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Sample records for alexandrium minutum dinophyceae

  1. Morphology, toxin composition and LSU rDNA phylogeny of Alexandrium minutum (Dinophyceae) from Denmark, with some morphological observations on other European strains

    DEFF Research Database (Denmark)

    Hansen, Gert; Daugbjerg, Niels; Franco, J.M.

    2003-01-01

    The morphology of Alexandrium minutum Halim from Denmark was studied and compared to the morphology of material from Portugal, Spain, France and Ireland. Strains from Denmark and the French coast of the English Channel differed from the typical minutum morphotype by the absence of a ventral pore...

  2. First record of potentially toxic dinoflagellate, Alexandrium minutum Halim 1960, from Peruvian coastal

    Directory of Open Access Journals (Sweden)

    Maribel Baylón

    2015-04-01

    Full Text Available Herein, we report the first record of the potentially toxic dinoflagellate Alexandrium minutum Halim 1960 from the Peruvian littoral. Alexandrium minutum produced the algae bloom in March 2006 and February 2009, in the Callao bay. Its identification was carried out by a morpho-taxonomic examination, detailing their plates with light and epifluorescence microscopy, moreover its quantification was realized in sedimentation chambers. This is the first report of A. minutum for Southeast Pacific. The characteristics in size, shape and thecal morphology were similarly to original descriptions of this species.

  3. Alexandrium minutum growth controlled by phosphorus An applied model

    OpenAIRE

    Chapelle, Annie; Labry, Claire; Sourisseau, Marc; Lebreton, Carole; Youenou, Agnes; Crassous, Marie-pierre

    2010-01-01

    Toxic algae are a worldwide problem threatening aquaculture public health and tourism Alexandrium a toxic dinoflagellate proliferates in Northwest France estuaries (i e the Penze estuary) causing Paralytic Shellfish Poisoning events Vegetative growth and in particular the role of nutrient uptake and growth rate are crucial parameters to understand toxic blooms With the goal of modelling in situ Alexandrium blooms related to environmental parameters we first try to calibrate a zero-dimensional...

  4. Warm temperature acclimation impacts metabolism of paralytic shellfish toxins from Alexandrium minutum in commercial oysters.

    Science.gov (United States)

    Farrell, Hazel; Seebacher, Frank; O'Connor, Wayne; Zammit, Anthony; Harwood, D Tim; Murray, Shauna

    2015-09-01

    Species of Alexandrium produce potent neurotoxins termed paralytic shellfish toxins and are expanding their ranges worldwide, concurrent with increases in sea surface temperature. The metabolism of molluscs is temperature dependent, and increases in ocean temperature may influence both the abundance and distribution of Alexandrium and the dynamics of toxin uptake and depuration in shellfish. Here, we conducted a large-scale study of the effect of temperature on the uptake and depuration of paralytic shellfish toxins in three commercial oysters (Saccostrea glomerata and diploid and triploid Crassostrea gigas, n = 252 per species/ploidy level). Oysters were acclimated to two constant temperatures, reflecting current and predicted climate scenarios (22 and 27 °C), and fed a diet including the paralytic shellfish toxin-producing species Alexandrium minutum. While the oysters fed on A. minutum in similar quantities, concentrations of the toxin analogue GTX1,4 were significantly lower in warm-acclimated S. glomerata and diploid C. gigas after 12 days. Following exposure to A. minutum, toxicity of triploid C. gigas was not affected by temperature. Generally, detoxification rates were reduced in warm-acclimated oysters. The routine metabolism of the oysters was not affected by the toxins, but a significant effect was found at a cellular level in diploid C. gigas. The increasing incidences of Alexandrium blooms worldwide are a challenge for shellfish food safety regulation. Our findings indicate that rising ocean temperatures may reduce paralytic shellfish toxin accumulation in two of the three oyster types; however, they may persist for longer periods in oyster tissue. © 2015 John Wiley & Sons Ltd.

  5. Comparative gene expression in toxic versus non-toxic strains of the marine dinoflagellate Alexandrium minutum

    Directory of Open Access Journals (Sweden)

    Glöckner Gernot

    2010-04-01

    Full Text Available Abstract Background The dinoflagellate Alexandrium minutum typically produces paralytic shellfish poisoning (PSP toxins, which are known only from cyanobacteria and dinoflagellates. While a PSP toxin gene cluster has recently been characterized in cyanobacteria, the genetic background of PSP toxin production in dinoflagellates remains elusive. Results We constructed and analysed an expressed sequence tag (EST library of A. minutum, which contained 15,703 read sequences yielding a total of 4,320 unique expressed clusters. Of these clusters, 72% combined the forward-and reverse reads of at least one bacterial clone. This sequence resource was then used to construct an oligonucleotide microarray. We analysed the expression of all clusters in three different strains. While the cyanobacterial PSP toxin genes were not found among the A. minutum sequences, 192 genes were differentially expressed between toxic and non-toxic strains. Conclusions Based on this study and on the lack of identified PSP synthesis genes in the two existent Alexandrium tamarense EST libraries, we propose that the PSP toxin genes in dinoflagellates might be more different from their cyanobacterial counterparts than would be expected in the case of a recent gene transfer. As a starting point to identify possible PSP toxin-associated genes in dinoflagellates without relying on a priori sequence information, the sequences only present in mRNA pools of the toxic strain can be seen as putative candidates involved in toxin synthesis and regulation, or acclimation to intracellular PSP toxins.

  6. Experimental and computational studies on molecularly imprinted solid-phase extraction for gonyautoxins 2,3 from dinoflagellate Alexandrium minutum.

    Science.gov (United States)

    Lian, Ziru; Li, Hai-Bei; Wang, Jiangtao

    2016-08-01

    An innovative and effective extraction procedure based on molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation of gonyautoxins 2,3 (GTX2,3) from Alexandrium minutum sample. Molecularly imprinted polymer microspheres were prepared by suspension polymerization and and were employed as sorbents for the solid-phase extraction of GTX2,3. An off-line MISPE protocol was optimized. Subsequently, the extract samples from A. minutum were analyzed. The results showed that the interference matrices in the extract were obviously cleaned up by MISPE procedures. This outcome enabled the direct extraction of GTX2,3 in A. minutum samples with extraction efficiency as high as 83 %, rather significantly, without any need for a cleanup step prior to the extraction. Furthermore, computational approach also provided direct evidences of the high selective isolation of GTX2,3 from the microalgal extracts.

  7. Cellular and biochemical responses of the oyster Crassostrea gigas to controlled exposures to metals and Alexandrium minutum

    Energy Technology Data Exchange (ETDEWEB)

    Haberkorn, Hansy; Lambert, Christophe; Le Goïc, Nelly [Laboratoire des Sciences de l‘Environnement Marin, UMR 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Place Copernic, Technopôle Brest-Iroise, 29280 Plouzané (France); Quéré, Claudie [IFREMER Centre de Brest, Laboratoire de Physiologie des Invertébrés, Unité Physiologie Fonctionnelle des Organismes Marins, BP 70, 29280 Plouzané (France); Bruneau, Audrey; Riso, Ricardo; Auffret, Michel [Laboratoire des Sciences de l‘Environnement Marin, UMR 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Place Copernic, Technopôle Brest-Iroise, 29280 Plouzané (France); Soudant, Philippe, E-mail: Philippe.Soudant@univ-brest.fr [Laboratoire des Sciences de l‘Environnement Marin, UMR 6539, Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale, Place Copernic, Technopôle Brest-Iroise, 29280 Plouzané (France)

    2014-02-15

    Highlights: •Oysters, C. gigas, were exposed to both metals and PST-producer A. minutum. •Oysters exposed to metals accumulated about thirty-six times less PSTs. •Exposure to both metals and A. minutum induced antagonistic or synergetic effects. -- Abstract: Effects of simultaneous exposure of Pacific oyster, Crassostrea gigas, to both a harmful dinoflagellate that produces Paralytic Shellfish Toxins (PST), Alexandrium minutum, and cadmium (Cd) and copper (Cu), were assessed. Oysters were exposed to a mix of Cd–Cu with two different diets (i.e. A. minutum or Tisochrysis lutea) and compared to control oysters fed A. minutum or T. lutea, respectively, without metal addition. Metals and PST accumulations, digestive gland lipid composition, and cellular and biochemical hemolymph variables were measured after 4 days of exposure. Oysters exposed to Cd–Cu accumulated about thirty-six times less PSTs than oysters exposed to A. minutum alone. Exposure to Cd–Cu induced significant changes in neutral lipids (increase in diacylglycerol – DAG – and decrease in sterols) and phospholipids (decreases in phosphatidylcholine, phosphatidylethanolamine, cardiolipin and ceramide aminoethylphosphonate) of digestive gland suggesting that lipid metabolism disruptions and/or lipid peroxidation have occurred. Simultaneously, concentrations, percentages of dead cells and phenoloxidase activity of hemocytes increased in oysters exposed to metals while reactive oxygen species production of hemocytes decreased. Feeding on the harmful dinoflagellate A. minutum resulted in significant decreases in monoacylglycerol (MAG) and DAG and ether glycerides (EG), as well as significant increases in hemocyte concentration and phagocytic activity as compared to oysters fed T. lutea. Finally, the present study revealed that short-term, simultaneous exposure to Cd–Cu and A. minutum may induce antagonistic (i.e. hemocyte concentration and phagocytosis) or synergic (i.e. DAG content in

  8. Selective isolation of gonyautoxins 1,4 from the dinoflagellate Alexandrium minutum based on molecularly imprinted solid-phase extraction.

    Science.gov (United States)

    Lian, Ziru; Wang, Jiangtao

    2017-09-15

    Gonyautoxins 1,4 (GTX1,4) from Alexandrium minutum samples were isolated selectively and recognized specifically by an innovative and effective extraction procedure based on molecular imprinting technology. Novel molecularly imprinted polymer microspheres (MIPMs) were prepared by double-templated imprinting strategy using caffeine and pentoxifylline as dummy templates. The synthesized polymers displayed good affinity to GTX1,4 and were applied as sorbents. Further, an off-line molecularly imprinted solid-phase extraction (MISPE) protocol was optimized and an effective approach based on the MISPE coupled with HPLC-FLD was developed for selective isolation of GTX1,4 from the cultured A. minutum samples. The separation method showed good extraction efficiency (73.2-81.5%) for GTX1,4 and efficient removal of interferences matrices was also achieved after the MISPE process for the microalgal samples. The outcome demonstrated the superiority and great potential of the MISPE procedure for direct separation of GTX1,4 from marine microalgal extracts. Copyright © 2017. Published by Elsevier Ltd.

  9. Uptake, distribution and depuration of paralytic shellfish toxins from Alexandrium minutum in Australian greenlip abalone, Haliotis laevigata.

    Science.gov (United States)

    Dowsett, Natalie; Hallegraeff, Gustaaf; van Ruth, Paul; van Ginkel, Roel; McNabb, Paul; Hay, Brenda; O'Connor, Wayne; Kiermeier, Andreas; Deveney, Marty; McLeod, Catherine

    2011-07-01

    Farmed greenlip abalone Haliotis laevigata were fed commercial seaweed-based food pellets or feed pellets supplemented with 8 × 10⁵ Alexandrium minutum dinoflagellate cells g⁻¹ (containing 12 ± 3.0 μg STX-equivalent 100 g⁻¹, which was mainly GTX-1,4) every second day for 50 days. Exposure of abalone to PST supplemented feed for 50 days did not affect behaviour or survival but saw accumulation of up to 1.6 μg STX-equivalent 100 g⁻¹ in the abalone foot tissue (muscle, mouth without oesophagus and epipodial fringe), which is ∼50 times lower than the maximum permissible limit (80 μg 100 g⁻¹ tissue) for PSTs in molluscan shellfish. The PST levels in the foot were reduced to 0.48 μg STX-equivalent 100 g⁻¹ after scrubbing and removal of the pigment surrounding the epithelium of the epipodial fringe (confirmed by both HPLC and LC-MS/MS). Thus, scrubbing the epipodial fringe, a common procedure during commercial abalone canning, reduced PST levels by ∼70%. Only trace levels of PSTs were detected in the viscera (stomach, gut, heart, gonad, gills and mantle) of the abalone. A toxin reduction of approximately 73% was observed in STX-contaminated abalone held in clean water and fed uncontaminated food over 50 days. The low level of PST uptake when abalone were exposed to high numbers of A. minutum cells over a prolonged period may indicate a low risk of PSP poisoning to humans from the consumption of H. laevigata that has been exposed to a bloom of potentially toxic A. minutum in Australia. Further research is required to establish if non-dietary accumulation can result in significant levels of PSTs in abalone. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  10. Die SekundärmetaboliteDMSP und Toxinein Dinophyceae der Gattungen Prorocentrum Ehrenberg und Alexandrium Halim

    OpenAIRE

    Gress, Ariane C.

    2006-01-01

    A common feature among Dinophyceae is the presence of intracellular secondary metabolites. The exact function and relevance of most of these secondary compounds for its host and the interplay between different secondary metabolites is not well understood. A better characterized secondary metabolite is the tertiary sulfonium compound dimethylsulfoniopropionate (DMSP) which - as compatible solute - is for example involved in the process of osmoregulation. In some species of dinoflagellates toxi...

  11. Distribution of Alexandrium fundyense (Dinophyceae) cysts in Greenland and Iceland, with an emphasis on viability and growth in the Arctic.

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    Richlen, Mindy L; Zielinski, Oliver; Holinde, Lars; Tillmann, Urban; Cembella, Allan; Lyu, Yihua; Anderson, Donald M

    2016-01-01

    The bloom-forming dinoflagellate Alexandrium fundyense has been extensively studied due its toxin-producing capabilities and consequent impacts to human health and economies. This study investigated the prevalence of resting cysts of A. fundyense in western Greenland and Iceland to assess the historical presence and magnitude of bloom populations in the region, and to characterize environmental conditions during summer, when bloom development may occur. Analysis of sediments collected from these locations showed that Alexandrium cysts were present at low to moderate densities in most areas surveyed, with highest densities observed in western Iceland. Additionally, laboratory experiments were conducted on clonal cultures established from isolated cysts or vegetative cells from Greenland, Iceland, and the Chukchi Sea (near Alaska) to examine the effects of photoperiod interval and irradiance levels on growth. Growth rates in response to the experimental treatments varied among isolates, but were generally highest under conditions that included both the shortest photoperiod interval (16h:8h light:dark) and higher irradiance levels (~146-366 μmol photons m -2 s -1 ), followed by growth under an extended photoperiod interval and low irradiance level (~37 μmol photons m -2 s -1 ). Based on field and laboratory data, we hypothesize that blooms in Greenland are primarily derived from advected Alexandrium populations, as low bottom temperatures and limited light availability would likely preclude in situ bloom development. In contrast, the bays and fjords in Iceland may provide more favorable habitat for germling cell survival and growth, and therefore may support indigenous, self-seeding blooms.

  12. Formal Revision of the Alexandrium tamarense Species Complex (Dinophyceae) Taxonomy: The Introduction of Five Species with Emphasis on Molecular-based (rDNA) Classification

    Science.gov (United States)

    John, Uwe; Litaker, R. Wayne; Montresor, Marina; Murray, Shauna; Brosnahan, Michael L.; Anderson, Donald M.

    2015-01-01

    The Alexandrium tamarense species complex is one of the most studied marine dinoflagellate groups due to its ecological, toxicological and economic importance. Several members of this complex produce saxitoxin and its congeners – potent neurotoxins that cause paralytic shellfish poisoning. Isolates from this complex are assigned to A. tamarense, A. fundyense, or A. catenella based on two main morphological characters: the ability to form chains and the presence/absence of a ventral pore between Plates 1′ and 4′. However, studies have shown that these characters are not consistent and/or distinctive. Further, phylogenies based on multiple regions in the rDNA operon indicate that the sequences from morphologically indistinguishable isolates partition into five clades. These clades were initially named based on their presumed geographic distribution, but recently were renamed as Groups I–V following the discovery of sympatry among some groups. In this study we present data on morphology, ITS/5.8S genetic distances, ITS2 compensatory base changes, mating incompatibilities, toxicity, the sxtA toxin synthesis gene, and rDNA phylogenies. All results were consistent with each group representing a distinct cryptic species. Accordingly, the groups were assigned species names as follows: Group I, A. fundyense; Group II, A. mediterraneum; Group III, A. tamarense; Group IV, A. pacificum; Group V, A. australiense. PMID:25460230

  13. Nitrogen and phosphorus requirements of an Alexandrium minutum bloom in the Penze' Estuary, France

    Digital Repository Service at National Institute of Oceanography (India)

    Maguer, J.-F.; Wafar, M.V.M.; Madec, C.; Morin, P.; Denn, E.E.

    . The role of NO3 was restricted to sustenance of the bloom, whereas warm conditions resulting in a water column stability seem to have triggered the bloom, and a self-shading, probably coupled with a phosphorus limitation, caused its decline...

  14. Analysis of Toxic and Non-Toxic Alexandrium (Dinophyceae) Species Using Ribosomal RNA Gene Sequences

    Science.gov (United States)

    1993-02-01

    Therriault, J.-C. (1988). Cladistic analysis of electrophoretic variants within the toxic dinoflagellate genus Protogonyaulax. Botanica Marina 31: 39- 51. 8... Botanica Marina 34: 575-587. Halegraeff, G. M., and Bolch, C.J. (1992). Transport of toxic dinoflagellate cysts via ship’s ballast water: implications...analysis of electrophoretic variants within the toxic dinoflagellate genus Protogonv-u.!a,. Botanica Marina 31: 39-51. Curran, J., Baillie, D.L

  15. Functional Genomics of a Non-Toxic Alexandrium Lusitanicum Culture

    National Research Council Canada - National Science Library

    Martins, Claudia A

    2007-01-01

    .... The loss of toxicity was accompanied by a reduction in growth capability. A subculture of this isolate maintains the ability to produce toxins and to grow at rates and to cell abundances that were characteristic of the original Alexandrium culture...

  16. Functional Genomics of a Non-Toxic Alexandrium Lusitanicum Culture

    Science.gov (United States)

    2007-02-01

    cultured in the Laboratorio de Micro- minutum analyzed with the same methods and instrument biologia e Ecotoxicologia where the loss of toxicity was...and Lach.) dies., Gonyaulax tamarensis Leb., and Peridinium trochoideum (Stein) Lemm. Notas e Estudos do Instituto de Biologia Marinha 26: 1-21. Silva

  17. Termination of a toxic Alexandrium bloom with hydrogen peroxide

    NARCIS (Netherlands)

    Burson, A.; Matthijs, H.C.P.; Bruijne, de W.; Talens, R.; Hoogenboom, L.A.P.; Gerssen, A.; Visser, P.M.; Stomp, M.; Steur, K.; Scheppingen, van Y.; Huisman, J.

    2014-01-01

    The dinoflagellate Alexandrium ostenfeldii is a well-known harmful algal species that can potentially cause paralytic shellfish poisoning (PSP). Usually A. ostenfeldii occurs in low background concentrations only, but in August of 2012 an exceptionally dense bloom of more than 1 million cells L-1

  18. The globally distributed genus Alexandrium: multifaceted roles in marine ecosystems and impacts on human health

    OpenAIRE

    Anderson, Donald M.; Alpermann, Tilman J.; Cembella, Allan D.; Collos, Yves; Masseret, Estelle; Montresor, Marina

    2012-01-01

    The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms. The ability of Alexandrium to colonize multiple habitats and to persist over large regions through time is testimony to the adaptability and resilience of this group of species. Three different families of toxins, as well as an as yet incompletely characterized suite of allelochemicals are produced among Alexandrium species. Nutri...

  19. The globally distributed genus Alexandrium: multifaceted roles in marine ecosystems and impacts on human health.

    Science.gov (United States)

    Anderson, Donald M; Alpermann, Tilman J; Cembella, Allan D; Collos, Yves; Masseret, Estelle; Montresor, Marina

    2012-02-01

    The dinoflagellate genus Alexandrium is one of the major harmful algal bloom (HAB) genera with respect to the diversity, magnitude and consequences of blooms. The ability of Alexandrium to colonize multiple habitats and to persist over large regions through time is testimony to the adaptability and resilience of this group of species. Three different families of toxins, as well as an as yet incompletely characterized suite of allelochemicals are produced among Alexandrium species. Nutritional strategies are equally diverse, including the ability to utilize a range of inorganic and organic nutrient sources, and feeding by ingestion of other organisms. Many Alexandrium species have complex life histories that include sexuality and often, but not always, cyst formation, which is characteristic of a meroplanktonic life strategy and offers considerable ecological advantages. Due to the public health and ecosystem impacts of Alexandrium blooms, the genus has been extensively studied, and there exists a broad knowledge base that ranges from taxonomy and phylogeny through genomics and toxin biosynthesis to bloom dynamics and modeling. Here we present a review of the genus Alexandrium, focusing on the major toxic and otherwise harmful species.

  20. Molecular Identification of Gambierdiscus and Fukuyoa (Dinophyceae from Environmental Samples

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    Kirsty F. Smith

    2017-08-01

    Full Text Available Ciguatera Fish Poisoning (CFP is increasing across the Pacific and the distribution of the causative dinoflagellates appears to be expanding. Subtle differences in thecal plate morphology are used to distinguish dinoflagellate species, which are difficult to determine using light microscopy. For these reasons we sought to develop a Quantitative PCR assay that would detect all species from both Gambierdiscus and Fukuyoa genera in order to rapidly screen environmental samples for potentially toxic species. Additionally, a specific assay for F. paulensis was developed as this species is of concern in New Zealand coastal waters. Using the assays we analyzed 31 samples from three locations around New Zealand and the Kingdom of Tonga. Fourteen samples in total were positive for Gambierdiscus/Fukuyoa and two samples were also positive using the F. paulensis assay. Samples from the Kermadec Islands were further characterized using high-throughput sequencing metabarcoding. The majority of reads corresponded to Gambierdiscus species with three species identified at all sites (G. australes, G. honu and G. polynesiensis. This is the first confirmed identification of G. polynesiensis, a known ciguatoxin producer, in New Zealand waters. Other known toxin-producing genera were also detected, included Alexandrium, Amphidinium, Azadinium, Dinophysis, Ostreopsis, and Prorocentrum.

  1. Georges Bank: a leaky incubator of Alexandrium fundyense blooms.

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    McGillicuddy, D J; Townsend, D W; Keafer, B A; Thomas, M A; Anderson, D M

    2014-05-01

    A series of oceanographic surveys on Georges Bank document variability of populations of the toxic dinoflagellate Alexandrium fundyense on time scales ranging from synoptic to seasonal to interannual. Blooms of A. fundyense on Georges Bank can reach concentrations on the order of 10 4 cells l -1 , and are generally bank-wide in extent. Georges Bank populations of A. fundyense appear to be quasi-independent of those in the adjacent coastal Gulf of Maine, insofar as they occupy a hydrographic niche that is colder and saltier than their coastal counterparts. In contrast to coastal populations that rely on abundant resting cysts for bloom initiation, very few cysts are present in the sediments on Georges Bank. Bloom dynamics must therefore be largely controlled by the balance between growth and mortality processes, which are at present largely unknown for this population. Based on correlations between cell abundance and nutrient distributions, ammonium appears to be an important source of nitrogen for A. fundyense blooms on Georges Bank.

  2. THE RED-TIDE DINOFLAGELLATE, ALEXANDRIUM MONILATUM, SUPPRESSES GROWTH OF MIXED NATURAL PHYTOPLANKTON

    Science.gov (United States)

    Alexandrium monilatum is a large, chain-forming, autotrophic dinoflagellate associated with red-tides and fish kills along the US Gulf of Mexico coast. When cultured inocula of A. monilatum were added to nutrient-amended seawater samples, growth rates and biomass yields of the na...

  3. Morphology and phylogeny of Triadinium polyedricum (Pouchet) Dodge (Dinophyceae) from Korean coastal waters

    Science.gov (United States)

    Shin, Hyeon Ho; Li, Zhun; Kim, Eun Song; Youn, Joo Yeon; Jeon, Seul Gi; Oh, Seok Jin; Lim, Weol-Ae

    2016-12-01

    To identify features that can be used to differentiate Triadinium polyedricum from other related species, such as Fukuyoa paulensis and Alexandrium species, the detailed morphology and phylogeny of T. polyedricum collected from Korean coastal waters were investigated. The cells had a plate formula of Po, 3', 7″, 5‴, 1p and 2″″, which is consistent with morphological descriptions in previous reports. Large subunit ribosomal DNA sequences also revealed that T. polyedricum from Korean coastal waters is identical to previously recorded isolates. T. polyedricum is morphologically characterized by a ventral pore in the 1″ plate that is comparable to F. paulensis and Alexandrium species. This result indicates that the location and presence of this ventral pore seems suitable for differentiating T. polyedricum from other related species.

  4. Genome analysis of Elusimicrobium minutum, the first cultivated representative of the Elusimicrobia phylum (formerly Termite Group 1)

    Energy Technology Data Exchange (ETDEWEB)

    Herlemann, D. P. R.; Geissinger, O.; Ikeda-Ohtsubo, W.; Kunin, V.; Sun, H.; Lapidus, A.; Hugenholtz, P.; Brune, A.

    2009-02-01

    The candidate phylum Termite group 1 (TG1), is regularly 1 encountered in termite hindguts but is present also in many other habitats. Here we report the complete genome sequence (1.64 Mbp) of Elusimicrobium minutum strain Pei191{sup T}, the first cultured representative of the TG1 phylum. We reconstructed the metabolism of this strictly anaerobic bacterium isolated from a beetle larva gut and discuss the findings in light of physiological data. E. minutum has all genes required for uptake and fermentation of sugars via the Embden-Meyerhof pathway, including several hydrogenases, and an unusual peptide degradation pathway comprising transamination reactions and leading to the formation of alanine, which is excreted in substantial amounts. The presence of genes encoding lipopolysaccharide biosynthesis and the presence of a pathway for peptidoglycan formation are consistent with ultrastructural evidence of a Gram-negative cell envelope. Even though electron micrographs showed no cell appendages, the genome encodes many genes putatively involved in pilus assembly. We assigned some to a type II secretion system, but the function of 60 pilE-like genes remains unknown. Numerous genes with hypothetical functions, e.g., polyketide synthesis, non-ribosomal peptide synthesis, antibiotic transport, and oxygen stress protection, indicate the presence of hitherto undiscovered physiological traits. Comparative analysis of 22 concatenated single-copy marker genes corroborated the status of Elusimicrobia (formerly TG1) as a separate phylum in the bacterial domain, which was so far based only on 16S rRNA sequence analysis.

  5. An Alexandrium Spp. Cyst Record from Sequim Bay, Washington State, USA, and its Relation to Past Climate Variability(1).

    Science.gov (United States)

    Feifel, Kirsten M; Moore, Stephanie K; Horner, Rita A

    2012-06-01

    Since the 1970s, Puget Sound, Washington State, USA, has experienced an increase in detections of paralytic shellfish toxins (PSTs) in shellfish due to blooms of the harmful dinoflagellate Alexandrium. Natural patterns of climate variability, such as the Pacific Decadal Oscillation (PDO), and changes in local environmental factors, such as sea surface temperature (SST) and air temperature, have been linked to the observed increase in PSTs. However, the lack of observations of PSTs in shellfish prior to the 1950s has inhibited statistical assessments of longer-term trends in climate and environmental conditions on Alexandrium blooms. After a bloom, Alexandrium cells can enter a dormant cyst stage, which settles on the seafloor and then becomes entrained into the sedimentary record. In this study, we created a record of Alexandrium spp. cysts from a sediment core obtained from Sequim Bay, Puget Sound. Cyst abundances ranged from 0 to 400 cysts · cm(-3) and were detected down-core to a depth of 100 cm, indicating that Alexandrium has been present in Sequim Bay since at least the late 1800s. The cyst record allowed us to statistically examine relationships with available environmental parameters over the past century. Local air temperature and sea surface temperature were positively and significantly correlated with cyst abundances from the late 1800s to 2005; no significant relationship was found between PDO and cyst abundances. This finding suggests that local environmental variations more strongly influence Alexandrium population dynamics in Puget Sound when compared to large-scale changes. © 2012 Phycological Society of America.

  6. Inhibition of the growth of Alexandrium tamarense by algicidal substances in Chinese fir (Cunninghamia lanceolata).

    Science.gov (United States)

    Yang, Wei-Dong; Liu, Jie-Sheng; Li, Hong-Ye; Zhang, Xin-Lian; Qi, Yu-Zao

    2009-10-01

    The wood sawdust from Chinese fir (Cunninghamia lanceolata) exhibited stronger inhibition on the growth of Alexandrium tamarense than those from alder (Alnus cremastogyne), pine (Pinus massoniana), birch (Betula alnoides) and sapele (Entandrophragma cylindricum). The water extract, acetone-water extract and essential oil from fir sawdust were all shown to inhibit the growth of A. tamarense. The inhibition of fir essential oil was the strongest among all the above wood sources while the half effective concentration was only 0.65 mg/L. These results suggested that the fir essential oil may play an important role in the algicidal effect of Chinese fir.

  7. [Effects of Alexandrium tamarense and Prorocentrum donghaiense on rotifer Brachionus plicatilis population].

    Science.gov (United States)

    Wang, Liping; Yan, Tian; Tan, Zhijun; Zhou, Mingjiang

    2003-07-01

    The effects of Prorocentrum donghaiense and Alexandrium sp., causative species of harmful algal bloom of East China Sea in May 2002, on rotifer Brachionus plicatilis population were studied in the laboratory. The results showed that Alexandrium tamarense (ATHK) had a lethal effect on B. plicatilis and the 48hLC50 was about 1300 cell.ml-1. The toxin comparison of different fractions showed that the algal culture and re-suspended algal cells had the adverse effects, and the alga at earlier growth phases showed a stronger impact, indicating that the inhibitory effect was related with the activity of the living algal cells. P. donghaiense at high densities (4 x 10(4), 5 x 10(4) and 10 x 10(4) cell.ml-1) had an adverse effect on B. plicatilis population, while at low densities (1 x 10(4), 2 x 10(4) and 3 x 10(4) cell.ml-1), the alga could be used as food for rotifer population. When the two algae were mixed, the lethal effect of A. tamarense could be decreased by P. donghaiense. The results indicated that the above HAB event could affect the micro-zooplankton population in the occurrence area of East China Sea.

  8. Comparative Proteomic Analysis Reveals Proteins Putatively Involved in Toxin Biosynthesis in the Marine Dinoflagellate Alexandrium catenella

    Directory of Open Access Journals (Sweden)

    Da-Zhi Wang

    2013-01-01

    Full Text Available Alexandrium is a neurotoxin-producing dinoflagellate genus resulting in paralytic shellfish poisonings around the world. However, little is known about the toxin biosynthesis mechanism in Alexandrium. This study compared protein profiles of A. catenella collected at different toxin biosynthesis stages (non-toxin synthesis, initial toxin synthesis and toxin synthesizing coupled with the cell cycle, and identified differentially expressed proteins using 2-DE and MALDI-TOF-TOF mass spectrometry. The results showed that toxin biosynthesis of A. catenella occurred within a defined time frame in the G1 phase of the cell cycle. Proteomic analysis indicated that 102 protein spots altered significantly in abundance (P < 0.05, and 53 proteins were identified using database searching. These proteins were involved in a variety of biological processes, i.e., protein modification and biosynthesis, metabolism, cell division, oxidative stress, transport, signal transduction, and translation. Among them, nine proteins with known functions in paralytic shellfish toxin-producing cyanobacteria, i.e., methionine S-adenosyltransferase, chloroplast ferredoxin-NADP+ reductase, S-adenosylhomocysteinase, adenosylhomocysteinase, ornithine carbamoyltransferase, inorganic pyrophosphatase, sulfotransferase (similar to, alcohol dehydrogenase and arginine deiminase, varied significantly at different toxin biosynthesis stages and formed an interaction network, indicating that they might be involved in toxin biosynthesis in A. catenella. This study is the first step in the dissection of the behavior of the A. catenella proteome during different toxin biosynthesis stages and provides new insights into toxin biosynthesis in dinoflagellates.

  9. Comparative proteomic analysis reveals proteins putatively involved in toxin biosynthesis in the marine dinoflagellate Alexandrium catenella.

    Science.gov (United States)

    Wang, Da-Zhi; Gao, Yue; Lin, Lin; Hong, Hua-Sheng

    2013-01-22

    Alexandrium is a neurotoxin-producing dinoflagellate genus resulting in paralytic shellfish poisonings around the world. However, little is known about the toxin biosynthesis mechanism in Alexandrium. This study compared protein profiles of A. catenella collected at different toxin biosynthesis stages (non-toxin synthesis, initial toxin synthesis and toxin synthesizing) coupled with the cell cycle, and identified differentially expressed proteins using 2-DE and MALDI-TOF-TOF mass spectrometry. The results showed that toxin biosynthesis of A. catenella occurred within a defined time frame in the G1 phase of the cell cycle. Proteomic analysis indicated that 102 protein spots altered significantly in abundance (P translation. Among them, nine proteins with known functions in paralytic shellfish toxin-producing cyanobacteria, i.e., methionine S-adenosyltransferase, chloroplast ferredoxin-NADP+ reductase, S-adenosylhomocysteinase, adenosylhomocysteinase, ornithine carbamoyltransferase, inorganic pyrophosphatase, sulfotransferase (similar to), alcohol dehydrogenase and arginine deiminase, varied significantly at different toxin biosynthesis stages and formed an interaction network, indicating that they might be involved in toxin biosynthesis in A. catenella. This study is the first step in the dissection of the behavior of the A. catenella proteome during different toxin biosynthesis stages and provides new insights into toxin biosynthesis in dinoflagellates.

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

    Directory of Open Access Journals (Sweden)

    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

  11. Allelopathic effects of Alexandrium tamarense on other algae: evidence from mixed growth experiments

    DEFF Research Database (Denmark)

    Tillmann, Urban; Hansen, Per Juel

    2009-01-01

    period, even though cell concentrations of Alex5 became very high (2 × 104 cells ml-1). As both strains contained comparable amounts of PST, this confirmed previous suggestions that so far unidentified compounds are causing the negative effects on other algae. Sensitivity of the tested algae to Alex2......The effect of 2 strains (Alex2 and Alex5) of the marine red tide dinoflagellate Alexandrium tamarense on 10 other planktonic algal target species common in temperate waters was studied in mixed growth experiments under nutrient-rich conditions. In a comparative approach, the 2 strains of A....... tamarense, similar in their cellular paralytic shellfish toxin (PST) content, were selected because of their fundamentally different lytic potencies. The Alex2 strain clearly affected all target algae while the Alex5 strain had no negative effect on the growth of any of the target species during the study...

  12. [Effects of red tide microalgae Alexandrium tamarense on the life history of rotifer Brachionus plicatilis].

    Science.gov (United States)

    Xie, Zhi-Hao; Xiao, Huh; Cai, Heng-Jiang; Wang, Ren-Jun; Tang, Xue-Xi

    2007-12-01

    In this paper, life-table method was used to study the effects of different concentration Alexandrium tamarense on the durations of different development stages of Brachionus plicatilis and the characters of its population growth. The results showed that A. tamarense had significant effects on the growth and development of B. plicatilis via prolonging the durations of the rotifer' s pre-reproduction and generation succession, shortening the durations of its reproduction and post-reproduction and its mean lifespan, and reducing its laying eggs and fecundity. The net reproduction rate and intrinsic increasing rate of B. plicatilis decreased significantly, in comparison with those of the control. B. plicatilis could maintain definite population increase at the presence of different concentration A. tamarense.

  13. Toxicity of algicidal extracts from Mangrovimonas yunxiaonensis strain LY01 on a HAB causing Alexandrium tamarense

    International Nuclear Information System (INIS)

    Li, Yi; Zhu, Hong; Zhang, Huajun; Chen, Zhangran; Tian, Yun; Xu, Hong; Zheng, Tianling; Zheng, Wei

    2014-01-01

    Highlights: • Stable and eco-environmental algicidal extracts were used to HABs-control. • Algicidal extracts induced cell-death and nuclear damage in Alexandrium tamarense. • Algicidal process and nuclear damage were confirmed by TEM and CLSM. • The transcription of rbcS, hsp and PCNA genes were influenced by algicidal extracts. - Abstract: Toxicity of algicidal extracts from Mangrovimonas yunxiaonensis strain LY01 on Alexandrium tamarense were measured through studying the algicidal procedure, nuclear damage and transcription of related genes. Medium components were optimized to improve algicidal activity, and characteristics of algicidal extracts were determined. Transmission electron microscope analysis revealed that the cell structure was broken. Cell membrane integrity destruction and nuclear structure degradation were monitored using confocal laser scanning microscope, and the rbcS, hsp and proliferating cell nuclear antigen (PCNA) gene expressions were studied. Results showed that 1.0% tryptone, 0.4% glucose and 0.8% MgCl 2 were the optimal nutrient sources. The algicidal extracts were heat and pH stable, non-protein and less than 1 kD. Cell membrane and nuclear structure integrity were lost, and the transcription of the rbcS and PCNA genes were significantly inhibited and there was up-regulation of hsp gene expression during the exposure procedure. The algicidal extracts destroyed the cell membrane and nuclear structure integrity, inhibited related gene expression and, eventually, lead to the inhibition of algal growth. All the results may elaborate firstly the cell death process and nuclear damage in A. tamarense which was induced by algicidal extracts, and the algicidal extracts could be potentially used as bacterial control of HABs in future

  14. Islandinium minutum subsp. barbatum subsp. nov. (Dinoflagellata), a New Organic-Walled Dinoflagellate Cyst from the Western Arctic: Morphology, Phylogenetic Position Based on SSU rDNA and LSU rDNA, and Distribution.

    Science.gov (United States)

    Potvin, Éric; Kim, So-Young; Yang, Eun Jin; Head, Martin J; Kim, Hyun-Cheol; Nam, Seung-Il; Yim, Joung Han; Kang, Sung-Ho

    2018-03-25

    A study of modern sediment from the Western Arctic has revealed the presence of a distinctive brown-colored cyst with a spherical central body bearing unbranched processes that are usually solid with a small basal pericoel. Distinctive barbs project from some processes, and process tips are usually minutely expanded into conjoined barbs. The archeopyle is apical and saphopylic. This cyst corresponds to Islandinium? cezare morphotype 2 of Head et al. (2001, J. Quat. Sci., 16:621). Phylogenetic analyses based on the small and large subunit rRNA genes infer close relationship with Islandinium minutum, the type of which is that of the genus. Re-examination of specimens of I. minutum reveals the presence of minute barbs on its processes, but differences with Islandinium? cezare morphotype 2 remain based on size, process distribution, and barb development. Furthermore, the internal transcribed spacer shows I. minutum to be distinct from this morphotype. On the basis of these small but discrete differences, we propose the new subspecies Islandinium minutum subsp. barbatum subsp. nov. Molecular sequencing of other cysts encountered, namely Echinidinium karaense, an unidentified flattened cyst, and "Polykrikos quadratus", places them in the Monovela clade, the latter showing greater morphological variability than previously thought. © 2018 The Author(s) Journal of Eukaryotic Microbiology © 2018 International Society of Protistologists.

  15. Global transcriptional profiling of the toxic dinoflagellate Alexandrium fundyense using Massively Parallel Signature Sequencing

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    Anderson Donald M

    2006-04-01

    Full Text Available Abstract Background Dinoflagellates are one of the most important classes of marine and freshwater algae, notable both for their functional diversity and ecological significance. They occur naturally as free-living cells, as endosymbionts of marine invertebrates and are well known for their involvement in "red tides". Dinoflagellates are also notable for their unusual genome content and structure, which suggests that the organization and regulation of dinoflagellate genes may be very different from that of most eukaryotes. To investigate the content and regulation of the dinoflagellate genome, we performed a global analysis of the transcriptome of the toxic dinoflagellate Alexandrium fundyense under nitrate- and phosphate-limited conditions using Massively Parallel Signature Sequencing (MPSS. Results Data from the two MPSS libraries showed that the number of unique signatures found in A. fundyense cells is similar to that of humans and Arabidopsis thaliana, two eukaryotes that have been extensively analyzed using this method. The general distribution, abundance and expression patterns of the A. fundyense signatures were also quite similar to other eukaryotes, and at least 10% of the A. fundyense signatures were differentially expressed between the two conditions. RACE amplification and sequencing of a subset of signatures showed that multiple signatures arose from sequence variants of a single gene. Single signatures also mapped to different sequence variants of the same gene. Conclusion The MPSS data presented here provide a quantitative view of the transcriptome and its regulation in these unusual single-celled eukaryotes. The observed signature abundance and distribution in Alexandrium is similar to that of other eukaryotes that have been analyzed using MPSS. Results of signature mapping via RACE indicate that many signatures result from sequence variants of individual genes. These data add to the growing body of evidence for widespread gene

  16. Effect of Associated Bacteria on the Growth and Toxicity of Alexandrium catenella

    Science.gov (United States)

    Uribe, Paulina; Espejo, Romilio T.

    2003-01-01

    Saprophytic bacteria in cultures of the marine dinoflagellate Alexandrium catenella were removed to assess their effect on growth and paralytic shellfish poisoning toxin production of this dinoflagellate. The actual axenic status was demonstrated by the lack of observable bacteria both immediately after treatment and following extended incubation in the absence of antibiotics. Bacteria were measured by counting CFU and also by epifluorescence microscopy and PCR amplification of bacterial 16S-23S spacer ribosomal DNA to detect noncultivable bacteria. Removal of bacteria did not have any effect on the growth of the dinoflagellate except for the inhibition of A. catenella disintegration after reaching the stationary phase. Toxicity was determined in dinoflagellate cell extracts by different methods: high-performance liquid chromatography (HPLC); an electrophysiological test called the Electrotest, which measures the inhibition of saxitoxin-sensitive Na+ channels expressed in a cell line; and a mouse bioassay, which measures the toxic effect on the whole mammal neuromuscular system. A lower toxicity of the dinoflagellates in axenic culture was observed by these three methods, though the difference was significant only by the mouse bioassay and HPLC methods. Altogether the results indicate that axenic cultures of A. catenella are able to produce toxin, though the total toxicity is probably diminished to about one-fifth of that in nonaxenic cultures. PMID:12514056

  17. A red tide of Alexandrium fundyense in the Gulf of Maine

    Science.gov (United States)

    McGillicuddy, D. J.; Brosnahan, M. L.; Couture, D. A.; He, R.; Keafer, B. A.; Manning, J. P.; Martin, J. L.; Pilskaln, C. H.; Townsend, D. W.; Anderson, D. M.

    2014-05-01

    In early July 2009, an unusually high concentration of the toxic dinoflagellate Alexandrium fundyense occurred in the western Gulf of Maine, causing surface waters to appear reddish brown to the human eye. The discolored water appeared to be the southern terminus of a large-scale event that caused shellfish toxicity along the entire coast of Maine to the Canadian border. Rapid-response shipboard sampling efforts together with satellite data suggest the water discoloration in the western Gulf of Maine was a highly ephemeral feature of less than two weeks in duration. Flow cytometric analysis of surface samples from the red water indicated the population was undergoing sexual reproduction. Cyst fluxes downstream of the discolored water were the highest ever measured in the Gulf of Maine, and a large deposit of new cysts was observed that fall. Although the mechanisms causing this event remain unknown, its timing coincided with an anomalous period of downwelling-favorable winds that could have played a role in aggregating upward-swimming cells. Regardless of the underlying causes, this event highlights the importance of short-term episodic phenomena on regional population dynamics of A. fundyense.

  18. Diversity and dynamics of a widespread bloom of the toxic dinoflagellate Alexandrium fundyense.

    Directory of Open Access Journals (Sweden)

    Deana L Erdner

    Full Text Available Historically, cosmopolitan phytoplankton species were presumed to represent largely unstructured populations. However, the recent development of molecular tools to examine genetic diversity have revealed differences in phytoplankton taxa across geographic scales and provided insight into the physiology and ecology of blooms. Here we describe the genetic analysis of an extensive bloom of the toxic dinoflagellate Alexandrium fundyense that occurred in the Gulf of Maine in 2005. This bloom was notable for its intensity and duration, covering hundreds of kilometers and persisting for almost two months. Genotypic analyses based on microsatellite marker data indicate that the open waters of the northeastern U.S. harbor a single regional population of A. fundyense comprising two genetically distinct sub-populations. These subpopulations were characteristic of early- and late-bloom samples and were derived from the northern and southern areas of the bloom, respectively. The temporal changes observed during this study provide clear evidence of succession during a continuous bloom and show that selection can act on the timescale of weeks to significantly alter the representation of genotypes within a population. The effects of selection on population composition and turnover would be magnified if sexual reproduction were likewise influenced by environmental conditions. We hypothesize that the combined effects of differential growth and reproduction rates serves to reduce gene flow between the sub-populations, reinforcing population structure while maintaining the diversity of the overall regional population.

  19. Characterizing the interactions among a dinoflagellate, flagellate and bacteria in the phycosphere of Alexandrium tamarense (Dinophyta

    Directory of Open Access Journals (Sweden)

    Lidan eHu

    2015-11-01

    Full Text Available A small flagellate alga was isolated from the phycosphere of a toxic red tide dinoflagellate Alexandrium tamarense. Phylogenetic analysis and ultrastructural observations demonstrated that the samll flagellate alga is a species belong to Ochrophyte Ochromonas sp. The process of ingesting bacteria by Ochromonas sp. was recorded by a time lapse capture under a light microscope. Through the use of different assemblages in the co-culture experiment, the species interactions in this phycosphere microenvironment were analyzed. We demonstrated that the growth of Ochromonas sp. was supported by bacteria. Three strains of bacteria ingested by Ochromonas sp. were isolated and identified to belong to α-, δ- and γ-Proteobacteria. The growth of A. tamarense was suppressed when co-cultured with bacteria. In contrast, Ochromonas sp. triggered the growth of A. tamarense by inhibiting the growth of algicidal bacteria. This result firstly demonstrated a positive effect of a flagellate on a dinoflagellate in the phycosphere of A. tamarense. Combined with other negative effects between dinoflagellates and bacteria or bacteria and flagellates, this study showed a series of clear interactions among dinoflagellate, bacterium, and flagellate in the dinoflagellate microenvironment.

  20. Fenologia, cultivo in vitro e aclimatização da bromélia ameaçada de extinção Nidularium minutum Mez

    Directory of Open Access Journals (Sweden)

    Flávia Maria Kazue Kurita

    2013-12-01

    Full Text Available http://dx.doi.org/10.5007/2175-7925.2014v27n1p59   O conhecimento da fenologia de uma espécie indica o período mais favorável à coleta de sementes maduras, que podem ser utilizadas na produção de mudas por meio de métodos eficientes como o cultivo in vitro. Essa técnica tem sido considerada uma estratégia para a propagação de espécies ameaçadas de extinção, como é o caso da bromélia Nidularium minutum Mez. Este artigo teve por objetivo identificar a época de frutificação e de produção de sementes de exemplares in situ de N. minutum e estabelecer um protocolo de cultivo in vitro a partir de sementes. A fenologia da espécie foi acompanhada por 12 meses em plantas na Estação Biológica do Alto da Serra, em Paranapiacaba-SP. Os resultados mostraram que o melhor período para a colheita das sementes foi de junho a agosto de 2008. O processo germinativo ocorreu em todas as temperaturas testadas, tendo sido mais eficiente aos 26ºC, não sendo necessários sais minerais. As melhores condições para o crescimento das plantas ocorreram com a mesma temperatura, em meio Murashige e Skoog (MS contendo metade da concentração dos macronutrientes. Por meio desse protocolo, é possível conservar as plantas in vitro e otimizar sua produção para o uso em programas de repovoamento.

  1. Comprehensive insights into the response of Alexandrium tamarense to algicidal component secreted by a marine bacterium

    Directory of Open Access Journals (Sweden)

    Xueqian eLei

    2015-01-01

    Full Text Available Harmful algal blooms occur throughout the world, threatening human health and destroying marine ecosystems. Alexandrium tamarense is a globally distributed and notoriously toxic dinoflagellate that is responsible for most paralytic shellfish poisoning incidents. The culture supernatant of the marine algicidal bacterium BS02 showed potent algicidal effects on A. tamarense ATGD98-006. In this study, we investigated the effects of this supernatant on A. tamarense at physiological and biochemical levels to elucidate the mechanism involved in the inhibition of algal growth by the supernatant of the strain BS02. Reactive oxygen species (ROS levels increased following exposure to the BS02 supernatant, indicating that the algal cells had suffered from oxidative damage. The levels of cellular pigments, including chlorophyll a and carotenoids, were significantly decreased, which indicated that the accumulation of ROS destroyed pigment synthesis. The decline of the maximum photochemical quantum yield (Fv/Fm and relative electron transport rate (rETR suggested that the photosynthesis systems of algal cells were attacked by the BS02 supernatant. To eliminate the ROS, the activities of antioxidant enzymes, including superoxide dismutase (SOD and catalase (CAT, increased significantly within a short period of time. Real-time PCR revealed changes in the transcript abundances of two target photosynthesis-related genes (psbA and psbD and two target respiration-related genes (cob and cox. The transcription of the respiration-related genes was significantly inhibited by the treatments, which indicated that the respiratory system was disturbed. Our results demonstrate that the BS02 supernatant can affect the photosynthesis process and might block the PS II electron transport chain, leading to the production of excessive ROS. The increased ROS can further destroy membrane integrity and pigments, ultimately inducing algal cell death.

  2. Enzymatic digestive activity and absorption efficiency in Tagelus dombeii upon Alexandrium catenella exposure

    Science.gov (United States)

    Fernández-Reiriz, M. J.; Navarro, J. M.; Cisternas, B. A.; Babarro, J. M. F.; Labarta, U.

    2013-12-01

    We analyzed absorption efficiency (AE) and digestive enzyme activity (amylase, cellulase complex, and laminarinase) of the infaunal bivalve Tagelus dombeii originating from two geographic sites, Corral-Valdivia and Melinka-Aysén, which have different long-term paralytic shellfish poisoning (PSP) exposure rates. We report the effects of past feeding history (origin) on T. dombeii exposed to a mixed diet containing the toxic dinoflagellate Alexandrium catenella and another dinoflagellate-free control diet over a 12-day period in the laboratory. Absorption efficiency values of T. dombeii individuals that experienced PSP exposure in their habitat (Melinka-Aysén) remained unchanged during exposure to toxic food in the laboratory. In contrast, T. dombeii from a non-PSP exposure field site (Corral-Valdivia) showed a significant reduction in AE with toxic exposure time. This study established that the amylase and cellulase complexes were the most important enzymes in the digestive glands of Tagelus from both sites. The temporal evolution of enzymatic activity under toxic diet was fitted to exponential (amylase and cellulase) and to a logarithmic (laminarinase) models. In all fits, we found significant effect of origin in the model parameters. At the beginning of the experiment, higher enzymatic activity was observed for clams from Corral-Valdivia. The amylase activity decreased with time exposure for individuals from Corral and increased for individuals from Melinka. Cellulase activity did not vary over time for clams from Corral, but increased for individuals from Melinka and laminarinase activity decreased over time for individuals from Corral and remained unchanged over time for Melinka. A feeding history of exposure to the dinoflagellate A. catenella was reflected in the digestive responses of both T. dombeii populations.

  3. Temperature, salinity, chlorophyll pigments, nutrients and other parameters as part of the ECOHAB-GOM: The Ecology and Oceanography of Toxic Alexandrium Blooms in the Gulf of Maine project (NODC Accession 0064309)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The subproject described here is one of several components of ECOHAB-GOM: The Ecology and Oceanography of Toxic Alexandrium Blooms in the Gulf of Maine, a multi-PI,...

  4. Mapping the Fundamental Niches of Two Freshwater Microalgae, Chlorella vulgaris (Trebouxiophyceae and Peridinium cinctum (Dinophyceae, in 5-Dimensional Ion Space

    Directory of Open Access Journals (Sweden)

    Terence J. Evens

    2011-01-01

    Full Text Available The fundamental niche defined by five ions, NO3 −, PO4 3−, K+, Na+, and Cl−, was mapped for Chlorella vulgaris (Trebouxiophyceae and Peridinium cinctum (Dinophyceae growth rates and maximum cell densities in batch cultures. A five dimensional ion-mixture experimental design was projected across a total ion concentration gradient of 1 to 30 mM to delineate the ion-based, “potential” niche space, defined as the entire n-dimensional hypervolume demarcated by the feasible ranges of the independent factors under consideration. The growth rate-based, fundamental niche volumes overlapped for ca. 94% of the ion mixtures, although the regions of maximal growth rates and cell densities were different for each alga. Both C. vulgaris and P. cinctum exhibited similar positive responses to cations and negative responses to anions. It was determined that total ion concentration for these five ions, from 1 to 30 mM, did not directly affect either growth rate or maximal cell density for either alga, although it did play an interactive role with several ions. This study is the first that we are aware of to attempt the mapping of a multivariate, ion-based, fundamental niche volume. The implications of the experimental design utilized and the potential utility of this type of approach are discussed.

  5. Spatio-temporal variability of dinoflagellate assemblages in different salinity regimes in the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Alkawri, A.A.S.; Ramaiah, N.

    2008 at the estuarine sampling location off Siridao. The toxic species, Alexandrium minutum (1171 cells l sup(-1)) followed by Dinophysis acuminata (838 cells l sup(-1)) were found to attain maximum cell numbers among the 10 different toxic species...

  6. [The red tide caused by the dinoflagellate Alexandrium tamarense in the Colombian Pacific coast (2001)].

    Science.gov (United States)

    García-Hansen, Ingrid; Cortés-Altamirano, Roberto; Sierra-Beltrán, Arturo P

    2004-09-01

    From April 26th to May 15th 2001, a large algae bloom was observed off Tumaco Bay on the Pacific coast of Colombia. This was the first harmful algae bloom (HAB) reported in the region, and reached Gorgona Island, about 120 km north. A year later, starting March 2002, an offshore HAB developed from Cabo Corrientes North to Solano Bay. The typical abundance during the blooms reached 7.5 x 10(6) cells l(-1) for the 2001 event and 1.6 x 10(6) cells l(-1) for the 2002 event. During both events, low temperature and high salinity were recorded. Typical measurements in the area are 27-27.5 degrees C and 30-31.5 psu. Values observed during the two events were 24-24.6 degrees C and 33-34 psu; 3 degrees C below normal and more than 2.5 psu above average values. These conditions are indicative of local upwelling processes at the time of the events. On both occasions, cells corresponding to the Alexandrium catenella/fundeyense/tamarense complex represented 99-100% of the biomass. It was difficult to differentiate the cells from A. catenella, but the presence of short chains of only 4 cells (single cells represented most of the biomass) was suggestive of A. tamarense. Shape, dimensions, and detailed structure of the apical pore complex, first apical plate, posterior sulcal plate, and position of the ventral pore on plate 1' of cells were consistent with the description of A. tamarense, which has not been reported in the tropical East Pacific. The Control Center of Pacific Contamination of the Maritime General Direction of the Colombian Navy has been monitoring the area since 1994 without finding this species or HABs. This leads us to consider the two events as caused by recently introduced species, where local upwelling processes favor permanent and cyclic HABs. However, during these two events, there were no reports of effects on marine biota or of human poisoning, probably because the blooms occurred some distance offshore and far from exploited shellfish beds.

  7. Alexandrium fundyense cyst viability and germling survival in light vs. dark at a constant low temperature

    Science.gov (United States)

    Vahtera, Emil; Crespo, Bibiana G.; McGillicuddy, Dennis J.; Olli, Kalle; Anderson, Donald M.

