Histopathologic and biochemical responses in Arctic marine bivalve molluscs exposed to experimentally spilled oil

Energy Technology Data Exchange (ETDEWEB)

Neff, J.M.; Hillman, R.E.; Carr, R.S.; Buhl, R.L.; Lahey, J.I.

1987-01-01

Following two experimental spills of chemically dispersed and undispersed crude oil in shallow bays on the northwest coast of Baffin Island bivalve molluscs accumulated significant amounts of petroleum hydrocarbons in bay receiving dispersed oil and in those receiving crude oil alone. Specimens of Mya truncata and Macoma calcarea for histopathologic examination were collected immediately before, immediately after and one year after the experimental oil spills. Immediately after there was increased gill and digestive tract necrosis in Mya from the chemically dispersed oil. After one year a few clams had granulocytomas throughout the tissues. Three clams receiving oil alone collected one year after the spill had invasive neoplasias. There were few lesions in Macoma immediatelly after or one year after the spill; animals had a high incidence of vacuolization of the digestive tubule epithelium. The incidence of parasitism and hemocytic infiltration also was higher in Maccoma. Clams Mya truncata were collected for biochemical analysis before, after and two weeks after the simulated oil spills. Concentations in the clam tissues of glucose, glycogen, trehalose, total lipid, and free amino acids were measured; free amino acids in adductor muscles were the most useful indices of pollutant stress. The results of the biochemical analyses indicate that Mya were not severely stressed by either dispersed oil or oil alone. After two weeks, clams from the dispersed oil bays were nearly normal, while those from the bay receiving oil alone appeared stressed. These results seem to corroborate results that the acute effects of dispersed oil are greater than those of undispersed oil, but effects of undispersed oil on infaunal molluscs develop more slowly and persist longer than those from dispersed oil. 43 refs., 2 figs., 6 tabs.

The distribution and habitat preferences of the declining species Orobanche arenaria Borkh at the northern limit of its geographical range

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Renata Piwowarczyk

2011-01-01

Full Text Available Three new sites of Orobanche arenaria were discovered during floristic investigations in the Wyżyna Małopolska upland in central Poland. The new localities are concentrated in the Ponidzie area (Garb Pińczowski ridge and Niecka Połaniecka basin and form the northern limit of the geographical range of O. arenaria. The paper presents information on the distribution of Orobanche arenaria in Poland, the abundance at the sites and habitats occupied by the species.

Population dynamics of Meloidogyne arenaria and Pasteuria penetrans in a long-term crop rotation study.

Science.gov (United States)

Timper, Patricia

2009-12-01

The endospore-forming bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes (Meloidogyne spp.). The primary objective of this study was to determine the effect of crop sequence on abundance of P. penetrans. The experiment was conducted from 2000 to 2008 at a field site naturally infested with both the bacterium and its host Meloidogyne arenaria and included the following crop sequences: continuous peanut (Arachis hypogaea) (P-P-P) and peanut rotated with either 2 years of corn (Zea mays) (C-C-P), 1 year each of cotton (Gossypium hirsutum) and corn (Ct-C-P), or 1 year each of corn and a vegetable (V-C-P). The vegetable was a double crop of sweet corn and eggplant (Solanum melongena). A bioassay with second-stage juveniles (J2) of M. arenaria from a greenhouse (GH) population was used to estimate endospore abundance under the different crop sequences. A greater numerical increase in endospore densities was expected in the P-P-P and V-C-P sequences than in the other sequences because both peanut and eggplant are good hosts for M. arenaria. However, endospore densities, as determined by bioassay, did not substantially increase in any of the sequences during the 9-year experiment. To determine whether the nematode population had developed resistance to the resident P. penetrans, five single egg-mass (SEM) lines from the field population of M. arenaria were tested alongside the GH population for acquisition of endospores from the field soil. Four of the five SEM lines acquired 9 to 14 spores/J2 whereas the GH population and one of the SEM lines acquired 3.5 and 1.8 spores/J2, respectively. Endospore densities estimated with the four receptive SEM lines were highest in the P-P-P plots (14-20 spores/J2), intermediate in the V-C-P plots (6-7 spores/J2), and lowest in the Ct-C-P plots (< 1 spore/J2). These results indicate that the field population of M. arenaria is heterogeneous for attachment of P. penetrans endospores. Moreover, spore densities

Population Dynamics of Meloidogyne arenaria and Pasteuria penetrans in a Long-Term Crop Rotation Study

Science.gov (United States)

2009-01-01

The endospore-forming bacterium Pasteuria penetrans is an obligate parasite of root-knot nematodes (Meloidogyne spp.). The primary objective of this study was to determine the effect of crop sequence on abundance of P. penetrans. The experiment was conducted from 2000 to 2008 at a field site naturally infested with both the bacterium and its host Meloidogyne arenaria and included the following crop sequences: continuous peanut (Arachis hypogaea) (P-P-P) and peanut rotated with either 2 years of corn (Zea mays) (C-C-P), 1 year each of cotton (Gossypium hirsutum) and corn (Ct-C-P), or 1 year each of corn and a vegetable (V-C-P). The vegetable was a double crop of sweet corn and eggplant (Solanum melongena). A bioassay with second-stage juveniles (J2) of M. arenaria from a greenhouse (GH) population was used to estimate endospore abundance under the different crop sequences. A greater numerical increase in endospore densities was expected in the P-P-P and V-C-P sequences than in the other sequences because both peanut and eggplant are good hosts for M. arenaria. However, endospore densities, as determined by bioassay, did not substantially increase in any of the sequences during the 9-year experiment. To determine whether the nematode population had developed resistance to the resident P. penetrans, five single egg-mass (SEM) lines from the field population of M. arenaria were tested alongside the GH population for acquisition of endospores from the field soil. Four of the five SEM lines acquired 9 to 14 spores/J2 whereas the GH population and one of the SEM lines acquired 3.5 and 1.8 spores/J2, respectively. Endospore densities estimated with the four receptive SEM lines were highest in the P-P-P plots (14-20 spores/J2), intermediate in the V-C-P plots (6-7 spores/J2), and lowest in the Ct-C-P plots (< 1 spore/J2). These results indicate that the field population of M. arenaria is heterogeneous for attachment of P. penetrans endospores. Moreover, spore densities

Establishment, growth and degeneration of Ammophila arenaria in coastal sand dunes

NARCIS (Netherlands)

Putten, van der W.H.

1989-01-01

Introduction

This study deals with the establishment, growth, and degeneration of Ammophila arenaria (marram grass), a grass species that dominates the vegetation in coastal foredunes. Following natural

Morula-like cells in photo-symbiotic clams harboring zooxanthellae.

Science.gov (United States)

Nakayama, K; Nishijima, M; Maruyama, T

1998-06-01

Symbiosis is observed between zooxanthellae, symbiotic dinoflagellates, and giant clams and related clams which belong to the families Tridacnidae and Cardiidae. We have previously shown that a photo-symbiotic clam Tridacna crocea has three types of hemocytes, the eosinophilic granular hemocyte with phagocytic activity, the agranular cell with electron lucent granules, and the morula-like cell with large (ca. 2 mum in diameter) colorless granules. The function of the morula-like cell is not clear, but it has not been reported in any other bivalves except photo-symbiotic clams T. crocea and Tridacna maxima. In order to clarify whether it is specific to photo-symbiotic clams or not, we studied hemocytes in the photo-symbiotic clams Tridacna derasa (Tridacnidae), Hippopus hippopus (Tridacnidae) and Corculum cardissa (Cardiidae), and a closely related non-symbiotic clam Fulvia mutica (Cardiidae). The eosinophilic granular hemocytes and the agranular cells were found in all of the clams examined. However, the morula-like cells which were packed with many large electron dense granules (ca. 2 mum in diameter), were observed only in the photo-symbiotic clams. In F. mutica, a closely related non-symbiotic clam, this type of hemocyte was not found. Instead a hemocyte with vacuoles and a few large granules containing peroxidase activity was observed. The large granules of F. mutica varied in size from ca. 1-9 mum in diameter. Present data suggests that the presence of morula-like cells is restricted to photo-symbiotic clams and that the hemocytes associated with the morula-like cells may have some functional relationship to symbiosis with zooxanthellae.

A comparison between Carex arenaria L. and Carex ligerica GAY - sedges from the Arenariae group based on leaf characteristics

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Lech Urbaniak

2014-01-01

Full Text Available The purpose of the study was to compare two taxonomically close species of sedges - Carex arenaria and Carex ligerica. The analysis was based on 6 characters of leaves. The populations studied were grown for the period of at least one year under the same conditions in a greenhouse. The results of statistical analysis indicate a distinctive character of each of the studied populations. Furthermore, the results show a higher interpopulational differentiation among C. ligerica populations.

Een nieuwe naam voor Arenaria serpyllifolia L. var. macrocarpa Lloyd

NARCIS (Netherlands)

Gutermann, W.; Mennema, J.

1983-01-01

The name Arenaria serpyllifoiia L. var. macrocarpa Lloyd is illegitimate, because of the existence of the earlier non-synonymous A. serpyllifolia0 macrocarpa Godron. As on the level of variety no other name is available, we call the taxon A renaria serpylli/olia L. var. Iloydn (Jord.) Gutermann et

Interaction between a fungal endophyte and root herbivores of Ammophila arenaria

NARCIS (Netherlands)

Hol, W.H.G.; de la Peña, E.; Moens, M.; Cook, R.

2007-01-01

The effect of an endophytic fungus (Acremonium strictum) on plant-growth related parameters of marram grass (Ammophila arenaria), and its potential as a protective agent against root herbivores (Pratylenchus dunensis and Pratylenchus penetrans, root-lesion nematodes) was investigated in two

The Role of Symbiotic Zooxanthellae on Giant Clam Nutrition

OpenAIRE

Ambariyanto

1997-01-01

Zooxanthellae, Symbiodinium sp, are single cell dinoflagellate algae known to live in association with many marine invertebrates such as hermatypic corals, sea anemones, jellyfish and giant clams (family Tridacnidae). In giant clams, these photosynthetic algae are located in a tubular system (known as Z tube system) which occurs within the clams. Apart from filter feeding, the nutrition of the clams is provided by zooxanthellae. These algae are capable of translocating part of their photosynt...

[First report of Montagnea arenaria (D.C.) Zeller (Agaricales) in Chile].

Science.gov (United States)

Madrid Lorca, Hugo; Muñoz, Mélica

2006-06-01

Montagnea arenaria (D.C.) Zeller (Agaricales), an interesting basidiomycete adapted to arid environments is recorded for the first time from a sample collected on sandy soil in the northern zone of Chile. Its mature fruiting body is described. Taxonomic and ecological comments are also addressed.

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

International Nuclear Information System (INIS)

Winter, A G; V; Dorsch, D S; Slocum, A H; Hosoi, A E; Deits, R L H

2014-01-01

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)

Influence of root exudates on attachment of Pasteuria penetrans to Meloidogyne arenaria

Science.gov (United States)

We hypothesized that root exudates would influence the spore attachment of Pasteuria penetrans to root-knot nematodes (Meloidogyne arenaria). An experiment was carried out using a factorial arrangement of two single spore (SS) lines cultured from P. penetrans and three single egg mass(SEM)lines cult...

Application of Arbuscular Mycorrhizal Fungi during the Acclimatization of Alpinia purpurata to Induce Tolerance to Meloidogyne arenaria

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Maryluce Albuquerque da Silva Campos

2017-06-01

Full Text Available An experiment was conducted to evaluate the tolerance of micropropagated and mycorrhized alpinia plants to the parasite Meloidogyne arenaria. The experimental design was completely randomized with a factorial arrangement of four inoculation treatments with arbuscular mycorrhizal fungi (AMF (Gigaspora albida, Claroideoglomus etunicatum, Acaulospora longula, and a non-inoculated control in the presence or absence of M. arenaria with five replicates. The following characteristics were evaluated after 270 days of mycorrhization and 170 days of M. arenaria inoculation: height, number of leaves and tillers, fresh mass of aerial and subterranean parts, dry mass of aerial parts, foliar area, nutritional content, mycorrhizal colonization, AMF sporulation, and the number of galls, egg masses, and eggs. The results indicated a significant interaction between the treatments for AMF spore density, total mycorrhizal colonization, and nutrient content (Zn, Na, and N, while the remaining parameters were influenced by either AMF or nematodes. Plants inoculated with A. longula or C. etunicatum exhibited greater growth than the control. Lower N content was observed in plants inoculated with AMF, while Zn and Na were found in larger quantities in plants inoculated with C. etunicatum. Fewer galls were observed on mycorrhized plants, and egg mass production and the number of eggs were lower in plants inoculated with G. albida. Plants inoculated with A. longula showed a higher percentage of total mycorrhizal colonization in the presence of the nematode. Therefore, the association of micropropagated alpinia plants and A. longula enhanced tolerance to parasitism by M. arenaria.

The Clam Trail: Blending Science Education, Public Art, and Tourism

Science.gov (United States)

Muscio, Cara; Flimlin, Gef; Bushnell, Rick

2011-01-01

The Barnegat Bay Shellfish Restoration's Clam Trail is an award-winning scavenger hunt that combines science education, public art, and tourism. This family adventure has participants seeking out giant painted fiberglass clams, upweller clam nurseries, and points of interest in search of science facts to record on their forms. Upon returning these…

Calculating the Contribution of Zooxanthellae to Giant Clams Respiration Energy Requirements

OpenAIRE

Ambariyanto

2002-01-01

Giant clams (Tridacnidae) are known to live in association with photosynthetic single cell dinoflagellate algae commonly called zooxanthellae. These algae which can be found in the mantle of the clams are capable of transferring part of their photosynthates which become an important source of energy to the host ( apart from filter feeding activity). In order to understand the basic biological processes of the giant clams , the contribution of zooxanthellae to the clam's energy requirement nee...

Weed Hosts of Meloidogyne arenaria and M. incognita Common in Tobacco Fields in South Carolina.

Science.gov (United States)

Tedford, E C; Fortnum, B A

1988-10-01

Thirty-two weed species common in South Carolina and one cultivar of tobacco were evaluated as hosts of Meloidogyne arenaria race 2 and M. incognita race 3 in the greenhouse. Egg mass production and galling differed (P Eleusine indica, Sorghum halepense, Setaria viridis, Digitaria sanguinalis, and Datura stramonium were poor hosts for M. arenaria. Amaranthus palmeri, Amaranthus hybridus, Chenopodium album, Euphorbia maculata, Setaria lutescens, Vicia villosa, Sida spinosa, Rumex crispus, and Portulaca oleracea were moderate hosts and Ipomoea hederacea var. integriuscula, Xanthium strumarium, Cyperus esculentus, Cynodon dactylon, Paspalum notatum, Eleusine indica, Setaria viridis, and Rumex acetosella were poor hosts for M. incognita. None of the above were good hosts for M. incognita. Tobacco 'PD4' supported large numbers of both nematode species.

Inactivation of Vibrio parahaemolyticus in hard clams (Mercanaria mercanaria) by high hydrostatic pressure (HHP) and the effect of HHP on the physical characteristics of hard clam meat.

Science.gov (United States)

Mootian, Gabriel K; Flimlin, George E; Karwe, Mukund V; Schaffner, Donald W

2013-02-01

Shellfish may internalize dangerous pathogens during filter feeding. Traditional methods of depuration have been found ineffective against certain pathogens. The objective was to explore high hydrostatic pressure (HHP) as an alternative to the traditional depuration process. The effect of HHP on the survival of Vibrio parahaemolyticus in live clams (Mercanaria mercanaria) and the impact of HHP on physical characteristics of clam meat were investigated. Clams were inoculated with up to 7 log CFU/g of a cocktail of V. parahaemolyticus strains via filter feeding. Clams were processed at pressures ranging from 250 to 552 MPa for hold times ranging between 2 and 6 min. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level (5 log reductions. The volume of clam meat (processed in shell) increased with negligible change in mass after exposure to pressure at 552 MPa for 3 min, while the drip loss was reduced. Clams processed at 552 MPa were softer compared to those processed at 276 MPa. However, all HHP processed clams were found to be harder compared to unprocessed. The lightness (L*) of the meat increased although the redness (a*) decreased with increasing pressure. Although high pressure-processed clams may pose a significantly lower risk from V. parahaemolyticus, the effect of the accompanied physical changes on the consumer's decision to purchase HHP clams remains to be determined. Shellfish may contain dangerous foodborne pathogens. Traditional methods of removing those pathogen have been found ineffective against certain pathogens. The objective of this research was to determine the effect of high hydrostatic pressure on V. parahaemolyticus in clams. Processing conditions of 450 MPa for 4 min and 350 MPa for 6 min reduced the initial concentration of V. parahaemolyticus to a nondetectable level, achieving >5 log reductions. © 2013 Institute of Food Technologists®

Model-assisted measurements of suspension-feeding flow velocities.

Science.gov (United States)

Du Clos, Kevin T; Jones, Ian T; Carrier, Tyler J; Brady, Damian C; Jumars, Peter A

2017-06-01

Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis , measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers ( Re ). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re , pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8 to 520, and exhalant Re ranged from 15 to 1073. Volumetric pumping rates ranged from 1.7 to 7.4 l h -1 for M . arenaria , 0.3 to 3.6 l h -1 for M . m ercenaria and 0.07 to 0.97 l h -1 for C . intestinalis We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies. © 2017. Published by The Company of Biologists Ltd.

Effects of predation by sea ducks on clam abundance in soft-bottom intertidal habitats

Science.gov (United States)

Lewis, Tyler; Esler, Daniel N.; Boyd, W. Sean

2007-01-01

Recent studies have documented strong, top-down predation effects of sea ducks on mussel populations in rocky intertidal communities. However, the impact of these gregarious predators in soft-bottom communities has been largely unexplored. We evaluated effects of predation by wintering surf scoters Melanitta perspicillata and white-winged scoters M. fusca on clam populations in soft-bottom intertidal habitats of the Strait of Georgia, British Columbia. Specifically, we documented spatial and temporal variation in clam density (clams m–2), scoter diet composition, and the consequences of scoter predation on clam abundance. Of the 3 most numerous clams, Manila clams Venerupis philippinarum and varnish clams Nuttallia obscurata were the primary prey items of both scoter species, while clams of the genus Macoma were rarely consumed by scoters. Between scoter arrival in the fall and departure in the spring, Manila clams decreased in density at most sample sites, while varnish clam densities did not change or declined slightly. Our estimates of numbers of clams consumed by scoters accounted for most of the observed declines in combined abundance of Manila and varnish clams, despite the presence of numerous other vertebrate and invertebrate species known to consume clams. For Macoma spp., we detected an over-winter increase in density, presumably due to growth of clams too small to be retained by our sieve (<5 mm) during fall sampling, in addition to the lack of predation pressure by scoters. These results illustrate the strong predation potential of scoters in soft-bottom intertidal habitats, as well as their potentially important role in shaping community structure.

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

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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.

Analysis of trace elements in the shell of asari clams

International Nuclear Information System (INIS)

Arakawa, J.; Sakamoto, W.; Arai, N.; Yoshida, K.

1999-01-01

Strontium concentration in the shells of asari clams collected at different locations was analyzed by PIXE. The Sr concentration of external surface of shell umbo was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length, 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. (author)

Does salt stress constrain spatial distribution of dune building grasses Ammophila arenaria and Elytrichia juncea on the beach?

Science.gov (United States)

van Puijenbroek, Marinka E B; Teichmann, Corry; Meijdam, Noortje; Oliveras, Imma; Berendse, Frank; Limpens, Juul

2017-09-01

Rising sea levels threaten coastal safety by increasing the risk of flooding. Coastal dunes provide a natural form of coastal protection. Understanding drivers that constrain early development of dunes is necessary to assess whether dune development may keep pace with sea-level rise. In this study, we explored to what extent salt stress experienced by dune building plant species constrains their spatial distribution at the Dutch sandy coast. We conducted a field transplantation experiment and a glasshouse experiment with two dune building grasses Ammophila arenaria and Elytrigia juncea . In the field, we measured salinity and monitored growth of transplanted grasses in four vegetation zones: (I) nonvegetated beach, (II) E. juncea occurring, (III) both species co-occurring, and (IV) A. arenaria dominant. In the glasshouse, we subjected the two species to six soil salinity treatments, with and without salt spray. We monitored biomass, photosynthesis, leaf sodium, and nutrient concentrations over a growing season. The vegetation zones were weakly associated with summer soil salinity; zone I and II were significantly more saline than zones III and IV. Ammophila arenaria performed equally (zone II) or better (zones III, IV) than E. juncea , suggesting soil salinity did not limit species performance. Both species showed severe winter mortality. In the glasshouse, A. arenaria biomass decreased linearly with soil salinity, presumably as a result of osmotic stress. Elytrigia juncea showed a nonlinear response to soil salinity with an optimum at 0.75% soil salinity. Our findings suggest that soil salinity stress either takes place in winter, or that development of vegetated dunes is less sensitive to soil salinity than hitherto expected.

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)

Effect of low salinity on the yellow clam Mesodesma mactroides

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YBM. Carvalho

Full Text Available The aim of this study was to determine the lethal salinity (LC50 for the yellow clam Mesodesma mactroides (Bivalvia: Mesodesmatidae and identify histopathological alterations that could be used to diagnose structural changes in clam tissue. Clams in two size classes (adults and juveniles were placed in 10 L chambers and exposed to salinities of 35, 30, 25, 20, 15, 10, and 5 g/L. There were triplicate chambers with seven clams each for each salinity. The LC50 values for a 48 h exposure were 6.5 g/L and 5.7 g/L for adults and juveniles, respectively. For a 96 h exposure, the LC50 values were 10.5 g/L for adults and 8.8 g/L for juveniles. The histological examination of yellow clams exposed to 10 g/L for 96 h showed intercellular oedema and necrotic foci in the epithelium of the digestive gland and occlusion of the lumen of the digestive gland. In conclusion, M. mactroides can be characterised as a moderately euryhaline species, tolerating salinities from 35 to 15 g/L.

Toxicity of a traditional molluscicide to asian clam veligers

Science.gov (United States)

Layhee, Megan J.; ,; Miho Yoshioka,; 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.

Ancient Clam Gardens Increased Shellfish Production: Adaptive Strategies from the Past Can Inform Food Security Today

Science.gov (United States)

Groesbeck, Amy S.; Rowell, Kirsten; Lepofsky, Dana; Salomon, Anne K.

2014-01-01

Maintaining food production while sustaining productive ecosystems is among the central challenges of our time, yet, it has been for millennia. Ancient clam gardens, intertidal rock-walled terraces constructed by humans during the late Holocene, are thought to have improved the growing conditions for clams. We tested this hypothesis by comparing the beach slope, intertidal height, and biomass and density of bivalves at replicate clam garden and non-walled clam beaches in British Columbia, Canada. We also quantified the variation in growth and survival rates of littleneck clams (Leukoma staminea) we experimentally transplanted across these two beach types. We found that clam gardens had significantly shallower slopes than non-walled beaches and greater densities of L. staminea and Saxidomus giganteus, particularly at smaller size classes. Overall, clam gardens contained 4 times as many butter clams and over twice as many littleneck clams relative to non-walled beaches. As predicted, this relationship varied as a function of intertidal height, whereby clam density and biomass tended to be greater in clam gardens compared to non-walled beaches at relatively higher intertidal heights. Transplanted juvenile L. staminea grew 1.7 times faster and smaller size classes were more likely to survive in clam gardens than non-walled beaches, specifically at the top and bottom of beaches. Consequently, we provide strong evidence that ancient clam gardens likely increased clam productivity by altering the slope of soft-sediment beaches, expanding optimal intertidal clam habitat, thereby enhancing growing conditions for clams. These results reveal how ancient shellfish aquaculture practices may have supported food security strategies in the past and provide insight into tools for the conservation, management, and governance of intertidal seascapes today. PMID:24618748

Low cycle fatigue properties of CLAM steel at 823 K

Energy Technology Data Exchange (ETDEWEB)

Hu, Xue [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049 (China); Huang, Lixin [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Yan, Wei; Wang, Wei [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Sha, Wei [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, Belfast BT9 5AG (United Kingdom); Shan, Yiyin, E-mail: yyshan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

2014-09-08

China Low Activation Martensitic (CLAM) steel is considered to be the main candidate material for the first wall components of future fusion reactors in China. In this paper, the low cycle fatigue (LCF) behavior of CLAM steel is studied under fully reversed tension–compression loading at 823 K in air. Total strain amplitude was controlled from 0.14% to 1.8% with a constant strain rate of 2.4×10{sup −3} s{sup −1}. The corresponding plastic strain amplitude ranged from 0.023% to 1.613%. The CLAM steel displayed continuous softening to failure at 823 K. The relationship between strain, stress and fatigue life was obtained using the parameters obtained from fatigue tests. The LCF properties of CLAM steel at 823 K followed Coffin–Manson relationship. Furthermore, irregular serration was observed on the stress–strain hysteresis loops of CLAM steel tested with the total strain amplitude of 0.45–1.8%, which was attributed to the dynamic strain aging (DSA) effect. During continuous cyclic deformation, the microstructure and precipitate distribution of CLAM steel changed gradually. Many tempered martensitic laths were decomposed into subgrains, and the size and number of M{sub 23}C{sub 6} carbide and MX carbonitride precipitates decreased with the increase of total strain amplitude. The response cyclic stress promoted the recovery of martensitic lath, while the thermal activation mainly played an important role on the growth of precipitates in CLAM steel at 823 K. In order to have a better understanding of high-temperature LCF behavior, the potential mechanisms controlling stress–strain response, DSA phenomenon and microstructure changes have also been evaluated.

Identification of clam plasma proteins that bind its pathogen Quahog Parasite Unknown.

Science.gov (United States)

Hartman, Rachel; Pales Espinosa, Emmanuelle; Allam, Bassem

2018-06-01

The hard clam (Mercenaria mercenaria) is among the most economically-important marine species along the east coast of the United States, representing the first marine resource in several Northeastern states. The species is rather resilient to infections and the only important disease of hard clams results from an infection caused by Quahog Parasite Unknown (QPX), a protistan parasite that can lead to significant mortality events in wild and aquacultured clam stocks. Though the presence of QPX disease has been documented since the 1960s, little information is available on cellular and molecular interactions between the parasite and the host. This study examined the interactions between the clam immune system and QPX cells. First, the effect of clam plasma on the binding of hemocytes to parasite cells was evaluated. Second, clam plasma proteins that bind QPX cells were identified through proteomic (LC-MS/MS) analyses. Finally, the effect of prior clam exposure to QPX on the abundance of QPX-reactive proteins in the plasma was evaluated. Results showed that plasma factors enhance the attachment of hemocytes to QPX. Among the proteins that specifically bind to QPX cells, several lectins were identified, as well as complement component proteins and proteolytic enzymes. Furthermore, results showed that some of these lectins and complement-related proteins are inducible as their abundance significantly increased following QPX challenge. These results shed light on plasma proteins involved in the recognition and binding of parasite cells and provide molecular targets for future investigations of factors involved in clam resistance to the disease, and ultimately for the selection of resistant clam stocks. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of steam and soil solarization for Meloidogyne arenaria control in Florida floriculture crops

Science.gov (United States)

Steam and soil solarization were investigated for control of the root-knot nematode Meloidogyne arenaria in two years of field trials on a commercial flower farm in Florida. The objective was to determine if pre-plant steam treatments in combination with solarization, or solarization alone effective...

Ancient clam gardens, traditional management portfolios, and the resilience of coupled human-ocean systems

Directory of Open Access Journals (Sweden)

Julia Jackley

2016-12-01

Full Text Available Indigenous communities have actively managed their environments for millennia using a diversity of resource use and conservation strategies. Clam gardens, ancient rock-walled intertidal beach terraces, represent one example of an early mariculture technology that may have been used to improve food security and confer resilience to coupled human-ocean systems. We surveyed a coastal landscape for evidence of past resource use and management to gain insight into ancient resource stewardship practices on the central coast of British Columbia, Canada. We found that clam gardens are embedded within a diverse portfolio of resource use and management strategies and were likely one component of a larger, complex resource management system. We compared clam diversity, density, recruitment, and biomass in three clam gardens and three unmodified nonwalled beaches. Evidence suggests that butter clams (Saxidomus gigantea had 1.96 times the biomass and 2.44 times the density in clam gardens relative to unmodified beaches. This was due to a reduction in beach slope and thus an increase in the optimal tidal range where clams grow and survive best. The most pronounced differences in butter clam density between nonwalled beaches and clam gardens were found at high tidal elevations at the top of the beach. Finally, clam recruits (0.5-2 mm in length tended to be greater in clam gardens compared to nonwalled beaches and may be attributed to the addition of shell hash by ancient people, which remains on the landscape today. As part of a broader social-ecological system, clam garden sites were among several modifications made by humans that collectively may have conferred resilience to past communities by providing reliable and diverse access to food resources.

Continuous cooling transformation behaviors of CLAM steel

Energy Technology Data Exchange (ETDEWEB)

Wu, Qing-sheng, E-mail: qingsheng.wu@fds.org.cn; Zheng, Shu-hui; Huang, Qun-ying; Liu, Shao-jun; Han, Yang-yang

2013-11-15

The continuous cooling transformation (CCT) behaviors of CLAM (China Low Activation Martensitic) steel were studied, the CCT diagram was constructed, and the influence of cooling rates on the microstructures was also investigated. The microstructures were investigated using optical microscopy (OM) and microhardness tests were also carried out. The results showed that CLAM steel possessed high hardenability and there were ferrite and martensite transformation regions only. The maximum cooling rate to form ferrite microstructure was found to be 10–12 K/min. In order to obtain fully ferrite microstructure, the cooling rate should be lower than 1 K/min. The CCT diagram also gave relevant parameters such as the transformation temperatures, i.e., A{sub c1}, A{sub c3}, M{sub s} and M{sub f} were 1124 K, 1193 K, 705 K and 593 K, respectively. The diagram made it possible to predict the microstructures and properties of CLAM steel with different cooling rates.

Continuous cooling transformation behaviors of CLAM steel

International Nuclear Information System (INIS)

Wu, Qing-sheng; Zheng, Shu-hui; Huang, Qun-ying; Liu, Shao-jun; Han, Yang-yang

2013-01-01

The continuous cooling transformation (CCT) behaviors of CLAM (China Low Activation Martensitic) steel were studied, the CCT diagram was constructed, and the influence of cooling rates on the microstructures was also investigated. The microstructures were investigated using optical microscopy (OM) and microhardness tests were also carried out. The results showed that CLAM steel possessed high hardenability and there were ferrite and martensite transformation regions only. The maximum cooling rate to form ferrite microstructure was found to be 10–12 K/min. In order to obtain fully ferrite microstructure, the cooling rate should be lower than 1 K/min. The CCT diagram also gave relevant parameters such as the transformation temperatures, i.e., A c1 , A c3 , M s and M f were 1124 K, 1193 K, 705 K and 593 K, respectively. The diagram made it possible to predict the microstructures and properties of CLAM steel with different cooling rates

9-Hydroxyfurodysinin-O-ethyl Lactone: A New Sesquiterpene Isolated from the Tropical Marine Sponge Dysidea arenaria

Directory of Open Access Journals (Sweden)

P. Karuso

2005-10-01

Full Text Available A new sesquiterpene, 9-hydroxyfurodysinin-O-ethyl lactone, has been isolated from a New Caledonian Dysidea arenaria, along with three known compounds. The possible incorporation of the ethyl ether from the extraction solvent is discussed.

Risk-based probabilistic approach to assess the impact of false mussel invasions on farmed hard clams.

Science.gov (United States)

Liao, Chung-Min; Ju, Yun-Ru; Chio, Chia-Pin; Chen, Wei-Yu

2010-02-01

The purpose of this article is to provide a risk-based predictive model to assess the impact of false mussel Mytilopsis sallei invasions on hard clam Meretrix lusoria farms in the southwestern region of Taiwan. The actual spread of invasive false mussel was predicted by using analytical models based on advection-diffusion and gravity models. The proportion of hard clam colonized and infestation by false mussel were used to characterize risk estimates. A mortality model was parameterized to assess hard clam mortality risk characterized by false mussel density and infestation intensity. The published data were reanalyzed to parameterize a predictive threshold model described by a cumulative Weibull distribution function that can be used to estimate the exceeding thresholds of proportion of hard clam colonized and infestation. Results indicated that the infestation thresholds were 2-17 ind clam(-1) for adult hard clams, whereas 4 ind clam(-1) for nursery hard clams. The average colonization thresholds were estimated to be 81-89% for cultivated and nursery hard clam farms, respectively. Our results indicated that false mussel density and infestation, which caused 50% hard clam mortality, were estimated to be 2,812 ind m(-2) and 31 ind clam(-1), respectively. This study further indicated that hard clam farms that are close to the coastal area have at least 50% probability for 43% mortality caused by infestation. This study highlighted that a probabilistic risk-based framework characterized by probability distributions and risk curves is an effective representation of scientific assessments for farmed hard clam in response to the nonnative false mussel invasion.

Predação de sementes de Allagoptera arenaria (Gomes O'Kuntze (Arecaceae por Pachymerus nucleorum Fabricius (Coleoptera, Chrysomelidae, Bruchinae Seed predation on Allagoptera arenaria (Gomes O'Kuntze (Arecaceae by Pachymerus nucleorum Fabricius (Coleoptera, Chrysomelidae, Bruchinae

Directory of Open Access Journals (Sweden)

Viviane Grenha

2008-01-01

Full Text Available A predação de sementes da palmeira Allagoptera arenaria (Gomes O'Kuntze, 1891(Arecaceae por Pachymerus nucleorum Fabricius, 1972 foi avaliada de setembro de 2003 a setembro de 2005 no Parque Nacional da Restinga de Jurubatiba (RJ. A biologia e o comportamento de P. nucleorum em A. arenaria e as taxas de predação de sementes foram descritas. Frutos encontrados sob 50 palmeiras foram coletados, mensalmente, em cada uma das duas áreas amostradas no PNRJ (mata de cordão arenoso e formação arbustiva aberta de Clusia Sclthdl, Clusiaceae. A avaliação dos cocos predados foi feita a partir da contagem dos orifícios de saída dos bruquíneos no campo, da emergência dos insetos no laboratório e da abertura dos frutos remanescentes. Através de observações e experimentos em 60 infrutescências, verificou-se que a oviposição de Pachymerus nucleorum em A. arenaria ocorre na infrutescência ainda em desenvolvimento diferentemente de registros na literatura em outras espécies de palmeiras, onde a oviposição ocorre nos frutos no chão. A predação dos frutos por P. nucleorum foi de 29,3% na área de mata de cordão arenoso e 20,6% na formação arbustiva aberta de Clusia. O ciclo de vida de P. nucleorum foi bastante longo e com amplitudes bem grandes dentro de uma mesma amostra, o que sugere uma possível diapausa em alguma fase do seu ciclo de vida.Seed predation on Allagoptera arenaria (Gomes O'Kuntze, 1891(Arecaceae palm by Pachymerus nucleorum Fabricius, 1972 was evaluated from September 2003 to September 2005 at the Parque Nacional da Restinga de Jurubatiba (PNRJ, Rio de Janeiro, Brazil. The biology and behaviour of P. nucleorum on A. arenaria and predation rates were described. Fruits found beneath 50 palms were collected, monthly, for each one of the two sampled areas at PNRJ (ridge forest and Clusia Sclthdl (Clusiaceae open shrubland formation. The evaluation of preyed fruits was done by counting exit holes of Bruchinae in the field

The Dual Nature of Metallothioneins in the Metabolism of Heavy Metals and Reactive Oxygen Species in Aquatic Organisms: Implications of Use as a Biomarker of Heavy-Metal Effects in Field Investigations

Directory of Open Access Journals (Sweden)

F. Gagné

2008-01-01

Full Text Available The purpose of this study was to examine the function of metallothioneins (MT in respect to the mobilization of heavy metals and superoxide anion (O 2 – scavenging in aquatic organisms. Using an O 2 – generating system, liberation of free zinc from native and zinc MT (Zn-MT was measured in vitro. Addition of the O 2 – generating system and H 2 O 2 readily increased the di- and trimeric forms of MT as determined by gel electrophoresis analysis. To determine whether the proportion of oxidized MT could change in contaminated environments, metal-contaminated Mya arenaria clams were collected from a harbour in the St. Lawrence Estuary. The levels of labile zinc, superoxide dismutase (O 2 – scavenging enzyme, lipid peroxidation (LPO and the oxidized/metallic form of MT were determined in the digestive gland. The results revealed that the induction of total MT levels was the result of increased oxidized MT at the expense of the reduced or metallic form of MT. Both superoxide dismutase (SOD and labile zinc (Zn levels were induced and they were significantly correlated with the oxidized form of MT, but not the metallic form, in feral clam populations. We concluded that the level of total MT was related to Zn mobility and the activation of antioxidant mechanisms such as SOD, and corresponded to the levels of oxidized MT. The metallic form of MT was negatively associated with Zn mobility but positively associated with oxidative damage such as LPO. Overall, the oxidized fraction of MT appeared to be more closely related to detoxification, while the metallic form of MT was associated with metal mobility and toxicity via oxidative damage. The protective effect of MT during heavy-metal contamination depends on the availability of metals and on its capacity to sequester reactive oxygen species.

The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

KAUST Repository

Pappas, Melissa

2017-12-01

The stability of marine photosymbiotic holobionts has major implications for the future of coral reef communities. This study aims to describe the stability of the Red Sea giant clam holobiont over the duration of one year and during induced bleaching stress under laboratory thermal manipulations. Tridacnid clams of the species Tridacna maxima were sampled at three reef locations near the central Saudi coast of the Red Sea. Associated Symbiodinium of Red Sea giant clams have previously been described to be part of only Clade A, which suggests a strong specificity in the clam-algal partnership, but specific types and potential shifting of types within this clade have not been examined for giant clams. The results from this study confirm that tridacnid symbiont types shift over time and the change between three A1 types suggests a biological and functional significance of two undescribed A1 Symbiodinium types. Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

Effects of Tropical Rotation Crops on Meloidogyne arenaria Population Densities and Vegetable Yields in Microplots.

Science.gov (United States)

McSorley, R; Dickson, D W; de Brito, J A; Hewlett, T E; Frederick, J J

1994-06-01

The effects of 12 summer crop rotation treatments on population densities of Meloidogyne arenaria race 1 and on yields of subsequent spring vegetable crops were determined in microplots. The crop sequence was: (i) rotation crops during summer 1991 ; (ii) cover crop of rye (Secale cereale) during winter 1991-92; (iii) squash (Cucurbita pepo) during spring 1992; (iv) rotation crops during summer 1992; (v) rye during winter 1992-93; (vi) eggplant (Solanum melongena) during spring 1993. The 12 rotation treatments were castor (Ricinus communis), cotton (Gossypium hirsutum), velvetbean (Mucuna deeringiana), crotalaria (Crotalaria spectabilis), fallow, hairy indigo (Indigofera hirsuta), American jointvetch (Aeschynomene americana), sorghum-sudangrass (Sorghum bicolor x S. sudanense), soybean (Glycine max), horsebean (Canavalia ensiformis), sesame (Sesamum indicum), and peanut (Arachis hypogaea). Compared to peanut, the first eight rotation treatments resulted in lower (P crops may provide a means for depressing M. arenaria population densities on a short-term basis to enhance yields in a subsequent susceptible vegetable crop.

PCDD/F and dioxin-like PCB bioaccumulation by Manila clam from polluted areas of Venice lagoon (Italy)

International Nuclear Information System (INIS)

Sfriso, Adriano; Facca, Chiara; Raccanelli, Stefano

2014-01-01

POP bioaccumulation pathways in the clam Tapes philippinarum were examined for two years from juveniles to adult size. Two polluted sites, one with sandy sediment, the other muddy were compared with a reference site characterized by low contamination levels. Juvenile clams coming from a hatchery were reared both on the sediment and in nets suspended at 30 cm from the bottom. POP changes in clam tissue were related to the concentrations recorded in sediments and in the particulate matter during the entire fattening period. Results provided interesting data on the relationships between environmental contamination and bioaccumulation. Contrary to studies on the decontamination times of the clams collected in polluted areas, this work investigates the preferential clam bioaccumulation pathways during growth under different environmental conditions. In general POP bioaccumulation resulted to be correlated to concentrations in SPM rather than in sediments and was higher in S-clams rather than in B-clams. -- Highlights: • PCDD/Fs and dioxin-like PCB accumulation in clam tissues during growth. • Muddy and sandy polluted areas. • How sediment and suspended matter contamination affect clam toxicity. • Clam toxicity and law limits. -- Clam bioaccumulation pathways in polluted areas

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

International Nuclear Information System (INIS)

Liu Fubin; Yao Man

2012-01-01

Highlights: ► China Low Activation Martensitic steel (CLAM) as FW the structural material. ► 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. ► 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 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.

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.

Photosymbiotic giant clams are transformers of solar flux.

Science.gov (United States)

Holt, Amanda L; Vahidinia, Sanaz; Gagnon, Yakir Luc; Morse, Daniel E; Sweeney, Alison M

2014-12-06

'Giant' tridacnid clams have evolved a three-dimensional, spatially efficient, photodamage-preventing system for photosymbiosis. We discovered that the mantle tissue of giant clams, which harbours symbiotic nutrition-providing microalgae, contains a layer of iridescent cells called iridocytes that serve to distribute photosynthetically productive wavelengths by lateral and forward-scattering of light into the tissue while back-reflecting non-productive wavelengths with a Bragg mirror. The wavelength- and angle-dependent scattering from the iridocytes is geometrically coupled to the vertically pillared microalgae, resulting in an even re-distribution of the incoming light along the sides of the pillars, thus enabling photosynthesis deep in the tissue. There is a physical analogy between the evolved function of the clam system and an electric transformer, which changes energy flux per area in a system while conserving total energy. At incident light levels found on shallow coral reefs, this arrangement may allow algae within the clam system to both efficiently use all incident solar energy and avoid the photodamage and efficiency losses due to non-photochemical quenching that occur in the reef-building coral photosymbiosis. Both intra-tissue radiometry and multiscale optical modelling support our interpretation of the system's photophysics. This highly evolved 'three-dimensional' biophotonic system suggests a strategy for more efficient, damage-resistant photovoltaic materials and more spatially efficient solar production of algal biofuels, foods and chemicals.

Evidence for Reciprocal Selection between Populations of Meloidogyne arenaria and Pasteuria penetrans in a Field Study

Science.gov (United States)

Beginning in 1998, a bioassay using second-stage juveniles (J2) from a greenhouse (GH) population of Meloidogyne arenaria (Ma) was used to monitor endospore densities of the bacterium Pasteuria penetrans, which was parasitizing Ma in a crop rotation study. Spore densities of the bacterium were very...

Evaluation of steam for Meloidogyne Arenaria control in production of in-ground floriculture crops in Florida

Science.gov (United States)

Steam and soil solarization were investigated for control of the root-knot nematode Meloidogyne arenaria in two years of field trials on a commercial flower farm in Florida. The objective was to determine if pre-plant steam treatments in combination with solarization, or solarization alone effective...

Great Lakes clams find refuge from zebra mussels in restored, lake-connected marsh (Ohio)

Science.gov (United States)

Nichols, S. Jerrine; Wilcox, Douglas A.

2004-01-01

Since the early 1990s, more than 95 percent of the freshwater clams once found in Lake Erie have died due to the exotic zebara mussel (Dreissena polymorpha). Zebra mussels attach themselves to native clams in large numbers, impeding the ability of the clams to eat and burrow. However, in 1996, we discovered a population of native clams in Metzger Marsh in western Lake Erie (about 50 miles [80 km] east of Toledo) that were thriving despite the longtime presence of zebra mussel in surrounding waters. At that time, Metzger Marsh was undergoing extensive restoration, including construction of a dike to replace the eroded barrier beach and of a water-control structure to maintain hydrologic connections with the lake (Wilcox and Whillans 1999). The restoration plan called for a drawdown of water levels to promote plant growth from the seedbank -- a process that would also destroy most of the clam population. State and federal resource managers recommended removing as many clams as possible to a site that was isolated from zebra mussels, and then returning them to the marsh after it was restored. We removed about 7,000 native clams in 1996 and moved them back to Metzger Marsh in 1999.

A SOCIAL COST-BENEFIT ANALYSIS OF A SMALL-SCALE CLAM ...

African Journals Online (AJOL)

Results from the CBA yielded positive net present values (NPVs) for project options involving live clams being sold on the export market (to Hong Kong) for R24.70 kg-1 and negative NPVs for domestic market options (Johannesburg and Cape Town), where the clam would be sold for R6.50 kg-1. Assuming a discount rate ...

Permanent genetic resources added to molecular ecology resources database 1 june 2011–31 july 2011

DEFF Research Database (Denmark)

Barker, F. Keith; Bell, James J.; Bogdanowicz, Steven M.

2011-01-01

This article documents the addition of 112 microsatellite marker loci and 24 pairs of single nucleotide polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Agelaius phoeniceus, Austrolittorina cincta, Circus cyaneus......, Circus macrourus, Circus pygargus, Cryptocoryne · purpurea Ridl. nothovar. purpurea, Mya arenaria, Patagioenas squamosa, Prochilodus mariae, Scylla serrata and Scytalopus speluncae. These loci were cross-tested on the following species: Cryptocoryne · purpurea nothovar. purpurea, Cryptocoryne affinis...

Concentrations of organotin compounds in sediment and clams collected from coastal areas in Vietnam

International Nuclear Information System (INIS)

Midorikawa, Sayaka; Arai, Takaomi; Harino, Hiroya; Ohji, Madoka; Nguyen Duc Cu; Miyazaki, Nobuyuki

2004-01-01

Levels of butyltin (BT) and phenyltin (PT) compounds were determined in sediments and clam Meretrix spp. collected from north and central coastal areas in Vietnam. Concentrations of TBT in sediments ranged from 0.89 to 34 ng g -1 dry wt and those in clams ranged from 1.4 to 56 ng g -1 wet wt. The levels of TBT in sediments and clams from Vietnam were within limits reported from other countries. Further, the TBT level in clams was lower than the tolerable average residue level (TARL) estimated based on tolerable daily intake (TDI). Trace amounts of PTs were also found in both sediment and clam samples. In sediments from north and central Vietnam, the concentrations of TBT were highest in the order of Hue (28 ng g -1 dry wt), Cua Luc (15 ng g -1 dry wt), Sam Son (6.3 ng g -1 dry wt), and Tra Co (5.5 ng g -1 dry wt). Among the clams from north and central Vietnam, the levels of TBT in clams from Cua Luc were dramatically high at 47 ng g -1 wet wt. TBT formed the principal butyltin species in sediment at all sites studied. The ratios of TBT in sediment were higher among BT compounds at all study sites. Of total BTs, TBT was the dominant species in clams from almost all sites studied. In spatial distribution, TPT showed a pattern similar to TBT, suggesting the use of TPT as an antifouling paint. The partition coefficient between sediment and calms was calculated. The partition coefficients of TBT and TPT were 2.01 (0.56-5.5) and 9.23 (3.1-20), respectively. These results show that sediment-bound TBT is a source of contamination to clams in addition to dissolved TBT

Resistance of Newly Introduced Vegetables to Meloidogyne arenaria and M. incognita in Korea

Directory of Open Access Journals (Sweden)

Donggeun Kim

2013-12-01

Full Text Available To select resistant vegetables against two species of root-knot nematodes, M. incognita and M. arenaria, 39 vegetables belongs to 7 families, 13 genera, 25 species were screened in greenhouse pot test. Susceptible vegetables to both nematodes were amarath and leaf beet in Amaranthaceae, Malabar spinach in Basellaceae, Moroheiya in Tiliaceae, and Water-convolvulus in Convolvulaceae, Pak-choi in Brassica campestris var. chinensis, Tah tasai in B. campestris var. narinosa, B. campestris var. chinensis x narinosa, Leaf mustard, Mustard green in B. juncea, Kyona in B. juncea var. laciniate, Choy sum in B. rapa subsp. arachinenesis, Kairan in B. oleracea var. alboglabra, Arugula in Eruca sativa, Garland chrysanthemum in Chrysanthemum coronarium, Endive in Cichorium endivia, Artichoke in Cynara cardunculus var. scolymus, Lettuce in Lactuca sativa. Resistant to M. arenaria but susceptible to M. incognita were B. oleracea cv. Matjjang kale, B. oleracea var. gongyloides cv. Jeok kohlrabi, and C. intybus cv. Radicchio. Resistant vegetables to both nematodes were C. intybus cv. Sugar loaf, Grumoro, Radichio treviso, B. oleracea cv. Manchu collard, Super matjjang, B. oleracea italica, B. oleracea var. botrytis italiana, and Perilla in Lamiaceae. Vegetables resistant to both species of root-knot nematodes could be used as high-valued rotation crops in greenhouses where root-knot nematodes are problem.

Continuous water quality monitoring for the hard clam industry in Florida, USA.

Science.gov (United States)

Bergquist, Derk C; Heuberger, David; Sturmer, Leslie N; Baker, Shirley M

2009-01-01

In 2000, Florida's fast-growing hard clam aquaculture industry became eligible for federal agricultural crop insurance through the US Department of Agriculture, but the responsibility for identifying the cause of mortality remained with the grower. Here we describe the continuous water quality monitoring system used to monitor hard clam aquaculture areas in Florida and show examples of the data collected with the system. Systems recording temperature, salinity, dissolved oxygen, water depth, turbidity and chlorophyll at 30 min intervals were installed at 10 aquaculture lease areas along Florida's Gulf and Atlantic coasts. Six of these systems sent data in real-time to a public website, and all 10 systems provided data for web-accessible archives. The systems documented environmental conditions that could negatively impact clam survival and productivity and identified biologically relevant water quality differences among clam aquaculture areas. Both the real-time and archived data were used widely by clam growers and nursery managers to make management decisions and in filing crop loss insurance claims. While the systems were labor and time intensive, we recommend adjustments that could reduce costs and staff time requirements.

Recolonization of reactor cooling water system by the Asiatic clam Corbicula fluminea

International Nuclear Information System (INIS)

Harvey, R.S.

1978-01-01

Recolonization rates for the Asiatic clam Corbicula fluminea ranged from 3.0 to 5.6 metric tons per year in cooling water basins for a nuclear production reactor at the Savannah River Plant. However, a 10-month cleaning cycle for each basin (flow area, 6100 m 2 ) keeps the depth of the silt/clam layer low. With this cleaning frequency, Corbicula are not reaching heat exchangers at sufficient size or in sufficient numbers to restrict flow. Data are presented on the size/age distribution for clams recolonizing cooling water basins between cleanings

Sensory Characteristics of Mud Clam (Polymesoda Erosa) Hydrolysate

International Nuclear Information System (INIS)

Normah Ismail; Noorasma Mustakim

2016-01-01

Mud clam (Polymesoda erosa) was hydrolysed using two different microbial enzymes; alcalase and flavourzyme. The volatile compounds, amino acids and molecular weight associated with umami and bitter taste in mud clam hydrolysate were determined by head space solid phase micro-extraction gas chromatography (HS-SPME-GCMS), High performance liquid chromatography (HPLC) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The characteristics of hydrolysates produced using alcalase and flavourzyme were compared. In total, eighteen, seven and six volatile compounds were identified in the flesh, alcalase hydrolysate and flavourzyme hydrolysate, respectively. 2-piperidinone volatile compound content which is associated with bitterness was 6.79 % in alcalase hydrolysate and 3.78 % in flavourzyme hydrolysate. SDS-PAGE results showed that alcalase hydrolysate contains smaller peptide (<52 kDa) compared to flavourzyme hydrolysate (<126 kDa). In addition, sensory analysis using quantitative descriptive analysis (QDA) showed that flavourzyme hydroysate was the least bitter but elicited more umami taste compared to alcalase hydrolysate. Further treatments are still needed to enhance umami taste and to remove bitter taste in mud clam hydrolysate. (author)

Long-Term Surveys Show Invasive Overbite Clams (Potamocorbula amurensis are Spatially Limited in Suisun Marsh, California

Directory of Open Access Journals (Sweden)

Jason Baumsteiger

2017-07-01

Full Text Available https://doi.org/10.15447/sfews.2017v15iss2art6The overbite clam (Potamocorbula amurensis is a major invasive species in the San Francisco Estuary, California, and has been implicated in the decline of pelagic productivity and native fish species. Little is known of its impact on Suisun Marsh, a large brackish tidal region of the estuary. We looked at the abundance and spatial distribution of clams in the marsh, including examining the influence of water quality, using long-term (1988–2015 otter trawl surveys. Temporal trends indicated that overbite clam abundance has been increasing, but adult clams were spatially restricted to a single large slough (Suisun. Clams were absent from most interior channels, limiting their overall effect on the marsh aquatic ecosystem. Abiotic variables, particularly salinity, proved important predictors of overbite clam abundance, although the variables examined alone could not explain overbite clam distributions. We propose that connectivity, detritus loads, and/or predation pressure may work in conjunction with abiotic variables to cause poor survival rates for recruits in interior marsh sites, keeping the distribution limited. Overall results are encouraging for restoration projects in brackish tidal marshes that need to deal with overbite clams.

Who's working on giant clam culture?

OpenAIRE

Vega, M.J.M.

1990-01-01

An examination is made of the literature on giant clam (Tridacna ) culture methods induced spawning, larvae, larval and post-larval rearing and socioeconomics. ASFA and the ICLARM library and professional staff collections were used for the search.

PCDD/F and dioxin-like PCB bioaccumulation by Manila clam from polluted areas of Venice lagoon (Italy).

Science.gov (United States)

Sfriso, Adriano; Facca, Chiara; Raccanelli, Stefano

2014-01-01

POP bioaccumulation pathways in the clam Tapes philippinarum were examined for two years from juveniles to adult size. Two polluted sites, one with sandy sediment, the other muddy were compared with a reference site characterized by low contamination levels. Juvenile clams coming from a hatchery were reared both on the sediment and in nets suspended at 30 cm from the bottom. POP changes in clam tissue were related to the concentrations recorded in sediments and in the particulate matter during the entire fattening period. Results provided interesting data on the relationships between environmental contamination and bioaccumulation. Contrary to studies on the decontamination times of the clams collected in polluted areas, this work investigates the preferential clam bioaccumulation pathways during growth under different environmental conditions. In general POP bioaccumulation resulted to be correlated to concentrations in SPM rather than in sediments and was higher in S-clams rather than in B-clams. Copyright © 2013 Elsevier Ltd. All rights reserved.

BASIC ANATOMICAL PROPERTIES of Ammannia auriculata var. arenaria (LYTHRACEAE

Directory of Open Access Journals (Sweden)

Mehmet AYBEKE

2016-12-01

Full Text Available This study was performed in order to define some anatomical characteristics of Ammannia auriculata Willd. var. arenaria (Kunth Koehne (Lythraceae to ensure a proper identification of the species and prevent confusion with other plants. Roots, leaves and stems of the plants were fixed in Formalin-Aceto-Alcohol (FAA, stained with various dyes, examined under a microscope and their photos were taken. The microscopic investigations of the plant parts revealed that 1 the leaf anatomy showed partly mezophyte character, the stem and roots beared aquatic characters with a wide aeranchymatic cortex and 2 thick lignified secondary xylem tissue in the roots and stems were located outwards of the stele. The results were compared with those of similar studies.

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.

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

International Nuclear Information System (INIS)

Tu, Tengxiu; Li, Shunxing; Chen, Lihui; Zheng, Fengying; Huang, Xu-Guang

2014-01-01

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

Influence of root exudates and soil on attachment of Pasteuria penetrans to root-knot nematode Meloidogyne arenaria

Science.gov (United States)

Pasteuria penetrans is a parasite of root-knot nematode (Meloidogyne spp.). Spores of P. penetrans attach to the cuticle of second stage juvenile (J2) and sterilize infected female. This study looked at different factors that influence spore attachment of P. penetrans to M. arenaria. Incubating J2 ...

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

OpenAIRE

Ismail, S.; Ahmed, A. S.; Anr, Reddy; Hamdan, S.

2016-01-01

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 s...

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.

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

Energy Technology Data Exchange (ETDEWEB)

Chang, Yongqin, E-mail: chang@ustb.edu.cn; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

2014-12-15

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.

An overview of the welding technologies of CLAM steels for fusion application

Energy Technology Data Exchange (ETDEWEB)

Chen Xizhang, E-mail: kernel.chen@gmail.com [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Huang Yuming [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Madigan, Bruce [Montana Tech. of University of Montana, Butte, MT 59701 (United States); Zhou Jianzhong [School of Mechanical Engineering, Jiangsu University, ZhenJiang, Jiangsu 221013 (China)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Welding technologies of China Low Activation Martensitic steel is overviewed. Black-Right-Pointing-Pointer Most welding technologies in use are discussed and suggestions are given. Black-Right-Pointing-Pointer Proper welding technologies could ensure weld properties but more detailed work are necessary. - Abstract: China Low Activation Martensitic steel (CLAMs), a kind of RAFM steel with Chinese intellectual property rights, is considered as the primary structural material for the China-designed ITER test blanket module (TBM). As one of the key issues in the fabrication of the fusion reactor, the welding technologies of CLAMs are reviewed. Emphasis is placed on the weldability of CLAMs by different welding methods, and on the properties of as-welded and post-weld heat-treated joints. Recent highlights in research and development for the welding of CLAMs show that proper welding procedure could provide welds with adequate tensile strength but the welds exhibit lower impact toughness compared with the base metal. Post-weld heat treatment (PWHT) and the application of ultrasonic energy during TIG welding could dramatically improve impact toughness. Research also shows that welds in CLAMs have sufficient resistance to swelling under irradiation as well as suitable compatibility with liquid LiPb. The microstructure, mechanical and other physical properties of welds are significantly different from those of the base metal due to the complicated welding thermal cycle. The weld joint is the area most likely to fail one or more of the design requirements within the fusion reactor. Therefore significant additional research is necessary to ensure safe application of welded CLAM steel for fusion reactor construction.

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.

The Stability of the Giant Clam Holobiont over Time and during Bleaching Stress

KAUST Repository

Pappas, Melissa

2017-01-01

Experimental bleaching shows that Red Sea giant clams, although exposed to rather hot temperatures naturally, will bleach at 34°C after two weeks, and severely bleached clams likely will not recover. During bleaching, Symbiodinium types shift as well, and shift more drastically than seasonal shifts during the year. This shifting may be an evolved characteristic of the giant clam to aid in surviving major changes in the environment. However, more research is needed to determine if these holobionts are capable of keeping up with the global forecast of warming in reef environments.

Ten-month recolonization of the k-area cooling water system by the Asiatic clam Corbicula fluminea

International Nuclear Information System (INIS)

Harvey, R.S.

1978-01-01

The Asiatic clam Corbicula fluminea was found in the Savannah River near Augusta, Georgia, in 1973. In 1975, Corbicula clogged heat exchangers and caused a shutdown of P Reactor, one of three operating nuclear production reactors (P, K, and C) at the Savannah River Plant (SRP). Clams were subsequently removed from K-Area and C-Area cooling water systems. At K Area, large volumes of river water are discharged into three 23-megaliter basins (Figure 1) where some settling occurs before the water is pumped through heat exchangers in the reactor area. The deposited silt provides a suitable substrate for Corbicula growth and reproduction. The silt must be removed at regular inervals to prevent heat exchanger pluggage arising from high populations of clams in the basins. The 186 basins at K Area were sampled to determine: the buildup of the Corbicula population since the basins were last cleaned, the size/age distribution of the clam population, and the occurrence of clam larvae. In addition, debris from flushes of Emergency Cooling Water Headers CW-39 and RW-1 were analyzed to determine: the relative abundance of live and dead clams, the size/age distribution of clams, and the volume of individual debris components

The Role of Plant-Parasitic Nematodes and Soil-Borne Fungi in the Decline of Ammophila-Arenaria (L) Link

NARCIS (Netherlands)

De Rooij van der Goes, P.C.E.M.

1995-01-01

In coastal foredunes, Ammophila arenaria (L.) Link grows vigorously when it is buried regularly by windblown sand and degenerates at stabilized sites. Nematodes and soil-borne fungi were found to be involved in its decline. In order to establish their role in the disease complex, seedlings of A.

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.

Recovery of intertidal hardshelled clams in Prince William Sound from Exxon Valdez oiling and shoreline treatments

International Nuclear Information System (INIS)

Houghton, J.P.; Lees, D.C.; Driskell, W.B.

1994-01-01

Native little neck (Protothaca staminea) and butter clams (Saxidomus giganteus) were quantitatively surveyed from 1989 through 1993 to evaluate effects from the Exxon Valdez oil spill. Hydraulic washing of sand and gravel beaches altered beach morphology by transporting material down slope from upper elevations, often burying the lower beach in several centimeters of sediment having a relatively low content of fines and organic carbon. Hydraulically washed beaches showed significant reductions in clam densities in 1989 and 1990. Recruitment of clams was very limited on these beaches through 1993; as a result, clam densities on these hydraulically washed beaches remain very depressed compared to those on beaches that were unoiled or oiled but not washed. Littlenecks transplanted from a reference site to a heavily oiled but untreated site showed significant patterns of increased mortality, decreased growth, and increased bioaccumulation of PAH in response to a gradient in sediment PAH, This same heavily oiled site has consistently had among the highest rates of hardshelled clam recruitment of any of the sites sampled. Littlenecks also were transplanted to another heavily oiled beach that had been hydraulically washed and had little remaining hydrocarbons. These clams showed very high survival, yet this beach has had very little clam recruitment. It is hypothesized that recruitment at this site may be inhibited by the low level of finer sediments and low organic content remaining after washing

Detection of Pasteuria penetrans infection in Meloidogyne arenaria race 1 in planta by polymerase chain reaction.

