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Sample records for marine dinoflagellate alexandrium

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

    PubMed Central

    2010-01-01

    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. PMID:20403159

  2. Effects of toxic dinoflagellate Alexandrium tamarense on the energy budgets and growth of two marine bivalves.

    PubMed

    Li, Siu-Chung; Wang, Wen-Xiong; Hsieh, Dennis P H

    2002-03-01

    Harmful algal blooms (HAB) may impose a serious threat to aquatic lives and human health. We determined the effects of a toxic dinoflagellate Alexandrium tamarense (clone ATCIO1, isolated from Hong Kong coastal waters) on the energy budget, quantified as scope for growth (SFG), and the growth rate of the manila clam Ruditapes philippinarum and the green-lipped mussel Perna viridis. To quantify the SFG, clams and mussels were dosed with different amounts of toxic A. tamarense for 6 days, resulting in different toxin burdens in the tissues. Clearance rate, absorption efficiency, and respiration rate were subsequently measured in these toxin containing bivalves. Clearance rate significantly declined at the highest toxin burden in the clams only, while there was no significant difference in the clearance rate among different treatments for the mussels. The respiration rate of either bivalve was not significantly affected by toxin accumulation in the tissues. In contrast, the absorption efficiency of both clams and mussels decreased, in a concentration-dependent manner for mussels but not for clams, when the tissue accumulated the toxins. With an increase in paralytic shellfish poisoning (PSP) toxin burden, SFG in both clams and mussels was significantly reduced, primarily because of the decrease of absorption efficiency. The growth rate of juvenile clam R. philippinarum, measured as an increment in tissue dry weight over a 15 d exposure period, was significantly lower during their feeding on toxic dinoflagellate than the growth rate of clams feeding on the diatom Thalassiosira pseudonana. The juvenile mussel P. viridis, however, exhibited similar growth rates after feeding on the toxic dinoflagellates and the nontoxic diatom. This study showed that SFG can provide a sensitive and integrated measure of the effect of HAB on the physiology of bivalves. Clam R. philippinarum may be more sensitive, in terms of their energy budget, to PSP toxin accumulation than the mussel P

  3. Photosynthetic Carbon Isotope Fractionation of the Marine Dinoflagellate Alexandrium tamarense: A Chemostat Investigation of Taxonomic and Physiological Controls on the Stable Carbon Isotope Record

    NASA Astrophysics Data System (ADS)

    Wilkes, E.; Carter, S. J.; Pearson, A.

    2015-12-01

    Interpretations of stable carbon isotope excursions in the sedimentary record are strengthened by laboratory culture studies investigating the photosynthetic carbon isotope fractionation (ɛp) of marine phytoplankton taxa with long geological records. These studies are essential for understanding organic matter δ13C signals in terms of environmental changes (e.g., atmospheric pCO2 and nutrient availability) or taxonomic changes (e.g., algal species succession and community composition). Dinoflagellates are among the most widespread and ecologically dominant primary producers in modern oceans and throughout the Mesozoic and Cenozoic. Compared to more recently evolved phytoplankton taxa, however, dinoflagellate carbon isotope fractionation has received relatively little mechanistic study. Several dilute batch culture experiments with dinoflagellates have investigated ɛp as a function of CO2 availability, but the influences of changing growth rates, nutrient limitation, pH, and irradiance require further systematic exploration. We investigated stable carbon isotope fractionation in the marine dinoflagellate Alexandrium tamarense under nitrate-limited conditions in a chemostat culture system in which full DIC system parameters, including the concentration and δ13C value of CO2, were determined. Growth rates were varied between experiments, and cells were grown under continuous light. Previously reported ɛp values for seven dinoflagellate species including A. tamarense ranged from approximately -1 to 14‰ in nutrient-replete batch culture studies ([CO2] = 0-50 µmol kg-1). In contrast, in chemostat conditions we measured ɛp values on the order of 20‰ ([CO2] = 20-30 µmol kg-1). These experiments provide an initial step toward understanding the physiological controls on ɛp in dinoflagellates and illuminating the role of algal taxonomy in shaping the Phanerozoic stable carbon isotope record.

  4. A novel algicide: evidence of the effect of a fatty acid compound from the marine bacterium, Vibrio sp. BS02 on the harmful dinoflagellate, Alexandrium tamarense.

    PubMed

    Li, Dong; Zhang, Huajun; Fu, Lijun; An, Xinli; Zhang, Bangzhou; Li, Yi; Chen, Zhangran; Zheng, Wei; Yi, Lin; Zheng, Tianling

    2014-01-01

    Alexandrium tamarense is a notorious bloom-forming dinoflagellate, which adversely impacts water quality and human health. In this study we present a new algicide against A. tamarense, which was isolated from the marine bacterium Vibrio sp. BS02. MALDI-TOF-MS, NMR and algicidal activity analysis reveal that this compound corresponds to palmitoleic acid, which shows algicidal activity against A. tamarense with an EC50 of 40 μg/mL. The effects of palmitoleic acid on the growth of other algal species were also studied. The results indicate that palmitoleic acid has potential for selective control of the Harmful algal blooms (HABs). Over extended periods of contact, transmission electron microscopy shows severe ultrastructural damage to the algae at 40 μg/mL concentrations of palmitoleic acid. All of these results indicate potential for controlling HABs by using the special algicidal bacterium and its active agent. PMID:24626054

  5. Genome sequence of the Roseovarius mucosus type strain (DSM 17069T), a bacteriochlorophyll a-containing representative of the marine Roseobacter group isolated from the dinoflagellate Alexandrium ostenfeldii

    PubMed Central

    2015-01-01

    Roseovarius mucosus Biebl et al. 2005 is a bacteriochlorophyll a-producing representative of the marine Roseobacter group within the alphaproteobacterial family Rhodobacteraceae, which was isolated from the dinoflagellate Alexandrium ostenfeldii. The marine Roseobacter group was found to be abundant in the ocean and plays an important role for global and biogeochemical processes. Here we describe the features of the R. mucosus strain DFL-24T together with its genome sequence and annotation generated from a culture of DSM 17069T. The 4,247,724 bp containing genome sequence encodes 4,194 protein-coding genes and 57 RNA genes. In addition to the presence of four plasmids, genome analysis revealed the presence of genes associated with host colonization, DMSP utilization, cytotoxins, and quorum sensing that could play a role in the interrelationship of R. mucosus with the dinoflagellate A. ostenfeldii and other marine organisms. Furthermore, the genome encodes genes associated with mixotrophic growth, where both reduced inorganic compounds for lithotrophic growth and a photoheterotrophic lifestyle using light as additional energy source could be used. PMID:26203330

  6. SxtA gene sequence analysis of dinoflagellate Alexandrium minutum

    NASA Astrophysics Data System (ADS)

    Norshaha, Safida Anira; Latib, Norhidayu Abdul; Usup, Gires; Yusof, Nurul Yuziana Mohd

    2015-09-01

    The dinoflagellate Alexandrium minutum is typically known for the production of potent neurotoxins such as saxitoxin, affecting the health of human seafood consumers via paralytic shellfish poisoning (PSP). These phenomena is related to the harmful algal blooms (HABs) that is believed to be influenced by environmental and nutritional factors. Previous study has revealed that SxtA gene is a starting gene that involved in the saxitoxin production pathway. The aim of this study was to analyse the sequence of the sxtA gene in A. minutum. The dinoflagellates culture was cultured at temperature 26°C with 16:8-hour light:dark photocycle. After the samples were harvested, RNA was extracted, complementary DNA (cDNA) was synthesised and amplified by polymerase chain reaction (PCR). The PCR products were then purified and cloned before sequenced. The SxtA sequence obtained was then analyzed in order to identify the presence of SxtA gene in Alexandrium minutum.

  7. Gene expression and molecular evolution of sxtA4 in a saxitoxin producing dinoflagellate Alexandrium catenella.

    PubMed

    Wiese, Maria; Murray, Shauna A; Alvin, Alfonsus; Neilan, Brett A

    2014-12-15

    Dinoflagellates of the genus Alexandrium produce the neurotoxin saxitoxin (STX), responsible for paralytic shellfish poisoning (PSP) and accumulates in marine invertebrates. The recent identification of STX biosynthesis genes allowed us to investigate the expression of sxtA4 at different growth stages in Alexandrium catenella Group IV. We found no significant differences in expression of sxtA4, despite significant differences in STX levels at different growth stages (P < 0.023). Three reference genes were tested for normalisation: actin, cytochrome b (cob), and the large subunit ribosomal RNA (LSU rDNA). cob was most stably expressed but the combination of two reference genes, actin and cob, resulted in the best stability factor. Most genomic sequences of sxtA4 from A. catenella were in a clade that included sequences from Alexandrium fundyense Group I, however, one paralogue was not related to the others, suggesting recombination or lateral transfer. A comparison of the sxtA4 cDNA sequences with genomic DNA sequences indicated the possibility of transcript editing and the preferential transcription of certain genomic DNA loci. The results show that, in dinoflagellates, post-transcriptional mechanisms play a major role in the regulation of saxitoxin biosynthesis. PMID:25301480

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

    EPA Science Inventory

    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...

  9. GROWTH RATES AND ELEMENTAL COMPOSITION OF ALEXANDRIUM MONILATUM, A REDTIDE DINOFLAGELLATE

    EPA Science Inventory

    The combined effects of temperature and salinity on growth of Alexandrium monilatum were studied in laboratory cultures. This toxic, red-tide dinoflagellate grew faster with higher temperatures, up to a maximum of approximately 1 division d-1 at 31 C. Salinities above 15 psu had ...

  10. GROWTH RATES, PHYSIOLOGICAL INDICATORS AND ELEMENTAL COMPOSITION OF THE RED-TIDE DINOFLAGELLATE, ALEXANDRIUM MONILATUM

    EPA Science Inventory

    Alexandrium monilatum is a thecate, autotrophic, bioluminescent and chain-forming dinoflagellate. Although it has been known to be associated with red tides and fish kills along the US Gulf of Mexico coast for almost 50 years, little basic physiological information is available f...

  11. Isolation of an algicide from a marine bacterium and its effects against the toxic dinoflagellate Alexandrium catenella and other harmful algal bloom species.

    PubMed

    Kim, Yun Sook; Son, Hong-Joo; Jeong, Seong-Yun

    2015-08-01

    The aim of this study was to isolate and identify bacteria demonstrating an algicidal effect against Alexandrium catenella and to determine the activity and range of any algicide discovered. The morphological and biochemical attributes of an algicidal bacterium, isolate YS-3, and analysis of its 16S rRNA gene sequence revealed it to be a member of the genus Brachybacterium. This organism, designated Brachybacterium sp. YS-3, showed the greatest effect against A. catenella cells of all bacteria isolated, and is assumed to produce secondary metabolites. When 10% solutions of culture filtrates from this strain were applied to A. catenella cultures, over 90% of cells were killed within 9 h. Bioassay-guided isolation of the algicide involved led to the purification and identification of an active compound. Based on physicochemical and spectroscopic data, including nuclear magnetic resonance and mass analyses, this compound was identified as 1-acetyl-β-carboline. This algicide showed significant activity against A. catenella and a wide range of harmful algal bloom (HAB)-forming species. Taken together, our results suggest that Brachybacterium sp. YS-3 and its algicide represent promising candidates for use in HAB control. PMID:26224453

  12. Identification of gymnodimine D and presence of gymnodimine variants in the dinoflagellate Alexandrium ostenfeldii from the Baltic Sea.

    PubMed

    Harju, Kirsi; Koskela, Harri; Kremp, Anke; Suikkanen, Sanna; de la Iglesia, Pablo; Miles, Christopher O; Krock, Bernd; Vanninen, Paula

    2016-03-15

    Gymnodimines are lipophilic toxins produced by the marine dinoflagellates Karenia selliformis and Alexandrium ostenfeldii. Currently four gymnodimine analogues are known and characterized. Here we describe a novel gymnodimine and a range of gymnodimine related compounds found in an A. ostenfeldii isolate from the northern Baltic Sea. Gymnodimine D (1) was extracted and purified from clonal cultures, and characterized by liquid chromatography-tandem mass spectrometry (LC-MS/MS), nuclear magnetic resonance (NMR) spectroscopy, and liquid chromatography-high resolution mass spectrometry (LC-HRMS) experiments. The structure of 1 is related to known gymnodimines (2-5) with a six-membered cyclic imine ring and several other fragments typical of gymnodimines. However, the carbon chain in the gymnodimine macrocyclic ring differs from the known gymnodimines in having two tetrahydrofuran rings in the macrocyclic ring. PMID:26829651

  13. First Report of Parasitism on the Toxic Dinoflagellate Alexandrium minutum Halim

    NASA Astrophysics Data System (ADS)

    Erard-Le Denn, E.; Chrétiennot-Dinet, M.-J.; Probert, I.

    2000-01-01

    Blooms of the toxic red tide phytoplankton Alexandrium minutum Halim (Dinophyceae) have frequently occurred during recent years in the estuaries of northern Brittany, France. Some months after a bloom in the Penzé River in 1997, many Alexandrium cells in samples maintained in the dark at 14 °C were observed to be infected by the sporocysts of an unknown parasite, which, upon exposure to increased light intensity and temperature, ejected many small biflagellate zoospores. The parasite was found to infect laboratory cultures of several other dinoflagellate species, and estimates of parasite-induced mortality indicate that this parasite is capable of removing a significant fraction of dinoflagellate biomass in a short time, raising the possibility of its use as a biological control agent of toxic dinoflagellate blooms. The effect of this parasite on natural A. minutum populations remains, however, to be estimated. This paper presents video images used in a preliminary identification and life cycle elucidation of the parasite, which may be affiliated with the Apicomplexan complex.

  14. Development of a real-time PCR assay for rapid detection and quantification of Alexandrium minutum (a Dinoflagellate).

    PubMed

    Galluzzi, Luca; Penna, Antonella; Bertozzini, Elena; Vila, Magda; Garcés, Esther; Magnani, Mauro

    2004-02-01

    The marine dinoflagellate genus Alexandrium includes a number of species which produce neurotoxins responsible for paralytic shellfish poisoning (PSP), which in humans may cause muscular paralysis, neurological symptoms, and, in extreme cases, death. A. minutum is the most widespread toxic PSP species in the western Mediterranean basin. The monitoring of coastal waters for the presence of harmful algae also normally involves microscopic examinations of phytoplankton populations. These procedures are time consuming and require a great deal of taxonomic experience, thus limiting the number of specimens that can be analyzed. Because of the genetic diversity of different genera and species, molecular tools may also help to detect the presence of target microorganisms in marine field samples. In this study, we developed a real-time PCR-based assay for rapid detection of all toxic species of the Alexandrium genus in both fixative-preserved environmental samples and cultures. Moreover, we developed a real-time quantitative PCR assay for the quantification of A. minutum cells in seawater samples. Alexandrium genus-specific primers were designed on the 5.8S rDNA region. Primer specificity was confirmed by using BLAST and by amplification of a representative sample of the DNA of other dinoflagellates and diatoms. Using a standard curve constructed with a plasmid containing the ITS1-5.8S-ITS2 A. minutum sequence and cultured A. minutum cells, we determined the absolute number of 5.8S rDNA copies per cell. Consequently, after quantification of 5.8S rDNA copies in samples containing A. minutum cells, we were also able to estimate the number of cells. Several fixed A. minutum bloom sea samples from Arenys Harbor (Catalan Coast, Spain) were analyzed using this method, and quantification results were compared with standard microscopy counting methods. The two methods gave comparable results, confirming that real-time PCR could be a valid, fast alternative procedure for the

  15. Environmental Barcoding Reveals Massive Dinoflagellate Diversity in Marine Environments

    PubMed Central

    Stern, Rowena F.; Horak, Ales; Andrew, Rose L.; Coffroth, Mary-Alice; Andersen, Robert A.; Küpper, Frithjof C.; Jameson, Ian; Hoppenrath, Mona; Véron, Benoît; Kasai, Fumai; Brand, Jerry; James, Erick R.; Keeling, Patrick J.

    2010-01-01

    Background 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. Methodology/Principal Findings 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. Conclusions/Significance COI barcoding was successful in identifying species from 70% of cultured genera. When applied to environmental samples, it revealed a massive amount of

  16. Transcriptomic responses of the calanoid copepod Calanus finmarchicus to the saxitoxin producing dinoflagellate Alexandrium fundyense

    PubMed Central

    Roncalli, Vittoria; Cieslak, Matthew C.; Lenz, Petra H.

    2016-01-01

    In the Gulf of Maine, the copepod Calanus finmarchicus co-occurs with the neurotoxin-producing dinoflagellate, Alexandrium fundyense. The copepod is resistant to this toxic alga, but little is known about other effects. Gene expression profiles were used to investigate the physiological response of females feeding for two and five days on a control diet or a diet containing either a low or a high dose of A. fundyense. The physiological responses to the two experimental diets were similar, but changed between the time points. At 5-days the response was characterized by down-regulated genes involved in energy metabolism. Detoxification was not a major component of the response. Instead, genes involved in digestion were consistently regulated, suggesting that food assimilation may have been affected. Thus, predicted increases in the frequency of blooms of A. fundyense could affect C. finmarchicus populations by changing the individuals’ energy budget and reducing their ability to build lipid reserves. PMID:27181871

  17. Transcriptomic responses of the calanoid copepod Calanus finmarchicus to the saxitoxin producing dinoflagellate Alexandrium fundyense.

    PubMed

    Roncalli, Vittoria; Cieslak, Matthew C; Lenz, Petra H

    2016-01-01

    In the Gulf of Maine, the copepod Calanus finmarchicus co-occurs with the neurotoxin-producing dinoflagellate, Alexandrium fundyense. The copepod is resistant to this toxic alga, but little is known about other effects. Gene expression profiles were used to investigate the physiological response of females feeding for two and five days on a control diet or a diet containing either a low or a high dose of A. fundyense. The physiological responses to the two experimental diets were similar, but changed between the time points. At 5-days the response was characterized by down-regulated genes involved in energy metabolism. Detoxification was not a major component of the response. Instead, genes involved in digestion were consistently regulated, suggesting that food assimilation may have been affected. Thus, predicted increases in the frequency of blooms of A. fundyense could affect C. finmarchicus populations by changing the individuals' energy budget and reducing their ability to build lipid reserves. PMID:27181871

  18. CHARACTERIZATION OF 17 NEW MICROSATELLITE MARKERS FOR THE DINOFLAGELLATE ALEXANDRIUM FUNDYENSE (DINOPHYCEAE), A HARMFUL ALGAL BLOOM SPECIES

    PubMed Central

    Sehein, Taylor; Richlen, Mindy L.; Nagai, Satoshi; Yasuike, Motoshige; Nakamura, Yoji; Anderson, Donald M.

    2016-01-01

    Alexandrium fundyense is the toxic marine dinoflagellate responsible for “red tide” events in temperate and sub-arctic waters worldwide. In the Gulf of Maine (GOM) and Bay of Fundy in the Northwest Atlantic, blooms of A. fundyense recur annually, and are associated with major health and ecosystem impacts. In this region, microsatellite markers have been used to investigate genetic structure and gene flow; however, the loci currently available for this species were isolated from populations from Japan and the North Sea, and only a subset are suitable for the analysis of A. fundyense populations in the Northwest Atlantic. To facilitate future studies of A. fundyense blooms, both in this region and globally, we isolated and characterized 17 polymorphic microsatellite loci from 31 isolates collected from the GOM and from the Nauset Marsh System, an estuary on Cape Cod, MA, USA. These loci yielded between two and 15 alleles per locus, with an average of 7.1. Gene diversities ranged from 0.297 to 0.952. We then analyzed these same 31 isolates using previously published markers for comparison. We determined the new markers are sufficiently variable and better suited for the investigation of genetic structure, bloom dynamics, and diversity in the Northwest Atlantic. PMID:27274617

  19. Draft genome sequence of Mameliella alba strain UMTAT08 isolated from clonal culture of toxic dinoflagellate Alexandrium tamiyavanichii.

    PubMed

    Danish-Daniel, Muhd; Han Ming, Gan; Noor, Mohd Ezhar Mohd; Yeong, Yik Sung; Usup, Gires

    2016-12-01

    Mameliella alba strain UMTAT08 was isolated from clonal culture of paralytic shellfish toxin producing dinoflagellate, Alexandrium tamiyavanichii. Genome of the strain UMTAT08 was sequenced in order to gain insights into the dinoflagellate-bacteria interactions. The draft genome sequence of strain UMTAT08 contains 5.84Mbp with an estimated G + C content of 65%, 5717 open reading frames, 5 rRNAs and 49 tRNAs. It contains genes related to nutrients uptake, quorum sensing and environmental tolerance related genes. Gene clusters for the biosynthesis of type 1 polyketide synthase, bacteriocin, microcin, terpene and ectoine were also identified. This is suggesting that the bacterium possesses diverse adaptation strategy to survive within the dinoflagellate phycosphere. The draft genome sequence and annotation have been deposited at DDBJ/EMBL/GenBank under the accession number JSUQ00000000. PMID:27625991

  20. Glutathione S-Transferase Regulation in Calanus finmarchicus Feeding on the Toxic Dinoflagellate Alexandrium fundyense

    PubMed Central

    Roncalli, Vittoria; Jungbluth, Michelle J.; Lenz, Petra H.

    2016-01-01

    The effect of the dinoflagellate, Alexandrium fundyense, on relative expression of glutathione S-transferase (GST) transcripts was examined in the copepod Calanus finmarchicus. Adult females were fed for 5-days on one of three experimental diets: control (100% Rhodomonas spp.), low dose of A. fundyense (25% by volume, 75% Rhodomonas spp.), and high dose (100% A. fundyense). Relative expression of three GST genes was measured using RT-qPCR on days 0.5, 1, 2 and 5 in two independent experiments. Differential regulation was found for the Delta and the Sigma GSTs between 0.5 to 2 days, but not on day 5 in both experiments. The third GST, a microsomal, was not differentially expressed in either treatment or day. RT-qPCR results from the two experiments were similar, even though experimental females were collected from the Gulf of Maine on different dates and their reproductive output differed. In the second experiment, expression of 39 GSTs was determined on days 2 and 5 using RNA-Seq. Global gene expression analyses agreed with the RT-qPCR results. Furthermore, the RNA-Seq measurements indicated that only four GSTs were differentially expressed under the experimental conditions, and the response was small in amplitude. In summary, the A. fundyense diet led to a rapid and transient response in C. finmarchicus in three cytosolic GSTs, while a fourth GST (Omega I) was significantly up-regulated on day 5. Although there was some regulation of GSTs in response the toxic dinoflagellate, the tolerance to A. fundyense by C. finmarchicus is not dependent on the long-term up-regulation of specific GSTs. PMID:27427938

  1. First report of goniodomin A production by the dinoflagellate Alexandrium pseudogonyaulax developing in southern Mediterranean (Bizerte Lagoon, Tunisia).

    PubMed

    Zmerli Triki, Habiba; Laabir, Mohamed; Moeller, Peter; Chomérat, Nicolas; Kéfi Daly-Yahia, Ons

    2016-03-01

    The dinoflagellate Alexandrium pseudogonyaulax is widely distributed around the world including the Mediterranean waters. The objectives of this study were to determine the morphology and phylogenic affiliation of A. pseudogonyaulax strain isolated from Bizerte Lagoon (Mediterranean waters, Tunisia) and investigate its toxicity. Molecular analyses confirmed the morphological identification of the isolated strain (APBZ12) as A. pseudogonyaulax. Moreover, it showed that it is 100% identical with strains of this species found in New Zealand, Japan, China and North Sea (Norway and Denmark) suggesting that this species is cosmopolitan. Until now, no toxin studies have been conducted on fully characterized (morphologically and molecularly) A. pseudogonyaulax. Cellular toxin production was determined using high pressure liquid chromatography coupled to mass spectrometry (HPLC/MS). Results showed for the first time that A. pseudogonyaulax contains goniodomin A (GDA), a highly toxic macrolide polyether previously shown to be produced by two other dinoflagellate species Alexandrium monilatum (Hsia et al., 2006) and Alexandrium hiranoi (erroneously identified as A. pseudogonyaulax in Murakami et al., 1988) in American and Japanese waters, respectively. This biologically active toxin has been associated over decades with fish mortality. Our study showed that the cell extracts of APBZ12 showed an important bioactivity using GH4C1 rat pituitary cytotoxicity bioassay. PMID:26748155

  2. Isolation of bacteria from toxic dinoflagellate Alexandrium minutum and their effects on algae toxicity.

    PubMed

    Lu, Y H; Chai, T J; Hwang, D F

    2000-11-01

    Attempts were made to isolate the bacteria from toxic dinoflagellate Alexandrium minutum T1 and to study the effect of these bacteria on the growth and toxicity of A. minutum T1. It was found that intracellular bacterial species including Pasteurella haemolytica, Pseudomonas vesicularis, and Sphingomonas sp., and extracellular bacterial species including Pasteurolla pneumotropica, Morganella wisconsensis, Flavobacterium oryzihabitans, Pseudomonas pseudomallei, and Sphingomonas sp. All of them were cultured and determined to have non-PSP-producing ability. The maximum cell number of A. minutum cultured without isolated bacteria was higher than that cultured with isolated bacteria. The total toxicity of A. minutum cultured with bacteria was similar to that of A. minutum T1 cultured without bacteria from lag phase to stationary phase, but it was lower after stationary phase. The growth of A. minutum T1 cultured without antibiotics was also better than that cultured with antibiotics. The total toxicity of A. minutum cultured without antibiotics was higher than that of A. minutum cultured with antibiotics. However, the cell toxicity of A. minutum did not decrease even if the culture medium was added with antibiotics. PMID:11126517

  3. 2D-PAGE protein analysis of dinoflagellate Alexandrium minutum based on three different temperatures

    NASA Astrophysics Data System (ADS)

    Latib, Norhidayu Abdul; Norshaha, Safida Anira; Usup, Gires; Yusof, Nurul Yuziana Mohd

    2015-09-01

    Harmful algae bloom or red tide seems to be considered as threat to ecosystem, especially to human consumption because of the production of neurotoxin by dinoflagellates species such as Alexandrium minutum which can lead to paralytic shellfish poisoning. The aim of this study is to determine the most suitable method for protein extraction of A. minutum followed by determination of differential protein expression of A. minutum on three different temperatures (15°C, 26°C and 31.5°C). After the optimization, the protein extract was subjected to two-dimensional polyacrylamide gel electrophoresis (2-DE) to compare the intensity and distribution of the protein spots. Based on quantitative and qualitative protein assessment, use of Trizol reagent is the most suitable method to extract protein from A. minutum. 2-DE analysis of the samples results in different distribution and intensity of the protein spots were compared between 15°C, 26°C and 31.5°C.

  4. Biotransformation of mycosporine like amino acids (MAAs) in the toxic dinoflagellate Alexandrium tamarense.

    PubMed

    Callone, Alan I; Carignan, Mario; Montoya, Nora G; Carreto, José I

    2006-09-01

    Changes in mycosporine-like amino acids (MAAs) induced by the increase of photosynthetically active radiation (PAR) were studied in the toxic dinoflagellate Alexandrium tamarense. Cultures of A. tamarense were maintained at exponential growth under low (25 micromol quanta m(-2)s(-1)) PAR irradiance. The cultures were nutrient enriched and one day later exposed to higher irradiance (150 micromol quanta m(-2)s(-1)). The content of MAAs was determined by means of high performance liquid chromatography (HPLC). Eleven MAAs, including some partially characterized compounds, were identified. The MAAs synthesis induction can be described as a two-stage process. The first one involves the net synthesis of the MAAs bi-substituted by amino acids. In the second stage these compounds were transformed into other secondary MAAs. The two most prominent changes were observed in the concentration of porphyra-334 and palythene. The cellular concentration of porphyra-334 increased during the first 2h of exposure to higher irradiance and then decreased rapidly. In contrast, the cellular concentration of palythene showed a continuous accumulation since the beginning of the exposure. In A. tamarense the main route of MAAs transformation has porphyra-334 as a precursor of a sequential conversion resulting in the accumulation of palythene. PMID:16697653

  5. Toxic dinoflagellate Alexandrium tamarense induces oxidative stress and apoptosis in hepatopancreas of shrimp ( Fenneropenaeus chinensis)

    NASA Astrophysics Data System (ADS)

    Liang, Zhongxiu; Li, Jian; Li, Jitao; Tan, Zhijun; Ren, Hai; Zhao, Fazhen

    2014-12-01

    This study investigated the inductive effect of Alexandrium tamarense, a toxic dinoflagellate producing paralytic shellfish poison, on oxidative stress and apoptosis in hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The individuals of F. chinensis were exposed to 200 and 1000 cells mL-1 of A. tamarense with their superoxide dismutase (SOD), glutathione S-transferase (GST) activities, malonyldialdehyde (MDA) concentration, and caspase gene ( FcCasp) expression in hepatopancreas determined at 12, 24, 48, 72 and 96 h. In addition, apoptosis in hepatopancreas of F. chinensis at 96 h after exposure was determined through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. The hepatopancreatic SOD and GST activities of F. chinensis exposed to 1000 cells mL-1 of A. tamarense showed a bell-shaped response to exposure time. The hepatopancreatic MDA concentration of F. chinensis exposed to 1000 cells mL-1 of A. tamarense increased gradually from 48 to 96 h, and such a trend corresponded to the decrease of GST activity. The hepatopancreatic FcCasp transcript abundance of F. chinensis exposed to 1000 cells mL-1 of A. tamarense was positively and linearly correlated to MDA concentration. Results of TUNEL assay showed that exposure to 1000 cells mL-1 of A. tamarense induced apoptosis in the hepatopancreas of F. chinensis. Our study revealed that A. tamarense exposure influenced the antioxidative status of F. chinensis and caused lipid peroxidation and apoptosis in the hepatopancreas of shrimp.

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

    PubMed

    Erdner, Deana L; Richlen, Mindy; McCauley, Linda A R; Anderson, Donald M

    2011-01-01

    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. PMID:21829565

  7. Immunological and physiological responses of the periwinkle Littorina littorea during and after exposure to the toxic dinoflagellate Alexandrium minutum.

    PubMed

    Neves, Raquel A F; Figueiredo, Gisela M; Valentin, Jean Louis; da Silva Scardua, Patricia Mirella; Hégaret, Hélène

    2015-03-01

    Species of the dinoflagellate genus Alexandrium produce phycotoxins responsible for paralytic shellfish poisoning. Blooms of Alexandrium minutum reach very high concentrations of vegetative cells in the water column; and when these blooms occur, large numbers of toxic cysts can be produced and deposited on sediments becoming available to benthic species. The present study investigated the potential effect of exposure to toxic cysts of A. minutum on the periwinkle Littorinalittorea. Snails were exposed for nine days to pellicle cysts of toxic and non-toxic dinoflagellates, A. minutum and Heterocapsa triquetra, respectively, followed by six days of depuration while they were fed only H. triquetra. Toxin accumulation, condition index, immune and histopathological responses were analyzed. Histological alterations were also monitored in snails exposed to a harmful A. minutum bloom, which naturally occurred in the Bay of Brest. Snails exposed to toxic cysts showed abnormal behavior that seems to be toxin-induced and possibly related to muscle paralysis. Periwinkles accumulated toxins by preying on toxic cysts and accumulation appeared dependent on the time of exposure, increasing during intoxication period but tending to stabilize during depuration period. Toxic exposure also seemed to negatively affect hemocyte viability and functions, as ROS production and phagocytosis. Histological analyses revealed that toxic exposure induced damages on digestive organs of snails, both in laboratory and natural systems. This study demonstrates that an exposure to the toxic dinoflagellate A. minutum leads to sublethal effects on L. littorea, which may alter individual fitness and increase the susceptibility of snails to pathogens and diseases. PMID:25621399

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

    PubMed Central

    Zhang, Yong; Zhang, Shu-Fei; Lin, Lin; Wang, Da-Zhi

    2014-01-01

    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. PMID:25421324

  9. Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellate Alexandrium minutum in the Bay of Brest (France).

    PubMed

    Klouch, Khadidja Z; Schmidt, Sabine; Andrieux-Loyer, Françoise; Le Gac, Mickaël; Hervio-Heath, Dominique; Qui-Minet, Zujaila N; Quéré, Julien; Bigeard, Estelle; Guillou, Laure; Siano, Raffaele

    2016-07-01

    The multiannual dynamic of the cyst-forming and toxic marine dinoflagellate Alexandrium minutum was studied over a time scale of about 150 years by a paleoecological approach based on ancient DNA (aDNA) quantification and cyst revivification data obtained from two dated sediment cores of the Bay of Brest (Brittany, France). The first genetic traces of the species presence in the study area dated back to 1873 ± 6. Specific aDNA could be quantified by a newly developed real-time PCR assay in the upper core layers, in which the germination of the species (in up to 17-19-year-old sediments) was also obtained. In both cores studied, our quantitative paleogenetic data showed a statistically significant increasing trend in the abundance of A. minutum ITS1 rDNA copies over time, corroborating three decades of local plankton data that have documented an increasing trend in the species cell abundance. By comparison, paleogenetic data of the dinoflagellate Scrippsiella donghaienis did not show a coherent trend between the cores studied, supporting the hypothesis of the existence of a species-specific dynamic of A. minutum in the study area. This work contributes to the development of paleoecological research, further showing its potential for biogeographical, ecological and evolutionary studies on marine microbes. PMID:27162179

  10. Ichthyotoxicity studies of milkfish Chanos chanos fingerlings exposed to a harmful dinoflagellate Alexandrium minutum.

    PubMed

    Chen, C -Y.; Chou, H -N.

    2001-07-30

    Milkfish (Chanos chanos Forsskal) fingerlings were treated with toxic, nontoxic dinoflagellate Alexandrium minutum cells or toxic algal extract in the water medium without any aeration. Mortality of fish increased with increasing concentrations of toxic, nontoxic algal cells and water-soluble toxic algae extract. Milkfish fingerlings, which were exposed to toxic algae (1.5x10(4)-3.0x10(4) cells/ml) or algal extract [5.13x10(3)-2.05x10(4) cells/ml, 0.195 MU/10(4) cells (toxin concentration)] for 24 h, revealed by light microscopic observations a noticeable edema, hyperplasia and necrosis of secondary gill lamellae. The same toxicological symptom was observed in fish exposed to pure saxitoxin (STX) (6.475x10(-2) &mgr;g/ml) in the water medium. A higher critical oxygen pressure and oxygen consumption rate were also found in the milkfish fingerlings exposed to toxic algae extract (5.13x10(3)-2.05x10(4) cells/ml) and STX (6.475x10(-2) &mgr;g/ml). The cells of nontoxic A. minutum did not cause the gill damage to milkfish, and the extract of nontoxic algae did not cause an increase in oxygen consumption rate or critical oxygen demand of milkfish. From these results, we infer that toxic cells and its extract cause nonspecific response in gill tissues of milkfish. An instant increase in oxygen consumption rate and oxygen demand may be one of the major causes of fish death. PMID:11445088

  11. Dinomyces arenysensis gen. et sp. nov. (Rhizophydiales, Dinomycetaceae fam. nov.), a chytrid infecting marine dinoflagellates.

    PubMed

    Lepelletier, Frédéric; Karpov, Sergey A; Alacid, Elisabet; Le Panse, Sophie; Bigeard, Estelle; Garcés, Esther; Jeanthon, Christian; Guillou, Laure

    2014-03-01

    Environmental 18S rRNA gene surveys of microbial eukaryotes have recently revealed the diversity of major parasitic agents in pelagic freshwater systems, consisting primarily of chytrid fungi. To date, only a few studies have reported the presence of chydrids in the marine environment and a limited number of marine chytrids have been properly identified and characterized. Here, we report the isolation and cultivation of a marine chytrid from samples taken during a bloom of the toxic dinoflagellate Alexandrium minutum in the Arenys de Mar harbour (Mediterranean Sea, Spain). Cross-infections using cultures and natural phytoplankton communities revealed that this chytrid is only able to infect certain species of dinoflagellates, with a rather wide host range but with a relative preference for Alexandrium species. Phylogenetic analyses showed that it belongs to the order Rhizophydiales, but cannot be included in any of the existing families within this order. Several ultrastructural characters confirmed the placement of this taxon within the Rhizophydiales as well its novelty notably in terms of zoospore structure. This marine chytridial parasitoid is described as a new genus and species, Dinomyces arenysensis, within the Dinomycetaceae fam. nov. PMID:24709472

  12. Molecular analysis of complete ssu to lsu rdna sequence in the harmful dinoflagellate alexandrium tamarense (korean isolate, HY970328M)

    NASA Astrophysics Data System (ADS)

    Ki, Jang-Seu; Han, Myung-Soo

    2005-09-01

    New PCR primers (N=18) were designed for the isolation of complete SSU to LSU rDNA sequences from the dinoflagellate Alexandrium tamarense. Standard PCR, employing each primer set selected for amplifications of less than 1.5 kb, successfully amplified the expected rDNA regions of A. tamarense (Korean isolate, HY970328M). Complete SSU, LSU rDNAs and ITS sequences, including 5.8S rDNA, were recorded at 1,800 bp, 520 bp and 3,393 bp, respectively. The LSU rDNA sequence was the first report in Alexandrium genus. No intron was found in the LSU rRNA coding region. Twelve D-domains within the LSU rDNA were put together into 1,879 bp (44.4% G+C), and cores into 1514 bp (42.8% G+C). The core sequence was significantly different (0.0867 of genetic distance, 91% sequence similarity) in comparison with Prorocentrum micans (GenBank access. no. X16108). The D2 region was the longest in length (300 bp) and highly variable among the 12 D-domains. In a phylogenetic analysis using complete LSU rDNA sequences of a variety of phytoplankton, A tamarense was clearly separated with high resolution against other species. The result suggests that the sequence may resolve the taxonomic ambiguities of Alexandrium genus, particularly of the tamarensis complex.

  13. Ribosomal DNA organization patterns within the dinoflagellate genus Alexandrium as revealed by FISH: life cycle and evolutionary implications.

    PubMed

    Figueroa, Rosa Isabel; Cuadrado, Angeles; Stüken, Anke; Rodríguez, Francisco; Fraga, Santiago

    2014-05-01

    Dinoflagellates are a group of protists whose genome differs from that of other eukaryotes in terms of size (contains up to 250pg per haploid cell), base composition, chromosomal organization, and gene expression. But rDNA gene mapping of the active nucleolus in this unusual eukaryotic genome has not been carried out thus far. Here we used FISH in dinoflagellate species belonging to the genus Alexandrium (genome sizes ranging from 21 to 170 pg of DNA per haploid genome) to localize the sequences encoding the 18S, 5.8S, and 28S rRNA genes. The results can be summarized as follows: 1) Each dinoflagellate cell contains only one active nucleolus, with no hybridization signals outside it. However, the rDNA organization varies among species, from repetitive clusters forming discrete nuclear organizer regions (NORs) in some to specialized "ribosomal chromosomes" in other species. The latter chromosomes, never reported before in other eukaryotes, are mainly formed by rDNA genes and appeared in the species with the highest DNA content. 2) Dinoflagellate chromosomes are first characterized by several eukaryotic features, such as structural differentiation (centromere-like constrictions), size differences (dot chromosomes), and SAT (satellite) chromosomes. 3) NOR patterns prove to be useful in discriminating between cryptic species and life cycle stages in protists. PMID:24846057

  14. Enzymatic Permeabilization of the Thecate Dinoflagellate Alexandrium minutum (Dinophyceae) Yields Detection of Intracellularly Associated Bacteria via Catalyzed Reporter Deposition-Fluorescence In Situ Hybridization▿

    PubMed Central

    Palacios, Lucía; Marín, Irma

    2008-01-01

    The enzymatic permeabilization procedure described here allows the detection of intracellular bacteria in the thecate dinoflagellate Alexandrium minutum by using catalyzed reporter deposition-fluorescence in situ hybridization. The combined use of propidium iodide and calcofluor for confocal laser scanning microscopy, together with general and specific fluorescent bacterial probes, demonstrated the intracellular presence of bacteria, including members of the phylum Bacteroidetes. PMID:18263745

  15. Neurotoxins from Marine Dinoflagellates: A Brief Review

    PubMed Central

    Wang, Da-Zhi

    2008-01-01

    Dinoflagellates are not only important marine primary producers and grazers, but also the major causative agents of harmful algal blooms. It has been reported that many dinoflagellate species can produce various natural toxins. These toxins can be extremely toxic and many of them are effective at far lower dosages than conventional chemical agents. Consumption of seafood contaminated by algal toxins results in various seafood poisoning syndromes: paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), amnesic shellfish poisoning (ASP), diarrheic shellfish poisoning (DSP), ciguatera fish poisoning (CFP) and azaspiracid shellfish poisoning (ASP). Most of these poisonings are caused by neurotoxins which present themselves with highly specific effects on the nervous system of animals, including humans, by interfering with nerve impulse transmission. Neurotoxins are a varied group of compounds, both chemically and pharmacologically. They vary in both chemical structure and mechanism of action, and produce very distinct biological effects, which provides a potential application of these toxins in pharmacology and toxicology. This review summarizes the origin, structure and clinical symptoms of PSP, NSP, CFP, AZP, yessotoxin and palytoxin produced by marine dinoflagellates, as well as their molecular mechanisms of action on voltage-gated ion channels. PMID:18728731

  16. Relationship of proteomic variation and toxin synthesis in the dinoflagellate Alexandrium tamarense CI01 under phosphorus and inorganic nitrogen limitation.

    PubMed

    Jiang, Xi-Wen; Wang, Jing; Gao, Yue; Chan, Leo Lai; Lam, Paul Kwan Sing; Gu, Ji-Dong

    2015-10-01

    Paralytic shellfish toxins (PSTs) are originated from cyanobacteria and dinoflagellates, including Alexandrium tamarense, the common dinoflagellate species. In this study, a toxic dinoflagellate strain of A. tamarense CI01 was selected for studying the PSTs' concentration and the related protein variation during the whole cell cycle under different nutrient conditions. High-performance liquid chromatography, 2-D DIGE and Western blotting were used collectively for protein profiling and identification. Results showed that the toxin content was suppressed under nitrogen limiting condition, but enhanced in phosphorous limiting medium. Based on the results of proteomics analysis, 7 proteins were discovered to be related to the PSTs biosynthesis of A. tamarense CI01, including S-adenosylhomocysteine hydrolase, ornithine cyclodeaminase, argininosuccinate synthase, methyluridine methyltransferase cystine ABC transporter, phosphoserine phosphatase, argininosuccinate synthase and acyl-CoA dehydrogenase, which corresponds to the metabolism of the methionine, cysteine, ornithine, arginine and proline. Moreover, some photosynthesis relating proteins also increased their expression during PST synthesis period in A. tamarense CI01, such as phosphoenolpyruvate carboxylase, chloroplast phosphoglycerate kinase, peridinin-chlorophyll α-binding protein, Mg(2+) transporter protein and chloroplast phosphoglycerate kinase. The above findings are in support of our hypothesis that these proteins are involved in toxin biosynthesis of A. tamarense CI01, but cause-and-effect mechanisms need to be investigated in further studies. PMID:26239440

  17. Competition among Dinoflagellate Alexandrium tamarense, raphidophyte Heterosigma carterae and diatom Skeletonema costatum under combinations of two temperatures and five salinities

    NASA Astrophysics Data System (ADS)

    Yan, Tian; Zhou, Mingjiang; Qian, Peiyuan

    2003-09-01

    Competition among HAB (Harmful Algal Bloom) species Dinoflagellate Alexandrium tamarense, Raphidophyte Heterosigma carterae, and Diatom Skeletonema costatum was studied in the laboratory. Experiments with these three major HAB species under combinations of different salinities (10, 18, 25, 30, 35) and temperatures (19°C, 25°C) were carried out. The results showed that S. costatum successfully competed with the other two species at salinities of 18, 25, 30, and 35 at temperatures of 19°C and 25°C. However, H. carterae showed its advantage at low salinity of 10 and became the single dominant species at salinity 10 and 25°C. A. tamarense could not compete successfully with the other two species especially at low salinities. However, it could remain at low density in the presence of higher densities of other algae.

  18. Environmental Factors and Seasonal Occurrence of the Dinoflagellate Alexandrium minutum, a PSP Potential Producer, in a Mediterranean Lagoon

    NASA Astrophysics Data System (ADS)

    Giacobbe, M. G.; Oliva, F. D.; Maimone, G.

    1996-05-01

    Seasonal fluctuations of hydrobiological parameters were studied, throughout 1992, in a shallow Mediterranean area (Ganzirri lagoon), affected by the dinoflagellate Alexandrium minutum, a potential producer of saxitoxins. Concentrations of dissolved inorganic nitrogen (DIN) and N:P ratios were high in autumn and winter, when the waters were well mixed and free from A. minutumcells. The spring appearance of this species coincided with enhanced rainfall and freshwater runoff and with stabilization of the water column, whereas cell dispersion was observed in summer. Although A. minutumnever dominated the algal community, cell densities were maximal in May, when values of salinity did not exceed 30; during this month, there were reduced amounts of DIN, N:P atomic ratios close to 16:1 and a minor competitive pressure by other phytoplankters. Subsequent increases in values of the above parameters—in particular, of the ammonium nitrogen—were associated with a decline in cell numbers, and final disappearance of A. minutumcells.

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

    PubMed Central

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

    2011-01-01

    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. 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. PMID:22308102

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

    PubMed

    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. PMID:17465118

  1. Marine dinoflagellates show induced life-history shifts to escape parasite infection in response to water-borne signals.

    PubMed

    Toth, Gunilla B; Norén, Fredrik; Selander, Erik; Pavia, Henrik

    2004-04-01

    Many dinoflagellate species form dormant resting cysts as a part of their life cycle, and in some freshwater species, hatching of these cysts can be delayed by the presence of water-borne signals from grazing zooplankton. Some marine dinoflagellates can form temporary cysts, which may function to resist unfavourable short-term environmental conditions. We investigated whether the marine dinoflagellate Alexandrium ostenfeldii is able to induce an increased resistance to the parasitic flagellate Parvilucifera infectans by forming temporary cysts. We performed several laboratory experiments where dinoflagellates were exposed either to direct contact with parasites or to filtered water from cultures of parasite-infected conspecifics (parasite-derived signals). Infection by P. infectans is lethal to motile A. ostenfeldii cells, but temporary cysts were more resistant to parasite infection. Furthermore, A. ostenfeldii induced a shift in life-history stage (from motile cells to temporary cysts) when exposed to parasite-derived water-borne signals. The response was relaxed within a couple of hours, indicating that A. ostenfeldii may use this behaviour as a short-term escape mechanism to avoid parasite infection. The results suggest that intraspecies chemical communication evoked by biotic interactions can be an important mechanism controlling life-history shifts in marine dinoflagellates, which may have implications for the development of toxic algal blooms. PMID:15209107

  2. Divinyl chlorophyll a in the marine eukaryotic protist Alexandrium ostenfeldii (Dinophyceae).

    PubMed

    Rodríguez, Francisco; Garrido, José Luis; Sobrino, Cristina; Johnsen, Geir; Riobó, Pilar; Franco, José; Aamot, Inga; Ramilo, Isabel; Sanz, Noelia; Kremp, Anke

    2016-02-01

    Here it is reported the first detection of DV-chl a together with the usual chl a in the marine dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Growth response and photosynthetic parameters were examined at two irradiances (80 and 240 μmol photons m(-2) s(-1)) and temperatures (15 °C and 19 °C) in a divinylic strain (AOTV-OS20) versus a monovinylic one (AOTV-OS16), using in vivo chl a fluorescence kinetics of PSII to characterize photosynthetic parameters by pulse amplitude modulated fluorescence, (14)C assimilation rates and toxin analyses. The divinylic isolate exhibited slower growth and stronger sensitivity to high irradiance than normal chl a strain. DV-chl a : chl a ratios decreased along time (from 11.3 to < 0.5 after 10 months) and to restore them sub-cloning and selection of strains with highest DV-chl a content was required. A mutation and/or epigenetic changes in the expression of divinyl reductase gene/s in A. ostenfeldii may explain this altered pigment composition. Despite quite severe limitations (reduced fitness and gradual loss of DV-chl a content), the DV-chl a-containing line in A. ostenfeldii could provide a model organism in photosynthetic studies related with chl biosynthesis and evolution. PMID:26337730

  3. Application of rRNA probes and fluorescence in situ hybridization for rapid detection of the toxic dinoflagellate Alexandrium minutum

    NASA Astrophysics Data System (ADS)

    Tang, Xianghai; Yu, Rencheng; Zhou, Mingjiang; Yu, Zhigang

    2012-03-01

    The dinoflagellate Alexandrium minutum is often associated with harmful algal blooms (HABs). This species consists of many strains that differ in their ability to produce toxins but have similar morphology, making identification difficult. In this study, species-specific rRNA probes were designed for whole-cell fluorescence in situ hybridization (FISH) to distinguish A. minutum from two phylogenetic clades. We acquired the complete SSU to LSU rDNA sequences (GenBank accession numbers JF906989-JF906999) of 11 Alexandrium strains and used these to design rRNA targeted oligonucleotide probes. Three ribotype-specific probes, M-GC-1, M-PC-2, and M-PC-3, were designed. The former is specific for the GC clade ("Global clade") of A. minutum, the majority of which have been found non-toxic, and the latter two are specific for the PSP (paralytic shellfish poisoning)-producing PC clade ("Pacific clade"). The specificity of these three probes was confirmed by FISH. All cells in observed fields of view were fluorescently labeled when probes and target species were incubated under optimized FISH conditions. However, the accessibility of rRNA molecules in ribosomes varied among the probe binding positions. Thus, there was variation in the distribution of positive signals in labeled cells within nucleolus and cytosol (M-GC-1, M-PC-3), or just nucleolus (M-PC-2). Our results provide a methodological basis for studying the biogeography and population dynamics of A. minutum, and providing an early warning of toxic HABs.

  4. On an extremely dense bloom of the dinoflagellate Alexandrium tamarense in lagoons of the PO river delta: Impact on the environment

    NASA Astrophysics Data System (ADS)

    Sorokin, Yu. I.; Sorokin, P. Yu.; Ravagnan, G.

    1996-06-01

    An extremely dense bloom of the potentially toxic dinoflagellate Alexandrium tamarense was observed in the lagoons of Cà Pisani (Veneto, Italy) in summer 1993. The lagoons were experiencing a significant eutrophication impact, receiving waste waters from intensive fish culture plants. During their bloom dinoflagellates in the lagoons reached densities of 2 to 4 × 10 6 cells·dm -3 and a biomass of over 100 g·m -3. The bloom produced drastic ecological changes in the lagoons. It caused nocturnal anoxia, mortality of macrophytes and the build-up of labile organic matter in the water column. Grazing by the tintinnid Favella sp. contributed to the termination of the bloom of the flagellates. The results show that coastal aqua culture probably stimulates dinoflagellate blooms in shallow brackish lagoons.

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

    PubMed Central

    Lei, Xueqian; Li, Dong; Li, Yi; Chen, Zhangran; Chen, Yao; Cai, Guanjing; Yang, Xujun; Zheng, Wei; Zheng, Tianling

    2015-01-01

    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. PMID:25667582

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

    PubMed

    Lei, Xueqian; Li, Dong; Li, Yi; Chen, Zhangran; Chen, Yao; Cai, Guanjing; Yang, Xujun; Zheng, Wei; Zheng, Tianling

    2015-01-01

    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. PMID:25667582

  7. Transcriptome de novo assembly sequencing and analysis of the toxic dinoflagellate Alexandrium catenella using the Illumina platform.

    PubMed

    Zhang, Shu; Sui, Zhenghong; Chang, Lianpeng; Kang, Kyoungho; Ma, Jinhua; Kong, Fanna; Zhou, Wei; Wang, Jinguo; Guo, Liliang; Geng, Huili; Zhong, Jie; Ma, Qingxia

    2014-03-10

    In this article, high-throughput de novo transcriptomic sequencing was performed in Alexandrium catenella, which provided the first view of the gene repertoire in this dinoflagellate based on next-generation sequencing (NGS) technologies. A total of 118,304 unigenes were identified with an average length of 673bp (base pair). Of these unigenes, 77,936 (65.9%) were annotated with known proteins based on sequence similarities, among which 24,149 and 22,956 unigenes were assigned to gene ontology categories (GO) and clusters of orthologous groups (COGs), respectively. Furthermore, 16,467 unigenes were mapped onto 322 pathways using the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG). We also detected 1143 simple sequence repeats (SSRs), in which the tri-nucleotide repeat motif (69.3%) was the most abundant. The genetic facts and significance derived from the transcriptome dataset were suggested and discussed. All four core nucleosomal histones and linker histones were detected, in addition to the unigenes involved in histone modifications.190 unigenes were identified as being involved in the endocytosis pathway, and clathrin-dependent endocytosis was suggested to play a role in the heterotrophy of A. catenella. A conserved 22-nt spliced leader (SL) was identified in 21 unigenes which suggested the existence of trans-splicing processing of mRNA in A. catenella. PMID:24440238

  8. [Seasonal dynamics of genus Alexandrium (potentially toxic dinoflagellate) in the lagoon of Bizerte (North of Tunisia) and controls by the abiotic factors].

    PubMed

    Bouchouicha Smida, Donia; Sahraoui, Inès; Mabrouk, Hassine Hadj; Sakka Hlaili, Asma

    2012-06-01

    Some species of the genus Alexandrium are known as potential producers of saxitoxin, a neurotoxin that causes the paralytic shellfish poisoning (PSP) syndrome. Blooming of these species, especially in shellfish farms can affect the aquaculture production and harm human health. Seasonal dynamics of Alexandrium spp. abundance in relationship to environmental factors was investigated from November 2007 to February 2009 at six stations in the Bizerte lagoon, an important shellfish farming area situated in SW Mediterranean. The sampling stations represented different hydrological and trophic conditions: one station TJ (Tinja) is affected by the river plume; two stations (Chaara [Ch] and Canal [Ca]) are influenced by marine inflow (particularly in summer), industrial and urban effluents; and the three other stations (Menzel Abdelrahmen [MA], Menzel Jemil [MJ] and Douaouda [Do]) are located close to shellfish farms. Cell abundance of Alexandrium spp. varied among stations and months. Species of this genus showed a sporadic appearance, but they reached high concentration (0.67-7 × 10(5)cells L(-1)). Maximal cell density was detected in autumn (November 2007; station MA), at salinity of 37.5, temperature of 16 °C and NH(4)(+) level of 55.45 μM. During this month, Alexandrium spp. abundance accounted for a large fraction (61%) of the harmful phytoplankton. The statistical analysis revealed that Alexandrium concentrations were positively correlated with N:P ratio and NH4+ levels. Thus, the eutrophic waters of the lagoon favour the growth of Alexandrium, which seemed to have preference for N-nutrient loading from antrophogenic activities, as ammonium. Blooms of these potential harmful algae may constitute a potential threat in this coastal lagoon of the southern Mediterranean. Consequently, it is necessary to be well vigilant and to do regular monitoring of Alexandrium species. PMID:22721562

  9. Population genetic structure and connectivity of the harmful dinoflagellate Alexandrium minutum in the Mediterranean Sea

    PubMed Central

    Casabianca, Silvia; Penna, Antonella; Pecchioli, Elena; Jordi, Antoni; Basterretxea, Gotzon; Vernesi, Cristiano

    2012-01-01

    The toxin-producing microbial species Alexandrium minutum has a wide distribution in the Mediterranean Sea and causes high biomass blooms with consequences on the environment, human health and coastal-related economic activities. Comprehension of algal genetic differences and associated connectivity is fundamental to understand the geographical scale of adaptation and dispersal pathways of harmful microalgal species. In the present study, we combine A. minutum population genetic analyses based on microsatellites with indirect connectivity (Ci) estimations derived from a general circulation model of the Mediterranean sea. Our results show that four major clusters of genetically homogeneous groups can be identified, loosely corresponding to four regional seas: Adriatic, Ionian, Tyrrhenian and Catalan. Each of the four clusters included a small fraction of mixed and allochthonous genotypes from other Mediterranean areas, but the assignment to one of the four clusters was sufficiently robust as proved by the high ancestry coefficient values displayed by most of the individuals (>84%). The population structure of A. minutum on this scale can be explained by microalgal dispersion following the main regional circulation patterns over successive generations. We hypothesize that limited connectivity among the A. minutum populations results in low gene flow but not in the erosion of variability within the population, as indicated by the high gene diversity values. This study represents a first and new integrated approach, combining both genetic and numerical methods, to characterize and interpret the population structure of a toxic microalgal species. This approach of characterizing genetic population structure and connectivity at a regional scale holds promise for the control and management of the harmful algal bloom events in the Mediterranean Sea. PMID:21593032

  10. Life history, excystment features, and growth characteristics of the Mediterranean harmful dinoflagellate Alexandrium pseudogonyaulax.

    PubMed

    Zmerli Triki, Habiba; Laabir, Mohamed; Kéfi Daly-Yahia, Ons

    2015-10-01

    Studies considering the biology and ecology of the toxic bloom-forming species, Alexandrium pseudogonyaulax, are rare. Our results highlight five features not described before in A. pseudogonyaulax life cycle: (i) A. pseudogonyaulax gametes showed two modes of conjugation, anisogamy and isogamy, (ii) sexual conjugation occurs either in the dark or in the light phase by engulfment or a fusion process, (iii) the presence of planozygote and newly formed cysts in monoclonal culture suggests homothallism, (iv) newly formed cysts have very dark vesicular content and are mostly unparatabulated when observed under light microscope and (v) natural resting cysts are able to give either a planomeiocyte or two vegetative cells. Cyst viability was enhanced after 5 months of cold storage (4°C), with excystment rate reaching 97% after 3 d of incubation. Excystment rate was highest (43%-79%) in Enriched Natural Sea Water diluted culture medium, whereas few germling cells were able to survive without the culture medium (0%-13%). Salinity-irradiance experiments revealed that the highest cell concentrations occur at high irradiances for all the tested salinities. Vegetative growth rates generally increased with increasing irradiance, and were less dependent on salinity variations. The relatively low growth rate, low cell densities in the laboratory, and the notable capacity of producing cysts along growth phases of A. pseudogonyaulax could explain the occurrence of high resting cysts densities in the sediment of Bizerte lagoon and the relatively low abundances of vegetative cells in the water column. PMID:26986892

  11. Population genetic structure and connectivity of the harmful dinoflagellate Alexandrium minutum in the Mediterranean Sea.

    PubMed

    Casabianca, Silvia; Penna, Antonella; Pecchioli, Elena; Jordi, Antoni; Basterretxea, Gotzon; Vernesi, Cristiano

    2012-01-01

    The toxin-producing microbial species Alexandrium minutum has a wide distribution in the Mediterranean Sea and causes high biomass blooms with consequences on the environment, human health and coastal-related economic activities. Comprehension of algal genetic differences and associated connectivity is fundamental to understand the geographical scale of adaptation and dispersal pathways of harmful microalgal species. In the present study, we combine A. minutum population genetic analyses based on microsatellites with indirect connectivity (C(i)) estimations derived from a general circulation model of the Mediterranean sea. Our results show that four major clusters of genetically homogeneous groups can be identified, loosely corresponding to four regional seas: Adriatic, Ionian, Tyrrhenian and Catalan. Each of the four clusters included a small fraction of mixed and allochthonous genotypes from other Mediterranean areas, but the assignment to one of the four clusters was sufficiently robust as proved by the high ancestry coefficient values displayed by most of the individuals (>84%). The population structure of A. minutum on this scale can be explained by microalgal dispersion following the main regional circulation patterns over successive generations. We hypothesize that limited connectivity among the A. minutum populations results in low gene flow but not in the erosion of variability within the population, as indicated by the high gene diversity values. This study represents a first and new integrated approach, combining both genetic and numerical methods, to characterize and interpret the population structure of a toxic microalgal species. This approach of characterizing genetic population structure and connectivity at a regional scale holds promise for the control and management of the harmful algal bloom events in the Mediterranean Sea. PMID:21593032

  12. Strategies of marine dinoflagellate survival and some rules of assembly

    NASA Astrophysics Data System (ADS)

    Smayda, Theodore J.; Reynolds, Colin S.

    2003-03-01

    Dinoflagellate ecology is based on multiple adaptive strategies and species having diverse habitat preferences. Nine types of mixing-irradiance-nutrient habitats selecting for specific marine dinoflagellate life-form types are recognised, with five rules of assembly proposed to govern bloom-species selection and community organisation within these habitats. Assembly is moulded around an abiotic template of light energy, nutrient supply and physical mixing in permutative combinations. Species selected will have one of three basic ( C-, S-, R-) strategies: colonist species ( C-) which predominate in chemically disturbed habitats; nutrient stress tolerant species ( S-), and species ( R-) tolerant of shear/stress forces in physically disturbed water masses. This organisational plan of three major habitat variables and three major adaptive strategies is termed the 3-3 plan. The bloom behaviour and habitat specialisation of dinoflagellates and diatoms are compared. Dinoflagellates behave as annual species, bloom soloists, are ecophysiologically diverse, and habitat specialists whose blooms tend to be monospecific. Diatoms behave as perennial species, guild members, are habitat cosmopolites, have a relatively uniform bloom strategy based on species-rich pools and exhibit limited habitat specialisation. Dinoflagellate bloom-species selection follows a taxonomic hierarchical pathway which progresses from phylogenetic to generic to species selection, and in that sequence. Each hierarchical taxonomic level has its own adaptive requirements subject to rules of assembly. Dinoflagellates would appear to be well suited to exploit marine habitats and to be competitive with other phylogenetic groups, yet fail to do so.

  13. Identification and Characterization of Three Differentially Expressed Genes, Encoding S-Adenosylhomocysteine Hydrolase, Methionine Aminopeptidase, and a Histone-Like Protein, in the Toxic Dinoflagellate Alexandrium fundyense†

    PubMed Central

    Taroncher-Oldenburg, Gaspar; Anderson, Donald M.

    2000-01-01

    Genes showing differential expression related to the early G1 phase of the cell cycle during synchronized circadian growth of the toxic dinoflagellate Alexandrium fundyense were identified and characterized by differential display (DD). The determination in our previous work that toxin production in Alexandrium is relegated to a narrow time frame in early G1 led to the hypothesis that transcriptionally up- or downregulated genes during this subphase of the cell cycle might be related to toxin biosynthesis. Three genes, encoding S-adenosylhomocysteine hydrolase (Sahh), methionine aminopeptidase (Map), and a histone-like protein (HAf), were isolated. Sahh was downregulated, while Map and HAf were upregulated, during the early G1 phase of the cell cycle. Sahh and Map encoded amino acid sequences with about 90 and 70% similarity to those encoded by several eukaryotic and prokaryotic Sahh and Map genes, respectively. The partial Map sequence also contained three cobalt binding motifs characteristic of all Map genes. HAf encoded an amino acid sequence with 60% similarity to those of two histone-like proteins from the dinoflagellate Crypthecodinium cohnii Biecheler. This study documents the potential of applying DD to the identification of genes that are related to physiological processes or cell cycle events in phytoplankton under conditions where small sample volumes represent an experimental constraint. The identification of an additional 21 genes with various cell cycle-related DD patterns also provides evidence for the importance of pretranslational or transcriptional regulation in dinoflagellates, contrary to previous reports suggesting the possibility that translational mechanisms are the primary means of circadian regulation in this group of organisms. PMID:10788388

  14. First Evidence of Altererythrobacter sp. LY02 with Indirect Algicidal Activity on the Toxic Dinoflagellate, Alexandrium tamarense.

    PubMed

    Li, Yi; Liu, Lei; Xu, Yanting; Guan, Chengwei; Lei, Xueqian; Zheng, Wei; Wang, Hailei; Zheng, Tianling

    2016-10-01

    Alexandrium tamarense is a toxic harmful algal blooms (HABs) causing species, which poses great threat to human health and marine economy. In this study, we isolated an algicidal bacterium Altererythrobacter sp. LY02 towards to A. tamarense and later investigated the algicidal activity, algicidal mode, characteristics of algicidal active substance and algicidal procedure. The results indicated that the cell-free filtrate of strain LY02 showed high algicidal effect on algal growth, however, bacterial cells almost lost algicidal activity. The algicidal active substance was temperature- and pH-stability, and its molecular weight was less than 1000 Da, and was a non-proteinaceous material or non-polysaccharide, mid-polar substance. Under the algicidal effect of active substance, the morphology and structure of A. tamarense cells were seriously damaged as well as organelles. Our study confirmed that the algicidal active substance could be used as an excellent bio-agent for controlling HABs caused by A. tamarense. PMID:27422436

  15. EFFECT OF FLUID SHEAR AND IRRADIANCE ON POPULATION GROWTH AND CELLULAR TOXIN CONTENT OF THE DINOFLAGELLATE ALEXANDRIUM FUNDYENSE.

    EPA Science Inventory

    The potential for in situ turbulence to inhibit dinoflagellate population growth has been demonstrated by experimentally exposing dinoflagellate cultures to quantified shear flow. However, despite interest in understanding environmental factors that affect the growth of toxic din...

  16. No evidence for induction or selection of mutant sodium channel expression in the copepod Acartia husdsonica challenged with the toxic dinoflagellate Alexandrium fundyense

    PubMed Central

    Finiguerra, Michael; Avery, David E; Dam, Hans G

    2014-01-01

    Some species in the dinoflagellate genus Alexandrium spp. produce a suite of neurotoxins that block sodium channels, known as paralytic shellfish toxins (PST), which have deleterious effects on grazers. Populations of the ubiquitous copepod grazer Acartia hudsonica that have co-occurred with toxic Alexandrium spp. are better adapted than naïve populations. The mechanism of adaptation is currently unknown. We hypothesized that a mutation in the sodium channel could account for the grazer adaptation. We tested two hypotheses: (1) Expression of the mutant sodium channel could be induced by exposure to toxic Alexandrium fundyense; (2) in the absence of induction, selection exerted by toxic A. fundyense would favor copepods that predominantly express the mutant isoform. In the copepod A. hudsonica, both isoforms are expressed in all individuals in varying proportions. Thus, in addition to comparing expression ratios of wild-type to mutant isoforms for individual copepods, we also partitioned copepods into three groups: those that predominantly express the mutant (PMI) isoform, the wild-type (PWI) isoform, or both isoforms approximately equally (EI). There were no differences in isoform expression between individuals that were fed toxic and nontoxic food after three and 6 days; induction of mutant isoform expression did not occur. Furthermore, the hypothesis that mutant isoform expression responds to toxic food was also rejected. That is, no consistent evidence showed that the wild-type to mutant isoform ratios decreased, or that the relative proportion of PMI individuals increased, due to the consumption of toxic food over four generations. However, in the selected line that was continuously exposed to toxic food sources, egg production rate increased, which suggested that adaptation occurred but was unrelated to sodium channel isoform expression. PMID:25535562

  17. Biosynthesis and Molecular Genetics of Polyketides in Marine Dinoflagellates

    PubMed Central

    Kellmann, Ralf; Stüken, Anke; Orr, Russell J. S.; Svendsen, Helene M.; Jakobsen, Kjetill S.

    2010-01-01

    Marine dinoflagellates are the single most important group of algae that produce toxins, which have a global impact on human activities. The toxins are chemically diverse, and include macrolides, cyclic polyethers, spirolides and purine alkaloids. Whereas there is a multitude of studies describing the pharmacology of these toxins, there is limited or no knowledge regarding the biochemistry and molecular genetics involved in their biosynthesis. Recently, however, exciting advances have been made. Expressed sequence tag sequencing studies have revealed important insights into the transcriptomes of dinoflagellates, whereas other studies have implicated polyketide synthase genes in the biosynthesis of cyclic polyether toxins, and the molecular genetic basis for the biosynthesis of paralytic shellfish toxins has been elucidated in cyanobacteria. This review summarises the recent progress that has been made regarding the unusual genomes of dinoflagellates, the biosynthesis and molecular genetics of dinoflagellate toxins. In addition, the evolution of these metabolic pathways will be discussed, and an outlook for future research and possible applications is provided. PMID:20479965

  18. Identification of microRNAs in the Toxigenic Dinoflagellate Alexandrium catenella by High-Throughput Illumina Sequencing and Bioinformatic Analysis

    PubMed Central

    Geng, Huili; Sui, Zhenghong; Zhang, Shu; Du, Qingwei; Ren, Yuanyuan; Liu, Yuan; Kong, Fanna; Zhong, Jie; Ma, Qingxia

    2015-01-01

    Micro-ribonucleic acids (miRNAs) are a large group of endogenous, tiny, non-coding RNAs consisting of 19–25 nucleotides that regulate gene expression at either the transcriptional or post-transcriptional level by mediating gene silencing in eukaryotes. They are considered to be important regulators that affect growth, development, and response to various stresses in plants. Alexandrium catenella is an important marine toxic phytoplankton species that can cause harmful algal blooms (HABs). To date, identification and function analysis of miRNAs in A. catenella remain largely unexamined. In this study, high-throughput sequencing was performed on A. catenella to identify and quantitatively profile the repertoire of small RNAs from two different growth phases. A total of 38,092,056 and 32,969,156 raw reads were obtained from the two small RNA libraries, respectively. In total, 88 mature miRNAs belonging to 32 miRNA families were identified. Significant differences were found in the member number, expression level of various families, and expression abundance of each member within a family. A total of 15 potentially novel miRNAs were identified. Comparative profiling showed that 12 known miRNAs exhibited differential expression between the lag phase and the logarithmic phase. Real-time quantitative RT-PCR (qPCR) was performed to confirm the expression of two differentially expressed miRNAs that were one up-regulated novel miRNA (aca-miR-3p-456915), and one down-regulated conserved miRNA (tae-miR159a). The expression trend of the qPCR assay was generally consistent with the deep sequencing result. Target predictions of the 12 differentially expressed miRNAs resulted in 1813target genes. Gene ontology (GO) analysis and the Kyoto Encyclopedia of Genes and Genomes pathway database (KEGG) annotations revealed that some miRNAs were associated with growth and developmental processes of the alga. These results provide insights into the roles that miRNAs play in the growth of

  19. Dinoflagellate cysts in recent marine sediments from Thermaikos Gulf, Greece: Effects of resuspension events on vertical cyst distribution

    NASA Astrophysics Data System (ADS)

    Giannakourou, A.; Orlova, T. Y.; Assimakopoulou, G.; Pagou, K.