    2014-05-01

    Both observations and models suggest that large-scale coastal blooms of Alexandrium fundyense in the Gulf of Maine are seeded by deep-bottom cyst accumulation zones (“seed beds”) where cysts germinate from the sediment surface or the overlying near-bottom nepheloid layers at water depths exceeding 100 m. The germling cells and their vegetative progeny are assumed to be subject to mortality while in complete darkness, as they swim to illuminated surface waters. To test the validity of this assumption we conducted laboratory investigations of cyst viability and the survival of the germling cells and their vegetative progeny during prolonged exposure to darkness at a temperature of 6 °C, simulating the conditions in deep Gulf of Maine waters. We isolated cysts from bottom sediments collected in the Gulf of Maine under low red light and incubated them in 96-well tissue culture-plates in culture medium under a 10:14 h light:dark cycle and under complete darkness. Cyst viability was high, with excystment frequency reaching 90% in the illuminated treatment after 30 days and in the dark treatment after 50 days. Average germination rates were 0.062 and 0.038 d-1 for light and dark treatments, respectively. The dark treatment showed an approximately 2-week time lag in maximum germination rates compared to the light treatment. Survival of germlings was considerably lower in the dark treatment. In the light treatments, 47% of germinated cysts produced germlings that were able to survive for 7 days and produce vegetative progeny, i.e., there were live cells in the well along with an empty cyst at least once during the experiment. In the dark treatments 12% of the cysts produced germlings that were able to survive for the same length of time. When dark treatments are scaled to take into account non-darkness related mortality, approximately 28% of the cysts produced germlings that were able to survive for at least 7 days. Even though cysts are able to germinate in darkness

  8. CO2-dependent carbon isotope fractionation in the dinoflagellate Alexandrium tamarense

    Science.gov (United States)

    Wilkes, Elise B.; Carter, Susan J.; Pearson, Ann

    2017-09-01

    The carbon isotopic composition of marine sedimentary organic matter is used to resolve long-term histories of pCO2 based on studies indicating a CO2-dependence of photosynthetic carbon isotope fractionation (εP). It recently was proposed that the δ13C values of dinoflagellates, as recorded in fossil dinocysts, might be used as a proxy for pCO2. However, significant questions remain regarding carbon isotope fractionation in dinoflagellates and how such fractionation may impact sedimentary records throughout the Phanerozoic. Here we investigate εP as a function of CO2 concentration and growth rate in the dinoflagellate Alexandrium tamarense. Experiments were conducted in nitrate-limited chemostat cultures. Values of εP were measured on cells having growth rates (μ) of 0.14-0.35 d-1 and aqueous carbon dioxide concentrations of 10.2-63 μmol kg-1 and were found to correlate linearly with μ/[CO2(aq)] (r2 = 0.94) in accord with prior, analogous chemostat investigations with eukaryotic phytoplankton. A maximum fractionation (εf) value of 27‰ was characterized from the intercept of the experiments, representing the first value of εf determined for an algal species employing Form II RubisCO-a structurally and catalytically distinct form of the carbon-fixing enzyme. This value is larger than theoretical predictions for Form II RubisCO and not significantly different from the ∼25‰ εf values observed for taxa employing Form ID RubisCO. We also measured the carbon isotope contents of dinosterol, hexadecanoic acid, and phytol from each experiment, finding that each class of biomarker exhibits different isotopic behavior. The apparent CO2-dependence of εP values in our experiments strengthens the proposal to use dinocyst δ13C values as a pCO2 proxy. Moreover, the similarity between the εf value for A. tamarense and the consensus value of ∼25‰ indicates that the CO2-sensitivity of carbon isotope fractionation saturates at similar CO2 levels across all three

  9. Short-term feeding response of the mussel Mytilus chilensis exposed to diets containing the toxic dinoflagellate Alexandrium catenella Respuesta alimentaria inicial del bivalvo Mytilus chilensis expuesto a dietas conteniendo el dinoflagelado tóxico Alexandrium catenella

    Directory of Open Access Journals (Sweden)

    JORGE M NAVARRO

    2008-03-01

    Full Text Available The short-term feeding response of the bivalve Mytilus chilensis was measured using four diets containing different proportions of the toxic dinoflagellate Alexandrium catenella. The diets containing the highest concentrations of the dinoflagellate showed the greatest effect on the feeding activity in the mussel, with clearance and ingestión rates significantly reduced during the first hours of exposure. After this period, M. chilensis demonstrated a capacity to acclimate to the toxic diets, with feeding parameters reaching values similar to those of untreated control organisms. It was not clear if the negative effect on the feeding behavior was caused by the presence of the paralytic toxin, or due to the larger size of the dinoflagellate cells in comparison with cells of Isochrysis galbana used in the control diet. However, parallel studies with diets containing the nontoxic dinoflagellate Alexandrium affine of similar size and shape to that of A. catenella, suggested the cell size was the main cause for impairment of feeding behavior. The capacity for acclimation to either toxin or cell size by M. chilensis makes it a good indicator species for the early detection of harmful PSP events, since its relative insensitivity to the toxin allows it to quickly recover normal feeding behavior and permits it to accumulate PSP in its tissues in a short timeLa respuesta inicial del bivalvo Mytilus chilensis fue medida bajo cuatro dietas que contenían diferentes proporciones del dinoflagelado tóxico Alexandrium catenella. Las dietas que contenían las concentraciones más altas de este dinoflagelado mostraron el mayor efecto durante las primeras horas de exposición. Después de este periodo inicial, M. chilensis demostró la capacidad para aclimatarse a estas dietas tóxicas, con parámetros de alimentación que alcanzaron valores similares a aquellos de los organismos controles. No fue claro si el efecto negativo sobre la conducta de alimentación fue

  10. Dynamics of late spring and summer phytoplankton communities on Georges Bank, with emphasis on diatoms, Alexandrium spp., and other dinoflagellates

    Science.gov (United States)

    Gettings, Rachel M.; Townsend, David W.; Thomas, Maura A.; Karp-Boss, Lee

    2014-05-01

    We analyzed the distribution, abundance, and succession patterns of major phytoplankton taxa on Georges Bank in relation to hydrography, nutrients, and size-fractionated chlorophyll concentrations (>20 μm; Gymnodinium spp., and Prorocentrum spp., had become more abundant. Patches of regenerated silicate during the June-July period appeared to support a post-spring-bloom diatom community on the central crest of the Bank (total diatom cell densities >180,000 cellsl-1) of Leptocylindrus spp., Dactyliosolen spp., and Guinardia flaccida. Multivariate statistical analyses of phytoplankton taxa and station locations revealed distinct assemblages of diatom and dinoflagellate taxa on the Bank throughout the late spring and summer. Results are interpreted in the ecological context of earlier-reported laboratory culture experiments on the competitive interactions between Alexandrium fundyense and diatoms.

  11. Coupling planktonic and benthic shifts during a bloom of Alexandrium catenella in southern Chile:Implications for bloom dynamics and recurrence

    OpenAIRE

    Díaz, P.A.; Molinet, C.; Seguel, M.; Díaz, M.; Labra, G.; Figueroa, R.I. (Rosa Isabel)

    2014-01-01

    Cell abundances and distributions of Alexandrium catenella resting cysts in recent sediments were studied along time at two locations in the Chilean Inland Sea exposed to different oceanographic conditions: Low Bay, which is much more open to the ocean than the more interior and protected Ovalada Island. The bloom began in interior areas but maximum cyst concentrations were recorded in locations more open to the ocean, at the end of the Moraleda channel. Our results showed a time lapse of aro...

  12. Paralytic Toxins Accumulation and Tissue Expression of α-Amylase and Lipase Genes in the Pacific Oyster Crassostrea gigas Fed with the Neurotoxic Dinoflagellate Alexandrium catenella

    Directory of Open Access Journals (Sweden)

    Mohamed Laabir

    2012-11-01

    Full Text Available The pacific oyster Crassostrea gigas was experimentally exposed to the neurotoxic Alexandrium catenella and a non-producer of PSTs, Alexandrium tamarense (control algae, at concentrations corresponding to those observed during the blooming period. At fixed time intervals, from 0 to 48 h, we determined the clearance rate, the total filtered cells, the composition of the fecal ribbons, the profile of the PSP toxins and the variation of the expression of two α-amylase and triacylglecerol lipase precursor (TLP genes through semi-quantitative RT-PCR. The results showed a significant decrease of the clearance rate of C. gigas fed with both Alexandrium species. However, from 29 to 48 h, the clearance rate and cell filtration activity increased only in oysters fed with A. tamarense. The toxin concentrations in the digestive gland rose above the sanitary threshold in less than 48 h of exposure and GTX6, a compound absent in A. catenella cells, accumulated. The α-amylase B gene expression level increased significantly in the time interval from 6 to 48 h in the digestive gland of oysters fed with A. tamarense, whereas the TLP gene transcript was significantly up-regulated in the digestive gland of oysters fed with the neurotoxic A. catenella. All together, these results suggest that the digestion capacity could be affected by PSP toxins.

  13. Paralytic Shellfish Toxins and Cyanotoxins in the Mediterranean: New Data from Sardinia and Sicily (Italy).

    Science.gov (United States)

    Lugliè, Antonella; Giacobbe, Maria Grazia; Riccardi, Elena; Bruno, Milena; Pigozzi, Silvia; Mariani, Maria Antonietta; Satta, Cecilia Teodora; Stacca, Daniela; Bazzoni, Anna Maria; Caddeo, Tiziana; Farina, Pasqualina; Padedda, Bachisio Mario; Pulina, Silvia; Sechi, Nicola; Milandri, Anna

    2017-11-16

    Harmful algal blooms represent a severe issue worldwide. They affect ecosystem functions and related services and goods, with consequences on human health and socio-economic activities. This study reports new data on paralytic shellfish toxins (PSTs) from Sardinia and Sicily (Italy), the largest Mediterranean islands where toxic events, mainly caused by Alexandrium species (Dinophyceae), have been ascertained in mussel farms since the 2000s. The toxicity of the A. minutum, A. tamarense and A. pacificum strains, established from the isolation of vegetative cells and resting cysts, was determined by high performance liquid chromatography (HPLC). The analyses indicated the highest toxicity for A. pacificum strains (total PSTs up to 17.811 fmol cell-1). The PSTs were also assessed in a strain of A. tamarense. The results encourage further investigation to increase the knowledge of toxic species still debated in the Mediterranean. This study also reports new data on microcystins (MCs) and β-N-methylamino-L-alanine (BMAA) from a Sardinian artificial lake (Lake Bidighinzu). The presence of MCs and BMAA was assessed in natural samples and in cell cultures by enzyme-linked immunosorbent assay (ELISA). BMAA positives were found in all the analysed samples with a maximum of 17.84 µg L-1. The obtained results added further information on cyanotoxins in Mediterranean reservoirs, particularly BMAA, which have not yet been thoroughly investigated.

  14. Investigation of the 2006 Alexandrium fundyense Bloom in the Gulf of Maine: In situ Observations and Numerical Modeling.

    Science.gov (United States)

    Li, Yizhen; He, Ruoying; McGillicuddy, Dennis J; Anderson, Donald M; Keafer, Bruce A

    2009-09-30

    In situ observations and a coupled bio-physical model were used to study the germination, initiation, and development of the Gulf of Maine (GOM) Alexandrium fundyense bloom in 2006. Hydrographic measurements and comparisons with GOM climatology indicate that 2006 was a year with normal coastal water temperature, salinity, current and river runoff conditions. A. fundyense cyst abundance in bottom sediments preceding the 2006 bloom was at a moderate level compared to other recent annual cyst survey data. We used the coupled bio-physical model to hindcast coastal circulation and A. fundyense cell concentrations. Field data including water temperature, salinity, velocity time series and surface A. fundyense cell concentration maps were applied to gauge the model's fidelity. The coupled model is capable of reproducing the hydrodynamics and the temporal and spatial distributions of A. fundyense cell concentration reasonably well. Model hindcast solutions were further used to diagnose physical and biological factors controlling the bloom dynamics. Surface wind fields modulated the bloom's horizontal and vertical distribution. The initial cyst distribution was found to be the dominant factor affecting the severity and the interannual variability of the A. fundyense bloom. Initial cyst abundance for the 2006 bloom was about 50% of that prior to the 2005 bloom. As the result, the time-averaged gulf-wide cell concentration in 2006 was also only about 60% of that in 2005. In addition, weaker alongshore currents and episodic upwelling-favorable winds in 2006 reduced the spatial extent of the bloom as compared with 2005.

  15. Study of molecularly imprinted solid-phase extraction of gonyautoxins 2,3 in the cultured dinoflagellate Alexandrium tamarense by high-performance liquid chromatography with fluorescence detection

    International Nuclear Information System (INIS)

    Lian, Zi-Ru; Wang, Jiang-Tao

    2013-01-01

    A highly selective sample cleanup procedure combined with molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation of gonyautoxins 2,3 (GTX2,3) from Alexandrium tamarense sample. The molecularly imprinted polymer microspheres (MIPMs) were prepared by suspension polymerization using caffeine as the dummy template molecule, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and polyvinyl alcohol as the dispersive reagent. The polymer microspheres were used as a selective sorbent for the solid-phase extraction of gonyautoxins 2,3. An off-line MISPE method followed by high-performance liquid chromatography (HPLC) with fluorescence detection for the analysis of gonyautoxins 2,3 was established. Finally, the extract samples from Alexandrium tamarense were analyzed. The results showed the imprinted polymer microspheres exhibited high affinity and selectivity for gonyautoxins 2,3. The interference matrix in the extract were obviously cleaned by MISPE and the extraction efficiency of gonyautoxins 2,3 in the sample ranged from 81.74% to 85.86%. -- Graphical abstract: This is the SEM photograph of molecularly imprinted polymer microspheres (MIPMs). MIPMs were prepared by suspension polymerization and used as selective sorbents for the solid-phase extraction of gonyautoxins 2,3. An off-line MISPE method followed by high-performance liquid chromatography with fluorescence detection for the analysis of gonyautoxins 2,3 was established. The extract samples from Alexandrium tamarense were analyzed by molecularly imprinted solid-phase extraction. Highlights: •The molecularly imprinted polymer microspheres (MIPMs) for GTX2,3 were prepared. •The characteristics and regeneration property of MIPMs were studied. •An off-line method using MIPMs as solid-phase extraction (SPE) sorbents was developed. •GTX2,3 from Alexandrium tamarense extract was successfully isolated by MIPMs-SPE. -- MIPMs for GTX2,3 were

  16. Occurrence of Ceratium furcoides (Levander Langhans 1925 (Dinophyceae: Ceratiaceae in Two Reservoirs of the Capibaribe Watershed Located in Semiarid Region | Ocorrência de Ceratium furcoides (Levander Langhans 1925 (Dinophyceae: Ceratiaceae em Dois Reservatórios da Baía de Capibaribe Localizada na Região Semiárida

    Directory of Open Access Journals (Sweden)

    Indira Maria Estolano Macedo

    2016-06-01

    Full Text Available (Occurrence of Ceratium furcoides (Levander Langhans 1925 (Dinophyceae: Ceratiaceae in Two Reservoirs of the Capibaribe Watershed Located in Semiarid Region. This study reported the first occurrence of Ceratium furcoides (Levander Langhans 1925 species in two eutrophic in the Capibaribe river basin (Pernambuco-Brazil, located in semiarid region. Fortnightly, samples were collected in the sub-surface reservoirs. The following abiotic variables were analyzed: pH, apparent color, turbidity, conductivity, total hardness, chlorides, ammonia, nitrate, nitrite, inorganic phosphate, iron, copper, manganese and zinc.  Phytoplankton biomass was quantified through its density. C. furcoides occurred in 17% of the samples in both reservoirs, and also presented high biomass (2.14 mm3.L-1 in Jucazinho and 4.04 mm3.L-1 in Toritama. The studied reservoirs are eutrophic and showed high concentrations of nutrients, particularly nitrite, as well as high conductivity and total hardness values.

  17. La marea roja causada por el dinoflagelado Alexandrium tamarense en la costa Pacífica colombiana (2001

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    Ingrid García-Hansen

    2004-09-01

    Full Text Available El 26 de marzo de 2001 se registró por primera vez en las aguas del Pacífico colombiano, en el área de la Ensenada de Tumaco, la aparición de una marea roja producida por la especie Alexandrium tamarense con valores que superaron las 7.5 x 10(6 céls l-1 , la marea se mantuvo hacia la región oceánica, derivando en sentido sur-norte por efecto de las corrientes, hasta ser vista por ultima vez cerca a la Isla Gorgona, casi tres semanas después. Un año mas tarde, en marzo de 2002, una segunda proliferación, conformada por la misma especie, se reportó cerca de Cabo Corrientes con una concentración de 1.6 x 10(6 céls l -1 . Ambos casos estuvieron relacionados con la presencia de bajas temperaturas en la superficie del mar y no estuvieron asociadas con fenómenos de intoxicación y mortalidadFrom April 26th to May 15th 2001, a large algae bloom was observed off Tumaco Bay on the Pacific coast of Colombia. This was the first harmful algae bloom (HAB reported in the region, and reached Gorgona Island, about 120 km north. Ayear later, starting March 2002, an offshore HAB developed from Cabo Corrientes North to Solano Bay. The typical abundance during the blooms reached 7.5 x 10(6 cells l-1 for the 2001 event and 1.6 x 10(6 cells l-1 for the 2002 event. During both events, low temperature and high salinity were recorded. Typical measurements in the area are 27-27.5°C and 30-31.5 psu. Values observed during the two events were 24-24.6°C and 33-34 psu; 3°C below normal and more than 2.5 psu above average values. These conditions are indicative of local upwelling processes at the time of the events. On both occasions, cells corresponding to the Alexandrium catenella/fundeyense/tamarense complex represented 99-100% of the biomass. It was difficult to differentiate the cells from A. catenella, but the presence of short chains of only 4 cells (single cells represented most of the biomass was suggestive of A. tamarense. Shape, dimensions, and

  18. Comparative Transcriptome Analysis of a Toxin-Producing Dinoflagellate Alexandrium catenella and Its Non-Toxic Mutant

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    Yong Zhang

    2014-11-01

    Full Text Available The dinoflagellates and cyanobacteria are two major kingdoms of life producing paralytic shellfish toxins (PSTs, a large group of neurotoxic alkaloids causing paralytic shellfish poisonings around the world. In contrast to the well elucidated PST biosynthetic genes in cyanobacteria, little is known about the dinoflagellates. This study compared transcriptome profiles of a toxin-producing dinoflagellate, Alexandrium catenella (ACHK-T, and its non-toxic mutant form (ACHK-NT using RNA-seq. All clean reads were assembled de novo into a total of 113,674 unigenes, and 66,812 unigenes were annotated in the known databases. Out of them, 35 genes were found to express differentially between the two strains. The up-regulated genes in ACHK-NT were involved in photosynthesis, carbon fixation and amino acid metabolism processes, indicating that more carbon and energy were utilized for cell growth. Among the down-regulated genes, expression of a unigene assigned to the long isoform of sxtA, the initiator of toxin biosynthesis in cyanobacteria, was significantly depressed, suggesting that this long transcript of sxtA might be directly involved in toxin biosynthesis and its depression resulted in the loss of the ability to synthesize PSTs in ACHK-NT. In addition, 101 putative homologs of 12 cyanobacterial sxt genes were identified, and the sxtO and sxtZ genes were identified in dinoflagellates for the first time. The findings of this study should shed light on the biosynthesis of PSTs in the dinoflagellates.

  19. Effect of oxidative stress induced by Brevibacterium sp. BS01 on a HAB causing species--Alexandrium tamarense.

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    Huajun Zhang

    Full Text Available Harmful algal blooms occur all over the world, destroying aquatic ecosystems and threatening other organisms. The culture supernatant of the marine algicidal actinomycete BS01 was able to lysis dinoflagellate Alexandrium tamarense ATGD98-006. Physiological and biochemical responses to oxidative stress in A. tamarense were investigated to elucidate the mechanism involved in BS01 inhibition of algal growth. Transmission electron microscope analysis revealed that there were some chloroplast abnormalities in response to BS01 supernatant. The decrease in cellular-soluble protein content suggested that cell growth was greatly inhibited at high concentration of BS01 supernatant. The increase in the levels of reactive oxygen species (ROS and malondialdehyde contents following exposure to BS01 supernatant indicated that algal cells suffered from oxidative damage. The content of pigment was significantly decreased after 12 h treatment, which indicated that the accumulation of ROS destroyed pigment synthesis. Moreover, the decrease of Fv/Fm ratio suggested that in the photosynthetic system, the dominant sites producing ROS were destroyed by the supernatant of the BS01 culture. The activities of the antioxidant enzymes including superoxide dismutase and peroxidase increased in a short time and decreased slightly with increasing exposure time. A real-time PCR assay showed changes in the transcript abundances of two photosynthetic genes, psbA and psbD. The results showed that BS01 supernatant reduced the expression of the psbA gene after 2 h exposure, but the expression of the psbD gene was increased at concentrations of 1.0 and 1.5%. Our results demonstrated that the expression of the psbA gene was inhibited by the BS01 supernatant, which might block the electron transport chain, significantly enhancing ROS level and excess activity of the antioxidant system. The accumulation of ROS destoryed pigment synthesis and membrane integrity, and inhibited or

  20. The physiological adaptations and toxin profiles of the toxic Alexandrium fundyense on the eastern Bering Sea and Chukchi Sea shelves.

    Science.gov (United States)

    Natsuike, Masafumi; Oikawa, Hiroshi; Matsuno, Kohei; Yamaguchi, Atsushi; Imai, Ichiro

    2017-03-01

    Abundant cyst distributions of the toxic dinoflagellate Alexandrium fundyense (previous A. tamarense north American clade) were recently observed on the north Chukchi Sea shelf and on the eastern Bering Sea shelf, suggesting that A. fundyense is both highly adapted to the local environments in the high latitude areas and might cause toxin contamination of plankton feeders. However, little is known about the physiological characteristics and toxin profiles of A. fundyense in these areas, which are characterized by low water temperatures, weak sunlight, and more or less permanent ice cover during winter. To clarify the physiological characteristics of A. fundyense, the effects of water temperature and light intensity on the vegetative growth and toxin profiles of this species were examined using A. fundyense strains isolated from one sediment sample collected from each area. Using the same sediments samples, seasonal changes of the cyst germination in different water temperatures were investigated. Vegetative cells grew at temperatures as low as 5°C and survived at 1°C under relatively low light intensity. They also grew at moderate water temperatures (10-15°C). Their cysts could germinate at low temperatures (1°C) and have an endogenous dormancy period from late summer to early spring, and warmer water temperatures (5-15°C) increased germination success. These physiological characteristics suggest that A. fundyense in the Chukchi Sea and eastern Bering Sea is adapted to the environments of high latitude areas. In addition, the results suggest that in the study areas A. fundyense has the potential to germinate and grow when water temperatures increase. Cellular toxin amounts of A. fundyense strains from the eastern Bering Sea and Chukchi Sea were ranged from 7.2 to 38.2 fmol cell -1 . These toxin amounts are comparable with A. fundyense strains isolated from other areas where PSP toxin contamination of bivalves occurs. The dominant toxin of the strains isolated

  1. Geographic structure evidenced in the toxic dinoflagellate Alexandrium pacificum Litaker (A. catenella - group IV (Whedon & Kofoid) Balech) along Japanese and Chinese coastal waters.

    Science.gov (United States)

    Genovesi, Benjamin; Berrebi, Patrick; Nagai, Satoshi; Reynaud, Nathalie; Wang, Jinhui; Masseret, Estelle

    2015-09-15

    The intra-specific diversity and genetic structure within the Alexandrium pacificum Litaker (A. catenella - Group IV) populations along the Temperate Asian coasts, were studied among individuals isolated from Japan to China. The UPGMA dendrogram and FCA revealed the existence of 3 clusters. Assignment analysis suggested the occurrence of gene flows between the Japanese Pacific coast (cluster-1) and the Chinese Zhejiang coast (cluster-2). Human transportations are suspected to explain the lack of genetic difference between several pairs of distant Japanese samples, hardly explained by a natural dispersal mechanism. The genetic isolation of the population established in the Sea of Japan (cluster-3) suggested the existence of a strong ecological and geographical barrier. Along the Pacific coasts, the South-North current allows limited exchanges between Chinese and Japanese populations. The relationships between Temperate Asian and Mediterranean individuals suggested different scenario of large-scale dispersal mechanisms. Copyright © 2015. Published by Elsevier Ltd.

  2. Outbreeding lethality between toxic Group I and nontoxic Group III Alexandrium tamarense spp. isolates: Predominance of heterotypic encystment and implications for mating interactions and biogeography

    Science.gov (United States)

    Brosnahan, Michael L.; Kulis, David M.; Solow, Andrew R.; Erdner, Deana L.; Percy, Linda; Lewis, Jane; Anderson, Donald M.

    2010-02-01

    We report the zygotic encystment of geographically dispersed isolates in the dinoflagellate species complex Alexandrium tamarense, in particular, successful mating of toxic Group I and nontoxic Group III isolates. However, hypnozygotes produced in Group I/III co-cultures complete no more than three divisions after germinating. Previous reports have suggested a mate recognition mechanism whereby hypnozygotes produced in co-cultures could arise from either homotypic (inbred) or heterotypic (outbred) gamete pairs. To determine the extent to which each occurs, a nested PCR assay was developed to determine parentage of individual hypnozygotes. The vast majority of hypnozygotes from pairwise Group I/III co-cultures were outbred, so that inviability was a result of hybridization, not inbreeding. These findings support the assertion that complete speciation underlies the phylogenetic structure of the Alexandrium tamarense species complex. Additionally, the ribosomal DNA (rDNA) copy numbers of both hybrid and single ribotype hypnozygotes were reduced substantially from those of haploid motile cells. The destruction of rDNA loci may be crucial for the successful mating of genetically distant conjugants and appears integral to the process of encystment. The inviability of Group I/III hybrids is important for public health because the presence of hybrid cysts may indicate ongoing displacement of a nontoxic population by a toxic one (or vice versa). Hybrid inviability also suggests a bloom control strategy whereby persistent, toxic Group I blooms could be mitigated by introduction of nontoxic Group III cells. The potential for hybridization in nature was investigated by applying the nested PCR assay to hypnozygotes from Belfast Lough, Northern Ireland, a region where Group I and III populations co-occur. Two hybrid cysts were identified in 14 successful assays, demonstrating that Group I and III populations do interbreed in that region. However, an analysis of mating data

  3. A Kinetic and Factorial Approach to Study the Effects of Temperature and Salinity on Growth and Toxin Production by the Dinoflagellate Alexandrium ostenfeldii from the Baltic Sea.

    Directory of Open Access Journals (Sweden)

    Pablo Salgado

    Full Text Available Alexandrium ostenfeldii is present in a wide variety of environments in coastal areas worldwide and is the only dinoflagellate known species that produces paralytic shellfish poisoning (PSP toxins and two types of cyclic imines, spirolides (SPXs and gymnodimines (GYMs. The increasing frequency of A. ostenfeldii blooms in the Baltic Sea has been attributed to the warming water in this region. To learn more about the optimal environmental conditions favoring the proliferation of A. ostenfeldii and its complex toxicity, the effects of temperature and salinity on the kinetics of both the growth and the net toxin production of this species were examined using a factorial design and a response-surface analysis (RSA. The results showed that the growth of Baltic A. ostenfeldii occurs over a wide range of temperatures and salinities (12.5-25.5°C and 5-21, respectively, with optimal growth conditions achieved at a temperature of 25.5°C and a salinity of 11.2. Together with the finding that a salinity > 21 was the only growth-limiting factor detected for this strain, this study provides important insights into the autecology and population distribution of this species in the Baltic Sea. The presence of PSP toxins, including gonyautoxin (GTX-3, GTX-2, and saxitoxin (STX, and GYMs (GYM-A and GYM-B/-C analogues was detected under all temperature and salinity conditions tested and in the majority of the cases was concomitant with both the exponential growth and stationary phases of the dinoflagellate's growth cycle. Toxin concentrations were maximal at temperatures and salinities of 20.9°C and 17 for the GYM-A analogue and > 19°C and 15 for PSP toxins, respectively. The ecological implications of the optimal conditions for growth and toxin production of A. ostenfeldii in the Baltic Sea are discussed.

  4. GROWTH AND PHOTOPROTECTION IN THREE DINOFLAGELLATES (INCLUDING TWO STRAINS OF ALEXANDRIUM TAMARENSE) AND ONE DIATOM EXPOSED TO FOUR WEEKS OF NATURAL AND ENHANCED ULTRAVIOLET-B RADIATION(1).

    Science.gov (United States)

    Laurion, Isabelle; Roy, Suzanne

    2009-02-01

    Long-term growth response to natural solar radiation with enhanced ultraviolet-B (UVB) exposure was examined in two species of dinoflagellates [Alexandrium tamarense (M. Lebour) Balech, At, and Heterocapsa triquetra (Ehrenb.) F. Stein, Ht], including two strains of A. tamarense, one from Spain and another from UK, and one diatom species (Thalassiosira pseudonana Hasle et Heimdal). We examined whether variable photoprotection (mycosporine-like amino acids [MAAs] and xanthophyll-cycle pigments) affected photosynthetic performance, phytoplankton light absorption, and growth. Growth rate was significantly reduced under enhanced UVB for the UK strain of At and for Ht (both grew very little) as well as for the diatom (that maintained high growth rates), but there was no effect for the Spanish strain of At. MAA concentration was high in the dinoflagellates, but undetectable in the diatom, which instead used the xanthophyll cycle for photoprotection. The highest cell concentrations of MAAs and photoprotective pigments were observed in the UK strain of At, along with lowest growth rates and Fv /Fm , indicating high stress levels. In contrast, the Spanish strain showed progressive acclimation to the experimental conditions, with no significant difference in growth between treatments. Increase in total MAAs followed linearly the cumulative UVB of the preceding day, and both total and primary MAAs were maintained at higher constitutive levels in this strain. Acclimation to enhanced UVB in the diatom resulted in an increase in PSII activity and reduction in nonphotochemical quenching, indicating an increased resistance to photoinhibition after a few weeks. All four species showed increased phytoplankton light absorption under enhanced UVB. Large intrastrain differences suggest a need to consider more closely intraspecific variability in UV studies. © 2009 Phycological Society of America.

  5. The use of fuzzy logic for data analysis and modelling of European ...

    African Journals Online (AJOL)

    The use of fuzzy logic for data analysis and modelling of European harmful algal blooms: results of the HABES project. ... African Journal of Marine Science ... Alexandrium minutum, Karenia mikimotoi and Phaeocystis globosa at various European sites as part of the Harmful Algal Blooms Expert System (HABES) project.

  6. Phylogenetic diversity of bacteria associated with toxic and non-toxic ...

    African Journals Online (AJOL)

    Phylogenetic diversity of bacteria associated with toxic and non-toxic strains of Alexandrium minutum. L Palacios, B Reguera, J Franco, I Marín. Abstract. Marine planktonic dinoflagellates are usually associated with bacteria, some of which seem to have a symbiotic relation with the dinoflagellate cells. The role of bacteria in ...

  7. Complexities of bloom dynamics in the toxic dinoflagellate Alexandrium fundyense revealed through DNA measurements by imaging flow cytometry coupled with species-specific rRNA probes

    Science.gov (United States)

    Brosnahan, Michael L.; Farzan, Shahla; Keafer, Bruce A.; Sosik, Heidi M.; Olson, Robert J.; Anderson, Donald M.

    2014-05-01

    Measurements of the DNA content of different protist populations can shed light on a variety of processes, including cell division, sex, prey ingestion, and parasite invasion. Here, we modified an Imaging FlowCytobot (IFCB), a custom-built flow cytometer that records images of microplankton, to measure the DNA content of large dinoflagellates and other high-DNA content species. The IFCB was also configured to measure fluorescence from Cy3-labeled rRNA probes, aiding the identification of Alexandrium fundyense (syn. A. tamarense Group I), a photosynthetic dinoflagellate that causes paralytic shellfish poisoning (PSP). The modified IFCB was used to analyze samples from the development, peak and termination phases of an inshore A. fundyense bloom (Salt Pond, Eastham, MA, USA), and from a rare A. fundyense ‘red tide’ that occurred in the western Gulf of Maine, offshore of Portsmouth, NH (USA). Diploid or G2 phase (‘2C’) A. fundyense cells were frequently enriched at the near-surface, suggesting an important role for aggregation at the air-sea interface during sexual events. Also, our analysis showed that large proportions of A. fundyense cells in both the Salt Pond and red tide blooms were planozygotes during bloom decline, highlighting the importance of sexual fusion to bloom termination. At Salt Pond, bloom decline also coincided with a dramatic rise in infections by the parasite genus Amoebophrya. The samples that were most heavily infected contained many large cells with higher DNA-associated fluorescence than 2C vegetative cells, but these cells' nuclei were also frequently consumed by Amoebophrya trophonts. Neither large cell size nor increased DNA-associated fluorescence could be replicated by infecting an A. fundyense culture of vegetative cells. Therefore, we attribute these characteristics of the large Salt Pond cells to planozygote maturation rather than Amoebophrya infection, though an interaction between infection and planozygote maturation may

  8. Susceptibilidad a la radiación ultravioleta_B del dinoflagelado Alexandrium catenella Kofoid Balech y de la diatomea Phaeodactylum tricornutum Bohlin Susceptibility to ultraviolet-B radiation of the dinoflagellate Alexandrium catenella Kofoid Balech, and the diatom Phaeodactylum tricornutum Bohlin

    Directory of Open Access Journals (Sweden)

    GINGER MARTINEZ

    2000-06-01

    Full Text Available La susceptibilidad diferencial de microalgas a la radiación UV-B (RUV-B, 280 - 320 nm genera patrones de predominio numérico dentro de los ensambles del fitoplancton. Sin embargo, a pesar que algunos eventos de floraciones algales nocivas (FAN del dinoflagelado Alexandrium catenella han sido coincidentes con episodios de alta RUV-B en el extremo sur de Chile, se desconoce alguna relación de causalidad entre estos procesos. A través de los parámetros poblacionales tasa intrínseca de crecimiento (µ y capacidad de carga (K, se determinó el efecto de la RUV-B sobre la dinámica poblacional de cultivos de A. catenella, la que fue comparada con la respuesta demográfica de cultivos de una diatomea susceptible a la RUV-B, Phaeodactylum tricornutum. Los resultados mostraron que ambas especies presentaron una disminución significativa de µ frente a un incremento de RUV-B. Sin embargo, mientras que la respuesta de A. catenella mostró una dosis umbral para el crecimiento, bajo la cual se obtuvo una disminución de µ hasta 0,03 d-1, P. tricornutum presentó un decrecimiento proporcional, hasta un mínimo de 0,34 d-1. A pesar que el parámetro K en ambas especies presentó un decrecimiento similar frente a un gradiente de RUV-B, A. catenella mostró una significativa inhibición a partir de 2,9 KJ m-2 d-1, a diferencia de P. tricornutum, donde K se afectó a dosis iguales o mayores a 4,1 KJ m-2 d-1. Contrario a la predicción, los resultados indican una mayor susceptibilidad en A. catenella que en P. tricornutum al aumento de dosis de RUV-B, lo cual otorga una débil causalidad a este factor en la determinación del patrón de predominio numérico presentado por A. catenella durante los eventos de FANDifferential susceptibility to ultraviolet B (UV-B, 280 - 320 nm radiation among microalgae generates patterns of dominance in phytoplankton assemblages. However, despite some events of harmful algal blooms (HAB's of the dinoflagellate Alexandrium

  9. Biosynthetic Studies of 13-Desmethylspirolide C Produced by Alexandrium ostenfeldii (= A. peruvianum): Rationalization of the Biosynthetic Pathway Following Incorporation of (13)C-Labeled Methionine and Application of the Odd-Even Rule of Methylation.

    Science.gov (United States)

    Anttila, Matthew; Strangman, Wendy; York, Robert; Tomas, Carmelo; Wright, Jeffrey L C

    2016-03-25

    Understanding the biosynthesis of dinoflagellate polyketides presents many unique challenges. Because of the remaining hurdles to dinoflagellate genome sequencing, precursor labeling studies remain the only viable way to investigate dinoflagellate biosynthesis. However, prior studies have shown that polyketide chain assembly does not follow any of the established processes. Additionally, acetate, the common precursor for polyketides, is frequently scrambled, thus compromising interpretation. These factors are further compounded by low production yields of the compounds of interest. A recent report on the biosynthesis of spirolides, a group belonging to the growing class of toxic spiroimines, provided some insight into the polyketide assembly process based on acetate labeling studies, but many details were left uncertain. By feeding (13)C methyl-labeled methionine to cultures of Alexandrium ostenfeldii, the producing organism of 13-desmethylspirolide C, and application of the odd-even methylation rule, the complete biosynthetic pathway has been established.

  10. Spatial and temporal variation of Peridinium umbonatum F. Stein, 1883 (Dinophyceae and its relationship with total phytoplankton of a shallow, oligotrophic lake in central Brazil (Lagoon Bonita, Distrito Federal Variação especial e temporal de Peridinium umbonatum F. Stein, 1883 (Dinophyceae e sua relação com o fitoplâncton total de uma lagoa rasa e oligotrófica no Brasil Central (Lagoa Bonita, Distrito Federal

    Directory of Open Access Journals (Sweden)

    Patrícia Pereira Gomes

    2010-09-01

    Full Text Available AIM: The main goal of this study was to investigate the temporal and spatial distribution of Peridinium umbonatum and its relationship with the physical and chemical water variables of the pelagic and littoral zones of Lagoon Bonita, located in Brasília, Distrito Federal; METHODS: Samples were collected at three stations: two in the littoral zone and one in the pelagic zone, every 15 days from April 2005 through March 2006; RESULTS: P. umbonatum was the only member of class Dinophyceae recorded during the entire seasonal cycle, with few exceptions, in both the littoral and pelagic zones of Lagoon Bonita. The highest biovolume (7.5 mm³.L-1 of this alga occurred near shore at the beginning of the rainy season, in November 2005. Smaller values of P. umbonatum biovolume were recorded in May and June 2005, typical dry months; CONCLUSIONS: P. umbonatum and the phytoplankton community as a whole had higher biovolumes in the two littoral zone sites, at the end of the dry season and the beginning of the rains. Both, the temporal and spatial scales were relevant in the presence of P. umbonatum, and the spatial heterogeneity was the dominant factor along the study period. The plant community structure, mainly submersed macrophytes, has affected the P. umbonatum population dynamics that took place at shallow, nutrient-poor conditions, small-size lake, which matches with habitat template described to Lo functional classification established by Reynolds et al. (2002.OBJETIVOS: O principal objetivo deste estudo foi investigar a distribuição temporal e espacial de Peridinium umbonatum e sua relação com as variáveis físicas e químicas da água das zonas pelágica e litorânea da Lagoa Bonita, localizada em Brasília, Distrito Federal; MÉTODOS: As amostras foram coletadas em três estações: duas na zona litorânea e uma na zona pelágica, a cada 15 dias, de abril de 2005 a março de 2006; RESULTADOS: P. umbonatum foi o único membro da classe

  11. Patrones de distribución espacial y temporal de floraciones de Alexandrium catenella (Whedon & Kofoid Balech 1985, en aguas interiores de la Patagonia noroccidental de Chile Spatial and temporal distribution patterns of blooms of Alexandrium catenella (Whedon & Kofoid Balech 1985, on inland seas of northwest Patagonia, Chile

    Directory of Open Access Journals (Sweden)

    CARLOS MOLINET

    2003-12-01

    Full Text Available La presencia del dinoflagelado tóxico Alexandrium catenella en las aguas interiores de la Patagonia noroccidental, fue registrada en la década de los 90. A partir de 1995 se iniciaron programas de monitoreo de fitoplancton orientados al seguimiento de este dinoflagelado y sus efectos sobre los mariscos en la Décima y Undécima Región de Chile, financiados por distintas instituciones. Esto permitió recolectar una importante base de datos, aunque incompleta en muchos aspectos debido a la independencia de objetivos de los diferentes estudios. En esta revisión se agruparon todos los datos disponibles para buscar patrones que ayuden a la formulación de hipótesis sobre la dispersión e incidencia espacial y temporal de A. catenella en esta amplia zona y mucho más habitada que la Duodécima Región. Inicialmente se recolectaron muestras mensuales y desde fines de 2000 semanales tanto de fitoplancton como de mariscos en un número de estaciones que varió cada año. Desde fines de 1995 al 2002 se registraron cuatro floraciones de A. catenella, con intensidad y distribución variable, observándose una expansión de la distribución geográfica de esta especie hacia el norte (desde aproximadamente 45° 47' S en 1996 a 42° S, Chiloé en 2002. Las cuatro floraciones registradas fueron marcadamente estacionales, concentradas entre los meses de enero a marzo y coincidieron con los máximos registros del veneno paralizante de los mariscos. Los datos analizados sugieren que el origen de las floraciones de A. catenella en las aguas interiores de la región estaría asociada a la presencia de bancos de quistes, cuyo ciclo de vida se expresa con una variación bianual debido a la variación en condiciones ambientales que favorecen la germinación de estos organismos. La influencia de oscilaciones en el océano adyacente que estarían afectando las características de circulación general de las aguas interiores y las características de la columna de

  12. Isolation and characterization of pigmented algicidal bacteria from seawater

    Science.gov (United States)

    Shaima, A.; Gires, U.; Asmat, A.

    2014-09-01

    Some dinoflagellate species are toxic and widely distributed in Malaysian marines ecosystems. They can cause many problems to aquatic life due to the production of various potential and natural toxins that accumulate in filter feeding shellfish and cause food poisoning to human. In recent decades, bacteria have been widely used as a biological control against these harmful algae. In the present study, pigmented bacteria isolated from marine water of Port Dickson beach was studied for their anti-algal activity towards toxic dinoflagellate Alexandrium minutum. Four isolates were studied and only one was capable of inhibiting algal growth when treated with bacterial culture. The algilytic effect on dinoflagellate was evaluated based on direct cell count under the microscope. Results showed that only isolate Sdpd-310 with orange colour has an inhibitory effect on A. minutum growth. This study demonstrated the rapid algicidal activity of a marine pigmented bacteria against the toxic dinoflagellate A. minutum.

  13. Paralytic shellfish poison algal biotoxins: Sardinia report 2002-2011 and non-compliance management

    Directory of Open Access Journals (Sweden)

    Giuseppa Lorenzoni

    2013-09-01

    Full Text Available Several microalgae of the genus Alexandrium (Alexandrium minutum and Alexandrium catenelle can produce an algal biotoxin, the paralytic shellfish poison (PSP that can be accumulated in the shellfish edible tissues making them hazardous to the consumer’s health. In this paper we report i the results of PSP toxins survey carried out by mouse bioassays (mouse test AOAC 958.08 on 7457 samples of bivalve molluscs farmed in Sardinia and in other European countries and marketed in Sardinia region from 2002 to 2011, and ii the management of positive cases. Based on our experience it is very important to strictly apply the planned activities in order to prevent any risk and to protect the consumer’s and producer’s health.

  14. The alga Trachydiscus minutus (Pseudostaurastrum minutum): growth and composition

    Czech Academy of Sciences Publication Activity Database

    Iliev, I.; Petkov, G.; Lukavský, Jaromír; Furnadzhieva, S.; Andreeva, R.; Bankova, V.

    2011-01-01

    Roč. 36, 3-4 (2011), 222-231 ISSN 1312-8183 R&D Projects: GA MŠk 1M0571 Institutional research plan: CEZ:AV0Z60050516 Keywords : algae, * fatty acids * pilot plant cultivation Subject RIV: EF - Botanics

  15. Bloom dynamics and life cycle strategies of two toxic dinoflagellates in a coastal upwelling system (NW Iberian Peninsula)

    Science.gov (United States)

    Bravo, Isabel; Fraga, Santiago; Isabel Figueroa, Rosa; Pazos, Yolanda; Massanet, Ana; Ramilo, Isabel

    2010-02-01

    A study of Gymnodinium catenatum and Alexandrium minutum blooms on the Galician coast was conducted from 2005 to 2007 in order to increase knowledge of the mechanisms governing recurrent blooms of these species. Considerable differences in their bloom dynamics were observed. G. catenatum blooms occurred in autumn and winter, following the pattern previously reported in the literature: they began off-shore and were advected to the Galician rias when a relaxation of the coastal upwelling occurred. On the other hand, A. minutum blooms developed inside embayments in spring and summer during the upwelling season and were associated with water stability and stratification. Both the vegetative population and the cyst distribution of A. minutum were related to less saline water from freshwater river outputs, which support a saline-gradient relationship postulated herein for this species. Dinoflagellates may produce both long-term double-walled cysts (resting) and short-term pellicle cysts. Resting cyst deposition and distribution in sediments showed that seeding occurred during the blooms of both species. However, the relationship between the cyst distribution in the sediments in Baiona Bay and the intensity and occurrence of G. catenatum blooms, suggests that the latter are not directly related to resting cyst germination. Moreover, the results presented in the present study point to other difference between the two species, such as the detection of pellicle cysts only for A. minutum. Finally, we discuss how the life cycle strategies of these two species may help to explain the different mechanisms of bloom formation reported herein.

  16. PSP toxin levels and plankton community composition and abundance in size-fractionated vertical profiles during spring/summer blooms of the toxic dinoflagellate Alexandrium fundyense in the Gulf of Maine and on Georges Bank, 2007, 2008, and 2010: 2. Plankton community composition and abundance.

    Science.gov (United States)

    Petitpas, Christian M; Turner, Jefferson T; Deeds, Jonathan R; Keafer, Bruce A; McGillicuddy, Dennis J; Milligan, Peter J; Shue, Vangie; White, Kevin D; Anderson, Donald M

    2014-05-01

    As part of the Gulf of Maine Toxicity (GOMTOX) project, we determined Alexandrium fundyense abundance, paralytic shellfish poisoning (PSP) toxin levels in various plankton size fractions, and the community composition of potential grazers of A. fundyense in plankton size fractions during blooms of this toxic dinoflagellate in the coastal Gulf of Maine and on Georges Bank in spring and summer of 2007, 2008, and 2010. PSP toxins and A. fundyense cells were found throughout the sampled water column (down to 50 m) in the 20-64 μm size fractions. While PSP toxins were widespread throughout all size classes of the zooplankton grazing community, the majority of the toxin was measured in the 20-64 μm size fraction. A. fundyense cellular toxin content estimated from field samples was significantly higher in the coastal Gulf of Maine than on Georges Bank. Most samples containing PSP toxins in the present study had diverse assemblages of grazers. However, some samples clearly suggested PSP toxin accumulation in several different grazer taxa including tintinnids, heterotrophic dinoflagellates of the genus Protoperidinium , barnacle nauplii, the harpacticoid copepod Microsetella norvegica , the calanoid copepods Calanus finmarchicus and Pseudocalanus spp., the marine cladoceran Evadne nordmanni , and hydroids of the genus Clytia . Thus, a diverse assemblage of zooplankton grazers accumulated PSP toxins through food-web interactions. This raises the question of whether PSP toxins pose a potential human health risk not only from nearshore bivalve shellfish, but also potentially from fish and other upper-level consumers in zooplankton-based pelagic food webs.

  17. Evolutionary Acquisition and Loss of Saxitoxin Biosynthesis in Dinoflagellates: the Second “Core” Gene, sxtG

    Science.gov (United States)

    Orr, Russell J. S.; Stüken, Anke; Murray, Shauna A.

    2013-01-01

    Saxitoxin and its derivatives are potent neurotoxins produced by several cyanobacteria and dinoflagellate species. SxtA is the initial enzyme in the biosynthesis of saxitoxin. The dinoflagellate full mRNA and partial genomic sequences have previously been characterized, and it appears that sxtA originated in dinoflagellates through a horizontal gene transfer from a bacterium. So far, little is known about the remaining genes involved in this pathway in dinoflagellates. Here we characterize sxtG, an amidinotransferase enzyme gene that putatively encodes the second step in saxitoxin biosynthesis. In this study, the entire sxtG transcripts from Alexandrium fundyense CCMP1719 and Alexandrium minutum CCMP113 were amplified and sequenced. The transcripts contained typical dinoflagellate spliced leader sequences and eukaryotic poly(A) tails. In addition, partial sxtG transcript fragments were amplified from four additional Alexandrium species and Gymnodinium catenatum. The phylogenetic inference of dinoflagellate sxtG, congruent with sxtA, revealed a bacterial origin. However, it is not known if sxtG was acquired independently of sxtA. Amplification and sequencing of the corresponding genomic sxtG region revealed noncanonical introns. These introns show a high interspecies and low intraspecies variance, suggesting multiple independent acquisitions and losses. Unlike sxtA, sxtG was also amplified from Alexandrium species not known to synthesize saxitoxin. However, amplification was not observed for 22 non-saxitoxin-producing dinoflagellate species other than those of the genus Alexandrium or G. catenatum. This result strengthens our hypothesis that saxitoxin synthesis has been secondarily lost in conjunction with sxtA for some descendant species. PMID:23335767

  18. Evolutionary acquisition and loss of saxitoxin biosynthesis in dinoflagellates: the second "core" gene, sxtG.

    Science.gov (United States)

    Orr, Russell J S; Stüken, Anke; Murray, Shauna A; Jakobsen, Kjetill S

    2013-04-01

    Saxitoxin and its derivatives are potent neurotoxins produced by several cyanobacteria and dinoflagellate species. SxtA is the initial enzyme in the biosynthesis of saxitoxin. The dinoflagellate full mRNA and partial genomic sequences have previously been characterized, and it appears that sxtA originated in dinoflagellates through a horizontal gene transfer from a bacterium. So far, little is known about the remaining genes involved in this pathway in dinoflagellates. Here we characterize sxtG, an amidinotransferase enzyme gene that putatively encodes the second step in saxitoxin biosynthesis. In this study, the entire sxtG transcripts from Alexandrium fundyense CCMP1719 and Alexandrium minutum CCMP113 were amplified and sequenced. The transcripts contained typical dinoflagellate spliced leader sequences and eukaryotic poly(A) tails. In addition, partial sxtG transcript fragments were amplified from four additional Alexandrium species and Gymnodinium catenatum. The phylogenetic inference of dinoflagellate sxtG, congruent with sxtA, revealed a bacterial origin. However, it is not known if sxtG was acquired independently of sxtA. Amplification and sequencing of the corresponding genomic sxtG region revealed noncanonical introns. These introns show a high interspecies and low intraspecies variance, suggesting multiple independent acquisitions and losses. Unlike sxtA, sxtG was also amplified from Alexandrium species not known to synthesize saxitoxin. However, amplification was not observed for 22 non-saxitoxin-producing dinoflagellate species other than those of the genus Alexandrium or G. catenatum. This result strengthens our hypothesis that saxitoxin synthesis has been secondarily lost in conjunction with sxtA for some descendant species.

  19. Life-cycle stages of Dinophysis acuminata (Dinophyceae) in the ...

    African Journals Online (AJOL)

    Despite many observations of different life-cycle stages of Dinophysis species, the complete life history of the genus is still unknown owing to the difficulties encountered in culturing these species. The seasonal distribution of D. acuminata was followed at two offshore stations in the brackish Baltic Sea by means of in situ ...

  20. The histones of the endosymbiont alga of Peridinium balticum (Dinophyceae).

    Science.gov (United States)

    Rizzo, P J; Morris, R L; Zweidler, A

    1988-01-01

    The histones of the endosymbiont nucleus of the binucleate dinoflagellate Peridinium balticum were characterized by amino acid analysis and peptide mapping, and compared to calf thymus histones. Using these and various other criteria we have identified two H1-like histones as well as the highly conserved histones H3 and H4. A 13,000 dalton component in sodium dodecyl sulphate (SDS) gels can be separated into two components in Triton-containing gels. We suggest that these histones (HPb1 and HPb2) correspond to the vertebrate histones H2A and H2B, respectively.

  1. Population genetics of reef coral endosymbionts (Symbiodinium, Dinophyceae).

    Science.gov (United States)

    Thornhill, D J; Howells, E J; Wham, D C; Steury, T D; Santos, S R

    2017-05-01

    Symbiodinium is a diverse genus of unicellular dinoflagellate symbionts associating with various marine protists and invertebrates. Although the broadscale diversity and phylogenetics of the Symbiodinium complex is well established, there have been surprisingly few data on fine-scale population structure and biogeography of these dinoflagellates. Yet population-level processes contribute strongly to the biology of Symbiodinium, including how anthropogenic-driven global climate change impacts these symbionts and their host associations. Here, we present a synthesis of population-level characteristics for Symbiodinium, with an emphasis on how phylogenetic affinities, dynamics within and among host individuals, and a propensity towards clonality shape patterns on and across reefs. Major inferences include the following: (i) Symbiodinium populations within individual hosts are comprised mainly of cells belonging to a single or few genetic clones. (ii) Symbiont populations exhibit a mixed mode of reproduction, wherein at least one sexual recombination event occurs in the genealogy between most genotypes, but clonal propagation predominates overall. (iii) Mutualistic Symbiodinium do not perpetually persist outside their hosts, instead undergoing turnover and replacement via the continuous shedding of viable clonal cells from host individuals. (iv) Symbiont populations living in the same host, but on different reefs, are often genetically subdivided, suggesting low connectivity, adaptation to local conditions, or prolific asexual reproduction and low effective population sizes leading to disproportionate success within and among hosts. Overall, this synthesis forms a basis for future investigations of coral symbiosis ecology and evolution as well as delimitation of species boundaries in Symbiodinium and other eukaryotic microorganisms. © 2017 John Wiley & Sons Ltd.

  2. Redescription of Gymnodinium heterostriatum Kofoid et Swezy 1921 (Dinophyceae)

    Science.gov (United States)

    Elbrächter, M.

    1994-12-01

    The dinoflagellate Gymnodinium heterostriatum Kofoid et Swezy is described anew from live material of the upwelling region off the NW African coast. The characteristics that distinguish it from Gymnodinium striatissimum Hulburt, a species with which it has been mistaken since the original description, are discussed.

  3. An ultrastructural and ecological study of Ceratium hirundinella (Dinophyceae)

    OpenAIRE

    Chapman, Deborah Vivien

    1981-01-01

    Vegetative cells of Ceratium hirundinella taken from Esthwaite Water, a small productive lake in the English Lake District, were studied each month by scanning and transmission electron microscopy. Changes in size and abundance of chloroplasts and their lamellar spacing was shown to be related to their exposure to light within the lake. Changes in the quantities of starch and lipid present were mainly related to cyst formation or recent excystment. Excystment and encystment were studied by li...

  4. Noctiluca Scintillans (Dinophyceae) in Central Coastal Waters of ...

    African Journals Online (AJOL)

    A one-year study (July 2003 – June 2004) to explore the spatial and temporal variability of potentially harmful dinoflagellates was carried out in the central coastal waters of Tanzania. During the course of the study a green dinoflagellate, Noctiluca scintillans, which has cosmopolitan distribution, was encountered for the first ...

  5. Mixotrophy and Nitrogen Uptake by Pfiesteria Piscicida (Dinophyceae)

    Science.gov (United States)

    Alan J. Lewitus; Bonnie M. Willis; Kenneth C. Hayes; JoAnn M. Burkholder; Howard B. Gasgow; Patricia M. Gilbert

    1999-01-01

    The nutritional versatility of dinoflagellates is a complicating factor in identifying potential links between nutrient eurichment and the proliferation of harmful algal bloom. For exmaple, although dinoflagellates associated with hamful algal blooms (e.g. red tides) are generally considered to be phototrophic and we inorganic nutrients such as nitrate or phosphate,...

  6. Synonymy and biogeography of the dinoflagellate genus Histioneis (Dinophysiales: Dinophyceae

    Directory of Open Access Journals (Sweden)

    Fernando Gómez

    2007-06-01

    Full Text Available The genus Histioneis (=Parahistioneis contains an excessive number of poorly described species, often based on the observation of a single specimen and ignoring the intraspecific variability. In order to investigate the validity of the species and to suggest synonyms, the original illustrations of all known species of Histioneis are reproduced and grouped based on the morphological similarity. The scarce records and the uncertainties on the identification at the species level are responsible of the lack of biogeographical information. Large and highly ornamented species tended to appear in tropical waters, whereas smaller and less ornamented species showed a wider distribution and they can also found in temperate waters such as the Mediterranean Sea. Rev. Biol. Trop. 55 (2: 459-477. Epub 2007 June, 29.El género Histioneis (=Parahistioneis tiene una cantidad excesiva de especies, descritas insuficientemente y a menudo a partir de un solo espécimen, ignorando la variabilidad intra-específica. Con el objetivo de investigar la validez de las especies y sugerir sinónimos, aquí se presentan las ilustraciones originales de Histioneis agrupadas según su parecido morfológico. Las escasas observaciones de Histioneis y las dudas en la identificación a nivel de especie son responsables de la falta de información sobre su distribución geográfica. Las especies de mayor tamaño y más ornamentadas son típicas de aguas tropicales. Las especies más pequeñas y menos ornamentadas presentan una distribución más amplia y pueden encontrarse también en aguas templadas, como el Mar Mediterráneo.

