseudobryopsis myura (Chlorophyta: Turkey, Aplysia dactylomela (Mollusca, Opisthobranchia: Karpathos island,and Kyklades Archipelago, Greece, Asparagopsis armata and Botryocladia madagascariensis (Rhodophyta: South Peloponnesos,Greece, Oxynotus centrina (Fish: Greece, Caulerpa racemosa var. cylindracea (Chlorophyta , Stypopodium schimperi(Phaeophyta Siganus luridus and Stephanolepis diaspros (Fish Percnon gibbesi (Decapoda, Brachyura (Kyklades Archipelago,Greece, Cerithium scabridum (Mollusca, Prosobranchia: Anavissos: Greece and Cerithium renovatum (Mollusca, Prosobranchia:N. Κriti, Cassiopea andromeda (Scyphomedusa: Rhodos Island, Greece, Abra tenuis (Mollusca Bivalvia: VouliagmeniLake, Greece Lagocephalus lagocephalus (Fish: Calabrian coast, Italy and Plocamopherus ocellatus (Mollusca, Opisthobranchia:İskenderun Bay, Turkey.

  11. Phylogenetic relationships among Opisthobranchia (Mollusca: Gastropoda) based on mitochondrial cox 1, trnV, and rrnL genes.

    Science.gov (United States)

    Grande, Cristina; Templado, Josè; Cervera, J Lucas; Zardoya, Rafael

    2004-11-01

    We reconstructed the phylogenetic relationships among 37 species representing seven main lineages within Opisthobranchia (Mollusca: Gastropoda) based on a mitochondrial fragment that included partial cox 1, complete trnV, and partial rrnL genes (about 2500 bp). Phylogenetic analyses confirmed tentatively that all studied main opisthobranch lineages conformed monophyletic groups except Nudibranchia. The sacoglossan Ascobulla was placed as the most basal lineage of opisthobranchs. The basommatophoran pulmonate Siphonaria was recovered within Opisthobranchia between Ascobulla and the remaining opisthobranchs. The latter were divided into two different lineages that await formal description: on one side, Cephalaspidea, Tylodinoidea, and Anaspidea (sharing features in the reproductive, digestive, and circulatory systems) were grouped together and, on the other Architectibranchia and Nudipleura (sharing similarities in the circulatory system) were recovered as sister group taxa. Two well-supported clades were recovered within Nudipleura: Pleuroanthobranchia (new taxon) and Cladobranchia. Pleuroanthobranchia (Pleurobranchoidea plus Anthobranchia) was defined by the presence of blood gland, the presence of calcareous spicules in the integument and the presence of a caecum with an opening directly into the stomach. The new molecular phylogeny provided a robust framework for comparative studies, and prompted a revision of the morphological synapomorphies diagnosing the main clades within opisthobranchs. PMID:15336672

  12. Seasonal Changes in Glycogen Contents in Various Tissues of the Edible Bivalves, Pen Shell Atrina lischkeana, Ark Shell Scapharca kagoshimensis, and Manila Clam Ruditapes philippinarum in West Japan

    Directory of Open Access Journals (Sweden)

    Tatsuya Yurimoto

    2015-01-01

    Full Text Available The types of tissues accumulating glycogen and seasonal changes in glycogen content were investigated in the following shell species: pen shell Atrina lischkeana, ark shell Scapharca kagoshimensis, and Manila clam Ruditapes philippinarum. Comparison of the results showed that the adductor muscle or foot was the main glycogen reservoir and the levels varied seasonally. The adductor muscle in the pen shell showed higher glycogen content during spring and lower content during autumn. The ark shell, on the other hand, showed higher content during winter and spring and lower content during summer and autumn, while the Manila clam showed higher glycogen content during spring and summer and lower content during autumn and winter. These results revealed that the adductor muscle in pen shells and the foot in ark shells and Manila clams act as the main storage tissues for glycogen in the three species studied and that these tissues are suitable to analyze glycogen prevalence to estimate individual physiological condition.

  13. Can ecological history influence response to pollutants? Transcriptomic analysis of Manila clam collected in different Venice lagoon areas and exposed to heavy metal.

    Science.gov (United States)

    Milan, Massimo; Matozzo, Valerio; Pauletto, Marianna; Di Camillo, Barbara; Giacomazzo, Matteo; Boffo, Luciano; Binato, Giovanni; Marin, Maria Gabriella; Patarnello, Tomaso; Bargelloni, Luca

    2016-05-01

    Chronic exposure to environmental pollutants can exert strong selective pressures on natural populations, favoring the transmission over generations of traits that enable individuals to survive and thrive in highly impacted environments. The lagoon of Venice is an ecosystem subject to heavy anthropogenic impact, mainly due to the industrial activities of Porto Marghera (PM), which led to a severe chemical contamination of soil, groundwater, and sediments. Gene expression analysis on wild Manila clams collected in different Venice lagoon areas enabled to identify differences in gene expression profiles between clams collected in PM and those sampled in clean areas, and the definition of molecular signatures of chemical stress. However, it remains largely unexplored to which extent modifications of gene expression patterns persists after removing the source of contamination. It is also relatively unknown whether chronic exposure to xenobiotics affects the response to other chemical pollutants. To start exploring such issues, in the present study a common-garden experiment was coupled with transcriptomic analysis, to compare gene expression profiles of PM clams with those of clams collected in the less impacted area of Chioggia (CH) during a period under the same control conditions. Part of the two experimental groups were also exposed to copper for seven days to assess whether different "ecological history" does influence response to such pollutant. The results obtained suggest that the chronic exposure to chemical pollution generated a response at the transcriptional level that persists after removal for the contaminated site. These transcriptional changes are centered on key biological processes, such as defense against either oxidative stress or tissue/protein damage, and detoxification, suggesting an adaptive strategy for surviving in the deeply impacted environment of Porto Marghera. On the other hand, CH clams appeared to respond more effectively to copper

  14. Can ecological history influence response to pollutants? Transcriptomic analysis of Manila clam collected in different Venice lagoon areas and exposed to heavy metal.

    Science.gov (United States)

    Milan, Massimo; Matozzo, Valerio; Pauletto, Marianna; Di Camillo, Barbara; Giacomazzo, Matteo; Boffo, Luciano; Binato, Giovanni; Marin, Maria Gabriella; Patarnello, Tomaso; Bargelloni, Luca

    2016-05-01

    Chronic exposure to environmental pollutants can exert strong selective pressures on natural populations, favoring the transmission over generations of traits that enable individuals to survive and thrive in highly impacted environments. The lagoon of Venice is an ecosystem subject to heavy anthropogenic impact, mainly due to the industrial activities of Porto Marghera (PM), which led to a severe chemical contamination of soil, groundwater, and sediments. Gene expression analysis on wild Manila clams collected in different Venice lagoon areas enabled to identify differences in gene expression profiles between clams collected in PM and those sampled in clean areas, and the definition of molecular signatures of chemical stress. However, it remains largely unexplored to which extent modifications of gene expression patterns persists after removing the source of contamination. It is also relatively unknown whether chronic exposure to xenobiotics affects the response to other chemical pollutants. To start exploring such issues, in the present study a common-garden experiment was coupled with transcriptomic analysis, to compare gene expression profiles of PM clams with those of clams collected in the less impacted area of Chioggia (CH) during a period under the same control conditions. Part of the two experimental groups were also exposed to copper for seven days to assess whether different "ecological history" does influence response to such pollutant. The results obtained suggest that the chronic exposure to chemical pollution generated a response at the transcriptional level that persists after removal for the contaminated site. These transcriptional changes are centered on key biological processes, such as defense against either oxidative stress or tissue/protein damage, and detoxification, suggesting an adaptive strategy for surviving in the deeply impacted environment of Porto Marghera. On the other hand, CH clams appeared to respond more effectively to copper

  15. The impact of selection on population genetic structure in the clam Meretrix petechialis revealed by microsatellite markers.

    Science.gov (United States)

    Lu, Xia; Wang, Hongxia; Li, Yan; Liu, Baozhong

    2016-02-01

    The aim of our work is to evaluate the impact of mass selection on genetic structure in artificially closed populations of the clam Meretrix petechialis. In the present study, we performed mass selection over four generations (from 2004 to 2010) on two clam populations [shell features of purple lines (SP) and black dots (SB)] and analyzed their temporal genetic variation and structure using microsatellite makers. The two closed populations originated from the natural Shandong population (SD); thus, a natural SD population (10SD) was used to detect the current genetic structure after 6 years of natural selection. The results showed that the genetic diversity of the four generations of SB and SP was gradually reduced but remained at relatively high levels (SB, A = 18.9.4-16.8, Ho = 0.7389-0.6971, and He = 0.8897-0.8591; SP, A = 20.0-17.8, Ho = 0.7512-0.7043, and He = 0.8938-0.8625), which has not been reduced compared with that of the 10SD population (A = 17.8, Ho = 0.6803, and He = 0.8302). The Ne estimates for the two populations were almost at the same levels as the actual numbers of parental individuals. In addition, a low inbreeding coefficient was detected in the two populations (SB, 0.00201-0.00639; SP, 0.00176-0.00541). Based on the results, the present mass selection has not made a large impact on the population genetic structure of the closed populations. The present investigation provides important information for the development of management strategies for genetic breeding of the clam.

  16. Following the infection process of vibriosis in Manila clam (Ruditapes philippinarum) larvae through GFP-tagged pathogenic Vibrio species.

    Science.gov (United States)

    Dubert, Javier; Nelson, David R; Spinard, Edward J; Kessner, Linda; Gomez-Chiarri, Marta; da Costa, Fiz; Prado, Susana; Barja, Juan L

    2016-01-01

    Vibriosis represents the main bottleneck for the larval production process in shellfish aquaculture. While the signs of this disease in bivalve larvae are well known, the infection process by pathogenic Vibrio spp. during episodes of vibriosis has not been elucidated. To investigate the infection process in bivalves, the pathogens of larvae as V. tubiashii subsp. europaensis, V. neptunius and V. bivalvicida were tagged with green fluorescent protein (GFP). Larvae of Manila clam (Ruditapes philippinarum) were inoculated with the GFP-labeled pathogens in different infection assays and monitored by microscopy. Manila clam larvae infected by distinct GFP-tagged Vibrio spp. in different challenges showed the same progression in the infection process, defining three infection stages. GFP-tagged Vibrio spp. were filtered by the larvae through the vellum and entered in the digestive system through the esophagus and stomach and colonized the digestive gland and particularly the intestine, where they proliferated during the first 2h of contact (Stage I), suggesting a chemotactic response. Then, GFP-tagged Vibrio spp. expanded rapidly to the surrounding organs in the body cavity from the dorsal to ventral region (Stage II; 6-8h), colonizing the larvae completely at the peak of infection (Stage III) (14-24h). Results demonstrated for the first time that the vibriosis is asymptomatic in Manila clam larvae during the early infection stages. Thus, the early colonization and the rapid proliferation of Vibrio pathogens within the body cavity supported the sudden and fatal effect of the vibriosis, since the larvae exhibited the first signs of disease when the infection process is advanced. As a first step in the elucidation of the potential mechanisms of bacterial pathogenesis in bivalve larvae the enzymatic activities of the extracellular products released from the wild type V. neptunius, V. tubiashii subsp. europaensis and V. bivalvicida were determined and their cytotoxicity was

  17. Best management strategies for sustainable giant clam fishery in French Polynesia islands: answers from a spatial modeling approach.

    Directory of Open Access Journals (Sweden)

    Simon Van Wynsberge

    Full Text Available The giant clam Tridacna maxima has been largely overexploited in many tropical regions over the past decades, and was therefore listed in appendix II of the Convention of International Trade in Endangered Species (CITES in 1985. In French Polynesia, several atolls and islands harbor the world's highest stocks of giant clams in very shallow and accessible areas, which are therefore highly vulnerable to fishing pressure. The local fishery authority (i.e., Direction des Resources Marines or "DRM" implemented several management schemes in 2002 to control and regulate fishing pressure. However, for further decisions DRM was missing a sensitivity analysis on the effectiveness of the possible management actions. Here, we report on the use of a deterministic Viable Population Analysis (VPA and spatially-explicit age-based population model that simulated the 30-year trajectory of a Tridacna maxima stock under different management approaches. Specifically, given various scenarios of intra-island larval dispersal, we tested which of No-take-Areas (NTAs, rotational closures, size limits, quotas, and restocking schemes would lead to the highest future stocks in Tubuai and Raivavae, two exploited islands of the Austral archipelago. For both islands, stock abundances were estimated in 2004/2010 and 2005/2010 respectively, and natural mortalities were assessed previously only in Tubuai. When compared to field data, the model successfully predicted the 2010 stocks for Tubuai, but proved to be less reliable for Raivavae, where natural mortality rates may well be different from those on Tubuai. For Tubuai, the spatial model suggested that reducing fishing effort (through fixed quotas and banning fishing below the 12 cm size limit (as currently implemented were the most effective management actions to sustain T. maxima populations into the future. Implementing NTAs was of poor effectiveness. NTAs increased giant clam stock inside the protected area, but also

  18. Coping with seawater acidification and the emerging contaminant diclofenac at the larval stage: A tale from the clam Ruditapes philippinarum.

    Science.gov (United States)

    Munari, Marco; Chemello, Giulia; Finos, Livio; Ingrosso, Gianmarco; Giani, Michele; Marin, Maria G

    2016-10-01

    Seawater acidification could alter the susceptibility of marine organisms to emerging contaminants, such as pharmaceuticals. In this study, the combined effects of seawater acidification and the non-steroidal anti-inflammatory drug diclofenac on survival, growth and oxidative stress-related parameters (catalase activity and lipid peroxidation) in the larvae of the Manila clam Ruditapes philippinarum were investigated for the first time. An experimental flow-through system was set up to carry out a 96-h exposure of clam larvae. Two pH levels (pH 8.0, the control, and pH 7.8, the predicted pH by the end of this century) were tested with and without diclofenac (0.5 μg/L). After 4 days, mortality was dramatically higher under reduced pH, particularly in the presence of diclofenac (62% of the larvae dead). Shell morphology was negatively affected by both acidification and diclofenac from the first day of exposure. The percentage of abnormal larvae was always higher at pH 7.8 than in controls, peaking at 98% in the presence of diclofenac after 96 h. Instead, shell length, shell height or the ratio of these values were only negatively influenced by reduced pH throughout the whole experiment. After 96 h, catalase activity was significantly increased in all larvae kept at pH 7.8, whereas no significant difference in lipid peroxidation was found among the treatments. This study demonstrates a high susceptibility of R. philippinarum larvae to a slight reduction in seawater pH. Furthermore, the results obtained highlight that acidification enhances the sensitivity of clam larvae to environmentally relevant concentrations of diclofenac. PMID:27391052

  19. De novo transcriptome assembly of Perkinsus olseni trophozoite stimulated in vitro with Manila clam (Ruditapes philippinarum) plasma.

    Science.gov (United States)

    Hasanuzzaman, Abul Farah Md; Robledo, Diego; Gómez-Tato, Antonio; Alvarez-Dios, Jose A; Harrison, Peter W; Cao, Asunción; Fernández-Boo, Sergio; Villalba, Antonio; Pardo, Belén G; Martínez, Paulino

    2016-03-01

    The protistan parasite Perkinsus olseni is a deadly causative agent of perkinsosis, a molluscan disease affecting Manila clam (Ruditapes philippinarum), having a significant impact on world mollusc production. Deciphering the underlying molecular mechanisms in R. philippinarum-P. olseni interaction is crucial for controlling this parasitosis. The present study investigated the transcriptional expression in the parasite trophozoite using RNA-seq. Control and treatment (in vitro challenged with Manila clam-plasma) P. olseni trophozoite RNA were extracted and sequenced on the Illumina HiSeq 2000 instrument using a 100-bp paired-end sequencing strategy. Paired reads (64.7 million) were de novo assembled using Trinity, and the resultant transcripts were further clustered using CAP3. The re-constructed P. olseni transcriptome contains 47,590 unique transcripts of which 23,505 were annotated to 9764 unique proteins. A large number of genes were associated with Gene Ontology terms such as stress and immune-response, cell homeostasis, antioxidation, cell communication, signal transduction, signalling and proteolysis. Among annotated transcripts, a preliminary gene expression analysis detected 679 up-regulated and 478 down-regulated genes, linked to virulence factors, anti-oxidants, adhesion and immune-response molecules. Genes of several metabolic pathways such as DOXP/MEP, FAS II or folate biosynthesis, which are potential therapeutic targets, were identified. This study is the first description of the P. olseni transcriptome, and provides a substantial genomic resource for studying the molecular mechanisms of the host-parasite interaction in perkinsosis. In this sense, it is also the first evaluation of the parasite gene expression after challenge with clam extracellular products.

  20. First study of Vibrios in larval cultures of pullet carpet shell clam (Venerupis corrugata in hatchery

    Directory of Open Access Journals (Sweden)

    Javier Dubert Pérez

    2014-07-01

    Full Text Available Protocol for hatchery culture of the pullet carpet shell clam Venerupis corrugata spat is currently under development, as the only reliable means of providing spat to replenish natural beds or to support aquaculture activities. Among other variables, the microbiota has been demonstrated to be critical for successful bivalve culture. Shellfish hatcheries are hindered by fatal outbreaks of disease, regardless the bivalve species. These mass mortalities are mainly caused by opportunistic bacteria belonging to genus Vibrio and constitute one bottleneck for this economic activity. Different species, as V. tubiashii, V. pectenicida, V. splendidus, V. neptunius, V. ostreicida and V. bivalvicida, have been identified as responsible of mortalities in hatchery-reared larvae, affecting a wide range of bivalves. This is the first report of the microbiota associated with larval cultures of the pullet carpet shell clam. We present the results of the microbiological analyses of two larval cultures of pullet carpet shell reared in the Centro de Investigacións Mariñas (CIMA, Xunta de Galicia de Ribadeo (Galicia, NW Spain following the procedures developed in the institution. Each batch, A and B, was obtained from broodstocks collected in natural environment but in different geographical locations, the stock A (SW Galicia and the stock B (NW Galicia. Previous records of mortalities led us to divide each batch in two. One sub-batch (A1 and B1 was cultured following the routine procedures. Antibiotic was experimentally added to the other sub-batch (A2 and B2 with the aim of evaluating the effects on the culturable bacterial population (total marine bacteria and presumptive vibrios and on larval survival. Chloramphenicol, formerly the most commonly used antibiotic in bivalve hatcheries, was supplied with each change of seawater during larval development. Microbiological samples of broodstock, larvae and seawater in culture tanks were taken and processed

  1. Haemocytic leukemia in Prince Edward Island (PEI) soft shell clam (Mya arenaria): Spatial distribution in agriculturally impacted estuaries

    Energy Technology Data Exchange (ETDEWEB)

    Muttray, Annette, E-mail: amuttray@rescan.com [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Reinisch, Carol, E-mail: creinisch@mbl.edu [Visiting Scientist Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Miller, Jason, E-mail: j.miller@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Ernst, William, E-mail: bill.ernst@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 45 Alderney Drive, Dartmouth, NS, Canada B2Y 2N6 (Canada); Gillis, Patricia, E-mail: patty.gillis@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Losier, Melanie, E-mail: melanie.losier@ec.gc.ca [Environment Canada, Atlantic Laboratory for Environmental Testing, Environmental Science Centre, P.O. Box 23005 Moncton, NB, Canada E1A 6S8 (Canada); Sherry, James, E-mail: jim.sherry@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada)

    2012-05-01

    Intensive farming of potatoes in Prince Edward Island (PEI) relies on the repeated and widespread application of fertilizers and pesticides. In PEI the main potato farming areas are in close proximity and drain directly to estuaries. Runoff from high agricultural activity watersheds could impact benthic organism health in the depositional zone of downstream estuaries. The estuarine filter feeder Mya arenaria (soft-shell clam) could be particularly vulnerable to both particle-adsorbed and water soluble contaminants. M. arenaria is susceptible to haemocytic leukemia. In May 2009, we established that heavily proliferated leukemia (HPL) prevalence was generally higher in PEI estuaries located downstream of high intensity potato farming (Dunk and Wilmot estuaries) watersheds than in estuaries downstream of lower intensity areas. Using Mab-1E10 based immunocytochemistry we observed that leukemic haemocytes from the Dunk and Wilmot estuaries were 1E10 negative whereas those from the Ox/Sheep estuary (low potato farming intensity) were 1E10 positive. The expression of genes in the p53 tumour suppressor pathway enabled us to differentiate groups of leukemic and normal M. arenaria, validating our diagnoses. In October 2009, we confirmed that HPL prevalence was elevated in the Dunk and Wilmot estuaries compared to reference (Souris River). Moreover, leukemia prevalence declined with distance from the river mouths along transects through the Dunk and Wilmot estuaries. The pesticides ss-endosulfan and {alpha}-endosulfan were detected in surface sediments from the Dunk and Wilmot estuaries, but not in sediments from either the Souris River or several other lower intensity potato farming watersheds. Our study provides evidence of an association between intensity of potato farming and prevalence of clam leukemia at downstream estuaries in PEI. - Highlights: Black-Right-Pointing-Pointer We examined leukemia prevalence in PEI clams Mya arenaria. Black

  2. Marine pollution as indicated by oil accumulated on clams collected from the western coasts of the Red Sea, Egypt

    International Nuclear Information System (INIS)

    In order to save the environment from pollution, many techniques are used for identifying oil accumulated on clams along the western coast of the Red Sea. Gas chromatography (GC), infrared (IR), and ultraviolet (UV) absorption spectrophotometry are three different techniques used to analyze the collected samples, GC chromatograms for oil extracted from these animals indicate that the source of pollution is petroleum, and a few peaks reveal a mixture of biogenic and petrogenic hydrocarbons. These results are confirmed by the characteristic IR spectra profiles, high concentrations of the aromatic compounds, and the UV absorption spectra of these samples

  3. Ruegeria conchae sp. nov., isolated from the ark clam Scapharca broughtonii.

    Science.gov (United States)

    Lee, Jina; Whon, Tae Woong; Shin, Na-Ri; Roh, Seong Woon; Kim, Jandi; Park, Seong-Kyu; Kim, Min-Soo; Shin, Kee-Sun; Lee, Jung-Sook; Lee, Keun Chul; Kim, Young-Ok; Bae, Jin-Woo

    2012-12-01

    A slightly halophilic, Gram-negative, strictly aerobic, non-motile rod, designated TW15(T), was isolated from an ark clam in South Korea. Growth occurred at 10-37 °C, with 1-5% (w/v) NaCl and at pH 7.0-10.0. Optimal growth occurred at 25-30 °C, with 2% (w/v) NaCl and at pH 8.0. Strain TW15(T) exhibited both oxidase and catalase activities. The major fatty acids of strain TW15(T) were summed feature 8 (consisting of C(18:1)ω7c and/or C(18:1)ω6c) and 11-methyl C(18:1)ω7c. The predominant isoprenoid quinone was ubiquinone-10 (Q-10). The polar lipids of strain TW15(T) comprised phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, an unidentified aminolipid and five unidentified lipids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain TW15(T) was most closely related to Ruegeria lacuscaerulensis DSM 11314(T) (98.0% 16S rRNA gene sequence similarity). DNA-DNA relatedness with closely related strains was <52 ± 3%. The DNA G+C content was 55.7 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain TW15(T) represents a novel species of the genus Ruegeria, for which the name Ruegeria conchae sp. nov. is proposed. The type strain is TW15(T) ( = KACC 15115(T)  = JCM 17315(T)).