    2005-12-01

    A qualitative and semi-quantitative study of recent dinoflagellate cysts has been undertaken in the NW part of Aegean Sea, Thermaikos Gulf (Eastern Mediteranean), before (September 2001), during (October 2001) and after 120 days (February 2002) of intensive trawling activities. This is the first survey of recent dinoflagellate cysts from Greek marine coastal environments. Sediment samples were collected with a corer and the vertical distribution of the cysts was studied at five different layers, from 0 to 10 cm. Dinoflagellate cysts were both abundant and diverse. Cysts were found over the whole sampling area and periods, with concentrations ranging between 247-3202 cysts cm -3. Thirty-six cyst types were encountered, of which 32 were identified to species level, representing 12 genera. It seems that significant local resuspension, related to the onset of the trawling period and stirring up of the sediment, contributed to mixing of the upper layers, resulting to more homogenous cyst profiles in the sediment. Viable cysts constituted 16-60% of the total cyst abundance. The abundance peaks of viable cysts within the subsurface sediment layers, observed during the undisturbed period, disappeared during October. In February, the reduction of cyst concentration was associated to a loss of viable cysts, whilst the ratio of viable/empty cysts ranged between 0.30 and 0.67. The abundance of the different dinoflagellate species, in their active form, was monitored in order to detect any relationship between the concentration of cysts in the top 10 cm of sediment and blooms of algae in the water column. Cysts of potentially toxic species, causing Paralitic Shellfish Poisoning (PSP), such as Alexandrium cf. tamarense, A. cf. affine, A. cf. minutum, as well as Gymnodinium catenatum, were detected in the cyst survey.

  20. Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions.

    PubMed

    Lassudrie, Malwenn; Soudant, Philippe; Nicolas, Jean-Louis; Miner, Philippe; Le Grand, Jacqueline; Lambert, Christophe; Le Goïc, Nelly; Hégaret, Hélène; Fabioux, Caroline

    2016-04-01

    The Pacific oyster Crassostrea gigas is an important commercial species cultured throughout the world. Oyster production practices often include transfers of animals into new environments that can be stressful, especially at young ages. This study was undertaken to determine if a toxic Alexandrium bloom, occurring repeatedly in French oyster beds, could modulate juvenile oyster cellular immune responses (i.e. hemocyte variables). We simulated planting on commercial beds by conducting a cohabitation exposure of juvenile, "specific pathogen-free" (SPF) oysters (naïve from the environment) with previously field-exposed oysters to induce interactions with new microorganisms. Indeed, toxic Alexandrium spp. exposures have been reported to modulate bivalve interaction with specific pathogens, as well as physiological and immunological variables in bivalves. In summary, SPF oysters were subjected to an artificial bloom of Alexandrium catenella, simultaneously with a cohabitation challenge. Exposure to A. catenella, and thus to the paralytic shellfish toxins (PSTs) and extracellular bioactive compounds produced by this alga, induced higher concentration, size, complexity and reactive oxygen species (ROS) production of circulating hemocytes. Challenge by cohabitation with field-exposed oysters also activated these hemocyte responses, suggesting a defense response to new microorganism exposure. These hemocyte responses to cohabitation challenge, however, were partially inhibited by A. catenella exposure, which enhanced hemocyte mortality, suggesting either detrimental effects of the interaction of both stressors on immune capacity, or the implementation of an alternative immune strategy through apoptosis. Indeed, no infection with specific pathogens (herpesvirus OsHV-1 or Vibrio aesturianus) was detected. Additionally, lower PST accumulation in challenged oysters suggests a physiological impairment through alteration of feeding-related processes. Overall, results of this

  1. Recent radiation in a marine and freshwater dinoflagellate species flock.

    PubMed

    Annenkova, Nataliia V; Hansen, Gert; Moestrup, Øjvind; Rengefors, Karin

    2015-08-01

    Processes of rapid radiation among unicellular eukaryotes are much less studied than among multicellular organisms. We have investigated a lineage of cold-water microeukaryotes (protists) that appear to have diverged recently. This lineage stands in stark contrast to known examples of phylogenetically closely related protists, in which genetic difference is typically larger than morphological differences. We found that the group not only consists of the marine-brackish dinoflagellate species Scrippsiella hangoei and the freshwater species Peridinium aciculiferum as discovered previously but also of a whole species flock. The additional species include Peridinium euryceps and Peridinium baicalense, which are restricted to a few lakes, in particular to the ancient Lake Baikal, Russia, and freshwater S. hangoei from Lake Baikal. These species are characterized by relatively large conspicuous morphological differences, which have given rise to the different species descriptions. However, our scanning electron microscopic studies indicate that they belong to a single genus according to traditional morphological characterization of dinoflagellates (thecal plate patterns). Moreover, we found that they have identical SSU (small subunit) rDNA fragments and distinct but very small differences in the DNA markers LSU (large subunit) rDNA, ITS2 (internal transcribed spacer 2) and COB (cytochrome b) gene, which are used to delineate dinoflagellates species. As some of the species co-occur, and all four have small but species-specific sequence differences, we suggest that these taxa are not a case of phenotypic plasticity but originated via recent adaptive radiation. We propose that this is the first clear example among free-living microeukaryotes of recent rapid diversification into several species followed by dispersion to environments with different ecological conditions. PMID:25603395

  2. Rapid detection and quantification of the marine toxic algae, Alexandrium minutum, using a super-paramagnetic immunochromatographic strip test.

    PubMed

    Gas, Fabienne; Baus, Béatrice; Queré, Julien; Chapelle, Annie; Dreanno, Catherine

    2016-01-15

    The dinoflagellates of Alexandrium genus are known to be producers of paralytic shellfish toxins that regularly impact the shellfish aquaculture industry and fisheries. Accurate detection of Alexandrium including Alexandrium minutum is crucial for environmental monitoring and sanitary issues. In this study, we firstly developed a quantitative lateral flow immunoassay (LFIA) using super-paramagnetic nanobeads for A. minutum whole cells. This dipstick assay relies on two distinct monoclonal antibodies used in a sandwich format and directed against surface antigens of this organism. No sample preparation is required. Either frozen or live cells can be detected and quantified. The specificity and sensitivity are assessed by using phytoplankton culture and field samples spiked with a known amount of cultured A. minutum cells. This LFIA is shown to be highly specific for A. minutum and able to detect reproducibly 10(5)cells/L within 30min. The test is applied to environmental samples already characterized by light microscopy counting. No significant difference is observed between the cell densities obtained by these two methods. This handy super-paramagnetic lateral flow immnunoassay biosensor can greatly assist water quality monitoring programs as well as ecological research. PMID:26592649

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed Central

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

    2013-01-01

    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

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

    PubMed

    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 also have

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

    PubMed

    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. PMID:27251197

  7. Examination of the Seasonal Dynamics of the Toxic Dinoflagellate Alexandrium catenella at Redondo Beach, California, by Quantitative PCR▿

    PubMed Central

    Garneau, Marie-Ève; Schnetzer, Astrid; Countway, Peter D.; Jones, Adriane C.; Seubert, Erica L.; Caron, David A.

    2011-01-01

    The presence of neurotoxic species within the genus Alexandrium along the U.S. coastline has raised concern of potential poisoning through the consumption of contaminated seafood. Paralytic shellfish toxins (PSTs) detected in shellfish provide evidence that these harmful events have increased in frequency and severity along the California coast during the past 25 years, but the timing and location of these occurrences have been highly variable. We conducted a 4-year survey in King Harbor, CA, to investigate the seasonal dynamics of Alexandrium catenella and the presence of a particulate saxitoxin (STX), the parent compound of the PSTs. A quantitative PCR (qPCR) assay was developed for quantifying A. catenella in environmental microbial assemblages. This approach allowed for the detection of abundances as low as 12 cells liter−1, 2 orders of magnitude below threshold abundances that can impact food webs. A. catenella was found repeatedly during the study, particularly in spring, when cells were detected in 38% of the samples (27 to 5,680 cells liter−1). This peak in cell abundances was observed in 2006 and corresponded to a particulate STX concentration of 12 ng liter−1, whereas the maximum STX concentration of 26 ng liter−1 occurred in April 2008. Total cell abundances and toxin levels varied strongly throughout each year, but A. catenella was less abundant during summer, fall, and winter, when only 2 to 11% of the samples yielded positive qPCR results. The qPCR method developed here provides a useful tool for investigating the ecology of A. catenella at subbloom and bloom abundances. PMID:21926210

  8. STRATEGIES OF MARINE DINOFLAGELLATE SURVIVAL AND SOME RULES OF ASSEMBLY. (R829368)

    EPA Science Inventory

    Dinoflagellate ecology is based on multiple adaptive strategies and species having diverse habitat preferences. Nine types of mixing-irradiance-nutrient habitats selecting for specific marine dinoflagellate life-form types are recognised, with five rules of assembly proposed t...

  9. Exposure to the Neurotoxic Dinoflagellate, Alexandrium catenella, Induces Apoptosis of the Hemocytes of the Oyster, Crassostrea gigas

    PubMed Central

    Medhioub, Walid; Ramondenc, Simon; Vanhove, Audrey Sophie; Vergnes, Agnes; Masseret, Estelle; Savar, Veronique; Amzil, Zouher; Laabir, Mohamed; Rolland, Jean Luc

    2013-01-01

    This study assessed the apoptotic process occurring in the hemocytes of the Pacific oyster, Crassostrea gigas, exposed to Alexandrium catenella, a paralytic shellfish toxins (PSTs) producer. Oysters were experimentally exposed during 48 h to the toxic algae. PSTs accumulation, the expression of 12 key apoptotic-related genes, as well as the variation of the number of hemocytes in apoptosis was measured at time intervals during the experiment. Results show a significant increase of the number of hemocytes in apoptosis after 29 h of exposure. Two pro-apoptotic genes (Bax and Bax-like) implicated in the mitochondrial pathway were significantly upregulated at 21 h followed by the overexpression of two caspase executor genes (caspase-3 and caspase-7) at 29 h, suggesting that the intrinsic pathway was activated. No modulation of the expression of genes implicated in the cell signaling Fas-Associated protein with Death Domain (FADD) and initiation-phase (caspase-2) was observed, suggesting that only the extrinsic pathway was not activated. Moreover, the clear time-dependent upregulation of five (Bcl2, BI-1, IAP1, IAP7B and Hsp70) inhibitors of apoptosis-related genes associated with the return to the initial number of hemocytes in apoptosis at 48 h of exposure suggests the involvement of strong regulatory mechanisms of apoptosis occurring in the hemocytes of the Pacific oyster. PMID:24317471

  10. Accumulation and depuration profiles of PSP toxins in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Alexandrium catenella.

    PubMed

    Samsur, Mohamad; Yamaguchi, Yasunaga; Sagara, Takefumi; Takatani, Tomohiro; Arakawa, Osamu; Noguchi, Tamao

    2006-09-01

    A toxic dinoflagellate responsible for paralytic shellfish poisoning (PSP), Alexandrium catenella (Ac) was fed to the short-necked clam Tapes japonica, and the accumulation and depuration profiles of PSP toxins were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested more than 99% of the Ac cells (4 x 10(7)cells) supplied once at the beginning of experiment, and accumulated a maximal amount of toxin (185 nmol/10 clams) after 12h. The rate of toxin accumulation at that time was 23%, which rapidly decreased thereafter. Composition of the PSP toxin accumulated in the clams obviously different from that of Ac even 0.5h after the cell supply, the proportion of C1+2 being much higher than in Ac, although the reason remains to be elucidated. In contrast, a higher ratio of gonyautoxin (GTX)1+4 than in Ac was detected in the toxin profiles of clam excrements. The variation in toxin composition derived presumably from the transformation of toxin analogues in clams was observed from 0.5h, such as reversal of the ratio of C1 to C2, and appearance of carbamate (saxitoxin (STX), neoSTX and GTX2, 3) and decarbamoyl (dc) derivatives (dcSTX and dcGTX2, 3), which were undetectable in Ac cells. The total amount of toxin distributed over Ac cells, clams and their excrements gradually declined, and only 1% of supplied toxin was detected at the end of experiment. PMID:16887162

  11. Blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine in 1993 and 1994: A comparative modeling study

    USGS Publications Warehouse

    Stock, C.A.; McGillicuddy, D.J., Jr.; Anderson, D.M.; Solow, A.R.; Signell, R.P.

    2007-01-01

    Blooms of the toxic dinoflagellate Alexandrium fundyense commonly occur in the western Gulf of Maine but the amount of toxin observed in coastal shellfish is highly variable. In this study, a coupled physical-biological model is used to investigate the dynamics underlying the observed A. fundyense abundance and shellfish toxicity in 1993 (a high toxicity year) and 1994 (low toxicity year). The physical model simulates the spring circulation, while the biological model estimates the germination and population dynamics of A. fundyense based on laboratory and field data. The model captures the large-scale aspects of the initiation and development of A. fundyense blooms during both years, but small-scale patchiness and the dynamics of bloom termination remain problematic. In both cases, the germination of resting cysts accounts for the magnitude of A. fundyense populations early in the spring. Simulations with low net A. fundyense growth rates capture the mean observed concentration during the bloom peak, which is of similar magnitude during both years. There is little evidence that large-scale changes in biological dynamics between 1993 and 1994 were a primary driver of the differences in shellfish toxicity. Results instead suggest that the persistent southwesterly flow of the western Maine Coastal Current led to A. fundyense populations of similar alongshore extent by late May of both years. This period coincides with peak cell abundance in the region. Variations in wind forcing (downwelling favorable in 1993, upwelling favorable in 1994) and subsequent cell transport (inshore in 1993, offshore in 1994) in early June then provides a plausible explanation for the dramatic mid-June differences in shellfish toxicity throughout the western Gulf of Maine. ?? 2007 Elsevier Ltd. All rights reserved.

  12. 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

    PubMed Central

    Salgado, Pablo; Vázquez, José A.; Riobó, Pilar; Franco, José M.; Figueroa, Rosa I.; Kremp, Anke; Bravo, Isabel

    2015-01-01

    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. PMID:26636674

  13. Physiological and pathological changes in the eastern oyster Crassostrea virginica infested with the trematode Bucephalus sp. and exposed to the toxic dinoflagellate Alexandrium fundyense.

    PubMed

    Lassudrie, Malwenn; Wikfors, Gary H; Sunila, Inke; Alix, Jennifer H; Dixon, Mark S; Combot, Doriane; Soudant, Philippe; Fabioux, Caroline; Hégaret, Hélène

    2015-03-01

    Effects of experimental exposure to Alexandrium fundyense, a Paralytic Shellfish Toxin (PST) producer known to affect bivalve physiological condition, upon eastern oysters, Crassostrea virginica with a variable natural infestation of the digenetic trematode Bucephalus sp. were determined. After a three-week exposure to cultured A. fundyense or to a control algal treatment with a non-toxic dinoflagellate, adult oysters were assessed for a suite of variables: histopathological condition, hematological variables (total and differential hemocyte counts, morphology), hemocyte functions (Reactive Oxygen Species (ROS) production and mitochondrial membrane potential), and expression in gills of genes involved in immune responses and cellular protection (MnSOD, CAT, GPX, MT-IV, galectin CvGal) or suspected to be (Dominin, Segon). By comparing individual oysters infested heavily with Bucephalus sp. and uninfested individuals, we found altered gonad and digestive gland tissue and an inflammatory response (increased hemocyte concentration in circulating hemolymph and hemocyte infiltrations in tissues) associated with trematode infestation. Exposure to A. fundyense led to a higher weighted prevalence of infection by the protozoan parasite Perkinsus marinus, responsible for Dermo disease. Additionally, exposure to A. fundyense in trematode-infested oysters was associated with the highest prevalence of P. marinus infection. These observations suggest that the development of P. marinus infection was advanced by A. fundyense exposure, and that, in trematode-infested oysters, P. marinus risk of infection was higher when exposed to A. fundyense. These effects were associated with suppression of the inflammatory response to trematode infestation by A. fundyense exposure. Additionally, the combination of trematode infestation and A. fundyense exposure caused degeneration of adductor muscle fibers, suggesting alteration of valve movements and catch state, which could increase

  14. Blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine in 1993 and 1994: A comparative modeling study

    NASA Astrophysics Data System (ADS)

    Stock, Charles A.; McGillicuddy, Dennis J.; Anderson, Donald M.; Solow, Andrew R.; Signell, Richard P.

    2007-11-01

    Blooms of the toxic dinoflagellate Alexandrium fundyense commonly occur in the western Gulf of Maine but the amount of toxin observed in coastal shellfish is highly variable. In this study, a coupled physical-biological model is used to investigate the dynamics underlying the observed A. fundyense abundance and shellfish toxicity in 1993 (a high toxicity year) and 1994 (low toxicity year). The physical model simulates the spring circulation, while the biological model estimates the germination and population dynamics of A. fundyense based on laboratory and field data. The model captures the large-scale aspects of the initiation and development of A. fundyense blooms during both years, but small-scale patchiness and the dynamics of bloom termination remain problematic. In both cases, the germination of resting cysts accounts for the magnitude of A. fundyense populations early in the spring. Simulations with low net A. fundyense growth rates capture the mean observed concentration during the bloom peak, which is of similar magnitude during both years. There is little evidence that large-scale changes in biological dynamics between 1993 and 1994 were a primary driver of the differences in shellfish toxicity. Results instead suggest that the persistent southwesterly flow of the western Maine Coastal Current led to A. fundyense populations of similar alongshore extent by late May of both years. This period coincides with peak cell abundance in the region. Variations in wind forcing (downwelling favorable in 1993, upwelling favorable in 1994) and subsequent cell transport (inshore in 1993, offshore in 1994) in early June then provides a plausible explanation for the dramatic mid-June differences in shellfish toxicity throughout the western Gulf of Maine.

  15. Ocean Acidification Reduces Growth and Calcification in a Marine Dinoflagellate

    PubMed Central

    Van de Waal, Dedmer B.; John, Uwe; Ziveri, Patrizia; Reichart, Gert-Jan; Hoins, Mirja; Sluijs, Appy; Rost, Björn

    2013-01-01

    Ocean acidification is considered a major threat to marine ecosystems and may particularly affect calcifying organisms such as corals, foraminifera and coccolithophores. Here we investigate the impact of elevated pCO2 and lowered pH on growth and calcification in the common calcareous dinoflagellate Thoracosphaera heimii. We observe a substantial reduction in growth rate, calcification and cyst stability of T. heimii under elevated pCO2. Furthermore, transcriptomic analyses reveal CO2 sensitive regulation of many genes, particularly those being associated to inorganic carbon acquisition and calcification. Stable carbon isotope fractionation for organic carbon production increased with increasing pCO2 whereas it decreased for calcification, which suggests interdependence between both processes. We also found a strong effect of pCO2 on the stable oxygen isotopic composition of calcite, in line with earlier observations concerning another T. heimii strain. The observed changes in stable oxygen and carbon isotope composition of T. heimii cysts may provide an ideal tool for reconstructing past seawater carbonate chemistry, and ultimately past pCO2. Although the function of calcification in T. heimii remains unresolved, this trait likely plays an important role in the ecological and evolutionary success of this species. Acting on calcification as well as growth, ocean acidification may therefore impose a great threat for T. heimii. PMID:23776586

  16. Nutrients and water masses in the Gulf of Maine - Georges Bank region: Variability and importance to blooms of the toxic dinoflagellate Alexandrium fundyense

    PubMed Central

    Townsend, D.W.; McGillicuddy, D.J.; Thomas, M.A.; Rebuck, N.R.

    2015-01-01

    We report here the results of ten oceanographic survey cruises carried out in the Gulf of Maine - Georges Bank region of the Northwest Atlantic during the late spring to summer period in 2007, 2008 and 2010, for which we examine and characterize relationships among dissolved inorganic nutrient fields, water mass dynamics and cell densities of the toxic dinoflagellate Alexandrium fundyense. Nutrients are supplied to continental shelf waters of the Gulf of Maine - Georges Bank region by inflows of deep offshore water masses; once in the Gulf they are transported with the residual circulation and mix with surface waters, both in the Gulf and on the Bank. Those fluxes of offshore water masses and their nutrient loads are the major source of nutrients for phytoplankton production in the region, including annual blooms of A. fundyense in the Gulf and on Georges Bank. This much is already known. We suggest here that the locations and magnitude of A. fundyense blooms are controlled in part by variable nutrient fluxes to the interior Gulf of Maine from offshore, and, those interior Gulf of Maine waters are, in turn, the main nutrient source to Georges Bank, which are brought onto the Bank by tidal pumping on the Northern Flank. We present evidence that nitrate is the initial form of nitrogenous nutrient for A. fundyense blooms, but it is quickly depleted to limiting concentrations of less than 0.5 μM, at which time continued growth and maintenance of the population is likely fueled by recycled ammonium. We also show that phosphate may be the limiting nutrient over much of Georges Bank in summer, allowing recycled ammonium concentrations to increase. Our temperature-salinity analyses reveal spatial and temporal (seasonal and interannual) variability in the relative proportions of two deep source waters that enter the Gulf of Maine at depth through the Northeast Channel: Warm Slope Water (WSW) and Labrador Slope Water (LSW). Those two source waters are known to vary in their

  17. Improvement of lipid production in the marine strains Alexandrium minutum and Heterosigma akashiwo by utilizing abiotic parameters.

    PubMed

    Fuentes-Grünewald, C; Garcés, E; Alacid, E; Sampedro, N; Rossi, S; Camp, J

    2012-01-01

    Two different strains of microalgae, one raphidophyte and one dinoflagellate, were tested under different abiotic conditions with the goal of enhancing lipid production. Whereas aeration was crucial for biomass production, nitrogen deficiency and temperature were found to be the main abiotic parameters inducing the high-level cellular accumulation of neutral lipids. Net neutral lipid production and especially triacylglycerol (TAG) per cell were higher in microalgae (>200% in Alexandrium minutum, and 30% in Heterosigma akashiwo) under treatment conditions (25°C; 330 μM NaNO(3)) than under control conditions (20°C; 880 μM NaNO(3)). For both algal species, oil production (free fatty acids plus TAG fraction) was also higher under treatment conditions (57 mg L(-1) in A. minutum and 323 mg L(-1) in H. akashiwo). Despite the increased production and accumulation of lipids in microalgae, the different conditions did not significantly change the fatty acids profiles of the species analyzed. These profiles consisted of saturated fatty acids (SAFA) and polyunsaturated fatty acids (PUFA) in significant proportions. However, during the stationary phase, the concentrations per cell of some PUFAs, especially arachidonic acid (C20:4n6), were higher in treated than in control algae. These results suggest that the adjustment of abiotic parameters is a suitable and one of the cheapest alternatives to obtain sufficient quantities of microalgal biomass, with high oil content and minimal changes in the fatty acid profile of the strains under consideration. PMID:21766212

  18. Correlation and paleoenvironments of middle Paleogene marine beds based on dinoflagellate cysts in southwestern Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Guerstein, G. Raquel; González Estebenet, M. Sol; Alperín, Marta I.; Casadío, Silvio A.; Archangelsky, Sergio

    2014-07-01

    An understanding of paleonvironmental and paleoceanographic evolution of the Southwestern Atlantic Ocean during the Palaeogene is prevented by the lack of precise tools to date and correlate the sedimentary units. Palynological samples collected in the upper portion of the Man Aike Formation, which crops out southern Lago Argentino area, in the southwest of the Austral Basin (50°21‧45″S-72°14‧30″W), contain well preserved marine organic dinoflagellate cysts, which are potentially important biostratigraphic and paleoenvironmental indicators. Herein we describe the composition of the Man Aike Formation's dinoflagellate cyst assemblages and compare them to similar assemblages collected in the same basin in the upper member of the Río Turbio Formation using Compositional Statistical Analysis. The dinoflagellate cyst assemblages from the upper part of the Man Aike Formation are highly correlated to the assemblages from the upper member of the Río Turbio Formation from outcropping sections (51°31‧13″S-72°15‧11″W) and with the lower part of sediment cores drilled by Yacimientos Carboníferos Fiscales in the Río Turbio Formation area. These dinoflagellate cyst assemblages show a very low correlation with the assemblages from the upper part of the Yacimientos Carboníferos Fiscales's cores. The comparison of our results with the high-resolution Southern Pacific Ocean dinoflagellate cyst zonation for the late Palaeocene to late Eocene allow us to date some of the dinoflagellate events recorded in formations of southwestern Patagonia. The assemblages from the Man Aike Formation and the lower part of the upper member of the Río Turbio Formation relate to the zones SPDZ11 and SPDZ12 and are assigned to the mid-middle Eocene (late Lutetian to early Bartonian). The biostratigraphy proposed herein constrains the age of the Man Aike Formation and equivalent units based on calcareous microfossil data, mollusks affinities and 87Sr/86Sr isotopic values to an

  19. The variability in DMSP content and DMSP lyase activity in marine dinoflagellates

    NASA Astrophysics Data System (ADS)

    Caruana, Amandine M. N.; Malin, Gill

    2014-01-01

    More than 20 years ago Maureen Keller and co-workers published a study that identified dinoflagellates as an important marine phytoplankton group with respect to the production of dimethylsulphoniopropionate (DMSP). Here, we present a synthesis and analysis of all the DMSP and DMSP lyase activity (DLA) measurements currently available for dinoflagellates. The data cover 110 species and strains and reveal over 6 orders of magnitude variability in intracellular DMSP concentrations and substantial variations in DLA in 23 strains. Inter-specific variability was explored with reference to a range of biological characteristics. The presence of a theca did not appear to be related to DMSP concentration but there was a potential relationship with toxicity (P = 0.06) and bioluminescent species produced significantly lower concentrations (P < 0.01) than non-bioluminescent ones. DMSP concentrations were related to plastid types (P < 0.05); dinoflagellates with haptophyte-like plastids contained lower amounts of DMSP than those with peridinin plastids (P < 0.01), whereas those containing cryptomonad-like plastids tended to have higher DMSP concentrations. Heterotrophic dinoflagellates were also considered given their importance in the natural environment. They are the only heterotrophs known to synthesise DMSP and this ability may support the theory that they are of photosynthetic origin. However, the heterotrophic species investigated so far suggest wide variability in DMSP content and the species Oxyrrhis marina had no detectable DMSP. The oceanic province of origin significantly affected the DMSP concentrations (P < 0.05) with higher DMSP content observed in dinoflagellates from the Mediterranean province, the Kuroshio Current province and the East Coastal Australian province. Overall this study supports the concept that DMSP-containing dinoflagellates are an important potential source of DMS to the global atmosphere and highlights current gaps in knowledge.

  20. Modelling the Stoichiometric Regulation of C-Rich Toxins in Marine Dinoflagellates

    PubMed Central

    Pistocchi, Rossella; Vanucci, Silvana; Ciavatta, Stefano; Polimene, Luca

    2015-01-01

    Toxin production in marine microalgae was previously shown to be tightly coupled with cellular stoichiometry. The highest values of cellular toxin are in fact mainly associated with a high carbon to nutrient cellular ratio. In particular, the cellular accumulation of C-rich toxins (i.e., with C:N > 6.6) can be stimulated by both N and P deficiency. Dinoflagellates are the main producers of C-rich toxins and may represent a serious threat for human health and the marine ecosystem. As such, the development of a numerical model able to predict how toxin production is stimulated by nutrient supply/deficiency is of primary utility for both scientific and management purposes. In this work we have developed a mechanistic model describing the stoichiometric regulation of C-rich toxins in marine dinoflagellates. To this purpose, a new formulation describing toxin production and fate was embedded in the European Regional Seas Ecosystem Model (ERSEM), here simplified to describe a monospecific batch culture. Toxin production was assumed to be composed by two distinct additive terms; the first is a constant fraction of algal production and is assumed to take place at any physiological conditions. The second term is assumed to be dependent on algal biomass and to be stimulated by internal nutrient deficiency. By using these assumptions, the model reproduced the concentrations and temporal evolution of toxins observed in cultures of Ostreopsis cf. ovata, a benthic/epiphytic dinoflagellate producing C-rich toxins named ovatoxins. The analysis of simulations and their comparison with experimental data provided a conceptual model linking toxin production and nutritional status in this species. The model was also qualitatively validated by using independent literature data, and the results indicate that our formulation can be also used to simulate toxin dynamics in other dinoflagellates. Our model represents an important step towards the simulation and prediction of marine algal

  1. A quantitative real-time PCR assay for the identification and enumeration of Alexandrium cysts in marine sediments

    NASA Astrophysics Data System (ADS)

    Erdner, D. L.; Percy, L.; Keafer, B.; Lewis, J.; Anderson, D. M.

    2010-02-01

    Harmful algal blooms (HABs) are a global problem that affects both human and ecosystem health. One of the most serious and widespread HAB poisoning syndromes is paralytic shellfish poisoning, commonly caused by Alexandrium spp. dinoflagellates. Like many toxic dinoflagellates, Alexandrium produces resistant resting cysts as part of its life cycle. These cysts play a key role in bloom initiation and decline, as well as dispersal and colonization of new areas. Information on cyst numbers and identity is essential for understanding and predicting blooms, yet comprehensive cyst surveys are extremely time- and labor-intensive. Here we describe the development and validation of a quantitative real-time PCR (qPCR) technique for the enumeration of cysts of A. tamarense of the toxic North American/Group I ribotype. The method uses a cloned fragment of the large subunit ribosomal RNA gene as a standard for cyst quantification, with an experimentally determined conversion factor of 28,402±6152 LSU ribosomal gene copies per cyst. Tests of DNA extraction and PCR efficiency show that mechanical breakage is required for adequate cyst lysis, and that it was necessary to dilute our DNA extracts 50-fold in order to abolish PCR inhibition from compounds co-extracted from the sediment. The resulting assay shows a linear response over 6 orders of magnitude and can reliably quantify ≥10 cysts/cm 3 sediment. For method validation, 129 natural sediment samples were split and analyzed in parallel, using both the qPCR and primulin-staining techniques. Overall, there is a significant correlation ( p<0.001) between the cyst abundances determined by the two methods, although the qPCR counts tend to be lower than the primulin values. This underestimation is less pronounced in those samples collected from the top 1 cm of sediment, and more pronounced in those derived from the next 1-3 cm of the core. These differences may be due to the condition of the cysts in the different layers, as the

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

    PubMed

    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. PMID:26188429

  3. Dinoflagellate species and organic facies evidence of marine transgression and regression in the atlantic coastal plain

    USGS Publications Warehouse

    Habib, D.; Miller, J.A.

    1989-01-01

    Palynological evidence is used to date and interpret depositional environments of sediments of Campanian, Maestrichtian and early Danian ages cored in three wells from South Carolina and Georgia. The evidence is usefil for distinguishing environments which lithofacies evidence indicates a range from nonmarine to coastal to inner neritic shallow shelf. Numerous dinoflagellate species and an organic facies defined abundant amoprphous debris (amorphous debris facies) distinguish shallow shelf sediments deposited during marine transgression. The nearshore amorphous debris facies of late Campanian age consists of heterogenous assemblages dominated by Palaeohystrichophora infusorioides Deflandre or Hystrichosphaerina varians (May). The farther offshore amorphous debris facies of late early Maestrichtian to late Maestrichtian age consists of heterogenous assemblages dominated by Glaphyrocysta retiintexta (Cookson) and/or Areoligera medusettiformis (Wetzel). The larger number of dinoflagellate species in the offshore facies represents the maximum transgression detected in the investigated interval. A multiple occurrence datum defined by the combination of first appearance, klast appearances and sole occurrence of dinoflagellate species at the base of each interval distinguished by the amorphous debris facies provides the first evidence of marine transgression. Relatively small organic residues consisting of intertinite and few or no palynomorphs define the inertinite facies in nonmarine deltaic and in coastal (lagoonal, tidal flat, interdistributary bary) sediments. Dinocyt{star, open}s are absent in the nonmarine sediments and are represented by few species and few specimens in the coastal inertinite faceis. A third organic facies (vascular tissue facies) is defined by the abundance of land plant tissue. Sporomorph species, including those of the Normapolles pollen group and of pteridophyte spores, comprise a large proportion of the total palynomorph flora in the

  4. Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population

    PubMed Central

    John, Uwe; Tillmann, Urban; Hülskötter, Jennifer; Alpermann, Tilman J.; Wohlrab, Sylke; Van de Waal, Dedmer B.

    2015-01-01

    Dinoflagellates are a major cause of harmful algal blooms (HABs), with consequences for coastal marine ecosystem functioning and services. Alexandrium fundyense (previously Alexandrium tamarense) is one of the most abundant and widespread toxigenic species in the temperate Northern and Southern Hemisphere and produces paralytic shellfish poisoning toxins as well as lytic allelochemical substances. These bioactive compounds may support the success of A. fundyense and its ability to form blooms. Here we investigate the impact of grazing on monoclonal and mixed set-ups of highly (Alex2) and moderately (Alex4) allelochemically active A. fundyense strains and a non-allelochemically active conspecific (Alex5) by the heterotrophic dinoflagellate Polykrikos kofoidii. While Alex4 and particularly Alex5 were strongly grazed by P. kofoidii when offered alone, both strains grew well in the mixed assemblages (Alex4 + Alex5 and Alex2 + Alex5). Hence, the allelochemical active strains facilitated growth of the non-active strain by protecting the population as a whole against grazing. Based on our results, we argue that facilitation among clonal lineages within a species may partly explain the high genotypic and phenotypic diversity of Alexandrium populations. Populations of Alexandrium may comprise multiple cooperative traits that act in concert with intraspecific facilitation, and hence promote the success of this notorious HAB species. PMID:25411447

  5. The toxic dinoflagellate Alexandrium minutum disrupts daily rhythmic activities at gene transcription, physiological and behavioral levels in the oyster Crassostrea gigas.

    PubMed

    Tran, Damien; Ciutat, Aurélie; Mat, Audrey; Massabuau, Jean-Charles; Hégaret, Hélène; Lambert, Christophe; Le Goic, Nelly; Soudant, Philippe

    2015-01-01

    The objective of the present work was to study the effect of the harmful alga Alexandrium minutum on the daily rhythm of the oyster Crassostrea gigas. Many metabolic and physiological functions are rhythmic in living animals. Their cycles are modeled in accordance with environmental cycles such as the day/night cycle, which are fundamental to increase the fitness of an organism in its environment. A disruption of rhythmic activities is known to possibly impact the health of an animal. This study focused in C. gigas, on a gene known to be involved in circadian rhythmicity, cryptochrome gene (CgCry), on putative clock-controlled genes involved in metabolic and physiological functions, on the length cycle of the style, a structure involved in digestion, and on the rhythmicity of valve activity involved in behavior. The results indicate that daily activity is synchronized at the gene level by light:dark cycles in C. gigas. A daily rhythm of valve activity and a difference in crystalline style length between scotophase and photophase were also demonstrated. Additionally, A. minutum exposure was shown to alter cyclic activities: in exposed oysters, gene transcription remained at a constant low level throughout a daily cycle, valve opening duration remained maximal and crystalline style length variation disappeared. The results show that a realistic bloom of A. minutum clearly can disrupt numerous and diverse molecular, physiological and behavioral functions via a loss of rhythmicity. PMID:25461744

  6. Taxonomic and Environmental Variation of Metabolite Profiles in Marine Dinoflagellates of the Genus Symbiodinium

    PubMed Central

    Klueter, Anke; Crandall, Jesse B.; Archer, Frederick I.; Teece, Mark A.; Coffroth, Mary Alice

    2015-01-01

    Microorganisms in terrestrial and marine ecosystems are essential to environmental sustainability. In the marine environment, invertebrates often depend on metabolic cooperation with their endosymbionts. Coral reefs, one of the most important marine ecosystems, are based on the symbiosis between a broad diversity of dinoflagellates of the genus Symbiodinium and a wide phyletic diversity of hosts (i.e., cnidarian, molluscan, poriferan). This diversity is reflected in the ecology and physiology of the symbionts, yet the underlying biochemical mechanisms are still poorly understood. We examined metabolite profiles of four cultured species of Symbiodinium known to form viable symbioses with reef-building corals, S. microadriaticum (cp-type A194), S. minutum (cp-type B184), S. psygmophilum (cp-type B224) and S. trenchii (cp-type D206). Metabolite profiles were shown to differ among Symbiodinium species and were found to be affected by their physiological response to growth in different temperatures and light regimes. A combined Random Forests and Bayesian analysis revealed that the four Symbiodinium species examined primarily differed in their production of sterols and sugars, including a C29 stanol and the two sterols C28Δ5 and C28Δ5,22, as well as differences in metabolite abundances of a hexose and inositol. Inositol levels were also strongly affected by changes in temperature across all Symbiodinium species. Our results offer a detailed view of the metabolite profile characteristic of marine symbiotic dinoflagellates of the genus Symbiodinium, and identify patterns of metabolites related to several growth conditions. PMID:25693143

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

    PubMed

    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. PMID:27153107

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

    PubMed Central

    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. PMID:27153107

  9. Holocene dinoflagellate cyst record of climate and marine primary productivity change in the Santa Barbara Basin, southern California.

    NASA Astrophysics Data System (ADS)

    Pospelova, Vera; Mertens, Kenneth N.; Hendy, Ingrid, L.; Pedersen, Thomas F.

    2015-04-01

    High-resolution sedimentary records of dinoflagellate cysts and other marine palynomorphs from the Santa Barbara Basin (Ocean Drilling Program Hole 893A) demonstrate large variability of primary productivity during the Holocene, as the California Current System responded to climate change. Throughout the sequence, dinoflagellate cyst assemblages are characterized by the dominance of cysts produced by heterotrophic dinoflagellates, and particularly by Brigantedinium, accompanied by other upwelling-related taxa such as Echinidinium and cysts of Protoperidinium americanum. During the early Holocene (~12-7 ka), the species richness is relatively low (16 taxa) and genius Brigantedinium reaches the highest relative abundance, thus indicating nutrient-rich and highly productive waters. The middle Holocene (~7-3.5 ka) is characterized by relatively constant cyst concentrations, and dinoflagellate cyst assemblages are indicative of a slight decrease in sea-surface temperature. A noticeable increase and greater range of fluctuations in the cyst concentrations during the late Holocene (~3.5-1 ka) indicate enhanced marine primary productivity and increased climatic variability, most likely related to the intensification of El Niño-like conditions. Keywords: dinoflagellate cysts, Holocene, North Pacific, climate, primary productivity.

  10. Rapidly diverging evolution of an atypical alkaline phosphatase (PhoAaty) in marine phytoplankton: insights from dinoflagellate alkaline phosphatases

    PubMed Central

    Lin, Xin; Wang, Lu; Shi, Xinguo; Lin, Senjie

    2015-01-01

    Alkaline phosphatase (AP) is a key enzyme that enables marine phytoplankton to scavenge phosphorus (P) from dissolved organic phosphorus (DOP) when inorganic phosphate is scarce in the ocean. Yet how the AP gene has evolved in phytoplankton, particularly dinoflagellates, is poorly understood. We sequenced full-length AP genes and corresponding complementary DNA (cDNA) from 15 strains (10 species), representing four classes of the core dinoflagellate lineage, Gymnodiniales, Prorocentrales, Suessiales, and Gonyaulacales. Dinoflagellate AP gene sequences exhibited high variability, containing variable introns, pseudogenes, single nucleotide polymorphisms and consequent variations in amino acid sequence, indicative of gene duplication events and consistent with the “birth-and-death” model of gene evolution. Further sequence comparison showed that dinoflagellate APs likely belong to an atypical type AP (PhoAaty), which shares conserved motifs with counterparts in marine bacteria, cyanobacteria, green algae, haptophytes, and stramenopiles. Phylogenetic analysis suggested that PhoAaty probably originated from an ancestral gene in bacteria and evolved divergently in marine phytoplankton. Because variations in AP amino acid sequences may lead to differential subcellular localization and potentially different metal ion requirements, the multiple types of APs in algae may have resulted from selection for diversifying strategies to utilize DOP in the P variable marine environment. PMID:26379645

  11. The sxt Gene and Paralytic Shellfish Poisoning Toxins as Markers for the Monitoring of Toxic Alexandrium Species Blooms.

    PubMed

    Penna, Antonella; Perini, Federico; Dell'Aversano, Carmela; Capellacci, Samuela; Tartaglione, Luciana; Giacobbe, Maria Grazia; Casabianca, Silvia; Fraga, Santiago; Ciminiello, Patrizia; Scardi, Michele

    2015-12-15

    Paralytic shellfish poisoning (PSP) is a serious human illness caused by the ingestion of seafood contaminated with saxitoxin and its derivatives (STXs). These toxins are produced by some species of marine dinoflagellates within the genus Alexandrium. In the Mediterranean Sea, toxic Alexandrium spp. blooms, especially of A. minutum, are frequent and intense with negative impact to coastal ecosystem, aquaculture practices and other economic activities. We conducted a large scale study on the sxt gene and toxin distribution and content in toxic dinoflagellate A. minutum of the Mediterranean Sea using both quantitative PCR (qPCR) and HILIC-HRMS techniques. We developed a new qPCR assay for the estimation of the sxtA1 gene copy number in seawater samples during a bloom event in Syracuse Bay (Mediterranean Sea) with an analytical sensitivity of 2.0 × 10° sxtA1 gene copy number per reaction. The linear correlation between sxtA1 gene copy number and microalgal abundance and between the sxtA1 gene and STX content allowed us to rapidly determine the STX-producing cell concentrations of two Alexandrium species in environmental samples. In these samples, the amount of sxtA1 gene was in the range of 1.38 × 10(5) - 2.55 × 10(8) copies/L and the STX concentrations ranged from 41-201 nmol/L. This study described a potential PSP scenario in the Mediterranean Sea. PMID:26580419

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

    PubMed Central

    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

  13. Ozonation of the marine dinoflagellate alga Amphidinium sp.--implications for ballast water disinfection.

    PubMed

    Oemcke, D J; Hans van Leeuwen, J

    2005-12-01

    Ozone has been investigated for its potential to remove marine dinoflagellate algae from ships' ballast water. Dinoflagellate algae, Amphidinium sp. isolated from the Great Barrier Reef, Townsville, Australia were used as indicators since these produce a type of cyst that is difficult to inactivate, but are relatively easy to culture. The ozonation experiments have demonstrated a high ozone demand for inactivation of the algal cultures, which increases as the culture ages. The main ozone demand in seawater is due to its reaction with bromide to form bromine compounds. The non-bromide ozone demand has been estimated by measuring the residuals produced after various doses of ozone. The Amphidinium sp. show an unexpected response to both ozonation and bromination, with an instantaneous inactivation of the organisms for all doses that produced an oxidant residual in the seawater, followed by an effect of the disinfection residual. The standard design procedure of comparing Ct will not be effective for predicting the response of the organism to varying dose, C, and contact time, t, and a plot of ozone produced oxidant residual against organism inactivation for various contact times is proposed for design purposes. High doses of ozone (5-11 mg/L) and up to 6h of residual contact were required for a 4-log inactivation of the Amphidinium sp. Ozonation is likely to be a difficult technology to implement for organisms with this ozone requirement in combination with characteristics of ballast tanks, which contain areas of sediments high in detritus and areas of corrosion. PMID:16289281

  14. Genome sequence of Enterobacter sp. ST3, a quorum sensing bacterium associated with marine dinoflagellate

    PubMed Central

    Zhou, Jin; Lao, Yong-Min; Ma, Zhi-Ping; Cai, Zhong-Hua

    2016-01-01

    Phycosphere environment is a typical marine niche, harbor diverse populations of microorganisms, which are thought to play a critical role in algae host and influence mutualistic and competitive interactions. Understanding quorum sensing-based acyl-homoserine lactone (AHL) language may shed light on the interaction between algal-associated microbial communities in the native environment. In this work, we isolated an epidermal bacterium (was tentatively named Enterobacter sp. ST3, and deposited in SOA China, the number is MCCC1K02277-ST3) from the marine dinoflagellate Scrippsiella trochoidea, and found it has the ability to produce short-chain AHL signal. In order to better understand its communication information at molecular level, the genomic map was investigated. The genome size was determined to be 4.81 Mb with a G + C content of 55.59%, comprising 6 scaffolds of 75 contigs containing 4647 protein-coding genes. The functional proteins were predicted, and 3534 proteins were assigned to COG functional categories. An AHL-relating gene, LuxR, was found in upstream position at contig 1. This genome data may provide clues to increase understanding of the chemical characterization and ecological behavior of strain ST3 in the phycosphere microenvironment. PMID:26981407

  15. The chemical mimicking of the mechanical stimulation, photoinhibition, and recovery from photoinhibition of bioluminescence in the marine dinoflagellate, Gonyaulax polyedra

    SciTech Connect

    Hamman, J.P.; Seliger, H.H.

    1982-06-01

    Mechanically stimulable bioluminescence and photoinhibition of sensitivity to mechanical stimulation in the marine dinoflagellate Gonyaulax polyedra can be mimicked by a number of cations, proportional to the logarithm of their external concentrations. The data are consistent with mechanical stimulability as a membrane depolarization resulting in an increase in H/sup +/ ions at bioluminescence sites and with photoinhibition as a hyperpolarization of the cell membrane.

  16. The chemical mimicking of the mechanical stimulation, photoinhibition, and recovery from photoinhibition of bioluminescence in the marine dinoflagellate, Gonyaulax polyedra

    SciTech Connect

    Hamman, J.P.; Seliger, H.H.

    1982-01-01

    Mechanically stimulable bioluminescence and photoinhibition of sensitivity to mechanical stimulation in the marine dinoflagellate Gonyaulax polyedra can be mimicked by a number of cations, proportional to the logarithm of their external concentrations. The data are consistent with mechanical stimulability as a membrane depolarization resulting in an increase in H/sup +/ ions at bioluminescence sites and with photoinhibition as a hyperpolarization of the cell membrane.

  17. Discovery of Nuclear-Encoded Genes for the Neurotoxin Saxitoxin in Dinoflagellates

    PubMed Central

    Stüken, Anke; Orr, Russell J. S.; Kellmann, Ralf; Murray, Shauna A.; Neilan, Brett A.; Jakobsen, Kjetill S.

    2011-01-01

    Saxitoxin is a potent neurotoxin that occurs in aquatic environments worldwide. Ingestion of vector species can lead to paralytic shellfish poisoning, a severe human illness that may lead to paralysis and death. In freshwaters, the toxin is produced by prokaryotic cyanobacteria; in marine waters, it is associated with eukaryotic dinoflagellates. However, several studies suggest that saxitoxin is not produced by dinoflagellates themselves, but by co-cultured bacteria. Here, we show that genes required for saxitoxin synthesis are encoded in the nuclear genomes of dinoflagellates. We sequenced >1.2×106 mRNA transcripts from the two saxitoxin-producing dinoflagellate strains Alexandrium fundyense CCMP1719 and A. minutum CCMP113 using high-throughput sequencing technology. In addition, we used in silico transcriptome analyses, RACE, qPCR and conventional PCR coupled with Sanger sequencing. These approaches successfully identified genes required for saxitoxin-synthesis in the two transcriptomes. We focused on sxtA, the unique starting gene of saxitoxin synthesis, and show that the dinoflagellate transcripts of sxtA have the same domain structure as the cyanobacterial sxtA genes. But, in contrast to the bacterial homologs, the dinoflagellate transcripts are monocistronic, have a higher GC content, occur in multiple copies, contain typical dinoflagellate spliced-leader sequences and eukaryotic polyA-tails. Further, we investigated 28 saxitoxin-producing and non-producing dinoflagellate strains from six different genera for the presence of genomic sxtA homologs. Our results show very good agreement between the presence of sxtA and saxitoxin-synthesis, except in three strains of A. tamarense, for which we amplified sxtA, but did not detect the toxin. Our work opens for possibilities to develop molecular tools to detect saxitoxin-producing dinoflagellates in the environment. PMID:21625593

  18. Characterization of Satellite DNA from Three Marine Dinoflagellates (Dinophyceae): Glenodinium sp. and Two Members of the Toxic Genus, Protogonyaulax 1

    PubMed Central

    Boczar, Barbara A.; Liston, John; Cattolico, Rose Ann

    1991-01-01

    Using CsCl-Hoechst dye or CsCl-ethidium bromide gradients, satellite and nuclear DNAs were separated and characterized in three marine dinoflagellates: Glenodinium sp., and two toxic dinoflagellates, Protogonyaulax tamarensis and Protogonyaulax catenella. In all three dinoflagellates, the lowest density fraction, satellite DNA1, hybridized to chloroplast genes derived from terrestrial plants and/or other algae. Dinoflagellate chloroplast DNAs exhibited molecular sizes of 114 to 125 kilobase pairs, which is consistent with plastid sizes determined for other chromophytic algae (120-150 kilobase pairs). Mitochondrial DNA was not resolved from nuclear DNA in this system. Two additional satellite DNAs, satellite DNA2 and satellite DNA3, recovered from P. tamarensis and P. catenella were similar to one another, both within and between species, when characterized by restriction enzyme analysis. These satellites were 85 to 95 kilobase pairs in size, and exhibited restriction fragments that hybridized to yeast nuclear ribosomal RNA genes. Restriction enzyme analyses and DNA hybridization studies of cpDNA document that the two Protogonyaulax isolates are not evolutionarily identical. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:16668443

  19. Influence of Starvation on Respiratory Metabolism and Pyridine Nucleotide Levels in the Marine Dinoflagellate Oxyrrhis marina.

    PubMed

    Osma, Natalia; Aristizabal, Manuela; Fernández-Urruzola, Igor; Packard, Theodore T; Gómez, May

    2016-04-01

    Respiratory oxygen consumption rate (RO2) and potential respiration (Φ) has been monitored during a food deprivation period in the heterotrophic dinoflagellate Oxyrrhis marina. Φ was determined by measuring the activity of the enzymes from the electron transport system (ETS), the major contributor to the oxygen consumption in the cells. Additionally, we have quantified for the first time the concentration of pyridine nucleotides in this organism, both in their oxidized (NAD(P)(+)) and reduced forms (NAD(P)H). These molecules are the main electron donors at the beginning of the ETS. We observed a dramatic decrease in RO2 within the first days, whereas Φ steadily, but more gradually declined during the entire experiment. This led to a decrease of the RO2 /Φ with time. The intracellular total pool of NAD and NADP concentration, in turn, dropped exponentially in a manner parallel to the RO2. This strong decrease was mainly driven by a reduction in the concentration of the oxidized forms. The present work constitutes a first step in clarifying the role of intracellular NAD and NADP concentrations and the redox status in the control of in vivo RO2 in marine organisms. PMID:26994731

  20. Light-Promoted Rhodopsin Expression and Starvation Survival in the Marine Dinoflagellate Oxyrrhis marina

    PubMed Central

    Guo, Zhiling; Zhang, Huan; Lin, Senjie

    2014-01-01

    The discovery of microbial rhodopsins in marine proteobacteria changed the dogma that photosynthesis is the only pathway to use the solar energy for biological utilization in the marine environment. Although homologs of these rhodopsins have been identified in dinoflagellates, the diversity of the encoding genes and their physiological roles remain unexplored. As an initial step toward addressing the gap, we conducted high-throughput transcriptome sequencing on Oxyrrhis marina to retrieve rhodopsin transcripts, rapid amplification of cDNA ends to isolate full-length cDNAs of dominant representatives, and quantitative reverse-transcription PCR to investigate their expression under varying conditions. Our phylogenetic analyses showed that O. marina contained both the proton-pumping type (PR) and sensory type (SR) rhodopsins, and the transcriptome data showed that the PR type dominated over the SR type. We compared rhodopsin gene expression for cultures kept under light: dark cycle and continuous darkness in a time course of 24 days without feeding. Although both types of rhodopsin were expressed under the two conditions, the expression levels of PR were much higher than SR, consistent with the transcriptomic data. Furthermore, relative to cultures kept in the dark, rhodopsin expression levels and cell survival rate were both higher in cultures grown in the light. This is the first report of light-dependent promotion of starvation survival and concomitant promotion of PR expression in a eukaryote. While direct evidence needs to come from functional test on rhodopsins in vitro or gene knockout/knockdown experiments, our results suggest that the proton-pumping rhodopsin might be responsible for the light-enhanced survival of O. marina, as previously demonstrated in bacteria. PMID:25506945

  1. Brevisulcatic acids, marine ladder-frame polyethers from the red tide dinoflagellate Karenia brevisulcata in New Zealand.

    PubMed

    Suzuki, Rina; Irie, Raku; Harntaweesup, Yanit; Tachibana, Kazuo; Holland, Patrick T; Harwood, D Tim; Shi, Feng; Beuzenberg, Veronica; Itoh, Yoshiyuki; Pascal, Steven; Edwards, Patrick J B; Satake, Masayuki

    2014-11-21

    The isolation and structural determination of new marine ladder-frame polyethers, brevisulcatic acids-1 (1) and -4 (2) are reported. Brevisulcatic acids were isolated from the dinoflagellate Karenia brevisulcata, which was identified as the causative species of a major red tide event in New Zealand in 1998. The ether ring composition and a β-hydroxy, γ-methylene valeric acid side chain of 1 and 2 are common, but 2 has a γ-lactone as the 5-membered A-ring while 1 is the seco acid analogue. Compound 2 has structural and bioactivity similarities to brevetoxin A. PMID:25356530

  2. Alexandrium minutum growth controlled by phosphorus . An applied model

    NASA Astrophysics Data System (ADS)

    Chapelle, A.; Labry, C.; Sourisseau, M.; Lebreton, C.; Youenou, A.; Crassous, M. P.

    2010-11-01

    Toxic algae are a worldwide problem threatening aquaculture, public health and tourism. Alexandrium, a toxic dinoflagellate proliferates in Northwest France estuaries (i.e. the Penzé 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 box model of Alexandrium growth. This work focuses on phosphorus nutrition. Our objective is to calibrate Alexandrium minutum as well as Heterocapsa triquetra (a non-toxic dinoflagellate) growth under different rates of phosphorus supply, other factors being optimal and constant. Laboratory experiments are used to calibrate two growth models and three uptake models for each species. Models are then used to simulate monospecific batch and semi-continuous experiments as well as competition between the two algae (mixed cultures). Results show that the Droop growth model together with linear uptake versus quota can represent most of our observations, although a power law uptake function can more accurately simulate our phosphorus uptake data. We note that such models have limitations in non steady-state situations and cell quotas can depend on a variety of factors, so care must be taken in extrapolating these results beyond the specific conditions studied.

  3. Pilot-scale bubble column photobioreactor culture of a marine dinoflagellate microalga illuminated with light emission diodes.

    PubMed

    López-Rosales, L; García-Camacho, F; Sánchez-Mirón, A; Martín Beato, E; Chisti, Yusuf; Molina Grima, E

    2016-09-01

    Production of biomass of the shear-sensitive marine algal dinoflagellate Karlodinium veneficum was successfully scaled-up to 80L using a bubble column photobioreactor. The scale factor exceeded 28,500. Light-emission diodes were used as the light source. The diel irradiance profile mimicked the outdoor profile of natural sunlight. The final cell concentration in the absence of nutrient limitation in the scaled-up photobioreactor was nearly 12×10(5)cellsmL(-1), or the same as in laboratory culture systems. The pH-controlled culture (pH=8.5) was always carbon-sufficient. The culture was mixed pneumatically by using a superficial air velocity of 1.9×10(-3)ms(-1) and the temperature was controlled at 21±1°C. PMID:27318163

  4. Aspergillus Sydowii Marine Fungal Bloom in Australian Coastal Waters, Its Metabolites and Potential Impact on Symbiodinium Dinoflagellates.

    PubMed

    Hayashi, Aiko; Crombie, Andrew; Lacey, Ernest; Richardson, Anthony J; Vuong, Daniel; Piggott, Andrew M; Hallegraeff, Gustaaf

    2016-03-01

    Dust has been widely recognised as an important source of nutrients in the marine environment and as a vector for transporting pathogenic microorganisms. Disturbingly, in the wake of a dust storm event along the eastern Australian coast line in 2009, the Continuous Plankton Recorder collected masses of fungal spores and mycelia (~150,000 spores/m³) forming a floating raft that covered a coastal area equivalent to 25 times the surface of England. Cultured A. sydowii strains exhibited varying metabolite profiles, but all produced sydonic acid, a chemotaxonomic marker for A. sydowii. The Australian marine fungal strains share major metabolites and display comparable metabolic diversity to Australian terrestrial strains and to strains pathogenic to Caribbean coral. Secondary colonisation of the rafts by other fungi, including strains of Cladosporium, Penicillium and other Aspergillus species with distinct secondary metabolite profiles, was also encountered. Our bioassays revealed that the dust-derived marine fungal extracts and known A. sydowii metabolites such as sydowic acid, sydowinol and sydowinin A adversely affect photophysiological performance (Fv/Fm) of the coral reef dinoflagellate endosymbiont Symbiodinium. Different Symbiodinium clades exhibited varying sensitivities, mimicking sensitivity to coral bleaching phenomena. The detection of such large amounts of A. sydowii following this dust storm event has potential implications for the health of coral environments such as the Great Barrier Reef. PMID:26999164

  5. Aspergillus Sydowii Marine Fungal Bloom in Australian Coastal Waters, Its Metabolites and Potential Impact on Symbiodinium Dinoflagellates

    PubMed Central

    Hayashi, Aiko; Crombie, Andrew; Lacey, Ernest; Richardson, Anthony J.; Vuong, Daniel; Piggott, Andrew M.; Hallegraeff, Gustaaf

    2016-01-01

    Dust has been widely recognised as an important source of nutrients in the marine environment and as a vector for transporting pathogenic microorganisms. Disturbingly, in the wake of a dust storm event along the eastern Australian coast line in 2009, the Continuous Plankton Recorder collected masses of fungal spores and mycelia (~150,000 spores/m3) forming a floating raft that covered a coastal area equivalent to 25 times the surface of England. Cultured A. sydowii strains exhibited varying metabolite profiles, but all produced sydonic acid, a chemotaxonomic marker for A. sydowii. The Australian marine fungal strains share major metabolites and display comparable metabolic diversity to Australian terrestrial strains and to strains pathogenic to Caribbean coral. Secondary colonisation of the rafts by other fungi, including strains of Cladosporium, Penicillium and other Aspergillus species with distinct secondary metabolite profiles, was also encountered. Our bioassays revealed that the dust-derived marine fungal extracts and known A. sydowii metabolites such as sydowic acid, sydowinol and sydowinin A adversely affect photophysiological performance (Fv/Fm) of the coral reef dinoflagellate endosymbiont Symbiodinium. Different Symbiodinium clades exhibited varying sensitivities, mimicking sensitivity to coral bleaching phenomena. The detection of such large amounts of A. sydowii following this dust storm event has potential implications for the health of coral environments such as the Great Barrier Reef. PMID:26999164

  6. Molecular topology of the photosynthetic light-harvesting pigment complex, peridinin-chlorophyll a-protein, from marine dinoflagellates.

    PubMed

    Song, P S; Koka, P; Prézelin, B B; Haxo, F T

    1976-10-01

    The photosynthetic light-harvesting complex, peridinin-chlorophyll a-protein, was isolated from several marine dinoflagellates including Glenodinium sp. by Sephadex and ion-exchange chromatography. The carotenoid (peridinin)-chlorophyll a ratio in the complex is estimated to be 4:1. The fluorescence excitation spectrum of the complex indicates that energy absorbed by the carotenoid is transferred to the chlorophyll a molecule with 100% efficiency. Fluorescence lifetime measurements indicate that the energy transfer is much faster than fluorescence emission from chlorophyll a. The four peridinin molecules within the complex appear to form two allowed exciton bands which split the main absorption band of the carotenoid into two circular dichronic bands (with negative ellipticity band at 538 nm and positive band at 463 nm in the case of peridinin-chlorophyl a-protein complex from Glenodinium sp.). The fluorescence polarization of chlorophyll a in the complex at 200 K is about 0.1 in both circular dichroic excitation bands of the carotenoid chromophore. From these circular dichroic and fluorescence polarization data, a possible molecular arrangement of the four peridinin and chlorophyll molecules has been deduced for the complex. The structure of the complex deduced is also consistent with the magnitude of the exciton spliting (ca. greater than 3000 cm-1) at the intermolecular distance in the dimer pair of peridinin (ca. 12 A). This structural feature accounts for the efficient light-harvesting process of dinoflagellates as the exciton interaction lengthens the lifetime of peridinin (radiative) and the complex topology increases the energy transfer probability. The complex is, therefore, a useful molecular model for elucidating the mechanism and efficiency of solar energy conversion in vivo as well as in vitro. PMID:987799

  7. Simultaneous Effect of Temperature and Irradiance on Growth and Okadaic Acid Production from the Marine Dinoflagellate Prorocentrum belizeanum

    PubMed Central

    López-Rosales, Lorenzo; Gallardo-Rodríguez, Juan Jose; Sánchez-Mirón, Asterio; Cerón-García, María del Carmen; Belarbi, El Hassan; García-Camacho, Francisco; Molina-Grima, Emilio

    2014-01-01

    Benthic marine dioflagellate microalgae belonging to the genus Prorocentrum are a major source of okadaic acid (OA), OA analogues and polyketides. However, dinoflagellates produce these valuable toxins and bioactives in tiny quantities, and they grow slowly compared to other commercially used microalgae. This hinders evaluation in possible large-scale applications. The careful selection of producer species is therefore crucial for success in a hypothetical scale-up of culture, as are appropriate environmental conditions for optimal growth. A clone of the marine toxic dinoflagellate P. belizeanum was studied in vitro to evaluate its capacities to grow and produce OA as an indicator of general polyketide toxin production under the simultaneous influence of temperature (T) and irradiance (I0). Three temperatures and four irradiance levels were tested (18, 25 and 28 °C; 20, 40, 80 and 120 µE·m−2·s−1), and the response variables measured were concentration of cells, maximum photochemical yield of photosystem II (PSII), pigments and OA. Experiments were conducted in T-flasks, since their parallelepipedal geometry proved ideal to ensure optically thin cultures, which are essential for reliable modeling of growth-irradiance curves. The net maximum specific growth rate (µm) was 0.204 day−1 at 25 °C and 40 µE·m−2·s−1. Photo-inhibition was observed at I0 > 40 μEm−2s−1, leading to culture death at 120 µE·m−2·s−1 and 28 °C. Cells at I0 ≥ 80 µE·m−2·s−1 were photoinhibited irrespective of the temperature assayed. A mechanistic model for µm-I0 curves and another empirical model for relating µm-T satisfactorily interpreted the growth kinetics obtained. ANOVA for responses of PSII maximum photochemical yield and pigment profile has demonstrated that P. belizeanum is extremely light sensitive. The pool of photoprotective pigments (diadinoxanthin and dinoxanthin) and peridinin was not able to regulate the excessive light-absorption at high I0

  8. Simultaneous effect of temperature and irradiance on growth and okadaic acid production from the marine dinoflagellate Prorocentrum belizeanum.

    PubMed

    López-Rosales, Lorenzo; Gallardo-Rodríguez, Juan Jose; Sánchez-Mirón, Asterio; Cerón-García, María del Carmen; Belarbi, El Hassan; García-Camacho, Francisco; Molina-Grima, Emilio

    2014-01-01

    Benthic marine dioflagellate microalgae belonging to the genus Prorocentrum are a major source of okadaic acid (OA), OA analogues and polyketides. However, dinoflagellates produce these valuable toxins and bioactives in tiny quantities, and they grow slowly compared to other commercially used microalgae. This hinders evaluation in possible large-scale applications. The careful selection of producer species is therefore crucial for success in a hypothetical scale-up of culture, as are appropriate environmental conditions for optimal growth. A clone of the marine toxic dinoflagellate P. belizeanum was studied in vitro to evaluate its capacities to grow and produce OA as an indicator of general polyketide toxin production under the simultaneous influence of temperature (T) and irradiance (I0). Three temperatures and four irradiance levels were tested (18, 25 and 28 °C; 20, 40, 80 and 120 µE·(m-2)·s(-1)), and the response variables measured were concentration of cells, maximum photochemical yield of photosystem II (PSII), pigments and OA. Experiments were conducted in T-flasks, since their parallelepipedal geometry proved ideal to ensure optically thin cultures, which are essential for reliable modeling of growth-irradiance curves. The net maximum specific growth rate (µ(m)) was 0.204 day(-1) at 25 °C and 40 µE·(m-2)·s(-1). Photo-inhibition was observed at I0 > 40 μEm(-2)s(-1), leading to culture death at 120 µE·m(-2)·s(-1) and 28 °C. Cells at I0 ≥ 80 µE·m(-2)·s(-1) were photoinhibited irrespective of the temperature assayed. A mechanistic model for µ(m)-I0 curves and another empirical model for relating µ(m)-T satisfactorily interpreted the growth kinetics obtained. ANOVA for responses of PSII maximum photochemical yield and pigment profile has demonstrated that P. belizeanum is extremely light sensitive. The pool of photoprotective pigments (diadinoxanthin and dinoxanthin) and peridinin was not able to regulate the excessive light-absorption at

  9. BMAA in shellfish from two Portuguese transitional water bodies suggests the marine dinoflagellate Gymnodinium catenatum as a potential BMAA source.

    PubMed

    Lage, Sandra; Costa, Pedro Reis; Moita, Teresa; Eriksson, Johan; Rasmussen, Ulla; Rydberg, Sara Jonasson

    2014-07-01

    The neurotoxin β-N-methylamino-l-alanine (BMAA) and its putative role in multiple neurodegenerative diseases have been intensely studied since 2005 when the toxin was discovered to be produced by worldwide-distributed cyanobacterial species inhabiting terrestrial, marine, brackish, and freshwater ecosystems. Recently, BMAA production was also associated with one eukaryotic group, namely, diatoms, raising questions about its production by other phytoplanktonic groups. To test for BMAA bioavailability in ecosystems where abundant phytoplanktonic blooms regularly occur, samples of filter-feeding shellfish were collected in two Portuguese transitional water bodies. BMAA content in cockles (Cerastoderma edule) collected weekly between September and November 2009 from Ria de Aveiro and at least once a month from May to November from Ria Formosa, fluctuated from 0.079±0.055 to 0.354±0.066μg/g DW and from below the limit of detection to 0.434±0.110μg/g DW, respectively. Simultaneously to BMAA occurrence in cockles, paralytic shellfish toxins were detected in shellfish as a result of Gymnodinium catenatum blooms indicating a possible link between this marine dinoflagellate and BMAA production. Moreover, considerable high BMAA levels, 0.457±0.186μg/g DW, were then determined in a laboratory grown culture of G. catenatum. This work reveals for the first time the presence of BMAA in shellfish from Atlantic transitional water bodies and consubstantiate evidences of G. catenatum as one of the main sources of BMAA in these ecosystems. PMID:24747603

  10. Blooms of the toxic dinoflagellate, Alexandrium fundyense in the Casco Bay region of the western Gulf of Maine: Advection from offshore source populations and interactions with the Kennebec River plume

    NASA Astrophysics Data System (ADS)

    Keafer, Bruce A.; Churchill, James H.; Anderson, Donald M.

    2005-09-01

    The Casco Bay region, an embayment adjacent to the Kennebec River, has been suggested as a source region for Alexandrium fundyense bloom development in the western Gulf of Maine (GOM). In this study, shipboard observations were acquired within Casco Bay and the nearby coastal waters during the spring of 1998 and 2000. In the early bloom season, low A. fundyense abundances (<100 cells l -1) were observed within the bay, sometimes isolated from A. fundyense populations observed in adjacent coastal waters. When high abundances of A. fundyense (>500 cells l -1) were observed within Casco Bay, they were contiguous with coastal populations observed within the Kennebec/Penobscot river plume and within offshore waters of the western segment of the Maine Coastal Current (WMCC). This general distributional pattern occurred during both study years. Wind directly affected the pathway of the incoming coastal populations. Downwelling-favorable winds generally facilitated bloom formation (and outbreaks of shellfish toxicity) within Casco Bay by enhancing the connection with offshore populations via alongshore and onshore transport of cells from the upstream coastal waters. In contrast, persistent upwelling-favorable winds were associated with low A. fundyense cell abundances (and shellfish toxicity) in Casco Bay by slowing the advance of the coastal population and shifting it offshore with the Kennebec plume front. The striking difference between late season (June) population abundances of the two study years can be explained by a combination of the wind pre-history and interannual differences in large-scale (Gulf-wide) circulation patterns, as evidenced by higher salinities in the coastal waters in 2000 vs. 1998. Advection of A. fundyense cells into Casco Bay and retention, not local growth within the Bay, are likely the dominant processes that typically result in the accumulation of high populations and shellfish toxicity in the Bay. A variety of mechanisms (e.g., circulation

  11. Molecular detection and species identification of Alexandrium (Dinophyceae) causing harmful algal blooms along the Chilean coastline

    PubMed Central

    Jedlicki, Ana; Fernández, Gonzalo; Astorga, Marcela; Oyarzún, Pablo; Toro, Jorge E.; Navarro, Jorge M.; Martínez, Víctor

    2012-01-01

    Background and aims On the basis of morphological evidence, the species involved in South American Pacific coast harmful algal blooms (HABs) has been traditionally recognized as Alexandrium catenella (Dinophyceae). However, these observations have not been confirmed using evidence based on genomic sequence variability. Our principal objective was to accurately determine the species of Alexandrium involved in local HABs in order to implement a real-time polymerase chain reaction (PCR) assay for its rapid and easy detection on filter-feeding shellfish, such as mussels. Methodology For species-specific determination, the intergenic spacer 1 (ITS1), 5.8S subunit, ITS2 and the hypervariable genomic regions D1–D5 of the large ribosomal subunit of local strains were sequenced and compared with two data sets of other Alexandrium sequences. Species-specific primers were used to amplify signature sequences within the genomic DNA of the studied species by conventional and real-time PCR. Principal results Phylogenetic analysis determined that the Chilean strain falls into Group I of the tamarensis complex. Our results support the allocation of the Chilean Alexandrium species as a toxic Alexandrium tamarense rather than A. catenella, as currently defined. Once local species were determined to belong to Group I of the tamarensis complex, a highly sensitive and accurate real-time PCR procedure was developed to detect dinoflagellate presence in Mytilus spp. (Bivalvia) samples after being fed (challenged) in vitro with the Chilean Alexandrium strain. The results show that real-time PCR is useful to detect Alexandrium intake in filter-feeding molluscs. Conclusions It has been shown that the classification of local Alexandrium using morphological evidence is not very accurate. Molecular methods enabled the HAB dinoflagellate species of the Chilean coast to be assigned as A. tamarense rather than A. catenella. Real-time PCR analysis based on A. tamarense primers allowed the

  12. The Parasitic Dinoflagellates Blastodinium spp. Inhabiting the Gut of Marine, Planktonic Copepods: Morphology, Ecology, and Unrecognized Species Diversity

    PubMed Central

    Skovgaard, Alf; Karpov, Sergey A.; Guillou, Laure

    2012-01-01

    Blastodinium is a genus of dinoflagellates that live as parasites in the gut of marine, planktonic copepods in the World’s oceans and coastal waters. The taxonomy, phylogeny, and physiology of the genus have only been explored to a limited degree and, based on recent investigations, we hypothesize that the morphological and genetic diversity within this genus may be considerably larger than presently recognized. To address these issues, we obtained 18S rDNA and ITS gene sequences for Blastodinium specimens of different geographical origins, including representatives of the type species. This genetic information was in some cases complemented with new morphological, ultrastructural, physiological, and ecological data. Because most current knowledge about Blastodinium and its effects on copepod hosts stem from publications more than half a century old, we here summarize and discuss the existing knowledge in relation to the new data generated. Most Blastodinium species possess functional chloroplasts, but the parasitic stage, the trophocyte, has etioplasts and probably a limited photosynthetic activity. Sporocytes and swarmer cells have well-developed plastids and plausibly acquire part of their organic carbon needs through photosynthesis. A few species are nearly colorless with no functional chloroplasts. The photosynthetic species are almost exclusively found in warm, oligotrophic waters, indicating a life strategy that may benefit from copepods as microhabitats for acquiring nutrients in a nutrient-limited environment. As reported in the literature, monophyly of the genus is moderately supported, but the three main groups proposed by Chatton in 1920 are consistent with molecular data. However, we demonstrate an important genetic diversity within the genus and provide evidences for new groups and the presence of cryptic species. Finally, we discuss the current knowledge on the occurrence of Blastodinium spp. and their potential impact on natural copepod

  13. Structural Confirmation of a Unique Carotenoid Lactoside, P457, in Symbiodinium sp. Strain nbrc 104787 Isolated from a Sea Anemone and its Distribution in Dinoflagellates and Various Marine Organisms.