  7. Ship traffic and the introduction of diatoms and dinoflagellates via ballast water in the port of Annaba, Algeria

    Science.gov (United States)

    Cheniti, Radhia; Rochon, André; Frihi, Hocine

    2018-03-01

    We present here the first study on the role of ship traffic in the introduction of potentially harmful and/or non-indigenous species in the port of Annaba (Algeria). A total of 25 ships of two different types (general cargo and bulk carriers) were sampled and separated into two categories: oceanic and Mediterranean ships. We estimated propagule pressure of high-risk coastal phytoplankton delivered in ballast water to the port of Annaba. We identified 40 diatom and 38 dinoflagellate taxa, among which, 11 harmful/toxic taxa: Pseudo-nitzschia spp., Alexandrium tamarense, Alexandrium sp., Dinophysis acuminata, Dinophysis rotundata, Dinophysis sp., Gonyaulax spinifera, Gymnodinium catenatum, Lingulodinium polyedrum, Protoceratium reticulatum and cyst of Alexandrium sp. In addition, 8 taxa (5 diatoms, 1 dinoflagellate and 2 dinoflagellate cysts) never observed in the Annaba region were considered as potentially non-indigenous: Actinoptychus splendens, Coscinodiscus asteromphalus, Coscinodiscus lineatus, Odentella granulata, Thalassiosira cf. decipiens, Prorocentrum scutellum, cyst of Polykrikos kofoidii and Islandinium minutum. Several factors were examined, including ship routes, ballast water age and the volume of ballast water discharged. Our analyses revealed that diatom and dinoflagellate abundances decreased with ballast water age, possibly as a result of mortality of species due to voyage length and lack of light in ballast tanks. Estimates of actual propagule pressure, diatoms and dinoflagellates abundances varied from 1 to 4 × 108 cells/ship. The results of this study could serve as the baseline for the development and implementation of monitoring and ballast water management programs in ports of Algeria.

  8. Salmon mortalities associated with a bloom of Alexandrium ...

    African Journals Online (AJOL)

    Blue mussels Mytilus edulis analysed from areas affected by the bloom reached levels of 18 000ìg STX equivalents 100g–1 of tissue. As a result of the salmon mortalities, a project was initiated to establish a monitoring approach for harmful algal blooms to provide an early warning of potential events and to act as a tool for ...

  9. Glutathione transferase activity and oocyte development in copepods exposed to toxic phytoplankton

    DEFF Research Database (Denmark)

    Kozlowsky-Suzuki, Betina; Koski, Marja; Hallberg, Eric

    2009-01-01

    toxins generally observed in copepods. In addition, decreasing gross growth efficiency (GGE) of copepods with increasing concentration of toxic diets could be caused either by a high expenditure coping with toxins (e.g., increase in the activity of detoxification enzymes) or by a deterioration...... of reproductive tissues. To assess the effect of toxic phytoplankton on the activity of detoxification enzymes and on oocyte maturation of Acartia tonsa and Temora longicornis, feeding and egg production experiments were carried out with a variety of toxic diets and an adequate non-toxic food control (Rhodomonas...... spp.) all provided as single species diets. Toxic diets included the nodularin-producing cyanobacterium Nodularia spumigena, the dinoflagellates Alexandrium minutum, and A. tamarense, which contained Paralytic Shellfish Poisoning (PSP) toxins, the dinoflagellate Prorocentrum lima with Diarrhetic...

  10. Dinoflagellate cysts from surface sediments of Syracuse Bay (Western Ionian Sea, Mediterranean)

    Science.gov (United States)

    Rubino, Fernando; Belmonte, Manuela; Caroppo, Carmela; Giacobbe, Mariagrazia

    2010-02-01

    The occurrence and abundance of dinoflagellate cysts were investigated for the first time at an Ionian locality along the south-eastern coast of Sicily, subject to spring-summer harmful algal events. Thirty-four cyst morphotypes were recognized belonging to 24 taxa identified at least at the genus level. Cyst abundance in surface sediments ranged from 43 to 828 cysts g -1 dry weight, with the highest numbers recorded at the most restricted station. Germination experiments allowed confirmation of species identification determined by cyst analysis and provided clonal cultures of Alexandrium minutum and Gymnodinium nolleri, two of the bloom-forming species in the area. This represents the first record of G. nolleri for the Mediterranean Sea.

  11. Algicidal Effects of a Novel Marine Pseudoalteromonas Isolate (Class Proteobacteria, Gamma Subdivision) on Harmful Algal Bloom Species of the Genera Chattonella, Gymnodinium, and Heterosigma

    Science.gov (United States)

    Lovejoy, Connie; Bowman, John P.; Hallegraeff, Gustaaf M.

    1998-01-01

    During a bacterial survey of the Huon Estuary in southern Tasmania, Australia, we isolated a yellow-pigmented Pseudoalteromonas strain (class Proteobacteria, gamma subdivision), designated strain Y, that had potent algicidal effects on harmful algal bloom species. This organism was identified by 16S rRNA sequencing as a strain with close affinities to Pseudoalteromonas peptidysin. This bacterium caused rapid cell lysis and death (within 3 h) of gymnodinoids (including Gymnodinium catenatum) and raphidophytes (Chattonella marina and Heterosigma akashiwo). It caused ecdysis of armored dinoflagellates (e.g., Alexandrium catenella, Alexandrium minutum, and Prorocentrum mexicanum), but the algal cultures then recovered over the subsequent 24 h. Strain Y had no effect on a cryptomonad (Chroomonas sp.), a diatom (Skeletonema sp.), a cyanobacterium (Oscillatoria sp.), and two aplastidic protozoans. The algicidal principle of strain Y was excreted into the seawater medium and lost its efficacy after heating. Another common bacterial species, Pseudoalteromonas carrageenovora, was isolated at the same time and did not have these algicidal effects. The minimum concentrations of strain Y required to kill G. catenatum were higher than the mean concentrations found in nature under nonbloom conditions. However, the new bacterium showed a chemotactic, swarming behavior that resulted in localized high concentrations around target organisms. These observations imply that certain bacteria could play an important role in regulating the onset and development of harmful algal blooms. PMID:9687434

  12. Optimal N:P ratios of growth media: quantification of nutrient-replete growth rates in five ion hyperspace for Chlorella vulgaris (Dinophyceae) and Peridinium cinctum (Dinophyceae).

    Science.gov (United States)

    In this study our principal goal was to quantify the main effects and interactions of several primary nutrient and bulk solution ions. The total ion concentration range chosen spans fresh to brackish waters (1-30 milliMolar) and explores most of the hypervolume delineated by the five ion/concentrat...

  13. A search for mixotrophy and mucus trap production in Alexandrium spp. and the dynamics of mucus trap formation in Alexandrium pseudogonyaulax

    DEFF Research Database (Denmark)

    Blossom, Hannah Eva; Bædkel, Tina Dencker; Tillmann, Urban

    2017-01-01

    , such as speed and frequency of trap formation as well as what happens to the trap after the A. pseudogonyaulax cell detaches from it. The percentage of A. pseudogonyaulax cells producing a mucus trap and the number of prey cells caught increased with increasing prey concentration, whereas the physical size...... of the traps was independent of prey concentration. In one strain given an excess of prey, within 1 h over 90% of individual A. pseudogonyaulax cells had formed a trap, each containing an average of 45 prey cells. Individual A. pseudogonyaulax cells steadily produced traps and up to 5 traps were produced...

  14. Differences in pigmentation between life cycle stages in Scrippsiella lachrymosa (dinophyceae).

    Science.gov (United States)

    Persson, Agneta; Smith, Barry C; Cyronak, Tyler; Cooper, Emily; DiTullio, Giacomo R

    2016-02-01

    Various life cycle stages of cyst-producing dinoflagellates often appear differently colored under the microscope; gametes appear paler while zygotes are darker in comparison to vegetative cells. To compare physiological and photochemical competency, the pigment composition of discrete life cycle stages was determined for the common resting cyst-producing dinoflagellate Scrippsiella lachrymosa. Vegetative cells had the highest cellular pigment content (25.2 ± 0.5 pg · cell(-1) ), whereas gamete pigment content was 22% lower. The pigment content of zygotes was 82% lower than vegetative cells, even though they appeared darker under the microscope. Zygotes of S. lachrymosa contained significantly higher cellular concentrations of β-carotene (0.65 ± 0.15 pg · cell(-1) ) than all other life stages. Photoprotective pigments and the de-epoxidation ratio of xanthophylls-cycle pigments in S. lachrymosa were significantly elevated in zygotes and cysts compared to other stages. This suggests a role for accessory pigments in combating intracellular oxidative stress during sexual reproduction or encystment. Resting cysts contained some pigments even though chloroplasts were not visible, suggesting that the brightly colored accumulation body contained photosynthetic pigments. The differences in pigmentation between life stages have implications for interpretation of pigment data from field samples when sampled during dinoflagellate blooms. © 2015 Phycological Society of America.

  15. Especies de dinoflagelados del género Gambierdiscus (Dinophyceae del Mar Caribe mexicano

    Directory of Open Access Journals (Sweden)

    D.U Hernández-Becerril

    2004-09-01

    Full Text Available Algunos dinoflagelados de hábitos bénticos están relacionados con la ciguatera, por consumo de pescado, en áreas tropicales. En el Caribe mexicano la ciguatera es un padecimiento relativamente común, sin embargo solo existe un trabajo sobre este tema y muy pocos antecedentes publicados sobre fitoplancton y microalgas bénticas. En este estudio se analizó material recolectado en varios puntos a lo largo de las costas del Estado de Quintana Roo, tanto con red de fitoplancton (54 mm, como de sedimento y epífitas de plantas macroscópicas, para estudiar los dinoflagelados tóxicos y asociados. Se registra la presencia de tres especies del género Gambierdiscus, asociadas con la producción de toxinas causantes de la ciguatera: G. belizeanus, G. toxicus y G. yasumotoi, todas distribuídas en áreas costeras poco profundas, incluyendo lagunas costeras. Las especies han sido estudiadas con microscopía de luz y electrónica de barrido. Para el reconocimiento de las especies se emplearon los caracteres morfológicos usuales, pero eventualmente se pueden usar caracteres fisiológicos, ecológicos y moleculares. La llamada "comunidad ciguatoxigénica" también está formada por especies de los géneros Prorocentrum, Ostreopsis y Coolia, cuyo estudio florístico y taxonómico se recomienda ampliamente, así como investigaciones complementarias de aspectos biológicos, ecológicos, fisiológicos y epidemiológicos de esta comunidad

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

    Directory of Open Access Journals (Sweden)

    UDHI EKO HERNAWAN

    2008-01-01

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

  17. Microsatellite markers for the palaeo-temperature indicator Pentapharsodinium dalei (Dinophyceae)

    DEFF Research Database (Denmark)

    Lundholm, Nina; Nielsen, Lene Rostgaard; Ribeiro, Sofia

    2014-01-01

    Pentapharsodinium dalei is a widely distributed cold-water dinoflagellate, which is used in palaeoecology as an indicator of relatively warmer conditions in polar and subpolar regions. This species has been proposed to be one of the first indicators of global warming at high latitudes.We developed...... dinucleotide polymorphic microsatellite markers were developed as multiplex polymerase chain reactions and were genotyped in 32 strains. The number of alleles per locus varied between 4 and 12, and the estimated gene diversity varied from 0.588 to 0.891. The haploid state of the vegetative cells was confirmed...

  18. Influence of Environmental Variables on Gambierdiscus spp. (Dinophyceae Growth and Distribution.

    Directory of Open Access Journals (Sweden)

    Yixiao Xu

    Full Text Available Benthic dinoflagellates in the genus Gambierdiscus produce the ciguatoxin precursors responsible for the occurrence of ciguatera toxicity. The prevalence of ciguatera toxins in fish has been linked to the presence and distribution of toxin-producing species in coral reef ecosystems, which is largely determined by the presence of suitable benthic habitat and environmental conditions favorable for growth. Here using single factor experiments, we examined the effects of salinity, irradiance, and temperature on growth of 17 strains of Gambierdiscus representing eight species/phylotypes (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, G. pacificus, G. silvae, Gambierdiscus sp. type 4-5, most of which were established from either Marakei Island, Republic of Kiribati, or St. Thomas, United States Virgin Island (USVI. Comparable to prior studies, growth rates fell within the range of 0-0.48 divisions day(-1. In the salinity and temperature studies, Gambierdiscus responded in a near Gaussian, non-linear manner typical for such studies, with optimal and suboptimal growth occurring in the range of salinities of 25 and 45 and 21.0 and 32.5°C. In the irradiance experiment, no mortality was observed; however, growth rates at 55 μmol photons · m(-2 · s(-1 were lower than those at 110-400 μmol photons · m(-2 · s(-1. At the extremes of the environmental conditions tested, growth rates were highly variable, evidenced by large coefficients of variability. However, significant differences in intraspecific growth rates were typically found only at optimal or near-optimal growth conditions. Polynomial regression analyses showed that maximum growth occurred at salinity and temperature levels of 30.1-38.5 and 23.8-29.2°C, respectively. Gambierdiscus growth patterns varied among species, and within individual species: G. belizeanus, G. caribaeus, G. carpenteri, and G. pacificus generally exhibited a wider range of tolerance to environmental conditions, which may explain their broad geographic distribution. In contrast, G. silvae and Gambierdiscus sp. types 4-5 all displayed a comparatively narrow range of tolerance to temperature, salinity, and irradiance.

  19. Bloom of the Yessotoxin producing dinoflagellate Protoceratium reticulatum (Dinophyceae) in Northern Chile

    Science.gov (United States)

    Álvarez, Gonzalo; Uribe, Eduardo; Díaz, Rosario; Braun, Mauricio; Mariño, Carmen; Blanco, Juan

    2011-05-01

    In summer 2007, a dinoflagellate preliminarily identified as Protoceratium reticulatum bloomed in Bahía Mejillones, northern Chile. Phytoplankton samples were analyzed in detail by light and scanning electron microscopy revealing the presence of resting cyst and motile cells of P. reticulatum. Oceanographic and phytoplankton data suggest that the bloom was initiated offshore by motile cells and germinated cysts during an upwelling pulse. These cells were advected into the bay when upwelling relaxed and grew without any relevant competitor. Phytoplankton net samples were found to contain yessotoxin as the only toxin in an estimated proportion of 0.2 and 0.4 pg cell - 1 , thus confirming that P. reticulatum is a source of yessotoxin in northern Chilean waters and consequently that it poses a risk for human health and mollusk exploitation in the area.

  20. dinoref: A curated dinoflagellate (Dinophyceae) reference database for the 18S rRNA gene.

    Science.gov (United States)

    Mordret, Solenn; Piredda, Roberta; Vaulot, Daniel; Montresor, Marina; Kooistra, Wiebe H C F; Sarno, Diana

    2018-03-30

    Dinoflagellates are a heterogeneous group of protists present in all aquatic ecosystems where they occupy various ecological niches. They play a major role as primary producers, but many species are mixotrophic or heterotrophic. Environmental metabarcoding based on high-throughput sequencing is increasingly applied to assess diversity and abundance of planktonic organisms, and reference databases are definitely needed to taxonomically assign the huge number of sequences. We provide an updated 18S rRNA reference database of dinoflagellates: dinoref. Sequences were downloaded from genbank and filtered based on stringent quality criteria. All sequences were taxonomically curated, classified taking into account classical morphotaxonomic studies and molecular phylogenies, and linked to a series of metadata. dinoref includes 1,671 sequences representing 149 genera and 422 species. The taxonomic assignation of 468 sequences was revised. The largest number of sequences belongs to Gonyaulacales and Suessiales that include toxic and symbiotic species. dinoref provides an opportunity to test the level of taxonomic resolution of different 18S barcode markers based on a large number of sequences and species. As an example, when only the V4 region is considered, 374 of the 422 species included in dinoref can still be unambiguously identified. Clustering the V4 sequences at 98% similarity, a threshold that is commonly applied in metabarcoding studies, resulted in a considerable underestimation of species diversity. © 2018 John Wiley & Sons Ltd.

  1. Unusual blooms of green Noctiluca miliaris (Dinophyceae) in the Arabian Sea during the winter monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Gomes, H.R.; Matondkar, S.G.P.; Parab, S.G.; Goes, J.I.; Pednekar, S.; Al-Azri, A.R.N.; Thoppil, P.G.

    A large-scale, ongoing study conducted by the National Institute of Oceanography, India, from 2003 onward in support of India’s ocean color program, has documented for the first time ever the appearance of extensive blooms of Noctiluca miliaris...

  2. Molecular phylogeny of the parasitic dinoflagellate Chytriodinium within the Gymnodinium clade (Gymnodiniales, Dinophyceae)

    DEFF Research Database (Denmark)

    Gómez, Fernando; Skovgaard, Alf

    2015-01-01

    for the Atlantic Chytriodinium sp. The first complete small subunit ribosomal DNA (SSU rDNA) of the Atlantic Chytriodinium sp. suggests that the specimens belong to an undescribed species. This is the first evidence of the split of the Gymnodinium clade: one for the parasitic forms of Chytriodiniaceae...

  3. Allelopathic effect of Chattonella marina var. marina (Raphidophyceae) on Gymnodinium catenatum (Dinophycea).

    Science.gov (United States)

    Fernández-Herrera, Leyberth J; Band-Schmidt, Christine J; López-Cortés, David J; Hernández-Guerrero, Claudia J; Bustillos-Guzmán, José J; Núñez-Vázquez, Erick

    2016-01-01

    The allelopathic effect of the raphidophyte Chattonella marina var. marina on the dinoflagellate Gymnodinium catenatum was determined. Both species are harmful algal bloom forming algae, produce toxic metabolites, and can co-exist in the environment. In general, raphidophytes tend to dominate over dinoflagellates, which may indicate an allelopathic effect of the former algae. Strains of C. marina var. marina and G. catenatum isolated from Bahía de La Paz were cultured in bi-algal cultures with and without cell contact. Additionally, cultures of G. catenatum were exposed to cell-free culture filtrates of the raphidophyte to test whether soluble allelopathic molecules are active. During late stationary phase, both species were cultivated in mixed cultures for 72h using the following cell abundance proportions: 20×10 3 cellsL -1 : 20×10 3 cellsL -1 (1:1; G. catenatum: C. marina); 10×10 3 cellsL -1 : 20×10 3 cellsL -1 (1:2), and 20×10 3 cellsL -1 : 10×10 3 cellsL -1 (2:1). Cells of G. catenatum were also exposed to different volumes of cell filtrates of C. marina (10, 20, and 50mL) using the same cell abundance proportions for 24h. Samples were taken daily for cell counts and microscopic observations. Growth inhibition was higher when there was cell contact between both species, however mortality of G. catenatum was also observed without direct cell contact, indicating that toxic metabolites are liberated to the culture medium. Changes in cell morphology of G. catenatum occurred in the presence of cells and filtrates of C. marina, such as loss of flagella and motility, swelling, loss of girdle and sulci, prominent nucleus, rupture of cell membrane, and cell lysis. Induction of temporary cysts was also observed. These results suggest that toxic metabolites are liberated to the medium by C. marina, affecting G. catenatum by inhibiting its growth and causing changes in its life history, providing new insights of interactions between raphidophytes and dinoflagellates that could happen in the natural environment when both species are present. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Phylogeny of five species of Nusuttodinium gen. nov. (Dinophyceae), a genus of unarmoured kleptoplastidic dinoflagellates.

    Science.gov (United States)

    Takano, Yoshihito; Yamaguchi, Haruyo; Inouye, Isao; Moestrup, Øjvind; Horiguchi, Takeo

    2014-12-01

    Cells of five unarmoured kleptoplastidic dinoflagellates, Amphidinium latum, Amphidinium poecilochroum, Gymnodinium amphidinioides, Gymnodinium acidotum and Gymnodinium aeruginosum were observed under light and/or scanning electron microscopy and subjected to single-cell PCR. The SSU rDNA and the partial LSU rDNA of all the examined species were sequenced, and the SSU rDNA of G. myriopyrenoides was sequenced. Phylogenetic analyses revealed that the unarmoured kleptoplastidic species formed a monophyletic clade within the Gymnodinium-clade sensu Daugbjerg et al. (2000). The sister taxa for this clade were Gymnodinium palustre and Spiniferodinium galeiforme, both of which possess brown-coloured chloroplasts. The results indicated that acquisition of kleptoplastidy in these unarmoured dinoflagellates was a single event and that these unarmoured kleptoplastidic dinoflagellates may have evolved from a form with permanent chloroplasts. Molecular trees suggested that the acquisition of kleptoplastidy took place in a marine habitat and later some species colonized the freshwater habitat. Because these unarmoured kleptoplastidic dinoflagellates are monophyletic and characterized by distinct morphological and cytological features (including the presence of the same type of apical groove, absence of nuclear chambers in the nuclear envelope, absence of genuine chloroplasts, and the possession of kleptochloroplasts), we propose the establishment of a new genus, Nusuttodinium, to accommodate all these dinoflagellates. Copyright © 2014 Elsevier GmbH. All rights reserved.

  5. Systematics of a kleptoplastidal dinoflagellate, Gymnodinium eucyaneum Hu (Dinophyceae), and its cryptomonad endosymbiont.

    Science.gov (United States)

    Xia, Shuang; Zhang, Qi; Zhu, Huan; Cheng, Yingyin; Liu, Guoxiang; Hu, Zhengyu

    2013-01-01

    New specimens of the kleptoplastidal dinoflagellate Gymnodinium eucyaneum Hu were collected in China. We investigated the systematics of the dinoflagellate and the origin of its endosymbiont based on light morphology and phylogenetic analyses using multiple DNA sequences. Cells were dorsoventrally flattened with a sharply acute hypocone and a hemispherical epicone. The confusion between G. eucyaneum and G. acidotum Nygaard still needs to be resolved. We found that the hypocone was conspicuously larger than the epicone in most G. eucyaneum cells, which differed from G. acidotum, but there were a few cells whose hypocone and epicone were of nearly the same size. In addition, there was only one site difference in the partial nuclear LSU rDNA sequences of a sample from Japan given the name G. acidotum and G. eucyaneum in the present study, which suggest that G. eucyaneum may be a synonym of G. acidotum. Spectroscopic analyses and phylogenetic analyses based on nucleomorph SSU rDNA sequences and chloroplast 23 s rDNA sequences suggested that the endosymbiont of G. eucyaneum was derived from Chroomonas (Cryptophyta), and that it was most closely related to C. coerulea Skuja. Moreover, the newly reported kleptoplastidal dinoflagellates G. myriopyrenoides and G. eucyaneum in our study were very similar, and the taxonomy of kleptoplastidal dinoflagellates was discussed.

  6. ALGICIDAL BACTERIA ACTIVE AGAINST GYMNODINIUM BREVE (DINOPHYCEAE). BACTERIAL ISOLATION AND CHARACTERIZATION OF KILLING ACTIVITY. (R827085)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  7. Influence of static magnetic fields in phototaxis and osmotic stress in Gymnodinium catenatum (Dinophyceae).

    Science.gov (United States)

    Vale, Paulo

    2017-07-01

    Phototaxis response of the toxic microalgae Gymnodinium catenatum was studied in vitro. The percentage of cells remaining at mid-depth 20 min after stirring increased with solar radio, X-ray and solar flares output. It also increased with geomagnetic activity and temperature, and was dependent on culture time. Increase in the local static magnetic field with a permanent magnet did not influence the positive phototaxis response. However, survival and growth to a provoked hypo-osmotic shock in an altered static magnetic field was dependent on culture time and geomagnetic activity at a threshold below 22 nT. The results from phototaxis and hypo-osmotic shock experiments were in line with the previous hypothesis for the existence of two separate deleterious mechanisms conditioning the natural blooms of G. catenatum: one that is dependent on solar radiation and the other that is related to geomagnetic activity. Variations in electromagnetic fields caused by tectonic activity were also capable of influencing G. catenatum phototaxis and growth response in vitro.

  8. [Modeling the occurrence of shellfish poisoning outbreaks caused by Gymnodinium catenatum (Dinophyceae) through electromagnetic signal triggering].

    Science.gov (United States)

    Vale, Pulo

    2014-01-01

    Accumulation of paralytic shellfish poisoning toxins (PSTs) in bivalves attributed to Gymnodinium catenatum blooms at the NW Portuguese coast was previously associated with periods of low solar activity (measured by the radio flux [R]), or low geomagnetic A(a) index. It was also observed that reduction of R preceded the occurrence of toxin accumulation, while A(a) index increase could be related to its absence during periods of low activity. For modeling toxin accumulation, the monthly decrease in R was studied along the decade 2003-2012. A match that helped explaining the highly toxic years of 2007 and 2008 was obtained by plotting the formula: ΔR = (R(n-1) - R(n))/(R(n) - 65)2, where 65 represented the lowest radio activity known to date. The complex denominator was required to take into account the sunspot cycle. A 1-2 month lag was observed between maximal relative decline and maximal PSTs accumulation. PSTs in bivalves from the Portuguese south coast were related with natural electromagnetic cycles for the first time, and were not statistically associated with low R. A statistically significant association with low A(a) index also was not achieved, due to the low number of occurrences, although the 25-75 percentile was restricted to low Aa indexes in a similar way to that found for the NW coast. PSTs accumulation outside solar minima could be triggered by a steep decline in the A(a) index (ΔA), but no lag was observed in this case. While ΔR amplitude helped explaining the highly toxic years of 2007 and 2008 at the NW coast, the amplitude of ΔA was not related to the severity of the accumulation. Other kind of local electromagnetic signaling was investigated resorting to the occurrence of seismologic phenomena, because these events can trigger electric activities. No statistical association was found between seism number or magnitude and PSTs at the south coast, located near the boundary between the African and Eurasian plates, and marked by moderate seismicity.

  9. Can Mycosporine-Like Amino Acids Act as Multifunctional Compounds in Gymnodinium catenatum (Dinophyceae)?

    Science.gov (United States)

    Vale, Paulo

    2016-03-01

    MAAs originating from Gymnodinium catenatum were subjected to H 2 O 2 oxidation, light and heat. Shinorine and porphyra-334 were the more resistant to all treatments, mycosporine-glycine (MYGL) was the least resistant to oxidation and heat, whereas palythene and M-370 were the least resistant to light. MYGL and M-311 were similarly resistant to photodegradation and oxidation in the dark and low temperature, but M-311 was more resistant to oxidation under light or heat. The ratio M-370/M-365 changed from 29:1 to 6:1 ratio after 240 h of exposure to fluorescent light, indicating that M-365 could represent the M-370 cis-isomer. The role of MAAs as antioxidants and/or osmolytes was evaluated by studying effects of abrupt salinity reduction. Both increases or decreases in concentrations were observed and were dependent on the MAA initial concentration and its chemical structure. The relative increase in MAAs with a known antioxidant capacity (MYGL, palythene) followed an exponential decay trend related to initial concentration. The relative decrease in highly polar MAAs (shinorine, porphyra-334, M-332) with a suspected osmolyte role followed a rise to a maximum with the increase in initial concentration. Whether or not MAAs play a significant role in osmoregulation, their loss can occur upon hypoosmotic shock. © 2016 The American Society of Photobiology.

  10. Kleptochloroplast Enlargement, Karyoklepty and the Distribution of the Cryptomonad Nucleus in Nusuttodinium (= Gymnodinium) aeruginosum (Dinophyceae).

    Science.gov (United States)

    Onuma, Ryo; Horiguchi, Takeo

    2015-05-01

    The unarmoured freshwater dinoflagellate Nusuttodinium (= Gymnodinium) aeruginosum retains a cryptomonad-derived kleptochloroplast and nucleus, the former of which fills the bulk of its cell volume. The paucity of studies following morphological changes to the kleptochloroplast with time make it unclear how the kleptochloroplast enlarges and why the cell ultimately loses the cryptomonad nucleus. We observed, both at the light and electron microscope level, morphological changes to the kleptochloroplast incurred by the enlargement process under culture conditions. The distribution of the cryptomonad nucleus after host cell division was also investigated. The volume of the kleptochloroplast increased more than 20-fold, within 120h of ingestion of the cryptomonad. Host cell division was not preceded by cryptomonad karyokinesis so that only one of the daughter cells inherited a cryptomonad nucleus. The fate of all daughter cells originating from a single cell through five generations was closely monitored, and this observation revealed that the cell that inherited the cryptomonad nucleus consistently possessed the largest kleptochloroplast for that generation. Therefore, this study suggests that some important cryptomonad nucleus division mechanism is lost during ingestion process, and that the cryptomonad nucleus carries important information for the enlargement of the kleptochloroplast. Copyright © 2015 Elsevier GmbH. All rights reserved.

  11. Resistance to Hydrogen Peroxide Highlights Gymnodinium catenatum (Dinophyceae) Sensitivity to Geomagnetic Activity.

    Science.gov (United States)

    Vale, Paulo

    2018-01-01

    The chain-forming dinoflagellate Gymnodinium catenatum was exposed to hydrogen peroxide. Microscopical examination revealed striking dose-response alterations in chain formation above 245 μm: singlets replaced the dominance of long chain formations. These observations were valid for cells acclimated to halogen light. Under fluorescent light, cells were more resistant to modifications in chain length after H 2 O 2 exposure. Growth along 9 h in the presence of extracellular H 2 O 2 followed an hormesis response in both light regimes. Under halogen light conditions, alterations in chain formation and net growth were related to culture time, inocula concentration and geomagnetic activity (GMA) in the proceeding hours. Below a 16 nT threshold in GMA average growth was 0%, while above 16 nT it was circa +9%, independently if the local static magnetic field was altered by a permanent magnet or not. Mycosporine-like amino acids that can have an antioxidant role and are easily oxidized decreased from 7.1 to 6.5 pg cell -1 (P < 0.05) under halogen light and exposure to 245 μm H 2 O 2 . GMA, as well as UV-A, increased stress responsiveness that can momentarily protect cells from extracellular H 2 O 2 addition. However, stress response is dependent on bio-availability of several micronutrients and macronutrients, many found at limiting concentrations in oceanic waters. © 2017 The American Society of Photobiology.

  12. Molecular phylogeny of the ocelloid-bearing dinoflagellates erythropsidinium and warnowia (warnowiaceae, dinophyceae).

    Science.gov (United States)

    Gómez, Fernando; López-García, Purificación; Moreira, David

    2009-01-01

    Members of the family Warnowiaceae are unarmored phagotrophic dinoflagellates that possess an ocelloid. The genus Erythropsidinium (=Erythropsis) has also developed a unique dynamic appendage, the piston, which is able to independently retract and extend for at least 2 min after the cell lyses. We provide the first small subunit ribosomal RNA gene sequences of warnowiid dinoflagellates, those of the type Erythropsidinium agile and one species of Warnowia. Phylogenetic analyses show that warnowiid dinoflagellates branch within the Gymnodinium sensu stricto group, forming a cluster separated from the Polykrikos clade and with autotrophic Pheopolykrikos beauchampii as closest relative. This reinforces their classification as unarmored dinoflagellates based on the shape of the apical groove, despite the strong ecological and ultrastructural diversity of the Gymnodinium s.s. group. Other structures, such as the ocelloid and piston, have no systematic value above the genus level.

  13. ULTRASTRUCTURE OF GYMNODINIUM AUREOLUM (DINOPHYCEAE): TOWARD A FURTHER REDEFINITION OF GYMNODINIUM SENSU STRICTO

    DEFF Research Database (Denmark)

    Hansen, Gert

    2001-01-01

    Examination of the ultrastucture of the unarmored dinoflagellate Gymnodinium aureolum (Hulburt) G. Hansen (syn: Gyrodinium aureolum Hulburt) revealed the presence of nuclear chambers, which are specialized differentiations of the nuclear envelope, similar to those described in the type species...... of Gymnodinium, G. fuscum (Ehrenberg) Stein and certain other Gymnodinium species. The nuclear pores were restricted to these chambers. In the flagellar apparatus a nuclear fibrous connective linked the longitudinal microtubular root and the nucleus. This structure had so far been observed only in Gymnodinium...... in Ceratium furca (Ehrenberg) Claparède et Lachmann and C. tripos (O.F. Müller) Nitzsch. Gymnodinium aureolum also possessed a prominent ventral protrusion associated with the peduncle and containing electron opaque material. It is concluded that G. aureolum belongs to the Gymnodinium sensu stricto group...

  14. THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM (DINOPHYCEAE) REQUIRES MARINE BACTERIA FOR GROWTH(1).

    Science.gov (United States)

    Bolch, Christopher J S; Subramanian, Thaila A; Green, David H

    2011-10-01

    Interactions with the bacterial community are increasingly considered to have a significant influence on marine phytoplankton populations. Here we used a simplified dinoflagellate-bacterium experimental culture model to conclusively demonstrate that the toxic dinoflagellate Gymnodinium catenatum H. W. Graham requires growth-stimulatory marine bacteria for postgermination survival and growth, from the point of resting cyst germination through to vegetative growth at bloom concentrations (10(3)  cells · mL(-1) ). Cysts of G. catenatum were germinated and grown in unibacterial coculture with antibiotic-resistant or antibiotic-sensitive Marinobacter sp. DG879 or Brachybacterium sp., and with mixtures of these two bacteria. Addition of antibiotics to cultures grown with antibiotic-sensitive strains of bacteria resulted in death of the dinoflagellate culture, whereas cultures grown with antibiotic-resistant bacteria survived antibiotic addition and continued to grow beyond the 21 d experiment. Removal of either bacterial type from mixed-bacterial dinoflagellate cultures (using an antibiotic) resulted in cessation of dinoflagellate growth until bacterial concentration recovered to preaddition concentrations, suggesting that the bacterial growth factors are used for dinoflagellate growth or are labile. Examination of published reports of axenic dinoflagellate culture indicate that a requirement for bacteria is not universal among dinoflagellates, but rather that species may vary in their relative reliance on, and relationship with, the bacterial community. The experimental model approach described here solves a number of inherent and logical problems plaguing studies of algal-bacterium interactions and provides a flexible and tractable tool that can be extended to examine bacterial interactions with other phytoplankton species. © 2011 Phycological Society of America.

  15. Molecular Phylogeny of the Parasitic Dinoflagellate Chytriodinium within the Gymnodinium Clade (Gymnodiniales, Dinophyceae).

    Science.gov (United States)

    Gómez, Fernando; Skovgaard, Alf

    2015-01-01

    The dinoflagellate genus Chytriodinium, an ectoparasite of copepod eggs, is reported for the first time in the North and South Atlantic Oceans. We provide the first large subunit rDNA (LSU rDNA) and Internal Transcribed Spacer 1 (ITS1) sequences, which were identical in both hemispheres for the Atlantic Chytriodinium sp. The first complete small subunit ribosomal DNA (SSU rDNA) of the Atlantic Chytriodinium sp. suggests that the specimens belong to an undescribed species. This is the first evidence of the split of the Gymnodinium clade: one for the parasitic forms of Chytriodiniaceae (Chytriodinium, Dissodinium), and other clade for the free-living species. © 2014 The Author(s) Journal of Eukaryotic Microbiology © 2014 International Society of Protistologists.

  16. Systematics of a kleptoplastidal dinoflagellate, Gymnodinium eucyaneum Hu (Dinophyceae, and its cryptomonad endosymbiont.

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    Shuang Xia

    Full Text Available New specimens of the kleptoplastidal dinoflagellate Gymnodinium eucyaneum Hu were collected in China. We investigated the systematics of the dinoflagellate and the origin of its endosymbiont based on light morphology and phylogenetic analyses using multiple DNA sequences. Cells were dorsoventrally flattened with a sharply acute hypocone and a hemispherical epicone. The confusion between G. eucyaneum and G. acidotum Nygaard still needs to be resolved. We found that the hypocone was conspicuously larger than the epicone in most G. eucyaneum cells, which differed from G. acidotum, but there were a few cells whose hypocone and epicone were of nearly the same size. In addition, there was only one site difference in the partial nuclear LSU rDNA sequences of a sample from Japan given the name G. acidotum and G. eucyaneum in the present study, which suggest that G. eucyaneum may be a synonym of G. acidotum. Spectroscopic analyses and phylogenetic analyses based on nucleomorph SSU rDNA sequences and chloroplast 23 s rDNA sequences suggested that the endosymbiont of G. eucyaneum was derived from Chroomonas (Cryptophyta, and that it was most closely related to C. coerulea Skuja. Moreover, the newly reported kleptoplastidal dinoflagellates G. myriopyrenoides and G. eucyaneum in our study were very similar, and the taxonomy of kleptoplastidal dinoflagellates was discussed.

  17. Balechina and the New Genus Cucumeridinium Gen. Nov. (Dinophyceae), Unarmored Dinoflagellates with Thick Cell Coverings

    Science.gov (United States)

    Gómez, Fernando; López-García, Purificación; Takayama, Haruyoshi; Moreira, David

    2016-01-01

    The genus Balechina (=subgenus Pachydinium) was established for heterotrophic gymnodinioid dinoflagellates with a thick cell covering. The type species, B. pachydermata (=Gymnodinium pachydermatum), showed numerous fine longitudinal striae, whereas B. coerulea (=G. coeruleum) showed ~24 prominent longitudinal surface ridges or furrows and a distinctive blue pigmentation. We have investigated the morphology and molecular phylogeny of these taxa and the species Gymnodinium cucumis, G. lira and G. amphora from the western Mediterranean, Brazil and Japan. Sudden contractions at the cingulum level were seen in B. pachydermata, which also showed a high morphological variability which included morphotypes that have been described as Amphidinium vasculum, G. amphora, G. dogielii and G. gracile sensu Kofoid and Swezy. Molecular phylogeny based on small subunit rRNA gene sequences revealed that Balechina coerulea, G. cucumis and G. lira formed a clade distantly related to the clade of the type species, B. pachydermata, and G. amphora. We propose the new genus Cucumeridinium for the species with longitudinal ridges and a circular apical groove (Cucumeridinium coeruleum comb. nov., C. lira comb. nov. and C. cucumis comb. nov.), and Gymnodinium canus and G. costatum are considered synonyms of C. coeruleum. The genus Balechina remains for the species with a double-layer cell covering, bossed surface with fine striae, and an elongated elliptical apical groove. At present, the genus is monotypic containing only B. pachydermata. PMID:26987004

  18. Morphological transition in kleptochloroplasts after ingestion in the dinoflagellates Amphidinium poecilochroum and Gymnodinium aeruginosum (Dinophyceae).

    Science.gov (United States)

    Onuma, Ryo; Horiguchi, Takeo

    2013-09-01

    The unarmoured marine dinoflagellate Amphidinium poecilochroum and the unarmoured freshwater dinoflagellate Gymnodinium aeruginosum both belonging to the same clade, are known to possess cryptomonad-derived kleptochloroplasts. Previous studies revealed that G. aeruginosum can synchronise the division of the chloroplast with its own cell division while no simultaneous division takes place in A. poecilochroum, which is interpreted to mean that state of kleptochloroplastidy in G. aeruginosum is closer to that of the initial acquisition of the 'true chloroplast' within the lineage. Although the general ultrastructure of these two species has been reported, the changes in the kleptochloroplast with time have never been followed. We observed morphological changes in kleptochloroplasts of A. poecilochroum and G. aeruginosum following the ingestion of cryptomonad cells, using light and transmission electron microscopes. In A. poecilochroum, the cryptomonad ejectosomes, mitochondria and cytoplasm were all actively transferred into digestive vacuoles within 1h of ingestion. The chloroplasts were deformed and the cryptomonad nucleus was digested after 3h. By contrast, in G. aeruginosum, the cryptomonad cytoplasm and nucleus were retained for 24h following ingestion, and the chloroplast was substantially enlarged. These differences imply that the retention of the cryptomonad nucleus is important for the maintenance of the chloroplast. Copyright © 2013 Elsevier GmbH. All rights reserved.

  19. Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians.

    Science.gov (United States)

    Yuasa, Tomoko; Horiguchi, Takeo; Mayama, Shigeki; Takahashi, Osamu

    2016-02-01

    The symbiotic dinoflagellate Gymnoxanthella radiolariae T. Yuasa et T. Horiguchi gen. et sp. nov. isolated from polycystine radiolarians is described herein based on light, scanning and transmission electron microscopy as well as molecular phylogenetic analyses of SSU and LSU rDNA sequences. Motile cells of G. radiolariae were obtained in culture, and appeared to be unarmored. The cells were 9.1-11.4 μm long and 5.7-9.4 μm wide, and oval to elongate oval in the ventral view. They possessed an counterclockwise horseshoe-shaped apical groove, a nuclear envelope with vesicular chambers, cingulum displacement with one cingulum width, and the nuclear fibrous connective; all of these are characteristics of Gymnodinium sensu stricto (Gymnodinium s.s.). Molecular phylogenetic analyses also indicated that G. radiolariae belongs to the clade of Gymnodinium s.s. However, in our molecular phylogenetic trees, G. radiolariae was distantly related to Gymnodinium fuscum, the type species of Gymnodinium. Based on the consistent morphological, genetic, and ecological divergence of our species with the other genera and species of Gymnodinium s.s., we considered it justified to erect a new, separate genus and species G. radiolariae gen. et sp. nov. As for the peridinioid symbiont of radiolarians, Brandtodinium has been erected as a new genus instead of Zooxanthella, but the name Zooxanthella is still valid. Brandtodinium is a junior synonym of Zooxanthella. Our results suggest that at least two dinoflagellate symbiont species, peridinioid Zooxanthella nutricula and gymnodinioid G. radiolariae, exist in radiolarians, and that they may have been mixed and reported as "Z. nutricula" since the 19th century. © 2016 Phycological Society of America.

  20. Influence of solar and geomagnetic activity in Gymnodinium catenatum (Dinophyceae) cultures.

    Science.gov (United States)

    Vale, Paulo

    2017-01-01

    Laboratory cultures of the paralytic shellfish poisoning producing microalga Gymnodinium catenatum were subjected to a hypo-osmotic shock and changes in cell concentration were observed in two separate experiments of 8 and 24 hours duration, respectively. The increase in geomagnetic activity (GMA), radio and X-ray fluxes and solar X-ray flares were negatively correlated with cell numbers. Cell losses were observed in the short experiment, but not in the longest one. GMA action was related to the course of the experimental period, while electromagnetic radiation (EMR) was only significantly related when the previous hours before the experiments were considered. The differential action windows might be indicative of two differential disruptive mechanisms: EMR might act on DNA synthesis and mitosis phases of the cell cycle (taking place in the dark period) and GMA might be more disruptive at the end of mytosis or cytokinesis phases taking place in the light period. Formation of long chains (> 4 cells/chain) was reduced with salinity and with temperatures above 27ºC but increased with EMR and GMA, particularly when grown at the highest temperatures recorded during the study period (≥28ºC).

  1. Quantitative proteomic analysis of cell cycle of the dinoflagellate Prorocentrum donghaiense (Dinophyceae.

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    Da-Zhi Wang

    Full Text Available Dinoflagellates are the major causative agents of harmful algal blooms in the coastal zone, which has resulted in adverse effects on the marine ecosystem and public health, and has become a global concern. Knowledge of cell cycle regulation in proliferating cells is essential for understanding bloom dynamics, and so this study compared the protein profiles of Prorocentrum donghaiense at different cell cycle phases and identified differentially expressed proteins using 2-D fluorescence difference gel electrophoresis combined with MALDI-TOF-TOF mass spectrometry. The results showed that the synchronized cells of P. donghaiense completed a cell cycle within 24 hours and cell division was phased with the diurnal cycle. Comparison of the protein profiles at four cell cycle phases (G1, S, early and late G2/M showed that 53 protein spots altered significantly in abundance. Among them, 41 were identified to be involved in a variety of biological processes, e.g. cell cycle and division, RNA metabolism, protein and amino acid metabolism, energy and carbon metabolism, oxidation-reduction processes, and ABC transport. The periodic expression of these proteins was critical to maintain the proper order and function of the cell cycle. This study, to our knowledge, for the first time revealed the major biological processes occurring at different cell cycle phases which provided new insights into the mechanisms regulating the cell cycle and growth of dinoflagellates.

  2. First record of Lophodinium polylophum (Daday Lemmermann 1910 (Dinophyceae: Lophodiniaceae in Peru

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    Iris Samanez

    2015-04-01

    Full Text Available Herein, the first record of Lophodinium polylophum from Peru is presented. This fresh water dinoflagellate was identified in plankton samples from the lagoon Picoplancha of Santuario Nacional Pampas del Heath (Madre de Dios and from a stream in the Puinahua River basin in Loreto.

  3. The Gonyaulax spinifera (Dinophyceae) "complex": Perpetuating the paradox?

    DEFF Research Database (Denmark)

    Rochon, André; Lewis, Jane; Ellegaard, Marianne

    2009-01-01

    Specimens of dinoflagellate cysts referable to the cyst-species Spiniferites ramosus (Ehrenberg 1838) Mantell 1854 and Nematosphaeropsis labyrinthus (Ostenfeld 1903) Reid 1974 have been produced in the same crossed-strain of Gonyaulax spinifera-type (Claparède and Lachmann 1857) Diesing 1866 moti...

  4. Morphology and rDNA phylogeny of a Mediterranean Coolia monotis (Dinophyceae strain from Greece

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    Nicolas P. Dolapsakis

    2006-03-01

    Full Text Available Sequences of LSU and SSU ribosomal RNA genes and phylogeny have not been widely investigated for the dinoflagellate Coolia monotis Meunier, and no information is available on the small and large rDNA subunits of Mediterranean strains. A strain isolated from the Thermaikos Gulf in northern Greece was identified as C. monotis—a new record for the Greek algal flora—using thecal morphology by light, epifluorescence and scanning electron microscopy. The small subunit and partial (D1/D2 large subunit sequences were analyzed and compared to other strains of C. monotis and dinoflagellates from various regions. Thecal architecture showed that the Greek strain of C. monotis was phenotypically similar, but not identical, to other strains reported in literature. The partial LSU sequence (700 bp was found to vary by 113 bp positions (16% from the C. monotis strain from New Zealand, whereas the SSU (1757 bp had 15 bp differences (0.85% from the strain from Norway. Phylogenetic tree construction showed that the Greek strain fell within the Coolia clade and had a close relationship with the families Ostreopsidaceae and Goniodomaceae of the order Gonyaulacales. Preliminary findings suggest the existence of different genotype strains of C. monotis with large intraspecific genetic variability and minimal morphological differentiation (similar phenotypes. Certain ecological and evolutionary implications of these findings are discussed.

  5. The Ecology, Life History, and Phylogeny of the Marine Thecate Heterotrophic Dinoflagellates Protoperidinium and Diplopsalidaceae (Dinophyceae)

    Science.gov (United States)

    2006-09-01

    specimens, appeared to be identical to Actinophrys sol and other distinct protist species (as discussed in Coats 2002). Being unaware of the...hypothesizes that photosynthetic eukaryotes evolved through a series of symbiotic relationships between heterotrophic protists and autotrophic prokaryotes...species or genus level. Athecate dinoflagellates were not well preserved by formalin-fixation, and thus were not counted. Metazoans and protists

  6. Trojan Horse Strategy for Non-invasive Interference of Clock Gene in the Oyster Crassostrea gigas.

    Science.gov (United States)

    Payton, Laura; Perrigault, Mickael; Bourdineaud, Jean-Paul; Marcel, Anjara; Massabuau, Jean-Charles; Tran, Damien

    2017-08-01

    RNA interference is a powerful method to inhibit specific gene expression. Recently, silencing target genes by feeding has been successfully carried out in nematodes, insects, and small aquatic organisms. A non-invasive feeding-based RNA interference is reported here for the first time in a mollusk bivalve, the pacific oyster Crassostrea gigas. In this Trojan horse strategy, the unicellular alga Heterocapsa triquetra is the food supply used as a vector to feed oysters with Escherichia coli strain HT115 engineered to express the double-stranded RNA targeting gene. To test the efficacy of the method, the Clock gene, a central gene of the circadian clock, was targeted for knockout. Results demonstrated specific and systemic efficiency of the Trojan horse strategy in reducing Clock mRNA abundance. Consequences of Clock disruption were observed in Clock-related genes (Bmal, Tim1, Per, Cry1, Cry2, Rev.-erb, and Ror) and triploid oysters were more sensitive than diploid to the interference. This non-invasive approach shows an involvement of the circadian clock in oyster bioaccumulation of toxins produced by the harmful alga Alexandrium minutum.

  7. Risk associated with toxic blooms of marine phytoplankton functional groups on Artemia franciscana

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    Ana D’ors

    2014-08-01

    Full Text Available Objective: To study mortality of copepod Artemia franciscana against the occurrence of harmful marine algae and possible toxicological changes exhibited by binary and tertiary combinations of these harmful algae toxins. Methods: Tweenty four hours acute toxicity assays were performed with selected concentrations of Alexandrium minutum, Prorocentrum lima and Nitzschia N1c1 living cells. Additionally, the results were analyzed using the median-effect/combination index (CI-isobologram equation to assess possible changes in the toxic effect induced by phytoplankton functional groups. Results: Biotoxin equivalent values obtained by immunodetection were (2.12±0.10, (8.60±1.30 and (4.32±1.67 pg/cell for saxitoxin, okadaic acid and domoic acid, respectively. The 24-h LC50 values estimated to saxitoxin and okadaic acid equivalents were 4.06 and 6.27 µg/L, significantly below the value obtained for Nitzschia N1c1, which was established at 467.33 µg/L. CI analysis applied on phytoplankton assemblages showed that both ternary mixture as the binary combinations exhibited antagonic action on toxic effects in Artemia nauplii, which were significantly lower than the toxic effect exhibited by each species studied. Conclusions: These results show that, although these harmful algae represent a serious risk to estuarine zooplankton community, the presence of phytoplankton functional groups within the same bloom can reduce the potential risk compared to the expected risk when each of the phytoplankton groups are evaluated individually.

  8. Dinoflagellate cyst abundance is positively correlated to sediment organic carbon in Sydney Harbour and Botany Bay, NSW, Australia.

    Science.gov (United States)

    Tian, Chang; Doblin, Martina A; Dafforn, Katherine A; Johnston, Emma L; Pei, Haiyan; Hu, Wenrong

    2018-02-01

    There is growing public concern about the global expansion of harmful algal bloom species (HABs), with dinoflagellate microalgae comprising the major portion of the harmful taxa. These motile, unicellular organisms have a lifecycle involving sexual reproduction and resting cyst formation whereby cysts can germinate from sediments and 'seed' planktonic populations. Thus, investigation of dinoflagellate cyst (dinocyst) distribution in sediments can provide significant insights into HAB dynamics and contribute to indices of habitat quality. Species composition and abundance of dinocysts in relation to sediment characteristics were studied at 18 stations in two densely populated temperate Australian estuaries, Sydney Harbour (Parramatta River/Port Jackson; PS) and Botany Bay (including Georges River; GB). Eighteen dinocyst taxa were identified, dominated by Protoceratium reticulatum and Gonyaulax sp.1 in the PS estuary, together with Archaeperidinium minutum and Gonyaulax sp.1 in the GB estuary. Cysts of Alexandrium catenella, which is one of the causative species of paralytic shellfish poisoning (PSP), were also detected in both estuaries. Out of the measured sediment characteristics (TOC, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn and polycyclic aromatic hydrocarbons), TOC was the parameter explaining most of the variation in dinocyst assemblages and was positively correlated to most of the heavy metals. Given the significant relationship between sediment TOC and dinocyst abundance and heavy metal concentrations, this study suggests that sediment TOC could be broadly used in risk management for potential development of algal blooms and sediment contamination in these estuaries.

  9. Molecular phylogeny of selected species of the order Dinophysiales (Dinophyceae) - testing the hypothesis of a Dinophysioid radiation

    DEFF Research Database (Denmark)

    Jensen, Maria Hastrup; Daugbjerg, Niels

    2009-01-01

    additional information on morphology and ecology to these evolutionary lineages. We have for the first time combined morphological information with molecular phylogenies to test the dinophysioid radiation hypothesis in a modern context. Nuclear-encoded LSU rDNA sequences including domains D1-D6 from 27...

  10. Patterns of Symbiodinium (Dinophyceae) diversity and assemblages among diverse hosts and the coral reef environment of Lizard Island, Australia

    KAUST Repository

    Ziegler, Maren; Stone, Elizabeth; Colman, Daniel; Takacs-Vesbach, Cristina; Shepherd, Ursula

    2018-01-01

    careful evaluation. Of the less abundant OTUs, roughly half occurred at only one site or in one species and the background Symbiodinium communities were distinct between individual samples. We conclude that sampling multiple host taxa with differing life

  11.  Serial replacement of diatom endosymbiont in two freshwater dinoflagellates, Peridiniopsis spp., (Peridiniales, Dinophyceae)

    DEFF Research Database (Denmark)

    Takano, Y.; Hansen, Gert; Fujita, D.

    2008-01-01

    Two freshwater armoured dinoflagellates, Peridiniopsis cf. kevei from Japan and Peridiniopsis penardii from Japan and Italy, were examined by means of light, scanning and transmission electron microscopy. Morphological studies indicated that the two dinoflagellates had similar type of cellular......-harbouring dinoflagellates. On the contrary, the phylogenetic analyses based on plastid-encoded rbcL and nuclear-encoded SSU rDNA of the endosymbionts included the endosymbiont of these two freshwater dinoflagellates in the Thalassiosira/Skeletonema-clade (Centrales), whereas the endosymbionts of other diatom...

  12. High genetic diversity and fine-scale spatial structure in the marine flagellate Oxyrrhis marina (Dinophyceae uncovered by microsatellite loci.

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    Chris D Lowe

    2010-12-01

    Full Text Available Free-living marine protists are often assumed to be broadly distributed and genetically homogeneous on large spatial scales. However, an increasing application of highly polymorphic genetic markers (e.g., microsatellites has provided evidence for high genetic diversity and population structuring on small spatial scales in many free-living protists. Here we characterise a panel of new microsatellite markers for the common marine flagellate Oxyrrhis marina. Nine microsatellite loci were used to assess genotypic diversity at two spatial scales by genotyping 200 isolates of O. marina from 6 broad geographic regions around Great Britain and Ireland; in one region, a single 2 km shore line was sampled intensively to assess fine-scale genetic diversity. Microsatellite loci resolved between 1-6 and 7-23 distinct alleles per region in the least and most variable loci respectively, with corresponding variation in expected heterozygosities (H(e of 0.00-0.30 and 0.81-0.93. Across the dataset, genotypic diversity was high with 183 genotypes detected from 200 isolates. Bayesian analysis of population structure supported two model populations. One population was distributed across all sampled regions; the other was confined to the intensively sampled shore, and thus two distinct populations co-occurred at this site. Whilst model-based analysis inferred a single UK-wide population, pairwise regional F(ST values indicated weak to moderate population sub-division (0.01-0.12, but no clear correlation between spatial and genetic distance was evident. Data presented in this study highlight extensive genetic diversity for O. marina; however, it remains a substantial challenge to uncover the mechanisms that drive genetic diversity in free-living microorganisms.

  13. Fukuyoa paulensis gen. et sp. nov., a new genus for the globular species of the dinoflagellate Gambierdiscus (Dinophyceae.