  4. Effect of cadmium in the clam Ruditapes decussatus assessed by proteomic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chora, Suze [University of Algarve, CIMA, Faculty of Marine and Environmental Sciences, Campus de Gambelas, 8000-139 Faro (Portugal); University of Nice-Sophia Antipolis EA 4228 ECOMERS ' Ecosystemes Cotiers Marins et Reponses aux stress' Parc Valrose, BP 71, 06108 Nice cedex 2 (France); Starita-Geribaldi, Mireille [University of Nice-Sophia Antipolis, Laboratory of Oral Microbiology, URE 01., Faculty of Odontology, Pole Universitaire Saint-Jean d' Angely, 24 avenue des Diables Bleus 06357 Nice cedex 4 (France); Guigonis, Jean-Marie [University of Nice-Sophia Antipolis, Plateforme Bernard Rossi - Proteome Metabolome IFR50, Nice, F-06107 (France); Samson, Michel [University of Nice-Sophia Antipolis, Plateforme Bernard Rossi - Proteome Metabolome IFR50, Nice, F-06107 (France); INSERM, Unite 638, Nice, F-06107 (France); Romeo, Michele [University of Nice-Sophia Antipolis EA 4228 ECOMERS ' Ecosystemes Cotiers Marins et Reponses aux stress' Parc Valrose, BP 71, 06108 Nice cedex 2 (France); Bebianno, Maria Joao, E-mail: mbebian@ualg.pt [University of Algarve, CIMA, Faculty of Marine and Environmental Sciences, Campus de Gambelas, 8000-139 Faro (Portugal)

    2009-10-04

    Cadmium, an environmental stressor due to its toxicity, persistence and accumulation in biota, is widespread in the aquatic environment. Cadmium accumulation kinetics have revealed that Ruditapes decussatus has a high affinity to this metal. Proteomics is an effective tool to evaluate the toxic effects of contaminants. The aim of this study was to investigate the Cd effects in the gill and digestive gland of the sentinel species R. decussatus. Protein expression profiles (PEPs) in the clam tissues exposed to Cd (40 {mu}g l{sup -1}, 21 days) were compared to unexposed ones. Cd induces major changes in tissue-specific protein expression profiles in gill and digestive gland. This tissue dependent response results mainly from differences in Cd accumulation, protein inhibition and/or autophagy. An overall decrease of protein spots was detected in both treated tissues, being higher in gill. Some of the spots more drastically altered after pollutants exposure were excised and nine were identified by micro liquid chromatography tandem mass spectrometry (LC-MS/MS). Proteins identified by homology search in databases included: three proteins (8-fold) up-regulated, one down-regulated, four suppressed and one induced. Cd induces major changes in proteins involved in cytoskeletal structure maintenance (muscle-type actin, adductor muscle actin and {beta}-tubulin), cell maintenance (Rab GDP) and metabolism (ALDH and MCAD, both identified by de novo sequencing) suggesting potential energetic change. They provide a valuable knowledge of Cd effects at biochemical and molecular levels in the gill and digestive gland of R. decussatus.

  5. Low Genetic Diversity and High Invasion Success of Corbicula fluminea (Bivalvia, Corbiculidae) (Müller, 1774) in Portugal

    Science.gov (United States)

    Gomes, Cidália; Sousa, Ronaldo; Mendes, Tito; Borges, Rui; Vilares, Pedro; Vasconcelos, Vitor; Guilhermino, Lúcia; Antunes, Agostinho

    2016-01-01

    The Asian clam, Corbicula fluminea, is an invasive alien species (IAS) originally from Asia that has spread worldwide causing major ecological and economic impacts in aquatic ecosystems. Here, we evaluated C. fluminea genetic (using COI mtDNA, CYTb mtDNA and 18S rDNA gene markers), morphometric and sperm morphology variation in Portuguese freshwater ecosystems. The COI marker revealed a single haplotype, which belongs to the Asian FW5 invasive lineage, suggesting a common origin for all the 13 Portuguese C. fluminea populations analysed. Morphometric analyses showed differences between the populations colonizing the North (with the exception of the Lima River) and the Centre/South ecosystems. The sperm morphology examination revealed the presence of biflagellate sperm, a distinctive character of the invasive androgenetic lineages. The low genetic variability of the Portuguese C. fluminea populations and the pattern of sperm morphology have been illuminating for understanding the demographic history of this invasive species. We hypothesize that these populations were derived from a unique introductory event of a Corbicula fluminea FW5 invasive androgenic lineage in the Tejo River, which subsequently dispersed to other Portuguese freshwater ecosystems. The C. fluminea asexual reproductive mode may have assisted these populations to become highly invasive despite the low genetic diversity. PMID:27391333

  6. Commercial Manila clam ( Tapes philippinarum) culture in British Columbia, Canada: The effects of predator netting on intertidal sediment characteristics

    Science.gov (United States)

    Munroe, Daphne; McKinley, R. Scott

    2007-03-01

    Quantifying risks posed by aquaculture to adjacent coastal ecosystems is necessary to ensure long term stability of coastal systems and the sustainability of industries that exist therein. Research has demonstrated that the use of predator netting in shellfish aquaculture increases sedimentation rates and productivity; here we examine the influence of netting on the west coast of Canada. Changes in percent silt (sediment particles 2 mm), organic and inorganic carbon levels and temperature, and differences in clam populations were monitored on paired netted and non-netted Manila clam ( Tapes philippinarum) plots on four farmed beaches at Baynes Sound, British Columbia in 2003 and 2004. There were no significant differences in the levels of silt ( p = 0.129, n = 8), gravel ( p = 0.723, n = 8), or inorganic carbon ( p = 0.070, n = 8) between netted and non-netted plots. However, the level of organic carbon was significantly higher on netted plots ( p = 0.014, n = 8) and a slight temperature buffering effect of the netting during low-tide events over the period of study. There were significantly more T. philippinarum on netted plots compared to non-netted plots ( p = 0.001, n = 8) and the length frequency distribution of the populations also differed ( p Baynes Sound British Columbia, has limited effect on the sediment.

  7. The influence of salinity on toxicological effects of arsenic in digestive gland of clam Ruditapes philippinarum using metabolomics

    Science.gov (United States)

    Ji, Chenglong; Wu, Huifeng; Liu, Xiaoli; Zhao, Jianmin; Yu, Junbao; Yin, Xiuli

    2013-03-01

    Ruditapes philippinarum, a clam that thrives in intertidal zones of various salinities, is a useful biomonitor to marine contaminants. We investigated the influence of dilution to 75% and 50% of normal seawater salinity (31.1) on the responses of the digestive gland of R. philippinarum to arsenic exposure (20 μg/L), using nuclear magnetic resonance (NMR)-based metabolomics. After acute arsenic exposure for 48 h, salinity-dependent differential metabolic responses were detected. In normal seawater, arsenic exposure increased the concentrations of branched-chain amino acids, and of threonine, proline, phosphocholine and adenosine, and it decreased the levels of alanine, hypotaurine, glucose, glycogen and ATP in the digestive glands. Differential changes in metabolic biomarkers observed at lower salinity (˜23.3) included elevation of succinate, taurine and ATP, and depletion of branched-chain amino acids, threonine and glutamine. Unique effects of arsenic at the lowest salinity (˜15.6) included down-regulation of glutamate, succinate and ADP, and up-regulation of phosphocholine. We conclude that salinity influences the metabolic responses of this clam to arsenic.

  8. Cypermethrin-Induced Toxic Effect on Glycogen Metabolism in Estuarine Clam, Marcia Opima (Gmelin, 1791 of Ratnagiri Coast, Maharashtra

    Directory of Open Access Journals (Sweden)

    Medha Tendulkar

    2012-01-01

    Full Text Available Cypermethrin is a synthetic pyrethroid class of insecticide. Toxic effects of cypermethrin were studied by selecting Marcia opima as an animal model. Cypermethrins effect on the total glycogen content of mantle, gill, foot, hepatopancreas, male gonad and a female gonad of an estuarine clam, Marcia opima was examined. The clams were exposed to 1.58 ppm cypermethrin for acute and 1/th of that concentration for chronic treatment. It was found that there was a decrease in glycogen content in various tissues as compared to control. In LC0 and LC50 groups, glycogen was decreased in all tissues except in hepatopancreas compared to control. This decrease is greater in mantle, gill, and foot in LC50 group than the decrease in those tissues of LC0 group. In chronic exposure it was found that glycogen was decreased in mantle, foot, male gonad, and female gonad when compared to the control group except in gill and hepatopancreas. Decrease in glycogen content indicates greater utilization of glycogen for metabolic purposes and too combat with cypermethrin stress. The significant increase in glycogen content in gill and hepatopancreas may be a reaction to the increase in energy demand.

  9. Effects of LSP on micro-structures and residual stresses in a 4 mm CLAM steel weld joints

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xizhang, E-mail: chenxizhang@wzu.edu.cn [School of Mechanical and Electrical Engineering, Wenzhou University., Wenzhou 325035 (China); School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Fang, Yuanyuan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China); Zhang, Shuyan; Kelleher, Joe F. [ISIS, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Zhou, Jianzhong [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu (China)

    2015-05-15

    The effects of laser shock processing (LSP) on the distribution of residual stress and micro-structure of China Low Activation Martensitic (CLAM) steel weldment were investigated via neutron diffraction and optical microscope (OM). A pair of 4 mm CLAM steel plates joined by GTA welding. Special attention is paid to the generation of high level compressive residual stresses introduced by LSP. Residual stress in longitudinal, normal and transversal direction at weldment surface and longitudinal stress through thickness are evaluated via neutron diffraction. Compressive residual stress after LSP occurred at more than 90% areas within the weld joint, it is almost double the areas of compressive stress compare to weldment surface before LSP. The maximum compressive normal residual stress becomes to −183 MPa after LSP from −63 MPa before LSP. The Modification of surface micro-structures including weld zone (WZ), heat affected zone (HAZ) and base metal (BM) are also discussed. Results to date demonstrate that laser shock processing has been a great potential method for the improvement of mechanical performance of components.

  10. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta.

    Science.gov (United States)

    Li, Yun; Sadiq, Faizan A; Fu, Li; Zhu, Hui; Zhong, Minghua; Sohail, Muhammad

    2016-01-01

    Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans T3 proteases hydrolysate (37.84%) and alcalase (30.55%). The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibitory activity. The 3 kDa membrane permeate of A. elegans T3 proteases hydrolysate showed the highest ACE-inhibitory activity with an IC50 of 0.79 mg/mL. After chromatographic separation by Sephadex G-15 gel filtration and reverse phase-high performance liquid chromatography, the potent fraction was subjected to MALDI/TOF-TOF MS/MS for identification. A novel ACE-inhibitory peptide (VQY) was identified exhibiting an IC50 of 9.8 μM. The inhibitory kinetics investigation by Lineweaver-Burk plots demonstrated that the peptide acts as a competitive ACE inhibitor. The razor clam hydrolysate obtained by A. elegans T3 proteases could serve as a source of functional peptides with ACE-inhibitory activity for physiological benefits. PMID:27271639

  11. Invasive zebra mussels (Driessena polymorpha) and Asian clams (Corbicula fluminea) survive gut passage of migratory fish species: implications for dispersal

    Science.gov (United States)

    Gatlin, Michael R.; Shoup, Daniel E.; Long, James M.

    2013-01-01

    The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for two invasive bivalves: zebra mussel (Driessena polymorpha) and Asian clam (Corbicula fluminea). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures.

  12. Histopathological survey of the mussel Mytilus chilensis (Mytilidae and the clam Gari solida (Psammobiidae from southern Chile

    Directory of Open Access Journals (Sweden)

    Florencia Cremonte

    2015-03-01

    Full Text Available A total of 175 specimens of mussels, Mytilus chilensis (Mytilidae, and 56 specimens of clams, Gari solida (Psammobiidae, were collected in natural beds and culture sites of southern Chile. Juvenile mussel specimens (3 cm of maximum length were free of parasites and diseases, whilst the commercial sized populations was parasitized by intracellular inclusions of bacteria-like organisms in the digestive gland epithelium and in the gills, by ciliates in the gills, turbellarians similar to Paravortex (Rhabocoela in the intestine lumen and copepods attached to the gills. In addition, the disseminated neoplasia disease was also present although in low prevalences. In the clam, G. solida, prokariotic inclusions were found in the digestive gland epithelium and bacteria-like organisms in the gills, often encapsulated by haemocytes; oocysts containing up to 8 sporozoites similar to Nematopsis (Apicomplexa in the connective tissue, causing haemocytic infiltration when the intensity of infection was high; ciliates belonging to two different species (one of them similar to Trichodina inhabiting the gills; and a turbellarian similar to Paravortex in the lumen of digestive system without apparent host reaction. The populations of the bivalve species here studied were devoid of serious pathogens.

  13. Identification of Perkinsus-like parasite in Manila clam, Ruditapes philippinarum using DNA molecular marker at ITS region

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Genomic DNA was extracted from hypnospores of Perkinsus-like parasite of Manila clam Ruditapes philippinarum collected at the fishing grounds in Huanghai Sea coast Shicheng Island and East China Sea coast Ningbo, China. The internal transcribed spacer(ITS)in rDNA was PCR-amplified, cloned, sequenced, and compared with that of five Perkinsus species in GenBank. The fragment amplified from DNA of parasite of either Shicheng Island or Ningbo contained 649 bp, including partial ssrRNA(51 bp) and ITS(+5.8 S)(598 bp) regions. The ITS(+5.8S) sequences of Perkinsus-like parasite of both Shicheng Island and Ningbo were all 99% identical to those ofPerkinsus atlanticus,and were not more than 95% identical to those of other four Perkinsus species including P. marinus, P.andrewsi, P. qugwadi and P. medierraneus.The ITS (+5.8S) sequence of Perkinsus-like parasite of Shicheng Island was 99% identical to that of Ningbo. These facts about nucleotide sequences suggested that the Perkinsus-like parasite in Manila clam, Ruditapes philippinarum collected from either the Huanghai Sea coast or the East China Sea coast was P. atlanticus, and might reflect P. atlanticus strains of distinct geographic distribution.

  14. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta

    Directory of Open Access Journals (Sweden)

    Yun Li

    2016-06-01

    Full Text Available Angiotensin I-converting enzyme (ACE inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH (45.87% followed by A. elegans T3 proteases hydrolysate (37.84% and alcalase (30.55%. The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibitory activity. The 3 kDa membrane permeate of A. elegans T3 proteases hydrolysate showed the highest ACE-inhibitory activity with an IC50 of 0.79 mg/mL. After chromatographic separation by Sephadex G-15 gel filtration and reverse phase-high performance liquid chromatography, the potent fraction was subjected to MALDI/TOF-TOF MS/MS for identification. A novel ACE-inhibitory peptide (VQY was identified exhibiting an IC50 of 9.8 μM. The inhibitory kinetics investigation by Lineweaver-Burk plots demonstrated that the peptide acts as a competitive ACE inhibitor. The razor clam hydrolysate obtained by A. elegans T3 proteases could serve as a source of functional peptides with ACE-inhibitory activity for physiological benefits.

  15. Identification of a regulation network in response to cadmium toxicity using blood clam Tegillarca granosa as model

    Science.gov (United States)

    Bao, Yongbo; Liu, Xiao; Zhang, Weiwei; Cao, Jianping; Li, Wei; Li, Chenghua; Lin, Zhihua

    2016-01-01

    Clam, a filter-feeding lamellibranch mollusk, is capable to accumulate high levels of trace metals and has therefore become a model for investigation the mechanism of heavy metal toxification. In this study, the effects of cadmium were characterized in the gills of Tegillarca granosa during a 96-hour exposure course using integrated metabolomic and proteomic approaches. Neurotoxicity and disturbances in energy metabolism were implicated according to the metabolic responses after Cd exposure, and eventually affected the osmotic function of gill tissue. Proteomic analysis showed that oxidative stress, calcium-binding and sulfur-compound metabolism proteins were key factors responding to Cd challenge. A knowledge-based network regulation model was constructed with both metabolic and proteomic data. The model suggests that Cd stimulation mainly inhibits a core regulation network that is associated with histone function, ribosome processing and tight junctions, with the hub proteins actin, gamma 1 and Calmodulin 1. Moreover, myosin complex inhibition causes abnormal tight junctions and is linked to the irregular synthesis of amino acids. For the first time, this study provides insight into the proteomic and metabolomic changes caused by Cd in the blood clam T. granosa and suggests a potential toxicological pathway for Cd. PMID:27760991

  16. Assessment of parental contribution and effective population size from a 3×3 diallel cross of clam Meretrix meretrix

    Science.gov (United States)

    Dai, Ping; Wang, Hongxia; Liu, Baozhong

    2014-03-01

    Unbalanced parental contribution and small effective population size ( N e) are common issues during the artificial breeding of marine bivalves. The impact of hatchery-spawning practices on parental contribution, effective population size, the N e/ N ratio, and genetic diversity are largely unknown. To address this, we conducted a parentage analysis on a complete 3×3 diallel cross of clam M eretrix meretrix using eight microsatellite markers. The genetic diversity of the parents was higher than that of their respective offspring in most crosses (8/9). Sires or dams from the same family contributed unequally to the pool of offspring from a particular cross, and the same parent clam exhibited large variation in parental contribution among different crosses. The variance in male contribution was higher than that of the female contribution in most crosses, suggesting that male contribution was more skewed than for females. The N e/ N ratio for nine crosses ranged from 0.58 to 0.86. There was no linear relationship between the sex ratio and the N e/ N ratio ( P > 0.05). Moreover, a sex ratio closer to one-to-one does not necessarily mean a larger effective population size. A solution to small effective population size in commercial breeding programs is increasing broodstock numbers and attempting to maintain a balanced sex ratio.

  17. The influence of salinity on toxicological effects of arsenic in digestive gland of clam Ruditapes philippinarum using metabolomics

    Institute of Scientific and Technical Information of China (English)

    JI Chenglong; WU Huifeng; LIU Xiaoli; ZHAO Jianmin; YU Junbao; YIN Xiuli

    2013-01-01

    Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity (31.1) on the responses of the digestive gland of R.philippinarum to arsenic exposure (20 μg/L),using nuclear magnetic resonance (NMR)-based metabolomics.After acute arsenic exposure for 48 h,salinity-dependent differential metabolic responses were detected.In normal seawater,arsenic exposure increased the concentrations of branched-chain amino acids,and of threonine,proline,phosphocholine and adenosine,and it decreased the levels of alanine,hypotaurine,glucose,glycogen and ATP in the digestive glands.Differential changes in metabolic biomarkers observed at lower salinity (~23.3)included elevation of succinate,taurine and ATP,and depletion of branched-chain amino acids,threonine and glutamine.Unique effects of arsenic at the lowest salinity (~15.6) included down-regulation of glutamate,succinate and ADP,and up-regulation of phosphocholine.We conclude that salinity influences the metabolic responses of this clam to arsenic.

  18. Screening of antiangiogenic potential of twenty two marine invertebrate extracts of phylum Mollusca from South East Coast of India

    Institute of Scientific and Technical Information of China (English)

    Pankaj Gupta; Muthuvel Arumugam; Raj Vardhan Azad; Rohit Saxena; Supriyo Ghose; Nihar Ranjan Biswas; Thirumurthy Velpandian

    2014-01-01

    Objective: To evaluate the antiangiogenic potential of twenty two marine invertebrate species of Phylum Mollusca from south east coast of India.Methods:Live specimens of molluscan species were collected and their methanolic extracts were evaluated for preliminary antiangiogenic activity using the in ovo chick chorio-allantoic membrane assay. The extracts were further evaluated for in vivo antiangiogenic activity using chemical cautery induced corneal neovascularization assay in rats and oxygen induced retinopathy assay in rat pups.Results:In the chick chorio-allantoic membrane assay, four methanolic extracts of marine molluscan species viz. Meretrix meretrix, Meretrix casta, Telescopium telescopium and Bursacrumena methanolic extracts exhibited noticeable antiangiogenic activity at the tested concentration of 200 µg whereby they significantly inhibited the VEGF induced proliferation of new blood vessels. Among these four extracts, the methanolic extract of Meretrix casta exhibited relatively higher degree of antiangiogenic activity with an inhibitiory percentage (64.63%) of the VEGF induced neovascularization followed by the methanolic extracts of Telescopium telescopium (62.02%), Bursa crumena (60.48%) and Meretrix meretrix (47.01%). These four methanolic extracts were further evaluated for in vivo antiangiogenic activity whereby the methanolic extract of Telescopium telescopium exhibited most noticeable inhibition (42.58%) of the corneal neovascularization in rats in comparison to the sham treated group, and also exhibited most noticeable inhibition (31.31%) of the oxygen induced retinal neovascularization in rat pups in comparison to the hyperoxia group that was observed for considerable retinal neovascularization.Conclusions:The significant antiangiogenic activity evinced by the extract of Telescopium telescopium merits further investigation for ocular neovascular diseases.

  19. Tropomyosin and Actin Identified as Major Allergens of the Carpet Clam (Paphia textile and the Effect of Cooking on Their Allergenicity

    Directory of Open Access Journals (Sweden)

    Zailatul Hani Mohamad Yadzir

    2015-01-01

    Full Text Available Objectives. To identify the major allergenic proteins of clam (Paphia textile and to investigate the effect of different cooking methods on the allergenicity of these identified proteins. Methods. Clam protein extracts were separated by denaturing polyacrylamide gel electrophoresis. IgE reactive proteins were then analyzed by immunoblotting with sera from patients with positive skin prick tests (SPT to the raw clam extract. Mass spectrometry was used to identify the major allergenic proteins of this clam. Results. Raw extract showed 12 protein bands (18–150 kDa. In contrast, fewer protein bands were seen in the boiled extract; those ranging from 40 to 150 kDa were denatured. The protein profiles were similarly altered by frying or roasting. The immunoblots of raw and boiled extracts yielded 10 and 2 IgE-binding proteins, respectively. The fried and roasted extracts showed only a single IgE-binding protein at 37 kDa. Mass spectrometry analysis of the 37 and 42 kDa major allergens indicated that these spots were tropomyosin and actin, respectively. Conclusion. The two major allergens of Paphia textile were identified as the thermostable tropomyosin and a new thermolabile allergen actin.