    PubMed

    Wakahama, Takahiro; Laza-Martínez, Aitor; Bin Haji Mohd Taha, Ahmad Iskandar; Okuyama, Hidetoshi; Yoshida, Kiyohito; Kogame, Kazuhiro; Awai, Koichiro; Kawachi, Masanobu; Maoka, Takashi; Takaichi, Shinichi

    2012-12-01

    The molecular structure of the carotenoid lactoside P457, (3S,5R,6R,3'S,5'R,6'S)-13'-cis-5,6-epoxy-3',5'-dihydroxy-3-(β-d-galactosyl-(1→4)-β-d-glucosyl)oxy-6',7'-didehydro-5,6,7,8,5',6'-hexahydro-β,β-caroten-20-al, was confirmed by spectroscopic methods using Symbiodinium sp. strain NBRC 104787 cells isolated from a sea anemone. Among various algae, cyanobacteria, land plants, and marine invertebrates, the distribution of this unique diglycosyl carotenoid was restricted to free-living peridinin-containing dinoflagellates and marine invertebrates that harbor peridinin-containing zooxanthellae. Neoxanthin appeared to be a common precursor for biosynthesis of peridinin and P457, although neoxanthin was not found in peridinin-containing dinoflagellates. Fucoxanthin-containing dinoflagellates did not possess peridinin or P457; green dinoflagellates, which contain chlorophyll a and b, did not contain peridinin, fucoxanthin, or P457; and no unicellular algae containing both peridinin and P457, other than peridinin-containing dinoflagellates, have been observed. Therefore, the biosynthetic pathways for peridinin and P457 may have been coestablished during the evolution of dinoflagellates after the host heterotrophic eukaryotic microorganism formed a symbiotic association with red alga that does not contain peridinin or P457. PMID:27009990

  14. Toxic effects of harmful benthic dinoflagellate Ostreopsis ovata on invertebrate and vertebrate marine organisms.

    PubMed

    Faimali, Marco; Giussani, Valentina; Piazza, Veronica; Garaventa, Francesca; Corrà, Christian; Asnaghi, Valentina; Privitera, Davide; Gallus, Lorenzo; Cattaneo-Vietti, Riccardo; Mangialajo, Luisa; Chiantore, Mariachiara

    2012-05-01

    Harmful benthic microalgae blooms are an emerging phenomenon causing health and economic concern, especially in tourist areas. This is the case of the Mediterranean Sea, where Ostreopsis ovata blooms occur in summer, with increasing regularity. Ostreopsis species produce palytoxin (PTX) and analogues, and a number of deaths directly associated with the ingestion of PTX contaminated seafood have been reported. PTX is considered one of the most toxic molecules occurring in nature and can provoke severe and sometimes lethal intoxications in humans. So far in temperate areas, O. ovata blooms were reported to cause intoxications of humans by inhalation and irritations by contact. In addition, invertebrate mass mortalities have been reported, possibly linked to O. ovata blooms, although other causes cannot be ruled out, such as oxygen depletion or high seawater temperature. In order to improve our knowledge about the direct toxicity of this species on invertebrate and vertebrate marine organisms, we performed an ecotoxicological screening to investigate the toxic effects of different concentrations of O. ovata (cultured in the laboratory and sampled in the field during blooms) on crustaceans and fish as model organisms. Artemia salina, Tigriopus fulvus, and Amphibalanus amphitrite larvae and juveniles of the sea bass Dicentrarchus labrax were used as model species. Toxic effects associated with cultured O. ovata cells were investigated using a crossed design: testing two different temperatures (20 and 25 °C), four different cell concentrations, and four treatments (untreated O. ovata culture, filtered and resuspended algal cells, growth medium devoid of algal cells, and sonicated algal cells). The results indicate that the toxicity of cultured O. ovata is related to the presence of living O. ovata cells, and that this effect is amplified by temperature. Furthermore, both tests with laboratory cultured algae and field sampled cells pointed out that A. salina is the most

  15. Phylogenetic Diversity and Specificity of Bacteria Closely Associated with Alexandrium spp. and Other Phytoplankton

    PubMed Central

    Jasti, Suresh; Sieracki, Michael E.; Poulton, Nicole J.; Giewat, Michael W.; Rooney-Varga, Juliette N.

    2005-01-01

    While several studies have suggested that bacterium-phytoplankton interactions have the potential to dramatically influence harmful algal bloom dynamics, little is known about how bacteria and phytoplankton communities interact at the species composition level. The objective of the current study was to determine whether there are specific associations between diverse phytoplankton and the bacteria that co-occur with them. We determined the phylogenetic diversity of bacterial assemblages associated with 10 Alexandrium strains and representatives of the major taxonomic groups of phytoplankton in the Gulf of Maine. For this analysis we chose xenic phytoplankton cultures that (i) represented a broad taxonomic range, (ii) represented a broad geographic range for Alexandrium spp. isolates, (iii) grew under similar cultivation conditions, (iv) had a minimal length of time since the original isolation, and (v) had been isolated from a vegetative phytoplankton cell. 16S rRNA gene fragments of most Bacteria were amplified from DNA extracted from cultures and were analyzed by denaturing gradient gel electrophoresis and sequencing. A greater number of bacterial species were shared by different Alexandrium cultures, regardless of the geographic origin, than by Alexandrium species and nontoxic phytoplankton from the Gulf of Maine. In particular, members of the Roseobacter clade showed a higher degree of association with Alexandrium than with other bacterial groups, and many sequences matched sequences reported to be associated with other toxic dinoflagellates. These results provide evidence for specificity in bacterium-phytoplankton associations. PMID:16000752

  16. 13C fractionation of dinoflagellates - a new proxy for past CO2 levels?

    NASA Astrophysics Data System (ADS)

    Hoins, M.; Van de Waal, D. B.; Eberlein, T.; Reichart, G.; Sluijs, A.; Rost, B.

    2012-12-01

    Reliable reconstructions of atmospheric CO2 levels prior to ~1 million years ago are required to quantify climate sensitivity as well as ocean acidification in response to past carbon cycle perturbations. Despite recent progress, however, uncertainties in reconstructed values especially from the Paleogene and older, are still very large. We aim to develop a new proxy for CO2 concentrations based on the carbon isotopic fractionation of autotrophic marine dinoflagellates. Dinoflagellates feature RubisCO (type II) with the lowest CO2 affinity of all eukaryote phytoplankton, which makes this group inherently sensitive to changes in carbonate chemistry. Along with growth and carbon production also the 13C versus 12C incorporation, i.e., the 13C fractionation (ɛp), will likely be affected. Hence, the carbon isotopic composition of dinoflagellates may ultimately reflect the prevailing atmospheric CO2 concentrations. Crucially, microfossils of dinoflagellates, i.e. organic dinoflagellate cysts, have been recovered from ocean sediments as old as the Triassic (i.e. ~215 Ma BP). We performed dilute batch experiments with four dinoflagellate species: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at various CO2 concentrations representing the Last Glacial Maximum (180 ppm), present day (380 ppm), and future projections (and estimates for distant past levels; 950 ppm and 1400 ppm). Consistent with expectations, ɛp increased with CO2 concentration in all four species (with a slope of up to 0.19 ‰ μM-1), while growth and carbon production (μc) had little effect. ɛp in relation to CO2 varied between species and strains, but the relation of ɛp to μc/CO2 was more consistent. First results of underlying processes affecting ɛp, including carbon acquisition and leakage, will be discussed. Considering that the cysts of P. reticulatum (Operculodinium centrocarpum) and G. spinifera (Spiniferites sp.) are

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

    PubMed Central

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

    PubMed Central

    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

  19. RNA Sequencing Revealed Numerous Polyketide Synthase Genes in the Harmful Dinoflagellate Karenia mikimotoi

    PubMed Central

    Kimura, Kei; Okuda, Shujiro; Nakayama, Kei; Shikata, Tomoyuki; Takahashi, Fumio; Yamaguchi, Haruo; Skamoto, Setsuko; Yamaguchi, Mineo; Tomaru, Yuji

    2015-01-01

    The dinoflagellate Karenia mikimotoi forms blooms in the coastal waters of temperate regions and occasionally causes massive fish and invertebrate mortality. This study aimed to elucidate the toxic effect of K. mikimotoi on marine organisms by using the genomics approach; RNA-sequence libraries were constructed, and data were analyzed to identify toxin-related genes. Next-generation sequencing produced 153,406 transcript contigs from the axenic culture of K. mikimotoi. BLASTX analysis against all assembled contigs revealed that 208 contigs were polyketide synthase (PKS) sequences. Thus, K. mikimotoi was thought to have several genes encoding PKS metabolites and to likely produce toxin-like polyketide molecules. Of all the sequences, approximately 30 encoded eight PKS genes, which were remarkably similar to those of Karenia brevis. Our phylogenetic analyses showed that these genes belonged to a new group of PKS type-I genes. Phylogenetic and active domain analyses showed that the amino acid sequence of four among eight Karenia PKS genes was not similar to any of the reported PKS genes. These PKS genes might possibly be associated with the synthesis of polyketide toxins produced by Karenia species. Further, a homology search revealed 10 contigs that were similar to a toxin gene responsible for the synthesis of saxitoxin (sxtA) in the toxic dinoflagellate Alexandrium fundyense. These contigs encoded A1–A3 domains of sxtA genes. Thus, this study identified some transcripts in K. mikimotoi that might be associated with several putative toxin-related genes. The findings of this study might help understand the mechanism of toxicity of K. mikimotoi and other dinoflagellates. PMID:26561394

  20. Effects of temperature and salinity on the growth of Alexandrium (Dinophyceae) isolates from the Salish Sea.

    PubMed

    Bill, Brian D; Moore, Stephanie K; Hay, Levi R; Anderson, Donald M; Trainer, Vera L

    2016-04-01

    Toxin-producing blooms of dinoflagellates in the genus Alexandrium have plagued the inhabitants of the Salish Sea for centuries. Yet the environmental conditions that promote accelerated growth of this organism, a producer of paralytic shellfish toxins, is lacking. This study quantitatively determined the growth response of two Alexandrium isolates to a range of temperatures and salinities, factors that will strongly respond to future climate change scenarios. An empirical equation, derived from observed growth rates describing the temperature and salinity dependence of growth, was used to hindcast bloom risk. Hindcasting was achieved by comparing predicted growth rates, calculated from in situ temperature and salinity data from Quartermaster Harbor, with corresponding Alexandrium cell counts and shellfish toxin data. The greatest bloom risk, defined at μ >0.25 d(-1) , generally occurred from April through November annually; however, growth rates rarely fell below 0.10 d(-1) . Except for a few occasions, Alexandrium cells were only observed during the periods of highest bloom risk and paralytic shellfish toxins above the regulatory limit always fell within the periods of predicted bloom occurrence. While acknowledging that Alexandrium growth rates are affected by other abiotic and biotic factors, such as grazing pressure and nutrient availability, the use of this empirical growth function to predict higher risk time frames for blooms and toxic shellfish within the Salish Sea provides the groundwork for a more comprehensive biological model of Alexandrium bloom dynamics in the region and will enhance our ability to forecast blooms in the Salish Sea under future climate change scenarios. PMID:27037588

  1. Transcriptomic profiling of Alexandrium fundyense during physical interaction with or exposure to chemical signals from the parasite Amoebophrya.

    PubMed

    Lu, Yameng; Wohlrab, Sylke; Groth, Marco; Glöckner, Gernot; Guillou, Laure; John, Uwe

    2016-03-01

    Toxic microalgae have their own pathogens, and understanding the way in which these microalgae respond to antagonistic attacks may provide information about their capacity to persist during harmful algal bloom events. Here, we compared the effects of the physical presence of the parasite Amoebophrya sp. and exposure to waterborne cues from cultures infected with this parasite, on gene expression by the toxic dinoflagellates, Alexandrium fundyense. Compared with control samples, a total of 14,882 Alexandrium genes were differentially expressed over the whole-parasite infection cycle at three different time points (0, 6 and 96 h). RNA sequencing analyses indicated that exposure to the parasite and parasitic waterborne cues produced significant changes in the expression levels of Alexandrium genes associated with specific metabolic pathways. The observed upregulation of genes associated with glycolysis, the tricarboxylic acid cycle, fatty acid β-oxidation, oxidative phosphorylation and photosynthesis suggests that parasite infection increases the energy demand of the host. The observed upregulation of genes correlated with signal transduction indicates that Alexandrium could be sensitized by parasite attacks. This response might prime the defence of the host, as indicated by the increased expression of several genes associated with defence and stress. Our findings provide a molecular overview of the response of a dinoflagellate to parasite infection. PMID:26841307

  2. Suspended Alexandrium spp. hypnozygote cysts in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Kirn, Sarah L.; Townsend, David W.; Pettigrew, Neal R.

    2005-09-01

    The life cycle of dinoflagellates of the genus Alexandrium includes sexual reproduction followed by the formation of a dormant hypnozygote cyst, which serves as a resting stage. Negatively buoyant cysts purportedly fall to the benthos where they undergo a mandatory period of quiescence. Previous reports of cysts in the surficial sediments of the Gulf of Maine, where Alexandrium blooms are well documented, show a broad distribution of cysts, with highest concentrations generally in sediments below 100 m depth. We report here an exploration of cysts suspended in the water column, where they would be better positioned to inoculate springtime Alexandrium populations. During cruises in February, April, and June of 2000, water samples were collected at depths just off the bottom (within 5 m), at the top of the bottom nepheloid layer, and near the surface (1 m) and examined for cyst concentrations. Suspended cysts were found throughout the Gulf of Maine and westernmost Bay of Fundy. Planktonic cyst densities were generally greater in near-bottom and top of the bottom nepheloid layer samples than in near-surface water samples; densities were of the order of 10 2 cysts m -3 in surface waters, and 10 2-10 3 cysts m -3 at near-bottom depths. Temporally, they were most abundant in February and least abundant in April. Reports by earlier workers of cysts in the underlying sediments were on the order of 10 3 cysts cm -3. We present calculations that demonstrate the likelihood of cyst resuspension from bottom sediments forced by swell and tidal currents, and propose that such resuspended cysts are important in inoculating the seasonal bloom. We estimate that suspended cysts may contribute significantly to the annual vegetative cell population in the Gulf of Maine.

  3. The death mechanism of the harmful algal bloom species Alexandrium tamarense induced by algicidal bacterium Deinococcus sp. Y35

    PubMed Central

    Li, Yi; Zhu, Hong; Lei, Xueqian; Zhang, Huajun; Cai, Guanjing; Chen, Zhangran; Fu, Lijun; Xu, Hong; Zheng, Tianling

    2015-01-01

    Harmful algal blooms (HABs) cause a variety of deleterious effects on aquatic ecosystems, especially the toxic dinoflagellate Alexandrium tamarense, which poses a serious threat to marine economic and human health based on releasing paralytic shellfish poison into the environment. The algicidal bacterium Deinococcus sp. Y35 which can induce growth inhibition on A. tamarense was used to investigate the functional mechanism. The growth status, reactive oxygen species (ROS) content, photosynthetic system and the nuclear system of algal cells were determined under algicidal activity. A culture of strain Y35 not only induced overproduction of ROS in algal cells within only 0.5 h of treatment, also decrease the total protein content as well as the response of the antioxidant enzyme. Meanwhile, lipid peroxidation was induced and cell membrane integrity was lost. Photosynthetic pigments including chlorophyll a and carotenoid decreased along with the photosynthetic efficiency being significantly inhibited. At the same time, photosynthesis-related gene expression showed down-regulation. More than, the destruction of cell nuclear structure and inhibition of proliferating cell nuclear antigen (PCNA) related gene expression were confirmed. The potential functional mechanism of the algicidal bacterium on A. tamarense was investigated and provided a novel viewpoint which could be used in HABs control. PMID:26441921

  4. Exposure to the Paralytic Shellfish Toxin Producer Alexandrium catenella Increases the Susceptibility of the Oyster Crassostrea gigas to Pathogenic Vibrios.

    PubMed

    Abi-Khalil, Celina; Lopez-Joven, Carmen; Abadie, Eric; Savar, Veronique; Amzil, Zouher; Laabir, Mohamed; Rolland, Jean-Luc

    2016-01-01

    The multifactorial etiology of massive Crassostrea gigas summer mortalities results from complex interactions between oysters, opportunistic pathogens and environmental factors. In a field survey conducted in 2014 in the Mediterranean Thau Lagoon (France), we evidenced that the development of the toxic dinoflagellate Alexandrium catenella, which produces paralytic shellfish toxins (PSTs), was concomitant with the accumulation of PSTs in oyster flesh and the occurrence of C. gigas mortalities. In order to investigate the possible role of toxic algae in this complex disease, we experimentally infected C. gigas oyster juveniles with Vibrio tasmaniensis strain LGP32, a strain associated with oyster summer mortalities, after oysters were exposed to Alexandrium catenella. Exposure of oysters to A. catenella significantly increased the susceptibility of oysters to V. tasmaniensis LGP32. On the contrary, exposure to the non-toxic dinoflagellate Alexandrium tamarense or to the haptophyte Tisochrysis lutea used as a foraging alga did not increase susceptibility to V. tasmaniensis LGP32. This study shows for the first time that A. catenella increases the susceptibility of Crassostrea gigas to pathogenic vibrios. Therefore, in addition to complex environmental factors explaining the mass mortalities of bivalve mollusks, feeding on neurotoxic dinoflagellates should now be considered as an environmental factor that potentially increases the severity of oyster mortality events. PMID:26784228

  5. Exposure to the Paralytic Shellfish Toxin Producer Alexandrium catenella Increases the Susceptibility of the Oyster Crassostrea gigas to Pathogenic Vibrios

    PubMed Central

    Abi-Khalil, Celina; Lopez-Joven, Carmen; Abadie, Eric; Savar, Veronique; Amzil, Zouher; Laabir, Mohamed; Rolland, Jean-Luc

    2016-01-01

    The multifactorial etiology of massive Crassostrea gigas summer mortalities results from complex interactions between oysters, opportunistic pathogens and environmental factors. In a field survey conducted in 2014 in the Mediterranean Thau Lagoon (France), we evidenced that the development of the toxic dinoflagellate Alexandrium catenella, which produces paralytic shellfish toxins (PSTs), was concomitant with the accumulation of PSTs in oyster flesh and the occurrence of C. gigas mortalities. In order to investigate the possible role of toxic algae in this complex disease, we experimentally infected C. gigas oyster juveniles with Vibrio tasmaniensis strain LGP32, a strain associated with oyster summer mortalities, after oysters were exposed to Alexandrium catenella. Exposure of oysters to A. catenella significantly increased the susceptibility of oysters to V. tasmaniensis LGP32. On the contrary, exposure to the non-toxic dinoflagellate Alexandrium tamarense or to the haptophyte Tisochrysis lutea used as a foraging alga did not increase susceptibility to V. tasmaniensis LGP32. This study shows for the first time that A. catenella increases the susceptibility of Crassostrea gigas to pathogenic vibrios. Therefore, in addition to complex environmental factors explaining the mass mortalities of bivalve mollusks, feeding on neurotoxic dinoflagellates should now be considered as an environmental factor that potentially increases the severity of oyster mortality events. PMID:26784228

  6. Nutrient conditions during Alexandrium fundyense blooms in the western Gulf of Maine, USA

    NASA Astrophysics Data System (ADS)

    Love, Rebecca C.; Loder, Theodore C.; Keafer, Bruce A.

    2005-09-01

    Inorganic nutrients and organic nitrogen were measured in April-June of 1998 and 2000 near Casco Bay, Maine and the adjacent coastal waters as part of the Ecology and Oceanography of Harmful Algal Blooms—Gulf of Maine (ECOHAB-GOM) program. The samples were collected during development of toxic Alexandrium fundyense blooms [ Keafer, B.A., Churchill, J.H., Anderson, D.M., 2005. Blooms of the toxic dinoflagellate, Alexandrium fundyense in the Casco Bay region of the western Gulf of Maine: advection from offshore source populations and interactions with the Kennebec River plume. Deep Sea Research II, this issue [ doi:10.1016/j.dsr2.2005.06.017

  7. Evolution and Distribution of Saxitoxin Biosynthesis in Dinoflagellates

    PubMed Central

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

    2013-01-01

    Numerous species of marine dinoflagellates synthesize the potent environmental neurotoxic alkaloid, saxitoxin, the agent of the human illness, paralytic shellfish poisoning. In addition, certain freshwater species of cyanobacteria also synthesize the same toxic compound, with the biosynthetic pathway and genes responsible being recently reported. Three theories have been postulated to explain the origin of saxitoxin in dinoflagellates: The production of saxitoxin by co-cultured bacteria rather than the dinoflagellates themselves, convergent evolution within both dinoflagellates and bacteria and horizontal gene transfer between dinoflagellates and bacteria. The discovery of cyanobacterial saxitoxin homologs in dinoflagellates has enabled us for the first time to evaluate these theories. Here, we review the distribution of saxitoxin within the dinoflagellates and our knowledge of its genetic basis to determine the likely evolutionary origins of this potent neurotoxin. PMID:23966031

  8. Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4

    PubMed Central

    Durán-Riveroll, Lorena M.; Cembella, Allan D.; Band-Schmidt, Christine J.; Bustillos-Guzmán, José J.; Correa-Basurto, José

    2016-01-01

    Saxitoxin (STX) and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav), impeding passage of Na+ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs. PMID:27164145

  9. Docking Simulation of the Binding Interactions of Saxitoxin Analogs Produced by the Marine Dinoflagellate Gymnodinium catenatum to the Voltage-Gated Sodium Channel Nav1.4.

    PubMed

    Durán-Riveroll, Lorena M; Cembella, Allan D; Band-Schmidt, Christine J; Bustillos-Guzmán, José J; Correa-Basurto, José

    2016-01-01

    Saxitoxin (STX) and its analogs are paralytic alkaloid neurotoxins that block the voltage-gated sodium channel pore (Nav), impeding passage of Na⁺ ions into the intracellular space, and thereby preventing the action potential in the peripheral nervous system and skeletal muscle. The marine dinoflagellate Gymnodinium catenatum produces an array of such toxins, including the recently discovered benzoyl analogs, for which the mammalian toxicities are essentially unknown. We subjected STX and its analogs to a theoretical docking simulation based upon two alternative tri-dimensional models of the Nav1.4 to find a relationship between the binding properties and the known mammalian toxicity of selected STX analogs. We inferred hypothetical toxicities for the benzoyl analogs from the modeled values. We demonstrate that these toxins exhibit different binding modes with similar free binding energies and that these alternative binding modes are equally probable. We propose that the principal binding that governs ligand recognition is mediated by electrostatic interactions. Our simulation constitutes the first in silico modeling study on benzoyl-type paralytic toxins and provides an approach towards a better understanding of the mode of action of STX and its analogs. PMID:27164145

  10. Improvement of Omega-3 Docosahexaenoic Acid Production by Marine Dinoflagellate Crypthecodinium cohnii Using Rapeseed Meal Hydrolysate and Waste Molasses as Feedstock

    PubMed Central

    Gong, Yangmin; Liu, Jiao; Jiang, Mulan; Liang, Zhuo; Jin, Hu; Hu, Xiaojia; Wan, Xia; Hu, Chuanjiong

    2015-01-01

    Rapeseed meal and waste molasses are two important agro-industrial by-products which are produced in large quantities. In this study, solid state fermentation and fungal autolysis were performed to produce rapeseed meal hydrolysate (RMH) using fungal strains of Aspergillus oryzae, Penicillium oxalicum and Neurospora crassa. The hydrolysate was used as fermentation feedstock for heterotrophic growth of microalga Crypthecodinium cohnii that produce docosahexaenoic acid (DHA). The addition of waste molasses as a supplementary carbon source greatly increased the biomass and DHA yield. In the batch fermentations using media composed of diluted RMH (7%) and 1-9% waste molasses, the highest biomass concentration and DHA yield reached 3.43 g/L and 8.72 mg/L, respectively. The algal biomass produced from RMH and molasses medium also had a high percentage of DHA (22-34%) in total fatty acids similar to that of commercial algal biomass. RMH was shown to be rich in nitrogen supply comparable to the commercial nitrogen feedstock like yeast extract. Using RMH as sole nitrogen source, waste molasses excelled other carbon sources and produced the highest concentration of biomass. This study suggests that DHA production of the marine dinoflagellate C. cohnii could be greatly improved by concomitantly using the cheap by-products rapeseed meal hydrolysate and molasses as alternative feedstock. PMID:25942565

  11. Improvement of Omega-3 Docosahexaenoic Acid Production by Marine Dinoflagellate Crypthecodinium cohnii Using Rapeseed Meal Hydrolysate and Waste Molasses as Feedstock.

    PubMed

    Gong, Yangmin; Liu, Jiao; Jiang, Mulan; Liang, Zhuo; Jin, Hu; Hu, Xiaojia; Wan, Xia; Hu, Chuanjiong

    2015-01-01

    Rapeseed meal and waste molasses are two important agro-industrial by-products which are produced in large quantities. In this study, solid state fermentation and fungal autolysis were performed to produce rapeseed meal hydrolysate (RMH) using fungal strains of Aspergillus oryzae, Penicillium oxalicum and Neurospora crassa. The hydrolysate was used as fermentation feedstock for heterotrophic growth of microalga Crypthecodinium cohnii that produce docosahexaenoic acid (DHA). The addition of waste molasses as a supplementary carbon source greatly increased the biomass and DHA yield. In the batch fermentations using media composed of diluted RMH (7%) and 1-9% waste molasses, the highest biomass concentration and DHA yield reached 3.43 g/L and 8.72 mg/L, respectively. The algal biomass produced from RMH and molasses medium also had a high percentage of DHA (22-34%) in total fatty acids similar to that of commercial algal biomass. RMH was shown to be rich in nitrogen supply comparable to the commercial nitrogen feedstock like yeast extract. Using RMH as sole nitrogen source, waste molasses excelled other carbon sources and produced the highest concentration of biomass. This study suggests that DHA production of the marine dinoflagellate C. cohnii could be greatly improved by concomitantly using the cheap by-products rapeseed meal hydrolysate and molasses as alternative feedstock. PMID:25942565

  12. Genetic structuring and transfer of marine dinoflagellate Cochlodinium polykrikoides in Japanese and Korean coastal waters revealed by microsatellites.

    PubMed

    Nagai, S; Nishitani, G; Sakamoto, S; Sugaya, T; Lee, C K; Kim, C H; Itakura, S; Yamaguchi, M

    2009-06-01

    To determine the process of population expansion and ascertain the origin of the Sea of Japan population, in a noxious red tide forming dinoflagellate Cochlodinium polykrikoides, 13 samples, isolated from 11 different localities in Japanese and Korean coasts, were analysed using 10 polymorphic microsatellites. Analyses by nonmetric multidimensional scaling plots of pairwise F(ST), global amova, and genetic admixture analysis identified three clusters--the Sea of Japan populations, Yatsushiro Sea (Kumamoto Pref.) populations, and other populations--indicating genetic structuring of the 13 samples into three distinct populations. In the proportion of shared alleles by pairwise individuals (P(SAxy)) analyses between the Sea of Japan and the other samples, P(SAxy) was extremely low compared with that among the Sea of Japan or among other samples, indicating that a large genetic barrier has occurred between the populations. No significant relationship of isolation-by-distance patterns and almost no genetic distance were detected between pairwise samples of the Sea of Japan, although there is a maximal distance of > 600 km between samples. In addition, P(SAxy) data among the samples were extremely high compared with those among other samples, clearly showing that a large-scale transfer from west to east has occurred via the Tushima Warm Current. In the P(SAxy) data of the Seto Inland Sea and Pacific samples, individuals showing relatively high P(SAxy) were concentrated in the three areas of Nagasaki, Harima, and Mie, suggesting that frequent transfer may have occurred by human-assisted dispersal, although Nagasaki and Mie are separated by a distance of approximately 700 km. PMID:19457209

  13. Distribution of organic-walled dinoflagellate cysts in recent marine sediments from the Gulf of Tehuantepec, South Pacific of Mexico.

    NASA Astrophysics Data System (ADS)

    Vasquez-Bedoya, L. F.; de Vernal, A.; Ruiz-Fernandez, A. C.; Machain-Castillo, M. L.; Radi, T.; Hillaire-Marcel, C.

    2007-05-01

    A qualitative and quantitative study of recent organic-walled dinoflagellate dinocysts recovered in sediments has been undertaken in the coastal zone of the Gulf of Tehuantepec, Mexico. A sediment core was collected in 2004 with a Reineck-type corer using a plastic tube (7 cm i.d); and it was subsampled at 0.3 cm intervals down to 10 cm depth and then at 1 cm intervals at further depths. The 210Pb and 137Cs-derived sedimentation and mass accumulation rates at the site were found to vary from 0.033 to 0.209 cm yr-1, and from 0.05 to 0.29 g cm-2 yr-1., respectively. The cysts concentrations ranged between 477 and 2300 cysts g-1 and the cysts fluxes between 68 a 494 cysts cm-2 yr-1. Twenty-three cyst taxa were identified: Brigantedinium spp., Polysphaeridium zoharyii, Bitectatodinium spongium, Spiniferites delicatus, Quinquecuspis concreta, Echinidinium transparantum, Operculodinium centrocarpum, Selenopemphix quanta, Type Echinidinium granulatum, Echinidinium aculeatum, Protoperidinium americanum, Echinidinium delicatum, Selenopemphix nephroides, Cyst of Protoperidinum stellatum, Lingulodinium machaerophorum, Islandinium spp., Votadinium spinosum, Polykrikos kofoidii, Pentapharsodinium dalei, Tuberculodinium vancampoe, Spiniferites mirabilis, Votadinium calvum and Nematosphaeropsis labyrinthus. The assemblages included cysts of both phototrophic and heterotrophic species, with variation of their respective abundance reflecting changes in the trophic structure of the upper water mass, especially after 1950, with a decrease from ~30% to 15% of photototrophic species, likely as a response to pollution (including cultural eutrophication) created by the industrial development of the adjacent coastal zone. Brigantedinium spp., Polysphaeridium zoharyii and Bitectatodinium spongium, were the dominant species found in the core and are most likely influenced by the seasonal upwelling that characterize the study area, as indicated by the predominance of planktonic foraminiferal

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

    PubMed

    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. PMID:27011070

  15. Compositional changes in neurotoxins and their oxidative derivatives from the dinoflagellate, Karenia brevis, in seawater and marine aerosol

    PubMed Central

    Pierce, Richard H.; Henry, Michael S.; Blum, Patricia C.; Osborn, Shannon E.; Cheng, Yung-Sung; Zhou, Yue; Irvin, Clinton M.; Bourdelais, Andrea J.; Naar, Jerome; Baden, Daniel G.

    2011-01-01

    The harmful alga, Karenia brevis, produces a suite of polyether neurotoxins, brevetoxins or PbTx, that cause marine animal mortality and neurotoxic shellfish poisoning (NSP). A characteristic of K. brevis blooms is associated airborne toxins that result in severe respiratory problems. This study was undertaken to determine the composition of aerosolized brevetoxins and oxidative derivatives to which beachgoers are exposed during a K. brevis bloom. The suite of brevetoxins and derivatives in seawater is comprised of intra-cellular (IC) and extra-cellular (EC) compounds. We hypothesized that aerosolized compounds are generated primarily from EC, hydrophobic compounds in seawater by bubble-mediated transport. Thus the composition of aerosolized brevetoxins and derivatives, to which beachgoers are exposed, would reflect the EC composition of the source matrix (the local surf zone). Brevetoxins were extracted from water collected along the shore and from marine aerosols along Siesta Beach and Lido Beach in Sarasota, FL, USA, during K. brevis blooms. Water samples were further processed into IC and EC components. The primary brevetoxins observed in water and air included PbTx-1, -2, -3, -PbTx-2-carboxylic acid, and brevenal. Oxidation and/or hydrolysis products of PbTx-1, -2, -3 and -7 were also found in EC water and in aerosol, but not IC. PMID:21191552

  16. The distribution of organic-walled dinoflagellate cysts in marine surface samples of the eastern Indian Ocean in relation to environmental conditions

    NASA Astrophysics Data System (ADS)

    Hessler, I.; Young, M.; Mohtadi, M.; Lückge, A.; Behling, H.

    2012-04-01

    The eastern Indian Ocean is characterised by a complex system of surface currents that move according to the monsoon-dominated wind regime and show a strong seasonality. The Indonesian Throughflow, which originates in the northwestern and tropical Pacific and passes through the Indonesian archipelago into the Indian Ocean, is the only low-latitude oceanic connection between the Pacific and Indian Oceans and represents a key element in the global thermohaline circulation and hence the global climate system. In recent decades it has become increasingly important to understand the atmospheric and oceanographic processes involved in climate variations. Assemblages of organic-walled dinoflagellate cysts (dinocysts) from marine surface samples provide insights into the relationship between the spatial distribution of dinocysts and modern local environmental conditions (e.g. sea surface temperature, sea surface salinity, productivity). These information are of great value for the interpretation of past variations in surface water conditions. We present an extensive data-set of marine surface samples (n=116) from the Eastern Indian Ocean. The conducted Principal Component Analysis (PCA) illustrates the variation of species association between the sites and reveals a geographical affinity of the samples to the regions of (1) Western Indonesia, (2) Java, (3) the Indonesian Throughflow and (4) Western Australia including the Timor Sea. The results of the PCA further indicate the existence of two environmental gradients in the study area, a nutrient gradient increasing from Western Indonesia towards the Indonesian Throughflow region and a temperature gradient increasing from Western Australia towards Western Indonesia. The Redundancy Analysis indicates the presence of three dominating taxa in the sample set, namely Spiniferites spp., Operculodinium centrocarpum and Brigantedinium spp., and reveals significant correlations of the three dominant taxa to specific environmental

  17. Competition of bloom-forming marine phytoplankton at low nutrient concentrations.

    PubMed

    Hu, Hanhua; Zhang, Jun; Chen, Weidong

    2011-01-01

    Competition of three bloom-forming marine phytoplankton (diatom Skeletonema costatum, and dinoflagellates Prorocentrum minimum and Alexandrium tamarense) was studied through a series of multispecies cultures with different nitrate (NaNO3) and phosphate (NaH2PO4) levels and excess silicate to interpret red tide algae succession. S. costatum outgrew the other two dinoflagellates in nitrate and phosphate replete cultures with 10 micromol/L Na2SiO3. Under nitrate limited (8.82 micromol/L NaNO3) conditions, the growth of S. costatum was also dominant when phosphate concentrations were from 3.6 to 108 micromol/L. Cell density of the two dinoflagellates only increased slightly, to less than 400 and 600 cells/mL, respectively. Cell density of S. costatum decreased with time before day 12, and then increased to 4000 cells/mL (1.5 mg/L dry biomass) at NaNO3 concentrations between 88.2 and 882 micromol/L with limited phosphate (0.36 micromol/L NaH2PO4) levels. In addition, P. minimum grew well with a maximal cell density of 1690-2100 cells/mL (0.5-0.6 mg/L dry biomass). Although S. costatum initially grew fast, its cell density decreased quickly with time later in the growth phase and the two dinoflagellates were dominant under the nitrate-limited and high nitrate conditions with limited phosphate. These results indicated that the diatom was a poor competitor compared to the two dinoflagellates under limited phosphate; however, it grew well under limited nitrate when growth of the dinoflagellates was near detection limits. PMID:21793409

  18. Genome of the R-body producing marine alphaproteobacterium Labrenzia alexandrii type strain (DFL-11T)

    PubMed Central

    Fiebig, Anne; Pradella, Silke; Petersen, Jörn; Päuker, Orsola; Michael, Victoria; Lünsdorf, Heinrich; Göker, Markus; Klenk, Hans-Peter; Wagner-Döbler, Irene

    2013-01-01

    Labrenzia alexandrii Biebl et al. 2007 is a marine member of the family Rhodobacteraceae in the order Rhodobacterales, which has thus far only partially been characterized at the genome level. The bacterium is of interest because it lives in close association with the toxic dinoflagellate Alexandrium lusitanicum. Ultrastructural analysis reveals R-bodies within the bacterial cells, which are primarily known from obligate endosymbionts that trigger “killing traits” in ciliates (Paramecium spp.). Genomic traits of L. alexandrii DFL-11T are in accordance with these findings, as they include the reb genes putatively involved in R-body synthesis. Analysis of the two extrachromosomal elements suggests a role in heavy-metal resistance and exopolysaccharide formation, respectively. The 5,461,856 bp long genome with its 5,071 protein-coding and 73 RNA genes consists of one chromosome and two plasmids, and has been sequenced in the context of the Marine Microbial Initiative. PMID:24019989

  19. LIPID BIOMARKER CHARACTERIZATION OF BLOOM-RELATED DINOFLAGELLATES

    EPA Science Inventory

    Marine eukaryotic algae synthesize an array of lipids of chemotaxonomic utility that are potentially valuable in characterizing phytoplankton communities. Sterols and photopigments characteristic of dinoflagellates are rarely found in other algal classes. Long chain (C28) highly ...

  20. Genomic Insights into Processes Driving the Infection of Alexandrium tamarense by the Parasitoid Amoebophrya sp.

    PubMed Central

    Wohlrab, Sylke; Glöckner, Gernot; Guillou, Laure; John, Uwe

    2014-01-01

    The regulatory circuits during infection of dinoflagellates by their parasites are largely unknown on the molecular level. Here we provide molecular insights into these infection dynamics. Alexandrium tamarense is one of the most prominent harmful algal bloom dinoflagellates. Its pathogen, the dinoflagellate parasitoid Amoebophrya sp., has been observed to infect and control the blooms of this species. We generated a data set of transcripts from three time points (0, 6, and 96 h) during the infection of this parasite-host system. Assembly of all transcript data from the parasitoid (>900,000 reads/313 Mbp with 454/Roche next-generation sequencing [NGS]) yielded 14,455 contigs, to which we mapped the raw transcript reads of each time point of the infection cycle. We show that particular surface lectins are expressed at the beginning of the infection cycle which likely mediate the attachment to the host cell. In a later phase, signal transduction-related genes together with transmembrane transport and cytoskeleton proteins point to a high integration of processes involved in host recognition, adhesion, and invasion. At the final maturation stage, cell division- and proliferation-related genes were highly expressed, reflecting the fast cell growth and nuclear division of the parasitoid. Our molecular insights into dinoflagellate parasitoid interactions point to general mechanisms also known from other eukaryotic parasites, especially from the Alveolata. These similarities indicate the presence of fundamental processes of parasitoid infection that have remained stable throughout evolution within different phyla. PMID:25239978

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

    PubMed Central

    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

  2. Discovery of an algicidal compound from Brevibacterium sp. BS01 and its effect on a harmful algal bloom-causing species, Alexandrium tamarense

    PubMed Central

    An, Xinli; Zhang, Bangzhou; Zhang, Huajun; Li, Yi; Zheng, Wei; Yu, Zhiming; Fu, Lijun; Zheng, Tianling

    2015-01-01

    Blooms of the dinoflagellate Alexandrium tamarense have become worldwide phenomena and have detrimental impacts on aquatic ecosystems and human health. In this study, a culture supernatant of the marine actinomycete BS01 exerted a strong algicidal effect on A. tamarense (ATGD98-006). The target algicide from BS01 was separated by adsorption chromatography and identified by MALDI-TOF-MS and NMR analysis. The results suggested that the purified algicidal component corresponded to a hydrophobic compound (2-isobutoxyphenyl)amine (C10H15NO) with a molecular weight of 165 Da, which exhibited a significant algicidal effect (64.5%) on A. tamarense. After incubation in 5 μg/mL of (2-isobutoxyphenyl)amine for 24 h, the algae lost mobility and sank to the bottom of the flasks, and 56.5% of the algae cells lost vitality at a concentration of 20 μg/mL (p < 0.01) despite having intact cell profiles. Morphological analysis revealed that the cell structure of A. tamarense was altered by (2-isobutoxyphenyl)amine resulting in cytoplasm degradation and the loss of organelle integrity. The images following propidium iodide staining suggested that the algal nucleus was also severely damaged and eventually degraded due to exposure to the algicidal compound. All of the results indicate that (2-isobutoxyphenyl)amine from the actinomycete might be a candidate for the control of bloom-forming A. tamarense. PMID:26594205

  3. Discovery of an algicidal compound from Brevibacterium sp. BS01 and its effect on a harmful algal bloom-causing species, Alexandrium tamarense.

    PubMed

    An, Xinli; Zhang, Bangzhou; Zhang, Huajun; Li, Yi; Zheng, Wei; Yu, Zhiming; Fu, Lijun; Zheng, Tianling

    2015-01-01

    Blooms of the dinoflagellate Alexandrium tamarense have become worldwide phenomena and have detrimental impacts on aquatic ecosystems and human health. In this study, a culture supernatant of the marine actinomycete BS01 exerted a strong algicidal effect on A. tamarense (ATGD98-006). The target algicide from BS01 was separated by adsorption chromatography and identified by MALDI-TOF-MS and NMR analysis. The results suggested that the purified algicidal component corresponded to a hydrophobic compound (2-isobutoxyphenyl)amine (C10H15NO) with a molecular weight of 165 Da, which exhibited a significant algicidal effect (64.5%) on A. tamarense. After incubation in 5 μg/mL of (2-isobutoxyphenyl)amine for 24 h, the algae lost mobility and sank to the bottom of the flasks, and 56.5% of the algae cells lost vitality at a concentration of 20 μg/mL (p < 0.01) despite having intact cell profiles. Morphological analysis revealed that the cell structure of A. tamarense was altered by (2-isobutoxyphenyl)amine resulting in cytoplasm degradation and the loss of organelle integrity. The images following propidium iodide staining suggested that the algal nucleus was also severely damaged and eventually degraded due to exposure to the algicidal compound. All of the results indicate that (2-isobutoxyphenyl)amine from the actinomycete might be a candidate for the control of bloom-forming A. tamarense. PMID:26594205

  4. Combined heat shock protein 90 and ribosomal RNA sequence phylogeny supports multiple replacements of dinoflagellate plastids.

    PubMed

    Shalchian-Tabrizi, Kamran; Minge, Marianne A; Cavalier-Smith, Tom; Nedreklepp, Joachim M; Klaveness, Dag; Jakobsen, Kjetill S

    2006-01-01

    Dinoflagellates harbour diverse plastids obtained from several algal groups, including haptophytes, diatoms, cryptophytes, and prasinophytes. Their major plastid type with the accessory pigment peridinin is found in the vast majority of photosynthetic species. Some species of dinoflagellates have other aberrantly pigmented plastids. We sequenced the nuclear small subunit (SSU) ribosomal RNA (rRNA) gene of the "green" dinoflagellate Gymnodinium chlorophorum and show that it is sister to Lepidodinium viride, indicating that their common ancestor obtained the prasinophyte (or other green alga) plastid in one event. As the placement of dinoflagellate species that acquired green algal or haptophyte plastids is unclear from small and large subunit (LSU) rRNA trees, we tested the usefulness of the heat shock protein (Hsp) 90 gene for dinoflagellate phylogeny by sequencing it from four species with aberrant plastids (G. chlorophorum, Karlodinium micrum, Karenia brevis, and Karenia mikimotoi) plus Alexandrium tamarense, and constructing phylogenetic trees for Hsp90 and rRNAs, separately and together. Analyses of the Hsp90 and concatenated data suggest an ancestral origin of the peridinin-containing plastid, and two independent replacements of the peridinin plastid soon after the early radiation of the dinoflagellates. Thus, the Hsp90 gene seems to be a promising phylogenetic marker for dinoflagellate phylogeny. PMID:16677346

  5. Dinoflagellates, a new proxy for evidencing (paleo)tsunamis

    NASA Astrophysics Data System (ADS)

    Popescu, S.; Do Couto, D.; Suc, J.; Gorini, C.

    2012-12-01

    As a preliminary investigation, dinoflagellates have been searched in the Sri Lanka tsunami deposits (2004, Sumatra earthquake). The goals of this analysis were (1) to establish if dinoflagellate cysts (marine algae) are preserved in such types of deposits, and (2) to delimit the inland flooded surface. This work was performed on only 1-2 grams of sands, which had been sterilized at 121°C to prevent any microbial activity. The analysis points out the presence of several marine dinoflagellate cysts with a poor to moderate preservation, allowing to estimate the extent of the flooded area. In addition, a sample provided two dinoflagellate thecae, an exceptional occurrence because the cellulosic form of a dinoflagellate (i.e. the theca) is generally considered as unable to be preserved within sediments. In laboratory experiments, thecae are known to persist between 2 and 72 hours, depending of the species. If we accept a possible preservation of thecae in "peculiar" conditions, their presence in a tsunami sedimentary sequence may sign a precise instant of a tsunami event. Dinoflagellates have been searched in sedimentary basins affected by intense seismic activity: the Black Sea (Quaternary) and Alboran Sea (Messinian - Zanclean), two areas marked by important environmental changes. Marine dinoflagellate cysts are recorded in the Black Sea before its Holocene connection with Mediterranean through the Bosphorus Strait. Their occurrence constitutes a robust support for tsunamis already described in the region. In Late Messinian and Early Pliocene deposits from the Sorbas and Malaga basins (Alboran Sea region), cysts and thecae of marine dinoflagellates have been evidenced for the first time, maybe in relation with possible tsunamis. This new approach is to be developed on other recent tsunami deposits in order to contribute to identify past tsunami events. One must mention that dinoflagellates may help in reconstruction of past sea-surface physical parameters (salinity

  6. Paralytic shellfish toxin content is related to genomic sxtA4 copy number in Alexandrium minutum strains.

    PubMed

    Stüken, Anke; Riobó, Pilar; Franco, José; Jakobsen, Kjetill S; Guillou, Laure; Figueroa, Rosa I

    2015-01-01

    Dinoflagellates are microscopic aquatic eukaryotes with huge genomes and an unusual cell regulation. For example, most genes are present in numerous copies and all copies seem to be obligatorily transcribed. The consequence of the gene copy number (CPN) for final protein synthesis is, however, not clear. One such gene is sxtA, the starting gene of paralytic shellfish toxin (PST) synthesis. PSTs are small neurotoxic compounds that can accumulate in the food chain and cause serious poisoning incidences when ingested. They are produced by dinoflagellates of the genera Alexandrium, Gymnodium, and Pyrodinium. Here we investigated if the genomic CPN of sxtA4 is related to PST content in Alexandrium minutum cells. SxtA4 is the 4th domain of the sxtA gene and its presence is essential for PST synthesis in dinoflagellates. We used PST and genome size measurements as well as quantitative PCR to analyze sxtA4 CPN and toxin content in 15 A. minutum strains. Our results show a strong positive correlation between the sxtA4 CPN and the total amount of PST produced in actively growing A. minutum cells. This correlation was independent of the toxin profile produced, as long as the strain contained the genomic domains sxtA1 and sxtA4. PMID:25983733

  7. Paralytic shellfish toxin content is related to genomic sxtA4 copy number in Alexandrium minutum strains

    PubMed Central

    Stüken, Anke; Riobó, Pilar; Franco, José; Jakobsen, Kjetill S.; Guillou, Laure; Figueroa, Rosa I.

    2015-01-01

    Dinoflagellates are microscopic aquatic eukaryotes with huge genomes and an unusual cell regulation. For example, most genes are present in numerous copies and all copies seem to be obligatorily transcribed. The consequence of the gene copy number (CPN) for final protein synthesis is, however, not clear. One such gene is sxtA, the starting gene of paralytic shellfish toxin (PST) synthesis. PSTs are small neurotoxic compounds that can accumulate in the food chain and cause serious poisoning incidences when ingested. They are produced by dinoflagellates of the genera Alexandrium, Gymnodium, and Pyrodinium. Here we investigated if the genomic CPN of sxtA4 is related to PST content in Alexandrium minutum cells. SxtA4 is the 4th domain of the sxtA gene and its presence is essential for PST synthesis in dinoflagellates. We used PST and genome size measurements as well as quantitative PCR to analyze sxtA4 CPN and toxin content in 15 A. minutum strains. Our results show a strong positive correlation between the sxtA4 CPN and the total amount of PST produced in actively growing A. minutum cells. This correlation was independent of the toxin profile produced, as long as the strain contained the genomic domains sxtA1 and sxtA4. PMID:25983733

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

    PubMed Central

    Bienfang, P. K.; DeFelice, S. V.; Laws, E. A.; Brand, L. E.; Bidigare, R. R.; Christensen, S.; Trapido-Rosenthal, H.; Hemscheidt, T. K.; McGillicuddy, D. J.; Anderson, D. M.; Solo-Gabriele, H. M.; Boehm, A. B.; Backer, L. C.

    2011-01-01

    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. PMID:20976073

  9. Prominent human health impacts from several marine microbes: history, ecology, and public health implications.

    PubMed

    Bienfang, P K; Defelice, S V; Laws, E A; Brand, L E; Bidigare, R R; Christensen, S; Trapido-Rosenthal, H; Hemscheidt, T K; McGillicuddy, D J; Anderson, D M; Solo-Gabriele, H M; Boehm, A B; Backer, L C

    2011-01-01

    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. PMID:20976073

  10. A new class of transcription initiation factors, intermediate between TATA box-binding proteins (TBPs) and TBP-like factors (TLFs), is present in the marine unicellular organism, the dinoflagellate Crypthecodinium cohnii.

    PubMed

    Guillebault, Delphine; Sasorith, Souphatta; Derelle, Evelyne; Wurtz, Jean-Marie; Lozano, Jean-Claude; Bingham, Scott; Tora, Laszlo; Moreau, Hervé

    2002-10-25

    Dinoflagellates are marine unicellular eukaryotes that exhibit unique features including a very low level of basic proteins bound to the chromatin and the complete absence of histones and nucleosomal structure. A cDNA encoding a protein with a strong homology to the TATA box-binding proteins (TBP) has been isolated from an expressed sequence tag library of the dinoflagellate Crypthecodinium cohnii. The typical TBP repeat signature and the amino acid motives involved in TFIIA and TFIIB interactions were conserved in this new TBP-like protein. However, the four phenylalanines known to interact with the TATA box were substituted with hydrophilic residues (His(77), Arg(94), Tyr(171), Thr(188)) as has been described for TBP-like factors (TLF)/TBP-related proteins (TRP). A phylogenetic analysis showed that cTBP is intermediate between TBP and TLF/TRP protein families, and the structural similarity of cTBP with TLF was confirmed by low affinity binding to a consensus' TATA box in an equivalent manner to that usually observed for TLFs. Six 5'-upstream gene regions of dinoflagellate genes have been analyzed and neither a TATA box nor a consensus-promoting element could be found within these different sequences. Our results showed that cTBP could bind stronger to a TTTT box sequence than to the canonical TATA box, especially at high salt concentration. Same binding results were obtained with a mutated cTBP (mcTBP), in which the four phenylalanines were restored. To our knowledge, this is the first description of a TBP-like protein in a unicellular organism, which also appears as the major form of TBP present in C. cohnii. PMID:12154093

  11. Georges Bank: A leaky incubator of Alexandrium fundyense blooms

    NASA Astrophysics Data System (ADS)

    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 104 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.

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

    PubMed Central

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

    2012-01-01

    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 104 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. PMID:24976691

  13. Use of stimulable bioluminescence from dinoflagellates as a means of detecting toxicity in the marine environment. (Reannouncement with new availability information). Professional paper

    SciTech Connect

    Lapota, D.; Moskowitz, G.; Grovhoug, J.

    1993-03-01

    Phytoplankton bioassays have been used as biological tools in assessing environmental contamination. In our laboratory, a simple bioassay has been developed which measures the light output from bioluminescence dinoflagellates for assessment of toxic effects when exposed to a single toxicant or mixture. Successful use of this type of bioassay has provided data on the acute response and has demonstrated the chronic effects, from hours up to 11 days, on dinoflagellate cells of Pyrocystis lunula and Gonyaulax polyedra upon exposure to several metals and storm drain effluent. Dinoflagellate cells were exposed to various concentrations of tributyltin chloride (TBTCI), copper (11) sulfate (CUS04), zinc sulfate (ZnSO4), or storm drain effluent. Stimulable bioluminescence was measured at each test period (3 or 4 h, 24 h, 48 h, 72 h, etc.) following setup for all assays. Cells were kept in the dark for 3 or 4 h prior to testing. Stirring the cells within the chamber stimulated maximum bioluminescence from the dinoflagellates. An IC50 (an estimated concentration that is likely to cause a 50% reduction in light output) was estimated for all assays. The trend of light reduction as a response to increasing dose level of test article was observed in all assays. A reduction in light output was measured from cells exposed to 1.6, 4.2, and 12.8 ug/L TBTCI. The IC50 decreased from 8.5 ug/L at 120 h to 3.0 ug/L at 264 h. The cells exposed to 6.25%, 12.5%, and 25.0% storm drain effluent exhibited a statistically significant (P=0.05) reduction in light output in as little as 3 h exposure....Plankton, Oceanography, Bioluminescence.

  14. 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: 1. Toxin levels

    PubMed Central

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

    2014-01-01

    As part of the NOAA ECOHAB funded Gulf of Maine Toxicity (GOMTOX)1 project, we determined Alexandrium fundyense abundance, paralytic shellfish poisoning (PSP) toxin composition, and concentration in quantitatively-sampled size-fractionated (20–64, 64–100, 100–200, 200–500, and > 500 μm) particulate water samples, and the community composition of potential grazers of A. fundyense in these size fractions, at multiple depths (typically 1, 10, 20 m, and near-bottom) during 10 large-scale sampling cruises during the A. fundyense bloom season (May–August) in the coastal Gulf of Maine and on Georges Bank in 2007, 2008, and 2010. Our findings were as follows: (1) when all sampling stations and all depths were summed by year, the majority (94% ± 4%) of total PSP toxicity was contained in the 20–64 μm size fraction; (2) when further analyzed by depth, the 20–64 μm size fraction was the primary source of toxin for 97% of the stations and depths samples over three years; (3) overall PSP toxin profiles were fairly consistent during the three seasons of sampling with gonyautoxins (1, 2, 3, and 4) dominating (90.7% ± 5.5%), followed by the carbamate toxins saxitoxin (STX) and neosaxitoxin (NEO) (7.7% ± 4.5%), followed by n-sulfocarbamoyl toxins (C1 and 2, GTX5) (1.3% ± 0.6%), followed by all decarbamoyl toxins (dcSTX, dcNEO, dcGTX2&3) (< 1%), although differences were noted between PSP toxin compositions for nearshore coastal Gulf of Maine sampling stations compared to offshore Georges Bank sampling stations for 2 out of 3 years; (4) surface cell counts of A. fundyense were a fairly reliable predictor of the presence of toxins throughout the water column; and (5) nearshore surface cell counts of A. fundyense in the coastal Gulf of Maine were not a reliable predictor of A. fundyense populations offshore on Georges Bank for 2 out of the 3 years sampled. PMID:25076816

  15. Bioluminescent response of individual dinoflagellate cells to hydrodynamic stress measured with millisecond resolution in a microfluidic device.

    PubMed

    Latz, Michael I; Bovard, Michelle; VanDelinder, Virginia; Segre, Enrico; Rohr, Jim; Groisman, Alex

    2008-09-01

    Dinoflagellate bioluminescence serves as a model system for examining mechanosensing by suspended motile unicellular organisms. The response latency, i.e. the delay time between the mechanical stimulus and luminescent response, provides information about the mechanotransduction and signaling process, and must be accurately known for dinoflagellate bioluminescence to be used as a flow visualization tool. This study used a novel microfluidic device to measure the response latency of a large number of individual dinoflagellates with a resolution of a few milliseconds. Suspended cells of several dinoflagellate species approximately 35 microm in diameter were directed through a 200 microm deep channel to a barrier with a 15 microm clearance impassable to the cells. Bioluminescence was stimulated when cells encountered the barrier and experienced an abrupt increase in hydrodynamic drag, and was imaged using high numerical aperture optics and a high-speed low-light video system. The average response latency for Lingulodinium polyedrum strain HJ was 15 ms (N>300 cells) at the three highest flow rates tested, with a minimum latency of 12 ms. Cells produced multiple flashes with an interval as short as 5 ms between individual flashes, suggesting that repeat stimulation involved a subset of the entire intracellular signaling pathway. The mean response latency for the dinoflagellates Pyrodinium bahamense, Alexandrium monilatum and older and newer isolates of L. polyedrum ranged from 15 to 22 ms, similar to the latencies previously determined for larger dinoflagellates with different morphologies, possibly reflecting optimization of dinoflagellate bioluminescence as a rapid anti-predation behavior. PMID:18723546

  16. The Vitamin B1 and B12 Required by the Marine Dinoflagellate Lingulodinium polyedrum Can be Provided by its Associated Bacterial Community in Culture.

    PubMed

    Cruz-López, Ricardo; Maske, Helmut

    2016-01-01

    In this study we established the B1 and B12 vitamin requirement of the dinoflagellate Lingulodinium polyedrum and the vitamin supply by its associated bacterial community. In previous field studies the B1 and B12 demand of this species was suggested but not experimentally verified. When the axenic vitamin un-supplemented culture (B-ns) of L. polyedrum was inoculated with a coastal bacterial community, the dinoflagellate's vitamin growth limitation was overcome, reaching the same growth rates as the culture growing in vitamin B1B7B12-supplemented (B-s) medium. Measured B12 concentrations in the B-s and B-ns cultures were both higher than typical coastal concentrations and B12 in the B-s culture was higher than in the B-ns culture. In both B-s and B-ns cultures, the probability of dinoflagellate cells having bacteria attached to the cell surface was similar and in both cultures an average of six bacteria were attached to each dinoflagellate cell. In the B-ns culture the free bacterial community showed significantly higher cell abundance suggesting that unattached bacteria supplied the vitamins. The fluorescence in situ hybridization (FISH) protocol allowed the quantification and identification of three bacterial groups in the same samples of the free and attached epibiotic bacteria for both treatments. The relative composition of these groups was not significantly different and was dominated by Alphaproteobacteria (>89%). To complement the FISH counts, 16S rDNA sequencing targeting the V3-V4 regions was performed using Illumina-MiSeq technology. For both vitamin amendments, the dominant group found was Alphaproteobacteria similar to FISH, but the percentage of Alphaproteobacteria varied between 50 and 95%. Alphaproteobacteria were mainly represented by Marivita sp., a member of the Roseobacter clade, followed by the Gammaproteobacterium Marinobacter flavimaris. Our results show that L. polyedrum is a B1 and B12 auxotroph, and acquire both vitamins from the associated

  17. Direct and fast detection of Alexandrium minutum algae by using high frequency microbalance.

    PubMed

    Sousa, Célia; Compère, Chantal; Dreanno, Catherine; Crassous, Marie-Pierre; Gas, Fabienne; Baus, Beatrice; Perrot, Hubert

    2014-09-01

    In this paper, a simple detection of a toxic algae, Alexandrium minutum, was developed using highly sensitive quartz crystal microbalance. In terms of performance, compared with other conventional analytical tools, the main interest of our immunosensor is based on a fast and direct detection of these living cells. This system requires the use of one monoclonal antibody directed against the surface antigen of A. minutum. We demonstrate that the whole living and motile algae are caught and detected. The high specificity of the biosensor is also demonstrated by testing several other dinoflagellate species. The frequency shift is correlated to the A. minutum cell concentration. This simple system is potentially promising for environmental monitoring purposes. PMID:24927989

  18. The Vitamin B1 and B12 Required by the Marine Dinoflagellate Lingulodinium polyedrum Can be Provided by its Associated Bacterial Community in Culture

    PubMed Central

    Cruz-López, Ricardo; Maske, Helmut

    2016-01-01

    In this study we established the B1 and B12 vitamin requirement of the dinoflagellate Lingulodinium polyedrum and the vitamin supply by its associated bacterial community. In previous field studies the B1 and B12 demand of this species was suggested but not experimentally verified. When the axenic vitamin un-supplemented culture (B-ns) of L. polyedrum was inoculated with a coastal bacterial community, the dinoflagellate’s vitamin growth limitation was overcome, reaching the same growth rates as the culture growing in vitamin B1B7B12-supplemented (B-s) medium. Measured B12 concentrations in the B-s and B-ns cultures were both higher than typical coastal concentrations and B12 in the B-s culture was higher than in the B-ns culture. In both B-s and B-ns cultures, the probability of dinoflagellate cells having bacteria attached to the cell surface was similar and in both cultures an average of six bacteria were attached to each dinoflagellate cell. In the B-ns culture the free bacterial community showed significantly higher cell abundance suggesting that unattached bacteria supplied the vitamins. The fluorescence in situ hybridization (FISH) protocol allowed the quantification and identification of three bacterial groups in the same samples of the free and attached epibiotic bacteria for both treatments. The relative composition of these groups was not significantly different and was dominated by Alphaproteobacteria (>89%). To complement the FISH counts, 16S rDNA sequencing targeting the V3–V4 regions was performed using Illumina-MiSeq technology. For both vitamin amendments, the dominant group found was Alphaproteobacteria similar to FISH, but the percentage of Alphaproteobacteria varied between 50 and 95%. Alphaproteobacteria were mainly represented by Marivita sp., a member of the Roseobacter clade, followed by the Gammaproteobacterium Marinobacter flavimaris. Our results show that L. polyedrum is a B1 and B12 auxotroph, and acquire both vitamins from the

  19. Spatial distribution and viability of Alexandrium tamarense resting cysts in surface sediments from the St. Lawrence Estuary, Eastern Canada

    NASA Astrophysics Data System (ADS)

    Gracia, Stéphanie; Roy, Suzanne; Starr, Michel

    2013-04-01

    The dinoflagellate Alexandrium tamarense Group 1 (as defined by Lilly et al., 2007) is responsible for recurrent outbreaks of paralytic shellfish poisoning (PSP) in the St. Lawrence Estuary (SLE), Eastern Canada. In August 2008, a major bloom of A. tamarense developed in the SLE and caused major mortality of fish, seabirds and marine mammals notably in the vicinity of a marine park. Eleven months later, surface (0-5 cm) and deeper (5-10 cm) sediments were sampled to determine resting cysts concentrations, locate prospective cyst seedbeds and examine if these had changed following this major bloom. This information is thought to be important to understand inter-annual patterns in algal toxicity, cyst abundance being a good predictor of subsequent bloom magnitude in some regions. Surface cyst distribution was heterogeneous and it confirmed the location of the cyst seedbed previously reported on the north shore near the Manicouagan/aux-Outardes Rivers (>500 cysts cm-3). A zone of cyst accumulation was also observed on the south shore of the SLE (maximum of 1200 cysts cm-3), with higher concentrations relative to previous cyst mapping in the 1980s. A mismatch was observed between the zones with high surface cyst concentrations and those where the highest PSP toxins were detected (used as a proxy for vegetative cells in the water column). Cyst concentrations were negatively correlated with PSP levels from the same sites, suggesting that cysts were formed and deposited away from the major sites of toxicity. Deposition likely took place near the end of the bloom, once it had reached the eastern boundary of the SLE. PSP toxicity was worse near the peak of the bloom, which occurred westward of this region. This highlights the dynamic behaviour of local blooms, influenced by the estuarine and mesoscale circulation. Interestingly, the major bloom of August 2008 was not followed by particularly large cyst deposition or by any major bloom in 2009 in this region. Cyst viability

  20. Viable cell sorting of dinoflagellates by multi-parametric flow cytometry.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electronic cell sorting for isolation and culture of dinoflagellates and other marine eukaryotic phytoplankton was compared to the traditional method of manually picking of cells using a micropipette. Trauma to electronically sorted cells was not a limiting factor as fragile dinoflagellates, such a...

  1. Alexandrium minutum resting cyst distribution dynamics in a confined site

    NASA Astrophysics Data System (ADS)

    Anglès, Sílvia; Jordi, Antoni; Garcés, Esther; Basterretxea, Gotzon; Palanques, Albert

    2010-02-01

    The life cycle of the toxic dinoflagellate Alexandrium minutum consists of an asexual stage, characterized by motile vegetative cells, and a sexual stage, a resting cyst that once formed remains dormant in the sediment. Insight into the factors that determine the distribution and abundance of resting cysts is essential to understanding the dynamics of the vegetative phase. In investigations carried out between January 2005 and January 2008 in Arenys de Mar harbor (northwestern Mediterranean Sea), the spatial and temporal distribution patterns of A. minutum resting cysts and of the sediments were studied during different bloom stages of the vegetative population. Maximum cyst abundance was recorded mainly in the innermost part of the harbor while the lowest abundance always occurred near the harbor entrance, consistent with the distribution of silt-clay sediment fractions. The tendency of cysts in sediments to increase after bloom periods was clearly associated with new cyst formation, while cyst abundance decreased during non-bloom periods. Exceptions to this trend were observed in stations dominated by the deposition of coarse sediments. High correlation between the presence of cysts and clays during non-bloom periods indicates that cysts behave as passive sediment particles and are influenced by the same hydrodynamic processes as clays. In Arenys de Mar, the main physical forcing affecting sediment resuspension is the seiche, which was studied using in situ measurements and numerical models to interpret the observed distribution patterns. During non-bloom periods, cyst losses were smaller when the seiche was more active and at the station where the seiche-induced current was larger. Thus, seiche-forced resuspension appears to reduce cyst losses by reallocating cysts back to the sediment surface such that their burial in the sediment is avoided. The observed vertical profiles of the cysts were consistent with this process.

  2. Evolution of Saxitoxin Synthesis in Cyanobacteria and Dinoflagellates

    PubMed Central

    Hackett, Jeremiah D.; Wisecaver, Jennifer H.; Brosnahan, Michael L.; Kulis, David M.; Anderson, Donald M.; Bhattacharya, Debashish; Plumley, F. Gerald; Erdner, Deana L.

    2013-01-01

    Dinoflagellates produce a variety of toxic secondary metabolites that have a significant impact on marine ecosystems and fisheries. Saxitoxin (STX), the cause of paralytic shellfish poisoning, is produced by three marine dinoflagellate genera and is also made by some freshwater cyanobacteria. Genes involved in STX synthesis have been identified in cyanobacteria but are yet to be reported in the massive genomes of dinoflagellates. We have assembled comprehensive transcriptome data sets for several STX-producing dinoflagellates and a related non-toxic species and have identified 265 putative homologs of 13 cyanobacterial STX synthesis genes, including all of the genes directly involved in toxin synthesis. Putative homologs of four proteins group closely in phylogenies with cyanobacteria and are likely the functional homologs of sxtA, sxtG, and sxtB in dinoflagellates. However, the phylogenies do not support the transfer of these genes directly between toxic cyanobacteria and dinoflagellates. SxtA is split into two proteins in the dinoflagellates corresponding to the N-terminal portion containing the methyltransferase and acyl carrier protein domains and a C-terminal portion with the aminotransferase domain. Homologs of sxtB and N-terminal sxtA are present in non-toxic strains, suggesting their functions may not be limited to saxitoxin production. Only homologs of the C-terminus of sxtA and sxtG were found exclusively in toxic strains. A more thorough survey of STX+ dinoflagellates will be needed to determine if these two genes may be specific to SXT production in dinoflagellates. The A. tamarense transcriptome does not contain homologs for the remaining STX genes. Nevertheless, we identified candidate genes with similar predicted biochemical activities that account for the missing functions. These results suggest that the STX synthesis pathway was likely assembled independently in the distantly related cyanobacteria and dinoflagellates, although using some

  3. LIPID BIOMARKER CHARACTERIZATION OF BLOOM-RELATED DINOFLAGELLATES AND OTHER EUKARYOTIC ALGAE

    EPA Science Inventory

    Marine eukaryotic algae synthesize an array of lipids of chemotaxonomic utility that are potentially valuable in characterizing phytoplankton communities. Sterols and photopigments characteristic of dinoflagellates are rarely found in other algal classes. Long chain (C28) highly ...