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    Fernando Gómez

    Full Text Available The marine epiphytic dinoflagellate Gambierdiscus is a toxicologically important genus responsible for ciguatera fish poisoning, the principal cause of non-bacterial illness associated with fish consumption. The genus currently contains species exhibiting either globular or anterior-posteriorly compressed morphologies with marked differences in cell shape and plate arrangement. Here we report a third globular, epiphytic and tychoplanktonic species from the coasts of Ubatuba, Brazil. The new species can be distinguished from G. yasumotoi and G. ruetzleri by its broader first apical plate that occupies a larger portion of the epitheca. Accordingly, phylogenetic trees from small subunit (SSU and large subunit (LSU ribosomal DNA sequences also showed strongly supported separation of the new species from the G. yasumotoi/G. ruetzleri group albeit with short distance. The molecular phylogenies, which included new sequences of the planktonic species Goniodoma polyedricum, further indicated that the globular species of Gambierdiscus formed a tight clade, clearly separated (with strong bootstrap support from the clade of lenticular species including the type for Gambierdiscus. The morphological and molecular data in concert support the split of Gambierdiscus sensu lato into two genera. Gambierdiscus sensu stricto should be reserved for the species with lenticular shapes, highly compressed anterioposteriorly, with short-shank fishhook apical pore plate, large 2' plate, low and ascending cingular displacement, and pouch-like sulcal morphology. The new genus name Fukuyoa gen. nov. should be applied to the globular species, slightly laterally compressed, with long-shank fishhook apical pore plate, large 1' plate, greater and descending cingular displacement, and not pouch-like vertically-oriented sulcal morphology. Fukuyoa contains the new species Fukuyoa paulensis gen. et sp. nov., and F. yasumotoi comb. nov. and F. ruetzleri comb. nov.

  14. Genetic diversity and distribution of the ciguatera-causing dinoflagellate Gambierdiscus spp. (Dinophyceae in coastal areas of Japan.

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    Tomohiro Nishimura

    Full Text Available The marine epiphytic dinoflagellate genus Gambierdiscus produce toxins that cause ciguatera fish poisoning (CFP: one of the most significant seafood-borne illnesses associated with fish consumption worldwide. So far, occurrences of CFP incidents in Japan have been mainly reported in subtropical areas. A previous phylogeographic study of Japanese Gambierdiscus revealed the existence of two distinct phylotypes: Gambierdiscus sp. type 1 from subtropical and Gambierdiscus sp. type 2 from temperate areas. However, details of the genetic diversity and distribution for Japanese Gambierdiscus are still unclear, because a comprehensive investigation has not been conducted yet.A total of 248 strains were examined from samples mainly collected from western and southern coastal areas of Japan during 2006-2011. The SSU rDNA, the LSU rDNA D8-D10 and the ITS region were selected as genetic markers and phylogenetic analyses were conducted. The genetic diversity of Japanese Gambierdiscus was high since five species/phylotypes were detected: including two reported phylotypes (Gambierdiscus sp. type 1 and Gambierdiscus sp. type 2, two species of Gambierdiscus (G. australes and G. cf. yasumotoi and a hitherto unreported phylotype Gambierdiscus sp. type 3. The distributions of type 3 and G. cf. yasumotoi were restricted to the temperate and the subtropical area, respectively. On the other hand, type 1, type 2 and G. australes occurred from the subtropical to the temperate area, with a tendency that type 1 and G. australes were dominant in the subtropical area, whereas type 2 was dominant in the temperate area. By using mouse bioassay, type 1, type 3 and G. australes exhibited mouse toxicities.This study revealed a surprising diversity of Japanese Gambierdiscus and the distribution of five species/phylotypes displayed clear geographical patterns in Japanese coastal areas. The SSU rDNA and the LSU rDNA D8-D10 as genetic markers are recommended for further use.

  15. Evolutionary transition towards permanent chloroplasts? - Division of kleptochloroplasts in starved cells of two species of Dinophysis (Dinophyceae.

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    Pernille Møller Rusterholz

    Full Text Available Species within the marine toxic dinoflagellate genus Dinophysis are phagotrophic organisms that exploit chloroplasts (kleptochloroplasts from other protists to perform photosynthesis. Dinophysis spp. acquire the kleptochloroplasts from the ciliate Mesodinium rubrum, which in turn acquires the chloroplasts from a unique clade of cryptophytes. Dinophysis spp. digest the prey nuclei and all other cell organelles upon ingestion (except the kleptochloroplasts and they are therefore believed to constantly acquire new chloroplasts as the populations grow. Previous studies have, however, indicated that Dinophysis can keep the kleptochloroplasts active during long term starvation and are able to produce photosynthetic pigments when exposed to prey starvation. This indicates a considerable control over the kleptochloroplasts and the ability of Dinophysis to replicate its kleptochloroplasts was therefore re-investigated in detail in this study. The kleptochloroplasts of Dinophysis acuta and Dinophysis acuminata were analyzed using confocal microscopy and 3D bioimaging software during long term starvation experiments. The cell concentrations were monitored to confirm cell divisions and samples were withdrawn each time a doubling had occurred. The results show direct evidence of kleptochloroplastidic division and that the decreases in total kleptochloroplast volume, number of kleptochloroplasts and number of kleptochloroplast centers were not caused by dilution due to cell divisions. This is the first report of division of kleptochloroplasts in any protist without the associated prey nuclei. This indicates that Dinophysis spp. may be in a transitional phase towards possessing permanent chloroplasts, which thereby potentially makes it a key organism to understand the evolution of phototrophic protists.

  16. Patterns of Symbiodinium (Dinophyceae) diversity and assemblages among diverse hosts and the coral reef environment of Lizard Island, Australia

    KAUST Repository

    Ziegler, Maren

    2018-04-26

    Large-scale environmental disturbances may impact both partners in coral host-Symbiodinium systems. Elucidation of the assembly patterns in such complex and interdependent communities may enable better prediction of environmental impacts across coral reef ecosystems. In this study, we investigated how the community composition and diversity of dinoflagellate symbionts in the genus Symbiodinium were distributed among 12 host species from six taxonomic orders (Actinaria, Alcyonacea, Miliolida, Porifera, Rhizostoma, Scleractinia) and in the reef water and sediments at Lizard Island, Great Barrier Reef before the 3rd Global Coral Bleaching Event. 454 pyrosequencing of the ITS2 region of Symbiodinium yielded 83 Operational Taxonomic Units (OTUs) at a 97% similarity cut-off. Approximately half of the Symbiodinium OTUs from reef water or sediments were also present in symbio. OTUs belonged to six clades (A-D, F-G), but community structure was uneven. The two most abundant OTUs (100% matches to types C1 and A3) comprised 91% of reads and OTU C1 was shared by all species. However, sequence-based analysis of these dominant OTUs revealed host species-specificity, suggesting that genetic similarity cut-offs of Symbiodinium ITS2 data sets need careful evaluation. Of the less abundant OTUs, roughly half occurred at only one site or in one species and the background Symbiodinium communities were distinct between individual samples. We conclude that sampling multiple host taxa with differing life history traits will be critical to fully understand the symbiont diversity of a given system and to predict coral ecosystem responses to environmental change and disturbance considering the differential stress response of the taxa within. This article is protected by copyright. All rights reserved.

  17. Mapping the fundamental niches of two freshwater microalgae, Chlorella vulgaris (Trebouxiophyceae) and Peridinium cinctum (Dinophyceae), in 5-dimensional ion space

    Science.gov (United States)

    A five dimensional experimental design, i.e. a five component ion mixture design for nitrate, phosphate, potassium, sodium and chloride projected across a total ion concentration gradient of 1-30 mM was utilized to map the ion-based, scenopoetic, or ‘Grinnellian’, niche space for two freshwater alga...

  18. Architecture of the flagellar apparatus and related structures in the type species of Peridinium, P. cinctum (Dinophyceae)

    DEFF Research Database (Denmark)

    Calado, A.C.; Hansen, Gert; Moestrup, Øjvind

    1999-01-01

    The ultrastructure of Peridinium cinctum, was examined by serial sectioning with particular emphasis on the detailed construction of the flagellar apparatus. The pusular system of P. cinctum included two sac pusules in open connection with the flagellar canals; disorganized material was found ins...

  19. Taxonomy and phylogeny of a new kleptoplastidal dinoflagellate, Gymnodinium myriopyrenoides sp. nov. (Gymnodiniales, Dinophyceae), and its cryptophyte symbiont.

    Science.gov (United States)

    Yamaguchi, Haruyo; Nakayama, Takeshi; Kai, Atsushi; Inouye, Isao

    2011-10-01

    A new kleptoplastidal dinoflagellate, Gymnodinium myriopyrenoides sp. nov., was described using light microscopy, electron microscopy and phylogengetic analysis based on partial LSU rDNA sequences. Cells were dorsiventrally flattened, elongate-elliptical in ventral view. There was no displacement of the cingulum encircling the anterior part of the cell. The cingulum was curved posteriorly at the terminal junction with the sulcus. The sulcus was generally narrow but expanded in the posterior end. The epicone possessed an apical groove made of one and one-half counterclockwise revolutions. Phylogenetic analysis based on LSU rDNA showed that the sequence of G. myriopyrenoides was included in the Gymnodiniales sensu stricto clade and had special affinities with the species Amphidinium poecilochroum and Gymnodinium acidotum, which also harbor kleptochloroplasts. Phylogenetic analysis based on plastid-encoded SSU rDNA and ultrastructural observations suggested that the symbionts of G. myriopyrenoides were cryptophytes of the genus Chroomonas or Hemiselmis. Organelles including the nucleus, the nucleomorph, mitochondria, Golgi bodies and large chloroplasts remained in the cytoplasm of the symbionts, but not the periplast, ejectosomes or flagellar apparatus. The symbiotic level of G. myriopyrenoides was estimated to be a relatively early stage in the unarmored kleptoplastidal dinoflagellates. Copyright © 2011 Elsevier GmbH. All rights reserved.

  20. Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and Flagellar apparatus.

    Science.gov (United States)

    Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind; Matsuoka, Kazumi

    2010-01-01

    The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior sulcal extension on the dorsal side of the epicone. The eyespot is located dorsally and composed of two layers of globules situated within the chloroplast. A narrow invagination of the plasma membrane is associated with the eyespot. The nuclear envelope has normal nuclear pores similar to other eukaryotes but different from the Gymnodinium group with diagnostic nuclear chambers. The longitudinal and transverse basal bodies are separated by approximately 0.5-1.0 microm and interconnected directly by a striated basal body connective and indirectly by microtubular and fibrous structures. Characteristic features of the flagellar apparatus are as follows: (1) a nuclear extension projects to the R1 (longitudinal microtubular root) and is connected to the root by thin fibrous material; (2) fibrillar structures are associated with the longitudinal and transverse flagellar canal; and (3) a striated ventral connective extends toward the posterior end of the cell along the longitudinal flagellar canal. We conclude, based on both morphological and molecular evidence, that Cochlodinium is only distantly related to Gymnodinium.

  1. Effects of Light and Salinity Stresses in Production of Mycosporine-Like Amino Acids by Gymnodinium catenatum (Dinophyceae).

    Science.gov (United States)

    Vale, Paulo

    2015-01-01

    Mycosporine-like amino acids (MAAs) were analyzed in a Portuguese Gymnodinium catenatum strain when transferred to high salinity and high light conditions. Total MAA concentrations increased progressively between 30 and 36 psu, attaining at 36 psu 2.9-fold the 30 psu treatment. When abruptly transferred to solar light in an outdoor shadowed location, MAA concentration increased steadily along the day for most compounds. After 8 h, mycosporine-glycine, palythene and M-319 attained or surpassed 25-fold their initial concentration, while M-370 only attained 4-fold concentration. When transferred from halogen to fluorescent light, polar MAAs such as shinorine and porphyra-334, increased until day two and then declined, while M-370 increase slowly, becoming the dominant compound from the profile after 1 week. These experiments put into evidence the relation of palythene with M-319, which was further identified as its acid degradation product, palythine. Acid degradation of M-370 originated M-324, while M-311 seems to be the precursor of M-370. Under high salinity and high light conditions chain formation was altered toward shorter chains or solitary cells. This alteration can represent a morphological stress sign, which in the natural environment could affect average population speed during daily vertical migrations. © 2015 The American Society of Photobiology.

  2. Diversity and Phylogeny of Gymnodiniales (Dinophyceae) from the NW Mediterranean Sea Revealed by a Morphological and Molecular Approach.

    Science.gov (United States)

    Reñé, Albert; Camp, Jordi; Garcés, Esther

    2015-05-01

    The diversity and phylogeny of dinoflagellates belonging to the Gymnodiniales were studied during a 3-year period at several coastal stations along the Catalan coast (NW Mediterranean) by combining analyses of their morphological features with rDNA sequencing. This approach resulted in the detection of 59 different morphospecies, 13 of which were observed for the first time in the Mediterranean Sea. Fifteen of the detected species were HAB producers; four represented novel detections on the Catalan coast and two in the Mediterranean Sea. Partial rDNA sequences were obtained for 50 different morphospecies, including novel LSU rDNA sequences for 27 species, highlighting the current scarcity of molecular information for this group of dinoflagellates. The combination of morphology and genetics allowed the first determinations of the phylogenetic position of several genera, i.e., Torodinium and many Gyrodinium and Warnowiacean species. The results also suggested that among the specimens belonging to the genera Gymnodinium, Apicoporus, and Cochlodinium were those representing as yet undescribed species. Furthermore, the phylogenetic data suggested taxonomic incongruences for some species, i.e., Gyrodinium undulans and Gymnodinium agaricoides. Although a species complex related to G. spirale was detected, the partial LSU rDNA sequences lacked sufficient resolution to discriminate between various other Gyrodinium morphospecies. Copyright © 2015 Elsevier GmbH. All rights reserved.

  3. THE INFLUENCE OF ENVIRONMENTAL NUTRIENT CONDITION ON GYMNODINIUM BREVE (DINOPHYCEAE) POPULATION DYNAMICS: A NUMERICAL STUDY. (R827085)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  4. Toxin Profile of Gymnodinium catenatum (Dinophyceae from the Portuguese Coast, as Determined by Liquid Chromatography Tandem Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Pedro R. Costa

    2015-04-01

    Full Text Available The marine dinoflagellate Gymnodinium catenatum has been associated with paralytic shellfish poisoning (PSP outbreaks in Portuguese waters for many years. PSP syndrome is caused by consumption of seafood contaminated with paralytic shellfish toxins (PSTs, a suite of potent neurotoxins. Gymnodinium catenatum was frequently reported along the Portuguese coast throughout the late 1980s and early 1990s, but was absent between 1995 and 2005. Since this time, G. catenatum blooms have been recurrent, causing contamination of fishery resources along the Atlantic coast of Portugal. The aim of this study was to evaluate the toxin profile of G. catenatum isolated from the Portuguese coast before and after the 10-year hiatus to determine changes and potential impacts for the region. Hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS was utilized to determine the presence of any known and emerging PSTs in sample extracts. Several PST derivatives were identified, including the N-sulfocarbamoyl analogues (C1–4, gonyautoxin 5 (GTX5, gonyautoxin 6 (GTX6, and decarbamoyl derivatives, decarbamoyl saxitoxin (dcSTX, decarbamoyl neosaxitoxin (dcNeo and decarbamoyl gonyautoxin 3 (dcGTX3. In addition, three known hydroxy benzoate derivatives, G. catenatum toxin 1 (GC1, GC2 and GC3, were confirmed in cultured and wild strains of G. catenatum. Moreover, two presumed N-hydroxylated analogues of GC2 and GC3, designated GC5 and GC6, are reported. This work contributes to our understanding of the toxigenicity of G. catenatum in the coastal waters of Portugal and provides valuable information on emerging PST classes that may be relevant for routine monitoring programs tasked with the prevention and control of marine toxins in fish and shellfish.

  5. Effects of light quality and nutrient availability on accumulation of mycosporine-like amino acids in Gymnodinium catenatum (Dinophycea).

    Science.gov (United States)

    Vale, Paulo

    2015-02-01

    A Portuguese Gymnodinium catenatum Graham strain was studied for its ultraviolet (UV) photoprotective pigments. This strain presented high absorption in the UVA region, in particular in the near UVA region around 370nm, followed by the far-UVA region around 340nm. Absorption in the near-UVA increased when grown under fluorescent when compared to halogen light. This was even more relevant when grown under nutrient-limiting conditions, which even surpassed absorption in the blue region, closely resembling absorption in natural plankton assemblages reported in the literature. HPLC analysis for mycosporine-like amino acids (MAAs), revealed several UV photoprotective pigments common in other marine microalgae from the northwest Atlantic. Amongst the compounds absorbing in the far-UVA region, three were identified by spectra and retention time characteristics: shinorine, porphyra-334, and mycosporine-glycine. In the near-UVA region, the unknown M-370 was usually the most abundant, followed by palythene. The proportional and absolute cellular concentrations of MAAs absorbing in the near-UVA region increased with fluorescent light when compared to halogen light. Additional experiments with light filtration suggest the set of MAAs absorbing in the near-UVA region seem to be regulated separately from the other set of MAAs absorbing in the far-UVA region, and those from the near-UVA region might be stimulated not only by UV but by blue light also. Nutrient availability affected profile: a shift towards MAAs with low nitrogen:carbon ratio (e.g.: mycosporine-glycine) was observed. As G. catenatum requires extensive UV-photoprotection over the entire UVA range, nitrogen availability might strongly restrict blooming, as MAAs are nitrogen-based. This UV sensitivity might help explaining its pronounced autumnal seasonality, tied to a reduced solar exposure. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Toxin profile of Gymnodinium catenatum (Dinophyceae) from the Portuguese coast, as determined by liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Costa, Pedro R; Robertson, Alison; Quilliam, Michael A

    2015-04-13

    The marine dinoflagellate Gymnodinium catenatum has been associated with paralytic shellfish poisoning (PSP) outbreaks in Portuguese waters for many years. PSP syndrome is caused by consumption of seafood contaminated with paralytic shellfish toxins (PSTs), a suite of potent neurotoxins. Gymnodinium catenatum was frequently reported along the Portuguese coast throughout the late 1980s and early 1990s, but was absent between 1995 and 2005. Since this time, G. catenatum blooms have been recurrent, causing contamination of fishery resources along the Atlantic coast of Portugal. The aim of this study was to evaluate the toxin profile of G. catenatum isolated from the Portuguese coast before and after the 10-year hiatus to determine changes and potential impacts for the region. Hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) was utilized to determine the presence of any known and emerging PSTs in sample extracts. Several PST derivatives were identified, including the N-sulfocarbamoyl analogues (C1-4), gonyautoxin 5 (GTX5), gonyautoxin 6 (GTX6), and decarbamoyl derivatives, decarbamoyl saxitoxin (dcSTX), decarbamoyl neosaxitoxin (dcNeo) and decarbamoyl gonyautoxin 3 (dcGTX3). In addition, three known hydroxy benzoate derivatives, G. catenatum toxin 1 (GC1), GC2 and GC3, were confirmed in cultured and wild strains of G. catenatum. Moreover, two presumed N-hydroxylated analogues of GC2 and GC3, designated GC5 and GC6, are reported. This work contributes to our understanding of the toxigenicity of G. catenatum in the coastal waters of Portugal and provides valuable information on emerging PST classes that may be relevant for routine monitoring programs tasked with the prevention and control of marine toxins in fish and shellfish.

  7. Toxin Profile of Gymnodinium catenatum (Dinophyceae) from the Portuguese Coast, as Determined by Liquid Chromatography Tandem Mass Spectrometry

    Science.gov (United States)

    Costa, Pedro R.; Robertson, Alison; Quilliam, Michael A.

    2015-01-01

    The marine dinoflagellate Gymnodinium catenatum has been associated with paralytic shellfish poisoning (PSP) outbreaks in Portuguese waters for many years. PSP syndrome is caused by consumption of seafood contaminated with paralytic shellfish toxins (PSTs), a suite of potent neurotoxins. Gymnodinium catenatum was frequently reported along the Portuguese coast throughout the late 1980s and early 1990s, but was absent between 1995 and 2005. Since this time, G. catenatum blooms have been recurrent, causing contamination of fishery resources along the Atlantic coast of Portugal. The aim of this study was to evaluate the toxin profile of G. catenatum isolated from the Portuguese coast before and after the 10-year hiatus to determine changes and potential impacts for the region. Hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) was utilized to determine the presence of any known and emerging PSTs in sample extracts. Several PST derivatives were identified, including the N-sulfocarbamoyl analogues (C1–4), gonyautoxin 5 (GTX5), gonyautoxin 6 (GTX6), and decarbamoyl derivatives, decarbamoyl saxitoxin (dcSTX), decarbamoyl neosaxitoxin (dcNeo) and decarbamoyl gonyautoxin 3 (dcGTX3). In addition, three known hydroxy benzoate derivatives, G. catenatum toxin 1 (GC1), GC2 and GC3, were confirmed in cultured and wild strains of G. catenatum. Moreover, two presumed N-hydroxylated analogues of GC2 and GC3, designated GC5 and GC6, are reported. This work contributes to our understanding of the toxigenicity of G. catenatum in the coastal waters of Portugal and provides valuable information on emerging PST classes that may be relevant for routine monitoring programs tasked with the prevention and control of marine toxins in fish and shellfish. PMID:25871287

  8. Three Dinophyceae from Clipperton Island lagoon (eastern Pacific Ocean), including a description of Peridiniopsis cristata var. tubulifera var. nov.

    OpenAIRE

    Coute, Alain; Perrette, Catherine; Chomerat, Nicolas

    2012-01-01

    Clipperton Island is a small French coral atoll in the eastern Pacific Ocean, which has been rarely investigated because of its remote location and difficult access. There is little scientific information on this ecosystem and only a few microalgae have been reported from the lagoon. To date, only one dinoflagellate taxon, Peridiniopsis cristata, is known to inhabit the lagoon. During an expedition in 2005 to study the lagoon and the surrounding oceanic waters of Clipperton Island, a further ...

  9. Blooms of the Toxic Dinoflagellate Alexandrium fundyense in the Gulf of Maine: Investigations Using a Physical-Biological Model

    National Research Council Canada - National Science Library

    Stock, Charles

    2005-01-01

    .... In this thesis, a biological model of the A. fundyense life cycle developed from laboratory and field data is combined with a circulation model to test hypothesis concerning the factors governing...

  10. Distinctly different behavioral responses of a copepod, Temora longicornis, to different strains of toxic dinoflagellates, Alexandrium spp

    DEFF Research Database (Denmark)

    Xu, Jiayi; Hansen, Per Juel; Nielsen, Lasse Tor

    2017-01-01

    Zooplankton responses to toxic algae are highly variable, even towards taxonomically closely related species or different strains of the same species. Here, the individual level feeding behavior of a copepod, Temora longicornis, was examined which offered 4 similarly sized strains of toxic...... of the copepod during 4 h incubations: (i) the ‘normal’ feeding behavior, in which the feeding appendages were beating almost constantly to produce a feeding current and most (90%) of the captured algae were ingested; (ii) the beating activity of the feeding appendages was reduced by ca. 80% during the initial...... may be equally beneficial to the prey and its competitors. These behaviors were not related to lytic activity or overall paralytic shellfish toxins (PSTs) content and composition and suggest that other cues are responsible for the responses....

  11. Blooms of the Toxic Dinoflagellate Alexandrium fundyense in the Gulf of Maine: Investigations Using a Physical-Biological Model

    Science.gov (United States)

    2005-02-01

    M. R., 1983. 25 years of algal growth kinetic, a personal view. Botanica Marina 26, 99-112. Eppley, R. W., Rogers, J. N., McCarthy, J. J., 1969. Half...kinetic, a personal view. Botanica Marina 26, 99-112. Eppley, R. W., Rogers, J. N., McCarthy, J. J., 1969. Half-saturation constants for uptake of

  12. Effect of water stress on growth, yield and water use efficiency of berseem (Trifolium alexandrium in Tadla

    Directory of Open Access Journals (Sweden)

    B. Bouazzama

    2018-01-01

    Full Text Available The study of crop response to water deficit is important in areas where water resources are limited. This study was carried out over the period 2008-2011 in order to study the effect of water deficit on the productivity of berseem in the Tadla region. Four water regimes (100%, 80%, 60% and 40% ETc were compared under both flood and drip irrigation techniques. Observations were made on the soil, biomass at each cut and root system. The results showed that the average annual maximum yield obtained was 16.2 t/ha. Reductions in yields by applying 60% of water inputs are 40% and 42% in 2009/10 and 2010/11, respectively. The contribution of cycles without irrigation to annual biomass yield varies from 35% under 100% ETc to 52% under 40% ETc. Water use efficiency of berseem over the over the entire crop period is 3.37 kg/m3. The maximum average yield obtained under drip irrigation was 15.7 t/ha. It was obtained with a water supply of 411 mm which allowed a saving of 57% of water supply versus flood irrigation technique.

  13. Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005.

    Directory of Open Access Journals (Sweden)

    Masafumi Natsuike

    Full Text Available The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100-1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will increase the frequency and scale of toxic blooms and the toxin contamination of plankton feeders. This poses serious threats to humans and the marine ecosystem.

  14. Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005.

    Science.gov (United States)

    Natsuike, Masafumi; Saito, Rui; Fujiwara, Amane; Matsuno, Kohei; Yamaguchi, Atsushi; Shiga, Naonobu; Hirawake, Toru; Kikuchi, Takashi; Nishino, Shigeto; Imai, Ichiro

    2017-01-01

    The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100-1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate) were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will increase the frequency and scale of toxic blooms and the toxin contamination of plankton feeders. This poses serious threats to humans and the marine ecosystem.

  15. NOAA NCCOS: New England Red Tide Research

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Alexandrium blooms are one of several algal bloom types often called "red tides," but more correctly referred to as Harmful Algal Blooms (HABs). Alexandrium produces...

  16. Population fluctuations of Pyrodinium bahamense and Ceratium furca (Dinophyceae in Laguna Grande, Puerto Rico, and environmental variables associated during a three-year period

    Directory of Open Access Journals (Sweden)

    Miguel P. Sastre

    2013-12-01

    Full Text Available Bioluminescent bays and lagoons are unique natural environments and popular tourist attractions. However, the bioluminescence in many of these water bodies has declined, principally due to anthropogenic activities. In the Caribbean, the bioluminescence in these bays and lagoons is mostly produced by the dinoflagellate Pyrodinium bahamense var. bahamense. Laguna Grande is one of the three year-round bioluminescent water bodies in Puerto Rico that are known to remain but P. bahamense var. bahamense density fluctuations have not been studied. In this study we describe water quality parameters and density fluctuations of the most common dinoflagellates in Laguna Grande, P. bahamense var. bahamense and Ceratium furca, over a three-year period. For this, three sampling stations were established in Laguna Grande from which water samples were collected in triplicate and analyzed for temperature, phosphates, nitrates, salinity, water transparency, fluorescence, and dinoflagellate densities, at the water surface and at 2m depth, from May 2003 to May 2006. The results showed a density fluctuation pattern for P. bahamense var. bahamense, where higher densities were observed mainly from April to September, and lower densities from October to February. Density fluctuations of C. furca were more erratic and a repetitive pattern was not observed. Densities of P. bahamense var. bahamense ranged from 0.48 to 90 978 cells/L and densities of C. furca ranged from 0 to 11 200 cells/L. The mean population density throughout the sampling period was significantly higher in P. bahamense var. bahamense (mean=18 958.5 cells/L than in C. furca (mean=2 601.9 cells/L. Population densities of P. bahamense var. bahamense were negatively correlated with C. furca densities during the first year of sampling; however, they were positively correlated during the third year. Non-significant differences between surface and 2m depth samples were observed for temperature, phosphates, nitrates, salinity, fluorescence, and densities of P. bahamense var. bahamense and C. furca, suggesting a vertically mixed water column. Water transparency was positively correlated with salinity and negatively correlated with fluorescence. Fluorescence was negatively correlated with salinity. The mean population densities of P. bahamense var. bahamense and C. furca observed in this study were within the range of previous reports in other bioluminescent water bodies in Puerto Rico and Florida, USA. In order to conserve the continuous P. bahamense var. bahamense populations in Laguna Grande, as well as its bioluminescence, it is recommended to maintain the existing water flow levels in the 1.5km long inlet/outlet channel; to maintain unpolluted water quality parameters within the bay, the hydrographical basin and adjacent waters, and to preserve mangrove communities within the basin and adjacent areas. Results of this study may help to develop management plans aiming to conserve P. bahamense, its bioluminescence and the lagoon attraction.

  17. Effects of irradiance and prey deprivation on growth, cell carbon and photosynthetic activity of the freshwater kleptoplastidic dinoflagellate Nusuttodinium (= Gymnodinium) aeruginosum (Dinophyceae)

    DEFF Research Database (Denmark)

    Drumm, Kirstine; Liebst-Olsen, Mette; Daugbjerg, Niels

    2017-01-01

    not explain the observed growth rates at high irradiances. Cultures of N. aeruginosum subjected to prey starvation were able to survive for at least 27 days in the light. The sequestered chloroplasts maintained their photosynthetic activity during the entire period of starvation, during which the population......The freshwater dinoflagellate Nusuttodinium aeruginosum lacks permanent chloroplasts. Rather it sequesters chloroplasts as well as other cell organelles, like mitochondria and nuclei, from ingested cryptophyte prey. In the present study, growth rates, cell production and photosynthesis were...... measured at seven irradiances, ranging from 10 to 140 µmol photons m-2s-1, when fed the cryptophyte Chroomonas sp. Growth rates were positively influenced by irradiance and increased from 0.025 d-1 at 10 µmol photons m-2s-1 to maximum growth rates of ~0.3 d-1 at irradiances ≥ 40 µmol photons m-2s-1...

  18. A hypocystal archeopyle in a freshwater dinoflagellate from the Peridinium umbonatum group (Dinophyceae) from Lake Nero di Cornisello, South Eastern Alps, Italy

    DEFF Research Database (Denmark)

    Tardio, Massimiliano; Ellegaard, Marianne; Lundholm, Nina

    2009-01-01

    Cornisello, a low-alkalinity high mountain lake of the Adamello mountain range (2233m above sea level, South Eastern Alps, Italy). The archeopyle is large, clearly hypocystal, polygonal, and slightly peanut-shaped. The species producing this cyst belongs to the Peridinium umbonatum group and is described...

  19. The Epiphytic Genus Gambierdiscus (Dinophyceae) in the Kermadec Islands and Zealandia Regions of the Southwestern Pacific and the Associated Risk of Ciguatera Fish Poisoning.

    Science.gov (United States)

    Rhodes, Lesley L; Smith, Kirsty F; Murray, Sam; Harwood, D Tim; Trnski, Tom; Munday, Rex

    2017-07-11

    Species in the genus Gambierdiscus produce ciguatoxins (CTXs) and/or maitotoxins (MTXs), which may cause ciguatera fish poisoning (CFP) in humans if contaminated fish are consumed. Species of Gambierdiscus have previously been isolated from macroalgae at Rangitahua (Raoul Island and North Meyer Islands, northern Kermadec Islands), and the opportunity was taken to sample for Gambierdiscus at the more southerly Macauley Island during an expedition in 2016. Gambierdiscus cells were isolated, cultured, and DNA extracted and sequenced to determine the species present. Bulk cultures were tested for CTXs and MTXs by liquid chromatography-mass spectrometry (LC-MS/MS). The species isolated were G. australes , which produced MTX-1 (ranging from 3 to 36 pg/cell), and G. polynesiensis , which produced neither MTX-1 nor, unusually, any known CTXs. Isolates of both species produced putative MTX-3. The risk of fish, particularly herbivorous fish, causing CFP in the Zealandia and Kermadec Islands region is real, although in mainland New Zealand the risk is currently low. Both Gambierdiscus and Fukuyoa have been recorded in the sub-tropical northern region of New Zealand, and so the risk may increase with warming seas and shift in the distribution of Gambierdiscus species.

  20. The Epiphytic Genus Gambierdiscus (Dinophyceae in the Kermadec Islands and Zealandia Regions of the Southwestern Pacific and the Associated Risk of Ciguatera Fish Poisoning

    Directory of Open Access Journals (Sweden)

    Lesley L. Rhodes

    2017-07-01

    Full Text Available Species in the genus Gambierdiscus produce ciguatoxins (CTXs and/or maitotoxins (MTXs, which may cause ciguatera fish poisoning (CFP in humans if contaminated fish are consumed. Species of Gambierdiscus have previously been isolated from macroalgae at Rangitahua (Raoul Island and North Meyer Islands, northern Kermadec Islands, and the opportunity was taken to sample for Gambierdiscus at the more southerly Macauley Island during an expedition in 2016. Gambierdiscus cells were isolated, cultured, and DNA extracted and sequenced to determine the species present. Bulk cultures were tested for CTXs and MTXs by liquid chromatography-mass spectrometry (LC-MS/MS. The species isolated were G. australes, which produced MTX-1 (ranging from 3 to 36 pg/cell, and G. polynesiensis, which produced neither MTX-1 nor, unusually, any known CTXs. Isolates of both species produced putative MTX-3. The risk of fish, particularly herbivorous fish, causing CFP in the Zealandia and Kermadec Islands region is real, although in mainland New Zealand the risk is currently low. Both Gambierdiscus and Fukuyoa have been recorded in the sub-tropical northern region of New Zealand, and so the risk may increase with warming seas and shift in the distribution of Gambierdiscus species.

  1. Gymnodinium corollarium sp. nov. (Dinophyceae) - a new cold-water dinoflagellate responsible for cyst sedimentation events in the Baltic Sea

    DEFF Research Database (Denmark)

    Sundström, Annica; Kremp, Anke; Daugbjerg, Niels

    2009-01-01

    revealed a preference of G. corollarium for low salinities and temperatures, confirming it to be a cold-water species well adapted to the brackish water conditions in the Baltic Sea. At nitrogen-deplete conditions, G. corollarium cultures produced small, slightly oval cysts resembling a previously...

  2. ON THE IDENTITY OF KARLODINIUM VENEFICUM AND DESCRIPTION OF KARLODINIUM ARMIGER SP. NOV. (DINOPHYCEAE), BASED ON LIGHT AND ELECTRON MICROSCOPY, NUCLEAR-ENCODED LSU RDNA, AND PIGMENT COMPOSITION

    DEFF Research Database (Denmark)

    Bergholtz, Trine; Daugbjerg, Niels; Moestrup, Øjvind

    2006-01-01

    An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species of Karlo......An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species...... of Karlodinium (K. micrum (Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic of Karlodinium. In K. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile of K. armiger revealed...... sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species, K. micrum, to K. veneficum. The three genera Karlodinium, Takayama, and Karenia constitute a separate evolutionary lineage, for which...

  3. Ecological characterization of toxic phytoplankton species (Dinophysis spp., Dinophyceae) in Slovenian mariculture areas (Gulf of Trieste, Adriatic Sea) and the implications for monitoring

    International Nuclear Information System (INIS)

    France, Janja . E-mail france@mbss.org; Mozetic, Patricija

    2006-01-01

    Diarrhetic shellfish poisoning (DSP) events are often registered in Slovenian mariculture areas (Gulf of Trieste, Adriatic Sea) and are related to the occurrence of Dinophysis spp. The annual dynamic of this genus and succession of the most important species were studied at two shellfish farms during monitoring fieldwork in the period 1995-2003. Results indicate that the Dinophysis genus maintains a relatively stable inter-annual dynamic at both sites. The Dinophysis community is characterized by two surface maxima in June and September, while in the middle layer only the autumn peak is pronounced (peak median 92 cells l -1 ). Occasional abundance maxima of around 2000 cells l -1 in the surface layer indicate that potential outbursts of toxic species are less predictable than their seasonal dynamic. On the basis of multivariate analysis, Dinophysis sacculus was characterized as a typical late spring-early summer species, and Dinophysis caudata and Dinophysis fortii as autumn species. Correlation analysis revealed the influence of stratified conditions only on the most abundant species, D. sacculus. Ecological characteristics of the species were combined with shellfish safety requirements towards a more effective monitoring

  4. Role of Modular Polyketide Synthases in the Production of Polyether Ladder Compounds in Ciguatoxin-Producing Gambierdiscus polynesiensis and G. excentricus (Dinophyceae).

    Science.gov (United States)

    Kohli, Gurjeet S; Campbell, Katrina; John, Uwe; Smith, Kirsty F; Fraga, Santiago; Rhodes, Lesley L; Murray, Shauna A

    2017-09-01

    Gambierdiscus, a benthic dinoflagellate, produces ciguatoxins that cause the human illness Ciguatera. Ciguatoxins are polyether ladder compounds that have a polyketide origin, indicating that polyketide synthases (PKS) are involved in their production. We sequenced transcriptomes of Gambierdiscus excentricus and Gambierdiscus polynesiensis and found 264 contigs encoding single domain ketoacyl synthases (KS; G. excentricus: 106, G. polynesiensis: 143) and ketoreductases (KR; G. excentricus: 7, G. polynesiensis: 8) with sequence similarity to type I PKSs, as reported in other dinoflagellates. In addition, 24 contigs (G. excentricus: 3, G. polynesiensis: 21) encoding multiple PKS domains (forming typical type I PKSs modules) were found. The proposed structure produced by one of these megasynthases resembles a partial carbon backbone of a polyether ladder compound. Seventeen contigs encoding single domain KS, KR, s-malonyltransacylase, dehydratase and enoyl reductase with sequence similarity to type II fatty acid synthases (FAS) in plants were found. Type I PKS and type II FAS genes were distinguished based on the arrangement of domains on the contigs and their sequence similarity and phylogenetic clustering with known PKS/FAS genes in other organisms. This differentiation of PKS and FAS pathways in Gambierdiscus is important, as it will facilitate approaches to investigating toxin biosynthesis pathways in dinoflagellates. © 2017 The Author(s) Journal of Eukaryotic Microbiology © 2017 International Society of Protistologists.

  5. Ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides (Dinophyceae) with reference to the apical groove and flagellar apparatus

    DEFF Research Database (Denmark)

    Iwataki, Mitsunori; Hansen, Gert; Moestrup, Øjvind

    2010-01-01

    The external and internal ultrastructure of the harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef has been examined with special reference to the apical groove and three-dimensional structure of the flagellar apparatus. The apical groove is U-shaped and connected to the anterior...

  6. GYMNODINIUM COROLLARIUM SP. NOV. (DINOPHYCEAE)-A NEW COLD-WATER DINOFLAGELLATE RESPONSIBLE FOR CYST SEDIMENTATION EVENTS IN THE BALTIC SEA(1).

    Science.gov (United States)

    Sundström, Annica M; Kremp, Anke; Daugbjerg, Niels; Moestrup, Øjvind; Ellegaard, Marianne; Hansen, Regina; Hajdu, Susanna

    2009-08-01

    A naked dinoflagellate with a unique arrangement of chloroplasts in the center of the cell was isolated from the northern Baltic proper during a spring dinoflagellate bloom (March 2005). Morphological, ultrastructural, and molecular analyses revealed this dinoflagellate to be undescribed and belonging to the genus Gymnodinium F. Stein. Gymnodinium corollarium A. M. Sundström, Kremp et Daugbjerg sp. nov. possesses features typical of Gymnodinium sensu stricto, such as nuclear chambers and an apical groove running in a counterclockwise direction around the apex. Phylogenetic analyses based on partial nuclear-encoded LSU rDNA sequences place the species in close proximity to G. aureolum, but significant genetic distance, together with distinct morphological features, such as the position of chloroplasts, clearly justifies separation from this species. Temperature and salinity experiments revealed a preference of G. corollarium for low salinities and temperatures, confirming it to be a cold-water species well adapted to the brackish water conditions in the Baltic Sea. At nitrogen-deplete conditions, G. corollarium cultures produced small, slightly oval cysts resembling a previously unidentified cyst type commonly found in sediment trap samples collected from the northern and central open Baltic Sea. Based on LSU rDNA comparison, these cysts were assigned to G. corollarium. The cysts have been observed in many parts of the Baltic Sea, indicating the ecologic versatility of the species and its importance for the Baltic ecosystem. © 2009 Phycological Society of America.

  7. Effects of irradiance and prey deprivation on growth, cell carbon and photosynthetic activity of the freshwater kleptoplastidic dinoflagellate Nusuttodinium (= Gymnodinium aeruginosum (Dinophyceae.

    Directory of Open Access Journals (Sweden)

    Kirstine Drumm

    Full Text Available The freshwater dinoflagellate Nusuttodinium aeruginosum lacks permanent chloroplasts. Rather it sequesters chloroplasts as well as other cell organelles, like mitochondria and nuclei, from ingested cryptophyte prey. In the present study, growth rates, cell production and photosynthesis were measured at seven irradiances, ranging from 10 to 140 μmol photons m-2s-1, when fed the cryptophyte Chroomonas sp. Growth rates were positively influenced by irradiance and increased from 0.025 d-1 at 10 μmol photons m-2s-1 to maximum growth rates of ~0.3 d-1 at irradiances ≥ 40 μmol photons m-2s-1. Similarly, photosynthesis ranged from 1.84 to 36.9 pg C cell-1 h-1 at 10 and 140 μmol photons m-2s-1, respectively. The highest rates of photosynthesis in N. aeruginosum only corresponded to ~25% of its own cell carbon content and estimated biomass production. The measured rates of photosynthesis could not explain the observed growth rates at high irradiances. Cultures of N. aeruginosum subjected to prey starvation were able to survive for at least 27 days in the light. The sequestered chloroplasts maintained their photosynthetic activity during the entire period of starvation, during which the population underwent 4 cell divisions. This indicates that N. aeruginosum has some control of the chloroplasts, which may be able to replicate. In conclusion, N. aeruginosum seems to be in an early stage of chloroplast acquisition with some control of its ingested chloroplasts.

  8. Effect of temperature on growth and paralytic toxin profiles in isolates of Gymnodinium catenatum (Dinophyceae) from the Pacific coast of Mexico.

    Science.gov (United States)

    Band-Schmidt, Christine J; Bustillos-Guzmán, José J; Hernández-Sandoval, Francisco E; Núñez-Vázquez, Erick J; López-Cortés, David J

    2014-11-01

    The effects of temperature on growth, cell toxicity, toxin content, and profile of paralytic shellfish toxins was determined in eight isolates of Gymnodinium catenatum from several localities along the Pacific Coast of Mexico. The isolates were cultivated in modified f/2 media with Se (10(-8) M), and a reduced concentration of Cu (10(-8) M), under a 12 h:12 h day-night cycle with an irradiance of 150 μE m(-2) s(-1). Isolates were progressively adapted for three generations to each of the temperatures (16, 19, 22, 24, 27, 30, and 33 °C). The cultures were grown in 125 mL Erlenmeyer flasks with 60 mL of media and harvested by filtration in late exponential growth. Toxins were analyzed by HPLC with a post-column oxidation and fluorescent detection (FLD). G. catenatum isolates tolerate temperatures between 16 and 33 °C, with maximum growth rates of 0.32 and 0.39 div day(-1) at 21 °C and 24 °C, respectively; maximum cell densities of 4700 and 5500 cells mL(-1) were obtained at 27 and 21 °C, respectively. No effect of toxicity per cell with temperature was observed, varying between 10.10 and 28.19 pgSXTeq cell(-1). Ten saxitoxin analogues were detected in all isolates, observing changes in the toxin profile with temperature. C1/2 toxins decreased from 80% mol at 16 °C to 20% mol at 33 °C, B1/2 toxins increased from 19% mol at 16 °C to 42% mol at 33 °C, and decarbamoyl toxins were more abundant at 21 °C. These results show that G. catenatum isolates from different regions of the Pacific coast of Mexico have a similar response to temperature and that this parameter can modify growth rate, cell density, and toxin profile of the species, particularly the decarbamoyl and sulfocarbamoyl toxins. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Effects of irradiance and prey deprivation on growth, cell carbon and photosynthetic activity of the freshwater kleptoplastidic dinoflagellate Nusuttodinium (= Gymnodinium) aeruginosum (Dinophyceae).

    Science.gov (United States)

    Drumm, Kirstine; Liebst-Olsen, Mette; Daugbjerg, Niels; Moestrup, Øjvind; Hansen, Per Juel

    2017-01-01

    The freshwater dinoflagellate Nusuttodinium aeruginosum lacks permanent chloroplasts. Rather it sequesters chloroplasts as well as other cell organelles, like mitochondria and nuclei, from ingested cryptophyte prey. In the present study, growth rates, cell production and photosynthesis were measured at seven irradiances, ranging from 10 to 140 μmol photons m-2s-1, when fed the cryptophyte Chroomonas sp. Growth rates were positively influenced by irradiance and increased from 0.025 d-1 at 10 μmol photons m-2s-1 to maximum growth rates of ~0.3 d-1 at irradiances ≥ 40 μmol photons m-2s-1. Similarly, photosynthesis ranged from 1.84 to 36.9 pg C cell-1 h-1 at 10 and 140 μmol photons m-2s-1, respectively. The highest rates of photosynthesis in N. aeruginosum only corresponded to ~25% of its own cell carbon content and estimated biomass production. The measured rates of photosynthesis could not explain the observed growth rates at high irradiances. Cultures of N. aeruginosum subjected to prey starvation were able to survive for at least 27 days in the light. The sequestered chloroplasts maintained their photosynthetic activity during the entire period of starvation, during which the population underwent 4 cell divisions. This indicates that N. aeruginosum has some control of the chloroplasts, which may be able to replicate. In conclusion, N. aeruginosum seems to be in an early stage of chloroplast acquisition with some control of its ingested chloroplasts.

  10. Ultrastructure and LSU rDNA-based phylogeny of Peridinium lomnickii and description of Chimonodinium gen. nov. (Dinophyceae)

    DEFF Research Database (Denmark)

    Craveiro, Sandra C.; Calado, António J.; Daugbjerg, Niels

    2011-01-01

    Several populations of Peridinium lomnickii were examined by SEM and serial section TEM. Comparison with typical Peridinium, Peridiniopsis, Palatinus and Scrippsiella species revealed significant structural differences, congruent with phylogenetic hypotheses derived from partial LSU rDNA sequence...

  11. Tandem repeats, high copy number and remarkable diel expression rhythm of form II RuBisCO in Prorocentrum donghaiense (Dinophyceae.

    Directory of Open Access Journals (Sweden)

    Xinguo Shi

    Full Text Available Gene structure and expression regulation of form II RuBisCO (rbcII in dinoflagellates are still poorly understood. Here we isolated this gene (Pdrbc and investigated its diel expression pattern in a harmful algal bloom forming dinoflagellate Prorocentrum donghaiense. We obtained cDNA sequences with triple tandem repeats of the coding unit (CU; the 5' region has the sequence of a typical dinoflagellate plastid gene, encoding an N-terminus with two transmembrane regions separated by a plastid transit peptide. The CUs (1,455 bp except 1464 bp in last CU are connected through a 63 bp spacer. Phylogenetic analysis showed that rbcII CUs within species formed monophyletic clusters, indicative of intraspecific gene duplication or purifying evolution. Using quantitative PCR (qPCR we estimated 117±40 CUs of Pdrbc in the P. donghaiense genome. Although it is commonly believed that most dinoflagellate genes lack transcriptional regulation, our RT-qPCR analysis on synchronized cultures revealed remarkable diel rhythm of Pdrbc expression, showing significant correlations of transcript abundance with the timing of the dark-to-light transition and cell cycle G2M-phase. When the cultures were shifted to continuous light, Pdrbc expression remained significantly correlated with the G2M-phase. Under continuous darkness the cell cycle was arrested at the G1 phase, and the rhythm of Pdrbc transcription disappeared. Our results suggest that dinoflagellate rbcII 1 undergoes duplication or sequence purification within species, 2 is organized in tandem arrays in most species probably to facilitate efficient translation and import of the encoded enzyme, and 3 is regulated transcriptionally in a cell cycle-dependent fashion at least in some dinoflagellates.

  12. Taksonomic study on Micromelum Blume (Rutaceae in Indonesia

    Directory of Open Access Journals (Sweden)

    TAHAN UJI

    2005-04-01

    Full Text Available Taxonomic study on Micromelum Blume was conducted at Herbarium Bogoriense (BO and Kew Herbarium (K and using 84 collections number of herbarium specimen. This research used descriptive method based on morphological characters. Terminology by Stearn (1983 was used, whereas the revision method as described by Rifai (1976 and Vogel (1987 were used. Based on this study were produced two species only of Micromelum respectively which occurred in Indonesia. They were Micromelum diversifolium Miq. and M. minutum (Forst. f. Wight. & Arn. M. diversifolium had two varieties, i.e. M. diversifolium Miq. var. diversifolium and M. diversifolium Miq. var. cuneata Miq. Whereas M. minutum had three varieties, i.e. M. minutum (Forst. f. Wight. & Arn. var. minutum, M. minutum (Forst. f. Wight & Arn. var. tomentosum Tan. and M. minutum (Forst. f. Wight & Arn. var. villosum Tan. New record specimen collections of M. diversifolium from Biak Island (Papua was reported also.

  13. Primer informe del género Gambierdiscus (Dinophyceae y otros dinoflagelados bentónicos en el Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental First report of the genus Gambierdiscus (Dinophyceae and other benthic dinoflagellates from Isla del Coco National Park, Costa Rica, Eastern Tropical Pacific

    Directory of Open Access Journals (Sweden)

    Maribelle Vargas-Montero

    2012-11-01

    Full Text Available El Pacífico Tropical Oriental se ha indicado como una región de los océanos libre de ciguatera, una intoxicación que causa serios trastornos gastrointestinales, neurológicos y cardiovasculares, en casos extremos, la muerte. Pero con el presente estudio hemos encontrado una incidencia alta de microalgas bénticas involucradas en la producción de ciguatera en el Parque Nacional Isla del Coco (PNIC, Costa Rica. En campañas oceanográficas realizadas entre el 2006 y el 2011 al PNIC se recolectaron 420 muestras de fitoplancton con el interés de encontrar especies de dinoflagelados bentónicos implicados en la producción de ciguatera. Las muestras se tomaron con red de fitoplancton o mediante buceos, entre los 5 y 30 m de profundidad en zonas de arrecife y por extracción directa de macroalgas. Se encontró a los dinoflagelados Gambierdiscus spp., Coolia tropicales, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae y Ostreopsis siamensis. Se determinó que la cantidad de dinoflagelados por peso de macroalga era elevada, principalmente para el género Gambierdiscus. Los géneros Ostreopsis y Prorocentrum mostraron tener la mayor distribución en los sitios de colecta. Gambierdiscus es un género productor de ciguatera. Se encontraron dos tamaños diferentes de individuos de Gambierdiscus, Comparando los especímenes de Gambierdiscus encontradas con otros estudios, se concluye que son diferentes a las descritas anteriormente, por lo que podría tratarse de especies nuevas, lo que se confirmará con cultivos y análisis moleculares. Al ser la Isla del Coco un sitio oceánico aislado y en estado de conservación, es un sitio ideal para el estudio de la evolución de especies de fitoplancton marino. Además, el monitoreo a largo plazo es muy importante debido a la variedad de dinoflagelados bentónicos potencialmente tóxicos que habitan en este ecosistema marino. Este es el primer estudio donde se da a conocer la incidencia de dinoflagelados bentónicos implicados en ciguatera para el Pacífico Tropical Oriental.The Eastern Tropical Pacific is a region reported as free of ciguatera poisoning that causes serious gastrointestinal, neural and cardiovascular problems, even death. But with this study we found a high incidence of benthic microalgae involved in ciguatera poisoning in Isla del Coco National Park (PNIC, from its name in Spanish, Costa Rica. Between 2006 and 2011, during expeditions to PNIC, 420 phytoplankton samples with the interest of finding benthic dinoflagellates involved in the ciguatera poisoning were collected and analyzed. Samples were taken with phytoplankton nets, towed vertically and horizontally or carried by diving, between 5 to 30 m depth, over reef areas, and by direct extraction from benthic macroalgae. We found the dinoflagellates Gambierdiscus spp., Coolia tropicalis, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae and Ostreopsis siamensis. The quantity of dinoflagellates by macroalgae weight was high, mainly for Gambierdiscus. Ostreopsis and Prorocentrum, the most widely distributed genera throughout the collection sites. Gambierdiscus is a ciguatera producing genus. Two different sizes of Gambierdiscus were found, and comparing our samples with other studies, we conclude that they are different to any previously reported. They possibly represent two new species. Coco Island is an oceanic island and because of its protection status, it is an ideal site for studying the evolution of marine phytoplankton. Also, long-term monitoring is important due to the variety of potentially toxic dinoflagellates living in this marine ecosystem. This is the first study to report benthic dinoflagellates implicated in ciguatera poisoning in other areas of the Eastern Tropical Pacific.

  14. Human-induced river runoff overlapping natural climate variability over the last 150 years: Palynological evidence (Bay of Brest, NW France)

    Science.gov (United States)

    Lambert, Clément; Penaud, Aurélie; Vidal, Muriel; Klouch, Khadidja; Gregoire, Gwendoline; Ehrhold, Axel; Eynaud, Frédérique; Schmidt, Sabine; Ragueneau, Olivier; Siano, Raffaele

    2018-01-01

    For the first time a very high resolution palynological study (mean resolution of 1 to 5 years) was carried out over the last 150 years in a French estuarine environment (Bay of Brest; NW France), allowing direct comparison between the evolution of landscapes, surface water, and human practices on Bay of Brest watersheds, through continental (especially pollen grains) and marine (phytoplanktonic microalgae: cysts of dinoflagellates or dinocysts) microfossils. Thanks to the small size of the watersheds and the close proximity of the depositional environment to the mainland, the Bay of Brest represents an ideal case study for palynological investigations. Palynological data were then compared to published palaeo-genetic analyses conducted on the same core and to various available instrumental data, allowing us to better characterize past environmental variability since the second half of the 19th century in Western Brittany. We provide evidence of some clues of recent eutrophication and/or pollution that affected phytoplankton communities and which appears linked with increased runoff (higher precipitations, higher percentages of riparian forest pollen, decline of salt marsh-type indicators, and higher values of the XRF Ti/Ca signal), mainly explained by the evolution of agricultural practices since 1945 superimposed on the warming climate trend. We assume that the significant relay observed between dinocyst taxa: Lingulodinium machaerophorum and Spiniferites bentorii around 1965 then followed by Spiniferites membranaceus after 1985, attests to a strong and recent eutrophication of Bay of Brest surface waters induced by high river runoff combined with abnormally elevated air temperatures, especially obvious in the data from 1990. The structure of the dinocyst community has thus been deeply altered, accompanied by an unprecedented increase of Alexandrium minutum toxic form at the same period, as confirmed by the genetic quantification. Despite this recent major

  15. Download this PDF file

    African Journals Online (AJOL)

    Dinophyceae) in Central Coastal Areas of. Tanzania. Charles Lugomela. Department of Fisheries Science and Aquaculture, Faculty oquuatic Sciences and Technology, University of Dar es Salaam, R0. Box 35064 Dar es Salaam, Tanzania.

  16. NCBI nr-aa BLAST: CBRC-MLUC-01-0516 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-MLUC-01-0516 ref|YP_001875573.1| hypothetical protein Emin_0681 [Elusimicrobium... minutum Pei191] gb|ACC98236.1| hypothetical protein Emin_0681 [Elusimicrobium minutum Pei191] YP_001875573.1 1e-08 21% ...

  17. NCBI nr-aa BLAST: CBRC-TTRU-01-1329 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-1329 ref|YP_001876264.1| cell cycle protein [Elusimicrobium minutum Pe...i191] gb|ACC98927.1| cell cycle protein [Elusimicrobium minutum Pei191] YP_001876264.1 0.004 25% ...

  18. NCBI nr-aa BLAST: CBRC-MLUC-01-0516 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-MLUC-01-0516 ref|YP_001875427.1| hypothetical protein Emin_0535 [Elusimicrobium... minutum Pei191] gb|ACC98090.1| hypothetical protein Emin_0535 [Elusimicrobium minutum Pei191] YP_001875427.1 6e-07 22% ...

  19. NCBI nr-aa BLAST: CBRC-TTRU-01-1038 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-TTRU-01-1038 ref|YP_001876264.1| cell cycle protein [Elusimicrobium minutum Pe...i191] gb|ACC98927.1| cell cycle protein [Elusimicrobium minutum Pei191] YP_001876264.1 0.009 22% ...