Science.gov (United States)

Schmidt, L M; Preston, J F; Nong, G; Dickson, D W; Aldrich, H C

2004-06-01

We report on the development of a PCR-based assay to detect Pasteuria penetrans infection of Meloidogyne arenaria in planta using specific primers for recently sequenced sigE, spoIIAB and atpF genes of P. penetrans biotype P20. Amplification of these genes in crude DNA extracts of ground tomato root galls using real-time kinetic PCR distinguished infected from uninfected M. arenaria race 1 by analysis of consensus thresholds for single copy genes. Fluorescent in situ hybridization (FISH) using the sigE primer sequence as a probe shows hybridization to P. penetrans cells in various stages of vegetative (pre-endospore) development. Ratios of gene copies for sigE and 16S rDNA were obtained for P. penetrans and compared to Bacillus subtilis as a genomic paradigm of endospore-forming bacteria. Phylogenetic analysis of the sigE gene from Gram-positive, endospore-forming bacteria finds P. penetrans most closely related Paenbacillus polymyxa. The sporulation genes (spo genes), particularly sigE, have sequence diversity that recommends them for species and biotype differentiation of the numerous Pasteuria isolates that infect a large number of plant-parasitic nematodes.

Suppression of hyphal growth of soil-borne fungi by dune soils from vigorous and declining stands of Ammophila arenaria

NARCIS (Netherlands)

De Boer, W.; Klein Gunnewiek, P.J.A.; Woldendorp, J.W.

1998-01-01

A study was carried out to determine whether expansion of marram-grass stands (Ammophila arenaria (L.) Link) on acidic inner Dutch coastal dunes was caused by suppressiveness of soils from these stands against three potential pathogenic fungi of marram grass, namely Fusarium culmorum (W. G. Sm.)

Vertical migration of nematodes and soil-borne fungi to developing roots of Ammophila arenaria (L.) link after sand accretion

NARCIS (Netherlands)

De Rooij van der Goes, P.C.E.M.; Peters, B.A.M.; Van der Putten, W.H.

1998-01-01

Ammophila arenaria benefits from regular burial of windblown beach sand as it allows escape from soilborne pathogens (nematodes and fungi). The present study was done to obtain more insight into the timing and order of migration of the soil organisms towards the newly formed roots. Accordingly,

Population Development of Pasteuria penetrans on Meloidogyne arenaria.

Science.gov (United States)

Oostendorp, M; Dickson, D W; Mitchell, D J

1991-01-01

A microplot study on the influence of cropping sequences with peanut in summer and bare fallowed or cover crops of rye or vetch in winter on the population development of Pasteuria penetrans was initiated in the spring of 1987. The number of spores of P. penetrans attached per second-stage juvenile of Meloidogyne arenaria race 1 increased from 0.11 in the fall of 1987 to 7.6, 8.6, and 3.6 in the fall of 1989 in the rye, vetch, and fallowed plots, respectively. Higher (P rye and vetch plots than in fallowed plots. No influence of P. penetrans on peanut, rye, or vetch yield was observed in 1987 and 1988, but in 1989 peanut yield was 64% higher (P cropping sequences in the spring of 1988 and 1989 but not in the fall following the peanut crop. In the spring the plots with rye had the lowest nematode numbers in either year (P rye, vetch, and fallowed).

Sublethal Effects of Tributyltin on the Hard Shell Clam, Mercenaria mercenaria,

Science.gov (United States)

1988-01-01

7) Laughlin, R.8., Jr., R.G. Gustafson and Peter Distribution/ Pendoley. 1987. Acute toxicity of tributyltin Avaiabilty Cdes( TBT ) to early life...Dist rSpecial Gustafson. 1987. Chronic embryo larval toxicity I of tributyltin ( TBT ) to the hard shell clam, All Aercenaria mercenaria. In preparation... tributyltin compounds ( TBT ). Post-set clams microalgae, Isochyis galmna Tahiti strain. TBT survived exposures up to 7.5 1i / for 25 days. No corentrations in

Avian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus

OpenAIRE

Hall, Jeffrey S.; Krauss, Scott; Franson, J. Christian; TeSlaa, Joshua L.; Nashold, Sean W.; Stallknecht, David E.; Webby, Richard J.; Webster, Robert G.

2012-01-01

Please cite this paper as: Hall et al. (2012) Avian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00358.x. Background  Low pathogenic avian influenza viruses (LPAIV) have been reported in shorebirds, especially at Delaware Bay, USA, during spring migration. However, data on patterns of virus excretion, minimal infectious doses, and clinical outcome are l...

Evaluation of 4-nonylphenol toxicity in the clam Tapes philippinarum

International Nuclear Information System (INIS)

Matozzo, Valerio; Deppieri, Martina; Oschino, Vanessa; Marin, M.G.

2003-01-01

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 LC 50 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

Size-related and seasonal diet of the manila clam (Ruditapes philippinarum), as determined using dual stable isotopes

Science.gov (United States)

Suh, Yeon Jee; Shin, Kyung-Hoon

2013-12-01

Stable isotope ratios of lab-cultured Manila clams (Ruditapes philippinarum) and those from natural tidal flats of Seonjae Island in Korea were investigated in terms of their dietary uptake patterns in relation to body size and season. The smallest size group of wild Manila clams revealed significantly depleted δ15N based on the results of a one-way ANOVA. There was significant seasonal change in the proportional contribution of food sources, especially in winter, from benthic particulate organic matter (BPOM) to pelagic particulate organic matter (POM). Laboratory-cultured Manila clams showed growth rates of 6.02-37.75 mm/yr, and smaller-sized clams did not fully utilise the microalgal diets that were provided constantly. Instead, they derived most of their energy from detritus or dead microalgae that had settled on the bottom. Bigger clams, however, exhibited well-balanced source contributions, converting the microalgal diets into biomass. This demonstrates intra-specific differences in the growth rates and preferred diet uptakes of Manila clams, even under similar environmental conditions.

New polymorphic microsatellite markers derived from hemocyte cDNA library of Manila clam Ruditapes philippinarum challenged by the protozoan parasite Perkinsus olseni

Science.gov (United States)

Kang, Hyun-Sil; Hong, Hyun-Ki; Park, Kyung-Il; Cho, Moonjae; Youn, Seok-Hyun; Choi, Kwang-Sik

2017-03-01

Manila clam Ruditapes philippinarum is one of the most important benthic animals in the coastal north Pacific region, where clam populations have been mixed genetically through trade and aquaculture activities. Accordingly, identification of the genetically different clam populations has become one of the most important issues to manage interbreeding of the local and introduced clam populations. To identify genetically different populations of clam populations, we developed 11 expressed sequence tag (EST)-microsatellite loci (i.e., simple sequence repeat, SSR) from 1,128 clam hemocyte cDNA clones challenged by the protozoan parasite Perkinsus olseni. Genotype analysis using the markers developed in this study demonstrated that clams from a tidal flat on the west coast contained 6 to 19 alleles per locus, and a population from Jeju Island had 4 to 20 alleles per locus. The expected heterozygosity of the 2 clam populations ranged from 0.472 to 0.919 for clams from the west coast, and 0.494 to 0.919 for clams from Jeju Island, respectively. Among the 11 loci discovered in this study, 7 loci significantly deviated from the Hardy-Weinberg equilibrium after Bonferroni correction. The 5 loci developed in this study also successfully amplified the SSRs of R. variegatus, a clam species taxonomically very close to R. philippinarum, from Hong Kong and Jeju Island. We believe that the 11 novel polymorphic SSR developed in this study can be utilized successfully in Manila clam genetic diversity analysis, as well as in genetic discrimination of different clam populations.

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.

Resistance of Commercial Tomato Cultivars to Meloidogyne arenaria and M. incognita

Directory of Open Access Journals (Sweden)

Donggeun Kim

2013-03-01

Full Text Available Root-knot nematodes (Meloidogyne spp. are among the main pathogens of greenhouse crops worldwide.Plant resistance is currently the method of choice for controlling these pests. To select resistant tomato againsttwo common species of root-knot nematodes, M. incognita and M. arenaria, 36 commercial tomato(Lycopersicon esculentum Mill. cultivars were screened. Seventeen tomato cultivars were resistant to bothroot-knot nematodes: six in cherry tomato, ‘Tenten’, ‘Cadillac’, ‘Cutti’, ‘Sweet’, ‘Ppotto’, ‘Lycopin-9’, eightin globe tomato, ‘Lovely 240’, ‘Dotaerang Dia’, ‘Cupirang’, ‘Dotaerang Master’, ‘Super Dotaerang’,‘Dotaerang Season’, ‘Miroku’, ‘Hoyong’, and three in root stock, ‘Special’, ‘Fighting’, and ‘Magnet’.

Preliminary Study on Hot Isostatic Pressing Diffusion Bonding for CLAM Steel

International Nuclear Information System (INIS)

Chunjing Li; Qunying Huang; Yican Wu

2006-01-01

China Low Activation Martensitic (CLAM) steel is being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences) since three years ago. CLAM is selected as the major candidate structure materials for the FDS series design of fusion reactors and for China liquid metal LiPb Test Blanket Module (TBM) for ITER i.e. DFLL-TBM, which are being carried out in ASIPP. Since the hot isostatic pressing (HIP) bonding technique is one of the main candidate bonding techniques for manufacturing of the first wall of a fusion reactor, research of the HIP technique on CLAM/CLAM is greatly needed. Preliminary HIP diffusion bonding experiments on CLAM steel have been performed. A few machining approaches such as dry-milling, turnery and grounding etc. were used to prepare the sample surfaces and then they were degreased with a mixture of alcohol, ether and acetone in an ultrasonic bath. The samples were joined by HIP diffusion bonding with the compression pressure of 150 MPa and the holding time of 2 ∼ 3 hours under different temperatures between 950 deg. and 1100 deg.. Different seal techniques of the capsules were studied as well. Then appropriate post heat treatment was done. Tests on mechanical properties of the joints such as tensile strength and impact toughness have been performed. The preliminary results show that the tensile properties are roughly the same as those of the base material. The absorbed energy of the joints at present is a little low and further research is needed to increase it. Microstructure of the joints was studied by optical microscope, SEM and TEM. Compositions of the defects on the joining line were analyzed by EDS. Through analysis of the results, optimized parameters for HIP are given. (author)

Phylogenetic diversity and functional characterization of the Manila clam microbiota: a culture-based approach.

Science.gov (United States)

Leite, Laura; Jude-Lemeilleur, Florence; Raymond, Natalie; Henriques, Isabel; Garabetian, Frédéric; Alves, Artur

2017-09-01

According to the hologenome theory, the microbiota contributes to the fitness of the holobiont having an important role in its adaptation, survival, development, health, and evolution. Environmental stress also affects the microbiota and its capability to assist the holobiont in coping with stress factors. Here, we analyzed the diversity of cultivable bacteria associated with Manila clam tissues (mantle, gills, hemolymph) in two non-contaminated sites (Portugal and France) and one metal-contaminated site (Portugal). A total of 240 isolates were obtained. Representative isolates (n = 198) of the overall diversity were identified by 16S rDNA sequencing and subjected to functional characterization. Isolates affiliated with Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes. Proteobacteria (mostly Pseudoalteromonadaceae and Vibrionaceae) were dominant in non-contaminated sites while Actinobacteria (mostly Microbacteriaceae) dominated in the metal-contaminated site. The main factor affecting the microbiota composition was contamination. No significant differences were observed between clam tissues and geographic regions. Several isolates tested positive for antibacterial activity, biofilm formation, protease, and siderophore production. The results show that the Manila clam harbors a diverse microbiota that may contribute to clam protection and overall fitness, as well as to its adaptation to stressful environments. In addition, the Manila clam microbiota is revealed as a promising source of novel probiotics with potential application in aquaculture.

Bitterness and Physichochemical Properties of Angelwing Clam (Pholas Orientalis) Hydrolysate

International Nuclear Information System (INIS)

Normah Ismail; Nurul Fasihah Razak

2016-01-01

Protein hydrolysates from angelwing clam were obtained by enzymatic hydrolysis using bromelain. The bitterness of hydrolysates was evaluated based on the degree hydrolysis (DH), sensory analysis, molecular weight distribution and functional group. By using 3 % of enzyme substrate ratio bromelain resulted in high DH value at 12.57 % when angelwing clam was hydrolysed for 2 hours. Sensory analysis showed that angelwing hydrolysate was bitter. Angelwing hydrolysate had molecular weight below 50 kDa. The lower molecular weight indicated that the protein has been degraded into smaller peptide chains which contribute to bitter taste. Moreover, the high peak of amine group in angelwing hydrolysate (3385.6 cm -1 ) suggested that bitterness exists. Angelwing hydrolysate had higher protein content, lower fat content and had good water holding capacity than the flesh. This result suggested that angelwing hydrolysate could be useful as food ingredient even though bitter taste developed after the hydrolysis. Thus, debittering should be considered in order to pave the way for full utilization of angelwing clam hydrolysate as a food ingredient. (author)

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.

Aquaculture Land-Use Policy: The Case of Clam Farming in Thaibinh Province, Vietnam

Directory of Open Access Journals (Sweden)

Thi Thu Hang NGO

2016-12-01

Full Text Available Policy-making and enforcement remains centralized in Vietnam. Policies have been formulated with less scientific and public justification, thus being largely bureaucratic and infeasible, and in many cases, they have created plagues for people at the grass-roots levels. This article focuses on the implementation of policies related to intertidal land-use and supports for clam farming in the Thaibinh province as a case study to explore the impacts of policies on clam farming and farmers. During the period of 2011–2013, provincial policies on intertidal land allocation and technical and financial supports had boosted clam farming development in the province to a surprising extent. Rapid expansion of the clam farming area has created significant consequences for the farming sector, as well as farmer’s lives. However, for the same provincial policies, but with different enforcement, different farming outcomes for clam farmers in the three study communes have resulted. Where farmers had more of a voice and choice in bidding for the intertidal areas they preferred, they faced fewer problems. It is, thus, suggested that a more decentralized policy-making and enforcement are needed, in which more scientific assessment and farmer participation are required to not only make government policy more successful in supporting farmers and achieving their expected outcomes, but also to provide farmers with more room to make their own farming decisions from which farming and marketing risks could be mitigated.

Occurrence of antibiotics in mussels and clams from various FAO areas.

Science.gov (United States)

Chiesa, Luca Maria; Nobile, Maria; Malandra, Renato; Panseri, Sara; Arioli, Francesco

2018-02-01

Filter feeders, like mussels and clams, are suitable bioindicators of environmental pollution. These shellfish, when destined for human consumption, undergo a depuration step that aims to nullify their pathogenic microorganism load and decrease chemical contamination. Nevertheless, the lack of contamination by drugs may not be guaranteed. Antimicrobials are a class of drugs of particular concern due to the increasing phenomenon of antibiotic resistance. Their use in breeding and aquaculture is a major cause of this. We developed a multiclass method for the HPLC-MS/MS analysis of 29 antimicrobials, validated according to the Commission Decision 2002/657/UE guidelines, and applied it to 50 mussel and 50 clam samples derived from various Food and Agricultural Organisation marine zones. The results obtained, indicate a negligible presence of antibiotics. Just one clam sample showed the presence of oxytetracycline at a concentration slightly higher than the European Union Maximum residue limit set for fish. Copyright © 2017. Published by Elsevier Ltd.

Further development of the SEA-Clam wave energy converter

Energy Technology Data Exchange (ETDEWEB)

Bellamy, N.W.; Peatfield, A.M.

1984-04-01

The final design of the SEA-Clam as a unit for a large 2 GW scheme has been described. This is the leading wave energy device arising out of the UK National Wave Energy Program and is seen as having the greatest potential for further development particularly for smaller scale applications. The small scale market for wave energy is examined and the design and cost parameters evaluated for the 250 kW to 1000 kW range of SEA-Clam units. Building a demonstration prototype rated at 650 kW and producing an annual average output of 250 kW is identified as the next step towards the commercial exploitation of wave energy.

Effects of Peanut-Tobacco Rotations on Population Dynamics of Meloidogyne arenaria in Mixed Race Populations

OpenAIRE

Hirunsalee, Anan; Barker, K. R.; Beute, M. K.

1995-01-01

A 3-year microplot study was initiated to characterize the population dynamics, reproduction potential, and survivorship of single or mixed populations of Meloidogyne arenaria race 1 (Ma1) and race 2 (Ma2), as affected by crop rotations of peanut 'Florigiant' and M. incognita races 1 and 3-resistant 'McNair 373' and susceptible 'Coker 371-Gold' tobacco. Infection, reproduction, and root damage by Ma2 on peanut and by Ma1 on resistant tobacco were limited in the first year. Infection, reproduc...

Resistance of Commercial Tomato Cultivars to Meloidogyne arenaria and M. incognita

Directory of Open Access Journals (Sweden)

Donggeun Kim

2013-03-01

Full Text Available Root-knot nematodes (Meloidogyne spp. are among the main pathogens of greenhouse crops worldwide. Plant resistance is currently the method of choice for controlling these pests. To select resistant tomato against two common species of root-knot nematodes, M. incognita and M. arenaria, 36 commercial tomato (Lycopersicon esculentum Mill. cultivars were screened. Seventeen tomato cultivars were resistant to both root-knot nematodes: six in cherry tomato, ‘Tenten’, ‘Cadillac’, ‘Cutti’, ‘Sweet’, ‘Ppotto’, ‘Lycopin-9’, eight in globe tomato, ‘Lovely 240’, ‘Dotaerang Dia’, ‘Cupirang’, ‘Dotaerang Master’, ‘Super Dotaerang’, ‘Dotaerang Season’, ‘Miroku’, ‘Hoyong’, and three in root stock, ‘Special’, ‘Fighting’, and ‘Magnet’.

Competition between endoparasitic nematodes and effect on biomass of Ammophila arenaria (marram grass) as affected by timing of inoculation and plant age

NARCIS (Netherlands)

Brinkman, E.P.; Duyts, H.; Van der Putten, W.H.

2005-01-01

We studied the effects of intra- and interspecific competition on the abundance of endoparasitic nematodes and assessed the consequences for biomass production of the natural dune grass Ammophila arenaria. Pratylenchus penetrans was limited by intraspecific competition and it suppressed the

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

The Clam-Gallas Palace in Prague: Emblematic Architecture?

Czech Academy of Sciences Publication Activity Database

Konečný, Lubomír

2010-01-01

Roč. 18, - (2010), s. 1-10 ISSN 0885-968X Institutional research plan: CEZ:AV0Z80330511 Keywords : Clam-Gallas Palace * Johann Bernhard Fischer von Erlach * architecture * emblem s * imprints Subject RIV: AL - Art, Architecture, Cultural Heritage

Direct contribution of clams (Ruditapes philippinarum) to benthic fluxes, nitrification, denitrification and nitrous oxide emission in a farmed sediment

Science.gov (United States)

Welsh, David T.; Nizzoli, Daniele; Fano, Elisa A.; Viaroli, Pierluigi

2015-03-01

The influence of the manila clam (Ruditapes philippinarum) on N-cycle processes, and oxygen and nutrient fluxes in a farmed sediment was investigated using a multiple core incubation approach and parallel incubations of individual clams. Clam population/biomass density varied ∼8-fold between cores and all sediment-water column solute (O2. N2, N2O, NH4+, NOX and DIN) fluxes and benthic process (N-regeneration, nitrification and denitrification) rates were strongly and significantly correlated with clam density/biomass. Isolated clams exhibited high rates of respiration, N-excretion, nitrification and denitrification of 2050 ± 70, 395 ± 49, 201 ± 42 and 235 ± 40 nmol individual-1 h-1, respectively. The direct contribution of the clams and their associated microbiota to benthic processes was estimated by multiplying the per individual rates by the number of clams in each incubated core. The clams on average directly accounted for 64-133% of total rates of sediment oxygen demand, N-regeneration, nitrification and denitrification, indicating that they regulated processes primarily through their own metabolic activity and that of bacteria that colonise them. Clams and the farmed sediments were significant sources of the greenhouse gas N2O, but this was primarily due to their high nitrification and denitrification rates, rather than high specific N2O yields, as N2O emissions represented farmed sediments had a high denitrification efficiency of 67 ± 10%, but this ecosystem service came at the environmental cost of increased N-regeneration and N2O emission rates. The measured N2O emissions indicate that bivalve aquaculture may be a significant source of N2O. It is therefore recommended that N2O emissions should be included in the impact assessments of current and future bivalve-farming projects.

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.

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

International Nuclear Information System (INIS)

Milan, Massimo; Pauletto, Marianna; Patarnello, Tomaso; Bargelloni, Luca; Marin, Maria Gabriella; Matozzo, Valerio

2013-01-01

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 μg 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.

Disentangling plant establishment in sandy coastal systems: biotic and abiotic factors that determine Allagoptera arenaria (Arecaceae germination

Directory of Open Access Journals (Sweden)

Luis Fernando Tavares de Menezes

2017-10-01

Full Text Available ABSTRACT Germination rate and establishment success of plants in harsh environments depend on the ability of seeds to withstand unfavorable environmental conditions and avoid predators. Brazilian coastal plains, known as restinga, are subject to environmental factors that seriously limit plant establishment and survival (e.g. salinity, desiccation, oligotrophy, flooding, high temperature and radiation levels. We tested, both in field and laboratory experiments, conditions for germination and establishment of Allagoptera arenaria, a palm tree often found in restinga ecosystems of southeastern Brazil, and which have a principal role in plant community dynamics. Our results showed that the absence of mesocarp, high radiation exposure, and temperature were the main drivers of seed germination. In the field, the highest germination rate was linked to nude seeds buried in open areas. High temperatures and/or predation damaged seeds that remained on the soil surface, especially if they were close to the mother plant and alongside dung piles made by dispersers. Under controlled conditions, seeds exhibited optimum germination at 35 ºC. Therefore, the germination and establishment of A. arenaria depend as much on environmental conditions as on a network of interactions including vertebrates and invertebrates, which allow this species to colonize harsh, open areas in restinga ecosystems.

Uptake and release of paralytic shellfish toxins by the clam Ruditapes decussatus exposed to Gymnodinium catenatum and subsequent depuration.

Science.gov (United States)

Botelho, Maria João; Vale, Carlos; Grilo, Rita Velez; Ferreira, João Gomes

2012-06-01

A laboratory experiment was performed with the clam Ruditapes decussatus, fed with the toxic dinoflagellate Gymnodinium catenatum and the non-toxic algae Isochrysis galbana (14 days) and subsequently only with I. galbana (15 days). Individual paralytic shellfish toxins were determined by LC-FLD in G. catenatum cells, whole clam tissues, and particulate organic matter (POM) produced by clams. The toxins dcSTX and dcGTX2 + 3 in the algae were less abundant than C1 + 2 and B1, but were predominant in clams during both the exposure and depuration phases. The toxin dcNEO was only detected in clams during a short period, indicating conversion from other compounds. The toxin composition of the POM indicated the export of dcSTX as faeces or pseudo-faeces along the entire experiment (2.5-14 nmol mg(-1)), B1 was present in a short period of the exposure and C1 + 2 and dcGTX2 + 3 absent. A mass balance calculation indicated that approximately 95% of C1 + 2 and 85% of B1 supplied to the clams were converted into other toxins or lost in solution. Conversely, the net gain of 512, 61 and 31 nmol for dcSTX, dcGTX2 + 3 and dcNEO, respectively, suggests the conversion from other assimilated compounds by clams during exposure and depuration phases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Low cycle fatigue properties of CLAM steel at 450 °C and 550 °C

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yanyun; Zhai, Xiangwei; Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn

2016-11-15

Highlights: • Low cycle fatigue properties of CLAM steel were investigated at 450 °C and 550 °C. • CLAM steel showed the continuous softening up to fail failure under cyclic loading. The degree of softening increased with increasing temperature. • Dislocation density decrease and subgrain coarsening during the test process were the possible reasons for the cyclic softening of the CLAM steel. - Abstract: The low cycle fatigue behavior of China Low Activation Martensitic (CLAM) steel has been studied using a constant strain rate of 8 × 10{sup −3}/s with the strain amplitudes ranging from 0.3% to 0.8% at 450 °C and 550 °C. Cyclic stress response showed a gradual softening until complete failure. The fatigue life decreased with increasing test temperature, and the effect of temperature on fatigue life was more pronounced at lower strain amplitudes. The cyclic deformation behavior at different temperatures has been analyzed according to the hysteresis loop, and the mechanism of cyclic softening was interpreted in view of the changes taking place in dislocation density and lath structures. Evaluation of low cycle fatigue properties of CLAM steel at 450 °C and 550 °C can help in design of the Chinese Test Blanket Module (TBM) for the International Thermonuclear Experimental Reactor (ITER) and a future fusion power plant.

Toxicological effects of paracetamol on the clam Ruditapes philippinarum: exposure vs recovery.

Science.gov (United States)

Nunes, Bruno; Nunes, Joana; Soares, Amadeu M V M; Figueira, Etelvina; Freitas, Rosa

2017-11-01

Exposure of wild organisms to anthropogenic substances never follows a definite time-course and pulsed events can often determine biological responses to such chemicals, confounding the interpretation of toxicological data. This is the case of specific chemicals such as pharmaceutical drugs, which are commonly released by sewage systems into sensitive areas, including estuaries. The presence and amount of these chemicals in the wild can be modulated by events such as dilution due to heavy rain, floods, or by varying patterns of domestic water use (daily vs. seasonal). The present study aimed to obtain additional data about the toxicity of paracetamol towards the marine clam species Ruditapes philippinarum, following realistic modes of exposure. Thus, the toxicity assessment was made after an acute exposure to different concentrations of paracetamol, followed by a recovery period. The adopted toxicological endpoints included energy-related parameters (glycogen content, GLY; protein content, PROT; electron transport system activity, ETS), activity of antioxidant and biotransformation enzymes (superoxide dismutase, SOD; glutathione peroxidase, GPx; Glutathione-S-transferases, GSTs), levels of reduced glutathione (GSH), neurotoxicity (cholinesterases activity, ChEs), and indicators of oxidative damage (lipid peroxidation, LPO). The here obtained results showed an increase in SOD and GPx activities after exposure. In organisms exposed to the highest concentration tested it was also possible to observe a significant increase in GSTs activity. However, these alterations in the antioxidant defence system were not able to prevent the occurrence of oxidative stress in exposed organisms. Furthermore, exposure to paracetamol induced neurotoxicity in clams, with a concentration-dependent ChEs inhibition along the exposure concentrations. Exposure to paracetamol also led to an increase of GLY content which resulted from metabolic activity depression along the increasing exposure

Growth and Histological Effects to Protothaca staminea (Littleneck Clam) of Long-Term Exposure to Chlorinated Sea Water

Energy Technology Data Exchange (ETDEWEB)

Gibson, C. I.; Hillman, A. E.; Wilkinson, P.; Woodruff, D. L.

1980-08-01

There has been considerable concern about the potential for long-term effects to marine organisms from chlorinated sea water. As part of a larger study to investigate the effects of materials resulting from seawater chlorination on marine organisms, groups of littleneck clams, Protothaca staminea, were exposed to sea water that had been chlorinated. Two experiments were conducted. In one test, groups of littleneck clams were exposed to dilutions of chlorinated sea water that had average chlorine produced oxidant (CPO) concentrations of 16 {micro}g/l or less. In the second test, groups of clams were exposed to chlorinated seawater-unchlorinated seawater mixtures that had target CPO concentrations of 0, 6, 12, 25, 50 and 100 {micro}g/l. In the first experiment, length measurements were made on all clams at approximately one-month intervals for three months. In the second test, length, weight, depth, width and edge etching were used to measure growth, and subsamples were harvested and measured at one-month intervals. In addition, clams were preserved for histological examination. The clams in the first experiment all had negative growth. In the second test, growth was inhibited under all conditions through the first four months of exposure. During the last four months, there was positive signs of growth at the 0, 6 and 12 {micro}g/l CPO test conditions. Histological examination indicates that P. staminea does not adapt well to being held in aquaria. Most clams, tram all test and control conditions, showed evidence of necrosis at one month. This condition seemed to improve with longer exposure at lower CPO concentrations but persisted at CPO concentrations of 25 {micro}g/l and higher. Other histological effects were apparent at the higher exposure concentrations as the length of exposure increased.

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.

Elimination of Escherichia coli and Salmonella in Clam by Using Zeolite in a Station of Depuration.

Science.gov (United States)

Gdoura, Morsi; Sellami, Hanen; Khannous, Lamia; Ketata, Najib; Neila, Idriss Ben; Traore, Al Ibrahim; Chekir, Zouhair; Gdoura, Radhouane

2017-09-01

  The application of natural zeolite for water and wastewater treatment has been carried out and is still a promising technique in environmental cleaning processes. Natural zeolite can be used to improve the purification process of clams (Ruditapes decussatus). Thus, our study aimed at improving the clam purification system in order to reduce Escherichia coli and eliminate Salmonella in samples artificially contaminated with this bacterium using a natural zeolite to replace the biological filter. The results showed that zeolite used in a depuration system improved the clam purification process. Moreover, natural zeolite exhibited high performance in the adsorption of bacteria and allowed to reduce the Escherichia coli abundance in 24 h, thus ensuring purified clams conformity with the ISO 16649-3 standard. These results indicate the beneficial effects of using zeolite in the adsorption of bacteria and the reduction in the abundance of Escherichia coli and set the Salmonella from marine organisms.

In situ studies with Asian clams (Carbacula fluminea) detect acid mine drainage and nutrient inputs in low-order streams

International Nuclear Information System (INIS)

Soucek, D. J.; Schmidt, T. S.; Cherry, D. S.

2001-01-01

This study evaluates the correlation between transplanted Asiatic clam and indigenous community responses to acid mine drainage and nutrient loading in first-to-third-order streams, by comparing the toxicological endpoints of clam survival and growth with benthic macro-invertebrate community indices as community responses to both acid mine drainage and nutrient loading. Clam survival was found to be positively correlated with water column pH and negatively correlated with conductivity and metal concentrations. There was also a positive correlation with the relative abundance of the macro-invertebrate Ephemeroptera, the most sensitive taxonomic group, to acid mine drainage in this watershed. No correlation was found between clam growth and acid mine drainage inputs, but there was evidence of positive correlation with nitrate concentrations and the relative abundance of collector-filterer functional feeding groups. These results suggest that clam growth is related to nutrient levels and accurately reflect benthic macro-invertebrate responses to nutrient loading. 28 refs., 5 tabs., 1 fig

Allozyme electrophoresis as a tool for distinguishing different zooxanthellae symbiotic with giant clams

Science.gov (United States)

Baillie, B. K.; Monje, V.; Silvestre, V.; Sison, M.; Belda-Baillie, C. A.

1998-01-01

The taxonomy of zooxanthellae in marine invertebrate symbioses is not well understood owing mainly to their lack of reliable morphological differences. Nevertheless, previous work using protein and DNA electrophoreses has set the stage for advancing our taxonomic understanding of cnidarian zooxanthellae. Here we present the use of allozymes as genetic markers for distinguishing algal isolates from tridacnid hosts. Zooxanthellae from seven Tridacna and Hippopus species were isolated and maintained in axenic clonal cultures over many generations. Of 16 enzyme systems, α- and β-esterase (EST), esterase-F (EST-F), glucose phosphate isomerase (GPI), and malate dehydrogenase (MDH) were found suitable polymorphic markers of genetic differences among clonal cultures. Of 39 clonal isolates, 97% were found to be genetically distinguishable. This high extent of genetic variation in zooxanthellae within and between clam species was unexpected, and is difficult to explain based solely on the general notion of asexual reproduction in symbiotic zooxanthellae. Our results are also consistent with the occurrence of sexual reproduction in clam zooxanthellae. The close genetic similarity of the symbionts of Tridacna gigas, the largest and fastest-growing clam species, and the difficulty of initiating their clonal cultures in the given nutrient medium, compared with the symbionts of other clam species, are further indicative of possibly distinct algal symbionts in T. gigas. These findings are discussed in light of current taxonomic understanding of these organisms.

Reproduction and recruitment patterns of the surf clam Donax serra ...

African Journals Online (AJOL)

Reproduction and recruitment patterns of the surf clam Donax serra (Bivalvia, Donacidae) on two ... Keywords: condition index, Donax serra, histology, Namibia, recruitment, reproduction, sandy beach ecology ... AJOL African Journals Online.

Susceptibility of Several Common Subtropical Weeds to Meloidogyne arenaria, M. incognita, and M. javanica.

Science.gov (United States)

Kokalis-Burelle, Nancy; Rosskopf, Erin N

2012-06-01

Experiments were conducted in the greenhouse to assess root galling and egg production of three root-knot nematode species, Meloidogyne arenaria, M. incognita, and M. javanica, on several weeds common to Florida agricultural land. Weeds evaluated were Amaranthus retroflexus (redroot pigweed), Cyperus esculentus (yellow nutsedge), Eleusine indica (goosegrass), Portulaca oleracea (common purslane), and Solanum americanum (American black nightshade). Additionally, although it is recommended as a cover crop in southern regions of the U.S., Aeschynomene americana (American jointvetch) was evaluated as a weed following the detection of root galling in a heavy volunteer infestation of an experimental field in southeastern Florida. Weeds were propagated from seed and inoculated with 1000 nematode eggs when plants reached the two true-leaf stage. Tomato (Solanum lycopersicum 'Rutgers') was included as a positive control. Aeschynomene americana and P. oleracea roots supported the highest number of juveniles (J2) and had the highest number of eggs/g of root for all three species of Meloidogyne tested. However, though P. oleracea supported very high root levels of the three nematode species tested, its fleshy roots did not exhibit severe gall symptoms. Low levels of apparent galling, combined with high egg production, increase the potential for P. oleracea to support populations of these three species of root-knot nematodes to a degree that may not be appropriately recognized. This research quantifies the impact of P. oleracea as a host for M. arenaria, M. incognita, and M. javanica compared to several other important weeds commonly found in Florida agricultural production, and the potential for A. americana to serve as an important weed host of the three species of root-knot nematode tested in southern regions of Florida.

Effects of clam size, food type, sediment characteristic, and seawater carbonate chemistry on grazing capacity of Venus clam Cyclina sinensis (Gmelin, 1791)

Science.gov (United States)

Lin, Tingting; Zhou, Kai; Liu, Xin; Lai, Qifang; Zhang, Dong; Shi, Liyan

2017-09-01

Aquaculture in saline-alkaline water has a major problem: microalgal blooming causes the pH of water to increase dramatically, thereby causing damage to the reared organisms. To solve this problem, we set out to find a candidate filter-feeding bivalve species suitable for saline-alkaline water to graze on microalgae and to control the pH. In the current study, we investigated the effect of carbonate alkalinity (CA, 2.5, 10.0, and 20.0 meq/L) and pH (8.0, 8.5, and 9.0) on the grazing capacity (GC) of the clam Cyclina sinensis. Additionally, the effect of clam size (small, medium, and large) and microalgae species ( Nannochloropsis oculata, Chaetoceros müelleri, and Isochrysis galbana), and the effect of bottom sediment characteristic (mud, sandy mud, and muddy sand) and thickness (3 and 6 cm) were analyzed as well. The results show that the GC on I. galbana was the highest and small size had the maximum GC/ W ( W: wet weight including body and shells). No significant differences were observed between sediment type and thickness. Regarding CA and pH, a significant decrease in GC by the pH or by their interaction was found. The GC of C. sinensis was not greatly reduced in the treatments of pH≤8.5 and CA≤20.0, and also not affected by bottom sediment type, indicating that this clam is capable to manage microalgal concentrations and might be a candidate species for pH reduction in saline-alkaline water ponds.

Antimicrobial Activity of Diterpenes from Viguiera arenaria against Endodontic Bacteria

Directory of Open Access Journals (Sweden)

Carlos H. G. Martins

2011-01-01

Full Text Available Six pimarane-type diterpenes isolated from Viguiera arenaria Baker and two semi-synthetic derivatives were evaluated in vitro against a panel of representative microorganisms responsible for dental root canal infections. The microdilution method was used for the determination of the minimum inhibitory concentration (MIC and minimum bactericidal concentration (MBC against Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia, Prevotella buccae, Fusobacterium nucleatum, Bacteroides fragilis, Actinomyces naeslundii, Actinomyces viscosus, Peptostreptococcus micros, Enterococcus faecalis and Aggregatibacter actinomycetemcomitans. The compounds ent-pimara-8(14,15-dien-19-oic acid, its sodium salt and ent-8(14,15-pimaradien-3β-ol were the most active, displaying MIC values ranging from 1 to 10 μg mL-1. The results also allow us to conclude that minor structural differences among these diterpenes significantly influence their antimicrobial activity, bringing new perspectives to the discovery of new chemicals for use as a complement to instrumental endodontic procedures.

Bioaccumulation of hydrocarbons derived from terrestrial and anthropogenic sources in the Asian clam, Potamocorbula amurensis, in San Francisco Bay estuary

Science.gov (United States)

Pereira, Wilfred E.; Hostettler, Frances D.; Rapp, John B.

1992-01-01

An assessment was made in Suisun Bay, California, of the distributions of hydrocarbons in estuarine bed and suspended sediments and in the recently introduced asian clam, Potamocorbula amurensis. Sediments and clams were contaminated with hydrocarbons derived from petrogenic and pyrogenic sources. Distributions of alkanes and of hopane and sterane biomarkers in sediments and clams were similar, indicating that petroleum hydrocarbons associated with sediments are bioavailable to Potamocorbula amurensis. Polycyclic aromatic hydrocarbons in the sediments and clams were derived mainly from combustion sources. Potamocorbula amurensis is therefore a useful bioindicator of hydrocarbon contamination, and may be used as a biomonitor of hydrocarbon pollution in San Francisco Bay.

Release from native root herbivores and biotic resistance by soil pathogens in a new habitat both affect the alien Ammophila arenaria in South Africa

NARCIS (Netherlands)

Knevel, IC; Lans, T; Menting, FBJ; Hertling, UM; van der Putten, WH

2004-01-01

Many native communities contain exotic plants that pose a major threat to indigenous vegetation and ecosystem functioning. Therefore the enemy release hypothesis (ERH) and biotic resistance hypothesis (BRH) were examined in relation to the invasiveness of the introduced dune grass Ammophila arenaria

Statistical Optimization of Culture Variables for Enhancing Agarase Production by Dendryphiella arenaria Utilizing Palisada perforata (Rhodophyta) and Enzymatic Saccharification of the Macroalgal Biomass.

Science.gov (United States)

Gomaa, Mohamed; Hifney, Awatief F; Fawzy, Mustafa A; Abdel-Gawad, Khayria M

2017-12-01

Agarase is a promising biocatalyst for several industrial applications. Agarase production was evaluated by the marine fungus Dendryphiella arenaria utilizing Palisada perforata as a basal substrate in semi-solid state fermentation. Seaweed biomass, glucose, and sucrose were the most significant parameters affecting agarase production, and their levels were further optimized using Box-Behnken design. The maximum agarase activity was 7.69 U/mL. Agarase showed a degree of thermostability with half-life of 99 min at 40 °C, and declining to 44.72 min at 80 °C. Thermodynamics suggested an important process of protein aggregation during thermal inactivation. Additionally, the enzymatic saccharification of the seaweed biomass using crude agarase was optimized with respect to biomass particle size, solid/liquid ratio, and enzyme loadings. The amount of biosugars obtained after optimization was 26.15 ± 1.43 mg/g. To the best of our knowledge, this is the first report on optimization of agarase in D. arenaria.

Abundance of Vibrio cholerae, V. vulnificus, and V. parahaemolyticus in oysters (Crassostrea virginica) and clams (Mercenaria mercenaria) from Long Island sound.

Science.gov (United States)

Jones, Jessica L; Lüdeke, Catharina H M; Bowers, John C; DeRosia-Banick, Kristin; Carey, David H; Hastback, William

2014-12-01

Vibriosis is a leading cause of seafood-associated morbidity and mortality in the United States. Typically associated with consumption of raw or undercooked oysters, vibriosis associated with clam consumption is increasingly being reported. However, little is known about the prevalence of Vibrio spp. in clams. The objective of this study was to compare the levels of Vibrio cholerae, Vibrio vulnificus, and Vibrio parahaemolyticus in oysters and clams harvested concurrently from Long Island Sound (LIS). Most probable number (MPN)-real-time PCR methods were used for enumeration of total V. cholerae, V. vulnificus, V. parahaemolyticus, and pathogenic (tdh(+) and/or trh(+)) V. parahaemolyticus. V. cholerae was detected in 8.8% and 3.3% of oyster (n = 68) and clam (n = 30) samples, with levels up to 1.48 and 0.48 log MPN/g in oysters and clams, respectively. V. vulnificus was detected in 97% and 90% of oyster and clam samples, with median levels of 0.97 and -0.08 log MPN/g, respectively. V. parahaemolyticus was detected in all samples, with median levels of 1.88 and 1.07 log MPN/g for oysters and clams, respectively. The differences between V. vulnificus and total and pathogenic V. parahaemolyticus levels in the two shellfish species were statistically significant (P oysters than in hard clams. Additionally, the data suggest differences in vibrio populations between shellfish harvested from different growing area waters within LIS. These results can be used to evaluate and refine illness mitigation strategies employed by risk managers and shellfish control authorities. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

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.

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

Science.gov (United States)

Watson, Sue-Ann

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 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.

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.

Influence of particle characteristics and organic matter content on the bioavailability and bioaccumulation of pyrene by clams

International Nuclear Information System (INIS)

Verrengia Guerrero, N.R.; Taylor, M.G.; Wider, E.A.; Simkiss, K.

2003-01-01

An experimental model with artificial particles and humic acids describes bioavailability of sediment-bound pyrene to clams. - Hydrophobic chemicals are known to associate with sediment particles including those from both suspended particulate matter and bottom deposits. The complex and variable composition of natural particles makes it very difficult therefore, to predict the bioavailability of sediment-bound contaminants. To overcome these problems we have previously devised a test system using artificial particles, with or without humic acids, for use as an experimental model of natural sediments. In the present work we have applied this experimental technique to investigate the bioavailability and bioaccumulation of pyrene by the freshwater fingernail clam Sphaerium corneum. The uptake and accumulation of pyrene in clams exposed to the chemical in the presence of a sample of natural sediment was also investigated. According to the results obtained, particle surface properties and organic matter content are the key factors for assessing the bioavailability and bioaccumulation of pyrene by clams

Diversity of lactic acid bacteria in sian-sianzih (fermented clams), a traditional fermented food in Taiwan.

Science.gov (United States)

Chen, Yi-sheng; Wu, Hui-chung; Li, Ya-han; Leong, Kun-hon; Pua, Xiao-hui; Weng, Ming-kai; Yanagida, Fujitoshi

2012-01-30

Sian-sianzih (fermented clams) is a popular traditional fermented food in Taiwan. The lactic acid bacteria (LAB) microflora in sian-sianzih have not been studied in detail. In this study, LAB from sian-sianzih were isolated, characterized and identified. A total of 186 cultures of LAB were isolated from seven sian-sianzih samples and 29 cultures were isolated from its main raw substrate: clams. The identification results revealed up to 11 distinct bacterial species belonging to five genera in sian-sianzih, and three species belonging to two genera in clams. The most common bacterial genera in sian-sianzih were Lactobacillus and Weissella, followed by Leuconostoc, Pediococcus and Lactococcus. A regional similarity in LAB, with differences in diversity, was observed in the current study. On the other hand, Lactococcus lactis subsp. lactis was the most common species found in raw clam samples. The results also suggested that greater LAB diversity could be observed in wild clams than in cultured ones. Furthermore, antibacterial activities of the isolates were determined, and one Weisella hellenica strain showed inhibitory activity against the indicator strain Lactobacilluas sakei JCM 1157(T) . A sensory assessment of seven sian-sianzih samples was also performed and the results indicated that diversity of LAB has a great effect on its aroma and taste formation. The results demonstrate that various LAB species are distributed in sian-sianzih and have a great effect on the flavor of sian-sianzih. Copyright © 2011 Society of Chemical Industry.

Effect of post-weld heat treatment on the mechanical properties of CLAM/316L dissimilar joint

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junyu [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); Huang, Bo [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Wu, Qingsheng, E-mail: qingsheng.wu@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; Huang, Qunying [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

2015-11-15

Highlights: • Dissimilar joints between CLAM and 316L steels welded by TIG were investigated. • After PWHTs, the hardening in HAZ on the CLAM steel side decreased remarkably. • Tempering at 740 °C for 2 h was considered as the preferable treatment rule. - Abstract: Dissimilar welding between China low activation martensitic (CLAM) steel and 316L austenitic stainless steel was investigated to achieve the reliable connection between test blanket modules (TBMs) and piping system in the international thermonuclear experimental reactor (ITER). The dissimilar joints were welded by tungsten inert gas (TIG) welding process with a filler material type-309. In order to stabilize the microstructure and improve the strength and toughness, post-weld heat treatments (PWHTs) of tempering at 740 °C, 780 °C and 820 °C, respectively, for 2 h were performed. The microstructure observation showed that tempering at 740 °C for 2 h was the preferable PWHT rule in this work. After the treatment, the hardening in heat affected zone (HAZ) on the CLAM steel side decreased remarkably. The tensile strength of the joint was roughly the same as that of the base metal. The impact toughness of HAZ on the CLAM steel side was 77% of that of the base metal. The absorbed energy of HAZ of 316L steel decreased by 93 J, and that of weld metal (WM) was 110 J after the treatment.

Corrosion behavior of CLAM steel weldment in flowing liquid Pb-17Li at 480 °C

International Nuclear Information System (INIS)

Chen Xizhang; Shen Zheng; Chen Xing; Lei Yucheng; Huang Qunying

2011-01-01

Highlights: ► The research shows that the CLAM steel weldment have its own corrosion mechanism in liquid Pb-17Li alloy. The basic rule of the corrosion behaviour of weldments is that the coorosion rate decreases obviously with the increasing of exposed time. ► The weight loss of CLAM steel weldment is far higer than the base metal after exposed to Pb-17Li alloy. Corrosion has little effects on elements of weldment sample surfaces. And an easier corrosion area in the weld joint are found. ► A simple presumably corrosion behavior model is established. The model demonstrate that the easier corroded area will be formed when the direction of martensite laths form small-angle with the specimen surface, The easy corrosion area is the martensite lath area lack of Cr and distributes like laths, the cross-section area is 1 μm 2 to 4 μm 2, the existence of the easier corrosion area is one of the reasons that lead to the difference of the corrosion rate. - Abstract: CLAM (China Low Activation Martensitic) steel is considered as one of the candidate structural materials in liquid LiPb blanket concepts. Welding is one of the essential technologies for its practical application, CLAM steel weldment shows a great difference with base metal due to the effect of welding thermal cycle. In order to investigate the corrosion behavior and mechanism of CLAM weldments in liquid Pb-17Li, the experiments were performed by exposing the TIG weldment samples in flowing LiPb at 480 °C. The weight loss test of exposed specimens show that in 500 h, 1000 h dynamic conditions, corrosion resistance of CLAM steel weldment is poor, SEM analysis shows that the thicker martensite lath in weld area lead to higher corrosion amount, EDS results show that the influence of corrosion on surface elements is small, and surface corrosion is even, EDX analysis shows that the penetration of Pb-17Li does not exist in the joint. With the increasing of exposure time, the corrosion rate decreases

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

Species show varying levels of plasticity regarding morphology, physiology and behaviour in relation to their immediate environment, and several trait characteristics are habitat-dependent. Determining when and how the environmental context changes trait expression is of key importance...... for understanding the role of individual species for ecosystem functioning. The tellinid clam Macoma balthica can vary its feeding behaviour, shifting between deposit- and suspension-feeding. In order to study the context-dependency of this trophic plasticity in adult clams, we conducted an experiment assessing...... food uptake by using stable isotope signatures (delta C-13 and delta N-15). We transplanted individuals between and within two shallow bays differing in exposure (exposed sheltered) and sediment characteristics. Our results show that isotope signatures of clams differed between the two habitats...

Influence of Root Exudates and Soil on Attachment of Pasteuria penetrans to Meloidogyne arenaria.

Science.gov (United States)

Liu, Chang; Timper, Patricia; Ji, Pingsheng; Mekete, Tesfamariam; Joseph, Soumi

2017-09-01

The bacterium Pasteuria penetrans is a parasite of root-knot nematodes ( Meloidogyne spp.). Endospores of P. penetrans attach to the cuticle of second-stage juveniles (J2) and subsequently sterilize infected females. When encumbered by large numbers of spores, juveniles are less mobile and their ability to infect roots is reduced. This study looked at different factors that influence spore attachment of P. penetrans to the root-knot nematode Meloidogyne arenaria . Pretreatment of J2 with root exudates of eggplant ( Solanum melongena cv. Black beauty) reduced spore attachment compared with pretreatment with phosphate-buffered saline (PBS), suggesting that the nematode surface coat was altered or the spore recognition domains on the nematode surface were blocked. Spore attachment was equally reduced following exposure to root exudates from both host and nonhost plants for M. arenaria , indicating a common signal that affects spore attachment. Although phytohormones have been shown to influence the lipophilicity of the nematode surface coat, auxins and kinetins did not affect spore attachment compared with PBS. Root exudates reduced spore attachment more in sterilized soil than in natural soil. Sterilization may have eliminated microbes that consume root exudates, or altered the chemical components of the soil solution or root exudates. Root exudates caused a greater decrease in spore attachment in loamy sand than in a sandy loam soil. The sandy loam had higher clay content than the loamy sand, which may have resulted in more adsorption of compounds in the root exudates that affect spore attachment. The components of the root exudates could have also been modified by soil type. The results of this study demonstrate that root exudates can decrease the attachment of P. penetrans endospores to root-knot nematodes, indicating that when these nematodes enter the root zone their susceptibility to spore attachment may decrease.

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.

Numerical simulation and experimental study of CLAM T-shapes for fusion applications by hydroforming

International Nuclear Information System (INIS)

Guo Xunzhong; Tao Jie; Liu Hongbing; Li Ming

2010-01-01

The integral hydroforming process to prepare CLAM T-shapes for fusion applications was evaluated by means of numerical simulation. The paper firstly investigated the effect of different paths on the protrusion height and distribution of thickness thinning rate of T-shapes. Then, it discussed that the friction coefficient between die and tube blank played an important role in manufacturing high quality T-shapes. Subsequently, the practical hydroforming was performed based on the simulation results with the aid of special lubrication coatings with friction coefficient 0.07. It is obviously indicated that the simulation results agree well with the experimental ones in geometry size and wall thickness distribution. The results indicate that the numerical simulation guides the practical hydroforming of CLAM tube effectively and determines the actual cold forming process parameters rapidly. The sound CLAM T-shapes with proper geometry size and thickness distribution can be obtained by the optimal hydroforming process. (authors)

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

International Nuclear Information System (INIS)

Ju Hua; Wang Feng; Ha Yiming; Liu Shuliang

2009-01-01

The growth of pathogenic bacteria during storage and their D 10 values by irradiation in short necked clam were evaluated. The results showed that the D 10 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 60 Co 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)

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.

Composting clam processing wastes in a laboratory- and pilot-scale in-vessel system.

Science.gov (United States)

Hu, Zhenhu; Lane, Robert; Wen, Zhiyou

2009-01-01

Waste materials from the clam processing industry (offal, shells) have several special characteristics such as a high salinity level, a high nitrogen content, and a low C/N ratio. The traditional disposal of clam waste through landfilling is facing the challenges of limited land available, increasing tipping fees, and strict environmental and regulatory scrutiny. The aim of this work is to investigate the performance of in-vessel composting as an alternative for landfill application of these materials. Experiments were performed in both laboratory-scale (5L) and pilot-scale (120L) reactors, with woodchips as the bulking agent. In the laboratory-scale composting test, the clam waste and woodchips were mixed in ratios from 1:0.5 to 1:3 (w/w, wet weight). The high ratios resulted in a better temperature performance, a higher electrical conductivity, and a higher ash content than the low-ratio composting. The C/N ratio of the composts was in the range of 9:1-18:1. In the pilot-scale composting test, a 1:1 ratio of clam waste to woodchips was used. The temperature profile during the composting process met the US Environmental Protection Agency sanitary requirement. The final cured compost had a C/N ratio of 14.6, with an ash content of 167.0+/-14.1g/kg dry matter. In addition to the major nutrients (carbon, nitrogen, calcium, magnesium, phosphorus, potassium, sulfur, and sodium), the compost also contained trace amounts of zinc, manganese, copper, and boron, indicating that the material can be used as a good resource for plant nutrients.

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.

Accumulation of 210Po in Baltic invertebrates

International Nuclear Information System (INIS)

Skwarzec, B.; Falkowski, L.

1988-01-01

This paper presents the results of an investigation of the 210 Po contents of Baltic marine invertebrates. The 210 Po concentrations fall within the range 11.3-78.9 Bq kg -1 (dry wt), the higher values relating to polychaeta, priapulida and malacostraca and the lower levels to bivalvia. It is demonstrated that 210 Po is non-uniformly distributed within the isopod Mesidotea entomon and the bivalve Mya arenaria. The 210 Po contents of the internal organs decreasing in the order-hepatopancreas > alimentary tract > gill > muscle. Moreover, the results indicate the dominant role of the digestive organs of these invertebrates in controlling absorption and elimination of 210 Po. (author)

Distribution of 137Cs activities in clams, Tivela mactroidea collected along the northern coast of Venezuela and the island of Margarita

International Nuclear Information System (INIS)

LaBrecque, J.J.; Alfonso, J.A.; Cordoves, P.R.

2007-01-01

Clam meats were obtained directly from the fishermen on the beaches in front of where the clams were collected at eight sites; seven along the northern coast of Venezuela and one on the northern coast of the island of Margarita (Venezuela). Marine sediments were also collected in the same corresponding areas as the clams. 137 Cs was determined both in clam meats and the marine sediments by high resolution gamma-ray spectrometry employing a hyperpure germanium detector. About 5 kg portions of clam meats were washed and dried in the laboratory, before 500 cm 3 volumes were transferred and weighed in the measuring containers. Similarly, 500 cm 3 volumes of marine sediments that were dried and ground to pass a 85 μm sieve were transferred to the measuring containers. The samples were counted for 150,000 seconds of real time. The 137 Cs activity of the clam meats ranged from -1 (our detection limit) to 0.36 Bq x kg -1 (dried weigh). These values are all within the range of values considered for environmental fallout from the nuclear weapons tests. Finally, all the values for the corresponding marine sediments were below our detection limit of 0.1 Bq x kg -1 of 137 Cs (dried weigh). (author)

Wave actions and topography determine the small-scale spatial distribution of newly settled Asari clams Ruditapes philippinarum on a tidal flat

Science.gov (United States)

Nambu, Ryogen; Saito, Hajime; Tanaka, Yoshio; Higano, Junya; Kuwahara, Hisami

2012-03-01

There are many studies on spatial distributions of Asari clam Ruditapes philippinarum adults on tidal flats but few have dealt with spatial distributions of newly settled Asari clam (physical/topographical conditions on tidal flats. We examined small-scale spatial distributions of newly settled individuals on the Matsunase tidal flat, central Japan, during the low spring tides on two days 29th-30th June 2007, together with the shear stress from waves and currents on the flat. The characteristics of spatial distribution of newly settled Asari clam markedly varied depending on both of hydrodynamic and topographical conditions on the tidal flat. Using generalized linear models (GLMs), factors responsible for affecting newly settled Asari clam density and its spatial distribution were distinguished between sampling days, with "crest" sites always having a negative influence each on the density and the distribution on both sampling days. The continuously recorded data for the wave-current flows at the "crest" site on the tidal flat showed that newly settled Asari clam, as well as bottom sediment particles, at the "crest" site to be easily displaced. Small-scale spatial distributions of newly settled Asari clam changed with more advanced benthic stages in relation to the wave shear stress.

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

International Nuclear Information System (INIS)

Baldi, Franco; Gallo, Michele; Marchetto, Davide; Faleri, Claudia; Maida, Isabel; Fani, Renato

2013-01-01

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 −1 HgCl 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 with

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 [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

Microbiota and environmental stress: how pollution affects microbial communities in Manila clams.

Science.gov (United States)

Milan, M; Carraro, L; Fariselli, P; Martino, M E; Cavalieri, D; Vitali, F; Boffo, L; Patarnello, T; Bargelloni, L; Cardazzo, B

2018-01-01

Given the crucial role of microbiota in host development, health, and environmental interactions, genomic analyses focusing on host-microbiota interactions should certainly be considered in the investigation of the adaptive mechanisms to environmental stress. Recently, several studies suggested that microbiota associated to digestive tract is a key, although still not fully understood, player that must be considered to assess the toxicity of environmental contaminants. Bacteria-dependent metabolism of xenobiotics may indeed modulate the host toxicity. Conversely, environmental variables (including pollution) may alter the microbial community and/or its metabolic activity leading to host physiological alterations that may contribute to their toxicity. Here, 16s rRNA gene amplicon sequencing has been applied to characterize the hepatopancreas microbiota composition of the Manila clam, Ruditapes philippinarum. The animals were collected in the Venice lagoon area, which is subject to different anthropogenic pressures, mainly represented by the industrial activities of Porto Marghera (PM). Seasonal and geographic differences in clam microbiotas were explored and linked to host response to chemical stress identified in a previous study at the transcriptome level, establishing potential interactions among hosts, microbes, and environmental parameters. The obtained results showed the recurrent presence of putatively detoxifying bacterial taxa in PM clams during winter and over-representation of several metabolic pathways involved in xenobiotic degradation, which suggested the potential for host-microbial synergistic detoxifying actions. Strong interaction between seasonal and chemically-induced responses was also observed, which partially obscured such potentially synergistic actions. Seasonal variables and exposure to toxicants were therefore shown to interact and substantially affect clam microbiota, which appeared to mirror host response to environmental variation. It

Fracture toughness of China low activation martensitic (CLAM) steel at room temperature

Energy Technology Data Exchange (ETDEWEB)

Li, Kunfeng [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); Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn [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); Xu, Gang; Jiang, Siben [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

2014-04-15

Highlights: • The fracture toughness of CLAM steel at room temperature is 417.9 kJ/m{sup 2} measured by unloading compliance method according to the ASTM E1820-11. • The fracture toughness of CLAM steel at room temperature can be calculated on the basis of the fractal dimensions measured under plane strain conditions. The calculated result and relative error for this experiment are 454.6 kJ/m{sup 2} and 8.78% respectively. • The calculation method could be used to estimate the fracture toughness of materials with analysis of the fracture surface. - Abstract: The fracture toughness (J{sub IC}) of China low activation martensitic (CLAM) steel was tested at room temperature through the compact tension specimen, the result is 417.9 kJ/m{sup 2}, which is similar to the JLF-1 at same experimental conditions. The microstructural observation of the fracture surface shows that the fracture mode is a typical ductile fracture. Meanwhile, the fracture toughness is also calculated on the basis of the fractal dimension and the calculated result is 454.6 kJ/m{sup 2}, which is consistent well with the experimental result. This method could be used to estimate the fracture toughness of materials by analyzing of the fracture surface.

Impact of High Hydrostatic Pressure on the Shelling Efficacy, Physicochemical Properties, and Microstructure of Fresh Razor Clam (Sinonovacula constricta).

Science.gov (United States)

Xuan, Xiao-Ting; Cui, Yan; Lin, Xu-Dong; Yu, Jing-Feng; Liao, Xiao-Jun; Ling, Jian-Gang; Shang, Hai-Tao

2018-02-01

The effects of high hydrostatic pressure (HHP) treatments (200, 300, and 400 MPa for 1, 3, 5 and 10 min) on the shelling efficacy (the rate of shelling, the rate of integrity and yield of razor clam meat) and the physicochemical (drip loss, water-holding capacity, pH, conductivity, lipid oxidation, Ca 2+ -ATPase activity, myofibrillar protein content), microbiological (total viable counts) and microstructural properties of fresh razor clam (Sinonovacula constricta) were investigated. HHP treatments significantly (P hydrostatic pressure (HHP) is now well known as a nonthermal processing technology and becoming increasingly acknowledged. However, it has not been widely applied to shell seafood due to its uncertain influence on its quality and shelling property. This study could provide valuable information regarding the shelling efficacy, physicochemical properties, and microstructure of razor clam treated by HHP. And it demonstrated that HHP showed a positive impact on quality of razor clam treated by HHP. © 2018 Institute of Food Technologists®.

Clam bioaccumulation of Alkylphenols and Polyciclic aromatic hydrocarbons in the Venice lagoon under different pressures.