  4. Effects of salinity, pH and temperature on the re-establishment of bioluminescence and copper or SDS toxicity in the marine dinoflagellate Pyrocystis lunula using bioluminescence as an endpoint

    USGS Publications Warehouse

    Craig, J.M.; Klerks, P.L.; Heimann, K.; Waits, J.L.

    2003-01-01

    Pyrocystis lunula is a unicellular, marine, photoautotrophic, bioluminescent dinoflagellate. This organism is used in the Lumitox ?? bioassay with inhibition of bioluminescence re-establishment as the endpoint. Experiments determined if acute changes in pH, salinity, or temperature had an effect on the organisms' ability to re-establish bioluminescence, or on the bioassay's potential to detect sodium dodecyl sulfate (SDS) and copper toxicity. The re-establishment of bioluminescence itself was not very sensitive to changes in pH within the pH 6-10 range, though reducing pH from 8 to levels below 6 decreased this capacity. Increasing the pH had little effect on Cu or SDS toxicity, but decreasing the pH below 7 virtually eliminated the toxicity of either compound in the bioassay. Lowering the salinity from 33 to 27??? or less resulted in a substantial decrease in re-establishment of bioluminescence, while increasing the salinity to 43 or 48 ??? resulted in a small decline. Salinity had little influence on the bioassay's quantification of Cu toxicity, while the data showed a weak negative relationship between SDS toxicity and salinity. Re-establishment of bioluminescence showed a direct dependence on temperature, but only at 10??C did temperature have an obvious effect on the toxicity of Cu in this bioassay. ?? 2003 Elsevier Science Ltd. All rights reserved.

  5. Trophic accumulation of PSP toxins in zooplankton during Alexandrium fundyense blooms in Casco Bay, Gulf of Maine, April-June 1998. II. . Zooplankton abundance and size-fractionated community composition

    NASA Astrophysics Data System (ADS)

    Turner, Jefferson T.; Doucette, Gregory J.; Keafer, Bruce A.; Anderson, Donald M.

    2005-09-01

    During spring blooms of the toxic dinoflagellate Alexandrium fundyense in Casco Bay, Maine in 1998, we investigated vectorial intoxication of various zooplankton size fractions with PSP toxins, including zooplankton community composition from quantitative zooplankton samples (>102 μm), as well as zooplankton composition in relation to toxin levels in various size fractions (20-64, 64-100, 100-200, 200-500, >500 μm). Zooplankton abundance in 102 μm mesh samples was low (most values<10,000 animals m -3) from early April through early May, but increased to maxima in mid-June (cruise mean=121,500 animals m -3). Quantitative zooplankton samples (>102 μm) were dominated by copepod nauplii, and Oithona similis copepodites and adults at most locations except for those furthest inshore. At these inshore locations, Acartia hudsonica copepodites and adults were usually dominant. Larger copepods such as Calanus finmarchicus, Centropages typicus, and Pseudocalanus spp. were found primarily offshore, and at much lower abundances than O. similis. Rotifers, mainly present from late April to late May, were most abundant inshore. The marine cladoceran Evadne nordmani was sporadically abundant, particularly in mid-June. Microplankton in 20-64 μm size fractions was generally dominated by A. fundyense, non-toxic dinoflagellates, and tintinnids. Microplankton in 64-100 μm size fractions was generally dominated by larger non-toxic dinoflagellates, tintinnids, aloricate ciliates, and copepod nauplii, and in early May, rotifers. Some samples (23%) in the 64-100 μm size fractions contained abundant cells of A. fundyense, presumably due to sieve clogging, but most did not contain A. fundyense cells. This suggests that PSP toxin levels in those samples were due to vectorial intoxication of microzooplankters such as heterotrophic dinoflagellates, tintinnids, aloricate ciliates, rotifers, and copepod nauplii via feeding on A. fundyense cells. Dominant taxa in zooplankton fractions varied

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Bacterial diversity in toxic Alexandrium tamarense blooms off the Orkney Isles and the Firth of Forth

    NASA Astrophysics Data System (ADS)

    Wichels, Antje; Hummert, Christian; Elbrächter, Malte; Luckas, Bernd; Schütt, Christian; Gerdts, Gunnar

    2004-04-01

    The genetic diversity of the bacterial community associated with Alexandrium tamarense blooms was studied in blooms of the toxic dinoflagellates in the waters around the Orkney Isles and the Firth of Forth (Scotland). For toxin and molecular analysis of the bacterial communities associated with the toxic bloom, water samples were taken in 1998 and 1999 from A. tamarense blooms. The bacterial community structure, as determined by DGGE (denaturing gradient gel electrophoresis) showed clear differences between all three investigated size fractions (dinoflagellate-associated bacteria, attached bacteria and free-living bacteria), with high diversity within each sample. DNA sequence analysis of the dominant and most frequent DGGE bands revealed the dominance of α Proteobacteria, mainly of the Roseobacter clade, with similarities of 91-99%. Moreover, DGGE bands occurring at the same position in the gel throughout in most samples corroborate the presence of several specific α Proteobacteria of the Roseobacter clade. Overall, 500 bacteria were isolated from the bloom and partly phylogenetically analysed. They were members of two prokaryotic phyla, the Proteobacteria and the Bacteroidetes, related to Proteobacteria of the α and γ subdivisions (Alteromonas, Pseudoalteromonas and Colwellia). All bacteria were tested for the production of sodium channel blocking (SCB) toxins using mouse neuroblastoma assay. No production of SCB toxins was found and high performance liquid chromatography (HPLC) analysis confirmed these results. The content of total paralytic shellfish poisoning (PSP) toxin in the water samples, as measured within the toxic dinoflagellate blooms using HPLC, ranged from 53 to 2191 ng PSP l-1 in 1998 and from 0 to 478 ng PSP l-1 in 1999. Changes in PSP toxin content were not accompanied by changes of DGGE band patterns. We therefore presume that the bacterial groups identified in this study were not exclusively associated with toxic A. tamarense, but were

  8. Quantitative PCR Method for Enumeration of Cells of Cryptic Species of the Toxic Marine Dinoflagellate Ostreopsis spp. in Coastal Waters of Japan

    PubMed Central

    Hariganeya, Naohito; Tanimoto, Yuko; Yamaguchi, Haruo; Nishimura, Tomohiro; Tawong, Wittaya; Sakanari, Hiroshi; Yoshimatsu, Takamichi; Sato, Shinya; Preston, Christina M.; Adachi, Masao

    2013-01-01

    Monitoring of harmful algal bloom (HAB) species in coastal waters is important for assessment of environmental impacts associated with HABs. Co-occurrence of multiple cryptic species such as toxic dinoflagellate Ostreopsis species make reliable microscopic identification difficult, so the employment of molecular tools is often necessary. Here we developed new qPCR method by which cells of cryptic species can be enumerated based on actual gene number of target species. The qPCR assay targets the LSU rDNA of Ostreopsis spp. from Japan. First, we constructed standard curves with a linearized plasmid containing the target rDNA. We then determined the number of rDNA copies per cell of target species from a single cell isolated from environmental samples using the qPCR assay. Differences in the DNA recovery efficiency was calculated by adding exogenous plasmid to a portion of the sample lysate before and after DNA extraction followed by qPCR. Then, the number of cells of each species was calculated by division of the total number of rDNA copies of each species in the samples by the number of rDNA copies per cell. To test our procedure, we determined the total number of rDNA copies using environmental samples containing no target cells but spiked with cultured cells of several species of Ostreopsis. The numbers estimated by the qPCR method closely approximated total numbers of cells added. Finally, the numbers of cells of target species in environmental samples containing cryptic species were enumerated by the qPCR method and the total numbers also closely approximated the microscopy cell counts. We developed a qPCR method that provides accurate enumeration of each cryptic species in environments. This method is expected to be a powerful tool for monitoring the various HAB species that occur as cryptic species in coastal waters. PMID:23593102

  9. High Sequence Variability, Diverse Subcellular Localizations, and Ecological Implications of Alkaline Phosphatase in Dinoflagellates and Other Eukaryotic Phytoplankton

    PubMed Central

    Lin, Xin; Zhang, Huan; Cui, Yudong; Lin, Senjie

    2012-01-01

    Alkaline phosphatase (AP) is a key enzyme for phytoplankton to utilize dissolved organic phosphorus (DOP) when dissolved inorganic phosphorus is limited. While three major types of AP and their correspondingly diverse subcellular localization have been recognized in bacteria, little is known about AP in eukaryotic phytoplankton such as dinoflagellates. Here, we isolated a full-length AP cDNA from a latest-diverging dinoflagellate genus Alexandrium, and conducted comparative analyses with homologs from a relatively basal (Amphidinium carterae) and late-diverging (Karenia brevis) lineage of dinoflagellates as well as other eukaryotic algae. New data and previous studies indicate that AP is common in dinoflagellates and most other major eukaryotic groups of phytoplankton. AP sequences are more variable than many other genes studied in dinoflagellates, and are divergent among different eukaryotic phytoplankton lineages. Sequence comparison to the other characterized APs suggests that dinoflagellates and some other eukaryotic phytoplankton possess the putative AP as phoA type, but some other eukaryotic phytoplankton seem to have other types. Phylogenetic analyses based on AP amino acid sequences indicated that the “red-type” eukaryotic lineages formed a monophyletic group, suggesting a common origin of their APs. As different amino acid sequences have been found to predictably determine different spatial distribution in the cells, which may facilitate access to different pools of DOP, existing computational models were adopted to predict the subcellular localizations of putative AP in the three dinoflagellates and other eukaryotic phytoplankton. Results showed different subcellular localizations of APs in different dinoflagellates and other lineages. The linkage between AP sequence divergence, subcellular localization, and ecological niche differentiation requires rigorous experimental verification, and this study now provides a framework for such a future effort

  10. SURVEY OF THE STEROL COMPOSITION OF THE MARINE DINOFLAGELLATES KARENIA BREVIS, KARENIA MIKIMOTOI, AND KARLODINIUM MICRUM: DISTRIBUTION OF STEROLS WITHIN OTHER MEMBERS OF THE CLASS DINOPHYCEAE

    EPA Science Inventory

    The sterol composition of different marine microalgae was examined to determine the utility of sterols as biomarkers to distinguish members of various algal classes. For example, members of the class Dinophyceae possess certain 4-methyl sterols, such as dinosterol, which are rare...

  11. Homology-Driven Proteomics of Dinoflagellates with Unsequenced Genomes Using MALDI-TOF/TOF and Automated De Novo Sequencing

    PubMed Central

    Wang, Da-Zhi; Li, Cheng; Xie, Zhang-Xian; Dong, Hong-Po; Lin, Lin; Hong, Hua-Sheng

    2011-01-01

    This study developed a multilayered, gel-based, and underivatized strategy for de novo protein sequence analysis of unsequenced dinoflagellates using a MALDI-TOF/TOF mass spectrometer with the assistance of DeNovo Explorer software. MASCOT was applied as the first layer screen to identify either known or unknown proteins sharing identical peptides presented in a database. Once the confident identifications were removed after searching against the NCBInr database, the remainder was searched against the dinoflagellate expressed sequence tag database. In the last layer, those borderline and nonconfident hits were further subjected to de novo interpretation using DeNovo Explorer software. The de novo sequences passing a reliability filter were subsequently submitted to nonredundant MS-BLAST search. Using this layer identification method, 216 protein spots representing 158 unique proteins out of 220 selected protein spots from Alexandrium tamarense, a dinoflagellate with unsequenced genome, were confidently or tentatively identified by database searching. These proteins were involved in various intracellular physiological activities. This study is the first effort to develop a completely automated approach to identify proteins from unsequenced dinoflagellate databases and establishes a preliminary protein database for various physiological studies of dinoflagellates in the future. PMID:21977052

  12. A feedback mechanism to control apoptosis occurs in the digestive gland of the oyster crassostrea gigas exposed to the paralytic shellfish toxins producer Alexandrium catenella.

    PubMed

    Rolland, Jean-Luc; Medhioub, Walid; Vergnes, Agnes; Abi-Khalil, Celina; Savar, Véronique; Abadie, Eric; Masseret, Estelle; Amzil, Zouher; Laabir, Mohamed

    2014-09-01

    To better understand the effect of Paralytic Shellfish Toxins (PSTs) accumulation in the digestive gland of the Pacific oyster, Crassostrea gigas, we experimentally exposed individual oysters for 48 h to a PSTs producer, the dinoflagellate Alexandrium catenella. In comparison to the effect of the non-toxic Alexandrium tamarense, on the eight apoptotic related genes tested, Bax and BI.1 were significantly upregulated in oysters exposed 48 h to A. catenella. Among the five detoxification related genes tested, the expression of cytochrome P450 (CYP1A) was shown to be correlated with toxin concentration in the digestive gland of oysters exposed to the toxic dinoflagellate. Beside this, we observed a significant increase in ROS production, a decrease in caspase-3/7 activity and normal percentage of apoptotic cells in this tissue. Taken together, these results suggest a feedback mechanism, which may occur in the digestive gland where BI.1 could play a key role in preventing the induction of apoptosis by PSTs. Moreover, the expression of CYP1A, Bax and BI.1 were found to be significantly correlated to the occurrence of natural toxic events, suggesting that the expression of these genes together could be used as biomarker to assess the biological responses of oysters to stress caused by PSTs. PMID:25257788

  13. A Feedback Mechanism to Control Apoptosis Occurs in the Digestive Gland of the Oyster Crassostrea gigas Exposed to the Paralytic Shellfish Toxins Producer Alexandrium catenella

    PubMed Central

    Rolland, Jean-Luc; Medhioub, Walid; Vergnes, Agnes; Abi-khalil, Celina; Savar, Véronique; Abadie, Eric; Masseret, Estelle; Amzil, Zouher; Laabir, Mohamed

    2014-01-01

    To better understand the effect of Paralytic Shellfish Toxins (PSTs) accumulation in the digestive gland of the Pacific oyster, Crassostrea gigas, we experimentally exposed individual oysters for 48 h to a PSTs producer, the dinoflagellate Alexandrium catenella. In comparison to the effect of the non-toxic Alexandrium tamarense, on the eight apoptotic related genes tested, Bax and BI.1 were significantly upregulated in oysters exposed 48 h to A. catenella. Among the five detoxification related genes tested, the expression of cytochrome P450 (CYP1A) was shown to be correlated with toxin concentration in the digestive gland of oysters exposed to the toxic dinoflagellate. Beside this, we observed a significant increase in ROS production, a decrease in caspase-3/7 activity and normal percentage of apoptotic cells in this tissue. Taken together, these results suggest a feedback mechanism, which may occur in the digestive gland where BI.1 could play a key role in preventing the induction of apoptosis by PSTs. Moreover, the expression of CYP1A, Bax and BI.1 were found to be significantly correlated to the occurrence of natural toxic events, suggesting that the expression of these genes together could be used as biomarker to assess the biological responses of oysters to stress caused by PSTs. PMID:25257788

  14. Unique carotenoid lactoside, P457, in Symbiodinium sp. of dinoflagellate.

    PubMed

    Wakahama, Takahiro; Okuyama, Hidetoshi; Maoka, Takashi; Takaichi, Shinichi

    2012-01-01

    The dinoflagellates are a large group of unicellular alge in marine and fresh water. Some are an endosymbiont of marine animals. Photosynthetic dinoflagellates have peridinin, a light-harvesting carotenoid. In addition, a unique carotenoid, P457, was found from Amphinidium. The presence of P457 in Symbiodinium derived from marine animals has not been reported. We reconfirmed the molecular structure of P457, a neoxanthin-like carotenoid with an aldehyde group and a lactoside, from Symbiodinium sp. NBRC 104787 isolated from a sea anemone. In addition, we investigated the distribution of P457 and peridinin in various Symbiodinium and scleractinian coral species, and possible biosynthetic pathways of these carotenoids are proposed. PMID:22428117

  15. Isolation, purification and spectrometric analysis of PSP toxins from moraxella sp., a bacterium associated with a toxic dinoflagellate

    SciTech Connect

    Boyce, S.D.; Doucette, G.J.

    1994-12-31

    Paralytic shellfish poisoning (PSP) is a seafood intoxication syndrome caused by the injestion of shellfish contaminated with toxins produced by algae known as dinoflagellates. The PSP toxins, saxitoxin and its derivatives, act to block voltage-dependent sodium channels and can cause paralysis and even death at higher doses. It is well documented that bacteria coexist with many harmful or toxic algal species, though the exact nature of the association in relation to toxin production is unknown. Recently, the bacterium Moraxella sp. was isolated from the PSP toxin producing dinoflagellate Alexandrium tamarense. Through HPLC analysis and saxitoxin receptor binding assays performed on crude bacterial extracts, it appears that Moraxella sp. is capable of producing saxitoxin and several of its derivatives. However, physical confirmation (e.g. mass spectrometry) of these results is still needed.

  16. Cob gene pyrosequencing enables characterization of benthic dinoflagellate diversity and biogeography.

    PubMed

    Kohli, Gurjeet S; Neilan, Brett A; Brown, Mark V; Hoppenrath, Mona; Murray, Shauna A

    2014-02-01

    Dinoflagellates in marine benthic habitats living epiphytically on macroalgae are an important but highly understudied group of protists. Many produce toxins that can have severe economic impacts on marine-based economies, and improved monitoring tools are required to enhance the management of toxin-related hazards. We analysed the distribution and diversity of epibenthic dinoflagellates inhabiting eight sites in Cocos (Keeling) Islands, Papua New Guinea, and Broome and Exmouth, Western Australia. We used pyrosequencing approaches based on two DNA barcoding marker genes - 18S ribosomal RNA (rRNA) and mitochondrial cytochrome b (cob) - and compared these to an approach based on clone libraries (197 sequences) using the cob gene. Dinoflagellate sequences accounted for 133 [64 unique operational taxonomic units (OTU)] out of 10 529 18S rRNA gene sequences obtained from all samples. However, using the dinoflagellate specific assay targeting the cob gene marker, we obtained 9748 (1217 unique OTU) dinoflagellate sequences from the same environmental samples, providing the largest, to date, set of dinoflagellate cob gene sequences and reliable estimates of total dinoflagellate richness within the samples and biogeographic comparisons between samples. This study also reports the presence of potentially toxic species of the genera Gambierdiscus, Ostreopsis, Coolia, Prorocentrum and Amphidinium from the above-mentioned geographical regions. PMID:24147781

  17. Phytoplankton invasions: comments on the validity of categorizing the non-indigenous dinoflagellates and diatoms in European seas.

    PubMed

    Gómez, Fernando

    2008-04-01

    The validity of categorizing the diatoms and dinoflagellates reported in the literature as non-indigenous phytoplankton in the European Seas was investigated. Species that are synonymous are often included as separate species (Gessnerium mochimaensis=Alexandrium monilatum, Gymnodinium nagasakiense=Karenia mikimotoi, Pleurosigma simonsenii=P. planctonicum), while other species names are synonyms of cosmopolitan taxa (Prorocentrum redfieldii=P. triestinum, Pseliodinium vaubanii=Gyrodinium falcatum, Gonyaulax grindleyi=Protoceratium reticulatum, Asterionella japonica=Asterionellopsis glacialis). Epithets of an exotic etymology (i.e. japonica, sinensis, indica) imply that a cosmopolitan species may be non-indigenous, and several taxa are even considered as non-indigenous in their type locality (Alexandrium tamarense and A. pseudogoniaulax). The records of Alexandrium monilatum, A. leei and Corethron criophilum are doubtful. Cold or warm-water species expand their geographical ranges or increase their abundances to detectable levels during cooling (Coscinodiscus wailesii) or warming periods (Chaetoceros coarctatus, Proboscia indica, Pyrodinium bahamense). These are a few examples of marginal dispersal associated with climatic events instead of species introductions from remote areas. The number of non-indigenous phytoplankton species in European Seas has thus been excessively inflated. PMID:18295804

  18. Characterization of mycosporine-serine-glycine methyl ester, a major mycosporine-like amino acid from dinoflagellates: a mass spectrometry study.

    PubMed

    Carignan, Mario O; Carreto, José I

    2013-08-01

    Several unknown mycosporine-like amino acids (MAAs) have been previously isolated from some cultured species of toxic dinoflagellates of the Alexandrium genus (Dinophyceae). One of them, originally called M-333, was tentatively identified as a shinorine methyl ester, but the precise nature of this compound is still unknown. Using a high-resolution reversed-phase liquid chromatography mass spectrometry analyses (HPLC/MS), we found that natural populations of the red tide dinoflagellate Prorocentrum micans Ehrenberg showed a net dominance of M-333 together with lesser amounts of other MAAs. We also documented the isolation and characterization of this MAA from natural dinoflagellate populations and from Alexandrium tamarense (Lebour) Balech cultures. Using a comparative fragmentation study in electrospray mass spectrometry between deuterated and non-deuterated M-333 compounds and synthesized mono and dimethyl esters of shinorine, this novel compound was characterized as mycosporine-serine-glycine methyl ester, a structure confirmed by nuclear magnetic resonance. These isobaric compounds can be differentiated by their fragmentation patterns in MS(3) experiments because the extension and the specific site of the methylation changed the fragmentation pathway. PMID:27007200

  19. Spliced leader–based metatranscriptomic analyses lead to recognition of hidden genomic features in dinoflagellates

    PubMed Central

    Lin, Senjie; Zhang, Huan; Zhuang, Yunyun; Tran, Bao; Gill, John

    2010-01-01

    Environmental transcriptomics (metatranscriptomics) for a specific lineage of eukaryotic microbes (e.g., Dinoflagellata) would be instrumental for unraveling the genetic mechanisms by which these microbes respond to the natural environment, but it has not been exploited because of technical difficulties. Using the recently discovered dinoflagellate mRNA-specific spliced leader as a selective primer, we constructed cDNA libraries (e-cDNAs) from one marine and two freshwater plankton assemblages. Small-scale sequencing of the e-cDNAs revealed functionally diverse transcriptomes proven to be of dinoflagellate origin. A set of dinoflagellate common genes and transcripts of dominant dinoflagellate species were identified. Further analyses of the dataset prompted us to delve into the existing, largely unannotated dinoflagellate EST datasets (DinoEST). Consequently, all four nucleosome core histones, two histone modification proteins, and a nucleosome assembly protein were detected, clearly indicating the presence of nucleosome-like machinery long thought not to exist in dinoflagellates. The isolation of rhodopsin from taxonomically and ecotypically diverse dinoflagellates and its structural similarity and phylogenetic affinity to xanthorhodopsin suggest a common genetic potential in dinoflagellates to use solar energy nonphotosynthetically. Furthermore, we found 55 cytoplasmic ribosomal proteins (RPs) from the e-cDNAs and 24 more from DinoEST, showing that the dinoflagellate phylum possesses all 79 eukaryotic RPs. Our results suggest that a sophisticated eukaryotic molecular machine operates in dinoflagellates that likely encodes many more unsuspected physiological capabilities and, meanwhile, demonstrate that unique spliced leaders are useful for profiling lineage-specific microbial transcriptomes in situ. PMID:21041634

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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.

    2013-01-01

    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. PMID:25170191

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

    PubMed

    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. PMID:25170191

  3. Chemostratigraphic reconstruction of biofacies: Molecular evidence linking cyst-forming dinoflagellates with pre-Triassic ancestors

    NASA Astrophysics Data System (ADS)

    Moldowan, J. Michael; Dahl, Jeremy; Jacobson, Stephen R.; Huizinga, Bradley J.; Fago, Frederick J.; Shetty, Rupa; Watt, David S.; Peters, Kenneth E.

    1996-02-01

    New data from numerous detailed mass-spectrometric studies have detected triaromatic dinosteroids in Precambrian to Cenozoic rock samples. Triaromatic dinosteroids are organic geochemicals derived from dinosterols, compounds known in modern organisms to be the nearly exclusive widely occurring products of dinoflagellates. We observed the ubiquitous occurrence of these dinosteroids in 49 Late Triassic through Cretaceous marine source rocks and the absence of them in 13 Permian-Carboniferous source rocks synergistic with the dinoflagellate cyst record. However, finding dinosteroids in lower Paleozoic and Precambrian strata presents challenging results for molecular paleontologists, evolutionary biologists, palynologists, and especially for those concerned with the food web at various times of biological crisis. Other than the few species known as parasites and symbionts, many other dinoflagellate species are important as primary producers. The presence of Precambrian to Devonian triaromatic dinosteroids gives chemostratigraphic evidence of dinoflagellates (or other organisms with similar chemosynthetic capabilities) in rocks significantly older than the oldest undisputed dinoflagellate fossils (dinoflagellate cysts from the Middle Triassic, ˜ 240 Ma), and older than the putative Silurian ˜ 420 Ma) dinocyst,Arpylorus antiquus (Calandra) Sargent, from Tunisia. This systematic chemostratigraphic approach can shed light not only on lineages of dinoflagellates and their precursors, but potentially on many other lineages, especially bacteria, algae, plants, and possibly some metazoans.

  4. Comparison of three protein extraction procedures from toxic and non-toxic dinoflagellates for proteomics analysis.

    PubMed

    Jiang, Xi-Wen; Wang, Jing; Chan, Leo Lai; Lam, Paul Kwan Sing; Gu, Ji-Dong

    2015-08-01

    Three methods for extraction and preparation of high-quality proteins from both toxic and non-toxic dinoflagellates for proteomics analysis, including Trizol method, Lysis method and Tris method, were compared with the subsequent protein separation profiles using 2-D differential gel electrophoresis (2-D DIGE), Coomassie Blue and silver staining. These methods showed suitability for proteins with different pIs and molecular weights. Tris method was better for low molecular weight and low pI protein isolation; whereas both Lysis and Trizol method were better for high-molecular weight and high pI protein purification. Trizol method showed good results with Alexandrium species and Gynodinium species, and the background in gel was much clearer than the other two methods. At the same time, only Lysis method caused breaking down of the target proteins. On the other hand, Trizol method obtained higher concentration of ribulose-1,5-bisphosphate carboxylase/oxygenase proteins by Western-blotting, while Tris method was the best for peridinin-chlorophyll-protein complexes protein and T1 protein preparation. DIGE was better than Coomassie Blue and silver staining, except for some limitations, such as the high cost of the dyes, relatively short shelf life and the requirements for extensive and special image capturing equipment. Some proteins related to PSTs synthesis in dinoflagellates are hydrophobic with high molecular weight or binding on membranes and Trizol method performed better than Tris method for these proteins. The Trizol method and 2-D DIGE were effective combination for proteomics investigations of dinoflagellates. This procedure allows reliable and high recovery efficiency of proteins from dinoflagellates for better understanding on their occurrence and toxin-production for physiological and biochemical information. PMID:26197730

  5. Alexandrium fundyense cyst dynamics in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Anderson, Donald M.; Stock, Charles A.; Keafer, Bruce A.; Bronzino Nelson, Amy; Thompson, Brian; McGillicuddy, Dennis J.; Keller, Maureen; Matrai, Patricia A.; Martin, Jennifer

    2005-09-01

    The flux of cells from germinated cysts is critical in the population dynamics of many dinoflagellates. Here, data from a large-scale cyst survey are combined with surveys in other years to yield an Alexandrium fundyense cyst distribution map for the Gulf of Maine that is massive in geographic extent and cyst abundance. The benthic cyst population extends nearly 500 km alongshore. Embedded within it are several distinct accumulation zones or "seedbeds," each 3000-5000 km 2 in area. Maximal cyst abundances range from 2-20×10 6 cysts m -2. Cysts are equally or more abundant in deeper sediment layers; nearshore, cysts are fewer by a factor of 10 or more. This cyst distribution reflects sedimentary dynamics and the location of blooms in overlying surface waters. The flux of germinated cells from sediments was estimated using a combination of laboratory measurements of cyst germination and autofluorescence and observations of cyst autofluorescence in the field. These measurements constrained a germination function that, when applied to the cyst distribution map, provided an estimate of the germination inoculum for a physical/biological numerical model. In the laboratory studies, virtually all cysts incubated at different temperatures and light regimes became autofluorescent, but the rate of development was slower at lower temperatures, with no difference between light and dark incubations. Germination rates were highest at elevated temperatures, and were 2-fold greater in the light than in the dark. Laboratory and field fluorescence measurements suggest that>70% of the cysts in the top cm of sediment would germinate over a 60-90 day period in offshore waters. The combination of laboratory germination experiments and numerical modeling predicts nearly 100% germination of cysts in the top cm of sediment and resulting early season cell concentrations that are comparable in magnitude to observed cell distributions. It cannot account for late-season peaks in cell abundance

  6. Factors determining the dynamics of toxic blooms of Alexandrium minutum during a 10-year study along the shallow southwestern Mediterranean coasts

    NASA Astrophysics Data System (ADS)

    Abdenadher, Moufida; Hamza, Asma; Fekih, Wafa; Hannachi, Imen; Zouari Bellaaj, Amel; Bradai, Mohamed Nejmeddine; Aleya, Lotfi

    2012-06-01

    Many blooms of the toxic dinoflagellate Alexandrium minutum have been recorded since 1990 in the Gulf of Gabes (southwestern Mediterranean Sea). To understand the determining factors of bloom formation, we studied the distribution of A. minutum in relation to environmental factors in samples taken at shallow sandy (<1 m) beach stations and a lagoon between 1997 and 2006. This was accompanied by laboratory experiments to identify A. minutum. The species forms harmful algal blooms (HABs) in stations subjected to anthropogenic eutrophication and in confined lagoons, living under conditions of varying salinity which gives it a unique opportunity to broaden its physiological tolerance and increase its colonisation potential. Increases in phosphorus appear to be more important than nitrogen or temperature in the control of A. minutum. The stations sampled all along the coast present specific hydrographic properties (shallowness, turbulence) suggesting that factors other than temperature and nutrients influence Alexandrium distribution, the exception being Boughrara Lagoon where the species developed in accordance with published data. Our findings and their interpretations indicate that the mechanism of the sudden A. minutum blooms along the nearshore of the Gulf of Gabes was complex and differed from that of true coastal ecosystems.

  7. Differences in the toxin profiles of Alexandrium ostenfeldii (Dinophyceae) strains isolated from different geographic origins: Evidence of paralytic toxin, spirolide, and gymnodimine.

    PubMed

    Salgado, Pablo; Riobó, Pilar; Rodríguez, Francisco; Franco, José M; Bravo, Isabel

    2015-09-01

    Among toxin-producing dinoflagellates of the genus Alexandrium, Alexandrium ostenfeldii is the only species able to produce paralytic shellfish poisoning (PSP) toxins, spirolides (SPXs) and gymnodimines (GYMs). In this study we characterized and compared three A. ostenfeldii strains isolated from the Baltic, Mediterranean, and southern Chile Seas with respect to their toxin profiles, morphology, and phylogeny. Toxin analyses by HPLC-FD and LC-HRMS revealed differences in the toxin profiles of the three strains. The PSP toxin profiles of the southern Chile and Baltic strains were largely the same and included gonyautoxin (GTX)-3, GTX-2, and saxitoxin (STX), although the total PSP toxin content of the Chilean strain (105.83 ± 72.15 pg cell(-1)) was much higher than that of the Baltic strain (4.04 ± 1.93 pg cell(-1)). However, the Baltic strain was the only strain that expressed detectable amounts of analogues of GYM-A and GYM-B/-C (48.27 ± 26.12 pg GYM-A equivalents cell(-1)). The only toxin expressed by the Mediterranean strain was 13-desmethyl SPX-C (13dMeC; 2.85 ± 4.76 pg cell(-1)). Phylogenetic analysis based on the LSU rRNA showed that the studied strains belonged to distinct molecular clades. The toxin profiles determined in this study provide further evidence of the taxonomic complexity of this species. PMID:26093028

  8. Influence of Environmental Factors on the Paralytic Shellfish Toxin Content and Profile of Alexandrium catenella (Dinophyceae) Isolated from the Mediterranean Sea

    PubMed Central

    Laabir, Mohamed; Collos, Yves; Masseret, Estelle; Grzebyk, Daniel; Abadie, Eric; Savart, Véronique; Sibat, Manoella; Amzil, Zouher

    2013-01-01

    Laboratory experiments were designed to study the toxin content and profile of the Alexandrium catenella strain ACT03 (isolated from Thau Lagoon, French Mediterranean) in response to abiotic environmental factors under nutrient-replete conditions. This dinoflagellate can produce various paralytic shellfish toxins with concentrations ranging from 2.9 to 50.3 fmol/cell. The toxin profile was characterized by carbamate toxins (GTX3, GTX4 and GTX5) and N-sulfocarbamoyl toxins (C1, C2, C3 and C4). C2 dominated at 12–18 °C, but only for salinities ranging from 10 to 25 psu, whereas GTX5 became dominant at temperatures ranging from 21 to 30 °C at almost all salinities. There was no significant variation in the cellular toxin amount from 18 °C to 27 °C for salinities ranging between 30 and 40 psu. At salinities of 10 to 25 psu, the toxin concentrations always remained below 20 fmol/cell. Toxin content was stable for irradiance ranging from 10 to 70 μmol photons/m2/s then slightly increased. Overall, the toxin profile was more stable than the toxin content (fmol/cell), except for temperature and/or salinity values different from those recorded during Alexandrium blooms in Thau Lagoon. PMID:23676417

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

    PubMed

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

    2012-12-01

    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 (24h) 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 24h. 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. PMID:23122731

  10. Abundance of epiphytic dinoflagellates from coastal waters off Jeju Island, Korea During Autumn 2009

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Seop; Yih, Wonho; Kim, Jong Hyeok; Myung, Geumog; Jeong, Hae Jin

    2011-09-01

    The occurrence of harmful epiphytic dinoflagellates is of concern to scientists, the aquaculture industry, and government due to their toxicity not only to marine organisms but also to humans. There have been no studies on the abundance of the epiphytic dinoflagellates in Korean waters. We explored the presence of epiphytic dinoflagellates in the coastal waters off Jeju Island, southwestern Korea. Furthermore, we measured the abundance of epiphytic dinoflagellates on the thalli of 24 different macroalgae, collected from five different locations in October 2009. Five epiphytic dinoflagellate genera Amphidinium, Coolia, Gambierdiscus, Ostreopsis, and Prorocentrum were found. These five genera were observed on the thalli of the macroalgae Chordaria flagelliformis, Martensia sp., Padina arborescens, and Sargassum sp., while none were observed exceptionally on Codium fragile. The abundance of Ostreopsis spp. was highest on Derbesia sp. (8,660 cells/g wet weight), while that of Gambierdiscus spp. was highest on Martensia sp. (4,870 cells/g-ww). The maximum abundances of Amphidinium spp., Coolia spp., and Prorocentrum spp. were 410, 710, and 300 cells/g-ww, respectively. The maximum abundance of Coolia spp., Gambierdiscus spp., and Ostreopsis spp. obtained in the present study was lower than for other locations reported in literature. The results of the present study suggest that the presence and abundance of epiphytic dinoflagellates may be related to the macroalgal species of the coastal waters of Jeju Island.

  11. Putting the N in dinoflagellates

    PubMed Central

    Dagenais-Bellefeuille, Steve; Morse, David

    2013-01-01

    The cosmopolitan presence of dinoflagellates in aquatic habitats is now believed to be a direct consequence of the different trophic modes they have developed through evolution. While heterotrophs ingest food and photoautotrophs photosynthesize, mixotrophic species are able to use both strategies to harvest energy and nutrients. These different trophic modes are of particular importance when nitrogen nutrition is considered. Nitrogen is required for the synthesis of amino acids, nucleic acids, chlorophylls, and toxins, and thus changes in the concentrations of various nitrogenous compounds can strongly affect both primary and secondary metabolism. For example, high nitrogen concentration is correlated with rampant cell division resulting in the formation of the algal blooms commonly called red tides. Conversely, nitrogen starvation results in cell cycle arrest and induces a series of physiological, behavioral and transcriptomic modifications to ensure survival. This review will combine physiological, biochemical, and transcriptomic data to assess the mechanism and impact of nitrogen metabolism in dinoflagellates and to compare the dinoflagellate responses with those of diatoms. PMID:24363653

  12. Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

    PubMed Central

    Pilskaln, C.H.; Hayashi, K.; Keafer, B.A.; Anderson, D.M.; McGillicuddy, D.J.

    2014-01-01

    Cysts residing in benthic nepheloid layers (BNLs) documented in the Gulf of Maine have been proposed as a possible source of inoculum for annual blooms of a toxic dinoflagellate in the region. Herein we present a spatially extensive data set of the distribution and thickness of benthic nepheloid layers in the Gulf of Maine and the abundance and inventories of suspended Alexandrium fundyense cysts within these near-bottom layers. BNLs are pervasive throughout the gulf and adjacent Bay of Fundy with maximum layer thicknesses of 50–60 m observed. Mean BNL thickness is 30 m in the eastern gulf and Bay of Fundy, and 20 m in the western gulf. Cyst densities in the near-bottom particle resuspension layers varied by three orders of magnitude across the gulf with maxima of 105 cysts m−3. An important interconnection of elevated BNL cyst densities is observed between the Bay of Fundy, the Maine Coastal Current and the south-central region of the gulf. BNL cyst inventories estimated for the eastern and western gulf are each on the order of 1015 cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 1016 . Although BNL cyst inventories in the eastern and western gulf are 1–2 orders of magnitude smaller than the abundance of cysts in the upper 1 cm of sediment in those regions, BNL and sediment-bound cyst inventories are comparable in the Bay of Fundy. The existence of widespread BNLs containing substantial cyst inventories indicates that these near-bottom layers represent an important source of germinating A. fundyense cysts in the region. PMID:25419055

  13. Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

    NASA Astrophysics Data System (ADS)

    Pilskaln, C. H.; Hayashi, K.; Keafer, B. A.; Anderson, D. M.; McGillicuddy, D. J.

    2014-05-01

    Cysts residing in benthic nepheloid layers (BNLs) documented in the Gulf of Maine have been proposed as a possible source of inoculum for annual blooms of a toxic dinoflagellate in the region. Herein we present a spatially extensive data set of the distribution and thickness of benthic nepheloid layers in the Gulf of Maine and the abundance and inventories of suspended Alexandrium fundyense cysts within these near-bottom layers. BNLs are pervasive throughout the gulf and adjacent Bay of Fundy with maximum layer thicknesses of 50-60 m observed. Mean BNL thickness is 30 m in the eastern gulf and Bay of Fundy, and 20 m in the western gulf. Cyst densities in the near-bottom particle resuspension layers varied by three orders of magnitude across the gulf with maxima of 105 cysts m-3. An important interconnection of elevated BNL cyst densities is observed between the Bay of Fundy, the Maine Coastal Current and the south-central region of the gulf. BNL cyst inventories estimated for the eastern and western gulf are each on the order of 1015 cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 1016. Although BNL cyst inventories in the eastern and western gulf are 1-2 orders of magnitude smaller than the abundance of cysts in the upper 1 cm of sediment in those regions, BNL and sediment-bound cyst inventories are comparable in the Bay of Fundy. The existence of widespread BNLs containing substantial cyst inventories indicates that these near-bottom layers represent an important source of germinating A. fundyense cysts in the region.

  14. Patterns of post-glacial genetic differentiation in marginal populations of a marine microalga.

    PubMed

    Tahvanainen, Pia; Alpermann, Tilman J; Figueroa, Rosa Isabel; John, Uwe; Hakanen, Päivi; Nagai, Satoshi; Blomster, Jaanika; Kremp, Anke

    2012-01-01

    This study investigates the genetic structure of an eukaryotic microorganism, the toxic dinoflagellate Alexandrium ostenfeldii, from the Baltic Sea, a geologically young and ecologically marginal brackish water estuary which is predicted to support evolution of distinct, genetically impoverished lineages of marine macroorganisms. Analyses of the internal transcribed spacer (ITS) sequences and Amplified Fragment Length Polymorphism (AFLP) of 84 A. ostenfeldii isolates from five different Baltic locations and multiple external sites revealed that Baltic A. ostenfeldii is phylogenetically differentiated from other lineages of the species and micro-geographically fragmented within the Baltic Sea. Significant genetic differentiation (F(ST)) between northern and southern locations was correlated to geographical distance. However, instead of discrete genetic units or continuous genetic differentiation, the analysis of population structure suggests a complex and partially hierarchic pattern of genetic differentiation. The observed pattern suggests that initial colonization was followed by local differentiation and varying degrees of dispersal, most likely depending on local habitat conditions and prevailing current systems separating the Baltic Sea populations. Local subpopulations generally exhibited low levels of overall gene diversity. Association analysis suggests predominately asexual reproduction most likely accompanied by frequency shifts of clonal lineages during planktonic growth. Our results indicate that the general pattern of genetic differentiation and reduced genetic diversity of Baltic populations found in large organisms also applies to microscopic eukaryotic organisms. PMID:23300940

  15. Patterns of Post-Glacial Genetic Differentiation in Marginal Populations of a Marine Microalga

    PubMed Central

    Tahvanainen, Pia; Alpermann, Tilman J.; Figueroa, Rosa Isabel; John, Uwe; Hakanen, Päivi; Nagai, Satoshi; Blomster, Jaanika; Kremp, Anke

    2012-01-01

    This study investigates the genetic structure of an eukaryotic microorganism, the toxic dinoflagellate Alexandrium ostenfeldii, from the Baltic Sea, a geologically young and ecologically marginal brackish water estuary which is predicted to support evolution of distinct, genetically impoverished lineages of marine macroorganisms. Analyses of the internal transcribed spacer (ITS) sequences and Amplified Fragment Length Polymorphism (AFLP) of 84 A. ostenfeldii isolates from five different Baltic locations and multiple external sites revealed that Baltic A. ostenfeldii is phylogenetically differentiated from other lineages of the species and micro-geographically fragmented within the Baltic Sea. Significant genetic differentiation (FST) between northern and southern locations was correlated to geographical distance. However, instead of discrete genetic units or continuous genetic differentiation, the analysis of population structure suggests a complex and partially hierarchic pattern of genetic differentiation. The observed pattern suggests that initial colonization was followed by local differentiation and varying degrees of dispersal, most likely depending on local habitat conditions and prevailing current systems separating the Baltic Sea populations. Local subpopulations generally exhibited low levels of overall gene diversity. Association analysis suggests predominately asexual reproduction most likely accompanied by frequency shifts of clonal lineages during planktonic growth. Our results indicate that the general pattern of genetic differentiation and reduced genetic diversity of Baltic populations found in large organisms also applies to microscopic eukaryotic organisms. PMID:23300940

  16. Physiological responses of Manila clams Venerupis (=Ruditapes) philippinarum with varying parasite Perkinsus olseni burden to toxic algal Alexandrium ostenfeldii exposure.

    PubMed

    Lassudrie, Malwenn; Soudant, Philippe; Richard, Gaëlle; Henry, Nicolas; Medhioub, Walid; da Silva, Patricia Mirella; Donval, Anne; Bunel, Mélanie; Le Goïc, Nelly; Lambert, Christophe; de Montaudouin, Xavier; Fabioux, Caroline; Hégaret, Hélène

    2014-09-01

    Manila clam stock from Arcachon Bay, France, is declining, as is commercial harvest. To understand the role of environmental biotic interactions in this decrease, effects of a toxic dinoflagellate, Alexandrium ostenfeldii, which blooms regularly in Arcachon bay, and the interaction with perkinsosis on clam physiology were investigated. Manila clams from Arcachon Bay, with variable natural levels of perkinsosis, were exposed for seven days to a mix of the nutritious microalga T-Iso and the toxic dinoflagellate A. ostenfeldii, a producer of spirolides, followed by seven days of depuration fed only T-Iso. Following sacrifice and quantification of protozoan parasite Perkinsus olseni burden, clams were divided into two groups according to intensity of the infection ("Light-Moderate" and "Moderate-Heavy"). Hemocyte and plasma responses, digestive enzyme activities, antioxidant enzyme activities in gills, and histopathological responses were analyzed. Reactive oxygen species (ROS) production in hemocytes and catalase (CAT) activity in gills increased with P. olseni intensity of infection in control clams fed T-Iso, but did not vary among A. ostenfeldii-exposed clams. Exposure to A. ostenfeldii caused tissue alterations associated with an inflammatory response and modifications in hemocyte morphology. In the gills, superoxide dismutase (SOD) activity decreased, and an increase in brown cell occurrence was seen, suggesting oxidative stress. Observations of hemocytes and brown cells in tissues during exposure and depuration suggest involvement of both cell types in detoxication processes. Results suggest that exposure to A. ostenfeldii disrupted the pro-/anti-oxidant response of clams to heavy P. olseni intensity. In addition, depressed mitochondrial membrane potential (MMP) in hemocytes of clams exposed to A. ostenfeldii suggests that mitochondrial functions are regulated to maintain homeostasis of digestive enzyme activity and condition index. PMID:24858898

  17. The influence of extracellular compounds produced by selected Baltic cyanobacteria, diatoms and dinoflagellates on growth of green algae Chlorella vulgaris

    NASA Astrophysics Data System (ADS)

    Żak, Adam; Kosakowska, Alicja

    2015-12-01

    Secondary metabolites produced by bacteria, fungi, algae and plants could affect the growth and development of biological and agricultural systems. This natural process that occurs worldwide is known as allelopathy. The main goal of this work was to investigate the influence of metabolites obtained from phytoplankton monocultures on the growth of green algae Chlorella vulgaris. We selected 6 species occurring in the Baltic Sea from 3 different taxonomic groups: cyanobacteria (Aphanizomenon flos-aquae; Planktothrix agardhii), diatoms (Thalassiosira pseudonana; Chaetoceros wighamii) and dinoflagellates (Alexandrium ostenfeldii; Prorocentrum minimum). In this study we have demonstrated that some of selected organisms caused allelopathic effects against microalgae. Both the negative and positive effects of collected cell-free filtrates on C. vulgaris growth, chlorophyll a concentration and fluorescence parameters (OJIP, QY, NPQ) have been observed. No evidence has been found for the impact on morphology and viability of C. vulgaris cells.

  18. SxtA and sxtG Gene Expression and Toxin Production in the Mediterranean Alexandrium minutum (Dinophyceae)

    PubMed Central

    Perini, Federico; Galluzzi, Luca; Dell’Aversano, Carmela; Dello Iacovo, Emma; Tartaglione, Luciana; Ricci, Fabio; Forino, Martino; Ciminiello, Patrizia; Penna, Antonella

    2014-01-01

    The dinoflagellate Alexandrium minutum is known for the production of potent neurotoxins affecting the health of human seafood consumers via paralytic shellfish poisoning (PSP). The aim of this study was to investigate the relationship between the toxin content and the expression level of the genes involved in paralytic shellfish toxin (PST) production. The algal cultures were grown both in standard f/2 medium and in phosphorus/nitrogen limitation. In our study, LC-HRMS analyses of PST profile and content in different Mediterranean A. minutum strains confirmed that this species was able to synthesize mainly the saxitoxin analogues Gonyautoxin-1 (GTX1) and Gonyautoxin-4 (GTX4). The average cellular toxin content varied among different strains, and between growth phases, highlighting a decreasing trend from exponential to stationary phase in all culture conditions tested. The absolute quantities of intracellular sxtA1 and sxtG mRNA were not correlated with the amount of intracellular toxins in the analysed A. minutum suggesting that the production of toxins may be regulated by post-transcriptional mechanisms and/or by the concerted actions of alternative genes belonging to the PST biosynthesis gene cluster. Therefore, it is likely that the sxtA1 and sxtG gene expression could not reflect the PST accumulation in the Mediterranean A. minutum populations under the examined standard and nutrient limiting conditions. PMID:25341029

  19. Description of two species of early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp.

    PubMed

    Okamoto, Noriko; Horák, Aleš; Keeling, Patrick J

    2012-01-01

    In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epicone-hypocone structure, and (2) undulation in either flagella. Instead they display a mosaïc of dinokaryotes traits, i.e. (3) presence of bi-partite trychocysts; Oxyrrhis marina-like traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7) a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids, colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates. PMID:22719825

  20. Description of Two Species of Early Branching Dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp

    PubMed Central

    Okamoto, Noriko; Horák, Aleš; Keeling, Patrick J.

    2012-01-01

    In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epicone–hypocone structure, and (2) undulation in either flagella. Instead they display a mosaïc of dinokaryotes traits, i.e. (3) presence of bi-partite trychocysts; Oxyrrhis marina–like traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7) a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids, colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates. PMID:22719825

  1. A dinoflagellate cyst record of Holocene climate and hydrological changes along the southeastern Swedish Baltic coast

    NASA Astrophysics Data System (ADS)

    Yu, Shi-Yong; Berglund, Björn E.

    2007-03-01

    A high-resolution, well-dated dinoflagellate cyst record from a lagoon of the southeastern Swedish Baltic Sea reveals climate and hydrological changes during the Holocene. Marine dinoflagellate cysts occurred initially at about 8600 cal yr BP, indicating the onset of the Littorina transgression in the southeastern Swedish lowland associated with global sea level rise, and thus the opening of the Danish straits. Both the species diversity and the total accumulation rates of dinoflagellate cysts continued to increase by 7000 cal yr BP and then decreased progressively. This pattern reveals the first-order change in local sea level as a function of ice-volume-equivalent sea level rise versus isostatic land uplift. Superimposed upon this local sea level trend, well-defined fluctuations of the total accumulation rates of dinoflagellate cysts occurred on quasi-1000- and 500-yr frequency bands particularly between 7500 and 4000 cal yr BP, when the connection between the Baltic basin and the North Atlantic was broader. A close correlation of the total accumulation rates of dinoflagellate cysts with GISP2 ice core sea-salt ions suggests that fluctuations of Baltic surface conditions during the middle Holocene might have been regulated by quasi-periodic variations of the prevailing southwesterly winds, most likely through a system similar to the dipole oscillation of the modern North Atlantic atmosphere.

  2. Diversity and Divergence of Dinoflagellate Histone Proteins

    PubMed Central

    Marinov, Georgi K.; Lynch, Michael

    2015-01-01

    Histone proteins and the nucleosomal organization of chromatin are near-universal eukaroytic features, with the exception of dinoflagellates. Previous studies have suggested that histones do not play a major role in the packaging of dinoflagellate genomes, although several genomic and transcriptomic surveys have detected a full set of core histone genes. Here, transcriptomic and genomic sequence data from multiple dinoflagellate lineages are analyzed, and the diversity of histone proteins and their variants characterized, with particular focus on their potential post-translational modifications and the conservation of the histone code. In addition, the set of putative epigenetic mark readers and writers, chromatin remodelers and histone chaperones are examined. Dinoflagellates clearly express the most derived set of histones among all autonomous eukaryote nuclei, consistent with a combination of relaxation of sequence constraints imposed by the histone code and the presence of numerous specialized histone variants. The histone code itself appears to have diverged significantly in some of its components, yet others are conserved, implying conservation of the associated biochemical processes. Specifically, and with major implications for the function of histones in dinoflagellates, the results presented here strongly suggest that transcription through nucleosomal arrays happens in dinoflagellates. Finally, the plausible roles of histones in dinoflagellate nuclei are discussed. PMID:26646152

  3. Short-Term Behavioural Responses of the Great Scallop Pecten maximus Exposed to the Toxic Alga Alexandrium minutum Measured by Accelerometry and Passive Acoustics

    PubMed Central

    Coquereau, Laura; Jolivet, Aurélie; Hégaret, Hélène; Chauvaud, Laurent

    2016-01-01

    Harmful algal blooms produced by toxic dinoflagellates have increased worldwide, impacting human health, the environment, and fisheries. Due to their potential sensitivity (e.g., environmental changes), bivalves through their valve movements can be monitored to detect harmful algal blooms. Methods that measure valve activity require bivalve-attached sensors and usually connected cables to data transfers, leading to stress animals and limit the use to sessile species. As a non-intrusive and continuously deployable tool, passive acoustics could be an effective approach to detecting harmful algal blooms in real time based on animal sound production. This study aimed to detect reaction changes in the valve movements of adult Pecten maximus exposed to the toxic dinoflagellate Alexandrium minutum using both accelerometry and passive acoustic methods. Scallops were experimentally exposed to three ecologically relevant concentrations of A. minutum for 2 hours. The number of each type of valve movement and their sound intensity, opening duration, and valve-opening amplitude were measured. Four behaviours were identified: closures, expulsion, displacement, and swimming. The response of P. maximus to A. minutum occurred rapidly at a high concentration. The valve activity of P. maximus was different when exposed to high concentrations (500 000 cells L-1) of A. minutum compared to the non-toxic dinoflagellate Heterocapsa triquetra; the number of valve movements increased, especially closure and expulsion, which were detected acoustically. Thus, this study demonstrates the potential for acoustics and sound production changes in the detection of harmful algal blooms. However, field trials and longer duration experiments are required to provide further evidence for the use of acoustics as a monitoring tool in the natural environment where several factors may interfere with valve behaviours. PMID:27508498

  4. Trophic accumulation of PSP toxins in zooplankton during Alexandrium fundyense blooms in Casco Bay, Gulf of Maine, April June 1998. I. Toxin levels in A. fundyense and zooplankton size fractions

    NASA Astrophysics Data System (ADS)

    Doucette, Gregory J.; Turner, Jefferson T.; Powell, Christine L.; Keafer, Bruce A.; Anderson, Donald M.

    2005-09-01

    The transfer of marine algal toxins involving a range of phytoplanktivorous vectors is well documented as a means of exposing organisms at higher trophic levels (including humans) to these naturally occurring yet harmful compounds. While previous studies have examined the potential for, and dynamics of, algal toxin accumulation by individual zooplankton species, few have attempted to distinguish the contribution of various grazer size classes to toxin trophic transfer in natural communities and characterize some of the factors that can influence this process. The current investigation was aimed at describing the size-fractioned (64-100, 100-200, 200-500, >500 μm) accumulation of paralytic shellfish poisoning (PSP) toxins by zooplankton in Casco Bay and the adjacent coastal waters of the Gulf of Maine during a series of cruises from April to June 1998. Several variables, including the abundance of PSP toxin-producing Alexandrium fundyense, in-water toxin concentrations associated with this dinoflagellate, and algal toxin cell quotas, were measured and their relationship to zooplankton toxin accumulation assessed. A principal finding of this work was the ability of any grazer size class examined (including grazers present in the 20-64 μm A. fundyense-containing fraction) to serve as an initial vector for introducing PSP toxins into the Casco Bay food web at various times during the sampling period, thereby providing multiple potential routes of toxin trophic transfer. In addition, trends observed in the coincident mapping of A. fundyense cells and their associated toxin were generally in agreement, yet did not remain closely coupled at all times. Therefore, although A. fundyense abundance can be a reasonable indicator of PSP toxin presence in the phytoplankton, this relationship can vary considerably and lead to situations where elevated toxin levels occur at low cell concentrations and vice versa. The uncoupling of A. fundyense cell and in-water toxin

  5. Dinoflagellate-Related Amphidinolides from the Brazilian Octocoral Stragulum bicolor.

    PubMed

    Nuzzo, Genoveffa; Gomes, Bruno A; Luongo, Elvira; Torres, Maria C M; Santos, Evelyne A; Cutignano, Adele; Pessoa, Otília D L; Costa-Lotufo, Leticia V; Fontana, Angelo

    2016-07-22

    Benthic cnidarians are colonial marine animals that host a rich population of associated and symbiotic microorganisms. In a recent paper we described for the first time the isolation of amphidinolide P (1) from the Brazilian octocoral Stragulum bicolor. Amphidinolides and similar compounds had been previously reported only from dinoflagellates of the genus Amphidinium; thus the presence of 1 in the invertebrate opens intriguing questions on the role and occurrence of these molecules in marine ecosystems. Here we report the identification of four further amphidinolides from the same soft coral, including the known amphidinolide T1 (2) and the new analogues here named amphidinolides C4 (3), B8 (4), and B9 (5). The chemical structures have been elucidated mainly by extensive study of spectroscopic data. Cytotoxic activities of 3 and 4 were evaluated against the colon adenocarcinoma cell line HCT-116. PMID:27400333

  6. Phylogenetic Analyses of Three Genes of Pedinomonas noctilucae, the Green Endosymbiont of the Marine Dinoflagellate Noctiluca scintillans, Reveal its Affiliation to the Order Marsupiomonadales (Chlorophyta, Pedinophyceae) under the Reinstated Name Protoeuglena noctilucae.

    PubMed

    Wang, Lu; Lin, Xin; Goes, Joaquim I; Lin, Senjie

    2016-04-01

    In the last decade, field studies in the northern Arabian Sea showed a drastic shift from diatom-dominated phytoplankton blooms to thick and widespread blooms of the green dinoflagellate, Noctiluca scintillans. Unlike the exclusively heterotrophic red form, which occurs widely in tropical to temperate coastal waters, the green Noctiluca contains a large number of endosymbiotic algal cells that can perform photosynthesis. These symbiotic microalgae were first described under the genus Protoeuglena Subrahmanyan and further transferred to Pedinomonas as P. noctilucae Sweeney. In this study, we used the 18S rDNA, rbcL and chloroplast 16S rDNA as gene markers, in combination with the previously reported morphological features, to re-examine the phylogenetic position of this endosymbiotic algal species. Phylogenetic trees inferred from these genes consistently indicated that P. noctilucae is distantly related to the type species of Pedinomonas. The sequences formed a monophyletic clade sister to the clade of Marsupiomonas necessitating the placement of the algal symbionts as an independent genus within the family Marsupiomonadaceae. Based on the phylogenetic affiliation and ecological characteristics of this alga as well as the priority rule of nomenclature, we reinstate the genus Protoeuglena and reclassify the endosymbiont as Protoeuglena noctilucae. PMID:27033730

  7. WITHDRAWN: Gene expression and molecular evolution of sxtA4 in a saxitoxin producing dinoflagellate Alexandrium catenella.

    PubMed

    Wiese, Maria; Murray, Shauna A; Alvin, Alfonsus; Neilan, Brett A

    2014-07-28

    This article has been withdrawn at the request of the authors and editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy. PMID:25080311

  8. Do All Dinoflagellates have an Extranuclear Spindle?

    PubMed

    Moon, Eunyoung; Nam, Seung Won; Shin, Woongghi; Park, Myung Gil; Coats, D Wayne

    2015-11-01

    The syndinean dinoflagellates are a diverse assemblage of alveolate endoparasites that branch basal to the core dinoflagellates. Because of their phylogenetic position, the syndineans are considered key model microorganisms in understanding early evolution in the dinoflagellates. Closed mitosis with an extranuclear spindle that traverses the nucleus in cytoplasmic grooves or tunnels is viewed as one of the morphological features shared by syndinean and core dinoflagellates. Here we describe nuclear morphology and mitosis in the syndinean dinoflagellate Amoebophrya sp. from Akashiwo sanguinea, a member of the A. ceratii complex, as revealed by protargol silver impregnation, DNA specific fluorochromes, and transmission electron microscopy. Our observations show that not all species classified as dinoflagellates have an extranuclear spindle. In Amoebophrya sp. from A. sanguinea, an extranuclear microtubule cylinder located in a depression in the nuclear surface during interphase moves into the nucleoplasm via sequential membrane fusion events and develops into an entirely intranuclear spindle. Results suggest that the intranuclear spindle of Amoebophrya spp. may have evolved from an ancestral extranuclear spindle and indicate the need for taxonomic revision of the Amoebophryidae. PMID:26491972

  9. Analysis of the hydrographic conditions and cyst beds in the San Jorge Gulf, Argentina, that favor dinoflagellate population development including toxigenic species and their toxins

    NASA Astrophysics Data System (ADS)

    Krock, Bernd; Borel, C. Marcela; Barrera, Facundo; Tillmann, Urban; Fabro, Elena; Almandoz, Gastón O.; Ferrario, Martha; Garzón Cardona, John E.; Koch, Boris P.; Alonso, Cecilia; Lara, Rubén

    2015-08-01

    The overlay of cooler nutrient enriched Beagle-Magellan water with warmer nutrient depleted shelf water and a strong stratification of the water column in the San Jorge Gulf region, Argentina, coincided with relatively high dinoflagellate abundances in April 2012, up to 34,000 cells L- 1. This dinoflagellate proliferation was dominated by Ceratium spp., but environmental conditions also favored to a lesser amount the occurrence of toxigenic dinoflagellates, such as Alexandrium tamarense and Protoceratium reticulatum, whose toxins were hardly detected in any other areas along the expedition transect of the R/V Puerto Deseado between 38 and 56°S (Ushuaia-Mar del Plata) in March/April 2012. Generally vegetative cells of A. tamarense and P. reticulatum co-occurred with their respective phycotoxins in the water column and their cysts in the upper sediment layers. Two strains of A. tamarense were isolated from the bloom sample and morphologically characterized. Their PSP toxin profiles consisted of C1/2, gonyautoxins 1/4 and to a lesser amount of neosaxitoxin and confirmed earlier data from this region. The ratios between autotrophic picoplankton and heterotrophic bacteria were higher in shelf waters in the north than in Beagle-Magellan waters in the south of San Jorge Gulf.

  10. New-old hemoglobin-like proteins of symbiotic dinoflagellates

    PubMed Central

    Rosic, Nedeljka N; Leggat, William; Kaniewska, Paulina; Dove, Sophie; Hoegh-Guldberg, Ove

    2013-01-01

    Symbiotic dinoflagellates are unicellular photosynthetic algae that live in mutualistic symbioses with many marine organisms. Within the transcriptome of coral endosymbionts Symbiodinium sp. (type C3), we discovered the sequences of two novel and highly polymorphic hemoglobin-like genes and proposed their 3D protein structures. At the protein level, four isoforms shared between 87 and 97% sequence identity for Hb-1 and 78–99% for Hb-2, whereas between Hb-1 and Hb-2 proteins, only 15–21% sequence homology has been preserved. Phylogenetic analyses of the dinoflagellate encoding Hb sequences have revealed a separate evolutionary origin of the discovered globin genes and indicated the possibility of horizontal gene transfer. Transcriptional regulation of the Hb-like genes was studied in the reef-building coral Acropora aspera exposed to elevated temperatures (6–7°C above average sea temperature) over a 24-h period and a 72-h period, as well as to nutrient stress. Exposure to elevated temperatures resulted in an increased Hb-1 gene expression of 31% after 72 h only, whereas transcript abundance of the Hb-2 gene was enhanced by up to 59% by both 1-day and 3-day thermal stress conditions. Nutrient stress also increased gene expression of Hb-2 gene by 70%. Our findings describe the differential expression patterns of two novel Hb genes from symbiotic dinoflagellates and their polymorphic nature. Furthermore, the inducible nature of Hb-2 gene by both thermal and nutrient stressors indicates a prospective role of this form of hemoglobin in the initial coral–algal responses to changes in environmental conditions. This novel hemoglobin has potential use as a stress biomarker. PMID:23610627

  11. Biogeography of dinoflagellate cysts in northwest Atlantic estuaries.

    PubMed

    Price, Andrea M; Pospelova, Vera; Coffin, Michael R S; Latimer, James S; Chmura, Gail L

    2016-08-01

    Few biogeographic studies of dinoflagellate cysts include the near-shore estuarine environment. We determine the effect of estuary type, biogeography, and water quality on the spatial distribution of organic-walled dinoflagellate cysts from the Northeast USA (Maine to Delaware) and Canada (Prince Edward Island). A total of 69 surface sediment samples were collected from 27 estuaries, from sites with surface salinities >20. Dinoflagellate cysts were examined microscopically and compared to environmental parameters using multivariate ordination techniques. The spatial distribution of cyst taxa reflects biogeographic provinces established by other marine organisms, with Cape Cod separating the northern Acadian Province from the southern Virginian Province. Species such as Lingulodinium machaerophorum and Polysphaeridinium zoharyi were found almost exclusively in the Virginian Province, while others such as Dubridinium spp. and Islandinium? cezare were more abundant in the Acadian Province. Tidal range, sea surface temperature (SST), and sea surface salinity (SSS) are statistically significant parameters influencing cyst assemblages. Samples from the same type of estuary cluster together in canonical correspondence analysis when the estuaries are within the same biogeographic province. The large geographic extent of this study, encompassing four main estuary types (riverine, lagoon, coastal embayment, and fjord), allowed us to determine that the type of estuary has an important influence on cyst assemblages. Due to greater seasonal variations in SSTs and SSSs in estuaries compared to the open ocean, cyst assemblages show distinct latitudinal trends. The estuarine context is important for understanding present-day species distribution, the factors controlling them, and to better predict how they may change in the future. PMID:27547344

  12. Differential effects of ocean acidification on carbon acquisition in two bloom-forming dinoflagellate species.

    PubMed

    Eberlein, Tim; Van de Waal, Dedmer B; Rost, Björn

    2014-08-01

    Dinoflagellates represent a cosmopolitan group of phytoplankton with the ability to form harmful algal blooms. Featuring a Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) with very low CO2 affinities, photosynthesis of this group may be particularly prone to carbon limitation and thus benefit from rising atmospheric CO2 partial pressure (pCO2) under ocean acidification (OA). Here, we investigated the consequences of OA on two bloom-forming dinoflagellate species, the calcareous Scrippsiella trochoidea and the toxic Alexandrium tamarense. Using dilute batch incubations, we assessed growth characteristics over a range of pCO2 (i.e. 180-1200 µatm). To understand the underlying physiology, several aspects of inorganic carbon acquisition were investigated by membrane-inlet mass spectrometry. Our results show that both species kept growth rates constant over the tested pCO2 range, but we observed a number of species-specific responses. For instance, biomass production and cell size decreased in S. trochoidea, while A. tamarense was not responsive to OA in these measures. In terms of oxygen fluxes, rates of photosynthesis and respiration remained unaltered in S. trochoidea whereas respiration increased in A. tamarense under OA. Both species featured efficient carbon concentrating mechanisms (CCMs) with a CO2-dependent contribution of HCO3(-) uptake. In S. trochoidea, the CCM was further facilitated by exceptionally high and CO2-independent carbonic anhydrase activity. Comparing both species, a general trade-off between maximum rates of photosynthesis and respective affinities is indicated. In conclusion, our results demonstrate effective CCMs in both species, yet very different strategies to adjust their carbon acquisition. This regulation in CCMs enables both species to maintain growth over a wide range of ecologically relevant pCO2 . PMID:24320746

  13. Symbiodinium transcriptomes: genome insights into the dinoflagellate symbionts of reef-building corals.

    PubMed

    Bayer, Till; Aranda, Manuel; Sunagawa, Shinichi; Yum, Lauren K; Desalvo, Michael K; Lindquist, Erika; Coffroth, Mary Alice; Voolstra, Christian R; Medina, Mónica

    2012-01-01

    Dinoflagellates are unicellular algae that are ubiquitously abundant in aquatic environments. Species of the genus Symbiodinium form symbiotic relationships with reef-building corals and other marine invertebrates. Despite their ecologic importance, little is known about the genetics of dinoflagellates in general and Symbiodinium in particular. Here, we used 454 sequencing to generate transcriptome data from two Symbiodinium species from different clades (clade A and clade B). With more than 56,000 assembled sequences per species, these data represent the largest transcriptomic resource for dinoflagellates to date. Our results corroborate previous observations that dinoflagellates possess the complete nucleosome machinery. We found a complete set of core histones as well as several H3 variants and H2A.Z in one species. Furthermore, transcriptome analysis points toward a low number of transcription factors in Symbiodinium spp. that also differ in the distribution of DNA-binding domains relative to other eukaryotes. In particular the cold shock domain was predominant among transcription factors. Additionally, we found a high number of antioxidative genes in comparison to non-symbiotic but evolutionary related organisms. These findings might be of relevance in the context of the role that Symbiodinium spp. play as coral symbionts.Our data represent the most comprehensive dinoflagellate EST data set to date. This study provides a comprehensive resource to further analyze the genetic makeup, metabolic capacities, and gene repertoire of Symbiodinium and dinoflagellates. Overall, our findings indicate that Symbiodinium possesses some unique characteristics, in particular the transcriptional regulation in Symbiodinium may differ from the currently known mechanisms of eukaryotic gene regulation. PMID:22529998

  14. Mycosporine-like amino acids from coral dinoflagellates.

    PubMed

    Rosic, Nedeljka N; Dove, Sophie

    2011-12-01

    Coral reefs are one of the most important marine ecosystems, providing habitat for approximately a quarter of all marine organisms. Within the foundation of this ecosystem, reef-building corals form mutualistic symbioses with unicellular photosynthetic dinoflagellates of the genus Symbiodinium. Exposure to UV radiation (UVR) (280 to 400 nm) especially when combined with thermal stress has been recognized as an important abiotic factor leading to the loss of algal symbionts from coral tissue and/or a reduction in their pigment concentration and coral bleaching. UVR may damage biological macromolecules, increase the level of mutagenesis in cells, and destabilize the symbiosis between the coral host and their dinoflagellate symbionts. In nature, corals and other marine organisms are protected from harmful UVR through several important photoprotective mechanisms that include the synthesis of UV-absorbing compounds such as mycosporine-like amino acids (MAAs). MAAs are small (<400-Da), colorless, water-soluble compounds made of a cyclohexenone or cyclohexenimine chromophore that is bound to an amino acid residue or its imino alcohol. These secondary metabolites are natural biological sunscreens characterized by a maximum absorbance in the UVA and UVB ranges of 310 to 362 nm. In addition to their photoprotective role, MAAs act as antioxidants scavenging reactive oxygen species (ROS) and suppressing singlet oxygen-induced damage. It has been proposed that MAAs are synthesized during the first part of the shikimate pathway, and recently, it has been suggested that they are synthesized in the pentose phosphate pathway. The shikimate pathway is not found in animals, but in plants and microbes, it connects the metabolism of carbohydrates to the biosynthesis of aromatic compounds. However, both the complete enzymatic pathway of MAA synthesis and the extent of their regulation by environmental conditions are not known. This minireview discusses the current knowledge of MAA

  15. Novel insight into the role of heterotrophic dinoflagellates in the fate of crude oil in the sea.

    PubMed

    Almeda, Rodrigo; Connelly, Tara L; Buskey, Edward J

    2014-01-01

    Although planktonic protozoans are likely to interact with dispersed crude oil after a spill, protozoan-mediated processes affecting crude oil pollution in the sea are still not well known. Here, we present the first evidence of ingestion and defecation of physically or chemically dispersed crude oil droplets (1-86 μm in diameter) by heterotrophic dinoflagellates, major components of marine planktonic food webs. At a crude oil concentration commonly found after an oil spill (1 μL L(-1)), the heterotrophic dinoflagellates Noctiluca scintillans and Gyrodinium spirale grew and ingested ~0.37 μg-oil μg-C(dino)(-1) d(-1), which could represent ~17% to 100% of dispersed oil in surface waters when heterotrophic dinoflagellates are abundant or bloom. Egestion of faecal pellets containing crude oil by heterotrophic dinoflagellates could contribute to the sinking and flux of toxic petroleum hydrocarbons in coastal waters. Our study indicates that crude oil ingestion by heterotrophic dinoflagellates is a noteworthy route by which petroleum enters marine food webs and a previously overlooked biological process influencing the fate of crude oil in the sea after spills. PMID:25523528

  16. Novel insight into the role of heterotrophic dinoflagellates in the fate of crude oil in the sea

    PubMed Central

    Almeda, Rodrigo; Connelly, Tara L.; Buskey, Edward J.