  20. NCBI nr-aa BLAST: CBRC-MLUC-01-0516 [SEVENS

    Lifescience Database Archive (English)

    Full Text Available CBRC-MLUC-01-0516 ref|YP_001875823.1| hypothetical protein Emin_0933 [Elusimicrobium... minutum Pei191] gb|ACC98486.1| hypothetical protein Emin_0933 [Elusimicrobium minutum Pei191] YP_001875823.1 5e-11 24% ...

  1. Autecology and phylogeny of Coolia tropicalis and Coolia malayensis (Dinophyceae), with emphasis on taxonomy of C. tropicalis based on light microscopy, scanning electron microscopy and LSU rDNA(1).

    Science.gov (United States)

    Mohammad-Noor, Normawaty; Moestrup, Øjvind; Lundholm, Nina; Fraga, Santiago; Adam, Aimimualiani; Holmes, Michael J; Saleh, Ejria

    2013-06-01

    Coolia is a widespread and ecologically important genus of benthic marine dinoflagellates found in tropical regions. Historically, there has been taxonomic confusion about the taxonomy and toxicity of this group. The goal of this study was to resolve morphological questions concerning Coolia tropicalis and determine the taxonomic identity of the Australian Coolia isolate which has been reported to produce cooliatoxins. To accomplish this, the morphology of tropical strains from Belize (the type locality of C. tropicalis), Malaysia, Indonesia, and Australia were examined and compared to published reports. The morphological analysis showed that C. tropicalis differs from the original description in that it has a slightly larger size (35-47 μm long by 30-45 μm wide versus 23-40 μm long by 25-39 μm wide), and the shape of fourth apical plate, and the length of Po plate (7.4-12 μm versus 7 μm). Based on both morphology and phylogenetic analysis using LSU D1- D3 rDNA sequences, the clones of C. tropicalis from Malaysia, Indonesia, and Belize were found to form a monophyletic clade within the genus. The strain producing cooliatoxin was found to be C. tropicalis, not Coolia monotis as originally assumed. To explore the factors influencing the growth of Coolia species, the growth rates of C. tropicalis and Coolia malayensis were determined at different temperatures and salinities. Both species tolerated a wide range of temperatures, but cannot survive at temperatures 35°C. C. monotis, the dominant species reported in the literature, probably does not produce toxins. © 2013 Phycological Society of America.

  2. Pentaplacodinium saltonense gen. et sp. nov. (Dinophyceae) and its relationship to the cyst-defined genus Operculodinium and yessotoxin-producing Protoceratium reticulatum

    DEFF Research Database (Denmark)

    Mertens, Kenneth Neil; Carbonell-Moore, M. Consuelo; Pospelova, Vera

    2018-01-01

    Strains of a dinoflagellate from the Salton Sea, previously identified as Protoceratium reticulatum and yessotoxin producing, have been reexamined morphologically and genetically and Pentaplacodinium saltonense n. gen. et sp. is erected to accommodate this species. Pentaplacodinium saltonense dif...

  3. Primer informe del género Gambierdiscus (Dinophyceae y otros dinoflagelados bentónicos en el Parque Nacional Isla del Coco, Costa Rica, Pacífico Tropical Oriental

    Directory of Open Access Journals (Sweden)

    Maribelle Vargas-Montero

    2012-11-01

    Full Text Available El Pacífico Tropical Oriental se ha indicado como una región de los océanos libre de ciguatera, una intoxicación que causa serios trastornos gastrointestinales, neurológicos y cardiovasculares, en casos extremos, la muerte. Pero con el presente estudio hemos encontrado una incidencia alta de microalgas bénticas involucradas en la producción de ciguatera en el Parque Nacional Isla del Coco (PNIC, Costa Rica. En campañas oceanográficas realizadas entre el 2006 y el 2011 al PNIC se recolectaron 420 muestras de fitoplancton con el interés de encontrar especies de dinoflagelados bentónicos implicados en la producción de ciguatera. Las muestras se tomaron con red de fitoplancton o mediante buceos, entre los 5 y 30 m de profundidad en zonas de arrecife y por extracción directa de macroalgas. Se encontró a los dinoflagelados Gambierdiscus spp., Coolia tropicales, Coolia cf. areolota, Prorocentrum concavum, Prorocentrum compressum, Amphidinium carterae y Ostreopsis siamensis. Se determinó que la cantidad de dinoflagelados por peso de macroalga era elevada, principalmente para el género Gambierdiscus. Los géneros Ostreopsis y Prorocentrum mostraron tener la mayor distribución en los sitios de colecta. Gambierdiscus es un género productor de ciguatera. Se encontraron dos tamaños diferentes de individuos de Gambierdiscus, Comparando los especímenes de Gambierdiscus encontradas con otros estudios, se concluye que son diferentes a las descritas anteriormente, por lo que podría tratarse de especies nuevas, lo que se confirmará con cultivos y análisis moleculares. Al ser la Isla del Coco un sitio oceánico aislado y en estado de conservación, es un sitio ideal para el estudio de la evolución de especies de fitoplancton marino. Además, el monitoreo a largo plazo es muy importante debido a la variedad de dinoflagelados bentónicos potencialmente tóxicos que habitan en este ecosistema marino. Este es el primer estudio donde se da a conocer la incidencia de dinoflagelados bentónicos implicados en ciguatera para el Pacífico Tropical Oriental.

  4. Ultrastructure and LSU rDNA-based revision of Peridinium group palatinum (Dinophyceae) with the description of Palatinus gen. nov

    DEFF Research Database (Denmark)

    Craveiro, Sandra; Calado, Antonio J.; Daugbjerg, Niels

    2009-01-01

    ornamentation and a suite of internal cell features to suggest a generic-level distinction between Peridinium group palatinum and typical Peridinium. The branching pattern of the phylogenetic tree is compatible with this conclusion, although with low support from bootstrap values and posterior probabilities....... comb. Distinctive characters for Palatinus include a smooth or slightly granulate, but not areolate, plate surface, a large central pyrenoid penetrated by cytoplasmic channels and radiating into chloroplast lobes, and the presence of a peduncle-homologous microtubular strand. Palatinus cells exit...

  5. Separate introns gained within short and long soluble peridinin-chlorophyll a-protein genes during radiation of Symbiodinium (Dinophyceae) clade A and B lineages - PLoS One

    Science.gov (United States)

    Here we document introns in two Symbiodinium clades that were most likely gained following divergence of this genus from other peridinin-containing dinoflagellate lineages. Soluble peridinin-chlorophyll a-proteins (sPCP) occur in short and long forms in different species, and all...

  6. Description of a new genus and species of the Coleopterous family Colydidae

    NARCIS (Netherlands)

    Reitter, E.

    1882-01-01

    Corpus valde elongatum, convexum. Antennae 11-articulatae, sub frontis margine ante oculos insertae, apicem versus sensim incrassatae, articulo ultimo rotundato. Fronte tateribus elevata. Oculi antice emarginati. Prothorax elongatus, carinatus. Scutellum minutum. Elytra punctatostriata, interstitiis

  7. Grazing of heterotrophic dinoflagellate Noctiluca scintillans (Mcartney) Kofoid on Gymnodinium catenatum Graham.

    Science.gov (United States)

    Alonso Rodríguez, Rosalba; Ochoa, José Luis; Uribe Alcocer, Manuel

    2005-01-01

    A dinoflagellate bloom ("red tide" event) dominated by the toxic Gymnodinium catenatum Graham (Gymnodiniales, Dinophyceae; 99.7%) and the noxious Noctiluca scintillans (Mcartney) Kofoid (Noctilucaceae, Dinophyceae; 0.3%) was observed in Bahia de Mazatlán Bay, México, on 24-26 January 2000. Photographic and microscopic analysis of samples during such an event, allowed us to collect evidence of a marked The particularity of grazing of G. catrenatum by by N. scintillans cells, suggesting a mechanism of "biocontrol" between these species that may contribute to attenuate a potentially toxic phenomenon under natural conditions.

  8. Western Indian Ocean Journal of Marine Science - Vol 5, No 2 (2006)

    African Journals Online (AJOL)

    Dinophyceae) in Central Coastal Areas of Tanzania · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. C Lugomela, 213-221. http://dx.doi.org/10.4314/wiojms.v5i2.28512 ...

  9. Environmental Barcoding Reveals Massive Dinoflagellate Diversity in Marine Environments

    Czech Academy of Sciences Publication Activity Database

    Stern, R. F.; Horák, Aleš; Andrew, R. L.; Coffroth, M. A.; Andersen, R. A.; Kupper, F. C.; Jameson, I.; Hoppenrath, M.; Véron, B.; Kasai, F.; Brand, J.; James, E. R.; Keeling, P. J.

    2010-01-01

    Roč. 5, č. 11 (2010), e13991 E-ISSN 1932-6203 Keywords : RIBOSOMAL-RNA GENE * FREE-LIVING STRAIN * SP-NOV DINOPHYCEAE * TOXIC DINOFLAGELLATE * MOLECULAR PHYLOGENY * COASTAL WATERS * NATURAL-ENVIRONMENT * RDNA SEQUENCES * SYMBIODINIUM Impact factor: 4.411, year: 2010

  10. Phytoplankton diversity in the Cross River Estuary of Nigeria | Ekwu ...

    African Journals Online (AJOL)

    Bacillariophyceae (Diatom) was the most abundant phytoplankton family, constituting 71.58% of total Algal density, followed by Chlorophyceae (Green algae) with 13.84%, Cyanobacteria (Blue-green algae) with 12.69%, while Euglenophyceae (Green flagellates) and Dinophyceae (Dinoflagellates) recorded 0.88% and ...

  11. Dinoflagellate Toxins Responsible for Ciguatera Food Poisoning

    Science.gov (United States)

    1991-03-30

    and labeled for shipment. The vial is then encased ip a plastic container with absorbant material. The plastic container is then packed into a metal ...and Pesado , D., (1985) Production and toxicity of Gambierdiscus tcxicas, Adacbh and Fukuyo (Dinophyceae), Phycologia, 24, 2 17-223. 96. Durand, M

  12. STEROLS AS BIOMARKERS IN GYMNODINIUM BREVE DISTRIBUTION IN DINOFLAGELLATES

    Science.gov (United States)

    The sterol composition of marine microalgae has been shown to be a chemotaxonomic property potentially of value in distinguishing members of different algal classes. For example, members of the class Dinophyceae display sterol compositions ranging from as few as two (cholesterol ...

  13. Harmful Algal Bloom Monitoring Data for Puget Sound - SoundToxins: Partnership for Enhanced Monitoring and Emergency Response to Harmful Algal Blooms in Puget Sound

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Toxic outbreaks of species of the dinoflagellate Alexandrium have become pervasive in the Puget Sound region over the last two decades, escalating the threats to...

  14. A new species of Limnoderetrema (Trematoda, Digenea from the freshwater Atherinid fish Basilichthys australis Eigenmann, 1927 from the south of Chile

    Directory of Open Access Journals (Sweden)

    Patricio Torres

    1991-12-01

    Full Text Available Limnoderetrema tolosai sp. n. (Trematoda, Digenea within an autochthonous freshwater fish, the silverside Basilichthys autralis Eigenmann, 1927, from Lakes Riñihue and Ranco in Southern Chile is described. The species is distinguished from Limnoderetrema minutum (Manter, 1954 by the presence of one spine in the cirrus and cecal bifurcation nearer to ventral sucker than to pharinx. It is proposed Limnoderetrema macrophallus (Szidat & Nani, 1951 n. comb. (originally Steganoderma. Limnoderetrema tolosai differs from L. macrophallus since it cirrus has a distal spine and by its vitelline follicles distribution. It seems that Limnoderetrema spp. of South America are highly specific unlike L. minutum of New Zealand.

  15. Especies del Fitoplancton Presentes en el Lago Tonatiahua, Morelos, México Especies del Fitoplancton Presentes en el Lago Tonatiahua, Morelos, México

    Directory of Open Access Journals (Sweden)

    Roberto Trejo Albarrán

    2012-02-01

    Full Text Available Se llevó a cabo un reconocimiento de las especies del fitoplancton del Lago Tonatiahua, Morelos, México, registrándose un total de 24 especies, incluidas en las siguientes clases: Chlorophyceae con 4 especies, Chlamydophyceae con 3 especies, Cyanophyceae con 3 especies, Euglenophyceae con 2 especies, Dinophyceae con 1 especie y Bacillariophyceae con 11, se da una descripción de cada una de ellas y la distribución que presentaron en la columna de agua durante el estudio. An examination of the phytoplankton species from the Tonatiahua lake of Morelos, Mexico was carried out. 24species were examinated. They were included in the following classification: Chlorophyceae with 4species, Chlamydophyceae with 3species, Cyanophyceae with 3 species, Euglenophyceae with 2 species, Dinophyceae with 1 species, Bacillariophyceae with 11 species, a description of each are and its distribution in a water column during the test are presented in this paper.

  16. sxtA-Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters ▿ †

    Science.gov (United States)

    Murray, Shauna A.; Wiese, Maria; Stüken, Anke; Brett, Steve; Kellmann, Ralf; Hallegraeff, Gustaaf; Neilan, Brett A.

    2011-01-01

    The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring. PMID:21841034

  17. sxtA-based quantitative molecular assay to identify saxitoxin-producing harmful algal blooms in marine waters.

    Science.gov (United States)

    Murray, Shauna A; Wiese, Maria; Stüken, Anke; Brett, Steve; Kellmann, Ralf; Hallegraeff, Gustaaf; Neilan, Brett A

    2011-10-01

    The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.

  18. The annual planktonic protist community structure in an ice-free high Arctic fjord (Adventfjorden, West Spitsbergen)

    Science.gov (United States)

    Kubiszyn, A. M.; Wiktor, J. M.; Wiktor, J. M.; Griffiths, C.; Kristiansen, S.; Gabrielsen, T. M.

    2017-05-01

    We investigated the size and trophic structure of the annual planktonic protist community structure in the ice-free Adventfjorden in relation to environmental factors. Our high-resolution (weekly to monthly) study was conducted in 2012, when warm Atlantic water was advected into the fjord in winter and summer. We observed a distinct seasonality in the protist communities. The winter protist community was characterised by extremely low levels of protist abundance and biomass (primarily Dinophyceae, Ciliophora and Bacillariophyceae) in a homogenous water column. In the second half of April, the total protist abundance and biomass rapidly increased, thus initiating the spring bloom in a still well-mixed water column. The spring bloom was initially dominated by the prymnesiophyte Phaeocystis pouchetii and Bacillariophyceae (primarily from the genera Thalassiosira, Fragilariopsis and Chaetoceros) and was later strictly dominated by Phaeocystis colonies. When the bloom terminated in mid-June, the community shifted towards flagellates (Dinophyceae, Ciliophora, Cryptophyceae and nanoflagellates 3-7 μm in size) in a stratified, nutrient-depleted water column. Decreases in the light intensity decreased the protist abundance and biomass, and the fall community (Dinophyceae, Cryptophyceae and Bacillariophyceae) was followed by the winter community.

  19. Molecular characterisation of a mycorrhizal inoculant that enhances ...

    African Journals Online (AJOL)

    SERVER

    2007-07-04

    Jul 4, 2007 ... lum used as biological models originated from the same desert area. In order to identify this mycorrhizal fungal inoculum, a molecular approach developed by Helgason et al. (1999) was adapted. The small subunit 18S from the roots of mycorrhizal T. alexandrium was amplified using primers NS31 and ...

  20. (5S-5-[(4aR,8aS,9E,11S,13R,14S,16R,17R,19S-11,19-Dihydroxy-8,10,13,16-tetramethyl-18-methylidene-3,4,5,6,8a,11,12,13,14,15,16,17,18,19,20,21-hexadecahydro-2H-14,17-epoxybenzo[2,3]cyclohexadeca[1,2-b]pyridine-7-yl]-3-methylfuran-2(5H-one (12-Methylgymnodimine B

    Directory of Open Access Journals (Sweden)

    Wendy Strangman

    2016-04-01

    Full Text Available A new member of the gymnodimine class of spiroimine toxins has been isolated from a laboratory culture strain of Alexandrium ostenfeldii. Extensive one-dimensional (1D and two-dimensional (2D NMR data analysis was used to elucidate its structure as 12-methylgymnodimine B.

  1. Enhanced detection levels in a semi-automated sandwich ...

    African Journals Online (AJOL)

    A peptide nucleic acid (PNA) signal probe was tested as a replacement for a typical DNA oligonucleotidebased signal probe in a semi-automated sandwich hybridisation assay designed to detect the harmful phytoplankton species Alexandrium tamarense. The PNA probe yielded consistently higher fluorescent signal ...

  2. The Upper Miocene rodents from the Pezinok in the Danube Basin, Slovakia

    OpenAIRE

    Peter Joniak

    2016-01-01

    Rodent assemblages are described from two sampled sites at the Pezinok clay pit in the Danube Basin. Although these assemblages contain material poor in specimens, the following eleven rodent taxa are distinguished and described: Progonomys hispanicus, Kowalskia sp., Microtocricetus molassicus, Anomalomys gaillardi, Graphiurops austriacus, Paraglirulus sp., Eomyops catalaunicus, Keramidomys sp., Spermophilinus sp., Albanensia sp. and Euroxenomys minutum. The co-occurrence of very primitive Pr...

  3. Temperature effects on Microalgal Photosynthesis-Light responses measured by O2 production, Pulse-Amplitude-Modulated Fluorescence, and 14C assimilation

    DEFF Research Database (Denmark)

    Hancke, Kasper; Hancke, Torunn; Olsen, Lasse M.

    2008-01-01

    Short-term temperature effects on photosynthesis were investigated by measuring O2 production, PSII-fluorescence kinetics, and 14C-incorporation rates in monocultures of the marine phytoplankton species Prorocentrum minimum (Pavill.) J. Schiller (Dinophyceae), Prymnesium parvum f. patelliferum ( J....... C. Green, D. J. Hibberd et Pienaar) A. Larsen (Coccolithophyceae), and Phaeodactylum tricornutum Bohlin (Bacillariophyceae), grown at 15 oC and 80 umol photons m-2 s-1. Photosynthesis versus irradiance curves were measured at seven temperatures (0oC to 30oC) by all three approaches. The maximum...

  4. Winter-summer succession of unicellular eukaryotes in a meso-eutrophic coastal system.

    Science.gov (United States)

    Christaki, Urania; Kormas, Konstantinos A; Genitsaris, Savvas; Georges, Clément; Sime-Ngando, Télesphore; Viscogliosi, Eric; Monchy, Sébastien

    2014-01-01

    The objective of this study was to explore the succession of planktonic unicellular eukaryotes by means of 18S rRNA gene tag pyrosequencing in the eastern English Channel (EEC) during the winter to summer transition. The 59 most representative (>0.1%, representing altogether 95% of total reads), unique operational taxonomic units (OTUs) from all samples belonged to 18 known high-level taxonomic groups and 1 unaffiliated clade. The five most abundant OTUs (69.2% of total reads) belonged to Dinophyceae, Cercozoa, Haptophyceae, marine alveolate group I, and Fungi. Cluster and network analysis between samples distinguished the winter, the pre-bloom, the Phaeocystis globosa bloom and the post-bloom early summer conditions. The OTUs-based network revealed that P. globosa showed a relatively low number of connections-most of them negative-with all other OTUs. Fungi were linked to all major taxonomic groups, except Dinophyceae. Cercozoa mostly co-occurred with the Fungi, the Bacillariophyceae and several of the miscellaneous OTUs. This study provided a more detailed exploration into the planktonic succession pattern of the EEC due to its increased depth of taxonomic sampling over previous efforts based on classical monitoring observations. Data analysis implied that the food web concept in a coastal system based on predator-prey (e.g. grazer-phytoplankton) relationships is just a part of the ecological picture; and those organisms exploiting a variety of strategies, such as saprotrophy and parasitism, are persistent and abundant members of the community.

  5. Effects of Harmful Algae on the Physiology of Fishes

    DEFF Research Database (Denmark)

    Svendsen, Morten Bo Søndergaard

    Blooms of harmful planktonic algae causing adverse effects in aquatic environments are a global problem, causing both human morbidity and killing aquatic lifeforms worldwide. Focusing on fish kills, it is largely unknown what mechanisms of the fish’s physiology are affected during exposure...... is deemed unlikely on basis of rainbow trout (Onchorhyncus mykiss) not recovering. The specific toxicity of Pseudochattonella spp. is unknown, but by studying the effects of Pseudochattonella spp. on fish during a natural bloom occurring at a trout farm an adverse outcome could be created. The adverse...... Alexandrium monilatum has been studied intensively the effects of Alexandrium monilatum on fish is largely unknown. In the Chesapeake Bay, Eastern U.S.A., fishes are further challenged in late summer by an oxygen squeeze from deep part of the water column, limiting their utilizable habitat to mid...

  6. Gulf of Maine Harmful Algal Bloom in summer 2005 - Part 1: In Situ Observations of Coastal Hydrography and Circulation

    OpenAIRE

    He, Ruoying; McGillicuddy, Dennis J.

    2008-01-01

    An extensive Alexandrium fundyense bloom occurred along the coast of the Gulf of Maine in late spring and early summer, 2005. To understand the physical aspects of bloom?s initiation and development, in-situ observations from both a gulf-wide ship survey and the coastal observing network were used to characterize coastal circulation and hydrography during that time period. Comparisons between these in-situ observations and their respective long term means revealed anomalous ocean conditions d...

  7. [Acute toxicity effects of three red tide algae on Brachionus plicatilis].

    Science.gov (United States)

    Zhou, Wen-Li; Xiao, Hui; Wang, You; Zhai, Hong-Chang; Tang, Xue-Xi

    2008-11-01

    Acute toxicity testing method was used to study effects of different density of Prorocentrum donghaiense, Heterosigma akashiwo and Alexandrium tamarense on mortality rates and population growth parameter of Brachionus plicatilis under controlled experimental conditions. Results showed that 24 h LC50 values of Prorocentrum donghaiense, Heterosigma akashiwo and Alexandrium tamarense treatment to mortality rate of Brachionus plicatilis were 3.56, 1.21 and 0.49 (x 10(4) cells/mL) respectively. Marked density effects were presented when three species of red tide microalga showed their toxicity to Brachionus plicatilis. There were significant inhibitory effects on Brachionus plicatilis when it was exposed to cells of Prorocentrum donghaiense at the concentration of 10(4) cells/mL, filtrate and cell contents of Heterosigma akashiwo at the concentration of 10(5) cells/mL, and cells, filtrate and cell contents of Alexandrium tamarense at the concentration of 10(3) cells/mL respectively. Inhibitory effects of three species of microalga on Brachionus plicatilis were enhanced with increasing of microalgal density.

  8. A new genus of athecate interstitial dinoflagellates, Togula gen. nov., previously encompassed within Amphidinium sensu lato: Inferred from light and electron microscopy and phylogenetic analyses of partial large subunit ribosomal DNA sequences

    DEFF Research Database (Denmark)

    Jørgensen, Mårten Flø; Murray, Shauna; Daugbjerg, Niels

    2004-01-01

    was not closely related to other genera included in the molecular phylogenetic analyses, but formed a highly supported clade in Bayesian analysis together with the six small-sized strains. The six strains also formed a highly supported clade, consisting of two closely related, albeit distinct, clades. Light......The recent emendation of Amphidinium (Dinophyceae), which now only consists of species with minute left-deflected epicone, has left more than 100 species without a clear generic affiliation. In the present study, a strain identified as one of the species with a divergent epicone type, Amphidinium...... subunit ribosomal DNA as well as in size and shape. Based on morphological similarity and partial large subunit ribosomal DNA evidence, we erect the new genus, Togula gen. nov. with the emended type species Togula britannica (Herdman) comb. nov. Based on differences in division pattern and partial large...

  9. Specific toxic effect of dinoflagellate Heterocapsa circularisquama on the rotifer Brachionus plicatilis.

    Science.gov (United States)

    Kim, D; Sato, Y; Oda, T; Muramatsu, T; Matsuyama, Y; Honjo, T

    2000-12-01

    Heterocapsa circularisquama (Dinophyceae), a noxious red tide dinoflagellate, is known to have a specifically lethal effect on shellfish, especially bivalves such as pearl oyster (Pinctada fucata), but no detrimental effects of this alga on fishes have not been observed so far. In this study, we found that H. circularisquama was toxic to a microzooplankton, a rotifer (Brachionus plicatilis) in a cell concentration-dependent manner, while the cultured supernatant or ultrasonic ruptured H. circularisquama had no significant toxic effect on the rotifer. Since no such toxic effects on the rotifer were observed in Chattonella marina, Heterosigma akashiwo, or Cochlodinium polykrikoides, other species of harmful red tide plankton, H. circularisquama may have a strictly specific toxic mechanism against the rotifer as well as bivalves.

  10. STRUKTUR KOMUNITAS FITOPLANKTON DI DANAU TOBA, SUMATERA UTARA

    Directory of Open Access Journals (Sweden)

    Arif Rahman

    2016-08-01

    Full Text Available Lake Toba is the largest lake in Indonesia, located in the Province of North Sumatra. Lake Toba is used to aquaculture, agricultural, tourism, and residential areas. These activities will produce organic and anorganic matter that can affect water quality and can cause eutrophication. Some indicators of eutrophication are an increase in phytoplankton biomass and changes in phytoplankton community structure. The aim of this study was to describe the phytoplankton community structure in Lake Toba. This study was conducted on 20-24 October 2014 at 23 stations around the Samosir Island, Lake Toba. The results showed that the phytoplankton abundance ranged 216-68.319.716 cells/m3. The phytoplankton composition consists of 35 genera from four classes: Cyanophyceae, Chlorophyceae, Bacillariophyceae, and Dinophyceae. Chyanophyceae is a dominant phytoplankton groups based on the composition of abundance (>40%. Structure of phytoplankton communities in Lake Toba dominated by Anabaena.

  11. Antilisterial effects of ethanolic extracts of some edible Thai plants on refrigerated cooked pork

    Directory of Open Access Journals (Sweden)

    Siriporn Stonsaovapak

    2010-12-01

    Full Text Available Listeria monocytogenes is a major foodborne pathogen responsible for the disease listeriosis.Effective methods for reducing L. monocytogenes in foods would reduce the likelihood of foodborneoutbreaks of listeriosis and decrease economic losses to the food industry. Crude ethanolic extracts from 50 edible Thai plants were screened for inhibitory effects on isolated strains and type strains of L.monocytogenes by the well assay technique. Ethanolic extracts of Micromelum minutum, Artocarpus heterophyllus, Piper retrofractum and Cucurbita moschata, which showed listerial growth inhibition,were applied to cooked pork to determine their antimicrobial activities against L. monocytogenes. Pork was cooked to an internal temperature of 85C, allowed to cool to 8C and then treated by surface application with the plant extracts. Low (102 cfu g-1 or high (105 cfu g-1 population of L.monocytogenes were applied and samples were stored at 4C for up to 7 days. M. minutum and A.heterophyllus extracts were most effective in inhibiting the growth of the pathogen. These results suggested that some edible Thai plant extracts might be useful as antimicrobials in cooked, ready-to-eatpork.

  12. Developing a Phytoplankton Biotic Index as an Indicator of Freshwater Inflow within a Subtropical Estuary

    Science.gov (United States)

    Steichen, J. L.; Quigg, A.; Lucchese, A.; Preischel, H.

    2016-02-01

    Freshwater inflows drive the water and sediment quality in coastal bays and estuaries influencing the ecosystem and health of the biological community. Phytoplankton accessory pigments (used as a proxy for major taxonomic groups) have been utilized to develop a biotic index of physical, chemical and biotic disturbances in Chesapeake Bay (USA) and other estuarine systems. In this study we have used the Chesapeake Bay - Phytoplankton Index of Biotic Integrity model as a guide in developing an index for Galveston Bay, TX (USA) as an indicator of sufficient freshwater inflow to a subtropical estuary. Multivariate statistical analyses were run using PRIMER-E+PERMANOVA to determine the correlations between phytoplankton accessory pigment concentrations and a suite of abiotic factors associated with freshwater inflow (salinity, DIN, PO4, secchi). Phytoplankton pigment concentrations and water quality parameters were collected across Galveston Bay on a monthly basis from 2008-2013. In the upper region of the bay nearest the river source Dinophyceae, Cryptophyceae (winter (Dec-Feb)) and Chlorophyceae (winter and spring (Mar-May)) were significantly correlated to freshwater inflow and nutrient concentrations PO4 (p<0.05). Increased concentrations of Bacillariophyceae and Cyanophyceae (summer (Jun-Aug)) were significantly correlated to lower concentrations of DIN (p<0.05). Near the mouth of the estuary there was a significant correlation between the increase in Bacillariophyceae, Cyanophyceae, Cryptophyceae and Dinophyceae with decreasing PO4 (p<0.05). Within the dynamic system of Galveston Bay we are working to apply a Phytoplankton Index of Biotic Integrity as a means of monitoring the biological health of this ecologically and economically important estuarine ecosystem.

  13. Tracing the origin of paralytic shellfish toxins in scallop Patinopecten yessoensis in the northern Yellow Sea.

    Science.gov (United States)

    Chen, Jian-Hua; Yu, Ren-Cheng; Gao, Yan; Kong, Fan-Zhou; Wang, Yun-Feng; Zhang, Qing-Chun; Kang, Zhen-Jun; Yan, Tian; Zhou, Ming-Jiang

    2013-01-01

    Some dinoflagellate species within the genera Alexandrium, Gymnodinium and Pyrodinium are well-known producers of paralytic shellfish toxins (PST), which led to many poisoning incidents around the world. In the northern Yellow Sea, an important mariculture zone for scallop Patinopecten yessoensis, PST have been frequently detected from scallops. However, there is little knowledge concerning PST-producing microalgae in this region so far. In cruises carried out in 2011 and 2012, scallop and phytoplankton samples were collected from the northern Yellow Sea. PST were detected from scallops by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Toxin content and profile were remarkably different among the four tissues, i.e. viscera, adductor muscle, mantle and gonad, suggesting apparent toxin transfer and transformation in scallops. Viscera always had the highest content of PST dominated by low-potency N-sulfocarbamoyl toxins C1 and C2, which closely resembled the toxin profiles of net-concentrated phytoplankton samples in spring. Based on the morphological features, cells of Alexandrium spp. in net-concentrated phytoplankton samples were picked out and a partial sequence of the large subunit ribosomal RNA gene (LSU rDNA) was amplified using a single-cell polymerase chain reaction (PCR) method. Cells of both toxic A. tamarense species complex and non-toxic A. affine were identified from the phytoplankton samples based on the partial LSU rDNA sequence information. According to these findings, it is implied that A. tamarense species complex is the major toxic species related to PST contamination in scallops of the northern Yellow Sea. The presence of both toxic and non-toxic Alexandrium spp. in this region requires for a species-specific method to monitor the distribution and dynamics of A. tamarense species complex.

  14. Magnetically modified microalgae and their applications

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Procházková, G.; Pospíšková, K.; Brányik, T.

    2016-01-01

    Roč. 36, č. 5 (2016), s. 931-941 ISSN 0738-8551 R&D Projects: GA ČR GA13-13709S; GA MŠk(CZ) LD13021 Institutional support: RVO:67179843 Keywords : oleaginous chlorella sp * fresh-water microalgae * magnetophoretic separation * high-gradient * harvesting microalgae * alexandrium-fundyense * polymer binder * algal blooms * cells * removal * Harvesting algal cells * magnetic labeling * magnetic modification * magnetic separation * microalgae Subject RIV: EI - Biotechnology ; Bionics Impact factor: 6.542, year: 2016

  15. Gene duplication, loss and selection in the evolution of saxitoxin biosynthesis in alveolates.

    Science.gov (United States)

    Murray, Shauna A; Diwan, Rutuja; Orr, Russell J S; Kohli, Gurjeet S; John, Uwe

    2015-11-01

    A group of marine dinoflagellates (Alveolata, Eukaryota), consisting of ∼10 species of the genus Alexandrium, Gymnodinium catenatum and Pyrodinium bahamense, produce the toxin saxitoxin and its analogues (STX), which can accumulate in shellfish, leading to ecosystem and human health impacts. The genes, sxt, putatively involved in STX biosynthesis, have recently been identified, however, the evolution of these genes within dinoflagellates is not clear. There are two reasons for this: uncertainty over the phylogeny of dinoflagellates; and that the sxt genes of many species of Alexandrium and other dinoflagellate genera are not known. Here, we determined the phylogeny of STX-producing and other dinoflagellates based on a concatenated eight-gene alignment. We determined the presence, diversity and phylogeny of sxtA, domains A1 and A4 and sxtG in 52 strains of Alexandrium, and a further 43 species of dinoflagellates and thirteen other alveolates. We confirmed the presence and high sequence conservation of sxtA, domain A4, in 40 strains (35 Alexandrium, 1 Pyrodinium, 4 Gymnodinium) of 8 species of STX-producing dinoflagellates, and absence from non-producing species. We found three paralogs of sxtA, domain A1, and a widespread distribution of sxtA1 in non-STX producing dinoflagellates, indicating duplication events in the evolution of this gene. One paralog, clade 2, of sxtA1 may be particularly related to STX biosynthesis. Similarly, sxtG appears to be generally restricted to STX-producing species, while three amidinotransferase gene paralogs were found in dinoflagellates. We investigated the role of positive (diversifying) selection following duplication in sxtA1 and sxtG, and found negative selection in clades of sxtG and sxtA1, clade 2, suggesting they were functionally constrained. Significant episodic diversifying selection was found in some strains in clade 3 of sxtA1, a clade that may not be involved in STX biosynthesis, indicating pressure for diversification

  16. Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids.

    Directory of Open Access Journals (Sweden)

    Juan José Dorantes-Aranda

    Full Text Available Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum. Quantification of superoxide production by these algae was also performed. The effect of purified phycotoxins and crude extracts was compared, and the effect of fatty acids is discussed. The raphidophyte Chattonella was the most ichthyotoxic (gill cell viability down to 35% and also the major producer of superoxide radicals (14 pmol cell-1 hr-1 especially after cell lysis. The raphidophyte Heterosigma and dinoflagellate Alexandrium were the least toxic and had low superoxide production, except when A. catenella was lysed (5.6 pmol cell-1 hr-1. Catalase showed no changes in activity in all the treatments. Superoxide dismutase (SOD and lactate dehydrogenase exhibited significant activity increases of ≤23% and 51.2% TCC (total cellular content, respectively, after exposure to C. marina, but SOD showed insignificant changes with remaining algal species. A strong relationship between gill cell viability and superoxide production or superoxide dismutase was not observed. Purified brevetoxins PbTx-2 and -3 (from Karenia brevis, LC50 of 22.1 versus 35.2 μg mL-1 and karlotoxin KmTx-2 (from Karlodinium; LC50 = 380 ng mL-1 could almost entirely account for the fish killing activity by those two dinoflagellates. However, the paralytic shellfish toxins (PST GTX1&4, C1&C2, and STX did not account for Alexandrium ichthyotoxicity. Only aqueous extracts of Alexandrium were cytotoxic (≤65% decrease of viability, whereas

  17. A framework for examining climate-driven changes to the seasonality and geographical range of coastal pathogens and harmful algae

    Directory of Open Access Journals (Sweden)

    John Jacobs

    2015-01-01

    Full Text Available Climate change is expected to alter coastal ecosystems in ways which may have predictable consequences for the seasonality and geographical distribution of human pathogens and harmful algae. Here we demonstrate relatively simple approaches for evaluating the risk of occurrence of pathogenic bacteria in the genus Vibrio and outbreaks of toxin-producing harmful algae in the genus Alexandrium, with estimates of uncertainty, in U.S. coastal waters under future climate change scenarios through the end of the 21st century. One approach forces empirical models of growth, abundance and the probability of occurrence of the pathogens and algae at specific locations in the Chesapeake Bay and Puget Sound with ensembles of statistically downscaled climate model projections to produce first order assessments of changes in seasonality. In all of the case studies examined, the seasonal window of occurrence for Vibrio and Alexandrium broadened, indicating longer annual periods of time when there is increased risk for outbreaks. A second approach uses climate model projections coupled with GIS to identify the potential for geographic range shifts for Vibrio spp. in the coastal waters of Alaska. These two approaches could be applied to other coastal pathogens that have climate sensitive drivers to investigate potential changes to the risk of outbreaks in both time (seasonality and space (geographical distribution under future climate change scenarios.

  18. Application of rotifer Brachionus plicatilis in detecting the toxicity of harmful algae

    Science.gov (United States)

    Yan, Tian; Wang, Yunfeng; Wang, Liping; Chen, Yang; Han, Gang; Zhou, Mingjiang

    2009-05-01

    The toxicity of seven major HAB (harmful algal bloom) species/strains, Prorocentrum donghaiense, Phaeocystis globosa, Prorocentrum micans, Alexandrium tamarense (AT-6, non-PSP producer), Alexandrium lusitanicum, Alexandrum tamarense (ATHK) and Heterosigma akashiwo were studied against rotifer Brachionus plicatilis under laboratory conditions. The results show that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6), or A. lusitanicum could maintain the individual survival and reproduction, as well as the population increase of the rotifer, but the individual reproduction would decrease when exposed to these five algae at higher densities for nine days; H. akashiwo could decrease the individual survival and reproduction, as well as population increase of the rotifer, which is similar to that of the starvation group, indicating that starvation might be its one lethal factor except for the algal toxins; A. tamarense (ATHK) has strong lethal effect on the rotifer with 48h LC50 at 800 cells/mL. The experiment on ingestion ability indicated by gut pigment change shows that P. donghaiense, P. globosa, P. micans, A. tamarense (AT-6) and A. lusitanicum can be taken by the rotifers as food, but A. tamarense (ATHK) or H. akashiwo can be ingested by the rotifers. The results indicate that all the indexes of individual survival and reproduction, population increase, gut pigment change of the rotifers are good and convenient to be used to reflect the toxicities of HAB species. Therefore, rotifer is suggested as one of the toxicity testing organisms in detecting the toxicity of harmful algae.

  19. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Directory of Open Access Journals (Sweden)

    Hela Ben Gharbia

    Full Text Available Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis. The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella. Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  20. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Science.gov (United States)

    Ben Gharbia, Hela; Kéfi-Daly Yahia, Ons; Cecchi, Philippe; Masseret, Estelle; Amzil, Zouher; Herve, Fabienne; Rovillon, Georges; Nouri, Habiba; M'Rabet, Charaf; Couet, Douglas; Zmerli Triki, Habiba; Laabir, Mohamed

    2017-01-01

    Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa) and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis). The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella). Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  1. When naked became armored: an eight-gene phylogeny reveals monophyletic origin of theca in dinoflagellates.

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    Russell J S Orr

    Full Text Available The dinoflagellates are a diverse lineage of microbial eukaryotes. Dinoflagellate monophyly and their position within the group Alveolata are well established. However, phylogenetic relationships between dinoflagellate orders remain unresolved. To date, only a limited number of dinoflagellate studies have used a broad taxon sample with more than two concatenated markers. This lack of resolution makes it difficult to determine the evolution of major phenotypic characters such as morphological features or toxin production e.g. saxitoxin. Here we present an improved dinoflagellate phylogeny, based on eight genes, with the broadest taxon sampling to date. Fifty-five sequences for eight phylogenetic markers from nuclear and mitochondrial regions were amplified from 13 species, four orders, and concatenated phylogenetic inferences were conducted with orthologous sequences. Phylogenetic resolution is increased with addition of support for the deepest branches, though can be improved yet further. We show for the first time that the characteristic dinoflagellate thecal plates, cellulosic material that is present within the sub-cuticular alveoli, appears to have had a single origin. In addition, the monophyly of most dinoflagellate orders is confirmed: the Dinophysiales, the Gonyaulacales, the Prorocentrales, the Suessiales, and the Syndiniales. Our improved phylogeny, along with results of PCR to detect the sxtA gene in various lineages, allows us to suggest that this gene was probably acquired separately in Gymnodinium and the common ancestor of Alexandrium and Pyrodinium and subsequently lost in some descendent species of Alexandrium.

  2. When Naked Became Armored: An Eight-Gene Phylogeny Reveals Monophyletic Origin of Theca in Dinoflagellates

    Science.gov (United States)

    Orr, Russell J. S.; Murray, Shauna A.; Stüken, Anke; Rhodes, Lesley; Jakobsen, Kjetill S.

    2012-01-01

    The dinoflagellates are a diverse lineage of microbial eukaryotes. Dinoflagellate monophyly and their position within the group Alveolata are well established. However, phylogenetic relationships between dinoflagellate orders remain unresolved. To date, only a limited number of dinoflagellate studies have used a broad taxon sample with more than two concatenated markers. This lack of resolution makes it difficult to determine the evolution of major phenotypic characters such as morphological features or toxin production e.g. saxitoxin. Here we present an improved dinoflagellate phylogeny, based on eight genes, with the broadest taxon sampling to date. Fifty-five sequences for eight phylogenetic markers from nuclear and mitochondrial regions were amplified from 13 species, four orders, and concatenated phylogenetic inferences were conducted with orthologous sequences. Phylogenetic resolution is increased with addition of support for the deepest branches, though can be improved yet further. We show for the first time that the characteristic dinoflagellate thecal plates, cellulosic material that is present within the sub-cuticular alveoli, appears to have had a single origin. In addition, the monophyly of most dinoflagellate orders is confirmed: the Dinophysiales, the Gonyaulacales, the Prorocentrales, the Suessiales, and the Syndiniales. Our improved phylogeny, along with results of PCR to detect the sxtA gene in various lineages, allows us to suggest that this gene was probably acquired separately in Gymnodinium and the common ancestor of Alexandrium and Pyrodinium and subsequently lost in some descendent species of Alexandrium. PMID:23185516

  3. Biofilm forming microorganisms on various substrata from greenhouse of Botanical Garden “Jevremovac”

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    Unković Nikola D.

    2017-01-01

    Full Text Available Diversity of subaerial biofilm forming cyanobacteria, algae and fungi was investigated on 10 different substrata from greenhouse of Botanical Garden “Jevremovac”. Out of 37 documented taxa, 16 cyanobacterial and 10 algal taxa were identified. Remaining 11 taxa belong to the Kingdom of Fungi. The highest diversity of biofilm forming microorganisms, a total of 24 taxa, was detected on the corroded metal surface, while significantly lower number of taxa was recorded on other examined substrata. Cyanobacterium Porphyrosiphon sp., diatom Achnanthes sp. and green algae Chlorella sp. and Chlorococcum minutum were the most frequently encountered photosynthetic components of biofilms. In all analyzed samples, Trichoderma sp., followed by Cladosporium sp. and Rhizopus stolonifer, were the most frequently identified fungi. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI176020, Grant no. OI176018, and Grant no. OI173032

  4. Microalgal biomass and lipid production in mixed municipal, dairy, pulp and paper wastewater together with added flue gases.

    Science.gov (United States)

    Gentili, Francesco G

    2014-10-01

    The aim of the study was to grow microalgae on mixed municipal and industrial wastewater to simultaneously treat the wastewater and produce biomass and lipids. All algal strains grew in all wastewater mixtures; however, Selenastrum minutum had the highest biomass and lipids yields, up to 37% of the dry matter. Nitrogen and phosphorus removal were high and followed a similar trend in all three strains. Ammonium was reduced from 96% to 99%; this reduction was due to algal growth and not to stripping to the atmosphere, as confirmed by the amount of nitrogen in the dry algal biomass. Phosphate was reduced from 91% to 99%. In all strains used the lipid content was negatively correlated to the nitrogen concentration in the algal biomass. Mixtures of pulp and paper wastewater with municipal and dairy wastewater have great potential to grow algae for biomass and lipid production together with effective wastewater treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. A diverse host thrombospondin-type-1 repeat protein repertoire promotes symbiont colonization during establishment of cnidarian-dinoflagellate symbiosis.

    Science.gov (United States)

    Neubauer, Emilie-Fleur; Poole, Angela Z; Neubauer, Philipp; Detournay, Olivier; Tan, Kenneth; Davy, Simon K; Weis, Virginia M

    2017-05-08

    The mutualistic endosymbiosis between cnidarians and dinoflagellates is mediated by complex inter-partner signaling events, where the host cnidarian innate immune system plays a crucial role in recognition and regulation of symbionts. To date, little is known about the diversity of thrombospondin-type-1 repeat (TSR) domain proteins in basal metazoans or their potential role in regulation of cnidarian-dinoflagellate mutualisms. We reveal a large and diverse repertoire of TSR proteins in seven anthozoan species, and show that in the model sea anemone Aiptasia pallida the TSR domain promotes colonization of the host by the symbiotic dinoflagellate Symbiodinium minutum . Blocking TSR domains led to decreased colonization success, while adding exogenous TSRs resulted in a 'super colonization'. Furthermore, gene expression of TSR proteins was highest at early time-points during symbiosis establishment. Our work characterizes the diversity of cnidarian TSR proteins and provides evidence that these proteins play an important role in the establishment of cnidarian-dinoflagellate symbiosis.

  6. The Early Burdigalian (MN3; Miocene large mammals from Estrepouy (Aquitaine basin, France: an updated faunal list

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    Ginsburg, L.

    2011-12-01

    Full Text Available The purpose of the present work is to describe the mammals from the Early Miocene locality of Estrepouy, Gers, France. We have identified 17 species belonging to 3 orders; Carnivora; Amphicyon lanthanicus, Cynelos helbingi, Plithocyon bruneti, Hemicyon gargan, Palaeogale hyaenoides, Semigenetta elegans y Pseudaelurus turnauensis. Perissodactyla; Anchitherium aurelianense, Protaceratherium minutum y Diaceratherium cf. aurelianense. Arctiodactyla; Aureliachoerus aurelianensis, Xenohyus venitor, Caenotherium aff. lintillae, Andegameryx andegaviensis, Oriomeryx willii, Procervulus praelucidus, Lagomeryx parvulus y Procervulus praelucidus. The Estrepouy mammal assemblage seems older than that represented in Wintershof-West (Alemania, MN 3 reference locality.

    [fr] Des grands mammifères sont determines pour le Miocène inférieur (MN3 de Etrepouy, Gers, France. 17 taxons appartenant à trois déterminés ont été identifies: Carnivora; Amphicyon lanthanicus, Cynelos helbingi, Plithocyon bruneti, Hemicyon gargan, Palaeogale hyaenoides, Semigenetta elegans et Pseudaelurus turnauensis. Perissodactyla; Anchitherium aurelianense, Protaceratherium minutum et Diaceratherium cf. aurelianense. Arctiodactyla; Aureliachoerus aurelianensis, Xenohyus venitor, Caenotherium aff. lintillae, Andegameryx andegaviensis, Oriomeryx willii, Procervulus praelucidus, Lagomeryx parvulus et Procervulus praelucidus. L’association des mammifères Estrepouy regarde un peu plus âgé que celui représenté à la localité de référence du MN3 á Wintershof-Ouest (Allemagne.

  7. The use of flue gas for the growth of microalgal biomass

    International Nuclear Information System (INIS)

    Zeiler, K.G.; Kadam, K.L.; Heacox, D.A.

    1995-01-01

    Capture and utilization of carbon dioxide (CO 2 ) by microalgae is a promising technology to help reduce emissions from fossil fuel-fired power plants. Microalgae are of particular interest because of their rapid growth rates and tolerance to varying environmental conditions. Laboratory work is directed toward investigating the effects of simulated flue gas on microalgae, while engineering studies have focused on the economics of the technology. One strain of a green algae, Monoraphidium minutum, has shown excellent tolerance and growth when exposed to simulated flue gas which meets the requirements of the 1990 Clean Air Act Amendments (1990 CAAA). Biomass concentrations of ∼2g/L have been measured in batch culture. Several other microalgae have also shown tolerance to simulated flue gas; however, the growth of these strains is not equivalent to that observed for M. minutum. Coupling the production of biodiesel or other microalgae-derived commodity chemicals with the use of flue gas carbon dioxide is potentially a zero-cost method of reducing the amount of carbon dioxide contributed to the atmosphere by fossil fuel-fired power plants. We have identified two major biological performance parameters which can provide sufficient improvement in this technology to render it cost-competitive with other existing CO x mitigation technologies. These are algal growth rate and lipid content. An updated economic analysis shows that growth rate is the more important of the two, and should be the focus of near term research activities. The long term goal of achieving zero cost will require other, non-biological, improvements in the process

  8. The use of flue gas for the growth of microalgal biomass

    Energy Technology Data Exchange (ETDEWEB)

    Zeiler, K.G.; Kadam, K.L.; Heacox, D.A. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1995-11-01

    Capture and utilization of carbon dioxide (CO{sub 2}) by microalgae is a promising technology to help reduce emissions from fossil fuel-fired power plants. Microalgae are of particular interest because of their rapid growth rates and tolerance to varying environmental conditions. Laboratory work is directed toward investigating the effects of simulated flue gas on microalgae, while engineering studies have focused on the economics of the technology. One strain of a green algae, Monoraphidium minutum, has shown excellent tolerance and growth when exposed to simulated flue gas which meets the requirements of the 1990 Clean Air Act Amendments (1990 CAAA). Biomass concentrations of {similar_to}2g/L have been measured in batch culture. Several other microalgae have also shown tolerance to simulated flue gas; however, the growth of these strains is not equivalent to that observed for M. minutum. Coupling the production of biodiesel or other microalgae-derived commodity chemicals with the use of flue gas carbon dioxide is potentially a zero-cost method of reducing the amount of carbon dioxide contributed to the atmosphere by fossil fuel-fired power plants. We have identified two major biological performance parameters which can provide sufficient improvement in this technology to render it cost-competitive with other existing CO{sub x} mitigation technologies. These are algal growth rate and lipid content. An updated economic analysis shows that growth rate is the more important of the two, and should be the focus of near term research activities. The long term goal of achieving zero cost will require other, non-biological, improvements in the process.

  9. Dinoflagelados em diversos habitats e hidroperíodos na zona costeira do sul do Brasil Dinoflagellates in different habitats and hydroperiods on the coast of southern Brazil

    Directory of Open Access Journals (Sweden)

    Luciana de Souza Cardoso

    2007-06-01

    Full Text Available Informações sobre a riqueza, densidade, diversidade e distribuição de dinoflagelados em habitats aquáticos (lagoas abertas e fechadas, canais, açudes e áreas úmidas, em relação aos períodos de águas altas e baixas, são apresentadas. O estudo baseou-se em amostragens realizadas em 23 pontos, localizados nas margens leste (área da Lagoa do Casamento e oeste (área do Butiazal de Tapes da laguna dos Patos, no ano de 2003. Foram identificados 11 táxons, cuja distribuição teve maior homogeneidade no período de águas altas. Durinskia baltica (Levander Carty & Cox foi o único táxon cuja distribuição não se alterou pelo hidroperíodo. Peridinium gatunense Nygaard foi uma espécie indicadora de águas altas e P. umbonatum Stein foi indicadora de habitats associados à área do Butiazal de Tapes. Esta área mostrou ter mais alta diversidade de Dinophyceae em relação à área da Lagoa do Casamento, independente do hidroperíodo, refletindo a maior diversidade e especificidade de habitats aquáticos. O tipo de habitat influenciou significativamente (pData on richness, density, diversity and distribution of dinoflagellates in aquatic habitats (open and closed lagoons, channels, reservoirs and wetlands during high and low water periods are presented. The study was based on 23 point samples, located on the eastern (Lagoa do Casamento area and western (Butiazal de Tapes area shores of Laguna dos Patos, in 2003. Eleven taxa were identified; taxon distribution was more homogeneous during the high-water period. Durinskia baltica (Levander Carty & Cox was the only taxon whose distribution was the same for both hydroperiods. Peridinium gatunense Nygaard was a high-water indicator species and P. umbonatum Stein was an indicator of habitats associated with the Butiazal de Tapes area. This area had higher Dinophyceae diversity than the Lagoa do Casamento area, regardless of hydroperiod, due to the higher diversity and specificity of aquatic

  10. Occurrence of four species of algae in the marine water of Hong Kong.

    Science.gov (United States)

    Chai, Yemao; Deng, Wen-Jing; Qin, Xing; Xu, Xiangrong

    2017-11-30

    Harmful algal blooms (HABs) have broken out frequently throughout the world in recent decades; they are caused by the rapid multiplication of algal cells in near-coastal waters polluted with nitrogen and phosphorus and greatly affect the quality of marine water and human health. Over the past several decades, climate change and increasing environmental degradation have provided favourable growth conditions for certain phytoplankton species. Therefore, it is essential to rapidly identify and enumerate harmful marine algae to control these species. In this study, quantitative PCR (qPCR) was used to detect four representative species of HABs that are widespread in the marine water of Hong Kong, namely, Alexandrium catenella, Pseudo-nitzschia spp., Karenia mikimotoi and Heterosigma akashiwo. We applied qPCR with the dye SYBR Green to detect Alexandrium spp. and Pseudo-nitzschia spp. and used TaqMan probe for the enumeration of Karenia mikimotoi and Heterosigma akashiwo. The total genomic DNA of these algae from Hong Kong marine water was extracted successfully using the CTAB method, and for each kind of alga, we constructed a ten-fold series of recombinant plasmid solutions containing certain gene fragments of 18S rDNA and ITS1-5.8S-ITS2 as standard samples. Ten-fold dilutions of the DNA of known numbers of the extracted algal cells were also used to create an additional standard curve. In this way, the relationship between the cell number and the related plasmid copy number was established. The qPCR assay displayed high sensitivity in monitoring marine water samples in which the low concentrations of harmful algae were not detected accurately by traditional methods. The results showed that the cell numbers of the four species were all in low abundance. For Alexandrium catenella, the cell abundances at 12 sites ranged from 3.8×10 2 to 4.3×10 3 cellsL -1 , while H. akashiwo, K. mikimotoi and Pseudo-nitzschia ranged from 1.1×10 2 to 1.3×10 3 , from 23 to 6.5×10 2

  11. Five red tide species in genus Prorocentrum including the description of Prorocentrum donghaiense Lu SP. nov. from the East China Sea

    Science.gov (United States)

    Lu, Dou-Ding; Goebel, Jeanette

    2001-12-01

    A new planktonic dinoflagellate, Prorocentrum donghaiense Lu sp. nov., is described in the present paper. The water sample was collected from the Changjiang Estuary, the East China Sea. The species identification is based on shape, size, surface micro-morphology, ornamentation of thecal plates and the architecture of the periflagellar area and the intercalary bands as seen by light and scanning electron microscope. Prorocentrum donghaiense Lu sp. nov. is compared with other prorocentrum species with respect to morphological characteristics and bloom behavior. It is not known whether Prorocentrum donghaiense Lu sp. nov produces phycotoxins like some other Prorocentrum species. Four other red tide species in the family Prorocentraceae (Dinophyceae), namely P. balticum, P. minimum, P. micans, P. triestinum, were examined and identified by light and scanning electron microscope. They have been recorded as bloom-forming species. Some aggregates of Prorocentrum are observed at the end of blooms. An event of strong discoloration caused by P. donghaiense could be detected by satellite sensor in the East China Sea in the late spring of 1995.