Science.gov (United States)

Ademollo, N; Patrolecco, L; Matozzo, V; Marin, M G; Valsecchi, S; Polesello, S

2017-11-15

Biota-Sediment Accumulation Factors (BSAFs) of nonylphenols (NPs) and polycyclic aromatic hydrocarbons (PAHs) in Ruditapes philippinarum from the Venice Lagoon (Italy) were determined with the aim to verify whether the routine biomonitoring studies are reliable in contaminated sites. Clams and sediments were collected in field campaigns (October 2003 to June 2004) in three sites of the Venice Lagoon. Results showed that Marghera and Campalto sediments were more contaminated by NPs and PAHs than Poveglia. Different trends were observed in the contamination of clams with the highest BSAFs found at Poveglia. BSAF trend appeared to be inversely related to the contaminant pressure on the sites. These results suggest that clam bioaccumulation is not always representative of the chemical pressure on aquatic biota. The direct correlation between sediment and biota concentrations in contaminated sites can be lost as a function of the site-specific conditions such as sediment toxicity and food availability. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

Pasteuria penetrans for Control of Meloidogyne incognita on Tomato and Cucumber, and M. arenaria on Snapdragon.

Science.gov (United States)

Kokalis-Burelle, Nancy

2015-09-01

Meloidogyne incognita and Meloidogyne arenaria are important parasitic nematodes of vegetable and ornamental crops. Microplot and greenhouse experiments were conducted to test commercial formulations of the biocontrol agent Pasteuria penetrans for control of M. incognita on tomato and cucumber and M. arenaria on snapdragon. Three methods of application for P. penetrans were assessed including seed, transplant, and post-plant treatments. Efficacy in controlling galling and reproduction of the two root-knot nematode species was evaluated. Seed treatment application was assessed only for M. incognita on cucumber. Pasteuria treatment rates of a granular transplant formulation ranged from 1.5 × 10(5) endospores/cm(3) to 3 × 10(5) endospores/cm(3) of transplant mix applied at seeding. Additional applications of 1.5 × 10(5) endospores/cm(3) of soil were applied as a liquid formulation to soil post-transplant for both greenhouse and microplot trials. In greenhouse cucumber trials, all Pasteuria treatments were equivalent to steamed soil for reducing M. incognita populations in roots and soil, and reducing nematode reproduction and galling. In cucumber microplot trials there were no differences among treatments for M. incognita populations in roots or soil, eggs/g root, or root condition ratings. Nematode reproduction on cucumber was low with Telone II and with the seed treatment plus post-plant application of Pasteuria, which had the lowest nematode reproduction. However, galling for all Pasteuria treatments was higher than galling with Telone II. Root-knot nematode control with Pasteuria in greenhouse and microplot trials varied on tomato and snapdragon. Positive results were achieved for control of M. incognita with the seed treatment application on cucumber.

Gametogenic development and spawning of the mud clam, Polymesoda erosa (Solander, 1876) at Chorao Island, Goa

Digital Repository Service at National Institute of Oceanography (India)

Clemente, S.; Ingole, B.S.

islands of tropical and sub-tropical regions (Meehan 1982). Given the extensive use of the mangrove clam in the diet of many tropical islanders, the potential exists to exploit this clam commercially. An under- standing of the reproductive biology...: baban@nio.org Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark Marine Biology Research, 2009; 5: 109C1121 (Accepted 12 June 2008...

Freshwater Clams (Pilsbryoconcha Exilis) as an Potential Local Mineral Sources in Weaning Food to Overcome Stunting in Grobogan, Central Java, Indonesia

Science.gov (United States)

Putri, S. R.; Anjani, Gemala; Wijayanti, Hartanti Sandi; Nuryanto

2018-02-01

Based on a preliminary survey in Grobogan Central Java, one of the local food that has a prospective nutrient content developed is freshwater clams. Results of PSG report in 2015, especially in Grobogan district with stunting problem of 31.5% consisting of 7.2% very short and 24.1% short. From the stunting event factor, the role of weaning food in the form of baby porridge is the most important component in the fulfillment of infant nutrition. The research is divided into two stages of the research is the initial stage to make the formulation process by way of freshwater clams, nutrient analysis, and formula calculation. The second stage is the process of formulation weaning food by way of formula making, nutrient analysis, and acceptance test of weaning food on the baby slurry is substituted by the freshwater clams. The influence statistically different substitution of freshwater clams on protein content (p=0.014), fat (p=0,041), carbohydrate (p=0,039), water (p=0,0001), ash (p=0.0001), iron (p=0.0001), and zinc (p=0.0001). There is no influence substitution of freshwater clams on energy content (p=0,129) and fiber (p=0,225). The percentage of favorite level on the acceptance test of color (p=0,005) and taste (p=0,006) was statistically different, but there was no difference flavour (p=0,913) and texture (p=0,198). freshwater clams flour is rich in iron and zinc content, so it can serve as local food, especially in Grobogan Central Java as a stunting handling. Obtained from the results of several formulations substituted of freshwater clams in formulation 2 is a formula that can meet the standards of KEPMENKES except on the content of protein and moisture content. Formula 2 acceptable to the panelists, except for the assessment of taste.

Allometric relationships in the bioconcentration of heavy metals by the edible tropical clam Gafrarium tumidum

International Nuclear Information System (INIS)

Hedouin, L.; Metian, M.; Teyssie, J.-L.; Fowler, S.W.; Fichez, R.; Warnau, M.

2006-01-01

Although metal contamination is a problem of major concern in the lagoon of New Caledonia due to intense mining activities conducted on land, very little is known on the metal ecotoxicology of local marine organisms. The clam Gafrarium tumidum was investigated to assess its usefulness as a bioindicator species of metal contamination in this lagoon. More particularly, allometric relationships between metal accumulation and clam size were determined for five common metals in New Caledonian lagoon waters (Cd, Cr, Co, Zn and Ag) using a highly sensitive radiotracer technique. Experimental results showed that allometric relationships were dependent on the element and on the body compartment considered. As a rule, allometric relationships of metal concentration factor were more pronounced in shell than in soft parts. Significant relationships with clam size for Cd, Cr, Co and Zn followed inverse power functions. In contrast, the degree of Ag bioaccumulation was positively correlated with size. In view of the literature on Ag in bivalves, the latter observation suggests the occurrence of a specific detoxification mechanism (sequestration) that would be more efficient in old individuals. Overall, the experimental results indicate that the use of G. tumidum as a bioindicator in monitoring programmes requires selecting individuals of a specific size range in order to obtain comparable information about ambient metal levels. Since the size effect is greatest among smaller individuals, it is recommended to select clams with a shell width greater than 35 mm

Allometric relationships in the bioconcentration of heavy metals by the edible tropical clam Gafrarium tumidum

Energy Technology Data Exchange (ETDEWEB)

Hedouin, L. [International Atomic Energy Agency-Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 Monaco (Monaco); Laboratoire de Biologie et d' Environnement Marins, FRE 2727, La Rochelle University, 22 Av. Michel Crepeau, F-17000 La Rochelle (France); Institut de Recherche pour le Developpement, Centre d' Oceanologie de Marseille, Station Marine d' Endoume, Rue de la Batterie des Lions, F-13007 Marseille (France); Metian, M. [International Atomic Energy Agency-Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 Monaco (Monaco); Teyssie, J.-L. [International Atomic Energy Agency-Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 Monaco (Monaco); Fowler, S.W. [International Atomic Energy Agency-Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 Monaco (Monaco); Fichez, R. [Institut de Recherche pour le Developpement, Centre d' Oceanologie de Marseille, Station Marine d' Endoume, Rue de la Batterie des Lions, F-13007 Marseille (France); Warnau, M. [International Atomic Energy Agency-Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 Monaco (Monaco)]. E-mail: m.warnau@iaea.org

2006-07-31

Although metal contamination is a problem of major concern in the lagoon of New Caledonia due to intense mining activities conducted on land, very little is known on the metal ecotoxicology of local marine organisms. The clam Gafrarium tumidum was investigated to assess its usefulness as a bioindicator species of metal contamination in this lagoon. More particularly, allometric relationships between metal accumulation and clam size were determined for five common metals in New Caledonian lagoon waters (Cd, Cr, Co, Zn and Ag) using a highly sensitive radiotracer technique. Experimental results showed that allometric relationships were dependent on the element and on the body compartment considered. As a rule, allometric relationships of metal concentration factor were more pronounced in shell than in soft parts. Significant relationships with clam size for Cd, Cr, Co and Zn followed inverse power functions. In contrast, the degree of Ag bioaccumulation was positively correlated with size. In view of the literature on Ag in bivalves, the latter observation suggests the occurrence of a specific detoxification mechanism (sequestration) that would be more efficient in old individuals. Overall, the experimental results indicate that the use of G. tumidum as a bioindicator in monitoring programmes requires selecting individuals of a specific size range in order to obtain comparable information about ambient metal levels. Since the size effect is greatest among smaller individuals, it is recommended to select clams with a shell width greater than 35 mm.

Ecotoxicological Effects of Chemical Contaminants Adsorbed to Microplastics in the Clam Scrobicularia plana

Directory of Open Access Journals (Sweden)

Sarit O'Donovan

2018-04-01

Full Text Available Although microplastics (MPs are distributed globally in the marine environment, a great deal of unknowns relating to their ecotoxicological effects on the marine biota remains. Due to their lipophilic nature, microplastics have the potential to adsorb persistent organic pollutants present in contaminated regions, which may increase their detrimental impact once assimilated by organisms. This study investigates the ecotoxicological effects of exposure to low-density polyethylene (LDPE microplastics (11–13 μm, with and without adsorbed contaminants (benzo[a]pyrene—BaP and perfluorooctane sulfonic acid—PFOS, in the peppery furrow shell clam, Scrobicularia plana. Environmentally relevant concentrations of contaminants (BaP−16.87 ± 0.22 μg g−1 and PFOS−70.22 ± 12.41 μg g−1 were adsorbed to microplastics to evaluate the potential role of plastic particles as a source of chemical contamination once ingested. S. plana were exposed to microplastics, at a concentration of 1 mg L−1, in a water-sediment exposure setup for 14 days. Clams were sampled at the beginning of the experiment (day 0 and after 3, 7, and 14 days. BaP accumulation, in whole clam tissues, was analyzed. A multi-biomarker assessment was conducted in the gills, digestive gland, and haemolymph of clams to clarify the effects of exposure. This included the quantification of antioxidant (superoxide dismutase, catalase, glutathione peroxidase and biotransformation (glutathione-S-transferases enzyme activities, oxidative damage (lipid peroxidation levels, genotoxicity (single and double strand DNA breaks, and neurotoxicity (acetylcholinesterase activity. Results suggest a potential mechanical injury of gills caused by ingestion of microplastics that may also affect the analyzed biomarkers. The digestive gland seems less affected by mechanical damage caused by virgin microplastic exposure, with the MPs-adsorbed BaP and PFOS exerting a negative influence over the assessed

Intra-specific diet shift in manila clams (Ruditapes philippinarum) as revealed by carbon and nitrogen stable isotopes and fatty acid biomarker

Science.gov (United States)

Suh, Y.; Shin, K.

2011-12-01

Manila clams sampled in Seonjae Island, Korea with shell lengths (SL) below 19.76 mm in average showed a significantly depleted carbon and nitrogen isotope values (Pcultured in IFHRI. The result of fatty acid composition of manila clams in relation to size or growth rate suggests that fast growing clams would have rapid metabolism of fatty acids not required by the animals and an accumulation of the essential fatty acids (PUFA). In addition, their higher energy requirement and more active state of development would further diminish lipid reserve of the species.

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

Microstructure evolution of the oxide dispersion strengthened CLAM steel during mechanical alloying process

Energy Technology Data Exchange (ETDEWEB)

Song, Liangliang [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Science, Hefei, Anhui, 230031 (China); University of Science and Technology of China, Hefei, Anhui, 230031 (China); Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Science, Hefei, Anhui, 230031 (China); Mao, Xiaodong [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Science, Hefei, Anhui, 230031 (China)

2016-11-15

Highlights: • A nano-sized oxides dispersed ODS-CLAM steel was obtained by MA and HIP. • A minimum saturated grain size of down to 30 nm was achieved by varying the milling time from 0 to 100 h. • Solution of W in the MA powder could be significantly improved by increasing MA rotation speed. - Abstracts: Oxide dispersion strengthened Ferritic/Martensitic steel is considered as one of the most potential structural material for future fusion reactor, owing to its high mechanical properties and good irradiation resistance. The oxide dispersion strengthened China Low Activation Martensitic (ODS-CLAM) steel was fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP). The microstructural evolutions during the process of ball milling and subsequent consolidation were investigated by SEM, XRD and TEM. The results showed that increasing the milling time during the first 36 h milling could effectively decrease the grain size to a value of around 30 nm, over which grain sized remained nearly constant. Increasing the rotation speed promoted the solution of tungsten (W) element obviously and decreased the grain size to a certain degree. Observation on the consolidated and further heat-treated ODS-CLAM steel samples indicated that a martensite microstructure with a high density of nano-particles was achieved.

Effect of Meloidogyne arenaria and Mulch Type on Okra in Microplot Experiments.

Science.gov (United States)

Ritzinger, C H; McSorley, R; Gallaher, R N

1998-12-01

The effects of perennial peanut (Arachis glabrata) hay, an aged yard-waste compost (mainly woodchips), and a control treatment without amendment were determined on two population levels of root-knot (Melaidogyne arenaria) nematode over three consecutive years in field microplots. Okra (Hibiscus esculentus, susceptible to the root-knot nematode) and a rye (Secale cereale) cover crop (poor nematode host) were used in the summer and winter seasons, respectively. The organic amendment treatments affected plant growth parameters. In the first year, okra yields were greatest in peanut-amended plots. Yield differences with amendment treatment diminished in the second and third years. Okra plant height, total fruit weight, and fruit number were greater with the lower population level of the root-knot nematode. Residual levels of nutrients in soil were greater where root-knot nematode levels and damage were higher and plant growth was poor. Nutrient levels affected the growth of a subsequent rye cover crop.

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.

Enhanced trace element concentrations in tissues of the clam Ruditapes decussatus transplanted to areas influenced by human activities (Ria Formosa, Portugal

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Maria João Botelho

2017-06-01

Full Text Available To examine the extent to which human activities near the Ria Formosa coastal lagoon influence the accumulation of trace elements (TE in Ruditapes decussatus, individuals were transplanted from a natural bank located in the lower lagoon to three sites located in clam growth grounds under the influence of a small city (Faro, a fish farming centre (Olhão and a site near the lagoon inlet (Lavajo. Concentrations were determined in substrate of the clam grounds and in the digestive gland, gills, mantle plus siphons, and remaining tissues of clams in four periods of the year. These measurements were accomplished with the monthly survey of the gametogenic stages, condition index, proteins, glycogen, total lipids, pH and osmolarity of hemolymph. Arsenic, Cu, Mn, V, Cr and Pb were preferentially linked to the digestive gland, while Cd was linked to the gills. TE concentrations in the digestive gland and remaining tissues were higher in winter, most likely reflecting additional inputs associated with rain. The lack of disruptions in biological parameters and the prolonged period of spawning and gonad recovery in clams suggest that the current TE availability in the lagoon has a minor influence on the reproductive cycle and hence on clam production.

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)

Botelho, Maria João; Soares, Florbela; Matias, Domitília; Vale, Carlos

2015-01-01

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

Spectrophotometric evaluation of selenium binding by Saccharomyces cerevisiae ATCC MYA-2200 and Candida utilis ATCC 9950 yeast.

Science.gov (United States)

Kieliszek, Marek; Błażejak, Stanisław; Płaczek, Maciej

2016-05-01

In this study, the ability of selenium binding the biomas of Saccharomyces cerevisiae ATCC MYA-2200 and Candida utilis ATCC 9950 was investigated. Sodium selenite(IV) salts were added to the experimental media at concentrations of 10, 20, 40, and 60 mg Se(4+) L(-1). In the tested concentration range, one concentration reported a significant reduction in the biomass yield of both yeast strains. Intense growth was observed for C. utilis yeast, which reached the highest biomass yield of 15 gd.w.L(-1) after 24h cultivation in the presence of 10mg Se(4+) L(-1). Based on the use of spectrophotometric method for the determination of selenium content by using Variamine Blue as a chromogenic agent, efficient accumulation of this element in the biomass of the investigated yeast was observed. The highest amount of selenium, that is, 5.64 mg Se(4+)gd.w.(-1), was bound from the environment by S. cerevisiae ATCC MYA-2200 cultured in the presence of 60 mg Se(4+) L(-1) medium 72h Slightly less amount, 5.47 mg Se(4+) gd.w.(-1), was absorbed by C. utilis ATCC 9950 during similar cultural conditions. Based on the results of the biomass yield and the use of selenium from the medium, it can be observed that yeasts of the genus Candida are more efficient in binding this element, and this property finds practical application in the production of selenium-enriched yeast. Copyright © 2016 Elsevier GmbH. All rights reserved.

Variability characteristics and comparison of Carex arenaria L. and Carex ligerica Gay populations based on rhizome characters

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Lech Urbaniak

2014-01-01

Full Text Available The studies included 9 populations of Carex arenaria L. and 7 populations of Carex ligerica Gay, compared with each other on grounds of variability analysis, related to rhizome characters. The sedges reach in the area of Poland their eastern range limits, with isolated populations spread along the range margins. The studied plants were placed in a greenhouse in homogenous conditions,which made possible an analysis of genetic variability in the populations. The obtained results point to the absence of gene flow between the studied species and, thus, to their clearly distinct character. Genetic drift was postulated as one of the causes of the obtained variability pattern.

Cadmium sulfide quantum dots induce oxidative stress and behavioral impairments in the marine clam Scrobicularia plana.

Science.gov (United States)

Buffet, Pierre-Emmanuel; Zalouk-Vergnoux, Aurore; Poirier, Laurence; Lopes, Christelle; Risso-de-Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Perrein-Ettajani, Hanane; Valsami-Jones, Eugenia; Mouneyrac, Catherine

2015-07-01

Cadmium sulfide (CdS) quantum dots have a number of current applications in electronics and solar cells and significant future potential in medicine. The aim of the present study was to examine the toxic effects of CdS quantum dots on the marine clam Scrobicularia plana exposed for 14 d to these nanomaterials (10 µg Cd L(-1) ) in natural seawater and to compare them with soluble Cd. Measurement of labile Cd released from CdS quantum dots showed that 52% of CdS quantum dots remained in the nanoparticulate form. Clams accumulated the same levels of Cd regardless of the form in which it was delivered (soluble Cd vs CdS quantum dots). However, significant changes in biochemical responses were observed in clams exposed to CdS quantum dots compared with soluble Cd. Increased activities of catalase and glutathione-S-transferase were significantly higher in clams exposed in seawater to Cd as the nanoparticulate versus the soluble form, suggesting a specific nano effect. The behavior of S. plana in sediment showed impairments of foot movements only in the case of exposure to CdS quantum dots. The results show that oxidative stress and behavior biomarkers are sensitive predictors of CdS quantum dots toxicity in S. plana. Such responses, appearing well before changes might occur at the population level, demonstrate the usefulness of this model species and type of biomarker in the assessment of nanoparticle contamination in estuarine ecosystems. © 2015 SETAC.

Clam-Gallasův palác - emblematická architektura?

Czech Academy of Sciences Publication Activity Database

Konečný, Lubomír

2009-01-01

Roč. 28, - (2009), s. 91-98 ISSN 0231-7443. [Život pražských paláců. Praha, 09.10.2007-11.10.2007] Institutional research plan: CEZ:AV0Z80330511 Keywords : Clam-Gallas Palace * Johann Bernhard Fischer von Erlach * architecture * emblem s * imprints Subject RIV: AL - Art, Architecture, Cultural Heritage

Settlement, mortality and growth of the asari clam (Ruditapes philippinarum) for a collapsed population on a tidal flat in Nakatsu, Japan

Science.gov (United States)

Tezuka, Naoaki; Kamimura, Satomi; Hamaguchi, Masami; Saito, Hajime; Iwano, Hideki; Egashira, Junichi; Fukuda, Yuichi; Tawaratsumida, Takahiko; Nagamoto, Atsushi; Nakagawa, Koichi

2012-04-01

Although fluctuation and decline in bivalve populations have been reported worldwide, the underlying processes are not yet fully understood. This lack of understanding is partly due to an absence of demographic information for the early post-settlement period. This is the case particularly for annual production of the asari clam (also commonly known as the Manila clam, Ruditapes philippinarum) in Japan, which has greatly decreased in recent years. A remarkable decrease has been observed in the Nakatsu tidal flat, where current yields are less than 0.02% of the maximum yield. Possible explanations for this decline are: 1. limitation on recruitment due to overfishing; and 2. the demographic processes of growth and mortality have been altered by environmental changes, such as rise in seawater temperature or decrease in phytoplankton abundance. However, because of a lack of demographic information (e.g., the initial densities of larval settlement and mortality and growth rates post-settlement), the reasons for the decline, and the relative importance of each period in the life cycle in determining population abundance, remain unclear. Despite the decline, we observed high levels of recruitment of 0-year-class clams on the Nakatsu tidal flat in spring 2005, where more than 10,000 individuals m- 2 3-5 mm in shell length, estimated to have settled during the previous autumn, were observed. To obtain demographic information on the Nakatsu clams, we investigated two factors. First, we investigated the distribution of the 0-year-class clams and their rate of change in density as a combination of mortality, emigration and immigration on the whole tidal flat after a year. Second, we investigated the rate of change in the density and growth of clams after settlement in the center of the flat for 3 years. The rate of decrease in the density of the 0-year-class clams over the whole tidal flat after a year was greater at the stations where the initial density was higher. This

Sensitive PCR Detection of Meloidogyne arenaria, M. incognita, and M. javanica Extracted from Soil

Science.gov (United States)

Qiu, Jinya Jack; Westerdahl, Becky B.; Anderson, Cindy; Williamson, Valerie M.

2006-01-01

We have developed a simple PCR assay protocol for detection of the root-knot nematode (RKN) species Meloidogyne arenaria, M. incognita, and M. javanica extracted from soil. Nematodes are extracted from soil using Baermann funnels and centrifugal flotation. The nematode-containing fraction is then digested with proteinase K, and a PCR assay is carried out with primers specific for this group of RKN and with universal primers spanning the ITS of rRNA genes. The presence of RKN J2 can be detected among large numbers of other plant-parasitic and free-living nematodes. The procedure was tested with several soil types and crops from different locations and was found to be sensitive and accurate. Analysis of unknowns and spiked soil samples indicated that detection sensitivity was the same as or higher than by microscopic examination. PMID:19259460

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

International Nuclear Information System (INIS)

Spann, Nicole; Aldridge, David C.; Griffin, Julian L.; Jones, Oliver A.H.

2011-01-01

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

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

Bioavailability of polycyclic aromatic hydrocarbons (PAHs) to short-neck clam (Paphia undulata) from sediment matrices in mudflat ecosystem of the west coast of Peninsular Malaysia.

Science.gov (United States)

Keshavarzifard, Mehrzad; Zakaria, Mohamad Pauzi; Hwai, Tan Shau

2017-06-01

The bioaccumulation and bioavailability of polycyclic aromatic hydrocarbons (PAHs) were characterized in sediment and Paphia undulata (short-neck clam) from six mudflat areas in the west coasts of Peninsular Malaysia. The concentrations of total PAHs varied from 357.1 to 6257.1 and 179.9 ± 7.6 to 1657.5 ± 53.9 ng g -1 dry weight in sediment and short-neck clam samples, respectively. PAHs can be classified as moderate to very high level of pollution in sediments and moderate to high level of pollution in short-neck clams. The diagnostic ratios of individual PAHs and principal component analysis indicate both petrogenic and pyrogenic sources with significant dominance of pyrogenic source. The first PAHs biota-sediment accumulation factors and relative biota-sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. Evaluation of PAH levels in sediments and short-neck clams indicates that short-neck clam could be introduced as a good biomonitor in mudflats. The results also demonstrated that under environmental conditions, the sedimentary load of hydrocarbons appears to be one of the factors controlling their bioavailability to biota.

A novel approach for acid mine drainage pollution biomonitoring using rare earth elements bioaccumulated in the freshwater clam Corbicula fluminea.

Science.gov (United States)

Bonnail, Estefanía; Pérez-López, Rafael; Sarmiento, Aguasanta M; Nieto, José Miguel; DelValls, T Ángel

2017-09-15

Lanthanide series have been used as a record of the water-rock interaction and work as a tool for identifying impacts of acid mine drainage (lixiviate residue derived from sulphide oxidation). The application of North-American Shale Composite-normalized rare earth elements patterns to these minority elements allows determining the origin of the contamination. In the current study, geochemical patterns were applied to rare earth elements bioaccumulated in the soft tissue of the freshwater clam Corbicula fluminea after exposure to different acid mine drainage contaminated environments. Results show significant bioaccumulation of rare earth elements in soft tissue of the clam after 14 days of exposure to acid mine drainage contaminated sediment (ΣREE=1.3-8μg/gdw). Furthermore, it was possible to biomonitor different degrees of contamination based on rare earth elements in tissue. The pattern of this type of contamination describes a particular curve characterized by an enrichment in the middle rare earth elements; a homologous pattern (E MREE =0.90) has also been observed when applied NASC normalization in clam tissues. Results of lanthanides found in clams were contrasted with the paucity of toxicity studies, determining risk caused by light rare earth elements in the Odiel River close to the Estuary. The current study purposes the use of clam as an innovative "bio-tool" for the biogeochemical monitoring of pollution inputs that determines the acid mine drainage networks affection. Copyright © 2017 Elsevier B.V. All rights reserved.

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)

Arakawa, Jumpei; Sakamoto, Wataru

1998-01-01

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)

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

International Nuclear Information System (INIS)

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.

2015-01-01

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

Histopathology and stress biomarkers in the clam Venerupis philippinarum from the Venice Lagoon (Italy).

Science.gov (United States)

Boscolo Papo, Michele; Bertotto, Daniela; Quaglio, Francesco; Vascellari, Marta; Pascoli, Francesco; Negrato, Elena; Binato, Giovanni; Radaelli, Giuseppe

2014-07-01

The aim of this study was to evaluate the histomorphology and the stress response in the bivalve Venerupis philippinarum sampled in four differently polluted sites of the Venice Lagoon (Palude del Monte, Marghera, Ca' Roman and Val di Brenta). This species is often used as bioindicator of environmental pollution since it can bioaccumulate a large variety of pollutants because of its filter feeding. Chemical analyses for heavy metals (Cd, Cu, Hg and Pb) and polycyclic aromatic hydrocarbons (PAHs) were performed on whole soft tissues of V. philippinarum. The histological evaluation of clams revealed the presence of Perkinsus sp. infection in animals from all sites, although a very high prevalence of parasites was evidenced in clams from Ca' Roman. Perkinsus sp. were systemically distributed in the mantle, in the intestine and digestive gland, in gonads and gills. The trophozoites of Perkinsus sp. were found isolated or in cluster surrounded by a heavy hemocitical response. Haemocytes always exhibited an immunopositivity to cytochrome P4501A (CYP1A), heat shock protein 70 (HSP70), 4-hydroxy-2-nonenal (HNE) and nitrotyrosine (NT) antibodies. The digestive gland of animals from Palude del Monte showed the highest malondialdehyde (MDA) concentration, whereas clams from Ca' Roman exhibited the highest quantity of metallothioneins. Copyright © 2014 Elsevier Ltd. All rights reserved.

POLLINATOR-MEDIATED COMPETITION, REPRODUCTIVE CHARACTER DISPLACEMENT, AND THE EVOLUTION OF SELFING IN ARENARIA UNIFLORA (CARYOPHYLLACEAE).

Science.gov (United States)

Fishman, Lila; Wyatt, Robert

1999-12-01

Ecological factors that reduce the effectiveness of cross-pollination are likely to play a role in the frequent evolution of routine self-fertilization in flowering plants. However, we lack empirical evidence linking the reproductive assurance value of selfing in poor pollination environments to evolutionary shifts in mating system. Here, we investigated the adaptive significance of prior selfing in the polymorphic annual plant Arenaria uniflora (Caryophyllaceae), in which selfer populations occur only in areas of range overlap with congener A. glabra. To examine the hypothesis that secondary contact between the two species contributed to the evolution and maintenance of selfing, we used field competition experiments and controlled hand-pollinations to measure the female fitness consequences of pollinator-mediated interspecific interactions. Uniformly high fruit set by selfers in the naturally pollinated field arrays confirmed the reproductive assurance value of selfing, whereas substantial reductions in outcrosser fruit set (15%) and total seed production (20-35%) in the presence of A. glabra demonstrated that pollinator-mediated interactions can provide strong selection for self-pollination. Heterospecific pollen transfer, rather than competition for pollinator service, appears to be the primary mechanism of pollinator-mediated competition in Arenaria. Premating barriers to hybridization between outcrossers and A. glabra are extremely weak. The production of a few inviable hybrid seeds after heterospecific pollination and intermediate seed set after mixed pollinations indicates that A. glabra pollen can usurp A. uniflora ovules. Thus, any visit to A. uniflora by shared pollinators carries a potential female fitness cost. Moreover, patterns of fruit set and seed set in the competition arrays relative to controls were consistent with the receipt of mixed pollen loads, rather than a lack of pollinator visits. Competition through pollen transfer favors preemptive

Development of a Taqman real-time PCR assay for rapid detection and quantification of Vibrio tapetis in extrapallial fluids of clams

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Adeline Bidault

2015-12-01

Full Text Available The Gram-negative bacterium Vibrio tapetis is known as the causative agent of Brown Ring Disease (BRD in the Manila clam Venerupis (=Ruditapes philippinarum. This bivalve is the second most important species produced in aquaculture and has a high commercial value. In spite of the development of several molecular methods, no survey has been yet achieved to rapidly quantify the bacterium in the clam. In this study, we developed a Taqman real-time PCR assay targeting virB4 gene for accurate and quantitative identification of V. tapetis strains pathogenic to clams. Sensitivity and reproducibility of the method were assessed using either filtered sea water or extrapallial fluids of clam injected with the CECT4600T V. tapetis strain. Quantification curves of V. tapetis strain seeded in filtered seawater (FSW or extrapallial fluids (EF samples were equivalent showing reliable qPCR efficacies. With this protocol, we were able to specifically detect V. tapetis strains down to 1.125 101 bacteria per mL of EF or FSW, taking into account the dilution factor used for appropriate template DNA preparation. This qPCR assay allowed us to monitor V. tapetis load both experimentally or naturally infected Manila clams. This technique will be particularly useful for monitoring the kinetics of massive infections by V. tapetis and for designing appropriate control measures for aquaculture purposes.

Photosymbiotic Giant Clams are Transformers of Solar Flux

Science.gov (United States)

2014-01-01

function to forward-scatter light reflected from high albedo sand or from the highly reflec- tive clam shell itself (M. Lim 2014, personal communication...grains: aggregates made of crystalline water ice . Icarus 215, 682–694. (doi:10.1016/j.icarus.2011.04.011) 17. Denton EJ, Land MF. 1971 Mechanism of...2005.50.5.1490) 29. McFarland WN, Munz FW. 1975 Part II: the photic environment of clear tropical seas during the day. Vis. Res. 15, 1063–1070. (doi

Triangular gold nanoparticles modify shell characteristics and increase antioxidant enzyme activities in the clam Ruditapes decussatus.

Science.gov (United States)

Abdelhafidh, Khazri; Badreddine, Sellami; Mezni, Amine; Mouhamed, Dellali; Wiem, Saidani; Imen, Bouzidi; David, Sheehan; Mahmoudi, Ezzeddine; Hamouda, Beyrem

2018-04-19

Nanoparticles may cause adverse environmental effects but there is limited information on their interactions with marine organisms. Our aim was to examine the effects of triangular gold nanoparticles (Tr-Au NPs) on the clam, Ruditapes decussatus. Clams were exposed to Tr-Au1 = 5 µg/L and Tr-Au2 = 10 µg/L for 2 and 7 days. Effects on shell structure were investigated. Superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GST) activities, protein carbonyl levels and malondialdehyde content were used to assess biochemical status. Transmission electron microscopy (TEM) and electron dispersive X-ray microanalysis (EDX) showed that Tr-Au NPs modified shell structure and morphology. Tr-Au NPs size increased forming aggregate particles. Tr-Au NPs increased SOD, CAT and GST activities in gill and digestive gland in a concentration- and time-dependent manner indicating defence against oxidative stress. Enhanced lipid peroxidation and protein carbonyl levels confirmed oxidative stress. Tr-Au NPs cause oxidative stress and affect shell structure of clams. These findings may have relevance to other marine species.

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

2016-10-15

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. © 2016. Published by The Company of Biologists Ltd.

Acidified seawater increases accumulation of cobalt but not cesium in manila clam Ruditapes philippinarum.

Science.gov (United States)

Sezer, Narin; Kocaoğlan, Hasan Oğuz; Kılıç, Önder; Lacoue-Labarthe, Thomas; Belivermiş, Murat

2018-04-01

The pH of seawater around the world is expected to continue its decline in the near future in response to ocean acidification that is driven by heightened atmospheric CO 2 emissions. Concomitantly, economically-important molluscs that live in coastal waters including estuaries and embayments, may be exposed to a wide assortment of contaminants, including trace metals and radionuclides. Seawater acidification may alter both the chemical speciation of select elements as well as the physiology of organisms, and may thus pose at risk to many shellfish species, including the manila clam Ruditapes philippinarum. The bioconcentration efficiency of two common radionuclides associated with the nuclear fuel cycle, 134 Cs and 57 Co, were investigated by exposing live clams to dissolved 134 Cs and 57 Co at control (pH = 8.1) and two lowered pH (pH = 7.8 and 7.5) levels using controlled aquaria. The uptake and depuration kinetics of the two radionuclides in the whole-body clam were followed for 21 and 35 days, respectively. At steady-state equilibrium, the concentration factor (CF ss ) for 57 Co increased as the pH decreased (i.e. 130 ± 5, 194 ± 6, and 258 ± 10 at pH levels 8.1, 7.8 and 7.5, respectively), whereas the 134 Cs uptake was not influenced by a change in pH conditions. During depuration, the lowest depuration rate constant of 57 Co by the manila clam was observed at the intermediate pH of 7.8. An increase in the accumulation of 57 Co at the intermediate pH value was thought to be caused mainly by the aragonitic shell of the clam, as well as the low salinity and alkalinity of seawater used in the experiment. Considering that accumulation consists of uptake and depuration, among the three pH conditions moderately acidified seawater enhanced most the accumulation of 57 Co. Accumulation of 134 Cs was not strongly influenced by a reduced pH condition, as represented by an analogous uptake constant rate and CF ss in each treatment. Such results suggest that

Morphological and functional characterization of hemocytes from two deep-sea vesicomyid clams Phreagena okutanii and Abyssogena phaseoliformis.

Science.gov (United States)

Tame, Akihiro; Ozawa, Genki; Maruyama, Tadashi; Yoshida, Takao

2018-03-01

Deep-sea vesicomyid clams harboring intracellular symbiotic sulfur-oxidizing bacteria are often dominant in chemosynthetic animal communities. Although they are known to have erythrocytes, little is known about other hemocytes. To investigate the types and roles of various hemocytes in vesicomyid clams, we performed morphological, histochemical and functional characterization of the hemocytes in two species, Phreagena okutanii, collected from 873 to 978 m depth, and Abyssogena phaseoliformis, from 5199 to 5355 m. Both were found to have three types of hemocytes: erythrocytes (ERCs), eosinophilic granulocytes (EGs), and basophilic granulocytes (BGs). The ERCs contain hemoglobin in the cytoplasm, with basophilic vacuoles containing acid polysaccharide, neutral lipids, and peroxidase. The EGs were found to contain acid polysaccharides and eosinophilic granules containing lysosomal enzymes, acid and alkaline phosphatases, chloroacetate esterase, and peroxidase. Although BGs had some basophilic granules with alkaline phosphatase, they lacked acid phosphatase and acid polysaccharides. The EGs and BGs were shown to have phagocytic ability, while the ERCs exhibited no phagocytosis. The EGs showed higher phagocytic activity as well as a higher phagosome-lysosome fusion rate than BGs. The hemocytes of the two vesicomyid species differed in the intracellular structures. In A. phaseoliformis, ERCs additionally contained neutral polysaccharides in vacuoles and had vesicles with acinus-like acidic mucus in the cytoplasm, neither of which were observed in P. okutanii. The eosinophilic granules in the EGs had heteromorphically-elongated shapes containing homogeneously electron-dense material in P. okutanii, but were more spherical and composed of fibrous structures in A. phaseoliformis. The difference in hemocytes between the two clams seems to be reflective of phylogenetically differentiated lineages adapting to differing conditions in their respective deep-sea environments

Biomarker responses and contamination levels in the clam Ruditapes philippinarum for biomonitoring the Lagoon of Venice (Italy).

Science.gov (United States)

Matozzo, Valerio; Binelli, Andrea; Parolini, Marco; Locatello, Lisa; Marin, Maria Gabriella

2010-03-01

A multibiomarker approach was used to assess effects of environmental contaminants in the clam Ruditapes philippinarum from the Lagoon of Venice. Bivalves were collected in 8 sites of the Lagoon (Campalto, Marghera, Palude del Monte, Valle di Brenta, Cà Roman, San Servolo, Fusina and Canale Dese), differently influenced by both anthropogenic impact and natural conditions. The following biomarkers were chosen: total haemocyte count and lysozyme activity in cell-free haemolymph as immunomarkers, acetylcholinesterase activity in gills as a biomarker of exposure to neurotoxic compounds, vitellogenin-like protein levels in both digestive gland and cell-free haemolymph as a biomarker of exposure to estrogenic compounds, and survival-in-air widely used to evaluate general stress conditions in clams. In addition, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT) and its breakdown products (DDE, DDD), hexachlorobenzene (HCB) and hexachlorocyclohexane (HCH) were measured in clams. Results demonstrated that the integrated approach between biomarkers and chemical analyses in R. philippinarum is a useful tool in biomonitoring the Lagoon of Venice. The biomarker responses suggested quite similar contamination levels in the entire Lagoon, although the relative impact of differing classes of pollutants changed among sites according to potential sources, as chemical analyses demonstrated. Overall, among the sampling sites investigated, Palude del Monte can represent an environmental risk area, bearing in mind its peculiar use for clam culture.

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

Effect of weld spacing on microstructure and mechanical properties of CLAM electron beam welding joints

Energy Technology Data Exchange (ETDEWEB)

Zhai, Yutao; Huang, Bo, E-mail: aufa0007@163.com; Zhang, Junyu; Zhang, Baoren; Liu, Shaojun; Huang, Qunying

2016-11-15

Highlights: • The welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding, and a simplified model of CLAM sheet was proposed. • The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). • The effect of the welding thermal cycle was significantly when the weld spacings were smaller than 4 mm. • When the weld spacing was small enough, the original microstructures would be fragmented with the high heat input. - Abstract: China low activation martensitic (CLAM) steel has been chosen as the primary structural material in the designs of dual function lithium-lead (DFLL) blanket for fusion reactors, China helium cooled ceramic breeder (HCCB) test blanket module (TBM) for ITER and China fusion engineering test reactor (CFETR) blanket. The cooling components of the blankets are designed with high density cooling channels (HDCCs) to remove the high nuclear thermal effectively. Hence, the welding spacing among the channels are small. In this paper, the welded joints of CLAM steel with different weld spacings have been fabricated with electron beam welding (EBW). The weld spacing was designed to be 2 mm, 3 mm, 4 mm, 6 mm and 8 mm. The microstructure and mechanical properties such as microhardness, impact and tensile were investigated at different welding spacing for both conditions of as-welded and post weld heat treatment (PWHT). The PWHT is tempering at 740 °C for 120 min. The results showed that the grain size in the heat affected zone (HAZ) increased with the increasing weld spacing, and the joint with small weld spacing had a better performance after PWHT. This work would give useful guidance to improve the preparation of the cooling components of blanket.

Heavy metal concentrations in the razor clams (Solen spp.) from Muara Tebas, Sarawak

International Nuclear Information System (INIS)

Devagi Kanakaraju; Connie Jios; Shabdin Mohd Long

2008-01-01

The razor clams (Solen spp) or locally known as ambal in Sarawak collected from Muara Tebas were studied for their heavy metals contents in tissues and shells. Sediment samples were also tested for their metal contents. Concentrations of Pb, Fe, Zn, Cu, Cd and Mn were determined by using Flame Atomic Absorption Spectrophotometer (FAAS). Tissues of razor clams showed highest concentrations of Fe and Zn, while shells accumulated highest concentrations of Pb and Mn. The lowest metal concentrations found were Cu and Cd. In general, the levels of metals in ambal were within the permissible limit recommended by international standard, the Food and Agricultural Organization (FAO). However, the study revealed that the sediments at Muara Tebas fall under the category of slightly polluted (for Pb) when compared to the guidelines suggested by United States Environment Protection Agency (USEPA). (author)

Second generation wave energy device - the clam concept

Energy Technology Data Exchange (ETDEWEB)

Bellamy, N.W.

1981-01-01

A device concept is presented which has arisen from a system approach adopted by a research group with considerable experience in the discipline of wave energy. The Clam, which can be classified as a spine-based pneumatic terminator, is deemed to be a second generation wave energy device in that it tries to utilize system components already identified as attractive, while at the same time avoiding known problem areas. A working model of this wave power device at an engineering scale is discussed for trials in real waves. 3 refs.

Modeling habitat suitability of the invasive clam Corbicula fluminea in a Neotropical shallow lagoon, southern Brazil

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T. C. L. Silveira

Full Text Available Abstract This study aimed to model the habitat suitability for an invasive clam Corbicula fluminea in a coastal shallow lagoon in the southern Neotropical region (–30.22, –50.55. The lagoon (19km2, maximum deep 2.5m was sampled with an Ekman dredge in an orthogonal matrix comprising 84 points. At each sampling point, were obtained environmental descriptors as depth, organic matter content (OMC, average granulometry (Avgran, and the percentage of sand (Pcsand. Prediction performance of Generalized Linear Models (GLM, Generalized Additive Models (GAM and Boosted Regression Tree (BRT were compared. Also, niche overlapping with other native clam species (Castalia martensi, Neocorbicula limosa and Anodontites trapesialis was examined. A BRT model with 1400 trees was selected as the best model, with cross-validated correlation of 0.82. The relative contributions of predictors were Pcsand-42.6%, OMC-35.8%, Avgran-10.9% and Depth-10.8%. Were identified that C. fluminea occur mainly in sandy sediments with few organic matter, in shallow areas nor by the shore. The PCA showed a wide niche overlap with the native clam species C. martensi, N. limosa and A. trapesialis.

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)

Species biology and potential for controlling four exotic plants (Ammophila arenaria, Carpobrotus edulis, Cortaderia jubata and Gasoul crystallinum) on Vandenberg Air Force Base, California

Science.gov (United States)

Schmalzer, Paul A.; Hinkle, C. Ross

1987-01-01

Invasive exotic plants can displace native flora and modify community and ecosystem structure and function. Ammophila arenaria, Corpobrotus edulis, Cortaderia jubata, and Gasoul crystallinum are invasive plants present on Vandenberg Air Force Base, California, designated for study by the Environmental Task Force because of the perceived threat they represent to the native flora. Each plant's native habitat, how they came to be at Vandenberg, their propagation, and how they can be controlled is discussed.

Insights into the establishment of the Manila clam on a tidal flat at the southern end of an introduced range in Southern California, USA.

Directory of Open Access Journals (Sweden)

Drew M Talley

Full Text Available Coastal ecosystem modifications have contributed to the spread of introduced species through alterations of historic disturbance regimes and resource availability, and increased propagule pressure. Frequency of occurrence of the Manila clam (Venerupis phillipinarum, Veneridae in Southern California estuaries has increased from absent or sparse to common since the mid-1990s. Potential invasion vectors include seafood sales and aquaculture, and spread from established northern populations over decades. The clam's post-settlement habitat preferences are, however, uncertain in this region. Our project aimed to identify factors associated with established patches of the clam within a bay toward the southern end of this introduced range. During summer 2013, we sampled 10 tidal flat sites in Mission Bay, San Diego; each containing an area with and without hard structure (e.g., riprap, boulders. We measured likely environmental influences (e.g., sediment variables, distance to ocean. Manila clam densities across the bay were most strongly associated with site, where highest densities were located in the northern and/or back halves of the bay; and weakly correlated with lower porewater salinities. Within sites, Manila clam density was enhanced in the presence of hard structure in most sites. Prevailing currents and salinity regimes likely contribute to bay wide distributions, while hard structures may provide suitable microhabitats (refuge from predators and physical stress and larval entrapment within sites. Results provide insights into decisions about future shoreline management efforts. Finally, we identify directions for future study to better understand and therefore predict patterns of establishment of the Manila clam in the southern portion of its introduced range.

Tropomyosin and Actin Identified as Major Allergens of the Carpet Clam (Paphia textile and the Effect of Cooking on Their Allergenicity

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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.

Presence of enteric viruses, bioaccumulation and stability in Anomalocardia brasiliana clams (Gmelin, 1791).

Science.gov (United States)

Souza, Doris Sobral Marques; Dominot, Ana Ferreira Ávila; Moresco, Vanessa; Barardi, Célia Regina Monte

2018-02-02

Bivalve mollusks are filter feeders and may accumulate human pathogens in their tissues. Many studies demonstrated human diseases associated with bivalve consumption, especially oysters. Anomalocardia brasiliana clams are distributed along the Brazilian coastal area and are an exotic ingredient for some typical dishes in Brazil. Even though there are several reports describing the contamination of oysters and mussels with human pathogens, there is a lack of studies reporting contamination of A. brasiliana with human pathogens. An evaluation of natural microbiological contamination in A. brasiliana samples over a period of 18months (November 2014 to April 2016) showed that the bacteria indices were in accordance with Brazilian regulations (E. colitime period. NoV GI was the most adsorbed virus after 24h. HAV concentration was time, reaching its highest values after 24h (times (0, 1, 1.5, 3 and 5mins), viral infectivity was evaluated using ICC-et-RT-qPCR. The temperature inside the DT remained time and after 5min of cooking the HAdV reached a decay of 90% (1 log 10 ). The results showed a real warn to the consumers that can be exposed to infectious human viruses if they eat these clams improperly cooked. HAV was the most detected virus in these animals, which may lead to outbreaks. A. brasiliana exhibited distinct behavior in NoV GI bioaccumulation and persistence, pointing to the need for further studies about the cellular ligands used by these viruses to become attached to these clams. Copyright © 2017. Published by Elsevier B.V.

Total petroleum systems of the Trias/Ghadames Province, Algeria, Tunisia, and Libya; the Tanezzuft-Oued Mya, Tanezzuft-Melrhir, and Tanezzuft-Ghadames

Science.gov (United States)

Klett, T.R.

2000-01-01

Undiscovered conventional oil and gas resources were assessed within total petroleum systems of the Trias/Ghadames Province (2054) as part of the U.S. Geological Survey World Petroleum Assessment 2000. The Trias/Ghadames Province is in eastern Algeria, southern Tunisia, and westernmost Libya. The province and its total petroleum systems generally coincide with the Triassic Basin. The province includes the Oued Mya Basin, Melrhir Basin, and Ghadames (Berkine) Basin. Although several total petroleum systems may exist within each of these basins, only three “composite” total petroleum systems were identified. Each total petroleum system occurs in a separate basin, and each comprises a single assessment unit.The main source rocks are the Silurian Tanezzuft Formation (or lateral equivalents) and Middle to Upper Devonian mudstone. Maturation history and the major migration pathways from source to reservoir are unique to each basin. The total petroleum systems were named after the oldest major source rock and the basin in which it resides.The estimated means of the undiscovered conventional petroleum volumes in total petroleum systems of the Trias/Ghadames Province are as follows [MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids]:Tanezzuft-Oued Mya 830 MMBO 2,341 BCFG 110 MMBNGLTanezzuft-Melrhir 1,875 MMBO 4,887 BCFG 269 MMBNGLTanezzuft-Ghadames 4,461 MMBO 12,035 BCFG 908 MMBNGL

Fracture toughness and fracture behavior of CLAM steel in the temperature range of 450 °C-550 °C

Science.gov (United States)

Zhao, Yanyun; Liang, Mengtian; Zhang, Zhenyu; Jiang, Man; Liu, Shaojun

2018-04-01

In order to analyze the fracture toughness and fracture behavior (J-R curves) of China Low Activation Martensitic (CLAM) steel under the design service temperature of Test Blanket Module of the International Thermonuclear Experimental Reactor, the quasi-static fracture experiment of CLAM steel was carried out under the temperature range of 450 °C-550 °C. The results indicated that the fracture behavior of CLAM steel was greatly influenced by test temperature. The fracture toughness increased slightly as the temperature increased from 450 °C to 500 °C. In the meanwhile, the fracture toughness at 550 °C could not be obtained due to the plastic deformation near the crack tip zone. The microstructure analysis based on the fracture topography and the interaction between dislocations and lath boundaries showed two different sub-crack propagation modes: growth along 45° of the main crack direction at 450 °C and growth perpendicular to the main crack at 500 °C.

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.

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

International Nuclear Information System (INIS)

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

2014-01-01

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-dot 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

Prevalence and Density of Digenetic Trematode Metacercariae in Clams and Oysters from Western Coastal Regions of the Republic of Korea.

Science.gov (United States)

Sohn, Woon-Mok; Na, Byoung-Kuk; Cho, Shin-Hyeong; Lee, Won-Ja

2017-08-01

A survey was performed to know the recent infection status of digenetic trematode metacercariae in clams and oysters from 4 sites in western coastal regions of the Republic of Korea (=Korea). Four species of clams (Mactra veneriformis, Ruditapes philippinarum, Cyclina sinensis, and Saxidomus purpuratus) were collected from Taean-gun, Chungcheongnam-do (Province), Buan-gun (County) and Gochang-gun, Jeollabuk-do, and oysters, Crassostrea gigas, from Shinan-gun, Jeollanam-do were transferred to our laboratory on ice and examined by the artificial digestion method. The metacercariae of Himasthla alincia were detected in 3 species of clams, M. veneriformis, R. philippinarum, and C. sinensis from the 3 surveyed areas. The positive rate and the mean density per clam infected were 98.9% (30.8 metacercariae) in M. veneriformis, 60.0% (5.0) in R. philippinarum, and 96.0% (28.4) in C. sinensis. The positive rate (mean density) of Acanthoparyphium tyosenense metacercariae in M. veneriformis was 50.0% (2.1) from Taean-gun and 70.0% (2.8) from Gochang-gun. The metacercariae of Parvatrema spp. were detected in M. veneriformis and R. philippinarum from Taean-gun and Gochang-gun; the positive rate (mean density) was 63.3% (4,123) and 50.0% (19) in M. veneriformis, and 6.7% (126) and 100% (238) in R. philippinarum from the 2 regions, respectively. The metacercariae of Gymnophalloides seoi were detected in all 30 oysters from Shinan-gun, and their average density per oyster was 646. From the above results, it has been confirmed that more than 3 species of metacercariae are prevalent in clams from the western coastal regions, and G. seoi metacercariae are still prevalent in oysters from Shinan-gun, Jeollanam-do, Korea.

Shell Shape Analysis and Spatial Allometry Patterns of Manila Clam (Ruditapes philippinarum in a Mesotidal Coastal Lagoon

Directory of Open Access Journals (Sweden)

Nathalie Caill-Milly

2012-01-01

Full Text Available While gradual allometric changes of shells are intrinsically driven by genotype, morphometrical shifts can also be modulated by local environmental conditions. Consequently the common use of a unique dimension (usually length to assess bivalves’ growth may mask phenotypic differences in valve shape among populations. A morphometric exhaustive study was conducted on Manila clam, Ruditapes philippinarum, by acquiring data in the French Arcachon Bay (intrasite phenotypic variability and by comparing with other sites in the literature (intersite phenotypic variability. 2070 shells were subsampled, weighted, and automatically measured using TNPC software. Some ratios’ values indicate a relatively round and globular shape shell in comparison with other sites confirming poor conditions for some individuals. Among adult clams, three main morphological groups were identified and discussed according to spatial considerations. Allometric relations for pairs of shell descriptors were determined by testing classical linear and piecewise regression models on log-transformed relation of Huxley. A significant shape change correlated to size was observed; it corresponds to the second year of life of the clam. Relationships between density, disease, and shell shape are demonstrated and discussed related to other potential factors affecting shell shape. Finally, consequences on population regulation are addressed.

Prevalence of Vibrio parahaemolyticus in oyster and clam culturing environments in Taiwan.

Science.gov (United States)

Yu, Wei-Ting; Jong, Koa-Jen; Lin, Yu-Ren; Tsai, Shing-en; Tey, Yao Hsien; Wong, Hin-chung

2013-01-01

Vibrio parahaemolyticus is the most prevalent gastroenteritis pathogen in Taiwan and some other Asian countries, and it frequently occurs in oysters and other seafood. This study monitors changes in the density of V. parahaemolyticus and environmental parameters in oyster and hard clam aquacultural environments in Taiwan. Water, sediment and shellfish samples were collected from five sampling sites in 2008-2010, and analyzed for environmental physiochemical parameters, numbers of indicator bacteria (total aerobic counts, total coliforms and fecal coliforms), Vibrio and V. parahaemolyticus present. The results for open oyster farms and hard clam ponds did not differ significantly. V. parahaemolyticus was detected in 77.5, 77.5, 70.8 and 68.8% of the water, sediment, oyster and clam samples, respectively. The densities of V. parahaemolyticus were significantly higher in shellfish than in sediment or water samples, with mean values of 1.33, 1.04 and -0.02 Log CFU/g, respectively. Among these five sampling sites, Shengang and Fangyuan yielded significantly different data from those obtained at the other three sites. As determined by linear multiple regression, V. parahaemolyticus density in water samples depended significantly on the precipitation and Vibrio count, while the V. parahaemolyticus density in the sediment or shellfish samples depended significantly on the salinity of the seawater. Among 1076 isolates examined, a total of three putative pathogenic isolates were identified from 2.5% of the examined samples, and these isolates exhibited hemolytic or urease activities and the presence of gene markers for tdh, trh, type III secretion system (T3SS) 1 (vcrD1) or T3SS2α (vcrD2). The results herein may facilitate the assessment of risk associated with this pathogen in Taiwan and other geographically similar regions. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of Tantalum content on the low cycle fatigue properties of CLAM steel at 823 K

Energy Technology Data Exchange (ETDEWEB)

Zhai, Xiangwei [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); Liu, Shaojun, E-mail: shaojun.liu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Zhao, Yanyun; Wang, Kun [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

2017-01-15

Highlights: • The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. • The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles. • The grain size and M{sub 23}C{sub 6} were closely associated with the Ta content. • The crack distribution was quite sensitive to the Ta content. - Abstract: The effect of tantalum (Ta) content on the low cycle fatigue (LCF) properties of CLAM steel at 823 K was investigated in this paper. Low cycle fatigue tests were carried out on four ingots of CLAM steel with Ta contents of 0.027 wt%, 0.078 wt%, 0.15 wt% and 0.18 wt%, respectively. The results showed that the fatigue life and softening behavior of CLAM steel were influenced by Ta content. The fatigue life initially decreased and then increased as the Ta content was increased from 0.027 wt% to 0.18 wt%. The softening rate had declined with Ta content increased and the reduced softening rate was attributed to the increased number of Ta-rich MX particles.

Identification of larvae: The zebra mussel (Dreissena polymorpha), quagga mussel (Dreissena rosteriformis bugensis), and Asian clam (Corbicula fluminea)

Science.gov (United States)

Nichols, S. Jerrine; Black, M.G.

1994-01-01

There are presently four freshwater bivalves in the United States that produce larvae or veligers commonly found in the water column: two forms of Asian clams and two species of dreissenids. Portions of the geographic range of three of these bivalves, one species of Asian clam (Corbicula fluminea), zebra mussels (Dreissena polymorpha), and quagga mussels (Dreissena rosteriformis bugensis), overlap, causing problems with larval identification. To determine which characteristics can be used to separate larval forms, adult Asian clams, quaggas, and zebra mussels were brought into the laboratory and induced to spawn, and the resulting larvae were reared. Hybrids between quaggas and zebra mussels were also produced, but not reared to maturity. Characteristics allowing for the most rapid and accurate separation of larvae were hinge length, shell length/height, shell shape, shell size, and the presence or absence of a foot and velum. These characteristics were observed in laboratory-reared larvae of known parentage and field-caught larvae of unknown parentage. In most cases, larvae of the Asian clam can be readily separated from those produced by either type of dreissenid on the basis of shell size and presence of a foot. Separating the gametes and embryos of the two types of dreissenids is not possible, but after shell formation, most of the larval stages can be distinguished. Hinge length, shell length/height, and the similarity in size of the shell valves can be used to separate straight-hinged, umbonal, pediveliger, and plantigrade larvae. Quagga × zebra mussel hybrids show characteristics of both parents and are difficult to identify.

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.

Toxicity and the fractional distribution of trace metals accumulated from contaminated sediments by the clam Scrobicularia plana exposed in the laboratory and the field

International Nuclear Information System (INIS)

Kalman, J.; Bonnail-Miguel, E.; Smith, B.D.; Bury, N.R.; Rainbow, P.S.

2015-01-01

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

Effect of mining activities on the clam fisheries and bottom fauna of Goa estuaries

Digital Repository Service at National Institute of Oceanography (India)

Parulekar, A.H.; Ansari, Z.A.; Ingole, B.S.

Comparison of two clam beds and associated benthic fauna, in Mandovi and Cumbarjua canal estuarine system of Goa, India, severely affected by massive inputs of mining rejects, revealed that, in less than 10 years (1972-73 to 1982-83), high biotic...

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)

Torres, Z.; Bernuy, B.; Kahn, G.; Zapata, G.; Vivanco, M.; Guzman, E.; Leon, R.

2001-01-01

The radiation decimal reduction dose (D 10 ) 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 D 10 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)

Evaluation of entomopathogenic nematodes and the supernatants of the in vitro culture medium of their mutualistic bacteria for the control of the root-knot nematodes Meloidogyne incognita and M. arenaria.

Science.gov (United States)

Kepenekci, Ilker; Hazir, Selcuk; Lewis, Edwin E

2016-02-01

The suppressive effects of various formulations of four entomopathogenic nematode (EPN) species and the supernatants of their mutualistic bacteria on the root-knot nematodes (RKNs) Meloidogyne incognita and M. arenaria in tomato roots were evaluated. The EPNs Steinernema carpocapsae, S. feltiae, S. glaseri and Heterorhabditis bacteriophora were applied as either live infective juveniles (IJs) or infected insect cadavers. Spent medium from culturing the bacterial symbionts Xenorhabdus bovienii and Photorhabdus luminescens kayaii with the cells removed was also applied without their nematode partners. The aqueous suspensions of IJs, infected cadaver applications of EPNs and especially treatments of X. bovienii supernatant suppressed the negative impact of RKNs on tomatoes. Specific responses to treatment were reduced RKN egg masses, increased plant height and increased fresh and dry weights compared with the control where only RKNs were applied. Among the treatments tested, the plant-dipping method of X. bovienii into bacterial culture fluid may be the most practical and effective method for M. incognita and M. arenaria control. © 2015 Society of Chemical Industry.

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

Microcystin uptake and biochemical responses in the freshwater clam Corbicula leana P. exposed to toxic and non-toxic Microcystis aeruginosa: Evidence of tolerance to cyanotoxins.

Science.gov (United States)

Pham, Thanh-Luu; Shimizu, Kazuya; Dao, Thanh-Son; Hong-Do, Lan-Chi; Utsumi, Motoo

2015-01-01

We investigated the accumulation and adverse effects of toxic and non-toxic Microcystis in the edible clam Corbicula leana . Treated clams were exposed to toxic Microcystis at 100 μg of MC (microcystin)-LR eq  L -1 for 10 days. The experimental organism was then placed in toxin-free water and fed on non-toxic Microcystis for the following 10 days for depuration. Filtering rates (FRs) by C. leana of toxic and non-toxic Microcystis and of the green alga Chlorella vulgaris as a control were estimated. Adverse effects were evaluated though the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST). Clam accumulated MCs (up to 12.7 ± 2.5 μg g -1 dry weight (DW) of free MC and 4.2 ± 0.6 μg g -1 DW of covalently bound MC). Our results suggest that although both toxic and non-toxic cyanobacteria caused adverse effects by inducing the detoxification and antioxidant defense system, the clam was quite resistant to cyanotoxins. The estimated MC concentration in C. leana was far beyond the World Health Organization's (WHO) provisional tolerable daily intake (0.04 μg kg -1  day -1 ), suggesting that consuming clams harvested during cyanobacterial blooms carries a high health risk.

Microcystin uptake and biochemical responses in the freshwater clam Corbicula leana P. exposed to toxic and non-toxic Microcystis aeruginosa: Evidence of tolerance to cyanotoxins

Directory of Open Access Journals (Sweden)

Thanh-Luu Pham

2015-01-01

Full Text Available We investigated the accumulation and adverse effects of toxic and non-toxic Microcystis in the edible clam Corbicula leana. Treated clams were exposed to toxic Microcystis at 100 μg of MC (microcystin-LReq L−1 for 10 days. The experimental organism was then placed in toxin-free water and fed on non-toxic Microcystis for the following 10 days for depuration. Filtering rates (FRs by C. leana of toxic and non-toxic Microcystis and of the green alga Chlorella vulgaris as a control were estimated. Adverse effects were evaluated though the activity of catalase (CAT, superoxide dismutase (SOD and glutathione S-transferase (GST. Clam accumulated MCs (up to 12.7 ± 2.5 μg g−1 dry weight (DW of free MC and 4.2 ± 0.6 μg g−1 DW of covalently bound MC. Our results suggest that although both toxic and non-toxic cyanobacteria caused adverse effects by inducing the detoxification and antioxidant defense system, the clam was quite resistant to cyanotoxins. The estimated MC concentration in C. leana was far beyond the World Health Organization's (WHO provisional tolerable daily intake (0.04 μg kg−1 day−1, suggesting that consuming clams harvested during cyanobacterial blooms carries a high health risk.