  20. Perkinsus olseni and P. chesapeaki detected in a survey of perkinsosis of various clam species in Galicia (NW Spain) using PCR-DGGE as a screening tool.

    Science.gov (United States)

    Ramilo, Andrea; Pintado, José; Villalba, Antonio; Abollo, Elvira

    2016-01-01

    A survey on perkinsosis was performed involving 15 locations scattered along the Galician coast (NW Spain) and four clam species with high market value (Ruditapes decussatus, Ruditapes philippinarum, Venerupis corrugata and Polititapes rhomboides). The prevalence of Perkinsus parasites was estimated by PCR using genus-specific primers. The highest percentage of PCR-positive cases for perkinsosis corresponded to clams R. decussatus and V. corrugata, while lower values were detected in R. philippinarum and no case was found in P. rhomboides. The discrimination of Perkinsus species was performed by PCR-RFLP and by a new PCR-DGGE method developed in this study. Perkinsus olseni was identified in every clam species, except in P. rhomboides, using both PCR-DGGE and PCR-RFLP. Additionally, Perkinsus chesapeaki was only detected by PCR-DGGE infecting two Manila clams R. philippinarum from the same location, reporting the first case in Galicia. P. chesapeaki identification was further confirmed by in situ hybridisation assay and phylogenetic analysis of ITS region and LSU rDNA.

  1. How life history influences the responses of the clam Scrobicularia plana to the combined impacts of carbamazepine and pH decrease

    International Nuclear Information System (INIS)

    In the present study, the bivalve Scrobicularia plana, collected from two contrasting areas (pristine location and mercury contaminated area), was selected to assess the biochemical alterations imposed by pH decrease, carbamazepine (an antiepileptic) and the combined effect of both stressors. The effects on oxidative stress related biomarkers after 96 h exposure revealed that pH decrease and carbamazepine induced alterations on clams, with greater impacts on individuals from the contaminated area which presented higher mortality, higher lipid peroxidation and higher glutathione S-transferase activity. These results emphasize the risk of extrapolating results from one area to another, since the same species inhabiting different areas may be affected differently when exposed to the same stressors. Furthermore, the results obtained showed that, when combined, the impact of pH decrease and carbamazepine was lower than each stressor acting alone, which could be related to the defence mechanism of valves closure when bivalves are under higher stressful conditions. - Highlights: • Environmentally relevant concentrations of CBZ and pH 7.1 impacted the performance of Scrobicularia plana. • The combination of CBZ and pH 7.1 did not induce higher impacts compared with stressors acting alone. • Clams from a polluted area showed greater alterations than clams collected from an unpolluted area. - pH decrease and carbamazepine induced biochemical alterations on clams (Scrobicularia plana), with greater impacts on individuals from the contaminated area

  2. Population density, biomass, and age-class structure of the invasive clam Corbicula fluminea in rivers of the lower San Joaquin River watershed, California

    Science.gov (United States)

    Brown, L.R.; Thompson, J.K.; Higgins, K.; Lucas, L.V.

    2007-01-01

    Corbicula fluminea is well known as an invasive filter-feeding freshwater bivalve with a variety of effects on ecosystem processes. However. C. fluminea has been relatively unstudied in the rivers of the western United States. In June 2003, we sampled C. fluminea at 16 sites in the San Joaquin River watershed of California, which was invaded by C. fluminea in the 1940s. Corbicula fluminea was common in 2 tributaries to the San Joaquin River, reaching densities of 200 clams??m-2, but was rare in the San Joaquin River. Biomass followed a similar pattern. Clams of the same age were shorter in the San Joaquin River than in the tributaries. Distribution of clams was different in the 2 tributaries, but the causes of the difference are unknown. The low density and biomass of clams in the San Joaquin River was likely due to stressful habitat or to water quality, because food was abundant. The success of C. fluminea invasions and subsequent effects on trophic processes likely depends on multiple factors. As C. fluminea continues to expand its range around the world, questions regarding invasion success and effects on ecosystems will become important in a wide array of environmental settings.

  3. Comparative genomic analysis of mitochondrial protein-coding genes in Veneroida clams: Analysis of superfamily-specific genomic and evolutionary features.

    Science.gov (United States)

    Hwang, Jae Yeon; Lee, Chang-Kyu; Kim, Heebal; Nam, Bo-Hye; An, Cheul Min; Park, Jung Youn; Park, Kyu-Hyun; Huh, Chul-Sung; Kim, Eun Bae

    2015-12-01

    Veneroida is the largest order of bivalves, and these clams are commercially important in Asian countries. Although numerous studies have focused on the genomic characters of individual species or genera in Veneroida, superfamily-specific genomic characters have not been determined. In this study, we performed a comparative genomic analysis of 12 mitochondrial protein coding genes (PCGs) from 25 clams in six Veneroida superfamilies to determine genomic and evolutionary features of each superfamily. Length and distribution of nucleotides encoding the PCGs were too variable to define superfamily-specific genomic characters. Phylogenetic analysis revealed that PCGs are suitable for classification of species in three superfamilies: Cardioidea, Mactroidea, and Veneroidea. However, one species classified in Tellinoidea, Sinonovacula constricta, was evolutionarily closer to Solenoidea clams than Tellinoidea clams. dN/dS analysis showed that positively selected sites in NADH dehydrogenase subunit, nd4 and subunit of ATP synthase, atp6 were present in Mactroidea. Differences in selected sites in the nd4 and atp6 could be caused by superfamily-level differences in sodium transport or ATP synthesis functions, respectively. These differences in selected sites in NADH may have conferred these animals, which have low motility and do not generally move, with increased flexibility to maintain homeostasis in the face of osmotic pressure. Our study provides insight into evolutionary traits as well as facilitates identification of veneroids. PMID:26343338

  4. Certification of Trace Elements and Methyl Mercury Mass Fractions in IAEA-461 Clam (Gafrarium tumidum) Sample

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories is to assist Member States in the use of both stable and radioisotope analytical techniques to understand, monitor and protect the environment. In this context, the major impact exerted by large coastal cities on marine ecosystems is an issue of primary concern for the IAEA and the IAEA Environment Laboratories. The marine pollution assessments required to understand such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments. The IAEA Environment Laboratories has been assisting national laboratories and regional laboratory networks since the early 1970s through the provision of reference material programme for the analysis of radionuclides, trace elements and organic compounds in marine samples. Quality assurance, quality control and associated good laboratory practice are essential components of all marine environmental monitoring studies. Quality control procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess the reliability and comparability of measurement data. Data that are not based on adequate quality assurance and quality control can be erroneous, and their misuse can lead to poor environmental management decisions. This publication describes the production of the IAEA-461 certified reference material, which was produced following ISO Guide 34:2009, General Requirements for the Competence of Reference Material Producers. A sample of approximately 60 kg of clams (Gafrarium tumidum) was collected in Noumea, New Caledonia, and processed at the IAEA Environment Laboratories to produce a certified reference material of marine biota. The sample contained certified mass fractions for arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, mercury, methyl mercury, manganese, nickel, selenium, vanadium and zinc. The produced vials

  5. Interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.

    Science.gov (United States)

    Garcia, R N; Chung, K W; Key, P B; Burnett, L E; Coen, L D; Delorenzo, M E

    2014-04-01

    Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene). Acute toxicity (4-day LC50) values ranged from 1.59 to >10 mg/L. Overall, clams were more susceptible to mosquito control insecticides than oysters. Naled was the most toxic compound in oyster larvae, whereas resmethrin was the most toxic compound in clam larvae. Mortality for both species generally increased with chronic insecticide exposure (21-day LC50 values ranged from 0.60 to 9.49 mg/L). Insecticide exposure also caused sublethal effects, including decreased swimming activity after 4 days in larval oysters (4-day EC50 values of 0.60 to 2.33 mg/L) and decreased growth (shell area and weight) in juvenile clams and oysters after 21 days (detected at concentrations ranging from 0.625 to 10 mg/L). Hypoxia, hypercapnia, and a combination of hypoxia and hypercapnia caused mortality in larval clams and increased resmethrin toxicity. These data will benefit both shellfish mariculture operations and environmental resource agencies as they manage the use of mosquito control insecticides near coastal ecosystems.

  6. Long-term Cultivation of the Deep-Sea Clam Calyptogena okutanii: Changes in the Abundance of Chemoautotrophic Symbiont, Elemental Sulfur, and Mucus.

    Science.gov (United States)

    Ohishi, Kazue; Yamamoto, Masahiro; Tame, Akihiro; Kusaka, Chiho; Nagai, Yukiko; Sugimura, Makoto; Inoue, Koji; Uematsu, Katsuyuki; Yoshida, Takao; Ikuta, Tetsuro; Toyofuku, Takashi; Maruyama, Tadashi

    2016-06-01

    Survival of deep-sea Calyptogena clams depends on organic carbon produced by symbiotic, sulfur-oxidizing, autotrophic bacteria present in the epithelial cells of the gill. To understand the mechanism underlying this symbiosis, the development of a long-term cultivation system is essential. We cultivated specimens of Calyptogena okutanii in an artificial chemosynthetic aquarium with a hydrogen sulfide (H2S) supply system provided by the sulfate reduction of dog food buried in the sediment. We studied morphological and histochemical changes in the clams' gills by immunohistochemical and energy-dispersive X-ray analyses. The freshly collected clams contained a high amount of elemental sulfur in the gill epithelial cells, as well as densely packed symbiotic bacteria. Neither elemental sulfur nor symbiotic bacteria was detected in any other organs except the ovaries, where symbiotic bacteria, but not sulfur, was detected. The longest survival of an individual clam in this aquarium was 151 days. In the 3 clams dissected on Days 57 and 91 of the experiment, no elemental sulfur was detected in the gills. The symbiotic bacteria content had significantly decreased by Day 57, and was absent by Day 91. For comparison, we also studied the deep-sea mussel Bathymodiolus septemdierum, which harbors a phylogenetically close, sulfur-oxidizing, symbiotic bacterium with similar sulfur oxidation pathways. Sulfur particles were not detected, even in the gills of the freshly collected mussels. We discuss the importance of the proportion of available H2S and oxygen to the bivalves for elemental sulfur accumulation. Storage of nontoxic elemental sulfur, an energy source, seems to be an adaptive strategy of C. okutanii. PMID:27365420

  7. Contrasting physiological responses of two populations of the razor clam Tagelus dombeii with different histories of exposure to paralytic shellfish poisoning (PSP.

    Directory of Open Access Journals (Sweden)

    Jorge M Navarro

    Full Text Available This study describes the physiological performance of two populations of the razor clam Tagelus dombeii from two geographic areas with different histories of exposure to paralytic shellfish poisoning (PSP linked to the toxic dinoflagellate Alexandrium catenella. Clams from Melinka-Aysén, which are frequently exposed to PSP, were not affected by the presence of toxins in the diet. However, clams from Corral-Valdivia, which have never been exposed to PSP, exhibited significantly reduced filtration activity and absorption, affecting the energy allocated to scope for growth (SFG. Ammonia excretion and oxygen uptake were not affected significantly by the presence of A. catenella in the diet. Measurements of energy acquisition and expenditure were performed during a 12-day intoxication period. According to three-way repeated measure ANOVAs, the origin of the clams had a highly significant effect on all physiological variables, and the interaction between diet and origin was significant for the clearance and absorption rates and for the scope for growth. The scope for growth index showed similar positive values for both the toxic and non-toxic individuals from the Melinka-Aysén population. However, it was significantly reduced in individuals from Corral-Valdivia when exposed to the diet containing A. catenella. The absence of differences between the physiological response of the toxic and non-toxic clams from Melinka-Aysén may be related to the frequent presence of A. catenella in the environment, indicating that this bivalve does not suffer negative consequences from PSP. By contrast, A. catenella has a negative effect on the physiological performance, primarily on the energy gained from the environment, on T. dombeii from Corral-Valdivia. This study supports the hypothesis that the history of PSP exposure plays an important role in the physiological performance and fitness of filter feeding bivalves.

  8. Interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.

    Science.gov (United States)

    Garcia, R N; Chung, K W; Key, P B; Burnett, L E; Coen, L D; Delorenzo, M E

    2014-04-01

    Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene). Acute toxicity (4-day LC50) values ranged from 1.59 to >10 mg/L. Overall, clams were more susceptible to mosquito control insecticides than oysters. Naled was the most toxic compound in oyster larvae, whereas resmethrin was the most toxic compound in clam larvae. Mortality for both species generally increased with chronic insecticide exposure (21-day LC50 values ranged from 0.60 to 9.49 mg/L). Insecticide exposure also caused sublethal effects, including decreased swimming activity after 4 days in larval oysters (4-day EC50 values of 0.60 to 2.33 mg/L) and decreased growth (shell area and weight) in juvenile clams and oysters after 21 days (detected at concentrations ranging from 0.625 to 10 mg/L). Hypoxia, hypercapnia, and a combination of hypoxia and hypercapnia caused mortality in larval clams and increased resmethrin toxicity. These data will benefit both shellfish mariculture operations and environmental resource agencies as they manage the use of mosquito control insecticides near coastal ecosystems. PMID:24531857

  9. Strict sex-specific mtDNA segregation in the germ line of the DUI species Venerupis philippinarum (Bivalvia: Veneridae).

    Science.gov (United States)

    Ghiselli, Fabrizio; Milani, Liliana; Passamonti, Marco

    2011-02-01

    Doubly Uniparental Inheritance (DUI) is one of the most striking exceptions to the common rule of standard maternal inheritance of metazoan mitochondria. In DUI, two mitochondrial genomes are present, showing different transmission routes, one through eggs (F-type) and the other through sperm (M-type). In this paper, we report results from a multiplex real-time quantitative polymerase chain reaction analysis on the Manila clam Venerupis philippinarum (formerly Tapes philippinarum). We quantified M- and F-types in somatic tissues, gonads, and gametes. Nuclear and external reference sequences were used, and the whole experimental process was designed to avoid any possible cross-contamination. In most male somatic tissues, the M-type is largely predominant: This suggests that the processes separating sex-linked mitochondrial DNAs (mtDNAs) in somatic tissues are less precise than in other DUI species. In the germ line, we evidenced a strict sex-specific mtDNA segregation because both sperm and eggs do carry exclusively M- and F-types, respectively, an observation that is in contrast with a previous analysis on Mytilus galloprovincialis. More precisely, whereas two mtDNAs are present in the whole gonad, only the sex-specific one is detected in gametes. Because of this, we propose that the mtDNA transmission is achieved through a three-checkpoint process in V. philippinarum. The cytological mechanisms of male mitochondria segregation in males and degradation in females during the embryo development (here named Checkpoint #1 and Checkpoint #2) are already well known for DUI species; a Checkpoint #3 would act when primordial germ cells (PGCs) are first formed and would work in both males and females. We believe that Checkpoint #3 is a mere variation of the "mitochondrial bottleneck" in species with standard maternal inheritance, established when their PGCs separate during embryo cleavage.

  10. Effect of acidic electrolyzed water-induced bacterial inhibition and injury in live clam (Venerupis philippinarum) and mussel (Mytilus edulis).

    Science.gov (United States)

    Al-Qadiri, Hamzah M; Al-Holy, Murad A; Shiroodi, Setareh Ghorban; Ovissipour, Mahmoudreza; Govindan, Byju N; Al-Alami, Nivin; Sablani, Shyam S; Rasco, Barbara

    2016-08-16

    The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus and Campylobacter jejuni in laboratory contaminated live clam (Venerupis philippinarum) and mussel (Mytilus edulis) was investigated. The initial levels of bacterial contamination were: in clam 4.9 to 5.7log10CFU/g, and in mussel 5.1 to 5.5log10CFU/g. Two types of AEW were used for treatment time intervals of 1 and 2h: strong (SAEW) with an available chlorine concentration (ACC) of 20mg/L, pH=3.1, and an oxidation-reduction potential (ORP) of 1150mV, and weak (WAEW) at ACC of 10mg/L, pH=3.55 and ORP of 950mV. SAEW and WAEW exhibited significant inhibitory activity against inoculated bacteria in both shellfish species with significant differences compared to saline solutions treatments (1-2% NaCl) and untreated controls (0h). SAEW showed the largest inhibitory activity, the extent of reduction (log10CFU/g) ranged from 1.4-1.7 for E. coli O104:H4; 1.0-1.6 for L. monocytogenes; 1.3-1.6 for A. hydrophila; 1.0-1.5 for V. parahaemolyticus; and 1.5-2.2 for C. jejuni in both types of shellfish. In comparison, significantly (Pmonocytogenes; 0.6-1.3 for A. hydrophila; 0.7-1.3 for V. parahaemolyticus; and 0.8-1.9 for C. jejuni in both types of shellfish. Among all bacterial strains examined in this study, AEW induced less bacterial injury (~0.1-1.0log10CFU/g) and more inactivation effect. This study revealed that AEW (10-20mg/L ACC) could be used to reduce bacterial contamination in live clam and mussel, which may help control possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish. PMID:27208583

  11. Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

    International Nuclear Information System (INIS)

    Highlights: •PCO2 alters accumulation of Cd and Cu in clam cells. •Accumulation of Cd induces release of free Zn2+. •Accumulation of Cu induces an increase in free Cu2+ and Fe2+. •Metal-induced oxidative stress is alleviated at high PCO2. •Toxicity of Cu in likely enhanced while that of Cd alleviated by high PCO2. -- Abstract: Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 (PCO2) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high PCO2 (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between PCO2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of PCO2 (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated PCO2 resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated PCO2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated PCO2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd2+ concentration remained the same, while intracellular levels of free Zn2+ increased suggesting that Cd2+ substitutes bound Zn2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn2+ but led to a profound increase in the intracellular levels of labile Cu2+ and Fe2+. An increase

  12. 蛤蜊中微量元素含量的测定%Determination of trace elements in Clams

    Institute of Scientific and Technical Information of China (English)

    姜凤

    2014-01-01

    用高压罐硝化样品,以正交试验原理,借助方差分析,利用ICP-AES法测定蛤蜊中Co、Mg、Zn、Fe、Ca、Sr等15种微量元素的含量,方法回收率在96.50%~102.50%之间,相对标准偏差小于2.57%。ICP-AES法具有灵敏度高、简单,快捷等优点,且多元素同时测定,更适合蛤蜊中金属与非金属元素的分析测定。通过实验:蛤蜊中含有丰富的Mg、Zn、Fe、Ca、K、P,还含有Se、Ge、Sr、Mn等微量元素对人体健康极其有益,是营养价值很高的海产品。但近些年,海水被环境造成一定程度的污染,食用时应加以注意。%Samples were digested by high pressure nitrifying pot.Orthogonal test and analysis of variance were applied to the determination of content of 15 kinds of trace elements in clam such as Co,Mg,Zn,Fe,Ca,Sr etc by ICP-AES .The recovery rate of the method is in the range of 96.50%-102.50%. Relative standard deviations is less than 2.57%. ICP-AES method is high sensitivity,convenient, rapid and simultaneous determination of many elements, more suitable for the analysis of clam in metallic and nonmetallic elements determination. Experimental results show that clams are rich in Mg, Zn, Fe, Ca, K, P, also contains Se, Ge, Sr, Mn and other trace elements beneficial to human body extremely. Seafood is high nutritional value, but the current environment seawater caused a certain degree of pollution.Consumption should be noted.

  13. The reproductive cycle of Eurhomalea exalbida (Chemnitz, 1795) (Bivalvia: Veneridae) in Ushuaia Bay (54°50′ S), Beagle Channel (Argentina)

    OpenAIRE

    Morriconi, E.; Lomovasky, B.; Calvo, J.; Brey, Thomas

    2002-01-01

    The reproductive cycle of Eurhomalea exalbida (Chemnitz, 1795) in Ushuaia Bay, Beagle Channel, was studied from October 1998 to December 1999. Clams were collected monthly by SCUBA diving at 3 to 5 m water depth. The degree of sexual maturity was determined histologically (n=318). The sex ratio was 1:1 (Chi-squared p > 0.05). First sexual maturity occurred at 39 mm shell heigth in males and 40 mm in females (i.e. 4 years of age).Five distinct histological stages of sexual maturity could be es...

  14. Metabolic responses of clams, Ruditapes decussatus and Ruditapes philippinarum, to short-term exposure to lead and zinc.

    Science.gov (United States)

    Aru, Violetta; Sarais, Giorgia; Savorani, Francesco; Engelsen, Søren Balling; Cesare Marincola, Flaminia

    2016-06-15

    This study investigated the effects of 48h heavy metal exposure upon the metabolic profiles of Ruditapes decussatus and Ruditapes philippinarum using (1)H NMR metabolomics. Both species were exposed to increasing concentrations of lead nitrate (10, 40, 60 and 100μg/L) and zinc chloride (20, 50, 100 and 150μg/L), under laboratory conditions. ICP-OES analysis was further performed on the clams' samples in order to verify the occurrence of heavy metal bioaccumulation. With respect to the controls, the metabolic profiles of treated R. decussatus exhibited higher levels of organic osmolytes and lower contents of free amino acids. An opposite behavior was shown by R. philippinarum. In terms of heavy metal, the exposure effects were more evident in the case of Pb rather than Zn. These findings show that NMR-based metabolomics has the required sensitivity and specificity for the identification of metabolites that can act as sensitive indicators of contaminant-induced stress.

  15. Sequencing and de novo assembly of the Asian clam (Corbicula fluminea transcriptome using the Illumina GAIIx method.

    Directory of Open Access Journals (Sweden)

    Huihui Chen

    Full Text Available BACKGROUND: The Asian clam (Corbicula fluminea is currently one of the most economically important aquatic species in China and has been used as a test organism in many environmental studies. However, the lack of genomic resources, such as sequenced genome, expressed sequence tags (ESTs and transcriptome sequences has hindered the research on C. fluminea. Recent advances in large-scale RNA-Seq enable generation of genomic resources in a short time, and provide large expression datasets for functional genomic analysis. METHODOLOGY/PRINCIPAL FINDINGS: We used a next-generation high-throughput DNA sequencing technique with an Illumina GAIIx method to analyze the transcriptome from the whole bodies of C. fluminea. More than 62,250,336 high-quality reads were generated based on the raw data, and 134,684 unigenes with a mean length of 791 bp were assembled using the Velvet and Oases software. All of the assembly unigenes were annotated by running BLASTx and BLASTn similarity searches on the Nt, Nr, Swiss-Prot, COG and KEGG databases. In addition, the Clusters of Orthologous Groups (COGs, Gene Ontology (GO terms and Kyoto Encyclopedia of Gene and Genome (KEGG annotations were also assigned to each unigene transcript. To provide a preliminary verification of the assembly and annotation results, and search for potential environmental pollution biomarkers, 15 functional genes (five antioxidase genes, two cytochrome P450 genes, three GABA receptor-related genes and five heat shock protein genes were cloned and identified. Expressions of the 15 selected genes following fluoxetine exposure confirmed that the genes are indeed linked to environmental stress. CONCLUSIONS/SIGNIFICANCE: The C. fluminea transcriptome advances the underlying molecular understanding of this freshwater clam, provides a basis for further exploration of C. fluminea as an environmental test organism and promotes further studies on other bivalve organisms.