  12. Biodiversity patterns of plankton assemblages at the extremes of the Red Sea.

    Science.gov (United States)

    Pearman, J K; Kürten, S; Sarma, Y V B; Jones, B H; Carvalho, S

    2016-03-01

    The diversity of microbial plankton has received limited attention in the main basin of the Red Sea. This study investigates changes in the community composition and structure of prokaryotes and eukaryotes at the extremes of the Red Sea along cross-shelf gradients and between the surface and deep chlorophyll maximum. Using molecular methods to target both the 16S and 18S rRNA genes, it was observed that the dominant prokaryotic classes were Acidimicrobiia, Alphaproteobacteria and Cyanobacteria, regardless of the region and depth. The eukaryotes Syndiniophyceae and Dinophyceae between them dominated in the north, with Bacillariophyceae and Mamiellophyceae more prominent in the southern region. Significant differences were observed for prokaryotes and eukaryotes for region, depth and distance from shore. Similarly, it was noticed that communities became less similar with increasing distance from the shore. Canonical correspondence analysis at the class level showed that Mamiellophyceae and Bacillariophyceae correlated with increased nutrients and chlorophyll a found in the southern region, which is influenced by the input of Gulf of Aden Intermediate Water. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Biomass and species structure of the phytoplankton of an high mountain lake (Lake Paione Superiore, Central Alps, Italy

    Directory of Open Access Journals (Sweden)

    Roberta BETTINETTI

    1999-08-01

    Full Text Available In the framework of the EU MOLAR Project on “Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change” a three whole-year study (1996-1998 on the composition and dynamics of phytoplankton community of the high mountain lake, acid sensitive Lago Paione Superiore (LPS was carried out. The data were analyzed and compared with those gathered during the years 1991-1993. The phytoplankton was made up by nanoplanktonic unicellular algae, the only exception being the colonial Dinobryon sertularia. Just four species, belonging to Chrysophyceae (Chromulina sp., Dinobryon sertularia and Mallomonas alveolata and to Dinophyceae (Gymnodinium sp. were important as biomass and density, and they were always present throughout the year. The prevalence of potentially mixotrophic species suggests an adaptive strategy to the low environmental concentrations of inorganic carbon and phosphorus. The seasonal variations of the total biomass were similar to those observed in the previous years. The total number of species has increased; this could be related with the recent increase of the pH and of the alkalinity.

  14. Mapping of trophic states based on nutrients concentration and phytoplankton abundance in Jatibarang Reservoir

    Science.gov (United States)

    Rudiyanti, Siti; Anggoro, Sutrisno; Rahman, Arif

    2018-02-01

    Jatibarang Reservoir is one of the Indonesian Reservoirs, which used for human activities such as tourism and agriculture. These activities will provide input of organic matter and nutrients into the water. These materials will impact water quality and eutrophication process. Eutrophication is the water enrichment by nutrients, especially nitrogen and phosphorus which can promote the growth of phytoplankton. Some indicators of eutrophication are increasing nutrients, trophic states, and change of phytoplankton composition. The relationship between water quality and phytoplankton community can be used as an indicator of trophic states in Jatibarang Reservoir. The aim of this study was to analyze the effect of nutrients concentration and phytoplankton abundance to the trophic states and mapping trophic states based on nutrients concentration and phytoplankton in Jatibarang Reservoir. This study was conducted in June and July 2017 at 9 stations around Jatibarang Reservoir. The results showed that average concentration of nitrate, phosphate, and chlorophyll-a in Jatibarang Reservoir was 0.69 mg/L, 0.27 mg/L, and 1.66 mg/m3, respectively. The phytoplankton abundance ranged 16-62,200 cells/L, consists of 21 genera of four classes, i.e. Chlorophyceae, Cyanophyceae, Bacillariophyceae, and Dinophyceae. Cyanophyceae was a dominant phytoplankton group based on the composition of abundance (>80%). High nutrient concentrations and phytoplankton dominated by Anabaena (Cyanophyceae) which indicated that the waters in Jatibarang Reservoir were eutrophic.

  15. Determining Microeukaryotic Plankton Community around Xiamen Island, Southeast China, Using Illumina MiSeq and PCR-DGGE Techniques.

    Directory of Open Access Journals (Sweden)

    Lingyu Yu

    Full Text Available Microeukaryotic plankton are important components of aquatic environments and play key roles in marine microbial food webs; however, little is known about their genetic diversity in subtropical offshore areas. Here we examined the community composition and genetic diversity of the microeukaryotic plankton in Xiamen offshore water by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis, clone-based sequencing and Illumina based sequencing. The Illumina MiSeq sequencing revealed a much (approximately two orders of magnitude higher species richness of the microeukaryotic community than DGGE, but there were no significant difference in species richness and diversity among the northern, eastern, southern or western stations based on both methods. In this study, Copepoda, Ciliophora, Chlorophyta, Dinophyceae, Cryptophyta and Bacillariophyta (diatoms were the dominant groups even though diatoms were not detected by DGGE. Our Illumina based results indicated that two northern communities (sites N2 and N3 were significantly different from others in having more protozoa and fewer diatoms. Redundancy analysis (RDA showed that both temperature and salinity were the significant environmental factors influencing dominant species communities, whereas the full microeukaryotic community appeared to be affected by a complex of environmental factors. Our results suggested that extensive sampling combined with more deep sequencing are needed to obtain the complete diversity of the microeukaryotic community, and different diversity patterns for both abundant and rare taxa may be important in evaluating the marine ecosystem health.

  16. Suitability of phytosterols alongside fatty acids as chemotaxonomic biomarkers for phytoplankton

    Directory of Open Access Journals (Sweden)

    Sami Johan Taipale

    2016-03-01

    Full Text Available e composition and abundance of phytoplankton is important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids are needed for monitoring changes in phytoplankton community and to know nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers by analyzing sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes and by using multivariate statistics. We were able to detect totally 47 fatty acids and 29 sterols in our phytoplankton samples, which both differed statistically significantly between phytoplankton classes. Due to the high variation of fatty acid composition among cyanobacteria, taxonomical differentiation increased, when cyanobacteria were excluded from statistical analysis. Sterol composition was more heterogeneous within class than fatty acids and did not improve separation of phytoplankton classes when used alongside with fatty acids. However, we conclude that sterols can provide additional information on the abundance of specific genera within a class which can be generated by using fatty acids. For example, whereas high 16 ω-3 PUFAs (polyunsaturated fatty acid indicates the presence of Chlorophyceae, simultaneous high amount of ergosterol could specify the presence of Chlamydomonas spp. (Chlorophyceae. Additionally, we found specific 4α-methyl sterols for distinct Dinophyceae genus, suggesting that 4α-methyl sterols can potentially separate freshwater dinoflagellates from each other.

  17. Suitability of Phytosterols Alongside Fatty Acids as Chemotaxonomic Biomarkers for Phytoplankton.

    Science.gov (United States)

    Taipale, Sami J; Hiltunen, Minna; Vuorio, Kristiina; Peltomaa, Elina

    2016-01-01

    The composition and abundance of phytoplankton is an important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids) are needed for monitoring changes in a phytoplankton community and to know the nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers using multivariate statistics, by analyzing the sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes. We were able to detect a total of 47 fatty acids and 29 sterols in our phytoplankton samples, which both differed statistically significantly between phytoplankton classes. Due to the high variation of fatty acid composition among Cyanophyceae, taxonomical differentiation increased when Cyanophyceae were excluded from statistical analysis. Sterol composition was more heterogeneous within class than fatty acids and did not improve separation of phytoplankton classes when used alongside fatty acids. However, we conclude that sterols can provide additional information on the abundance of specific genera within a class which can be generated by using fatty acids. For example, whereas high C16 ω-3 PUFA (polyunsaturated fatty acid) indicates the presence of Chlorophyceae, a simultaneous high amount of ergosterol could specify the presence of Chlamydomonas spp. (Chlorophyceae). Additionally, we found specific 4α-methyl sterols for distinct Dinophyceae genera, suggesting that 4α-methyl sterols can potentially separate freshwater dinoflagellates from each other.

  18. Abundance of plankton population densities in relation to bottom soil textural types in aquaculture ponds

    Directory of Open Access Journals (Sweden)

    F. Siddika

    2012-06-01

    Full Text Available Plankton is an important food item of fishes and indicator for the productivity of a water body. The present study was conducted to evaluate the effects of bottom soil textural conditions on abundance of plankton in aquaculture pond. The experiment was carried out using three treatments, i.e., ponds bottom with sandy loam (T1, with loam (T2 and with clay loam (T3. The ranges of water quality parameters analyzed were suitable for the growth of plankton during the experimental period. Similarly, chemical properties of soil were also within suitable ranges and every parameter showed higher ranges in T2. A total 20 genera of phytoplankton were recorded belonged to Chlorophyceae (7, Cyanophyceae (5, Bacillariophyceae (5, Euglenophyceae (2 and Dinophyceae (1. On the other hand, total 13 genera of zooplankton were recorded belonged to Crustacea (7 and Rotifera (6. The highest ranges of phytoplankton and zooplankton densities were found in T2 where low to medium-type bloom was observed during the study period. Consequently, the mean abundance of plankton (phytoplankton and zooplankton density was significantly highest in T2. The highest abundance of plankton in the T2 indicated that pond bottom with loamy soil is suitable for the growth and production of plankton in aquaculture ponds.

  19. Composition and seasonal variation of phytoplankton community in Lake Hlan, Republic of Bénin

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    Arsène Mathieu Houssou

    2016-12-01

    Full Text Available Knowledge of biodiversity of aquatic ecosystems is nowadays a challenge for global research. Phytoplankton being very important in the sustainability of ecosystems, its mastery allows the development of early monitoring and evaluation tools of the health status of aquatic environments. The study aims to make an initial inventory of phytoplankton of the lake Hlan and to evaluate the influence of hydrologic season on its dynamics. Plankton samples were collected monthly between May and December 2012 using plankton net of 30 µm size. They were then treated and species identified using light microscopy. 39 species in 7 classes (Bacillariophyceae, 18 species in 10 genera, (Cyanophyceae, 5 species in 5 genera, (Chlorophyceae, 5 species in 3 genera, (Zygnematophyceae, 3 species in 2 genera, (Trebouxiophyceae, 2 species in 2 genera (Euglenophyceae, 4 species in 3 genera and (Dinophyceae, 2 species in 2 genera have been identified. The Shannon index varied between 4.8 and 5.1 bit cell-1. This shows that the ecosystem is balanced. Nevertheless, the presence of potentially toxic species requires a monitoring program for Lake Hlan.

  20. Biodiversity patterns of plankton assemblages at the extremes of the Red Sea

    KAUST Repository

    Pearman, John K.

    2016-01-07

    The diversity of microbial plankton has received limited attention in the main basin of the Red Sea. This study investigates changes in the community composition and structure of prokaryotes and eukaryotes at the extremes of the Red Sea along cross-shelf gradients and between the surface and deep chlorophyll maximum. Using molecular methods to target both the 16S and 18S rRNA genes, it was observed that the dominant prokaryotic classes were Acidimicrobiia, Alphaproteobacteria and Cyanobacteria, regardless of the region and depth. The eukaryotes Syndiniophyceae and Dinophyceae between them dominated in the north, with Bacillariophyceae and Mamiellophyceae more prominent in the southern region. Significant differences were observed for prokaryotes and eukaryotes for region, depth and distance from shore. Similarly, it was noticed that communities became less similar with increasing distance from the shore. Canonical correspondence analysis at the class level showed that Mamiellophyceae and Bacillariophyceae correlated with increased nutrients and chlorophyll a found in the southern region, which is influenced by the input of Gulf of Aden Intermediate Water.

  1. Microbial activity during a coastal phytoplankton bloom on the Western Antarctic Peninsula in late summer.

    Science.gov (United States)

    Alcamán-Arias, María E; Farías, Laura; Verdugo, Josefa; Alarcón-Schumacher, Tomás; Díez, Beatriz

    2018-05-01

    Phytoplankton biomass during the austral summer is influenced by freezing and melting cycles as well as oceanographic processes that enable nutrient redistribution in the West Antarctic Peninsula (WAP). Microbial functional capabilities, metagenomic and metatranscriptomic activities as well as inorganic 13C- and 15N-assimilation rates were studied in the surface waters of Chile Bay during two contrasting summer periods in 2014. Concentrations of Chlorophyll a (Chla) varied from 0.3 mg m-3 in February to a maximum of 2.5 mg m-3 in March, together with a decrease in nutrients; however, nutrients were never depleted. The microbial community composition remained similar throughout both sampling periods; however, microbial abundance and activity changed with Chla levels. An increased biomass of Bacillariophyta, Haptophyceae and Cryptophyceae was observed along with night-grazing activity of Dinophyceae and ciliates (Alveolates). During high Chla conditions, HCO3- uptake rates during daytime incubations increased 5-fold (>2516 nmol C L-1 d-1), and increased photosynthetic transcript numbers that were mainly associated with cryptophytes; meanwhile night time NO3- (>706 nmol N L-1 d-1) and NH4+ (41.7 nmol N L-1 d-1) uptake rates were 2- and 3-fold higher, respectively, due to activity from Alpha-/Gammaproteobacteria and Bacteroidetes (Flavobacteriia). Due to a projected acceleration in climate change in the WAP, this information is valuable for predicting the composition and functional changes in Antarctic microbial communities.

  2. Phytoplankton community and limnology of Chatla floodplain wetland of Barak valley, Assam, North-East India

    Directory of Open Access Journals (Sweden)

    Sultana Laskar H.

    2013-09-01

    Full Text Available Phytoplankton diversity was investigated over a period of two years (2006 to 2008 in Chatla floodplain wetland in Barak valley, Assam, North-East India. Site 1 and site 2 are two inlets and site 3 is a lentic system associated with vegetation cover of Calamus tenuis and Baringtonia acutangula. The floodplain has a unique hydrology because of the presence of different types of habitats (inlets, fisheries, beels and outlets which maintains a network among the floodplains, rivers and streams. Phytoplankton community composition, density and diversity were studied in relation to environmental variables. All the variables were estimated by following standard methods. Phytoplankton was collected by plankton net and quantitative estimation was made by using Sedgwick Rafter counting cell. Phytoplankton community comprised 53 taxa represented by Chlorophyceae (31, Cyanophyceae (11, Bacillariophyceae (7, Euglenophyceae (1 and Dinophyceae (3. Phytoplankton taxa was dominated by Volvox sp., Nostoc sp., Eunotia sp., Navicula sp., Euglena spp. and density was found highest in site 3 and lowest in site 1. Shannon diversity index (H′ for phytoplankton community varied between 2.4 to 2.65 indicating fairly high species diversity. The varying magnitude of correlationship among environmental variables and phytoplankton species density as shown by Canonical correspondence analysis (CCA indicated that some of the environmental variables (water temperature, transparency, rainfall, nitrate and ammonia are the driving factors for governing the phytoplankton species assemblages in Chatla floodplain wetland. Fluctuation of phytoplankton density and community composition in different habitats indicated various niche apportionment as well as anthropogenic influences.

  3. Microbial planktonic communities in the Red Sea: high levels of spatial and temporal variability shaped by nutrient availability and turbulence

    KAUST Repository

    Pearman, John K.; Ellis, Joanne; Irigoien, Xabier; Yellepeddi, Sarma B.; Jones, Burton; Carvalho, Susana

    2017-01-01

    The semi-enclosed nature of the Red Sea (20.2°N-38.5°N) makes it a natural laboratory to study the influence of environmental gradients on microbial communities. This study investigates the composition and structure of microbial prokaryotes and eukaryotes using molecular methods, targeting ribosomal RNA genes across different regions and seasons. The interaction between spatial and temporal scales results in different scenarios of turbulence and nutrient conditions allowing for testing of ecological theory that categorizes the response of the plankton community to these variations. The prokaryotic reads are mainly comprised of Cyanobacteria and Proteobacteria (Alpha and Gamma), with eukaryotic reads dominated by Dinophyceae and Syndiniophyceae. Periodic increases in the proportion of Mamiellophyceae and Bacillariophyceae reads were associated with alterations in the physical oceanography leading to nutrient increases either through the influx of Gulf of Aden Intermediate Water (south in the fall) or through water column mixing processes (north in the spring). We observed that in general dissimilarity amongst microbial communities increased when nutrient concentrations were higher, whereas richness (observed OTUs) was higher in scenarios of higher turbulence. Maximum abundance models showed the differential responses of dominant taxa to temperature giving an indication how taxa will respond as waters become warmer and more oligotrophic.

  4. Biodiversity patterns of plankton assemblages at the extremes of the Red Sea

    KAUST Repository

    Pearman, John K.; Kurten, Saskia; Yellepeddi, Sarma B.; Jones, Burton; Carvalho, Susana

    2016-01-01

    The diversity of microbial plankton has received limited attention in the main basin of the Red Sea. This study investigates changes in the community composition and structure of prokaryotes and eukaryotes at the extremes of the Red Sea along cross-shelf gradients and between the surface and deep chlorophyll maximum. Using molecular methods to target both the 16S and 18S rRNA genes, it was observed that the dominant prokaryotic classes were Acidimicrobiia, Alphaproteobacteria and Cyanobacteria, regardless of the region and depth. The eukaryotes Syndiniophyceae and Dinophyceae between them dominated in the north, with Bacillariophyceae and Mamiellophyceae more prominent in the southern region. Significant differences were observed for prokaryotes and eukaryotes for region, depth and distance from shore. Similarly, it was noticed that communities became less similar with increasing distance from the shore. Canonical correspondence analysis at the class level showed that Mamiellophyceae and Bacillariophyceae correlated with increased nutrients and chlorophyll a found in the southern region, which is influenced by the input of Gulf of Aden Intermediate Water.

  5. Microbial planktonic communities in the Red Sea: high levels of spatial and temporal variability shaped by nutrient availability and turbulence

    KAUST Repository

    Pearman, John K.

    2017-07-20

    The semi-enclosed nature of the Red Sea (20.2°N-38.5°N) makes it a natural laboratory to study the influence of environmental gradients on microbial communities. This study investigates the composition and structure of microbial prokaryotes and eukaryotes using molecular methods, targeting ribosomal RNA genes across different regions and seasons. The interaction between spatial and temporal scales results in different scenarios of turbulence and nutrient conditions allowing for testing of ecological theory that categorizes the response of the plankton community to these variations. The prokaryotic reads are mainly comprised of Cyanobacteria and Proteobacteria (Alpha and Gamma), with eukaryotic reads dominated by Dinophyceae and Syndiniophyceae. Periodic increases in the proportion of Mamiellophyceae and Bacillariophyceae reads were associated with alterations in the physical oceanography leading to nutrient increases either through the influx of Gulf of Aden Intermediate Water (south in the fall) or through water column mixing processes (north in the spring). We observed that in general dissimilarity amongst microbial communities increased when nutrient concentrations were higher, whereas richness (observed OTUs) was higher in scenarios of higher turbulence. Maximum abundance models showed the differential responses of dominant taxa to temperature giving an indication how taxa will respond as waters become warmer and more oligotrophic.

  6. [Phytoplankton community in a recreational fishing lake, Brazil].

    Science.gov (United States)

    Matsuzaki, Mayla; Mucci, José Luiz Negrão; Rocha, Aristides Almeida

    2004-10-01

    The assessment of water quality and phytoplankton community in recreational environments allows to setting management programs aiming at preventing potential harm to human health. The purpose of the present study was to describe phytoplankton seasonal changes in a freshwater system and their relation to water quality. The recreational fishing lake is located in the southern area of the city of São Paulo, Brazil. Water samples were collected in three previously selected sites in the lake throughout a year and analyzed regarding floristic composition and physical and chemical parameters. The phytoplankton qualitative analysis revealed 91 taxa distributed among eight classes: Chlorophyceae, Cyanophyceae, Euglenophyceae, Zygnemaphyceae, Bacillariophyceae, Xantophyceae, Dinophyceae, and Chrysophyceae. Some physical and chemical parameters seemed to influence phytoplankton community behavior. Chlorophyceae development was favored by local conditions. Among the species of cyanobacteria identified, Microcystis paniformis, Cylindrospermopsis raciborskii, and Anabaena species were the most important due to their ability to produce toxins, posing a high risk to public health. Some physical and chemical parameters had an impact on the structure of phytoplankton community. The presence of Microcystis paniformis, Cylindrospermopsis raciborskii and Anabaena species indicates toxic potential and likelihood of public health problems unless there is constant monitoring. Further studies are recommended to prevent hazardous effects to the environment and public health.

  7. Seasonal and interannual study of volatile reduced sulfur compounds (VRSC) in coastal environment: the Bay of Quiberon (Brittany, France)

    Science.gov (United States)

    Cozic-Houly, A.; Viollier, E.; Sarazin, G.; Knoery, J.

    2009-10-01

    Seasonal and annual variability of hydrogen sulfide (H2S), carbonyl sulfide (OCS), methane thiol (MeSH), dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) concentrations and supporting parameters (e.g., phytoplanktonic cells abundance) were investigated in a coastal marine environment, the Bay of Quiberon (Brittany, France) from July 2004 to August 2006. The sampling was conducted in the water column, within two meters of the sediment water interface (SWI). Minimum and maximum values were <0.1-1.6 nmol L-1 for H2S, <0.1-4.2 nmol L-1 for OCS, <0.1-7.8 nmol L-1 for MeSH, <0.1-17.5 nmol L-1 for DMS and <0.1-1.7 nmol L-1 for DMDS. Vertical carbonyl sulfide distribution showed seasonal variations with lower concentration near the SWI in winter and bottom enrichments near sediments in summer. Vertical sulfide distribution not seems to be influenced by the shallow sediments. The likely influence of Dinophyceae abundance on the MeSH, DMS and DMDS concentrations was evident for the 3-summer monitored period.

  8. Environmental gradients regulate the spatio-temporal variability of phytoplankton assemblages in the Can Gio Mangrove Biosphere Reserve, Vietnam

    Science.gov (United States)

    Pham, Thanh-Luu

    2017-12-01

    This paper covers spatial and temporal variation in phytoplankton communities and physico-chemical variables in the Can Gio Mangrove Biosphere Reserve (CGMBR), Vietnam, based on field measurement conducted monthly at nine stations during February 2009 to January 2010. Species diversity, richness and phytoplankton abundance were calculated. Canonical Correspondence Analysis (CCA) was used to investigate the relationship between environmental factors and phytoplankton community. A total of 126 species were recorded with a clear dominance of Bacillariophyceae, which formed about 76.4% of the total phytoplankton counts with an annual average of 44.900 cells/L. Other algal classes like Dinophyceae, Cyanophyceae and Chrysophyceae sustained low counts, forming collectively about 14% of the total abundance of phytoplankton. Although Chaetoceros and Coscinodiscus were the most dominant genera, Schroederella and Skeletonema showed high abundance during the studied period. Among the nine environmental parameters tested in this study, salinity, nitrate and ammonium were found to be significantly different between two seasons. On the other hand, no significant difference was found between stations for the studied variables. Results of CCA indicated that phytoplankton assemblage in the CGMBR was influenced by salinity, nitrate and phosphate concentration. This is the first study simultaneously investigating the phytoplankton communities and their environment in this area and it is essential in order to set up the baseline of future studies.

  9. Development of phytoplankton communities: Implications of nutrient injections on phytoplankton composition, pH and ecosystem production

    DEFF Research Database (Denmark)

    Jakobsen, Hans; Blanda, Elisa; Stæhr, Peter Anton

    2015-01-01

    The development of a marine phytoplankton community was studied in a series of mesocosm tanks exposed to different levels of nutrient inputs. Key ecosystem variables such as phytoplankton species development, ecosystem net production (NEP), pH and bacteria production were measured. The overall aim...... was to mimic the consequences of extreme weather events by applying nutrients in either repeated (pulse treatment) versus a single inputs (full treatment). Regardless of treatment type, pH increased steadily, until nutrients became exhausted. During the experiment, potentially nuisance dinoflagellates...... developed and became dominant whereas diatoms became rare as compared to the parallel controls. At pH > 9, a shift from the presence of the potential nuisance Alexandrium pseudogonyaulax towards high pH tolerant Prorocentrum species was observed. Diatoms disappeared when A. pseudogonyaulax became dominant...

  10. Fight and flight in dinoflagellates?

    DEFF Research Database (Denmark)

    Selander, Erik; Fagerberg, Tony; Wohlrab, Sylke

    2012-01-01

    We monitored the kinetics of grazer-induced responses in the marine dinoflagellate Alexandrium tamarense. Chemical cues from each of three calanoid copepods (Calanus sp., Centropages typicus, and Acartia tonsa) induced increased toxicity and suppressed chain formation in A. tamarense. Both chemical...... and morphological responses augmented over 3 d. Toxicity subsequently averaged 299% higher than controls, and average biovolume 24% lower than controls because of suppression of chain formation in grazed treatments. Grazer-induced toxicity returned to control levels after approximately 11 d, equivalent to five cell...... that the inducing cue(s) attenuate rapidly in seawater, which allows A. tamarense to adjust resource allocation to grazer-induced responses to follow fluctuations in grazer density. Grazer-induced responses, however, develop too slowly to be accounted for in short-term grazing experiments with laboratory cultures...

  11. Foraging response and acclimation of ambush feeding and feeding-current feeding copepods to toxic dinoflagellates

    DEFF Research Database (Denmark)

    Xu, Jiayi; Nielsen, Lasse Tor; Kiørboe, Thomas

    2018-01-01

    reticulatum. We hypothesize (1) that ambush feeders are less affected by toxic algae than feeding-current feeders, (2) that copepods acclimate to the toxic algae, and (3) that phytoplankton cells previously exposed to copepod cues elicit stronger responses. Both copepod species consumed the toxic algae...... to examine the response and temporal acclimation (5 d) of two copepods with different foraging behaviors to toxic dinoflagellates. Feeding-current feeding Temora longicornis and ambush feeding Acartia tonsa were offered three strains of toxic Alexandrium tamarense and a nontoxic control Protoceratium...... at a reduced rate and there was no difference in their net-response, but the mechanisms differed. T. longicornis responded in strain-specific ways by reducing its feeding activity, by rejecting captured algae, or by regurgitating consumed cells. A. tonsa reduced its consumption rate, jump frequency, and jump...

  12. Fatal paralytic shellfish poisoning in Kittlitz's Murrelet (Brachyramphus brevirostris) nestlings, Alaska, USA

    Science.gov (United States)

    Shearn-Bochsler, Valerie I.; Lance, Ellen W.; Corcoran, Robin; Piatt, John F.; Bodenstein, Barbara; Frame, Elizabeth; Lawonn, James

    2014-01-01

    Paralytic shellfish poisoning (PSP) is an acute toxic illness in humans resulting from ingestion of shellfish contaminated with a suite of neurotoxins (saxitoxins) produced by marine dinoflagellates, most commonly in the genus Alexandrium. Poisoning also has been sporadically suspected and, less often, documented in marine wildlife, often in association with an outbreak in humans. Kittlitz's Murrelet (Brachyramphus brevirostris) is a small, rare seabird of the Northern Pacific with a declining population. From 2008 to 2012, as part of a breeding ecology study, multiple Kittlitz's Murrelet nests on Kodiak Island, Alaska, were monitored by remote cameras. During the 2011 and 2012 breeding seasons, nestlings from several sites died during mild weather conditions. Remote camera observations revealed that the nestlings died shortly after consuming sand lance (Ammodytes hexapterus), a fish species known to biomagnify saxitoxin. High levels of saxitoxin were subsequently documented in crop content in 87% of nestling carcasses. Marine bird deaths from PSP may be underreported.

  13. Uncovering the Complex Transcriptome Response of Mytilus chilensis against Saxitoxin: Implications of Harmful Algal Blooms on Mussel Populations

    Science.gov (United States)

    Detree, Camille; Núñez-Acuña, Gustavo; Roberts, Steven; Gallardo-Escárate, Cristian

    2016-01-01

    Saxitoxin (STX), a principal phycotoxin contributing to paralytic shellfish poisoning, is largely produced by marine microalgae of the genus Alexandrium. This toxin affects a wide range of species, inducing massive deaths in fish and other marine species. However, marine bivalves can resist and accumulate paralytic shellfish poisons. Despite numerous studies on the impact of STX in marine bivalves, knowledge regarding STX recognition at molecular level by benthic species remains scarce. Therefore, the aim of this study was to identify novel genes that interact with STX in the Chilean mussel Mytilus chilensis. For this, RNA-seq and RT-qPCR approaches were used to evaluate the transcriptomic response of M. chilensis to a purified STX as well as in vivo Alexandrium catenella exposure. Approximately 800 million reads were assembled, generating 138,883 contigs that were blasted against the UniProt Mollusca database. Pattern Recognition Receptors (PRRs) involved in mussel immunity, such as Toll-like receptors, tumor necrosis factor receptors, and scavenger-like receptors were found to be strongly upregulated at 8 and 16 h post-STX injection. These results suggest an involvement of PRRs in the response to STX, as well as identifying potential, novel STX-interacting receptors in this Chilean mussel. This study is the first transcriptomic overview of the STX-response in the edible species M. chilensis. However, the most significant contribution of this work is the identification of immune receptors and pathways potentially involved in the recognition and defense against STX’s toxicity and its impact of harmful algae blooms on wild and cultivated mussel populations. PMID:27764234

  14. The Dinoflagellate Toxin 20-Methyl Spirolide-G Potently Blocks Skeletal Muscle and Neuronal Nicotinic Acetylcholine Receptors

    Directory of Open Access Journals (Sweden)

    Aurélie Couesnon

    2016-08-01

    Full Text Available The cyclic imine toxin 20-methyl spirolide G (20-meSPX-G, produced by the toxigenic dinoflagellate Alexandrium ostenfeldii/Alexandrium peruvianum, has been previously reported to contaminate shellfish in various European coastal locations, as revealed by mouse toxicity bioassay. The aim of the present study was to determine its toxicological profile and its molecular target selectivity. 20-meSPX-G blocked nerve-evoked isometric contractions in isolated mouse neuromuscular preparations, while it had no action on contractions elicited by direct electrical stimulation, and reduced reversibly nerve-evoked compound muscle action potential amplitudes in anesthetized mice. Voltage-clamp recordings in Xenopus oocytes revealed that 20-meSPX-G potently inhibited currents evoked by ACh on Torpedo muscle-type and human α7 nicotinic acetylcholine receptors (nAChR, whereas lower potency was observed in human α4β2 nAChR. Competition-binding assays showed that 20-meSPX-G fully displaced [3H]epibatidine binding to HEK-293 cells expressing the human α3β2 (Ki = 0.040 nM, whereas a 90-fold lower affinity was detected in human α4β2 nAChR. The spirolide displaced [125I]α-bungarotoxin binding to Torpedo membranes (Ki = 0.028 nM and in HEK-293 cells expressing chick chimeric α7-5HT3 nAChR (Ki = 0.11 nM. In conclusion, this is the first study to demonstrate that 20-meSPX-G is a potent antagonist of nAChRs, and its subtype selectivity is discussed on the basis of molecular docking models.

  15. Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America Estrategias ecofisiológicas en respuesta a la radiación ultravioleta-B en cultivos de microalgas templadas aisladas de la costa sudamericana del Pacífico

    Directory of Open Access Journals (Sweden)

    VIVIAN MONTECINO

    2001-06-01

    Full Text Available Marine microalgae exposed to ultraviolet radiation (UV have complex adaptive responses provided by a series of protection and repair mechanisms. Interspecific differences in UV sensibility could result in differential selection of the more tolerant species, having consequences for the structure of phytoplankton assemblages. The relative importance of protection and photorepair mechanisms of microalgal cells exposed to potential UV-B stress was studied in monocultures with different taxonomic, ecological and size characteristics obtained from the Chilean coast. Differences in photosynthesis and growth rates were predicted, since the ability to effectively acclimate to UV is not universal between microalgal species. The dinoflagellate Alexandrium catenella Whedon et Kofoid Balech, the diatom Phaeodactylum tricornutum Bohlin, the chrysophyte Aureococcus sp. and the cyanobacterium Spirulina subsalsa Oersted were acclimated during exponential cell growth under PAR + UV-A radiation (365 nm, 140-240 kJ m-2 d-1 and thereafter exposed 2 h d-1 to high and low UV-B radiation (312 nm, maximum 3.1 kJ m-2 d-1 at the center of the 16 h light period. Measured parameters were growth rates (µ, in vivo spectral absorption, cellular fluorescence capacity, pigment concentration, photosynthesis and photoreactivation during three cycles in controls and treatment samples. Growth rates diminished less than 35 % in Phaeodactylum and Aureococcus compared to 80-100 % decrease in Alexandrium and Spirulina. In these two last species, a significant increase in UV absorbing substances was observed, probably related to the presence of mycosporine-like aminoacids (MAAs and scytonemin, respectively, and also lower photoreactivation efficiency compared to Phaeodactylum and Aureococcus. The analysis of photosynthetic performance under different PAR/UV-A ratios for Alexandrium and Phaeodactylum, could also explain the differences in µ. These results suggest that in time, species

  16. The scavenger receptor repertoire in six cnidarian species and its putative role in cnidarian-dinoflagellate symbiosis

    Directory of Open Access Journals (Sweden)

    Emilie F. Neubauer

    2016-11-01

    Full Text Available Many cnidarians engage in a mutualism with endosymbiotic photosynthetic dinoflagellates that forms the basis of the coral reef ecosystem. Interpartner interaction and regulation includes involvement of the host innate immune system. Basal metazoans, including cnidarians have diverse and complex innate immune repertoires that are just beginning to be described. Scavenger receptors (SR are a diverse superfamily of innate immunity genes that recognize a broad array of microbial ligands and participate in phagocytosis of invading microbes. The superfamily includes subclades named SR-A through SR-I that are categorized based on the arrangement of sequence domains including the scavenger receptor cysteine rich (SRCR, the C-type lectin (CTLD and the CD36 domains. Previous functional and gene expression studies on cnidarian-dinoflagellate symbiosis have implicated SR-like proteins in interpartner communication and regulation. In this study, we characterized the SR repertoire from a combination of genomic and transcriptomic resources from six cnidarian species in the Class Anthozoa. We combined these bioinformatic analyses with functional experiments using the SR inhibitor fucoidan to explore a role for SRs in cnidarian symbiosis and immunity. Bioinformatic searches revealed a large diversity of SR-like genes that resembled SR-As, SR-Bs, SR-Es and SR-Is. SRCRs, CTLDs and CD36 domains were identified in multiple sequences in combinations that were highly homologous to vertebrate SRs as well as in proteins with novel domain combinations. Phylogenetic analyses of CD36 domains of the SR-B-like sequences from a diversity of metazoans grouped cnidarian with bilaterian sequences separate from other basal metazoans. All cnidarian sequences grouped together with moderate support in a subclade separately from bilaterian sequences. Functional experiments were carried out on the sea anemone Aiptasia pallida that engages in a symbiosis with Symbiodinium minutum

  17. Checklist of the benthic marine and brackish Galician algae (NW Spain

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    Bárbara, Ignacio

    2005-06-01

    Full Text Available We present an annotated checklist of the benthic marine and brackish algae of the Galician coasts (Spain based on literature records and new collections. This checklist includes 618 species: 118 Cyanophyta, 296 Rhodophyta, 127 Ochrophyta, and 77 Chlorophyta. The number of specific, infraspecific taxa, and stages is 643: 121 Cyanophyta, 309 Rhodophyta, 135 Ochrophyta, and 79 Chlorophyta. Hyella caespitosa var. nitida, Calothrix fasciculata, Gracilariopsis longissima, Compsonema minutum, and Sphacelaria tribuloides are new records for Galicia, and there are also some new provincial records. We state the presence of each species for Lugo (Lu, A Coruña (Co, and Pontevedra (Po provinces. The number of species found in Galicia is high, since 85% of the species recorded for the warm-temperate NE Atlantic Ocean grow in Galicia. Biogeographical comments comparing the Galician data with the neighboring areas of Britain and Ireland, Basque coast, Portugal, southern Iberian Peninsula, Canary Islands and Atlantic coast of Morocco are given. Finally, we present lists of cold-temperate, warm-temperate, Lusitanic Province endemics, and alien species growing in Galicia.Se presenta una lista comentada de las especies de algas bentónicas marinas y salobres de la costa de Galicia (España basada en citas bibliográficas y nuevos datos de los autores. La lista contiene 618 especies: 118 Cyanophyta, 296 Rhodophyta, 127 Ochrophyta y 77 Chlorophyta. El número de taxa específicos e infraespecíficos asciende a 643: 121 Cyanophyta, 309 Rhodophyta, 135 Ochrophyta y 79 Chlorophyta. Hyella caespitosa var. nitida, Calothrix fasciculata, Gracilariopsis longissima, Compsonema minutum y Sphacelaria tribuloides son nuevas citas para Galicia, y algunas nuevas citas provinciales. Para cada especie se especifica su presencia en las provincias de Lugo (Lu, A Coruña (Co y Pontevedra (Po. El número de especies encontradas en Galicia es elevado, ya que se conocen el 85% de las

  18. Estructura comunitaria de diatomeas presentes en los sedimentos superficiales de ocho lagos andinos de Chile central Diatoms community structure in superficial sediments of eight Andean lakes of central Chile

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    INGRID E ALVIAL

    2008-03-01

    Full Text Available En este trabajo se analizó la estructura comunitaria de diatomeas depositadas en los sedimentos superficiales de ocho lagos andinos chilenos ubicados entre los 32°49' y 38°48' S. Se encontró un total de 99 taxa de diatomeas, distribuidos en 48 géneros. Del total de taxa, 74 fueron identificados a nivel de especie siendo todos ellos cosmopolitas a excepción de Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis y Pinnularia acidicola, entre otras, que están descritos solo para el Hemisferio Sur. Por otro lado, las muestras analizadas presentaron distinta composición florística de diatomeas. De esta manera, en los ensambles diatomológicos depositados en los sedimentos de las lagunas de altura Ocho, Huifa, Ensueño y Negra ubicadas sobre los 2.860 m del nivel del mar, abundaron especies bentónicas, típicas de aguas oligotróficas y acidas como Achnanthidium exiguum, Achnanthidium minutissimum, Encyonema minutum, Pinnularia acidicola y Planothidium lanceolatum. En los ensambles diatomológicos de los lagos Galletué, Icalma y Laja, ubicados bajo los 1.360 m del nivel del mar, abundaron diatomeas planctónicas, características de aguas alcalinas y mesotróficas como Asterionella formosa, Aulacoseira distans, Aulacoseira granulata, Cyclotella stelligera y Rhopalodia gibbaIn this research the taxonomic structure of diatoms in sediments of high mountain lakes was studied. These lakes are located in Chile between 32°49' and 38°48' S in the Andean Cordillera. A total of 99 diatom taxa distributed in 48 genera were identified and all this taxa are cosmopolitan excepting a Eunotia andinofrequens, Gomphonema punae, Pinnularia araucanensis and Pinnularia acidicola, which are know only for the Southern Hemisphere. The assemblages of diatoms were different in the studied lakes. So the high mountain lakes Ocho, Huifa, Ensueño and Negra, dominated benthic diatoms which are typical of oligotrophic and acid waters as Achnanthidium

  19. Comunidade fitoplanctônica de um pesqueiro na cidade de São Paulo Phytoplankton community in a recreational fishing lake, Brazil

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    Mayla Matsuzaki

    2004-10-01

    Full Text Available OBJETIVO: A avaliação da qualidade da água e da comunidade fitoplanctônica em ambientes destinados à recreação permite estabelecer formas de manejo desses sistemas, evitando possíveis problemas à saúde humana. Assim, realizou-se estudo com objetivo de analisar a variação sazonal do fitoplâncton de um sistema lacustre natural, e sua relação com a qualidade da água. MÉTODOS: O lago estudado faz parte de um pesqueiro localizado na zona sul da cidade de São Paulo. Foram realizadas quatro coletas no período de um ano, em três pontos de amostragem. As amostras foram analisadas quanto à composição florística e às variáveis físicas e químicas da água. RESULTADOS: A análise qualitativa do fitoplâncton revelou o total de 91 táxons distribuídos em oito classes: Chlorophyceae (52%, Cyanophyceae (16%, Euglenophyceae (12%, Zygnemaphyceae (10%, Bacillariophyceae (5%, Xantophyceae (3%, Dinophyceae (1% e Chrysophyceae (1%. Alguns dos parâmetros físicos e químicos parecem ter influenciado o comportamento do fitoplâncton; a classe Chlorophyceae foi a mais favorecida pelas condições ambientais. Dentre as espécies de cianofíceas identificadas, destacaram-se Microcystis paniformis, Cylindrospermopsis raciborskii e espécies de Anabaena, que apresentaram maior importância do ponto de vista sanitário devido à produção de toxinas. CONCLUSÕES: Algumas variáveis físicas e químicas da água interferiram na estrutura da comunidade fitoplanctônica. A presença de Microcystis paniformis, Cylindrospermopsis raciborskii e espécies de Anabaena indicam o potencial tóxico e os possíveis problemas que podem ocorrer à saúde pública, caso esse ambiente não seja continuamente monitorado. Estudos adicionais são recomendados, com a finalidade de se evitar efeitos deletérios ao ambiente e à saúde da população.OBJECTIVE: The assessment of water quality and phytoplankton community in recreational environments allows to setting

  20. Estudio Ficológico de lagos urbanos artificiales del sur de la provincia de Córdoba Phycological study of artificial urban reservoirs of the South of the province of Córdoba

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    Martín David Novoa

    2006-12-01

    Full Text Available El presente trabajo fue realizado en dos lagos urbanos artificiales de Río Cuarto (Córdoba: Parque Sarmiento y Villa Dalcar, durante el año 2003. El objetivo fue: conocer y comparar la composición algal, su relación con parámetros ambientales y registros bacteriológicos en ambos lagos. Se determinaron 275 taxa: 178 Bacillariophyceae , 60 Chlorophyceae , 21 Cyanophyceae , 13 Euglenophyceae , 2 Dinophyceae y 1 Chrysophyceae . Las especies y/o variedades fueron registradas por primera vez para el área de estudio, 53 son nuevas citas para la provincia de Córdoba y 8 para la Argentina. El lago con mayor número de especies propias fue el Villa Dalcar. El Parque Sarmiento en otoño, registró un gran número de clorofíceas propias de este lago. Se evidenciaron dos floraciones en el lago Villa Dalcar: estival de Aphanizomenon flos-aquae y primaveral de Peridinium pusillum . El índice de Jaccard evidenció la mayor similitud entre los sitios Este y Centro en otoño, para el lago Parque Sarmiento y Salida y Malón, en verano, para el lago Villa Dalcar. Según el Índice de Sorensen-Dice aplicado a ambos lagos y estaciones del año, la máxima similitud fue entre los sitios Salida del Villa Dalcar y Este del Parque Sarmiento, en invierno. En primavera y verano se registró un número elevado de bacterias coliformes en el sitio Puente Oeste del lago Parque Sarmiento , y en el sitio el Malón del lago Villa Dalcar, en verano.The present work was carried out in two urban lakes in Río Cuarto (Córdoba, Argentina: Parque Sarmiento and Villa Dalcar, during the year 2003. The objective was to know and to compare the algal composition and its relation with environmental parameters and bacteriological registries in both lakes. 275 taxa were determined: 178 Bacillariophyceae , 60 Chlorophyceae , 21 Cyanophyceae , 13 Euglenophyceae , 2 Dinophyceae and 1 Chrysophyceae. The species and/or varieties are registred for the irst time in the study area, 53 are

  1. Kelimpahan dan Keanekaragaman Plankton di Perairan Selat Bali (Plankton Abundance and Diversity in the Bali Strait

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    Ruly Isfatul Khasanah

    2013-12-01

    Full Text Available Fitoplankton mempunyai peran sangat penting dalam suatu perairan, selain berada pada dasar rantai makanan sedangkan zooplankton merupakan herbivor pemangsanya. Penelitian mengenai kelimpahan dan keanekaragaman plankton di perairan Selat Bali dilakukan pada musim peralihan II (Nopember 2012 dan musim barat (Pebruari 2013. Penelitian bertujuan untuk mengamati perbedaan kelimpahan dan keanekaragaman plankton pada dua musim angin muson. Sampel air diambil dengan menggunakan water sampler sedangkan sampel plankton diambil secara horisontal dan vertikal  pada kedalaman 1 m dan 20 m dengan jaring plankton Kitahara bermata jaring 20 µm. Hasil pengukuran nutrien pada musim peralihan II memiliki kadar fosfat, nitrat, bahan organik, silikat dan klorofil-a lebih tinggi dibandingkan pada musim barat. Informasi tersebut memperkuat indikasi adanya perpindahan massa air dari lapisan yang lebih dalam ke lapisan yang lebih dangkal. Nutrien fosfat dan nitrat diperlukan untuk mempertahankan fungsi membran sel dan silikia dibutuhkan untuk pembentukan dinding sel terutama pada diatom. Hasil penelitian juga menunjukkan bahwa kelas diatom (Bacillariophyceae mencapai 95,9 % dari total jenis dan kelimpahan fitoplankton seluruh stasiun penelitian, sisanya berasal dari genus Dinophyceae. Kelimpahan fitoplankton tertinggi terjadi pada musim peralihan II dengan Rhizosolenia stolterfothii sebesar 51.405 sel.L-1 (80,1%, sedangkan pada musim barat copepoda ditemukan melimpah sebesar 8.178 ind.L-1 (88,3 %. Hasil ini mengindikasikan bahwa dengan kelimpahan plankton yang ditemukan perairan Selat Bali dinilai cukup potensial untuk mendukung kehidupan biota laut pelagis. Kata kunci: plankton, selat Bali, rhizosolenia stolterfothii, muson   Abstract Phytoplankton has important role as primary producer in the sea and act as base of food chain while zooplankton act as herbivore prey on them. Research on abundance and diversity of plankton at Bali Strait was performed during

  2. Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms

    International Nuclear Information System (INIS)

    Thi Thuy Duong; Morin, Soizic; Herlory, Olivier; Feurtet-Mazel, Agnes; Coste, Michel; Boudou, Alain

    2008-01-01

    The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems

  3. Myxomycetes from mangroves: species occurring in the state of Maranhão, northeastern Brazil

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    L. A. N. N. Agra

    Full Text Available Abstract Mangrove swamps and forests cover over 137,000 km2 distributed latitudinally among subtropical zones, 7% of which are in Brazil, with a greater density in the country’s northernmost region. Considering that the community of Myxomycetes recorded for this environment is hardly known, three areas located in the state of Maranhão were investigated. Two field trips were conducted, one at the beginning of the rainy season and another during the dry season. In each area, two plots (125 m2 equidistant 100 m apart from each other were surveyed. In these areas, standing dead tree trunks and dead branches still attached to the mother plant that were above the tideline, were examined. On these same occasions, samples of the aerial litter and from the cortex of living trees (Rhizophora were collected for the preparation of moist chambers cultures. Twenty-one specimens were obtained from field and moist chambers, belonging to 11 species, distributed in nine genera and five families. Seven species are new records from Maranhão. There was a predominance of r-strategist (73% over K-strategist (27% species. Cribraria violacea, Comatricha tenerrima, Echinostelium minutum, and Fuligo septica are new worldwide records from mangrove environments, and Oligonema flavidum is reported for the first time from Brazil.

  4. Modeling continuous cultures of microalgae colimited by nitrogen and phosphorus.

    Science.gov (United States)

    Bougaran, Gaël; Bernard, Olivier; Sciandra, Antoine

    2010-08-07

    It is well documented that the combination of low nitrogen and phosphorus resources can lead to situations where colimitation of phytoplankton growth arises, yet the underlying mechanisms are not fully understood. Here, we propose a Droop-based model built on the idea that colimitation by nitrogen and phosphorus arises from the uptake of nitrogen. Indeed, since N-porters are active systems, they require energy that could be related to the phosphorus status of the cell. Therefore, we assumed that N uptake is enhanced by the P quota. Our model also accounts for the biological observations that uptake of a nutrient can be down-regulated by its own internal quota, and succeeds in describing the strong contrast for the non-limiting quotas under N-limited and P-limited conditions that was observed on continuous cultures with Selenastrum minutum and with Isochrysis affinis galbana. Our analysis suggests that, regarding the colimitation concept, N and P would be better considered as biochemically dependent rather than biochemically independent nutrients. Copyright 2010 Elsevier Ltd. All rights reserved.

  5. Biotransformation of mercury in pH-stat cultures of eukaryotic freshwater algae.

    Science.gov (United States)

    Kelly, David J A; Budd, Kenneth; Lefebvre, Daniel D

    2007-01-01

    Eukaryotic algae were studied to determine their ability to biotransform Hg(II) under aerated and pH controlled conditions. All algae converted Hg(II) into beta-HgS and Hg(0) to varying degrees. When Hg(II) was administered as HgCl(2) to the algae, biotransformation by species of Chlorophyceae (Selenastrum minutum and Chlorella fusca var. fusca) was initiated with beta-HgS synthesis (K (1/2) of hours) and concomitant Hg degrees evolution occurred in the first hour. Hg degrees synthesis was impeded by the formation of beta-HgS and this inhibition was released in C. fusca var. fusca when cellular thiols were oxidized by the addition of dimethylfumarate (DMF). The diatom, Navicula pelliculosa (Bacillariophyceae), converted a substantially greater proportion of the applied Hg(II) into Hg(0), whereas the thermophilic alga, Galdieria sulphuraria (Cyanidiophyceae), rapidly biotransformed as much as 90% of applied Hg(II) into beta-HgS (K (1/2) approximately 20 min). This thermophile was also able to generate Hg(0) even after all exogenously applied HgCl(2) had been biotransformed. The results suggest that beta-HgS may be the major dietary mercurial for grazers of contaminated eukaryotic algae.

  6. The Influence of Edaphic and Orographic Factors on Algal Diversity in Biological Soil Crusts on Bare Spots in the Polar and Subpolar Urals

    Science.gov (United States)

    Patova, E. N.; Novakovskaya, I. V.; Deneva, S. V.

    2018-03-01

    The influence of edaphic and orographic factors on the formation of algal diversity in biological soil crusts was studied in mountain tundras of the Polar and Subpolar Urals. Bare spots developed in the soils on different parent materials and overgrown to different extents were investigated. Overall, 221 algal species from six divisions were identified. Among them, eighty-eight taxa were new for the region studied. The Stigonema minutum, S. ocellatum, Nostoc commune, Gloeocapsopsis magma, Scytonema hofmannii, Leptolyngbya foveolarum, Pseudococcomyxa simplex, Sporotetras polydermatica species and species of the Cylindrocystis, Elliptochloris, Fischerella, Leptosira, Leptolyngbya, Myrmecia, Mesotaenium, Phormidium, Schizothrix genera were permanent components of biological soil crusts. The basis of the algal cenoses in soil crusts was composed of cosmopolitan cyanoprokaryotes, multicellular green algae with thickened covers and abundant mucus. The share of nitrogen fixers was high. The physicochemical properties of primary soils forming under the crusts of spots are described. The more important factors affecting the species composition of algae in the crusts are the elevation gradient, temperature, soil moisture, and the contents of Ca, Mg, mobile phosphorus, and total nitrogen.

  7. Plankton community and the relationship with the environment in saline lakes of Onon-Torey plain, Northeastern Mongolia.

    Science.gov (United States)

    Afonina, Ekaterina Yu; Tashlykova, Natalya A

    2018-02-01

    The plankton community of sixteen saline lakes located on Onon-Torey plain (Northeastern Mongolia) during the filling phase and the raising of the water level was investigated in July 2011. Thirty-five taxa of phytoplankton and thirty-one species of zooplankton were found. For phytoplankton, blue-green algae ( Merismopedia elegans , Anabaenopsis elenkinii , Arthrospora fusiformis , Spirulina major , Lyngbya sp., Oscillatoria sp.) and green algae ( Monoraphidium minutum , Tetrastrum komarekii , Ankyra ocellata , Oocystis sp.) were dominant. For zooplankton, Filinia longiseta, Brachionus plicatilis , B. variabilis , Hexarthra mira (Rotifera), Daphnia magna , Moina brachiata , M. mongolica (Cladocera), Arctodiaptomus bacillifer , Mixodiaptomus incrassatus , Metadiaptomus asiaticus (Copepoda) dominated. Mineralization, active hydrogen ratio, dissolved oxygen and water temperature were the main factors influencing the diversity, structure and distribution of plankton organisms in the steppe lakes during low water level. The RDA analysis for phytoplankton and zooplankton from different lakes was carried out for selected two groups which included lakes and a subset related species. The first group is of oligohaline and mesohaline lakes in which mostly green algae, rotifers and copepods inhabit. The second group is of mesohaline and polyhaline lakes with mainly blue-green algae , some crustaceans and rotifers inhabiting. High abundance and biomass of Spirulina major , Oscillatoria sp. and Brachionus variabilis were observed in lakes with high mineralization, pH and temperature.

  8. Use of rotifers for the maintenance of monoalgal mass cultures of Spirulina

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, S.A.; Richmond, A.

    1987-01-01

    Zooplankton was successfully used for the biological control of unicellular algal contaminants in Spirulina mass cultures even under conditions adverse to the growth of Spirulina (maximal winter daily temperature of approximately 10 degrees C and very low bicarbonate concentration). Brachionus plicatilis (Rotifera) was the most successful species of zooplankton used. The interrelationships between Spirulina, green unicellular contaminant, and B. plicatilis were studied under various conditions. Two species of unicellular contaminant were used; Monoraphidium minutum was isolated from local cultures and Chlorella vulgaris, obtained from contaminated Spirulina cultures in Israel. The rotifer B. plicatilis successfully controlled the population size of both contaminants whether they were introduced in a single addition or as a daily dose. The biological control of the unicellular contaminants allows Spirulina to be cultured in a medium low in bicarbonate, thereby reducing the cost of the medium and increasing the quantity of CO2 that may be freely absorbed from the atmosphere at the optimal pH for Spirulina cultivation. (Refs. 9).

  9. Plankton community and the relationship with the environment in saline lakes of Onon-Torey plain, Northeastern Mongolia

    Directory of Open Access Journals (Sweden)

    Ekaterina Yu. Afonina

    2018-02-01

    Full Text Available The plankton community of sixteen saline lakes located on Onon-Torey plain (Northeastern Mongolia during the filling phase and the raising of the water level was investigated in July 2011. Thirty-five taxa of phytoplankton and thirty-one species of zooplankton were found. For phytoplankton, blue-green algae (Merismopedia elegans, Anabaenopsis elenkinii, Arthrospora fusiformis, Spirulina major, Lyngbya sp., Oscillatoria sp. and green algae (Monoraphidium minutum, Tetrastrum komarekii, Ankyra ocellata, Oocystis sp. were dominant. For zooplankton, Filinia longiseta, Brachionus plicatilis, B. variabilis, Hexarthra mira (Rotifera, Daphnia magna, Moina brachiata, M. mongolica (Cladocera, Arctodiaptomus bacillifer, Mixodiaptomus incrassatus, Metadiaptomus asiaticus (Copepoda dominated. Mineralization, active hydrogen ratio, dissolved oxygen and water temperature were the main factors influencing the diversity, structure and distribution of plankton organisms in the steppe lakes during low water level. The RDA analysis for phytoplankton and zooplankton from different lakes was carried out for selected two groups which included lakes and a subset related species. The first group is of oligohaline and mesohaline lakes in which mostly green algae, rotifers and copepods inhabit. The second group is of mesohaline and polyhaline lakes with mainly blue-green algae, some crustaceans and rotifers inhabiting. High abundance and biomass of Spirulina major, Oscillatoria sp. and Brachionus variabilis were observed in lakes with high mineralization, pH and temperature.

  10. Toxicity of chlorpyrifos on some marine cyanobacteria species

    International Nuclear Information System (INIS)

    Shoaib, N.; Siddiqui, A.; Khalid, H.