Annual changes in abundance of non-indigenous marine benthos on a very large spatial scale

DEFF Research Database (Denmark)

Thomsen, Mads S.; Wernberg, Thomas; Stæhr, Peter Anton

2008-01-01

to quantify annual nation-wide changes in abundance of non-indigenous soft-bottom invertebrates (from grab samples) and hard-bottom macroalgae (from diver based percent cover values) in Denmark. Based on criteria of being either abundant (constituting >1% of the entire Danish assemblages) or increasing...... in abundance, NIMS of particular interest were found to be Mya arenaria and Bonemaissonia hamifera (abundant), Crepidula fornicata, Ensis americanus, Neanthes succinea (a cryptogenic species), Marenzelleria spp. (increasing), and Sargassum muticum (abundant and increasing). In addition, new and/or warm......-water eurohaline NIMS such as Gracilaria vermiculophylla and Crassostrea gigas, should be given attention as these species are expected to increase in the future. Finally, species not included in existing monitoring programs (hard-bottom estuarine invertebrates, fish, parasites, highly mobile species) should also...

Distribution of haemic neoplasia of soft-shelled clams in Prince Edward Island: an examination of anthropogenic factors and effects of experimental fungicide exposure.

Science.gov (United States)

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

2016-05-01

Haemic neoplasia was first considered a disease of concern for soft-shell clams in Prince Edward Island (PEI) when it was diagnosed as the cause of mass mortalities in 1999. The aetiology of the disease remains elusive, but has been associated with environmental degradation. In this study, a 2-year (2001-2002) geographic and seasonal survey was conducted for haemic neoplasia, using histology, in soft-shell clams from PEI. In addition, using geographic information system, the association between anthropogenic factors in the watersheds at sites affected by haemic neoplasia and the prevalence of the disease was investigated. Finally, histopathological changes were assessed in soft-shell clams experimentally exposed to four concentrations of chlorothalonil for 27 days. Haemic neoplasia could not be induced at any concentration of chlorothalonil. Clams exposed to a concentration of 1000 μg L(-1) of the fungicide, however, exhibited an LC50 of 17 days. Although this information provides additional toxicity information (LC50) for soft-shell clams, further experiments are required to assess longer term exposure to the fungicide. The highest prevalences of haemic neoplasia in PEI were found in North River and Miscouche (28.3-50.9% and 33.0-77.8%, respectively). No clear seasonal patterns were found. There was a correlation between haemic neoplasia prevalence and watersheds with a high percentage of potato acreage and forest coverage (P = 0.026 and P = 0.045, respectively), suggesting a link between anthropogenic activity and the prevalence of the disease. © 2015 John Wiley & Sons Ltd.

Age and growth of the sword razor clam Ensis arcuatus in the Ría de Pontevedra (NW Spain): Influence of environmental parameters

Science.gov (United States)

Hernández-Otero, A.; Gaspar, M. B.; Macho, G.; Vázquez, E.

2014-01-01

The sword razor clam Ensis arcuatus is the most important commercial species of razor clam in Spain, and its fishery in the Ría de Pontevedra (Galicia, NW Spain) is the most productive. Despite the economic importance of this species, information on its biology is scarce. This study reports shell morphometric relationships, age, and growth rates of E. arcuatus in three fishing beds in the Ría de Pontevedra (Brensa, Bueu and Ons, located in respectively the inner, middle and outer zones of the ria), providing the first estimates of growth parameters for the species in the Iberian Peninsula. Growth was estimated by examination of surface growth rings and internal shell microgrowth patterns (acetate peel technique) that proved to be the most suitable method for growth estimate. Growth of E. arcuatus was slower in Bueu (L∞ = 140.4, k = 0.40) followed by Brensa (L∞ = 151.91, k = 0.40) and Ons (L∞ = 172.7, k = 0.33), and the clams reached commercial size in 1.7, 2.3 and 2.8 years in Ons, Brensa and Bueu, respectively. The differences in growth between sites in relation to environmental parameters are evaluated and the implications for the razor clam fishery are discussed.

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

Atypical feeding behavior of Long-tailed Ducks in the wake of a commercial fishing boat while clamming

Science.gov (United States)

Perry, Matthew; Osenton, Peter C.; White, Timothy P.

2017-01-01

A foraging group of Clangula hyemalis (Long-tailed Duck) was observed on 10 February 2010 diving behind a commercial boat that was clamming near Monomoy Island, Nantucket Sound, MA. We used a shotgun to collect 9 of the ducks, and our analyses of gizzard and gullet (esophagus and proventriculus) revealed 37 food items in the gizzard and 16 in the gullet. Mollusca were the dominant food in the gizzard (49%), whereas Crustacea were dominant in the gullet (57%). Crustacea were the second most important food in the gizzard (38%), whereas Mollusca were the second most important food in the gullet (31%). Relatively high volumes of the Amphipoda Caprella sp. (skeleton shrimp) and the Decopoda Crangon septemspinosa (Sand Shrimp) were recorded in the gullet and gizzard. Ensis directus (Atlantic Jackknife Clam) formed the greatest volume of Mollusca in the gizzard (15%) and in the gullet (15%). Long-tailed Ducks had fed on this Bivalvia and several other species of Mollusca that had no shell or broken shell when consumed. Many of the food organisms were apparently dislodged and some damaged by the clamming operation creating an opportunistic feeding strategy for the Long-tailed Ducks.

Report on feasibility study of the Clam Wave Energy Device

Energy Technology Data Exchange (ETDEWEB)

1979-04-01

The main emphasis of the feasibility study has been towards producing an acceptable spine design for the Clam wave energy converter. Concrete and steel designs based on a mathematical model of the waveloading have been produced. Progress is also reported in the design of a bellows for a low-pressure air power transmission system. A narrow wave tank and scale model have been constructed in order to carry out a test programme on various aspects of the device's construction and performance.

A study of the naturalisation and dispersal of a non-native bivalve, the Manila clam, Ruditapes philippinarum (Adams and Reeve 1850) in estuaries along the South coast of England.

OpenAIRE

Harris, Matthew

2016-01-01

The Manila clam, Ruditapes philippinarum, was introduced into the British Isles in the 1980s for the purpose of aquaculture in order to take advantage of the rapid growth rate and high profitability of this non-native species. The decision to import the Manila clam, was based on the findings of a report commissioned by the Ministry of Agriculture Fisheries and Food which determined that the Manila clam would be able to be grown to marketable size faster than the local species Ruditapes decuss...

Compatibility of CLAM steel weldments with static LiPb alloy at 550 Degree-Sign C

Energy Technology Data Exchange (ETDEWEB)

Chen Xizhang, E-mail: kernel.chen@gmail.com [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Shen Zheng; Li Peng [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Madigan, Bruce [Montana Tech. of University of Montana, Butte, MT 59701 (United States); Huang Yuming; Lei Yucheng [School of Materials Science and Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China); Huang Qunying [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 031 (China); Zhou Jianzhong [School of Mechanical Engineering, Jiangsu University, ZhenJiang, Jiangsu 212013 (China)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Corrosion extent of weld zone is higher than that of HAZ. Black-Right-Pointing-Pointer Thick martensite lath and large residual stress lead to higher corrosion rate. Black-Right-Pointing-Pointer Cr on the surface of weld zone decreases by about 50%, W increases slightly. Black-Right-Pointing-Pointer After 500 h and 1000 h of corrosion, weight losses are 0.272 mg/cm{sup 2} and 0.403 mg/cm{sup 2}. Black-Right-Pointing-Pointer With the increasing of corrosion time, the corrosion rate decreases significantly. - Abstract: CLAM steel is considered as a structural material to be used in the Test Blanket Module as a barrier or blanket adjacent to liquid LiPb in fusion reactors. In this paper, CLAM steel is welded by tungsten inert gas (TIG) welding, and the compatibility of the weldment with liquid LiPb is tested. Specimens were corroded in static liquid LiPb, with corrosion times of 500 h and 1000 h, at 550 Degree-Sign C, and the corresponding weight losses are 0.272 mg/cm{sup 2} and 0.403 mg/cm{sup 2} respectively. Also the corrosion rate decreases with increased corrosion time. In the as-welded condition, corrosion resistance of the weld zone is higher than that of the HAZ (Heat Affected Zone). Likely, thick martensite lath and large residual stresses at the welding zone result in higher corrosion rates. The compatibility of CLAM steel weld joints with high temperature liquid LiPb can be improved to some extent through a post-weld tempering process. The surface of the as-welded CLAM steel is uniformly corroded and the concentration of Cr on the surface decreases by about 50% after corrosion. Penetration of LiPb into the matrix is observed for neither the as-welded nor the as-tempered conditions. Influenced by thick martensite lath and large residual stresses, the welded area, especially the weld zone, is easily corroded, therefore it is of primary importance to protect the welded area in the solid blanket of the fusion reactor.

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)

Freitas, Rosa; Almeida, Ângela; Calisto, Vânia; Velez, Cátia; Moreira, Anthony; Schneider, Rudolf J.; Esteves, Valdemar I.; Wrona, Frederick J.; Soares, Amadeu M.V. M.; Figueira, Etelvina

2015-01-01

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

Assessment of relationship between rainfall and Escherichia coli in clams (Chamelea gallina using the Bayes Factor

Directory of Open Access Journals (Sweden)

Cesare Ciccarelli

2017-08-01

Full Text Available Consumption of bivalve shellfish harvested from water contaminated with sewage pollution presents a risk of human infections and targeting control measures require a good understanding of environmental factors influencing the transport and the fate of faecal contaminants within the hydrological catchments. Although there has been extensive development of regression models, the point of this paper, focused on the relationship between rainfall events and concentrations of Escherichia coli monitored in clams, was the use of a Bayesian approach, by the Bayes Factor. The study was conducted on clams harvested from the south coast of Marche Region (Italy, a coastal area impacted by continuous treated effluents, intermittent rainfalldependent untreated sewage spillage - as a consequence of stormwater overflowing - and rivers with an ephemeral flow regime. The work compared the different interpretation criteria of Bayes Factor, confirmed that E. coli concentrations in clams from the studied area varied in correlation with rainfall events, and demonstrated the effectiveness of Bayes Factor in the assessment of shellfish quality in coastal marine waters. However, it suggested that further investigations would be warranted to determine which environmental factors provide the better basis for accurate and timely predictions. Furthermore the gathered data could be useful, to the local authorities of Marche Region, in the definition of flexible monitoring programmes, taking into account the atmospheric events that could affect the correct functioning of sewage managing systems and the flow of tributary rivers.

Risk-based approach to appraise valve closure in the clam Corbicula fluminea in response to waterborne metals

International Nuclear Information System (INIS)

Liao, C.-M.; Jou, L.-J.; Chen, B.-C.

2005-01-01

We developed a risk-based approach to assess how the valve closure behavior of Asiatic clam Corbicula fluminea responds to waterborne copper (Cu) and cadmium (Cd). We reanalyzed the valve closure response data from published literature to reconstruct the response time-dependent dose-response profiles based on an empirical three-parameter Hill equation model. We integrated probabilistic exposure profiles of measured environmental Cu and Cd concentrations in the western coastal areas of Taiwan with the reconstructed dose-response relationships at different integration times of response to quantitatively estimate the valve response risk. The risk assessment results implicate exposure to waterborne Cu and Cd may pose no significant risk to clam valve activity in the short-time response periods (e.g., <30 min), yet a relative high risk for valve closure response to waterborne Cu at response times greater than 120 min is alarming. We successfully linked reconstructed dose-response profiles and EC50-time relationships associated with the fitted daily valve opening/closing rhythm characterized by a three-parameter lognormal function to predict the time-varying bivalve closure rhythm response to waterborne metals. We parameterized the proposed predictive model that should encourage a risk-management framework for discussion of future design of biological monitoring systems. - A model was developed to link valve closure in clams to concentrations of metals in water

Characterisation of 12 microsatellite loci in the Vietnamese commercial clam Lutraria rhynchaena Jonas 1844 (Heterodonta: Bivalvia: Mactridae) through next-generation sequencing.

Science.gov (United States)

Thai, Binh Thanh; Tan, Mun Hua; Lee, Yin Peng; Gan, Han Ming; Tran, Trang Thi; Austin, Christopher M

2016-05-01

The marine clam Lutraria rhynchaena is gaining popularity as an aquaculture species in Asia. Lutraria populations are present in the wild throughout Vietnam and several stocks have been established and translocated for breeding and aquaculture grow-out purposes. In this study, we demonstrate the feasibility of utilising Illumina next-generation sequencing technology to streamline the identification and genotyping of microsatellite loci from this clam species. Based on an initial partial genome scan, 48 microsatellite markers with similar melting temperatures were identified and characterised. The 12 most suitable polymorphic loci were then genotyped using 51 individuals from a population in Quang Ninh Province, North Vietnam. Genetic variation was low (mean number of alleles per locus = 2.6; mean expected heterozygosity = 0.41). Two loci showed significant deviation from Hardy-Weinberg equilibrium (HWE) and the presence of null alleles, but there was no evidence of linkage disequilibrium among loci. Three additional populations were screened (n = 7-36) to test the geographic utility of the 12 loci, which revealed 100 % successful genotyping in two populations from central Vietnam (Nha Trang). However, a second population from north Vietnam (Co To) could not be successfully genotyped and morphological evidence and mitochondrial variation suggests that this population represents a cryptic species of Lutraria. Comparisons of the Qang Ninh and Nha Trang populations, excluding the 2 loci out of HWE, revealed statistically significant allelic variation at 4 loci. We reported the first microsatellite loci set for the marine clam Lutraria rhynchaena and demonstrated its potential in differentiating clam populations. Additionally, a cryptic species population of Lutraria rhynchaena was identified during initial loci development, underscoring the overlooked diversity of marine clam species in Vietnam and the need to genetically characterise population representatives prior

Phytoplankton growth balanced by clam and zooplankton grazing and net transport into the low-salinity zone of the San Francisco Estuary

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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.

Ecotoxicological and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Short-Neck Clam (Paphia undulata) and Contaminated Sediments in Malacca Strait, Malaysia.

Science.gov (United States)

Keshavarzifard, Mehrzad; Zakaria, Mohamad Pauzi; Sharifi, Reza

2017-10-01

The distribution, sources, and human health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediment and the edible tissue of short-neck clam (Paphia undulata) from mudflat ecosystem in the west coast of Malaysia were investigated. The concentrations of ∑ 16 PAHs varied from 347.05 to 6207.5 and 179.32 to 1657.5 ng g -1 in sediment and short-neck clam samples, respectively. The calculations of mean PEL quotients (mean-PELQs) showed that the ecological risk of PAHs in the sediment samples was low to moderate-high level, whereas the total health risk through ingestion and dermal contact was considerably high. The PAHs biota sediment accumulation factors data for short-neck clam were obtained in this study, indicating a preferential accumulation of lower molecular weight PAHs. The source apportionment of PAHs in sediment using positive matrix factorization model indicated that the highest contribution to the PAHs was from diesel emissions (30.38%) followed by oil and oil derivate and incomplete coal combustion (23.06%), vehicular emissions (16.43%), wood combustion (15.93%), and natural gas combustion (14.2%). A preliminary evaluation of human health risk using chronic daily intake, hazard index, benzo[a]pyrene-equivalent (BaP eq ) concentration, and the incremental lifetime cancer risk indicated that PAHs in short-neck clam would induce potential carcinogenic effects in the consumers.

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

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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

Microstructure and mechanical properties of the TIG welded joints of fusion CLAM steel

Energy Technology Data Exchange (ETDEWEB)

Jiang Zhizhong, E-mail: zhizhongjiang2006@yahoo.com.c [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, Beijing 100083 (China); Ren Litian; Huang Jihua; Ju Xin; Wu Huibin [School of Materials Science and Engineering, University of Science and Technology Beijing, Xueyuan Road, Beijing 100083 (China); Huang Qunying; Wu Yican [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

2010-12-15

The CLAM steel plates were butt-welded through manual tungsten inert gas welding (TIG) process, and the following post-welding heat treatment (PWHT) at 740 {sup o}C for 1 h. The microstructure and mechanical properties of the welded joints were measured. The results show that both hardening and softening occur in the weld joints before PWHT, but the hardening is not removed completely in the weld metal and the fusion zone after PWHT. In as-welded condition, the microstructure of the weld metal is coarse lath martensite, and softened zone in heat-affected zone (HAZ) consists of a mixture of tempered martensite and ferrite. After PWHT, a lot of carbides precipitate at all zones in weld joints. The microstructure of softened zone transforms to tempered sorbite. Tensile strength of the weld metal is higher than that of HAZ and base metal regardless of PWHT. However, the weld metal has poor toughness without PWHT. The impact energy of the weld metal after PWHT reaches almost the same level as the base metal. So it is concluded that microstructure and mechanical properties of the CLAM steel welded joints can be improved by a reasonable PWHT.

Population dynamics of the freshwater clam Galatea paradoxa from the Volta River, Ghana

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Adjei-Boateng D.

2012-07-01

Full Text Available Population parameters such as asymptotic (L∞, growth coefficient (K, mortality rates (Z,F and M, exploitation level (E and recruitment pattern of the freshwater clam Galatea paradoxa were estimated using length-frequency data from the Volta River estuary, Ghana. The L∞ for G. paradoxa at the Volta estuary was 105.7 mm, the growth coefficient (K and the growth performance index (Ǿ ranged between 0.14–0.18 year-1 and 3.108–3.192, respectively. Total mortality (Z was 0.65–0.82 year-1, while natural mortality (M and fishing mortality (F were 0.35–0.44 year-1 and 0.21–0.47 year-1, respectively, with an exploitation level of 0.32–0.57. The recruitment pattern suggested that G. paradoxa has year-round recruitment with a single pulse over an extended period (October–March in the Volta River. The Volta River stock of G. paradoxa is overfished and requires immediate action to conserve it. This can be achieved by implementing a minimum landing size restriction and intensifying the culture of smaller clams which is a traditional activity at the estuary.

Physiological responses to copper in giant clams: a comparison of two methods in revealing effects on photosynthesis in zooxanthellae.

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Elfwing, Tina; Blidberg, Eva; Tedengren, Michael

2002-08-01

In the present work physiological responses to a short term, sub-lethal exposure to copper (5 microg Cu2 l(-1) were studied on two species of giant clams, Tridacna gigas and Hippopus hippopus. All giant clams (fam. Tridacnidae) maintain a symbiotic relationship with photo-synthesising microalgae (zooxanthellae) and the phytotoxic effects of this copper concentration were approached with two different end points: changes in oxygen production and maximal quantum yield (Fv/Fm). Additionally we measured respiration, whereby Pg:R ratios could be calculated for the system (algae and clam) and used as an indicator of stress. Cu accumulation was only determined for T. gigas and showed significantly higher tissue concentrations in exposed specimens (11.3 microg Cu g(-1) dry wt) compared to the controls (4.2 microg Cu g(-1)). Both species displayed significantly reduced Pg:R ratios due to exposure, mainly explained by lowered gross production. No indication of stress was shown in the fluorescence measurements and possible explanations are discussed in the paper. We propose that inhibitions in the slow kinetics of photosynthesis were not captured by this fluorescence parameter. Accordingly we suggest that measurements of maximum fluorescence yield should be accompanied by complementary parameters when studying pollutants with unclear phytotoxic mechanisms.

Study of the toxic effects of flame retardant PBDE-47 on the clam Chamelea gallina (Linnaeus, 1758

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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.

Metabolic physiology of the invasive clam, Potamocorbula amurensis: the interactive role of temperature, salinity, and food availability.

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Miller, Nathan A; Chen, Xi; Stillman, Jonathon H

2014-01-01

In biological systems energy serves as the ultimate commodity, often determining species distributions, abundances, and interactions including the potential impact of invasive species on native communities. The Asian clam Potamocorbula amurensis invaded the San Francisco Estuary (SFE) in 1986 and is implicated in the decline of native fish species through resource competition. Using a combined laboratory/field study we examined how energy expenditure in this clam is influenced by salinity, temperature and food availability. Measures of metabolism were made at whole organism (metabolic rate) and biochemical (pyruvate kinase (PK) and citrate synthase (CS) enzyme activities) levels. We found in the field, over the course of a year, the ratio of PK to CS was typically 1.0 suggesting that aerobic and fermentative metabolism were roughly equivalent, except for particular periods characterized by low salinity, higher temperatures, and intermediate food availabilities. In a 30-day laboratory acclimation experiment, however, neither metabolic rate nor PK:CS ratio was consistently influenced by the same variables, though the potential for fermentative pathways did predominate. We conclude that in field collected animals, the addition of biochemical measures of energetic state provide little additional information to the previously measured whole organism metabolic rate. In addition, much of the variation in the laboratory remained unexplained and additional variables, including reproductive stage or body condition may influence laboratory-based results. Further study of adult clams must consider the role of organismal condition, especially reproductive state, in comparisons of laboratory experiments and field observations.

Size dependent bioaccumulation and ecotoxicity of gold nanoparticles in an endobenthic invertebrate: The Tellinid clam Scrobicularia plana

International Nuclear Information System (INIS)

Pan Jinfen; Buffet, Pierre-Emmanuel; Poirier, Laurence; Amiard-Triquet, Claude; Gilliland, Douglas; Joubert, Yolaine; Pilet, Paul; Guibbolini, Marielle; Risso de Faverney, Christine; Roméo, Michèle; Valsami-Jones, Eugenia; Mouneyrac, Catherine

2012-01-01

Gold nanoparticles (AuNPs) have important technological applications resulting in an increased potential for release to the environment, and a greater possibility of toxicological effects. The marine bivalve Scrobicularia plana was exposed to AuNPs of size 5, 15 and 40 nm during a 16 d laboratory exposure at 100 μg Au L −1 . After exposure to AuNPs forming aggregates (>700 nm), the clams accumulated Au in their soft tissues. Biochemical (biomarkers) and behavioral (burrowing and feeding) responses were investigated. Au NPs were responsible of metallothionein induction (5, 40 nm), increased activities of catalase (15, 40 nm) and superoxide dismutase (40 nm) and of glutathione S-transferase by the three sizes of AuNPs indicating defense against oxidative stress. Exposure to AuNPs impaired burrowing behavior. However, it must be underlined that these effects were observed at a dose much higher than expected in the environment. - Highlights: ► AuNPs were aggregated to a maximum distribution peak at 0.6 μm in seawater. ► Scrobicularia plana accumulated Au with higher accumulation for bigger NPs. ► Induction of MT, CAT, SOD and GST showed oxidative stress in clams. ► TBARS levels advocated no significant oxidative damage in clams. ► Gold is an inert metal, ecotoxic effects are probably due to the nanoparticle form. - AuNPs were aggregated in seawater, Scrobicularia plana accumulated Au with higher accumulation for bigger NPs and increased activities of biomarkers showed oxidative stress.

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.

Evaluation of Rapid, Early Warning Approaches to Track Shellfish Toxins Associated with Dinophysis and Alexandrium Blooms

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Theresa K. Hattenrath-Lehmann

2018-01-01

Full Text Available Marine biotoxin-contaminated seafood has caused thousands of poisonings worldwide this century. Given these threats, there is an increasing need for improved technologies that can be easily integrated into coastal monitoring programs. This study evaluates approaches for monitoring toxins associated with recurrent toxin-producing Alexandrium and Dinophysis blooms on Long Island, NY, USA, which cause paralytic and diarrhetic shellfish poisoning (PSP and DSP, respectively. Within contrasting locations, the dynamics of pelagic Alexandrium and Dinophysis cell densities, toxins in plankton, and toxins in deployed blue mussels (Mytilus edulis were compared with passive solid-phase adsorption toxin tracking (SPATT samplers filled with two types of resin, HP20 and XAD-2. Multiple species of wild shellfish were also collected during Dinophysis blooms and used to compare toxin content using two different extraction techniques (single dispersive and double exhaustive and two different toxin analysis assays (liquid chromatography/mass spectrometry and the protein phosphatase inhibition assay (PP2A for the measurement of DSP toxins. DSP toxins measured in the HP20 resin were significantly correlated (R2 = 0.7–0.9, p < 0.001 with total DSP toxins in shellfish, but were detected more than three weeks prior to detection in deployed mussels. Both resins adsorbed measurable levels of PSP toxins, but neither quantitatively tracked Alexandrium cell densities, toxicity in plankton or toxins in shellfish. DSP extraction and toxin analysis methods did not differ significantly (p > 0.05, were highly correlated (R2 = 0.98–0.99; p < 0.001 and provided complete recovery of DSP toxins from standard reference materials. Blue mussels (Mytilus edulis and ribbed mussels (Geukensia demissa were found to accumulate DSP toxins above federal and international standards (160 ng g−1 during Dinophysis blooms while Eastern oysters (Crassostrea virginica and soft shell clams (Mya

Overview on the welding technologies of CLAM steel and the DFLL TBM fabrication

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Junyu Zhang

2016-12-01

Full Text Available Dual Functional Lithium Lead (DFLL blanket was proposed for its advantages of high energy exchange efficiency and on-line tritium extraction, and it was selected as the candidate test blanket module (TBM for China Fusion Engineering Test Reactor (CFETR and the blanket for Fusion Design Study (FDS series fusion reactors. Considering the influence of high energy fusion neutron irradiation and high heat flux thermal load on the blanket, China Low Activation Martensitic (CLAM steel was selected as the structural material for DFLL blanket. The structure of the blanket and the cooling internal components were pretty complicated. Meanwhile, high precision and reliability were required in the blanket fabrication. Therefore, several welding techniques, such as hot isostatic pressing diffusion bonding, tungsten inner gas welding, electron beam welding and laser beam welding were developed for the fabrication of cooling internals and the assembly of the blanket. In this work, the weldability on CLAM steel by different welding methods and the properties of as-welded and post-weld heat-treated joints were investigated. Meanwhile, the welding schemes and the assembly strategy for TBM fabrication were raised. Many tests and research efforts on scheme feasibility, process standardization, component qualification and blanket assembly were reviewed.

Establishing the norm of Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) in Chinese infants.

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Chang, Y C; Huang, C C; Hu, S C

1998-01-01

The Cognitive Adaptive Test/Clinical Linguistic and Auditory Milestone Scale (CAT/CLAMS) has been recommended as a useful diagnostic tool for cognitive delay. To provide wider application of this instrument as a general screening tool for pediatricians, a normative percentile graph from a large convenience sample of Chinese infants has been established. The effects of environmental factors on early language and adaptive development were also analyzed. A total of 402 normal infants aged 4 to 36 months attending well-child clinics were recruited. These infants were from all socioeconomic strata, and half were bilingual with Mandarin and Taiwanese. Grandmothers were the chief caretakers or co-caretakers in 28% of this population. The milestones were attained in a sequential and orderly fashion. In contrast to the adaptive ability, there was a wide variation in language acquisition between age 12 and 24 months. Multiple stepwise regression of demographic and environmental factors revealed that age was the main variance in CAT score (P = 0.0001). In CLAMS score, however, age and caretakers were the significant predictors (P = 0.0001). Infants cared for by both mothers and grandmothers had higher CLAMS score by two months over those cared by mothers only (P = 0.001). Those cared for by grandmothers only had lower language score than those by mothers only, though without statistical significance (P = 0.05). Bilingualism, birth order, numbers of siblings, familial structures, and parental socioeconomic status had no effect on early development.

Biological activities from extracts of endophytic fungi isolated from Viguiera arenaria and Tithonia diversifolia.

Science.gov (United States)

Guimarães, Denise O; Borges, Warley S; Kawano, Cristina Y; Ribeiro, Patrícia H; Goldman, Gustavo H; Nomizo, Auro; Thiemann, Otávio H; Oliva, Glaucius; Lopes, Norberto P; Pupo, Mônica T

2008-01-01

A total of 39 endophytic fungi have been isolated from Viguiera arenaria and Tithonia diversifolia, both collected in São Paulo State, Brazil. The isolates were identified based on their ribosomal DNA sequences. The ethyl acetate (EtOAc) extracts of all endophytic fungi were evaluated for their antimicrobial, antiparasitic and antitumoral activity. Antimicrobial screening was conducted using an agar diffusion assay against three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli and Candida albicans. Antiparasitic activity was determined by enzymatic inhibition of gGAPDH of Trypanosoma cruzi and adenine phosphorybosiltransferase (APRT) of Leishmania tarentolae. Antitumoral activity was tested against human T leukemia cells by the Mosmann colorimetric method. All extracts showed activity in at least one assay: 79.5% of the extracts were cytotoxic against leukemia cells, 5.1% of the extracts were active against S. aureus, 25.6% against E. coli and 64.1% against Candida albicans. Only one extract showed promising results in the inhibition of parasitic enzymes gGAPDH (95.0%) and three were found to inhibit APRT activity. The cytotoxic extract produced by the strain VA1 (Glomerella cingulata) was fractionated and yielded nectriapyrone and tyrosol. Nectriapyrone showed relevant cytotoxic activity against both human T leukemia and melanoma tumor cell lines.

Freshwater Clam Extract Ameliorates Triglyceride and Cholesterol Metabolism through the Expression of Genes Involved in Hepatic Lipogenesis and Cholesterol Degradation in Rats

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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.

Addressing Sustainability of Clam Farming in the Venice Lagoon

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Donata Melaku Canu

2011-09-01

According to the System Approach Framework (SAF, based on previous studies and stakeholder interactions, we developed a model integrating ecological, social, and economic (ESE aspects. We chose the aspects necessary to represent the essential dynamics of major ecological, social, and economic clam farming system components to project the consequences of implementing alternative management policies and to address the ecological and social carrying capacity. Results of the simulations suggest that a properly managed farming system can sustain an acceptable income and support the local community, while reducing negative environmental impacts, social conflicts, and consumer health risks and improving system resilience. The results highlight the importance of an interdisciplinary, participatory, and adaptive approach in planning the management of this important renewable resource.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Pacific Southwest). Common Littleneck Clam.

Science.gov (United States)

1986-04-01

cells in clam (P. tenerrima) in having December and January (Quayle 1943). w , , radiating ribs more prominent than The growth of gametes reaches a...reproductive cycle levels in intertidal mollusks of of Protothaca stamine ’ using histo- California. Veliger 14(4):365-372. logical, wet weight-dry

Comparison of two methods for the detection of hepatitis A virus in clam samples (Tapes spp.) by reverse transcription-nested PCR.

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Suñén, Ester; Casas, Nerea; Moreno, Belén; Zigorraga, Carmen

2004-03-01

The detection of hepatitis A virus in shellfish by reverse transcription-nested polymerase chain reaction (RT-nested PCR) is hampered mainly by low levels of virus contamination and PCR inhibitors in shellfish. In this study, we focused on getting a rapid and sensitive processing procedure for the detection of HAV by RT-nested PCR in clam samples (Tapes spp.). Two previously developed processing methods for virus concentration in shellfish have been improved upon and compared. The first method involves acid adsorption, elution, polyethylene glycol (PEG) precipitation, chloroform extraction and PEG precipitation. The second method is based on elution with a glycine buffer at pH 10, chloroform extraction and concentration by ultracentrifugation. Final clam concentrates were processed by RNA extraction or immunomagnetic capture of viruses (IMC) before the RT-nested PCR reaction. Both methods of sample processing combined with the RNA extraction from the concentrates were very efficient when they were assayed in seeded and naturally contaminated samples. The results show that the first method was more effective in removal inhibitors and the second was simpler and faster. The IMC of HAV from clam concentrates processed by method 1 was revealed to be a very effective method of simultaneously removing residual PCR inhibitors and of concentrating the virus.

Favored use of anti-predator netting (APN) applied for the farming of clams leads to little benefits to industry while increasing nearshore impacts and plastics pollution.

Science.gov (United States)

Bendell, L I

2015-02-15

An overview of the efficacy of anti-predator netting (APN) used by the shellfish industry is presented. There is little support that the currently favored APN effectively protects farmed clams from predators. Evidence does suggest that APN leads to impacts and pollution. APN is an attractant for predators, e.g., crabs, by providing a refuge within Ulva sp. which attaches onto the surface of APN. APN entrains silt and organic matter and increases sediment temperatures degrading habitat underneath the APN. APN present hazards to fish and wildlife and is a source of plastics to the marine environment. The continued use of ineffective APN does not serve either the environment or industry well, and many of these issues could be addressed through the alternate use of "ancient" technology used by aboriginal people to maintain clam gardens; building of rock walls optimizing the amount of clam habitat thereby increasing numbers without the use of APN. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antimicrobial resistance and detection of the mecA gene besides enterotoxin-encoding genes among coagulase-negative Staphylococci isolated from clam meat of Anomalocardia brasiliana.

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Batista, Jacqueline Ellen Camelo; Ferreira, Ewerton Lucena; Nascimento, Danielle Cristina de Oliveira; Ventura, Roberta Ferreira; de Oliveira, Wagner Luis Mendes; Leal, Nilma Cintra; Lima-Filho, José Vitor

2013-12-01

The marine clam Anomalocardia brasiliana is a candidate as a sentinel animal to monitor the contamination levels of coliforms in shellfish-harvesting areas of Brazil's northeastern region. The aim of the present study was to search enterotoxin-encoding genes plus the mecA gene among coagulase-negative staphylococci (CNS) isolates from shellfish meats of A. brasiliana. The specimen clam (n=48; 40 clams per sample) was collected during low tide in the bay area of Mangue Seco from April through June 2009, and random samples of chilled and frozen shelled clam meat (n=33; 250 g per sample) were obtained from retail shops from January through March 2012. Seventy-nine CNS isolates were identified, including Staphylococcus xylosus, S. cohnii spp. urealyticus, S. sciuri, and S. lentus. A high percentage of isolates resistant to erythromycin (58.5%), penicillin (51.2%), and tetracycline (43.9%), and the fluoroquinolones levofloxacin (39%) and ciprofloxacin (34.1%) were recorded from those environmental samples. Isolates from retail shops were particularly resistant to oxacillin (55.3%) and penicillin (36.8%). All CNS resistant to oxacillin and/or cefoxitin were positive for the presence of the mecA gene, but phenotypically susceptible to vancomycin. Also, the enterotoxin-encoding genes seg and seh were detected through multiplex-polymerase chain reaction in 77.7% and 88.8% of the isolates from environmental samples, versus 90.5% and 100% of the isolates from retail shops, respectively. The data reveal the risk to public health due to consuming raw or undercooked shellfish containing enterotoxigenic plus methicillin-resistant CNS.

The Whole-Genome and Transcriptome of the Manila Clam (Ruditapes philippinarum).

Science.gov (United States)

Mun, Seyoung; Kim, Yun-Ji; Markkandan, Kesavan; Shin, Wonseok; Oh, Sumin; Woo, Jiyoung; Yoo, Jongsu; An, Hyesuck; Han, Kyudong

2017-06-01

The manila clam, Ruditapes philippinarum, is an important bivalve species in worldwide aquaculture including Korea. The aquaculture production of R. philippinarum is under threat from diverse environmental factors including viruses, microorganisms, parasites, and water conditions with subsequently declining production. In spite of its importance as a marine resource, the reference genome of R. philippinarum for comprehensive genetic studies is largely unexplored. Here, we report the de novo whole-genome and transcriptome assembly of R. philippinarum across three different tissues (foot, gill, and adductor muscle), and provide the basic data for advanced studies in selective breeding and disease control in order to obtain successful aquaculture systems. An approximately 2.56 Gb high quality whole-genome was assembled with various library construction methods. A total of 108,034 protein coding gene models were predicted and repetitive elements including simple sequence repeats and noncoding RNAs were identified to further understanding of the genetic background of R. philippinarum for genomics-assisted breeding. Comparative analysis with the bivalve marine invertebrates uncover that the gene family related to complement C1q was enriched. Furthermore, we performed transcriptome analysis with three different tissues in order to support genome annotation and then identified 41,275 transcripts which were annotated. The R. philippinarum genome resource will markedly advance a wide range of potential genetic studies, a reference genome for comparative analysis of bivalve species and unraveling mechanisms of biological processes in molluscs. We believe that the R. philippinarum genome will serve as an initial platform for breeding better-quality clams using a genomic approach. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Growth, Survival and Reproduction of the Giant Clam Tridacna maxima (Röding 1798, Bivalvia) in Two Contrasting Lagoons in French Polynesia

Science.gov (United States)

Van Wynsberge, Simon; Andréfouët, Serge; Gaertner-Mazouni, Nabila; Wabnitz, Colette C. C.; Menoud, Mathilde; Le Moullac, Gilles; Levy, Peva; Gilbert, Antoine; Remoissenet, Georges

2017-01-01

Shell growth, reproduction, and natural mortality of the giant clam Tridacna maxima were characterized over a two-year-period in the lagoon of the high island of Tubuai (Austral Archipelago) and in the semi-closed lagoon of Tatakoto (Tuamotu Archipelago) in French Polynesia. We also recorded temperature, water level, tidal slope, tidal range, and mean wave height in both lagoons. Lower lagoon aperture and exposure to oceanic swells at Tatakoto than at Tubuai was responsible for lower lagoon water renewal, as well as higher variability in temperature and water level at Tatakoto across the studied period. These different environmental conditions had an impact on giant clams. Firstly, spawning events in the lagoon of Tatakoto, detected by gonad maturity indices in June and July 2014, were timed with high oceanic water inflow and a decrease in lagoon water temperature. Secondly, temperature explained differences in shell growth rates between seasons and lagoons, generating different growth curves for the two sites. Thirdly, local mortality rates were also found to likely be related to water renewal patterns. In conclusion, our study suggests that reef aperture and lagoon water renewal rates play an integral role in giant clam life history, with significant differences in rates of shell growth, mortality and fertility found between open versus semi-closed atoll lagoons in coral reef ecosystems. PMID:28118406

Growth, Survival and Reproduction of the Giant Clam Tridacna maxima (Röding 1798, Bivalvia in Two Contrasting Lagoons in French Polynesia.

Directory of Open Access Journals (Sweden)

Simon Van Wynsberge

Full Text Available Shell growth, reproduction, and natural mortality of the giant clam Tridacna maxima were characterized over a two-year-period in the lagoon of the high island of Tubuai (Austral Archipelago and in the semi-closed lagoon of Tatakoto (Tuamotu Archipelago in French Polynesia. We also recorded temperature, water level, tidal slope, tidal range, and mean wave height in both lagoons. Lower lagoon aperture and exposure to oceanic swells at Tatakoto than at Tubuai was responsible for lower lagoon water renewal, as well as higher variability in temperature and water level at Tatakoto across the studied period. These different environmental conditions had an impact on giant clams. Firstly, spawning events in the lagoon of Tatakoto, detected by gonad maturity indices in June and July 2014, were timed with high oceanic water inflow and a decrease in lagoon water temperature. Secondly, temperature explained differences in shell growth rates between seasons and lagoons, generating different growth curves for the two sites. Thirdly, local mortality rates were also found to likely be related to water renewal patterns. In conclusion, our study suggests that reef aperture and lagoon water renewal rates play an integral role in giant clam life history, with significant differences in rates of shell growth, mortality and fertility found between open versus semi-closed atoll lagoons in coral reef ecosystems.

Effect of thermal aging on grain structural characteristic and Ductile-to-Brittle transition temperature of CLAM steel at 550 °C

Energy Technology Data Exchange (ETDEWEB)

Wang, Wei [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, 230031 (China); Chen, Jianwei [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Xu, Gang, E-mail: gang.xu@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

2017-02-15

Highlights: • The grain boundary length per unit area decreased with the increasing aging time. • The fraction of LABs increased obviously after thermal aging. • Prior austenitic grain refinement is more important to improve low temperature toughness. - Abstract: In this work, electron backscatter diffraction (EBSD) was used to investigate the grain structure evolution of China low activation martensitic (CLAM) steel samples which were aged at 550 °C for 0 h, 2000 h, 4000 h and 10,000 h. The results showed that the prior austenitic grain size increased with the aging time, which led to the decrease of grain boundary length. The fraction of misorientation angle in a range from about 4 to 10° increased obviously after thermal aging for 10,000 h, and it indicated that the fine subgrains formed in the CLAM steel during the long-term thermal exposure. Furthermore, Charpy impact experiments were carried out to analyze the toughness of the CLAM steel before and after aging, particularly the Ductile-to-Brittle Transition Temperature (DBTT). Though amounts of fine subgrians formed in matrix, a substantial increase in DBTT (∼40.1 °C) had been noticed after aging for 10,000 h. The results showed that the high angle boundaries such as prior austenitic grain boundaries are more effective in retarding the propagation of cleavage crack than subgrain boundaries.

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

International Nuclear Information System (INIS)

Chen, W.-Y.; Tsai, J.-W.; Ju, Y.-R.; Liao, C.-M.

2010-01-01

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.

Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

Energy Technology Data Exchange (ETDEWEB)

Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2010-05-15

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.

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.

PARTICLE REMOVAL RATES BY THE MUD SHRIMP UPOGEBIA PUGETTENSIS, ITS BURROW, AND A COMMENSAL CLAM: EFFECTS ON ESTUARINE PHYTOPLANKTON ABUNDANCE

Science.gov (United States)

The burrowing shrimp Upogebia pugettensis is an abundant intertidal inhabitant of Pacific Northwest bays and estuaries where it lives commensally with the bivalve Cryptomya californica. Suspension-feeding activities by the shrimp and by its commensal clam, as well as particle se...

Clams sensitivity towards As and Hg: A comprehensive assessment of native and exotic species.

Science.gov (United States)

Velez, Cátia; Freitas, Rosa; Antunes, Sara C; Soares, Amadeu M V M; Figueira, Etelvina

2016-03-01

To assess the environmental impact of As and Hg, bioindicator organisms such as bivalves have been used. Nevertheless, few studies have assessed the impacts of As and Hg in Ruditapes decussatus and Ruditapes philippinarum, which are native and exotic species in Europe, respectively. The main goal of the present study was to assess elements' partitioning and detoxification strategies of R. decussatus and R. philippinarum. Both clams showed a higher capacity to bioconcentrate Hg (BCF 2.29-7.49), when compared to As (0.59-1.09). Furthermore, As accumulation in both species was similar in the soluble and insoluble fractions, while in both species the majority of Hg was found in the insoluble fraction. Clams exposed to As showed different detoxification strategies, since R. decussatus had higher ability to enhance antioxidant enzymes and metallothioneins in order to reduce toxicity, and R.philippinarum increased glutathione S-transferase Ω activity, that catalyzes monomethyl arsenate reduction, the rate-limiting reaction in arsenic biotransformation. When exposed to Hg, R. decussatus presented, higher synthesis of antioxidant enzymes and lower LPO, being able to better tolerate Hg than the exotic species R. philippinarum. Thus under relevant levels of As and Hg contamination our work evidenced the higher ability of R. decussatus to survive and inhabit coastal environments not heavily contaminated by Hg and As. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparison of corrosion behavior of EUROFER and CLAM steels in flowing Pb–15.7Li

Energy Technology Data Exchange (ETDEWEB)

Konys, J., E-mail: juergen.konys@kit.edu [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Krauss, W. [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Zhu, Z.; Huang, Q. [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

2014-12-15

Ferritic martensitic steels are envisaged to be applied as structural materials in HCLL blanket systems. Their compatibility with the liquid breeder, which is in direct contact with the structural alloy, will be essential for reliable and safe operation of the designed blankets. Formerly performed corrosion tests of RAFM steels in PICOLO loop of KIT were mainly done at high flow velocities, e.g., 0.22 m/s and delivered severe attack with material loss rates above 400 μm/yr at 823 K. Meanwhile, flow velocities for corrosion testing have been reduced into the “cm range” to be near fusion relevant conditions. Among the international ITER-partners, many varieties of RAFM steels have been developed and manufactured within the last decade, e.g., the so-called Chinese Low Activation Martensitic steel (CLAM). In this paper, the long term corrosion behavior of EUROFER and CLAM steel in flowing Pb–15.7Li will be presented at a flow velocity of about 0.10 m/s and compared with earlier obtained results of RAFM steels exposed at other operation parameters of PICOLO loop. The observed corrosion attack is near 220 μm/yr and fits well to predictions made by MATLIM-modeling for low flow velocities in the turbulent flow regime.

Laboratory simulation reveals significant impacts of ocean acidification on microbial community composition and host-pathogen interactions between the blood clam and Vibrio harveyi.

Science.gov (United States)

Zha, Shanjie; Liu, Saixi; Su, Wenhao; Shi, Wei; Xiao, Guoqiang; Yan, Maocang; Liu, Guangxu

2017-12-01

It has been suggested that climate change may promote the outbreaks of diseases in the sea through altering the host susceptibility, the pathogen virulence, and the host-pathogen interaction. However, the impacts of ocean acidification (OA) on the pathogen components of bacterial community and the host-pathogen interaction of marine bivalves are still poorly understood. Therefore, 16S rRNA high-throughput sequencing and host-pathogen interaction analysis between blood clam (Tegillarca granosa) and Vibrio harveyi were conducted in the present study to gain a better understanding of the ecological impacts of ocean acidification. The results obtained revealed a significant impact of ocean acidification on the composition of microbial community at laboratory scale. Notably, the abundance of Vibrio, a major group of pathogens to many marine organisms, was significantly increased under ocean acidification condition. In addition, the survival rate and haemolytic activity of V. harveyi were significantly higher in the presence of haemolymph of OA treated T. granosa, indicating a compromised immunity of the clam and enhanced virulence of V. harveyi under future ocean acidification scenarios. Conclusively, the results obtained in this study suggest that future ocean acidification may increase the risk of Vibrio pathogen infection for marine bivalve species, such as blood clams. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

Science.gov (United States)

Hanana, H; Simon, G; Kervarec, N; Cérantola, S

2014-01-01

Tributyltin (TBT) is a highly toxic pollutant present in many aquatic ecosystems. Its toxicity in mollusks strongly affects their performance and survival. The main purpose of this study was to elucidate the mechanisms of TBT toxicity in clam Ruditapes decussatus by evaluating the metabolic responses of heart tissues, using high-resolution magic angle-spinning nuclear magnetic resonance (HRMAS NMR), after exposure to TBT (10 -9 , 10 -6 and 10 -4 M) during 24 h and 72 h. Results show that responses of clam heart tissue to TBT exposure are not dose dependent. Metabolic profile analyses indicated that TBT 10 -6 M, contrary to the two other doses tested, led to a significant depletion of taurine and betaine. Glycine levels decreased in all clam groups treated with the organotin. It is suggested that TBT abolished the cytoprotective effect of taurine, betaine and glycine thereby inducing cardiomyopathie. Moreover, results also showed that TBT induced increase in the level of alanine and succinate suggesting the occurrence of anaerobiosis particularly in clam group exposed to the highest dose of TBT. Taken together, these results demonstrate that TBT is a potential toxin with a variety of deleterious effects on clam and this organotin may affect different pathways depending to the used dose. 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 Ca 2+ dependent cell death induced by TBT. Therefore this compound could be a promising biomarker for TBT exposure.

Abnormalities in bivalve larvae from the Puck Bay (Gulf of Gdansk, southern Baltic Sea) as an indicator of environmental pollution.

Science.gov (United States)

Lasota, Rafal; Gierszewska, Katarzyna; Viard, Frédérique; Wolowicz, Maciej; Dobrzyn, Katarzyna; Comtet, Thierry

2018-01-01

This study described the occurrence of abnormalities in bivalve larvae from the Puck Bay. Analyses of plankton samples collected in 2012-2013 showed that larval Mytilus trossulus, Mya arenaria, and Cerastoderma glaucum exhibited abnormalities that could indicate adverse environmental impacts. The deformities were mainly in shells, but missing soft tissue fragments and protruding vela were also noted. In addition to larval studies, we analyzed benthic postlarvae of Mytilus trossulus. Interestingly, grooves and notches at different locations of the prodissoconch, dissoconch, and shell margin were observed. Some of these deformations were reminiscent of the indentations found on the shell edge of larvae. Comparing the proportion of abnormal postlarvae to larvae with shell abnormalities suggested that the survival of larvae with shell abnormalities was low. Overall, our results suggested that the ratio of abnormal bivalve larvae could be used as an indicator of the biological effects of hazardous substances in the pelagic environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparative bioaccumulation and toxicity of silver in different populations of the intra-sedimentary clam Macoma balthica exposed or not to metal contamination in their natural medium

International Nuclear Information System (INIS)

Amiard-Triquet, C.; Geffard, A.; Boisson, F.; Ballan-Dufrancais, C.; Jeantet, A.Y.; Berthet, B.; Mouneyrac, C.

1999-01-01

Tolerance to pollutants was observed in living organisms chronically exposed in their environment and detoxification processes have been evoked to explain such observations. In the present study, this hypothesis has been tested in clams originating from an industrialized estuary (Loire, Fr) and from an area submitted only to low anthropogenic influx (Bay of Somme, Fr). The comparison was carried out at different contamination levels in clams exposed to silver (50 to 100 ng Ag.ml -1 till LT 50 when 50% lethality was reached), a metal which has been described as liable to be detoxified through insolubilization and/or binding to metallothionein (MT)

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

Welding techniques development of CLAM steel for Test Blanket Module

Energy Technology Data Exchange (ETDEWEB)

Li Chunjing [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230027 (China)], E-mail: lcj@ipp.ac.cn; Huang Qunying; Wu Qingsheng; Liu Shaojun [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230027 (China); Lei Yucheng [Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Muroga, Takeo; Nagasaka, Takuya [National Institute for Fusion Science, Toki, Jifu, 509-5292 (Japan); Zhang Jianxun [Xi' an Jiaotong University, Xi' an, Shanxi, 710049 (China); Li Jinglong [Northwestern Polytechnical University, Xi' an, Shanxi, 710072 (China)

2009-06-15

Fabrication techniques for Test Blanket Module (TBM) with CLAM are being under development. Effect of surface preparation on the HIP diffusion bonding joints was studied and good joints with Charpy impact absorbed energy close to that of base metal have been obtained. The mechanical properties test showed that effect of HIP process on the mechanical properties of base metal was little. Uniaxial diffusion bonding experiments were carried out to study the effect of temperature on microstructure and mechanical properties. And preliminary experiments on Electron Beam Welding (EBW), Tungsten Inert Gas (TIG) Welding and Laser Beam Welding (LBW) were performed to find proper welding techniques to assemble the TBM. In addition, the thermal processes assessed with a Gleeble thermal-mechanical machine were carried out as well to assist the fusion welding research.

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.

Development and validation of 89 novel expressed sequence tag-derived microsatellite markers in blood clam, Tegillarca granosa

Science.gov (United States)

Teng, Shuangshuang; Fang, Jun; Cai, Yilong; Chai, Xueliang; Xiao, Guoqiang

2017-06-01

Blood clam, Tegillarca granosa, is an important shellfish in Chinese mariculture industry. Investigative research in this species, such as genetic linkage mapping, requires a large panel of molecular markers. In present study, a total of 89 polymorphic microsatellite markers were developed in T. granosa using the sequence database of Life Sciences Technology 454 next generation sequencing technology. All 89 loci were characterized in 20 individual clams from a natural population inhabiting Yueqing Gulf, Zhejiang Province, China. The number of alleles per polymorphic locus varied between 2 and 15, while the observed heterozygosity, expected heterozygosity and polymorphic information content varied between 0.000 and 1.000, 0.102 and 0.921, and 0.048 and 0.886, respectively. Of the 89 loci identified, 32 loci deviated significantly from Hardy-Weinberg equilibrium following Bonferroni correction. Thirty nine markers, which were shown to be polymorphic in a full-sibling family, were tested in Mendelian segregations. As expected, 32 loci were co-dominantly segregated in a Mendelian fashion. These novel developed microsatellite markers represent useful research tools for investigation of population genetic structure and genetic diversity in this species.

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.

Avian influenza in shorebirds: experimental infection of ruddy turnstones (Arenaria interpres) with avian influenza virus

Science.gov (United States)

Hall, Jeffrey S.; Krauss, Scott; Franson, J. Christian; TeSlaa, Joshua L.; Nashold, Sean W.; Stallknecht, David E.; Webby, Richard J.; Webster, Robert G.

2013-01-01

Background: Low pathogenic avian influenza viruses (LPAIV) have been reported in shorebirds, especially at Delaware Bay, USA, during spring migration. However, data on patterns of virus excretion, minimal infectious doses, and clinical outcome are lacking. The ruddy turnstone (Arenaria interpres) is the shorebird species with the highest prevalence of influenza virus at Delaware Bay. Objectives: The primary objective of this study was to experimentally assess the patterns of influenza virus excretion, minimal infectious doses, and clinical outcome in ruddy turnstones. Methods: We experimentally challenged ruddy turnstones using a common LPAIV shorebird isolate, an LPAIV waterfowl isolate, or a highly pathogenic H5N1 avian influenza virus. Cloacal and oral swabs and sera were analyzed from each bird. Results: Most ruddy turnstones had pre-existing antibodies to avian influenza virus, and many were infected at the time of capture. The infectious doses for each challenge virus were similar (103·6–104·16 EID50), regardless of exposure history. All infected birds excreted similar amounts of virus and showed no clinical signs of disease or mortality. Influenza A-specific antibodies remained detectable for at least 2 months after inoculation. Conclusions: These results provide a reference for interpretation of surveillance data, modeling, and predicting the risks of avian influenza transmission and movement in these important hosts.

Single nucleotide polymorphisms in i-type lysozyme gene and their correlation with vibrio-resistance and growth of clam Meretrix meretrix based on the selected resistance stocks.

Science.gov (United States)

Yue, Xin; Wang, Hongxia; Huang, Xiaohong; Wang, Chao; Chai, Xueliang; Wang, Chunde; Liu, Baozhong

2012-09-01

I-type lysozyme is considered to play crucial roles in both anti-bacteria and digestion function of the bivalve, which signifies that it is related to both immunity and growth. In this study, based on the principle of case-control association analysis, using the stock materials with different vibrio-resistance profile obtained by selective breeding, single nucleotide polymorphisms (SNPs) in the DNA partial sequence of an i-type lysozyme of Meretrix meretrix (MmeLys) were discovered and examined for their association with vibrio-resistance and growth. Twenty-seven SNPs were detected and fifteen of them were genotyped in clam stocks with different resistance to Vibrio harveyi (09-C and 09-R) and to Vibrio parahaemolyticus (11-S and 11-R). Allele frequency distribution among different stocks was compared. And wet weight of clams with different genotype at each SNP locus was compared. The results indicated that SNP locus 9 was associated with V. harveyi and V. parahaemolyticus resistance and growth of M. meretrix. Loci 12 and 14 were associated with both V. parahaemolyticus-resistance and growth, and also have the potential to be related with V. harveyi-resistance of M. meretrix. Therefore these three SNPs especially locus 9 were the potential markers which may be involved in assisting resistance selective breeding. In addition, this study showed evidence that improvements in clam resistance to vibriosis could be achieved through selective breeding. All results provided encouragement for the continuation of the selective breeding program for vibrio-resistance gain in clam M. meretrix and the application of polymorphisms in MmeLys to the future marker assisted selection. Copyright © 2012 Elsevier Ltd. All rights reserved.

A quantitative estimation of the energetic cost of brown ring disease in the Manila clam using Dynamic Energy Budget theory.

NARCIS (Netherlands)

Flye Sainte Marie, J.G.; Jean, F.; Paillard, C.; Kooijman, S.A.L.M.

2009-01-01

Brown ring disease (BRD) in the Manila clam, Ruditapes philippinarum, is a bacterial disease caused by the pathogen Vibrio tapetis. This disease induces the formation of a characteristic brown conchiolin deposit on the inner shell and is associated with a decrease in condition index indicating that

Two new miniature inverted-repeat transposable elements in the genome of the clam Donax trunculus.

Science.gov (United States)

Šatović, Eva; Plohl, Miroslav

2017-10-01

Repetitive sequences are important components of eukaryotic genomes that drive their evolution. Among them are different types of mobile elements that share the ability to spread throughout the genome and form interspersed repeats. To broaden the generally scarce knowledge on bivalves at the genome level, in the clam Donax trunculus we described two new non-autonomous DNA transposons, miniature inverted-repeat transposable elements (MITEs), named DTC M1 and DTC M2. Like other MITEs, they are characterized by their small size, their A + T richness, and the presence of terminal inverted repeats (TIRs). DTC M1 and DTC M2 are 261 and 286 bp long, respectively, and in addition to TIRs, both of them contain a long imperfect palindrome sequence in their central parts. These elements are present in complete and truncated versions within the genome of the clam D. trunculus. The two new MITEs share only structural similarity, but lack any nucleotide sequence similarity to each other. In a search for related elements in databases, blast search revealed within the Crassostrea gigas genome a larger element sharing sequence similarity only to DTC M1 in its TIR sequences. The lack of sequence similarity with any previously published mobile elements indicates that DTC M1 and DTC M2 elements may be unique to D. trunculus.

Effects of environmental and biological conditions on the recruitment and growth of the Manila clam Ruditapes philippinarum on the west coast of Korea

Science.gov (United States)

Kim, Sang Lyeol; Kwon, Soon Hyun; Lee, Hyung-Gon; Yu, Ok Hwan

2017-03-01

The distribution of the Manila clam Ruditapes philippinarum, which is often dominant in intertidal zones, is influenced by both environmental and biological conditions. However, there have been few comprehensive studies on the interactive effects of these two groups of factors. The present study examined the environmental and biological parameters determining the population dynamics of the clams that is a dominant component of the intertidal communities of Euhangri and Padori on the west coast of Korean peninsula. We collected R. philippinarum and other members of the macrobenthos (> 1 mm long) monthly from 0.25 m2 quadrats deployed in the intertidal zones at Euhangri, Taean, and Padori during the period from August 2013 to January 2015. Physicochemical parameters of the water and sediment were measured at the same time. Water temperature and salinity is high and low in the summer to winter, respectively. While mean grain size of the sediment was higher at Euhangri than at Padori, total mean density of R. philippinarum was higher at Euhangri (325 ind./ 0.25 m2 at Padori vs. 194 ind./0.25 m2 at Euhangri). Settled spat (population increased, the condition index of individual clams decreased, but as the population density of the spat increased the body condition index increased. The chlorophyll a content of the sediments at Padori exceeded that at Euhangri and decreased as the population of R. philippinarum increased. The shapes of R. philippinarum shells at Euhangri were more prolate than those at Padori, and the condition index at Euhangri exceeded that at Padori, indicating better growth conditions at Euhangri. The condition index and density of R. philippinarum were affected by the amount of chlorophyll a in the water column and in the sediment. The recruitment success of spats was negatively influenced by spat density. We suggest that regulation of habitat conditions for R. philippinarum, including the food supply, will optimize production of these commercial

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

International Nuclear Information System (INIS)

Bringas, J.E.

1996-01-01

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

Expression of a symbiosis-specific gene in Symbiodinium type A1 associated with coral, nudibranch and giant clam larvae

KAUST Repository

Mies, M.

2017-05-24

Symbiodinium are responsible for the majority of primary production in coral reefs and found in a mutualistic symbiosis with multiple animal phyla. However, little is known about the molecular signals involved in the establishment of this symbiosis and whether it initiates during host larval development. To address this question, we monitored the expression of a putative symbiosis-specific gene (H+-ATPase) in Symbiodinium A1 ex hospite and in association with larvae of a scleractinian coral (Mussismilia hispida), a nudibranch (Berghia stephanieae) and a giant clam (Tridacna crocea). We acquired broodstock for each host, induced spawning and cultured the larvae. Symbiodinium cells were offered and larval samples taken for each host during the first 72 h after symbiont addition. In addition, control samples including free-living Symbiodinium and broodstock tissue containing symbionts for each host were collected. RNA extraction and RT-PCR were performed and amplified products cloned and sequenced. Our results show that H+-ATPase was expressed in Symbiodinium associated with coral and giant clam larvae, but not with nudibranch larvae, which digested the symbionts. Broodstock tissue for coral and giant clam also expressed H+-ATPase, but not the nudibranch tissue sample. Our results of the expression of H+-ATPase as a marker gene suggest that symbiosis between Symbiodinium and M. hispida and T. crocea is established during host larval development. Conversely, in the case of B. stephanieae larvae, evidence does not support a mutualistic relationship. Our study supports the utilization of H+-ATPase expression as a marker for assessing Symbiodinium-invertebrate relationships with applications for the differentiation of symbiotic and non-symbiotic associations. At the same time, insights from a single marker gene approach are limited and future studies should direct the identification of additional symbiosis-specific genes, ideally from both symbiont and host.