  16. Persistent organic pollutants (POPs) in populations of the clam Chione californiensis in coastal lagoons of the Gulf of California.

    Science.gov (United States)

    Vargas-González, Héctor H; Méndez-Rodríguez, Lía C; García-Hernández, Jaqueline; Mendoza-Salgado, Renato A; Zenteno-Savín, Tania; Arreola-Lizárraga, José A

    2016-07-01

    This study examines the potential public health risk due to the massive use of organochlorine pesticides (OCs) in agriculture in the Gulf of California. Specimens of the clam Chione californiensis were collected from three coastal lagoons (Yavaros, Altata and Reforma). Sites were classified as polluted/nonpolluted based on the presence/absence of OCs as an indicator of the persistence of these pollutants; in polluted sites, the time elapsed since pesticide application (past or recent) was estimated. Screening values (SV) for protecting human health as per the U.S. Environmental Protection Agency (EPA) were used for risk assessment. OCs detected were ranked according to frequency of occurrence as follows: γ-chlordane (75%) > endrin (54%) > aldrin (48%) > heptachlor, and dichlorodiphenyl-trichloroethane (DDE) (37%) > β-heptachlor epoxide (30%) > lindane (α-BHC, δ-BHC) and endosulphan I (≤ 6%). Specifically, OCs detected at the highest concentration were heptachlor in Yavaros (0.0168 µgg(-1)) and Altata (0.0046 µgg(-1)), and aldrin in Reforma (0.0019 µgg(-1)). β-Heptachlor epoxide in Altata and Reforma was the only OC with a concentration exceeding the EPA Screening Value. From our results and based on the monthly consumption limit set forth by EPA, the maximum safe consumption of clams to avoid a carcinogenic risk derived from β-heptachlor epoxide in the fishing villages of Yavaros and Altata is 4 servings per month (1 serving = 0.227 kg) by a 70-kg person. These findings suggest that concentrations of OCs and their isomers in C. californiensis populations reflect environmental persistence as well as recent inputs of OCs into coastal lagoons in the Gulf of California.

  17. Northern Marshall Islands radiological survey: radionuclide concentrations in fish and clams and estimated doses via the marine pathway

    International Nuclear Information System (INIS)

    The survey consisted, in part, of an aerial radiological reconnaissance to map the external gamma-ray exposure rates. As a secondary phase, terrestrial and marine samples were collected to assess the radiological dose from pertinent food chains to atoll inhabitants. The marine sample collection, processing, and dose assessment methodology are presented as well as the concentration data for 90Sr, 137Cs, 238Pu, 239+240Pu, 241Am, and any of the other gamma emitters in fish and clam muscle tissue from the different species collected. Doses are calculated from the average radionuclide concentrations in fish and clam muscle tissue assuming an average daily intake of 200 and 10 g, respectivelty. The 90Sr concentration in muscle tissue is very low and there is little difference in the average concentrations from the different fish from different atolls or islands. The 239+240Pu concentration in the muscle tissue of all reef species, however, is higher than that in pelagic lagoon fish. In contrast, 137Cs concentrations are lowest in the muscle tissue of the bottom-feeding reef species and highest in pelagic logoon fish. Recent measurements of radionuclide concentrations in fish muscle tissue and other marine dietary items from international sources show that the average concentrations in species from the Marshall Islands are comparable to those in fish typically consumed as food in the United States and are generally lower than those in most international marine dietary items. The whole-body dose rates based on continuous consumption of 200 g/d of fish range from 0.028 to 0.1 mrem/y; the bone-marrow dose rates range from 0.029 to 0.12 mrem/y. The dose commitment, or 30-y integral doses, range from 0.00063 to 0.0022 rem for the whole body and from 0.00065 to 0.0032 rem for the bone marrow

  18. Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Qing [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Zhang, Yong [Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China); Peng, Hui-Fang [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); Ke, Cai-Huan, E-mail: chke@xmu.edu.cn [State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Huang, He-Qing, E-mail: hqhuang@xmu.edu.cn [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China)

    2014-11-15

    Highlights: • Fe accumulated in hepatopancreas tissues after iron-enriched exposure. • Ferritin expression was positively correlated with iron concentration in seawater. • Ferritin appears to be involved in iron homeostasis and immune defense mechanism of M. meretrix. • mRNAs of cytokine genes responded faster than antioxidant enzyme genes in immune defense mechanism. • The study gives a new potential biomarker for monitoring iron levels in seawater. - Abstract: The responses of genes encoding defense components such as ferritin, the lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), the inhibitor of nuclear factor-κB (IκB), metallothionein, and glutathione peroxidase were assessed at the transcriptional level in order to investigate the toxicological and immune mechanism of the hard clam Meretrix meretrix (HCMM) following challenge with iron or a bacterium (Vibrio parahaemolyticus). Fe dissolved in natural seawater led to an increase of Fe content in both the hepatopancreas and gill tissue of HCMM between 4 and 15 days of exposure. The ferritin gene responded both transcriptionally as indicated by real-time quantitative PCR and translationally as shown by western blotting results to iron exposure and both transcriptional and translational ferritin expression in the hepatopancreas had a positive correlation with the concentration of dissolved iron in seawater. Both iron and V. parahaemolyticus exposure triggered immune responses with similar trends in clam tissues. There was a significant post-challenge mRNA expression of LITAF and IκB at 3 h, ferritin at 24 h, and metallothionein and glutathione peroxidase at 48 h. This behavior might be linked to their specific functions in physiological processes. These results suggested that similar signaling pathways were triggered during both iron and V. parahaemolyticus challenges. Here, we indicated that the ferritin of Meretrix meretrix was an intermediate in the pathway of iron homeostasis

  19. Metals bioaccumulation and biomarkers responses in the Neotropical freshwater clam Anodontites trapesialis: Implications for monitoring coal mining areas.

    Science.gov (United States)

    Oliveira, Luciana Fernandes de; Cabral, Millena Terezinha; Vieira, Carlos Eduardo Delfino; Antoniazzi, Matheus Henrique; Risso, Wagner Ezequiel; Martinez, Claudia Bueno Dos Reis

    2016-11-15

    As one of the most impactful industries, coal mining can promote several alterations at surrounding environment. In surface water, elevated concentrations of metals like Mn, Zn, Fe and Al are often observed. Thus, the aim of this study was to investigate the bioaccumulation and the sub-lethal effects of these metals on various organs of the Neotropical bivalve Anodontites trapesialis confined along a stream located near a coal mine, in order to assess a set of biomarkers that could be used for effectively monitoring coal mining areas. Clams were caged, for 96h, at two sites located upstream (Up1 and Up2) and two sites downstream (Dw1 and Dw2) from the mine. Metals bioaccumulation was determined in gills, mantle, digestive gland, muscle and hemolymph and the following biomarkers were measured in A. trapesialis tissues: total antioxidant capacity against peroxyl radicals, metallothionein content, lipid peroxidation (LPO), proteins carbonylation, glutathione S-transferase activity, superoxide dismutase activity and acetylcholinesterase (AChE) activity. The results showed that Al and Fe bioaccumulation in the gills and hemolymph, Al bioaccumulation in the mantle and muscle, increased LPO in the gills (Dw1 and Dw2) and mantle (Dw1), as well as reduced AChE activity in the muscle (Dw1 and Dw2) should be considered effective biomarkers for monitoring coal mining areas. A. trapesialis proved to be an efficient biological model, considering that biomarkers responses were observed in the clams after only 96h of confinement at Dw sites, accordingly this species could be a good candidate for monitoring Neotropical freshwaters. PMID:27453135

  20. Persistent organic pollutants (POPs) in populations of the clam Chione californiensis in coastal lagoons of the Gulf of California.

    Science.gov (United States)

    Vargas-González, Héctor H; Méndez-Rodríguez, Lía C; García-Hernández, Jaqueline; Mendoza-Salgado, Renato A; Zenteno-Savín, Tania; Arreola-Lizárraga, José A

    2016-07-01

    This study examines the potential public health risk due to the massive use of organochlorine pesticides (OCs) in agriculture in the Gulf of California. Specimens of the clam Chione californiensis were collected from three coastal lagoons (Yavaros, Altata and Reforma). Sites were classified as polluted/nonpolluted based on the presence/absence of OCs as an indicator of the persistence of these pollutants; in polluted sites, the time elapsed since pesticide application (past or recent) was estimated. Screening values (SV) for protecting human health as per the U.S. Environmental Protection Agency (EPA) were used for risk assessment. OCs detected were ranked according to frequency of occurrence as follows: γ-chlordane (75%) > endrin (54%) > aldrin (48%) > heptachlor, and dichlorodiphenyl-trichloroethane (DDE) (37%) > β-heptachlor epoxide (30%) > lindane (α-BHC, δ-BHC) and endosulphan I (≤ 6%). Specifically, OCs detected at the highest concentration were heptachlor in Yavaros (0.0168 µgg(-1)) and Altata (0.0046 µgg(-1)), and aldrin in Reforma (0.0019 µgg(-1)). β-Heptachlor epoxide in Altata and Reforma was the only OC with a concentration exceeding the EPA Screening Value. From our results and based on the monthly consumption limit set forth by EPA, the maximum safe consumption of clams to avoid a carcinogenic risk derived from β-heptachlor epoxide in the fishing villages of Yavaros and Altata is 4 servings per month (1 serving = 0.227 kg) by a 70-kg person. These findings suggest that concentrations of OCs and their isomers in C. californiensis populations reflect environmental persistence as well as recent inputs of OCs into coastal lagoons in the Gulf of California. PMID:27050678

  1. Transcriptomics of in vitro immune-stimulated hemocytes from the Manila clam Ruditapes philippinarum using high-throughput sequencing.

    Directory of Open Access Journals (Sweden)

    Rebeca Moreira

    Full Text Available BACKGROUND: The Manila clam (Ruditapes philippinarum is a worldwide cultured bivalve species with important commercial value. Diseases affecting this species can result in large economic losses. Because knowledge of the molecular mechanisms of the immune response in bivalves, especially clams, is scarce and fragmentary, we sequenced RNA from immune-stimulated R. philippinarum hemocytes by 454-pyrosequencing to identify genes involved in their immune defense against infectious diseases. METHODOLOGY AND PRINCIPAL FINDINGS: High-throughput deep sequencing of R. philippinarum using 454 pyrosequencing technology yielded 974,976 high-quality reads with an average read length of 250 bp. The reads were assembled into 51,265 contigs and the 44.7% of the translated nucleotide sequences into protein were annotated successfully. The 35 most frequently found contigs included a large number of immune-related genes, and a more detailed analysis showed the presence of putative members of several immune pathways and processes like the apoptosis, the toll like signaling pathway and the complement cascade. We have found sequences from molecules never described in bivalves before, especially in the complement pathway where almost all the components are present. CONCLUSIONS: This study represents the first transcriptome analysis using 454-pyrosequencing conducted on R. philippinarum focused on its immune system. Our results will provide a rich source of data to discover and identify new genes, which will serve as a basis for microarray construction and the study of gene expression as well as for the identification of genetic markers. The discovery of new immune sequences was very productive and resulted in a large variety of contigs that may play a role in the defense mechanisms of Ruditapes philippinarum.

  2. A preliminary study of iron isotope fractionation in marine invertebrates (chitons, Mollusca) in near-shore environments

    Science.gov (United States)

    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-10-01

    Chitons (Mollusca) are marine invertebrates that produce radulae (teeth or rasping tongues) containing high concentrations of biomineralized magnetite and other iron-bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radulae might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radulae collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00 ‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae in the sublittoral zone, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds on both green and red algae in the eulittoral zone, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Three possible pathways are proposed to account for the different isotopic signatures: (i) physiologically controlled processes within the chitons that lead to species-dependent fractionation; (ii) diet-controlled variability due to different Fe isotope fractionation in the red and green algal food sources; and (iii) environmentally controlled fractionation that causes variation in the isotopic signatures of bioavailable Fe in the different

  3. Inactivation of Vibrio cholerae O1 El Tor inoculated into Peruvian ''choro'' mussels (Aulacomya ater) and two species of clams (Argopecten purpuratus and Gari solida) using medium-dose irradiation

    International Nuclear Information System (INIS)

    The radiation decimal reduction dose (D10) for Vibrio cholerae O1 biotype El Tor inoculated through the natural feeding system into three species of bivalve mollusks from the Peruvian Pacific coast: ''choro'' mussels (Aulacome ater), ''abanico'' clams (Argopecten purpuratus), and common clams (Gari solida), was determined in vivo. The D10 value obtained in vivo was 0.14 kGy in all mollusks tested. Concurrent studies conducted to determine the potential use of irradiation to extend the microbiological shelf-life of the mollusks during post-irradiation storage at 0-1 deg. C indicated that a dose of 1.0 kGy was optimal for choro mussels and abanico clams, whereas 2.0 kGy produced the best results when treating common clams. Shelf-life extension thus achieved was 31 days for choro mussels, 16 days for abanico clams, and 21 days for common clams. Non-irradiated control samples of all mollusks spoiled after 17 days of refrigerated storage. There were no significant (p<.05) adverse effects from the application of the optimal radiation treatments on the sensory characteristics (i.e. appearance, odor, flavor, and texture) of the mollusks. Total volatile basic nitrogen (VBN) and pH values were examined for use as indexes of seafood freshness. (author)

  4. Use of the Atlantic nut clam (Nucula proxima) and catworm (Nephtys incisa) in a sentinel species approach for monitoring the health of Bay of Fundy estuaries.

    Science.gov (United States)

    Pippy, B A; Kidd, K A; Munkittrick, K R; Mercer, A; Hunt, H

    2016-05-15

    Designing an effective environmental monitoring system for population responses requires knowledge of the biology of appropriate sentinel species and baseline information on the area's physical and chemical characteristics. This study collected information in Saint John Harbor, NB, Canada, for two abundant marine benthic invertebrates, the Atlantic nut clam (Nucula proxima) and the catworm (Nephtys incisa) to characterize their seasonal and spatial variability, determine the ideal sampling time and methods, and develop baseline data for future studies. We also evaluated whether contamination is impacting invertebrates by comparing sediment metal concentrations to responses of benthic infauna. Metals were generally below sediment quality guidelines except for nickel and arsenic. Clam densities were variable between sites but not seasons, whereas catworm densities were not significantly different between sites or seasons. Overall, these species show potential for environmental monitoring, although investigation at more contaminated sites is warranted to assess their sensitivity. PMID:26994836

  5. Phytoplankton growth balanced by clam and zooplankton grazing and net transport into the low-salinity zone of the San Francisco Estuary

    Science.gov (United States)

    Kimmerer, Wim J.; Thompson, Janet K.

    2014-01-01

    We estimated the influence of planktonic and benthic grazing on phytoplankton in the strongly tidal, river-dominated northern San Francisco Estuary using data from an intensive study of the low salinity foodweb in 2006–2008 supplemented with long-term monitoring data. A drop in chlorophyll concentration in 1987 had previously been linked to grazing by the introduced clam Potamocorbula amurensis, but numerous changes in the estuary may be linked to the continued low chlorophyll. We asked whether phytoplankton continued to be suppressed by grazing and what proportion of the grazing was by benthic bivalves. A mass balance of phytoplankton biomass included estimates of primary production and grazing by microzooplankton, mesozooplankton, and clams. Grazing persistently exceeded net phytoplankton growth especially for larger cells, and grazing by microzooplankton often exceeded that by clams. A subsidy of phytoplankton from other regions roughly balanced the excess of grazing over growth. Thus, the influence of bivalve grazing on phytoplankton biomass can be understood only in the context of limits on phytoplankton growth, total grazing, and transport.

  6. Freshwater Clam Extract Ameliorates Triglyceride and Cholesterol Metabolism through the Expression of Genes Involved in Hepatic Lipogenesis and Cholesterol Degradation in Rats

    Directory of Open Access Journals (Sweden)

    Thomas Laurent

    2013-01-01

    Full Text Available The freshwater clam (Corbicula spp. is a popular edible bivalve and has been used as a folk remedy for liver disease in Asia. As a Chinese traditional medicine, it is said that freshwater clam ameliorates alcoholic intoxication and cholestasis. In this study, to estimate the practical benefit of freshwater clam extract (FCE, we compared the effects of FCE and soy protein isolate (SPI on triglyceride and cholesterol metabolism in rats. FCE and SPI lowered serum cholesterol, and FCE tended to reduce serum triglycerides. FCE enhanced fecal sterol excretion and hepatic mRNA levels of CYP7A1 and ABCG5 more substantially than SPI; however, both diets reduced hepatic cholesterol. Both of the diets similarly suppressed liver lipids improved Δ9-desaturated fatty acid profile, and FCE was associated with a reduction in FAS and SCD1 mRNA levels. Hepatic transcriptome analysis revealed that inhibition of lipogenesis-related gene expression may contribute to downregulation of hepatic triglycerides by FCE. FCE would have better potential benefits for preventing metabolic disorders, through greater improvement of metabolism of triglycerides and cholesterol, likely through a mechanism similar to SPI.

  7. Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

    Energy Technology Data Exchange (ETDEWEB)

    Ivanina, Anna V. [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Beniash, Elia [Department of Oral Biology, University of Pittsburgh, 589 Salk Hall, 3501 Terrace Street, Pittsburgh, PA 15261 (United States); Etzkorn, Markus; Meyers, Tiffany B. [Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Ringwood, Amy H. [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Sokolova, Inna M., E-mail: isokolov@uncc.edu [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States)

    2013-09-15

    Highlights: •P{sub CO{sub 2}} alters accumulation of Cd and Cu in clam cells. •Accumulation of Cd induces release of free Zn{sup 2+}. •Accumulation of Cu induces an increase in free Cu{sup 2+} and Fe{sup 2+}. •Metal-induced oxidative stress is alleviated at high P{sub CO{sub 2}}. •Toxicity of Cu in likely enhanced while that of Cd alleviated by high P{sub CO{sub 2}}. -- Abstract: Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO{sub 2} (P{sub CO{sub 2}}) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high P{sub CO{sub 2}} (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between P{sub CO{sub 2}} and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of P{sub CO{sub 2}} (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated P{sub CO{sub 2}} resulted in a decrease in intracellular pH (pH{sub i}) of the isolated mantle cells from 7.8 to 7.4. Elevated P{sub CO{sub 2}} significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated P{sub CO{sub 2}} levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd{sup 2+} concentration remained the same, while intracellular levels of free Zn{sup 2+} increased suggesting that Cd{sup 2+} substitutes bound Zn{sup 2

  8. Scorched mussels (BIVALVIA: MYTILIDAE: BRACHIDONTINAE) from the temperate coasts of South America: phylogenetic relationships, trans-Pacific connections and the footprints of Quaternary glaciations.

    Science.gov (United States)

    Trovant, Berenice; Orensanz, J M Lobo; Ruzzante, Daniel E; Stotz, Wolfgang; Basso, Néstor G

    2015-01-01

    This study addresses aspects of the phylogeny and phylogeography of scorched mussels (BIVALVIA: MYTILIDAE: BRACHIDONTINAE) from southern South America (Argentina and Chile), as well as their ecophylogenetic implications. Relationships were inferred from sequences of two nuclear (28S and 18S) and one mitochondrial (COI) genes, using Bayesian and maximum likelihood analyses. Our results indicate that the monophyletic BRACHIDONTINAE include three well supported clades: [i] Brachidontes Swainson (=Hormomya Mörch), [ii] Ischadium Jukes-Browne+Geukensia van de Poel, and [iii] Austromytilus Laseron+Mytilisepta Habe (usually considered a member of the SEPTIFERINAE)+Perumytilus Olsson. Species of clade [iii] are distributed along the temperate coasts of the Pacific Ocean. Available evidence supports divergence between Austromytilus (Australia) and Perumytilus (South American) following the breakup of Australian, Antarctic and South American shelves. Four brachidontins occur in southern South America: Brachidontes rodriguezii (d'Orbigny), B. granulatus (Hanley), and two genetically distinct clades of Perumytilus. The latter are confined to the Chile-Peru (North Clade) and Magellanic (South Clade) Biogeographic Provinces, respectively warm- and cold-temperate. The South Clade is the only brachidontin restricted to cold-temperate waters. Biogeographic considerations and the fossil record prompted the hypothesis that the South Clade originated from the North Clade by incipient peripatric differentiation, followed by isolation during the Quaternary glaciations, genetic differentiation in the non-glaciated coasts of eastern Patagonia, back-expansion over southern Chile following post-LGM de-glaciation, and development of a secondary contact zone between the two clades in south-central Chile. Evidence of upper Pleistocene expansion of the South Clade parallels similar results on other organisms that have colonized coastal ecosystems from eastern Patagonia since the LGM

  9. GENETIC DIVERSITY OF FIVE FRESHWATER MUSSELS IN GENUS ANODONTA (MOLLUSCA: BIVALVIA ) REVEALED BY RAPD ANALYSIS%通过RAPD分析揭示五种淡水无齿蚌(软体动物门:双壳类)的遗传多样性

    Institute of Scientific and Technical Information of China (English)

    WEI Kai-Jian; XIONG Bang-Xi; ZHANG Gui-Rong

    2006-01-01

    Unionidae are an important group of benthic freshwater species. Due to the convergence phenomenon within freshwater mussels, there is still much controversy in the classification of Chinese Unionidae. In China, most studies on freshwater mussels emphasized resource investigation, biology and morphology, while little has been done in genetics, and particularly not in population genetic structure as well as genetic diversity. In order to further understand the status of genetic diversity of different species,random amplified polymorphic DNA (RAPD) markers were used to detect genetic diversity of populations in five species of the genus Anodonta : Anodonta arcaeformis , A . arcaeformis flavotincta , A .fluminea , A . woodiana woodiana and A . w . pacifica .DNA extraction method was based on phenol-chloroform and extracted genomic DNA from the adductor muscle and mantle tissues.Sixteen random primers were used for RAPD amplification and the polymorphism of amplified loci were analyzed. The results demonstrated that the percentage of amplified polymorphic loci for various populations ranged from 34.5% to 62.8%, the mean Shannon' s genetic diversity indices ranged from 0. 2021 to 0. 3552, and the mean intra-population Nei's genetic distance ranged from 0. 1386 to 0. 1713. In all populations of the five species, the genetic diversity for A. arcaeformis was the largest, and that of A. fluminea was the lowest. The inter-population genetic distance between A. w. woodiana and A. w. pacifica was 0.3186,so they can be considered as two sister species at the genetic angle.