    2014-01-01

    Although planktonic protozoans are likely to interact with dispersed crude oil after a spill, protozoan-mediated processes affecting crude oil pollution in the sea are still not well known. Here, we present the first evidence of ingestion and defecation of physically or chemically dispersed crude oil droplets (1–86 μm in diameter) by heterotrophic dinoflagellates, major components of marine planktonic food webs. At a crude oil concentration commonly found after an oil spill (1 μL L−1), the heterotrophic dinoflagellates Noctiluca scintillans and Gyrodinium spirale grew and ingested ~0.37 μg-oil μg-Cdino−1 d−1, which could represent ~17% to 100% of dispersed oil in surface waters when heterotrophic dinoflagellates are abundant or bloom. Egestion of faecal pellets containing crude oil by heterotrophic dinoflagellates could contribute to the sinking and flux of toxic petroleum hydrocarbons in coastal waters. Our study indicates that crude oil ingestion by heterotrophic dinoflagellates is a noteworthy route by which petroleum enters marine food webs and a previously overlooked biological process influencing the fate of crude oil in the sea after spills. PMID:25523528

  17. Novel insight into the role of heterotrophic dinoflagellates in the fate of crude oil in the sea

    NASA Astrophysics Data System (ADS)

    Almeda, Rodrigo; Connelly, Tara L.; Buskey, Edward J.

    2014-12-01

    Although planktonic protozoans are likely to interact with dispersed crude oil after a spill, protozoan-mediated processes affecting crude oil pollution in the sea are still not well known. Here, we present the first evidence of ingestion and defecation of physically or chemically dispersed crude oil droplets (1-86 μm in diameter) by heterotrophic dinoflagellates, major components of marine planktonic food webs. At a crude oil concentration commonly found after an oil spill (1 μL L-1), the heterotrophic dinoflagellates Noctiluca scintillans and Gyrodinium spirale grew and ingested ~0.37 μg-oil μg-Cdino-1 d-1, which could represent ~17% to 100% of dispersed oil in surface waters when heterotrophic dinoflagellates are abundant or bloom. Egestion of faecal pellets containing crude oil by heterotrophic dinoflagellates could contribute to the sinking and flux of toxic petroleum hydrocarbons in coastal waters. Our study indicates that crude oil ingestion by heterotrophic dinoflagellates is a noteworthy route by which petroleum enters marine food webs and a previously overlooked biological process influencing the fate of crude oil in the sea after spills.

  18. BIOCHEMISTRY OF DINOFLAGELLATE LIPIDS, WITH PARTICULAR REFERENCE TO THE FATTY ACID AND STEROL COMPOSITION OF A KARENIA BREVIS BLOOM

    EPA Science Inventory

    Leblond, Jeffrey D., Terence J. Evens and Peter J. Chapman. 2003. Biochemistry of Dinoflagellate Lipids, with Particular Reference to the Fatty Acid and Sterol Composition of a Karenia brevis Bloom. Phycologia. 42(4):324-331. (ERL,GB 1160).

    The harmful marine dinoflagella...

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

    NASA Astrophysics Data System (ADS)

    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.

  20. A New Polyether Ladder Compound Produced by the Dinoflagellate Karenia brevis

    PubMed Central

    Bourdelais, Andrea J.; Jacocks, Henry M.; Wright, Jeffrey L. C.; Bigwarfe, Paul M.; Baden, Daniel G.

    2009-01-01

    A new ladder-frame polyether compound containing five fused ether rings was isolated from laboratory cultures of the marine dinoflagellate Karenia brevis. This compound, named brevenal, and its dimethyl acetal derivative both competitively displace brevetoxin from its binding site in rat brain synaptosomes. Significantly, these compounds are also nontoxic to fish and antagonize the toxic effects of brevetoxins in fish. The structure and biological activity of brevenal, as well as the dimethyl acetal derivative, are described in this paper. PMID:15679307

  1. Cell Biology of Cnidarian-Dinoflagellate Symbiosis

    PubMed Central

    Allemand, Denis; Weis, Virginia M.

    2012-01-01

    Summary: The symbiosis between cnidarians (e.g., corals or sea anemones) and intracellular dinoflagellate algae of the genus Symbiodinium is of immense ecological importance. In particular, this symbiosis promotes the growth and survival of reef corals in nutrient-poor tropical waters; indeed, coral reefs could not exist without this symbiosis. However, our fundamental understanding of the cnidarian-dinoflagellate symbiosis and of its links to coral calcification remains poor. Here we review what we currently know about the cell biology of cnidarian-dinoflagellate symbiosis. In doing so, we aim to refocus attention on fundamental cellular aspects that have been somewhat neglected since the early to mid-1980s, when a more ecological approach began to dominate. We review the four major processes that we believe underlie the various phases of establishment and persistence in the cnidarian/coral-dinoflagellate symbiosis: (i) recognition and phagocytosis, (ii) regulation of host-symbiont biomass, (iii) metabolic exchange and nutrient trafficking, and (iv) calcification. Where appropriate, we draw upon examples from a range of cnidarian-alga symbioses, including the symbiosis between green Hydra and its intracellular chlorophyte symbiont, which has considerable potential to inform our understanding of the cnidarian-dinoflagellate symbiosis. Ultimately, we provide a comprehensive overview of the history of the field, its current status, and where it should be going in the future. PMID:22688813

  2. Effect of Alexandrium tamarense on three bloom-forming algae

    NASA Astrophysics Data System (ADS)

    Yin, Juan; Xie, Jin; Yang, Weidong; Li, Hongye; Liu, Jiesheng

    2010-07-01

    We investigated the allelopathic properties of Alexandrium tamarense (Laboar) Balech on the growth of Prorocentrum donghaiense Lu, Chattonella marina (Subrahmanyan) Hara et Chihara and Heterosigma akashiwo (Hada) Hada in a laboratory experiment. We examined the growth of A. tamarense, C. marina, P. donghaiense and H. Akashiwo in co-cultures and the effect of filtrates from A. tamarense cultures in various growth phases, on the three harmful algal bloom (HAB)-forming algae. In co-cultures with A. tamarense, both C. marina and H. akashiwo were dramatically suppressed at high cell densities; in contrast, the growth of P. donghaiense varied in different inoculative ratios of A. tamarense and P. donghaiense. When the ratio was 1:1 ( P. donghaiense: A. tamarense), growth of P. donghaiense was inhibited considerably, while the growth of P. donghaiense was almost the same as that of the control when the ratio was 9:1. The growth difference of P. donghaiense, C. marina and H. akashiwo when co-cultured with A. tamarense indicated that the allelopathic effect may be one of the important factors in algal competition and phytoplankton succession involving A. tamarense. In addition, the filtrate from A. tamarense culture had negative impacts on these three HAB algae, and such inhibition varied with different growth phases of A. tamarense in parallel with reported values of PSP toxin content in Alexandrium cells. This implied that PSP toxin was possibly involved in allelopathy of A. tamarense. However, the rapid decomposition and inactivation of PSP toxin above pH 7 weakened this possibility. Further studies on the allelochemicals responsible for the allelopathy of A. tamarense need to be carried out in future.

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

    PubMed

    Couesnon, Aurélie; Aráoz, Rómulo; Iorga, Bogdan I; Benoit, Evelyne; Reynaud, Morgane; Servent, Denis; Molgó, Jordi

    2016-01-01

    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 [(125)I]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. PMID:27563924

  4. Localization of polyketide synthase encoding genes to the toxic dinoflagellate Karenia brevis

    PubMed Central

    Snyder, Richard V.; Guerrero, Maria A.; Sinigalliano, Christopher D.; Winshell, Jamie; Perez, Roberto; Lopez, Jose V.; Rein, Kathleen S.

    2008-01-01

    Karenia brevis is a toxic marine dinoflagellate endemic to the Gulf of Mexico. Blooms of this harmful alga cause fish kills, marine mammal mortalities and neurotoxic shellfish poisonings. These harmful effects are attributed to a suite of polyketide secondary metabolites known as the brevetoxins. The carbon framework of all polyketides is assembled by a polyketide synthase (PKS). Previously, PKS encoding genes were amplified from K. brevis culture and their similarity to a PKS gene from the closely related protist, Cryptosporidium parvum, suggested that these genes originate from the dinoflagellate. However, K. brevis has not been grown axenically. The associated bacteria might be the source of the toxins or the PKS genes. Herein we report the localization of PKS encoding genes by a combination of flow cytometry/PCR and fluorescence in situ hybridization (FISH). Two genes localized exclusively to K. brevis cells while a third localized to both K. brevis and associated bacteria. While these genes have not yet been linked to toxin production, the work describes the first definitive evidence of resident PKS genes in any dinoflagellate. PMID:16051286

  5. MODIS and MERIS detection of dinoflagellates blooms using the RBD technique

    NASA Astrophysics Data System (ADS)

    Amin, R.; Gilerson, A.; Gross, B.; Moshary, F.; Ahmed, S.

    2009-09-01

    Harmful Algal Blooms (HABs) can lead to severe economical and ecological impacts particularly in the coastal areas and can threaten human and marine health. About three-quarter of these toxic blooms are caused by dinoflagellates species which are well known to migrate vertically. During the day, they migrate up to the surface for photosynthesis, and consequently, their dense aggregations produce strong bio-optical signals that are detectable by space borne optical satellite sensors. In this study we use our recently developed low backscattering bloom detection technique, the Red Band Difference (RBD), to detect various dinoflagellates blooms using both MODIS (Moderate Resolution Imaging Spectroradiometer) and MERIS (Medium Resolution Imaging Spectrometer) data and present the results which confirm the potentials of the RBD technique. Here we present examples of bloom detection in waters off Gulf of Mexico, Monterey Bay, South Africa, and East China Sea.

  6. Distribution of Alexandrium fundyense and A. pacificum (Dinophyceae) in the Yellow Sea and Bohai Sea.

    PubMed

    Gao, Yan; Yu, Ren-Cheng; Chen, Jian-Hua; Zhang, Qing-Chun; Kong, Fan-Zhou; Zhou, Ming-Jiang

    2015-07-15

    This study characterizes the distribution of two closely related, causative species of paralytic shellfish poisoning – Alexandrium fundyense and A. pacificum – within the Yellow Sea (YS) and Bohai Sea (BS). These two Alexandrium species are distinguished for the first time in a regional field study using species-specific, quantitative PCR (qPCR) based assays. Both qPCR assays target the large subunit ribosomal DNA gene and were used to analyze net-concentrated phytoplankton samples collected in May 2012. A. fundyense was mainly distributed in YS, while A. pacificum was confined to an area adjacent to the Changjiang River estuary. The different distribution of the two species is interpreted as evidence of their distinct bloom ecology. Expanded efforts implementing these assays offer the ability to discriminate the dynamics of A. fundyense and A. pacificum blooms and provide a more sound basis for monitoring toxic Alexandrium species in this region. PMID:26026250

  7. New Insights into the Parasitoid Parvilucifera sinerae Life Cycle: The Development and Kinetics of Infection of a Bloom-forming Dinoflagellate Host.

    PubMed

    Alacid, Elisabet; Reñé, Albert; Garcés, Esther

    2015-12-01

    Parvilucifera sinerae is a parasitoid of dinoflagellates, the major phytoplankton group responsible for harmful algal bloom events. Here we provide a detailed description of both the life cycle of P. sinerae, based on optical, confocal, and transmission electron microscopy observations, and its infection kinetics and dynamics. P. sinerae completes its life cycle in 3-4 days. The zoospore encounters and penetrates the host cell within 24h after its addition to the host culture. Inside the host, the parasitoid develops a trophocyte, which constitutes the longest stage of its life cycle. The trophocyte replicates and divides by schizogony to form hundreds of new zoospores contained within a sporangium. Under laboratory conditions, P. sinerae has a short generation time, a high rate of asexual reproduction, and is highly prevalent (up to 80%) in the Alexandrium minutum population. Prevalence was shown to depend on both the parasitoid inoculum size and host density, which increase the encounter probability rate. The parasitoid infection parameters described in this study are the first reported for the genus Parvilucifera. They show that P. sinerae is well-adapted to its dinoflagellate hosts and may be an important factor in the termination of A. minutum blooms in the natural environment. PMID:26605683

  8. Distribution and toxicity of Alexandrium ostenfeldii (Dinophyceae) in the Gulf of Maine, USA

    NASA Astrophysics Data System (ADS)

    Gribble, Kristin E.; Keafer, Bruce A.; Quilliam, Michael A.; Cembella, Allan D.; Kulis, David M.; Manahan, Abigail; Anderson, Donald M.

    2005-09-01

    Alexandrium ostenfeldii is a thecate, mixotrophic dinoflagellate recently linked to a novel suite of toxins called spirolides. This study provides the first description of the regional distribution of A. ostenfeldii in the Gulf of Maine (GOM), and the first report and analysis of spirolide toxicity in A. ostenfeldii in waters south of Nova Scotia. Morphological examination of cells in field samples and of clonal cultures isolated from several stations in the GOM confirmed the presence of A. ostenfeldii. A genus-specific antibody probe, and an A. ostenfeldii species-specific oligonucleotide probe labeled these cells; a probe specific for the North American A. fundyense/tamarense/catenella species complex did not label A. ostenfeldii cells. Cell size ranged from 20 to nearly 90 μm, and most cells contained food vacuoles, with a total vacuole size from 1 to 48 μm. The hydrographic forcings controlling the distribution of A. ostenfeldii in the GOM are quite similar to those acting on the A. fundyense population at the same time of the year. The highest concentrations of A. ostenfeldii were observed nearshore, to the east of Penobscot Bay, at times with an offshore-turning branch of high cell concentration to the south of Penobscot Bay. Casco Bay appears to be an area of accumulation for A. ostenfeldii cells advected toward shore from the core of the population to the northeast. Concentrations of A. ostenfeldii were generally higher at the surface than deeper, except at locations where the pooling of lower-salinity water at the surface may have led to the subduction of the population flowing in from the east. PSP toxins were detected in field populations containing A. ostenfeldii and A. fundyense, but not in A. ostenfeldii cultures isolated from the GOM. Spirolide toxins were found in 36 of 60 field samples. More than 83% of samples containing A. ostenfeldii cells had one or more of spirolide congeners A, B, C2 and D2. The total concentration of spirolides per cell at

  9. Isolation of symbiotic dinoflagellates by centrifugal elutriation

    SciTech Connect

    Bird, A.E.; Quinn, R.J.

    1986-01-01

    Centrifugal elutriation, a method combining centripetal liquid flow with centrifugal force, has been used to isolate symbiotic dinoflagellates from a cnidarian host. The elutriated cells were shown to be viable by photosynthetic incorporation of /sup 14/CO/sub 2/ and low release of photosynthetic products into the incubation medium. The level of contamination by clinging debris was low and by host solids was negligible.

  10. Dinoflagellate cyst production in Hudson Bay, the world's largest inland sea, based on monthly sediment trap data

    NASA Astrophysics Data System (ADS)

    Heikkilä, Maija; Pospelova, Vera; Forest, Alexandre; Stern, Gary

    2014-05-01

    Phytoplankters, microscopic primary producers of oceans are capable of responding rapidly to environmental fluctuations due to their high cell replication rates. Fast phytoplankton growth maybe balanced out by equally fast consumption by herbivorous grazers. In high-latitude marine systems, seasonal fluctuations in plankton biomass are essentially linked to light regime controlled by the waxing and waning sea-ice cover. In addition, nutrient limitation in surface waters, seasonal temperature fluctuations and changes in freshwater inputs may play important roles. In cold-water seas, many planktonic organisms cope with seasonal harshness by the production of benthic dormant stages. Dinoflagellates are a diverse group of single-celled plankton, constituting major marine primary producers, as well as herbivorous grazers of the microbial loop. Many dinoflagellate species produce highly resistant, organic-walled resting cysts that are archived in sediments and have been increasingly used to reconstruct past environmental conditions, e.g., sea-surface temperature and salinity, productivity, sea-ice cover and eutrophication. Marine sediment core sequences are characterized by slow accumulation rates and high mixing rates: the top centimeter of surface sediment from an arctic shelf may correspond to several years or decades of deposition. Consequently, sedimentary archives do not give direct information on long-term changes in seasonal bloom patterns or cues of annually recurring life-cycle events. We used two particle-intercepting sediment traps moored in eastern and western Hudson Bay, respectively, to study monthly fluctuations in dinoflagellate cyst production from October 2005 to September 2006. The traps were deployed close to the seafloor and recovered during the ArcticNet annual expeditions onboard the CCGS Amundsen in 2005 and the CCGS Pierre Radisson in 2006. We document the seasonal succession of dinoflagellate cyst taxa, together with cyst species composition

  11. Recognizing diversity in coral symbiotic dinoflagellate communities.

    PubMed

    Apprill, Amy M; Gates, Ruth D

    2007-03-01

    A detailed understanding of how diversity in endosymbiotic dinoflagellate communities maps onto the physiological range of coral hosts is critical to predicting how coral reef ecosystems will respond to climate change. Species-level taxonomy of the dinoflagellate genus Symbiodinium has been predominantly examined using the internal transcribed spacer (ITS) region of the nuclear ribosomal array (rDNA ITS2) and downstream screening for dominant types using denaturing gradient gel electrophoresis (DGGE). Here, ITS2 diversity in the communities of Symbiodinium harboured by two Hawaiian coral species was explored using direct sequencing of clone libraries. We resolved sixfold to eightfold greater diversity per coral species than previously reported, the majority of which corresponds to a novel and distinct phylogenetic lineage. We evaluated how these sequences migrate in DGGE and demonstrate that this method does not effectively resolve this diversity. We conclude that the Porites spp. examined here harbour diverse assemblages of novel Symbiodinium types and that cloning and sequencing is an effective methodological approach for resolving the complexity of endosymbiotic dinoflagellate communities harboured by reef corals. PMID:17391401

  12. Oligotrophication and emergence of picocyanobacteria and a toxic dinoflagellate in Thau lagoon, southern France

    NASA Astrophysics Data System (ADS)

    Collos, Yves; Bec, Béatrice; Jauzein, Cécile; Abadie, Eric; Laugier, Thierry; Lautier, Jacques; Pastoureaud, Annie; Souchu, Philippe; Vaquer, André

    2009-01-01

    Time series data have been examined in Thau lagoon (Southern France) from 1972 to 2006 for water temperature, salinity, nutrients and from 1987 to 2006 for phytoplankton. A first main trend identified is an increase in mean annual water temperature (1.5 °C over 33 years or 0.045 °C/year) that was not evenly distributed among seasons. The highest rate of increase was in the spring (+ 3.0 °C over 33 years), followed by summer (+ 2.0 °C) and fall (+ 1.7 °C). In winter, no significant increase over the 33 year period could be found. A second clear trend is a large decrease in soluble reactive phosphorus (SRP) concentration over the same 33 year period (summer values decreased from 10 µM to 1 µM, while winter values decreased from 3 µM to undetectable at present). Nitrate concentrations depended mainly on rainfall events and watershed runoff. Ammonium data were too fragmentary to be useful. N/P ratios expressed the traditional way of DIN/SRP cannot be used for phytoplankton that are not strict autotrophs. The recent and almost simultaneous appearance of both picocyanobacteria (mostly Synechococcus) and the toxic dinoflagellate Alexandrium catenella in Thau seem to be related to reduced nutrient loading and the increase in water temperature. A. catenella blooms occur either in the spring or the fall when water temperature is near 20 °C and remains so for several weeks with winds speeds below 2-3 m s - 1 . Picocyanobacterial growth is stimulated by increased summer temperatures, and lowered SRP levels provide picocyanobacteria an ecological advantage over other phytoplankton classes, in particular diatoms such as Skeletonema costatum whose cell densities have decreased over the last 8 years in summer and fall, but not in winter. An hypothesis is presented according to which A. catenella is not stimulated by increased temperatures, but is able to use picocyanobacteria for growth, and this provides this organism an additional resource over other strictly

  13. 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

    NASA Astrophysics Data System (ADS)

    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

  14. 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

    PubMed Central

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

    2013-01-01

    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

  15. Latest Quaternary palaeoceanographic change in the eastern North Atlantic based upon a dinoflagellate cyst event ecostratigraphy.

    PubMed

    Harland, Rex; Polovodova Asteman, Irina; Morley, Audrey; Morris, Angela; Harris, Anthony; Howe, John A

    2016-05-01

    The analyses of dinoflagellate cyst records, from the latest Quaternary sediments recovered from DSDP Core 610A taken on the Feni Ridge in the southern Rockall Trough, and part of core MD01-2461 on the continental margin of the Porcupine Seabight in the eastern North Atlantic Ocean, has provided evidence for significant oceanographic change encompassing the Last Glacial Maximum (LGM) and part of the Holocene. This together with other published records has led to a regional evaluation of oceanographic change in the eastern North Atlantic over the past 68 ka, based upon a distinctive dinoflagellate event ecostratigraphy. These changes reflect changes in the surface waters of the North Atlantic Current (NAC), and perhaps the deeper thermohaline Atlantic Meridional Overturning Circulation (AMOC), driving fundamental regime changes within the phytoplanktonic communities. Three distinctive dinoflagellate cyst associations based upon both factor and cluster analyses have been recognised. Associations characterised by Bitectatodinium tepikiense (between 61.1 ± 6.2 to 13.4 ± 1.1 ka BP), Nematosphaeropsis labyrinthus (between 10.5 ± 0.3 and 11.45 ± 0.8 ka. BP), and the cyst of Protoceratium reticulatum (between 8.5 ± 0.9 and 5.2 ± 1.3 ka. BP) indicate major change within the eastern North Atlantic oceanography. The transitions between these changes occur over a relatively short time span (c.1.5 ka), given our sampling resolution, and have the potential to be incorporated into an event stratigraphy through the latest Quaternary as recommended by the INTIMATE (INTegrating Ice core, MArine and TErrestrial records) group. The inclusion of a dinoflagellate cyst event stratigraphy would highlight changes within the phytoplankton of the North Atlantic Ocean as a fully glacial world changed to our present interglacial. PMID:27441285

  16. Feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense: feeding mechanism, prey species, and effect of prey concentration.

    PubMed

    Yoo, Yeong Du; Jeong, Hae Jin; Kang, Nam Seon; Song, Jae Yoon; Kim, Kwang Young; Lee, Gitack; Kim, Juhyoung

    2010-01-01

    To investigate the feeding by the newly described mixotrophic dinoflagellate Paragymnodinium shiwhaense (GenBank accession number=AM408889), we explored the feeding process and the kinds of prey species that P. shiwhaense is able to feed on using several different types of microscopes, including a transmission electron microscope and high-resolution video-microscopy. In addition, we measured the growth and ingestion rates of P. shiwhaense on its optimal algal prey Amphidinium carterae as a function of prey concentration. We also measured these parameters for edible prey at a single concentration at which the growth and ingestion rates of P. shiwhaense on A. carterae were saturated. Paragymnodinium shiwhaense feed on algal prey using a peduncle after anchoring the prey by a tow filament. Among the algal prey offered, P. shiwhaense ingested small algal species that had equivalent spherical diameters (ESDs) < or =11 microm (e.g. the prymnesiophyte Isochrysis galbana, the cryptophytes Teleaulax sp. and Rhodomonas salina, the raphidophyte Heterosigma akashiwo, and the dinoflagellates Heterocapsa rotundata and A. carterae). However, it did not feed on larger algal species that had ESDs > or =12 microm (e.g. the dinoflagellates Prorocentrum minimum, Heterocapsa triquetra, Scrippsiella trochoidea, Alexandrium tamarense, Prorocentrum micans, Gymnodinium catenatum, Akashiwo sanguinea, and Lingulodinium polyedrum) or the small diatom Skeletonema costatum. The specific growth rates for P. shiwhaense feeding upon A. carterae increased rapidly with increasing mean prey concentration before saturating at concentrations of ca. 350 ng C/ml (5,000 cells/ml). The maximum specific growth rate (i.e. mixotrophic growth) of P. shiwhaense on A. carterae was 1.097/d at 20 degrees C under a 14:10 h light-dark cycle of 20 microE/m(2)/s, while its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was -0.224/d. The maximum ingestion and clearance rates

  17. Intracellular pH of symbiotic dinoflagellates

    NASA Astrophysics Data System (ADS)

    Gibbin, E. M.; Davy, S. K.

    2013-09-01

    Intracellular pH (pHi) is likely to play a key role in maintaining the functional success of cnidarian-dinoflagellate symbiosis, yet until now the pHi of the symbiotic dinoflagellates (genus Symbiodinium) has never been quantified. Flow cytometry was used in conjunction with the ratiometric fluorescent dye BCECF to monitor changes in pHi over a daily light/dark cycle. The pHi of Symbiodinium type B1 freshly isolated from the model sea anemone Aiptasia pulchella was 7.25 ± 0.01 (mean ± SE) in the light and 7.10 ± 0.02 in the dark. A comparable effect of irradiance was seen across a variety of cultured Symbiodinium genotypes (types A1, B1, E1, E2, F1, and F5) which varied between pHi 7.21-7.39 in the light and 7.06-7.14 in the dark. Of note, there was a significant genotypic difference in pHi, irrespective of irradiance.

  18. Inducible Mixotrophy in the Dinoflagellate Prorocentrum minimum.

    PubMed

    Johnson, Matthew D

    2015-01-01

    Prorocentrum minimum is a neritic dinoflagellate that forms seasonal blooms and red tides in estuarine ecosystems. While known to be mixotrophic, previous attempts to document feeding on algal prey have yielded low grazing rates. In this study, growth and ingestion rates of P. minimum were measured as a function of nitrogen (-N) and phosphorous (-P) starvation. A P. minimum isolate from Chesapeake Bay was found to ingest cryptophyte prey when in stationary phase and when starved of N or P. Prorocentrum minimum ingested two strains of Teleaulax amphioxeia at higher rates than six other cryptophyte species. In all cases -P treatments resulted in the highest grazing. Ingestion rates of -P cells on T. amphioxeia saturated at ~5 prey per predator per day, while ingestion by -N cells saturated at 1 prey per predator per day. In the presence of prey, -P treated cells reached a maximum mixotrophic growth rate (μmax ) of 0.5 d(-1), while -N cells had a μmax of 0.18 d(-1). Calculations of ingested C, N, and P due to feeding on T. amphioxeia revealed that phagotrophy can be an important source of all three elements. While P. minimum is a proficient phototroph, inducible phagotrophy is an important nutritional source for this dinoflagellate. PMID:25510417

  19. Bubble stimulation efficiency of dinoflagellate bioluminescence.

    PubMed

    Deane, Grant B; Stokes, M Dale; Latz, Michael I

    2016-02-01

    Dinoflagellate bioluminescence, a common source of bioluminescence in coastal waters, is stimulated by flow agitation. Although bubbles are anecdotally known to be stimulatory, the process has never been experimentally investigated. This study quantified the flash response of the bioluminescent dinoflagellate Lingulodinium polyedrum to stimulation by bubbles rising through still seawater. Cells were stimulated by isolated bubbles of 0.3-3 mm radii rising at their terminal velocity, and also by bubble clouds containing bubbles of 0.06-10 mm radii for different air flow rates. Stimulation efficiency, the proportion of cells producing a flash within the volume of water swept out by a rising bubble, decreased with decreasing bubble radius for radii less than approximately 1 mm. Bubbles smaller than a critical radius in the range 0.275-0.325 mm did not stimulate a flash response. The fraction of cells stimulated by bubble clouds was proportional to the volume of air in the bubble cloud, with lower stimulation levels observed for clouds with smaller bubbles. An empirical model for bubble cloud stimulation based on the isolated bubble observations successfully reproduced the observed stimulation by bubble clouds for low air flow rates. High air flow rates stimulated more light emission than expected, presumably because of additional fluid shear stress associated with collective buoyancy effects generated by the high air fraction bubble cloud. These results are relevant to bioluminescence stimulation by bubbles in two-phase flows, such as in ship wakes, breaking waves, and sparged bioreactors. PMID:26061152

  20. Genome evolution of a tertiary dinoflagellate plastid.

    PubMed

    Gabrielsen, Tove M; Minge, Marianne A; Espelund, Mari; Tooming-Klunderud, Ave; Patil, Vishwanath; Nederbragt, Alexander J; Otis, Christian; Turmel, Monique; Shalchian-Tabrizi, Kamran; Lemieux, Claude; Jakobsen, Kjetill S

    2011-01-01

    The dinoflagellates have repeatedly replaced their ancestral peridinin-plastid by plastids derived from a variety of algal lineages ranging from green algae to diatoms. Here, we have characterized the genome of a dinoflagellate plastid of tertiary origin in order to understand the evolutionary processes that have shaped the organelle since it was acquired as a symbiont cell. To address this, the genome of the haptophyte-derived plastid in Karlodinium veneficum was analyzed by Sanger sequencing of library clones and 454 pyrosequencing of plastid enriched DNA fractions. The sequences were assembled into a single contig of 143 kb, encoding 70 proteins, 3 rRNAs and a nearly full set of tRNAs. Comparative genomics revealed massive rearrangements and gene losses compared to the haptophyte plastid; only a small fraction of the gene clusters usually found in haptophytes as well as other types of plastids are present in K. veneficum. Despite the reduced number of genes, the K. veneficum plastid genome has retained a large size due to expanded intergenic regions. Some of the plastid genes are highly diverged and may be pseudogenes or subject to RNA editing. Gene losses and rearrangements are also features of the genomes of the peridinin-containing plastids, apicomplexa and Chromera, suggesting that the evolutionary processes that once shaped these plastids have occurred at multiple independent occasions over the history of the Alveolata. PMID:21541332

  1. Genome Evolution of a Tertiary Dinoflagellate Plastid

    PubMed Central

    Espelund, Mari; Tooming-Klunderud, Ave; Patil, Vishwanath; Nederbragt, Alexander J.; Otis, Christian; Turmel, Monique; Shalchian-Tabrizi, Kamran; Lemieux, Claude; Jakobsen, Kjetill S.

    2011-01-01

    The dinoflagellates have repeatedly replaced their ancestral peridinin-plastid by plastids derived from a variety of algal lineages ranging from green algae to diatoms. Here, we have characterized the genome of a dinoflagellate plastid of tertiary origin in order to understand the evolutionary processes that have shaped the organelle since it was acquired as a symbiont cell. To address this, the genome of the haptophyte-derived plastid in Karlodinium veneficum was analyzed by Sanger sequencing of library clones and 454 pyrosequencing of plastid enriched DNA fractions. The sequences were assembled into a single contig of 143 kb, encoding 70 proteins, 3 rRNAs and a nearly full set of tRNAs. Comparative genomics revealed massive rearrangements and gene losses compared to the haptophyte plastid; only a small fraction of the gene clusters usually found in haptophytes as well as other types of plastids are present in K. veneficum. Despite the reduced number of genes, the K. veneficum plastid genome has retained a large size due to expanded intergenic regions. Some of the plastid genes are highly diverged and may be pseudogenes or subject to RNA editing. Gene losses and rearrangements are also features of the genomes of the peridinin-containing plastids, apicomplexa and Chromera, suggesting that the evolutionary processes that once shaped these plastids have occurred at multiple independent occasions over the history of the Alveolata. PMID:21541332

  2. Heat Shock Protein 70 and 90 Genes in the Harmful Dinoflagellate Cochlodinium polykrikoides: Genomic Structures and Transcriptional Responses to Environmental Stresses

    PubMed Central

    Guo, Ruoyu; Youn, Seok Hyun; Ki, Jang-Seu

    2015-01-01

    The marine dinoflagellate Cochlodinium polykrikoides is responsible for harmful algal blooms in aquatic environments and has spread into the world's oceans. As a microeukaryote, it seems to have distinct genomic characteristics, like gene structure and regulation. In the present study, we characterized heat shock protein (HSP) 70/90 of C. polykrikoides and evaluated their transcriptional responses to environmental stresses. Both HSPs contained the conserved motif patterns, showing the highest homology with those of other dinoflagellates. Genomic analysis showed that the CpHSP70 had no intron but was encoded by tandem arrangement manner with separation of intergenic spacers. However, CpHSP90 had one intron in the coding genomic regions, and no intergenic region was found. Phylogenetic analyses of separate HSPs showed that CpHSP70 was closely related with the dinoflagellate Crypthecodinium cohnii and CpHSP90 with other Gymnodiniales in dinoflagellates. Gene expression analyses showed that both HSP genes were upregulated by the treatments of separate algicides CuSO4 and NaOCl; however, they displayed downregulation pattern with PCB treatment. The transcription of CpHSP90 and CpHSP70 showed similar expression patterns under the same toxicant treatment, suggesting that both genes might have cooperative functions for the toxicant induced gene regulation in the dinoflagellate. PMID:26064872

  3. Repercussions of salinity changes and osmotic stress in marine phytoplankton species

    NASA Astrophysics Data System (ADS)

    D'ors, A.; Bartolomé, M. C.; Sánchez-Fortún, S.

    2016-06-01

    The short-term effect of low salinity was studied using laboratory protocols on some coastal phytoplankton species such as chlorophycea Tetraselmis suecica, among diatom the strain Nitzschia N1c1 and dinoflagellates Alexandrium minutum and Prorocentrum lima. All of cultures were exposed to low salinities, and cell growth rate, photosynthetic quantum yield (ΦPSII), and gross photosynthesis (Pg) were analyzed. Growth rate inhibition was similar in all species, and all of them also tolerate short-term exposures to salinities in the range 5-35. There were no significant differences between ΦPSII and Pg endpoints from Tetraselmis suecica and Nitzschia sp., while Alexandrium minutum and Prorocentrum lima displayed a higher affectation rate on Pg than on ΦPSII activity. The influence of low salinity was higher on respiration in T. suecica, while both dinoflagellates had higher net photosynthesis. Nitzschia sp. exhibited similar involvement of the two photosynthetic parameters. Therefore, although the four phytoplankton monocultures studied are able to survive in internal areas of estuaries under low salinity conditions, the photosynthetic activity is more affected than the growth rate in all phytoplankton communities studied except in chlorophycea T. suecica, which has increased tolerance for this salinity decrease.

  4. Molecular phylogeny of symbiotic dinoflagellates from planktonic foraminifera and radiolaria.

    PubMed

    Gast, R J; Caron, D A

    1996-11-01

    Recent analyses of the small subunit ribosomal DNA (srDNA) from dinoflagellate symbionts of cnidaria have confirmed historical descriptions of a diverse but well-defined clade, Symbiodinium, as well as several other independent symbiont lineages (Rowan 1991; Rowan and Powers 1992; Sadler et al. 1992; McNally et al 1994). Dinoflagellates also occur as intracellular symbionts in a number of pelagic protistan taxa, but the srDNA of these symbionts has not been examined. We analyzed the srDNA sequences of the symbiotic dinoflagellates from four planktonic foraminiferal species and six radiolarian species. The symbionts from these sarcodines formed two distinct lineages within the dinoflagellates. Within each lineage, symbionts obtained from different host species showed few, if any, srDNA sequence differences. The planktonic foraminiferal symbionts were most closely related to Gymnodinium simplex and the Symbiodinium clade, whereas the radiolarian symbionts were most closely related to the dinoflagellate symbiont from the oceanic chondrophore, Velella velella. Therefore, although the dinoflagellate symbionts of foraminifera appear to be a sister taxon of the symbionts from benthic foraminifera and invertebrates, the symbionts of radiolaria are distinct and arose from an independent lineage of dinoflagellate symbionts that shares common ancestry with the symbiont of at least one pelagic metazoan. The lack of srDNA variability within the sarcodine symbiont lineages suggests that coevolution of host and symbiont has not occurred. PMID:8896371

  5. Pigment compositions are linked to the habitat types in dinoflagellates.

    PubMed

    Yamada, Norico; Tanaka, Ayumi; Horiguchi, Takeo

    2015-11-01

    Compared to planktonic species, there is little known about the ecology, physiology, and existence of benthic dinoflagellates living in sandy beach or seafloor environments. In a previous study, we discovered 13(2),17(3)-cyclopheophorbide a enol (cPPB-aE) from sand-dwelling benthic dinoflagellates. This enol had never been detected in phytoplankton despite the fact that it is a chlorophyll a catabolite. We speculated from this discovery that habitat selection might be linked to pigment compositions in dinoflagellates. To test the hypothesis of habitat selection linking to pigment compositions, we conducted extensive analysis of pigments with high performance liquid chromatography (HPLC) for 40 species using 45 strains of dinoflagellates including three habitat types; sand-dwelling benthic forms, tidal pool inhabitants and planktonic species. The 40 dinoflagellates are also able to be distinguished into two types based on their chloroplast origins; red alga-derived secondary chloroplasts and diatom-derived tertiary ones. By plotting the pigments profiles onto three habitats, we noticed that twelve pigments including cPPB-aE were found to occur only in benthic sand-dwelling species of red alga-derived type. The similar tendency was also observed in dinoflagellates with diatom-derived chloroplasts, i.e. additional sixteen pigments including chl c 3 were found only in sand-dwelling forms. This is the first report of the occurrence of chl c 3 in dinoflagellates with diatom-derived chloroplasts. These results clarify that far greater diversity of pigments are produced by the dinoflagellates living in sand regardless of chloroplast types relative to those of planktonic and tidal pool forms. Dinoflagellates seem to produce a part of their pigments in response to their habitats. PMID:26243150

  6. Dinoflagellates in a mesotrophic, tropical environment influenced by monsoon

    NASA Astrophysics Data System (ADS)

    D'Costa, Priya M.; Chandrashekar Anil, Arga; Patil, Jagadish S.; Hegde, Sahana; D'Silva, Maria Shamina; Chourasia, Molji

    2008-03-01

    The changes in dinoflagellate community structure in both - the water column and sediment in a mesotrophic, tropical port environment were investigated in this study. Since the South West Monsoon (SWM) is the main source of climatic variation, observations were made during two consecutive post-monsoon periods (2001 and 2002) and the intervening pre-monsoon period (2002). The pre-monsoon period supported a more diverse dinoflagellate community in the water column compared to both post-monsoon periods. Heterotrophic dinoflagellates were abundant in the water column as well as sediment. A seasonal cycling between vegetative and resting cysts of autotrophic and heterotrophic dinoflagellates governed by the environmental characteristics of the study area was observed. Temperature, salinity and suspended particulate matter were the main factors affecting dinoflagellate community structure in both the water column and sediment. The dominant dinoflagellates in the water column differed during both post-monsoon periods that followed two dissimilar monsoon events. Prorocentroids and gonyaulacoids dominated the water column subsequent to the 2001 SWM, whereas dinophysoids and unidentified tiny dinoflagellates dominated during the next post-monsoon period. The 2001 SWM started in May, peaked during June-July and reduced gradually to end in October. The 2002 SWM was erratic; it started late (in June) and ended earlier (in September). These observations highlight the potential of the SWM to influence the community structure of dinoflagellates in tropical waters and points to the importance of long-term studies to discern robust variations in dinoflagellate communities in response to fluctuating monsoon regimes.

  7. Population dynamics of red tide dinoflagellates

    NASA Astrophysics Data System (ADS)

    Wyatt, Timothy; Zingone, Adriana

    2014-03-01

    Sea-surface discolorations due to high concentrations of phytoplankton are called red tides. Their ecological significance is a long standing puzzle, and they are sometimes considered pathological. Here we propose that many red tides, particularly but not exclusively those composed of certain autotrophic dinoflagellates, are presexual/sexual swarms, essential links in their complex life cycles. This view provides a rationale for the appearance of these organisms in thin surface layers, and helps explain their ephemeral nature. We suggest that further understanding of this phenomenon, and of phytoplankton ecology in general, would benefit from attention to the 'net reproductive value‧ (r) over the whole life cycle as well as to the division rate (μ) of the vegetative phase. It is argued that r is strategically adapted to seasonal cycles and long term environmental variability, while μ reflects tactical needs (timing) and constraints (grazers, parasites) on vegetative growth.

  8. Photoregulation in a Kleptochloroplastidic Dinoflagellate, Dinophysis acuta

    PubMed Central

    Hansen, Per J.; Ojamäe, Karin; Berge, Terje; Trampe, Erik C. L.; Nielsen, Lasse T.; Lips, Inga; Kühl, Michael

    2016-01-01

    Some phagotrophic organisms can retain chloroplasts of their photosynthetic prey as so-called kleptochloroplasts and maintain their function for shorter or longer periods of time. Here we show for the first time that the dinoflagellate Dinophysis acuta takes control over “third-hand” chloroplasts obtained from its ciliate prey Mesodinium spp. that originally ingested the cryptophyte chloroplasts. With its kleptochloroplasts, D. acuta can synthesize photosynthetic as well as photoprotective pigments under long-term starvation in the light. Variable chlorophyll fluorescence measurements showed that the kleptochloroplasts were fully functional during 1 month of prey starvation, while the chlorophyll a-specific inorganic carbon uptake decreased within days of prey starvation under an irradiance of 100 μmol photons m-2 s-1. While D. acuta cells can regulate their pigmentation and function of kleptochloroplasts they apparently lose the ability to maintain high inorganic carbon fixation rates. PMID:27303378

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

    PubMed

    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. PMID:26032975

  10. Eutrophication signals in the sedimentary record of dinoflagellate cysts in coastal waters

    NASA Astrophysics Data System (ADS)

    Dale, Barrie

    2009-01-01

    (supporting earlier postulations by fisheries biologists that eutrophication was a possible cause). They also link these local eutrophication events to regional variation in the NAO, thought to have caused pulses of nutrient loading within the Skagerrak from increased transport of relatively nutrient rich North Sea water into the system. This may represent a major breakthrough in understanding the relationship between climatic variation and coastal eutrophication. Some concluding remarks are added in an attempt to show how these cyst signals: 1) suggest interesting comparisons with the ecological classification of bloom dinoflagellates by Smayda and Reynolds [Smayda, T.J., Reynolds, C.S., 2003. Strategies of marine dinoflagellate survival and some rules of assembly. J. Sea Res. 49, 95-106.]; and 2) have helped to identify important questions regarding the extent to which climate variation influences coastal eutrophication. Addressing these questions represents an urgent challenge to marine science.

  11. Dinoflagellate biogeochemistry: developing new proxies for past carbon cycling (Invited)

    NASA Astrophysics Data System (ADS)

    Sluijs, A.; Hoins, M.; van de Waal, D.; Reichart, G.; Rost, B.

    2013-12-01

    Accurate reconstructions of atmospheric CO2 levels for time intervals that are beyond the reach of the ice cores (> ~850 kyr) remain one of the grand challenges of paleoclimate and paleoenvironmental research. Despite recent progress in analytical techniques and application in several proxies, uncertainties in reconstructed values remain large. Based on culturing experiments combined with gene expression analysis and physiological assays, we quantify and mechanistically underpin the geochemical response of dinoflagellates and their cysts to various CO2 concentrations. The results confirm theoretical inferences that the isotopic composition of both organic and calcite dinoflagellate cysts may serve as a proxy for past ocean carbonate chemistry, notably pCO2. We found a strong effect (~10x as strong as in foraminifera) of pCO2 on the stable oxygen isotopic composition of a calcareous dinoflagellate cyst. Moreover, we found that the stable carbon isotopic composition of four dinoflagellate species, of which two have organic dinocyst fossil records down to the early Cenozoic and Cretaceous, strongly respond to pCO2. Critically, the experiments show that the mechanisms forcing the changes in fractionation factors differ between species, opening a suite of opportunities to study past carbon cycling as well as protist physiology during Earth System perturbations. The dinoflagellate Apectodinium dominated dinoflagellate assemblages during the Paleocene-Eocene Thermal Maximum. Will its carbon isotopic composition reveal CO2 concentrations at that time?

  12. Evaluation of photo-reactive siderophore producing bacteria before, during and after a bloom of the dinoflagellate Lingulodinium polyedrum.

    PubMed

    Yarimizu, Kyoko; Polido, Geraldine; Gärdes, Astrid; Carter, Melissa L; Hilbern, Mary; Carrano, Carl J

    2014-06-01

    Evidence is increasing for a mutualistic relationship between phytoplankton and heterotrophic marine bacteria. It has been proposed that bacteria producing photoactive iron binding compounds known as siderophores could play an important role in such mutualistic associations by producing bioavailable iron utilizable by phytoplankton and in exchange receive autotrophically derived DOM. In order to understand the potential role photoactive siderophores might be playing in bacterial-algal mutualism or marine biogeochemistry in general, it is important to be able to detect and quantify their presence in various environments. One approach to accomplish that end is to make use of high sensitivity genomics technology (qPCR) to search for siderophore biosynthesis genes related to the production of photoactive siderophores. In this way one can access their "biochemical potential" and utilize this information as a proxy for the presence of these siderophores in the marine environment. In this report we studied the correlation of the presence of bacteria producing one of the three photoactive siderophores relative to total bacterial and dinoflagellate numbers from surface water at the Scripps Pier before, during, and after fall bloom of the dinoflagellate Lingulodinium polyedrum. We believe that these findings will aid us in gauging the importance of photoactive siderophores in the marine environment and in harmful algal bloom dynamics in particular. PMID:24760287

  13. Development of a Dinoflagellate-Oriented PCR Primer Set Leads to Detection of Picoplanktonic Dinoflagellates from Long Island Sound†

    PubMed Central

    Lin, Senjie; Zhang, Huan; Hou, Yubo; Miranda, Lilibeth; Bhattacharya, Debashish

    2006-01-01

    We developed dinoflagellate-specific 18S rRNA gene primers. PCR amplification using these oligonucleotides for a picoplanktonic DNA sample from Long Island Sound yielded 24 clones, and all but one of these clones were dinoflagellates primarily belonging to undescribed and Amoebophrya-like lineages. These results highlight the need for a systematic investigation of picodinoflagellate diversity in both coastal and oceanic ecosystems. PMID:16885319

  14. Effect of Oxidative Stress Induced by Brevibacterium sp. BS01 on a HAB Causing Species-Alexandrium tamarense

    PubMed Central

    Zhou, Yanyan; Zhang, Bangzhou; Zhang, Su; Li, Dong; Chen, Zhangran; Li, Yi; Bai, Shijie; Lv, Jinglin; Zheng, Wei; Tian, Yun; Zheng, Tianling

    2013-01-01

    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 ultimately killed the

  15. Late Quaternary climatic and oceanographic changes in the Northeast Pacific as recorded by dinoflagellate cysts from Guaymas Basin, Gulf of California (Mexico)

    NASA Astrophysics Data System (ADS)

    Price, Andrea M.; Mertens, Kenneth N.; Pospelova, Vera; Pedersen, Thomas F.; Ganeshram, Raja S.

    2013-01-01

    A high-resolution record of organic-walled dinoflagellate cyst production in Guaymas Basin, Gulf of California (Mexico) reveals a complex paleoceanographic history over the last ~40 ka. Guaymas Basin is an excellent location to perform high resolution studies of changes in late Quaternary climate and paleo-productivity because it is characterized by high primary productivity, high sedimentation rates, and low oxygen bottom waters. These factors contribute to the deposition and preservation of laminated sediments throughout large portions of the core MD02-2515. In this study, we document dinoflagellate cyst production at a centennial to millennial scale throughout the late Quaternary. Based on the cyst assemblages, three dinoflagellate cyst zones were established and roughly correspond to Marine Isotope Stages (MISs) 1 to 3. MISs 1 and 3 are dominated by cysts of heterotrophic dinoflagellates, whereas MIS 2 is characterized by enhanced variability and a greater proportion of cysts produced by autotrophic taxa. The most dominant dinoflagellate cyst taxa found throughout the core were Brigantedinium spp. and Operculodinium centrocarpum. Dansgaard-Oeschger event 8 is observed in the dinoflagellate cyst record where it is characterized by an increase in warm taxa, such as Spiniferites pachydermus. Other intervals of interest are the Younger Dryas where warmer conditions are recorded and the Holocene which is characterized by the consistent presence of tropical species Stelladinium reidii, Tuberculodinidum vancampoae, Bitectatodinium spongium, and an increase in Quinquecuspis concreta. Changes in cyst assemblages, concentrations, and species diversity, along with geochemical data reflect major orbital to millennial-scale climatic and oceanographic changes.

  16. Dinoflagellate cysts as indicators of millennial scale climatic and oceanographic variability in Guaymas Basin, Gulf of California (Mexico) during the Late Quaternary

    NASA Astrophysics Data System (ADS)

    Price, Andrea M.; Mertens, Kenneth N.; Pospelova, *Vera; Pedersen, Thomas F.; Ganeshram, Raja S.

    2015-04-01

    A high-resolution record of organic-walled dinoflagellate cyst production in Guaymas Basin, Gulf of California (Mexico) reveals a complex paleoceanographic history over the last ~40 ka. Guaymas Basin is an excellent location to perform high resolution studies of changes in Late Quaternary climate and paleo-productivity because it is characterized by high primary productivity, high sedimentation rates, and low oxygen bottom waters. These factors contribute to the deposition and preservation of laminated sediments throughout large portions of core MD02-2515. This is one of the first studies in the Northeast Pacific to document dinoflagellate cyst production at a centennial to millennial scale throughout the Late Quaternary. Based on the cyst assemblages three major dinoflagellate cyst zones were established, and roughly correspond to Marine Isotope Stages 1 to 3. The most dominant dinoflagellate cyst taxa found throughout the core were Brigantedinium spp. and Operculodinium centrocarpum. Dansgaard-Oeschger event 8 is observed in the dinoflagellate cyst record, and is characterized by an increase in warm water taxa such as Spiniferites pachydermus. Other intervals of interest are the Younger Dryas where cooler sea-surface conditions are not recorded, and the Holocene which is characterized by the consistent presence of warm water species Stelladinium reidii, Tuberculodinidum vancampoae, Bitectatodinium spongium and an increase in Quinquecuspis concreta. Changes in cyst assemblages, concentrations and species diversity, along with geochemical data reflect major orbital to millennial-scale climatic and oceanographic changes. Keywords: Dansgaard-Oeschger events; dinoflagellate cyst; Gulf of California; late Quaternary climate change; upwelling; Younger Dryas.

  17. Nuclear and cytoplasmic actin in dinoflagellates.

    PubMed

    Soyer-Gobillard, M O; Ausseil, J; Géraud, M L

    1996-01-01

    Experiments using monoclonal and polyclonal anti-actin antibodies allowed us to demonstrate the presence of F- or G-actin in original protists, dinoflagellates, either by biochemistry, immunofluorescence and in TEM. SDS-PAGE electrophoresis and immunoblottings made either from total or nuclear protein extracts revealed the presence of a 44-kDa band reacting with monoclonal anti-actin antibody in two species, Prorocentrum micans and Crypthecodinium cohnii, and thus demonstrated the presence of actin in nuclear and cytoplasmic fractions. After squash preparation of P micans cells, actin was identified within the nucleus and in some regions of the cytoplasm by immunofluorescence microscopy. Labelling of both the nucleolus and the centrosome region was evident together with amorphous nucleoplasmic material surrounding the chromosomes. The use of cryosections of intact P micans and C cohnii cells for immunofluorescence along with staining with DAPI to delineate the chromosomes themselves, yielded finer resolution of the intranuclear network labelling pattern and allowed us to complete our observations, in particular on the cytoplasmic labelling. In P micans, in addition to the centrosome region, the cytoplasmic channels passing through the nucleus in dividing cells are labelled. In C cohnii, the cortex, the centrosome region, the cytoplasmic channels, the region surrounding the nucleus, the filaments linking it to the cortex and the cleavage furrow are also labelled. In the nucleus of the two species, there is a prominent "weft' of fine actin filaments in the nucleoplasm forming a matrix of varying density around the persistent chromosomes. This actin matrix, of unknown function, is most conspicuous at the end of the S-phase of the cell cycle. Fluorescent derivatives of phalloidin, used as diagnostic cytochemical probes for polymeric actin (F-actin), gave similar results. Positive TEM immunolabelling of intranuclear actin confirms its presence in the nucleoplasm, in the

  18. Multi-gene analysis of Symbiodinium dinoflagellates: a perspective on rarity, symbiosis, and evolution

    PubMed Central

    Putnam, Hollie M.; Gates, Ruth D.

    2014-01-01

    Symbiodinium, a large group of dinoflagellates, live in symbiosis with marine protists, invertebrate metazoans, and free-living in the environment. Symbiodinium are functionally variable and play critical energetic roles in symbiosis. Our knowledge of Symbiodinium has been historically constrained by the limited number of molecular markers available to study evolution in the genus. Here we compare six functional genes, representing three cellular compartments, in the nine known Symbiodinium lineages. Despite striking similarities among the single gene phylogenies from distinct organelles, none were evolutionarily identical. A fully concatenated reconstruction, however, yielded a well-resolved topology identical to the current benchmark nr28S gene. Evolutionary rates differed among cellular compartments and clades, a pattern largely driven by higher rates of evolution in the chloroplast genes of Symbiodinium clades D2 and I. The rapid rates of evolution observed amongst these relatively uncommon Symbiodinium lineages in the functionally critical chloroplast may translate into potential innovation for the symbiosis. The multi-gene analysis highlights the potential power of assessing genome-wide evolutionary patterns using recent advances in sequencing technology and emphasizes the importance of integrating ecological data with more comprehensive sampling of free-living and symbiotic Symbiodinium in assessing the evolutionary adaptation of this enigmatic dinoflagellate. PMID:24883254

  19. A giant cell surface protein in Synechococcus WH8102 inhibits feeding by a dinoflagellate predator.

    PubMed

    Strom, Suzanne L; Brahamsha, Bianca; Fredrickson, Kerri A; Apple, Jude K; Rodríguez, Andres Gutiérrez

    2012-03-01

    Diverse strains of the marine planktonic cyanobacterium Synechococcus sp. show consistent differences in their susceptibility to predation. We used mutants of Sargasso Sea strain WH8102 (clade III) to test the hypothesis that cell surface proteins play a role in defence against predation by protists. Predation rates by the heterotrophic dinoflagellate Oxyrrhis marina on mutants lacking the giant SwmB protein were always higher (by 1.6 to 3.9×) than those on wild-type WH8102 cells, and equalled predation rates on a clade I strain (CC9311). In contrast, absence of the SwmA protein, which comprises the S-layer (surface layer of the cell envelope that is external to the outer membrane), had no effect on predation by O. marina. Reductions in predation rate were not due to dissolved substances in Synechococcus cultures, and could not be accounted for by variations in cell hydrophobicity. We hypothesize that SwmB defends Synechococcus WH8102 by interfering with attachment of dinoflagellate prey capture organelles or cell surface receptors. Giant proteins are predicted in the genomes of multiple Synechococcus isolates, suggesting that this defence strategy may be more general. Strategies for resisting predation will contribute to the differential competitive success of different Synechococcus groups, and to the diversity of natural picophytoplankton assemblages. PMID:22103339

  20. Dinoflagellate diversity among nudibranchs and sponges from French Polynesia: insights into associations and transfer.

    PubMed

    Wecker, Patricia; Fournier, Alice; Bosserelle, Pauline; Debitus, Cécile; Lecellier, Gaël; Berteaux-Lecellier, Véronique

    2015-04-01

    Symbioses with the dinoflagellate Symbiodinium are widespread among marine invertebrates and protists, especially in nutritionally demanding habitats, such as tropical coral reefs, where they play a major role in ecosystem survival. Moreover, apart from corals and sea anemones, many of the Symbiodinium species and clades involved in these partnerships remain to be characterized. This study provides new insights into nudibranch and sponge associations with Symbiodinium by sequencing regions of the Symbiodinium 28S rDNA and the host mitochondrial COI oxidase. Specimens were sampled between 2011 and 2013 from locations around the islands of Moorea and Tahiti, French Polynesia. Our results revealed that some of the sponges and nudibranchs harbored typical Symbiodinium from clade B or C while others harbored new, undescribed Symbiodinium-like dinoflagellates. A detailed analysis of the different life stages of the nudibranch Phestilla lugubris and of its specific coral prey, Porites rus, suggests a prey-predator horizontal transfer of the symbiont and its vertical inheritance from the parent to the eggs. PMID:25747266

  1. Potential distribution of the invasive freshwater dinoflagellate Ceratium furcoides (Levander) Langhans (Dinophyta) in South America.

    PubMed

    Meichtry de Zaburlín, Norma; Vogler, Roberto E; Molina, María J; Llano, Víctor M

    2016-04-01

    Dinoflagellates of the genus Ceratium are predominantly found in marine environments, with a few species in inland waters. Over the last decades, the freshwater species Ceratium hirundinella and Ceratium furcoides have colonized and invaded several South American basins. The purpose of this study was to create a distribution model for the invasive dinoflagellate C. furcoides in South America in order to further investigate the basins at potential risk, as well as the environmental conditions that influence its expansion. This species is known to develop blooms due to its mobility, resistance to sedimentation, and optimized use of resources. Although nontoxic, blooms of the species cause many problems to both the natural ecosystems and water users. Potential distribution was predicted by using a maximum entropy algorithm (MaxEnt). Model was run with 101 occurrences obtained from the scientific literature, and climatic, hydrological and topographic variables. The developed model had a very good performance for the study area. The most susceptible areas identified were mainly concentrated in the basins between southeastern Brazil and northeastern Argentina. Besides already affected regions, new potentially suitable areas were identified in temperate regions of South America. The information generated here will be useful for authorities responsible for water and watershed management to monitor the spread of this species and address problems related to its establishment in new environments. PMID:27037585

  2. [Harmful blooms of cyanobacteria (Oscillatoriaceae) and dinoflagellates (Gymnodiniaceae) in the Golfo de Nicoya, Costa Rica].

    PubMed

    Vargas-Montero, Maribelle; Freer, Enrique

    2004-09-01

    Recently, the Pacific coast of Costa Rica has experienced an increase in both magnitude and frequency of harmful algae blooms (HAB). The lack of data regarding the dynamics of these events in the area, and the species of microalgae that produce them, are themes of great interest. The blooms have produced negative impacts on fishery resources and on human health in Costa Rica. In May 2002 a HAB left a large number of dead fish along the central Pacific coast. Water samples were collected using a phytoplankton net and fixed for subsequent processing by electron microscopy. In addition, a one liter sample of surface water was taken for later cell count. In the observed HAB, the dominating organisms found were the cyanobacteria Trichodesmiun erythraeum surrounded by high concentrations of Gram-bacteria and the dinoflagellate Cochlodinium cf. polykrikoides. T. erythraeum, is one of the most important N2 fixing cyanobacteria in marine waters that has been associated with HAB events in diverse parts of the world as well as with symptoms that produce contact dermatitis and other discomforts. C. cf. polykrikoides is a dinoflagellete associated with fish kills; although the type of associated toxins are unknown. In a national newspaper 17 cases of intoxication in humans were reported during this same period, which presented respiratory disorders and burning of the eyes. This is the first report in Costa Rica where a cyanobacteria and a dinoflagellate were observed together producing HAB. PMID:17465125

  3. Toxic dinoflagellates (Dinophyceae) from Rarotonga, Cook Islands.

    PubMed

    Rhodes, Lesley L; Smith, Kirsty F; Munday, Rex; Selwood, Andy I; McNabb, Paul S; Holland, Patrick T; Bottein, Marie-Yasmine

    2010-10-01

    Dinoflagellate species isolated from the green calcareous seaweed, Halimeda sp. J.V. Lamouroux, growing in Rarotongan lagoons, included Gambierdiscus australes Faust & Chinain, Coolia monotis Meunier, Amphidinium carterae Hulburth, Prorocentrum lima (Ehrenberg) Dodge, P. cf. maculosum Faust and species in the genus Ostreopsis Schmidt. Isolates were identified to species level by scanning electron microscopy and/or DNA sequence analysis. Culture extracts of G. australes isolate CAWD149 gave a response of 0.04 pg P-CTX-1 equiv. per cell by an N2A cytotoxicity assay (equivalent to ca 0.4 pg CTX-3C cell(-1)). However, ciguatoxins were not detected by LC-MS/MS. Partitioned fractions of the cell extracts potentially containing maitotoxin were found to be very toxic to mice after intraperitoneal (i.p.) injection. A. carterae was also of interest as extracts of mass cultures caused respiratory paralysis in mice at high doses, both by i.p. injection and by oral administration. The Rarotongan isolate fell into a different clade to New Zealand A. carterae isolates, based on DNA sequence analysis, and also had a different toxin profile. As A. carterae co-occurred with G. australes, it may contribute to human poisonings attributed to CTX and warrants further investigation. A crude extract of C. monotis was of low toxicity to mice by i.p. injection, and an extract of Ostreopsis sp. was negative in the palytoxin haemolysis neutralisation assay. PMID:19481563

  4. New Host Range for Hematodinium in Southern Australia and Novel Tools for Sensitive Detection of Parasitic Dinoflagellates

    PubMed Central

    Gornik, Sebastian G.; Cranenburgh, Andrea; Waller, Ross F.

    2013-01-01

    Hematodinium is a parasitic dinoflagellate and emerging pathogen of crustaceans. It preferably manifests in haemolymph of marine decapod crustaceans, killing a large variety of genera with significant impacts on fisheries worldwide. There is, however, evidence that some crustacean stocks harbor high prevalence, low intensity infections that may not result in widespread host mortality and are therefore hard to detect. The most widely used methods for detection of Hematodinium are conventional blood smears and polymerase chain reaction (PCR) against ribosomal RNAs. Blood smears demand a trained investigator, are labor intensive and not readily scalable for high-throughput sampling. PCRs only detect parasite DNA and can also suffer from false negatives and positives. In order to develop alternative detection tools for Hematodinium cells in decapod crustaceans we employed an immunological approach against a newly identified, abundant dinoflagellate-specific nuclear protein—Dinoflagellate/Viral NucleoProtein (DVNP). Both immunofluorescence assay (IFA) and Western blot methods against DVNP showed high sensitivity of detection. The Western blot detects Hematodinium parasites to levels of 25 parasites per milliliter of crustacean haemolymph, with the potential for sample pooling and screening of large samples. Using both PCR and these new tools, we have identified Hematodinium cells present in three new host crab taxa, at high prevalence but with no sign of pathogenesis. This extends the known range of Hematodinium to southern Australia. PMID:24324829

  5. Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine

    PubMed Central

    Butman, Bradford; Aretxabaleta, Alfredo L.; Dickhudt, Patrick J.; Dalyander, P. Soupy; Sherwood, Christopher R.; Anderson, Donald M.; Keafer, Bruce A.; Signell, Richard P.

    2014-01-01

    Cysts of Alexandrium fundyense, a dinoflagellate that causes toxic algal blooms in the Gulf of Maine, spend the winter as dormant cells in the upper layer of bottom sediment or the bottom nepheloid layer and germinate in spring to initiate new blooms. Erosion measurements were made on sediment cores collected at seven stations in the Gulf of Maine in the autumn of 2011 to explore if resuspension (by waves and currents) could change the distribution of over-wintering cysts from patterns observed in the previous autumn; or if resuspension could contribute cysts to the water column during spring when cysts are viable. The mass of sediment eroded from the core surface at 0.4 Pa ranged from 0.05 kg m−2 near Grand Manan Island, to 0.35 kg m−2 in northern Wilkinson Basin. The depth of sediment eroded ranged from about 0.05 mm at a station with sandy sediment at 70 m water depth on the western Maine shelf, to about 1.2 mm in clayey–silt sediment at 250 m water depth in northern Wilkinson Basin. The sediment erodibility measurements were used in a sediment-transport model forced with modeled waves and currents for the period October 1, 2010 to May 31, 2011 to predict resuspension and bed erosion. The simulated spatial distribution and variation of bottom shear stress was controlled by the strength of the semi-diurnal tidal currents, which decrease from east to west along the Maine coast, and oscillatory wave-induced currents, which are strongest in shallow water. Simulations showed occasional sediment resuspension along the central and western Maine coast associated with storms, steady resuspension on the eastern Maine shelf and in the Bay of Fundy associated with tidal currents, no resuspension in northern Wilkinson Basin, and very small resuspension in western Jordan Basin. The sediment response in the model depended primarily on the profile of sediment erodibility, strength and time history of bottom stress, consolidation time scale, and the current in the water

  6. Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine

    USGS Publications Warehouse

    Butman, Bradford; Aretxabaleta, Alfredo L.; Dickhudt, Patrick J.; Dalyander, P. Soupy; Sherwood, Christopher R.; Anderson, Donald M.; Keafer, Bruce A.; Signell, Richard P.

    2014-01-01

    Cysts of Alexandrium fundyense, a dinoflagellate that causes toxic algal blooms in the Gulf of Maine, spend the winter as dormant cells in the upper layer of bottom sediment or the bottom nepheloid layer and germinate in spring to initiate new blooms. Erosion measurements were made on sediment cores collected at seven stations in the Gulf of Maine in the autumn of 2011 to explore if resuspension (by waves and currents) could change the distribution of over-wintering cysts from patterns observed in the previous autumn; or if resuspension could contribute cysts to the water column during spring when cysts are viable. The mass of sediment eroded from the core surface at 0.4 Pa ranged from 0.05 kg m−2 near Grand Manan Island, to 0.35 kg m−2 in northern Wilkinson Basin. The depth of sediment eroded ranged from about 0.05 mm at a station with sandy sediment at 70 m water depth on the western Maine shelf, to about 1.2 mm in clayey–silt sediment at 250 m water depth in northern Wilkinson Basin. The sediment erodibility measurements were used in a sediment-transport model forced with modeled waves and currents for the period October 1, 2010 to May 31, 2011 to predict resuspension and bed erosion. The simulated spatial distribution and variation of bottom shear stress was controlled by the strength of the semi-diurnal tidal currents, which decrease from east to west along the Maine coast, and oscillatory wave-induced currents, which are strongest in shallow water. Simulations showed occasional sediment resuspension along the central and western Maine coast associated with storms, steady resuspension on the eastern Maine shelf and in the Bay of Fundy associated with tidal currents, no resuspension in northern Wilkinson Basin, and very small resuspension in western Jordan Basin. The sediment response in the model depended primarily on the profile of sediment erodibility, strength and time history of bottom stress, consolidation time scale, and the current in the water

  7. Investigating the importance of sediment resuspension in Alexandrium fundyense cyst population dynamics in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Butman, Bradford; Aretxabaleta, Alfredo L.; Dickhudt, Patrick J.; Dalyander, P. Soupy; Sherwood, Christopher R.; Anderson, Donald M.; Keafer, Bruce A.; Signell, Richard P.

    2014-05-01

    Cysts of Alexandrium fundyense, a dinoflagellate that causes toxic algal blooms in the Gulf of Maine, spend the winter as dormant cells in the upper layer of bottom sediment or the bottom nepheloid layer and germinate in spring to initiate new blooms. Erosion measurements were made on sediment cores collected at seven stations in the Gulf of Maine in the autumn of 2011 to explore if resuspension (by waves and currents) could change the distribution of over-wintering cysts from patterns observed in the previous autumn; or if resuspension could contribute cysts to the water column during spring when cysts are viable. The mass of sediment eroded from the core surface at 0.4 Pa ranged from 0.05 kg m-2 near Grand Manan Island, to 0.35 kg m-2 in northern Wilkinson Basin. The depth of sediment eroded ranged from about 0.05 mm at a station with sandy sediment at 70 m water depth on the western Maine shelf, to about 1.2 mm in clayey-silt sediment at 250 m water depth in northern Wilkinson Basin. The sediment erodibility measurements were used in a sediment-transport model forced with modeled waves and currents for the period October 1, 2010 to May 31, 2011 to predict resuspension and bed erosion. The simulated spatial distribution and variation of bottom shear stress was controlled by the strength of the semi-diurnal tidal currents, which decrease from east to west along the Maine coast, and oscillatory wave-induced currents, which are strongest in shallow water. Simulations showed occasional sediment resuspension along the central and western Maine coast associated with storms, steady resuspension on the eastern Maine shelf and in the Bay of Fundy associated with tidal currents, no resuspension in northern Wilkinson Basin, and very small resuspension in western Jordan Basin. The sediment response in the model depended primarily on the profile of sediment erodibility, strength and time history of bottom stress, consolidation time scale, and the current in the water column

  8. A data mining approach to dinoflagellate clustering according to sterol composition: Correlations with evolutionary history.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examined the sterol compositions of 102 dinoflagellates (including several previously unexamined species) using clustering techniques as a means of determining the relatedness of the organisms. In addition, dinoflagellate sterol-based relationships were compared statistically to dinoflag...

  9. Integration of plastids with their hosts: Lessons learned from dinoflagellates

    PubMed Central

    Dorrell, Richard G.; Howe, Christopher J.