Shell shape analysis and spatial allometry patterns of Manila Clam (Ruditapes philippinarium) in a mesotidal coastal lagoon

OpenAIRE

Caill-Milly, Nathalie; Bru, Noëlle; Mahé, Kélig; D'Amico, Franck

2012-01-01

While gradual allometric changes of shells are intrinsically driven by genotype, morphometrical shifts can also be modulated by local environmental conditions. Consequently the common use of a unique dimension (usually length) to assess bivalves’ growth may mask phenotypic differences in valve shape among populations. A morphometric exhaustive study was conducted on Manila clam, Ruditapes philippinarum, by acquiring data in the French Arcachon Bay (intrasite phenotypic variability) and by com...

Influence of different cooling rates on the microstructure of the HAZ and welding CCT diagram of CLAM steel

Energy Technology Data Exchange (ETDEWEB)

Zheng Shuhui, E-mail: shzheng@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Wu Qingsheng [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); Huang Qunying [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui, 230027 (China); Liu Shaojun; Han Yangyang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, 230031 (China)

2011-10-15

The evolution of microstructure in the weld HAZ (Heat Affected Zone) under welding thermal cycle was simulated by Gleeble-1500. The microstructures and properties of HAZ at different cooling rates were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and microhardness test. The results showed that when the cooling rates ranged from 3600 K/min to 60 K/min, fully martensitic transformations were achieved, and the cooling rates had little influence on the microstructure and microhardness of martensite. The maximum cooling rate to form ferrite was 60 K/min. When the cooling rates ranged from 60 K/min to 1 K/min, the microhardness of the HAZ began to decrease due to the presence of ferrite, and the lath sizes grew up to 0.13-0.15 {mu}m. The critical cooling rate to gain fully ferrite was found to be slower than 1 K/min. The welding CCT diagram of CLAM steel was constructed and it showed that there were ferrite and martensite transformation regions only. The diagram made it possible to predict the microstructures and properties of HAZ and became an important tool to evaluate weldability of CLAM steel.

Influence of different cooling rates on the microstructure of the HAZ and welding CCT diagram of CLAM steel

International Nuclear Information System (INIS)

Zheng Shuhui; Wu Qingsheng; Huang Qunying; Liu Shaojun; Han Yangyang

2011-01-01

The evolution of microstructure in the weld HAZ (Heat Affected Zone) under welding thermal cycle was simulated by Gleeble-1500. The microstructures and properties of HAZ at different cooling rates were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and microhardness test. The results showed that when the cooling rates ranged from 3600 K/min to 60 K/min, fully martensitic transformations were achieved, and the cooling rates had little influence on the microstructure and microhardness of martensite. The maximum cooling rate to form ferrite was 60 K/min. When the cooling rates ranged from 60 K/min to 1 K/min, the microhardness of the HAZ began to decrease due to the presence of ferrite, and the lath sizes grew up to 0.13-0.15 μm. The critical cooling rate to gain fully ferrite was found to be slower than 1 K/min. The welding CCT diagram of CLAM steel was constructed and it showed that there were ferrite and martensite transformation regions only. The diagram made it possible to predict the microstructures and properties of HAZ and became an important tool to evaluate weldability of CLAM steel.

A desk evaluation review of project MYA/6/015 hormonal studies on pituitary adrenal disorders. Project desk evaluation

International Nuclear Information System (INIS)

1994-01-01

Snake-bite is one of the high priority health problems in Myanmar, causing high mortality and mobility rates among the rural population. In 1982 the Department of Medical Research (DMR) of the Ministry of Health launched a research programme for the comprehensive studies of snake (Russell's viper) bites and since then various research divisions of the DMR have been actively engaged in both basic and clinical studies aimed at obtaining adequate knowledge of the biochemical, clinical and pathophysiological mechanisms to guide rational management of snake-bite cases. Also, a clinical research unit has been established in a particular area where the incidence of Russell's viper bite is quite high. Project MYA/6/015 was initiated in 1989 with the objective of determining the incidence, facilitating early diagnosis and assessing the value of therapy in hypopituitarism following snake bite, through the measurements of pituitary and adreno-cortical hormones in serum and their changes in response to dynamic tests. The project was completed in July 1993. The review was undertaken upon request by the Asia and Pacific Section, to assess the overall performance of the project

A desk evaluation review of project MYA/6/015 hormonal studies on pituitary adrenal disorders. Project desk evaluation

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-09

Snake-bite is one of the high priority health problems in Myanmar, causing high mortality and mobility rates among the rural population. In 1982 the Department of Medical Research (DMR) of the Ministry of Health launched a research programme for the comprehensive studies of snake (Russell`s viper) bites and since then various research divisions of the DMR have been actively engaged in both basic and clinical studies aimed at obtaining adequate knowledge of the biochemical, clinical and pathophysiological mechanisms to guide rational management of snake-bite cases. Also, a clinical research unit has been established in a particular area where the incidence of Russell`s viper bite is quite high. Project MYA/6/015 was initiated in 1989 with the objective of determining the incidence, facilitating early diagnosis and assessing the value of therapy in hypopituitarism following snake bite, through the measurements of pituitary and adreno-cortical hormones in serum and their changes in response to dynamic tests. The project was completed in July 1993. The review was undertaken upon request by the Asia and Pacific Section, to assess the overall performance of the project.

Development of the 'SEA-Clam' wave energy device for small scale use. Interim report 1st August 1983 - 30th April 1984

Energy Technology Data Exchange (ETDEWEB)

1984-04-01

An Interim Report on the development of the Sea-Clam wave energy device for small scale use is presented. Experimental tests to measure the productivity of the Clam system, using 1/14th linear scale models of a 80 m long x 7 to 9 m deep x 5 m wide device intended for small community use are outlined. A feature of these experiments has been the development of a rotating damper which enables damping rate to be readily varied during a series of successive tests, a major advance in power measurements of air systems at this scale. Development of corded bags, progress made during the period with mathematical modelling of the turbine-generator power take-off system, and use of paralleled induction generators run at near-synchronous speed in conjuction with either a 3-phase base supply or an on-board alternator to provide magnetization current are discussed.

Ecotoxicological evaluation of tributyltin toxicity to the equilateral venus clam, Gomphina veneriformis (Bivalvia: Veneridae).

Science.gov (United States)

Park, Kiyun; Kim, Rosa; Park, Jung Jun; Shin, Hyun Chool; Lee, Jung Sick; Cho, Hyeon Seo; Lee, Yeon Gyu; Kim, Jongkyu; Kwak, Inn-Sil

2012-03-01

Tributyltin (TBT) is the most common pesticide in marine and freshwater environments. To evaluate the potential ecological risk posed by TBT, we measured biological responses such as growth rate, gonad index, sex ratio, the percentage of intersex gonads, filtration rate, and gill abnormalities in the equilateral venus clam (Gomphina veneriformis). Additionally, the biochemical and molecular responses were evaluated in G. veneriformis exposed to various concentrations of TBT. The growth of G. veneriformis was significantly delayed in a dose-dependent manner after exposure to all tested TBT concentrations. After TBT was administered to G. veneriformis, the gonad index decreased and the sex balance was altered. The percentage of intersex gonads also increased significantly in treated females, whereas no intersex gonads were detected in the solvent control group. Additionally, intersex gonads were detected in male G. veneriformis specimens exposed to relatively high TBT concentrations (20 μg L⁻¹). The filtration rate was also reduced in a dose-dependent manner in TBT-exposed G. veneriformis. We also noted abnormal gill morphology in TBT-exposed G. veneriformis. Furthermore, increases in antioxidant enzyme activities were observed in TBT-exposed G. veneriformis clams, regardless of dosage. Vitellogenin gene expression also increased significantly in a dose-dependent manner in G. veneriformis exposed to TBT. These results provide valuable information regarding our understanding of the toxicology of TBT in G. veneriformis. Moreover, the responses of biological and molecular factors could be utilized as information for risk assessments and marine monitoring of TBT toxicity. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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

2015-12-01

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 with chlorophyll a suggested that the development of the reproductive cycle of M. lyrata required a high amount of food to increase gametogenesis.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Survival and growth of the giant clam larvae utilizing zooxanthellae from Acropora valenciennesi, Tridacna crocea and Sarcophyton trocheliophorum

OpenAIRE

A. Niartiningsih; Magdalena Litaay; Niradhyna W. M

2015-01-01

The aim of this study was to know the survival and growth of the giant clam larvae given zooxanthellae from different host. The field experiment was conducted from September ???November 2006 at hatchery of Marine Field Station Barrang Lompo Island, Makassar. Zooxanthellae hosts used were: (A) Table coral (Acropora valenciennesi); (B) Tridacna crocea, (C) soft coral (Sarcophyton trocheliophorum) and (D) control (no additional zooxanthellae). The Complete Randomized Design with four treatments ...

Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic). SURF CLAM

Science.gov (United States)

1983-10-01

ter across the vitelline membrane; the Male and female surf clams are identi- innqr germinal vesicle averages 0.79 cal in external appearance, and...Jones et al. ) (1978) reported age-size relationships In laboratcry experiments con- using cut and polished shells (Table ducted •t 21.7 0 C (71 0 F...and Long Island’s south period (4-6 weeks), due to a persist - shore, out. to a depth of 75 m (246 ent southerly flow of air;. and ft), because of the

Microstructure and mechanical properties in TIG welding of CLAM steel

International Nuclear Information System (INIS)

Zhu Qiang; Lei Yucheng; Chen Xizhang; Ren Wenjie; Ju Xin; Ye Yimin

2011-01-01

Tungsten insert gas (TIG) welding on China low activation martensitic (CLAM) steel under identical conditions was performed. Microhardness test, tensile test, Charpy impact test and microstructure measurements were carried out on TIG welded joints after post weld heat-treatment. Hardening at WM and softening in HAZ is detected in the TIG weld joint. Microhardness in WM decreased when the temperature of PWHT increased. The ultimate tensile stress of weld metal is higher than that of HAZ and BM. Absorbed energy increased with PWHT temperature rising, until PWHT was done at 760 deg. C/30 min, the specimen ductile fractured in local area. The microstructure of the weld metal for every specimen was found to be tempered martensite with a little of delta ferrite. M 23 C 6 particles are the predominant type of carbides. Oxide precipitate phases appeared in WM, which are the primary crack initiation sites and it is critically important minimize their formation.

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

2016-11-01

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.

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.

A family 5 β-mannanase from the thermophilic fungus Thielavia arenaria XZ7 with typical thermophilic enzyme features.

Science.gov (United States)

Lu, Haiqiang; Zhang, Huitu; Shi, Pengjun; Luo, Huiying; Wang, Yaru; Yang, Peilong; Yao, Bin

2013-09-01

A novel β-mannanase gene, man5XZ7, was cloned from thermophilic fungus Thielavia arenaria XZ7, and successfully expressed in Pichia pastoris. The gene (1,110 bp) encodes a 369-amino acid polypeptide with a molecular mass of approximately 40.8 kDa. The deduced sequence of Man5XZ7 consists of a putative 17-residue signal peptide and a catalytic module belonging to glycoside hydrolase (GH) family 5, and displays 76 % identity with the experimentally verified GH 5 endo-β-1,4-mannanase from Podospora anserina. Recombinant Man5XZ7 was optimally active at 75 °C and pH 5.0 and exhibited high activity at a wide temperature range (>50.0 % activity at 50-85 °C). Moreover, it had good adaptability to acidic to basic pH (>74.1 % activity at pH 4.0-7.0 and 25.6 % even at pH 9.0) and good stability from pH 3.0 to 10.0. These enzymatic properties showed that Man5XZ7 was a new thermophilic and alkali-tolerant β-mannanase. Further amino acid composition analysis indicated that Man5XZ7 has several characteristic features of thermophilic enzymes.

The Effect of Season on the Metabolic Profile of the European Clam Ruditapes decussatus as Studied by 1H-NMR Spectroscopy

Directory of Open Access Journals (Sweden)

Violetta Aru

2017-07-01

Full Text Available In this study, the metabolome of Ruditapes decussatus, an economically and ecologically important marine bivalve species widely distributed in the Mediterranean region, was characterized by using proton Nuclear Magnetic Resonance (1H-NMR spectroscopy. Significant seasonal variations in the content of carbohydrates and free amino acids were observed. The relative amounts of alanine and glycine were found to exhibit the same seasonal pattern as the temperature and salinity at the harvesting site. Several putative sex-specific biomarkers were also discovered. Substantial differences were found for alanine and glycine, whose relative amounts were higher in males, while acetoacetate, choline and phosphocholine were more abundant in female clams. These findings reveal novel insights into the baseline metabolism of the European clam and represent a step forward towards a comprehensive metabolic characterization of the species. Besides providing a holistic view on the prominent nutritional components, the characterization of the metabolome of this bivalve represents an important prerequisite for elucidating the underlying metabolic pathways behind the environment-organism interactions.

ALAM/CLAM and some applications of computer algebra systems to problems in general relativity

International Nuclear Information System (INIS)

Russell-Clark, R.A.

1973-01-01

This paper is divided into three parts. Part A presents a historical survey of the development of the system, a brief description of its features and, finally, a critical assessment. ALAM and CLAM have been used in many problems in General Relativity; the vast majority of these belong to a set of standard calculations termed ''metric applications''. However, four large non-standard applications have been attempted successfully and these are described in Part B. CAMAL is the only other system which has been used extensively for work in relativity. CAMAL has played an important role in two research projects and details of these are given in Part C

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.

Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea

KAUST Repository

Pappas, Melissa

2017-05-19

The biodiversity of the Red Sea remains relatively understudied, particularly for invertebrate taxa. Documenting present patterns of biodiversity is essential for better understanding Red Sea reef ecosystems and how these ecosystems may be impacted by stressors (such as fishing and climate change). Several species of giant clams (genus Tridacna) are reported from the Red Sea, although the majority of research effort has occurred in the Gulf of Aqaba. We investigated the genetic diversity (16S rDNA) of the Tridacna species found in the central Saudi Arabian Red Sea. We also investigated the genetic diversity (ITS rDNA) of symbiotic dinoflagellates Symbiodinium associated with these clams. Samples were collected from nine reefs on a cross-shelf gradient near Thuwal, Saudi Arabia. Two species, T. squamosa and T. maxima, were recorded, with the latter being the most abundant. Tridacna squamosina, a species recently reported in the northern Red Sea, was not found, suggesting that this species is not present or is very rare in our study region. All tridacnids sampled were found to harbor Symbiodinium grouped in Clade A, considered an opportunistic, heat-tolerant symbiont group in anemones and corals. The consistent association with Clade A Symbiodinium in central Red Sea tridacnids may reflect the consequence of adaptation to the relatively extreme conditions of the Red Sea. This study contributes to an ever-growing catalog of Red Sea biodiversity and serves as important baseline information for a region experiencing dynamic pressures.

Genetic diversity of giant clams (Tridacna spp.) and their associated Symbiodinium in the central Red Sea

KAUST Repository

Pappas, Melissa; He, Song; Hardenstine, Royale; Kanee, Hana; Berumen, Michael L.

2017-01-01

The biodiversity of the Red Sea remains relatively understudied, particularly for invertebrate taxa. Documenting present patterns of biodiversity is essential for better understanding Red Sea reef ecosystems and how these ecosystems may be impacted by stressors (such as fishing and climate change). Several species of giant clams (genus Tridacna) are reported from the Red Sea, although the majority of research effort has occurred in the Gulf of Aqaba. We investigated the genetic diversity (16S rDNA) of the Tridacna species found in the central Saudi Arabian Red Sea. We also investigated the genetic diversity (ITS rDNA) of symbiotic dinoflagellates Symbiodinium associated with these clams. Samples were collected from nine reefs on a cross-shelf gradient near Thuwal, Saudi Arabia. Two species, T. squamosa and T. maxima, were recorded, with the latter being the most abundant. Tridacna squamosina, a species recently reported in the northern Red Sea, was not found, suggesting that this species is not present or is very rare in our study region. All tridacnids sampled were found to harbor Symbiodinium grouped in Clade A, considered an opportunistic, heat-tolerant symbiont group in anemones and corals. The consistent association with Clade A Symbiodinium in central Red Sea tridacnids may reflect the consequence of adaptation to the relatively extreme conditions of the Red Sea. This study contributes to an ever-growing catalog of Red Sea biodiversity and serves as important baseline information for a region experiencing dynamic pressures.

Three vibrio-resistance related EST-SSR markers revealed by selective genotyping in the clam Meretrix meretrix.

Science.gov (United States)

Nie, Qing; Yue, Xin; Chai, Xueliang; Wang, Hongxia; Liu, Baozhong

2013-08-01

The clam Meretrix meretrix is an important commercial bivalve distributed in the coastal areas of South and Southeast Asia. In this study, marker-trait association analyses were performed based on the stock materials of M. meretrix with different vibrio-resistance profile obtained by selective breeding. Forty-eight EST-SSR markers were screened and 27 polymorphic SSRs of them were genotyped in the clam stocks with different resistance to Vibrio parahaemolyticus (11-R and 11-S) and to Vibrio harveyi (09-R and 09-C). Allele frequency distributions of the SSRs among different stocks were compared using Pearson's Chi-square test, and three functional EST-SSR markers (MM959, MM4765 and MM8364) were found to be associated with vibrio-resistance trait. The 140-bp allele of MM959 and 128-bp allele of MM4765 had significantly higher frequencies in resistant groups (11-R and 09-R) than in susceptive/control groups (11-S and 09-C) (P SSR markers were consistent with the three subgroups distinctions. The putative functions of contig959, contig4765 and contig8364 also suggested that the three SSR-involved genes might play important roles in immunity of M. meretrix. All these results supported that EST-SSR markers MM959, MM4765 and MM8364 were associated with vibrio-resistance and would be useful for marker-assisted selection (MAS) in M. meretrix genetic breeding. Copyright © 2013 Elsevier Ltd. All rights reserved.

Benthic non-indigenous species among indigenous species and their habitat preferences in Puck Bay (southern Baltic Sea* This work was carried out under the ‘Ecosystem Approach to Marine Spatial Planning – Polish Marine Areas and the Natura 2000 Network’ project founded by an EEA grant from Iceland, Lichtenstein and Norway and partly by research grant BW/G 220-5-0232-9.

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Urszula Janas

2014-06-01

Full Text Available To date 11 non-indigenous benthic taxa have been reported in Puck Bay (southern Baltic Sea. Five of the 34 taxa forming the soft bottom communities are regarded as non-indigenous to this area. They are Marenzelleria spp., Mya arenaria, Potamopyrgus antipodarum, Gammarus tigrinus and Amphibalanus improvisus. Non-indigenous species comprised up to 33% of the total number of identified macrofaunal taxa (mean 17%. The average proportion of aliens was 6% (max 46% in the total abundance of macrofauna, and 10% (max 65% in the biomass. A significant positive relationship was found between the numbers of native and non-indigenous taxa. The number of native taxa was significantly higher on a sea bed covered with vascular plants than on an unvegetated one, but no such relationship was found for their abundance. No significant differences were found in the number and abundance of non-indigenous species between sea beds devoid of vegetation and those covered with vascular plants, Chara spp. or mats of filamentous algae. G. tigrinus preferred a sea bed with vegetation, whereas Marenzelleria spp. decidedly preferred one without vegetation.

Clam wave energy converter. Report for period July 1979 to December 1980

Energy Technology Data Exchange (ETDEWEB)

1981-02-01

Work by the Sea Energy Asociates Ltd - Lanchester Polytechnic Wave Energy Group on the Clam device since the April 1979 feasibility study has shown it to be a well developed and viable device capable of extracting energy economically from sea waves. The experience of the team includes mooring, structural and device tests from 1/100th to 1/10th scale in narrow and wide tanks, Draycote Reservoir and on Loch Ness. Theoretical and semi-empirical modelling has become increasingly important. Recently a test rig to assess a 1/10th scale power take off system, based on a Wells turbine, has been completed. The philosophy of the project team has been to aim for a device as simple as possible, with a small number of moving parts in order to minimise maintenance problems.

Development of the 'SEA-Clam' wave energy device for small scale use. Interim report 1st August 1983 - 30th April 1984

Energy Technology Data Exchange (ETDEWEB)

1984-04-01

An Interim Report on the development of the Sea-Clam wave energy device for small scale use is presented. Experimental tests to measure the productivity of the Clam system, using 1/14th linear scale models of a 80 m long x 7 to 9 m deep x 5 m wide device intended for small community use are outlined. A feature of these experiments has been the development of a rotating damper which enables damping rate to be readily varied during a series of successive tests, a major advance in power measurements of air systems at this scale. Development of corded bags, progress made during the period with mathematical modelling of the turbine-generator power take-off system, and use of paralleled induction generators run at near-synchronous speed in conjuction with either a 3-phase base supply or an on-board alternator to provide magnetization current are discussed.

Conversion of Biowaste Asian Hard Clam (Meretrix lusoria) Shells into White-Emitting Phosphors for Use in Neutral White LEDs.

Science.gov (United States)

Chang, Tsung-Yuan; Wang, Chih-Min; Lin, Tai-Yuan; Lin, Hsiu-Mei

2016-12-02

The increasing volume and complexity of waste associated with the modern economy poses a serious risk to ecosystems and human health. However, the remanufacturing and recycling of waste into usable products can lead to substantial resource savings. In the present study, clam shell waste was first transformed into pure and well-crystallized single-phase white light-emitting phosphor Ca₉Gd(PO₄)₇:Eu 2+ ,Mn 2+ materials. The phosphor Ca₉Gd(PO₄)₇:Eu 2+ ,Mn 2+ materials were synthesized by the solid-state reaction method and the carbothermic reduction process, and then characterized and analyzed by means of X-ray diffraction (XRD) and photoluminescence (PL) measurements. The structural and luminescent properties of the phosphors were investigated as well. The PL and quantum efficiency measurements showed that the luminescence properties of clam shell-based phosphors were comparable to that of the chemically derived phosphors. Moreover, white light-emitting diodes were fabricated through the integration of 380 nm chips and single-phase white light-emitting phosphors (Ca 0.979 Eu 0.006 Mn 0.015 )₉Gd(PO₄)₇ into a single package of a white light emitting diode (WLED) emitting a neutral white light of 5298 K with color coordinates of (0.337, 0.344).

Conversion of Biowaste Asian Hard Clam (Meretrix lusoria Shells into White-Emitting Phosphors for Use in Neutral White LEDs

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Tsung-Yuan Chang

2016-12-01

Full Text Available The increasing volume and complexity of waste associated with the modern economy poses a serious risk to ecosystems and human health. However, the remanufacturing and recycling of waste into usable products can lead to substantial resource savings. In the present study, clam shell waste was first transformed into pure and well-crystallized single-phase white light-emitting phosphor Ca9Gd(PO47:Eu2+,Mn2+ materials. The phosphor Ca9Gd(PO47:Eu2+,Mn2+ materials were synthesized by the solid-state reaction method and the carbothermic reduction process, and then characterized and analyzed by means of X-ray diffraction (XRD and photoluminescence (PL measurements. The structural and luminescent properties of the phosphors were investigated as well. The PL and quantum efficiency measurements showed that the luminescence properties of clam shell-based phosphors were comparable to that of the chemically derived phosphors. Moreover, white light-emitting diodes were fabricated through the integration of 380 nm chips and single-phase white light-emitting phosphors (Ca0.979Eu0.006Mn0.0159Gd(PO47 into a single package of a white light emitting diode (WLED emitting a neutral white light of 5298 K with color coordinates of (0.337, 0.344.

The Manila clam population in Arcachon Bay (SW France): Can it be kept sustainable?

Science.gov (United States)

Dang, Cécile; de Montaudouin, Xavier; Gam, Mériame; Paroissin, Christian; Bru, Noëlle; Caill-Milly, Nathalie

2010-02-01

The venerid clam Ruditapes philippinarum is the most prominent suspension-feeding bivalve inhabiting muddy intertidal seagrass beds in Arcachon Bay (SW France). It is exploited by fishermen, and Arcachon Bay ranks number one in France in terms of production and total biomass of this species. Previous studies revealed a decrease in the standing stock of R. philippinarum since 2003 and unbalanced length-frequency distributions with a lack of juveniles and of adults > 40 mm. Consequently, the population dynamics of this bivalve were studied at four intertidal sites and one oceanic site in Arcachon Bay. As clam size structure did not allow classical dynamics computations, field monitoring was coupled with field experiments (tagging-recapture) over two years. Monitoring of condition index and gonadal maturation stages highlighted a high variability in spawning number and intensity between sites. Recruitment events in the exploited area varied spatially but with uniformly low values. Von Bertalanffy Growth Function (VBGF) parameters ( K, L∞) were determined using Appeldoorn and ELEFAN methods. In the exploited sites in the inner lagoon, K was relatively high (mean = 0.72 yr - 1 ) but L∞ was low (mean = 41.1 mm) resulting in a moderate growth performance index (Φ' = 2.99). Growth parameters were not correlated with immersion time and L∞ was different between sites. Comparison of mortality coefficients ( Z) between cage experiments and field monitoring suggested that fishing accounts for 65-75% of total adult mortality. Low recruitment, a low growth rate and a normal mortality rate led to low somatic production (4.1 and 8.7 g Shell-Free Dry Weight (SFDW) m - 2 yr - 1 ) and an annual P/ B ratio from 0.44 to 0.92 yr - 1 . Under current conditions, the possibility of a sustainable population in Arcachon Bay will strongly depend on recruitment success and fishing management.

Paralytic shellfish toxins in the chocolata clam, Megapitaria squalida (Bivalvia: Veneridae, in Bahía de La Paz, Gulf of California

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I Gárate-Lizárraga

2004-09-01

Full Text Available Occurrence and toxic profiles of paralytic shellfish toxins (PST in the chocolata clam Megapitaria squalida were investigated. From December 2001 to December 2002, 25 clams were obtained monthly from Bahía de La Paz, Gulf of California. Additionally, net (20 µm and bottle phytoplankton samples were also collected to identify toxic species. Toxins were analyzed by HPLC with post-column oxidation and fluorescence detection. Toxicity in the clam was low and varied from 0.14 to 5.46 µg/STXeq/100 g. Toxicity was detected in December, March, April, June, and August. Toxin profile was composed mainly by STX, GTX2, GTX3, dcGTX2, dcGTX3, C2, dcSTX and B1. Gymnodinium catenatum was the only PST-producing dinoflagellate identified in the phytoplankton samples throughout the study period. G. catenatum was observed mainly in net samples from December 2001 to December 2002; however, in bottle samples, G. catenatum was only observed in five months. Highest abundance (2 600 cells l-1 was observed in March and the lowest (160 cells l-1 in June. G. catenatum mainly formed two-cell chains and rarely four or eight. The presence of PST in net phytoplankton samples support the fact that G. catenatum is the main source of PST in the clams. This study represents the first report of PST toxins in the chocolata clam from Bahía de La PazSe investigó la ocurrencia así como los perfiles de toxinas paralíticas (PST en la almeja chocolata Megapitaria squalida (Sowerby, 1835, de la cual se recolectaron mensualmente 25 ejemplares de diciembre del 2001 a diciembre del 2000 en La Bahía de La Paz, Golfo de California. Simultáneamente, se obtuvieron muestras de fitoplancton de botella y de red (20 µM para identificar especies tóxicas, así como para detectar la presencia de toxinas paralíticas. Las toxinas se analizaron por HPLC con una oxidación post-columna y detección fluorescente. La toxicidad en las almejas fue baja y varió de 0.14 a 5.46 µg/STXeq/100 g y se

Comparative genomics of vesicomyid clam (Bivalvia: Mollusca chemosynthetic symbionts

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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.

Mesozoic fossils (>145 Mya suggest the antiquity of the subgenera of Daphnia and their coevolution with chaoborid predators

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Taylor Derek J

2011-05-01

Full Text Available Abstract Background The timescale of the origins of Daphnia O. F. Mueller (Crustacea: Cladocera remains controversial. The origin of the two main subgenera has been associated with the breakup of the supercontinent Pangaea. This vicariance hypothesis is supported by reciprocal monophyly, present day associations with the former Gondwanaland and Laurasia regions, and mitochondrial DNA divergence estimates. However, previous multilocus nuclear DNA sequence divergence estimates at Daphnia. Results We describe new fossils of ephippia from the Khotont site in Mongolia associated with the Jurassic-Cretaceous boundary (about 145 MYA that are morphologically similar to several modern genera of the family Daphniidae, including the two major subgenera of Daphnia, i.e., Daphnia s. str. and Ctenodaphnia. The daphniid fossils co-occurred with fossils of the predaceous phantom midge (Chaoboridae. Conclusions Our findings indicate that the main subgenera of Daphnia are likely much older than previously known from fossils (at least 100 MY older or from nuclear DNA estimates of divergence. The results showing co-occurrence of the main subgenera far from the presumed Laurasia/Gondwanaland dispersal barrier shortly after formation suggests that vicariance from the breakup of Pangaea is an unlikely explanation for the origin of the main subgenera. The fossil impressions also reveal that the coevolution of a dipteran predator (Chaoboridae with the subgenus Daphnia is much older than previously known -- since the Mesozoic.

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

International Nuclear Information System (INIS)

Ivanina, Anna V.; Beniash, Elia; Etzkorn, Markus; Meyers, Tiffany B.; Ringwood, Amy H.; Sokolova, Inna M.

2013-01-01

Highlights: •P CO 2 alters accumulation of Cd and Cu in clam cells. •Accumulation of Cd induces release of free Zn 2+ . •Accumulation of Cu induces an increase in free Cu 2+ and Fe 2+ . •Metal-induced oxidative stress is alleviated at high P CO 2 . •Toxicity of Cu in likely enhanced while that of Cd alleviated by high P CO 2 . -- Abstract: Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO 2 (P CO 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 CO 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 CO 2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of P CO 2 (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated P CO 2 resulted in a decrease in intracellular pH (pH i ) of the isolated mantle cells from 7.8 to 7.4. Elevated P CO 2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated P CO 2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd 2+ concentration remained the same, while intracellular levels of free Zn 2+ increased suggesting that Cd 2+ substitutes bound Zn 2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn 2+ but led to a profound increase in the intracellular levels

The Whitish Inner Mantle of the Giant Clam, Tridacna squamosa, Expresses an Apical Plasma Membrane Ca2+-ATPase (PMCA Which Displays Light-Dependent Gene and Protein Expressions

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Yuen K. Ip

2017-10-01

Full Text Available Giant clams live in symbiosis with extracellular zooxanthellae and display high rates of growth and shell formation (calcification in light. Light-enhanced calcification requires an increase in the supply of Ca2+ to, and simultaneously an augmented removal of H+ from, the extrapallial fluid where shell formation occurs. We have obtained the complete coding cDNA sequence of Plasma Membrane Ca2+-ATPase (PMCA from the thin and whitish inner mantle, which is in touch with the extrapallial fluid, of the giant clam Tridacna squamosa. The deduced PMCA sequence consisted of an apical targeting element. Immunofluorescence microscopy confirmed that PMCA had an apical localization in the shell-facing epithelium of the inner mantle, whereby it can actively secrete Ca2+ in exchange for H+. More importantly, the apical PMCA-immunofluorescence of the shell-facing epithelium of the inner mantle increased significantly after 12 h of exposure to light. The transcript and protein levels of PMCA/PMCA also increased significantly in the inner mantle after 6 or 12 h of light exposure. These results offer insights into a light-dependable mechanism of shell formation in T. squamosa and a novel explanation of light-enhanced calcification in general. As the inner mantle normally lacks light sensitive pigments, our results support a previous proposition that symbiotic zooxanthellae, particularly those in the colorful and extensible outer mantle, may act as light-sensing elements for the host clam.

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.

Baseline of organotin pollution in fishes, clams, shrimps, squids and crabs collected from the west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Jadhav, S.; Bhosale, D.; Bhosle, N.B.

is available. The present study was planned to assess organotin contamination levels in edible marine organisms collected from the fish markets of Goa, Karwar and Mumbai, the west coast of India. The sampling locations: Goa (15.5ºN, 73.9ºE), Karwar (14.8º... of Karwar is around 36,000 tonnes. Mumbai coast is about 140 km long. Mumbai is among busiest harbours on the west coast of India is known for industrial pollution. The fishes, clams, crabs and squids and shrimps were collected from local fish markets...

Bio-accumulation of some trace metals in the short-neck clam Paphia malabarica from Mandovi estuary, Goa

Digital Repository Service at National Institute of Oceanography (India)

KrishnaKumari, L.; Kaisary, S.; Rodrigues, V.

distributed along the coast of Goa and forms an inexpensive and delicious seafood among recorded as Ag/g dry weight in the whole soft tissue was 3.8, 30.3, 13.5, estuary, Goa. Clams were categorised into two groups, 25–35 mm (small size) and 35–40 mm (big size.... Concentration factor was determined as a ratio of mean metal content (dissolved) in water (Ag/l) and that in the soft tissue (Ag/kg wet weight). All the analyses were carried out in duplicate, and the average values are reported in this paper. 3. Results...

Effects of Peanut-Tobacco Rotations on Population Dynamics of Meloidogyne arenaria in Mixed Race Populations.

Science.gov (United States)

Hirunsalee, A; Barker, K R; Beute, M K

1995-06-01

A 3-year microplot study was initiated to characterize the population dynamics, reproduction potential, and survivorship of single or mixed populations of Meloidogyne arenaria race 1 (Ma1) and race 2 (Ma2), as affected by crop rotations of peanut 'Florigiant' and M. incognita races 1 and 3-resistant 'McNair 373' and susceptible 'Coker 371-Gold' tobacco. Infection, reproduction, and root damage by Ma2 on peanut and by Ma1 on resistant tobacco were limited in the first year. Infection, reproduction, and root-damage potentials on susceptible tobacco were similar for Ma1 and Ma2. In the mixed (1:1) population, Ma1 was dominant on peanut and Ma2 was dominant on both tobacco cultivars. Crop rotation affected the population dynamics of different nematode races. For years 2 and 3, the low numbers of Ma1 and Ma2 from a previous-year poor host increased rapidly on suitable hosts. Ma1 had greater reproduction factors ([RF] = population density at harvest/population density at preplandng) than did Ma2 and Ma1 + Ma2 in second-year peanut plots following first-year resistant tobacco, and in third-year peanut plots following second-year tobacco. In mixed infestations, Ma1 predominated over Ma2 in previous-year peanut plots, whereas Ma2 predominated over Ma1 in previous-year tobacco plots. Moderate damage on resistant tobacco was induced by Ma1 in the second year. In the third year, moderate damage on peanut was associated with 'Ma2' from previous-year peanut plots. The resistant tobacco supported sufficient reproduction of Ma1 over 2 years to effect moderate damage and yield suppression to peanut in year 3.

Mesozoic fossils (>145 Mya) suggest the antiquity of the subgenera of Daphnia and their coevolution with chaoborid predators.

Science.gov (United States)

Kotov, Alexey A; Taylor, Derek J

2011-05-19

The timescale of the origins of Daphnia O. F. Mueller (Crustacea: Cladocera) remains controversial. The origin of the two main subgenera has been associated with the breakup of the supercontinent Pangaea. This vicariance hypothesis is supported by reciprocal monophyly, present day associations with the former Gondwanaland and Laurasia regions, and mitochondrial DNA divergence estimates. However, previous multilocus nuclear DNA sequence divergence estimates at Pangaea. We examined new and existing cladoceran fossils from a Mesozoic Mongolian site, in hopes of gaining insights into the timescale of the evolution of Daphnia. We describe new fossils of ephippia from the Khotont site in Mongolia associated with the Jurassic-Cretaceous boundary (about 145 MYA) that are morphologically similar to several modern genera of the family Daphniidae, including the two major subgenera of Daphnia, i.e., Daphnia s. str. and Ctenodaphnia. The daphniid fossils co-occurred with fossils of the predaceous phantom midge (Chaoboridae). Our findings indicate that the main subgenera of Daphnia are likely much older than previously known from fossils (at least 100 MY older) or from nuclear DNA estimates of divergence. The results showing co-occurrence of the main subgenera far from the presumed Laurasia/Gondwanaland dispersal barrier shortly after formation suggests that vicariance from the breakup of Pangaea is an unlikely explanation for the origin of the main subgenera. The fossil impressions also reveal that the coevolution of a dipteran predator (Chaoboridae) with the subgenus Daphnia is much older than previously known -- since the Mesozoic.

Biomonitoring approach with mussel Mytilus galloprovincialis (Lmk) and clam Ruditapes philippinarum (Adams and Reeve, 1850) in the Lagoon of Venice.

Science.gov (United States)

Moschino, Vanessa; Delaney, Eugenia; Meneghetti, Francesca; Ros, Luisa Da

2011-06-01

Transplanted Mytilus galloprovincialis and native Ruditapes philippinarum were deployed in 10 sampling stations with different pollution impact within the Lagoon of Venice to evaluate the temporal variations and the suitability of the following cytochemical and histochemical biomarkers just as indicators of environmental stress: lysosomal membrane stability, lipofuscins, neutral lipids and lysosome to cytoplasm volume ratio. The physiological status of the organisms was also investigated by determining the survival in air capability and the reburrowing rate (clams). The biological parameters were assessed in June and October. Furthermore, for a better definition of the environmental aspects of the study sites, heavy metal, PAH and PCB concentrations were also evaluated in the sediments. As a whole, the biological responses examined in both species from all the sampling sites showed significant differences between the two seasonal campaigns, only lysosomal membrane stability exhibited less variability. Pollutants in sediments generally showed low-intermediate contamination levels, few hotspots persisting mostly in the inner areas of the lagoon, the most influenced by the industrial zone. Transplanted mussels were more responsive than native clams and the biological responses of both species varied temporally. The range of the spatial variability was always narrow and reflected only partially the broader variability shown by the chemical content in the sediments. In this sense, biological responses seemed to be particularly influenced by the high temporal and spatial heterogeneity that characterise the Lagoon of Venice, as well as most of the transitional environments.

Consequences of an uncertain mass mortality regime triggered by climate variability on giant clam population management in the Pacific Ocean.

Science.gov (United States)

Van Wynsberge, Simon; Andréfouët, Serge; Gaertner-Mazouni, Nabila; Remoissenet, Georges

2018-02-01

Despite actions to manage sustainably tropical Pacific Ocean reef fisheries, managers have faced failures and frustrations because of unpredicted mass mortality events triggered by climate variability. The consequences of these events on the long-term population dynamics of living resources need to be better understood for better management decisions. Here, we use a giant clam (Tridacna maxima) spatially explicit population model to compare the efficiency of several management strategies under various scenarios of natural mortality, including mass mortality due to climatic anomalies. The model was parameterized by in situ estimations of growth and mortality and fishing effort, and was validated by historical and new in situ surveys of giant clam stocks in two French Polynesia lagoons. Projections on the long run (100 years) suggested that the best management strategy was a decrease of fishing pressure through quota implementation, regardless of the mortality regime considered. In contrast, increasing the minimum legal size of catch and closing areas to fishing were less efficient. When high mortality occurred due to climate variability, the efficiency of all management scenarios decreased markedly. Simulating El Niño Southern Oscillation event by adding temporal autocorrelation in natural mortality rates increased the natural variability of stocks, and also decreased the efficiency of management. These results highlight the difficulties that managers in small Pacific islands can expect in the future in the face of global warming, climate anomalies and new mass mortalities. Copyright © 2017 Elsevier Inc. All rights reserved.

Molecular characterization of a novel algal glutamine synthetase (GS) and an algal glutamate synthase (GOGAT) from the colorful outer mantle of the giant clam, Tridacna squamosa, and the putative GS-GOGAT cycle in its symbiotic zooxanthellae.

Science.gov (United States)

Fam, Rachel R S; Hiong, Kum C; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

2018-05-20

Giant clams harbor symbiotic zooxanthellae (Symbiodinium), which are nitrogen-deficient, mainly in the fleshy and colorful outer mantle. This study aimed to sequence and characterize the algal Glutamine Synthetase (GS) and Glutamate Synthase (GLT), which constitute the glutamate synthase cycle (or GS-GOGAT cycle, whereby GOGAT is the protein acronym of GLT) of nitrogen assimilation, from the outer mantle of the fluted giant clam, Tridacna squamosa. We had identified a novel GS-like cDNA coding sequence of 2325 bp, and named it as T. squamosa Symbiodinium GS1 (TSSGS1). The deduced TSSGS1 sequence had 774 amino acids with a molecular mass of 85 kDa, and displayed the characteristics of GS1 and Nucleotide Diphosphate Kinase. The cDNA coding sequence of the algal GLT, named as T. squamosa Symbiodinium GLT (TSSGLT), comprised 6399 bp, encoding a protein of 2133 amino acids and 232.4 kDa. The zooxanthellal origin of TSSGS1 and TSSGOGAT was confirmed by sequence comparison and phylogenetic analyses. Indeed, TSSGS1 and TSSGOGAT were expressed predominately in the outer mantle, which contained the majority of the zooxanthellae. Immunofluorescence microscopy confirmed the expression of TSSGS1 and TSSGOGAT in the cytoplasm and the plastids, respectively, of the zooxanthellae in the outer mantle. It can be concluded that the symbiotic zooxanthellae of T. squamosa possesses a glutamate synthase (TSSGS1-TSSGOGAT) cycle that can assimilate endogenous ammonia produced by the host clam into glutamate, which can act as a substrate for amino acid syntheses. Thus, our results provide insights into why intact giant clam-zooxanthellae associations do not excrete ammonia under normal circumstances. Copyright © 2018 Elsevier B.V. All rights reserved.

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

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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.

Parasites of the hard clam Meretrix meretrix Linnaeus from Western Johor Straits, Malaysian

Science.gov (United States)

Azmi, Nur Fauzana; Ghaffar, Mazlan Abd.; Cob, Zaidi Che

2014-09-01

This study describes the apicomplexa as well as other parasites infecting organs/tissues of the hard clam Meretrix meretrix Linnaeus, from Merambong Shoal, Western Johor Straits, Malaysia. Samples were collected randomly by hand picking, in November and December 2013. Histological techniques were performed, stained using Masson's Trichrome protocol and observed under light microscope. The results showed that gonad and gill were the most infected organs followed by digestive gland, intestine and adductor muscle. No pathology condition was observed in the mantle. Histophatological examination showed that the gregarine, Nematopsis, unidentified coccidian and Perkinsus were found in the gill and gonad, and also in the numerous hemocytes. Other pathological conditions such as bacteria-like inclusion and intracellular bacteria were also observed in the same organs. Further investigations are needed particularly on other molluscs present at the study area. Understanding the morphology and pathology of parasites infecting mollusks are very important for management of the resources.

Sequencing and de novo assembly of the Asian clam (Corbicula fluminea transcriptome using the Illumina GAIIx method.

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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.

Genetic diversity and population differentiation of small giant clam Tridacna maxima in Comoros islands assessed by microsatellite markers.

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Ahmed Mohamed, Nadjim; Yu, Qian; Chanfi, Mohamed Ibrahim; Li, Yangping; Wang, Shi; Huang, Xiaoting; Bao, Zhenmin

2016-01-01

Small giant clam, Tridacna maxima , widely distributed from French Polynesia to East Africa, has faced population declines due to over-exploitation. Comoros islands are an important biogeographic region due to potential richness of marine species, but no relevant information is available. In order to facilitate devising effective conservation management plan for T. maxima , nine microsatellite markers were used to survey genetic diversity and population differentiation of 72 specimens collected from three Comoros islands, Grande Comore, Moheli and Anjouan. A total of 51 alleles were detected ranged from 2 to 8 per locus. Observed and expected heterozygosity varied from 0.260 to 0.790 and from 0.542 to 0.830, respectively. All populations have high genetic diversity, especially the population in Moheli, a protected area, has higher genetic diversity than the others. Significant heterozygote deficiencies were recorded, and null alleles were probably the main factor leading to these deficits. F ST value indicated medium genetic differentiation among the populations. Although significant, AMOVA revealed 48.9 % of genetic variation within individuals and only a small variation of 8.9 % was found between populations. Gene flow was high ( Nm  = 12.40) between Grande Comore and Moheli, while lower ( Nm  = 1.80) between Grande Comore and Anjouan, explaining geographic barriers to genetic exchanges might exist in these two islands. Global gene flow analysis ( Nm  = 5.50) showed that larval dispersal is enough to move between the islands. The high genetic diversity and medium population differentiation revealed in the present study offer useful information on genetic conservation of small giant clams.

Seawater acidification affects the physiological energetics and spawning capacity of the Manila clam Ruditapes philippinarum during gonadal maturation.

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Xu, Xian; Yang, Feng; Zhao, Liqiang; Yan, Xiwu

2016-06-01

Ocean acidification is predicted to have widespread implications for marine bivalve mollusks. While our understanding of its impact on their physiological and behavioral responses is increasing, little is known about their reproductive responses under future scenarios of anthropogenic climate change. In this study, we examined the physiological energetics of the Manila clam Ruditapes philippinarum exposed to CO 2 -induced seawater acidification during gonadal maturation. Three recirculating systems filled with 600 L of seawater were manipulated to three pH levels (8.0, 7.7, and 7.4) corresponding to control and projected pH levels for 2100 and 2300. In each system, temperature was gradually increased ca. 0.3°C per day from 10 to 20°C for 30days and maintained at 20°C for the following 40days. Irrespective of seawater pH levels, clearance rate (CR), respiration rate (RR), ammonia excretion rate (ER), and scope for growth (SFG) increased after a 30-day stepwise warming protocol. When seawater pH was reduced, CR, ratio of oxygen to nitrogen, and SFG significantly decreased concurrently, whereas ammonia ER increased. RR was virtually unaffected under acidified conditions. Neither temperature nor acidification showed a significant effect on food absorption efficiency. Our findings indicate that energy is allocated away from reproduction under reduced seawater pH, potentially resulting in an impaired or suppressed reproductive function. This interpretation is based on the fact that spawning was induced in only 56% of the clams grown at pH 7.4. Seawater acidification can therefore potentially impair the physiological energetics and spawning capacity of R. philippinarum. Copyright © 2016 Elsevier Inc. All rights reserved.

Northern Marshall Islands radiological survey: radionuclide concentrations in fish and clams and estimated doses via the marine pathway

International Nuclear Information System (INIS)

Robison, W.L.; Noshkin, V.E.; Phillips, W.A.; Eagle, R.J.

1981-01-01

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 90 Sr, 137 Cs, 238 Pu, 239+240 Pu, 241 Am, 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 90 Sr 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+240 Pu concentration in the muscle tissue of all reef species, however, is higher than that in pelagic lagoon fish. In contrast, 137 Cs 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

Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

International Nuclear Information System (INIS)

Zhou, Qing; Zhang, Yong; Peng, Hui-Fang; Ke, Cai-Huan; Huang, He-Qing

2014-01-01

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

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

Light exposure enhances urea absorption in the fluted giant clam, Tridacna squamosa, and up-regulates the protein abundance of a light-dependent urea active transporter, DUR3-like, in its ctenidium.

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Chan, Christabel Y L; Hiong, Kum C; Boo, Mel V; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

2018-04-19

Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates ( Symbiodinium spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them. This study aimed to demonstrate light-enhanced urea absorption in the fluted giant clam, Tridacna squamosa , and to clone and characterize the urea active transporter DUR3-like from its ctenidium (gill). The results indicate that T. squamosa absorbs exogenous urea, and the rate of urea uptake in the light was significantly higher than that in darkness. The DUR3-like coding sequence obtained from its ctenidium comprised 2346 bp, encoding a protein of 782 amino acids and 87.0 kDa. DUR3-like was expressed strongly in the ctenidium, outer mantle and kidney. Twelve hours of exposure to light had no significant effect on the transcript level of ctenidial DUR3-like However, between 3 and 12 h of light exposure, DUR3-like protein abundance increased progressively in the ctenidium, and became significantly greater than that in the control at 12 h. DUR3-like had an apical localization in the epithelia of the ctenidial filaments and tertiary water channels. Taken together, these results indicate that DUR3-like might participate in light-enhanced urea absorption in the ctenidium of T. squamosa When made available to the symbiotic zooxanthellae that are known to possess urease, the absorbed urea can be metabolized to NH 3 and CO 2 to support amino acid synthesis and photosynthesis, respectively, during insolation. © 2018. Published by The Company of Biologists Ltd.

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

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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.

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria.

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Ivanina, Anna V; Beniash, Elia; Etzkorn, Markus; Meyers, Tiffany B; Ringwood, Amy H; Sokolova, Inna M

2013-09-15

Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) 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 [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in

Capillary crystallization and molecular-replacement solution of haemoglobin II from the clam Lucina pectinata

International Nuclear Information System (INIS)

Gavira, José A.; Jesus, Walleska de; Camara-Artigas, Ana; López-Garriga, Juan; García-Ruiz, Juan M.

2006-01-01

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 P4 2 2 1 2, 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 (V M ) of 3.15 Å 3 Da −1 and a solvent content of 61% by volume

Characterization and function of carbonic anhydrases in the zooxanthellae-giant clam symbiosis.

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Baillie, B K; Yellowlees, D

1998-03-22

Carbonic anhydrase (CA) has been purified from the host tissue of Tridacna gigas, a clam that lives in symbiosis with the dinoflagellate alga, Symbiodinium. At least two isoforms of CA were identified in both gill and mantle tissue. The larger (70 kDa) isoform is a glycoprotein with both N- and O-glycans attached and has highest homology to CAII. It is associated with the membrane fraction while the smaller (32 kDa) is present in the aqueous phase in both tissues. The 32 kDa CA has high homology with mammalian CAI at the N-terminus. Both isoforms cross-reacted with antibodies to CAII from chicken. Immunohistology demonstrated that the 70 kDa CA is present within the ciliated branchial filaments and cells lining the tertiary water channels in the gills of T. gigas. This is consistent with a role in the transport of inorganic carbon (Ci) to the haemolymph and therefore supply of Ci to the zooxanthellae. CA was also detected in mantle epithelial cells where it may also contribute to Ci supply to the zooxanthellae. The hyaline body and nerve tissue in the mantle express the 70 kDa CA where it may be involved in light sensing and nervous transmission.

Composition and Dynamics of the Nucleolinus, a Link between the Nucleolus and Cell Division Apparatus in Surf Clam (Spisula) Oocytes*

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Alliegro, Mark C.; Hartson, Steven; Alliegro, Mary Anne

2012-01-01

The nucleolinus is a little-known cellular structure, discovered over 150 years ago (Agassiz, L. (1857) Contributions to the Natural History of the United States of America, First Monograph, Part IIL, Little, Brown and Co., Boston) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. A role for the nucleolinus in formation of the cell division apparatus has recently been confirmed in oocytes of the surf clam, Spisula solidissima (Alliegro, M. A., Henry, J. J., and Alliegro, M. C. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 13718–13723). However, we know so little about the composition and dynamics of this compartment, it is difficult to construct mechanistic hypotheses or even to be sure that prior reports were describing analogous structures in the cells of mammals, amphibians, plants, and other organisms where it was observed. Surf clam oocytes are an attractive model to approach this problem because the nucleolinus is easily visible by light microscopy, making it accessible by laser microsurgery as well as isolation by common cell fractionation techniques. In this report, we analyze the macromolecular composition of isolated Spisula nucleolini and examine the relationship of this structure to the nucleolus and cell division apparatus. Analysis of nucleolinar RNA and protein revealed a set of molecules that overlaps with but is nevertheless distinct from the nucleolus. The proteins identified were primarily ones involved in nucleic acid metabolism and cell cycle regulation. Monoclonal antibodies generated against isolated nucleolini revealed centrosomal forerunners in the oocyte cytoplasm. Finally, induction of damage to the nucleolinus by laser microsurgery altered the trafficking of α- and γ-tubulin after fertilization. These observations strongly support a role for the nucleolinus in cell division and represent our first clues regarding mechanism. PMID:22219192

Composition and dynamics of the nucleolinus, a link between the nucleolus and cell division apparatus in surf clam (Spisula) oocytes.

Science.gov (United States)

Alliegro, Mark C; Hartson, Steven; Alliegro, Mary Anne

2012-02-24

The nucleolinus is a little-known cellular structure, discovered over 150 years ago (Agassiz, L. (1857) Contributions to the Natural History of the United States of America, First Monograph, Part IIL, Little, Brown and Co., Boston) and thought by some investigators in the late 19th to mid-20th century to function in the formation of the centrosomes or spindle. A role for the nucleolinus in formation of the cell division apparatus has recently been confirmed in oocytes of the surf clam, Spisula solidissima (Alliegro, M. A., Henry, J. J., and Alliegro, M. C. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 13718-13723). However, we know so little about the composition and dynamics of this compartment, it is difficult to construct mechanistic hypotheses or even to be sure that prior reports were describing analogous structures in the cells of mammals, amphibians, plants, and other organisms where it was observed. Surf clam oocytes are an attractive model to approach this problem because the nucleolinus is easily visible by light microscopy, making it accessible by laser microsurgery as well as isolation by common cell fractionation techniques. In this report, we analyze the macromolecular composition of isolated Spisula nucleolini and examine the relationship of this structure to the nucleolus and cell division apparatus. Analysis of nucleolinar RNA and protein revealed a set of molecules that overlaps with but is nevertheless distinct from the nucleolus. The proteins identified were primarily ones involved in nucleic acid metabolism and cell cycle regulation. Monoclonal antibodies generated against isolated nucleolini revealed centrosomal forerunners in the oocyte cytoplasm. Finally, induction of damage to the nucleolinus by laser microsurgery altered the trafficking of α- and γ-tubulin after fertilization. These observations strongly support a role for the nucleolinus in cell division and represent our first clues regarding mechanism.

Simulation and analysis of the residual stresses in functionally graded Al2O3 coatings on CLAM steel

International Nuclear Information System (INIS)

Yan Zilin; Huang Qunying; Song Yong; Guo Zhihui; Wu Yican

2008-01-01

Alumina coatings on CLAM steel substrate are proposed to serve as tritium, corrosion and electric insulation barriers in the design of Dual Functional Lithium Lead Test Blanket Module (DFLL-TBM) in China in the frame of ITER. In order to avoid the crack failure due to thermal expansion mismatch of the coating and the substrate, the functionally graded materials (FGM) concept was adopted. In this paper, the residual thermal stresses in the coatings were calculated with the commercial software ANSYS. It is recommended that the compositional factor, numbers of the gradient interlayers and the thickness of the FGM zone are p=0.8, N=8, H=0.6 mm, respectively, according to the simulation results. These results could be helpful and theoretical guidance to the preparation and optimization of the coatings in the future. (authors)

Development of the 'SEA-Clam' wave energy device for small scale use. Report for period 1st August 1983 - 31st March 1985

Energy Technology Data Exchange (ETDEWEB)

1985-03-01

The Report presented covers the work of the Sea Energy Associates Ltd./Coventry (Lanchester) Polytechnic Wave Energy Group on the development of the SEA Clam concept from a 290 metre long, 45 000 tonne displacement unit rated at 10 MW to a smaller unit, typically 500 to 1000 kW, for island or remote coastal communities. Productivity measurements, flexible bag development, and work on the Wells' turbine which has been concentrated on the outline design and costing of an engineered unit for this application are discussed.

Combined proteomic and metallomic analyses in Scrobicularia plana clams to assess environmental pollution of estuarine ecosystems.

Science.gov (United States)

González-Domínguez, Raúl; Santos, Hugo Miguel; Bebianno, Maria João; García-Barrera, Tamara; Gómez-Ariza, José Luis; Capelo, José Luis

2016-12-15

Estuaries are very important ecosystems with great ecological and economic value, but usually highly impacted by anthropogenic pressure. Thus, the assessment of pollution levels in these habitats is critical in order to evaluate their environmental quality. In this work, we combined complementary metallomic and proteomic approaches with the aim to monitor the effects of environmental pollution on Scrobicularia plana clams captured in three estuarine systems from the south coast of Portugal; Arade estuary, Ria Formosa and Guadiana estuary. Multi-elemental profiling of digestive glands was carried out to evaluate the differential pollution levels in the three study areas. Then, proteomic analysis by means of two-dimensional gel electrophoresis and mass spectrometry revealed twenty-one differential proteins, which could be associated with multiple toxicological mechanisms induced in environmentally stressed organisms. Accordingly, it could be concluded that the combination of different omic approaches presents a great potential in environmental research. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impacts of seawater saturation state (ΩA = 0.4-4.6) and temperature (10, 25 °C) on the dissolution kinetics of whole-shell biogenic carbonates

Science.gov (United States)

Ries, Justin B.; Ghazaleh, Maite N.; Connolly, Brian; Westfield, Isaac; Castillo, Karl D.

2016-11-01

Anthropogenic increase of atmospheric pCO2 since the Industrial Revolution has caused seawater pH to decrease and seawater temperatures to increase-trends that are expected to continue into the foreseeable future. Myriad experimental studies have investigated the impacts of ocean acidification and warming on marine calcifiers' ability to build protective shells and skeletons. No studies, however, have investigated the combined impacts of ocean acidification and warming on the whole-shell dissolution kinetics of biogenic carbonates. Here, we present the results of experiments designed to investigate the effects of seawater saturation state (ΩA = 0.4-4.6) and temperature (10, 25 °C) on gross rates of whole-shell dissolution for ten species of benthic marine calcifiers: the oyster Crassostrea virginica, the ivory barnacle Balanus eburneus, the blue mussel Mytilus edulis, the conch Strombus alatus, the tropical coral Siderastrea siderea, the temperate coral Oculina arbuscula, the hard clam Mercenaria mercenaria, the soft clam Mya arenaria, the branching bryozoan Schizoporella errata, and the coralline red alga Neogoniolithon sp. These experiments confirm that dissolution rates of whole-shell biogenic carbonates decrease with calcium carbonate (CaCO3) saturation state, increase with temperature, and vary predictably with respect to the relative solubility of the calcifiers' polymorph mineralogy [high-Mg calcite (mol% Mg > 4) ≥ aragonite > low-Mg calcite (mol% Mg carbonates. Furthermore, the severity of the temperature effects on gross dissolution rates also varied with respect to carbonate polymorph solubility, with warming (10-25 °C) exerting the greatest effect on biogenic high-Mg calcite, an intermediate effect on biogenic aragonite, and the least effect on biogenic low-Mg calcite. These results indicate that both ocean acidification and warming will lead to increased dissolution of biogenic carbonates in future oceans, with shells/skeletons composed of the more

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

[Carbon, nitrogen, and phosphorus budgets of bottom-cultured clam Ruditapes philippinarum].

Science.gov (United States)

Zhang, Sheng-li; Zhang, An-guo; Yuan, Xiu-tang; Liang, Bin; Liu, Shu-xi

2015-04-01

In order to elucidate the role of bottom-cultured clams in the coastal nutrient cycle, the seasonal filtration, ingestion and biodeposition rates were in situ measured and carbon (C), nitrogen (N) and phosphorus (P) budgets of Ruditapes philippinarum among four seasons were modeled. The results showed that the scope for growth of R. philippinarum in carbon (SFG(C)), nitrogen (SFG(N)), and phosphorus (SFG(P)) all varied significantly among seasons, with the highest values in spring. Meanwhile, SFG(C) was negative in summer, SFG(N) and SFG(P) were always positive throughout the year. The seasonal variations of SFG(C), SFG(N) and SFG(P) were -3.94-49.82 mg C x ind(-1) x d(-1), 0.72-9.49 mg N x ind(-1) x d(-1), and 0.15-3.06 mg P x ind(-1) x d(-1), respectively. The net growth efficiencies in carbon (K(C2)), nitrogen (K(N2)), and phosphorus (K(P2)) also showed a distinct seasonal pattern among seasons, and ranked as K(P2) > K(N2) > K(C2). The C, N, and P budgets illustrated that the R. philippinarum population relatively used more N and P than C for growth and efficiently transferred the pelagic primary production to a higher trophic level. The current study suggested that R. philippinarum bottom-cultured at large scale might play a dominant role in the nutrient cycle of the coastal ecosystem and should be considered as an important ecological component in coastal areas.

Croissance prolongée de la diatomée marine Phaeodactylum tricornutum en milieu contaminé par le chlorure de tributylétain : conséquence sur le biotransfert du polluant

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MARSOT P.

1996-04-01

Full Text Available Cette étude consiste à évaluer le biotransfert du tributylétain (TBT par le filtreur bivalve Mya arenaria, à partir d'une culture semi-continue de la diatomée Phaeodactylum tricornutum exposée à un niveau de contamination n'arrêtant pas sa croissance à long terme. La dose du contaminant employée (100 ng I-1 est de l'ordre de grandeur de celles décelées dans certaines régions contaminées, telles les marinas et les régions portuaires. Dans ces conditions, la culture de P tricornutum a maintenu son équilibre de croissance durant plus de 50 jours. Sa productivité était légèrement inférieure (de 4 % à celle de la culture témoin (sans contaminant. L'ingestion des diatomées contaminées, sur une période de 90 jours, a entraîné une bioaccumulation de TBT et DBT (dibutylétain dans la chair du mollusque, atteignant des concentrations respectives de 133 et 128 ng g-1 (poids humide. L'étude suggère que le biotransfert du TBT et du DBT associés à des micro-algues en croissance continue ou semi-continue pourrait constituer un facteur de bioamplification important du biocide en milieu naturel.

Shifting baselines in the Ems Dollard estuary: A comparison across three decades reveals changing benthic communities

Science.gov (United States)

Compton, Tanya J.; Holthuijsen, Sander; Mulder, Maarten; van Arkel, Maarten; Schaars, Loran Kleine; Koolhaas, Anita; Dekinga, Anne; ten Horn, Job; Luttikhuizen, Pieternella C.; van der Meer, Jaap; Piersma, Theunis; van der Veer, Henk W.