    2012-01-01

    Pakistan is an agricultural country and a wide variety of pesticides are used on its cropland. Pesticides pose serious threats to the natural ecosystem. In the present study cyanobacteria (blue green algae) were used to assess the ecotoxicological effect of chlorpyrifos (organophosphate pesticide). Cyanobacteria are the base of the food web providing food resource to consumers in higher trophic level. Cyanobacteria were isolated and purified from water samples collected from Manora channel. Fast growing cultures of cyanobacteria were used to assess the toxicity of test pesticide . The Light and Dark method was used to determine the primary production of the organisms. The acute toxicity of chlorpyrifos was determined by calculating IC/sub 50/ of the test organisms. The IC/sub 50/ was found to be 0.074, 0.013, 0.08 and 0.3 ppm for Synechocystis aquatilis, Komvophoron minutum, Gloeocapsa crepidinum and Gloeocapsa sanguinea when exposed to chlorpyrifos pesticide . Laboratory experiments with cyanobacteria have demonstrated that organophosphate pesticides are potent inhibitors of photosynthesis. (author)

  11. Genomes of coral dinoflagellate symbionts highlight evolutionary adaptations conducive to a symbiotic lifestyle

    KAUST Repository

    Aranda, Manuel

    2016-12-22

    Despite half a century of research, the biology of dinoflagellates remains enigmatic: they defy many functional and genetic traits attributed to typical eukaryotic cells. Genomic approaches to study dinoflagellates are often stymied due to their large, multi-gigabase genomes. Members of the genus Symbiodinium are photosynthetic endosymbionts of stony corals that provide the foundation of coral reef ecosystems. Their smaller genome sizes provide an opportunity to interrogate evolution and functionality of dinoflagellate genomes and endosymbiosis. We sequenced the genome of the ancestral Symbiodinium microadriaticum and compared it to the genomes of the more derived Symbiodinium minutum and Symbiodinium kawagutii and eukaryote model systems as well as transcriptomes from other dinoflagellates. Comparative analyses of genome and transcriptome protein sets show that all dinoflagellates, not only Symbiodinium, possess significantly more transmembrane transporters involved in the exchange of amino acids, lipids, and glycerol than other eukaryotes. Importantly, we find that only Symbiodinium harbor an extensive transporter repertoire associated with the provisioning of carbon and nitrogen. Analyses of these transporters show species-specific expansions, which provides a genomic basis to explain differential compatibilities to an array of hosts and environments, and highlights the putative importance of gene duplications as an evolutionary mechanism in dinoflagellates and Symbiodinium.

  12. Genomes of coral dinoflagellate symbionts highlight evolutionary adaptations conducive to a symbiotic lifestyle

    KAUST Repository

    Aranda, Manuel; Li, Yangyang; Liew, Yi Jin; Baumgarten, Sebastian; Simakov, O.; Wilson, M. C.; Piel, J.; Ashoor, Haitham; Bougouffa, Salim; Bajic, Vladimir B.; Ryu, Tae Woo; Ravasi, Timothy; Bayer, Till; Micklem, G.; Kim, H.; Bhak, J.; LaJeunesse, T. C.; Voolstra, Christian R.

    2016-01-01

    Despite half a century of research, the biology of dinoflagellates remains enigmatic: they defy many functional and genetic traits attributed to typical eukaryotic cells. Genomic approaches to study dinoflagellates are often stymied due to their large, multi-gigabase genomes. Members of the genus Symbiodinium are photosynthetic endosymbionts of stony corals that provide the foundation of coral reef ecosystems. Their smaller genome sizes provide an opportunity to interrogate evolution and functionality of dinoflagellate genomes and endosymbiosis. We sequenced the genome of the ancestral Symbiodinium microadriaticum and compared it to the genomes of the more derived Symbiodinium minutum and Symbiodinium kawagutii and eukaryote model systems as well as transcriptomes from other dinoflagellates. Comparative analyses of genome and transcriptome protein sets show that all dinoflagellates, not only Symbiodinium, possess significantly more transmembrane transporters involved in the exchange of amino acids, lipids, and glycerol than other eukaryotes. Importantly, we find that only Symbiodinium harbor an extensive transporter repertoire associated with the provisioning of carbon and nitrogen. Analyses of these transporters show species-specific expansions, which provides a genomic basis to explain differential compatibilities to an array of hosts and environments, and highlights the putative importance of gene duplications as an evolutionary mechanism in dinoflagellates and Symbiodinium.

  13. Seasonal effects of cadmium accumulation in periphytic diatom communities of freshwater biofilms

    Energy Technology Data Exchange (ETDEWEB)

    Thi Thuy Duong [Institute of Environmental Technology, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi (Viet Nam); Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: duongthuy0712@yahoo.com; Morin, Soizic [Cemagref, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex (France); Herlory, Olivier [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France); Feurtet-Mazel, Agnes [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: a.feurtet-mazel@epoc.u-bordeaux1.fr; Coste, Michel [Cemagref, UR REBX, 50 avenue de Verdun, F-33612 Cestas cedex (France); Boudou, Alain [Universite de Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)

    2008-10-20

    The relationships between diatom species and cadmium (Cd) accumulated in biofilms of the Riou-Mort River (SW, France) were studied in July 2004 and March 2005. Biofilms were sampled from artificial substrates immersed along a metallic pollution gradient during 20 days. Dynamics of diatom communities and cadmium accumulation were followed by collecting samples after 4, 7, 14 and 20 days of biofilm colonization. Cd accumulation in biofilms during experiment was significantly higher in Cd polluted station (Joanis) than in reference station (Firmi) for both seasons. Periphytic diatom composition varied between sites and seasons. At Firmi station, seasonal dynamics of diatom communities were stable with the dominance of Cyclotella meneghiniana and Melosira varians in July and Surirellabrebissonnii and Navicula gregaria in March. At Joanis station, diatom communities mainly responded to high levels of metal by a high proportion of small, adnate species. Positive correlations between Eolimna minima, Nitzschia palea, Encyonema minutum, Surirella angusta, and Gomphonema parvulum and cadmium accumulation were observed, indicating that these species are tolerant to high levels of cadmium. On the other hand, negative correlations of C. meneghiniana, N. gregaria, Navicula lanceolata, M. varians and Nitzschia dissipata with cadmium qualify them as sensitive diatom species. Periphytic diatom composition through the presence of specific species highlight metal tolerant indicator diatom groups which will be meaningful for biomonitoring pollution in natural aquatic systems.

  14. Body size and symbiotic status influence gonad development in Aiptasia pallida anemones.

    Science.gov (United States)

    Carlisle, Judith F; Murphy, Grant K; Roark, Alison M

    2017-01-01

    Pale anemones ( Aiptasia pallida ) coexist with dinoflagellates (primarily Symbiodinium minutum ) in a mutualistic relationship. The purpose of this study was to investigate the role of these symbionts in gonad development of anemone hosts. Symbiotic and aposymbiotic anemones were subjected to light cycles that induced gametogenesis. These anemones were then sampled weekly for nine weeks, and gonad development was analyzed histologically. Anemone size was measured as mean body column diameter, and oocytes or sperm follicles were counted for each anemone. Generalized linear models were used to evaluate the influence of body size and symbiotic status on whether gonads were present and on the number of oocytes or sperm follicles produced. Body size predicted whether gonads were present, with larger anemones being more likely than smaller anemones to develop gonads. Both body size and symbiotic status predicted gonad size, such that larger and symbiotic anemones produced more oocytes and sperm follicles than smaller and aposymbiotic anemones. Overall, only 22 % of aposymbiotic females produced oocytes, whereas 63 % of symbiotic females produced oocytes. Similarly, 6 % of aposymbiotic males produced sperm follicles, whereas 60 % of symbiotic males produced sperm follicles. Thus, while gonads were present in 62 % of symbiotic anemones, they were present in only 11 % of aposymbiotic anemones. These results indicate that dinoflagellate symbionts influence gonad development and thus sexual maturation in both female and male Aiptasia pallida anemones. This finding substantiates and expands our current understanding of the importance of symbionts in the development and physiology of cnidarian hosts.

  15. Studies on the phytoplankton of the deep subalpine Lake Iseo

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    Rosario MOSELLO

    2003-08-01

    Full Text Available This paper reports the results of investigations carried out on the chemical characteristics and phytoplankton community of Lake Iseo. Samplings were performed on a monthly basis from 1998 to 2000. At least three main algal groups dominated the community throughout the study period. The large Bacillariophyceae were dominant mainly during late winter and early spring (Aulacoseira spp., Melosira varians, Asterionella formosa, with few species able to maintain occasional positive growth also during mid summer and/or autumn (Fragilaria crotonensis and Diatoma elongatum. The thermal stability of the water column and silica depletion were the main factors responsible for the decline of the large spring diatoms. The subsequent growth of Mougeotia sp. (Conjugatophyceae was favoured by its lower sinking rate and resistance to increasing grazing pressure by the dominant copepods (Copidodiaptomus steueri and cladocerans (Daphnia hyalina × galeata. Among the cyanobacteria, the greater development of Planktothrix rubescens in the autumn months, with conditions of vertical homogenisation and decreasing Zeu/Zmix ratios, was favoured by its ability to survive at low light irradiances. The temporal replacement of these three groups constitutes the main sequence of the annual phytoplankton succession in Lake Iseo. A large development of other algal groups was recorded only in one or two of the three study years (e.g. Dinophyceae and Chlorococcales. The changes observed in the annual phytoplankton development are discussed in the light of differences in the spring fertilisation of the waters, caused by differences in the depth of the layer involved in the late winter and spring vertical mixing.

  16. IMPACT OF JUTE RETTING ON PHYTOPLANKTON DIVERSITY AND AQUATIC HEALTH: BIOMONITORING IN A TROPICAL OXBOW LAKE

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    Dipankar Ghosh

    2015-11-01

    Full Text Available Phytoplankton acts as a primary producer and biological filter of aquatic ecosystem. Jute retting during monsoon is a common anthropological activity in the rural Bengal. Quantitative seasonal bio-monitoring of phytoplankton community composition with relative abundance and its diversity indices was carried out in this study from April 2013 to March 2014 to assess water quality and the impact of jute retting on phytoplankton diversity of a tropical fresh water oxbow lake in Nadia district of India. We recorded a total of 34 genera of 5 distinct classes, Chlorophyceae (15, Bacillariophyceae (13, Cyanophyceae (4, Dinophyceae (1 and Euglenophyceae (1. Members of Chlorophyceae dominated throughout the year. Unlike Cyanophyceae, Bacillariophyceae was found to be significantly increased during monsoon when compared to the rest of the year. Average phytoplankton density was highest in post-monsoon (8760/L followed by monsoon (4680/L and pre-monsoon (3650/L. Owing to the dominance of class Chlorophyceae and Bacillariophyceae we found this lake to be oligotrophic to mesotrophic. Indices values of genera richness, Shannon-Wiener, evenness and Simpson’s diversity reached their lowest 14, 1.61, 0.61 and 0.68 in monsoon and highest 23, 2.42, 0.77 and 0.86 in post monsoon respectively. The lowest diversity values during monsoon clearly suggested that the selected lake has highest anthropogenic pollution due to jute retting which impacted significantly on phytoplankton diversity. Therefore, the lake is not conducive for fish growth especially during monsoon and we opine that there is a need to regulate jute retting process, intensity and its density in the lake during the monsoon to ensure enhanced biodiversity for sustainable management and conservation of aquatic environment of this Oxbow lake.

  17. Phytoplankton abundance in relation to the quality of the coastal water – Arabian Gulf, Saudi Arabia

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    Mostafa Abdel Mohsen El Gammal

    2017-12-01

    Full Text Available Phytoplankton abundance in relation to some physicochemical characters of the costal water of Arabian Gulf (Saudi Arabia was studied for one year. The sampling program included 15 locations in Dammam, Saihat, Al-Qatif, Al-Awamia and Safwa. Water samples were analyzed monthly for these parameters; temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, ammonia, carbon dioxide, total chloride, reactive orthophosphate and total phosphorus and alkalinity, also phytoplankton communities were identified and Chlorophyll a was estimated. The results showed that, the high phytoplankton density attaining the maximum (190.3 × 104/m3 during May and June, and the minimum (10.4 × 104/m3 during November and December. Forty Five species belonging to 5 phytoplankton groups were recorded. Bacillariophyceae was the first dominant group forming 48% of the total phytoplankton communities (23 species. The dominant species of Bacillariophyceae were Pleurosigma strigosum, Pleurosigma elongatum, Lyrella clavata, Rhizosolenia shrubsolei, Cylindrotheca closterium, Nitzschia panduriform, Nitzschia longissimia, Amphora sp and Stephanopyxis. Dinophyceae was the second dominant group and formed 31% of the total phytoplankton communities (10 species; the dominant species were Ceratium fusus, Heterosigma sp, Ceratium furca, Prorocentrum triestium, Protoperidinium sp, Gyrodinium spirale, Noctiluca scintillans and Scrippsiella trochoidea. Cyanophyceae formed 13% (5 species where Nostoc sp, Oscillatoria and Merismopedia sp were the dominant species. Chlorophyceae had 8% (6 species; Scendesmus sp., Chlorella sp., Chlamydomonas sp., Dunaliella salina and Nannochloropsis sp were the dominant species. The Euglinophyceae was rare only one species (Euglina sp. The relationship was positive between the phytoplankton, chlorophyll a and carbon dioxide while negative amongst dissolved oxygen and total nitrogen. This research indicated that the relation between water quality

  18. Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

    Science.gov (United States)

    Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

    2017-09-01

    Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

  19. Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile

    Science.gov (United States)

    Parris, Darren J.; Ganesh, Sangita; Edgcomb, Virginia P.; DeLong, Edward F.; Stewart, Frank J.

    2014-01-01

    Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2–1.6 μm, >1.6 μm) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 μm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2–1.6 μm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40–70% of sequences). Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18 and 40% of all sequences, respectively). The OMZ 0.2–1.6 μm fraction was dominated (11–99%) by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 μm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveal variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion. PMID:25389417

  20. Latitudinal variation of phytoplankton communities in the western Arctic Ocean

    Science.gov (United States)

    Min Joo, Hyoung; Lee, Sang H.; Won Jung, Seung; Dahms, Hans-Uwe; Hwan Lee, Jin

    2012-12-01

    Recent studies have shown that photosynthetic eukaryotes are an active and often dominant component of Arctic phytoplankton assemblages. In order to explore this notion at a large scale, samples were collected to investigate the community structure and biovolume of phytoplankton along a transect in the western Arctic Ocean. The transect included 37 stations at the surface and subsurface chlorophyll a maximum (SCM) depths in the Bering Sea, Chukchi Sea, and Canadian Basin from July 19 to September 5, 2008. Phytoplankton (>2 μm) were identified and counted. A cluster analysis of abundance and biovolume data revealed different assemblages over the shelf, slope, and basin regions. Phytoplankton communities were composed of 71 taxa representing Dinophyceae, Cryptophyceae, Bacillariophyceae, Chrysophyceae, Dictyochophyceae, Prasinophyceae, and Prymnesiophyceae. The most abundant species were of pico- to nano-size at the surface and SCM depths at most stations. Nano- and pico-sized phytoplankton appeared to be dominant in the Bering Sea, whereas diatoms and nano-sized plankton provided the majority of taxon diversity in the Bering Strait and in the Chukchi Sea. From the western Bering Sea to the Bering Strait, the abundance, biovolume, and species diversity of phytoplankton provided a marked latitudinal gradient towards the central Arctic. Although pico- and nano-sized phytoplankton contributed most to cell abundance, their chlorophyll a contents and biovolumes were less than those of the larger micro-sized taxa. Micro-sized phytoplankton contributed most to the biovolume in the largely ice-free waters of the western Arctic Ocean during summer 2008.

  1. Phytoplankton community and limnochemistry of Piburger See (Tyrol, Austria 28 years after lake restoration

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    Hansjörg THIES

    2002-02-01

    Full Text Available Phytoplankton community and limnochemistry of Piburger See, a small soft-water, meromictic lake situated at 913 m a.s.l. in a crystalline area of the Central Eastern Alps of Tyrol (Austria, were investigated 28 years after the beginning of lake restoration. Although long-term data of the lake show a declining trend in total phosphorus concentrations and phytoplankton biovolume, the response of Piburger See to the restoration measures carried out in 1970 was delayed by about 20 years. At present the lake is approaching its former oligotrophic level. The most evident difference between the past and present phytoplankton species composition of Piburger See is the actual absence of the Cyanophycean Oscillatoria limosa C. A. Agardh, which markedly increased during the first two decades after the lake restoration (1970-1987. The phytoplankton biovolume recorded in 1998 was lower than in the 1970s and 1980s, while seasonal patterns were similar to those recorded before and later on in the lake restoration. The lowest annual phytoplankton biovolume in 1998 occurred in early winter, while the absolute maximum was observed in metalimnetic water layers in late spring. In 1998 the intra-annual patterns of phytoplankton biovolume and chlorophyll-a compare well. Phytoplankton succession started in early 1998 under ice with coccal green algae followed by flagellated Chrysophyceae during spring. The mid-summer phytoplankton community was dominated by centric Bacillariophyceae, which were later replaced by coccal Cyanophyceae. During autumn, Dinophyceae and Chrysophyceae prevailed. Epilimnetic dominance of centric diatoms during mid summer appears to be a new feature, which in 1998 was related to a strong depletion of dissolved silica and nitrate. Long-term water chemistry and phytoplankton data were checked against local weather data in order to explain the delay in the re-oligotrophication process of Piburger See. However, no clear relationship could be

  2. Feeding by phototrophic red-tide dinoflagellates on the ubiquitous marine diatom Skeletonema costatum.

    Science.gov (United States)

    Du Yoo, Yeong; Jeong, Hae Jin; Kim, Mi Seon; Kang, Nam Seon; Song, Jae Yoon; Shin, Woongghi; Kim, Kwang Young; Lee, Kitack

    2009-01-01

    We investigated feeding by phototrophic red-tide dinoflagellates on the ubiquitous diatom Skeletonema costatum to explore whether dinoflagellates are able to feed on S. costatum, inside the protoplasm of target dinoflagellate cells observed under compound microscope, confocal microscope, epifluorescence microscope, and transmission electron microscope (TEM) after adding living and fluorescently labeled S. costatum (FLSc). To explore effects of dinoflagellate predator size on ingestion rates of S. costatum, we measured ingestion rates of seven dinoflagellates at a single prey concentration. In addition, we measured ingestion rates of the common phototrophic dinoflagellates Prorocentrum micans and Gonyaulax polygramma on S. costatum as a function of prey concentration. We calculated grazing coefficients by combining field data on abundances of P. micans and G. polygramma on co-occurring S. costatum with laboratory data on ingestion rates obtained in the present study. All phototrophic dinoflagellate predators tested (i.e. Akashiwo sanguinea, Amphidinium carterae, Alexandrium catenella, Alexandrium tamarense, Cochlodinium polykrikoides, G. polygramma, Gymnodinium catenatum, Gymnodinium impudicum, Heterocapsa rotundata, Heterocapsa triquetra, Lingulodinium polyedrum, Prorocentrum donghaiense, P. micans, Prorocentrum minimum, Prorocentrum triestinum, and Scrippsiella trochoidea) were able to ingest S. costatum. When mean prey concentrations were 170-260 ng C/ml (i.e. 6,500-10,000 cells/ml), the ingestion rates of G. polygramma, H. rotundata, H. triquetra, L. polyedrum, P. donghaiense, P. micans, and P. triestinum on S. costatum (0.007-0.081 ng C/dinoflagellate/d [0.2-3.0 cells/dinoflagellate/d]) were positively correlated with predator size. With increasing mean prey concentration of ca 1-3,440 ng C/ml (40-132,200 cells/ml), the ingestion rates of P. micans and G. polygramma on S. costatum continuously increased. At the given prey concentrations, the maximum ingestion

  3. Effect of Siderophore on Iron Availability in a Diatom and a Dinoflagellate Species: Contrasting Response in Associated Bacteria

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    Nicolas Sanchez

    2018-04-01

    Full Text Available Organic ligands play a key role controlling trace metal bioavailability in the world's oceans, yet the species-specific requirements determining whether certain iron forms can be metabolized largely remain unclear. Siderophores are considered relevant within the pool of ligands keeping iron soluble. We used desferrioxamine B (DFB to study the siderophore's effect on cultures of Skeletonema costatum and Alexandrium catenella. The experimental approach used semi-continuous additions of iron(II and DFB over time, reaching final concentrations of 1 and 10 nM Fe and 10–10,000 nM DFB. The negative effect of DFB on growth in S. costatum was evident and sharp until day 9 for treatments above 500 nM. Delayed growth occurred at 10,000 nM, reaching ~80% of cell density in Controls under both iron conditions. Alexandrium catenella exhibited a less severe negative effect of DFB on growth, only significant at 10,000 nM, while growth was enhanced at lowest DFB. Total bacterial abundance in diatom and dinoflagellate cultures presented inverse trends. While negatively correlated to DFB in diatom cultures, bacteria showed highest abundances in high DFB treatments in dinoflagellate cultures. Delayed growth exhibited in S. costatum at the highest DFB, indicates that favorable changes for Fe uptake occurred over time, suggesting the involvement of other mechanisms facilitating the diatom cell membrane reduction. Overall, unaffected growth in A. catenella suggests that this species can use FeDFB and therefore has the capacity to access strongly complexed Fe sources. Contrasting responses in the bacterial community associated with each species highlight the complexity of these interactions, while suggesting that for A. catenella it may represent an advantage for acquiring Fe. These results demonstrated the capacity for different uptake strategies among phytoplankton species of different functional groups and underlines the necessity to broaden the study of iron

  4. Results of a Saxitoxin Proficiency Test Including Characterization of Reference Material and Stability Studies

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    Kirsi Harju

    2015-11-01

    Full Text Available A saxitoxin (STX proficiency test (PT was organized as part of the Establishment of Quality Assurance for the Detection of Biological Toxins of Potential Bioterrorism Risk (EQuATox project. The aim of this PT was to provide an evaluation of existing methods and the European laboratories’ capabilities for the analysis of STX and some of its analogues in real samples. Homogenized mussel material and algal cell materials containing paralytic shellfish poisoning (PSP toxins were produced as reference sample matrices. The reference material was characterized using various analytical methods. Acidified algal extract samples at two concentration levels were prepared from a bulk culture of PSP toxins producing dinoflagellate Alexandrium ostenfeldii. The homogeneity and stability of the prepared PT samples were studied and found to be fit-for-purpose. Thereafter, eight STX PT samples were sent to ten participating laboratories from eight countries. The PT offered the participating laboratories the possibility to assess their performance regarding the qualitative and quantitative detection of PSP toxins. Various techniques such as official Association of Official Analytical Chemists (AOAC methods, immunoassays, and liquid chromatography-mass spectrometry were used for sample analyses.

  5. Compositional Similarities and Differences between Transparent Exopolymer Particles (TEP) from two Marine Bacteria and two Marine Algae: Significance to Surface Biofouling

    KAUST Repository

    Li, Sheng

    2015-06-12

    Transparent-exopolymer-particles (TEP) have been recently identified as a significant contributor to surface biofouling, such as on reverse osmosis (RO) membranes. TEP research has mainly focused on algal TEP/TEP precursors while limited investigations have been conducted on those released by bacteria. In this study, TEP/TEP precursors derived from both algae and bacteria were isolated and then characterized to investigate their similarities and/or differences using various advanced analytical techniques, thus providing a better understanding of their potential effect on biofouling. Bacterial TEP/TEP precursors were isolated from two species of marine bacteria (Pseudidiomarina homiensis and Pseudoalteromonas atlantica) while algal TEP/TEP precursors were isolated from two marine algae species (Alexandrium tamarense and Chaetoceros affinis). Results indicated that both isolated bacterial and algal TEP/TEP precursors were associated with protein-like materials, and most TEP precursors were high-molecular-weight biopolymers. Furthermore all investigated algal and bacterial TEP/TEP precursors showed a lectin-like property, which can enable them to act as a chemical conditioning layer and to agglutinate bacteria. This property may enhance surface biofouling. However, both proton nuclear magnetic resonance (NMR) spectra and the nitrogen/carbon (N/C) ratios suggested that the algal TEP/TEP precursors contained much less protein content than the bacterial TEP/TEP precursors. This difference may influence their initial deposition and further development of surface biofouling.

  6. A Stable-Isotope Mass Spectrometry-Based Metabolic Footprinting Approach to Analyze Exudates from Phytoplankton

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    Mark R. Viant

    2013-10-01

    Full Text Available Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction and analysed by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We used the harmful algal bloom forming dinoflagellate Alexandrium tamarense to prove the method. An algorithm was developed to automatically pinpoint just those metabolites with highly 13C-enriched isotope signatures, allowing us to discover algal exudates from the complex seawater background. The stable-isotope pattern (SIP of the detected metabolites then allowed for more accurate assignment to an empirical formula, a critical first step in their identification. This automated workflow provides an effective way to explore the chemical nature of the solutes exuded from phytoplankton cells and will facilitate the discovery of novel dissolved bioactive compounds.

  7. Combined Effects of Ocean Acidification and Light or Nitrogen Availabilities on 13C Fractionation in Marine Dinoflagellates.

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    Mirja Hoins

    Full Text Available Along with increasing oceanic CO2 concentrations, enhanced stratification constrains phytoplankton to shallower upper mixed layers with altered light regimes and nutrient concentrations. Here, we investigate the effects of elevated pCO2 in combination with light or nitrogen-limitation on 13C fractionation (εp in four dinoflagellate species. We cultured Gonyaulax spinifera and Protoceratium reticulatum in dilute batches under low-light ('LL' and high-light ('HL' conditions, and grew Alexandrium fundyense and Scrippsiella trochoidea in nitrogen-limited continuous cultures ('LN' and nitrogen-replete batches ('HN'. The observed CO2-dependency of εp remained unaffected by the availability of light for both G. spinifera and P. reticulatum, though at HL εp was consistently lower by about 2.7‰ over the tested CO2 range for P. reticulatum. This may reflect increased uptake of (13C-enriched bicarbonate fueled by increased ATP production under HL conditions. The observed CO2-dependency of εp disappeared under LN conditions in both A. fundyense and S. trochoidea. The generally higher εp under LN may be associated with lower organic carbon production rates and/or higher ATP:NADPH ratios. CO2-dependent εp under non-limiting conditions has been observed in several dinoflagellate species, showing potential for a new CO2-proxy. Our results however demonstrate that light- and nitrogen-limitation also affect εp, thereby illustrating the need to carefully consider prevailing environmental conditions.

  8. MF/UF rejection and fouling potential of algal organic matter from bloom-forming marine and freshwater algae

    KAUST Repository

    Villacorte, Loreen O.

    2015-07-01

    Pretreatment with microfiltration (MF) or ultrafiltration (UF) membranes has been proposed for seawater reverse osmosis (SWRO) plants to address operational issues associated with algal blooms. Here, we investigated the MF/UF rejection and fouling potential of algal organic matter (AOM) released by common species of bloom-forming marine (Alexandrium tamarense and Chaetoceros affinis) and freshwater (Microcystis sp.) algae. Batch culture monitoring of the three algal species illustrated varying growth pattern, cell concentration, AOM released and membrane fouling potential. The high membrane fouling potential of the cultures can be directly associated (R2>0.85) with AOM such as transparent exopolymer particle (TEP) while no apparent relationship with algal cell concentration was observed. The AOM comprised mainly biopolymers (e.g., polysaccharides and proteins) and low molecular weight organic compounds (e.g., humic-like substances). The former were largely rejected by MF/UF membranes while the latter were poorly rejected. MF (0.4μm and 0.1μm pore size) rejected 14%-56% of biopolymers while conventional UF (100kDa) and tight UF (10kDa) rejected up to 83% and 97%, respectively. The retention of AOM resulted in a rapid increase in trans-membrane pressure (δP) over time, characterised by pore blocking followed by cake filtration with enhanced compression as illustrated by an exponential progression of δP. © 2015 Elsevier B.V.

  9. Particle size fractionation of paralytic shellfish toxins (PSTs): seasonal distribution and bacterial production in the St Lawrence estuary, Canada.

    Science.gov (United States)

    Michaud, S; Levasseur, M; Doucette, G; Cantin, G

    2002-10-01

    We determined the seasonal distribution of paralytic shellfish toxins (PSTs) and PST producing bacteria in > 15, 5-15, and 0.22-5 microm size fractions in the St Lawrence. We also measured PSTs in a local population of Mytilus edulis. PST concentrations were determined in each size fraction and in laboratory incubations of sub-samples by high performance liquid chromatography (HPLC), including the rigorous elimination of suspected toxin 'imposter' peaks. Mussel toxin levels were determined by mouse bioassay and HPLC. PSTs were detected in all size fractions during the summer sampling season, with 47% of the water column toxin levels associated with particles smaller than Alexandrium tamarense ( 15 microm size fraction, we estimated that as much as 92% of PSTs could be associated with particles other than A. tamarense. Our results stress the importance of taking into account the potential presence of PSTs in size fractions other than that containing the known algal producer when attempting to model shellfish intoxication, especially during years of low cell abundance. Finally, our HPLC results confirmed the presence of bacteria capable of autonomous PST production in the St Lawrence as well as demonstrating their regular presence and apparent diversity in the plankton. Copyright 2002 Elsevier Science Ltd.

  10. Metabolites of saxitoxin analogues in bivalves contaminated by Gymnodinium catenatum.

    Science.gov (United States)

    Vale, Paulo

    2010-01-01

    Bivalve metabolites of saxitoxin analogues, not present in microalgae, were recently described as an important toxin fraction in mussels contaminated by Alexandrium tamarense. These possess very low fluorescence, and require mass spectrometry detection. HILIC-MS was implemented to look for these metabolites in bivalves contaminated during Gymnodinium catenatum blooms at the Portuguese coast. The presence of M1 was tentatively identified in several bivalves, ranging from estuarine (Mytilus galloprovinciallis, Cerastoderma edule and Ruditapes decussatus) to oceanic habitat (Donax trunculus and Ensis spp.). It was hypothesized that M1 could contribute to an important fraction of the profile of STX analogues. M1 was more abundant in estuarine bivalves that retain longer PSP toxins, in the following order: mussels>cockles>clams. These data highlight that the study by fluorimetry alone of the carbamoyl, N-sulfocarbamoyl, and decarbamoyl families is manifestly insufficient to fully understand toxin dynamics in bivalves feeding on G. catenatum without a proper study of hydroxybenzoate and hydroxylated M-toxins.

  11. Application of a laser fluorometer for discriminating phytoplankton species

    Science.gov (United States)

    Chen, Peng; Pan, Delu; Mao, Zhihua

    2015-04-01

    A portable laser-induced fluorescence system for discriminating phytoplankton species has been developed. It consists of a high pulsed repetition frequency (10-kHz) microchip laser at 405 nm, a reflective fluorescent probe and a broadband micro spectrometer. The measured fluorescent spectra were overlapped by various fluorescent components, and were then decomposed by a bi-Gaussian mixture model. A spectral shape description index was designed to characterize fluorescent spectral shapes for descriminating the phytoplankton species cultured in our laboratory. Using clustering analysis, the samples of eight phytoplankton species belonging to two divisions of Bacillariophyta and Dinophyta were divided into six categories: 1) Chaetoceros debilis, Thalassiosira rotula; 2) Prorocentrum donghaiense, Prorocentrum dentatum; 3) Gymnodinium simplex; 4) Alexandrium tamarense; 5) Karenia mikimotoi; and 6) Akashiwo sanguinea. The phytoplankton species belonging to Bacillariophyta were well separated from those belonging to Dinophyta. In addition, the phytoplankton species belonging to Dinophyta were successfully distinguished from each other at genus level. The portable system is expected to be used both in vivo and in the field.

  12. Marine Biotoxins: Occurrence, Toxicity, and Detection Methods

    Science.gov (United States)

    Asakawa, M.

    2017-04-01

    This review summarizes the role of marine organisms as vectors of marine biotoxins, and discusses the need for surveillance to protect public health and ensure the quality of seafood. I Paralytic shellfish poison (PSP) and PSP-bearing organisms-PSP is produced by toxic dinoflagellates species belonging to the genera Alexandrium, Gymnodinium, and Pyrodinium. Traditionally, PSP monitoring programs have only considered filter-feeding molluscs that concentrate these toxic algae, however, increasing attention is now being paid to higher-order predators that carry PSP, such as carnivorous gastropods and crustaceans. II. Tetrodotoxin (TTX) and TTX-bearing organisms - TTX is the most common natural marine toxin that causes food poisonings in Japan, and poses a serious public health risk. TTX was long believed to be present only in pufferfish. However, TTX was detected in the eggs of California newt Taricha torosa in 1964, and since then it has been detected in a wide variety of species belonging to several different phyla. In this study, the main toxic components in the highly toxic ribbon worm Cephalothrix simula and the greater blue-ringed octopus Hapalochlaena lunulata from Japan were purified and analysed.

  13. Effect of the Algaecide Palmitoleic Acid on the Immune Function of the Bay Scallop Argopecten irradians

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    Cheng Chi

    2016-05-01

    Full Text Available Palmitoleic acid (PA, an algicidal compound, is used against the toxin producing dinofagelate Alexandrium tamarense, however, its impact on the edible bay scallop (Argopecten irradians is still unclear. Therefore, we investigated the impacts of effective algicidal concentrations (20, 40, and 80 mg/L of PA on immune responses in A. irradians. Various immune parameters including acid phosphatase (ACP activity, superoxide dismutase (SOD, lysozyme, phagocytic activity, total protein, malondialdehyde (MDA level, and reactive oxygen species (ROS production and the expression of immune-related genes (PrxV, CLT-6, MT, and BD were measured at 3, 6, 12, 24, and 48 h post-exposure (hpe to PA. Lysozyme activity was lower in scallops at 12–48 hpe to 80 mg/L. SOD, ACP activity, ROS production, the total protein, and MDA level was higher at 12 to 48 hpe with different concentrations of PA. Phagocytic activity increased at 6–12 hpe to 40–80 mg/L of PA, but decreased at 24–48 hpe. The expressions of genes PrxV, CLT-6, MT and BD down-regulated at 3 hpe were observed, while differential expressions from 6–48 hpe with different concentrations of PA. The present study demonstrated that immersing A. irradians in PA at effective concentrations could result in differential effects on non-specific immune responses and expressions of immune-related genes.

  14. Assessment of harmful algal species using different approaches: the case study of the Sardinian coasts

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    C.T. Satta

    2014-04-01

    Full Text Available The presence and distribution of harmful algal species were investigated along the coasts of Sardinia in the summer of 2012. Fourteen potentially noxious taxa were identified at 74 beaches. The majority of the recovered taxa were potentially toxic and/or high biomass producers. Alexandrium taylorii, Gymnodinium instriatum, and Ostreopsis cf. ovata were the most frequent and abundant taxa, although Barrufeta bravensis reached the highest density (4.4 × 106 cells L−1. Barrufeta bravensis, A. taylorii, and G. instriatum were responsible for intense water discoloration at two of the beaches sampled. Polymerase chain reaction (PCR analyses supported the identification of several taxa and decisively identified B. bravensis. PCR assays increased the information available on the species distributions. The locations studied were heterogeneous in their prevailing environmental conditions and their morphodynamic profiles. Statistical analyses indicated that the distributions of harmful algal species correlated with gravel and medium-fine sand substrata. These data provide substantial knowledge on the distributions of harmful algal species on beaches, which have been poorly studied on a global scale. The apparent relationship between noxious species and grain size suggests that vegetative cells may be recruited from cyst beds in beach sediments.

  15. Potential Threats Posed by New or Emerging Marine Biotoxins in UK Waters and Examination of Detection Methodologies Used for Their Control: Cyclic Imines

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    Keith Davidson

    2015-11-01

    Full Text Available Cyclic imines (CIs are a group of phytoplankton produced toxins related to shellfish food products, some of which are already present in UK and European waters. Their risk to shellfish consumers is poorly understood, as while no human intoxication has been definitively related to this group, their fast acting toxicity following intraperitoneal injection in mice has led to concern over their human health implications. A request was therefore made by UK food safety authorities to examine these toxins more closely to aid possible management strategies. Of the CI producers only the spirolide producer Alexandrium ostenfeldii is known to exist in UK waters at present but trends in climate change may lead to increased risk from other organisms/CI toxins currently present elsewhere in Europe and in similar environments worldwide. This paper reviews evidence concerning the prevalence of CIs and CI-producing phytoplankton, together with testing methodologies. Chemical, biological and biomolecular methods are reviewed, including recommendations for further work to enable effective testing. Although the focus here is on the UK, from a strategic standpoint many of the topics discussed will also be of interest in other parts of the world since new and emerging marine biotoxins are of global concern.

  16. Neurotoxic Alkaloids: Saxitoxin and Its Analogs

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    Troco K. Mihali

    2010-07-01

    Full Text Available Saxitoxin (STX and its 57 analogs are a broad group of natural neurotoxic alkaloids, commonly known as the paralytic shellfish toxins (PSTs. PSTs are the causative agents of paralytic shellfish poisoning (PSP and are mostly associated with marine dinoflagellates (eukaryotes and freshwater cyanobacteria (prokaryotes, which form extensive blooms around the world. PST producing dinoflagellates belong to the genera Alexandrium, Gymnodinium and Pyrodinium whilst production has been identified in several cyanobacterial genera including Anabaena, Cylindrospermopsis, Aphanizomenon Planktothrix and Lyngbya. STX and its analogs can be structurally classified into several classes such as non-sulfated, mono-sulfated, di-sulfated, decarbamoylated and the recently discovered hydrophobic analogs—each with varying levels of toxicity. Biotransformation of the PSTs into other PST analogs has been identified within marine invertebrates, humans and bacteria. An improved understanding of PST transformation into less toxic analogs and degradation, both chemically or enzymatically, will be important for the development of methods for the detoxification of contaminated water supplies and of shellfish destined for consumption. Some PSTs also have demonstrated pharmaceutical potential as a long-term anesthetic in the treatment of anal fissures and for chronic tension-type headache. The recent elucidation of the saxitoxin biosynthetic gene cluster in cyanobacteria and the identification of new PST analogs will present opportunities to further explore the pharmaceutical potential of these intriguing alkaloids.

  17. Performance of a sand filter in removal of micro-algae from seawater in aquaculture production systems.

    Science.gov (United States)

    Sabiri, N E; Castaing, J B; Massé, A; Jaouen, P

    2012-01-01

    In this study, a sand filter was used to remove micro-algae from seawater feeding aquaculture ponds. A lab-scale sand filter was used to filter 30,000 cells/mL of Heterocapsa triquetra suspension, a non-toxic micro-alga that has morphological and dimensional (15-20 microm) similarities with Alexandrium sp., one of the smallest toxic micro-algae in seawater. Removal efficiency and capture mechanisms for a fixed superficial velocity (3.5 m/h) were evaluated in relation to size distribution and mean diameter of the sand. Various sands (average diameter ranging between 200 microm and 600 microm) were characterized and used as porous media. The structural parameters of the fixed beds were evaluated for each medium using experimental measurements of pressure drop as a function of superficial velocity over a range of Reynolds numbers covering Darcy's regime and the inertial regime. For a filtration cycle of six hours, the best efficiency (E = 90%) was obtained with the following sand characteristics: sieved sand with a range of grain diameter of 100 and 300 microm and a mean grain diameter equal to 256 microm. Results obtained show the influence of the size distribution of sand on the quality of retention of the micro-algae studied.

  18. Validation of a an analysis method of Marine Bio toxins Type Saxitoxin based on test coupled receptor (RBA) with Radiochemical Detection with liquid scintillation

    International Nuclear Information System (INIS)

    Selmi, Zied

    2009-01-01

    The saxitoxin s are bio toxins belonging to the family of toxins of the type PSP. They are paralysing toxins secreted by marine micro-organisms, phytoplankton, called Alexandrium. They constitute a risk for the human health in the event of their consumption in contaminated food. The acceptable maximum limit of these bio toxins in molluscs and shellfish is fixed to 800 μg /kg of meat of molluscs or shellfish. It proves, thus, that it is essential to develop and validate analytical methods for the level monitoring of contamination of the marine resources by these species in order to found a program of their monitoring and to guarantee an acceptable level of the food safety of the products available on the national and international markets. The present work allowed the validation of the quantification method of these toxins which is based on the use of the Receptor Binding Assay (RBA) with liquid scintillation nuclear technique detection using tritium as radiotracer and while proceeding by the different statistical tests of validation (Standard Nf XP T 90-210). The field of linearity ranged from 0 to 20 n M and the limit of detection was found to be 1 n M. The validation of this method will allow the reinforcement of the analytical means of analysis of marine bi toxins type SXT and to set up, in the near future, a monitoring and surveillance routine program for these bio toxins at the national, regional and African scales. (Author)

  19. Prominent Human Health Impacts from Several Marine Microbes: History, Ecology, and Public Health Implications

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    P. K. Bienfang

    2011-01-01

    Full Text Available This paper overviews several examples of important public health impacts by marine microbes and directs readers to the extensive literature germane to these maladies. These examples include three types of dinoflagellates (Gambierdiscus spp., Karenia brevis, and Alexandrium fundyense, BMAA-producing cyanobacteria, and infectious microbes. The dinoflagellates are responsible for ciguatera fish poisoning, neurotoxic shellfish poisoning, and paralytic shellfish poisoning, respectively, that have plagued coastal populations over time. Research interest on the potential for marine cyanobacteria to contribute BMAA into human food supplies has been derived by BMAA's discovery in cycad seeds and subsequent implication as the putative cause of amyotrophic lateral sclerosis/parkinsonism dementia complex among the Chamorro people of Guam. Recent UPLC/MS analyses indicate that recent reports that BMAA is prolifically distributed among marine cyanobacteria at high concentrations may be due to analyte misidentification in the analytical protocols being applied for BMAA. Common infectious microbes (including enterovirus, norovirus, Salmonella, Campylobacter, Shigella, Staphylococcus aureus, Cryptosporidium, and Giardia cause gastrointestinal and skin-related illness. These microbes can be introduced from external human and animal sources, or they can be indigenous to the marine environment.

  20. Combined Effects of Ocean Acidification and Light or Nitrogen Availabilities on 13C Fractionation in Marine Dinoflagellates.

    Science.gov (United States)

    Hoins, Mirja; Eberlein, Tim; Groβmann, Christian H; Brandenburg, Karen; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy; Van de Waal, Dedmer B

    2016-01-01

    Along with increasing oceanic CO2 concentrations, enhanced stratification constrains phytoplankton to shallower upper mixed layers with altered light regimes and nutrient concentrations. Here, we investigate the effects of elevated pCO2 in combination with light or nitrogen-limitation on 13C fractionation (εp) in four dinoflagellate species. We cultured Gonyaulax spinifera and Protoceratium reticulatum in dilute batches under low-light ('LL') and high-light ('HL') conditions, and grew Alexandrium fundyense and Scrippsiella trochoidea in nitrogen-limited continuous cultures ('LN') and nitrogen-replete batches ('HN'). The observed CO2-dependency of εp remained unaffected by the availability of light for both G. spinifera and P. reticulatum, though at HL εp was consistently lower by about 2.7‰ over the tested CO2 range for P. reticulatum. This may reflect increased uptake of (13C-enriched) bicarbonate fueled by increased ATP production under HL conditions. The observed CO2-dependency of εp disappeared under LN conditions in both A. fundyense and S. trochoidea. The generally higher εp under LN may be associated with lower organic carbon production rates and/or higher ATP:NADPH ratios. CO2-dependent εp under non-limiting conditions has been observed in several dinoflagellate species, showing potential for a new CO2-proxy. Our results however demonstrate that light- and nitrogen-limitation also affect εp, thereby illustrating the need to carefully consider prevailing environmental conditions.

  1. A single-step method for rapid extraction of total lipids from green microalgae.

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    Martin Axelsson

    Full Text Available Microalgae produce a wide range of lipid compounds of potential commercial interest. Total lipid extraction performed by conventional extraction methods, relying on the chloroform-methanol solvent system are too laborious and time consuming for screening large numbers of samples. In this study, three previous extraction methods devised by Folch et al. (1957, Bligh and Dyer (1959 and Selstam and Öquist (1985 were compared and a faster single-step procedure was developed for extraction of total lipids from green microalgae. In the single-step procedure, 8 ml of a 2∶1 chloroform-methanol (v/v mixture was added to fresh or frozen microalgal paste or pulverized dry algal biomass contained in a glass centrifuge tube. The biomass was manually suspended by vigorously shaking the tube for a few seconds and 2 ml of a 0.73% NaCl water solution was added. Phase separation was facilitated by 2 min of centrifugation at 350 g and the lower phase was recovered for analysis. An uncharacterized microalgal polyculture and the green microalgae Scenedesmus dimorphus, Selenastrum minutum, and Chlorella protothecoides were subjected to the different extraction methods and various techniques of biomass homogenization. The less labour intensive single-step procedure presented here allowed simultaneous recovery of total lipid extracts from multiple samples of green microalgae with quantitative yields and fatty acid profiles comparable to those of the previous methods. While the single-step procedure is highly correlated in lipid extractability (r² = 0.985 to the previous method of Folch et al. (1957, it allowed at least five times higher sample throughput.

  2. Partitioning of Respiration in an Animal-Algal Symbiosis: Implications for Different Aerobic Capacity Between Symbiodinium spp.

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    Thomas David Hawkins

    2016-04-01

    Full Text Available Cnidarian-dinoflagellate symbioses are ecologically important and the subject of much investigation. However, our understanding of critical aspects of symbiosis physiology, such as the partitioning of total respiration between the host and symbiont, remains incomplete. Specifically, we know little about how the relationship between host and symbiont respiration varies between different holobionts (host-symbiont combinations. We applied molecular and biochemical techniques to investigate aerobic respiratory capacity in naturally symbiotic Exaiptasia pallida sea anemones, alongside animals infected with either homologous ITS2-type A4 Symbiodinium or a heterologous isolate of Symbiodinium minutum (ITS2-type B1. In naturally symbiotic anemones, host, symbiont, and total holobiont mitochondrial citrate synthase (CS enzyme activity, but not host mitochondrial copy number, were reliable predictors of holobiont respiration. There was a positive association between symbiont density and host CS specific activity (mg protein-1, and a negative correlation between host- and symbiont CS specific activities. Notably, partitioning of total CS activity between host and symbiont in this natural E. pallida population was significantly different to the host/symbiont biomass ratio. In re-infected anemones, we found significant between-holobiont differences in the CS specific activity of the algal symbionts. Furthermore, the relationship between the partitioning of total CS activity and the host/symbiont biomass ratio differed between holobionts. These data have broad implications for our understanding of cnidarian-algal symbiosis. Specifically, the long-held assumption of equivalency between symbiont/host biomass and respiration ratios can result in significant overestimation of symbiont respiration and potentially erroneous conclusions regarding the percentage of carbon translocated to the host. The interspecific variability in symbiont aerobic capacity provides

  3. A snapshot of a coral "holobiont": a transcriptome assembly of the scleractinian coral, porites, captures a wide variety of genes from both the host and symbiotic zooxanthellae.

    Science.gov (United States)

    Shinzato, Chuya; Inoue, Mayuri; Kusakabe, Makoto

    2014-01-01

    Massive scleractinian corals of the genus Porites are important reef builders in the Indo-Pacific, and they are more resistant to thermal stress than other stony corals, such as the genus Acropora. Because coral health and survival largely depend on the interaction between a coral host and its symbionts, it is important to understand the molecular interactions of an entire "coral holobiont". We simultaneously sequenced transcriptomes of Porites australiensis and its symbionts using the Illumina Hiseq2000 platform. We obtained 14.3 Gbp of sequencing data and assembled it into 74,997 contigs (average: 1,263 bp, N50 size: 2,037 bp). We successfully distinguished contigs originating from the host (Porites) and the symbiont (Symbiodinium) by aligning nucleotide sequences with the decoded Acropora digitifera and Symbiodinium minutum genomes. In contrast to previous coral transcriptome studies, at least 35% of the sequences were found to have originated from the symbionts, indicating that it is possible to analyze both host and symbiont transcriptomes simultaneously. Conserved protein domain and KEGG analyses showed that the dataset contains broad gene repertoires of both Porites and Symbiodinium. Effective utilization of sequence reads revealed that the polymorphism rate in P. australiensis is 1.0% and identified the major symbiotic Symbiodinium as Type C15. Analyses of amino acid biosynthetic pathways suggested that this Porites holobiont is probably able to synthesize most of the common amino acids and that Symbiodinium is potentially able to provide essential amino acids to its host. We believe this to be the first molecular evidence of complementarity in amino acid metabolism between coral hosts and their symbionts. We successfully assembled genes originating from both the host coral and the symbiotic Symbiodinium to create a snapshot of the coral holobiont transcriptome. This dataset will facilitate a deeper understanding of molecular mechanisms of coral symbioses

  4. Mercury analysis of acid- and alkaline-reduced biological samples: identification of meta-cinnabar as the major biotransformed compound in algae.

    Science.gov (United States)

    Kelly, David; Budd, Kenneth; Lefebvre, Daniel D

    2006-01-01

    The biotransformation of Hg(II) in pH-controlled and aerated algal cultures was investigated. Previous researchers have observed losses in Hg detection in vitro with the addition of cysteine under acid reduction conditions in the presence of SnCl2. They proposed that this was the effect of Hg-thiol complexing. The present study found that cysteine-Hg, protein and nonprotein thiol chelates, and nucleoside chelates of Hg were all fully detectable under acid reduction conditions without previous digestion. Furthermore, organic (R-Hg) mercury compounds could not be detected under either the acid or alkaline reduction conditions, and only beta-HgS was detected under alkaline and not under acid SnCl2 reduction conditions. The blue-green alga Limnothrix planctonica biotransformed the bulk of Hg(II) applied as HgCl2 into a form with the analytical properties of beta-HgS. Similar results were obtained for the eukaryotic alga Selenastrum minutum. No evidence for the synthesis of organomercurials such as CH3Hg+ was obtained from analysis of either airstream or biomass samples under the aerobic conditions of the study. An analytical procedure that involved both acid and alkaline reduction was developed. It provides the first selective method for the determination of beta-HgS in biological samples. Under aerobic conditions, Hg(II) is biotransformed mainly into beta-HgS (meta-cinnabar), and this occurs in both prokaryotic and eukaryotic algae. This has important implications with respect to identification of mercury species and cycling in aquatic habitats.

  5. Mercury Analysis of Acid- and Alkaline-Reduced Biological Samples: Identification of meta-Cinnabar as the Major Biotransformed Compound in Algae†

    Science.gov (United States)

    Kelly, David; Budd, Kenneth; Lefebvre, Daniel D.

    2006-01-01

    The biotransformation of HgII in pH-controlled and aerated algal cultures was investigated. Previous researchers have observed losses in Hg detection in vitro with the addition of cysteine under acid reduction conditions in the presence of SnCl2. They proposed that this was the effect of Hg-thiol complexing. The present study found that cysteine-Hg, protein and nonprotein thiol chelates, and nucleoside chelates of Hg were all fully detectable under acid reduction conditions without previous digestion. Furthermore, organic (R-Hg) mercury compounds could not be detected under either the acid or alkaline reduction conditions, and only β-HgS was detected under alkaline and not under acid SnCl2 reduction conditions. The blue-green alga Limnothrix planctonica biotransformed the bulk of HgII applied as HgCl2 into a form with the analytical properties of β-HgS. Similar results were obtained for the eukaryotic alga Selenastrum minutum. No evidence for the synthesis of organomercurials such as CH3Hg+ was obtained from analysis of either airstream or biomass samples under the aerobic conditions of the study. An analytical procedure that involved both acid and alkaline reduction was developed. It provides the first selective method for the determination of β-HgS in biological samples. Under aerobic conditions, HgII is biotransformed mainly into β-HgS (meta-cinnabar), and this occurs in both prokaryotic and eukaryotic algae. This has important implications with respect to identification of mercury species and cycling in aquatic habitats. PMID:16391065

  6. A snapshot of a coral "holobiont": a transcriptome assembly of the scleractinian coral, porites, captures a wide variety of genes from both the host and symbiotic zooxanthellae.

    Directory of Open Access Journals (Sweden)

    Chuya Shinzato

    Full Text Available Massive scleractinian corals of the genus Porites are important reef builders in the Indo-Pacific, and they are more resistant to thermal stress than other stony corals, such as the genus Acropora. Because coral health and survival largely depend on the interaction between a coral host and its symbionts, it is important to understand the molecular interactions of an entire "coral holobiont". We simultaneously sequenced transcriptomes of Porites australiensis and its symbionts using the Illumina Hiseq2000 platform. We obtained 14.3 Gbp of sequencing data and assembled it into 74,997 contigs (average: 1,263 bp, N50 size: 2,037 bp. We successfully distinguished contigs originating from the host (Porites and the symbiont (Symbiodinium by aligning nucleotide sequences with the decoded Acropora digitifera and Symbiodinium minutum genomes. In contrast to previous coral transcriptome studies, at least 35% of the sequences were found to have originated from the symbionts, indicating that it is possible to analyze both host and symbiont transcriptomes simultaneously. Conserved protein domain and KEGG analyses showed that the dataset contains broad gene repertoires of both Porites and Symbiodinium. Effective utilization of sequence reads revealed that the polymorphism rate in P. australiensis is 1.0% and identified the major symbiotic Symbiodinium as Type C15. Analyses of amino acid biosynthetic pathways suggested that this Porites holobiont is probably able to synthesize most of the common amino acids and that Symbiodinium is potentially able to provide essential amino acids to its host. We believe this to be the first molecular evidence of complementarity in amino acid metabolism between coral hosts and their symbionts. We successfully assembled genes originating from both the host coral and the symbiotic Symbiodinium to create a snapshot of the coral holobiont transcriptome. This dataset will facilitate a deeper understanding of molecular mechanisms of

  7. Contrasting physiological plasticity in response to environmental stress within different cnidarians and their respective symbionts

    Science.gov (United States)

    Hoadley, Kenneth D.; Pettay, Daniel. T.; Dodge, Danielle; Warner, Mark E.

    2016-06-01

    Given concerns surrounding coral bleaching and ocean acidification, there is renewed interest in characterizing the physiological differences across the multiple host-algal symbiont combinations commonly found on coral reefs. Elevated temperature and CO2 were used to compare physiological responses within the scleractinian corals Montipora hirsuta ( Symbiodinium C15) and Pocillopora damicornis ( Symbiodinium D1), as well as the corallimorph (a non-calcifying anthozoan closely related to scleractinians) Discosoma nummiforme ( Symbiodinium C3). Several physiological proxies were affected more by temperature than CO2, including photochemistry, algal number and cellular chlorophyll a. Marked differences in symbiont number, chlorophyll and volume contributed to distinctive patterns of chlorophyll absorption among these animals. In contrast, carbon fixation either did not change or increased under elevated temperature. Also, the rate of photosynthetically fixed carbon translocated to each host did not change, and the percent of carbon translocated to the host increased in the corallimorph. Comparing all data revealed a significant negative correlation between photosynthetic rate and symbiont density that corroborates previous hypotheses about carbon limitation in these symbioses. The ratio of symbiont-normalized photosynthetic rate relative to the rate of symbiont-normalized carbon translocation (P:T) was compared in these organisms as well as the anemone, Exaiptasia pallida hosting Symbiodinium minutum, and revealed a P:T close to unity ( D. nummiforme) to a range of 2.0-4.5, with the lowest carbon translocation in the sea anemone. Major differences in the thermal responses across these organisms provide further evidence of a range of acclimation potential and physiological plasticity that highlights the need for continued study of these symbioses across a larger group of host taxa.

  8. Comunidade fitoplanctônica de um pesqueiro na cidade de São Paulo

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    Mayla Matsuzaki

    2004-10-01

    Full Text Available OBJETIVO: A avaliação da qualidade da água e da comunidade fitoplanctônica em ambientes destinados à recreação permite estabelecer formas de manejo desses sistemas, evitando possíveis problemas à saúde humana. Assim, realizou-se estudo com objetivo de analisar a variação sazonal do fitoplâncton de um sistema lacustre natural, e sua relação com a qualidade da água. MÉTODOS: O lago estudado faz parte de um pesqueiro localizado na zona sul da cidade de São Paulo. Foram realizadas quatro coletas no período de um ano, em três pontos de amostragem. As amostras foram analisadas quanto à composição florística e às variáveis físicas e químicas da água. RESULTADOS: A análise qualitativa do fitoplâncton revelou o total de 91 táxons distribuídos em oito classes: Chlorophyceae (52%, Cyanophyceae (16%, Euglenophyceae (12%, Zygnemaphyceae (10%, Bacillariophyceae (5%, Xantophyceae (3%, Dinophyceae (1% e Chrysophyceae (1%. Alguns dos parâmetros físicos e químicos parecem ter influenciado o comportamento do fitoplâncton; a classe Chlorophyceae foi a mais favorecida pelas condições ambientais. Dentre as espécies de cianofíceas identificadas, destacaram-se Microcystis paniformis, Cylindrospermopsis raciborskii e espécies de Anabaena, que apresentaram maior importância do ponto de vista sanitário devido à produção de toxinas. CONCLUSÕES: Algumas variáveis físicas e químicas da água interferiram na estrutura da comunidade fitoplanctônica. A presença de Microcystis paniformis, Cylindrospermopsis raciborskii e espécies de Anabaena indicam o potencial tóxico e os possíveis problemas que podem ocorrer à saúde pública, caso esse ambiente não seja continuamente monitorado. Estudos adicionais são recomendados, com a finalidade de se evitar efeitos deletérios ao ambiente e à saúde da população.