  10. COI-based DNA Barcoding in Tapetinae Species (Mollusca, Bivalvia, Veneridae) Along the Coast of CHINA%基于COI序列的DNA条形码在中国沿海缀锦蛤亚科贝类中的应用分析

    Institute of Scientific and Technical Information of China (English)

    陈军; 李琪; 孔令锋; 郑小东; 于瑞海

    2010-01-01

    该研究探讨了将COI序列应用于中国沿海缀锦蛤亚科贝类物种鉴定的可行性,获得了该亚科5属11种贝类51个个体的43个单倍型序列.碱幕替换饱和性分析表明,颠换未出现饱和现象,而转换在序列分化达到10%至15%时即到达饱和.单倍犁Hap33可能是由杂交引起的,排除此瞥倍型,种内个体间遗传距离在0%到2.02%之间,平均为0.46%,属内不同种个体间遗传距离在17.21%~32.24%之间,平均为24.96%,存在条形码问隙:11种缀锦蛤哑科贝类在邻接树和贝叶斯树上都独立的单系群.该研究表明,基于COI的DNA条形码技术能够将研究所涉及的约98%的缀锦蛤亚科贝类鉴定剑种的水平,因此,利用DNA条形码技术可以对缀锦蛤亚科贝类进行有效地分类鉴定.

  11. Early stage morphogenesis: an approach to problems of taxonomy, phylogeny and evolution in the Mytilidae (Mollusca: Bivalvia)%早期形态发生:一种解决贻贝科(软体动物门:双壳纲)分类、系统发育和进化问题的方法

    Institute of Scientific and Technical Information of China (English)

    George A. EVSEEV; Olga Ya. SEMENIKHINA; Natalya K. KOLOTUKHINA

    2005-01-01

    Sequence of appearance and transformations of morphological structures during larval and juvenile mytilids life histories have been examined. Ontogenies of about 60 taxa were typified into 4 morphogenetic patterns, or modes. Origin, developmental changes and homologies of the stage morphostructures were considered according to their location in three morphogenetic fields. The first, or central, field forms at the prodissoconch Ⅰ stage (PD-Ⅰ). It can be inherited by prodissoconch Ⅱ (PD-Ⅱ) and nepioconch (N) stages in one taxa, or PD-Ⅱ, N and dissoconch (D) stages in others. The second, or postero-dorsal, field appears at the N stage, and the third field, or antero-dorsal, at the D stage. The postero-dorsal field of the stage D inherits the N-morphostructures in one taxa, or D-stage in others. Central and postero-dorsal field morphostructures exhibit developmental sequences, or a system of characters which possess polarity, in contrast to adult characters applied in mytilid taxonomy. Based on early stage morphological characters of and well-known features studied previously but not used in taxonomy and phylogeny, a revaluation Soot-Ryen's system of supraspecific taxa and reconstruction of phylogenetic relationships among the Recent Mytilidae have been attempted. In the presented scheme, the subfamilies of Scarlato and Starobogatov (1984) form four phylogenetic lines beginning with the Modiolinae.%作者对贻贝科贝类的幼虫和幼贝期发育阶段形态结构的出现和变化顺序进行了研究,其约60个不同分类单元的个体发生可归纳为4种形态发生类型或模式.主要对3个形态发生区域的阶段形态结构的起源、发育变化和同源性做了研究.其一,即中央区域,开始形成于前双壳Ⅰ期(PD-Ⅰ),在某个分类单元它可以在前双壳Ⅱ期(PD-Ⅱ)和幼贝期(N)形成,而在其它分类单元则在前双壳Ⅱ期、幼贝期和双壳期(D)形成;第二区域,即背部后区,在幼贝期出现;第三区域,即背部前区,出现于双壳期.双壳期背部后区在某个分类单元起源于幼贝期的形态构造,在其它分类单元则可能起源于双壳期的形态构造.与在贻贝分类学上应用的成体特征相比,早期发育阶段中央和背部后区的形态结构显示出很明显的发育顺序或特征变化规律.根据以前人们熟知而尚未应用到分类和系统发育研究中的早期发育阶段形态特征,作者重新修订了Soot-Ryen的现生贻贝科种上阶元分类系统,重新提出了科内系统发育关系.修订的分类系统表明,Scarlato and Starobogatov (1984)提出的贻贝科各亚科由偏顶蛤亚科开始,沿4条系统发育路线演化发展,对应其早期发育阶段的4类形态发生类型或模式.

  12. 基于线粒体细胞色素c氧化酶亚基I基因序列的帘蛤科贝类分子系统发育研究%Phylogenetic analysis of Veneridae (Mollusca: Bivalvia) based on the mitochondrial cytochrome c oxidase subunit I gene fragment

    Institute of Scientific and Technical Information of China (English)

    程汉良; 彭永兴; 董志国; 易乐飞; 孟学平; 申欣; 周旻纯; 陈冬勤

    2013-01-01

    对21种帘蛤科贝类线粒体细胞色素c氧化酶亚基I(cytochrome c oxidase subunit I,COI)基因核苷酸序列进行了分析,以探讨这一序列在种质鉴定、分子系统发生研究中的应用价值.测序结果表明,所有物种扩增片段长度均为707 bp(含引物),序列A+T含量(62.4%-67.8%)明显高于G+C含量.物种间共有变异位点379个,其中简约信息位点334个;此区段共编码235个氨基酸,种间共有氨基酸变异位点100个.以COI基因片段序列为标记,用中国蛤蜊(Mactra chinensis)作外群,构建了35种帘蛤科贝类(其中14种贝类COI序列从GenBank下载)的系统发生树,结合拓扑结构分析和序列比对分析,结果表明:支持将短文蛤(Meretrix petechinalis)和丽文蛤(M.lusoria)订为文蛤(M.meretrix)的同物异名的观点,建议将丽文蛤和短文蛤订为文蛤的地理亚种;支持将薄片镜蛤(Dosinia corrugata)和D.angulosa订为2个独立种的观点;认为将波纹巴非蛤(Paphia undulata)和织锦巴非蛤(P.textile)订为2个独立种是合适的.COI基因序列含有丰富的遗传信息,适合作为帘蛤科贝类种群遗传结构和系统发生研究的分子标记.

  13. Sequence Analysis on Mitochondrial 16S Rrna Gene Fragments and ITS2 Loci in Three Species of Mactradae (Mollusca: Bivalvia)%蛤蜊科3种贝类16SrRNA基因片段及ITS2核苷酸序列分析

    Institute of Scientific and Technical Information of China (English)

    孟学平; 高如承; 董志国; 阎斌伦; 程汉良; 李艳杰; 陈建安

    2006-01-01

    利用PCR技术分别扩增连云港及启东沿海蛤蜊科的西施舌(Coelomactra antiquata)、中国蛤蜊(Mactra chinensis)和四角蛤蜊(Mactra veneriformis)3种双壳贝的16S rRNA基因片段和ITS2核苷酸序列,测序后用DNA star软件分析了核苷酸差异.结果显示:三种贝类16S rRNA基因片段长度相同,均为306bp(去除引物),核苷酸存在多态性,共有45个变异位点,54个核苷酸发生了变异,全部为碱基置换.西施舌与中国蛤蜊此片段核苷酸的同源性为88.9%,与四角蛤蜊的同源性为88.6%,中国蛤蜊与四角蛤蜊的同源性为90.6%.三种蛤蜊ITS2序列分别为390 bp(西施舌)、441 bp(四角蛤蜊)和466 bp(中国蛤蜊),存在长度多态性,ITS2核苷酸差异分析结果显示,西施舌与中国蛤蜊的同源性为70.9%-71.1 %,西施舌与四角蛤蜊的为70.5%-71.0 %,中国蛤蜊与四角蛤蜊的同源性为88.1%-88.8%.ITS2序列分析结果与16S rRNA基因片段分析结果一致,2种分子分析法均显示中国蛤蜊与四角蛤蜊的亲缘关系近.

  14. MOLECULAR PHYLOGENY OF MERETRIX(MOLLUSCA, BIVALVIA)BASED ON 16S rRNA GENES AND ITS1 SEQUENCES%文蛤属(Meretrix)16S rRna基因及ITS1序列的系统学分析

    Institute of Scientific and Technical Information of China (English)

    潘宝平; 吴琪; 张素萍; 宋林生; 卜文俊

    2006-01-01

    利用线粒体16S rRNA基因片段及核糖体DNA转录间隔区ITS1序列分析的方法,以近缘属的青蛤(Cyclina sinensis)为外群,对文蛤属的文蛤(M.meretrix)、丽文蛤(M.lusoria)、帘文蛤(M.lyrata)和斧文蛤(M.lamarckii)4种贝类进行了系统学研究.经ClustalX多重比对及DNAsp软件分析后,用PAUP4.0分析软件,计算出种间序列的碱基转换/颠换频率,利用邻接法NJ构建系统发育树.结果表明,帘文蛤与该属其他三种的分歧时间较早,两类序列与其他种类间的相对遗传距离分别在0.25866-0.28218和0.15644-0.20104之间.文蛤与丽文蛤间的16S rDNA及ITS1序列间的遗传距离仅为0.04805和0.04201,拓扑结构图显示关系很近,并且二者的分布区大面积重叠,其序列间的转换/颠换频率接近种内单元型(haplotype)间的序列变化,鉴于它们的贝壳形态有一定差别,应归为同一个种内的不同地理亚种比较恰当.

  15. Fine-scale spatial distribution of the common lugworm Arenicola marina, and effects of intertidal clam fishing

    Science.gov (United States)

    Boldina, Inna; Beninger, Peter G.

    2014-04-01

    Despite its ubiquity and its role as an ecosystem engineer on temperate intertidal mudflats, little is known of the spatial ecology of the lugworm Arenicola marina. We estimated lugworm densities and analyzed the spatial distribution of A. marina on a French Atlantic mudflat subjected to long-term clam digging activities, and compared these to a nearby pristine reference mudflat, using a combination of geostatistical techniques: point-pattern analysis, autocorrelation, and wavelet analysis. Lugworm densities were an order of magnitude greater at the reference site. Although A. marina showed an aggregative spatial distribution at both sites, the characteristics and intensity of aggregation differed markedly between sites. The reference site showed an inhibition process (regular distribution) at distances marina was clearly aggregated at both sites; however, the autocorrelation strength was much weaker at the impacted site. In addition, the non-impacted site presented multi-scale spatial distribution, which was not evident at the impacted site. The differences observed between the spatial distributions of the fishing-impacted vs. the non-impacted site reflect similar findings for other components of these two mudflat ecosystems, suggesting common community-level responses to prolonged mechanical perturbation: a decrease in naturally-occurring aggregation. This change may have consequences for basic biological characteristics such as reproduction, recruitment, growth, and feeding.

  16. Combining ability and heterosis analysis over two environments in a diallel cross of three families of the clam Meretrix meretrix

    Institute of Scientific and Technical Information of China (English)

    DAI Ping; WANG Hongxia; XIAO Guoqiang; LIU Baozhong

    2014-01-01

    A 3×3 complete diallel cross comprising three families of the clam Meretrix meretrix (P1, P2 and P3) was used to determine the combining ability of parental families and heterosis of F1 under indoor and open-air environments for growth traits. Analysis of variance for shell length and whole body weight indicated highly significant cross effects, environment effects and the interaction of cross by environment. General combining ability (GCA) and specific combing ability exhibited great variation among crosses and between two environments. Pooled over environments, P2 was the top combiner among the three parental families for both traits studied. The cross of P1 and P3 had the highest SCA. Additionally, significant reciprocal effects were observed. For individual environment, about half of the crossbred combinations showed favorable Mid-parent heterosis (MPH) (>1%) for the shell length and whole body weight. Our data has shown that non-additive genetic and reciprocal effects constituted the major sources of genetic variation for both shell length and whole body weight, which indicates that crossbreeding among selective families could further explore the heterotic effects.

  17. Kistimonas scapharcae sp. nov., isolated from a dead ark clam (Scapharca broughtonii), and emended description of the genus Kistimonas.

    Science.gov (United States)

    Lee, Jina; Shin, Na-Ri; Lee, Hae-Won; Roh, Seong Woon; Kim, Min-Soo; Kim, Young-Ok; Bae, Jin-Woo

    2012-12-01

    A Gram-negative, motile, facultatively anaerobic rod, designated A36(T), was isolated from a dead ark clam found on the south coast of Korea. The isolate was catalase- and oxidase-negative. 16S rRNA gene sequence analysis indicated that strain A36(T) was most closely related to Kistimonas asteriae KMD 001(T), with which it shared 98.2% 16S rRNA gene sequence similarity. Strain A36(T) grew optimally at 30-37 °C, with 1% (w/v) NaCl and at pH 8.0. The major respiratory quinone was ubiquinone-9 (Q-9). The major polar lipids were phosphatidylserine, phosphoethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were summed feature 3 (comprising C(16:1)ω7c and/or iso-C(15) 2-OH) and C(16:0). The genomic DNA G+C content was 47.3 mol%. DNA-DNA relatedness between the isolate and K. asteriae JCM 15607(T) was <25 ± 3%. Strain A36(T) represents a novel species of the genus Kistimonas, for which the name Kistimonas scapharcae sp. nov. is proposed. The type strain is A36(T) ( = KACC 16204(T)  = JCM 17805(T)). An emended description of the genus Kistimonas is also provided.

  18. Neptunomonas concharum sp. nov., isolated from a dead ark clam, and emended description of the genus Neptunomonas.

    Science.gov (United States)

    Lee, Hae-Won; Shin, Na-Ri; Lee, Jina; Roh, Seong Woon; Whon, Tae Woong; Bae, Jin-Woo

    2012-11-01

    A novel Gram-staining-negative, facultatively anaerobic, motile and rod-shaped bacterium, designated strain LHW37(T), was isolated from a dead ark clam collected on the south coast of Korea. The novel strain grew optimally at 37 °C, at pH 7.0-8.0 and with 2% (w/v) NaCl. The predominant cellular fatty acids were C(18:1)ω7c and summed feature 3 (C(16:1)ω7c and/or iso-C(15:0) 2-OH). The major isoprenoid quinone was ubiquinone-8 (Q-8) and the predominant polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel strain was most closely related to Neptunomonas japonica JAMM 0745(T) (97.1% sequence similarity). The genomic DNA G+C content of strain LHW37(T) was 48.2 mol%. The DNA-DNA relatedness values recorded in hybridization experiments between the novel strain and its closest known relative were ≤ 18%. Based on the phenotypic, genotypic and phylogenetic data, strain LHW37(T) represents a novel species belonging to the genus Neptunomonas for which the name Neptunomonas concharum sp. nov. is proposed. The type strain is LHW37(T) (=KACC 15543(T) =JCM 17730(T)). An emended description of the genus Neptunomonas is also provided.

  19. Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingsheng, E-mail: chunjing.li@fds.org.cn; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

    2013-11-15

    In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

  20. Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel

    Science.gov (United States)

    Wu, Qingsheng; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

    2013-11-01

    In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

  1. Effects of ocean acidification driven by elevated CO2 on larval shell growth and abnormal rates of the venerid clam, Mactra veneriformis

    Science.gov (United States)

    Kim, Jee-Hoon; Yu, Ok Hwan; Yang, Eun Jin; Kang, Sung-Ho; Kim, Won; Choy, Eun Jung

    2016-03-01

    The venerid clam (Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO2-enriched air at (400±25)×10-6 (ambient control), (800±25)×10-6 (high pCO2), or (1 200±28)×10-6 (extremely high pCO2), the atmospheric CO2 concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO2 conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.

  2. Study on Enzymatic Hydrolysis of Clam Adductor Muscle%文蛤闭壳肌酶法水解工艺研究

    Institute of Scientific and Technical Information of China (English)

    姚宏亮; 颜玉华; 杨勇胜; 李宏丽; 陈娟

    2012-01-01

    [Objective] To explore the best enzymatic hydrolysis conditions of clam adductor muscle. [Method] An orthogonal experiment with three factors of papain amount, temperature and pH at three levels was designed to hydrolyze the clam adductor muscle. [ Result] With the hydrolysis rate as index, the influential degree of each factor on the enzymatic hydrolysis decreased in the order of papain amount > pH > temperature. Under the best hydrolysis conditions of 8 000 U/g papain amount, 5.5 pH and 50 ℃ temperature, the hydrolysis rate was 32.4%. [Conclusion ] The study provided scientific basis for the comprehensive utilization of clam adductor muscle.%[目的]探讨文蛤闭壳肌酶法水解蛋白液制备的最佳工艺.[方法]以加酶量(木瓜蛋白酶)、pH、温度为因素采取3因素3水平的设计方法对文蛤闭壳肌进行水解.[结果]以水解率为指标,得到各因素对文蛤闭壳肌酶法水解影响的大小顺序为加酶量>pH>温度.最佳水解工艺条件为加酶量8 000 U/g原料,pH 5.5,温度50℃,优化方案的水解率为32.4%.[结论]研究为文蛤闭壳肌的综合利用提供了一定的科学依据.

  3. Studies on the Odour of Canned Fish (Part 6) : Volatile Basic Components in the Canned Edible Portion of Short-neck Clam, Tapes japonica

    OpenAIRE

    Shigenobu, OOYAMA

    1981-01-01

    The edible portion of short-neck clam was put up in cans and stored for two months at room temperature. The volatile basic fraction in the canned contents was obtained by a steam distillation method. Volatile bases in the fraction were extracted with ethyl ether, and then the ether extract was analyzed by gas chromatography as well as paper chromatography. The results obtained are as follows, 1. Ammonia and n-propylamine were detected in the ether extract by gas chromatography. Peak area of n...

  4. From water to land: How an invasive clam may function as a resource pulse to terrestrial invertebrates.

    Science.gov (United States)

    Novais, Adriana; Souza, Allan T; Ilarri, Martina; Pascoal, Cláudia; Sousa, Ronaldo

    2015-12-15

    Resource pulses are episodes of low frequency, large magnitude and short duration that result in increased resource availability in space and time, with consequences for food web dynamics. Studies assessing the importance of resource pulses by invasive alien species in the interface between terrestrial and aquatic ecosystems are rare, especially those in the direction from water to land. This study assessed the importance of massive die-offs of the Asian clam Corbicula fluminea (Müller, 1774) as a resource pulse to the terrestrial invertebrate community after an extreme climatic event using a manipulative experiment. We used 5 levels of C. fluminea density (0, 100, 500, 1000 and 2000ind·m(-2)), with terrestrial invertebrates being censused 7, 30 and 90days after C. fluminea addition. We also assessed the possible effect of plots position, where plots that delimited the experiment were assigned as edge plots and the remaining as core plots. Clear differences were detected in abundance, biomass, richness and diversity of terrestrial invertebrates depending on the C. fluminea density, time and position. Interestingly, the highest abundance of adult Diptera was observed 7days after C. fluminea addition, whereas that of the other terrestrial invertebrates was on day 30, both with C. fluminea densities higher than 500ind·m(-2) located on the edge of the experimental design. This study highlights the importance of major resource pulses after massive die-offs of invasive bivalves, contributing with remarkable amounts of carrion for adjacent terrestrial systems. Part of this carrion can be consumed directly by a great number of invertebrate species while the remainder can enter the detrital food web. Given the high density and biomass attained by several invasive bivalves worldwide and the predicted increase in the number, intensity and magnitude of extreme climatic events, the ecological importance of this phenomenon should be further investigated. PMID:26327634

  5. Heavy metals in oysters, mussels and clams collected from coastal sites along the Pearl River Delta, South China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Concentrations of 8 heavy metals: cadmium (Cd), copper(Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony(Sb) and tin (Sn) were examined in 3 species of bivalves (Pernaviridis, Crassostrea rivularis and Ruditapes philippinarum)collected from 25 sites along the Pearl River Delta coastal watersin the South China Sea from July to August 1996. In general, Cd,Cu, Zn and Sn concentrations in the three bivalve species collectedfrom the Estuarine Zone were significantly higher than thosecollected from the Western and Eastern Zones of the Pearl RiverDelta, which are related to the existence of various anthropogenicactivities in the catchment of the Pearl River Delta. The WesternEstuarine Zone is mainly impacted by Cr, Ni and Cu contamination.In Victoria Harbor, heavy metal contamination is mainly due to Cuand Pb. Cd, Cu and Zn concentrations in oysters were significantlyhigher than those in mussels and clams. This could be explained bythe fact that oysters live mainly in the Estuarine Zone of thePearl River Delta which receives most of the polluting dischargesfrom the catchment of the Delta. During turbid condition, heavymetals (soluble or adsorbed on suspended particulates) dischargedfrom the Delta are filtered from the water column and subsequentlyaccumulated into the soft body tissues of oysters. Heavy metalconcentrations in the three bivalve species were compared with themaximum permissible levels of heavy metals in seafood regulated bythe Public Health and Municipal Services Ordinance, Laws of HongKong, and it was revealed that Cd and Cr concentrations in thethree bivalve species exceeded the upper limits. At certainhotspots in the Delta, the maximum acceptable daily load for Cd wasalso exceeded.

  6. A microarray-based analysis of gametogenesis in two Portuguese populations of the European clam Ruditapes decussatus.

    Directory of Open Access Journals (Sweden)

    Joana Teixeira de Sousa

    Full Text Available The European clam, Ruditapes decussatus is a species with a high commercial importance in Portugal and other Southern European countries. Its production is almost exclusively based on natural recruitment, which is subject to high annual fluctuations. Increased knowledge of the natural reproductive cycle of R. decussatus and its molecular mechanisms would be particularly important in providing new highly valuable genomic information for better understanding the regulation of reproduction in this economically important aquaculture species. In this study, the transcriptomic bases of R. decussatus reproduction have been analysed using a custom oligonucleotide microarray representing 51,678 assembled contigs. Microarray analyses were performed in four gonadal maturation stages from two different Portuguese wild populations, characterized by different responses to spawning induction when used as progenitors in hatchery. A comparison between the two populations elucidated a specific pathway involved in the recognition signals and binding between the oocyte and components of the sperm plasma membrane. We suggest that this pathway can explain part of the differences in terms of spawning induction success between the two populations. In addition, sexes and reproductive stages were compared and a correlation between mRNA levels and gonadal area was investigated. The lists of differentially expressed genes revealed that sex explains most of the variance in gonadal gene expression. Additionally, genes like Foxl2, vitellogenin, condensing 2, mitotic apparatus protein p62, Cep57, sperm associated antigens 6, 16 and 17, motile sperm domain containing protein 2, sperm surface protein Sp17, sperm flagellar proteins 1 and 2 and dpy-30, were identified as being correlated with the gonad area and therefore supposedly with the number and/or the size of the gametes produced.