2017-09-01

At a time when there is a growing discussion about the natural state of estuaries, a comparison of macrozoobenthos communities from two surveys conducted 30 years apart in the Ems Dollard estuary, in the eastern Wadden Sea, The Netherlands, provides a unique opportunity to compare changes over time. As expected, our comparison revealed a gradient in species composition from land (the Dollard) to sea (the Outer Ems) at both points in time, with brackish species in the Dollard and more marine species in the Outer Ems (Wadden Sea). Total richness increased over time; however, this mainly reflected the immigration of new species and sampling differences. In the Dollard, total biomass declined over time, most likely reflecting de-eutrophication in this area. Strikingly, at the meeting point between the sea and the brackish Dollard, i.e. the Inner Ems, the community composition changed from one dominated by bivalves (1970s) to one dominated by worms (since 2009). This change involved a reduction in total biomass, mainly of Mya arenaria, and immigration of polychaete worms (Marenzellaria viridis and Alitta succinea). In the Outer Ems, an increase in total biomass was observed, associated with the recent successful recruitment of Cerastoderma edule. This comparison highlights that historical data provides useful insights at large spatial scales. However, a full understanding of the complex dynamics of estuaries requires an analysis of continuous long-term monitoring series.

Morphometry, growth and reproduction of an Atlantic population of the razor clam Ensis macha (Molina, 1782

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Pedro J. Barón

2004-06-01

Full Text Available Ensis macha is a razor clam distributed throughout the coasts of southern Argentina and Chile. Even though it represents a valuable fishery resource, the exploitation of its Atlantic populations has begun only in recent years. This study provides the first estimates of growth rate, an interpretation of the reproductive cycle on the coast of the northern Argentine Patagonia and an analysis of the species morphometry. Growth was estimated by direct observation of growth rings on the valves by two observers. The reproductive cycle was interpreted by the analysis of temporal change of oocyte size frequency distributions. Parameter estimations for the von Bertalanffy equations respectively obtained by observers 1 and 2 were 154 and 153.7 mm for L?, 0.25 and 0.20 yr-1 for k, and -0.08 and -0.72 yr for t0. Two spawning peaks were detected: September-November 1999 and May-June 2000. However, mature females were found all year round. An abrupt change in the relationship between shell length and height was detected at 11.2 mm length.

Desinfestação de substratos com a utilização de coletor solar Utilization of solar collector for treatment of plant growth substrates

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Raquel Ghini

1992-01-01

Full Text Available Coletores solares planos constituídos de caixas de madeira com canaletas de chapa de alumínio, onde se coloca o substrato e se cobre com plástico transparente, foram testados quanto ao controle de Sclerotium rolfsii, Rhizoctonia solani, Verticillium sp., Meloidogyne arenaria e Cyperus rotundus (tiririca. Dependendo da intensidade de radiação solar, é necessário um dia para desinfestação do substrato com S. rolfsii e dois dias para R. solani, Verticillium sp. e M. arenaria.Flat solar collectors were tested for the control of Sclerotium rolfsii, Rhizoctonia solani, VerticiUium sp., Meloidogyne arenaria and Cyperus rotundus (nut sedge. The equipment developed comprises, basically, gutters of aluminum with termic liner of glass wool and transparent plastic cover. The results showed that, depending upon the solar radiation, one day is required for the disinfestations of substrate infested with S. rolfsii and nut sedge, and two days for R. solani, Verticillium sp. and M. arenaria.

Induction of Symbiosis in Tridacna crocea (C. Bivalvia, F. Tridacnidae Using Zooxanthellae from T. gigas and from T. crocea: Effects on Clam Survival and Growth

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S. Suzanne Mingoa-Licuanan

2000-12-01

Full Text Available Survival and growth of post-metamorphic Tridacna crocea juveniles were improved by inducing symbiosis with fresh or cloned zooxanthellae (Tg10 derived from T. gigas. Although clam growth was best with Tc4, survival was also poorest. Symbiosis with specific zooxanthellae was established at the pediveliger stage, with reinfection a few days after. It is suggested that while survival and growth may be easily monitored and may be used as indicators of good performance of a functional holobiont, other phenotypic traits such as resistance to disease, bleaching, etc. may also be considered in evaluating the effectivity of the selected zooxanthellae.

Can the hemoglobin characteristics of vesicomyid clam species influence their distribution in deep-sea sulfide-rich sediments? A case study in the Angola Basin

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Decker, C.; Zorn, N.; Le Bruchec, J.; Caprais, J. C.; Potier, N.; Leize-Wagner, E.; Lallier, F. H.; Olu, K.; Andersen, A. C.

2017-08-01

Vesicomyids live in endosymbiosis with sulfur-oxidizing bacteria and therefore need hydrogen sulfide to survive. They can nevertheless live in a wide range of sulfide and oxygen levels and depths, which may explain the exceptional diversity of this clam family in deep-sea habitats. In the Gulf of Guinea, nine species of vesicomyid clams are known to live in cold-seep areas with pockmarks from 600 to 3200 m deep, as well as in the organic-rich sediments of the Congo deep-sea fan at 5000 m deep. Our previous study showed that two species living in a giant pockmark have different oxygen carriers, suggesting different adaptations to hypoxia. Here, we studied the hemoglobin structure and oxygen affinity in three other species, Calyptogena valdiviae, Elenaconcha guiness and Abyssogena southwardae to determine whether the characteristics of their oxygen carriers contribute to their distribution in sulfide-rich sediments at a regional scale. Documenting pairwise species associations in various proportions, we give a semi-quantitative account of their local distribution and oxygen and sulfide measurements at seven sites. Mass spectrometry showed that each vesicomyid species has four intracellular monomeric hemoglobin molecules of 15-16 kDa, all differing in their molecular mass. As expected, the monomers showed no cooperativity in oxygen binding. Their oxygen affinities were very high (below 1 Torr), but differed significantly. C. valdiviae had the highest affinity and was dominant in the Harp pockmark, the site with the lowest oxygen content (half the value of fully oxygenated water). A. southwardae dominated in the Congo Lobe area, the site with the deepest sulfides. We discuss how hemoglobin may favor an active, vertical distribution of vesicomyids in sulfide-rich sediments.

Preliminary study of HDA coating on CLAM steel followed by high temperature oxidation

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiaoqiang, E-mail: newboy.chen@163.com; Huang, Qunying; Yan, Zilin; Song, Yong; Liu, Shaojun; Jiang, Zhizhong

2013-11-15

A hot-dip aluminizing process is expected to produce aluminide coatings on structural materials to resist tritium permeation, corrosion, and magnetohydrodynamic (MHD) effects in the fusion reactor blanket. China Low Activation Martensitic (CLAM) steel, which is the candidate structural material for the LiPb blanket system in China, was coated with pure aluminum and with an Al–Si alloy. Factors affecting the thickness and morphology of the aluminide coatings were studied. After the hot-dipping treatment, FeAl{sub 3} and Fe{sub 2}Al{sub 5} were observed at the Al/steel interface. The existence of silicon in the molten aluminum suppressed the growth of Fe{sub 2}Al{sub 5}, built up the thickness of FeAl{sub 3} slightly, and contributed to reducing the thickness of the intermetallic layer. The brittle phase of Fe{sub 2}Al{sub 5} had completely transformed to ductile phases of FeAl{sub 2}, FeAl and α-Fe(Al) after high temperature heat-treatment in air. Kirkendall voids were found in the diffusion layer, due to the rapid interdiffusion of iron and aluminum during oxidation. Cracks and pores were observed on the coating surface and at the interlayer. Grazing incidence X-ray diffraction indicates the presence of α-Al{sub 2}O{sub 3} in the oxide layer.

Heavy metal determinations in algae and clams and their possible employment for assessing the sea water quality criteria.

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Locatelli, C; Fabbri, D; Torsi, G

2001-01-01

An empirical criterion for a possible classification of sea water quality is proposed. It is based on the knowledge of metal content in algae (Ulva Rigida) and clams (Tapes Philippinarum), two species present in marine ecosystems. The elements considered are Hg, Cu, Pb, Cd, Zn. The analytical technique employed is Differential Pulse Anodic Stripping Voltammetry (DPASV) in the case of Cu, Pb, Cd, Zn, while the determination of mercury is obtained by the Cold Vapour Atomic Absorption Spectroscopy (CV-AAS) technique with SnCl2 as reducing agent. The analytical procedure has been verified on three standard reference materials: Sea Water BCR-CRM 403, Ulva Lactuca BCR-CRM 279 and Mussel Tissue BCR-CRM 278. For all the elements, in addition to detection limits, accuracy and precision are given: the former, expressed as relative error (e), and the latter, expressed as relative standard deviation (Sr), were in all cases lower than 6%.

A biomineralization study of the Indo-Pacific giant clam Tridacna gigas

Science.gov (United States)

Gannon, M. E.; Pérez-Huerta, A.; Aharon, P.; Street, S. C.

2017-06-01

The giant clam, Tridacna gigas, is an important faunal component of reef ecosystems of the Indo-Pacific region. In addition to its ecological role, shells of this bivalve species are useful bioarchives for past climate and environmental reconstructions. However, the biomineralization processes involved in shell aragonite deposition are insufficiently understood. Here, we present a study of the shell microstructure of modern specimens from Palm Island, Great Barrier Reef (GBR), Australia, and Huon Peninsula, Papua New Guinea (PNG), using a combination of petrography, scanning electron microscopy, electron backscatter diffraction, Raman spectroscopy and stable carbon isotope ratios. Daily growth increments were recognizable in all specimens through ontogeny, and counting these growth lines provides a robust specimen age estimate. For the internal layers, paired increments of organized aragonitic needles and compact, oblong crystals were recognized in a specimen from PNG, whereas specimens from GBR were composed of shield-like crystals that were not definable at the microscale. The combination of nutrient availability, rainfall and solar irradiance are likely to be the most significant factors controlling shell growth and may explain the observed differences in microstructure. The external layer, identical in all specimens, was composed of dendritic microstructure that is significantly enriched in 13C compared to the internal layer, suggesting different metabolic controls on layer deposition. We propose that the mineralization of the internal and external layers is independent from each other and associated with the activity of specific mantles. Future studies using T. gigas shells as bioarchives should consider the microstructure as it reflects the environment in which the individual lived and the differences in mineralization pathways of internal and external layers.

Regeneração e riqueza da formação arbustiva de Palmae em uma cronoseqüência pós-fogo na Restinga da Marambaia, Rio de Janeiro, RJ, Brasil The structure and diversity of three areas of shrubby restinga vegetation were analyzed 3, 12 and 84 months after fire in the Marambaia Restinga, Rio de Janeiro State, Brazil

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Luis Fernando Tavares de Menezes

2004-12-01

Full Text Available A estrutura e a riqueza da formação arbustiva de Palmae foram analisadas em três sítios numa cronoseqüência de regeneração (3, 12 e 84 meses após a última queimada na Restinga da Marambaia, registrando-se a presença de 29, 41 e 64 táxons, respectivamente. No sítio com maior tempo de regeneração, Allagoptera arenaria (Gomes Kuntze representou 79% da dominância relativa (DoR, seguida das nanofanerófitas Inga maritima Benth. e Manilkara subsericea (Mart. Dubard. Na área queimada há 12 meses, A. arenaria representou 88% da DoR, seguida de Inga maritima, Setaria setosa (Sw. P. Beauv. e Paspalum arenarium Schrad. No sítio com três meses de regeneração, a DoR de A. arenaria foi de 82%, acompanhada de Clitoria sp., Inga maritima e Portulaca mucronata Link. Nos três sítios estudados, a forma de vida mais importante foi geófita rizomatosa, devido à dominância de A. arenaria. Caméfita herbácea escaposa foi a forma de vida que apresentou maior número de espécies nos sítios com três e 12 meses de regeneração e no sítio queimado há 84 meses, as nanofanerófitas acompanharam as caméfitas herbáceas escaposas em número de espécies. Das 29 espécies registradas no sítio com três meses de regeneração, só Portulaca mucronata e Sebastiania corniculata (Vahl Müll. Arg. originaramse a partir de sementes, sendo que as demais rebrotaram ou se regeneraram. Sete dias após a queimada A. arenaria apresentou, em média, 8cm de sua parte vegetativa regenerada e com 180 dias apresentou as primeiras inflorescências.A total of 29, 41 and 64 taxa, respectively, were found. In the area sampled 84 months after fire, relative dominance of Allagoptera arenaria (Gomes Kuntze was 79%, followed by the nanophanerophytes Inga maritima Benth. and Manilkara subsericea (Mart. Dubard. In the area sampled 12 months after fire, relative dominance of A. arenaria was 88%, followed by Inga maritima, Setaria setosa (Sw. P. Beauv and Paspalum

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.

Sterilization of freeze dried manila clam (Ruditapea philippinarum) porridge for immuno-compromised patients

Energy Technology Data Exchange (ETDEWEB)

Song, Beom Seok; Park, Jae Nam [Team for Radiation Food Science and Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2017-02-15

This study was conducted to evaluate the combined effect of gamma irradiation and different conditions (vacuum packaging, antioxidant and freezing) on the microbiological and sensory characteristics of freeze dried Manila clam porridge (MCP) for immuno-compromised patient food. McP can be sterilized at 1 kGy to 10 kGy. the initial counts of total aerobic bacteria and yeast molds in the non-irradiated MCP were 2.4±0.5 and 1.2±0.3 log CFU g{sup -}'1, respectively, but gamma irradiation significantly decreased the total aerobic bacteria to below the detection limit (1 log CFU g{sup -1}) (5 kGy). Moreover, gamma irradiation effectively eliminated yeasts/molds at dose below than 1 kGy. However, gamma irradiation accelerated the increase of lipid oxidation and therefore, decreased the sensory characteristics of MCP as irradiation dose increased. to improve the sensory qualities of gamma irradiated MCP, combination treatment (vacuum packaging, 0.1% vitamin c) were applied. there was no significant difference in the overall acceptance scores between the combined-treatment sample (5.6 points) and the non-irradiated samples (6.0). the results indicate that combination treatment (vacuum packaging, 0.1% vitamin c) may help to maintain the quality of MCP. therefore, it considered that irradiation of MCP with combined treatment and this is an effective method for the consumption as a special purpose food such as for space travel or immuno-compromised patients.

Sterilization of freeze dried manila clam (Ruditapea philippinarum) porridge for immuno-compromised patients

International Nuclear Information System (INIS)

Song, Beom Seok; Park, Jae Nam

2017-01-01

This study was conducted to evaluate the combined effect of gamma irradiation and different conditions (vacuum packaging, antioxidant and freezing) on the microbiological and sensory characteristics of freeze dried Manila clam porridge (MCP) for immuno-compromised patient food. McP can be sterilized at 1 kGy to 10 kGy. the initial counts of total aerobic bacteria and yeast molds in the non-irradiated MCP were 2.4±0.5 and 1.2±0.3 log CFU g"-'1, respectively, but gamma irradiation significantly decreased the total aerobic bacteria to below the detection limit (1 log CFU g"-"1) (5 kGy). Moreover, gamma irradiation effectively eliminated yeasts/molds at dose below than 1 kGy. However, gamma irradiation accelerated the increase of lipid oxidation and therefore, decreased the sensory characteristics of MCP as irradiation dose increased. to improve the sensory qualities of gamma irradiated MCP, combination treatment (vacuum packaging, 0.1% vitamin c) were applied. there was no significant difference in the overall acceptance scores between the combined-treatment sample (5.6 points) and the non-irradiated samples (6.0). the results indicate that combination treatment (vacuum packaging, 0.1% vitamin c) may help to maintain the quality of MCP. therefore, it considered that irradiation of MCP with combined treatment and this is an effective method for the consumption as a special purpose food such as for space travel or immuno-compromised patients

Overfishing population characteristics of razor clam, Ensis macha, from Independencia Bay, Peru, in 2004 year

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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.

Is metal contamination responsible for increasing aneuploidy levels in the Manila clam Ruditapes philippinarum?

KAUST Repository

Piló, D.

2016-11-03

The present study assessed the metal genotoxicity potential at chromosome-level in the bivalve Ruditapes philippinarum collected along different areas of the Tagus estuary. Higher levels of aneuploidy on gill cells were detected at the most sediment contaminated area both in May (31.7%) and October (36.0%) when compared to a less contaminated area over the same periods (20.3% and 29.0% respectively). Interestingly, metal bioaccumulation in gills was higher in the specimens collected at the least contaminated area with the exception of Pb. Indeed, the multivariate analysis revealed a stronger relation between aneuploidy and sediment contamination than between aneuploidy and the bioaccumulation of the metals. The temporal and spatial inconsistency found for the bioaccumulation of metals in R. philippinarum and the positive correlation between sediment contamination and aneuploidy at the most contaminated area suggest that these chromosome-level effects might be due to chronic metal contamination occurring in the Tagus estuary, rather than a direct result of the temporal variation of bioavailable contaminants. The vertical transmission phenomenon of bivalve aneuploidy levels may then be perpetuating those levels on clams from the most contaminated area. The present results shed light about the effect of metal toxicity at the chromosome-level in species inhabiting chronic contaminated areas and highlight the use of aneuploidy as an effective tool to identify persistent contamination in worldwide transitional waters.

Ocean Acidification Affects the Cytoskeleton, Lysozymes, and Nitric Oxide of Hemocytes: A Possible Explanation for the Hampered Phagocytosis in Blood Clams, Tegillarca granosa.

Science.gov (United States)

Su, Wenhao; Rong, Jiahuan; Zha, Shanjie; Yan, Maocang; Fang, Jun; Liu, Guangxu

2018-01-01

An enormous amount of anthropogenic carbon dioxide (CO 2 ) has been dissolved into the ocean, leading to a lower pH and changes in the chemical properties of seawater, which has been termed ocean acidification (OA). The impacts of p CO 2 -driven acidification on immunity have been revealed recently in various marine organisms. However, the mechanism causing the reduction in phagocytosis still remains unclear. Therefore, the impacts of p CO 2 -driven OA at present and near-future levels (pH values of 8.1, 7.8, and 7.4) on the rate of phagocytosis, the abundance of cytoskeleton components, the levels of nitric oxide (NO), and the concentration and activity of lysozymes (LZM) of hemocytes were investigated in a commercial bivalve species, the blood clam ( Tegillarca granosa ). In addition, the effects of OA on the expression of genes regulating actin skeleton and nitric oxide synthesis 2 ( NOS2 ) were also analyzed. The results obtained showed that the phagocytic rate, cytoskeleton component abundance, concentration and activity of LZM of hemocytes were all significantly reduced after a 2-week exposure to the future OA scenario of a pH of 7.4. On the contrary, a remarkable increase in the concentration of NO compared to that of the control was detected in clams exposed to OA. Furthermore, the expression of genes regulating the actin cytoskeleton and NOS were significantly up-regulated after OA exposure. Though the mechanism causing phagocytosis seemed to be complicated based on the results obtained in the present study and those reported previously, our results suggested that OA may reduce the phagocytosis of hemocytes by (1) decreasing the abundance of cytoskeleton components and therefore hampering the cytoskeleton-mediated process of engulfment, (2) reducing the concentration and activity of LZM and therefore constraining the degradation of the engulfed pathogen through an oxygen-independent pathway, and (3) inducing the production of NO, which may negatively

Pinnatoxin G is responsible for atypical toxicity in mussels (Mytilus galloprovincialis) and clams (Venerupis decussata) from Ingril, a French Mediterranean lagoon

Science.gov (United States)

Hess, Philipp; Abadie, Eric; Hervé, Fabienne; Berteaux, Tom; Séchet, Véronique; Aráoz, Romulo; Molgó, Jordi; Zakarian, Armen; Sibat, Manoëlla; Rundberget, Thomas; Miles, Christopher O.; Amzil, Zouher

2014-01-01

Following a review of official control data on shellfish in France, Ingril Lagoon had been identified as a site where positive mouse bioassays for lipophilic toxins had been repeatedly observed. These unexplained mouse bioassays, also called atypical toxicity, coincided with an absence of regulated toxins and rapid death times in mice observed in the assay. The present study describes pinnatoxin G as the main compound responsible for the toxicity observed using the mouse bioassay for lipophilic toxins. Using a well-characterised standard for pinnatoxin G, LC-MS/MS analysis of mussel samples collected from 2009 to 2012 revealed regular occurrences of pinnatoxin G at levels sufficient to account for the toxicity in the mouse bioassays. Baseline levels of pinnatoxin G from May to October usually exceeded 40 µg kg−1 in whole flesh, with a maximum in September 2010 of around 1200 µg kg−1. These concentrations were much greater than those at the other 10 sites selected for vigilance testing, where concentrations did not exceed 10 µg kg−1 in a 3-month survey from April to July 2010, and where rapid mouse deaths were not typically observed. Mussels were always more contaminated than clams, confirming that mussel is a good sentinel species for pinnatoxins. Profiles in mussels and clams were similar, with the concentration of pinnatoxin A less than 2% that of pinnatoxin G, and pteriatoxins were only present in non-quantifiable traces. Esters of pinnatoxin G could not be detected by analysis of extracts before and after alkaline hydrolysis. Analysis with a receptor-binding assay showed that natural pinnatoxin G was similarly active on the nicotinic acetylcholine receptor as chemically synthesized pinnatoxin G. Culture of Vulcanodinium rugosum, previously isolated from Ingril lagoon, confirmed that this alga is a pinnatoxin G producer (4.7 pg cell−1). Absence of this organism from the water column during prolonged periods of shellfish contamination and the dominance

Molecular characteristics of hemoglobins in blood clam and their immune responses to bacterial infection.

Science.gov (United States)

Xu, Bin; Zhang, Yanan; Jing, Zhao; Fan, Tingjun

2017-06-01

Bivalve hemoglobins have antibacterial activities, while the underlying mechanisms remain poorly understood. In our study, three full-length cDNAs of hemoglobins from blood clam skHbs were obtained, encoding putative polypeptides of 147, 150, and 152 amino acids, respectively. Predicted advanced protein structures showed that the skHbs had amphipathic antibacterial structures, displayed the typical structural characteristics of proteins with globin-like fold containing numerous alpha-helixes, and forming a homodimeric skHbI and a heterotetrameric skHbII complex. After injected with alive and heat-killed Gram-positive bacteria Bacillus subtilis, the mRNA levels of skHbI and skHbII were both significantly upregulated through increasing the expression of peptidoglycan recognition protein-like (PGRP-like) protein and Toll-like receptor (TLR-like) protein induced by peptidoglycan on the surface of the bacteria, but there were no obvious differences in their protein levels. Besides, reactive oxygen species (ROS) was detected to participate in the resistance to B. subtilis. These implied that skHbs could involve in the innate immune responses to Gram-positive bacterial infection directly with their amphipathic structures and indirectly by increasing ROS production through PGRP triggering Toll pathway. In conclusion, our findings reveal the structural characteristics of skHbs and their mechanism against Gram-positive bacteria thereby providing the molecular evidence for fundamental innate antibacterial activities by invoking respiratory proteins. Copyright © 2017 Elsevier B.V. All rights reserved.

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.

Surfing the vegetal pole in a small population: extracellular vertical transmission of an 'intracellular' deep-sea clam symbiont.

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Ikuta, Tetsuro; Igawa, Kanae; Tame, Akihiro; Kuroiwa, Tsuneyoshi; Kuroiwa, Haruko; Aoki, Yui; Takaki, Yoshihiro; Nagai, Yukiko; Ozawa, Genki; Yamamoto, Masahiro; Deguchi, Ryusaku; Fujikura, Katsunori; Maruyama, Tadashi; Yoshida, Takao

2016-05-01

Symbiont transmission is a key event for understanding the processes underlying symbiotic associations and their evolution. However, our understanding of the mechanisms of symbiont transmission remains still fragmentary. The deep-sea clam Calyptogena okutanii harbours obligate sulfur-oxidizing intracellular symbiotic bacteria in the gill epithelial cells. In this study, we determined the localization of their symbiont associating with the spawned eggs, and the population size of the symbiont transmitted via the eggs. We show that the symbionts are located on the outer surface of the egg plasma membrane at the vegetal pole, and that each egg carries approximately 400 symbiont cells, each of which contains close to 10 genomic copies. The very small population size of the symbiont transmitted via the eggs might narrow the bottleneck and increase genetic drift, while polyploidy and its transient extracellular lifestyle might slow the rate of genome reduction. Additionally, the extracellular localization of the symbiont on the egg surface may increase the chance of symbiont exchange. This new type of extracellular transovarial transmission provides insights into complex interactions between the host and symbiont, development of both host and symbiont, as well as the population dynamics underlying genetic drift and genome evolution in microorganisms.

Seasonal variation of the essential oil from two Brazilian native Aldama La Llave (Asteraceae) species.

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Oliveira, Tuane S DE; Bombo, Aline B; Oliveira, Adriana S S DE; Garcia, Vera L; Appezzato-DA-Glória, Beatriz

2016-01-01

Aldama arenaria and A. robusta are morphologically similar aromatic species that have seasonal development. The yield and chemical composition of essential oils from aerial and underground vegetative organs of these species were compared to verify the production of volatile metabolites in flowering and dormant phases of development and to identify if there are unique compounds for either species. The major compound in the essential oils from A. arenaria leaves was palustrol (16.22%) and for aerial stems was limonene (15.3%), whereas limonene (11.16%) and α-pinene (19.64%) were the major compounds for leaves and aerial stems from A. robusta, respectively. The major compound for the underground organs was α-pinene, in both species and phenological stages. High amounts of diterpenes were found especially for A. arenaria essential oils. Each analyzed species presented unique compounds, which can provide a characteristic chemical profile for both species helping to solve their taxonomic problems. This study characterized for the first time the yield and essential oil composition of A. arenaria and A. robusta, which have medicinal potential, and some of the compounds in their essential oils are unique to each one and may be useful in helping the correct identification of them.

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

OpenAIRE

Hanana, H.; Simon, G.; Kervarec, N.; Cérantola, S.

2014-01-01

Tributyltin (TBT) is a highly toxic pollutant present in many aquatic ecosystems. Its toxicity in mollusks strongly affects their performance and survival. The main purpose of this study was to elucidate the mechanisms of TBT toxicity in clam Ruditapes decussatus by evaluating the metabolic responses of heart tissues, using high-resolution magic angle-spinning nuclear magnetic resonance (HRMAS NMR), after exposure to TBT (10−9, 10−6 and 10−4 M) during 24 h and 72 h. Results show that response...

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

A preliminary molecular phylogeny of the Namib Desert darkling ...

African Journals Online (AJOL)

Speciation events in Namibian darkling beetles likely occurred during periods of aridification about 35 Mya, 16 Mya and 5–10 Mya. Those periods could be related to geological events and climate change due to the glaciation of Antarctica and the development of the Benguela current. African Zoology 45(1): 107–114 (April ...

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)

Verrengia Guerrero, N.R.; Taylor, M.G.; Simkiss, K.

2007-01-01

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

The trophic plasticity of genus phelipanche pomel (orobanchaceae in bulgaria Trofichna plastichnost na rod phelipanche pomel (orobanchaceae v bulgaria

Directory of Open Access Journals (Sweden)

Kiril STOYANOV

2013-03-01

Full Text Available New data about the natural parasitism of Phelipanche ramosa (L Pomel, P. mutelii (Shultz Pomel, P. oxyloba, P. arenaria and P. purpurea in Bulgaria are collected. The information for the hosts describes 46 new trophic systems with species from the families: Brassicaceae, Solanaceae, Fabaceae, Asteraceae, Apiaceae, Poaceae, Lamiaceae, Scrophulariaceae, Chenopodiaceae, Caryophyllaceae, Araliaceae, Euphorbiaceae, Geraniaceae, Dioscoreaceae and Verbenaceae. The samples are collected outside the crop fields, far from the known host crops, from different parts of the country. Some of the registered hosts are new for Bulgaria. The voucher specimens with physical connection to the hosts are deposited in the Herbarium of The Agricultural University - Plovdiv (SOA. The collected data suggest that genus Phelipanche is represented by two trophic groups according to the known sections. Sect. Phelipanche unites the polyphags P. ramosa, P. oxyloba and P. mutelii. Sect. Arenariae consist oligophags - P. arenaria and P. purpurea.

Evolutionary time-scale of the begomoviruses: evidence from integrated sequences in the Nicotiana genome.

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Pierre Lefeuvre

Full Text Available Despite having single stranded DNA genomes that are replicated by host DNA polymerases, viruses in the family Geminiviridae are apparently evolving as rapidly as some RNA viruses. The observed substitution rates of geminiviruses in the genera Begomovirus and Mastrevirus are so high that the entire family could conceivably have originated less than a million years ago (MYA. However, the existence of geminivirus related DNA (GRD integrated within the genomes of various Nicotiana species suggests that the geminiviruses probably originated >10 MYA. Some have even suggested that a distinct New-World (NW lineage of begomoviruses may have arisen following the separation by continental drift of African and American proto-begomoviruses ∼110 MYA. We evaluate these various geminivirus origin hypotheses using Bayesian coalescent-based approaches to date firstly the Nicotiana GRD integration events, and then the divergence of the NW and Old-World (OW begomoviruses. Besides rejecting the possibility of a<2 MYA OW-NW begomovirus split, we could also discount that it may have occurred concomitantly with the breakup of Gondwanaland 110 MYA. Although we could only confidently narrow the date of the split down to between 2 and 80 MYA, the most plausible (and best supported date for the split is between 20 and 30 MYA--a time when global cooling ended the dispersal of temperate species between Asia and North America via the Beringian land bridge.

In vitro exposure of haemocytes of the clam Ruditapes philippinarum to titanium dioxide (TiO2) nanoparticles: nanoparticle characterisation, effects on phagocytic activity and internalisation of nanoparticles into haemocytes.

Science.gov (United States)

Marisa, Ilaria; Marin, Maria Gabriella; Caicci, Federico; Franceschinis, Erica; Martucci, Alessandro; Matozzo, Valerio

2015-02-01

The continuous growth of nanotechnology and nano-industries, the considerable increase of products containing nanoparticles (NPs) and the potential release of NPs in aquatic environments suggest a need to study NP effects on aquatic organisms. In this context, in vitro assays are commonly used for evaluating or predicting the negative effects of chemicals and for understanding their mechanisms of action. In this study, a physico-chemical characterisation of titanium dioxide NPs (n-TiO2) was performed, and an in vitro approach was used to investigate the effects of n-TiO2 on haemocytes of the clam Ruditapes philippinarum. In particular, the effects on haemocyte phagocytic activity were evaluated in two different experiments (with and without pre-treatment of haemocytes) by exposing cells to P25 n-TiO2 (0, 1 and 10 μg/mL). In addition, the capability of n-TiO2 to interact with clam haemocytes was evaluated with a transmission electron microscope (TEM). In this study, n-TiO2 particles showed a mean diameter of approximately 21 nm, and both anatase (70%) and rutile (30%) phases were revealed. In both experiments, n-TiO2 significantly decreased the phagocytic index compared with the control, suggesting that NPs are able to interfere with cell functions. The results of the TEM analysis support this hypothesis. Indeed, we observed that TiO2 NPs interact with cell membranes and enter haemocyte cytoplasm and vacuoles after 60 min of exposure. To the best of our knowledge, this is the first study demonstrating the internalisation of TiO2 NPs into R. philippinarum haemocytes. The present study can contribute to the understanding of the mechanisms of action of TiO2 NPs in bivalve molluscs, at least at the haemocyte level. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamics and chemistry of vortex remnants in late Arctic spring 1997 and 2000: Simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS

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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

Remarkable invasion of San Francisco Bay (California, USA), by the Asian clam Potamocorbula amurensis. I. Introduction and dispersal

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Carlton, James T.; Thompson, Janet K.; Schemel, Laurence E.; Nichols, Frederic H.

1990-01-01

The euryhaline bivalve mollusc Potamocorbula amurensis (family Corbulidae), a native of China, Japan, and Korea, has recently appeared and become very abundant in San Francisco Bay. This clam appears to have been introduced as veliger larvae in the seawater ballast of cargo vessels. It was first collected in northern San Francisco Bay in late 1986. P, amurensis then spread throughout the estuary within 2 yr and reached densities at some sites exceeding 10 000 m-2 It lives primarily in the subtidal on all substrates (mud, sand, peat, and clay) and is found in the full range of bay salinities (estuary ecosystem. These could include changes in (1) trophic dynamics (through competition with other suspension-feeding and deposit-feeding infauna; changes in benthic community energy flow; availability of a new and abundant prey item for birds, fish, and crabs; and reduction - as a result of its filter feeding - of phytoplankton standmg stock) and (2) benthic dynamics (through inhibition and/or enhancement of infauna due to substrate destabilization; alteration of suspended sediment load of near-bottom water; and change of sediment surface redox balance). The early detection of the appearance and spread of P. amurensis in San Francisco Bay makes this one of the best documented invasions of any estuary in the world.

Geochemical influences on assimilation of sediment-bound metals in clams and mussels

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Griscom, S.B.; Fisher, N.S.; Luoma, S.N.

2000-01-01

A series of experiments was performed to evaluate the extent to which Cd, Co, Ag, Se, Cr, and Zn bound to sediments with different geochemical properties could be assimilated by the mussel Mytilus edulis and the clam Macoma balthica. Oxidized and reduced radiolabeled sediments were fed to suspension-feeding animals, the depuration patterns of the individuals were followed by ??-spectrometry, and the assimilation efficiencies (AEs) of ingested metals were determined. AEs from geochemically diverse sediments typically varied less than 2-fold and ranged from 1% for Cr to 42% for Zn. Metals were assimilated from anoxic sediment by both animals; Ag, Cd, and Co AEs in M. balthica were 9-16%, 2-fold lower than from oxic sediment, but in M. edulis AEs were about two times greater from anoxic sediment for all metals but Ag. For oxic sediment, Cd and Co AEs in M. edulis decreased 3-4-fold with increased sediment exposure time to the metals with smaller but significant effects also noted for Zn and Se but not Ag. A less pronounced decrease in AE for M. balthica was evident only after 6 months exposure time. Sequential extractions of the oxidized sediments showed a transfer of metals into more resistant sediment components over time, but the rate did not correlate with a decrease in metal AEs. Comparing the two bivalves, TOC concentrations had an inconsistent effect on metal AEs. AEs of metals from bacteria-coated glass beads were slightly higher than from humic acid-coated beads, which were comparable with whole-sediment AEs. There was correspondence of AE with desorption of Ag, Cd, Co, and Se (but not Zn) from sediments into pH 5 seawater, measured to simulate the gut pH of these bivalves. The results imply that metals associated with sulfides and anoxic sediments are bioavailable, that the bioavailability of metals from sediments decreases over exposure time, that organic carbon content generally has a small effect on AEs, and that AEs of sediment-bound metals differ among

Molecular characterization, light-dependent expression, and cellular localization of a host vacuolar-type H+-ATPase (VHA) subunit A in the giant clam, Tridacna squamosa, indicate the involvement of the host VHA in the uptake of inorganic carbon and its supply to the symbiotic zooxanthellae.

Science.gov (United States)

Ip, Yuen K; Hiong, Kum C; Lim, Leon J Y; Choo, Celine Y L; Boo, Mel V; Wong, Wai P; Neo, Mei L; Chew, Shit F

2018-06-15

The giant clam, Tridacna squamosa, represents a clam-zooxanthellae association. In light, the host clam and the symbiotic zooxanthellae conduct light-enhanced calcification and photosynthesis, respectively. We had cloned the cDNA coding sequence of a Vacuolar-type Proton ATPase (VHA) subunit A, ATP6V1A, from T. squamosa, whereby the VHA is an electrogenic transporter that actively 'pumps' H + out of the cell. The ATP6V1A of T. squamosa comprised 1866 bp, encoding a protein of 622 amino acids and 69.9 kDa, and had a host-origin. Its gene expression was strong in the ctenidium and the colorful outer mantle, but weak in the whitish inner mantle, corroborating a previous proposition that VHA might have a trivial role in light-enhanced calcification. Light exposure led to significant increases in the gene and protein expression levels of ATP6V1A/ATP6V1A in the ctenidium and the outer mantle. In the ctenidium, the ATP6V1A was localized in the apical epithelia of the filaments and tertiary water channels, indicating that the VHA could participate in the increased excretion of H + produced during light-enhanced calcification. Additionally, the excreted H + would augment HCO 3 - dehydration in the external medium and facilitate the uptake of CO 2 by the ctenidium during insolation. In the outer mantle, the ATP6V1A was detected in intracellular vesicles in a type of cells, presumably iridocytes, surrounding the zooxanthellal tubules, and in the apical epithelium of zooxanthellal tubules. Hence, the host VHA could participate in the transfer of inorganic carbon from the hemolymph to the luminal fluid of the tubules by increasing the supply of H + for the dehydration of HCO 3 - to CO 2 during insolation to benefit the photosynthesizing zooxanthellae. Copyright © 2018 Elsevier B.V. All rights reserved.

Carbonic anhydrase 2-like in the giant clam, Tridacna squamosa: characterization, localization, response to light, and possible role in the transport of inorganic carbon from the host to its symbionts.

Science.gov (United States)

Ip, Yuen K; Koh, Clarissa Z Y; Hiong, Kum C; Choo, Celine Y L; Boo, Mel V; Wong, Wai P; Neo, Mei L; Chew, Shit F

2017-12-01

The fluted giant clam, Tridacna squamosa , lives in symbiosis with zooxanthellae which reside extracellularly inside a tubular system. Zooxanthellae fix inorganic carbon (C i ) during insolation and donate photosynthate to the host. Carbonic anhydrases catalyze the interconversion of CO 2 and HCO3-, of which carbonic anhydrase 2 (CA2) is the most ubiquitous and involved in many biological processes. This study aimed to clone a CA2 homolog ( CA2-like ) from the fleshy and colorful outer mantle as well as the thin and whitish inner mantle of T. squamosa , to determine its cellular and subcellular localization, and to examine the effects of light exposure on its gene and protein expression levels. The cDNA coding sequence of CA2-like from T. squamosa comprised 789 bp, encoding 263 amino acids with an estimated molecular mass of 29.6 kDa. A phenogramic analysis of the deduced CA2-like sequence denoted an animal origin. CA2-like was not detectable in the shell-facing epithelium of the inner mantle adjacent to the extrapallial fluid. Hence, CA2-like is unlikely to participate directly in light-enhanced calcification. By contrast, the outer mantle, which contains the highest density of tertiary tubules and zooxanthellae, displayed high level of CA2-like expression, and CA2-like was localized to the tubule epithelial cells. More importantly, exposure to light induced significant increases in the protein abundance of CA2-like in the outer mantle. Hence, CA2-like could probably take part in the increased supply of inorganic carbon (C i ) from the host clam to the symbiotic zooxanthellae when the latter conduct photosynthesis to fix C i during light exposure. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Pengaruh Zooxanthellae Karaug Terhadap Kelangsungan Hidup Dan Pertumbuhan Kerang Raksasa Kima (Tridacna Squamosa)

OpenAIRE

Ambariyanto, Ambariyanto

2007-01-01

The influence of zooxanthellae isolated from corals on the growth and suwivorshipof giant clams. Giant clam known as marine bivalves (Tridacnidae) which live in coralreef. One important aspect of giant clam biology is the existence of zooxanthellae assymbiotic algae which have important role source of energy In hatchery operationalprocedure zooxanthellae were introduced into larvae. Zooxanthellae were isolated fromadult clams. Since clams are also known as endangered species, it is important ...

Tropical troposphere to stratosphere transport of carbon monoxide and long-lived trace species in the Chemical Lagrangian Model of the Stratosphere (CLaMS

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R. Pommrich

2014-12-01

Full Text Available Variations in the mixing ratio of trace gases of tropospheric origin entering the stratosphere in the tropics are of interest for assessing both troposphere to stratosphere transport fluxes in the tropics and the impact of these transport fluxes on the composition of the tropical lower stratosphere. Anomaly patterns of carbon monoxide (CO and long-lived tracers in the lower tropical stratosphere allow conclusions about the rate and the variability of tropical upwelling to be drawn. Here, we present a simplified chemistry scheme for the Chemical Lagrangian Model of the Stratosphere (CLaMS for the simulation, at comparatively low numerical cost, of CO, ozone, and long-lived trace substances (CH4, N2O, CCl3F (CFC-11, CCl2F2 (CFC-12, and CO2 in the lower tropical stratosphere. For the long-lived trace substances, the boundary conditions at the surface are prescribed based on ground-based measurements in the lowest model level. The boundary condition for CO in the lower troposphere (below about 4 km is deduced from MOPITT measurements. Due to the lack of a specific representation of mixing and convective uplift in the troposphere in this model version, enhanced CO values, in particular those resulting from convective outflow are underestimated. However, in the tropical tropopause layer and the lower tropical stratosphere, there is relatively good agreement of simulated CO with in situ measurements (with the exception of the TROCCINOX campaign, where CO in the simulation is biased low ≈10–15 ppbv. Further, the model results (and therefore also the ERA-Interim winds, on which the transport in the model is based are of sufficient quality to describe large scale anomaly patterns of CO in the lower stratosphere. In particular, the zonally averaged tropical CO anomaly patterns (the so called "tape recorder" patterns simulated by this model version of CLaMS are in good agreement with observations, although the simulations show a too rapid upwelling

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 .

Molecular Identification and Historic Demography of the Marine Tucuxi (Sotalia guianensis at the Amazon River’s Mouth by Means of Mitochondrial Control Region Gene Sequences and Implications for Conservation

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Joseph Mark Shostell

2013-09-01

Full Text Available In 2005, three fishermen, with artisan fishing vessels and drift gillnets, accidentally captured around 200 dolphins between Vigia and Salinópolis in the Amazon River estuary. The dolphins died and they then prepared their vaginas and penises in order to sell them in the Ver-ao-Peso market in the city of Belem within the Brazilian state of Pará. We randomly sampled a minimal quantity of tissue of these sexual organs from 78 of these 200 dolphins and we determined the following results after sequencing 689 base pairs (bp from the mitochondrial control region gene: (1 96.15% (75/78 of these dolphins belonged to the species Sotalia guianensis. The other species detected were Steno brenadensis, Stenella coeruleoalba and Tursiops truncatus; (2 The levels of gene diversity found in this sample of S. guianensis were high (33 haplotypes, haplotype diversity of 0.917 and nucleotide diversity of 0.0045 compared to gene diversities found in other Brazilian S. guianensis locations; (3 All the population genetics methods employed indicated a clear population expansion in this population. This population expansion could have begun 400,000 years ago; (4 The haplotype divergence within this population could have begun around 2.1 millions of years ago (MYA, with posterior splits around 2.0–1.8 MYA, 1.7–1.8 MYA, 1–1.5 MYA, 0.6–0.8 MYA, 0.4–0.2 MYA and 0.16–0.02 MYA, all during the Pleistocene.

Evaluation of the MODIS Aerosol Retrievals over Ocean and Land during CLAMS.

Science.gov (United States)

Levy, R. C.; Remer, L. A.; Martins, J. V.; Kaufman, Y. J.; Plana-Fattori, A.; Redemann, J.; Wenny, B.

2005-04-01

The Chesapeake Lighthouse Aircraft Measurements for Satellites (CLAMS) experiment took place from 10 July to 2 August 2001 in a combined ocean-land region that included the Chesapeake Lighthouse [Clouds and the Earth's Radiant Energy System (CERES) Ocean Validation Experiment (COVE)] and the Wallops Flight Facility (WFF), both along coastal Virginia. This experiment was designed mainly for validating instruments and algorithms aboard the Terra satellite platform, including the Moderate Resolution Imaging Spectroradiometer (MODIS). Over the ocean, MODIS retrieved aerosol optical depths (AODs) at seven wavelengths and an estimate of the aerosol size distribution. Over the land, MODIS retrieved AOD at three wavelengths plus qualitative estimates of the aerosol size. Temporally coincident measurements of aerosol properties were made with a variety of sun photometers from ground sites and airborne sites just above the surface. The set of sun photometers provided unprecedented spectral coverage from visible (VIS) to the solar near-infrared (NIR) and infrared (IR) wavelengths. In this study, AOD and aerosol size retrieved from MODIS is compared with similar measurements from the sun photometers. Over the nearby ocean, the MODIS AOD in the VIS and NIR correlated well with sun-photometer measurements, nearly fitting a one-to-one line on a scatterplot. As one moves from ocean to land, there is a pronounced discontinuity of the MODIS AOD, where MODIS compares poorly to the sun-photometer measurements. Especially in the blue wavelength, MODIS AOD is too high in clean aerosol conditions and too low under larger aerosol loadings. Using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) radiative code to perform atmospheric correction, the authors find inconsistency in the surface albedo assumptions used by the MODIS lookup tables. It is demonstrated how the high bias at low aerosol loadings can be corrected. By using updated urban/industrial aerosol

Fate of isotopically labeled zinc oxide nanoparticles in sediment and effects on two endobenthic species, the clam Scrobicularia plana and the ragworm Hediste diversicolor.

Science.gov (United States)

Buffet, Pierre-Emmanuel; Amiard-Triquet, Claude; Dybowska, Agnieszka; Risso-de Faverney, Christine; Guibbolini, Marielle; Valsami-Jones, Eugénia; Mouneyrac, Catherine

2012-10-01

Although it is reported that metal and metal oxide nanoparticles, which are among the most rapidly commercialized materials, can cause toxicity to organisms, their fate in the environment and toxicity to marine organisms are not well understood. In this study, we used a stable isotope labelling approach to trace the fate of nanoparticles (NPs) in sediments and also investigated bio-uptake in two estuarine intra-sedimentary invertebrates Scrobicularia plana and Nereis diversicolor. We selected exposure to 3 mg kg(-1) sediment ZnO NPs since this level is a realistic prediction of the environmental concentration in sediments. 67ZnO NPs (DLS: 21-34 nm, positively charged: 31.3 mV) suspensions were synthesised in diethylene glycol (DEG). We explored the fate of 67ZnO NPs in sediment, 67Zn bioaccumulation and the biochemical (biomarkers of defence and damage) and behavioural (burrowing kinetics and feeding rates) biomarkers in both species to 67ZnO NPs and DEG on its own during a 16 d laboratory exposure. After exposure, 67Zn concentrations in sediment showed higher levels in the upper section (1cm: 2.59 mg kg(-1)) decreasing progressively (2 cm: 1.63 mg kg(-1), 3 cm: 0.90 mg kg(-1), 4 cm: 0.67 mg kg(-1)) to a minimum value at the bottom (5 cm: 0.31 mg kg(-1)). 67Zn bioaccumulation was observed in both organisms exposed to 67ZnO NPs in DEG but no major inter-species differences were found. At the biochemical level, 67ZnO NPs exposure significantly induced increased glutathione-S-transferase activity in worms and catalase activity in clams whereas superoxide dismutase activity and thiobarbituric acid reactive substance levels were not affected in any species. Exposure to DEG on its own leads to a significant increase of metallothionein-like protein levels in clams compared with those exposed to 67ZnO NPs or controls. Burrowing behaviour as well as feeding rate were significantly impaired in both species exposed to 67ZnO NPs. Concerning exposure to DEG on its own

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.

How the food supply harvestable by waders in the Wadden Sea depends on the variation in energy density, body weight, biomass, burying depth and behaviour of tidal-flat invertebrates

Science.gov (United States)

Zwarts, Leo; Wanink, Jan H.

For several reasons, waders in the Wadden Sea face a large seasonal and annual variation in their food supply. Observations on a tidal flat in the Dutch Wadden Sea have shown that: - (1) The average energy density of ten invertebrate prey species varies between 21 and 23 kJ·g -1 AFDW. In Scrobicularia plana and Mya arenaria, but not in Macoma balthica, the energy density is 10% lower in winter than in summer. - (2) Depending on the species, body weights of prey of similar size are 30 to 60% lower in winter than in summer. - (3) The year-to-year fluctuation in standing-crop biomass is larger in some species than in others, the difference depending mainly on the frequency of successful recruitment. The overall biomass of the macrobenthos in winter is half of that in summer, but the timing of the peak biomass differs per species. - (4) The burying depth varies per species: Cerastoderma edule live just beneath the surface, while M. balthica, S. plana, M. arenaria, Arenicola marina and Nereis diversicolor bury more deeply and the majority of these prey live out of reach of the bird's bill. In all six species, burying depth increases with size. There is no seasonal variation in depth of C. edule and M. arenaria, but the four other species live at most shallow depth in early summer and most deeply in midwinter. Burying depths in winter vary from year to year, but are unrelated to temperature. Neither has temperature any effect on depth within months. For knot Calidris canutus feeding on M. balthica, the fluctuation in the accessible fraction was the main source of variation in the biomass of prey that is actually harvestable, i.e. the biomass of prey of suitable size that is accessible. Accordingly, the paper reviews the available data on the temporal variations in accessibility, detectability, ingestibility, digestibility and profitability of prey for waders. Only a small part of the prey is harvestable since many accessible prey are ignored because of their low

Degradation of bisphenol A and acute toxicity reduction by different thermo-tolerant ascomycete strains isolated from arid soils.

Science.gov (United States)

Mtibaà, Rim; Olicón-Hernández, Dario Rafael; Pozo, Clementina; Nasri, Moncef; Mechichi, Tahar; González, Jesus; Aranda, Elisabet

2018-07-30

Four different laccase-producing strains were isolated from arid soils and used for bisphenol A (BPA) degradation. These strains were identified as Chaetomium strumarium G5I, Thielavia arenaria CH9, Thielavia arenaria HJ22 and Thielavia arenaria SM1(III) by internal transcribed spacer 5.8 S rDNA analysis. Residual BPA was evaluated by HPLC analysis during 48 h of incubation. A complete removal of BPA was observed by the whole cell fungal cultures within different times, depending on each strain. C. strumarium G5I was the most efficient degrader, showing 100% of removal within 8 h of incubation. The degradation of BPA was accompanied by the production of laccase and dye decolorizing peroxidase (DyP) under degradation conditions. The presence of aminobenzotriazole (ABT) as an inhibitor of cytochrome P450s monooxygenases (CYP) demonstrated a slight decrease in BPA removal rate, suggesting the effective contribution of CYP in the conversion. The great involvement of laccase in BPA transformation together with cell-associated enzymes, such as CYP, was supported by the identification of hydroxylated metabolites by ultra-high performance liquid chromatography-mass spectroscopy (UHPLC-MS). The metabolic pathway of BPA transformation was proposed based on the detected metabolites. The acute toxicity of BPA and its products was investigated and showed a significant reduction, except for T. arenaria SM1(III) that did not caused reduction of toxicity (IC 50 strumarium G5I as an efficient degrader of BPA. Copyright © 2018 Elsevier Inc. All rights reserved.

A microarray-based analysis of gametogenesis in two Portuguese populations of the European clam Ruditapes decussatus.

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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.

Molecular Characterization of a Dual Domain Carbonic Anhydrase From the Ctenidium of the Giant Clam, Tridacna squamosa, and Its Expression Levels After Light Exposure, Cellular Localization, and Possible Role in the Uptake of Exogenous Inorganic Carbon

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Clarissa Z. Y. Koh

2018-03-01

Full Text Available A Dual-Domain Carbonic Anhydrase (DDCA had been sequenced and characterized from the ctenidia (gills of the giant clam, Tridacna squamosa, which lives in symbiosis with zooxanthellae. DDCA was expressed predominantly in the ctenidium. The complete cDNA coding sequence of DDCA from T. squamosa comprised 1,803 bp, encoding a protein of 601 amino acids and 66.7 kDa. The deduced DDCA sequence contained two distinct α-CA domains, each with a specific catalytic site. It had a high sequence similarity with tgCA from Tridacna gigas. In T. squamosa, the DDCA was localized apically in certain epithelial cells near the base of the ctenidial filament and the epithelial cells surrounding the tertiary water channels. Due to the presence of two transmembrane regions in the DDCA, one of the Zn2+-containing active sites could be located externally and the other one inside the cell. These results denote that the ctenidial DDCA was positioned to dehydrate HCO3- to CO2 in seawater, and to hydrate the CO2 that had permeated the apical membrane back to HCO3- in the cytoplasm. During insolation, the host clam needs to increase the uptake of inorganic carbon from the ambient seawater to benefit the symbiotic zooxanthellae; only then, can the symbionts conduct photosynthesis and share the photosynthates with the host. Indeed, the transcript and protein levels of DDCA/DDCA in the ctenidium of T. squamosa increased significantly after 6 and 12 h of exposure to light, respectively, denoting that DDCA could participate in the light-enhanced uptake and assimilation of exogenous inorganic carbon.

Cycad diversification and tropical biodiversity

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Rull, V.

2012-12-01

Full Text Available The recent unexpected discovery that living Cycadales are not Jurassic-Cretaceous (200– 65 Mya relicts, as all their extant genera began to diversify during the Late Miocene (12 Mya, has challenged a classical evolutionary myth. This brief note shows how this finding may also provide new clues on the shaping of the high tropical biodiversity

El reciente e inesperado descubrimiento de que las Cycadales actuales no son relictos Jurásico-Cretácicos (200-65 Mya, ya que todos sus géneros iniciaron su diversificación durante el Mioceno Tardío (12 Mya, ha puesto en entredicho un mito evolutivo clásico. En esta nota se expone como este hallazgo puede, además, proporcionar nuevas pistas sobre el origen de la elevada biodiversidad tropical.

Stable isotope and pen feeding trial studies confirm the value of horseshoe crab Limulus polyphemus eggs to spring migrant shorebirds in Delaware Bay

Science.gov (United States)

Haramis, G.M.; Link, W.A.; Osenton, P.C.; Carter, Daniel B.; Weber, R.G.; Clark, N.A.; Teece, M.A.; Mizrahi, D.S.

2007-01-01

We used stable isotope (SI) methods in combination with pen feeding trials to determine the importance of eggs of the Atlantic horseshoe crab Limulus polyphemus to migratory fattening of red knots Calidris canutus rufa and ruddy turnstones Arenaria interpres morinella during spring stopover in Delaware Bay. By manifesting measurable fractionation (ca +3?) and rapid turnover, blood plasma *15 nitrogen proved a functional marker for SI diet tracking during the short 3-week stopover. Blood samples from free-ranging knots (3 data sets) and turnstones (1 data set) produced similar convergence of plasma *15 N signatures with increasing body mass that indicated highly similar diets. Asymptotes deviated slightly (0.3? to 0.7?) from that of captive shorebirds fed a diet of only crab eggs during stopover, thus confirming a strong crab egg-shorebird linkage. The plasma *15N crab-egg diet asymptote was enriched ca +4.5? and therefore readily discriminated from that of either blue mussels Mytilus edulis or coquina clams Donax variabilis, the most likely alternative prey of knots in Delaware Bay. Crab eggs were highly palatable to captive knots and turnstones which achieved rates of mass gain (3?11 g/d) comparable to that of free-ranging birds. Peak consumption rates during hyperphagic events were 23,940 and 19,360 eggs/bird/d, respectively. The empirical conversions of eggs consumed to body mass gained (5,017 eggs/g for knots and 4,320 eggs/g for turnstones) indicate the large quantities of crab eggs required for the maintenance of these shorebird populations during stopover.

Bioconversion of D-psicose to D-tagatose and D-talitol by Mucoraceae fungi.

Science.gov (United States)

Yoshihara, Kazutoshi; Shinohara, Yoshihiro; Hirotsu, Takahiro; Izumori, Ken

2006-03-01

Rhizopus oryzae MYA-2483, which cannot utilize D-psicose as a sole source of carbon, converted D-psicose to two other compounds. These compounds were identified by NMR and IR as D-tagatose and D-talitol. In this study, we describe for the first time the bioconversion of D-psicose to D-tagatose. Various strains of Mucoraceae fungi, to which R. oryzae MYA-2483 belongs, exhibited conversion activity similar to that of R. oryzae MYA-2483. There is the possibility that a considerable number of fungi belonging to Mucoraceae possess such D-psicose conversion activity.

Highly restricted gene flow and deep evolutionary lineages in the giant clam Tridacna maxima

Science.gov (United States)

Nuryanto, A.; Kochzius, M.

2009-09-01

The tropical Indo-West Pacific is the biogeographic region with the highest diversity of marine shallow water species, with its centre in the Indo-Malay Archipelago. However, due to its high endemism, the Red Sea is also considered as an important centre of evolution. Currently, not much is known about exchange among the Red Sea, Indian Ocean and West Pacific, as well as connectivity within the Indo-Malay Archipelago, even though such information is important to illuminate ecological and evolutionary processes that shape marine biodiversity in these regions. In addition, the inference of connectivity among populations is important for conservation. This study aims to test the hypothesis that the Indo-Malay Archipelago and the Red Sea are important centres of evolution by studying the genetic population structure of the giant clam Tridacna maxima. This study is based on a 484-bp fragment of the cytochrome c oxidase I gene from 211 individuals collected at 14 localities in the Indo-West Pacific to infer lineage diversification and gene flow as a measure for connectivity. The analysis showed a significant genetic differentiation among sample sites in the Indo-West Pacific (Φst = 0.74, P < 0.001) and across the Indo-Malay Archipelago (Φst = 0.72, P < 0.001), indicating restricted gene flow. Hierarchical AMOVA revealed the highest fixation index (Φct = 0.8, P < 0.001) when sample sites were assigned to the following regions: (1) Red Sea, (2) Indian Ocean and Java Sea, (3) Indonesian throughflow and seas in the East of Sulawesi, and (4) Western Pacific. Geological history as well as oceanography are important factors that shape the genetic structure of T. maxima in the Indo-Malay Archipelago and Red Sea. The observed deep evolutionary lineages might include cryptic species and this result supports the notion that the Indo-Malay Archipelago and the Red Sea are important centres of evolution.

Recruitment of mud clam Polymesoda erosa (Solander, 1876 in a mangrove habitat of Chorao island, Goa

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Sandhya Clemente

2011-06-01

Full Text Available Habitat-specific settlement success results either from active habitat selection or differential mortality after non-selective settlement. The mud clam Polymesoda erosa (Solander, 1876 is an ecologically and economically important benthic invertebrate with high abundance in the mangrove forests of Chorao Island, Goa, India. A one-year study (Jul 2004-Jul 2005 was conducted to characterize the patterns of post-larval settlement and survival of P. erosa in the mangrove habitat. The mean density of settling post-larvae was 28 no.m-2 with a majority of settlers during Sept 04. The density of adult clams in the landward zone ranged from 7-12 no.m-2 (mean: 9 ± 6 sd; n=122. In the seaward region, adults were completely absent at the low tide level. Higher densities of juveniles observed at the low- and mid-tide levels were assumed to be due to frequent inundation which allowed the young individuals to feed adequately and attain the critical sizes at which vulnerability to physical and biological constraints is substantially reduced, whereas, at high-tide level, increased desiccation may account for the mortality of settlers. It is speculated that initially the settlers settle according to the hydrodynamic conditions for sedimentation; however, adult survival is affected by their recruitment in a suitable habitat (e.g. substrates near Avicennia sp.. Thus, habitat dependent viability during the post-settlement phase could be the best explanation for the non-random, patchy distribution of P. erosa observed in the Chorao mangrove swamp.Um assentamento larval bem sucedido resulta da seleção ativa do habitat pelas larvas ou da mortalidade diferencial destas após o assentamento não seletivo. Nos manguezais da ilha Chorao, Goa, India, a ostra do lodo Polymesoda erosa (Solander, 1876 é um invertebrado muito abundante e de importância econômica. O presente trabalho, realizado durante um ano (julho de 2004 a julho de 2005, visou caracterizar os padr

Host specificity of Pisidium coreanum (Bivalvia: Sphaeriidae) to larval infection with a human intestinal fluke Echinostoma cinetorchis (Trematoda: Echinostomatidae) in Korea.

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Park, Y K; Soh, C T; Park, G M; Hwang, M K; Chung, P R

2006-10-01

The fingernail clam, Pisidium coreanum, has been traditionally consumed raw as a so-called drug therapy by patients with bone fractures in Korea. The present study was designed to determine the possible occurrence and, if present, the prevalence of Echinostoma cinetorchis in P. coreanum collected at a local site, and to determine the susceptibility of the clams in the laboratory to infection with miracidia and cercariae of E. cinetorchis. No cercariae or metacercariae of E. cinetorchis were observed in field-collected P. coreanum clams. In susceptibility experiments with laboratory-reared clams, individuals exposed to miracidia of E. cinetorchis did not release cercariae by 20 days after exposure; necropsy of exposed clams failed to show development of any sporocysts or rediae. To confirm the possibility of these clams serving as an experimental second intermediate host of E. cinetorchis, 20 of them were exposed to E. cinetorchis cercariae from experimentally infected Segmentina hemisphaerula that had been previously exposed to miracidia of E. cinetorchis; all exposed clams became infected. Metacercariae from clams at 14 days postinfection were fed to rats, and adult worms were recovered from the ileocecal regions. This is the first report of P. coreanum serving as second intermediate host of E. cinetorchis.

Ocean acidification weakens the immune response of blood clam through hampering the NF-kappa β and toll-like receptor pathways.

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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. Copyright © 2016 Elsevier Ltd. All rights reserved.

A novel widespread cryptic species and phylogeographic patterns within several giant clam species (Cardiidae: Tridacna) from the Indo-Pacific Ocean.