    2015-01-01

    After their endosymbiotic acquisition, plastids become intimately connected with the biology of their host. For example, genes essential for plastid function may be relocated from the genomes of plastids to the host nucleus, and pathways may evolve within the host to support the plastid. In this review, we consider the different degrees of integration observed in dinoflagellates and their associated plastids, which have been acquired through multiple different endosymbiotic events. Most dinoflagellate species possess plastids that contain the pigment peridinin and show extreme reduction and integration with the host biology. In some species, these plastids have been replaced through serial endosymbiosis with plastids derived from a different phylogenetic derivation, of which some have become intimately connected with the biology of the host whereas others have not. We discuss in particular the evolution of the fucoxanthin-containing dinoflagellates, which have adapted pathways retained from the ancestral peridinin plastid symbiosis for transcript processing in their current, serially acquired plastids. Finally, we consider why such a diversity of different degrees of integration between host and plastid is observed in different dinoflagellates and how dinoflagellates may thus inform our broader understanding of plastid evolution and function. PMID:25995366

  10. Integration of plastids with their hosts: Lessons learned from dinoflagellates.

    PubMed

    Dorrell, Richard G; Howe, Christopher J

    2015-08-18

    After their endosymbiotic acquisition, plastids become intimately connected with the biology of their host. For example, genes essential for plastid function may be relocated from the genomes of plastids to the host nucleus, and pathways may evolve within the host to support the plastid. In this review, we consider the different degrees of integration observed in dinoflagellates and their associated plastids, which have been acquired through multiple different endosymbiotic events. Most dinoflagellate species possess plastids that contain the pigment peridinin and show extreme reduction and integration with the host biology. In some species, these plastids have been replaced through serial endosymbiosis with plastids derived from a different phylogenetic derivation, of which some have become intimately connected with the biology of the host whereas others have not. We discuss in particular the evolution of the fucoxanthin-containing dinoflagellates, which have adapted pathways retained from the ancestral peridinin plastid symbiosis for transcript processing in their current, serially acquired plastids. Finally, we consider why such a diversity of different degrees of integration between host and plastid is observed in different dinoflagellates and how dinoflagellates may thus inform our broader understanding of plastid evolution and function. PMID:25995366

  11. A Lipidomic Approach to Understanding Free Fatty Acid Lipogenesis Derived from Dissolved Inorganic Carbon within Cnidarian-Dinoflagellate Symbiosis

    PubMed Central

    Dunn, Simon R.; Thomas, Michael C.; Nette, Geoffrey W.; Dove, Sophie G.

    2012-01-01

    The cnidarian-dinoflagellate symbiosis is arguably one of the most important within the marine environment in that it is integral to the formation of coral reefs. However, the regulatory processes that perpetuate this symbiosis remain unresolved. It is essential to understand these processes, if we are to elucidate the mechanisms that support growth and resource accumulation by coral host, and conversely, recently observed reduction and/or mortality of corals in response to rapid environmental change. This study specifically focused on one area of metabolic activity within the symbiosis, that of free fatty acid synthesis within both the dinoflagellate symbionts and cnidarian host. The main model system used was Aiptasia pulchella and Symbiodinium sp. in combination with aposymbiotic A. pulchella, the symbiotic coral Acropora millepora system and dinoflagellate culture. Fatty acids (FAs) were selected because of their multiple essential roles inclusive of energy storage (resource accumulation), membrane structure fluidity and cell signaling. The study addressed free FA lipogenesis by using a new method of enriched stable isotopic (13C) incorporation from dissolved inorganic carbon (DI13C) combined with HPLC-MS. FAs derived from DI13C aligned with a mixture of known lipogenesis pathways with the addition of some unusual FAs. After 120 hr, 13C-enriched FA synthesis rates were attributed to only a complex integration of both n–3 and n–6 lipogenesis pathways within the dinoflagellate symbionts. Furthermore, there was no detectible evidence of symbiont derived enriched isotope fatty acids, catabolized 13C derivatives or DI13C being directly utilized, in host late n–6 pathway long-chain FA lipogenesis. These findings do not align with a popular mutualistic translocation model with respect to the use of translocated symbiont photoassimilates in host long-chain FA lipogenesis, which has important connotations for linking nutrient sources with metabolite production and

  12. Peridinialean dinoflagellate plate patterns, labels and homologies

    USGS Publications Warehouse

    Edwards, L.E.

    1990-01-01

    Tabulation patterns for peridinialean dinoflagellate thecae and cysts have been traditionally expressed using a plate labelling system described by C.A. Kofoid in the early 1900's. This system can obscure dinoflagellate plate homologies and has not always been strictly applied. The plate-labelling system presented here introduces new series labels but incorporates key features and ideas from the more recently proposed systems of G.L. Eaton and F.J.R. Taylor, as modified by W.R. Evitt. Plate-series recognition begins with the cingulum (C-series) and proceeds from the cingulum toward the apex for the three series of the epitheca/epicyst and proceeds from the cingulum toward the antapex for the two series of the hypotheca/hypocyst. The epithecal/epicystal model consists of eight plates that touch the anterior margin of the cingulum (E-series: plates E1-E7, ES), seven plates toward the apex that touch the E-series plates (M-series: R, M1-M6), and up to seven plates near the apex that do not touch E-series plates (D-series: Dp-Dv). The hypothecal/hypocystal model consists of eight plates that touch the posterior margin of the cingulum (H-series: H1-H6,HR,HS) and three plates toward the antapex (T1-T3). Epithecal/epicystal tabulation patterns come in both 8- and 7- models, corresponding to eight and seven plates, respectively, in the E-series. Hypothecal/hypocystal tabulation patterns also come in both 8- and 7-models, corresponding to eight and seven plates, respectively, in the H-series. By convention, the 7-model epitheca/epicyst has no plates E1 and M1; the 7-model hypotheca/hypocyst has no plate H6. Within an 8-model or 7-model, the system emphasizes plates that are presumed to be homologous by giving them identical labels. I introduce the adjectives "monothigmate", "dithigmate," and "trithigmate" to designate plates touching one, two, and three plates, respectively, of the adjacent series. The term "thigmation" applies to the analysis of plate contacts between

  13. The Symbiodinium kawagutii genome illuminates dinoflagellate gene expression and coral symbiosis.

    PubMed

    Lin, Senjie; Cheng, Shifeng; Song, Bo; Zhong, Xiao; Lin, Xin; Li, Wujiao; Li, Ling; Zhang, Yaqun; Zhang, Huan; Ji, Zhiliang; Cai, Meichun; Zhuang, Yunyun; Shi, Xinguo; Lin, Lingxiao; Wang, Lu; Wang, Zhaobao; Liu, Xin; Yu, Sheng; Zeng, Peng; Hao, Han; Zou, Quan; Chen, Chengxuan; Li, Yanjun; Wang, Ying; Xu, Chunyan; Meng, Shanshan; Xu, Xun; Wang, Jun; Yang, Huanming; Campbell, David A; Sturm, Nancy R; Dagenais-Bellefeuille, Steve; Morse, David

    2015-11-01

    Dinoflagellates are important components of marine ecosystems and essential coral symbionts, yet little is known about their genomes. We report here on the analysis of a high-quality assembly from the 1180-megabase genome of Symbiodinium kawagutii. We annotated protein-coding genes and identified Symbiodinium-specific gene families. No whole-genome duplication was observed, but instead we found active (retro)transposition and gene family expansion, especially in processes important for successful symbiosis with corals. We also documented genes potentially governing sexual reproduction and cyst formation, novel promoter elements, and a microRNA system potentially regulating gene expression in both symbiont and coral. We found biochemical complementarity between genomes of S. kawagutii and the anthozoan Acropora, indicative of host-symbiont coevolution, providing a resource for studying the molecular basis and evolution of coral symbiosis. PMID:26542574

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

    PubMed

    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. PMID:19634014

  15. Feeding by heterotrophic dinoflagellates and ciliates on the free-living dinoflagellate Symbiodinium sp. (Clade E).

    PubMed

    Jeong, Hae Jin; Lim, An Suk; Yoo, Yeong Du; Lee, Moo Joon; Lee, Kyung Ha; Jang, Tae Young; Lee, Kitack

    2014-01-01

    To investigate heterotrophic protists grazing on Symbiodinium sp., we tested whether the common heterotrophic dinoflagellates Gyrodinium dominans, Gyrodinium moestrupii, Gyrodinium spirale, Oblea rotundata, Oxyrrhis marina, and Polykrikos kofoidii and the ciliates Balanion sp. and Parastrombidinopsis sp. preyed on the free-living dinoflagellate Symbiodinium sp. (clade E). We measured the growth and ingestion rates of O. marina and G. dominans on Symbiodinium sp. as a function of prey concentration. Furthermore, we compared the results to those obtained for other algal prey species. In addition, we measured the growth and ingestion rates of other predators at single prey concentrations at which these rates of O. marina and G. dominans were saturated. All predators tested in the present study, except Balanion sp., preyed on Symbiodinium sp. The specific growth rates of O. marina and G. dominans on Symbiodinium sp. increased rapidly with increasing mean prey concentration < ca. 740-815 ng C/ml (7,400-8,150 cells/ml), but became saturated at higher concentrations. The maximum growth rates of O. marina and G. dominans on Symbiodinium sp. (0.87 and 0.61/d) were much higher than those of G. moestrupii and P. kofoidii (0.11 and 0.04/d). Symbiodinium sp. did not support positive growth of G. spirale, O. rotundata, and Parastrombidinopsis sp. However, the maximum ingestion rates of P. kofoidii and Parastrombidinopsis sp. (6.7-10.0 ng C/predator/d) were much higher than those of O. marina and G. dominans on Symbiodinium sp. (1.9-2.1 ng C/predator/d). The results of the present study suggest that Symbiodinium sp. may increase or maintain the populations of some predators. PMID:24102740

  16. Two-dimensional electrophoresis analysis of proteins extracted from Alexandrium sp. LC3

    NASA Astrophysics Data System (ADS)

    Li, Hao; Miao, Jinlai; Cui, Fengxia; Li, Guangyou

    2007-10-01

    Two-dimensional electrophoresis(2-DE) of protein extracted and purified from Alexandrium sp. LC3 was conducted. In the SDS-PAGE study, the relative molecular weights of the proteins were mainly in the range of 14kDa-31kDa and 43kDa-66kDa, and more proteins were detected between 14kDa and 31kDa. With the improved protein preparation, the two-dimensional electrophoresis patterns indicated that the relative molecular weights of the proteins were between 14kDa and 100kDa, and most of them ranged from 14kDa to 31kDa. This was consistent with the result of the SDS-PAGE analysis. The isoelectric points were found to lie between 3.0 and 8.0, and most of them were in the range of 3.0 6.0. Better separation effect was acquired with pre-prepared immobilized gradient (IPG) strip (pH3 5.6), and about 320 protein spots could be visualized on the 2-DE map by staining. Within pH3 10 and pH3 5.6 strips, the protein samples of Alexandrium sp. LC3 could be separated well.

  17. Dinoflagellate cysts as indicators of palaeoenvironmental and sea-level change: the Late Cenomanian - Early Coniacian (Cretaceous) of Europe

    NASA Astrophysics Data System (ADS)

    Olde, Kate; Jarvis, Ian; Pearce, Martin; Tocher, Bruce

    2014-05-01

    The Late Cretaceous represented a period of greenhouse climate of Earth history, and was characterised by high temperatures, high atmospheric CO2 and high eustatic sea level, with large areas of shallow, warm, epicontinental sea. Understanding the dynamics of the Late Cretaceous climate is important for understanding the Earth System and the impact of modern climate change. The productive Late Cretaceous oceans led to the deposition of a large portion of the world's oil and gas resources, so reconstruction of depositional environments and refinement of stratigraphic correlation are important for the petroleum industry. Dinoflagellates were a prolific and diverse group within the phyto- and zooplankton throughout Late Cretaceous oceans, and their cysts display good preservation across different facies, and so are a good group for biostratigraphic and palaeoenvironmental study. Selected results from a high-resolution quantitative study of the palynology from 5 European Upper Cenomanian to the Lower Coniacian (Upper Cretaceous) sections are summarised, along with their carbon stable-isotope chemostratigraphy. The sections are from a range of palaeolatitudes and basins, including the North Sea Basin, the Anglo-Paris Basin, the Bohemian Basin, the Polish Trough and the Vocontian Basin. Palynological assemblages differ between sections in the concentration of palynomorphs, proportions of terrestrial and marine palynomorphs, and in the diversity and varying proportions of species of dinoflagellate cysts (dinocysts). Dinocyst distribution is considered to have been controlled largely by nutrient levels, but was also impacted by temperature, sea level, and water mass changes. Influxes of certain species are related to changes in salinity, changes in temperature, and water mass change, and increased communication between basins. High dinocyst abundance, and particularly a high proportion of peridinioid cysts (which are thought to be derived from eutrophy

  18. Spatial and temporal variability of Alexandrium cyst fluxes in the Gulf of Maine: Relationship to seasonal particle export and resuspension

    NASA Astrophysics Data System (ADS)

    Pilskaln, C. H.; Anderson, D. M.; McGillicuddy, D. J.; Keafer, B. A.; Hayashi, K.; Norton, K.

    2014-05-01

    Quantification of Alexandrium cyst fluxes through the Gulf of Maine water column is central to understanding the linkage between the source and fate of annual Alexandrium blooms in the offshore waters. These blooms often lead to paralytic shellfish poisoning (PSP) and extensive closures of shellfish beds. We report here on time-series sediment trap deployments completed at four offshore locations in the gulf between 2005 and 2010 as components of two ECOHAB-GOM field programs. Data presented documents the substantial spatial and temporal fluctuations in Alexandrium fundyense cyst fluxes in the gulf. Cyst delivery out of the euphotic zone peaked primarily between July and August following annual spring-summer Alexandrium blooms and was greatest in the western gulf. At all sites, cyst flux maxima to the subsurface waters were rarely coincident with seasonal peaks in the total mass export of particulate material indicating that cyst delivery was primarily via individually sinking cysts. Where persistent benthic nepheloid layers (BNLs) exist, significant sediment resuspension input of cysts to the near-bottom water column was evidenced by deep cyst fluxes that were up to several orders of magnitude greater than that measured above the BNL. The largest cyst fluxes in the BNL were observed in the eastern gulf, suggesting greater resuspension energy and BNL cyst inventories in this region. Temporal similarities between peak cyst export out of the upper ocean and peak cyst fluxes in the BNL were observed and document the contribution of seasonal, newly formed cysts to the BNL. The data however also suggest that many Alexandrium cells comprising the massive, short-lived blooms do not transition into cysts. Time-series flow measurements and a simple 1D model demonstrate that the BNL cyst fluxes reflect the combined effects of tidal energy-maintained resuspension, deposition, and input of cysts from the overlying water column.

  19. Spatial and temporal variability of Alexandrium cyst fluxes in the Gulf of Maine: Relationship to seasonal particle export and resuspension.

    PubMed

    Pilskaln, C H; Anderson, D M; McGillicuddy, D J; Keafer, B A; Hayashi, K; Norton, K

    2014-05-01

    Quantification of Alexandrium cyst fluxes through the Gulf of Maine water column is central to understanding the linkage between the source and fate of annual Alexandrium blooms in the offshore waters. These blooms often lead to paralytic shellfish poisoning (PSP) and extensive closures of shellfish beds. We report here on time-series sediment trap deployments completed at four offshore locations in the gulf between 2005 and 2010 as components of two ECOHAB-GOM field programs. Data presented documents the substantial spatial and temporal fluctuations in Alexandrium fundyense cyst fluxes in the gulf. Cyst delivery out of the euphotic zone peaked primarily between July and August following annual spring-summer Alexandrium blooms and was greatest in the western gulf. At all sites, cyst flux maxima to the subsurface waters were rarely coincident with seasonal peaks in the total mass export of particulate material indicating that cyst delivery was primarily via individually sinking cysts. Where persistent benthic nepheloid layers (BNLs) exist, significant sediment resuspension input of cysts to the near-bottom water column was evidenced by deep cyst fluxes that were up to several orders of magnitude greater than that measured above the BNL. The largest cyst fluxes in the BNL were observed in the eastern gulf, suggesting greater resuspension energy and BNL cyst inventories in this region. Temporal similarities between peak cyst export out of the upper ocean and peak cyst fluxes in the BNL were observed and document the contribution of seasonal, newly formed cysts to the BNL. The data however also suggest that many Alexandrium cells comprising the massive, short-lived blooms do not transition into cysts. Time-series flow measurements and a simple 1D model demonstrate that the BNL cyst fluxes reflect the combined effects of tidal energy-maintained resuspension, deposition, and input of cysts from the overlying water column. PMID:25431527

  20. Spatial and temporal variability of Alexandrium cyst fluxes in the Gulf of Maine: Relationship to seasonal particle export and resuspension

    PubMed Central

    Pilskaln, C.H.; Anderson, D.M.; McGillicuddy, D.J.; Keafer, B.A.; Hayashi, K.; Norton, K.

    2014-01-01

    Quantification of Alexandrium cyst fluxes through the Gulf of Maine water column is central to understanding the linkage between the source and fate of annual Alexandrium blooms in the offshore waters. These blooms often lead to paralytic shellfish poisoning (PSP) and extensive closures of shellfish beds. We report here on time-series sediment trap deployments completed at four offshore locations in the gulf between 2005 and 2010 as components of two ECOHAB–GOM field programs. Data presented documents the substantial spatial and temporal fluctuations in Alexandrium fundyense cyst fluxes in the gulf. Cyst delivery out of the euphotic zone peaked primarily between July and August following annual spring–summer Alexandrium blooms and was greatest in the western gulf. At all sites, cyst flux maxima to the subsurface waters were rarely coincident with seasonal peaks in the total mass export of particulate material indicating that cyst delivery was primarily via individually sinking cysts. Where persistent benthic nepheloid layers (BNLs) exist, significant sediment resuspension input of cysts to the near-bottom water column was evidenced by deep cyst fluxes that were up to several orders of magnitude greater than that measured above the BNL. The largest cyst fluxes in the BNL were observed in the eastern gulf, suggesting greater resuspension energy and BNL cyst inventories in this region. Temporal similarities between peak cyst export out of the upper ocean and peak cyst fluxes in the BNL were observed and document the contribution of seasonal, newly formed cysts to the BNL. The data however also suggest that many Alexandrium cells comprising the massive, short-lived blooms do not transition into cysts. Time-series flow measurements and a simple 1D model demonstrate that the BNL cyst fluxes reflect the combined effects of tidal energy-maintained resuspension, deposition, and input of cysts from the overlying water column. PMID:25431527

  1. An analysis of dinoflagellate metabolism using EST data.

    PubMed

    Butterfield, Erin R; Howe, Christopher J; Nisbet, R Ellen R

    2013-03-01

    The dinoflagellates are an important group of eukaryotic, single celled algae. They are the sister group of the Apicomplexa, a group of intracellular parasites and photosynthetic algae including the malaria parasite Plasmodium. Many apicomplexan mitochondria have a number of unusual features, including the lack of a pyruvate dehydrogenase and the existence of a branched TCA cycle. Here, we analyse dinoflagellate EST (expressed sequence tag) data to determine whether these features are apicomplexan-specific, or if they are more widespread. We show that dinoflagellates have replaced a key subunit (E1) of pyruvate dehydrogenase with a subunit of bacterial origin and that transcripts encoding many of the proteins that are essential in a conventional ATP synthase/Complex V are absent, as is the case in Apicomplexa. There is a pathway for synthesis of starch or glycogen as a storage carbohydrate. Transcripts encoding isocitrate lyase and malate synthase are present, consistent with ultrastructural reports of a glyoxysome. Finally, evidence for a conventional haem biosynthesis pathway is found, in contrast to the Apicomplexa, Chromera and early branching dinoflagellates (Perkinsus, Oxyrrhis). PMID:23085481

  2. Quaternary coastal evolution and vegetation history of northern New South Wales, Australia, based on dinoflagellates and pollen

    NASA Astrophysics Data System (ADS)

    McMinn, Andrew

    1992-11-01

    The Richmond River Valley of northern N.S.W. contains a late Pleistocene succession dating back to approximately 250,000 yr B.P. Dinoflagellate and spore-pollen assemblages from the lowest interval, the lower "Dungarubba Clay" of Drury (1982), indicate deposition in a restricted estuarine environment at approximately 250,000 yr. Deposition in the overlying interval, the upper "Dungarubba Clay" and "Gundurimba Clay", at approximately 120,000 yr B.P., began in a restricted estuary, but rising sea level caused inundation and deposition in a more open, marine-dominated environment. Dinoflagellate cyst assemblages from the last interglaciation (stage 5) are interpreted by analogy with those from the morphologically similar, modern Broken Bay, N.S.W. They are indicative of an open, marine-dominated environment and imply that barrier formation in the Richmond River Valley, and possibly elsewhere in northern N.S.W., did not commence until after the initial postglacial transgression. Synchronous changes in sea level and rainforest development suggest that there was no significant time lag between climate and sea-level change.

  3. Characterization of Two Dinoflagellate Cold Shock Domain Proteins

    PubMed Central

    Beauchemin, Mathieu; Roy, Sougata; Pelletier, Sarah; Averback, Alexandra; Lanthier, Frederic

    2016-01-01

    ABSTRACT Roughly two-thirds of the proteins annotated as transcription factors in dinoflagellate transcriptomes are cold shock domain-containing proteins (CSPs), an uncommon condition in eukaryotic organisms. However, no functional analysis has ever been reported for a dinoflagellate CSP, and so it is not known if they do in fact act as transcription factors. We describe here some of the properties of two CSPs from the dinoflagellate Lingulodinium polyedrum, LpCSP1 and LpCSP2, which contain a glycine-rich C-terminal domain and an N-terminal cold shock domain phylogenetically related to those in bacteria. However, neither of the two LpCSPs act like the bacterial CSP, since they do not functionally complement the Escherichia coli quadruple cold shock domain protein mutant BX04, and cold shock does not induce LpCSP1 and LpCSP2 to detectable levels, based on two-dimensional gel electrophoresis. Both CSPs bind to RNA and single-stranded DNA in a nonspecific manner in electrophoretic mobility shift assays, and both proteins also bind double-stranded DNA nonspecifically, albeit more weakly. These CSPs are thus unlikely to act alone as sequence-specific transcription factors. IMPORTANCE Dinoflagellate transcriptomes contain cold shock domain proteins as the major component of the proteins annotated as transcription factors. We show here that the major family of cold shock domain proteins in the dinoflagellate Lingulodinium do not bind specific sequences, suggesting that transcriptional control is not a predominant mechanism for regulating gene expression in this group of protists. PMID:27303711

  4. Betaines and dimethylsulfoniopropionate as major osmolytes in cnidaria with endosymbiotic dinoflagellates.

    PubMed

    Yancey, Paul H; Heppenstall, Marina; Ly, Steven; Andrell, Raymond M; Gates, Ruth D; Carter, Virginia L; Hagedorn, Mary

    2010-01-01

    Most marine invertebrates and algae are osmoconformers whose cells accumulate organic osmolytes that provide half or more of cellular osmotic pressure. These solutes are primarily free amino acids and glycine betaine in most invertebrates and small carbohydrates and dimethylsulfoniopropionate (DMSP) in many algae. Corals with endosymbiotic dinoflagellates (Symbiodinium spp.) have been reported to obtain from the symbionts potential organic osmolytes such as glycerol, amino acids, and DMSP. However, corals and their endosymbionts have not been fully analyzed for osmolytes. We quantified small carbohydrates, free amino acids, methylamines, and DMSP in tissues of the corals Fungia scutaria, Pocillopora damicornis, Pocillopora meandrina, Montipora capitata, Porites compressa, and Porites lobata (all with symbionts) plus Tubastrea aurea (asymbiotic) from Kaneohe Bay, Oahu (Hawaii). Glycine betaine, at 33-69 mmol/kg wet mass, was found to constitute 90% or more of the measured organic solutes in all except the Porites species. Those were dominated by proline betaine and dimethyltaurine. DMSP was found at 0.5-3 mmol/kg in all species with endosymbionts. Freshly isolated Symbiodinium from Fungia, P. damicornis, and P. compressa were also analyzed. DMSP and glycine betaine dominated in the first two; Porites endosymbionts had DMSP, proline betaine, and dimethyltaurine. In all specimens, glycerol and glucose were detected by high-performance liquid chromatography only at 0-1 mmol/kg wet mass. An enzymatic assay for glycerol plus glycerol 3-phosphate and dihydroxyacetone phosphate yielded 1-10 mmol/kg. Cassiopeia andromeda (upside-down jelly; Scyphozoan) and Aiptasia puchella (solitary anemone; Anthozoan) were also analyzed; both have endosymbiotic dinoflagellates. In both, glycine betaine, taurine, and DMSP were the dominant osmolytes. In summary, methylated osmolytes dominate in many Cnidaria; in those with algal symbionts, host and symbiont have similar methylated amino

  5. Identifying and Characterizing Alternative Molecular Markers for the Symbiotic and Free-Living Dinoflagellate Genus Symbiodinium

    PubMed Central

    Pochon, Xavier; Putnam, Hollie M.; Burki, Fabien; Gates, Ruth D.

    2012-01-01

    Dinoflagellates in the genus Symbiodinium are best known as endosymbionts of corals and other invertebrate as well as protist hosts, but also exist free-living in coastal environments. Despite their importance in marine ecosystems, less than 10 loci have been used to explore phylogenetic relationships in this group, and only the multi-copy nuclear ribosomal Internal Transcribed Spacer (ITS) regions 1 and 2 have been used to characterize fine-scale genetic diversity within the nine clades (A–I) that comprise the genus. Here, we describe a three-step molecular approach focused on 1) identifying new candidate genes for phylogenetic analysis of Symbiodinium spp., 2) characterizing the phylogenetic relationship of these candidate genes from DNA samples spanning eight Symbiodinium clades (A–H), and 3) conducting in-depth phylogenetic analyses of candidate genes displaying genetic divergences equal or higher than those within the ITS-2 of Symbiodinium clade C. To this end, we used bioinformatics tools and reciprocal comparisons to identify homologous genes from 55,551 cDNA sequences representing two Symbiodinium and six additional dinoflagellate EST libraries. Of the 84 candidate genes identified, 7 Symbiodinium genes (elf2, coI, coIII, cob, calmodulin, rad24, and actin) were characterized by sequencing 23 DNA samples spanning eight Symbiodinium clades (A–H). Four genes displaying higher rates of genetic divergences than ITS-2 within clade C were selected for in-depth phylogenetic analyses, which revealed that calmodulin has limited taxonomic utility but that coI, rad24, and actin behave predictably with respect to Symbiodinium lineage C and are potential candidates as new markers for this group. The approach for targeting candidate genes described here can serve as a model for future studies aimed at identifying and testing new phylogenetically informative genes for taxa where transcriptomic and genomics data are available. PMID:22238660

  6. Thiol- and biotin-labeled probes for oligonucleotide quartz crystal microbalance biosensors of microalga alexandrium minutum.

    PubMed

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  7. Thiol- and Biotin-Labeled Probes for Oligonucleotide Quartz Crystal Microbalance Biosensors of Microalga Alexandrium Minutum

    PubMed Central

    Lazerges, Mathieu; Perrot, Hubert; Rabehagasoa, Niriniony; Compère, Chantal

    2012-01-01

    Two quartz crystal microbalance oligonucleotide biosensors of a toxic microalga gene sequence (Alexandrium Minutum) have been designed. Grafting on a gold surface of 20-base thiol- or biotin-labeled probe, and selective hybridization with the complementary 20-base target, have been monitored in situ with a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the set up is stable to within a few hertz, corresponding to the nanogram scale, for three hour experiments. DNA recognition by the two biosensors is efficient and selective. Hybridization kinetic curves indicate that the biosensor designed with the thiol-labeled probe is more sensitive, and that the biosensor designed with the biotin-labeled probe has a shorter time response and a higher hybridization efficiency. PMID:25585927

  8. Early Genotoxic and Cytotoxic Effects of the Toxic Dinoflagellate Prorocentrum lima in the Mussel Mytilus galloprovincialis

    PubMed Central

    Prego-Faraldo, María Verónica; Valdiglesias, Vanessa; Laffon, Blanca; Mendez, Josefina; Eirin-Lopez, Jose M.

    2016-01-01

    Okadaic acid (OA) and dinophysistoxins (DTXs) are the main toxins responsible for diarrhetic shellfish poisoning (DSP) intoxications during harmful algal blooms (HABs). Although the genotoxic and cytotoxic responses to OA have been evaluated in vitro, the in vivo effects of these toxins have not yet been fully explored. The present work fills this gap by evaluating the in vivo effects of the exposure to the DSP-toxin-producing dinoflagellate Prorocentrum lima during the simulation of an early HAB episode in the mussel Mytilus galloprovincialis. The obtained results revealed that in vivo exposure to this toxic microalgae induced early genotoxicity in hemocytes, as a consequence of oxidative DNA damage. In addition, the DNA damage observed in gill cells seems to be mainly influenced by exposure time and P. lima concentration, similarly to the case of the oxidative damage found in hemocytes exposed in vitro to OA. In both cell types, the absence of DNA damage at low toxin concentrations is consistent with the notion suggesting that this level of toxicity does not disturb the antioxidant balance. Lastly, in vivo exposure to growing P. lima cell densities increased apoptosis but not necrosis, probably due to the presence of a high number of protein apoptosis inhibitors in molluscs. Overall, this work sheds light into the in vivo genotoxic and cytotoxic effects of P. lima. In doing so, it also demonstrates for the first time the potential of the modified (OGG1) comet assay for assessing oxidative DNA damage caused by marine toxins in marine invertebrates. PMID:27231936

  9. Early Genotoxic and Cytotoxic Effects of the Toxic Dinoflagellate Prorocentrum lima in the Mussel Mytilus galloprovincialis.

    PubMed

    Prego-Faraldo, María Verónica; Valdiglesias, Vanessa; Laffon, Blanca; Mendez, Josefina; Eirin-Lopez, Jose M

    2016-01-01

    Okadaic acid (OA) and dinophysistoxins (DTXs) are the main toxins responsible for diarrhetic shellfish poisoning (DSP) intoxications during harmful algal blooms (HABs). Although the genotoxic and cytotoxic responses to OA have been evaluated in vitro, the in vivo effects of these toxins have not yet been fully explored. The present work fills this gap by evaluating the in vivo effects of the exposure to the DSP-toxin-producing dinoflagellate Prorocentrum lima during the simulation of an early HAB episode in the mussel Mytilus galloprovincialis. The obtained results revealed that in vivo exposure to this toxic microalgae induced early genotoxicity in hemocytes, as a consequence of oxidative DNA damage. In addition, the DNA damage observed in gill cells seems to be mainly influenced by exposure time and P. lima concentration, similarly to the case of the oxidative damage found in hemocytes exposed in vitro to OA. In both cell types, the absence of DNA damage at low toxin concentrations is consistent with the notion suggesting that this level of toxicity does not disturb the antioxidant balance. Lastly, in vivo exposure to growing P. lima cell densities increased apoptosis but not necrosis, probably due to the presence of a high number of protein apoptosis inhibitors in molluscs. Overall, this work sheds light into the in vivo genotoxic and cytotoxic effects of P. lima. In doing so, it also demonstrates for the first time the potential of the modified (OGG1) comet assay for assessing oxidative DNA damage caused by marine toxins in marine invertebrates. PMID:27231936

  10. Warm mid-Cretaceous high-latitude sea-surface temperatures from the southern Tethys Ocean and cool high-latitude sea-surface temperatures from the Arctic Ocean: asymmetric worldwide distribution of dinoflagellates

    NASA Astrophysics Data System (ADS)

    Masure, Edwige; Desmares, Delphine; Vrielynck, Bruno

    2014-05-01

    constraints. In the Northern Hemisphere the oceanic heat transport was stopped by continental masses located between the Tethys, Central Atlantic and Arctic Oceans while the heat transport in the Southern Hemisphere was not limited in the Tethys Ocean. Late Albian Boreal dinoflagellates inhabited the Western Interior Sea Way, with the warming and the sea level rise Late Cenomanian Tethyan species have been recorded up to 45°N. The estimation of temperatures requirements of dinoflagellates is modelled by combining the latitudinal distribution of species, with the estimated temperatures from δ18O or TEX86 ratios related to latitude. The Early Aptian subtropical dinoflagellates inhabited water masses with temperatures higher than 22°C. Late Albian subtropical dinoflagellates lived in water masses with temperatures of 24°C and tropical species in those in temperature up to 28°C. The Late Albian arctic dinoflagellates lived in water masses with temperature lower than 19°C. Biogeography of planktonic micro-organisms coupled with temperatures estimated from δ18O or TEX86 ratios increases their potential as palaeo-oceanographic proxies for a qualitative estimation of sea-surface temperatures and palaeo-biodiversity of world water masses and improves precision in biochronology. Masure E, Vrielynck B. 2009. Late Albian dinoflagellate cyst paleobiogeography as indicator of asymmetric sea surface temperature gradient on both hemispheres with southern high latitudes warmer than northern ones. Marine Micropaleontology 70, 120-133. Masure E, Aumar A-M, Vrielynck B. 2013. World palaeogeography of Aptian and Late Albian dinoflagellates cysts: Implications for sea surface temperature gradient and palaeoclimate in Lewis, JM, Marret F, Bradley L (eds). Biological and Geological Perspectives of Dinoflagellates. The Micropalaeontological Society, Special Publications. Geological Society, London, 97-125.

  11. Oceanic heterotrophic dinoflagellates: distribution, abundance, and role as microzooplankton

    SciTech Connect

    Lessard, E.J.

    1984-01-01

    The primary objectives of this thesis were to determine the distribution and abundance of heterotrophic dinoflagellates across the Gulf Stream system off Cape Hatteras and to assess the potential grazing impact of these microheterotrophs in plankton communities. A list of species encountered in this study and their trophic status based on epifluorescence is presented, as well as observations on the presence of external or internal symbionts. The abundance of heterotrophic dinoflagellates across the Gulf Stream region off Cape Hatteras was determined from bimonthly net tow samples over a year and from whole water samples in March. Their average abundance was twice that of net ciliates in the net plankton and ten times that of ciliates in the nanoplankton. An isotope technique was developed to measure grazing rates of individual dinoflaggellates and other microzooplankton which cannot be separated in natural populations on the basis of size. /sup 3/H-thymidine and /sup 14/C-bicarbonate were used to label natural heterotrophic (bacteria and bacterivores) and autotrophic (phytoplankton and herbivores) food, respectively. Estimates of the grazing impact of heterotrophic kinoflagellates relative to other groups of heterotrophs on phytoplankton and bacteria were made by combining abundance data and clearance rates. Such calculations suggested that heterotrophic dinoflagellates may be an important group of grazers in oceanic waters.

  12. Dinoflagellates and ciliates at Helgoland Roads, North Sea

    NASA Astrophysics Data System (ADS)

    Löder, Martin Günther Joachim; Kraberg, Alexandra Claudia; Aberle, Nicole; Peters, Silvia; Wiltshire, Karen Helen

    2012-03-01

    A monitoring programme for microzooplankton was started at the long-term sampling station "Kabeltonne" at Helgoland Roads (54°11.3'N; 7°54.0'E) in January 2007 in order to provide more detailed knowledge on microzooplankton occurrence, composition and seasonality patterns at this site and to complement the existing plankton data series. Ciliate and dinoflagellate cell concentration and carbon biomass were recorded on a weekly basis. Heterotrophic dinoflagellates were considerably more important in terms of biomass than ciliates, especially during the summer months. However, in early spring, ciliates were the major group of microzooplankton grazers as they responded more quickly to phytoplankton food availability. Mixotrophic dinoflagellates played a secondary role in terms of biomass when compared to heterotrophic species; nevertheless, they made up an intense late summer bloom in 2007. The photosynthetic ciliate Myrionecta rubra bloomed at the end of the sampling period. Due to its high biomass when compared to crustacean plankton especially during the spring bloom, microzooplankton should be regarded as the more important phytoplankton grazer group at Helgoland Roads. Based on these results, analyses of biotic and abiotic factors driving microzooplankton composition and abundance are necessary for a full understanding of this important component of the plankton.

  13. Diverse Bacterial PKS Sequences Derived From Okadaic Acid-Producing Dinoflagellates

    PubMed Central

    Perez, Roberto; Liu, Li; Lopez, Jose; An, Tianying; Rein, Kathleen S.

    2008-01-01

    Okadaic acid (OA) and the related dinophysistoxins are isolated from dinoflagellates of the genus Prorocentrum and Dinophysis. Bacteria of the Roseobacter group have been associated with okadaic acid producing dinoflagellates and have been previously implicated in OA production. Analysis of 16S rRNA libraries reveals that Roseobacter are the most abundant bacteria associated with OA producing dinoflagellates of the genus Prorocentrum and are not found in association with non-toxic dinoflagellates. While some polyketide synthase (PKS) genes form a highly supported Prorocentrum clade, most appear to be bacterial, but unrelated to Roseobacter or Alpha-Proteobacterial PKSs or those derived from other Alveolates Karenia brevis or Crytosporidium parvum. PMID:18728765

  14. Proof that dinoflagellate spliced leader (DinoSL) is a useful hook for fishing dinoflagellate transcripts from mixed microbial samples: Symbiodinium kawagutii as a case study.

    PubMed

    Zhang, Huan; Zhuang, Yunyun; Gill, John; Lin, Senjie

    2013-07-01

    The ability to analyze dinoflagellate lineage-specific transcriptomes in the natural environment would be powerful for gaining understanding on how these organisms thrive in diverse environments and how they form harmful algal blooms and produce biotoxins. This can be made possible by lineage-specific mRNA markers such as the dinoflagellate-specific trans-spliced leader (DinoSL). By constructing and sequencing a 5'-cap selective full-length cDNA library for a monoculture of the coral reef endosymbiotic dinoflagellate Symbiodinium kawagutii and a DinoSL-based cDNA library for a mixture of S. kawagutii and other phytoplankton, we found DinoSL in essentially all full-length cDNAs in the 5'-cap selective library. We also discovered that the DinoSL-based library contained functionally diverse transcripts all belonging to dinoflagellates with no evidence of biases toward certain groups of functional genes. The results verified that DinoSL is specific to dinoflagellate mRNAs and is ubiquitous in the dinoflagellate transcriptomes. Annotation of the unigene dataset generated from the two libraries combined indicated high functional diversity of the transcriptome and revealed some biochemical pathways previously undocumented in Symbiodinium such as an mRNA splicing machinery potentially serving both cis- and trans-splicing. The protocol will be useful for transcriptomic studies of Symbiodinium in hospite and other dinoflagellates in natural environments. PMID:23773861

  15. Mixotrophy in the newly described phototrophic dinoflagellate Woloszynskia cincta from western Korean waters: feeding mechanism, prey species and effect of prey concentration.

    PubMed

    Kang, Nam Seon; Jeong, Hae Jin; Yoo, Yeong Du; Yoon, Eun Young; Lee, Kyung Ha; Lee, Kitack; Kim, Gwanghoon

    2011-01-01

    Woloszynskia species are dinoflagellates in the order Suessiales inhabiting marine or freshwater environments; their ecophysiology has not been well investigated, in particular, their trophic modes have yet to be elucidated. Previous studies have reported that all Woloszynskia species are photosynthetic, although their mixotrophic abilities have not been explored. We isolated a dinoflagellate from coastal waters in western Korea and established clonal cultures of this dinoflagellate. On the basis of morphology and analyses of the small/large subunit rRNA gene (GenBank accession number=FR690459), we identified this dinoflagellate as Woloszynskia cincta. We further established that this dinoflagellate is a mixotrophic species. We found that W. cincta fed on algal prey using a peduncle. Among the diverse prey provided, W. cincta ingested those algal species that had equivalent spherical diameters (ESDs) ≤12.6 μm, exceptions being the diatom Skeletonema costatum and the dinoflagellate Prorocentrum minimum. However, W. cincta did not feed on larger algal species that had ESDs≥15 μm. The specific growth rates for W. cincta increased continuously with increasing mean prey concentration before saturating at a concentration of ca. 134 ng C/ml (1,340 cells/ml) when Heterosigma akashiwo was used as food. The maximum specific growth rate (i.e. mixotrophic growth) of W. cincta feeding on H. akashiwo was 0.499 d(-1) at 20 °C under illumination of 20 μE/m(2) /s on a 14:10 h light-dark cycle, whereas its growth rate (i.e. phototrophic growth) under the same light conditions without added prey was 0.040 d(-1). The maximum ingestion and clearance rates of W. cincta feeding on H. akashiwo were 0.49 ng C/grazer/d (4.9 cells/grazer/d) and 1.9 μl/grazer/h, respectively. The calculated grazing coefficients for W. cincta on co-occurring H. akashiwo were up to 1.1 d(-1). The results of the present study suggest that grazing by W. cincta can have a potentially considerable impact

  16. Nutritional input from dinoflagellate symbionts in reef-building corals is minimal during planula larval life stage

    PubMed Central

    Kopp, Christophe; Domart-Coulon, Isabelle; Barthelemy, Dominique; Meibom, Anders

    2016-01-01

    Dispersion of larval offspring is of fundamental ecological importance to sessile marine organisms. Photosymbiotic planulae emitted by many reef-forming corals may travel over large distances before settling to form a new colony. It is not clear whether the metabolic requirements of these planula larvae are met exclusively with lipid and protein reservoirs inherited from the mother colony or when metabolic inputs from their endosymbiotic dinoflagellates become important. Pulse-chase experiments using [13C]bicarbonate and [15N]nitrate, combined with subcellular structural and isotopic imaging of freshly emitted symbiotic larvae from the coral Pocillopora damicornis, show that metabolic input from the dinoflagellates is minimal in the planulae compared with adult colonies. The larvae are essentially lecithotrophic upon emission, indicating that a marked shift in metabolic interaction between the symbiotic partners takes place later during ontogeny. Understanding the cellular processes that trigger and control this metabolic shift, and how climate change might influence it, is a key challenge in coral biology. PMID:27051861

  17. Nutritional input from dinoflagellate symbionts in reef-building corals is minimal during planula larval life stage.

    PubMed

    Kopp, Christophe; Domart-Coulon, Isabelle; Barthelemy, Dominique; Meibom, Anders

    2016-03-01

    Dispersion of larval offspring is of fundamental ecological importance to sessile marine organisms. Photosymbiotic planulae emitted by many reef-forming corals may travel over large distances before settling to form a new colony. It is not clear whether the metabolic requirements of these planula larvae are met exclusively with lipid and protein reservoirs inherited from the mother colony or when metabolic inputs from their endosymbiotic dinoflagellates become important. Pulse-chase experiments using [(13)C]bicarbonate and [(15)N]nitrate, combined with subcellular structural and isotopic imaging of freshly emitted symbiotic larvae from the coral Pocillopora damicornis, show that metabolic input from the dinoflagellates is minimal in the planulae compared with adult colonies. The larvae are essentially lecithotrophic upon emission, indicating that a marked shift in metabolic interaction between the symbiotic partners takes place later during ontogeny. Understanding the cellular processes that trigger and control this metabolic shift, and how climate change might influence it, is a key challenge in coral biology. PMID:27051861

  18. The Dinoflagellate Lingulodinium polyedrum Responds to N Depletion by a Polarized Deposition of Starch and Lipid Bodies

    PubMed Central

    Dagenais Bellefeuille, Steve; Dorion, Sonia; Rivoal, Jean; Morse, David

    2014-01-01

    Dinoflagellates are important contributors to the marine phytoplankton and global carbon fixation, but are also infamous for their ability to form the spectacular harmful algal blooms called red tides. While blooms are often associated with high available nitrogen, there are instances where they are observed in oligotrophic environments. In order to maintain their massive population in conditions of nitrogen limitation, dinoflagellates must have evolved efficient adaptive mechanisms. Here we report the physiological responses to nitrogen deprivation in Lingulodinium polyedrum. We find that this species reacts to nitrogen stress, as do most plants and microalgae, by stopping cell growth and diminishing levels of internal nitrogen, in particular in the form of protein and chlorophyll. Photosynthesis is maintained at high levels for roughly a week following nitrate depletion, resulting in accumulated photosynthetic products in the form of starch. During the second week, photosynthesis rates decrease due to a reduction in the number of chloroplasts and the accumulation of neutral lipid droplets. Surprisingly, the starch granules and lipid droplets are seen to accumulate at opposite poles of the cell. Lastly, we observe that cells acclimated to nitrogen-depleted conditions resume normal growth after addition of inorganic nitrogen, but are able to maintain high cell densities far longer than cells grown continuously in nitrogen-replete conditions. PMID:25368991

  19. Proteomic analysis provides new insights into the adaptive response of a dinoflagellate Prorocentrum donghaiense to changing ambient nitrogen.

    PubMed

    Zhang, Ying-Jiao; Zhang, Shu-Fei; He, Zhi-Ping; Lin, Lin; Wang, Da-Zhi

    2015-10-01

    Nitrogen (N) is the major nutrient limiting phytoplankton growth and productivity over large ocean areas. Dinoflagellates are important primary producers and major causative agents of harmful algal blooms in the ocean. However, very little is known about their adaptive response to changing ambient N. Here, we compared the protein profiles of a marine dinoflagellate Prorocentrum donghaiense grown in inorganic N-replete, N-deplete and N-resupplied conditions using 2-D fluorescence differential gel electrophoresis. The results showed that cell density, chlorophyll a and particulate organic N contents presented low levels in N-deplete cells, while particulate organic carbon content and glutamine synthetase (GS) activity maintained high levels. Comparison of the protein profiles of N-replete, N-deplete and N-resupplied cells indicated that proteins involved in photosynthesis, carbon fixation, protein and lipid synthesis were down-regulated, while proteins participating in N reallocation and transport activity were up-regulated in N-deplete cells. High expressions of GS and 60 kDa chaperonin as well as high GS activity in N-deplete cells indicated their central role in N stress adaptation. Overall, in contrast with other photosynthetic eukaryotic algae, P. donghaiense possessed a specific ability to regulate intracellular carbon and N metabolism in response to extreme ambient N deficiency. PMID:25789726

  20. The Mitochondrial Genome and Transcriptome of the Basal Dinoflagellate Hematodinium sp.: Character Evolution within the Highly Derived Mitochondrial Genomes of Dinoflagellates

    PubMed Central

    Gornik, S. G.; Waller, R. F.

    2012-01-01

    The sister phyla dinoflagellates and apicomplexans inherited a drastically reduced mitochondrial genome (mitochondrial DNA, mtDNA) containing only three protein-coding (cob, cox1, and cox3) genes and two ribosomal RNA (rRNA) genes. In apicomplexans, single copies of these genes are encoded on the smallest known mtDNA chromosome (6 kb). In dinoflagellates, however, the genome has undergone further substantial modifications, including massive genome amplification and recombination resulting in multiple copies of each gene and gene fragments linked in numerous combinations. Furthermore, protein-encoding genes have lost standard stop codons, trans-splicing of messenger RNAs (mRNAs) is required to generate complete cox3 transcripts, and extensive RNA editing recodes most genes. From taxa investigated to date, it is unclear when many of these unusual dinoflagellate mtDNA characters evolved. To address this question, we investigated the mitochondrial genome and transcriptome character states of the deep branching dinoflagellate Hematodinium sp. Genomic data show that like later-branching dinoflagellates Hematodinium sp. also contains an inflated, heavily recombined genome of multicopy genes and gene fragments. Although stop codons are also lacking for cox1 and cob, cox3 still encodes a conventional stop codon. Extensive editing of mRNAs also occurs in Hematodinium sp. The mtDNA of basal dinoflagellate Hematodinium sp. indicates that much of the mtDNA modification in dinoflagellates occurred early in this lineage, including genome amplification and recombination, and decreased use of standard stop codons. Trans-splicing, on the other hand, occurred after Hematodinium sp. diverged. Only RNA editing presents a nonlinear pattern of evolution in dinoflagellates as this process occurs in Hematodinium sp. but is absent in some later-branching taxa indicating that this process was either lost in some lineages or developed more than once during the evolution of the highly unusual

  1. A dinoflagellate Amylax triacantha with plastids of the cryptophyte origin: phylogeny, feeding mechanism, and growth and grazing responses.

    PubMed

    Park, Myung Gil; Kim, Miran; Kang, Misun

    2013-01-01

    The gonyaulacalean dinoflagellates Amylax spp. were recently found to contain plastids of the cryptophyte origin, more specifically of Teleaulax amphioxeia. However, not only how the dinoflagellates get the plastids of the cryptophyte origin is unknown but also their ecophysiology, including growth and feeding responses as functions of both light and prey concentration, remain unknown. Here, we report the establishment of Amylax triacantha in culture, its feeding mechanism, and its growth rate using the ciliate prey Mesodinium rubrum (= Myrionecta rubra) in light and dark, and growth and grazing responses to prey concentration and light intensity. The strain established in culture in this study was assigned to A. triacantha, based on morphological characteristics (particularly, a prominent apical horn and three antapical spines) and nuclear SSU and LSU rDNA sequences. Amylax triacantha grew well in laboratory culture when supplied with the marine mixotrophic ciliate M. rubrum as prey, reaching densities of over 7.5 × 10(3)  cells/ml. Amylax triacantha captured its prey using a tow filament, and then ingested the whole prey by direct engulfment through the sulcus. The dinoflagellate was able to grow heterotrophically in the dark, but the growth rate was approximately two times lower than in the light. Although mixotrophic growth rates of A. triacantha increased sharply with mean prey concentrations, with maximum growth rate being 0.68/d, phototrophic growth (i.e. growth in the absence of prey) was -0.08/d. The maximum ingestion rate was 2.54 ng C/Amylax/d (5.9 cells/Amylax/d). Growth rate also increased with increasing light intensity, but the effect was evident only when prey was supplied. Increased growth with increasing light intensity was accompanied by a corresponding increase in ingestion. In mixed cultures of two predators, A. triacantha and Dinophysis acuminata, with M. rubrum as prey, A. triacantha outgrew D. acuminata due to its approximately three

  2. A Game of Russian Roulette for a Generalist Dinoflagellate Parasitoid: Host Susceptibility Is the Key to Success

    PubMed Central

    Alacid, Elisabet; Park, Myung G.; Turon, Marta; Petrou, Katherina; Garcés, Esther

    2016-01-01

    Marine microbial interactions involving eukaryotes and their parasites play an important role in shaping the structure of phytoplankton communities. These interactions may alter population densities of the main host, which in turn may have consequences for the other concurrent species. The effect generalist parasitoids exert on a community is strongly dependent on the degree of host specificity. Parvilucifera sinerae is a generalist parasitoid able to infect a wide range of dinoflagellates, including toxic-bloom-forming species. A density-dependent chemical cue has been identified as the trigger for the activation of the infective stage. Together these traits make Parvilucifera-dinoflagellate hosts a good model to investigate the degree of specificity of a generalist parasitoid, and the potential effects that it could have at the community level. Here, we present for the first time, the strategy by which a generalist dinoflagellate parasitoid seeks out its host and determine whether it exhibits host preferences, highlighting key factors in determining infection. Our results demonstrate that in its infective stage, P. sinerae is able to sense potential hosts, but does not actively select among them. Instead, the parasitoids contact the host at random, governed by the encounter probability rate and once encountered, the chance to penetrate inside the host cell and develop the infection strongly depends on the degree of host susceptibility. As such, their strategy for persistence is more of a game of Russian roulette, where the chance of survival is dependent on the susceptibility of the host. Our study identifies P. sinerae as a potential key player in community ecology, where in mixed dinoflagellate communities consisting of hosts that are highly susceptible to infection, parasitoid preferences may mediate coexistence between host species, reducing the dominance of the superior competitor. Alternatively, it may increase competition, leading to species exclusion. If

  3. Cold-Induced Cysts of the Photosynthetic Dinoflagellate Lingulodinium polyedrum Have an Arrested Circadian Bioluminescence Rhythm and Lower Levels of Protein Phosphorylation1[C][W

    PubMed Central

    Roy, Sougata; Letourneau, Louis; Morse, David

    2014-01-01

    Dinoflagellates are microscopic, eukaryotic, and primarily marine plankton. Temporary cyst formation is a well-known physiological response of dinoflagellate cells to environmental stresses. However, the molecular underpinnings of cold-induced cyst physiology have never been described. Cultures of the photosynthetic dinoflagellate Lingulodinium polyedrum readily form temporary cysts when placed at low (8°C ± 1°C) temperature and excyst to form normal motile cells following a return to normal temperature (18°C ± 1°C). The normal circadian bioluminescence rhythm and the expected changes in Luciferin Binding Protein abundance were arrested in L. polyedrum cysts. Furthermore, after excystment, the bioluminescence rhythm initiates at a time corresponding to zeitgeber 12, independent of the time when the cells encysted. Phosphoprotein staining after two-dimensional polyacrylamide gel electrophoresis, as well as column-based phosphoprotein enrichment followed by liquid chromatography tandem mass spectrometry, showed cyst proteins are hypophosphorylated when compared with those from motile cells, with the most marked decreases found for predicted Casein Kinase2 target sites. In contrast to the phosphoproteome, the cyst proteome is not markedly different from motile cells, as assessed by two-dimensional polyacrylamide gel electrophoresis. In addition to changes in the phosphoproteome, RNA sequencing revealed that cysts show a significant decrease in the levels of 132 RNAs. Of the 42 RNAs that were identified by sequence analysis, 21 correspond to plastid-encoded gene products and 11 to nuclear-encoded cell wall/plasma membrane components. Our data are consistent with a model in which the highly reduced metabolism in cysts is achieved primarily by alterations in the phosphoproteome. The stalling of the circadian rhythm suggests temporary cysts may provide an interesting model to address the circadian system of dinoflagellates. PMID:24335505

  4. Peridinin-Chlorophyll a Proteins of the Dinoflagellate Amphidinium carterae (Plymouth 450) 1

    PubMed Central

    Haxo, Francis T.; Kycia, J. Helen; Somers, G. Fred; Bennett, Allen; Siegelman, Harold W.

    1976-01-01

    The marine dinoflagellate Amphidinium carterae (Plymouth 450) releases several water-soluble peridinin-chlorophyll a proteins after freezethawing. These chromoproteins have a molecular weight of 39.2 × 103 and are comprised of noncovalently bound peridinin and chlorophyll a and a nonoligomeric protein. They have distinct isoelectric points and may be resolved into six components by either isoelectric focusing on polyacrylamide gel or ion exchange chromatography. The predominant chromoprotein, which has a pI of 7.5, constitutes about 90% of the extractable peridinin-chlorophyll a protein. It consists of an alanine-rich apoprotein of molecular weight 31.8 × 103 stoichiometrically associated with 9 peridinin and 2 chlorophyll a molecules. Additionally, the peridinin-chlorophyll a proteins with pI values of 7.6 and 6.4 were purified and found to have amino acid and chromophore composition essentially identical with the pI 7.5 protein. Peridinin-chlorophyll a protein, pI 7.5, after treatment at alkaline pH was transformed into several more acid pI forms of the protein, strongly suggesting that the naturally occurring proteins are deamidation products of a single protein. Fluorescence excitation and emission spectra demonstrate that light energy absorbed by peridinin induces chlorophyll a fluorescence presumably by intramolecular energy transfer. The peridinin-chlorophyll a proteins presumably function in vivo as photosynthetic light-harvesting pigments. PMID:16659470

  5. Inactivation of dinoflagellate Scripsiella trochoidea in synthetic ballast water by advanced oxidation processes.

    PubMed

    Yang, Zhishan; Jiang, Wenju; Zhang, Yi; Lim, T M

    2015-01-01

    Ship-borne ballast water contributes significantly to the transfer of non-indigenous species across aquatic environments. To reduce the risk of bio-invasion, ballast water should be treated before discharge. In this study, the efficiencies of several conventional and advanced oxidation processes were investigated for potential ballast water treatment, using a marine dinoflagellate species, Scripsiella trochoidea, as the indicator organism. A stable and consistent culture was obtained and treated by ultraviolet (UV) light, ozone (O3), hydrogen peroxide (H2O2), and their various combinations. UV apparently inactivated the cells after only 10 s of irradiation, but subsequently photo-reactivation of the cells was observed for all methods involving UV. O3 exhibited 100% inactivation efficiency after 5 min treatment, while H2O2 only achieved maximum 80% inactivation in the same duration. Combined methods, e.g. UV/O3 and UV/H2O2, were found to inhibit photo-reactivation and improve treatment efficiency to some degree, indicating the effectiveness of using combined treatment processes. The total residual oxidant (TRO) levels of the methods were determined, and the results indicated that UV and O3 generated the lowest and highest TRO, respectively. The synergic effect of combined processes on TRO generation was found to be insignificant, and thus UV/O3 was recommended as a potentially suitable treatment process for ballast water. PMID:25182606

  6. Biotransformation and assimilation of dietary lipids by Calanus feeding on a dinoflagellate

    SciTech Connect

    Harvey, H.R.; Eglinton, G. ); O'Hara, S.C.M.; Corner, E.D.S. )

    1987-11-01

    Stage V and adult females of the marine copepod Calanus helgolandicus were fed in the laboratory on the dinoflagellate Scrippsiella trochoidea at three concentrations calculated to represent pelagic ocean to bloom conditions. The identification and quantification of sterols, fatty acids and alcohols present in the algal diet, copepods and their faecal pellets were then carried out using computerized gas chromatography-mass spectrometry (C-GC-MS). The results showed marked differences in the proportion of the three lipid classes removed, with highest values found for fatty acids and the lowest for sterols. Up to 97% of ingested algal fatty acids were removed by the copepod, with a preference towards the removal of polyunsaturated acids. Algal sterols were also removed by Calanus; the percentage composition and concentration of sterols in faecal pellets differing from the algal diet at all three food levels. Evidence that the removal of lipids from the diet represented assimilation by the copepods was provided by the further finding that during the feeding period (20 hr) all three lipid classes increased in animal tissues. Quantitative measurements of individual sterols revealed that significant amounts of 4-methyl and 4-desmethyl sterols having the 8(14) and 17(20) unsaturation were removed at all dietary levels. In contrast, ring-saturated stanols were not removed and appear to pass through the gut quantitatively.

  7. Symbiont type influences trophic plasticity of a model cnidarian-dinoflagellate symbiosis.

    PubMed

    Leal, Miguel C; Hoadley, Kenneth; Pettay, D Tye; Grajales, Alejandro; Calado, Ricardo; Warner, Mark E

    2015-03-01

    The association between cnidarians and photosynthetic dinoflagellates within the genus Symbiodinium is a prevalent relationship in tropical and subtropical marine environments. Although the diversity of Symbiodinium provides a possible axis for niche diversification, increased functional range and resilience to physical stressors such as elevated temperature, how such diversity relates to the physiological balance between autotrophy and heterotrophy of the host animal remains unknown. Here, we experimentally show interspecific and intraspecific variability of photosynthetic carbon fixation and subsequent translocation by Symbiodinium to the model cnidarian host Aiptasia pallida. By using a clonal anemone line harboring different species of Symbiodinium, we determined that symbiont identity influences trophic plasticity through its density, capacity to fix carbon, quantity of translocated carbon and ultimately the host's capacity to ingest and digest prey. Symbiont carbon translocation and host prey ingestion were positively correlated across symbiont combinations that consisted of different isoclonal lines of Symbiodinium minutum, while a combination with type D4-5 Symbiodinium displayed lower carbon translocation, and prey capture and digestion more similar to Aiptasia lacking symbionts. The absence of a shift toward greater heterotrophy when carbon translocation is low suggests that the metabolic demand of feeding and digestion may overwhelm nutritional stores when photosynthesis is reduced, and amends the possible role of animal feeding in resistance to or recovery from the effects of climate change in more obligate symbioses such as reef-building corals. PMID:25617454

  8. Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate

    PubMed Central

    Gornik, Sebastian G.; Febrimarsa; Cassin, Andrew M.; MacRae, James I.; Ramaprasad, Abhinay; Rchiad, Zineb; McConville, Malcolm J.; Bacic, Antony; McFadden, Geoffrey I.; Pain, Arnab; Waller, Ross F.

    2015-01-01

    Organelle gain through endosymbiosis has been integral to the origin and diversification of eukaryotes, and, once gained, plastids and mitochondria seem seldom lost. Indeed, discovery of nonphotosynthetic plastids in many eukaryotes—notably, the apicoplast in apicomplexan parasites such as the malaria pathogen Plasmodium—highlights the essential metabolic functions performed by plastids beyond photosynthesis. Once a cell becomes reliant on these ancillary functions, organelle dependence is apparently difficult to overcome. Previous examples of endosymbiotic organelle loss (either mitochondria or plastids), which have been invoked to explain the origin of eukaryotic diversity, have subsequently been recognized as organelle reduction to cryptic forms, such as mitosomes and apicoplasts. Integration of these ancient symbionts with their hosts has been too well developed to reverse. Here, we provide evidence that the dinoflagellate Hematodinium sp., a marine parasite of crustaceans, represents a rare case of endosymbiotic organelle loss by the elimination of the plastid. Extensive RNA and genomic sequencing data provide no evidence for a plastid organelle, but, rather, reveal a metabolic decoupling from known plastid functions that typically impede organelle loss. This independence has been achieved through retention of ancestral anabolic pathways, enzyme relocation from the plastid to the cytosol, and metabolic scavenging from the parasite’s host. Hematodinium sp. thus represents a further dimension of endosymbiosis—life after the organelle. PMID:25902514

  9. Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate.

    PubMed

    Gornik, Sebastian G; Febrimarsa; Cassin, Andrew M; MacRae, James I; Ramaprasad, Abhinay; Rchiad, Zineb; McConville, Malcolm J; Bacic, Antony; McFadden, Geoffrey I; Pain, Arnab; Waller, Ross F

    2015-05-01

    Organelle gain through endosymbiosis has been integral to the origin and diversification of eukaryotes, and, once gained, plastids and mitochondria seem seldom lost. Indeed, discovery of nonphotosynthetic plastids in many eukaryotes--notably, the apicoplast in apicomplexan parasites such as the malaria pathogen Plasmodium--highlights the essential metabolic functions performed by plastids beyond photosynthesis. Once a cell becomes reliant on these ancillary functions, organelle dependence is apparently difficult to overcome. Previous examples of endosymbiotic organelle loss (either mitochondria or plastids), which have been invoked to explain the origin of eukaryotic diversity, have subsequently been recognized as organelle reduction to cryptic forms, such as mitosomes and apicoplasts. Integration of these ancient symbionts with their hosts has been too well developed to reverse. Here, we provide evidence that the dinoflagellate Hematodinium sp., a marine parasite of crustaceans, represents a rare case of endosymbiotic organelle loss by the elimination of the plastid. Extensive RNA and genomic sequencing data provide no evidence for a plastid organelle, but, rather, reveal a metabolic decoupling from known plastid functions that typically impede organelle loss. This independence has been achieved through retention of ancestral anabolic pathways, enzyme relocation from the plastid to the cytosol, and metabolic scavenging from the parasite's host. Hematodinium sp. thus represents a further dimension of endosymbiosis--life after the organelle. PMID:25902514

  10. Genome size of Alexandrium catenella and Gracilariopsis lemaneiformis estimated by flow cytometry

    NASA Astrophysics Data System (ADS)

    Du, Qingwei; Sui, Zhenghong; Chang, Lianpeng; Wei, Huihui; Liu, Yuan; Mi, Ping; Shang, Erlei; Zeeshan, Niaz; Que, Zhou

    2016-08-01

    Flow cytometry (FCM) technique has been widely applied to estimating the genome size of various higher plants. However, there is few report about its application in algae. In this study, an optimized procedure of FCM was exploited to estimate the genome size of two eukaryotic algae. For analyzing Alexandrium catenella, an important red tide species, the whole cell instead of isolated nucleus was studied, and chicken erythrocytes were used as an internal reference. The genome size of A. catenella was estimated to be 56.48 ± 4.14 Gb (1C), approximately nineteen times larger than that of human genome. For analyzing Gracilariopsis lemaneiformis, an important economical red alga, the purified nucleus was employed, and Arabidopsis thaliana and Chondrus crispus were used as internal references, respectively. The genome size of Gp. lemaneiformis was 97.35 ± 2.58 Mb (1C) and 112.73 ± 14.00 Mb (1C), respectively, depending on the different internal references. The results of this research will promote the related studies on the genomics and evolution of these two species.

  11. Parallel Analyses of Alexandrium catenella Cell Concentrations and Shellfish Toxicity in the Puget Sound▿

    PubMed Central

    Dyhrman, Sonya T.; Haley, Sheean T.; Borchert, Jerry A.; Lona, Bob; Kollars, Nicole; Erdner, Deana L.

    2010-01-01

    Alexandrium catenella is widespread in western North America and produces a suite of potent neurotoxins that cause paralytic shellfish poisoning (PSP) in humans and have deleterious impacts on public health and economic resources. There are seasonal PSP-related closures of recreational and commercial shellfisheries in the Puget Sound, but the factors that influence cell distribution, abundance, and relationship to paralytic shellfish toxins (PSTs) in this system are poorly described. Here, a quantitative PCR assay was used to detect A. catenella cells in parallel with state shellfish toxicity testing during the 2006 bloom season at 41 sites from April through October. Over 500,000 A. catenella cells liter−1 were detected at several stations, with two main pulses of cells driving cell distribution, one in June and the other in August. PSTs over the closure limit of 80 μg of PST 100 per g of shellfish tissue were detected at 26 of the 41 sites. Comparison of cell numbers and PST data shows that shellfish toxicity is preceded by an increase in A. catenella cells in 71% of cases. However, cells were also observed in the absence of PSTs in shellfish, highlighting the complex relationship between A. catenella and the resulting shellfish toxicity. These data provide important information on the dynamics of A. catenella cells in the Puget Sound and are a first step toward assessing the utility of plankton monitoring to augment shellfish toxicity testing in this system. PMID:20495054

  12. Cytotoxicity, Fractionation and Dereplication of Extracts of the Dinoflagellate Vulcanodinium rugosum, a Producer of Pinnatoxin G

    PubMed Central

    Geiger, Marie; Desanglois, Gwenaëlle; Hogeveen, Kevin; Fessard, Valérie; Leprêtre, Thomas; Mondeguer, Florence; Guitton, Yann; Hervé, Fabienne; Séchet, Véronique; Grovel, Olivier; Pouchus, Yves-François; Hess, Philipp

    2013-01-01

    Pinnatoxin G (PnTX-G) is a marine toxin belonging to the class of cyclic imines and produced by the dinoflagellate Vulcanodinium rugosum. In spite of its strong toxicity to mice, leading to the classification of pinnatoxins into the class of “fast-acting toxins”, its hazard for human health has never been demonstrated. In this study, crude extracts of V. rugosum exhibited significant cytotoxicity against Neuro2A and KB cells. IC50 values of 0.38 µg mL−1 and 0.19 µg mL−1 were estimated on Neuro2A cells after only 24 h of incubation and on KB cells after 72 h of incubation, respectively. In the case of Caco-2 cells 48 h after exposure, the crude extract of V. rugosum induced cell cycle arrest accompanied by a dramatic increase in double strand DNA breaks, although only 40% cytotoxicity was observed at the highest concentration tested (5 µg mL−1). However, PnTX-G was not a potent cytotoxic compound as no reduction of the cell viability was observed on the different cell lines. Moreover, no effects on the cell cycle or DNA damage were observed following treatment of undifferentiated Caco-2 cells with PnTX-G. The crude extract of V. rugosum was thus partially purified using liquid-liquid partitioning and SPE clean-up. In vitro assays revealed strong activity of some fractions containing no PnTX-G. The crude extract and the most potent fraction were evaluated using full scan and tandem high resolution mass spectrometry. The dereplication revealed the presence of a major compound that could be putatively annotated as nakijiquinone A, N-carboxy-methyl-smenospongine or stachybotrin A, using the MarinLit™ database. Further investigations will be necessary to confirm the identity of the compounds responsible for the cytotoxicity and genotoxicity of the extracts of V. rugosum. PMID:24002102

  13. NanoSIMS study of trophic interactions in the coral-dinoflagellate endosymbiosis

    NASA Astrophysics Data System (ADS)

    Kopp, Christophe; Mathieu, Pernice; Domart-Coulon, Isabelle; Djediat, Chakib; Spangenberg, Jorge; Alexander, Duncan; Hignette, Michel; Meziane, Tarik; Meibom, Anders

    2013-04-01

    Tropical and subtropical reef-building corals generally form a stable endosymbiotic association with autotrophic single-celled dinoflagellate algae, commonly known as "zooxanthellae", which is crucial for the development of coral reef ecosystems. In the present work, the spatial and temporal dynamics of trophic interactions between corals and their dinoflagellates was investigated in situ and at a subcellular level in the reef-building coral Pocillopora damicornis. Transmission electron microscopy (TEM) and quantitative NanoSIMS isotopic imaging of tissue ultra-thin sections (70 nm) were combined to precisely track the assimilation and the fate of 15N-labeled compounds (ammonium, nitrate and aspartic acid) within each symbiotic partner of the coral-dinoflagellate association. Among our main results, we found that (i) both dinoflagellate algae and coral tissue rapidly assimilate ammonium and aspartic acid from the environment, (ii) however only the dinoflagellates assimilate nitrate, (ii) nitrogen is rapidly and temporary stored within the dinoflagellate cells into uric acid crystals, and (iii) the dinoflagellate endosymbionts translocate nitrogenous compounds to their coral host. This study paves the way for exploring in details the wide range of metabolic interactions between partners of any symbiosis in the biosphere.

  14. Eutrophication, marine biotoxins, human health.

    PubMed

    Viviani, R

    1992-01-01

    Eutrophication phenomena in marine coastal waters can today be explained on the basis of natural or anthropogenic causes. Undesirable effects and also sanitary problems in both types of eutrophication are often produced, but they may differ greatly in frequency and significance. Some algal biotoxins can affect both marine animals and man, whilst others affect man alone. From data currently available it appears that the sanitary state of man can be affected through the digestive, respiratory and cutaneous apparatus. Four main dinoflagellate biointoxications are now recognized: paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), diarrhoetic shellfish poisoning (DSP), and venerupin poisoning. Other biointoxications are due to a diatom bloom responsible for amnesic shellfish poisoning (ASP) and to blue algae blooms which have effects on the skin and the respiratory tract. All these marine toxins are considered and particular attention is paid to: producing organisms, chemistry of the components, compromised sea foods, methods of analysis, occurrence worldwide, human intoxications, toxicology and mechanism of action on a molecular level, therapeutical notes, tolerance levels and remarks on safety. Attention is also paid to the relationship between the anthropogenic eutrophication and PSP and DSP since these are the most widespread biointoxications from toxic marine dinoflagellates in the world today and for which the European Economic Community (EEC) is proposing health legislation such as tolerance limits and methods for official analysis. In view of the harmful potential of coastal anthropogenic eutrophication, the main current committment of various countries concerns control. Finally, it is important to develop a suitable monitor research system using all the specific standards of allowed toxic substances, and also research on effective antiodotes against all biotoxins. PMID:1475681

  15. Initial observations of the 2005 Alexandrium fundyense bloom in southern New England: General patterns and mechanisms

    NASA Astrophysics Data System (ADS)

    Anderson, Donald M.; Keafer, Bruce A.; McGillicuddy, Dennis J.; Mickelson, Michael J.; Keay, Kenneth E.; Scott Libby, P.; Manning, James P.; Mayo, Charles A.; Whittaker, David K.; Michael Hickey, J.; He, Ruoying; Lynch, Daniel R.; Smith, Keston W.