  7. Cadmium contamination of three bivalve species (oysters, cockles and clams) in Nord Médoc salt marshes (Gironde estuary, France): Geochemical survey and metal bioaccumulation kinetics

    Science.gov (United States)

    Baudrimont, M.; Schäfer, J.; Marie, V.; Maury-Brachet, R.; Bossy, C.; Durrieu, G.; Palvadeau, A.; Maneux, E.; Boudou, A.; Blanc, G.

    2003-05-01

    A historical Cd pollution of the Lot-Garonne River system (France) bas led to the contamination of sediment and water of the Gironde Estuary. In spite of the decrease of fluvial Cd inputs since the early 90ies, Cd concentrations in the Gironde oysters remain higher than European norms (5 μg.g^{-1} dry mass) and the “zone D” classification of the estuary prohibits bivalve production and harvesting for human consumption. A geochemical survey in salt marshes used for aquaculture (crustaceans) has been conducted in order to assess the heavy métal contamination level in these systems periodically alimented by the Gironde water, accompanied by caging experiments on three bivalve species of economical interest: oysters (Crassostrea gigas), cockles (Cerastoderma edule) and clams (Ruditapes philippinarum) to study heavy metal accumulation in these organisms. Distribution of heavy metals in this system is controlled by biogeochemical processes and is independent of routine water management. Contamination levels in the studied species indicate the high accumulation of Cd by oysters. On the other hand, Cd concentrations in benthic species, such as cockles and clams, are clearly lower than European safety limits for human consumption.

  8. Effects of freshwater clam extract supplementation on time to exhaustion, muscle damage, pro/anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise.

    Science.gov (United States)

    Huang, Kuo-Chin; Wu, Wen-Tien; Yang, Fwu-Lin; Chiu, Yi-Han; Peng, Tai-Chu; Hsu, Bang-Gee; Liao, Kuang-Wen; Lee, Ru-Ping

    2013-01-01

    The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea) have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE) supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC); SC group with FCE supplementation (SC+FCE); exhaustive exercise (E); and E group with FCE supplementation (E+FCE). The SC+FCE and E+FCE groups were treated with gavage administration of 20 mg/kg for seven consecutive days. Blood samples were collected for the evaluation of biochemical parameters. The cytokine levels of TNF-α and IL-10 were also examined. Twenty-four hours after exhaustive exercise, the rat livers were removed for H & E staining. The FCE supplementation could extend the time to exhaustion in exercised rats. The levels of CPK, LDH, AST, ALT, lactate, TNF-α and H & E stains of the liver injury were significantly decreased in the E+FCE group, but the blood glucose and IL-10 were significantly higher in comparison with the E group. This study suggests that FCE supplementation may improve endurance performance and reduce exercise-induced muscle damage, inflammatory stress and liver injury. PMID:23531600

  9. High resolution oxygen isotope and grayscale records of a medieval fossil giant clam(Tridacna gigas) in the South China Sea:physiological and paleoclimatic implications

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; WANG Yuhong; SUN Liguang

    2014-01-01

    Mollusks are well known for their detailed recording of paleoenvironmental and paleoclimatic changes in their carbonate shells. In this study, we constructed 18-year blue color intensity and oxygen isotope profiles of a14C dated (AD 990±40) fossil giant clam,Tridacna gigas, from Shidao Island, South China Sea. Theδ18O profile of theT. gigas specimen displayed regular annual cycles and was probably controlled by seasonal variations of the climatic parameters. The blue color intensity profile showed good agreement with theδ18O series, and both had 18 clear annual cycles in accordance with the 18 visually identified annual growth bands. The annual shell growth rate determined from the blue color intensity and oxygen isotope profiles indicated that the annual shell increment of theTridacna specimen was stable after the onset of sexual ma-turity. Spectral analysis of theδ18O and blue color intensity time series suggested that the El Niño-Southern Oscillation (ENSO) period observed in the instrumental temperature and precipitation records of the South China Sea during the past 50 years also existed in medieval times. Our results showed that fossil giant clams could provide a good archive of historical intra-seasonal to decadal climate variations.

  10. Effects of Freshwater Clam Extract Supplementation on Time to Exhaustion, Muscle Damage, Pro/Anti-Inflammatory Cytokines, and Liver Injury in Rats after Exhaustive Exercise

    Directory of Open Access Journals (Sweden)

    Kuang-Wen Liao

    2013-03-01

    Full Text Available The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC; SC group with FCE supplementation (SC+FCE; exhaustive exercise (E; and E group with FCE supplementation (E+FCE. The SC+FCE and E+FCE groups were treated with gavage administration of 20 mg/kg for seven consecutive days. Blood samples were collected for the evaluation of biochemical parameters. The cytokine levels of TNF-α and IL-10 were also examined. Twenty-four hours after exhaustive exercise, the rat livers were removed for H & E staining. The FCE supplementation could extend the time to exhaustion in exercised rats. The levels of CPK, LDH, AST, ALT, lactate, TNF-α and H & E stains of the liver injury were significantly decreased in the E+FCE group, but the blood glucose and IL-10 were significantly higher in comparison with the E group. This study suggests that FCE supplementation may improve endurance performance and reduce exercise-induced muscle damage, inflammatory stress and liver injury.

  11. Seasonal variation of biochemical components in clam ( Saxidomus purpuratus Sowerby 1852) in relation to its reproductive cycle and the environmental condition of Sanggou Bay, China

    Science.gov (United States)

    Bi, Jinhong; Li, Qi; Zhang, Xinjun; Zhang, Zhixin; Tian, Jinling; Xu, Yushan; Liu, Wenguang

    2016-04-01

    Seasonal variation of biochemical components in clam ( Saxidomus purpuratus Sowerby 1852) was investigated from March 2012 to February 2013 in relation to environmental condition of Sanggou Bay and the reproductive cycle of clam. According to the histological analysis, the reproductive cycle of S. purpuratus includes two distinctive phases: a total spent and inactive stage from November to January, and a gametogenesis stage, including ripeness and spawning, during the rest of the year. Gametes were generated at a low temperature (2.1°C) in February. Spawning took place once a year from June to October. The massive spawning occurred in August when the highest water temperature and chlorophyll a level could be observed. The key biochemical components (glycogen, protein and lipid) in five tissues (gonad, foot, mantle, siphon and adductor muscle) were analyzed. The glycogen content was high before gametogenesis, and decreased significantly during the gonad development in the gonad, mantle and foot of both females and males, suggesting that glycogen was an important energy source for gonad development. The protein and lipid contents increased in the ovary during the gonad development, demonstrating that they are the major organic components of oocytes. The lipid and protein contents decreased in the testis, implying that they can provide energy and material for spermatogenesis. The results also showed that protein stored in the mantle and foot could support the reproduction after the glycogen was depleted.

  12. Mg-isotopic fractionation in the manila clam (Ruditapes philippinarum): New insights into Mg incorporation pathway and calcification process of bivalves

    Science.gov (United States)

    Planchon, Frédéric; Poulain, Céline; Langlet, Denis; Paulet, Yves-Marie; André, Luc

    2013-11-01

    We estimate the magnesium stable isotopic composition (δ26Mg) of the major compartments involved in the biomineralisation process of euryhaline bivalve, the manila clam Ruditapes philippinarum. Our aim is to identify the fractionation processes associated with Mg uptake and its cycling/transport in the bivalve organism, in order to better assess the controlling factors of the Mg isotopic records in bivalve shells. δ26Mg were determined in seawater, in hemolymph, extrapallial fluid (EPF), soft tissues and aragonitic shell of adult clams collected along the Auray River estuary (Gulf of Morbihan, France) at two sites showing contrasted salinity regimes. The large overall δ26Mg variations (4.16‰) demonstrate that significant mass-dependent Mg isotopic fractionations occur during Mg transfer from seawater to the aragonitic shell. Soft tissues span a range of fractionation factors relative to seawater (Δ26Mgsoft tissue-seawater) of 0.42 ± 0.12‰ to 0.76 ± 0.12‰, and show evidence for biological isotopic fractionation of Mg. Hemolymph and EPF are on average isotopically close to seawater (Δ26Mghemolymph-seawater = -0.20 ± 0.27‰; 2 sd; n = 5 and Δ26MgEPF-seawater = -0.23 ± 0.25‰; 2 sd; n = 5) indicating (1) a predominant seawater origin for Mg in the intercellular medium and (2) a relatively passive transfer route through the bivalve organism into the calcifying fluid. The lightest isotopic composition is found in shell, with δ26Mg ranging from -1.89 ± 0.07‰ to -4.22 ± 0.06‰. This range is the largest in the dataset and is proposed to result from a combination of abiotic and biologically-driven fractionation processes. Abiotic control includes fractionation during precipitation of aragonite and accounts for Δ26Mgaragonite-seawater ≈ 1000 ln αaragonite-seawater = -1.13 ± 0.28‰ at 20 °C based on literature data. Deviations from inorganic precipitate (expressed as Δ26MgPhysiol) appear particularly variable in the clam shell, ranging from 0

  13. Evaluación de la tasa de aclaración de la almeja dulceacuícola Anodontites tortolis en un medio con coliformes Escherichia coli Clearance rate of faecal coliforms by netropical freshwater clam

    Directory of Open Access Journals (Sweden)

    Juan René Mallama Leyton

    2011-01-01

    Full Text Available En condiciones de laboratorio se evaluón acute; la eficiencia de la almeja de agua dulce (Anodontites tortolis) para disminuir la carga de coliformes fecales (Escherichia coli) determinada mediante filtración en membrana por 8 horas. El experimento se diseñó con dos tratamientos (densidades de seis (T1) y ocho almejas (T2) más un control) con tres replicaciones. Se encontraron diferencias significativas (PUnder laboratory conditions the efficiency of the freshwater clam Anodontites tortolis to diminish the quantity of faecal coliforms, determined by the membrane filtration method during eight hours was evaluated. The experiment was design with two treatments (two densities of six (T1) and eight clams (T2) and a control) and three replications. Statistical significant differences (P<0.05) according to the Kruskal-Wallis test for the clearance rates were found. The highest levels of remotion of E. coli belonged to the treatment in which there was the highest number of individuals. The clearance rate of the clams varied between 0.47 and 3.80 l.h-1.ind-1 which is reported in the literature. Removal levels showing A. tortolis suggest that this clam can be used as a biological resource for the treatment of the tertiary waters contaminated with faecal coliform bacteria.

  14. Long-term toxicity of hexabromocyclododecane (HBCDD) to the benthic clam Macoma balthica (L.) from the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Smolarz, Katarzyna, E-mail: oceksm@univ.gda.pl [University of Gdansk, Institute of Oceanography, Laboratory of Ecosystem Functioning, al Pilsudskiego 46, 81-378 Gdynia (Poland); Soedertoern University College, School of Life Sciences, Alfred Nobels alle 7, 141 89 Huddinge (Sweden); Berger, Agata [University of Gdansk, Institute of Oceanography, Laboratory of Ecosystem Functioning, al Pilsudskiego 46, 81-378 Gdynia (Poland)

    2009-11-27

    The world's largest brackish water sea area, the Baltic Sea, is considered to be one of the most polluted seas of the world. Many new pollutants are constantly entering the environment, such as brominated flame-retardants (BFRs). BFRs represent a group of compounds that structurally resemble hydrophobic organic contaminants, but only scarce data about their toxicity to marine organism exist. Thus, the purpose of this study was to analyze long-term in vivo cytotoxicity and genotoxicity of hexabromocyclodododecane (HBCDD) to exposed marine invertebrates using a suite of cytogenetic biomarkers. This included a set of nuclear and nucleolar characteristics and the micronucleus test. The use of those parameters reflects different mechanisms of nuclear activity regulation in cells (as a parameter of cytotoxicity) and measures subcellular processes. The induction of nuclear abnormalities (like the formation of micronuclei) was also employed here as a parameter of genotoxicity. In order to reflect the proliferative and metabolic activity of the cells the number of argylophillic nucleolar organiser regions (NORs) in interphase cells was scored. Over a period of 50 days an in vivo exposure experiment with a clam Macoma balthica and different concentrations of HBCDD (nominal concentrations of 0, 100 and 250 {mu}g/l) with three replicates each was performed. Gill cells were used as 'sentinel systems' considering specificity in metabolism, repair mechanisms, adaptative response and cell proliferation. A significant increase in nuclear and nucleolar abnormalities and in the frequency of dead cells was observed during the duration of the experiment with the highest peak occurring 10 days after exposure for nuclear abnormalities and 20-30 days after exposure for malfunction of ribosomal genes (NORs) (GLM analyses and Spearman correlation, p < 0.05). Thus, the induction of micronuclei and other nuclear abnormalities reflected the toxic potential of HBCDD to marine

  15. Artificial radioactivity in edible parts of giant clam mollusc from Mururoa atoll from 1967 to 1990. Health physics aspect. Radioactivite artificielle dans les parties comestibles d'un mollusque (Benitier) de l'atoll de Mururoa entre 1967 et 1990. Interpretation sanitaire

    Energy Technology Data Exchange (ETDEWEB)

    Bablet, J.P.; Ducousso, R. (Service mixte de controle biologique, 91 - Montlhery (FR)); Arnould, C. (Laboratoire d' etudes et de surveillance de l' environnement, Papeete, Tahiti, (Polynesie francaise))

    1991-01-01

    Radionuclides concentration by giant clams is associated with feeding habit. It's also a main food for polynesian atolls inhabitants, elsewhere than Mururoa island because this mollusc is not consumed like all the other fishery products from this atoll lagoon. Nevertheless measurements of ten artificial radionuclides are performed in edible parts of giant clams fished from Mururoa lagoon since the beginning of nuclear tests. The decay of radionuclides concentration is described versus time. To go further on we have computed the dose-equivalent for internal exposure of an eventual giant clams eater. It is estimated that the resulting risk of malignancy is below than 1 per 10 000.

  16. Seasonal variation in larval density of Limnoperna fortunei (Bivalvia, Mytilidae in the Iguaçu and Paraná rivers, in the region of Foz do Iguaçu, Paraná, Southern Brazil

    Directory of Open Access Journals (Sweden)

    Débora Pestana

    2008-06-01

    Full Text Available The larval density of the invasive mussel Limnoperna fortunei (Bivalvia, Mytilidae was monitored from January 2005 to February 2006 at two points along the Paraná and the Iguaçu Rivers, near Foz do Iguaçu, PR, Brazil. The results indicated two density peaks in the Paraná River: a lower peak between March and June and a higher peak in October. In the Iguaçu River, the values were much lower, yet they also showed a peak between September and October. A reduction in the reproductive activity was observed in both the rivers between July and August. The average larval density at the collection point in the Paraná reached 948.5 larvae/m³, with a peak of 2,999.5 larvae/m³ in October. The present study represented the first quantification of the larval density of L. fortunei in the lower reaches of the Iguaçu River, downstream of the Iguaçu falls.A densidade larval do molusco invasor Limnoperna fortunei (Bivalvia, Mytilidae foi monitorada entre janeiro de 2005 e fevereiro de 2006 em dois pontos dos rios Paraná e Iguaçu, na região de Foz do Iguaçu, PR. Os resultados registraram dois picos de densidade no rio Paraná: entre março e junho e um maior em outubro. No rio Iguaçu, os valores foram muito inferiores, mas também com um pico entre setembro-outubro. Em ambos os rios foi verificada uma pausa reprodutiva entre os meses de julho-agosto. A densidade média de larvas de L. fortunei no ponto amostrado no rio Paraná chegou a 948.5 larvas/m³, com pico de 2.999,5 larvas/m³ em outubro. O presente estudo representa a primeira quantificação da densidade larval de L. fortunei no rio Iguaçu, a jusante das Cataratas do Iguaçu.

  17. The Diversity of Molluscas Was Applied to Monitor the Heavy Metals in the Huayuan River%软体动物多样性在花垣河水体重金属监测中的应用

    Institute of Scientific and Technical Information of China (English)

    刘俊; 郑济芳; 胡南; 胡劲松; 朱允华; 刘运莲; 殷杰

    2009-01-01

    对湘西花垣河软体动物多样性与重金属污染状况进行了调查.在花垣河8个监测断面中,除S1、S3、S8的软体动物丰富度指数(DMA)与Shannon-Wiener多样性指数(H′)分别介于0.264 3-2.493 7和0.676 5-2.412 3外,S2、S4、S5、S7、S8五个断面的软体动物丰富度和多样性指数均为零.Mn、Cd、Pb、Cu、Zn在花垣河8个监测断面的河水中都能检测到,其中Mn、Cd含量严重超出GB的Ⅴ类水标准.软体动物多样性监测与理化监测的结果均表明,花垣河水体已经受到严重重金属污染.%The diversities of molluscas and the pollution of heavy metals in the Xiangxi Huayuan River were investigated.The species richness indexes (DMA) and Shannon-Wiener diversity indexes (H′) of mollusca at S1,S3,S8 were 0.264 3-2.493 7 and 0.676 5-2.412 3,respectively.The DMA and H′ at the other 5 sections were zero.Mn、Cd、Pb、Cu、Zn were identified in the water,the concentrantions of Mn and Cd were severe exceed the standard of limits of Ⅴ class water of GB.The results of the diversities of molluscas and the physico-chemical monitoring suggested that the water of the Huayuan River had been polluted by heavy metals severity.

  18. A Study of the Soft Clam (Mya arenaria) Population on Some of the Mud Flats Within the Boundaries of the Parker River National Wildlife Refuge, Essex County, Massachusetts, with respect to the possible changes brought about by the influx of Black duck

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Several investigators working on the food habits of the black duck (Anas rubripes), have reported the presence of soft clams (Mya arenaria), in their stomachs and...

  19. A pesca e o manejo do berbigão (Anomalocardia brasiliana (Bivalvia: Veneridae na Reserva Extrativista Marinha do Pirajubaé, SC, Brasil

    Directory of Open Access Journals (Sweden)

    Paulo Ricardo Pezzuto

    2015-08-01

    Full Text Available The Marine Extractive Reserve of Pirajubaé (MER is located in the urban area of Florianópolis city (capital of Santa Catarina State, Southern Brazil, and has the bivalve known as “berbigão” (Anomalocardia brasiliana as its main fishing resource. Based on 100 daily surveys carried out during 2005, this paper describes the berbigão fishery and presents the history of its management. A hand dredge (“gancho” was used by 22 men and four women to catch the berbigão. The fishery is conducted predominantly in the morning and under water depths between 20 and 50 cm. On average, each fisherman swept 469.2 m2 with the dredge and caught 270.5 kilograms of live clams per fishing day, summing up 888.6 t landed in the RESEX along 2005. More than 97% of the individuals in the catch exceeded the minimum legal size (20 mm total length. However, both individual size and total biomass of the stock reduced significantly over time. Most of the catch was processed (i.e. cooked and unshelled and sold to very few buyers. Current management measures include: a maximum number of authorized fisherman; b days of the week and times of the day when the fishery is allowed; c minimum distance between the iron bars in the ganchos’ basket; d minimum legal size; e space-time rotation of fishing areas and, f reporting of daily production data. In spite of the large volume of scientific and traditional knowledge available and the existence of management rules discussed and approved on a participatory system, both the berbigão sustainability and the RESEX as a whole are threatened by administrative, social, economic, environmental and bureaucratic pressures. Neutralize such threats is a key challenge to be faced in this important federal conservation area of Southern Brazil.

  20. Metabolomic responses in caged clams, Ruditapes decussatus, exposed to agricultural and urban inputs in a Mediterranean coastal lagoon (Mar Menor, SE Spain).

    Science.gov (United States)

    Campillo, Juan A; Sevilla, Angel; Albentosa, Marina; Bernal, Cristina; Lozano, Ana B; Cánovas, Manuel; León, Víctor M

    2015-08-15

    The Mar Menor is a coastal lagoon affected by the growth of intensive agriculture and urban development in the surrounding area. Large amounts of chemical pollutants from these areas are discharged into El Albujón, a permanent water-course flowing into the lagoon. Biomarkers such as the activity of acetylcholinesterase or antioxidant enzymes have been previously tested in this lagoon demonstrating the presence of neurotoxicity and oxidative stress in clams transplanted in sites affected by the dispersion of the effluent from El Albujón. To complete this traditional toxicology work, a metabolomic profiling of these transplanted organisms has been carried out for the detection of metabolic biomarkers induced by agricultural/urban pollutants. More than 70 metabolites have been quantified using a targeting metabolomics platform based on HPLC-MS. The intracellular metabolic pattern was analyzed by PCA from the digestive gland of clams after 7 and 22 days of transplantation. Results showed a different profile of metabolite between organisms collected from control and exposed sites. At the shorter exposure time, there was an increase in several metabolites in the latter when compared with those from control sites, whereas metabolic profiling at 22 days showed that those metabolites were drastically diminished, with even lower levels than at control sites. These metabolites included: (i) 12 amino acids from the 21 proteogenic and HomoSer, (ii) osmotic protectants such as γ-butyrobetaine and taurine and (iii) nucleotides such as ITP. Regarding sulfur-containing molecules, taurine could be highlighted as a potential biomarker since its concentration was reduced by more than 30 times after 22 days of exposure, whereas the antioxidant glutathione remained constant in the organisms from both control and exposed sites. Although targeted metabolomics has been shown as an early technique of pollutant effect detection, the two-phase pattern could highlight a more complicated

  1. Expression of genes involved in the uptake of inorganic carbon in the gill of a deep-sea vesicomyid clam harboring intracellular thioautotrophic bacteria.