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Huelsken, Thomas; Keyse, Jude; Liggins, Libby; Penny, Shane; Treml, Eric A; Riginos, Cynthia

2013-01-01

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.

Out of Africa:Miocene Dispersal, Vicariance, and Extinction within Hyacinthaceae Subfamily Urgineoideae

Institute of Scientific and Technical Information of China (English)

Syed Shujait Ali; Martin Pfosser; Wolfgang Wetschnig; Mario MartnezAzorn; Manuel B. Crespo; Yan Yu

2013-01-01

Disjunct distribution patterns in plant lineages are usually explained according to three hypotheses:vicariance, geodispersal, and long-distance dispersal. The role of these hypotheses is tested in Urgineoideae (Hyacinthaceae), a subfamily disjunctly distributed in Africa, Madagascar, India, and the Mediterranean region. The potential ancestral range, dispersal routes, and factors responsible for the current distribution in Urgineoideae are investigated using divergence time estimations. Urgineoideae originated in Southern Africa approximately 48.9 Mya. Two independent dispersal events in the Western Mediterranean region possibly occurred during Early Oligocene and Miocene (29.9-8.5 Mya) via Eastern and Northwestern Africa. A dispersal from Northwestern Africa to India could have occurred between 16.3 and 7.6 Mya. Vicariance and extinction events occurred approximately 21.6 Mya. Colonization of Madagascar occurred between 30.6 and 16.6 Mya, after a single transoceanic dispersal event from Southern Africa. The current disjunct distributions of Urgineoideae are not satisfactorily explained by Gondwana fragmentation or dispersal via boreotropical forests, due to the younger divergence time estimates. The flattened winged seeds of Urgineoideae could have played an important role in long-distance dispersal by strong winds and big storms, whereas geodispersal could have also occurred from Southern Africa to Asia and the Mediterranean region via the so-called arid and high-altitude corridors.

ジンザイ コ ジンコウ イケ ニ オケル ヤマト シジミ ノ

OpenAIRE

大谷, 修司; 辻井, 要介; 江原, 亮; 草田, 和美; 板倉, 俊一; 山口, 啓子; 品川, 明; 秦, 明徳; 中村, 幹雄

2004-01-01

We studied feeding, egestion and digestion of Corbicula japonica in the laboratory. Clams were collected from an artificial shallow pond(20-60 cm deep)near the brackish Lake Jinzai in 2001. Pond water was supplied continuously from Lake Jinzai using a pump. Feces and pseudo-feces of the clams were observed by microscope. Clam pseudo-feces were irregular, wooly, and brown in color when clam fed phytoplankton. These were mainly composed of living micro-algae, detritus, cf. amoebocytes and proto...

A first possible chameleon from the late Miocene of India (the hominoid site of Haritalyangar): a tentative evidence for an Asian dispersal of chameleons.

Science.gov (United States)

Sankhyan, Anek R; Čerňanský, Andrej

2016-12-01

Miocene rare fossils from India, tentatively attributed to chameleons, are described for the first time. The material consists of a fragment of the left squamosal and an element interpreted as a posterodorsal process of the parietal. The specimens come from a late Miocene site of the Nagri Formation (Middle Siwaliks, ~ 9 Mya) at Haritalyangar, North India. This material presents a possible evidence for a chameleon dispersal to Asia. Based on molecular data, the dispersion of an Asian chamaeleonid lineage from Africa to Arabia/Asia is dated at approximately 13 Mya and its diversification in situ at around 6-8 Mya. However, till now, no Miocene-age fossil record has been described to support crown chamaeleonid presence in this area. The material described herein is very fragmented. If correctly allocated, the Haritalyangar chameleons show the oldest known occurrence of this clade in India, at least approximately 9 Mya ago.

Preengorde intensivo de almeja japonesa Ruditapes philippinarum (Adamsampersand Reeve, 1850) en sustrato, en la zona intermareal

OpenAIRE

Royo, A.; Ruiz-Azcona, P.; Navajas, R.

2005-01-01

The aim of this study was to analyse the effect of high density for Manila clams at the first ongrowing stage under netting in ground plots, in order to establish an economical improvement for clam farming. The intensive clam cultivation was maintained to the competence size at high density (6 000 indiv/m²), when the effects of density on mortality and growth begin. A total of 97 000 units of Manila clams Ruditapes philippinarum (Adamsampersand Reeve, 1850), prefattened in a raft with air-l...

Tracing the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within baleen whale (Mysticeti) lineages: a mitogenomic perspective.

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Yu, Jihyun; Nam, Bo-Hye; Yoon, Joon; Kim, Eun Bae; Park, Jung Youn; Kim, Heebal; Yoon, Sook Hee

2017-12-01

To explore the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within the baleen whale (Mysticeti) lineages, we analyzed 148 published mitochondrial genome sequences of baleen whales. We used a Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. The results showed that the fin whales had a single maternal origin, and that there is a significant correlation between geographic location and evolution of global fin whales. The most recent common female ancestor of this species lived approximately 9.88 million years ago (Mya). Here, North Pacific fin whales first appeared about 7.48 Mya, followed by a subsequent divergence in Southern Hemisphere approximately 6.63 Mya and North Atlantic about 4.42 Mya. Relatively recently, approximately 1.76 and 1.42 Mya, there were two additional occurrences of North Pacific populations; one originated from the Southern Hemisphere and the other from an uncertain location. The evolutionary rate of this species was 1.002 × 10 -3 substitutions/site/My. Our Bayesian skyline plot illustrates that the fin whale population has the rapid expansion event since ~ 2.5 Mya, during the Quaternary glaciation stage. Additionally, this study indicates that the fin whale has a sister group relationship with humpback whale (Meganoptera novaeangliae) within the baleen whale lineages. Of the 16 genomic regions, NADH5 showed the most powerful signal for baleen whale phylogenetics. Interestingly, fin whales have 16 species-specific amino acid residues in eight mitochondrial genes: NADH2, COX2, COX3, ATPase6, ATPase8, NADH4, NADH5, and Cytb.

Biomonitoring and assessment of monomethylmercury exposure in aqueous systems using the DGT technique

International Nuclear Information System (INIS)

Clarisse, O.; Lotufo, G.R.; Hintelmann, H.; Best, E.P.H.

2012-01-01

A series of laboratory experiments was conducted under realistic environmental conditions to test the ability of the Diffusive Gradient in Thin film (DGT) technique to mimic monomethylmercury (MMHg) bioaccumulation by a clam (Macoma balthica, Baltic clam). Using isotope enriched MMHg as tracers, bioavailability was determined by comparing the rate of MMHg uptake by novel DGT devices and sentinel organism over time. Experiments were conducted under varying conditions of salinity and MMHg speciation. Depending on MMHg level and speciation in the dissolved phase, MMHg uptake rates by the sentinel organism varied greatly from 0.4 to 2.4 L g −1 d −1 . Reproducibilities of MMHg uptakes by DGT and clams were estimated at 7 and 38%, respectively. A significant linear relationship (log basis) between MMHg accumulation by DGT and clams was observed (r 2 = 0.89). The study demonstrates that DGT results reasonably predict MMHg uptake by clams from the aqueous phase and provide the basis for application of the DGT device as a surrogate for sentinel organism for monitoring bioavailable MMHg. - Highlights: ► We investigate the potential of DGT devices to act as surrogates for sentinel organism. ► We compare monomethylmercury accumulation in DGT devices and in clams from the dissolved phase. ► We examine the effects of salinity and MMHg speciation on MMHg accumulation by DGT and clams. ► For all laboratory experiments, a strong overall correlation between MMHg accumulations in clams and DGTs is observed.

Nematodos agalladores asociados al cultivo de papaya (Carica papaya L. en el departamento de Córdoba, Colombia

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Jaraba Juan de Dios

2007-06-01

Full Text Available

El objetivo de este trabajo fue identificar los nematodos agalladores asociados al cultivo de papaya (Carica papaya L. en los municipios de Tierralta, Valencia, Lorica, Montería y Montelíbano que constituyen el área productora de papaya en Córdoba. Se evaluaron variables morfológicas y morfométricas en hembras, machos y juveniles de segundo estadío (J2. En las muestras de suelo se determinó pH, contenido de materia orgánica (MO, conductividad eléctrica (CE y textura, a fin de correlacionarlas con la presencia de especies nematodas. Se encontraron Meloidogyne javanica,M. incognita y M. arenaria, siendo M. incognita la especie más frecuente. Las tres especies se encontraron mezcladas en 37,5% de los individuos;M. incognita y M. arenaria en 50%, mientras que M. incognita y M. javanica no se encontraron mezcladas. Las especies se encontraron en pH de 4,9 a 6,4; CE de 0,1 a 0,45 dS· m^-1; MO de 1,2 % a 2,5 % y la textura fue arenosa, franca y franco arenosa. El pH, el contenido de arena y la CE correlacionan de manera positiva con la presencia de los nematodos, mientras la MO mostró correlación negativa. Se reporta por primera vez la ocurrencia de M. javanica, M. incognita, M. arenaria, así como la mezcla de M. incognita y M. arenaria, en papayas de Colombia.

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.

Growth responses of maritime sand dune plant species to arbuscular mycorrhizal fungi

Directory of Open Access Journals (Sweden)

Mariusz Tadych

2014-08-01

Full Text Available In a pot experiment conducted in a greenhouse, the response of 6 plant species dominating in the succession of vegetation of a deflation hollow of the Łeba Bar to inoculation with arbuscular mycorrhizal fungi (AMF was investigated. The inoculum was a mixture of soil, roots and spores of 5 species of AMF with the dominant species Glomus aggregatum. Except for Corynephorus canescens and Festuca rubra subsp. arenaria, both the growth and the dry matter of above-ground parts of plants of Agrostis stolonifera, Ammophila arenaria, Corynephorus canescens, Juncus articulatus and J. balticus inoculated with AMF were higher than those growing in soils lacking infection propagules of these fungi. Inoculation with AMF decreased the dry matter of root: shoot ratios in 5 plant species. This property was not determined in Festuca rubra subsp. arenaria due to the death of all control plants. The level of mycorrhizal infection was low and did not correlate with the growth responses found. The high growth reaction of Juncus spp. to AMF found in this study suggests that the opinion of non-mycotrophy or low dependence of plants of Juncaceae on AMF was based on results of investigations of plants growing in wet sites known to inhibit the formation of mycorrhizae.

Insights from the Shell Proteome: Biomineralization to Adaptation.

Science.gov (United States)

Arivalagan, Jaison; Yarra, Tejaswi; Marie, Benjamin; Sleight, Victoria A; Duvernois-Berthet, Evelyne; Clark, Melody S; Marie, Arul; Berland, Sophie

2017-01-01

Bivalves have evolved a range of complex shell forming mechanisms that are reflected by their incredible diversity in shell mineralogy and microstructures. A suite of proteins exported to the shell matrix space plays a significant role in controlling these features, in addition to underpinning some of the physical properties of the shell itself. Although, there is a general consensus that a minimum basic protein tool kit is required for shell construction, to date, this remains undefined. In this study, the shell matrix proteins (SMPs) of four highly divergent bivalves (The Pacific oyster, Crassostrea gigas; the blue mussel, Mytilus edulis; the clam, Mya truncata, and the king scallop, Pecten maximus) were analyzed in an identical fashion using proteomics pipeline. This enabled us to identify the critical elements of a "basic tool kit" for calcification processes, which were conserved across the taxa irrespective of the shell morphology and arrangement of the crystal surfaces. In addition, protein domains controlling the crystal layers specific to aragonite and calcite were also identified. Intriguingly, a significant number of the identified SMPs contained domains related to immune functions. These were often are unique to each species implying their involvement not only in immunity, but also environmental adaptation. This suggests that the SMPs are selectively exported in a complex mix to endow the shell with both mechanical protection and biochemical defense. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Efficacy of a high potency O1 Manisa monovalent vaccine against heterologous challenge with foot-and-mouth disease virus of O/SEA/Mya-98 lineage in sheep.

Science.gov (United States)

Singanallur, N B; Pacheco, J M; Arzt, J; Stenfeldt, C; Fosgate, G T; Rodriguez, L; Vosloo, W

2017-09-01

Potency tests for commercial oil-adjuvanted foot-and-mouth disease (FMD) vaccines are usually carried out in cattle, using a full dose (2 ml) of vaccine and homologous virus challenge. However, in sheep the recommended vaccine dose is half of the cattle dose (1 ml) and most vaccines have not been potency tested for this species, especially with heterologous viruses. To determine the efficacy of a high potency (>6PD 50 ) FMD virus (FMDV) O1Manisa vaccine in sheep, we carried out a study using a heterologous FMDV (FMDV O/SKR/2010 - Mya-98 strain) challenge. Groups of seven animals each were vaccinated with 2×, 1×, 1/2× or 1/4× dose (2 ml, 1 ml, 0.5 ml or 0.25 ml respectively) and challenged at 7 days post vaccination (dpv). Only 3 of the 7 sheep in the group vaccinated with 2 ml were protected. With 2 additional groups, receiving double or single doses and challenged at 14 dpv, 4 of 7 sheep were protected in each group. None of the sheep had measurable neutralising antibodies against the vaccine or challenge virus at 7 dpv. However, all vaccinated animals challenged at 14 dpv had a homologous neutralising response against FMDV O1 Manisa on the day of challenge and all but one animal also had a heterologous response to FMDV O/SKR/2010. Infectious FMDV and viral RNA could be found in nasal swabs between 1 and 6 days post challenge (dpc) in most vaccinated sheep, but those vaccinated with higher doses or challenged at 14 dpv showed significant decreases in the level of FMDV detection. Intermittent virus shedding was noticed between 1 and 35 dpc in all vaccinated groups, but persistent infection could be demonstrated only in 4 sheep (20%). This study showed that at the recommended dose, a high potency (>6 PD 50 ) FMDV O1Manisa vaccine does not protect sheep against a heterologous challenge at 7 dpv. However, partial protection was observed when a double dose was used at 7 dpv or when double or single dose vaccinated sheep were challenged at 14 dpv. Copyright �

Biomonitoring and assessment of monomethylmercury exposure in aqueous systems using the DGT technique

Energy Technology Data Exchange (ETDEWEB)

Clarisse, O., E-mail: olivier.clarisse@umoncton.ca [Trent University, Chemistry Department, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Universite de Moncton, Departement de Chimie et de Biochimie, Moncton, New Brunswick E1A 3E9 (Canada); Lotufo, G.R. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180-6199 (United States); Hintelmann, H. [Trent University, Chemistry Department, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Best, E.P.H. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180-6199 (United States); U.S. Environmental Protection Agency, National Risk Management Research Laboratory, 26 West Martin Luther King Boulevard, Cincinnati, OH 45268 (United States)

2012-02-01

A series of laboratory experiments was conducted under realistic environmental conditions to test the ability of the Diffusive Gradient in Thin film (DGT) technique to mimic monomethylmercury (MMHg) bioaccumulation by a clam (Macoma balthica, Baltic clam). Using isotope enriched MMHg as tracers, bioavailability was determined by comparing the rate of MMHg uptake by novel DGT devices and sentinel organism over time. Experiments were conducted under varying conditions of salinity and MMHg speciation. Depending on MMHg level and speciation in the dissolved phase, MMHg uptake rates by the sentinel organism varied greatly from 0.4 to 2.4 L g{sup -1} d{sup -1}. Reproducibilities of MMHg uptakes by DGT and clams were estimated at 7 and 38%, respectively. A significant linear relationship (log basis) between MMHg accumulation by DGT and clams was observed (r{sup 2} = 0.89). The study demonstrates that DGT results reasonably predict MMHg uptake by clams from the aqueous phase and provide the basis for application of the DGT device as a surrogate for sentinel organism for monitoring bioavailable MMHg. - Highlights: Black-Right-Pointing-Pointer We investigate the potential of DGT devices to act as surrogates for sentinel organism. Black-Right-Pointing-Pointer We compare monomethylmercury accumulation in DGT devices and in clams from the dissolved phase. Black-Right-Pointing-Pointer We examine the effects of salinity and MMHg speciation on MMHg accumulation by DGT and clams. Black-Right-Pointing-Pointer For all laboratory experiments, a strong overall correlation between MMHg accumulations in clams and DGTs is observed.

Фиалка песчаная (viola arenaria DC. ) - новый источник макро- и микроэлементов

OpenAIRE

Мартынов, А.; Чупарина, Е.

2008-01-01

Изучен элементный состав надземных органов фиалки песчаной Viola arenaria DC., сем. Violaceae. Обнаружены 20 макрои микроэлементов: Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Ba, Pb и установлено их количественное содержание. Преобладают среди них калий, фосфор, магний, кальций, кремний.

Biodepuration of polynuclear aromatic hydrocarbons from a bivalve mollusc, Mercenaria mercenaria L

International Nuclear Information System (INIS)

Tanacredl, J.T.; Cardenas, R.R.

1991-01-01

Mercenaria mercenaria, exposed in vitro for 48 h to nine parent polynuclear aromatic hydrocarbons (PAHs) found in waste crankcase oil (WCCO) and analyzed by multiparametric analysis over a 45-day depuration period in an activated carbon filtration aquaria system, did not depurate PAHs, but rather maintained them at detectable levels. Uptake of PAHs was shown to be directly related to clam weight. A cluster analysis of empirical results reaffirmed a biostabilization in PAH groupings in clam tissue over a 45-day depuration period and exhibited no evidence of a decreasing trend in total PAHs when subjected to ANOVA. Due to the commercial importance of hard-shell clams, the practices of clam depuration and clam relaying are reviewed in light of potential long-terms public health exposures to low-level xenobiotics and the implications for human consumers

Divergence times and colonization of the Canary Islands by Gallotia lizards.

Science.gov (United States)

Cox, Siobhan C; Carranza, Salvador; Brown, Richard P

2010-08-01

The Canary Islands have become a model region for evolutionary studies. We obtained 1.8 Kbp of mtDNA sequence from all known island forms of the endemic lizard genus Gallotia and from its sister taxon Psammodromus in order to reanalyze phylogenetic relationships within the archipelago, estimate lineage divergence times, and reconstruct the colonization history of this group. Well-supported phylogenies were obtained using maximum parsimony and Bayesian inference. Previous studies have been unable to establish the branching pattern at the base of the tree. We found evidence that G. stehlini (Gran Canaria) originated from the most basal Gallotia node and G. atlantica from the subsequent node. Divergence times were estimated under a global clock using Bayesian Markov Chain Monte Carlo methods implemented by three different programs: BEAST, MCMCTREE, MULTIDIVTIME. Node constraints were derived from subaerial island appearance data and were incorporated into the analyses as soft or hard maximal bounds. Posterior node ages differed slightly between programs, possibly due to different priors on divergence times. The most eastern Canary Islands first emerged just over 20 mya and their colonization appears to have taken place relatively quickly, around 17-20 mya. The subsequent node is consistent with cladogenesis due to colonization of Gran Canaria from the eastern islands about 11-13 mya. The western islands appear to have been colonized by a dispersal event from Lanzarote/Fuerteventura in the east to either La Gomera or one of the ancient edifices that subsequently formed Tenerife in the west, about 9-10 mya. Within the western islands, the most recent node that is ancestral to both the G. intermedia/G. gomerana/G. simonyi and the G.galloti/G. caesaris clades is dated at about 5-6 mya. Subsequent dispersal events between ancient Tenerife islands and La Gomera are dated at around 3 mya in both clades, although the direction of dispersal cannot be determined. Finally, we

Concentration distribution and potential health risk of heavy metals in Mactra veneriformis from Bohai Bay, China

International Nuclear Information System (INIS)

Li, Yuhu; Liu, Hui; Zhou, Hailong; Ma, Wandong; Han, Qian; Diao, Xiaoping; Xue, Qinzhao

2015-01-01

Highlights: • Mn was dominant in the heavy metals, followed by Zn, and Pb was the lowest. • THQs of Co were the highest at three sections and the others were less than 1. • Heavy metal concentration in clam was affected by pollution sources, and itself. • Consumer should be aware of their health risks associated with the consuming clam. - Abstract: To investigate the pollution level and evaluate the potential health risks of heavy metals, the concentrations of chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), antimony (Sb), and lead (Pb) were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in 198 clams (Mactra veneriformis) collected from 11 sites of the Bohai Bay. The results showed that heavy metal concentrations in the clams were different at different sites (p < 0.05). Mn was dominant with a percentage of 22.08–77.03% in heavy metals, followed by Zn with 12.66–57.11%, and the concentration of Pb was the lowest with 0.45–1.04%. The potential health risk to consumers was evaluated by the target hazard quotient (THQ) and the maximum daily consumption rate (CR max ). The results indicated that the THQs of Co were the highest with the values of 1.125, 1.665, and 1.144 at three sections; the values of other individual metals were <1, which indicated that consumption of clams from the study areas caused health risks due to Co. Moreover, the CR max values also indicated the potential health risk caused by Co in clams consumed in this area. Pearson correlation analysis and principal component analysis (PCA) indicated that there were significantly positive or negative correlations between the heavy metals (p < 0.05), and the studied metals were divided into four groups. The results indicated that the concentrations of heavy metals in clams were affected not only by pollution sources but also by the characteristics of clams that could absorb

Fatty acid composition of symbiotic zooxanthellae in relation to their hosts.

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Bishop, D G; Kenrick, J R

1980-10-01

Gymnodinoid dinoflagellate symbionts, commonly referred to as zooxanthellae, are widely distributed among marine invertebrates. It has been assumed that they represent only one species,Gymnodinium microadriaticum. The fatty acid composition of total lipids and galactolipids of zooxanthellae isolated from 8 species of corals, 3 species of clams and a foraminiferan have been analyzed and found to vary according to the host. For example, the content of eicosapentaenoic acid in clam zooxanthellae monogalactosyldiacylglycerol was less than 2%, whereas in the same lipid from coral zooxanthellae, the content ranged from 9 to 22%. Corresponding values for the acid in digalactosyl-diacylglycerol were 1-8% from clam zooxanthellae and 23-40% from coral zooxanthellae. Coral zooxanthellae monogalactosyldiacylglycerol contain higher levels of octadecatetraenoic acid than are found in digalactosyldiacylglycerol, whereas the reverse is true in clam zooxanthellae. The fatty acid composition of the lipids of an axenic culture of zooxanthellae isolated from the clamTridacna maxima are similar to those of cells freshly isolated from the host. The results suggest either that the host is capable of affecting the fatty acid metabolism of the symbiont or that different strains of zooxanthellae occur in corals and clams.

Veligers of the invasive Asian clam Corbicula fluminea in the Columbia River Basin: Broadscale distribution, abundance, and ecological associations

Science.gov (United States)

Hassett, Whitney; Bollens, Stephen M.; Counihan, Timothy D.; Rollwagen-Bollens, Gretchen; Zimmerman, Julie; Emerson, Joshua E.

2017-01-01

The invasive Asian clam Corbicula fluminea was introduced to North America in the 1930s and now inhabits most regions of the conterminous United States; however, the distribution and ecology of C. fluminea in the Columbia River Basin is poorly understood. During 2013 and 2014, 5 Columbia-Snake River reservoirs were sampled monthly from May through September, along with 23 additional lakes and reservoirs sampled once each summer. Associations among C. fluminea veligers, other components of the plankton, and environmental variables were analyzed using non-metric multidimensional scaling and canonical correspondence analysis. Corbicula fluminea veligers were found in high abundances in all mainstem Columbia-Snake River reservoirs, with an annual mean abundance of 71.2 individuals per cubic meter (inds./m3). Only 3 of 23 lakes and (non-mainstem) reservoirs contained C. fluminea, with abundances considerably lower (maximum = 21.2 inds./m3) than in the mainstem reservoirs. A diatom-dominated community preceded the spawning of C. fluminea in early summer at all sites. Corbicula fluminea veligers characterized the plankton community in late summer and were associated with cyanobacteria and high water temperatures. A third community, characterized by cyanobacteria, was apparent in non-mainstem sites in July and August. Our analyses describe the relationship of C. fluminea to the plankton community and environment, which contributes to our understanding of the possible effects of C. fluminea infestations and which waterbodies in the Columbia River Basin are at risk for infestation. Understanding the effects and environmental determinants of invasive mollusks will be increasingly important in the future with the possible arrival of zebra (Dreissena polymorpha) or quagga (D. bugensis) mussels to the region.

Bioaccumulation of mercury in reared and wild Ruditapes philippinarum of a Mediterranean lagoon

Science.gov (United States)

Giani, Michele; Rampazzo, Federico; Berto, Daniela; Maggi, Chiara; Mao, Andrea; Horvat, Milena; Emili, Andrea; Covelli, Stefano

2012-11-01

The Marano and Grado lagoon, one of the largest wetlands in the Mediterranean Sea, has been subject to mercury contamination by industrial and mining activities. This must be considered a severe threat for Manila clam harvesting, which is an important fishing and commercial activity in the area. Contamination levels and potential risk for human consumption both in reared and wild clams collected from the lagoon were assessed by analyzing total mercury (THg) and methylmercury (MeHg) contents. In addition, relationships between THg and MeHg in sediments and in the bivalves were investigated. Increased bioaccumulation of THg but not of MeHg with increasing size of wild clam populations was observed at most sites. Higher concentrations both of THg (605 ± 210 ng g-1 ww) and MeHg (147 ± 37 ng g-1 ww) were detected in the eastern lagoon where the highest THg contents in sediments were observed as a consequence of the long-term supply of cinnabar rich suspended material from the Isonzo river. The variation of Hg content in seeded Manila clams during growth was monitored over a period of 18 months at two sites of the western sector of the lagoon. Results showed that the two areas were suitable for clam farming, with THg levels in reared bivalves always lower than the 0.5 mg kg-1 ww European Community limit. At the same time, as clams grew bigger in size, their THg and MeHg concentrations decreased, becoming lower than in the starting seeded pool. Reared clams presented lower THg (84 ± 55 ng g-1 ww) and MeHg (44.1 ± 24.6 ng g-1 ww) content than wild clams of the same commercial size (>30 mm). Based on a precautionary approach, intake of Hg and MeHg with the estimated clam consumption does not seem to constitute a risk for human health in the studied area.

Molecular marker screening of peanut ( Arachis hypogaea L ...

African Journals Online (AJOL)

Molecular marker screening of peanut (Arachis hypogaea L.) germplasm for Meloidogyne arenaria resistance. V Carpentieri-Pipolo, M Gallo-Meagher, DW Dickson, DW Gorbet, M de Lurdes Mendes, SG Hulse de Souza ...

Incidence and Identification of Root-Knot Nematode in Plastic-House Fields of Central Area of Korea

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Hyoung Rai Ko

2017-12-01

Full Text Available To investigate occurrence of root-knot nematode (RKN in plastic house of central area of Korea, 132 soil samples were collected in cucumber, water melon, tomato, red pepper and strawberry fields from 2013 to 2015. Among 132 soil samples, 65 soil samples (49% were infested with RKN and mean density of RKN was 178 second-stage juveniles per 100 cm³ soil (min. 1 ~ max. 3,947. The frequency of RKN by regional was the highest in Chuncheon with 80%, followed by Cheonan (68%, Nonsan (36%, Buyeo (33% and Yesan (30%. The frequency of RKN by crops was the highest in tomato with 83%, followed by cucumber (61%, strawberry (41%, red pepper (30%, watermelon (26%. To identify the species of RKN, fifteen populations were selected for representative populations. As a phylogenetic analysis of 15 populations, southern root-knot nematode (Meloidogyne incognita, peanut root-knot nematode (M. arenaria and northern root-knot nematode (M. hapla were identified with 47%, 20% and 33% ratio, respectively. In crops, M. incognita, M. arenaria and M. hapla were detected in tomato, M. incognita and M. arenaria were detected in cucumber and watermelon, and M. hapla was detected in strawberry and lettuce. Thus, there should be a continuous management to major species of each crops to prevent dispersal of RKN damages.

Proboscidean mitogenomics: chronology and mode of elephant evolution using mastodon as outgroup.

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Nadin Rohland

2007-08-01

Full Text Available We have sequenced the complete mitochondrial genome of the extinct American mastodon (Mammut americanum from an Alaskan fossil that is between 50,000 and 130,000 y old, extending the age range of genomic analyses by almost a complete glacial cycle. The sequence we obtained is substantially different from previously reported partial mastodon mitochondrial DNA sequences. By comparing those partial sequences to other proboscidean sequences, we conclude that we have obtained the first sequence of mastodon DNA ever reported. Using the sequence of the mastodon, which diverged 24-28 million years ago (mya from the Elephantidae lineage, as an outgroup, we infer that the ancestors of African elephants diverged from the lineage leading to mammoths and Asian elephants approximately 7.6 mya and that mammoths and Asian elephants diverged approximately 6.7 mya. We also conclude that the nuclear genomes of the African savannah and forest elephants diverged approximately 4.0 mya, supporting the view that these two groups represent different species. Finally, we found the mitochondrial mutation rate of proboscideans to be roughly half of the rate in primates during at least the last 24 million years.

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. Copyright © 2015

Facultative parasitism by the bivalve Kurtiella pedroana in the sand crab Emerita analoga

Science.gov (United States)

Bhaduri, Ritin; Valentich-Scott, Paul; Hilgers, Mark; Singh, Rajvir; Hickman, Mikaila; Lafferty, Kevin D.

2017-01-01

It is rare that an organism capable of independent or commensalistic existence can also become endoparasitic on a host. In this study, we documented a potential step toward parasitism in the commensal clam Kurtiella pedroana (Bivalvia: Galeommatoidea). Galeommatoideans are known commensals of various invertebrates, including crustaceans. Emerita analoga (Decapoda: Hippidae) is an abundant intertidal decapod inhabiting sandy beaches of the Pacific coast of North and South America. Crabs collected from Monterey Bay, California, were measured and examined externally and internally for associated molluscs. Out of the 520 crabs, 37 large female individuals harbored 49 bivalves (prevalence of 7.11% and mean intensity of 1.3). Forty-one ectocommensal clams were either inside the crab's branchial chambers or on their lateroventral surfaces, and were attached by byssal threads. Our key finding was eight clams that lacked byssal threads and were living in the hemocoel. These internal clams were significantly smaller than the ectocommensals. Because these internal clams lacked access to their normal food, we hypothesize they might have fed on their host's hemolymph as would a parasite. This clam species likely can't reproduce inside its host, implying that endoparasitism is a dead-end state for K. pedroana. Facultative parasitism in a free-living or an ectocommensal is uncommon and suggests a pathway to parasitism.

Analysis of banned veterinary drugs and herbicide residues in shellfish by liquid chromatography-tandem mass spectrometry (LC/MS/MS) and gas chromatography-tandem mass spectrometry (GC/MS/MS)

International Nuclear Information System (INIS)

Chang, Geng-Ruei; Chen, Hui-Shan; Lin, Feng-Yi

2016-01-01

Seafood safety is a crucial public health concern for consumers. In this study, we applied a validated method to analyze the residue of banned veterinary drugs in shellfish, namely chloramphenicol, malachite green, leucomalachite green, and nitrofuran metabolites; additionally, the QuEChERS method was employed to detect 76 herbicides by LC/MS/MS and GC/MS/MS. In total, 42 shellfish samples, which included hard clams, freshwater clams, and oysters, were collected from aquafarms and production areas in Taiwan during 2012. Our results revealed 3.8 ng/g of chloramphenicol in one hard clam, 19.9–32.1 ng/g of ametryn in two hard clams, 16.1–60.1 ng/g of pendimethalin in four hard clams, and 17.0 ng/g of mefenacet in one oyster, indicating that 19.1% of the samples contained residues from banned veterinary drugs and pesticides. These data can be used to monitor the residue of veterinary drugs and pesticides in aquatic organisms and as a reference for food safety. - Highlights: • A certified method was employed for analyzing residues of banned veterinary drugs and herbicides in shellfish samples. • The trace levels of chloramphenicol, ametryn, pendimethalin were detected in hard clam samples. • For ensuring food safety, continual monitoring of aquatic products is necessary.

Estrutura de duas formações vegetais do cordão externo da restinga de Marambaia, RJ Structure of two plant communities on Marambaia barrier island, Rio de Janeiro, Brazil

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Luis Fernando Tavares de Menezes

1999-08-01

Full Text Available Foram caracterizadas duas formações vegetais, psamófila-reptante e arbustiva de Palmae, no cordão arenoso externo da restinga de Marambaia (RJ com base na posição topográfica, na fisionomia e na estrutura, utilizando-se o método de parcelas. Embora as duas formações sejam visualmente distintas, há uma zona de transição entre elas. Das 23 espécies amostradas na formação psamófila-reptante, Ipomoea pes-caprae, Ipomoea imperati, Allagoptera arenaria, Sporobolus virginicus, Remirea marítima e Panicum racemosum despontaram com maiores valores de importância (VI. A formação halófila dominada por Blutaparon portulacoides, típica de outras restingas no litoral brasileiro, não foi identificada devido ao intenso dinamismo da faixa entre o mar e a primeira linha de cristas praiais estabilizadas. A formação arbustiva de Palmae é dominada por Allagoptera arenaria, com 56% do VI total, dentre as 64 espécies amostradas. As duas formações são dominadas por geófitas rizomatosas.Two plant communities (creeping psamophyte and palm scrub are described from the outer Marambaia beach ridge, Rio de Janeiro State, Brazil, based on topography, vegetation physiognomy, and structure. Although the two communities can be distinguished visually, they are joined by a transition zone. Ipomoea pes-caprae, Ipomoea imperati, Remirea maritima, Allagoptera arenaria, Sporobolus virginicus, and Panicum racemosum were the most important species sampled in the creeping psammophyte community out of a total of 23. The halophyte community reported for other sandy coastal plains in Brazil was not observed at Marambaia due to the intense wave action on this beach. The palm scrub community was dominated by Allagoptera arenaria (56% of total importance value out of a total of 64 species. Rhizome-geophytes dominate both communities.

Examining time trends in the Oldowan technology at Beds I and II, Olduvai Gorge.

Science.gov (United States)

Kimura, Yuki

2002-09-01

The lithic analysis of the Bed I and II assemblages from Olduvai Gorge reveals both static and dynamic time trends in early hominids' technology from 1.8 to 1.2 m.y.a. The Bed I Oldowan (1.87-1.75 m.y.a.) is characterized by the least effort strategy in terms of raw material exploitation and tool production. The inclusion of new raw material, chert, for toolmaking in the following Developed Oldowan A (DOA, 1.65-1.53 m.y.a.) facilitated more distinctive and variable flaking strategies depending on the kind of raw materials. The unique characters of DOA are explainable by this raw material factor, rather than technological development of hominids. The disappearance of chert in the subsequent Developed Oldowan B and Acheulian (1.53-1.2 m.y.a.) necessitated a shift in tool production strategy more similar to that of Bed I Oldowan than DOA. However, the evidence suggests that Bed II hominids might have been more skillful toolmakers, intensive tool-users, and engaged in more active transport of stone tools than the Bed I predecessors. Koobi Fora hominids maintained a more static tool-using behavior than their Olduvai counterparts due mainly to a stable supply of raw materials. They differed from Olduvai hominids in terms of less battering of cores, consistent transport behavior, and few productions of side-struck flakes, indicating a regional variation of toolmaking and using practice. However, they shared with Olduvai hominids a temporal trend toward the production of larger flakes from larger cores after 1.6 m.y.a. Increased intake of animal resources and the expansion of ranging area of Homo ergaster would have led to the development of technological organization. Technological changes in the Oldowan industry are attested at Olduvai Gorge, Koobi Fora, and Sterkfontein, suggesting that it was a pan-African synchronous phenomenon, beginning at 1.5 m.y.a.

High-intensity strength training improves function of chronically painful muscles

DEFF Research Database (Denmark)

Andersen, Lars L; Andersen, Christoffer H; Skotte, Jørgen H

2014-01-01

AIM: This study investigates consequences of chronic neck pain on muscle function and the rehabilitating effects of contrasting interventions. METHODS: Women with trapezius myalgia (MYA, n = 42) and healthy controls (CON, n = 20) participated in a case-control study. Subsequently MYA were...... randomized to 10 weeks of specific strength training (SST, n = 18), general fitness training (GFT, n = 16), or a reference group without physical training (REF, n = 8). Participants performed tests of 100 consecutive cycles of 2 s isometric maximal voluntary contractions (MVC) of shoulder elevation followed...... MYA and CON. In the intervention study, SST improved all force parameters significantly more than the two other groups, to levels comparable to that of CON. This was seen along with muscle fiber hypertrophy and increased capillarization. CONCLUSION: Women with trapezius myalgia have lower strength...

Using trace element concentrations in Corbicula fluminea to identify potential sources of contamination in an urban river

International Nuclear Information System (INIS)

Loeffler Peltier, Gretchen; Meyer, Judith L.; Jagoe, Charles H.; Hopkins, William A.

2008-01-01

We used the biomonitor, Corbicula fluminea, to investigate the contributions of trace elements associated with different point sources and land uses in a large river. Trace elements were analyzed in tissues of clams collected from 15 tributary streams draining five land use or point source types: agriculture, forest, urban, coal-fired power plant (CFPP), and wastewater (WWTP). Clams from forested catchments had elevated Hg concentrations, and concentrations of arsenic and selenium were highest (5.0 ± 0.2 and 13.6 ± 0.9 μg g -1 dry mass (DM), respectively) in clams from CFPP sites. Cadmium concentrations were significantly higher in clams from urban and CFPP sites (4.1 ± 0.2 and 3.6 ± 0.9 μg g -1 DM, respectively). Non-metric multidimensional scaling (NMS) of tissue concentrations in clams clustered at CFPP and forest/agriculture sites at opposite ends of the ordination space, and the distribution of sites was driven by Cu, Zn, Cd, and Hg. - C. fluminea collected downstream of CFPPs had elevated tissue concentrations of trace elements

Embrionary and larval development of the marine clam Tivela mactroides (Bivalvia:Veneridaein Zulia State,Venezuela

Directory of Open Access Journals (Sweden)

Yinett M Reverol

2004-12-01

Full Text Available The marine clam,Tivela mactroides ,from Caño Sagua beach,Venezuela,was spawned and reared under laboratory conditions to monitor its early development.Spawning was spontaneous but in some cases it had to be induced by the additon of eggs and sperm.After fertilization,the embryonic development occurred at 5 hr approximately. Trochophore larvae were observed between eight and ten hours later.Straight-hinged veliger stage appeared 15 hr after fertilization.Transition from veliger stage to the umbo stage occurred about eight days after fertilization.Pediveliger stage was observed 22 days after fertilization.Metamorphosis of T.mactroides was not successful under our laboratory conditions;probably the bacterial contamination and subsequent mortalities were important factors constraining the final phase of the larval cycle.However,in a few cases young individuals were observed.We suspect that this was due to unfavorable conditions (e.g.:bacterial contamination, unsuitable food availability,etc.and the broad variation in developmental times,suggesting that these stages might be particularly sensitive to environmental changes.These results may not necessarily reflect what happens under natural conditions.Rev.Biol.Trop.52(4:903-909.Epub 2005 Jun 24.La almeja Tivela mactroides ,de la playa Caño Sagua, Venezuela,fue desovada y cultivada bajo condiciones de laboratorio,monitoreando su desarrollo embrionario y larvario.El desove fue espontáneo,sin embargo,en algunos casos se indujo adicionando óvulos y espermatozoides. El desarrollo embrionario se produjo en cinco horas, aproximadamente.La larva trocófora fue observada a las diez horas,mientras que la prodisoconcha aparece a las 15 horas después de la fertilización.La larva disoconcha aparece ocho días después de la fecundación y la veliconcha,aproximadamente a los 20 días.La metamorfosis de T.mactroides no fue satisfactoria bajo estas condiciones, ya que la contaminación bacterial fue uno de los

Evidence for the role of horizontal transfer in generating pVT1, a large mosaic conjugative plasmid from the clam pathogen, Vibrio tapetis.

Directory of Open Access Journals (Sweden)

Gaël Erauso

Full Text Available The marine bacterium Vibrio tapetis is the causative agent of the brown ring disease, which affects the clam Ruditapes philippinarum and causes heavy economic losses in North of Europe and in Eastern Asia. Further characterization of V. tapetis isolates showed that all the investigated strains harbored at least one large plasmid. We determined the sequence of the 82,266 bp plasmid pVT1 from the CECT4600(T reference strain and analyzed its genetic content. pVT1 is a mosaic plasmid closely related to several conjugative plasmids isolated from Vibrio vulnificus strains and was shown to be itself conjugative in Vibrios. In addition, it contains DNA regions that have similarity with several other plasmids from marine bacteria (Vibrio sp., Shewanella sp., Listonella anguillarum and Photobacterium profundum. pVT1 contains a number of mobile elements, including twelve Insertion Sequences or inactivated IS genes and an RS1 phage element related to the CTXphi phage of V. cholerae. The genetic organization of pVT1 underscores an important role of horizontal gene transfer through conjugative plasmid shuffling and transposition events in the acquisition of new genetic resources and in generating the pVT1 modular organization. In addition, pVT1 presents a copy number of 9, relatively high for a conjugative plasmid, and appears to belong to a new type of replicon, which may be specific to Vibrionaceae and Shewanelleacae.

Can ecological history influence immunomarker responses and antioxidant enzyme activities in bivalves that have been experimentally exposed to contaminants? A new subject for discussion in "eco-immunology" studies.

Science.gov (United States)

Matozzo, Valerio; Giacomazzo, Matteo; Finos, Livio; Marin, Maria Gabriella; Bargelloni, Luca; Milan, Massimo

2013-07-01

Numerous studies have demonstrated that environmental parameters affect bivalve immunomarkers. In the present study, we tested the hypothesis that clams (Venerupis philippinarum) collected in sites with different environmental conditions respond differently to experimental contaminant exposure. Clams were collected at two sites within the Lagoon of Venice that are influenced differently by both anthropogenic impact and natural conditions: Marghera, which is characterised by relatively high contamination levels and restricted clam fishing, and Chioggia, which is inside a licensed clam culture area that is characterised by lower contamination levels. Total haemocyte count, haemocyte diameter and volume, lysozyme activity in both haemocyte lysate and cell-free haemolymph, superoxide dismutase and catalase activities in gills and digestive glands were measured at time 0 (clam sampling time), after 7 days of acclimation in the laboratory and after 1, 3 and 7 days of copper exposure. Interestingly, statistical analyses (three-way ANOVA and Canonical Correlation Analysis) revealed persistent differences in the biological responses of clams from the two sampling sites before and after copper exposure. Conversely, the influence of copper on cellular and biochemical parameters was negligible. Overall, the results obtained indicated that animals with a different ecological history respond differently to experimental contaminant exposure. In addition, this study suggested that immunomarkers and other biomarkers might be used to determine the origin of fishing products. Copyright © 2013 Elsevier Ltd. All rights reserved.

Origin of marine planktonic cyanobacteria.

Science.gov (United States)

Sánchez-Baracaldo, Patricia

2015-12-01

Marine planktonic cyanobacteria contributed to the widespread oxygenation of the oceans towards the end of the Pre-Cambrian and their evolutionary origin represents a key transition in the geochemical evolution of the Earth surface. Little is known, however, about the evolutionary events that led to the appearance of marine planktonic cyanobacteria. I present here phylogenomic (135 proteins and two ribosomal RNAs), Bayesian relaxed molecular clock (18 proteins, SSU and LSU) and Bayesian stochastic character mapping analyses from 131 cyanobacteria genomes with the aim to unravel key evolutionary steps involved in the origin of marine planktonic cyanobacteria. While filamentous cell types evolved early on at around 2,600-2,300 Mya and likely dominated microbial mats in benthic environments for most of the Proterozoic (2,500-542 Mya), marine planktonic cyanobacteria evolved towards the end of the Proterozoic and early Phanerozoic. Crown groups of modern terrestrial and/or benthic coastal cyanobacteria appeared during the late Paleoproterozoic to early Mesoproterozoic. Decrease in cell diameter and loss of filamentous forms contributed to the evolution of unicellular planktonic lineages during the middle of the Mesoproterozoic (1,600-1,000 Mya) in freshwater environments. This study shows that marine planktonic cyanobacteria evolved from benthic marine and some diverged from freshwater ancestors during the Neoproterozoic (1,000-542 Mya).

Preconstruction Biogeochemical Analysis of Mercury in Wetlands Bordering the Hamilton Army Airfield (HAAF) Wetlands Restoration Site. Part 3

Science.gov (United States)

2009-12-01

but not included in the analyzed samples, were zooplankton, bacteria, and larvae for the Asian clam and mysids for the shrimp (Table 5-4). The...Asian clam, shrimp , goby) may contribute the most, while the central role of detritus-associated MeHg has to be further explored. The Questions and...Asian clam) Bay 1 -20.9 (-) 11.6 (-) 13.3 (-) Shrimp sp. Bay 6 -19.6 (0.4) 15.4 (1.6) 14.7 (1.4) Carcinus maenas (European green crab) Bay

Molecular marker screening of peanut (Arachis hypogaea L ...

African Journals Online (AJOL)

SAM

2014-06-25

Jun 25, 2014 ... the genomic DNA, the frozen samples were ground and DNA was extracted .... RFLP analysis, no evidence of segregation was found in ... Figure 1. RFLP locus R2430E linked to resistance to Meloidogyne arenaria in peanut.

Evidence for sex pheromones and inbreeding avoidance in select North America yellowjacket species (Hymenoptera: Vespidae)

Science.gov (United States)

Little is known about the roles of sex pheromones in mate-finding behavior of social wasps (Vespidae). Working with the aerial yellowjacket, Dolichovespula arenaria (Fabricius), baldfaced hornet, D. maculata (L.), western yellowjacket, Vespula pensylvanica (Saussure), southern yellowjacket, V. squam...

Intestinal Microbiota and Species Diversity of Campylobacter and Helicobacter spp. in Migrating Shorebirds in Delaware Bay

Science.gov (United States)

Using rDNA sequencing analysis, we examined the bacterial diversity and the presence of opportunistic bacterial pathogens (i.e., Campylobacter and Helicobacter) in Red Knot (Calidris canutus, n=40), Ruddy Turnstone (Arenaria interpres, n=35), and Semipalmated Sandpiper (Calidris ...

Tridacna maxima

African Journals Online (AJOL)

related to substrate affinity by two giant clam species found on the Mauritian coral reefs. Giant clams .... (Marine Protected Areas (Amendment) Act, 2007) with clear water and an ..... Endangered Species of Wild Fauna and Flora. (CITES) ...

Comparative feeding on chlorophyll - rich versus remaining organic matter in bivalve shellfish

NARCIS (Netherlands)

Hawkins, A.; Pascoe, P.L.; Parry, H.; Brinsley, M.; Cacciatore, F.; Black, K.; Fang, J.; Smaal, A.C.

2013-01-01

Filter feeding was compared in the blue mussel Mytilus edulis, Mediterranean mussel Mytilus galloprovincialis, Pacific oyster Crassostrea gigas, Chinese pleated oyster Crassostrea plicatula, Chinese scallop Chlamys farreri,Manila clam Tapes phillipinarum, razor clam Sinonvacula constricta, and blood

PAH (Polycyclic Aromatic Hydrocarbon) bioaccumulation and PAHs/shell weight index in Ruditapes philippinarum (Adams & Reeve, 1850) from the Vallona lagoon (northern Adriatic Sea, NE Italy).

Science.gov (United States)

Cacciatore, Federica; Bernarello, Valentina; Boscolo Brusà, Rossella; Sesta, Giulio; Franceschini, Gianluca; Maggi, Chiara; Gabellini, Massimo; Lamberti, Clauda Virno

2018-02-01

The Vallona lagoon is a transitional area located in the Po River delta (NE, ITALY) traditionally exploited for Manila clam (Ruditapes philippinarum) farming. During 2007-2008, a pipeline was buried in the middle of the lagoon to connect an off-shore structure to facilities on land. PAH levels were monitored in Manila clams and sediments before, during and after the pipeline construction to assess the impact of the activities through the pattern of distribution of the PAH compounds. PAH bioaccumulation in clams displayed seasonal fluctuations with higher levels in autumnal and wintry surveys than in spring-summer. Principal component analysis applied to PAHs in clams highlighted a petrogenic input during ante operam period and a pyrolytic origin during the burying activities. On the contrary, sediment PAH concentrations resulted quite similar both among sites and periods. Biota-Sediment-Accumulation-Factor values also confirmed that sediments were not the major source of PAH pollution for clams in this study. The welfare of clams was examined through two physiological indices (condition index and survival in air) to check the effects of the activities on a commercial resource. Both physiological indices exhibited seasonal variations connected to natural endogenous and exogenous factors; however survival in air was the most sensitive index in highlighting the effects of the pipeline burying activities. Finally, to ensure that PAH bioavailability assessment was not affected by seasonal variation of soft tissues of molluscs, PAHs/shell weight index was applied. Higher levels of this index were observed before and during the burying activities, whilst, after that, values significantly lowered. Moreover, the normalization enabled us to highlight the PAH uptake from clams in some particular periods and to compare different populations in a long-term biomonitoring program with data obtained from different periods of the year. Copyright © 2017 Elsevier Inc. All rights

A non-native prey mediates the effects of a shared predator on an ecosystem service.

Directory of Open Access Journals (Sweden)

James E Byers

Full Text Available Non-native species can alter ecosystem functions performed by native species often by displacing influential native species. However, little is known about how ecosystem functions may be modified by trait-mediated indirect effects of non-native species. Oysters and other reef-associated filter feeders enhance water quality by controlling nutrients and contaminants in many estuarine environments. However, this ecosystem service may be mitigated by predation, competition, or other species interactions, especially when such interactions involve non-native species that share little evolutionary history. We assessed trophic and other interference effects on the critical ecosystem service of water filtration in mesocosm experiments. In single-species trials, typical field densities of oysters (Crassostrea virginica reduced water-column chlorophyll a more strongly than clams (Mercenaria mercenaria. The non-native filter-feeding reef crab Petrolisthes armatus did not draw down chlorophyll a. In multi-species treatments, oysters and clams combined additively to influence chlorophyll a drawdown. Petrolisthes did not affect net filtration when added to the bivalve-only treatments. Addition of the predatory mud crab Panopeus herbstii did not influence oyster feeding rates, but it did stop chlorophyll a drawdown by clams. However, when Petrolisthes was also added in with the clams, the clams filtered at their previously unadulterated rates, possibly because Petrolisthes drew the focus of predators or habituated the clams to crab stimuli. In sum, oysters were the most influential filter feeder, and neither predators nor competitors interfered with their net effect on water-column chlorophyll. In contrast, clams filtered less, but were more sensitive to predators as well as a facilitative buffering effect of Petrolisthes, illustrating that non-native species can indirectly affect an ecosystem service by aiding the performance of a native species.

Contr rol of r root-kn saw not nem wdust matod in tom e by u mato ro ...

African Journals Online (AJOL)

SAM

proved with visualizing mical level a ot-knot nema ard dust ame dust. by- and accum ..... Table 2. Effect of sawdust on length of shoot and root (cm) of tomato plants. ...... Evaluation of powdered pine bark for control of Meloidogyne arenaria.

Microhabitat and biology of Sphaerium striatinum in a central New York stream

Science.gov (United States)

Dittman, Dawn E.; Johnson, James H.; Nack, Christopher C.

2018-01-01

In many lotic systems, drastic declines in freshwater bivalve populations, including fingernail clams (Sphaeriidae), have created concerns about biodiversity and future ecosystem services. We examined the local occurrence of the historically common fingernail clam, Sphaerium striatinum, in a central New York stream. We sampled the density of sphaeriids and measured the associated habitat variables (substrate, depth, water flow) to test within-stream multivariate benthic microhabitat association. Size distribution, density, and diel feeding periodicity were measured as focal aspects of fingernail clam biology and ecology. S. striatinum tended to be found in microhabitats that had harder substrates and faster flow. The Labrador Creek fingernail clam local population had positive indicators (size distribution, density). There was significant diel periodicity in feeding behavior. The clams fed most actively during the 0400–0800 h periods. This kind of behavioral periodicity can indicate a significant ecological interaction between predators and bivalve prey. Increased understanding of the behavioral ecology of small native freshwater bivalves in an unimpacted headwater stream is a fundamental building block for development of overall ecological conservation goals for freshwater bivalves and their lotic habitats.

Effect of TBT on Ruditapes decussatus juveniles.

Science.gov (United States)

Coelho, M R; Langston, W J; Bebianno, M J

2006-06-01

The effects of sublethal concentrations of tributyltin (TBT) on growth of juvenile clams Ruditapes decussatus were determined during exposure to TBT concentrations of 50, 100 and 250 ng l(-1) (as Sn) for a period up to two years. Length and weight of clams increased continuously in all treatments throughout the experimental period, and, overall, rates were not significantly influenced by TBT exposure, although final length and weight were inversely related to increasing TBT concentration. Juvenile R. decussatus therefore appear to be less sensitive to TBT than larval stages. Some juveniles exposed to TBT developed abnormal shell growth, laterally, changing the typical flattened shape of clams into a more "rounded" form. This characteristic was more visible in the anterior margins of valves than posteriorly, and mainly observed in clams exposed to TBT at 50 ng l(-1) (as Sn).

Distribution of myogenic progenitor cells and myonuclei is altered in women with vs. those without chronically painful trapezius muscle

DEFF Research Database (Denmark)

Mackey, Abigail; Andersen, Lars L; Frandsen, Ulrik

2010-01-01

It is hypothesized that repeated recruitment of low-threshold motor units is an underlying cause of chronic pain in trapezius myalgia. This study investigated the distribution of satellite cells (SCs), myonuclei, and macrophages in muscle biopsies from the trapezius muscle of 42 women performing...... repetitive manual work, diagnosed with trapezius myalgia (MYA; 44 ± 8 yr; mean ± SD) and 20 matched healthy controls (CON; 45 ± 9 yr). Our hypothesis was that muscle of MYA, in particular type I fibers, would demonstrate higher numbers of SCs, myonuclei, and macrophages compared with CON. SCs were identified...... was not in line with our hypothesis and suggests that the elevated SC content of MYA was not due to heightened inflammatory cell contents, but rather to provide new myonuclei. The findings of greater numbers of SCs in type I fibers of muscle subjected to repeated low-intensity work support our hypothesis...

Annual harvests of Corbicula populations prevent clogging of nuclear reactor heat exchangers

International Nuclear Information System (INIS)

Harvey, R.S.

1983-01-01

An annual program for removal of millions of Corbicula from upstream cooling water basins has prevented reclogging of nuclear reactor heat exchanger distributor plates at the Savannah River Plant during the past seven years. There are nine 32-megaliter basins in the three operating reactor areas where some settling of particulates occurs before cooling water is passed through screens in route to heat exchangers. Annual cleanings keep silt/clam substrate levels low and clam sizes small. Data are presented on the size/age distribution for clams recolonizing basins between cleanings

FEEDING RATES OF THE MUD SHRIMP UPOGEBIA PUGETTENSIS AND IMPLICATIONS FOR ESTUARINE PHYTOPLANKTON ABUNDANCE

Science.gov (United States)

The burrowing shrimp Upogebia pugettensis is an abundant inhabitant of Pacific Northwest bays and estuaries where it lives commensally with the clam Cryptomya californica. Suspension-feeding activities of the shrimp and its commensal clam, as well as particle settlement within t...

CRISTISPIRA IN NORTH AMERICAN SHELLFISH. A NOTE ON A SPIRILLUM FOUND IN OYSTERS.

Science.gov (United States)

Noguchi, H

1921-08-31

Ten varieties of North American shellfish were examined for the occurrence of Cristispira in their styles. A cristispira was found in various numbers in Ostrea virginiana, Venus mercenaria, and Modiola modiolus, but none in Ensis americana, Mya arenaria, Mactra solidissima, Pecten irradians, Mytilus edulis, Fulgur canaliculatus, or Nassa obsoleta. Of 298 oysters, only 128 showed the crystalline styles, in which cristispiras were present in 99. Active cristispiras were found in 59 styles only and degenerated forms in the remaining 40. In 110 clams (Venus mercenaria) 70 styles were found, and only 8 of these contained cristispiras; 5 yielded active and the other 3 degenerated cristispiras. In 97 modiolas there were 73 styles, only 4 of which contained cristispiras. The physical properties of the crystalline styles of these shellfish varied considerably. The styles of the oysters were moderately soft, and when exposed to the air or mixed with sea water they underwent liquefaction, forming a clear, viscid material. The styles from clams and modiolas were opaque and were more firm, not easily crushed even in a mortar. The styles of the scallops were the most solid of all the styles examined. It happened that the softer the styles, the more frequent was the occurrence of the cristispira; in fact, no cristispira was detected in styles other than those of oysters, clams, and modiolas, of which oysters had the softest styles and the largest percentage of cristispira invasion. The following observations were made regarding the structure of the cristispira found in oysters. The body is a long, flexible cylinder, with blunt extremities, towards which the diameter gradually diminishes. In motion the body rapidly stretches and contracts, forming in the contracted state several serpentine undulations. A membranous appendage (Gross' crista) winds about the body throughout its entire length. The inner margin is in connection with the body, the outer margin is free and is distinctly

Flavonoid concentrations in three grass species and a sedge grown in the field and under controlled environment conditions in response to enhanced UV-B radiation.

NARCIS (Netherlands)

van de Staaij, J.W.M.; Bakker, N.; Oosthoek, A.; Broekman, R.A.; van Beem, A.P.; Stroetenga, M.J.; Aerts, R.; Rozema, J.

2002-01-01

An investigation was carried out to find whether enhanced levels of UV-B radiation induce increased concentrations of flavonoids in the leaves of the grass species Deschampsia antarctica, Deschampsia borealis and Calamagrostis epigeios and the sedge Carex arenaria. Whether the enhanced levels of

Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata

International Nuclear Information System (INIS)

Sellami, Badreddine; Khazri, Abdelhafidh; Mezni, Amine; Louati, Héla; Dellali, Mohamed; Aissa, Patricia; Mahmoudi, Ezzeddine; Beyrem, Hamouda; Sheehan, David

2015-01-01

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

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)

Kalman, J.; Smith, B.D.; Bury, N.R.; Rainbow, P.S.

2014-01-01

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

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.

Assessing toxicant effects in a complex estuary--A case study of effects of silver on reproduction in the bivalve, Potamocurbula amurensis, in San Francisco Bay

Science.gov (United States)

Brown, Cynthia L.; Parchaso, Francis; Thompson, Janet K.; Luoma, Samuel N.

2003-01-01

Contaminant exposures in natural systems can be highly variable. This variability is superimposed upon cyclic variability in biological processes. Together, these factors can confound determination of contaminant effects. Long term, multidisciplined studies with high frequency sampling can be effective in overcoming such obstacles. While studying trace metal contamination in the tissues of the clam, Potamocorbula amurensis, in the northern reach of San Francisco Bay, an episode of high Ag concentrations was identified (maximum of 5.5 µg g−1) at two mid-estuary sites. High concentrations were not seen in clams up-estuary (maximum of 1.92 µg g−1) from these sites and were reduced down-estuary (maximum of 2.67 µg g−1). Silver is not common naturally in the environment, so its elevated presence is usually indicative of anthropogenic influences such as municipal and industrial discharge. Monthly sampling of reproductive status of clams characterized the reproductive cycle and differences in the patterns of reproductive activity that corresponded to changes in Ag tissue concentrations. The proportion of reproductive clams was less than 60% during periods when tissue concentrations were high (generally >2 µg g−1). When tissue concentrations of Ag decreased (≤1 µg g−1), the proportion of reproductive clams was 80 to 100%. A comparison between the annual proportion of reproductive clams and annual Ag tissue concentrations showed a significant negative correlation. No other measured environmental variables were correlated with reproductive impairment. The weight-of-evidence approach strongly supports a cause and effect relationship between Ag contamination and reduced reproductive activity in P. amurensis.

Assessing toxicant effects in a complex estuary: A case study of effects of silver on reproduction in the bivalve, Potamocorbula amurensis, in San Francisco Bay

Science.gov (United States)

Brown, C.L.; Parchaso, F.; Thompson, J.K.; Luoma, S.N.

2003-01-01

Contaminant exposures in natural systems can be highly variable. This variability is superimposed upon cyclic variability in biological processes. Together, these factors can confound determination of contaminant effects. Long term, multidisciplined studies with high frequency sampling can be effective in overcoming such obstacles. While studying trace metal contamination in the tissues of the clam, Potamocorbula amurensis, in the northern reach of San Francisco Bay, an episode of high Ag concentrations was identified (maximum of 5.5 ??g g-1) at two mid-estuary sites. High concentrations were not seen in clams up-estuary (maximum of 1.92 ??g g-1) from these sites and were reduced down-estuary (maximum of 2.67 ??g g-1). Silver is not common naturally in the environment, so its elevated presence is usually indicative of anthropogenic influences such as municipal and industrial discharge. Monthly sampling of reproductive status of clams characterized the reproductive cycle and differences in the patterns of reproductive activity that corresponded to changes in Ag tissue concentrations. The proportion of reproductive clams was less than 60% during periods when tissue concentrations were high (generally >2 ??g g-1). When tissue concentrations of Ag decreased (???1 ??g g-1), the proportion of reproductive clams was 80 to 100%. A comparison between the annual proportion of reproductive clams and annual Ag tissue concentrations showed a significant negative correlation. No other measured environmental variables were correlated with reproductive impairment. The weight-of-evidence approach strongly supports a cause and effect relationship between Ag contamination and reduced reproductive activity in P. amurensis.