  9. Phytoplankton variability in relation to some environmental factors in the eastern coast of Suez Gulf, Egypt.

    Science.gov (United States)

    Nassar, Mohamed Z; El-Din, Nihal G Shams; Gharib, Samiha M

    2015-10-01

    Water samples were seasonally collected from 12 stations of the eastern coast of Suez Gulf during autumn of 2012 and winter, spring, and summer of 2013 in order to investigate phytoplankton community structure in relation to some physicochemical parameters. The study area harbored a diversified phytoplankton community (138 species), belonging to 67 genera. Four algal groups were represented and classified as Bacillariophyceae (90 species), Dinophyceae (28 species), Cyanophyceae (16 species), and Chlorophyceae (4 species). The results indicated a relative high occurrence of some species namely.; Pleurotaenium trabecula of green algae; Chaetoceros lorenzianus, Proboscia alata var. gracillima, Pseudosolenia calcar-avis, and Pseudo-nitzschia pungens of diatoms; Trichodesmium erythraeum and Pseudoanabaena limnetica of cyanophytes. Most of other algal species were fairly distributed at the selected stations of the study area. The total abundance of phytoplankton was relatively low (average of 2989 unit/L) in the eastern coast of Suez Gulf, as compared its western coast and the northern part of the Red Sea. The diversity of phytoplankton species was relatively high (2.35-3.82 nats) with an annual average of 3.22 nats in the present study. The results concluded that most of eastern coast of Suez Gulf is still healthy, relatively unpolluted, and oligotrophic area, which is clearly achieved by the low values of dissolved phosphate (0.025-0.3 μM), nitrate (0.18-1.26 μM), and dissolved ammonium (0.81-5.36 μM). Even if the occurrence of potentially harmful algae species was low, the study area should be monitored continuously. The dissolved oxygen ranged between 1.77 and 8.41 mg/L and pH values between 7.6 and 8.41. The multiple regression analysis showed that the dissolved nitrate and pH values were the most effective factors that controlled the seasonal fluctuations of phytoplankton along the eastern coast of Suez Gulf during 2012-2013.

  10. Paralytic Shellfish Poisoning (PSP in Margarita Island, Venezuela

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    Amelia La Barbera-Sánchez

    2004-09-01

    Full Text Available A severe outbreak of Paralytic Shellfish Poisoning (PSP occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna exceeded the international safety limit of saxitoxin, 80 µg STX/100 g meat. PSP toxin values varied between 2 548 and 115 µg STX/100 g meat in Manzanillo, and between 1 422 and 86 µg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization. A high pressure liquid chromatographic (HPLC procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX, but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3 toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSPUn severo brote de intoxicación paralizante por moluscos (PSP en inglés ocurrió en Manzanillo y Guayacán en la costa noroeste de la Isla de Margarita, Venezuela entre agosto y octubre de 1991. Una proliferación de Prorocentrum gracile, Gymnodinium catenatum y Alexandrium tamarense causó el brote. Los niveles de PSP en mejillón (Perna perna superaron los niveles máximos permisibles de saxitoxina, 80 µg STX/100g carne. Los niveles de toxinas variaron entre 2 548 y 115

  11. First direct fluorescence polarization assay for the detection and quantification of spirolides in mussel samples

    Energy Technology Data Exchange (ETDEWEB)

    Otero, Paz; Alfonso, Amparo [Departamento de Farmacologia, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002 Lugo (Spain); Alfonso, Carmen [CIFGA Laboratorio, Plaza de Santo Domingo, 1, 27001 Lugo (Spain); Araoz, Romulo; Molgo, Jordi [CNRS, Institut de Neurobiologie Alfred Fessard - FRC2118, Laboratoire de Neurobiologie et Developpement UPR3294, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex (France); Vieytes, Mercedes R. [Departamento de Fisiologia, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo (Spain); Botana, Luis M., E-mail: luis.botana@usc.es [Departamento de Farmacologia, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002 Lugo (Spain)

    2011-09-09

    Highlights: {yields} A direct assay based in the binding of nAChR to spirolide toxins by FP is described. {yields} A direct relationship between FP and 13-desMeC in the range of 10-500 nM is obtained. {yields} FP is dependent on the 13, 19-didesMeC in a higher concentration range than 13-desMeC. {yields} FP assay is a sensitive method to detect and quantify 13-desMeC in mussel samples. - Abstract: In 2009, we achieve the first inhibition FP assay to detect imine cyclic toxins. In the present paper we propose a new FP assay for direct quantify spirolides. This new method has resulted in significant improvement of sensitivity, rapidity and accessibility. In the method design, nicotinic acetylcholine receptor from Torpedo marmorata membranes labelled with a derivative of fluorescein was used. Spirolides, 13-desmethyl spirolide C (13-desMeC) and 13,19-didesmethyl spirolide C (13,19-didesMeC) were extracted and purified from cultures of the Alexandrium ostenfeldii dinoflagellate. Data showed the decrease of FP when toxin concentration was increased. Thus, a relationship between the FP units and the spirolides amount present in a sample was obtained. This direct assay is a reproducible, simple and very sensitive method with a detection limit about 25 nM for 13-desMeC and 150 nM for 13,19-didesMeC. The procedure was used to measure spirolides in mussel samples using an extraction and clean up protocol suitable for the FP assay. Results obtained show that this method is able to quantify 13-desMeC in the range of 50-350 {mu}g kg{sup -1} meat. Other liposoluble toxins did not interfere with the assay, proving a specific method. Moreover, the matrix do not affect in the range of toxin concentrations that involving risk of spirolides intoxication.

  12. Determining the Advantages, Costs, and Trade-Offs of a Novel Sodium Channel Mutation in the Copepod Acartia hudsonica to Paralytic Shellfish Toxins (PST.

    Directory of Open Access Journals (Sweden)

    Michael Finiguerra

    Full Text Available The marine copepod Acartia hudsonica was shown to be adapted to dinoflagellate prey, Alexandrium fundyense, which produce paralytic shellfish toxins (PST. Adaptation to PSTs in other organisms is caused by a mutation in the sodium channel. Recently, a mutation in the sodium channel in A. hudsonica was found. In this study, we rigorously tested for advantages, costs, and trade-offs associated with the mutant isoform of A. hudsonica under toxic and non-toxic conditions. We combined fitness with wild-type: mutant isoform ratio measurements on the same individual copepod to test our hypotheses. All A. hudsonica copepods express both the wild-type and mutant sodium channel isoforms, but in different proportions; some individuals express predominantly mutant (PMI or wild-type isoforms (PWI, while most individuals express relatively equal amounts of each (EI. There was no consistent pattern of improved performance as a function of toxin dose for egg production rate (EPR, ingestion rate (I, and gross growth efficiency (GGE for individuals in the PMI group relative to individuals in the PWI expression group. Neither was there any evidence to indicate a fitness benefit to the mutant isoform at intermediate toxin doses. No clear advantage under toxic conditions was associated with the mutation. Using a mixed-diet approach, there was also no observed relationship between individual wild-type: mutant isoform ratios and among expression groups, on both toxic and non-toxic diets, for eggs produced over three days. Lastly, expression of the mutant isoform did not mitigate the negative effects of the toxin. That is, the reductions in EPR from a toxic to non-toxic diet for copepods were independent of expression groups. Overall, the results did not support our hypotheses; the mutant sodium channel isoform does not appear to be related to adaptation to PST in A. hudsonica. Other potential mechanisms responsible for the adaptation are discussed.

  13. Spatiotemporal patterns of paralytic shellfish toxins and their relationships with environmental variables in British Columbia, Canada from 2002 to 2012.

    Science.gov (United States)

    Finnis, Stephen; Krstic, Nikolas; McIntyre, Lorraine; Nelson, Trisalyn A; Henderson, Sarah B

    2017-07-01

    Harmful algal blooms produce paralytic shellfish toxins that accumulate in the tissues of filter feeding shellfish. Ingestion of these toxic shellfish can cause a serious and potentially fatal condition known as paralytic shellfish poisoning (PSP). The coast of British Columbia is routinely monitored for shellfish toxicity, and this study uses data from the monitoring program to identify spatiotemporal patterns in shellfish toxicity events and their relationships with environmental variables. The dinoflagellate genus Alexandrium produces the most potent paralytic shellfish toxin, saxitoxin (STX). Data on all STX measurements were obtained from 49 different shellfish monitoring sites along the coast of British Columbia for 2002-2012, and monthly toxicity events were identified. We performed hierarchical cluster analysis to group sites that had events in similar areas with similar timing. Machine learning techniques were used to model the complex relationships between toxicity events and environmental variables in each group. The Strait of Georgia and the west coast of Vancouver Island had unique toxicity regimes. Out of the seven environmental variables used, toxicity in each cluster could be described by multivariable models including monthly sea surface temperature, air temperature, sea surface salinity, freshwater discharge, upwelling, and photosynthetically active radiation. The sea surface salinity and freshwater discharge variables produced the strongest univariate models for both geographic areas. Applying these methods in coastal regions could allow for the prediction of shellfish toxicity events by environmental conditions. This has the potential to optimize biotoxin monitoring, improve public health surveillance, and engage the shellfish industry in helping to reduce the risk of PSP. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Molecular diversity patterns among various phytoplankton size-fractions in West Greenland in late summer

    Science.gov (United States)

    Elferink, Stephanie; Neuhaus, Stefan; Wohlrab, Sylke; Toebe, Kerstin; Voß, Daniela; Gottschling, Marc; Lundholm, Nina; Krock, Bernd; Koch, Boris P.; Zielinski, Oliver; Cembella, Allan; John, Uwe

    2017-03-01

    as Alexandrium fundyense and A. ostenfeldii) in the area points out the potential risk for this vulnerable ecosystem in a changing world.

  15. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate.

    Directory of Open Access Journals (Sweden)

    Cong Wang

    Full Text Available Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta. Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina regardless of DIP condition. Group V (Amphidinium carterae exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine

  16. Differential Growth Responses of Marine Phytoplankton to Herbicide Glyphosate

    Science.gov (United States)

    Wang, Cong; Lin, Xin; Li, Ling; Lin, Senjie

    2016-01-01

    Glyphosate is a globally popular herbicide to kill weeds and its wide applications may lead to accumulation in coastal oceans as a source of phosphorus (P) nutrient or growth inhibitor of phytoplankton. We studied the physiological effects of glyphosate on fourteen species representing five major coastal phytoplankton phyla (haptophyta, bacillariophyta, dinoflagellata, raphidophyta, and chlorophyta). Based on growth responses to different concentrations of glyphosate under contrasting dissolved inorganic phosphorus (DIP) conditions, we found that phytoplankton species could be classified into five groups. Group I (Emiliania huxleyi, Skeletonema costatum, Phaeodactylum tricornutum) could utilize glyphosate as sole P-source to support growth in axenic culture, but in the presence of DIP, they were inhibited by both 36-μM and 360-μM glyphosate. Group II (Karenia mikimotoi, Prorocentrum minimum, Dunaliella tertiolecta, Symbiodinium sp., Heterosigma akashiwo and Alexandrium catenella) could not utilize glyphosate as sole P-source to support growth, and in the presence of DIP growth was not affected by 36-μM but inhibited by 360-μM glyphosate. Glyphosate consistently enhanced growth of Group III (Isochrysis galbana) and inhibited Group IV (Thalassiosira weissflogii, Thalassiosira pseudonana and Chattonella marina) regardless of DIP condition. Group V (Amphidinium carterae) exhibited no measurable response to glyphosate regardless of DIP condition. This grouping is not congruent with the phylogenetic relationships of the phytoplankton species suggesting functional differentiation driven by environmental pressure. We conclude that glyphosate could be used as P-source by some species while is toxic to some other species and yet has no effects on others. The observed differential effects suggest that the continued use of glyphosate and increasing concentration of this herbicide in the coastal waters will likely exert significant impact on coastal marine phytoplankton

  17. First direct fluorescence polarization assay for the detection and quantification of spirolides in mussel samples

    International Nuclear Information System (INIS)

    Otero, Paz; Alfonso, Amparo; Alfonso, Carmen; Araoz, Romulo; Molgo, Jordi; Vieytes, Mercedes R.; Botana, Luis M.

    2011-01-01

    Highlights: → A direct assay based in the binding of nAChR to spirolide toxins by FP is described. → A direct relationship between FP and 13-desMeC in the range of 10-500 nM is obtained. → FP is dependent on the 13, 19-didesMeC in a higher concentration range than 13-desMeC. → FP assay is a sensitive method to detect and quantify 13-desMeC in mussel samples. - Abstract: In 2009, we achieve the first inhibition FP assay to detect imine cyclic toxins. In the present paper we propose a new FP assay for direct quantify spirolides. This new method has resulted in significant improvement of sensitivity, rapidity and accessibility. In the method design, nicotinic acetylcholine receptor from Torpedo marmorata membranes labelled with a derivative of fluorescein was used. Spirolides, 13-desmethyl spirolide C (13-desMeC) and 13,19-didesmethyl spirolide C (13,19-didesMeC) were extracted and purified from cultures of the Alexandrium ostenfeldii dinoflagellate. Data showed the decrease of FP when toxin concentration was increased. Thus, a relationship between the FP units and the spirolides amount present in a sample was obtained. This direct assay is a reproducible, simple and very sensitive method with a detection limit about 25 nM for 13-desMeC and 150 nM for 13,19-didesMeC. The procedure was used to measure spirolides in mussel samples using an extraction and clean up protocol suitable for the FP assay. Results obtained show that this method is able to quantify 13-desMeC in the range of 50-350 μg kg -1 meat. Other liposoluble toxins did not interfere with the assay, proving a specific method. Moreover, the matrix do not affect in the range of toxin concentrations that involving risk of spirolides intoxication.

  18. Harmful algal blooms and Vibrio spp. association in fishing and marine farming areas of mollusk bivalves in Sechura and Pisco bays, Peru

    Directory of Open Access Journals (Sweden)

    Rita Orozco

    2017-04-01

    Full Text Available Between February 2010 and May 2014, 22 surveys in Pisco and 16 in Sechura were conducted; both are major areas for shellfish production and mariculture in Peru. The incidence of Vibrio in seawater was monitored during algal blooms and in their absence. Environmental parameters such as temperature and nutrients were measured. In Sechura, Pseudo-nitzschia seriata and Protoperidinium depressum caused algal blooms and were dominant throughout the evaluation period. The temperatures in this area ranged from 21.8 to 25.3 °C. In Pisco, the harmful algal bloom-forming Akashiwo sanguinea, Messodinium rubrum, and Prorocentrum minimum and the dinoflagellate Cochlodinium polikrykoides were most prevalent. Harmful algal blooms occurred when temperatures were between 17.1 and 23.3 °C, with phosphates ranging 1.22 - 6.85 µM and nitrates 0.15 - 7.85 µM. In May 2012, the dinoflagellate Alexandrium peruvianum caused an algal bloom, with temperatures ranging 18.0 to 23.2 °C, phosphate values from 0.73 to 11.56 µM, and nitrates from 0.76 to 9.81 µM. Coliforms were low, < 2 - 23 MPN/100 ml, in both bays throughout the study period. Vibrio alginolyticus was the dominant Vibrio spp. predominated in both bays, while V. vulnificus and V. parahaemolyticus were detected in Pisco, where warmer sea temperatures are common and severe infections cases by seafood ingestion has been associated with a pathogen V. parahaemolyticus.

  19. Prevalence, Variability and Bioconcentration of Saxitoxin-Group in Different Marine Species Present in the Food Chain

    Science.gov (United States)

    Oyaneder Terrazas, Javiera; Contreras, Héctor R.; García, Carlos

    2017-01-01

    The saxitoxin-group (STX-group) corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium. Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that has affected ≈35% of the Southern Pacific coast territory, generating a high economic impact. The objective of this research was to study the toxicity of the STX-group in all aquatic organisms (bivalves, algae, echinoderms, crustaceans, tunicates, cephalopods, gastropods, and fish) present in areas with a variable presence of harmful algal blooms (HABs). Then, the toxic profiles of each species and dose of STX equivalents ingested by a 60 kg person from 400 g of shellfish were determined to establish the health risk assessment. The toxins with the highest prevalence detected were gonyautoxin-4/1 (GTX4/GTX1), gonyautoxin-3/2 (GTX3/GTX2), neosaxitoxin (neoSTX), decarbamoylsaxitoxin (dcSTX), and saxitoxin (STX), with average concentrations of 400, 2800, 280, 200, and 2000 µg kg−1 respectively, a species-specific variability, dependent on the evaluated tissue, which demonstrates the biotransformation of the analogues in the trophic transfer with a predominance of α-epimers in all toxic profiles. The identification in multiple vectors, as well as in unregulated species, suggests that a risk assessment and risk management update are required; also, chemical and specific analyses for the detection of all analogues associated with the STX-group need to be established. PMID:28604648

  20. Impact of several harmful algal bloom (HAB) causing species, on life history characteristics of rotifer Brachionus plicatilis Müller

    Science.gov (United States)

    Lin, Jianing; Yan, Tian; Zhang, Qingchun; Zhou, Mingjiang

    2016-07-01

    In recent years, harmful algal blooms (HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinoflagellate-dominated blooms. To examine the effects of different diatom and dinoflagellate HABs, the life history parameters of rotifers ( Brachionus plicatilis Müller) were measured after exposure to different concentrations of HAB species. The HAB species examined included a diatom ( Skeletonema costatum) and four dinoflagellates ( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium veneficum). Compared with the control treatment (CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinoflagellates at densities equivalent to those measured in the field resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production (CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span (CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate (CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., finite rate of increase (CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase (CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinoflagellates P. donghaiense, A. catenella, P. lima and K. veneficum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinoflagellates tested did show adverse effects. This suggests that dinoflagellate HABs may suppress microzooplankton, resulting in an increase in algal numbers.

  1. De novo assembly of a transcriptome for Calanus finmarchicus (Crustacea, Copepoda--the dominant zooplankter of the North Atlantic Ocean.

    Directory of Open Access Journals (Sweden)

    Petra H Lenz

    Full Text Available Assessing the impact of global warming on the food web of the North Atlantic will require difficult-to-obtain physiological data on a key copepod crustacean, Calanus finmarchicus. The de novo transcriptome presented here represents a new resource for acquiring such data. It was produced from multiplexed gene libraries using RNA collected from six developmental stages: embryo, early nauplius (NI-II, late nauplius (NV-VI, early copepodite (CI-II, late copepodite (CV and adult (CVI female. Over 400,000,000 paired-end reads (100 base-pairs long were sequenced on an Illumina instrument, and assembled into 206,041 contigs using Trinity software. Coverage was estimated to be at least 65%. A reference transcriptome comprising 96,090 unique components ("comps" was annotated using Blast2GO. 40% of the comps had significant blast hits. 11% of the comps were successfully annotated with gene ontology (GO terms. Expression of many comps was found to be near zero in one or more developmental stages suggesting that 35 to 48% of the transcriptome is "silent" at any given life stage. Transcripts involved in lipid biosynthesis pathways, critical for the C. finmarchicus life cycle, were identified and their expression pattern during development was examined. Relative expression of three transcripts suggests wax ester biosynthesis in late copepodites, but triacylglyceride biosynthesis in adult females. Two of these transcripts may be involved in the preparatory phase of diapause. A key environmental challenge for C. finmarchicus is the seasonal exposure to the dinoflagellate Alexandrium fundyense with high concentrations of saxitoxins, neurotoxins that block voltage-gated sodium channels. Multiple contigs encoding putative voltage-gated sodium channels were identified. They appeared to be the result of both alternate splicing and gene duplication. This is the first report of multiple NaV1 genes in a protostome. These data provide new insights into the transcriptome

  2. Phytoplankton blooms: an overlooked marine source of natural endocrine disrupting chemicals.

    Science.gov (United States)

    Gong, Yinhan; Wang, Xiaochong; Indran, Inthrani Raja; Zhang, Shi-Jun; Lv, Zhengbing; Li, Jun; Holmes, Michael; Tang, Ying Zhong; Yong, E L

    2014-09-01

    We had previously reported high androgenic and estrogenic activities in seawaters in confined clusters close to Singapore. Further investigations revealed a hitherto unsuspected link between estrogenic/androgenic activity and net phytoplankton count. The primary objective of this study was to investigate the cause of a correlation between net phytoplankton and endocrine activity, and corroborate this observation, and rule out other possible confounding factors. Our secondary objective was to study if these estrogenic secretions can impact human health. Five species of phytoplankton, Gymnodinium catenatum, Prorocentrum minimum, Alexandrium leei, Chattonella marina, and Fibrocapsa japonica, were isolated from Singapore waters and mass cultured and the cells and culture media screened for estrogenic and androgenic activity using human cell-based bioassays. The raphidophytes C. marina and F. japonica displayed significant estrogenic activity whilst the dinoflagellates G. catenatum and P. minimum displayed significant androgenic activity in both the cell extracts and the cell culture media extract. Our data shows that selected phytoplankton isolates are potent secretors of estrogenic and androgenic substances, which are potential endocrine disrupting chemicals (EDCs). As the harmful nature of EDCs is largely due to their bioaccumulation in the aquatic food chain our findings imply that the impact of these phytoplankton secretions needs to be investigated especially for seafoods, which are only a single trophic level away from phytoplankton. Alternatively, should these phytoplankton-origin EDCs not accumulate through marine food chains to significantly impact humans or marine mammals, our results indicate that functional assays could greatly over-estimate the risk from naturally occurring EDCs produced by marine phytoplankton. It remains to be determined if these EDCs affect zooplankton and other organisms that directly feed on marine phytoplankton, or if the secreted

  3. Prevalence, Variability and Bioconcentration of Saxitoxin-Group in Different Marine Species Present in the Food Chain.

    Science.gov (United States)

    Oyaneder Terrazas, Javiera; Contreras, Héctor R; García, Carlos

    2017-06-12

    The saxitoxin-group (STX-group) corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium , and Pyrodinium . Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that has affected ≈35% of the Southern Pacific coast territory, generating a high economic impact. The objective of this research was to study the toxicity of the STX-group in all aquatic organisms (bivalves, algae, echinoderms, crustaceans, tunicates, cephalopods, gastropods, and fish) present in areas with a variable presence of harmful algal blooms (HABs). Then, the toxic profiles of each species and dose of STX equivalents ingested by a 60 kg person from 400 g of shellfish were determined to establish the health risk assessment. The toxins with the highest prevalence detected were gonyautoxin-4/1 (GTX4/GTX1), gonyautoxin-3/2 (GTX3/GTX2), neosaxitoxin (neoSTX), decarbamoylsaxitoxin (dcSTX), and saxitoxin (STX), with average concentrations of 400, 2800, 280, 200, and 2000 µg kg -1 respectively, a species-specific variability, dependent on the evaluated tissue, which demonstrates the biotransformation of the analogues in the trophic transfer with a predominance of α-epimers in all toxic profiles. The identification in multiple vectors, as well as in unregulated species, suggests that a risk assessment and risk management update are required; also, chemical and specific analyses for the detection of all analogues associated with the STX-group need to be established.

  4. Prevalence, Variability and Bioconcentration of Saxitoxin-Group in Different Marine Species Present in the Food Chain

    Directory of Open Access Journals (Sweden)

    Javiera Oyaneder Terrazas

    2017-06-01

    Full Text Available The saxitoxin-group (STX-group corresponds to toxic metabolites produced by cyanobacteria and dinoflagellates of the genera Alexandrium, Gymnodinium, and Pyrodinium. Over the last decade, it has been possible to extrapolate the areas contaminated with the STX-group worldwide, including Chile, a phenomenon that has affected ≈35% of the Southern Pacific coast territory, generating a high economic impact. The objective of this research was to study the toxicity of the STX-group in all aquatic organisms (bivalves, algae, echinoderms, crustaceans, tunicates, cephalopods, gastropods, and fish present in areas with a variable presence of harmful algal blooms (HABs. Then, the toxic profiles of each species and dose of STX equivalents ingested by a 60 kg person from 400 g of shellfish were determined to establish the health risk assessment. The toxins with the highest prevalence detected were gonyautoxin-4/1 (GTX4/GTX1, gonyautoxin-3/2 (GTX3/GTX2, neosaxitoxin (neoSTX, decarbamoylsaxitoxin (dcSTX, and saxitoxin (STX, with average concentrations of 400, 2800, 280, 200, and 2000 µg kg−1 respectively, a species-specific variability, dependent on the evaluated tissue, which demonstrates the biotransformation of the analogues in the trophic transfer with a predominance of α-epimers in all toxic profiles. The identification in multiple vectors, as well as in unregulated species, suggests that a risk assessment and risk management update are required; also, chemical and specific analyses for the detection of all analogues associated with the STX-group need to be established.

  5. Nutrient and Phytoplankton Analysis of a Mediterranean Coastal Area

    Science.gov (United States)

    Sebastiá, M. T.; Rodilla, M.

    2013-01-01

    Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected ( Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

  6. Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

    Science.gov (United States)

    Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

    2015-07-01

    Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, hardly any data is available for organic cyst-forming dinoflagellates while this is an ecologically important group with a unique fossil record. We performed dilute batch experiments with four harmful dinoflagellate species known for their ability to form organic cysts: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at a range of dissolved CO2 concentrations characterizing past, modern and projected future values (∼5-50 μmol L-1), representing atmospheric pCO2 of 180, 380, 800 and 1200 μatm. In all tested species, 13C fractionation depends on CO2 with a slope of up to 0.17‰ (μmol L)-1. Even more consistent correlations were found between 13C fractionation and the combined effects of particulate organic carbon quota (POC quota; pg C cell-1) and CO2. Carbon isotope fractionation as well as its response to CO2 is species-specific. These results may be interpreted as a first step towards a proxy for past pCO2 based on carbon isotope ratios of fossil organic dinoflagellate cysts. However, additional culture experiments focusing on environmental variables other than pCO2, physiological underpinning of the recorded response, testing for possible offsets in 13C values between cells and cysts, as well as field calibration studies are required to establish a reliable proxy.

  7. Characterisation of algal organic matter produced by bloom-forming marine and freshwater algae

    KAUST Repository

    Villacorte, Loreen O.

    2015-04-01

    Algal blooms can seriously affect the operation of water treatment processes including low pressure (micro- and ultra-filtration) and high pressure (nanofiltration and reverse osmosis) membranes mainly due to accumulation of algal-derived organic matter (AOM). In this study, the different components of AOM extracted from three common species of bloom-forming algae (Alexandrium tamarense, Chaetoceros affinis and Microcystis sp.) were characterised employing various analytical techniques, such as liquid chromatography - organic carbon detection, fluorescence spectroscopy, fourier transform infrared spectroscopy, alcian blue staining and lectin staining coupled with laser scanning microscopy to indentify its composition and force measurement using atomic force microscopy to measure its stickiness. Batch culture monitoring of the three algal species illustrated varying characteristics in terms of growth pattern, cell concentration and AOM release. The AOM produced by the three algal species comprised mainly biopolymers (e.g., polysaccharides and proteins) but some refractory compounds (e.g., humic-like substances) and other low molecular weight acid and neutral compounds were also found. Biopolymers containing fucose and sulphated functional groups were found in all AOM samples while the presence of other functional groups varied between different species. A large majority (>80%) of the acidic polysaccharide components (in terms of transparent exopolymer particles) were found in the colloidal size range (<0.4μm). The relative stickiness of AOM substantially varied between algal species and that the cohesion between AOM-coated surfaces was much stronger than the adhesion of AOM on AOM-free surfaces. Overall, the composition as well as the physico-chemical characteristics (e.g., stickiness) of AOM will likely dictate the severity of fouling in membrane systems during algal blooms.

  8. Environmental barcoding reveals massive dinoflagellate diversity in marine environments.

    Directory of Open Access Journals (Sweden)

    Rowena F Stern

    2010-11-01

    Full Text Available Dinoflagellates are an ecologically important group of protists with important functions as primary producers, coral symbionts and in toxic red tides. Although widely studied, the natural diversity of dinoflagellates is not well known. DNA barcoding has been utilized successfully for many protist groups. We used this approach to systematically sample known "species", as a reference to measure the natural diversity in three marine environments.In this study, we assembled a large cytochrome c oxidase 1 (COI barcode database from 8 public algal culture collections plus 3 private collections worldwide resulting in 336 individual barcodes linked to specific cultures. We demonstrate that COI can identify to the species level in 15 dinoflagellate genera, generally in agreement with existing species names. Exceptions were found in species belonging to genera that were generally already known to be taxonomically challenging, such as Alexandrium or Symbiodinium. Using this barcode database as a baseline for cultured dinoflagellate diversity, we investigated the natural diversity in three diverse marine environments (Northeast Pacific, Northwest Atlantic, and Caribbean, including an evaluation of single-cell barcoding to identify uncultivated groups. From all three environments, the great majority of barcodes were not represented by any known cultured dinoflagellate, and we also observed an explosion in the diversity of genera that previously contained a modest number of known species, belonging to Kareniaceae. In total, 91.5% of non-identical environmental barcodes represent distinct species, but only 51 out of 603 unique environmental barcodes could be linked to cultured species using a conservative cut-off based on distances between cultured species.COI barcoding was successful in identifying species from 70% of cultured genera. When applied to environmental samples, it revealed a massive amount of natural diversity in dinoflagellates. This highlights

  9. Nutrient and phytoplankton analysis of a Mediterranean coastal area.

    Science.gov (United States)

    Sebastiá, M T; Rodilla, M

    2013-01-01

    Identifying and quantifying the key anthropogenic nutrient input sources are essential to adopting management measures that can target input for maximum effect in controlling the phytoplankton biomass. In this study, three systems characterized by distinctive main nutrient sources were sampled along a Mediterranean coast transect. These sources were groundwater discharge in the Ahuir area, the Serpis river discharge in the Venecia area, and a submarine wastewater outfall 1,900 m from the coast. The study area includes factors considered important in determining a coastal area as a sensitive area: it has significant nutrient sources, tourism is a major source of income in the region, and it includes an area of high water residence time (Venecia area) which is affected by the harbor facilities and by wastewater discharges. We found that in the Ahuir and the submarine wastewater outfall areas, the effects of freshwater inputs were reduced because of a greater water exchange with the oligotrophic Mediterranean waters. On the other hand, in the Venecia area, the highest levels of nutrient concentration and phytoplankton biomass were attributed to the greatest water residence time. In this enclosed area, harmful dinoflagellates were detected (Alexandrium sp. and Dinophysis caudata). If the planned enlargement of the Gandia Harbor proceeds, it may increase the vulnerability of this system and provide the proper conditions of confinement for the dinoflagellate blooms' development. Management measures should first target phosphorus inputs as this is the most potential-limiting nutrient in the Venecia area and comes from a point source that is easier to control. Finally, we recommend that harbor environmental management plans include regular monitoring of water quality in adjacent waters to identify adverse phytoplankton community changes.

  10. Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: Does cell size really matter?

    International Nuclear Information System (INIS)

    Othman, Hiba Ben; Leboulanger, Christophe; Le Floc’h, Emilie; Hadj Mabrouk, Hassine; Sakka Hlaili, Asma

    2012-01-01

    Highlights: ► Polycyclic aromatic hydrocarbons (PAHs) in the marine environment are a hazardous chemical legacy. ► Benz(a)anthracene and fluoranthene are toxic to phytoplankton photosynthesis and growth in culture. ► Acute (photosynthesis) and chronic (population growth) effects have different thresholds. ► Toxicity depends on both the species selected as a model and the compound considered. ► Further study of the size/sensitivity relationship is required to draw more general conclusions. - Abstract: The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L −1 . The short-term (24 h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent. For acute effects, fluoranthene was more toxic than benz(a)anthracene, with LOECs of 50.6 and 186 μg L −1 , respectively. After 72 h exposure, there was a dose-dependent decrease in cell density, fluoranthene being more toxic than benz(a)anthracene. The population endpoint at 72 h was affected to a greater extent than the photosynthetic endpoint at 24 h. EC50 was evaluated using the Hill model, and species sensitivity was negatively correlated to cell biovolume. The largest species tested, the dinoflagellate Alexandrium catenella, was almost insensitive to either PAH. The population endpoint EC50s for fluoranthene varied from 54 μg L −1 for the picophytoplankton Picochlorum sp. to 418 μg L −1 for the larger diatom Chaetoceros muelleri. The size/sensitivity relationship is proposed as a useful model when there is a lack of ecotoxicological data on hazardous chemicals, especially in marine microorganisms.

  11. A journey into the wild of the cnidarian model system Aiptasia and its symbionts

    KAUST Repository

    Voolstra, Christian R.

    2013-08-27

    distinct Aiptasia lineages are prevalent that have probably been spread through human activity. One lineage engages in a specific symbiosis with Symbiodinium minutum throughout the tropics, whereas a second, local Aiptasia sp. population in Florida appears more flexible in partnering with more than one symbiont. The existence of symbiont-specific and symbiont-flexible Aiptasia lineages can greatly complement laboratory-based experiments looking into mechanisms of symbiont selectivity. In a broader context, the study by Thornhill et al. (2013) should inspire more studies to target the natural environment of model systems in a global context targeting all participating member species when establishing ecological and genetic baselines. © 2013 John Wiley & Sons Ltd.

  12. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  13. Use of Open Source Hardware and Software Platforms to Quantify Spectrally Dependent Differences in Photochemical Efficiency and Functional Absorption Cross Section within the Dinoflagellate Symbiodinium spp.

    Directory of Open Access Journals (Sweden)

    Kenneth D. Hoadley

    2017-11-01

    Full Text Available Active chlorophyll a fluorescence is an essential tool for understanding photosynthetic activity within cnidarian/dinoflagellate symbioses. Fluorescence measurement is typically achieved by utilizing a blue or red monochromatic excitation light source. However, algal photosynthetic pigments can differ in their absorption spectra, potentially leading to excitation wavelength dependent measurements of maximal and light acclimated PSII photosynthetic quantum yield (Fv/Fm or Fq′/Fm′ and functional absorption cross section (σPSII or σPSII′. Here we utilized an open source hardware development platform to construct a multispectral excitation fluorometer to assess spectrally dependent differences in photochemistry within four different Symbiodinium species (two of each ITS2-type A4 and B1. Multivariate analysis of light acclimated photochemical signatures showed separation between most alga types. These spectrally dependent differences in light acclimated PSII efficiency and PSII functional absorption cross section likely reflect changes in light harvesting compounds, their connectivity to the PSII reaction centers and the balance between photochemical and non-photochemical fluorescence quenching. Additionally, acclimation to low (20 μmol photons m−2 s−1 and high (200 μmol photons m−2 s−1 light conditions was examined in two of these symbionts types (ITS-2 type A4 and B1 As expected, chlorophyll a cell−1 decreased under high light acclimation in both symbionts. However, only A4 saw a subsequent reduction in absorbance whereas cellular volume decreased in the B1 (S. minutum symbiont. In response to high light acclimation, Fv/Fm was significantly lower at all excitation wavelengths for the B1 symbiont where as efficiencies remained the same for A4. However, high-light acclimated Fq′/Fm′ levels decreased in both symbionts, but only when measured using the 615 or 625 nm excitation wavelengths. Non-photochemical quenching within the

  14. The Impact of the 1989 Exxon Valdez Oil Spill on Phytoplankton as Evidenced Through the Sedimentary Dinoflagellate Cyst Records in Prince William Sound (Alaska, USA).

    Science.gov (United States)

    Genest, M.; Pospelova, V.; Williams, J. R.; Dellapenna, T.; Mertens, K.; Kuehl, S. A.

    2016-12-01

    Large volumes of crude oil are extracted from marine environments and transported via the sea, putting coastal communities at a greater risk of oils spills. It is therefore crucial for these communities to properly assess the risk. The first step is to understand the effects of such events on the environment, which is limited by the lack of research on the impact of oil spills on phytoplankton. This first-of-its-kind research aims to identify how one of the major groups of phytoplankton, dinoflagellates, have been affected by the 1989 Exxon Valdez oil spill in Prince William Sound (PWS), Alaska. To do this, sedimentary records of dinoflagellate cysts, produced during dinoflagellate reproduction and preserved in the sediment, were analyzed. Two sediment cores were collected from PWS in 2012. The sediments are mainly composed of silt with a small fraction of clay. Both well-dated with 210Pb and 137Cs, the cores have high sedimentation rates, allowing for an annual to biannual resolution. Core 10 has a sedimentation rate of 1.1 cm yr-1 and provides continuous record since 1957, while Core 12 has a sedimentation rate of 1.3 cm yr-1 and spans from 1934. The cores were subsampled every centimeter for a total of 110 samples. Samples were treated using a standard palynological processing technique to extract dinoflagellate cysts and 300 cysts were counted per sample. In both cores, cysts were abundant, diverse and well preserved with the average cyst assemblage being characterized by an equal number of cysts produced by autotrophic and heterotrophic dinoflagellates. Of the 40 dinoflagellate cyst taxa, the most abundant are: Operculodinium centrocarpum and Brigantedinium spp. Other common species are: Spiniferites ramosus, cysts of Pentapharsodinium dalei, Echinidinium delicatum, E. zonneveldiae, E. transparantum, Islandinium minutum, and a thin pale brown Brigantedinium type. Changes in the sedimentary sequence of dinoflagellate cysts were analyzed by determining cyst

  15. Distribution of Epilithic Diatoms in Estuaries of the Korean Peninsula in Relation to Environmental Variables

    Directory of Open Access Journals (Sweden)

    Ha-Kyung Kim

    2015-11-01

    highest indicator values (>60% of each group were electrical conductivity for Navicula saprophila and Reimeria sinuate of Ia, and turbidity for Encyonema minutum of IIa. Collectively, the distribution of epilithic diatom communities inhabiting Korean estuaries are determined by geographical factors and water quality, which are in turn influenced by land cover and use, and which differ from east to west.

  16. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  17. Ammonia production by ruminal microorganisms and enumeration, isolation, and characterization of bacteria capable of growth on peptides and amino acids from the sheep rumen.

    Science.gov (United States)

    Eschenlauer, S C P; McKain, N; Walker, N D; McEwan, N R; Newbold, C J; Wallace, R J

    2002-10-01

    Excessive NH(3) production in the rumen is a major nutritional inefficiency in ruminant animals. Experiments were undertaken to compare the rates of NH(3) production from different substrates in ruminal fluid in vitro and to assess the role of asaccharolytic bacteria in NH(3) production. Ruminal fluid was taken from four rumen-fistulated sheep receiving a mixed hay-concentrate diet. The calculated rate of NH(3) production from Trypticase varied from 1.8 to 19.7 nmol mg of protein(-1) min(-1) depending on the substrate, its concentration, and the method used. Monensin (5 micro M) inhibited NH(3) production from proteins, peptides, and amino acids by an average of 28% with substrate at 2 mg/ml, compared to 48% with substrate at 20 mg/ml (P = 0.011). Of the total bacterial population, 1.4% grew on Trypticase alone, of which 93% was eliminated by 5 micro M monensin. Many fewer bacteria (0.002% of the total) grew on amino acids alone. Nineteen isolates capable of growth on Trypticase were obtained from four sheep. 16S ribosomal DNA and traditional identification methods indicated the bacteria fell into six groups. All were sensitive to monensin, and all except one group (group III, similar to Atopobium minutum), produced NH(3) at >250 nmol min(-1) mg of protein(-1), depending on the medium, as determined by a batch culture method. All isolates had exopeptidase activity, but only group III had an apparent dipeptidyl peptidase I activity. Groups I, II, and IV were most closely related to asaccharolytic ruminal and oral Clostridium and Eubacterium spp. Group V comprised one isolate, similar to Desulfomonas piger (formerly Desulfovibrio pigra). Group VI was 95% similar to Acidaminococcus fermentans. Growth of the Atopobium- and Desulfomonas-like isolates was enhanced by sugars, while growth of groups I, II, and V was significantly depressed by sugars. This study therefore demonstrates that different methodologies and different substrate concentrations provide an explanation

  18. Olsenella umbonata sp. nov., a microaerotolerant anaerobic lactic acid bacterium from the sheep rumen and pig jejunum, and emended descriptions of Olsenella, Olsenella uli and Olsenella profusa.

    Science.gov (United States)

    Kraatz, Mareike; Wallace, R John; Svensson, Liselott

    2011-04-01

    Strain A2 is an anaerobic, variably Gram-stain-positive, non-spore-forming, small and irregularly rod-shaped bacterium from the ruminal fluid of a sheep that has been described informally as a representative of 'Olsenella (basonym Atopobium) oviles'. Three phenotypically similar bacterial strains (lac15, lac16 and lac31(T)) were isolated in concert with Veillonella magna lac18(T) from the mucosal jejunum of a pig. A phylogenetic analysis based on 16S rRNA gene sequences revealed that strains A2, lac15, lac16 and lac31(T) formed a genetically coherent group (100 % interstrain sequence similarity) within the bigeneric Olsenella-Atopobium branch of the family Coriobacteriaceae, class Actinobacteria. This group was most closely related to the type strains of the two recognized Olsenella species, namely Olsenella uli (sequence similarity of 96.85 %) and Olsenella profusa (sequence similarity of 97.20 %). The sequence similarity to the type strain of Atopobium minutum, the type species of the genus Atopobium, was 92.33 %. Unlike those of O. uli and O. profusa, outgrown colonies of strains A2, lac15, lac16 and lac31(T) were opaque and greyish-white with an umbonate elevation on solid culture media. The four novel strains were characterized as being well-adapted and presumably indigenous to the gastrointestinal tract of homoeothermic vertebrates: they were mesophilic, microaerotolerant, neutrophilic and acidotolerant, bile-resistant, mucin-utilizing and markedly peptidolytic lactic acid bacteria. The results of DNA-DNA hybridizations, cellular fatty acid analysis and other differential phenotypic (physiological and biochemical) tests confirmed that strains A2, lac15, lac16 and lac31(T) represent a novel species of the genus Olsenella. On the basis of the genotypic and phenotypic results, we therefore describe Olsenella umbonata sp. nov., with lac31(T) ( = CCUG 58604(T)  = DSM 22620(T)  = JCM 16156(T)) as the type strain and A2 ( = CCUG 58212

  19. Combined effects of the herbicide terbuthylazine and temperature on different flagellates from the Northern Adriatic Sea.

    Science.gov (United States)

    Fiori, Emanuela; Mazzotti, Matilde; Guerrini, Franca; Pistocchi, Rossella

    2013-03-15

    The triazinic herbicide terbuthylazine (TBA) is becoming an emergent contaminant in Italian rivers and in coastal and groundwater. A preliminary analysis of the sensitivity of marine flagellates to TBA was performed by monitoring the photosynthetic efficiency of nine species (belonging to the Dinophyceae or Raphidophyceae class) isolated from the Adriatic Sea. Different sensitivity levels for each flagellate were observed and the most sensitive microalgae, based on PSII inhibition, were: Gonyaulax spinifera>Fibrocapsa japonica>Lingulodinium polyedrum while the most resistant were two species belonging to the Prorocentrum genus. Then the response of two microalgae to drivers, such as temperature and terbuthylazine, applied in combination was also investigated. Two potentially toxic flagellates, Prorocentrum minimum and G. spinifera, were exposed, under different temperature conditions (15, 20 and 25°C), to TBA concentrations that did not completely affect PSII. For both flagellates, effects of TBA on algal growth, measured through cell density and carbon analysis, as well as on the photosynthetic activity are reported. All parameters analyzed showed a negative effect of TBA from the exponential phase. TBA effect on algal growth was significantly enhanced at the optimal temperature conditions (20 and 25°C), while no difference between control and herbicide treatments were detected for G. spinifera grown at 15°C, which represented a stress condition for this species. The maximum inhibition of photosynthetic efficiency was found at 20°C for both organisms. Both flagellates increased cell carbon and nitrogen content in herbicide treatments compared to the control, except G. spinifera grown at 15°C. Chlorophyll-a production was increased only in G. spinifera exposed to 5 μg L(-1) of TBA and the effect was enhanced with the increase of temperature. Herbicide-induced variations in cellular components determined changes in cellular carbon:nitrogen (C:N) and

  20. Toxicity of benz(a)anthracene and fluoranthene to marine phytoplankton in culture: Does cell size really matter?

    Energy Technology Data Exchange (ETDEWEB)

    Othman, Hiba Ben [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia); Leboulanger, Christophe, E-mail: christophe.leboulanger@ird.fr [UMR 5119 ECOSYM, CNRS-IRD-Universite Montpellier II-Ifremer-Universite Montpellier I, SMEL 2 rue des Chantiers, F-34200 Sete (France); Le Floc' h, Emilie [UMS MEDIMEER, CNRS-Universite Montpellier II, SMEL 2 rue des Chantiers F-34200 Sete (France); Hadj Mabrouk, Hassine; Sakka Hlaili, Asma [Laboratoire de Cytologie Vegetale et Phytoplanctonologie, Faculte des Sciences de Bizerte, Universite de Carthage, Zarzouna 7021, Bizerte (Tunisia)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer Polycyclic aromatic hydrocarbons (PAHs) in the marine environment are a hazardous chemical legacy. Black-Right-Pointing-Pointer Benz(a)anthracene and fluoranthene are toxic to phytoplankton photosynthesis and growth in culture. Black-Right-Pointing-Pointer Acute (photosynthesis) and chronic (population growth) effects have different thresholds. Black-Right-Pointing-Pointer Toxicity depends on both the species selected as a model and the compound considered. Black-Right-Pointing-Pointer Further study of the size/sensitivity relationship is required to draw more general conclusions. - Abstract: The toxicity of benz(a)anthracene and fluoranthene (polycyclic aromatic hydrocarbons, PAHs) was evaluated on seven species of marine algae in culture belonging to pico-, nano-, and microphytoplankton, exposed to increasing concentrations of up to 2 mg L{sup -1}. The short-term (24 h) toxicity was assessed using chlorophyll a fluorescence transients, linked to photosynthetic parameters. The maximum quantum yield Fv/Fm was lower at the highest concentrations tested and the toxicity thresholds were species-dependent. For acute effects, fluoranthene was more toxic than benz(a)anthracene, with LOECs of 50.6 and 186 {mu}g L{sup -1}, respectively. After 72 h exposure, there was a dose-dependent decrease in cell density, fluoranthene being more toxic than benz(a)anthracene. The population endpoint at 72 h was affected to a greater extent than the photosynthetic endpoint at 24 h. EC50 was evaluated using the Hill model, and species sensitivity was negatively correlated to cell biovolume. The largest species tested, the dinoflagellate Alexandrium catenella, was almost insensitive to either PAH. The population endpoint EC50s for fluoranthene varied from 54 {mu}g L{sup -1} for the picophytoplankton Picochlorum sp. to 418 {mu}g L{sup -1} for the larger diatom Chaetoceros muelleri. The size/sensitivity relationship is proposed as a useful model when

  1. Impact of floral sources and processing on the antimicrobial activities of different unifloral honeys

    Science.gov (United States)

    Elbanna, Khaled; Attalla, Khaled; Elbadry, Medhat; Abdeltawab, Awad; Gamal-Eldin, Hosny; Ramadan, Mohamed Fawzy

    2014-01-01

    Objective To study in vitro antibacterial activity and physicochemical properties of three unifloral honeys (citrus, clover and cotton honeys), and to study the impacts of storage, dilution with water (33%, w/v) and autoclaving (121 °C for 15 min) on honeys characteristics. Methods Honey samples from monofloral sources including citrus (Citrus spp.), Egyptian clover (Trifolium alexandrium) and cotton (Gossypium vitifolium) were obtained during three successive seasons (2010-2012). Physicochemical properties and antimicrobial activities of different honey samples were studies. Results In honey samples stored for 12 or 24 month, colour, hydroxymethyl furfural and acidity increased, while refractive index, water activity, total soluble solids, electrical conductivity and pH remained relatively unaffected, but H2O2 values decreased. Types of honey exhibited various degrees of antibacterial activity against different indicator bacteria, wherein the highest antibacterial activity was recorded for clover honey followed by citrus and cotton honeys, respectively. Different species of bacteria were differed in their sensitivity to honey, wherein Salmonella enteritidis was the most sensitive followed by Staphylococcus aureus, Listeria monocytogenes and Escherichia coli, respectively. Storage up to 24 months at room temperature slightly reduced the antibacterial activity. The reduction levels were about 2.6% and 4.6% after 12 and 24 months, respectively. Diluting honeys with water increased the antibacterial activity by ca. 8.3%, while autoclaving decreased the antibacterial activity by ca. 13.5%. The relative contribution of the peroxide and non-peroxide components in the total antibacterial activity of fresh honeys was investigated. The antibacterial activity of honeys was mainly attributed to non-peroxide antibacterial agents, wherein their contribution was ca. 88%, while the contribution of H2O2 was only 12%. The contribution of the thermostable antibacterial components

  2. Understanding interannual, decadal level variability in paralytic shellfish poisoning toxicity in the Gulf of Maine: The HAB Index

    Science.gov (United States)

    Anderson, Donald M.; Couture, Darcie A.; Kleindinst, Judith L.; Keafer, Bruce A.; McGillicuddy, Dennis J., Jr.; Martin, Jennifer L.; Richlen, Mindy L.; Hickey, J. Michael; Solow, Andrew R.

    2014-05-01

    A major goal in harmful algal bloom (HAB) research has been to identify mechanisms underlying interannual variability in bloom magnitude and impact. Here the focus is on variability in Alexandrium fundyense blooms and paralytic shellfish poisoning (PSP) toxicity in Maine, USA, over 34 years (1978-2011). The Maine coastline was divided into two regions - eastern and western Maine, and within those two regions, three measures of PSP toxicity (the percent of stations showing detectable toxicity over the year, the cumulative amount of toxicity per station measured in all shellfish (mussel) samples during that year, and the duration of measurable toxicity) were examined for each year in the time series. These metrics were combined into a simple HAB Index that provides a single measure of annual toxin severity across each region. The three toxin metrics, as well as the HAB Index that integrates them, reveal significant variability in overall toxicity between individual years as well as long-term, decadal patterns or regimes. Based on different conceptual models of the system, we considered three trend formulations to characterize the long-term patterns in the Index - a three-phase (mean-shift) model, a linear two-phase model, and a pulse-decline model. The first represents a “regime shift” or multiple equilibria formulation as might occur with alternating periods of sustained high and low cyst abundance or favorable and unfavorable growth conditions, the second depicts a scenario of more gradual transitions in cyst abundance or growth conditions of vegetative cells, and the third characterizes a ”sawtooth” pattern in which upward shifts in toxicity are associated with major cyst recruitment events, followed by a gradual but continuous decline until the next pulse. The fitted models were compared using both residual sum of squares and Akaike's Information Criterion. There were some differences between model fits, but none consistently gave a better fit than the

  3. A comparative study for PSP toxins quantification by using MBA and HPLC official methods in shellfish.

    Science.gov (United States)

    Ben-Gigirey, B; Rodríguez-Velasco, M L; Otero, A; Vieites, J M; Cabado, A G

    2012-10-01

    Commission Regulation (EC) N° 2074/2005 recognises the biological method as the reference method for Paralytic Shellfish Poisoning (PSP) toxins detection in molluscs. It was amended by Commission Regulation (EC) N° 1664/2006 that accepted the so-called Lawrence method as an alternative to the reference method. The goal of this study was to compare AOAC Official Methods of Analysis 959.08 (Biological method) and 2005.06 (Prechromatographic Oxidation and Liquid Chromatography with fluorescence detection) in samples with different toxin profiles. The influence of extraction solvent in the total samples toxicity was also evaluated. A total of 40 samples including mussels, clams, scallops, razor-clams, cockles, oysters and barnacles were analysed by both official methods. Samples were selected with Alexandrium and Gymnodinium toxic profiles, from different origin and including several presentations: fresh, frozen, canned and boiled. Acetic and hydrochloric acid extractions were performed in all samples and the extracts were simultaneously analysed by both methods. Most samples were naturally contaminated and two samples were spiked. Comparison of both official methods, mouse bioassay (MBA) with HCl extraction and Liquid Chromatography with fluorescence detection (HPLC-FLD) with acetic acid extraction, led to an 85% of consistent results regarding compliance with legal limit, including samples below and above it. The linear correlation coefficient was r² = 0.69 and the paired t test (two tails, α = 0.05) indicated that there were not significant differences among both sets of data. Nevertheless, toxicity differences were found in several samples. In 15 out of 18 shellfish with a Gymnodinium toxic profile, higher toxicity levels were obtained by MBA. This fact was more evident in 7 samples, partially related to the lack of standards and the impossibility of analysing dc-NEO, C1, 2 and GTX6 at the beginning of the study. However, other factors concerning the extraction

  4. DAMPAK PEMBUANGAN LIMBAH TERHADAP PERUBAHAN KUALITAS OSEANOGRAFI BIOFISIK-KIMIA DAN PRODUKSI IKAN TERI (Stolephorus spp. DI PERAIRAN LAUT TELUK AMBON (The Impact of Waste Disposal on the Biophysical-chemical Characteristics Changes and Teri fish

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    Latif Sahubawa

    2001-04-01

    Full Text Available ABSTRAK Tujuan penelitian adalah untuk: (l mengidentifikasi karakteristik limbah hasil aktivitas manusia di pesisir teluk yang berpengaruh potensial terhadap penurunan sifat oseanografi biofisik-kimia perairan Laut Teluk Ambon; (2 mengevaluasi perubahan sifat oseanografi biofisik-kimia perairan dalam kaitannya dengan penyimpangan persyaratan peruntukkan sebagai tempat budi daya perikanan; dan (3 mengevaluasi pengaruh penyimpangan persyaratan peruntukan badan air laut terhadap potensi dan densitas ikan pelagis kecil, serta produksi ikan teri pada musim Timur dan Barat. Sampel penelitian terdiri atas air laut, ikan teri, dan kerang. Teknik pengambilan sampel ialah dengan pengacakan dan tanpa pengacakan. Teknik pengambilan data berupa survei, analisis laboratorium, wawancara, dan kuesioner. Metode analisis data Kurva Normal, Kuadrat Terkecil, Rancangan Acak Lengkap Pola Faktorial dan Berblok dengan Uji-F, Koefisien Nilai Nutrisi (KNN, Produksi Surplus, Hidroakustik, dan Sedimentasi Utermohl. Berdasarkan hasil analisis statistik, umumnya variabel penelitian tidak berpengaruh terhadap perubahan parameter oseanografi biofisik-kimia perairan Teluk Ambon, kecuali bahwa lokasi sampling berpengaruh terhadap nilai kecerahan pada tingkat signifikansi 95%. Kisaran nilai parameter oseanografi biofisik-kimia perairan laut ialah temperatur 23,7 - 28,7"C; TSS 2,005 - 12,436 mg/^; salinitas 24,00 - 35,50 mill; kecerahan 2,5 - 9,0 meter; pH 6,5 - 8,6; oksigen terlarut 2,09 - 6,88 mgA; BODs 10 - 50 mg/l; COD 22,5 - 150,8 mg/l; PO43- 0,22 - 3,29 mg/L, NQ-0.02 -2,94 mg/L; NO3- 21- 15,40 mg/L; Hg 0,001- 0,065 mg/L; KNN 0,27 -0/8 gr/cm; fitoplankton red-tede spesies Alexandrium affrne dengan jumlah 60,0 x 105 sel/liter menimbulkan perubahan warna perairan menj adi merah-kecoklatan. Produksi ikan teri pada musim Timur 191,5 ton (59,5 % dan musim Barat 130,2 ton (40,5 %. Populasi maksimum telur dan larva ikan teri adalah 4.090 telur/SO mt pada musim Timur dan 396 ekor/50