    2005-09-01

    From May to July, 2005, an extensive bloom of Alexandrium fundyense occurred along the coast of southern New England. The outbreak eventually closed shellfish beds from central Maine to Massachusetts, including Nantucket Island and portions of Martha's Vineyard, and resulted in the closure of 40,000 km 2 of offshore federal waters as well. The coastal Alexandrium bloom was exceptional in several ways: high toxin levels were measured farther south than ever before in New England; levels of toxicity in many locations were higher than previously observed at those stations; for the first time toxicity at some locations was above quarantine levels; cell concentrations far exceeded those observed in the coastal waters of southern New England in the past; and for the first time in the region the governors of Maine and Massachusetts officially declared the red tide to be a disaster, clearing the way for federal assistance. Initial observations suggest that several factors contributed to this bloom. Abundant rainfall and heavy snowmelt substantially increased the amount of fresh water entering the Gulf of Maine. Combined with other freshwater inputs, we hypothesize that this provided macro- and micro-nutrients, a stratified water column, and a transport mechanism that led to high cell abundances and broad, region-wide dispersal of the organism. Warm temperatures in western waters also would have favored A. fundyense growth. In addition, several storms with strong winds out of the northeast occurred at times when cells were abundant and in locations where the winds could advect them into Massachusetts and Cape Cod Bays and keep them there, leading to high cell concentrations and toxicity. Another contributing factor may have been the high abundance of newly deposited cysts in western Gulf of Maine sediments, as documented in a fall 2004 survey. Here, we evaluate this bloom and the patterns of toxicity in light of the conceptual models for A. fundyense dynamics developed

  16. Biogeochemical cycles during the species succession from Skeletonema costatum to Alexandrium tamarense in northern Hiroshima Bay

    NASA Astrophysics Data System (ADS)

    Yamamoto, Tamiji; Inokuchi, Yuko; Sugiyama, Teiji

    2004-12-01

    Temporal variations, budgets and cycling patterns of major biophilic elements [phosphorus (P), nitrogen (N) and silicon (Si)] in northern Hiroshima Bay during species succession from Skeletonema costatum to Alexandrium tamarense were documented using data collected on a weekly basis in 1996 and 1997. The budget calculations using a box model were made from the perspective of both particulate formation and decomposition of particulate matter. Thus, the overall circulation patterns of these three elements and their differences were examined in the present study. The turnover time of P was longer than that of N, indicating that the utilization efficiency of P by organisms is low. Along with this, absolute concentrations of dissolved inorganic phosphorus in this season and elemental ratios calculated from various forms of biophilic elements support the idea that DIP is too low for phytoplankton to utilize it. However, the utilization efficiency of P was higher in 1997 than in 1996, when A. tamarense formed a more intensive bloom, suggesting that these organisms could retain elements. When the bloom of A. tamarense formed in 1997, the residence time of water was extremely long, indicating that stagnation of water is a primary factor for bloom formation. In contrast to the large fluctuation in the residence time of water, residence times of biophilic elements were almost constant, indicating the importance of biological processes occurring in the system. On the other hand, in 1996, the residence times of biophilic elements were usually longer compared to that of water. This suggests that the particulate formation process by phytoplankton acts as a "nutrient trap" in combination with estuarine circulation.

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

    PubMed Central

    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

  18. Molecular Detection of Bioluminescent Dinoflagellates in Surface Waters of the Patagonian Shelf during Early Austral Summer 2008

    PubMed Central

    Valiadi, Martha; Painter, Stuart C.; Allen, John T.; Balch, William M.; Iglesias-Rodriguez, M. Debora

    2014-01-01

    We investigated the distribution of bioluminescent dinoflagellates in the Patagonian Shelf region using “universal” PCR primers for the dinoflagellate luciferase gene. Luciferase gene sequences and single cell PCR tests, in conjunction with taxonomic identification by microscopy, allowed us to identify and quantify bioluminescent dinoflagellates. We compared these data to coincidental discrete optical measurements of stimulable bioluminescence intensity. Molecular detection of the luciferase gene showed that bioluminescent dinoflagellates were widespread across the majority of the Patagonian Shelf region. Their presence was comparatively underestimated by optical bioluminescence measurements, whose magnitude was affected by interspecific differences in bioluminescence intensity and by the presence of other bioluminescent organisms. Molecular and microscopy data showed that the complex hydrography of the area played an important role in determining the distribution and composition of dinoflagellate populations. Dinoflagellates were absent south of the Falkland Islands where the cold, nutrient-rich, and well-mixed waters of the Falklands Current favoured diatoms instead. Diverse populations of dinoflagellates were present in the warmer, more stratified waters of the Patagonian Shelf and Falklands Current as it warmed northwards. Here, the dinoflagellate population composition could be related to distinct water masses. Our results provide new insight into the prevalence of bioluminescent dinoflagellates in Patagonian Shelf waters and demonstrate that a molecular approach to the detection of bioluminescent dinoflagellates in natural waters is a promising tool for ecological studies of these organisms. PMID:24918444

  19. Molecular detection of bioluminescent dinoflagellates in surface waters of the Patagonian shelf during early austral summer 2008.

    PubMed

    Valiadi, Martha; Painter, Stuart C; Allen, John T; Balch, William M; Iglesias-Rodriguez, M Debora

    2014-01-01

    We investigated the distribution of bioluminescent dinoflagellates in the Patagonian Shelf region using "universal" PCR primers for the dinoflagellate luciferase gene. Luciferase gene sequences and single cell PCR tests, in conjunction with taxonomic identification by microscopy, allowed us to identify and quantify bioluminescent dinoflagellates. We compared these data to coincidental discrete optical measurements of stimulable bioluminescence intensity. Molecular detection of the luciferase gene showed that bioluminescent dinoflagellates were widespread across the majority of the Patagonian Shelf region. Their presence was comparatively underestimated by optical bioluminescence measurements, whose magnitude was affected by interspecific differences in bioluminescence intensity and by the presence of other bioluminescent organisms. Molecular and microscopy data showed that the complex hydrography of the area played an important role in determining the distribution and composition of dinoflagellate populations. Dinoflagellates were absent south of the Falkland Islands where the cold, nutrient-rich, and well-mixed waters of the Falklands Current favoured diatoms instead. Diverse populations of dinoflagellates were present in the warmer, more stratified waters of the Patagonian Shelf and Falklands Current as it warmed northwards. Here, the dinoflagellate population composition could be related to distinct water masses. Our results provide new insight into the prevalence of bioluminescent dinoflagellates in Patagonian Shelf waters and demonstrate that a molecular approach to the detection of bioluminescent dinoflagellates in natural waters is a promising tool for ecological studies of these organisms. PMID:24918444

  20. Seasonality in the distribution of dinoflagellates with special reference to harmful algal species in tropical coastal environment, Bay of Bengal.

    PubMed

    Sahu, Gouri; Mohanty, A K; Samantara, M K; Satpathy, K K

    2014-10-01

    A study was carried out in the coastal waters of Kalpakkam, southeast coast of India, to find out the seasonal variation in dinoflagellate community structure. Samples were collected for a period of 4 years during 2006-2010. During the study 69 species of dinoflagellates were encountered among which Ceratium furca and Prorocentrum micans were most common during all the seasons. Genus Ceratium was found to be the most diverse one with 23 species which was followed by genus Protoperidinium with 16 species. Of 69 species, 27 species were considered as dominant based on their abundance during pre-monsoon (PRM), monsoon (MON) and post-monsoon (POM) periods. Relatively high density and diversity of dinoflagellates were encountered during the PRM period as compared to the MON and POM periods. Abundance pattern of dinoflagellates for three seasons showed the following trend: PRM > POM > MON. Salinity showed a positive correlation with dinoflagellate community showing its importance in dinoflagellate growth and sustenance. Ammonia and phosphate developed negative correlation with dinoflagellate density indicating the utilization of these nutrients by the dinoflagellate community. The presence of three dinoflagellate associations, broadly representing the three seasons experienced at this location, was evident from the cluster analysis. The study revealed presence of 19 relatively abundant toxic/red tide forming dinoflagellate species in the coastal waters of Kalpakkam. PMID:25012144

  1. Isolation and characterization of pigmented algicidal bacteria from seawater

    NASA Astrophysics Data System (ADS)

    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.

  2. MECHANISMS OF FLUID SHEAR-INDUCED INHIBITION OF POPULATION GROWTH IN A RED-TIDE DINOFLAGELLATE

    EPA Science Inventory

    Net population growth of some dinoflagellates is inhibited by fluid shear at shear stresses comparable with those generated during oceanic turbulence. Decreased net growth may occur through lowered cell division, increased mortality, or both. The dominant mechanism under various ...

  3. Simulation and analysis of a model dinoflagellate predator-prey system

    NASA Astrophysics Data System (ADS)

    Mazzoleni, M. J.; Antonelli, T.; Coyne, K. J.; Rossi, L. F.

    2015-12-01

    This paper analyzes the dynamics of a model dinoflagellate predator-prey system and uses simulations to validate theoretical and experimental studies. A simple model for predator-prey interactions is derived by drawing upon analogies from chemical kinetics. This model is then modified to account for inefficiencies in predation. Simulation results are shown to closely match the model predictions. Additional simulations are then run which are based on experimental observations of predatory dinoflagellate behavior, and this study specifically investigates how the predatory dinoflagellate Karlodinium veneficum uses toxins to immobilize its prey and increase its feeding rate. These simulations account for complex dynamics that were not included in the basic models, and the results from these computational simulations closely match the experimentally observed predatory behavior of K. veneficum and reinforce the notion that predatory dinoflagellates utilize toxins to increase their feeding rate.

  4. Dinoflagellate 17S rRNA sequence inferred from the gene sequence: Evolutionary implications.

    PubMed

    Herzog, M; Maroteaux, L

    1986-11-01

    We present the complete sequence of the nuclear-encoded small-ribosomal-subunit RNA inferred from the cloned gene sequence of the dinoflagellate Prorocentrum micans. The dinoflagellate 17S rRNA sequence of 1798 nucleotides is contained in a family of 200 tandemly repeated genes per haploid genome. A tentative model of the secondary structure of P. micans 17S rRNA is presented. This sequence is compared with the small-ribosomal-subunit rRNA of Xenopus laevis (Animalia), Saccharomyces cerevisiae (Fungi), Zea mays (Planta), Dictyostelium discoideum (Protoctista), and Halobacterium volcanii (Monera). Although the secondary structure of the dinoflagellate 17S rRNA presents most of the eukaryotic characteristics, it contains sufficient archaeobacterial-like structural features to reinforce the view that dinoflagellates branch off very early from the eukaryotic lineage. PMID:16578795

  5. Dinoflagellate 17S rRNA sequence inferred from the gene sequence: Evolutionary implications

    PubMed Central

    Herzog, Michel; Maroteaux, Luc

    1986-01-01

    We present the complete sequence of the nuclear-encoded small-ribosomal-subunit RNA inferred from the cloned gene sequence of the dinoflagellate Prorocentrum micans. The dinoflagellate 17S rRNA sequence of 1798 nucleotides is contained in a family of 200 tandemly repeated genes per haploid genome. A tentative model of the secondary structure of P. micans 17S rRNA is presented. This sequence is compared with the small-ribosomal-subunit rRNA of Xenopus laevis (Animalia), Saccharomyces cerevisiae (Fungi), Zea mays (Planta), Dictyostelium discoideum (Protoctista), and Halobacterium volcanii (Monera). Although the secondary structure of the dinoflagellate 17S rRNA presents most of the eukaryotic characteristics, it contains sufficient archaeobacterial-like structural features to reinforce the view that dinoflagellates branch off very early from the eukaryotic lineage. PMID:16578795

  6. The Large Mitochondrial Genome of Symbiodinium minutum Reveals Conserved Noncoding Sequences between Dinoflagellates and Apicomplexans

    PubMed Central

    Shoguchi, Eiichi; Shinzato, Chuya; Hisata, Kanako; Satoh, Nori; Mungpakdee, Sutada

    2015-01-01

    Even though mitochondrial genomes, which characterize eukaryotic cells, were first discovered more than 50 years ago, mitochondrial genomics remains an important topic in molecular biology and genome sciences. The Phylum Alveolata comprises three major groups (ciliates, apicomplexans, and dinoflagellates), the mitochondrial genomes of which have diverged widely. Even though the gene content of dinoflagellate mitochondrial genomes is reportedly comparable to that of apicomplexans, the highly fragmented and rearranged genome structures of dinoflagellates have frustrated whole genomic analysis. Consequently, noncoding sequences and gene arrangements of dinoflagellate mitochondrial genomes have not been well characterized. Here we report that the continuous assembled genome (∼326 kb) of the dinoflagellate, Symbiodinium minutum, is AT-rich (∼64.3%) and that it contains three protein-coding genes. Based upon in silico analysis, the remaining 99% of the genome comprises transcriptomic noncoding sequences. RNA edited sites and unique, possible start and stop codons clarify conserved regions among dinoflagellates. Our massive transcriptome analysis shows that almost all regions of the genome are transcribed, including 27 possible fragmented ribosomal RNA genes and 12 uncharacterized small RNAs that are similar to mitochondrial RNA genes of the malarial parasite, Plasmodium falciparum. Gene map comparisons show that gene order is only slightly conserved between S. minutum and P. falciparum. However, small RNAs and intergenic sequences share sequence similarities with P. falciparum, suggesting that the function of noncoding sequences has been preserved despite development of very different genome structures. PMID:26199191

  7. The Large Mitochondrial Genome of Symbiodinium minutum Reveals Conserved Noncoding Sequences between Dinoflagellates and Apicomplexans.

    PubMed

    Shoguchi, Eiichi; Shinzato, Chuya; Hisata, Kanako; Satoh, Nori; Mungpakdee, Sutada

    2015-08-01

    Even though mitochondrial genomes, which characterize eukaryotic cells, were first discovered more than 50 years ago, mitochondrial genomics remains an important topic in molecular biology and genome sciences. The Phylum Alveolata comprises three major groups (ciliates, apicomplexans, and dinoflagellates), the mitochondrial genomes of which have diverged widely. Even though the gene content of dinoflagellate mitochondrial genomes is reportedly comparable to that of apicomplexans, the highly fragmented and rearranged genome structures of dinoflagellates have frustrated whole genomic analysis. Consequently, noncoding sequences and gene arrangements of dinoflagellate mitochondrial genomes have not been well characterized. Here we report that the continuous assembled genome (∼326 kb) of the dinoflagellate, Symbiodinium minutum, is AT-rich (∼64.3%) and that it contains three protein-coding genes. Based upon in silico analysis, the remaining 99% of the genome comprises transcriptomic noncoding sequences. RNA edited sites and unique, possible start and stop codons clarify conserved regions among dinoflagellates. Our massive transcriptome analysis shows that almost all regions of the genome are transcribed, including 27 possible fragmented ribosomal RNA genes and 12 uncharacterized small RNAs that are similar to mitochondrial RNA genes of the malarial parasite, Plasmodium falciparum. Gene map comparisons show that gene order is only slightly conserved between S. minutum and P. falciparum. However, small RNAs and intergenic sequences share sequence similarities with P. falciparum, suggesting that the function of noncoding sequences has been preserved despite development of very different genome structures. PMID:26199191

  8. Complex response of dinoflagellate distribution patterns to cooler early Oligocene global oceans

    NASA Astrophysics Data System (ADS)

    Woods, Mark; Vandenbroucke, Thijs; Williams, Mark; Riding, James; De Schepper, Stijn; Sabbe, Koen

    2013-04-01

    Analysis of dinoflagellate cysts using two new global ocean datasets for the Mid Eocene (Bartonian) and Early Oligocene (Rupelian) reveals unexpected changes in their global distribution. The impact of Rupelian cooling appears to be globally asymmetric; the dinoflagellate cyst cooling signal is clearer in the southern hemisphere, but much less evident in the northern hemisphere. Additionally, a significant number of species with low and mid-latitude northern hemisphere occurrences in the Bartonian, unexpectedly extend their northward ranges in the Rupelian, including some 'warm water' forms. This may show that Rupelian dinoflagellate cyst distribution is a response to changes in a range of environmental variables linked to climate-cooling, for example changes in nutrient fluxes triggered by glacially-induced base-level fall, or complex reorganisation of ocean current systems between the Bartonian and Rupelian. Apparent lack of a clear climate-cooling signal in Rupelian dinoflagellate cyst distribution may in part reflect published evidence suggesting that summer SSTs in the early Rupelian northern hemisphere were only slightly reduced compared to the later part of the Eocene, despite much colder winters. The relatively broad temperature tolerance of many extant dinoflagellate species, and dormant cyst formation during short-lived environmental deterioration, may have contributed to allowing Rupelian dinoflagellates to thrive in more highly seasonal but otherwise hospitable, northern hemisphere oceans.

  9. Signal recognition particle RNA in dinoflagellates and the Perkinsid Perkinsus marinus.

    PubMed

    Zhang, Huan; Campbell, David A; Sturm, Nancy R; Rosenblad, Magnus A; Dungan, Christopher F; Lin, Senjie

    2013-09-01

    In dinoflagellates and perkinsids, the molecular structure of the protein translocating machinery is unclear. Here, we identified several types of full-length signal recognition particle (SRP) RNA genes from Karenia brevis (dinoflagellate) and Perkinsus marinus (perkinsid). We also identified the four SRP S-domain proteins, but not the two Alu domain proteins, from P. marinus and several dinoflagellates. We mapped both ends of SRP RNA transcripts from K. brevis and P. marinus, and obtained the 3' end from four other dinoflagellates. The lengths of SRP RNA are predicted to be ∼260-300 nt in dinoflagellates and 280-285 nt in P. marinus. Although these SRP RNA sequences are substantially variable, the predicted structures are similar. The genomic organization of the SRP RNA gene differs among species. In K. brevis, this gene is located downstream of the spliced leader (SL) RNA, either as SL RNA-SRP RNA-tRNA gene tandem repeats, or within a SL RNA-SRP RNA-tRNA-U6-5S rRNA gene cluster. In other dinoflagellates, SRP RNA does not cluster with SL RNA or 5S rRNA genes. The majority of P. marinus SRP RNA genes array as tandem repeats without the above-mentioned small RNA genes. Our results capture a snapshot of a potentially complex evolutionary history of SRP RNA in alveolates. PMID:23994724

  10. The distribution of intra-genomically variable dinoflagellate symbionts at Lord Howe Island, Australia

    NASA Astrophysics Data System (ADS)

    Wilkinson, Shaun P.; Pontasch, Stefanie; Fisher, Paul L.; Davy, Simon K.

    2016-06-01

    The symbiotic dinoflagellates of corals and other marine invertebrates ( Symbiodinium) are essential to the development of shallow-water coral reefs. This genus contains considerable genetic diversity and a corresponding range of physiological and ecological traits. Most genetic variation arises through the accumulation of somatic mutations that arise during asexual reproduction. Yet growing evidence suggests that occasional sexual reproductive events also occur within, and perhaps between, Symbiodinium lineages, further contributing to the pool of genetic variation available for evolutionary adaptation. Intra-genomic variation can therefore arise from both sexual and asexual reproductive processes, making it difficult to discern its underlying causes and consequences. We used quantitative PCR targeting the ITS2 locus to estimate proportions of genetically homogeneous symbionts and intra-genomically variable Symbiodinium (IGV Symbiodinium) in the reef-building coral Pocillopora damicornis at Lord Howe Island, Australia. We then sampled colonies through time and at a variety of spatial scales to find out whether the distribution of these symbionts followed patterns consistent with niche partitioning. Estimated ratios of homogeneous to IGV Symbiodinium varied between colonies within sites (metres to tens of metres) and between sites separated by hundreds to thousands of metres, but remained stable within colonies through time. Symbiont ratios followed a temperature gradient, with the local thermal maximum emerging as a negative predictor for the estimated proportional abundance of IGV Symbiodinium. While this pattern may result from fine-scale spatial population structure, it is consistent with an increased susceptibility to thermal stress, suggesting that the evolutionary processes that generate IGV (such as inter-lineage recombination and the accumulation of somatic mutations at the ITS2 locus) may have important implications for the fitness of the symbiont and

  11. Biotransformation and assimilation of dietary lipids by Calanus feeding on a dinoflagellate

    NASA Astrophysics Data System (ADS)

    Harvey, H. Rodger; Eglinton, Geoffrey; O'Hara, Sean C. M.; Corner, Eric D. S.

    1987-11-01

    Stage V and adult females of the marine copepod Calanus helgolandicus were fed in the laboratory on the dinoflagellate Scrippsiella trochoidea at three concentrations calculated to represent pelagic ocean to 'bloom' conditions. The identification and quantification of sterols, fatty acids and alcohols present in the algal diet, copepods and their faecal pellets were then carried out using computerized gas chromatography- mass spectrometry (C-GC-MS). The grazing rates of animals were measured and the data then combined with those of lipid distributions in the diet and faecal pellets in order to determine quantitatively the fate of each lipid during its passage through the gut of Calanus. The results showed marked differences in the proportion of the three lipid classes removed, with highest values found for fatty acids and the lowest for sterols. Up to 97% of ingested algal fatty acids were removed by the copepod, with a preference towards the removal of polyunsaturated acids. Algal sterols were also removed by Calanus; the percentage composition and concentration of sterols in faecal pellets differing from the algal diet at all three food levels. Evidence that the removal of lipids from the diet represented assimilation by the copepods was provided by the further finding that during the feeding period (20 hr) all three lipid classes increased in animal tissues. Quantitative measurements of individual sterols revealed that significant amounts of 4-methyl and 4-desmethyl sterols having the 8(14) and 17(20) unsaturation were removed at all dietary levels. In contrast, ring-saturated stanols were not removed and appear to pass through the gut quantitatively.

  12. Dinoflagellate cysts and benthic foraminifera in surface sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

    NASA Astrophysics Data System (ADS)

    Ferraro, L.; Rubino, F.; Frontalini, F.; Belmonte, M.; Di Leo, A.; Giandomenico, S.; Greco, M.; Lirer, F.; Spada, L.; Vallefuoco, M.

    2012-12-01

    Coastal areas have traditionally been places of human settlement, with the increasing development of cities, industries and other human-related activities possibly having an impact on the aquatic ecosystem. These impacts may take the form of pollution from industrial, domestic, agricultural or mining activities. For this reason, attention to marine environmental problems has recently increased and the search for new methodologies and techniques for the monitoring of coastal-marine areas become more and more active and accurate. In this context biological indicators result a useful tool to provide indication of environmental conditions including the presence or absence of contaminants; in fact biological monitoring is more directly related to the ecological health of an ecosystem than are chemical data. The increasing importance of bioindicators is also encouraged within the European Union's Water Framework Directive (WFD), which aims to achieve a good ecological status in all European water bodies (i.e., rivers, lakes and coastal waters). Among the wide range of bioindicators, 5 biological elements are listed within the WFD: phytoplankton, macroalgae, angiosperms, benthic invertebrates and fishes. Benthic invertebrates as foraminifera represent a group of protozoa widely distributed in all brackish and marine environments which are used in studies assessing the environmental quality of areas subject to intense human activity. Moreover in coastal marine environments benthic and pelagic domain present several relationships, one of these is represented by the life cycles of phytoplankton species, as Dinoflagellates, which include the production of benthic stages (cysts). These dormant stages, which accumulate in confined marine muddy areas, such as ports, lagoons or estuaries, can reach high densities, similar to the seed banks of terrestrial plants. The cysts have a high preservation potential and can rest in/on the sediments for decades. Due to this peculiar

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

    NASA Astrophysics Data System (ADS)

    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

  14. Toxin variability in cultured and natural populations of Alexandrium tamarense from southern South America - Evidences of diversity and environmental regulation.

    PubMed

    Montoya, Nora G; Fulco, Vanesa K; Carignan, Mario O; Carreto, José I

    2010-12-01

    Cell content and composition of paralytic shellfish toxins of 10 cultured strains and 6 natural populations of Alexandrium tamarense from the Argentine sea, were analyzed. These data were compiled with previously published data into a comprehensive view of the toxin composition of the complex A. tamarense/Alexandrium catenella from southern South America. The N-sulfocarbamoyl derivatives C1,2 were predominant in almost all the cultured strains. The second major derivatives were GTX1,4, although the GTX1,4/C1,2 ratio varied largely. Some strains contain relatively high amounts of GTX2,3 (up to 29%) and/or neoSTX (up to 24%). In all strains STX was a minor component (0-4.4%) whereas GTX5 was present only in Alexandrium catenella isolates. Similarity analysis based upon toxin profiles showed that cultured strains from Argentine, Brazil, Chile and Uruguay clustered together. However, whereas some strains from the same geographic area exhibited different toxin profiles, and consistently fell out in separate subgroups, strains from Chile are grouped in a unique subgroup. In contrast to cultured strains, C1,2 were minor components among field populations. The highly toxic GTX1,4 were predominant in all spring field populations (69.1-93.6%). Moreover, their toxin cell content (163.9-261.4 fmol cell(-1)) and toxicity (68.2-93.0 pg STX equiv. cell(-1)) were several times higher that showed by the cultured strains. Field populations are more closely related to one another than to the cultured strains. However a less toxic and morphologically distinctive autumn population, contained GTX2,3 as the quasi unique (88.5%) toxin derivative clustered separately. Variability in toxin content and composition of A. tamarense field populations were well correlated with in situ temperature and nitrate concentration. Whereas toxin cell content and GTX1,4 (mol %) increased following saturation functions, GTX2,3 (mol %) decrease exponentially with the increase of the in situ nitrate

  15. A new approach to discriminate dinoflagellate from diatom blooms from space in the East China Sea

    NASA Astrophysics Data System (ADS)

    Shang, Shaoling; Wu, Jingyu; Huang, Bangqin; Lin, Gong; Lee, Zhongping; Liu, James; Shang, Shaoping

    2014-07-01

    Dinoflagellate and diatom blooms often occur in the East China Sea (ECS) during spring and summer. Some of the dinoflagellate blooms are toxic, resulting in widespread economic damage. In order to mitigate the negative impacts, remote-sensing methods that can effectively and accurately discriminate between bloom types are demanded for early warning and continuous monitoring of bloom events at large scales. An in situ bio-optical data set collected from diatom and dinoflagellate blooming waters indicates that the two types of blooms exhibited distinctive differences in the shapes and magnitudes of remote-sensing reflectance (Rrs). The ratio of in situ measured Rrs spectral slopes at two spectral ranges (443-488 and 531-555 nm, bands available with the moderate resolution imaging spectrometer (MODIS) sensor), abbreviated as BI (representing bloom index), was found effective in differentiating dinoflagellates from diatoms. Reflectance model simulations, which were carried out using in situ and algal culture data as input, provided consistent results. A classification approach for separating dinoflagellate from diatom blooms in the ECS was then developed: When fluorescence line height (FLH) is doubled over the background level and total absorption coefficient at 443 nm ≥ 0.5 m-1, if 0.0 < BI ≤ 0.3, it suggests a dinoflagellate bloom; if 0.3 < BI ≤ 1.0, it suggests a diatom bloom. Finally, the approach was applied to MODIS measurements over the ECS, and a series of diatom and dinoflagellate bloom events during April-June 2005 and 2011 were successfully identified, suggesting that the proposed approach is generally valid for the ECS.

  16. Lipid biomarkers in Symbiodinium dinoflagellates: new indicators of thermal stress

    NASA Astrophysics Data System (ADS)

    Kneeland, J.; Hughen, K.; Cervino, J.; Hauff, B.; Eglinton, T.

    2013-12-01

    Lipid content and fatty acid profiles of corals and their dinoflagellate endosymbionts are known to vary in response to high-temperature stress. To better understand the heat-stress response in these symbionts, we investigated cultures of Symbiodinium goreauii type C1 and Symbiodinium sp. clade subtype D1 grown under a range of temperatures and durations. The predominant lipids produced by Symbiodinium are palmitic (C16) and stearic (C18) saturated fatty acids and their unsaturated analogs, the polyunsaturated fatty acid docosahexaenoic acid (C22:6, n-3; DHA), and a variety of sterols. Prolonged exposure to high temperature causes the relative amount of unsaturated acids within the C18 fatty acids in Symbiodinium tissue to decrease. Thermal stress also causes a decrease in abundance of fatty acids relative to sterols, as well as the more specific ratio of DHA to an algal 4-methyl sterol. These shifts in fatty acid unsaturation and fatty acid-to-sterol ratios are common to both types C1 and D1, but the apparent thermal threshold of lipid changes is lower for type C1. This work indicates that ratios among free fatty acids and sterols in Symbiodinium can be used as sensitive indicators of thermal stress. If the Symbiodinium lipid stress response is unchanged in hospite, the algal heat-stress biomarkers we have identified could be measured to detect thermal stress within the coral holobiont. These results provide new insights into the potential role of lipids in the overall Symbiodinium thermal stress response.

  17. Environmental forcings of Paleogene Southern Ocean dinoflagellate biogeography

    NASA Astrophysics Data System (ADS)

    Bijl, Peter K.; Pross, Jörg; Warnaar, Jeroen; Stickley, Catherine E.; Huber, Matthew; Guerstein, Raquel; Houben, Alexander J. P.; Sluijs, Appy; Visscher, Henk; Brinkhuis, Henk

    2011-02-01

    Despite warm polar climates and low meridional temperature gradients, a number of different high-latitude plankton assemblages were, to varying extents, dominated by endemic species during most of the Paleogene. To better understand the evolution of Paleogene plankton endemism in the high southern latitudes, we investigate the spatiotemporal distribution of the fossil remains of dinoflagellates, i.e., organic-walled cysts (dinocysts), and their response to changes in regional sea surface temperature (SST). We show that Paleocene and early Eocene (˜65-50 Ma) Southern Ocean dinocyst assemblages were largely cosmopolitan in nature but that a distinct switch from cosmopolitan-dominated to endemic-dominated assemblages (the so-called “transantarctic flora”) occurred around the early-middle Eocene boundary (˜50 Ma). The spatial distribution and relative abundance patterns of this transantarctic flora correspond well with surface water circulation patterns as reconstructed through general circulation model experiments throughout the Eocene. We quantitatively compare dinocyst assemblages with previously published TEX86-based SST reconstructions through the early and middle Eocene from a key locality in the southwest Pacific Ocean, ODP Leg 189 Site 1172 on the East Tasman Plateau. We conclude that the middle Eocene onset of the proliferation of the transantarctic flora is not linearly correlated with regional SST records and that only after the transantarctic flora became fully established later in the middle Eocene, possibly triggered by large-scale changes in surface-ocean nutrient availability, were abundances of endemic dinocysts modulated by regional SST variations.

  18. An epizootic of Florida manatees associated with a dinoflagellate bloom

    USGS Publications Warehouse

    O'Shea, T.J.; Rathbun, G.B.; Bonde, R.K.; Buergelt, C.D.; Odell, D.K.

    1991-01-01

    Over a 10-wk period in early 1982, 39 Florida manatees (Trichechus manatus latirostris) were found dead in the lower Caloosahatchee River and nearby waters of southwestern Florida. Two were killed by boats. The remainder showed no evidence of trauma. Lesions indicative of infectious agents were not identified, and bacteriological and contaminant residue findings were unremarkable. Nonspecific lesions of congestion and hemorrhage were identified in brain tissue. Numerous reports were also received of manatee morbidity. Some distressed manatees showed no biochemical lesions in clinical analyses of blood samples and recovered quickly. Timing of manatee illnesses coincided with fish and double-crested cormorant (Phalacrocorax auritus) mortality and morbidity. A widespread bloom of the dinoflagellate red tide organism (Gymnodinium breve) also coincided with these incidents. G. breve produces potent neurotoxins (brevetoxins). Circumstantial evidence links these events, and possible routes of exposure may include ingestion of filter-feeding ascidians. Ecological conditions that magnified the extent of the epizootic included an early dispersal of manatees into the area from a nearby winter aggregation site and unusually high salinities that facilitated the inshore spread of the red tide bloom. Management responses to future episodes of red tide in manatee areas are suggested.

  19. Functional Relationship between a Dinoflagellate Host and Its Diatom Endosymbiont.

    PubMed

    Hehenberger, Elisabeth; Burki, Fabien; Kolisko, Martin; Keeling, Patrick J

    2016-09-01

    While we know much about the evolutionary patterns of endosymbiotic organelle origins, we know less about how the actual process unfolded within each system. This is partly due to the massive changes endosymbiosis appears to trigger, and partly because most organelles evolved in the distant past. The dinotoms are dinoflagellates with diatom endosymbionts, and they represent a relatively recent but nevertheless obligate endosymbiotic association. We have carried out deep sequencing of both the host and endosymbiont transcriptomes from two dinotoms, Durinskia baltica and Glenodinium foliaceum, to examine how the nucleocytosolic compartments have functionally integrated. This analysis showed little or no functional reduction in either the endosymbiont or host, and no evidence for genetic integration. Rather, host and endosymbiont seem to be bound to each other via metabolites, such as photosynthate exported from the endosymbiont to the host as indicated by the presence of plastidic phosphate translocators in the host transcriptome. The host is able to synthesize starch, using plant-specific starch synthases, as a way to store imported photosynthate. PMID:27297471

  20. Structure Elucidation and in Vitro Toxicity of New Azaspiracids Isolated from the Marine Dinoflagellate Azadinium poporum

    PubMed Central

    Krock, Bernd; Tillmann, Urban; Potvin, Éric; Jeong, Hae Jin; Drebing, Wolfgang; Kilcoyne, Jane; Al-Jorani, Ahmed; Twiner, Michael J.; Göthel, Qun; Köck, Matthias

    2015-01-01

    Two strains of Azadinium poporum, one from the Korean West coast and the other from the North Sea, were mass cultured for isolation of new azaspiracids. Approximately 0.9 mg of pure AZA-36 (1) and 1.3 mg of pure AZA-37 (2) were isolated from the Korean (870 L) and North Sea (120 L) strains, respectively. The structures were determined to be 3-hydroxy-8-methyl-39-demethyl-azaspiracid-1 (1) and 3-hydroxy-7,8-dihydro-39-demethyl-azaspiracid-1 (2) by 1H- and 13C-NMR. Using the Jurkat T lymphocyte cell toxicity assay, (1) and (2) were found to be 6- and 3-fold less toxic than AZA-1, respectively. PMID:26528990

  1. Structure Elucidation and in Vitro Toxicity of New Azaspiracids Isolated from the Marine Dinoflagellate Azadinium poporum.

    PubMed

    Krock, Bernd; Tillmann, Urban; Potvin, Éric; Jeong, Hae Jin; Drebing, Wolfgang; Kilcoyne, Jane; Al-Jorani, Ahmed; Twiner, Michael J; Göthel, Qun; Köck, Matthias

    2015-11-01

    Two strains of Azadinium poporum, one from the Korean West coast and the other from the North Sea, were mass cultured for isolation of new azaspiracids. Approximately 0.9 mg of pure AZA-36 (1) and 1.3 mg of pure AZA-37 (2) were isolated from the Korean (870 L) and North Sea (120 L) strains, respectively. The structures were determined to be 3-hydroxy-8-methyl-39-demethyl-azaspiracid-1 (1) and 3-hydroxy-7,8-dihydro-39-demethyl-azaspiracid-1 (2) by ¹H- and (13)C-NMR. Using the Jurkat T lymphocyte cell toxicity assay, (1) and (2) were found to be 6- and 3-fold less toxic than AZA-1, respectively. PMID:26528990

  2. AN UNUSUAL POLYUNSATURATED C27 HYDROCARBON FROM THE MARINE DINOFLAGELLATE PYROCYSTIS LUNULA

    EPA Science Inventory

    Studies of the lipids of different algal species have revealed a diversity of fatty acids, sterols, and hydrocarbons, of which several are considered useful biomarkers, with potential for characterizing phytoplankton community composition. To extend this approach and characterize...

  3. Cloning, characterization and chromosomal localization of a repeated sequence in Crypthecodinium cohnii, a marine dinoflagellate.

    PubMed

    Moreau, H; Géraud, M L; Bhaud, Y; Soyer-Gobillard, M O

    1998-03-01

    Genomic DNA of Crypthecodinium cohnii has been extracted in the presence of cetylmethylammonium bromide and hydrolysed by 13 restriction enzymes. No typical ladder-like pattern or isolated band of satellite sequences were found with any of these enzymes. A "mini" genomic DNA library had been made and screened by reverse hybridization to isolate highly repeated sequences. Seven such DNA fragments were sequenced. The copy number of one of them (Cc18), 226 bp long, was estimated at around 25,000, representing 0.06% of the total genome. Cc18 was found to be included in a higher fragment of 3.0 kb by Southern blot analysis after cleavage by PstI. This higher molecular weight fragment could be composed either of tandemly repeated Cc18 sequences, or by only one or a very low copy number of Cc18. In this latter case, these fragments, also repeated 25,000 times would represent 1 to 2% of the total genome. Genomic localization of Cc18 by in situ hybridization on squashed C. cohnii cells showed that it was widely distributed on the different chromosomes. All the chromosomes observed displayed Cc18 labeling, which appeared homogeneously distributed. The ability of Cc18 to be a specific molecular marker to distinguish sibling C. cohnii species is discussed. PMID:10943339

  4. Seasonal Preservation Success of the Marine Dinoflagellate Coral Symbiont, Symbiodinium sp.

    PubMed

    Hagedorn, Mary; Carter, Virginia L

    2015-01-01

    Coral reefs are some of the most diverse and productive ecosystems on the planet, but are threatened by global and local stressors, mandating the need for incorporating ex situ conservation practices. One approach that is highly protective is the development of genome resource banks that preserve the species and its genetic diversity. A critical component of the reef are the endosymbiotic algae, Symbiodinium sp., living within most coral that transfer energy-rich sugars to their hosts. Although Symbiodinium are maintained alive in culture collections around the world, the cryopreservation of these algae to prevent loss and genetic drift is not well-defined. This study examined the quantum yield physiology and freezing protocols that resulted in survival of Symbiodinium at 24 h post-thawing. Only the ultra-rapid procedure called vitrification resulted in success whereas conventional slow freezing protocols did not. We determined that success also depended on using a thin film of agar with embedded Symbiodinium on Cryotops, a process that yielded a post-thaw viability of >50% in extracted and vitrified Symbiodinium from Fungia scutaria, Pocillopora damicornis and Porites compressa. Additionally, there also was a seasonal influence on vitrification success as the best post-thaw survival of F. scutaria occurred in winter and spring compared to summer and fall (P < 0.05). These findings lay the foundation for developing a viable genome resource bank for the world's Symbiodinium that, in turn, will not only protect this critical element of coral functionality but serve as a resource for understanding the complexities of symbiosis, support selective breeding experiments to develop more thermally resilient strains of coral, and provide a 'gold-standard' genomics collection, allowing for full genomic sequencing of unique Symbiodinium strains. PMID:26422237

  5. Seasonal Preservation Success of the Marine Dinoflagellate Coral Symbiont, Symbiodinium sp.

    PubMed Central

    Hagedorn, Mary; Carter, Virginia L.

    2015-01-01

    Coral reefs are some of the most diverse and productive ecosystems on the planet, but are threatened by global and local stressors, mandating the need for incorporating ex situ conservation practices. One approach that is highly protective is the development of genome resource banks that preserve the species and its genetic diversity. A critical component of the reef are the endosymbiotic algae, Symbiodinium sp., living within most coral that transfer energy-rich sugars to their hosts. Although Symbiodinium are maintained alive in culture collections around the world, the cryopreservation of these algae to prevent loss and genetic drift is not well-defined. This study examined the quantum yield physiology and freezing protocols that resulted in survival of Symbiodinium at 24 h post-thawing. Only the ultra-rapid procedure called vitrification resulted in success whereas conventional slow freezing protocols did not. We determined that success also depended on using a thin film of agar with embedded Symbiodinium on Cryotops, a process that yielded a post-thaw viability of >50% in extracted and vitrified Symbiodinium from Fungia scutaria, Pocillopora damicornis and Porites compressa. Additionally, there also was a seasonal influence on vitrification success as the best post-thaw survival of F. scutaria occurred in winter and spring compared to summer and fall (P < 0.05). These findings lay the foundation for developing a viable genome resource bank for the world’s Symbiodinium that, in turn, will not only protect this critical element of coral functionality but serve as a resource for understanding the complexities of symbiosis, support selective breeding experiments to develop more thermally resilient strains of coral, and provide a ‘gold-standard’ genomics collection, allowing for full genomic sequencing of unique Symbiodinium strains. PMID:26422237

  6. Stimulable and spontaneous bioluminescence in the marine dinoflagellates, Pyrodinium bahamense, Gonyaulax polyedra, and Pyrocystis lunula.

    PubMed

    Biggley, W H; Swift, E; Buchanan, R J; Seliger, H H

    1969-07-01

    P. bahamense, G. polyedra, and P. lunula exhibit interspecies differences in stimulable and spontaneous bioluminescence. For each species the total number of photons that can be emitted upon mechanical stimulation is a constant, regardless of the time during scotophase at which stimulation occurs. Ratios of stimulable bioluminescence per organism during scotophase and photophase are as high as 950:1 for laboratory cultures and have been observed as high as 4000: 1 for natural populations of P. bahamense. Spontaneous emission in darkness shows flashing as well as low-level continuous emission. Natural populations of P. bahamense, placed in darkness during natural photophase, exhibit a dual character to their stimulable bioluminescence. Mechanical stimulation techniques are described for rapid and reproducible stimulation of bioluminescence. PMID:5792367

  7. Stimulable and Spontaneous Bioluminescence in the Marine Dinoflagellates, Pyrodinium bahamense, Gonyaulax polyedra, and Pyrocystis lunula

    PubMed Central

    Biggley, W. H.; Swift, E.; Buchanan, R. J.; Seliger, H. H.

    1969-01-01

    P. bahamense, G. polyedra, and P. lunula exhibit interspecies differences in stimulable and spontaneous bioluminescence. For each species the total number of photons that can be emitted upon mechanical stimulation is a constant, regardless of the time during scotophase at which stimulation occurs. Ratios of stimulable bioluminescence per organism during scotophase and photophase are as high as 950:1 for laboratory cultures and have been observed as high as 4000: 1 for natural populations of P. bahamense. Spontaneous emission in darkness shows flashing as well as low-level continuous emission. Natural populations of P. bahamense, placed in darkness during natural photophase, exhibit a dual character to their stimulable bioluminescence. Mechanical stimulation techniques are described for rapid and reproducible stimulation of bioluminescence. PMID:5792367

  8. New observations on the meiotic process in the marine dinoflagellate Noctiluca scintillans (Noctilucales, dinophyceae)

    NASA Astrophysics Data System (ADS)

    Zhou, Cheng-Xu; Yan, Xiao-Jun

    2002-03-01

    The meiotic process in Noctiluca scintillans were observed under light microscope. Some abnormal cell divisions, incompletely separated “zoospores” and the changes of the zoospores are described in this paper. Together with the findings of field samplings and the previous results by other researcher, the process of meiosis in N. scintillans was supposed to be a pathway to reduce the extra high density of NH3-N within the cell in order to ensure normal population growth.

  9. LIPID CLASS DISTRIBUTION OF HIGHLY UNSATURATED LONG CHAIN FATTY ACIDS IN MARINE DINOFLAGELLATES.

    EPA Science Inventory

    The very long chain highly unsaturated C28 fatty acids, octacosaheptaenoic [28:7(n-6)] and octacosaoctaenoic acid [28:8(n-3)], were found to be associated with phospholipids, obtained by fractionation of total lipid extracts into distinct lipid classes, in 4 and 6, respectively, ...

  10. Sedimentary Records of Harmful Bloom-Producing Dinoflagellates from Alvarado Lagoon (Southwestern Gulf of Mexico)

    NASA Astrophysics Data System (ADS)

    Limoges, A.; Mertens, K. N.; ruiz-Fernandez, A. C.; Sánchez Cabeza, J. A.; de Vernal, A.

    2014-12-01

    Organic-walled dinoflagellate cyst assemblages were studied from a sediment core collected in Alvarado Lagoon (southwestern Gulf of Mexico) in order to evaluate their use as tracers of toxic algal blooms. The sedimentary record spans the last ~560 years (CE) and shows high abundances of Polysphaeridium zoharyi, the cyst of the dinoflagellate Pyrodinium bahamense, which is known to cause toxic blooms. Cyst fluxes in the sediment of the Alvarado lagoon suggest frequent blooms of Pyrodinium bahamense in the past hundreds of years. Moreover, the high concentrations of the cysts (~ 4000 cysts g-1) in the "modern" surface sediment reveal that the area is susceptible to be affected by future blooms, especially during seasons of heavy rain and wind, when cysts are resuspended in the water column. The dinoflagellate cyst bank in sediment deserves special attention as it may constitute a source for the export of cells in adjacent regions. The cyst of other harmful dinoflagellates have been recovered in the sediment. They notably include those of the benthic dinoflagellate Bysmatrum subsalsum, which is here reported for the first time.

  11. Histone-Like Proteins of the Dinoflagellate Crypthecodinium cohnii Have Homologies to Bacterial DNA-Binding Proteins

    PubMed Central

    Wong, J. T. Y.; New, D. C.; Wong, J. C. W.; Hung, V. K. L.

    2003-01-01

    The dinoflagellates have very large genomes encoded in permanently condensed and histoneless chromosomes. Sequence alignment identified significant similarity between the dinoflagellate chromosomal histone-like proteins of Crypthecodinium cohnii (HCCs) and the bacterial DNA-binding and the eukaryotic histone H1 proteins. Phylogenetic analysis also supports the origin of the HCCs from histone-like proteins of bacteria. PMID:12796310

  12. THE "HYSTRICHOSPHAERID" RESTING SPORE OF THE DINOFLAGELLATE PYRODINIUM BAHAMENSE, PLATF, 1906(2).

    PubMed

    Wall, D; Dale, B

    1969-06-01

    Germination experiments demonstrate that the "hystrichosphere" called Hemicystodinium zoharyi, which previously has been found only as a microfossil organism, is the resting spore stage in the life history of Pyrodinium bahamense, a modern bioluminescent, thecate dinoflagellate. The morphology of this spore, together with new details of the thecal structure and ontogeny of P. bahamense, is described, and it is concluded that Pyrodinium is closely related to Gonyaulax but worthy of retention as a discrete genus. The geological history of P. bahamense is traceable to the Eocene through fossil occurrences of its spore, and it is suggested that additional pyrodinioid dinoflagellates which now are extinct were represented in Lower Tertiary seas by another hystrichosphere genus, called Homotryblium. Selected aspects of the physiology and ecology of modern dinoflagellate resting spores are discussed briefly with special reference to Pyrodinium. PMID:27096245

  13. Evidence for the Retention of Two Evolutionary Distinct Plastids in Dinoflagellates with Diatom Endosymbionts

    PubMed Central

    Hehenberger, Elisabeth; Imanian, Behzad; Burki, Fabien; Keeling, Patrick J.

    2014-01-01

    Dinoflagellates harboring diatom endosymbionts (termed “dinotoms”) have undergone a process often referred to as “tertiary endosymbiosis”—the uptake of algae containing secondary plastids and integration of those plastids into the new host. In contrast to other tertiary plastids, and most secondary plastids, the endosymbiont of dinotoms is distinctly less reduced, retaining a number of cellular features, such as their nucleus and mitochondria and others, in addition to their plastid. This has resulted in redundancy between host and endosymbiont, at least between some mitochondrial and cytosolic metabolism, where this has been investigated. The question of plastidial redundancy is particularly interesting as the fate of the host dinoflagellate plastid is unclear. The host cytosol possesses an eyespot that has been postulated to be a remnant of the ancestral peridinin plastid, but this has not been tested, nor has its possible retention of plastid functions. To investigate this possibility, we searched for plastid-associated pathways and functions in transcriptomic data sets from three dinotom species. We show that the dinoflagellate host has indeed retained genes for plastid-associated pathways and that these genes encode targeting peptides similar to those of other dinoflagellate plastid-targeted proteins. Moreover, we also identified one gene encoding an essential component of the dinoflagellate plastid protein import machinery, altogether suggesting the presence of a functioning plastid import system in the host, and by extension a relict plastid. The presence of the same plastid-associated pathways in the endosymbiont also extends the known functional redundancy in dinotoms, further confirming the unusual state of plastid integration in this group of dinoflagellates. PMID:25172904

  14. In vitro culture and developmental cycle of the parasitic dinoflagellate Hematodinium sp. from the blue crab Callinectes sapidus.

    PubMed

    Li, Caiwen; Miller, Terrence L; Small, Hamish J; Shields, Jeffrey D

    2011-12-01

    Hematodinium is a genus of parasitic dinoflagellates whose species have caused significant mortalities in marine crustacean fisheries worldwide. A species of Hematodinium infects the blue crab, Callinectes sapidus on the eastern seaboard of the USA. The mode of transmission of the parasite in blue crabs is unknown. We established several continuous in vitro cultures of Hematodinium sp. isolated from the haemolymph of infected blue crabs. One isolate has been continuously maintained in our laboratory through serial subcultivation for over 12 months, and is capable of infecting new hosts when inoculated into healthy crabs. Cells of the parasite undergo characteristic developmental changes in vitro consistent with the identifiable stages of Hematodinium sp.: filamentous trophonts, amoeboid trophonts, arachnoid trophonts and sporonts, sporoblasts, prespores and dinospores (macrospores and microspores). Additionally, we describe an unusual shunt in the life cycle wherein presumptive schizonts derived from arachnoid sporonts developed into filamentous and arachnoid trophonts that can then initiate arachnoid sporonts in new cultures. This may explain the rapid proliferation of the parasite in blue crab hosts. We also found that temperature and light intensity affected the growth and development of the parasite in vitro. PMID:21902874

  15. Extraction and Analysis of Mycosporine-Like Amino Acids in Marine Algae.

    PubMed

    Rosic, Nedeljka N; Braun, Christoph; Kvaskoff, David

    2015-01-01

    Marine organisms use mycosporine-like amino acids (MAAs) as biological sunscreens for the protection from damaging ultraviolet (UV) radiation and the prevention of oxidative stress. MAAs have been discovered in many different marine and freshwater species including cyanobacteria, fungi, and algae, but also in animals like cnidarian and fishes. Here, we describe a general method for the isolation and characterization of MAA compounds from red algae and symbiotic dinoflagellates isolated from coral hosts. This method is also suitable for the extraction and analyses of MAAs from a range of other algal and marine biota. PMID:26108501

  16. Cell volumes, maximal growth rates of unicellular algae and ciliates, and the role of ciliates in the marine pelagial

    SciTech Connect

    Banse, K.

    1982-01-01

    A review of growth rates of diatoms and dinoflagellates in light-saturated, nutrient-replete cultures at 20/sup 0/C confirms weak dependence on cell volume or mass. These maximal (intrinsic) rates are not linearly related to surface area or surface-to-volume ratio of the cells. The growth of most diatoms is materially faster than that of dinoflagellates; other algae fall in between or below the dinoflagellates. Small ciliates have appreciably higher intrinsic growth rates than algae of the same cell volume. The average food consumption per ciliate in the marine pelagic realm is inferred to be very low, so that the realized specific growth rates are much smaller than the intrinsic potentials. Also, a previously postulated refuge from predation, afforded by small size, is extended down to about 10-..mu..m/sup 3/ cell volume.

  17. STEROLS AS BIOMARKERS IN GYMNODINIUM BREVE DISTRIBUTION IN DINOFLAGELLATES

    EPA Science Inventory

    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 ...

  18. Rhodopsin gene expression regulated by the light dark cycle, light spectrum and light intensity in the dinoflagellate Prorocentrum

    PubMed Central

    Shi, Xinguo; Li, Ling; Guo, Chentao; Lin, Xin; Li, Meizhen; Lin, Senjie

    2015-01-01

    The proton pump rhodopsin is widely found in marine bacteria and archaea, where it functions to capture light energy and convert it to ATP. While found in several lineages of dinoflagellates, this gene has not been studied in Prorocentrales species and whether it functionally tunes to light spectra and intensities as in bacteria remains unclear. Here we identified and characterized this gene in the bloom-forming Prorocentrum donghaiense. It is a 7-helix transmembrane polypeptide containing conserved domains and critical amino acid residues of PPR. This gene is phylogenetically affiliated to the xanthorhodopsin clade, but seems to have a distinct evolutionary origin. Quantitative reverse transcription PCR showed that in regular cultures, the transcript abundance of the gene exhibited a clear diel pattern, high abundance in the light period and low in the dark. The same diel pattern was observed for protein abundance with a Western blot using specific antiserum. The rhythm was dampened when the cultures were shifted to continuous dark or light condition, suggesting that this gene is not under circadian clock control. Rhodopsin transcript and protein abundances varied with light intensity, both being highest at a moderate illumination level. Furthermore, the expression of this gene responded to different light spectra, with slightly higher transcript abundance under green than blue light, and lowest abundance under red light. Transformed Escherichia coli over-expressing this rhodopsin gene also exhibited an absorption maximum in the blue–green region with slightly higher absorption in the green. These rhodopsin-promoting light conditions are similar to the relatively turbid marine habitat where the species forms blooms, suggesting that this gene may function to compensate for the light-limited photosynthesis in the dim environment. PMID:26082770

  19. Quantitative histopathology of the Mediterranean mussel (Mytilus galloprovincialis L.) exposed to the harmful dinoflagellate Ostreopsis cf. ovata.

    PubMed

    Carella, F; Sardo, A; Mangoni, O; Di Cioccio, D; Urciuolo, G; De Vico, G; Zingone, A

    2015-05-01

    Ostreopsis cf. ovata is a benthic dinoflagellate that produces palytoxin-like compounds that adversely affect both marine vertebrates and invertebrates and are reported to be responsible for human intoxication in aerosol form. In this work, a histopathological analysis accompanied by quantitative evaluation of tissue injury in mussels (Mytilus galloprovincialis) exposed to O. cf. ovata cells under natural and experimental conditions, provided baseline data on the health status of the mussels in terms of defensive and regressive pathological changes. We recorded a total of 15 health parameters in the digestive system, muscle, kidney and gills in mussels exposed to O. cf. ovata both in the laboratory and at sea. Animals exposed to different concentrations of O. cf. ovata cells (300, 500 and 1000cellsml(-)(1)) for 48h showed activation of the inflammatory response, which increased with the cell concentration, mainly characterized by haemocyte aggregates actively enclosing the algae, while mussel mortality was also recorded in some cases. Moreover the use of image analysis for the evaluation of digestive tubule damage revealed a pronounced increase in the lumen in terms of its area, perimeter and circularity, with a shift in a high percentage of tubules from an adsorbing profile to an atrophic profile. Animals collected from the natural environment during a summer bloom of O. cf. ovata in the Gulf of Naples (Italy) showed comparable lesions in terms of types and severity. This is the first quantitative study assessing damage to the digestive epithelia in terms of lumen modifications in mussels exposed to O. cf. ovata. The presented methodology provides a new technique for automating the evaluation of epithelial tubule modifications. Our results highlight the importance of monitoring the presence of O. cf. ovata in this area, taking into account the effects on the residing marine species. PMID:25769513

  20. Toxin and Growth Responses of the Neurotoxic Dinoflagellate Vulcanodinium rugosum to Varying Temperature and Salinity

    PubMed Central

    Abadie, Eric; Muguet, Alexia; Berteaux, Tom; Chomérat, Nicolas; Hess, Philipp; Roque D’OrbCastel, Emmanuelle; Masseret, Estelle; Laabir, Mohamed

    2016-01-01

    Vulcanodinium rugosum, a recently described species, produces pinnatoxins. The IFR-VRU-01 strain, isolated from a French Mediterranean lagoon in 2010 and identified as the causative dinoflagellate contaminating mussels in the Ingril Lagoon (French Mediterranean) with pinnatoxin-G, was grown in an enriched natural seawater medium. We tested the effect of temperature and salinity on growth, pinnatoxin-G production and chlorophyll a levels of this dinoflagellate. These factors were tested in combinations of five temperatures (15, 20, 25, 30 and 35 °C) and five salinities (20, 25, 30, 35 and 40) at an irradiance of 100 µmol photon m−2 s−1. V. rugosum can grow at temperatures and salinities ranging from 20 °C to 30 °C and 20 to 40, respectively. The optimal combination for growth (0.39 ± 0.11 d−1) was a temperature of 25 °C and a salinity of 40. Results suggest that V. rugosum is euryhaline and thermophile which could explain why this dinoflagellate develops in situ only from June to September. V. rugosum growth rate and pinnatoxin-G production were highest at temperatures ranging between 25 and 30 °C. This suggests that the dinoflagellate may give rise to extensive blooms in the coming decades caused by the climate change-related increases in temperature expected in the Mediterranean coasts. PMID:27164144

  1. Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates

    USGS Publications Warehouse

    Peglar, M.T.; Nerad, T.A.; Anderson, O.R.; Gillevet, P.M.

    2004-01-01

    This study was undertaken to assess whether amoebae commonly found in mesohaline environments are in fact stages in the life cycles of Pfiesteria and Pfiesteria-like dinoflagellates. Primary isolations of amoebae and dinoflagellates were made from water and sediment samples from five tributaries of the Chesapeake Bay. Additional amoebae were also cloned from bioassay aquaria where fish mortality was attributed to Pfiesteria. Electron microscopy and small subunit (SSU) rRNA gene sequence analysis of these isolates clearly demonstrated that the commonly depicted amoeboid form of Pfiesteria is very likely a species of Korotnevella and is unrelated to Pfiesteria or Pfiesteria-like dinoflagellates. We have determined that the Pfiesteria and Pfiesteria-like dinoflagellates examined in this study undergo a typical homothallic life cycle without amoeboid stages. Furthermore, we have demonstrated that cloned amoebae sharing morphological characteristics described for stages in the life cycle of Pfiesteria do not transform into dinozoites. The strict clonal isolation and cultivation techniques used in this study substantially support the conclusion that the amoebae and some of the flagellates depicted in the life cycle of Pfiesteria are environmental contaminants of the Pfiesteria culture system and that the Ambush Predator Hypothesis needs to be rigorously reevaluated.

  2. A single-cell view of ammonium assimilation in coral–dinoflagellate symbiosis

    PubMed Central

    Pernice, Mathieu; Meibom, Anders; Van Den Heuvel, Annamieke; Kopp, Christophe; Domart-Coulon, Isabelle; Hoegh-Guldberg, Ove; Dove, Sophie

    2012-01-01

    Assimilation of inorganic nitrogen from nutrient-poor tropical seas is an essential challenge for the endosymbiosis between reef-building corals and dinoflagellates. Despite the clear evidence that reef-building corals can use ammonium as inorganic nitrogen source, the dynamics and precise roles of host and symbionts in this fundamental process remain unclear. Here, we combine high spatial resolution ion microprobe imaging (NanoSIMS) and pulse-chase isotopic labeling in order to track the dynamics of ammonium incorporation within the intact symbiosis between the reef-building coral Acropora aspera and its dinoflagellate symbionts. We demonstrate that both dinoflagellate and animal cells have the capacity to rapidly fix nitrogen from seawater enriched in ammonium (in less than one hour). Further, by establishing the relative strengths of the capability to assimilate nitrogen for each cell compartment, we infer that dinoflagellate symbionts can fix 14 to 23 times more nitrogen than their coral host cells in response to a sudden pulse of ammonium-enriched seawater. Given the importance of nitrogen in cell maintenance, growth and functioning, the capability to fix ammonium from seawater into the symbiotic system may be a key component of coral nutrition. Interestingly, this metabolic response appears to be triggered rapidly by episodic nitrogen availability. The methods and results presented in this study open up for the exploration of dynamics and spatial patterns associated with metabolic activities and nutritional interactions in a multitude of organisms that live in symbiotic relationships. PMID:22222466

  3. Comparative Analysis of Membrane Lipids in Psychrophilic and Mesophilic Freshwater Dinoflagellates

    PubMed Central

    Anesi, Andrea; Obertegger, Ulrike; Hansen, Gert; Sukenik, Assaf; Flaim, Giovanna; Guella, Graziano

    2016-01-01

    Here we report the lipid profiles of ten dinoflagellate species originating from different freshwater habitats and grown at 4, 13, or 20°C akin to their natural occurrence. Lipids were determined by High Performance Liquid Chromatography-ElectroSpray Ionization-Mass Spectrometry in positive and negative ion modes. Besides the well-studied monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) lipids, our study revealed the presence of intact molecular lipid species of trigalactosyldiacylglycerols, betaine diacylglyceryl-carboxyhydroxymethylcholine, sulfolipid sulfoquinovosyldiacylglycerols (SQDG) and phospholipids, in particular phosphatidylcholine, phosphatidylethanolamine and phosphatidylglycerol. In multivariate ordination, the freshwater dinoflagellates studied could be distinguished into two groups based on their lipid profiles. Peridinium aciculiferum, Borghiella dodgei, B. tenuissima and Tovellia coronata belonged to group 1 while Ceratium cornutum, Gymnodinium palustre, Jadwigia applanata, P. cinctum, P. willei, and P. gatunense belonged to group 2. Indicator species analysis evidenced that group 1 was characterized by 36:9 MGDG and 36:9 DGDG and group 2 by 38:9 and 38:10 MGDG, 38:9 and 38:10 DGDG and 34:1 SQDG. We suggest that the grouping of dinoflagellates indicated their range of temperature tolerance. Furthermore, non-thylakoid lipids were linked to dinoflagellate phylogeny based on the large ribosomal sub-unit (28S LSU) rather than their temperature tolerance. Thus certain lipids better reflected habitat adaptation while other lipids better reflected genetic diversity. PMID:27148341

  4. Systematics of a Kleptoplastidal Dinoflagellate, Gymnodinium eucyaneum Hu (Dinophyceae), and Its Cryptomonad Endosymbiont

    PubMed Central

    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. PMID:23308288

  5. STEROLS OF THE HETEROTROPHIC DINOFLAGELLATE, PFIESTERIA PISCICIDA (DINOPHYCEAE): IS THERE A LIPID BIOMARKER?

    EPA Science Inventory

    Within United States waters, blooms of the dinoflagellate, Pfiesteria piscicida, have been recorded on an almost regular basis in the Chesapeake Bay and surrounding mid-Atlantic regions for the last two decades. Despite the apparent significance of such blooms to the environment ...

  6. DINOFLAGELLATE CYST RECORD AND HUMAN DISTURBANCE IN NEW BEDFORD HARBOR, MA AND NARRAGANSETT BAY ESTUARIES

    EPA Science Inventory

    We studied the dinoflagellate cyst records in sediments from New Bedford Harbor and Apponagansett Bay over the last 350 yr provides to determine if cysts are sensitive to environmental change caused by human activity in the watershed. Changes in the total number, and absolute and...

  7. A single-cell view of ammonium assimilation in coral-dinoflagellate symbiosis.

    PubMed

    Pernice, Mathieu; Meibom, Anders; Van Den Heuvel, Annamieke; Kopp, Christophe; Domart-Coulon, Isabelle; Hoegh-Guldberg, Ove; Dove, Sophie

    2012-07-01

    Assimilation of inorganic nitrogen from nutrient-poor tropical seas is an essential challenge for the endosymbiosis between reef-building corals and dinoflagellates. Despite the clear evidence that reef-building corals can use ammonium as inorganic nitrogen source, the dynamics and precise roles of host and symbionts in this fundamental process remain unclear. Here, we combine high spatial resolution ion microprobe imaging (NanoSIMS) and pulse-chase isotopic labeling in order to track the dynamics of ammonium incorporation within the intact symbiosis between the reef-building coral Acropora aspera and its dinoflagellate symbionts. We demonstrate that both dinoflagellate and animal cells have the capacity to rapidly fix nitrogen from seawater enriched in ammonium (in less than one hour). Further, by establishing the relative strengths of the capability to assimilate nitrogen for each cell compartment, we infer that dinoflagellate symbionts can fix 14 to 23 times more nitrogen than their coral host cells in response to a sudden pulse of ammonium-enriched seawater. Given the importance of nitrogen in cell maintenance, growth and functioning, the capability to fix ammonium from seawater into the symbiotic system may be a key component of coral nutrition. Interestingly, this metabolic response appears to be triggered rapidly by episodic nitrogen availability. The methods and results presented in this study open up for the exploration of dynamics and spatial patterns associated with metabolic activities and nutritional interactions in a multitude of organisms that live in symbiotic relationships. PMID:22222466

  8. Toxin and Growth Responses of the Neurotoxic Dinoflagellate Vulcanodinium rugosum to Varying Temperature and Salinity.

    PubMed

    Abadie, Eric; Muguet, Alexia; Berteaux, Tom; Chomérat, Nicolas; Hess, Philipp; Roque D'OrbCastel, Emmanuelle; Masseret, Estelle; Laabir, Mohamed

    2016-01-01

    Vulcanodinium rugosum, a recently described species, produces pinnatoxins. The IFR-VRU-01 strain, isolated from a French Mediterranean lagoon in 2010 and identified as the causative dinoflagellate contaminating mussels in the Ingril Lagoon (French Mediterranean) with pinnatoxin-G, was grown in an enriched natural seawater medium. We tested the effect of temperature and salinity on growth, pinnatoxin-G production and chlorophyll a levels of this dinoflagellate. These factors were tested in combinations of five temperatures (15, 20, 25, 30 and 35 °C) and five salinities (20, 25, 30, 35 and 40) at an irradiance of 100 µmol photon m(-2) s(-1). V. rugosum can grow at temperatures and salinities ranging from 20 °C to 30 °C and 20 to 40, respectively. The optimal combination for growth (0.39 ± 0.11 d(-1)) was a temperature of 25 °C and a salinity of 40. Results suggest that V. rugosum is euryhaline and thermophile which could explain why this dinoflagellate develops in situ only from June to September. V. rugosum growth rate and pinnatoxin-G production were highest at temperatures ranging between 25 and 30 °C. This suggests that the dinoflagellate may give rise to extensive blooms in the coming decades caused by the climate change-related increases in temperature expected in the Mediterranean coasts. PMID:27164144

  9. Applying Clustering and Phylogeny Analysis to Study Dinoflagellates based on Sterol Composition.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sterol compositions of dinoflagellates have been studied for several decades as a means of assessing whether certain species possess unique chemical biomarkers. However, no attempt has been made to compile the results from numerous studies to examine how sterol compositions may relate to the phylog...

  10. Significance of Plankton Community Structure and Nutrient Availability for the Control of Dinoflagellate Blooms by Parasites: A Modeling Approach

    PubMed Central

    Alves-de-Souza, Catharina; Pecqueur, David; Le Floc’h, Emilie; Mas, Sébastien; Roques, Cécile; Mostajir, Behzad; Vidussi, Franscesca; Velo-Suárez, Lourdes; Sourisseau, Marc; Fouilland, Eric; Guillou, Laure

    2015-01-01

    Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole. PMID:26030411

  11. Loktanella spp. Gb03 as an algicidal bacterium, isolated from the culture of Dinoflagellate Gambierdiscus belizeanus

    PubMed Central

    Bloh, Anmar Hameed; Usup, Gires; Ahmad, Asmat

    2016-01-01

    Aim: Bacteria associated with harmful algal blooms can play a crucial role in regulating algal blooms in the environment. This study aimed at isolating and identifying algicidal bacteria in Dinoflagellate culture and to determine the optimum growth requirement of the algicidal bacteria, Loktanella sp. Gb-03. Materials and Methods: The Dinoflagellate culture used in this study was supplied by Professor Gires Usup's Laboratory, School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, University Kebangsaan Malaysia, Malaysia. The culture was used for the isolation of Loktanella sp., using biochemical tests, API 20 ONE kits. The fatty acid content of the isolates and the algicidal activity were further evaluated, and the phenotype was determined through the phylogenetic tree. Results: Gram-negative, non-motile, non-spore-forming, short rod-shaped, aerobic bacteria (Gb01, Gb02, Gb03, Gb04, Gb05, and Gb06) were isolated from the Dinoflagellate culture. The colonies were pink in color, convex with a smooth surface and entire edge. The optimum growth temperature for the Loktanella sp. Gb03 isolate was determined to be 30°C, in 1% of NaCl and pH7. Phylogenetic analysis based on 16S rRNA gene sequences showed that the bacterium belonged to the genus Loktanella of the class Alphaproteobacteria and formed a tight cluster with the type strain of Loktanella pyoseonensis (97.0% sequence similarity). Conclusion: On the basis of phenotypic, phylogenetic data and genetic distinctiveness, strain Gb-03, were placed in the genus Loktanella as the type strain of species. Moreover, it has algicidal activity against seven toxic Dinoflagellate. The algicidal property of the isolated Loktanella is vital, especially where biological control is needed to mitigate algal bloom or targeted Dinoflagellates. PMID:27051199

  12. The role of dissolved organic matter (DOM) quality in the growth enhancement of Alexandrium fundyense (Dinophyceae) in laboratory culture(1).