Biofiltration using C. fluminea for E.coli removal from water: Comparison with ozonation and photocatalytic oxidation.

Science.gov (United States)

Gomes, João F; Lopes, Ana; Gonçalves, Daniel; Luxo, Cristina; Gmurek, Marta; Costa, Raquel; Quinta-Ferreira, Rosa M; Martins, Rui C; Matos, Ana

2018-06-06

Corbicula fluminea, an Asian clam, is one of the worst invasive species in Europe that can survive in very adverse environmental conditions. Despite its negative impacts, the species also has the capacity to bioaccumulate heavy metals, contaminants and can be exploited for wastewater treatment purposes. The capacity of the Asian clam to remove Escherichia coli, used as fecal contamination indicator, was analyzed. Conventional wastewater treatment plants are not suitable to remove bacteria, thus resulting in treated municipal wastewater with high bacterial loads. E. coli clearance rate was analyzed as function of the number of clams. The bivalves can remove bacteria until concentrations below the detection limit in about 6 h. The adsorption on the clam shells' and bioaccumulation on the soft tissues were also analyzed. The depuration of clams along 48 h were analyzed revealing that no bacteria was detected in the water. Thus, these results suggest that Asian clam can bioprocess E. coli. On the other hand, results obtained by this methodology were compared with ozonation and photocatalytic oxidation using TiO 2 , Ag, Au, Pd-TiO 2 . In all treatments it was possible to achieve concentrations of E. coli below the detection limit. However, photocatalytic oxidation demands about 4700 folds more energy than ozonation, besides the costs associated with catalysts. Comparing complexity of ozonation with biofiltration, this study suggests that application of biofiltration using C. fluminea can be a suitable solution to minimize the presence of bacteria in wastewater, reducing environmental and economic impacts. Copyright © 2018 Elsevier Ltd. All rights reserved.

Paleomagnetic dates of hominid remains from Yuanmou, China, and other Asian sites.

Science.gov (United States)

Hyodo, Masayuki; Nakaya, Hideo; Urabe, Atsushi; Saegusa, Haruo; Shunrong, Xue; Jiyun, Yin; Xuepin, Ji

2002-07-01

Two hominid upper central incisors found in the Yuanmou Basin in southwest China in 1965 have affinities with Homo erectus fossils from Zhoukoudian, but exhibit primitive features. The Yuanmou hominid remains are alleged to be coeval with or older than African specimens dated at about 1.8 m.y.a. Recent age refinements of geomagnetic short reversal events and excursions permit assigning the Yuanmou hominid-bearing bed to the early Brunhes chron (about 0.7 m.y.a.). Magnetochronological assessments confirm that the Lantian calotte which has been dated to about 1.2 m.y.a., is the oldest reliable evidence for the emergence of Homo in eastern Asia as well as China, and that hominid fossils from Sangiran and Mojokerto, Java, do not exceed 1.1 Ma in age. These results refute the view that the genus Homo migrated into eastern Asia in the late Pliocene or the earliest Pleistocene. Copyright 2002 Elsevier Science Ltd. All rights reserved.

Timing of the evolutionary history of Corallinaceae (Corallinales, Rhodophyta).

Science.gov (United States)

Rösler, Anja; Perfectti, Francisco; Peña, Viviana; Aguirre, Julio; Braga, Juan Carlos

2017-06-01

The temporal dimension of the most recent Corallinaceae (order Corallinales) phylogeny was presented here, based on first occurrence time estimates from the fossil record. Calibration of the molecular clock of the genetic marker SSU entailed a separation of Corallinales from Hapalidiales in the Albian (Early Cretaceous ~105 mya). Neither the calibration nor the fossil record resolved the succession of appearance of the first three emerging subfamilies: Mastophoroideae, Corallinoideae, and Neogoniolithoideae. The development of the tetra/bisporangial conceptacle roofs by filaments surrounding and interspersed among the sporangial initials was an evolutionary novelty emerging at the Cretaceous-Paleogene boundary (~66 mya). This novelty was shared by the subfamilies Hydrolithoideae, Metagoniolithoideae, and Lithophylloideae, which diverged in the early Paleogene. Subclades within the Metagoniolithoideae and Lithophylloideae diversified in the late Oligocene-middle Miocene (~28-12 mya). The most common reef corallinaceans (Hydrolithon, Porolithon, Harveylithon, "Pneophyllum" conicum, and subclades within Lithophylloideae) appeared in this interval in the Indo-Australian Archipelago. © 2017 Phycological Society of America.

454-sequencing reveals stochastic local reassembly and high disturbance tolerance within arbuscular mycorrhizal fungal communities

DEFF Research Database (Denmark)

Lekberg, Karin Ylva Margareta; Schnoor, Tim; Kjøller, Rasmus

2012-01-01

unpredictable, with approximately 40%of all sequences within a sample belonging to a single OTU of varying identity. The distribution of two plant species that are often poorly colonized by AMfungi (Dianthus deltoides and Carex arenaria) correlated significantly with the OTU composition, which may indicate...

Direct and indirect effects of different types of microplastics on freshwater prey (Corbicula fluminea) and their predator (Acipenser transmontanus)

Science.gov (United States)

Parnis, J. Mark; Browne, Mark A.; Serrato, Sebastian; Reiner, Eric J.; Robson, Matthew; Young, Thomas; Diamond, Miriam L.; Teh, Swee J.

2017-01-01

We examined whether environmentally relevant concentrations of different types of microplastics, with or without PCBs, directly affect freshwater prey and indirectly affect their predators. Asian clams (Corbicula fluminea) were exposed to environmentally relevant concentrations of polyethylene terephthalate (PET), polyethylene, polyvinylchloride (PVC) or polystyrene with and without polychlorinated biphenyls (PCBs) for 28 days. Their predators, white sturgeon (Acipenser transmontanus), were exposed to clams from each treatment for 28 days. In both species, we examined bioaccumulation of PCBs and effects (i.e., immunohistochemistry, histology, behavior, condition, mortality) across several levels of biological organization. PCBs were not detected in prey or predator, and thus differences in bioaccumulation of PCBs among polymers and biomagnification in predators could not be measured. One of the main objectives of this study was to test the hypothesis that bioaccumulation of PCBs would differ among polymer types. Because we could not answer this question experimentally, a bioaccumulation model was run and predicted that concentrations of PCBs in clams exposed to polyethylene and polystyrene would be greater than PET and PVC. Observed effects, although subtle, seemed to be due to microplastics rather than PCBs alone. For example, histopathology showed tubular dilation in clams exposed to microplastics with PCBs, with only mild effects in clams exposed to PCBs alone. PMID:29108004

Direct and indirect effects of different types of microplastics on freshwater prey (Corbicula fluminea and their predator (Acipenser transmontanus.

Directory of Open Access Journals (Sweden)

Chelsea M Rochman

Full Text Available We examined whether environmentally relevant concentrations of different types of microplastics, with or without PCBs, directly affect freshwater prey and indirectly affect their predators. Asian clams (Corbicula fluminea were exposed to environmentally relevant concentrations of polyethylene terephthalate (PET, polyethylene, polyvinylchloride (PVC or polystyrene with and without polychlorinated biphenyls (PCBs for 28 days. Their predators, white sturgeon (Acipenser transmontanus, were exposed to clams from each treatment for 28 days. In both species, we examined bioaccumulation of PCBs and effects (i.e., immunohistochemistry, histology, behavior, condition, mortality across several levels of biological organization. PCBs were not detected in prey or predator, and thus differences in bioaccumulation of PCBs among polymers and biomagnification in predators could not be measured. One of the main objectives of this study was to test the hypothesis that bioaccumulation of PCBs would differ among polymer types. Because we could not answer this question experimentally, a bioaccumulation model was run and predicted that concentrations of PCBs in clams exposed to polyethylene and polystyrene would be greater than PET and PVC. Observed effects, although subtle, seemed to be due to microplastics rather than PCBs alone. For example, histopathology showed tubular dilation in clams exposed to microplastics with PCBs, with only mild effects in clams exposed to PCBs alone.

Polycyclic aromatic hydrocarbons bioaccessibility in seafood: Culinary practices effects on dietary exposure.

Science.gov (United States)

Dos Santos Fogaça, Fabíola Helena; Soares, Cristina; Oliveira, Marta; Alves, Ricardo N; Maulvault, Ana L; Barbosa, Vera L; Anacleto, Patrícia; Magalhães, João Avelar; Bandarra, Narcisa M; Ramalhosa, Maria João; Morais, Simone; Marques, António

2018-07-01

This work aimed to determine the effect of culinary practices on the contamination level and bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in seafood. The selected farmed seafood species (marine shrimp, clams and seaweed) were commercially available in Portugal. The mean concentrations of PAHs varied between 0.23 and 51.8 µg kg -1 , with the lowest value being observed in raw shrimp and the highest in dried seaweed. The number of compounds detected in seaweed and clams (naphthalene, acenaphthene, fluorene, phenanthrene, benzo(b)fluoranthene and benzo(j)fluoranthene) were higher than in shrimp (fluorene and pyrene). Among the PAHs measured, fluorene was the predominant one. There was a significant interaction effect between species and culinary treatment (p < 0.05), thus boiled and dried seaweed samples presented the lowest and the highest levels of fluorene (0.13 and 1.8 µg kg -1 ), respectively. The daily intake of PAHs decreased with bioaccessibility, varying from 22% for benzo(k)fluoranthene (in raw clam) to 84% for phenanthrene (in steamed clam). According to the potency equivalent concentrations, screening values and bioaccessibility of PAHs, the consumption of marine shrimp, clam and seaweed is considered as safe for consumers. Copyright © 2018 Elsevier Inc. All rights reserved.

CLIP-seq analysis of multi-mapped reads discovers novel functional RNA regulatory sites in the human transcriptome.

Science.gov (United States)

Zhang, Zijun; Xing, Yi

2017-09-19

Crosslinking or RNA immunoprecipitation followed by sequencing (CLIP-seq or RIP-seq) allows transcriptome-wide discovery of RNA regulatory sites. As CLIP-seq/RIP-seq reads are short, existing computational tools focus on uniquely mapped reads, while reads mapped to multiple loci are discarded. We present CLAM (CLIP-seq Analysis of Multi-mapped reads). CLAM uses an expectation-maximization algorithm to assign multi-mapped reads and calls peaks combining uniquely and multi-mapped reads. To demonstrate the utility of CLAM, we applied it to a wide range of public CLIP-seq/RIP-seq datasets involving numerous splicing factors, microRNAs and m6A RNA methylation. CLAM recovered a large number of novel RNA regulatory sites inaccessible by uniquely mapped reads. The functional significance of these sites was demonstrated by consensus motif patterns and association with alternative splicing (splicing factors), transcript abundance (AGO2) and mRNA half-life (m6A). CLAM provides a useful tool to discover novel protein-RNA interactions and RNA modification sites from CLIP-seq and RIP-seq data, and reveals the significant contribution of repetitive elements to the RNA regulatory landscape of the human transcriptome. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Analysis of Fusarium causing dermal toxicosis in marram grass planters

NARCIS (Netherlands)

Snijders, CHA; Samson, RA; Hoekstra, ES; Ouellet, T; Miller, JD; deRooijvanderGoes, PCEM; Baar, AJM; Dubois, AEJ; Kauffman, HF

1996-01-01

In the European coastal dunes, marram grass (Ammophila arenaria) is planted in order to control sand erosion. In the years 1986 to 1991, workers on the Wadden islands in the Netherlands planting marram grass showed lesions of skin and mucous membranes, suggesting a toxic reaction. Fusarium culmorum

Over de twee ondersoorten van Festuca rubra L. in Nederland

NARCIS (Netherlands)

Wilde-Duyfjes, de B.E.E.

1973-01-01

A survey is given of the literature concerning Festuca rubra L. s.l. as it occurs along the European coasts. For the Netherlands two subspecies are distinguished, viz. subsp. rubra and subsp. arenaria (Osb.) Richt. This is in accordance with the findings of FREIJSEN & HEERES (1972).

Correlates of hyperdiversity in southern African ice plants (Aizoaceae).

Science.gov (United States)

Valente, Luis M; Britton, Adam W; Powell, Martyn P; Papadopulos, Alexander S T; Burgoyne, Priscilla M; Savolainen, Vincent

2014-01-01

The exceptionally high plant diversity of the Greater Cape Floristic Region (GCFR) comprises a combination of ancient lineages and young radiations. A previous phylogenetic study of Aizoaceae subfamily Ruschioideae dated the radiation of this clade of > 1500 species in the GCFR to 3.8-8.7 Mya, establishing it as a flagship example of a diversification event triggered by the onset of a summer-arid climate in the region. However, a more recent analysis found an older age for the Ruschioideae lineage (17 Mya), suggesting that the group may in fact have originated much before the aridification of the region 10-15 Mya. Here, we reassess the tempo of radiation of ice plants by using the most complete generic-level phylogenetic tree for Aizoaceae to date, a revised calibration age and a new dating method. Our estimates of the age of the clade are even younger than initially thought (stem age 1.13-6.49 Mya), supporting the hypothesis that the radiation post-dates the establishment of an arid environment in the GCFR and firmly placing the radiation among the fastest in angiosperms (diversification rate of 4.4 species per million years). We also statistically examine environmental and morphological correlates of richness in ice plants and find that diversity is strongly linked with precipitation, temperature, topographic complexity and the evolution of highly succulent leaves and wide-band tracheids.

50 CFR 648.77 - Framework adjustments to management measures.

Science.gov (United States)

2010-10-01

... Management Measures for the Atlantic Surf Clam and Ocean Quahog Fisheries § 648.77 Framework adjustments to... add or adjust management measures within the Atlantic Surf Clam and Ocean Quahog FMP if it finds that... stratification, reports, and/or industry-funded observers or observer set-aside programs). (2) Council...

Certification of Trace Elements and Methyl Mercury Mass Fractions in IAEA-461 Clam (Gafrarium tumidum) Sample

International Nuclear Information System (INIS)

2016-01-01

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

The greatest step in vertebrate history: a paleobiological review of the fish-tetrapod transition.

Science.gov (United States)

Long, John A; Gordon, Malcolm S

2004-01-01

Recent discoveries of previously unknown fossil forms have dramatically transformed understanding of many aspects of the fish-tetrapod transition. Newer paleobiological approaches have also contributed to changed views of which animals were involved and when, where, and how the transition occurred. This review summarizes major advances made and reevaluates alternative interpretations of important parts of the evidence. We begin with general issues and concepts, including limitations of the Paleozoic fossil record. We summarize important features of paleoclimates, paleoenvironments, paleobiogeography, and taphonomy. We then review the history of Devonian tetrapods and their closest stem group ancestors within the sarcopterygian fishes. It is now widely accepted that the first tetrapods arose from advanced tetrapodomorph stock (the elpistostegalids) in the Late Devonian, probably in Euramerica. However, truly terrestrial forms did not emerge until much later, in geographically far-flung regions, in the Lower Carboniferous. The complete transition occurred over about 25 million years; definitive emergences onto land took place during the most recent 5 million years. The sequence of character acquisition during the transition can be seen as a five-step process involving: (1) higher osteichthyan (tetrapodomorph) diversification in the Middle Devonian (beginning about 380 million years ago [mya]), (2) the emergence of "prototetrapods" (e.g., Elginerpeton) in the Frasnian stage (about 372 mya), (3) the appearance of aquatic tetrapods (e.g., Acanthostega) sometime in the early to mid-Famennian (about 360 mya), (4) the appearance of "eutetrapods" (e.g., Tulerpeton) at the very end of the Devonian period (about 358 mya), and (5) the first truly terrestrial tetrapods (e.g., Pederpes) in the Lower Carboniferous (about 340 mya). We discuss each of these steps with respect to inferred functional utility of acquired character sets. Dissociated heterochrony is seen as the most

Selection of vaccine strains for serotype O foot-and-mouth disease viruses (2007-2012) circulating in Southeast Asia, East Asia and Far East.

Science.gov (United States)

Mahapatra, Mana; Upadhyaya, Sasmita; Aviso, Sharie; Babu, Aravindh; Hutchings, Geoff; Parida, Satya

2017-12-18

Foot-and-mouth disease (FMD) is endemic in Southeast Asia (SEA) and East Asia with circulation of multiple serotypes and multiple genotypes within each serotype of the virus. Although countries like Japan and South Korea in the Far East were free of FMD, in 2010 FMD serotype O (O/Mya-98) outbreaks were recorded and since then South Korea has experienced several FMD outbreaks despite regular vaccination. In this study a total of 85 serotype O FMD viruses (FMDV) isolated from 2007 to 2012 from SEA, East Asia and Far East were characterized by virus neutralisation tests using antisera to four existing (O/HKN/6/83, O/IND/R2/75, O/SKR/2010 and O/PanAsia-2) and one putative (O/MYA/2009) vaccine strains, and by full capsid sequencing. Serological studies revealed broad cross-reactivity with the vaccine strains; O/PanAsia-2 exhibited a good match with 95.3%, O/HKN/6/83 with 91.8%, O/IND/R2/75 with 80%, and the putative strain O/MYA/2009 with 89.4% isolates employed in this study. Similarly O/PanAsia-2 and O/IND/R2/75 vaccines showed a good match with all eight viruses belonging to O-Ind-2001d sublineage whereas the vaccines of O/Mya-98 lineage, O/MYA/2009 and O/SKR/2010 exhibited the lowest match indicating their unsuitability to protect infections from O-Ind-2001d viruses. A Bayesian analysis of the capsid sequence data indicated these circulating viruses (n = 85) to be of either SEA or Middle East-South Asian (ME-SA) topotype. The ME-SA topotype viruses were mainly detected in Lao PDR, Vietnam, Myanmar and Thailand reflecting the trade links with the Indian subcontinent, and also within the SEA countries. Implications of these results in the context of FMD control in SEA and East Asian countries are discussed. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

AN 11-YEAR FIELD STUDY WITH PASTEURIA PENETRANS: LESSONS LEARNED THE HARD WAY.

Science.gov (United States)

Beginning in 1998, a bioassay using second-stage juveniles (J2) from a greenhouse (GH) population of the root-knot nematode Meloidogyne arenaria (Ma) was used to monitor endospore densities of the bacterium Pasteuria penetrans, which was parasitizing Ma in a long-term rotation study (begun in 1991)....

Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province

Directory of Open Access Journals (Sweden)

Zoltán Pécskay

2011-08-01

Full Text Available The dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their geochemistry is similar to tholeiites belonging to a bimodal suite defined as the High-Arctic Large Igneous Province (HALIP. K–Ar dating of numerous dolerites sampled from many locations across Svalbard define a narrow time span of this magmatism from 125.5±3.6 to 78.3±2.6 Mya. Discrete peaks of intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to (1 breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; (2 magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and (3 continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya.

Novel genomes and genome constitutions identified by GISH and 5S rDNA and knotted1 genomic sequences in the genus Setaria.

Science.gov (United States)

Zhao, Meicheng; Zhi, Hui; Doust, Andrew N; Li, Wei; Wang, Yongfang; Li, Haiquan; Jia, Guanqing; Wang, Yongqiang; Zhang, Ning; Diao, Xianmin

2013-04-11

The Setaria genus is increasingly of interest to researchers, as its two species, S. viridis and S. italica, are being developed as models for understanding C4 photosynthesis and plant functional genomics. The genome constitution of Setaria species has been studied in the diploid species S. viridis, S. adhaerans and S. grisebachii, where three genomes A, B and C were identified respectively. Two allotetraploid species, S. verticillata and S. faberi, were found to have AABB genomes, and one autotetraploid species, S. queenslandica, with an AAAA genome, has also been identified. The genomes and genome constitutions of most other species remain unknown, even though it was thought there are approximately 125 species in the genus distributed world-wide. GISH was performed to detect the genome constitutions of Eurasia species of S. glauca, S. plicata, and S. arenaria, with the known A, B and C genomes as probes. No or very poor hybridization signal was detected indicating that their genomes are different from those already described. GISH was also performed reciprocally between S. glauca, S. plicata, and S. arenaria genomes, but no hybridization signals between each other were found. The two sets of chromosomes of S. lachnea both hybridized strong signals with only the known C genome of S. grisebachii. Chromosomes of Qing 9, an accession formerly considered as S. viridis, hybridized strong signal only to B genome of S. adherans. Phylogenetic trees constructed with 5S rDNA and knotted1 markers, clearly classify the samples in this study into six clusters, matching the GISH results, and suggesting that the F genome of S. arenaria is basal in the genus. Three novel genomes in the Setaria genus were identified and designated as genome D (S. glauca), E (S. plicata) and F (S. arenaria) respectively. The genome constitution of tetraploid S. lachnea is putatively CCC'C'. Qing 9 is a B genome species indigenous to China and is hypothesized to be a newly identified species. The

Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods.

Science.gov (United States)

Coes, Alissa L; Paretti, Nicholas V; Foreman, William T; Iverson, Jana L; Alvarez, David A

2014-03-01

A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19-23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method. Published by Elsevier B.V.

Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods

Science.gov (United States)

Coes, Alissa L.; Paretti, Nicholas V.; Foreman, William T.; Iverson, Jana L.; Alvarez, David A.

2014-01-01

A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19–23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method.

Prevalence of human pathogenic enteric viruses in bivalve molluscan shellfish and cultured shrimp in south west coast of India.

Science.gov (United States)

Umesha, Kanasinakatte R; Bhavani, Naniah C; Venugopal, Moleyur N; Karunasagar, Indrani; Krohne, Georg; Karunasagar, Iddya

2008-03-20

The prevalence of human enteric viruses in bivalve molluscan shellfish and shrimp collected off the south west coast of India was studied to assess the extent of fecal pollution of coastal environment. Out of 194 samples analyzed, 37% of oyster, 46% of clam and 15% of shrimp samples were positive for enteroviruses (EV). Adenoviruses (ADV) were detected in 17% of oyster and 27% of clam samples. However, other enteric viruses such as noroviruses (NoV) and hepatitis A virus (HAV) were not detected in any of the samples. High prevalence of EV and ADV was noticed between May to December. Thirty four percent of oyster and 49% of clam samples showed fecal coliform values higher than the limit. MS-2 phage was detected in 57% of oyster and 73% of clam samples. The presence of MS-2 phage and human enteric viruses showed association while fecal coliforms and enteric viruses showed no association. However, 17 samples, which were positive for enteric viruses (EV and ADV), were negative for MS-2 phage.

Paired serologic and polymerase chain reaction analyses of avian influenza prevalence in Alaskan shorebirds

Science.gov (United States)

Pearce, John M.; Ruthrauff, Daniel R.; Hall, Jeffrey S.

2012-01-01

Surveillance has revealed low prevalence of avian influenza viruses (AIV) in shorebirds except Ruddy Turnstones (Arenaria interpres) on the North American Atlantic coast. Similarly, of five species of shorebirds surveyed in Alaska in 2010, Ruddy Turnstones had the highest AIV antibody prevalence; prevalence of AIV RNA was low or zero.

Welke soort rood zwenkgras (Festuca rubra s.l.) komt voor in de jonge kustduinen van Voorne en die van overig Nederland?

NARCIS (Netherlands)

Freijsen, A.H.J.; Heeres, Els

1972-01-01

By common consent two taxa of Festuca rubra s.l. occur in sandy outer dunes along the N.W. European coasts. Festuca juncifolia St. Amans is considered to be a typical grass of Ammophiladunes. Festuca rubra subsp. arenaria (Osb.) Richt. could be found on almost fixed dunes. The only usable character

Ecological effects of the harvest phase of geoduck clam (Panopea generosa Gould, 1850) aquaculture on infaunal communities in southern Puget Sound, Washington USA.

Science.gov (United States)

VanBlaricom, Glenn R.; Eccles, Jennifer L.; Olden, Julian D.; Mcdonald, P. Sean

2015-01-01

Intertidal aquaculture for geoducks (Panopea generosa Gould, 1850) is expanding in southern Puget Sound, Washington, where gently sloping sandy beaches are used for field culture. Geoduck aquaculture contributes significantly to the regional economy, but has become controversial because of a range of unresolved questions involving potential biological impacts on marine ecosystems. From 2008 through 2012, the authors used a “before-after-control-impact” experimental design, emphasizing spatial scales comparable with those used by geoduck culturists to evaluate the effects of harvesting market-ready geoducks on associated benthic infaunal communities. Infauna were sampled at three different study locations in southern Puget Sound at monthly intervals before, during, and after harvests of clams, and along extralimital transects extending away from the edges of cultured plots to assess the effects of harvest activities in adjacent uncultured habitat. Using multivariate statistical approaches, strong seasonal and spatial signals in patterns of abundance were found, but there was scant evidence of effects on the community structure associated with geoduck harvest disturbances within cultured plots. Likewise, no indications of significant “spillover” effects of harvest on uncultured habitat adjacent to cultured plots were noted. Complementary univariate approaches revealed little evidence of harvest effects on infaunal biodiversity and indications of modest effects on populations of individual infaunal taxa. Of 10 common taxa analyzed, only three showed evidence of reduced densities, although minor, after harvests whereas the remaining seven taxa indicated either neutral responses to harvest disturbances or increased abundance either during or in the months after harvest events. It is suggested that a relatively active natural disturbance regime, including both small-scale and large-scale events that occur with comparable intensity but more frequently than

A study on some trace elements in Chilean seafood

Energy Technology Data Exchange (ETDEWEB)

Gras, N; Munoz, L; Thieck, M; Hurtado, S [Comision Chilena de Energia Nuclear, Santiago (Chile). Lab. of Activation Analysis

1993-03-01

Levels of essential and toxic trace elements in six marine species greatly in demand in the international market (canned pink clams, razor clams, clams, king crab, sardines, and frozen albacore tuna fish) were studied. A special laboratory adequately equipped for handling and preparing biological materials, is described. The elements As, Br, Na, Se, Hg, Cr, Fe, Zn and Rb were determined by INAA, while copper and cadmium content were determined using RNAA. Significant differences were found on comparing the contents of some toxic elements in mollusk and other samples of marine food. Various certified reference materials (CRMs) of the IAEA, NIST and NIES were analyzed for quality assurance purposes. (author) 11 refs.; 1 fig.; 1 tab.

A study on some trace elements in Chilean seafood

International Nuclear Information System (INIS)

Gras, N.; Munoz, L.; Thieck, M.; Hurtado, S.

1993-01-01

Levels of essential and toxic trace elements in six marine species greatly in demand in the international market (canned pink clams, razor clams, clams, king crab, sardines, and frozen albacore tuna fish) were studied. A special laboratory adequately equipped for handling and preparing biological materials, is described. The elements As, Br, Na, Se, Hg, Cr, Fe, Zn and Rb were determined by INAA, while copper and cadmium content were determined using RNAA. Significant differences were found on comparing the contents of some toxic elements in mollusk and other samples of marine food. Various certified reference materials (CRMs) of the IAEA, NIST and NIES were analyzed for quality assurance purposes. (author) 11 refs.; 1 fig.; 1 tab

R and D status of China low activation martensitic steel

International Nuclear Information System (INIS)

Huang Qunying; Li Chunjing; Li Yanfen; Liu Shaojun; Wu Yican; Li Jiangang; Shan Yiyin; Yu Jinnan; Zhu Shengyun; Zhang Pinyuan; Yang Jianfeng; Han Fusheng; Kong Mingguang; Li Heqin; Muroga, T.; Nagasaka, T.

2007-01-01

The Reduced Activation Ferritic/Martensitic (RAFM) steel is considered as the primary candidate structural material for DEMO and the first fusion plant, and widely studied in the world. China low activation martensitic steel (CLAM) is being developed in Institute of Plasma Physics, Chinese Academy of Sciences, under wide collaboration with many other domestic and foreign institutes and universities. This paper summarized the main R and D progress on CLAM, which covered composition optimization of the CLAM, smelting and processing techniques, physical and mechanical property test and evaluation before and after irradiation, compatibility with liquid LiPb, welding techniques etc. Finally, further research and development, and the prospects on its application were stated. (authors)

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.

Mitochondrial DNA phylogeography of Semisulcospira libertina (Gastropoda: Cerithioidea: Pleuroceridae): implications the history of landform changes in Taiwan.

Science.gov (United States)

Hsu, Kui-Ching; Bor, Hor; Lin, Hung-Du; Kuo, Po-Hsun; Tan, Mian-Shin; Chiu, Yuh-Wen

2014-06-01

The mitochondrial DNA cytochrome c oxidase subunit I sequences from 95 specimens of Semisulcospira libertina in Taiwan were identified as two major phylogroups, exhibiting a southern and northern distribution, north of Formosa Bank and south of Miaoli Plateau. The genetic distance between these two phylogroups was 12.20%, and the distances within-phylogroups were 4.97 and 5.56%. According to a molecular clock of 1.56% per lineage per million years, the divergence time between these two major phylogroups was estimated at 4.94 million years ago (mya), with the two phylogroups forming at 3.64 and 3.75 mya, respectively. Moreover, the geological events have suggested that Taiwan Island emerged above sea level at 4-5 mya, and became its present shape at 2 mya. These results suggested that these two phylogroups might originate from two independent ancestral populations or divergent before colonizing Taiwan. Within South phylogroup, the initial colonization was hypothesized to be in Kaoping River (WT), followed by its northward. The high divergence between south- and north of WT River was influenced by the formation of the Kaoping foreland basins. Within North phylogroup, the colonization was from central sub-region through paleo-Miaoli Plateau to northern and northeastern sub-regions. This study showed that the landform changes might have shaped the genetic structure of S. libertina in concert. Apparently, two cryptic species or five different genetic stocks of S. libertina could be identified; these results are useful for the evaluation and conservation of S. libertina in Taiwan.

Genetic structure and historical diversification of catfish Brachyplatystoma platynemum (Siluriformes: Pimelodidae) in the Amazon basin with implications for its conservation

Science.gov (United States)

Ochoa, Luz Eneida; Pereira, Luiz Henrique G; Costa-Silva, Guilherme Jose; Roxo, Fábio F; Batista, Jacqueline S; Formiga, Kyara; Foresti, Fausto; Oliveira, Claudio

2015-01-01

Brachyplatystoma platynemum is a catfish species widely distributed in the Amazon basin. Despite being considered of little commercial interest, the decline in other fish populations has contributed to the increase in the catches of this species. The structure, population genetic variability, and evolutionary process that have driven the diversification of this species are presently unknown. Considering that, in order to better understand the genetic structure of this species, we analyzed individuals from seven locations of the Amazon basin using eight molecular markers: control region and cytochrome b mtDNA sequences, and a set of six nuclear microsatellite loci. The results show high levels of haplotype diversity and point to the occurrence of two structured populations (Amazon River and the Madeira River) with high values for FST. Divergence time estimates based on mtDNA indicated that these populations diverged about 1.0 Mya (0.2–2.5 Mya 95% HPD) using cytochrome b and 1.4 Mya (0.2–2.7 Mya 95% HPD) using control region. During that time, the influence of climate changes and hydrological events such as sea level oscillations and drainage isolation as a result of geological processes in the Pleistocene may have contributed to the current structure of B. platynemum populations, as well as of differences in water chemistry in Madeira River. The strong genetic structure and the time of genetic divergence estimated for the groups may indicate the existence of strong structure populations of B. platynemum in the Amazon basin. PMID:26045952

NOAA Surveys; Stabalizing Economy and Ecology on The U.S. Coast

Science.gov (United States)

Hylton, L. L.

2008-12-01

NOAA TEACHER AT SEA: LISHA LANDER HYLTON ONBOARD NOAA SHIP: DELAWARE II JUNE 29TH -JULY 11TH, 2008 MISSION: The mission of my trip with NOAA was to provide me (a teacher of third grade students) an extraordinary opportunity to take part in genuine-world experiences being conducted by NOAA in order for me to achieve a clearer insight into our ocean planet and a superior perceptive of NOAA-related careers. With the knowledge that I obtained on-board THE DELAWAREII - I am now able to teach the lesson plans created on my field study to my students, giving them insight as to how much power they have on their lives and this world we live in. My students are able to play a part in maritime activities as we study together, valuing the work and expertise that is required to sustain oceanic and atmospheric research. The students' enthusiasm, inquisitiveness and yearning to learn is only heightened with the hands-on, motivational activities that I gained from my research with this NOAA team. As a Part of this NOAA team, on-board we conducted clam surveys at various stations along the northeastern coast of the United States. I learned that clams are a very important part of economy and ecology in this region. Surveying clams and other marine species was performed on my field study with NOAA for the purpose of conserving marine life. NOAA realizes the importance of the fishing industry and conducts fishery surveys in order to stabilize fishery industries without destroying the marine ecosystems completely. Clams play a very important part in marine fishery; therefore these surveys are helping to maintain stability in the economy and ecology of The United States. By comparing past and present fishery surveys, our team made conclusions regarding the stability of these marine populations. After dredging, collecting, sorting, counting, measuring and weighing (clams with shells and shucked clam meat only) - the data was obtained and recorded then entered into computers filed under

Festuca rubra L. op Terschelling

NARCIS (Netherlands)

Freijsen, A.H.J.; Heusden, van H.T.A.

1965-01-01

The authors performed a preliminary survey of Festuca rubra L. s.l. in the outer dunes of the West- Frisian island of Terschelling. Starting-point was the question which dune-form of this grass — Festuca juncifolia St. Amans or Festuca rubra subvar. arenaria (Osb.) Hack. — was growing there. In the

Subcellular partitioning profiles and metallothionein levels in indigenous clams Moerella iridescens from a metal-impacted coastal bay

Energy Technology Data Exchange (ETDEWEB)

Wang, Zaosheng, E-mail: zswang@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China); State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Feng, Chenglian; Ye, Chun [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Youshao [State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301 (China); Yan, Changzhou, E-mail: czyan@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China); Li, Rui; Yan, Yijun; Chi, Qiaoqiao [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Boulevard, Xiamen 361021 (China)

2016-07-15

Highlights: • Subcellular partitioning profile of metals were investigated in biomonitor organism. • Cu, Zn and Cd levels in main fraction of HSP increase along accumulation gradients. • Despite MTs as the major binding pool, detoxification of Cd and Pb was incomplete. • Induced MTs were sequentially correlated with Cu, Zn and Cd levels in HSP fraction. • Intracellular metal fates highlighted the metabolic availability within organism. - Abstract: In this study, the effect of environmental metal exposure on the accumulation and subcellular distribution of metals in the digestive gland of clams with special emphasis on metallothioneins (MTs) was investigated. Specimens of indigenous Moerella iridescens were collected from different natural habitats in Maluan Bay (China), characterized by varying levels of metal contamination. The digestive glands were excised, homogenized and six subcellular fractions were separated by differential centrifugation procedures and analyzed for their Cu, Zn, Cd and Pb contents. MTs were quantified independently by spectrophotometric measurements of thiols. Site-specific differences were observed in total metal concentrations in the tissues, correlating well with variable environmental metal concentrations and reflecting the gradient trends in metal contamination. Concentrations of the non-essential Cd and Pb were more responsive to environmental exposure gradients than were tissue concentrations of the essential metals, Cu and Zn. Subcellular partitioning profiles for Cu, Zn and Cd were relatively similar, with the heat-stable protein (HSP) fraction as the dominant metal-binding compartment, whereas for Pb this fraction was much less important. The variations in proportions and concentrations of metals in this fraction along with the metal bioaccumulation gradients suggested that the induced MTs play an important role in metal homeostasis and detoxification for M. iridescens in the metal-contaminated bay. Nevertheless

Legal and Institutional Constraints on Aquaculture in Dredged Material Containment Areas

Science.gov (United States)

1993-04-01

SIZED CLAM PERMIT: It is unlawful to take, harvest, possess, sell, purchase, or import any hard clam of the genus Mercenaria of less than one inch in...S.W.2d 212, 216 (Tex.App. 19b?’ Bily v. Omni Equities . Inc., 731 S.W.2d 606, 611-12 (Tex.App. 1987); see also Tex. [Civ. Prac. & Rem.] Code Ann

Processes of physical change to the seabed and bivalve recruitment over a 10-year period following experimental hydraulic clam dredging on Banquereau, Scotian Shelf

Science.gov (United States)

Gilkinson, K.; King, E. L.; Li, M. Z.; Roddick, D.; Kenchington, E.; Han, G.

2015-01-01

A previous study on the effects of experimental hydraulic clam dredging on seabed habitat and commercial bivalve populations revealed a lack of recovery after a 3-year post-dredging period (1998-2001) on a deep (65-75 m) offshore sandy bank on the Scotian Shelf, Canada. Follow-up sidescan sonar surveys were carried out 5 and 10 years after dredging (2003, 2008) in order to identify long-term processes of seabed recovery. Grab sampling was carried out 10 years after dredging to identify post-dredging commercial bivalve recruitment. Changes in the seafloor, including dredge tracks, were documented with a series of 7 sidescan sonar surveys between 1998 and 2008. A sediment mobility model was constructed based on modeled tidal current and hindcast wave data over this time period to quantify natural seabed disturbance and interpret changes to the dredge tracks mapped by sidescan sonar surveys. The model indicated that tidal currents had minimal effect on sediment mobilization. The main driving force associated with re-working of surficial sediments as evidenced by deterioration of dredge tracks in sonograms was annual fall/winter storms. While the annual frequency of storms and associated wave heights was variable, the observations and sediment mobility calculations suggest that the most influential variable is the magnitude of individual large storms, specifically storms with a significant wave height of ∼11 m. These storms are capable of generating mobile sediment layers of 20-30 cm thickness, equivalent to the dredge blade cutting depth. It appears that, with minor exceptions, sediment properties have returned to pre-dredging conditions 10 years after dredging in this habitat. Based on known age-length relationships, the four commercial bivalve species showed very low recruitment at the experimental site over the 10-year post-dredging period. However, this is unlikely due to a dredging effect since a similar pattern was observed in non-dredged areas.

A phylogeographic investigation of the kelp genus Laminaria (Laminariales, Phaeophyceae), with emphasis on the South Atlantic Ocean.

Science.gov (United States)

Rothman, Mark D; Mattio, Lydiane; Anderson, Robert J; Bolton, John J

2017-08-01

The genus Laminaria has a wide distribution range compared with other kelp genera because it is found in both the North and the South Atlantic, on both sides of the North Pacific, as well as in the Mediterranean. Hypotheses behind this biogeographical pattern have been discussed by several authors but have not yet been fully evaluated with time-calibrated phylogenies. Based on the analysis of four molecular markers (ITS2, rbcL, atp8 and trnWI), our goal was to reassess the Laminaria species diversity in South Africa, assess its relationship with the other species distributed in the South Atlantic and reconstruct the historical biogeography of the genus. Our results confirm the occurrence of a single species, L. pallida, in southern Africa, and its sister relationship with the North Atlantic L. ochroleuca. Both species belonged to a clade containing the other South Atlantic species: L. abyssalis from Brazil, and the Mediterranean L. rodriguezii. Our time-calibrated phylogenies suggest that Laminaria originated in the northern Pacific around 25 mya, followed by at least two migration events through the Bering Strait after its opening (~5.32 mya). Today, the first is represented by L. solidungula in the Arctic, while the second gave rise to the rest of the Atlantic species. The colonization of the North Atlantic was followed by a gradual colonization southward along the west coast of Europe, into the Mediterranean (~2.07 mya) and two recent, but disconnected, migrations (~1.34 and 0.87 mya) across the equator, giving rise to L. abyssalis in Brazil and L. pallida in southern Africa, respectively. © 2017 Phycological Society of America.

New Eocene Coleoid (Cephalopoda Diversity from Statolith Remains: Taxonomic Assignation, Fossil Record Analysis, and New Data for Calibrating Molecular Phylogenies.

Directory of Open Access Journals (Sweden)

Pascal Neige

Full Text Available New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian of the Paris Basin. Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov., Loliginidae (Loligo clarkei sp. nov., and Ommastrephidae (genus indet. families. The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain. These sediments range in age from 46 Mya to 43 Mya. Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data indicates marked biases in our knowledge. Fossil statoliths are known from as far back as the Early Jurassic (199.3 to 190.8 Mya but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous. This is a "knowledge bias" and clearly calls for further studies. Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies. This comparison clearly indicates that the new records detailed here will challenge some estimated divergence times of coleoid cephalopod subclades.

New Eocene Coleoid (Cephalopoda) Diversity from Statolith Remains: Taxonomic Assignation, Fossil Record Analysis, and New Data for Calibrating Molecular Phylogenies.

Science.gov (United States)

Neige, Pascal; Lapierre, Hervé; Merle, Didier

2016-01-01

New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian) of the Paris Basin. Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov.), Loliginidae (Loligo clarkei sp. nov.), and Ommastrephidae (genus indet.) families. The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain. These sediments range in age from 46 Mya to 43 Mya. Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data) indicates marked biases in our knowledge. Fossil statoliths are known from as far back as the Early Jurassic (199.3 to 190.8 Mya) but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous. This is a "knowledge bias" and clearly calls for further studies. Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies. This comparison clearly indicates that the new records detailed here will challenge some estimated divergence times of coleoid cephalopod subclades.

Species Profiles. Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Gulf of Mexico). COMMON RANGIA.

Science.gov (United States)

1985-04-01

manufacture (Arndt 1976). Of the material dredged of glass, chemicals, chicken and cattle in 1967, an estimated 12.2 million tons feed, wallboard, and...Clam shells poultry grit, cattle roughage, filter are harvested by large commercial material, and whiting (pigment). hydraulic dredges. By far the...non-selective filter feeders orange coloration and effecting (Darnell 1958; Olsen 1976a) ingesting castration . Only large clams are large quantities

Analysis list: Clamp [Chip-atlas[Archive

Lifescience Database Archive (English)

Full Text Available Clamp Cell line + dm3 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clamp.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clam...p.5.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/target/Clam...p.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Clamp.Cell_line.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/colo/Cell_line.gml ...

Cool's Clams Casino

Science.gov (United States)

Cobey, Paul; Williams, David E.

1977-01-01

A mathematical game that reinforces basic multiplication facts, strengthens concepts of factors and multiples, and also provides arithmetic drill is described. Four variations of the game are also provided. (JT)

A phylogenetic perspective on the evolution of Mediterranean teleost fishes.

Directory of Open Access Journals (Sweden)

Christine N Meynard

Full Text Available The Mediterranean Sea is a highly diverse, highly studied, and highly impacted biogeographic region, yet no phylogenetic reconstruction of fish diversity in this area has been published to date. Here, we infer the timing and geographic origins of Mediterranean teleost species diversity using nucleotide sequences collected from GenBank. We assembled a DNA supermatrix composed of four mitochondrial genes (12S ribosomal DNA, 16S ribosomal DNA, cytochrome c oxidase subunit I and cytochrome b and two nuclear genes (rhodopsin and recombination activating gene I, including 62% of Mediterranean teleost species plus 9 outgroups. Maximum likelihood and Bayesian phylogenetic and dating analyses were calibrated using 20 fossil constraints. An additional 124 species were grafted onto the chronogram according to their taxonomic affinity, checking for the effects of taxonomic coverage in subsequent diversification analyses. We then interpreted the time-line of teleost diversification in light of Mediterranean historical biogeography, distinguishing non-endemic natives, endemics and exotic species. Results show that the major Mediterranean orders are of Cretaceous origin, specifically ~100-80 Mya, and most Perciformes families originated 80-50 Mya. Two important clade origin events were detected. The first at 100-80 Mya, affected native and exotic species, and reflects a global diversification period at a time when the Mediterranean Sea did not yet exist. The second occurred during the last 50 Mya, and is noticeable among endemic and native species, but not among exotic species. This period corresponds to isolation of the Mediterranean from Indo-Pacific waters before the Messinian salinity crisis. The Mediterranean fish fauna illustrates well the assembly of regional faunas through origination and immigration, where dispersal and isolation have shaped the emergence of a biodiversity hotspot.

Interspecific variability of endocrine disruption and oxidative stress in two bivalve species from the Ria Formosa Lagoon (south coast of Portugal

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Catarina Pereira

2013-01-01

Full Text Available Estuaries are highly productive ecosystems that have been increasingly affected by anthropogenic activities. In this study, the presence of endocrine disrupting compounds (EDCs and their relation to oxidative stress were assessed in two bivalve species (mussels Mytilus galloprovincialis and clams Ruditapes decussatus from the Ria Formosa Lagoon (south Portugal. We applied the alkali-labile phosphate (ALP assay to determine vitellogenin-like protein levels, and the lipid peroxidation (LPO method to assess oxidative damage. Mussels and clams exhibited the same pattern of ALP concentrations, with no differences between genders and higher levels in winter. R. decussatus showed higher ALP values than M. galloprovincialis, possibly associated with a stronger responsiveness of clams to EDCs or due to the influence of the reproductive cycle. Mussels exhibited a more evident seasonal effect for LPO, indicating that these organisms are more influenced by seasonal fluctuations in the water column compared to the sediment-associated clams. Both species appear to be under the influence of EDC exposure (which could induce Vg-like protein synthesis and oxidative stressors (leading to lipid peroxidation in the Ria Formosa Lagoon, particularly in winter, reflecting the presence of different contaminants in Ria Formosa and environmental changes, as well as complex interactions between them.

Hydroforming simulation and preparation of low activation martensitic steel Y-shapes

International Nuclear Information System (INIS)

Guo, X.Z.; Tao, J.; Yuan, Z.; Tang, Q.S.

2011-01-01

Highlights: → We hydroformed CLAM Y-shapes successfully after optimizing important parameters. → The feed of left punch decreased with the increasing protrusion angle. → The axial feed of the right punch increased with increasing the angle. → To obtain the highest protrusion, loading path 3 was the optimum. → The friction coefficient value of 0.07 is relatively superior. - Abstract: The hydroforming process to prepare China low activation Martensitic steel (CLAM) Y-shapes with desired protrusion height and uniform thinning rate was studied in this work. The axial feed distances for Y-shapes of the different protrusion angles were determined. Then, the effects of the loading path and the friction coefficient on the protrusion height and the distribution of thinning rate of the 45 o Y-shapes were investigated by numerical simulation, respectively. The optimized parameters were obtained: left axial feed 79 mm, right axial feed 60 mm and friction coefficient 0.07. In addition, the optimal loading path with the maximum rise rate of the internal pressure was determined. Subsequently, CLAM Y-shapes were hydroformed successfully based on the simulation results. The experimental results were approximately accordant with the simulative ones. It was indicated that the qualified CLAM Y-shapes could be obtained by the optimized hydroforming process.

Microplastics effects in Scrobicularia plana.

Science.gov (United States)

Ribeiro, Francisca; Garcia, Ana R; Pereira, Beatriz P; Fonseca, Maria; Mestre, Nélia C; Fonseca, Tainá G; Ilharco, Laura M; Bebianno, Maria João

2017-09-15

One of the most common plastics in the marine environment is polystyrene (PS) that can be broken down to micro sized particles. Marine organisms are vulnerable to the exposure to microplastics. This study assesses the effects of PS microplastics in tissues of the clam Scrobicularia plana. Clams were exposed to 1mgL -1 (20μm) for 14days, followed by 7days of depuration. A qualitative analysis by infrared spectroscopy in diffuse reflectance mode period detected the presence of microplastics in clam tissues upon exposure, which were not eliminated after depuration. The effects of microplastics were assessed by a battery of biomarkers and results revealed that microplastics induce effects on antioxidant capacity, DNA damage, neurotoxicity and oxidative damage. S. plana is a significant target to assess the environmental risk of PS microplastics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Carotenoids in Marine Invertebrates Living along the Kuroshio Current Coast

Directory of Open Access Journals (Sweden)

Yoshikazu Sakagami

2011-08-01

Full Text Available Carotenoids of the corals Acropora japonica, A. secale, and A. hyacinthus, the tridacnid clam Tridacna squamosa, the crown-of-thorns starfish Acanthaster planci, and the small sea snail Drupella fragum were investigated. The corals and the tridacnid clam are filter feeders and are associated with symbiotic zooxanthellae. Peridinin and pyrrhoxanthin, which originated from symbiotic zooxanthellae, were found to be major carotenoids in corals and the tridacnid clam. The crown-of-thorns starfish and the sea snail D. fragum are carnivorous and mainly feed on corals. Peridinin-3-acyl esters were major carotenoids in the sea snail D. fragum. On the other hand, ketocarotenoids such as 7,8-didehydroastaxanthin and astaxanthin were major carotenoids in the crown-of-thorns starfish. Carotenoids found in these marine animals closely reflected not only their metabolism but also their food chains.

Roughans Point, Revere, Massachusetts Coastal Flood Protection Study. Volume I. Main Report.

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1982-12-01

1982 conducted bT, Rusty Iwanowicz , Massachusetts Division of Marine Fisheries, concluded that the shoreline area that would be impacted by the... Iwanowicz , DMF, and Charles Freeman of my staff. In this survey, five test holes were dug seaward of the area of project impact in areas which Mr... Iwanowicz felt would indicate the productivity of the clam flat. Two holes revealed no shellfish, and the best hole produced two razor clams, two

Heavy metals in sediments and soft tissues of the Antarctic clam Laternula elliptica: more evidence as a possible biomonitor of coastal marine pollution at high latitudes?

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Vodopivez, Cristian; Curtosi, Antonio; Villaamil, Edda; Smichowski, Patricia; Pelletier, Emilien; Mac Cormack, Walter P

2015-01-01

Studies on metal contamination in 25 de Mayo Island, Antarctica, yielded controversial results. In this work, we analyzed Antarctic marine sediments and Antarctic clam (Laternula elliptica) tissues to investigate the possible use of this mollusk as a biomonitor of metals and to identify the sources of metal pollution. Different types of paint from several buildings from Carlini Station were examined to assess their contribution to the local and random metal pollution. Five sediment samples, 105 L. elliptica specimens (40.2-78.0mm length) and four types of paint were analyzed to quantify Cd, Cr, Cu, Fe, Mn, Pb and Zn using inductively coupled plasma-optical emission spectrometry. Metal concentrations in sediments were lower than the global averages of the earth's crust, with the exception of Cd and Cu. These results were related to the contribution of the local fresh-water runoff. The different varieties of paint showed low levels of Cu, Mn, Fe and Zn, whereas a broad range of values were found in the case of Cr and Pb (20-15,100 μg·g(-1) and 153-115,500 μg·g(-1) respectively). The remains of the paint would be responsible for the significant increases in Cr and Pb which are randomly detected by us and by other authors. High levels of Fe and Cd, in comparison to other Antarctic areas, appear to be related to the terrigenous materials transported by the local streams. Accumulation indexes suggested that kidney tissue from L. elliptica could be an adequate material for biomonitoring pollution with Cd, Zn and probably also Pb. In general, relationships between size and metal contents reported by other authors were not verified, suggesting that this issue should be revised. Copyright © 2014 Elsevier B.V. All rights reserved.

Multilocus resolution of phylogeny and timescale in the extant adaptive radiation of Hawaiian honeycreepers.

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Lerner, Heather R L; Meyer, Matthias; James, Helen F; Hofreiter, Michael; Fleischer, Robert C

2011-11-08

Evolutionary theory has gained tremendous insight from studies of adaptive radiations. High rates of speciation, morphological divergence, and hybridization, combined with low sequence variability, however, have prevented phylogenetic reconstruction for many radiations. The Hawaiian honeycreepers are an exceptional adaptive radiation, with high phenotypic diversity and speciation that occurred within the geologically constrained setting of the Hawaiian Islands. Here we analyze a new data set of 13 nuclear loci and pyrosequencing of mitochondrial genomes that resolves the Hawaiian honeycreeper phylogeny. We show that they are a sister taxon to Eurasian rosefinches (Carpodacus) and probably came to Hawaii from Asia. We use island ages to calibrate DNA substitution rates, which vary substantially among gene regions, and calculate divergence times, showing that the radiation began roughly when the oldest of the current large Hawaiian Islands (Kauai and Niihau) formed, ~5.7 million years ago (mya). We show that most of the lineages that gave rise to distinctive morphologies diverged after Oahu emerged (4.0-3.7 mya) but before the formation of Maui and adjacent islands (2.4-1.9 mya). Thus, the formation of Oahu, and subsequent cycles of colonization and speciation between Kauai and Oahu, played key roles in generating the morphological diversity of the extant honeycreepers. Copyright © 2011 Elsevier Ltd. All rights reserved.

Phylogeny and biogeography of the genus Stevia (Asteraceae: Eupatorieae): an example of diversification in the Asteraceae in the new world.

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Soejima, Akiko; Tanabe, Akifumi S; Takayama, Izumi; Kawahara, Takayuki; Watanabe, Kuniaki; Nakazawa, Miyuki; Mishima, Misako; Yahara, Tetsukazu

2017-11-01

The genus Stevia comprises approximately 200 species, which are distributed in North and South America, and are representative of the species diversity of the Asteraceae in the New World. We reconstructed the phylogenetic relationships using sequences of ITS and cpDNA and estimated the divergence times of the major clade of this genus. Our results suggested that Stevia originated in Mexico 7.0-7.3 million years ago (Mya). Two large clades, one with shrub species and another with herb species, were separated at about 6.6 Mya. The phylogenetic reconstruction suggested that an ancestor of Stevia was a small shrub in temperate pine-oak forests and the evolutionary change from a shrub state to a herb state occurred only once. A Brazilian clade was nested in a Mexican herb clade, and its origin was estimated to be 5.2 Mya, suggesting that the migration from North America to South America occurred after the formation of the Isthmus of Panama. The species diversity in Mexico appears to reflect the habitat diversity within the temperate pine-oak forest zone. The presence of many conspecific diploid-polyploid clades in the phylogenetic tree reflects the high frequency of polyploidization among the perennial Stevia species.

Complete Chloroplast Genome Sequence of Coptis chinensis Franch. and Its Evolutionary History

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He, Yang; Deng, Cao; Fan, Gang; Qin, Shishang

2017-01-01

The Coptis chinensis Franch. is an important medicinal plant from the Ranunculales. We used next generation sequencing technology to determine the complete chloroplast genome of C. chinensis. This genome is 155,484 bp long with 38.17% GC content. Two 26,758 bp long inverted repeats separated the genome into a typical quadripartite structure. The C. chinensis chloroplast genome consists of 128 gene loci, including eight rRNA gene loci, 28 tRNA gene loci, and 92 protein-coding gene loci. Most of the SSRs in C. chinensis are poly-A/T. The numbers of mononucleotide SSRs in C. chinensis and other Ranunculaceae species are fewer than those in Berberidaceae species, while the number of dinucleotide SSRs is greater than that in the Berberidaceae. C. chinensis diverged from other Ranunculaceae species an estimated 81 million years ago (Mya). The divergence between Ranunculaceae and Berberidaceae was ~111 Mya, while the Ranunculales and Magnoliaceae shared a common ancestor during the Jurassic, ~153 Mya. Position 104 of the C. chinensis ndhG protein was identified as a positively selected site, indicating possible selection for the photosystem-chlororespiration system in C. chinensis. In summary, the complete sequencing and annotation of the C. chinensis chloroplast genome will facilitate future studies on this important medicinal species. PMID:28698879

Complete Chloroplast Genome Sequence of Coptis chinensis Franch. and Its Evolutionary History

Directory of Open Access Journals (Sweden)

Yang He

2017-01-01

Full Text Available The Coptis chinensis Franch. is an important medicinal plant from the Ranunculales. We used next generation sequencing technology to determine the complete chloroplast genome of C. chinensis. This genome is 155,484 bp long with 38.17% GC content. Two 26,758 bp long inverted repeats separated the genome into a typical quadripartite structure. The C. chinensis chloroplast genome consists of 128 gene loci, including eight rRNA gene loci, 28 tRNA gene loci, and 92 protein-coding gene loci. Most of the SSRs in C. chinensis are poly-A/T. The numbers of mononucleotide SSRs in C. chinensis and other Ranunculaceae species are fewer than those in Berberidaceae species, while the number of dinucleotide SSRs is greater than that in the Berberidaceae. C. chinensis diverged from other Ranunculaceae species an estimated 81 million years ago (Mya. The divergence between Ranunculaceae and Berberidaceae was ~111 Mya, while the Ranunculales and Magnoliaceae shared a common ancestor during the Jurassic, ~153 Mya. Position 104 of the C. chinensis ndhG protein was identified as a positively selected site, indicating possible selection for the photosystem-chlororespiration system in C. chinensis. In summary, the complete sequencing and annotation of the C. chinensis chloroplast genome will facilitate future studies on this important medicinal species.

A Microarray Study of Carpet-Shell Clam (Ruditapes decussatus Shows Common and Organ-Specific Growth-Related Gene Expression Differences in Gills and Digestive Gland

Directory of Open Access Journals (Sweden)

Carlos Saavedra

2017-11-01

Full Text Available Growth rate is one of the most important traits from the point of view of individual fitness and commercial production in mollusks, but its molecular and physiological basis is poorly known. We have studied differential gene expression related to differences in growth rate in adult individuals of the commercial marine clam Ruditapes decussatus. Gene expression in the gills and the digestive gland was analyzed in 5 fast-growing and five slow-growing animals by means of an oligonucleotide microarray containing 14,003 probes. A total of 356 differentially expressed genes (DEG were found. We tested the hypothesis that differential expression might be concentrated at the growth control gene core (GCGC, i.e., the set of genes that underlie the molecular mechanisms of genetic control of tissue and organ growth and body size, as demonstrated in model organisms. The GCGC includes the genes coding for enzymes of the insulin/insulin-like growth factor signaling pathway (IIS, enzymes of four additional signaling pathways (Raf/Ras/Mapk, Jnk, TOR, and Hippo, and transcription factors acting at the end of those pathways. Only two out of 97 GCGC genes present in the microarray showed differential expression, indicating a very little contribution of GCGC genes to growth-related differential gene expression. Forty eight DEGs were shared by both organs, with gene ontology (GO annotations corresponding to transcription regulation, RNA splicing, sugar metabolism, protein catabolism, immunity, defense against pathogens, and fatty acid biosynthesis. GO term enrichment tests indicated that genes related to growth regulation, development and morphogenesis, extracellular matrix proteins, and proteolysis were overrepresented in the gills. In the digestive gland overrepresented GO terms referred to gene expression control through chromatin rearrangement, RAS-related small GTPases, glucolysis, and energy metabolism. These analyses suggest a relevant role of, among others

The ctenidium of the giant clam, Tridacna squamosa, expresses an ammonium transporter 1 that displays light-suppressed gene and protein expression and may be involved in ammonia excretion.

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Boo, Mel V; Hiong, Kum C; Goh, Enan J K; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

2018-04-24

Ammonium transporters (AMTs) can participate in ammonia uptake or excretion across the plasma membrane of prokaryotic, plant and invertebrate cells. The giant clam, Tridacna squamosa, harbors nitrogen-deficient symbiotic zooxanthellae, and normally conducts light-enhanced ammonia absorption to benefit the symbionts. Nonetheless, it can excrete ammonia when there is a supply of exogenous nitrogen or exposed to continuous darkness. This study aimed to elucidate the role of AMT1 in the ctenidium of T. squamosa by cloning and characterizing the AMT1/AMT1, determining its subcellular localization, and examining changes in its transcript and protein expression levels in response to light exposure. The cDNA coding sequence of AMT1 from T. squamosa consisted of 1527 bp and encoded 508 amino acids of 54.6 kDa. AMT1-immunofluorescence was detected mainly at the apical epithelium of ctenidial filaments, and it decreased significantly after 12 h of exposure to light. By contrast, the epithelial cells surrounding the tertiary water channels in the ctentidium, which are known to exhibit light-enhanced glutamine synthetase expression and take part in the assimilation of exogenous ammonia in light, did not display any AMT1-immunolabelling. Furthermore, the transcript level and protein abundance of ctenidial AMT1/AMT1 decreased significantly at the 6th and 12th h of light exposure. Taken together, these results indicate that AMT1 might participate in ammonia excretion instead of ammonia absorption and assimilation in T. squamosa. It is probable that the expression levels of AMT1/AMT1 need to be down-regulated during light exposure to achieve light-enhanced ammonia uptake.

Environmental genotoxicity and risk assessment in the Gulf of Riga (Baltic Sea) using fish, bivalves, and crustaceans.

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Butrimavičienė, Laura; Baršienė, Janina; Greiciūnaitė, Janina; Stankevičiūtė, Milda; Valskienė, Roberta

2018-06-21

Environmental genotoxicity in the Gulf of Riga was assessed using different bioindicators (fish, clams, and isopods) collected from 14 study stations. Comparison of genotoxicity responses (micronuclei (MN) and nuclear buds (NB)) in blood erythrocytes of herring (Clupea harengus), eelpout (Zoarces viviparous), and flounder (Platichthys flesus) revealed the species- and site-specific differences. For the first time, the analysis of genotoxicity was carried out in gill cells of isopods Saduria entomon. The highest inductions of MN and NB in gill cells of investigated S. entomon and clams (Macoma balthica) were evaluated in specimens from station 111A (offshore zone). In fish, the highest incidences of MN were measured in eelpout and in herring collected in the southern part of Gulf of Riga (station GOR3/41S). Moreover, in the southern coastal area, the assessment of genotoxicity risk (according to micronuclei levels) indicated exceptionally high risk for flounder, eelpout, and clams.