    Science.gov (United States)

    Hongo, Yuki; Ikuta, Tetsuro; Takaki, Yoshihiro; Shimamura, Shigeru; Shigenobu, Shuji; Maruyama, Tadashi; Yoshida, Takao

    2016-07-10

    Deep-sea vesicomyid clams, including the genus Phreagena (formerly Calyptogena), harbor thioautotrophic bacterial symbionts in the host symbiosome, which consists of cytoplasmic vacuoles in gill epithelial cells called bacteriocytes. The symbiont requires inorganic carbon (Ci), such as CO2, HCO3(-), and CO3(2-), to synthesize organic compounds, which are utilized by the host clam. The dominant Ci in seawater is HCO3(-), which is impermeable to cell membranes. Within the bacteriocyte, cytoplasmic carbonic anhydrase (CA) from the host, which catalyzes the inter-conversion between CO2 and HCO3(-), has been shown to be abundant and is thought to supply intracellular CO2 to symbionts in the symbiosome. However, the mechanism of Ci uptake by the host gill from seawater is poorly understood. To elucidate the influx pathway of Ci into the bacteriocyte, we isolated the genes related to Ci uptake via the pyrosequencing of cDNA from the gill of Phreagena okutanii, and investigated their expression patterns. Using phylogenetic and amino acid sequence analyses, three solute carrier family 4 (SLC4) bicarbonate transporters (slc4co1, slc4co2, and slc4co4) and two membrane-associated CAs (mcaco1 and mcaco2) were identified as candidate genes for Ci uptake. In an in situ hybridization analysis of gill sections, the expression of mcaco1 and mcaco2 was detected in the bacteriocytes and asymbiotic non-ciliated cells, respectively, and the expression of slc4co1 and slc4co2 was detected in the asymbiotic cells, including the intermediate cells of the inner area and the non-ciliated cells of the external area. Although subcellular localizations of the products of these genes have not been fully elucidated, they may play an important role in the uptake of Ci into the bacteriocytes. These findings will improve our understanding of the Ci transport system in the symbiotic relationships of chemosynthetic bivalves. PMID:27016297

  2. Influence of parental sample sizes on the estimating genetic parameters in cultured clamMeretrix meretrix based on factorial mating designs

    Institute of Scientific and Technical Information of China (English)

    LIANG Bingbing; YUE Xin; WANG Hongxia; LIU Baozhong

    2016-01-01

    The precise and accurate knowledge of genetic parameters is a prerequisite for making efficient selection strategies in breeding programs. A number of estimators of heritability about important economic traits in many marine mollusks are available in the literature, however very few research have evaluated about the accuracy of genetic parameters estimated with different family structures. Thus, in the present study, the effect of parent sample size for estimating the precision of genetic parameters of four growth traits in clamM. meretrix by factorial designs were analyzed through restricted maximum likelihood (REML) and Bayesian. The results showed that the average estimated heritabilities of growth traits obtained from REML were 0.23–0.32 for 9 and 16 full-sib families and 0.19–0.22 for 25 full-sib families. When using Bayesian inference, the average estimated heritabilities were 0.11–0.12 for 9 and 16 full-sib families and 0.13–0.16 for 25 full-sib families. Compared with REML, Bayesian got lower heritabilities, but still remained at a medium level. When the number of parents increased from 6 to 10, the estimated heritabilities were more closed to 0.20 in REML and 0.12 in Bayesian inference. Genetic correlations among traits were positive and high and had no significant difference between different sizes of designs. The accuracies of estimated breeding values from the 9 and 16 families were less precise than those from 25 families. Our results provide a basic genetic evaluation for growth traits and should be useful for the design and operation of a practical selective breeding program in the clamM. meretrix.

  3. Introducción al estudio de los gasterópodos (Mollusca de la laguna de Montcortès (Pallars Sobirà, Cataluña, NE de la península ibérica

    Directory of Open Access Journals (Sweden)

    V. Bros

    2009-01-01

    Full Text Available Introduction to the study of gastropods (Mollusca on the Montcortés lake (Pallars Sobirà, Catlonia, NE of the Iberian peninsulaThe check-list of 50 species of terrestrial gastro­pod and freshwater molluscs in the Montcortès lake (Catalonia, Spain and its environs, pertaining to 24 different families, is shown. Thirty-three species are cited for the first time in the area of study. The unpublished data on their distribution and ecological requirements are contributed. The preliminary results indicate us that the communities of molluscs that accompany to the helofitic vegetation and the higrofits well are formed with elements of high faunistic and ecological interest. Simultaneously, some recommendations for the protection of the malacological fauna of the lake are commented.

  4. Evaluation of toxicological effects induced by tributyltin in clam Ruditapes decussatus using high-resolution magic angle spinning nuclear magnetic resonance spectroscopy: Study of metabolic responses in heart tissue and detection of a novel metabolite

    Directory of Open Access Journals (Sweden)

    H. Hanana

    2014-01-01

    The main finding of this study was the appearance of an original metabolite after TBT treatment likely N-glycine-N′-alanine. It is the first time that this molecule has been identified as a natural compound. Its exact role is unknown and remains to be elucidated. We suppose that its formation could play an important role in clam defense response by attenuating Ca2+ dependent cell death induced by TBT. Therefore this compound could be a promising biomarker for TBT exposure.

  5. Dynamics and chemistry of vortex remnants in late Arctic spring 1997 and 2000: Simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS

    Directory of Open Access Journals (Sweden)

    P. Konopka

    2003-01-01

    Full Text Available High-resolution simulations of the chemical composition of the Arctic stratosphere during late spring 1997 and 2000 were performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS. The simulations were performed for the entire northern hemisphere on two isentropic levels 450 K (~18 km and 585 K (~24 km. The spatial distribution and the lifetime of the vortex remnants formed after the vortex breakup in May 1997 display different behavior above and below 20 km. Above 20 km, vortex remnants propagate southward (up to 40°N and are "frozen in'' in the summer circulation without significant mixing. Below 20 km the southward propagation of the remnants is bounded by the subtropical jet. Their lifetime is shorter by a factor of 2 than that above 20 km, owing to significant stirring below this altitude. The behavior of vortex remnants formed in March 2000 is similar but, due to an earlier vortex breakup, dominated during the first 6 weeks after the vortex breakup by westerly winds, even above 20 km. Vortex remnants formed in May 1997 are characterized by large mixing ratios of HCl indicating negligible, halogen-induced ozone loss. In contrast, mid-latitude ozone loss in late boreal spring 2000 is dominated, until mid-April, by halogen-induced ozone destruction within the vortex remnants, and subsequent transport of the ozone-depleted polar air masses (dilution into the mid-latitudes. By varying the intensity of mixing in CLaMS, the impact of mixing on the formation of ClONO2 and ozone depletion is investigated. We find that the photochemical decomposition of HNO3 and not mixing with NOx-rich mid-latitude air is the main source of NOx within the vortex remnants in March and April 2000. Ozone depletion in the remnants is driven by ClOx photolytically formed from ClONO2. At the end of May 1997, the halogen-induced ozone deficit at 450 K poleward of 30°N amounts to ~12% with ~10% in the polar vortex and ~2% in well-isolated vortex remnants

  6. Abundance pattern of wedge clam Donax cuneatus (L.) in different spatial scale in the vicinity of a coastal nuclear power plant.

    Science.gov (United States)

    Hussain, K Jahir; Mohanty, A K; Satpathy, K K; Prasad, M V R

    2010-04-01

    Impact of thermal discharge from a coastal power station (Madras Atomic Power Station, southeast coast of India) on the spatial variability of Donax cuneatus abundance was assessed to determine the impact boundary. Totally, 20 sites were selected both on south and north side in increasing spatial scale from mixing zone, 12 locations were selected toward south side at a distance from 0 (near mixing point) to 2,000 m and eight location were selected toward north from the effluent mixing zone. Mean water temperature along the coast ranged from 29.1 +/-0.15 degrees C to 31.2 +/- 0.15 degrees C. Total organic carbon content in the sediment ranged from 0.27% to 0.70%. D. cuneatus population on the swash zone was ranged between 1.3 +/- 1.5 and 88.3 +/- 9.6 m(-2). Meager population of wedge clam was observed up to 100 m (S100) south from mixing point and abundance gradually increased in different spatial scale. Comparatively high abundance was observed from S400 and reached maximum at S1000 (64.0 +/- 3.6 m(-2)). Similar pattern was observed on north side too but less abundance was observed only up to 80 m (N80). Maximum abundance was observed at control location C3-N500 (88.3 +/- 9.6 m(-2)). Forty meters on either side of discharge point was highly impacted, 80 to 100 m toward plume flow (south) was moderately impacted, and 80 m north of mixing point also witnessed moderate impact. After 100 m (N100), north was not affected by effluents, whereas between 100 and 400 m, south was influenced slightly. Multivariate clustering pattern on the environmental variables of all sampling locations and population trend of D. cuneatus at those stations showed similarity. Present investigation unambiguously showed that the abundance pattern of D. cuneatus on the sandy beach of east coast of Kalpakkam is not governed by single major factor but due to the result of multiple interacting factors. The population size of the wedge clam with reference to the effect of power plant effluents and

  7. 砗磲研究现状及在我国南海开展养殖的前景%Giant clam research and prospect of aquaculture in the South China Sea

    Institute of Scientific and Technical Information of China (English)

    周勤; 王玉芬; 姜秀凤

    2014-01-01

    砗磲是软体动物门瓣鳃纲砗磲科生物的统称,广泛分布于热带珊瑚礁海域。20世纪八九十年代,澳大利亚、美国以及菲律宾等太平洋岛屿国家集中开展了砗磲增养殖及与之相关的生理、生态和经济学等基础研究。砗磲通过与其共生的虫黄藻获得营养,这一特性使得砗磲生长速度极快。砗磲的单位面积保有量可达400t·hm-2,使得它们在热带珊瑚礁海域中具有重要的生态学和养殖意义。不仅如此,砗磲在其生长过程中所体现出来的珊瑚礁修复价值以及碳汇渔业价值对于海洋开发和保护都有着极其重要的意义。同时,我国南海拥有环境优越的广阔热带海域,可开展砗磲养殖的面积达3000km2以上。结合以上认识,作者认为砗磲养殖具有形成热带海洋贝类养殖重大产业的潜力,可以为我国南海珊瑚礁保护和生态文明建设工程提供支撑。%Giant clams are of the family Tridacnidae with 10 living species in only two genera, Tridacna and Hippopus. In the 1980s and 1990s, the Pacific Rim countries, including Australia, the Philippines and the U.S., conducted a series of joint research on the cultivation of giant clams and the relevant physiological, ecological and economic factors. The unique feature of giant clams among bivalve molluscs is their symbiotic relationship with dinoflagellate algae, zooxanthellae (Symbiodinium. sp); this gives them a nutritional and growth advantage over normal bivalve molluscs. Since the stocking of giant clams can reach 400 tonnes per hectare, giant clams have great significance to both mariculture sector and tropical coral reef ecosystem. Moreover, due to benefits to coral reef restoration and carbon sink fisheries, the growth of giant clams also has a significance for marine development and protection. Meantime The South China Sea has 3000 km2 tropical reef water, which is suitable for developing mariculture. We suggest that giant clams

  8. Biochemical compounds' dynamics during larval development of the carpet-shell clam Ruditapes decussatus (Linnaeus, 1758): effects of mono-specific diets and starvation

    Science.gov (United States)

    Matias, Domitília; Joaquim, Sandra; Ramos, Margarete; Sobral, Paula; Leitão, Alexandra

    2011-09-01

    Successful larval growth and development of bivalves depend on energy derived from internal (endotrophic phase) and external (exotrophic phase) sources. The present paper studies survival, growth and biochemical changes in the early developmental stages (from egg to pediveliger) of the clam Ruditapes decussatus in order to characterize the nutritional requirements and the transition from the endotrophic to the exotrophic phase. Three different feeding regimes were applied: starvation and two mono-specific microalgal diets ( Isochrysis aff galbana and Chaetoceros calcitrans). A comparison between fed and unfed larvae highlighted the importance of egg lipid reserves, especially neutral lipids, during a brief endotrophic phase of embryonic development (first 2 days after fertilization). Egg reserves, however, may energetically contribute to the maintenance of larvae beyond the embryonic development. In fed larvae, the endotrophic phase is followed by a mixotrophic phase extending to days 5-8 after fertilization and a subsequent exotrophic phase. Metamorphosis starts around day 20. The intense embryonic activities are supported by energy derived from lipids, mainly from neutral lipids, and the metamorphic activities are supported by energy derived essentially from proteins accumulated during the planktonic phase and depend on the nutritional value of diets. The diet of I. aff galbana proves to be more adequate to R. decussatus larval rearing. The results provide useful information for the successful production of R. decussatus aquaculture.

  9. A novel widespread cryptic species and phylogeographic patterns within several giant clam species (Cardiidae: Tridacna from the Indo-Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Thomas Huelsken

    Full Text Available Giant clams (genus Tridacna are iconic coral reef animals of the Indian and Pacific Oceans, easily recognizable by their massive shells and vibrantly colored mantle tissue. Most Tridacna species are listed by CITES and the IUCN Redlist, as their populations have been extensively harvested and depleted in many regions. Here, we survey Tridacna crocea and Tridacna maxima from the eastern Indian and western Pacific Oceans for mitochondrial (COI and 16S and nuclear (ITS sequence variation and consolidate these data with previous published results using phylogenetic analyses. We find deep intraspecific differentiation within both T. crocea and T. maxima. In T. crocea we describe a previously undocumented phylogeographic division to the east of Cenderawasih Bay (northwest New Guinea, whereas for T. maxima the previously described, distinctive lineage of Cenderawasih Bay can be seen to also typify western Pacific populations. Furthermore, we find an undescribed, monophyletic group that is evolutionarily distinct from named Tridacna species at both mitochondrial and nuclear loci. This cryptic taxon is geographically widespread with a range extent that minimally includes much of the central Indo-Pacific region. Our results reinforce the emerging paradigm that cryptic species are common among marine invertebrates, even for conspicuous and culturally significant taxa. Additionally, our results add to identified locations of genetic differentiation across the central Indo-Pacific and highlight how phylogeographic patterns may differ even between closely related and co-distributed species.

  10. Concentrations of Contaminants with Regulatory Limits in Samples of Clam (Chamelea gallina) Collected along the Abruzzi Region Coast in Central Italy.

    Science.gov (United States)

    Visciano, Pierina; Scortichini, Giampiero; Suzzi, Giovanna; Diletti, Gianfranco; Schirone, Maria; Martino, Giuseppe

    2015-09-01

    Concentrations of pollutants with regulatory limits were determined in specimens of Chamelea gallina, a species of clam collected along the Abruzzi coastal region of the central Adriatic Sea. Nine sampling sites were selected to evaluate the distribution of contaminants in the environment and the health risk for consumers. The concentrations of all the examined compounds were lower than the maximums set by European legislation. Polycyclic aromatic hydrocarbons and total mercury were below the detection limit (0.18 μg/kg for benzo[a]anthracene, 0.30 μg/kg for chrysene, 0.12 μg/kg for benzo[b]fluoranthene, 0.08 μg/kg for benzo[a]pyrene, and 0.0050 mg/kg for total mercury) in all the analyzed samples. Mean concentrations of lead and cadmium were 0.104 and 0.110 mg/kg, respectively. Of the non-dioxin-like polychlorinated biphenyls, PCB-153, PCB-180, and PCB-138 were the most abundant at all sampling sites (1a to 9a) at 0.25 mi (ca. 0.4 km) and at some sampling sites (1b, 2b, 3b, 5b and 7b) at 0.35 mi (ca. 0.56 km). Principal component analysis revealed that the concentrations of dioxin-like polychlorinated biphenyls were similar at the majority of sampling sites, and O8CDD and 2,3,7,8-T4CDF were the predominant dioxin congeners.

  11. Does the antibiotic amoxicillin affect haemocyte parameters in non-target aquatic invertebrates? The clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis as model organisms.

    Science.gov (United States)

    Matozzo, Valerio; Bertin, Valeria; Battistara, Margherita; Guidolin, Angelica; Masiero, Luciano; Marisa, Ilaria; Orsetti, Alessandro

    2016-08-01

    Amoxicillin (AMX) is one of the most widely used antibiotics worldwide, and its levels in aquatic ecosystems are expected to be detectable. At present, information concerning the toxic effects of AMX on non-target aquatic organisms, such as bivalves, is scarce. Consequently, in this study, we investigated for the first time the effects of AMX on the haemocyte parameters of two bivalve species, the clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis, which share the same habitat in the Lagoon of Venice, in order to compare the relative sensitivity of the two species. The bivalves were exposed to 100, 200 and 400 μg AMX/L for 1, 3 and 7 days, and the effects on the total haemocyte count (THC), the diameter and volume of the haemocytes, haemocyte proliferation, lactate dehydrogenase (LDH) activity in cell-free haemolymph, the haemolymph pH, and the formation of micronuclei were evaluated. The actual concentrations of AMX in the seawater samples from the experimental tanks were also measured. Overall, the obtained results demonstrated that AMX affected slightly the haemocyte parameters of bivalves. In addition, no clear differences in terms of sensitivity to AMX exposure were recorded between the two bivalve species.

  12. Ocean acidification weakens the immune response of blood clam through hampering the NF-kappa β and toll-like receptor pathways.

    Science.gov (United States)

    Liu, Saixi; Shi, Wei; Guo, Cheng; Zhao, Xinguo; Han, Yu; Peng, Chao; Chai, Xueliang; Liu, Guangxu

    2016-07-01

    The impact of pCO2 driven ocean acidification on marine bivalve immunity remains poorly understood. To date, this impact has only been investigated in a few bivalve species and the underlying molecular mechanism remains unknown. In the present study, the effects of the realistic future ocean pCO2 levels (pH at 8.1, 7.8, and 7.4) on the total number of haemocyte cells (THC), phagocytosis status, blood cell types composition, and expression levels of twelve genes from the NF-kappa β signaling and toll-like receptor pathways of a typical bottom burrowing bivalve, blood clam (Tegillarca granosa), were investigated. The results obtained showed that while both THC number and phagocytosis frequency were significantly reduced, the percentage of red and basophil granulocytes were significantly decreased and increased, respectively, upon exposure to elevated pCO2. In addition, exposure to pCO2 acidified seawater generally led to a significant down-regulation in the inducer and key response genes of NF-kappa β signaling and toll-like receptor pathways. The results of the present study revealed that ocean acidification may hamper immune responses of the bivalve T. granosa which subsequently render individuals more susceptible to pathogens attacks such as those from virus and bacteria.

  13. Seasonal Variations of Escherichia Coli Contamination in Clams (Chamelea Gallina) Harvested in the Adriatic Sea (San Benedetto del Tronto district, Italy)

    Science.gov (United States)

    Semeraro, Angela Marisa; Aliventi, Alessandra; Di Trani, Vittoria; Capocasa, Piero

    2014-01-01

    In the European Union, the classification of shellfish harvesting areas depends on levels of Escherichia coli checked in shellfish flesh and determines whether post-harvest treatment required before shellfish can be sold for human consumption. Nevertheless, intermittent sources of contamination, such as rainfall and runoff from agricultural and urban lands, may give rise to seasonal variations of E. coli concentration, hence an annual classification could not be correct. In this study, we investigated the microbial trend in clams (Chamelea gallina) harvested from the district of San Benedetto del Tronto, Italy. The Algaeadria database, a monitoring network for the whole Adriatic area, provided results from 2005 to 2012. E. coli values compliant and non-compliant with food safety criteria were evaluated by graphical data analysis tools and one-tailed Fisher’s exact test. The results showed a clear general seasonal trend and, in one of the considered areas, the non-compliant values from July to February were significantly lower than those from March to June (P<0.05). These findings may scientifically support a seasonal classification.

  14. Modelling 2,4-dichlorophenol bioavailability and bioaccumulation by the freshwater fingernail clam Sphaerium corneum using artificial particles and humic acids

    International Nuclear Information System (INIS)

    The complex and variable composition of natural sediments makes it very difficult to predict the bioavailability and bioaccumulation of sediment-bound contaminants. Several approaches have been proposed to overcome this problem, including an experimental model using artificial particles with or without humic acids as a source of organic matter. For this work, we have applied this experimental model, and also a sample of a natural sediment, to investigate the uptake and bioaccumulation of 2,4-dichlorophenol (2,4-DCP) by Sphaerium corneum. Additionally, the particle-water partition coefficients (K d) were calculated. The results showed that the bioaccumulation of 2,4-DCP by clams did not depend solely on the levels of chemical dissolved, but also on the amount sorbed onto the particles and the characteristics and the strength of that binding. This study confirms the value of using artificial particles as a suitable experimental model for assessing the fate of sediment-bound contaminants. - An experimental model is proposed to better understand the bioavailability and bioaccumulation of sediment-bound 2,4-dichlorophenol

  15. Application of electron-beam irradiation on the production of salted and seasoned short-necked clam, Tapes Pilippinarum, for safe distribution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B.; Song, H.P.; Choe, J.H.; Jung, S. [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Jang, A. [Quality Control and Utilization of Animal Products, National Institute of Animal Science, Suwon 441-706 (Korea, Republic of); Kim, Y.J. [Food Safety Research Division, Korea Food Research Institute, Seongnam 463-746 (Korea, Republic of); Jo, C. [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)], E-mail: cheorun@cnu.ac.kr

    2009-07-15

    Salted and seasoned short-necked clam (Tapes Philippinarum; SNC) and its major ingredients, red hot pepper powder, ginger, garlic and onion were irradiated at 0.5, 1, 2 and 5 kGy, respectively, and the microbiological and sensory quality were evaluated. The water activities of SNC and red pepper powder were 0.91 and 0.56, respectively, and others were higher than 0.97. The initial microbial populations of SNC were approximately 3.99, 4.38 and 2.22 log CFU/g for total aerobic bacteria, yeast and mold, and coliform bacteria. The highest contamination of total aerobic bacteria was detected from ground ginger among ingredients at 5.51 log CFU/g. Electron-beam irradiation (0, 0.5, 1, 2 and 5 kGy) significantly reduced the initial microbial level of SNC and its ingredients not only immediately after irradiation, but also during storage at 10 {sup o}C for 4 weeks (p<0.05). There was no adverse change of sensory score except for the color of onion irradiated at 5 kGy, which results in a lower score than control. From the results electron-beam irradiation is a useful tool to enhance the storage stability and safe distribution of SNC.

  16. The usability of ark clam shell (Anadara granosa) as calcium precursor to produce hydroxyapatite nanoparticle via wet chemical precipitate method in various sintering temperature.

    Science.gov (United States)

    Khiri, Mohammad Zulhasif Ahmad; Matori, Khamirul Amin; Zainuddin, Norhazlin; Abdullah, Che Azurahanim Che; Alassan, Zarifah Nadakkavil; Baharuddin, Nur Fadilah; Zaid, Mohd Hafiz Mohd

    2016-01-01

    This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35-69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries .

  17. Developing simple tools for transferring the biology to the management in small scale fisheries: the case of a sword razor clam fishery in Galicia

    Directory of Open Access Journals (Sweden)

    Alba Hernández Otero

    2014-06-01

    To achieve the presented objectives, different samplings were conducted between 2008 and 2011 in three fishing beds of the Ría de Pontevedra (Galicia, NW Spain (Brensa, Bueu and Ons located at the inner, middle and outer part of the ria by scuba-diving at depths between 5 and 15 m. Thus, 20 samples of E. magnus were collected fortnightly/monthly during two years in order to study reproduction using the four following methodologies: gonad coverage (established by visually determining the percentage of coverage of the gonad, gonad smear (a new scale was created describing the follicles, gonadal condition index (GCI: gonad fresh weight/dry shell weight and histology. The proportion of broken clams was recorded by the divers. Besides, 113 sites separated 50 m between them and distributed throughout the main beds of the ria were sampled by scuba diving in the shallower points and using a box corer in the deeper ones. The collected sand was sieved and processed by binocular microscope to calculate the recruit (size E. magnus is faster during the first three years of life, declines at about four–six years old and almost ceases in subs

  18. Does the antibiotic amoxicillin affect haemocyte parameters in non-target aquatic invertebrates? The clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis as model organisms.

    Science.gov (United States)

    Matozzo, Valerio; Bertin, Valeria; Battistara, Margherita; Guidolin, Angelica; Masiero, Luciano; Marisa, Ilaria; Orsetti, Alessandro

    2016-08-01

    Amoxicillin (AMX) is one of the most widely used antibiotics worldwide, and its levels in aquatic ecosystems are expected to be detectable. At present, information concerning the toxic effects of AMX on non-target aquatic organisms, such as bivalves, is scarce. Consequently, in this study, we investigated for the first time the effects of AMX on the haemocyte parameters of two bivalve species, the clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis, which share the same habitat in the Lagoon of Venice, in order to compare the relative sensitivity of the two species. The bivalves were exposed to 100, 200 and 400 μg AMX/L for 1, 3 and 7 days, and the effects on the total haemocyte count (THC), the diameter and volume of the haemocytes, haemocyte proliferation, lactate dehydrogenase (LDH) activity in cell-free haemolymph, the haemolymph pH, and the formation of micronuclei were evaluated. The actual concentrations of AMX in the seawater samples from the experimental tanks were also measured. Overall, the obtained results demonstrated that AMX affected slightly the haemocyte parameters of bivalves. In addition, no clear differences in terms of sensitivity to AMX exposure were recorded between the two bivalve species. PMID:27219711

  19. Ocean acidification weakens the immune response of blood clam through hampering the NF-kappa β and toll-like receptor pathways.

    Science.gov (United States)

    Liu, Saixi; Shi, Wei; Guo, Cheng; Zhao, Xinguo; Han, Yu; Peng, Chao; Chai, Xueliang; Liu, Guangxu

    2016-07-01

    The impact of pCO2 driven ocean acidification on marine bivalve immunity remains poorly understood. To date, this impact has only been investigated in a few bivalve species and the underlying molecular mechanism remains unknown. In the present study, the effects of the realistic future ocean pCO2 levels (pH at 8.1, 7.8, and 7.4) on the total number of haemocyte cells (THC), phagocytosis status, blood cell types composition, and expression levels of twelve genes from the NF-kappa β signaling and toll-like receptor pathways of a typical bottom burrowing bivalve, blood clam (Tegillarca granosa), were investigated. The results obtained showed that while both THC number and phagocytosis frequency were significantly reduced, the percentage of red and basophil granulocytes were significantly decreased and increased, respectively, upon exposure to elevated pCO2. In addition, exposure to pCO2 acidified seawater generally led to a significant down-regulation in the inducer and key response genes of NF-kappa β signaling and toll-like receptor pathways. The results of the present study revealed that ocean acidification may hamper immune responses of the bivalve T. granosa which subsequently render individuals more susceptible to pathogens attacks such as those from virus and bacteria. PMID:27109580

  20. RISK CHARACTERIZATION OF A COASTAL ENVIRONMENT FACING A MINING AND INDUSTRIAL AREA IN SARDINIA (SULCIS-IGLESIENTE BY MEANS OF CLUSTER SAMPLING AND CONTAMINANTS RESEARCH ON EDIBLE FISH AND CLAMS

    Directory of Open Access Journals (Sweden)

    P.L. Piras

    2011-01-01

    Full Text Available On the basis of the results obtained from the analysis carried out on various environmental substrates (sediments, sea water and bio-indicators, it can be assumed that there has been a transfer of contaminants from sediments to edible “biota” in the Boi Cerbus lagoon (Sulcis-Iglesiente. It has also been verified that the benthic clams, in particular the Cerastoderma glaucum, is the species mainly affected by heavy metals contamination, in particular Lead, even if the role of Cadmium in the lagoon would need further investigation.

  1. Light induces changes in activities of Na+/K+-ATPase, H+/K+-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam, Tridacna squamosa

    OpenAIRE

    Ip, Yuen K.; Ching, Biyun; Kum C Hiong; Choo, Celine Y. L.; Boo, Mel V.; Wong, Wai P.; Chew, Shit F.

    2015-01-01

    The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH+ 4 or H+, and activities of enzymes involved in converting NH+ 4 to glutamate/glutamine in inner mantle, outer mantle, and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH+ 4 in substitution for K+ to ac...

  2. Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa

    OpenAIRE

    Alex Y K Ip; Biyun eChing; Kum C Hiong; Yen Ling eChoo; Mel Veen Boo; WaiP eWong; S F Chew

    2015-01-01

    The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH4+ or H+, and activities of enzymes involved in converting NH4+ to glutamate/glutamine in inner mantle, outer mantle and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH4+ in substitution for K+ to activa...

  3. Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata

    Energy Technology Data Exchange (ETDEWEB)

    Sellami, Badreddine, E-mail: sellamibadreddine@gmail.com [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Khazri, Abdelhafidh [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Mezni, Amine [Unit of Research 99/UR12-30, Department of Chemistry, Faculty of Sciences of Bizerte, 7021 Jarzouna (Tunisia); Louati, Héla; Dellali, Mohamed; Aissa, Patricia; Mahmoudi, Ezzeddine; Beyrem, Hamouda [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Sheehan, David, E-mail: d.sheehan@ucc.ie [Environmental Research Institute and Department of Biochemistry, University College Cork, Western Gateway Building, Western Road, Cork (Ireland)

    2015-01-15

    Highlights: • We assessed toxicity of anthracene, permethrin and their mixture on clams. • Tissue and stressor-dependent changes were observed in biochemical responses. • Permethrin induces phase transition from aragonite to calcite in shell structure. • Interactive effects were observed on digestive gland and gill biomarkers. • Both approaches give new vision to risk assessment of organic pollution. - Abstract: Anthracene (ANT) and permethrin (PER) are two of the more toxic compounds reaching the marine environment. This study aimed to determine the impact of these molecules on Venerupis decussata, an economically important species cultured on the Tunisian coast. Shell structure and its possible transformation upon exposure to the two contaminants were studied by X-ray diffraction and gravimetric analyses. Results revealed a phase transition in shell composition from aragonite to calcite after PER exposure, to a mixture of PER and ANT (Mix) but not for ANT alone. Catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GST) activities were determined in digestive gland and gills after exposure to ANT, PER and Mix to assess the impact of the contamination on the oxidative status of V. decussata. Enzyme activities increased in the digestive gland after PER treatment and in the gills after ANT treatment. PER exposure significantly reduced the levels of free thiols and increased levels of carbonylated proteins in the digestive gland, as compared to controls. In contrast, ANT exposure significantly reduced free thiols and increased the number of carbonylated proteins in the gills. Mix induced additive effects as measured by both enzymatic and proteomic approaches. The present study suggests that PER has a strong effect on shell structure; that PER and ANT exposure generate compound-dependent oxidative stress in the tissues of V. decussata and that a mixture of the two compounds has synergistic effects on biochemical response.

  4. Growth increment periodicity in the shell of the razor clam Ensis directus using stable isotopes as a method to validate age

    Directory of Open Access Journals (Sweden)

    J. F. M. F. Cardoso

    2013-07-01

    Full Text Available To evaluate the role of the razor clam Ensis directus in Dutch coastal waters, understanding its population dynamics is important. As such, the age structure of the population forms a key parameter. Accurate age determination in bivalve shells is not always straightforward due to the difficulty of interpreting externally visible growth lines. In the present paper, we aimed at validating the seasonality in growth line formation using visual techniques in combination with stable oxygen and carbon isotope analyses (δ18O and δ13C. High δ18O values in the shell coincided with growth marks on the external surface of the valve and in acetate peels of the shell's cross section. Most shell δ18O samples were assigned to the months from June to September. From November to March no samples were retrieved, indicating that the shell did not grow. The lowest reconstructed temperature (6.3 °C suggests that ~ 6 °C may be the threshold temperature for growth. Nevertheless, most of the reconstructed values fell above 14.5 °C, indicating that growth occurred mainly in the summer at relatively high temperatures. Shell δ13C profiles followed a more or less seasonal cycle, but no direct relationship could be made between δ13C values and annual growth lines. Although counting external annual growth lines led to a correct estimation of age and consequently of growth rates, we recommend analysing acetate peels of cross sections to support the distinction between annual lines and disturbance lines.

  5. Occurrence of Vibrio Parahaemolyticus, Vibrio Cholerae and Vibrio Vulnificus in the Clam Ruditapes Philippinarum (Adams & Reeve, 1850) from Emilia Romagna and Sardinia, Italy

    Science.gov (United States)

    Passalacqua, Pier Luca; Zavatta, Emanuele; Bignami, Giorgia; Serraino, Andrea

    2016-01-01

    Marine vibrios, Vibrio parahaemolyticus, V. vulnificus and V. cholerae are responsible of the majority of food-borne human infections by consumption of bivalve shellfish. The aim of the present study was to ascertain the occurrence of these bacteria, and their potential pathogenicity, in the Manila clam R. philippinarum from Emilia Romagna (ER) and Sardinia (SR) regions, Italy. Isolation was performed on CHROMagarTM vibrio with subculture on (thiosulfate-citrate-bile salts-sucrose) Agar and m-modified-cellobiose-polymyxin b-colistin (-CPC) Agar. Suspected strains were purified, biochemically characterized and genotyped by simplex polymerase chain reaction (PCR) for the specie-specific and pathogenic gene markers: V. parahaemolyticus (toxRP, tdh and trh); V. vulnificus (vvhA, hsp, vcgC, vcgE, CPS operon allele 1, CPS operon allele 2, 16s-rRNA operon allele A, 16s-rRNA operon allele B; V. cholerae (toxRC, hlya, tcpI, tcpA, ctxA, ctxB, stn/sto). Moreover a multiplex PCR was applied to the SR bivalve shellfish, for the simultaneous detection of the three targets directly on homogenate samples, targeting the species-specific gene for V. cholerae (toxRC), V. parahaemolyticus (toxRP) and V. vulnificus (vvhA). As a result of phenotyping and genotyping of isolates, bivalve shellfish from ER resulted positive for V. parahaemolyticus (27.8%) and V. vulnificus (10.1%), but negative for V. cholerae. Shellfish from SR resulted positive for V. parahaemolyticus (30.3%), V. vulnificus (6.1%) and V. cholerae (3%). No significant differences emerged between the two areas (P>0.05).

  6. Biodynamic modelling of the bioaccumulation of trace metals (Ag, As and Zn) by an infaunal estuarine invertebrate, the clam Scrobicularia plana

    International Nuclear Information System (INIS)

    Highlights: • Biodynamic modelling is used to predict accumulation of Ag, As and Zn in S. plana. • Dissolved and sediment-associated metals contribute to total metal bioaccumulation. • Relative importance varies with water and sediment concentrations and geochemistries. - Abstract: Biodynamic modelling was used to investigate the uptake and accumulation of three trace metals (Ag, As, Zn) by the deposit feeding estuarine bivalve mollusc Scrobicularia plana. Radioactive labelling techniques were used to quantify the rates of trace metal uptake (and subsequent elimination) from water and sediment diet. The uptake rate constant from solution (±SE) was greatest for Ag (3.954 ± 0.375 l g−1 d−1) followed by As (0.807 ± 0.129 l g−1 d−1) and Zn (0.103 ± 0.016 l g−1 d−1). Assimilation efficiencies from ingested sediment were 40.2 ± 1.3% (Ag), 31.7 ± 1.0% (Zn) and 25.3 ± 0.9% (As). Efflux rate constants after exposure to metals in the solution or sediment fell in the range of 0.014–0.060 d−1. By incorporating these physiological parameters into biodynamic models, our results showed that dissolved metal is the predominant source of accumulated Ag, As and Zn in S. plana, accounting for 66–99%, 50–97% and 52–98% of total accumulation of Ag, As and Zn, respectively, under different field exposure conditions. In general, model-predicted steady state concentrations of Ag, As and Zn matched well with those observed in clams collected in SW England estuaries. Our findings highlight the potential of biodynamic modelling to predict Ag, As and Zn accumulation in S. plana, taking into account specific dissolved and sediment concentrations of the metals at a particular field site, together with local water and sediment geochemistries

  7. Effects of particulate carbonaceous matter on the bioavailability of benzo[a]pyrene and 2,2‘,5,5‘-tetrachlorobiphenyl to the clam, Macoma balthica

    Science.gov (United States)

    McLeod, Pamela B.; van den Heuvel-Greve, Martine J.; Allen-King, Richelle M.; Luoma, Samuel N.; Luthy, Richard G.

    2004-01-01

    We investigated the bioavailability via diet of spiked benzo[a]pyrene (BaP) and 2,2‘,5,5‘-tetrachlorobiphenyl (PCB-52) from different carbonaceous (non-carbonate, carbon containing) particle types to clams (Macoma balthica) collected from San Francisco Bay. Our results reveal significant differences in absorption efficiency between compounds and among carbonaceous particle types. Absorption efficiency for PCB-52 was always greater than that for BaP bound to a given particle type. Among particles, absorption efficiency was highest from wood and diatoms and lowest from activated carbon. Large differences in absorption efficiency could not be simply explained by comparatively small differences in the particles' total organic carbon content. BaP and PCB-52 bound to activated carbon exhibited less than 2% absorption efficiency and were up to 60 times less available to clams than the same contaminants associated with other types of carbonaceous matter. These results suggest that variations in the amount and type of sediment particulate carbonaceous matter, whether naturally occurring or added as an amendment, will have a strong influence on the bioavailability of hydrophobic organic contaminants. This has important implications for environmental risk assessment, sediment management, and development of novel remediation techniques.

  8. An assessment on the influence of salinity in the growth of black clam (Villorita cyprinoides in cage in Cochin Estuary with a special emphasis on the impact of Thanneermukkom salinity barrier

    Directory of Open Access Journals (Sweden)

    Aloorkalarickal U. Arun

    2009-06-01

    Full Text Available Regular tidal flow, estuarine circulation and other allied hydrographical parameters in the Cochin Estuary has changed due to regular closure and opening of Thanneermukkom bund and entry of saline water in to the estuary. Temperature, salinity and bottom sediment texture are found to be the important factors significant for the growth and survival of bivalves. The environmental condition on different parts of the estuary especially at station II (south of bund, station IV (north of bund and station V (near to bar mouth showed a clear and distinct variation in all the hydrographical parameters due to the existence of Thanneermukkom bund and bar mouth. At stations II the frequency of temperature fluctuation was high and the dominant environment was freshwater when compared with station IV. Sediment texture at station II was sandy silt and at station IV was silty sand. At station V the dominant condition was saline and sediment texture was clayey in nature. A higher salinity was noted throughout the study period at station V. At station II the annual average growth was 8.48 mm; at station IV it was 15.15 mm and at station V it was 9.64 mm. Moderate level of salinity is found to be a favourable factor for the growth of Villorita cyprinoides. Growth rates of smaller clams were found to be higher than larger clams.

  9. Biodynamic modelling of the bioaccumulation of trace metals (Ag, As and Zn) by an infaunal estuarine invertebrate, the clam Scrobicularia plana

    Energy Technology Data Exchange (ETDEWEB)

    Kalman, J., E-mail: judit.kalman@uca.es [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Smith, B.D. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bury, N.R. [Division of Diabetes and Nutritional Science, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Rainbow, P.S. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2014-09-15

    Highlights: • Biodynamic modelling is used to predict accumulation of Ag, As and Zn in S. plana. • Dissolved and sediment-associated metals contribute to total metal bioaccumulation. • Relative importance varies with water and sediment concentrations and geochemistries. - Abstract: Biodynamic modelling was used to investigate the uptake and accumulation of three trace metals (Ag, As, Zn) by the deposit feeding estuarine bivalve mollusc Scrobicularia plana. Radioactive labelling techniques were used to quantify the rates of trace metal uptake (and subsequent elimination) from water and sediment diet. The uptake rate constant from solution (±SE) was greatest for Ag (3.954 ± 0.375 l g{sup −1} d{sup −1}) followed by As (0.807 ± 0.129 l g{sup −1} d{sup −1}) and Zn (0.103 ± 0.016 l g{sup −1} d{sup −1}). Assimilation efficiencies from ingested sediment were 40.2 ± 1.3% (Ag), 31.7 ± 1.0% (Zn) and 25.3 ± 0.9% (As). Efflux rate constants after exposure to metals in the solution or sediment fell in the range of 0.014–0.060 d{sup −1}. By incorporating these physiological parameters into biodynamic models, our results showed that dissolved metal is the predominant source of accumulated Ag, As and Zn in S. plana, accounting for 66–99%, 50–97% and 52–98% of total accumulation of Ag, As and Zn, respectively, under different field exposure conditions. In general, model-predicted steady state concentrations of Ag, As and Zn matched well with those observed in clams collected in SW England estuaries. Our findings highlight the potential of biodynamic modelling to predict Ag, As and Zn accumulation in S. plana, taking into account specific dissolved and sediment concentrations of the metals at a particular field site, together with local water and sediment geochemistries.

  10. Numerical simulation on temperature and stress fields of CLAM steel TIG weld%CLAM钢TIG焊接头温度场和应力场数值模拟

    Institute of Scientific and Technical Information of China (English)

    雷玉成; 朱强; 尹莎; 巨新

    2011-01-01

    ANSYS thermal-structural coupling technology, Parametric Design Language, life-death element technique, and double ellipsoid heat source were applied togegher in the numerical simulation of temperature and stress fields on single layer welding and the single-sided double layer welding of CLAM steel TIG weld joints. Without considering phase change and only considering the effects of residual stress field, the stress field based on temperature field data was calculated. The results of simulation with that of experiment were compared. The numerical results of residual stress distribution are almost consistent with the experimental ones. On middle section of the surface, longitudinal stress is tensile stress near the weld zone, reaches the maximum in the fusion area, and turn to compressive stress away from weld zone.The transverse stress is small tensile stress. Residual stress of single-sided double-layer welding specimen is lower than that of single layer welding specimen.%运用ANSYS的热-结构耦合技术,采用APDL参数化语言及生死单元技术,以双椭球热源作为内热源,对CLAM钢TIG焊对接单层焊和单面双层焊的温度场进行了数值模拟.在不考虑焊接温度场对材料相变影响,而仅考虑对残余应力场影响的条件下,以温度场的计算数据为依据进行应力场的计算,并将应力场的模拟结果与试验结果进行比较.分析结果表明:焊件残余应力的实测值和模拟结果中残余应力分布比较吻合;在焊件截面上表面,纵向残余应力在近缝区为拉应力,且在熔合区附近达到最大,而远离焊缝处转变为压应力;横向残余应力比较小,且均为拉应力;单面双层焊件表面残余应力比单层焊件的残余应力小.

  11. Intragenomic sequence variation at the ITS1 - ITS2 region and at the 18S and 28S nuclear ribosomal DNA genes of the New Zealand mud snail, Potamopyrgus antipodarum (Hydrobiidae: mollusca)

    Science.gov (United States)

    Hoy, Marshal S.; Rodriguez, Rusty J.

    2013-01-01

    Molecular genetic analysis was conducted on two populations of the invasive non-native New Zealand mud snail (Potamopyrgus antipodarum), one from a freshwater ecosystem in Devil's Lake (Oregon, USA) and the other from an ecosystem of higher salinity in the Columbia River estuary (Hammond Harbor, Oregon, USA). To elucidate potential genetic differences between the two populations, three segments of nuclear ribosomal DNA (rDNA), the ITS1-ITS2 regions and the 18S and 28S rDNA genes were cloned and sequenced. Variant sequences within each individual were found in all three rDNA segments. Folding models were utilized for secondary structure analysis and results indicated that there were many sequences which contained structure-altering polymorphisms, which suggests they could be nonfunctional pseudogenes. In addition, analysis of molecular variance (AMOVA) was used for hierarchical analysis of genetic variance to estimate variation within and among populations and within individuals. AMOVA revealed significant variation in the ITS region between the populations and among clones within individuals, while in the 5.8S rDNA significant variation was revealed among individuals within the two populations. High levels of intragenomic variation were found in the ITS regions, which are known to be highly variable in many organisms. More interestingly, intragenomic variation was also found in the 18S and 28S rDNA, which has rarely been observed in animals and is so far unreported in Mollusca. We postulate that in these P. antipodarum populations the effects of concerted evolution are diminished due to the fact that not all of the rDNA genes in their polyploid genome should be essential for sustaining cellular function. This could lead to a lessening of selection pressures, allowing mutations to accumulate in some copies, changing them into variant sequences.                   

  12. Accumulation and detoxification of paralytic shellfish poison (PSP) in hard clam Meretrix meretrix%麻痹性贝毒在文蛤体内的累积及净化技术研究

    Institute of Scientific and Technical Information of China (English)

    沈和定; 付金花; 冉福

    2011-01-01

    There were two stages in the experiment, accumulation and detoxification. Accumulation PSP by hard clam Meretrix meretrix achieved by feeding clams certain amount paralytic shellfish poison (PSP) every day and detecting PSP periodically. The detoxification was determined by method of"inner discharge and out purification". We found that the clam had a low ability to accumulate PSP. It reached to 884μg/100g after exposed to toxic A. tamarense for 15 d and the toxins in the viscera were higher than in other muscles, accounting to 77.4% - 89.1%. The amounts of PSP decreased in three groups with the elimination rates of the control group 30.1%, ozone purified group 32.8%, group of inner discharge and out purification 47.2% during detoxification. This research showed that "inner discharge and out purification" could accelerate PSP detoxification.%试验研究分毒素累积和解毒两个阶段,丈蛤(Meretrix meretrix)对麻痹性贝毒(Paralytic Shellfish Poisoning,PSP)的累积能力试验中每天投喂一定量塔玛亚历山大藻(Alexandrium tamarense),定期测定丈蛤体内的毒素含量;解毒试验通过投喂饵料和水体消毒的“内排外解”法进行。结果表明:文蛤对麻痹性贝毒的累积能力