    PubMed

    Cawley, Kaelin M; Koerfer, Verena; McKnight, Diane M

    2013-06-01

    Several algal species responsible for harmful algal blooms (HABs), such as Alexandrium fundyense, are mixotrophic under certain environmental conditions. The ability to switch between photosynthetic and heterotrophic modes of growth may play a role in the development of HABs in coastal regions. We examined the influence of humic dissolved organic matter (HDOM) derived from terrestrial (plant/soil) and microbial sources on the growth of A. fundyense. We found that a terrestrially derived HDOM, Suwannee River humic acid (SRHA), did enhance A. fundyense growth; however, a microbially derived HDOM, Pony Lake fulvic acid (PLFA) did not enhance growth. A. fundyense grows in association with bacteria in culture and we observed that bacterial cell densities were much lower in A. fundyense cultures than in bacteria-only cultures, consistent with bacterial grazing by A. fundyense in culture. In bacteria-only cultures with added algal exudates (EX), the addition of PLFA and SRHA resulted in a slight increase in bacterial cell density compared to cultures without HDOM added. Changes over time in the chemical quality of the HDOM in the A. fundyense cultures reflected contributions of microbially derived material with similar characteristics as the PLFA. Overall, these results suggest that the chemical differences between SRHA and PLFA are responsible for the greater effect of SRHA on A. fundyense growth, and that the differential effect is not a result of an effect on the growth of associated bacteria. PMID:27007043

  13. Investigation of the 2006 Alexandrium fundyense bloom in the Gulf of Maine: In-situ observations and numerical modeling

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Li, Y.; He, R.; McGillicuddy, D. J.; Anderson, D. M.; Keafer, B. A.

    2008-12-01

    In situ observations and a coupled bio-physical model are used to study the Gulf of Maine (GOM) coastal ocean hydrodynamics, and the initiation, and development of the Alexandrium fundyense bloom in 2006. Hydrographic measurements indicate that 2006 is a year with normal coastal water temperature, salinity, current and river runoff conditions in comparison with the GOM climatology. A. fundyense cyst observations preceding the 2006 bloom show lower concentrations compared to other recent survey data. A coupled bio- physical model is used to hindcast coastal hydrodynamics and A. fundyense cell concentrations. Field data including water temperature, salinity, velocity time series and surface cell concentration maps are used to gauge the model's fidelity, indicating this coupled model is able to reproduce coastal circulation and the temporal and spatial distributions of A. fundyense cell concentration reasonably well. Model hindcast solutions are further used to diagnose physical and biological factors controlling the bloom dynamics. The initial cyst distribution is found to be the key factor controlling the severity of the bloom. Surface wind fields play an important role in modulating bloom's horizontal and vertical distribution. During the bloom's initiation phase, seasonal warming is a major factor determining the net growth rate. Later in the season, nutrient availability and cell mortality collectively control three-dimensional bloom distribution.

  15. Diversity and dynamics of Antarctic marine microbial eukaryotes under manipulated environmental UV radiation.

    PubMed

    Piquet, Anouk M-T; Bolhuis, Henk; Davidson, Andrew T; Thomson, Paul G; Buma, Anita G J

    2008-11-01

    In the light of the predicted global climate change, it is essential that the status and diversity of polar microbial communities is described and understood. In the present study, molecular tools were used to investigate the marine eukaryotic communities of Prydz Bay, Eastern Antarctica, from November 2002 to January 2003. Additionally, we conducted four series of minicosm experiments, where natural Prydz Bay communities were incubated under six different irradiation regimes, in order to investigate the effects of natural UV radiation on marine microbial eukaryotes. Denaturing gradient gel electrophoresis (DGGE) and 18S rRNA gene sequencing revealed a eukaryotic Shannon diversity index averaging 2.26 and 2.12, respectively. Phylogenetic analysis of 472 sequenced clones revealed 47 phylotypes, belonging to the Dinophyceae, Stramenopiles, Choanoflagellidae, Ciliophora, Cercozoa and Metazoa. Throughout the studied period, three communities were distinguished: a postwinter/early spring community comprising dinoflagellates, ciliates, cercozoans, stramenopiles, viridiplantae, haptophytes and metazoans; a dinoflagellate-dominated community; and a diatom-dominated community that developed after sea ice breakup. DGGE analysis showed that size fraction and time had a strong shaping effect on the community composition; however, a significant contribution of natural UV irradiance towards microeukaryotic community composition could not be detected. Overall, dinoflagellates dominated our samples and their diversity suggests that they fulfill an important role in Antarctic coastal marine ecosystems preceding ice breakup as well as between phytoplankton bloom events. PMID:18801046

  16. Biological importance of marine algae

    PubMed Central

    El Gamal, Ali A.

    2009-01-01

    Marine organisms are potentially prolific sources of highly bioactive secondary metabolites that might represent useful leads in the development of new pharmaceutical agents. Algae can be classified into two main groups; first one is the microalgae, which includes blue green algae, dinoflagellates, bacillariophyta (diatoms)… etc., and second one is macroalgae (seaweeds) which includes green, brown and red algae. The microalgae phyla have been recognized to provide chemical and pharmacological novelty and diversity. Moreover, microalgae are considered as the actual producers of some highly bioactive compounds found in marine resources. Red algae are considered as the most important source of many biologically active metabolites in comparison to other algal classes. Seaweeds are used for great number of application by man. The principal use of seaweeds as a source of human food and as a source of gums (phycocollides). Phycocolloides like agar agar, alginic acid and carrageenan are primarily constituents of brown and red algal cell walls and are widely used in industry. PMID:23960716

  17. Mapping the Distribution of Cysts from the Toxic Dinoflagellate Cochlodinium polykrikoides in Bloom-Prone Estuaries by a Novel Fluorescence In Situ Hybridization Assay

    PubMed Central

    Hattenrath-Lehmann, Theresa K.; Zhen, Yu; Wallace, Ryan B.

    2015-01-01

    Cochlodinium polykrikoides is a cosmopolitan dinoflagellate that is notorious for causing fish-killing harmful algal blooms (HABs) across North America and Asia. While recent laboratory and ecosystem studies have definitively demonstrated that Cochlodinium forms resting cysts that may play a key role in the dynamics of its HABs, uncertainties regarding cyst morphology and detection have prohibited even a rudimentary understanding of the distribution of C. polykrikoides cysts in coastal ecosystems. Here, we report on the development of a fluorescence in situ hybridization (FISH) assay using oligonucleotide probes specific for the large subunit (LSU) ribosomal DNA (rDNA) of C. polykrikoides. The LSU rDNA-targeted FISH assay was used with epifluorescence microscopy and was iteratively refined to maximize the fluorescent reaction with C. polykrikoides and minimize cross-reactivity. The final LSU rDNA-targeted FISH assay was found to quantitatively recover cysts made by North American isolates of C. polykrikoides but not cysts formed by other common cyst-forming dinoflagellates. The method was then applied to identify and map C. polykrikoides cysts across bloom-prone estuaries. Annual cyst and vegetative cell surveys revealed that elevated densities of C. polykrikoides cysts (>100 cm−3) during the spring of a given year were spatially consistent with regions of dense blooms the prior summer. The identity of cysts in sediments was confirmed via independent amplification of C. polykrikoides rDNA. This study mapped C. polykrikoides cysts in a natural marine setting and indicates that the excystment of cysts formed by this harmful alga may play a key role in the development of HABs of this species. PMID:26637596

  18. Mapping the Distribution of Cysts from the Toxic Dinoflagellate Cochlodinium polykrikoides in Bloom-Prone Estuaries by a Novel Fluorescence In Situ Hybridization Assay.

    PubMed

    Hattenrath-Lehmann, Theresa K; Zhen, Yu; Wallace, Ryan B; Tang, Ying-Zhong; Gobler, Christopher J

    2015-01-01

    Cochlodinium polykrikoides is a cosmopolitan dinoflagellate that is notorious for causing fish-killing harmful algal blooms (HABs) across North America and Asia. While recent laboratory and ecosystem studies have definitively demonstrated that Cochlodinium forms resting cysts that may play a key role in the dynamics of its HABs, uncertainties regarding cyst morphology and detection have prohibited even a rudimentary understanding of the distribution of C. polykrikoides cysts in coastal ecosystems. Here, we report on the development of a fluorescence in situ hybridization (FISH) assay using oligonucleotide probes specific for the large subunit (LSU) ribosomal DNA (rDNA) of C. polykrikoides. The LSU rDNA-targeted FISH assay was used with epifluorescence microscopy and was iteratively refined to maximize the fluorescent reaction with C. polykrikoides and minimize cross-reactivity. The final LSU rDNA-targeted FISH assay was found to quantitatively recover cysts made by North American isolates of C. polykrikoides but not cysts formed by other common cyst-forming dinoflagellates. The method was then applied to identify and map C. polykrikoides cysts across bloom-prone estuaries. Annual cyst and vegetative cell surveys revealed that elevated densities of C. polykrikoides cysts (>100 cm(-3)) during the spring of a given year were spatially consistent with regions of dense blooms the prior summer. The identity of cysts in sediments was confirmed via independent amplification of C. polykrikoides rDNA. This study mapped C. polykrikoides cysts in a natural marine setting and indicates that the excystment of cysts formed by this harmful alga may play a key role in the development of HABs of this species. PMID:26637596

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

    PubMed

    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

  20. Toxicity testing with the marine algae, Symbiodinium kawagutii (Dinophyceae)

    SciTech Connect

    Gorrie, J.R.; Bidwell, J.R.; Rippingale, R.J.

    1994-12-31

    The dinoflagellate, Symbiodinium kawagutii, is among the algal taxa which exist in symbiosis with a range of marine invertebrates. S. kawagutii is commonly found in association with the Hawaiian stony coral, Montipora verrucosa. The algae has been successfully cultured in the laboratory using a common marine algal growth media (Guillard f/2), and sufficient cell densities were achieved in a 96-hr bioassay to allow statistical evaluation of toxicity data. A 96-hr EC{sub 50} of 6.47 mg/L (95% C.I.: 3.54--9.88 mg/L) was calculated after exposure to potassium dichromate. Wide distribution of the coral host and ecological importance of the symbiosis make S. kawagutii an excellent candidate species for hazard evaluation in tropical marine ecosystems. Continuing research will seek to further refine the bioassay, including the use of a microplate technique for more rapid testing.

  1. Marine pollution

    SciTech Connect

    Albaiges, J. )

    1989-01-01

    This book covers the following topics: Transport of marine pollutants; Transformation of pollutants in the marine environment; Biological effects of marine pollutants; Sources and transport of oil pollutants in the Persian Gulf; Trace metals and hydrocarbons in Syrian coastal waters; and Techniques for analysis of trace pollutants.

  2. Genetic Diversity and Distribution of the Ciguatera-Causing Dinoflagellate Gambierdiscus spp. (Dinophyceae) in Coastal Areas of Japan

    PubMed Central

    Nishimura, Tomohiro; Sato, Shinya; Tawong, Wittaya; Sakanari, Hiroshi; Uehara, Keita; Shah, Md Mahfuzur Rahman; Suda, Shoichiro; Yasumoto, Takeshi; Taira, Yohsuke; Yamaguchi, Haruo; Adachi, Masao

    2013-01-01

    Background 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. Methods/Principal Finding 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. Conclusions/Significance 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

  3. Fukuyoa paulensis gen. et sp. nov., a New Genus for the Globular Species of the Dinoflagellate Gambierdiscus (Dinophyceae)

    PubMed Central

    Gómez, Fernando; Qiu, Dajun; Lopes, Rubens M.; Lin, Senjie

    2015-01-01

    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. PMID:25831082

  4. Overwintering of the parasitic dinoflagellate Hematodinium perezi in dredged blue crabs (Callinectes sapidus) from Wachapreague Creek, Virginia.

    PubMed

    Shields, Jeffrey D; Sullivan, Shelley E; Small, Hamish J

    2015-09-01

    Parasitic dinoflagellates in the genus Hematodinium cause disease and mortality in several commercially important marine decapod crustaceans. One species, Hematodinium perezi, occurs in blue crabs, Callinectes sapidus, along the eastern seaboard and Gulf coast of the USA. The parasite infects blue crabs, other decapods, and amphipods in the high salinity waters of coastal bays. Epizootics of the parasite often reach prevalence levels of 75-80% during outbreaks with diseased crabs dying from the infection. Prevalence of the parasite is bimodal, with a minor peak in late spring or summer, and a major peak in fall, and declining rapidly to nearly zero in late November and December. The rapid decline in infections in the late fall brings up the question of whether the parasite overwinters in crabs or whether it uses an unidentified resting stage, such as a cyst. We report observations on the prevalence of the parasite from winter dredge surveys undertaken in 2011 and 2012. Crabs were examined via hemolymph smears, histology, and PCR diagnosis for the presence of H. perezi and other pathogens. Active infections were observed from January through March in 2011 and 2012, indicating the parasite can overwinter in blue crabs. However, several crabs that were positive by PCR had presumptive effete infections that were difficult to diagnose in histological slides and hemolymph smears. These infections did not appear to be active and may have been in subsidence. Dredged crabs with light and moderate active infections were held at 15°C to determine if the parasite was capable of rapid progression. In 8 cases, infections exhibited logarithmic growth progressing rapidly over 8-12days. We present evidence that overwintering of H. perezi occurs in the blue crab hosts, that infections are capable of responding rapidly to increases in temperatures, and that overwintering provides a reservoir of infected animals for transmission to occur in the spring. PMID:26232044

  5. Modelling dinoflagellates as an approach to the seasonal forecasting of bioluminescence in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Marcinko, Charlotte L. J.; Martin, Adrian P.; Allen, John T.

    2014-11-01

    Bioluminescence within ocean surface waters is of significant interest because it can enhance the study of subsurface movement and organisms. Little is known about how bioluminescence potential (BPOT) varies spatially and temporally in the open ocean. However, light emitted from dinoflagellates often dominates the stimulated bioluminescence field. As a first step towards forecasting surface ocean bioluminescence in the open ocean, a simple ecological model is developed which simulates seasonal changes in dinoflagellate abundance. How forecasting seasonal changes in BPOT may be achieved through combining such a model with relationships derived from observations is discussed and an example is given. The study illustrates a potential new approach to forecasting BPOT through explicitly modelling the population dynamics of a prolific bioluminescent phylum. The model developed here offers a promising platform for the future operational forecasting of the broad temporal changes in bioluminescence within the North Atlantic. Such forecasting of seasonal patterns could provide valuable information for the targeting of scientific field campaigns.

  6. Thirty years - Alexandrium fundyense cyst, bloom dynamics and shellfish toxicity in the Bay of Fundy, eastern Canada

    NASA Astrophysics Data System (ADS)

    Martin, Jennifer L.; LeGresley, Murielle M.; Hanke, Alex R.

    2014-05-01

    Sediment and water samples were collected for Alexandrium fundyense spatial and temporal distribution and abundance at more than 120 locations throughout the Bay of Fundy during the summers and winters of 1980-1984. These broad surveys have been repeated at various times through the past 30 years, with more regular sampling since 2004. In addition, A. fundyense abundance has been monitored at several locations within the Bay of Fundy at weekly intervals from April to November and monthly during the remaining months since 1988. Paralytic Shellfish Poisoning (PSP) toxins in shellfish (notably Mya arenaria) have also been monitored at multiple locations in the Bay of Fundy since 1943. The datasets were examined to determine relationships and roles between overwintering resting cysts, bloom initiation, bloom decline, motile cell dispersal and A. fundyense motile populations and resulting shellfish toxicity since 1980. Cysts are widely dispersed throughout the Bay of Fundy in the offshore, inshore and intertidal zones with the largest deposits located in the offshore in silt/clay sediments to the east and north of Grand Manan Island at depths of 60-180 m. Results show that there is a constant stable source of cysts in the Bay of Fundy with highest concentrations of cysts (9780 cysts cm-3) observed in 2010 and highest concentrations of A. fundyense motile cells (18×106 cells L-1) observed in 1980. Interannual changes in abundance in A. fundyense populations, resting cysts and the temporal trends in M. arenaria toxicity are discussed. Results show that there was no relationship between the abundance of overwintering cysts and the magnitude of A. fundyense blooms. The offshore seed beds appear to be relatively constant in cyst density among most years and serve as an important source for the motile cells that lead to initiation of major blooms and resulting shellfish toxicity throughout the Bay of Fundy.

  7. Historic 2005 toxic bloom of Alexandrium fundyense in the western Gulf of Maine: 2. Coupled biophysical numerical modeling

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

    A coupled physical/biological modeling system was used to hindcast a massive Alexandrium fundyense bloom that occurred in the western Gulf of Maine in 2005 and to investigate the relative importance of factors governing the bloom's initiation and development. The coupled system consists of a state-of-the-art, free-surface primitive equation Regional Ocean Modeling System (ROMS) tailored for the Gulf of Maine (GOM) using a multinested configuration, and a population dynamics model for A. fundyense. The system was forced by realistic momentum and buoyancy fluxes, tides, river runoff, observed A. fundyense benthic cyst abundance, and climatological nutrient fields. Extensive comparisons were made between simulated (both physical and biological) fields and in situ observations, revealing that the hindcast model is capable of reproducing the temporal evolution and spatial distribution of the 2005 bloom. Sensitivity experiments were then performed to distinguish the roles of three major factors hypothesized to contribute to the bloom: (1) the high abundance of cysts in western GOM sediments; (2) strong `northeaster' storms with prevailing downwelling-favorable winds; and (3) a large amount of fresh water input due to abundant rainfall and heavy snowmelt. Model results suggest the following. (1) The high abundance of cysts in western GOM was the primary factor of the 2005 bloom. (2) Wind-forcing was an important regulator, as episodic bursts of northeast winds caused onshore advection of offshore populations. These downwelling favorable winds accelerated the alongshore flow, resulting in transport of high cell concentrations into Massachusetts Bay. A large regional bloom would still have happened, however, even with normal or typical winds for that period. (3) Anomalously high river runoff in 2005 resulted in stronger buoyant plumes/currents, which facilitated the transport of cell population to the western GOM. While affecting nearshore cell abundance in Massachusetts

  8. Relationships between satellite-measured thermal features and Alexandrium-imposed toxicity in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Luerssen, Remy M.; Thomas, Andrew C.; Hurst, John

    2005-09-01

    Relationships between satellite-derived sea-surface temperature (SST) patterns and the occurrence of paralytic shellfish poisoning (PSP) toxicity events caused by Alexandrium fundyense in the western Gulf of Maine are examined. Comparisons between surface A. fundyense cell distribution patterns and SST images indicate that highest cell concentrations are associated with colder waters of the eastern segment of the Gulf of Maine coastal current (EMCC) and that frontal zones at the edges of the EMCC often act as boundaries to surface distributions. Surface thermal patterns coincident with a May 2000 PSP toxic event and shellfish harvesting closure on the western Maine coast show enhanced connectivity between the EMCC and the western Gulf of Maine, suggesting transport linking A. fundyense cells in the EMCC to inshore areas of the western Gulf of Maine. Surface drifter data support such transport. Thirteen years (1990-2002) of toxicity data from eight monitoring sites along the coast of Maine and concurrent SST data show that in years of either large or very reduced toxicity, a consistent relationship exists between the timing and strength of fronts, taken as an indicator of alongshore connectivity, and the occurrence and strength of toxic events. Years with weak fronts and/or fronts that become established relatively late in the summer growing season are years of the strongest toxicity events in western Gulf of Maine. Years of early and strong fronts are years with few and/or weak toxicity events. Our results suggest that advective connections exist between cells present in the EMCC and toxicity along the western Gulf of Maine coast and that large-scale hydrographic processes, characterized here as surface thermal patterns, influence A. fundyense populations in the western Gulf of Maine, either through delivery of actual cells or advection of advantageous conditions into the region. These data point to the utility of satellite and other coastal observing system data

  9. Subcellular localization of dinoflagellate polyketide synthases and fatty acid synthase activity.

    PubMed

    Van Dolah, Frances M; Zippay, Mackenzie L; Pezzolesi, Laura; Rein, Kathleen S; Johnson, Jillian G; Morey, Jeanine S; Wang, Zhihong; Pistocchi, Rossella

    2013-12-01

    Dinoflagellates are prolific producers of polyketide secondary metabolites. Dinoflagellate polyketide synthases (PKSs) have sequence similarity to Type I PKSs, megasynthases that encode all catalytic domains on a single polypeptide. However, in dinoflagellate PKSs identified to date, each catalytic domain resides on a separate transcript, suggesting multiprotein complexes similar to Type II PKSs. Here, we provide evidence through coimmunoprecipitation that single-domain ketosynthase and ketoreductase proteins interact, suggesting a predicted multiprotein complex. In Karenia brevis (C.C. Davis) Gert Hansen & Ø. Moestrup, previously observed chloroplast localization of PKSs suggested that brevetoxin biosynthesis may take place in the chloroplast. Here, we report that PKSs are present in both cytosol and chloroplast. Furthermore, brevetoxin is not present in isolated chloroplasts, raising the question of what chloroplast-localized PKS enzymes might be doing. Antibodies to K. brevis PKSs recognize cytosolic and chloroplast proteins in Ostreopsis cf. ovata Fukuyo, and Coolia monotis Meunier, which produce different suites of polyketide toxins, suggesting that these PKSs may share common pathways. Since PKSs are closely related to fatty acid synthases (FAS), we sought to determine if fatty acid biosynthesis colocalizes with either chloroplast or cytosolic PKSs. [(3) H]acetate labeling showed fatty acids are synthesized in the cytosol, with little incorporation in chloroplasts, consistent with a Type I FAS system. However, although 29 sequences in a K. brevis expressed sequence tag database have similarity (BLASTx e-value <10(-10) ) to PKSs, no transcripts for either Type I (cytosolic) or Type II (chloroplast) FAS are present. Further characterization of the FAS complexes may help to elucidate the functions of the PKS enzymes identified in dinoflagellates. PMID:27007632

  10. The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum retain functionally overlapping mitochondria from two evolutionarily distinct lineages

    PubMed Central

    Imanian, Behzad; Keeling, Patrick J

    2007-01-01

    Background The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum are distinguished by the presence of a tertiary plastid derived from a diatom endosymbiont. The diatom is fully integrated with the host cell cycle and is so altered in structure as to be difficult to recognize it as a diatom, and yet it retains a number of features normally lost in tertiary and secondary endosymbionts, most notably mitochondria. The dinoflagellate host is also reported to retain mitochondrion-like structures, making these cells unique in retaining two evolutionarily distinct mitochondria. This redundancy raises the question of whether the organelles share any functions in common or have distributed functions between them. Results We show that both host and endosymbiont mitochondrial genomes encode genes for electron transport proteins. We have characterized cytochrome c oxidase 1 (cox1), cytochrome oxidase 2 (cox2), cytochrome oxidase 3 (cox3), cytochrome b (cob), and large subunit of ribosomal RNA (LSUrRNA) of endosymbiont mitochondrial ancestry, and cox1 and cob of host mitochondrial ancestry. We show that all genes are transcribed and that those ascribed to the host mitochondrial genome are extensively edited at the RNA level, as expected for a dinoflagellate mitochondrion-encoded gene. We also found evidence for extensive recombination in the host mitochondrial genes and that recombination products are also transcribed, as expected for a dinoflagellate. Conclusion Durinskia baltica and K. foliaceum retain two mitochondria from evolutionarily distinct lineages, and the functions of these organelles are at least partially overlapping, since both express genes for proteins in electron transport. PMID:17892581

  11. Evaluating the Ribosomal Internal Transcribed Spacer (ITS) as a Candidate Dinoflagellate Barcode Marker

    PubMed Central

    Stern, Rowena F.; Andersen, Robert A.; Jameson, Ian; Küpper, Frithjof C.; Coffroth, Mary-Alice; Vaulot, Daniel; Le Gall, Florence; Véron, Benoît; Brand, Jerry J.; Skelton, Hayley; Kasai, Fumai; Lilly, Emily L.; Keeling, Patrick J.

    2012-01-01

    Background DNA barcoding offers an efficient way to determine species identification and to measure biodiversity. For dinoflagellates, an ancient alveolate group of about 2000 described extant species, DNA barcoding studies have revealed large amounts of unrecognized species diversity, most of which is not represented in culture collections. To date, two mitochondrial gene markers, Cytochrome Oxidase I (COI) and Cytochrome b oxidase (COB), have been used to assess DNA barcoding in dinoflagellates, and both failed to amplify all taxa and suffered from low resolution. Nevertheless, both genes yielded many examples of morphospecies showing cryptic speciation and morphologically distinct named species being genetically similar, highlighting the need for a common marker. For example, a large number of cultured Symbiodinium strains have neither taxonomic identification, nor a common measure of diversity that can be used to compare this genus to other dinoflagellates. Methodology/Principal Findings The purpose of this study was to evaluate the Internal Transcribed Spacer units 1 and 2 (ITS) of the rDNA operon, as a high resolution marker for distinguishing species dinoflagellates in culture. In our study, from 78 different species, the ITS barcode clearly differentiated species from genera and could identify 96% of strains to a known species or sub-genus grouping. 8.3% showed evidence of being cryptic species. A quarter of strains identified had no previous species identification. The greatest levels of hidden biodiversity came from Scrippsiella and the Pfiesteriaceae family, whilst Heterocapsa strains showed a high level of mismatch to their given species name. Conclusions/Significance The ITS marker was successful in confirming species, revealing hidden diversity in culture collections. This marker, however, may have limited use for environmental barcoding due to paralogues, the potential for unidentifiable chimaeras and priming across taxa. In these cases ITS would

  12. Characterization of a new chytrid species parasitic on the dinoflagellate, Peridinium gatunense.

    PubMed

    Leshem, Tamar; Letcher, Peter M; Powell, Martha J; Sukenik, Assaf

    2016-01-01

    Only a few chytrid fungi have been reported as parasites of dinoflagellates. Among these reports, chytrids are periodically observed growing on the dinoflagellate, Peridinium gatunense, in Lake Kinneret (Sea of Galilee), Israel. Because of the distinctive roles of parasitic chytrid fungi in decreasing phytoplankton populations and in transforming inedible algae into chytrid biomass which zooplankton grazers can eat, characterizing dinoflagellate parasites contributes to our understanding of the sustainability of this important water resource. An undescribed chytrid parasite of P. gatunense from Lake Kinneret has recently been brought into pure culture (KLL_TL-060613), facilitating exploration of its infection process. To evaluate the ability of this chytrid to affect host populations, we determined the effect of: (1) temperature and light (or dark) on prevalence of infection and (2) host growth phase and parasite:host ratio on percentage of infection. The greatest amplification in host infection occurred in cultures grown in the dark at 25 C. The percentage of host cells infected increased as the availability of host cells compared to parasite cells increased. These results demonstrate that environmental factors influence the chytrid's potential to affect Peridinium gatunense populations. Because this chytrid had not been described taxonomically, we characterized its thallus morphology, development, zoospore ultrastructure and phylogenetic relationships. Zoospore ultrastructure was compatible with the Group II type zoospore characteristic of the family Chytridiaceae in the Chytridiales. Consistent with this observation, phylogenetic analyses of nuc 28S rDNA D1-D3 domains (28S) placed the chytrid in a clade among described taxa in the Chytridiaceae. Because thallus morphology was distinct from these other taxa, as well as other described parasites of dinoflagellates, this chytrid is described as a new genus and species, Dinochytrium kinnereticum. PMID:27582565

  13. Detection of dinoflagellates by the light scattering properties of the chiral structure of their chromosomes

    NASA Astrophysics Data System (ADS)

    Liu, Jianping; Kattawar, George W.

    2013-12-01

    One of the most prominent properties of dinoflagellates is their large sized and highly chromosome-laden nucleus, which contains dozens of cylindrically shaped chromosomes. With such high chromatic concentration, these chromosomes condense into ordered helical structures and were claimed to be responsible for the large circular polarization effects observed in the light scattering from dinoflagellates. In previous research, a thin helix model of a chromosome was used to compare the Discrete Dipole Approximation (DDA) and the analytical Born approximation calculations. However, for such a simplified model only modest qualitative agreements with experimental measurements were achieved. Moreover, only one chromosome in one nucleus was simulated, overlooking the effects of interactions between chromosomes. In this work, we adopt the helical plywood liquid crystal model with a capsule shape, in which parallel fibrils lie in plains perpendicular to the helix axis and the orientations of these fibrils twist at a constant angle between two neighboring layers. The ADDA code is applied to calculate the 16 Mueller matrix elements of light scattering from a single chromosome and from the nucleus, which is composed of a collection of randomly positioned and randomly orientated chromosomes. Special attention is paid to the S14 Mueller matrix element, which describes the ability of differentiating left and right circularly polarized light. Our results show that large S14 back scattering signals from the dinoflagellate nucleus results from the underlying helical structures of its chromosomes. These signals are sensitive to the light wavelength and pitch of the chromatic helix, the latter of which is species specific. Therefore, detecting back scattering S14 signal could be a promising method to monitor dinoflagellates such as Karenia brevis, the causal agent of the Florida red tide.

  14. Associated bacterial flora, growth, and toxicity of cultured benthic dinoflagellates Ostreopsis lenticularis and Gambierdiscus toxicus.

    PubMed

    Tosteson, T R; Ballantine, D L; Tosteson, C G; Hensley, V; Bardales, A T

    1989-01-01

    The growth, toxicity, and associated bacterial flora of 10 clonal cultures of the toxic benthic dinoflagellates Ostreopsis lenticularis and Gambierdiscus toxicus isolated from the coastal waters of southwest Puerto Rico have been examined. Clonal cultures of O. lenticularis grew more rapidly and at broader temperature ranges than those of G. toxicus. All five Ostreopsis clones were toxic, while only one of the five Gambierdiscus clones was poisonous. The degree of toxicity among poisonous clones was highly variable. The number of associated bacterial genera and their frequency of occurrence were quite variable among clones of both dinoflagellate genera. Bacterial isolates represented six genera (Nocardia, Pseudomonas, Vibrio, Aeromonas, Flavobacterium, and Moraxella) in addition to coryneform bacteria. Extracts of dinoflagellate-associated bacteria grown in pure culture were not toxic. Gambierdiscus clones were characterized by the frequent presence of Pseudomonas spp. (four of five clones) and the absence of coryneforms. In O. lenticularis, only one of five clones showed the presence of Pseudomonas spp., and Moraxella sp. was absent altogether. Detailed analyses of toxicity and associated microflora in a selected Ostreopsis clone, repeatedly cultivated (four times) over a period of 160 days, showed that peak cell toxicities developed in the late static and early negative culture growth phases. Peak Ostreopsis cell toxicities in the stationary phase of culture growth were correlated with significant increases in the percent total bacteria directly associated with these cells. Changes in the quantity of bacteria directly associated with microalgal cell surfaces and extracellular matrices during culture growth may be related to variability and degree of toxicity in these laboratory-cultured benthic dinoflagellates. PMID:2705766

  15. Genome Fragmentation Is Not Confined to the Peridinin Plastid in Dinoflagellates

    PubMed Central

    Espelund, Mari; Minge, Marianne A.; Gabrielsen, Tove M.; Nederbragt, Alexander J.; Shalchian-Tabrizi, Kamran; Otis, Christian; Turmel, Monique; Lemieux, Claude; Jakobsen, Kjetill S.

    2012-01-01

    When plastids are transferred between eukaryote lineages through series of endosymbiosis, their environment changes dramatically. Comparison of dinoflagellate plastids that originated from different algal groups has revealed convergent evolution, suggesting that the host environment mainly influences the evolution of the newly acquired organelle. Recently the genome from the anomalously pigmented dinoflagellate Karlodinium veneficum plastid was uncovered as a conventional chromosome. To determine if this haptophyte-derived plastid contains additional chromosomal fragments that resemble the mini-circles of the peridin-containing plastids, we have investigated its genome by in-depth sequencing using 454 pyrosequencing technology, PCR and clone library analysis. Sequence analyses show several genes with significantly higher copy numbers than present in the chromosome. These genes are most likely extrachromosomal fragments, and the ones with highest copy numbers include genes encoding the chaperone DnaK(Hsp70), the rubisco large subunit (rbcL), and two tRNAs (trnE and trnM). In addition, some photosystem genes such as psaB, psaA, psbB and psbD are overrepresented. Most of the dnaK and rbcL sequences are found as shortened or fragmented gene sequences, typically missing the 3′-terminal portion. Both dnaK and rbcL are associated with a common sequence element consisting of about 120 bp of highly conserved AT-rich sequence followed by a trnE gene, possibly serving as a control region. Decatenation assays and Southern blot analysis indicate that the extrachromosomal plastid sequences do not have the same organization or lengths as the minicircles of the peridinin dinoflagellates. The fragmentation of the haptophyte-derived plastid genome K. veneficum suggests that it is likely a sign of a host-driven process shaping the plastid genomes of dinoflagellates. PMID:22719952

  16. Genome fragmentation is not confined to the peridinin plastid in dinoflagellates.

    PubMed

    Espelund, Mari; Minge, Marianne A; Gabrielsen, Tove M; Nederbragt, Alexander J; Shalchian-Tabrizi, Kamran; Otis, Christian; Turmel, Monique; Lemieux, Claude; Jakobsen, Kjetill S

    2012-01-01

    When plastids are transferred between eukaryote lineages through series of endosymbiosis, their environment changes dramatically. Comparison of dinoflagellate plastids that originated from different algal groups has revealed convergent evolution, suggesting that the host environment mainly influences the evolution of the newly acquired organelle. Recently the genome from the anomalously pigmented dinoflagellate Karlodinium veneficum plastid was uncovered as a conventional chromosome. To determine if this haptophyte-derived plastid contains additional chromosomal fragments that resemble the mini-circles of the peridin-containing plastids, we have investigated its genome by in-depth sequencing using 454 pyrosequencing technology, PCR and clone library analysis. Sequence analyses show several genes with significantly higher copy numbers than present in the chromosome. These genes are most likely extrachromosomal fragments, and the ones with highest copy numbers include genes encoding the chaperone DnaK(Hsp70), the rubisco large subunit (rbcL), and two tRNAs (trnE and trnM). In addition, some photosystem genes such as psaB, psaA, psbB and psbD are overrepresented. Most of the dnaK and rbcL sequences are found as shortened or fragmented gene sequences, typically missing the 3'-terminal portion. Both dnaK and rbcL are associated with a common sequence element consisting of about 120 bp of highly conserved AT-rich sequence followed by a trnE gene, possibly serving as a control region. Decatenation assays and Southern blot analysis indicate that the extrachromosomal plastid sequences do not have the same organization or lengths as the minicircles of the peridinin dinoflagellates. The fragmentation of the haptophyte-derived plastid genome K. veneficum suggests that it is likely a sign of a host-driven process shaping the plastid genomes of dinoflagellates. PMID:22719952

  17. Damage to photosystem II in symbiotic dinoflagellates: A determinant of coral bleaching

    PubMed Central

    Warner, Mark E.; Fitt, William K.; Schmidt, Gregory W.

    1999-01-01

    Coral bleaching has been defined as a general phenomenon, whereby reef corals turn visibly pale because of the loss of their symbiotic dinoflagellates and/or algal pigments during periods of exposure to elevated seawater temperatures. During the summer of 1997, seawater temperatures in the Florida Keys remained at or above 30°C for more than 6 weeks, and extensive coral bleaching was observed. Bleached colonies of the dominant Caribbean reef-building species, Montastrea faveolata and Montastrea franksi, were sampled over a depth gradient from 1 to 17 m during this period of elevated temperature and contained lower densities of symbiotic dinoflagellates in deeper corals than seen in previous “nonbleaching” years. Fluorescence analysis by pulse-amplitude modulation fluorometry revealed severe damage to photosystem II (PSII) in remaining symbionts within the corals, with greater damage indicated at deeper depths. Dinoflagellates with the greatest loss in PSII activity also showed a significant decline in the D1 reaction center protein of PSII, as measured by immunoblot analysis. Laboratory experiments on the temperature-sensitive species Montastrea annularis, as well as temperature-sensitive and temperature-tolerant cultured symbiotic dinoflagellates, confirmed the temperature-dependent loss of PSII activity and concomitant decrease in D1 reaction center protein seen in symbionts collected from corals naturally bleached on the reef. In addition, variation in PSII repair was detected, indicating that perturbation of PSII protein turnover rates during photoinhibition at elevated temperatures underlies the physiological collapse of symbionts in corals susceptible to heat-induced bleaching. PMID:10393938

  18. Metabolic pathway redundancy within the apicomplexan-dinoflagellate radiation argues against an ancient chromalveolate plastid.

    PubMed

    Waller, Ross F; Gornik, Sebastian G; Koreny, Ludek; Pain, Arnab

    2016-01-01

    The chromalveolate hypothesis presents an attractively simple explanation for the presence of red algal-derived secondary plastids in 5 major eukaryotic lineages: "chromista" phyla, cryptophytes, haptophytes and ochrophytes; and alveolate phyla, dinoflagellates and apicomplexans. It posits that a single secondary endosymbiotic event occurred in a common ancestor of these diverse groups, and that this ancient plastid has since been maintained by vertical inheritance only. Substantial testing of this hypothesis by molecular phylogenies has, however, consistently failed to provide support for the predicted monophyly of the host organisms that harbour these plastids-the "chromalveolates." This lack of support does not disprove the chromalveolate hypothesis per se, but rather drives the proposed endosymbiosis deeper into the eukaryotic tree, and requires multiple plastid losses to have occurred within intervening aplastidic lineages. An alternative perspective on plastid evolution is offered by considering the metabolic partnership between the endosymbiont and its host cell. A recent analysis of metabolic pathways in a deep-branching dinoflagellate indicates a high level of pathway redundancy in the common ancestor of apicomplexans and dinoflagellates, and differential losses of these pathways soon after radiation of the major extant lineages. This suggests that vertical inheritance of an ancient plastid in alveolates is highly unlikely as it would necessitate maintenance of redundant pathways over very long evolutionary timescales. PMID:27066182

  19. A genomic approach to coral-dinoflagellate symbiosis: studies of Acropora digitifera and Symbiodinium minutum

    PubMed Central

    Shinzato, Chuya; Mungpakdee, Sutada; Satoh, Nori; Shoguchi, Eiichi

    2014-01-01

    Far more intimate knowledge of scleractinian coral biology is essential in order to understand how diverse coral-symbiont endosymbioses have been established. In particular, molecular and cellular mechanisms enabling the establishment and maintenance of obligate endosymbiosis with photosynthetic dinoflagellates require further clarification. By extension, such understanding may also shed light upon environmental conditions that promote the collapse of this mutualism. Genomic data undergird studies of all symbiotic processes. Here we review recent genomic data derived from the scleractinian coral, Acropora digitifera, and the endosymbiotic dinoflagellate, Symbiodinium minutum. We discuss Acropora genes involved in calcification, embryonic development, innate immunity, apoptosis, autophagy, UV resistance, fluorescence, photoreceptors, circadian clocks, etc. We also detail gene loss in amino acid metabolism that may explain at least part of the Acropora stress-response. Characteristic features of the Symbiodinium genome are also reviewed, focusing on the expansion of certain gene families, the molecular basis for permanently condensed chromatin, unique spliceosomal splicing, and unusual gene arrangement. Salient features of the Symbiodinium plastid and mitochondrial genomes are also illuminated. Although many questions regarding these interdependent genomes remain, we summarize information necessary for future studies of coral-dinoflagellate endosymbiosis. PMID:25071748

  20. Climate anomalies generate an exceptional dinoflagellate bloom in San Francisco Bay

    USGS Publications Warehouse

    Cloern, J.E.; Schraga, T.S.; Lopez, C.B.; Knowles, N.; Grover, Labiosa R.; Dugdale, R.

    2005-01-01

    We describe a large dinoflagellate bloom, unprecedented in nearly three decades of observation, that developed in San Francisco Bay (SFB) during September 2004. SFB is highly enriched in nutrients but has low summer-autumn algal biomass because wind stress and tidally induced bottom stress produce a well mixed and light-limited pelagic habitat. The bloom coincided with calm winds and record high air temperatures that stratified the water column and suppressed mixing long enough for motile dinoflagellates to grow and accumulate in surface waters. This event-scale climate pattern, produced by an upper-atmosphere high-pressure anomaly off the U.S. west coast, followed a summer of weak coastal upwelling and high dinoflagellate biomass in coastal waters that apparently seeded the SFB bloom. This event suggests that some red tides are responses to changes in local physical dynamics that are driven by large-scale atmospheric processes and operate over both the event scale of biomass growth and the antecedent seasonal scale that shapes the bloom community. Copyright 2005 by the American Geophysical Union.

  1. Phosphorus Deficiency Inhibits Cell Division But Not Growth in the Dinoflagellate Amphidinium carterae.

    PubMed

    Li, Meizhen; Shi, Xinguo; Guo, Chentao; Lin, Senjie

    2016-01-01

    Phosphorus (P) is an essential nutrient element for the growth of phytoplankton. How P deficiency affects population growth and the cell division cycle in dinoflagellates has only been studied in some species, and how it affects photosynthesis and cell growth remains poorly understood. In the present study, we investigated the impact of P deficiency on the cell division cycle, the abundance of the carbon-fixing enzyme Rubisco, and other cellular characteristics in the Gymnodiniales peridinin-plastid species Amphidinium carterae. We found that under P-replete condition, the cell cycle actively progressed in the culture in a 24-h diel cycle with daily growth rates markedly higher than the P-deficient cultures, in which cells were arrested in the G1 phase and cell size significantly enlarged. The results suggest that, as in previously studied dinoflagellates, P deficiency likely disenables A. carterae to complete DNA duplication or check-point protein phosphorylation. We further found that under P-deficient condition, overall photosystem II quantum efficiency (Fv/Fm ratio) and Rubisco abundance decreased but not significantly, while cellular contents of carbon, nitrogen, and proteins increased significantly. These observations indicated that under P-deficiency, this dinoflagellate was able to continue photosynthesis and carbon fixation, such that proteins and photosynthetically fixed carbon could accumulate resulting in continued cell growth in the absence of division. This is likely an adaptive strategy thereby P-limited cells can be ready to resume the cell division cycle upon resupply of phosphorus. PMID:27313570

  2. Dinoflagellate Gene Structure and Intron Splice Sites in a Genomic Tandem Array.

    PubMed

    Mendez, Gregory S; Delwiche, Charles F; Apt, Kirk E; Lippmeier, J Casey

    2015-01-01

    Dinoflagellates are one of the last major lineages of eukaryotes for which little is known about genome structure and organization. We report here the sequence and gene structure of a clone isolated from a cosmid library which, to our knowledge, represents the largest contiguously sequenced, dinoflagellate genomic, tandem gene array. These data, combined with information from a large transcriptomic library, allowed a high level of confidence of every base pair call. This degree of confidence is not possible with PCR-based contigs. The sequence contains an intron-rich set of five highly expressed gene repeats arranged in tandem. One of the tandem repeat gene members contains an intron 26,372 bp long. This study characterizes a splice site consensus sequence for dinoflagellate introns. Two to nine base pairs around the 3' splice site are repeated by an identical two to nine base pairs around the 5' splice site. The 5' and 3' splice sites are in the same locations within each repeat so that the repeat is found only once in the mature mRNA. This identically repeated intron boundary sequence might be useful in gene modeling and annotation of genomes. PMID:25963315

  3. The synthesis of mycosporine-like amino acids (MAAs) by cultured, symbiotic dinoflagellates.

    PubMed

    T Banaszak1 A; LaJeunesse; Trench

    2000-06-28

    We tested the hypothesis that there is a relation between phylotypes (phylogenetic types, as determined by restriction fragment length polymorphism (RFLP) and partial sequence analysis of the small subunit ribosomal RNA gene (SSUrDNA)) and the synthesis of mycosporine-like amino acids (MAAs) by symbiotic dinoflagellates under the influence of ultraviolet radiation (UV-B/A) and photosynthetically active radiation (PAR). We exposed 27 isolates of symbiotic dinoflagellates simultaneously to UV-B/A and PAR, and subsequently determined the MAAs present in cell extracts and in the media. The algae used included 24 isolates of Symbiodinium spp. originating from jellyfishes, sea anemones, zoanthids, scleractinians, octocorals, and bivalves, and three others in the genera Gymnodinium, Gloeodinium and Amphidinium from a jellyfish, an hydrocoral and a flatworm, respectively. In this study, all of the phylotype A Symbiodinium spp. synthesized up to three identified MAAs. None of the 11 cultured phylotypes B and C Symbiodinium spp. synthesized MAAs. The three non-Symbiodinium symbionts also synthesized up to three MAAs. The results support a conclusion that phylotype A Symbiodinium spp. have a high predilection for the synthesis of MAAs, while phylotypes B and C do not. Synthesis of MAAs by symbiotic dinoflagellates in culture does not appear to relate directly to depths or to the UV exposure regimes from which the consortia were collected. PMID:10841936

  4. Phosphorus Deficiency Inhibits Cell Division But Not Growth in the Dinoflagellate Amphidinium carterae

    PubMed Central

    Li, Meizhen; Shi, Xinguo; Guo, Chentao; Lin, Senjie

    2016-01-01

    Phosphorus (P) is an essential nutrient element for the growth of phytoplankton. How P deficiency affects population growth and the cell division cycle in dinoflagellates has only been studied in some species, and how it affects photosynthesis and cell growth remains poorly understood. In the present study, we investigated the impact of P deficiency on the cell division cycle, the abundance of the carbon-fixing enzyme Rubisco, and other cellular characteristics in the Gymnodiniales peridinin-plastid species Amphidinium carterae. We found that under P-replete condition, the cell cycle actively progressed in the culture in a 24-h diel cycle with daily growth rates markedly higher than the P-deficient cultures, in which cells were arrested in the G1 phase and cell size significantly enlarged. The results suggest that, as in previously studied dinoflagellates, P deficiency likely disenables A. carterae to complete DNA duplication or check-point protein phosphorylation. We further found that under P-deficient condition, overall photosystem II quantum efficiency (Fv/Fm ratio) and Rubisco abundance decreased but not significantly, while cellular contents of carbon, nitrogen, and proteins increased significantly. These observations indicated that under P-deficiency, this dinoflagellate was able to continue photosynthesis and carbon fixation, such that proteins and photosynthetically fixed carbon could accumulate resulting in continued cell growth in the absence of division. This is likely an adaptive strategy thereby P-limited cells can be ready to resume the cell division cycle upon resupply of phosphorus. PMID:27313570

  5. Morphology and behaviour of dinoflagellate chromosomes during the cell cycle and mitosis.

    PubMed

    Bhaud, Y; Guillebault, D; Lennon, J; Defacque, H; Soyer-Gobillard, M O; Moreau, H

    2000-04-01

    The morphology and behaviour of the chromosomes of dinoflagellates during the cell cycle appear to be unique among eukaryotes. We used synchronized and aphidicolin-blocked cultures of the dinoflagellate Crypthecodinium cohnii to describe the successive morphological changes that chromosomes undergo during the cell cycle. The chromosomes in early G(1) phase appeared to be loosely condensed with numerous structures protruding toward the nucleoplasm. They condensed in late G(1), before unwinding in S phase. The chromosomes in cells in G(2) phase were tightly condensed and had a double number of arches, as visualised by electron microscopy. During prophase, chromosomes elongated and split longitudinally, into characteristic V or Y shapes. We also used confocal microscopy to show a metaphase-like alignment of the chromosomes, which has never been described in dinoflagellates. The metaphase-like nucleus appeared flattened and enlarged, and continued to do so into anaphase. Chromosome segregation occurred via binding to the nuclear envelope surrounding the cytoplasmic channels and microtubule bundles. Our findings are summarized in a model of chromosome behaviour during the cell cycle. PMID:10704374

  6. Culturable and nonculturable bacterial symbionts in the toxic benthic dinoflagellate Ostreopsis lenticularis.

    PubMed

    Ashton, Mayra; Rosado, William; Govind, Nadathur S; Tosteson, Thomas R

    2003-09-15

    The toxic benthic dinoflagellate Ostreopsis lenticularis hosts a variety of symbiont bacterial flora. Laboratory cultured Ostreopsis clones require the presence of symbiotic Pseudomonas/Alteromonas bacterial strains for growth and toxicity development. Three culturable bacterial strains associated with Ostreopsis were identified as Pseudomonas/Alteromonas strain 1, Pseudomonas/Alteromonas strain 2 and Acinetobacter. Denaturing gradient gel electrophoresis (DGGE) analyses of extracted Ostreopsis associated bacterial DNAs indicated that there were three culturable and four non-culturable associated bacterial strains. The results presented here are the first report of the presence of unculturable bacterial symbionts in a toxic benthic dinoflagellate. Ostreopsis lost toxicity when exposed to elevated temperatures in the field and laboratory culture and subsequently recovered toxicity at reduced temperatures. Ostreopsis associated culturable Pseudomonas/Alteromonas bacterial strains were significantly reduced in dinoflagellate cultures exposed to elevated temperatures. The decreased toxicity of O. lenticularis exposed to elevated temperatures and their subsequent recovery of toxicity in periods of reduced thermal stress may have resulted from the effects of elevated temperature on the spectrum of culturable and unculturable bacterial species interacting with their Ostreopsis host. PMID:14505943

  7. Metabolic pathway redundancy within the apicomplexan-dinoflagellate radiation argues against an ancient chromalveolate plastid

    PubMed Central

    Waller, Ross F.; Gornik, Sebastian G.; Koreny, Ludek; Pain, Arnab

    2016-01-01

    ABSTRACT The chromalveolate hypothesis presents an attractively simple explanation for the presence of red algal-derived secondary plastids in 5 major eukaryotic lineages: “chromista” phyla, cryptophytes, haptophytes and ochrophytes; and alveolate phyla, dinoflagellates and apicomplexans. It posits that a single secondary endosymbiotic event occurred in a common ancestor of these diverse groups, and that this ancient plastid has since been maintained by vertical inheritance only. Substantial testing of this hypothesis by molecular phylogenies has, however, consistently failed to provide support for the predicted monophyly of the host organisms that harbour these plastids—the “chromalveolates.” This lack of support does not disprove the chromalveolate hypothesis per se, but rather drives the proposed endosymbiosis deeper into the eukaryotic tree, and requires multiple plastid losses to have occurred within intervening aplastidic lineages. An alternative perspective on plastid evolution is offered by considering the metabolic partnership between the endosymbiont and its host cell. A recent analysis of metabolic pathways in a deep-branching dinoflagellate indicates a high level of pathway redundancy in the common ancestor of apicomplexans and dinoflagellates, and differential losses of these pathways soon after radiation of the major extant lineages. This suggests that vertical inheritance of an ancient plastid in alveolates is highly unlikely as it would necessitate maintenance of redundant pathways over very long evolutionary timescales. PMID:27066182

  8. Genome of the marine alphaproteobacterium Hoeflea phototrophica type strain (DFL-43T)

    PubMed Central

    Fiebig, Anne; Pradella, Silke; Petersen, Jörn; Michael, Victoria; Päuker, Orsola; Rohde, Manfred; Göker, Markus; Klenk, Hans-Peter; Wagner-Döbler, Irene

    2013-01-01

    Hoeflea phototrophica Biebl et al. 2006 is a member of the family Phyllobacteriaceae in the order Rhizobiales, which is thus far only partially characterized at the genome level. This marine bacterium contains the photosynthesis reaction-center genes pufL and pufM and is of interest because it lives in close association with toxic dinoflagellates such as Prorocentrum lima. The 4,467,792 bp genome (permanent draft sequence) with its 4,296 protein-coding and 69 RNA genes is a part of the Marine Microbial Initiative. PMID:24019991

  9. In situ observation of harmful dinoflagellate bloom in the eastern coast of Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hisashi; Murakami, Hirishi; Miyamura, Kazuyoshi; Siawanto, Eko; Kobayashi, Hiroshi; Ishizaka, Joji

    2014-05-01

    Oita coast, where is in the eastern coast of Kyushu, Japan, is a richly fish aquaculture area. However, sometimes harmful algal blooms occur in this region, especially harmful dinoflagellates blooms, and cultured fish mortality occurs. Ocean color remote sensing is expected as a useful tool to reduce the financial damage of harmful algal blooms. However, ocean color data is low accuracy in the coastal region because colored dissolved organic matter and suspended solid are dominant. More optical data of harmful algal blooms are required because there are few data in harmful algal blooms. The field observation was conducted to understand the inherent optical property of harmful dinoflagellate bloom in the eastern coast of Oita prefecture on April and August 2013. Chlorophyll-a maximum (>24 mg m^-3) was observed in the subsurface layer on April 2013. The dominant phytoplankton species in this chlorophyll-a maximum layer was dinoflagellate Cochlodinium polykrikoides (>300 cells ml^-1) and early stage of the bloom was formed. Peak of the remote sensing reflectance was near 565nm due to strong phytoplankton absorption within 400 ~ 500 nm domain from the subsurface bloom layer. Moreover, high phytoplankton absorption coefficient was observed at the shorter wavelength (< 400nm). This strong absorption might be due to mycosporine-like amino acids, which absorb the UV (Kahru and Mitchell, 1998). And this subsurface C. polykrikoides bloom was detected by using dinoflagellate bloom detection algorithm, which is a simpler new satellite remote sensing-based harmful algal blooms detection method for JAXA's GCOM-C/SGLI (Siswanto et al., 2013). However, detection of the dinoflagellate Karenia mikimotoi bloom by using the algorithm on August 2013 was difficult as colored dissolved organic matter and detritus absorptions were high. Although the algorithm could detect the early stage of C. polycrikoides bloom, the algorithm improvement to detect the harmful algal blooms in the case II

  10. Petroleum effects on neural systems in marine organisms. Progress report, 1 August 1979-14 April 1980

    SciTech Connect

    Not Available

    1980-01-01

    Progress is reported in the following areas: (1) petroleum effects on chemosensory systems in the kelp crab, Pugettia producta, and the California spiny lobster, Panulirus interruptus; (2) chemosensory bradycardia in the spiny lobster; (3) petroleum effects on epithelial potentials in the coelenterate Tubularia; (4) petroleum effects on bioluminescence in the marine dinoflagellate, Pyrocystis fusiformis; and (5) analysis of petroleum for neurological testing on crustacea. (ACR)

  11. Glacial-Interglacial, Orbital and Millennial-Scale Climate Variability for the Last Glacial Cycle at Shackleton Site U1385 based on Dinoflagellate Cysts

    NASA Astrophysics Data System (ADS)

    Datema, M.

    2015-12-01

    The Shackleton Site (IODP Expedition 339 Site U1385), located off the West-Portuguese Margin, preserves a continuous high-fidelity record of millennial-scale climate variability for the last several glacial cycles (~1.4 Myr) that can be correlated precisely to patterns observed in polar ice cores. In addition, rapid delivery of terrestrial material to the deep-sea environment allows the correlation of these marine records to European terrestrial climate records. This unique marine-ice-terrestrial linkage makes the Shackleton Site the ideal reference section for studying Quaternary abrupt climate change. The main objective of studying Site U1385 is to establish a marine reference section of Pleistocene climate change. We generated (sub)millennial-scale (~600 year interval) dinoflagellate cyst (dinocyst) assemblage records from Shackleton Site U1385 (IODP Expedition 339) to reconstruct sea surface temperature (SST) and productivity/upwelling over the last 152 kyrs. In addition, our approach allows for detailed land-sea correlations, because we also counted assemblages of pollen and spores from higher plants. Dinocyst SST and upwelling proxies, as well as warm/cold pollen proxies from Site U1385 show glacial-interglacial, orbital and stadial-interstadial climate variability and correlate very well to Uk'37, planktic foraminifer δ18O and Ca/Ti proxies of previously drilled Shackleton Sites and Greenland Ice Core δ18O. The palynological proxies capture (almost) all Dansgaard-Oeschger events of the last glacial cycle, also before ~70 ka, where millennial-scale variability is overprinted by precession. We compare the performance and results of the palynology of Site U1385 to proxies of previously drilled Shackleton Sites and conclude that palynology strengthens the potential of this site to form a multi-proxy reference section for millennial scale climate variability across the Pleistocene-Holocene. Finally, we will present a long-term paleoceanographic perspective down

  12. Marine biology

    SciTech Connect

    Thurman, H.V.; Webber, H.H.

    1984-01-01

    This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index.

  13. Characteristics of phytoplankton community structure during and after a bloom of the dinoflagellate Scrippsiella trochoidea by HPLC pigment analysis

    NASA Astrophysics Data System (ADS)

    Wong, Chun-Kwan; Wong, Chong-Kim

    2009-06-01

    A bloom of the dinoflagellate Scrippsiella trochoidea was detected for the first time in inner Tolo Harbor, Hong Kong in 2 000. Water samples were collected at eight stations along a transect passing through a red tide patch for microscopic analysis of phytoplankton composition and high-performance liquid chromatography (HPLC) analysis of phytoplankton pigments. During the bloom, the density of dinoflagellates was 1.1×106 cells L-1 within the patch and 8.6×105 cells L-1 outside the patch where the phytoplankton community was dominated by diatoms. After the bloom the S. trochoidea began to decrease in density and was replaced by diatoms as the dominating bloom-causing organisms at all stations, and the density of dinoflagellates at most stations was less than 1.0 × 106 cells L-1. The status of S. trochoidea as the causative species of the bloom was indicated by the presence of peridinin, the marker pigment for dinoflagellates. The shift from dinoflagellates to diatoms was marked by the decline of peridinin and the prevalence of fucoxanthin. Phytoplankton pigment markers also revealed the presence of other minor phytoplankton assemblages such as cryptomonads and blue-green algal.

  14. Marine Biomedicine

    ERIC Educational Resources Information Center

    Bang, Frederik B.

    1977-01-01

    Describes early scientific research involving marine invertebrate pathologic processes that may have led to new insights into human disease. Discussed are inquiries of Metchnikoff, Loeb, and Cantacuzene (immunolgic responses in sea stars, horseshoe crabs, and marine worms, respectively). Describes current research stemming from these early…

  15. Marine Biology

    ERIC Educational Resources Information Center

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  16. Marine intervals in Neogene fluvial deposits of western Amazonia

    NASA Astrophysics Data System (ADS)

    Boonstra, Melanie; Troelstra, Simon; Lammertsma, Emmy; Hoorn, Carina

    2014-05-01

    Amazonia is one of the most species rich areas on Earth, but this high diversity is not homogeneous over the entire region. Highest mammal and tree-alpha diversity is found in the fluvio-lacustrine Pebas system, a Neogene wetland associated with rapid radiation of species. The estuarine to marine origin of various modern Amazonian fish, plants, and invertebrates has been associated with past marine ingressions into this freshwater Pebas system. The exact nature and age of these invasions is, however, debated. Here we present new evidence from fluvial and fluvio-lacustrine deposits of Neogene age in southeast Colombia, that point to periods of widespread marine conditions in western Amazonia. Our evidence is based on an analysis of marine palynomorphs, such as organic linings of foraminifera and dinoflagellate cysts, present in dark sandy clay sediments that outcrop along the Caqueta and Amazon rivers. Characteristically, the foraminiferal linings can be assigned to three benthic morphotypes only, e.g. Ammonia, Elphidium and Trochammina. This low diversity assemblage is associated with estuarine/marginal marine conditions. No distinct marine elements such as shelf or planktonic species were encountered. The observed foraminiferal linings and dinocyst assemblages are typical for a (eutrophic) shallow marine environment, suggesting that the Pebas freshwater wetland system occasionally changed to (marginal) marine. Although some reworked elements are found, a typical Neogene dinocyst taxon is commonly found supporting in situ deposition. Sedimentological features typical for tidal conditions that are reported for sites in Peru and northeastern Brazil likely relate to these marine ingressions. Sea level changes as well as foreland basin development related to Andes formation may have facilitated the entry of marine water during the Neogene.

  17. Amoebophrya spp. from the bloom-forming dinoflagellate Cochlodinium polykrikoides: parasites not nested in the "Amoebophrya ceratii complex".

    PubMed

    Kim, Sunju; Park, Myung Gil

    2014-01-01

    Members of Amoebophrya ceratii complex are known to infect a number of free-living dinoflagellates including harmful algal bloom species. In August and October 2012, Amoebophrya infections during two bloom events of the dinoflagellate Cochlodinium polykrikoides were observed along southern coastal waters of Korea. Microscopic observations and molecular data revealed that two different Amoebophrya parasites infected the same host species. In addition, while one developed in the host's nucleus, the other in the host's cytoplasm. Phylogenetic analyses showed that the two parasites were not nested in the previously recognized "Amoebophrya ceratii complex clade", which contained sequences of parasites infecting numerous dinoflagellate species. Instead, they branched as sister taxa to the isolate (possibly Amoebophrya) from radiolarians Hexacontium gigantheum. Our result indicates that the two Amoebophrya parasites infecting C. polykrikoides may be different species from those inside the "complex." PMID:24612333

  18. Unarmoured dinoflagellates with a small hyposome: Torodinium and Lebouridinium gen. nov. for Katodinium glaucum (Gymnodiniales, Dinophyceae)

    PubMed Central

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

    2016-01-01

    We investigated the morphology and evolutionary relationships of Torodinium spp. and Katodinium glaucum, unarmoured dinoflagellates characterized by a small hyposome. An emended generic description of Torodinium was proposed based on light and scanning electron microscopy. Torodinium exhibited a unique combination of morphological features including a minute hyposome, a long episome with longitudinal ribs and a canal of unknown function on the dextro-lateral side. Unlike any known dinoflagellate both cingulum and sulcus extended in the episome. The apex surface showed ribs that converged in a bill-like projection. The shape of the apical groove was a circular spiral that extended around the apex running in 2.5 turns in an anticlockwise direction. The type species T. teredo was usually longer than T. robustum. The longitudinal outline of T. teredo was linear, with almost parallel margins, a circular transversal section, a relatively large hyposome and a conspicuous bill-like projection. The longitudinal outline of T. robustum was oblong, widened in the middle, with an ellipsoidal transversal section, a small hyposome and a less prominent bill-like projection. Several morphological features of Katodinium glaucum (=Gyrodinium glaucum) resembled Gyrodinium, such as the cingular displacement, longitudinal ribs, trichocysts, rod-shaped and refractile bodies and a capsule that surrounded the spherical nucleus. Distinctive features of K. glaucum were the horseshoeshaped apical groove under a tongue-shaped notch pointed towards the dorsal side, and a bifurcated proximal end of the cingulum. Phylogenetic analysis revealed that Torodinium spp. and K. glaucum formed two independent lineages with no close relationships with other known dinoflagellates. The morphology of K. glaucum was distant from the type species of Katodinium. We propose the new genus and combination Lebouridinium glaucum gen. nov., comb. nov. for the species Katodinium glaucum. PMID:27284214

  19. A dual-species co-cultivation system to study the interactions between Roseobacters and dinoflagellates

    PubMed Central

    Wang, Hui; Tomasch, Jürgen; Jarek, Michael; Wagner-Döbler, Irene

    2014-01-01

    Some microalgae in nature live in symbiosis with microorganisms that can enhance or inhibit growth, thus influencing the dynamics of phytoplankton blooms. In spite of the great ecological importance of these interactions, very few defined laboratory systems are available to study them in detail. Here we present a co-cultivation system consisting of the toxic phototrophic dinoflagellate Prorocentrum minimum and the photoheterotrophic alphaproteobacterium Dinoroseobacter shibae. In a mineral medium lacking a carbon source, vitamins for the bacterium and the essential vitamin B12 for the dinoflagellate, growth dynamics reproducibly went from a mutualistic phase, where both algae and bacteria grow, to a pathogenic phase, where the algae are killed by the bacteria. The data show a “Jekyll and Hyde” lifestyle that had been proposed but not previously demonstrated. We used RNAseq and microarray analysis to determine which genes of D. shibae are transcribed and differentially expressed in a light dependent way at an early time-point of the co-culture when the bacterium grows very slowly. Enrichment of bacterial mRNA for transcriptome analysis was optimized, but none of the available methods proved capable of removing dinoflagellate ribosomal RNA completely. RNAseq showed that a phasin encoding gene (phaP1) which is part of the polyhydroxyalkanoate (PHA) metabolism operon represented approximately 10% of all transcripts. Five genes for aerobic anoxygenic photosynthesis were down-regulated in the light, indicating that the photosynthesis apparatus was functional. A betaine-choline-carnitine-transporter (BCCT) that may be used for dimethylsulfoniopropionate (DMSP) uptake was the highest up-regulated gene in the light. The data suggest that at this early mutualistic phase of the symbiosis, PHA degradation might be the main carbon and energy source of D. shibae, supplemented in the light by degradation of DMSP and aerobic anoxygenic photosynthesis. PMID:25009539

  20. A dual-species co-cultivation system to study the interactions between Roseobacters and dinoflagellates.

    PubMed

    Wang, Hui; Tomasch, Jürgen; Jarek, Michael; Wagner-Döbler, Irene

    2014-01-01

    Some microalgae in nature live in symbiosis with microorganisms that can enhance or inhibit growth, thus influencing the dynamics of phytoplankton blooms. In spite of the great ecological importance of these interactions, very few defined laboratory systems are available to study them in detail. Here we present a co-cultivation system consisting of the toxic phototrophic dinoflagellate Prorocentrum minimum and the photoheterotrophic alphaproteobacterium Dinoroseobacter shibae. In a mineral medium lacking a carbon source, vitamins for the bacterium and the essential vitamin B12 for the dinoflagellate, growth dynamics reproducibly went from a mutualistic phase, where both algae and bacteria grow, to a pathogenic phase, where the algae are killed by the bacteria. The data show a "Jekyll and Hyde" lifestyle that had been proposed but not previously demonstrated. We used RNAseq and microarray analysis to determine which genes of D. shibae are transcribed and differentially expressed in a light dependent way at an early time-point of the co-culture when the bacterium grows very slowly. Enrichment of bacterial mRNA for transcriptome analysis was optimized, but none of the available methods proved capable of removing dinoflagellate ribosomal RNA completely. RNAseq showed that a phasin encoding gene (phaP1 ) which is part of the polyhydroxyalkanoate (PHA) metabolism operon represented approximately 10% of all transcripts. Five genes for aerobic anoxygenic photosynthesis were down-regulated in the light, indicating that the photosynthesis apparatus was functional. A betaine-choline-carnitine-transporter (BCCT) that may be used for dimethylsulfoniopropionate (DMSP) uptake was the highest up-regulated gene in the light. The data suggest that at this early mutualistic phase of the symbiosis, PHA degradation might be the main carbon and energy source of D. shibae, supplemented in the light by degradation of DMSP and aerobic anoxygenic photosynthesis. PMID:25009539

  1. Vertical migration of the toxic dinoflagellate Karenia brevis and the impact on ocean optical properties

    NASA Astrophysics Data System (ADS)

    Schofield, Oscar; Kerfoot, John; Mahoney, Kevin; Moline, Mark; Oliver, Matthew; Lohrenz, Steven; Kirkpatrick, Gary

    2006-06-01

    Vertical migration behavior is found in many harmful algal blooms; however, the corresponding impact on ocean optical properties has not been quantified. A near-monospecific population of the dinoflagellate Karenia brevis was encountered off the west coast of Florida. The community was tracked for 24 hours by following a Lagrangian drifter deployed at the beginning of the experiment. A suite of inherent optical and cellular measurements was made. Over the 24 hour period, the K. brevis population increased during the day with concentrations peaking in the late afternoon (1600 local daylight time) in the upper 2 m of the water column. The increase in K. brevis in surface waters resulted in enhanced reflectance at the sea surface with distinct spectral changes. There was a 22% decrease in the relative amount of the green reflectance due to increased pigment absorption. There was enhanced red (35%) and infrared (75%) light reflectance due to the increased particle backscatter and chlorophyll a fluorescence; however, the relative impact of the fluorescence was relatively small despite high cell numbers due to the significant fluorescence quenching present in K. brevis. The relative change in the blue light reflectance was not as large as the change in green light reflectance, which is surprising given the pigment absorption in the blue wavelengths of light. The increased blue light pigment absorption was offset by a significant decrease in nonalgal particle absorption. The inverse relationship between K. brevis and nonalgal particles was robust. This relationship may reflect low grazing on K. brevis populations due to the neurotoxins associated with this dinoflagellate. The low-grazing pressure may provide the mechanism by which this slow-growing dinoflagellate can achieve high cell numbers in the ocean.

  2. Gambierone, a Ladder-Shaped Polyether from the Dinoflagellate Gambierdiscus belizeanus.

    PubMed

    Rodríguez, Inés; Genta-Jouve, Grégory; Alfonso, Carmen; Calabro, Kevin; Alonso, Eva; Sánchez, Jon A; Alfonso, Amparo; Thomas, Olivier P; Botana, Luis M

    2015-05-15

    A new natural product named gambierone (1) was isolated from the cultured dinoflagellate Gambierdiscus belizeanus. The structure of this compound features an unprecedented polyether skeleton and an unusual right-hand side chain. Its relative configuration was fully determined by interpretation of ROESY experiment and comparison between experimental and theoretical NMR data. Although the succession of cycles has no chemical similarity with ciguatoxins, 1 has a molecular formula and biological activity similar to those of CTX-3C, although much lower in intensity. PMID:25950201

  3. A phylogenetic mosaic plastid proteome and unusual plastid-targeting signals in the green-colored dinoflagellate Lepidodinium chlorophorum

    PubMed Central

    2010-01-01

    Background Plastid replacements through secondary endosymbioses include massive transfer of genes from the endosymbiont to the host nucleus and require a new targeting system to enable transport of the plastid-targeted proteins across 3-4 plastid membranes. The dinoflagellates are the only eukaryotic lineage that has been shown to have undergone several plastid replacement events, and this group is thus highly relevant for studying the processes involved in plastid evolution. In this study, we analyzed the phylogenetic origin and N-terminal extensions of plastid-targeted proteins from Lepidodinium chlorophorum, a member of the only dinoflagellate genus that harbors a green secondary plastid rather than the red algal-derived, peridinin-containing plastid usually found in photosynthetic dinoflagellates. Results We sequenced 4,746 randomly picked clones from a L. chlorophorum cDNA library. 22 of the assembled genes were identified as genes encoding proteins functioning in plastids. Some of these were of green algal origin. This confirms that genes have been transferred from the plastid to the host nucleus of L. chlorophorum and indicates that the plastid is fully integrated as an organelle in the host. Other nuclear-encoded plastid-targeted protein genes, however, are clearly not of green algal origin, but have been derived from a number of different algal groups, including dinoflagellates, streptophytes, heterokonts, and red algae. The characteristics of N-terminal plastid-targeting peptides of all of these genes are substantially different from those found in peridinin-containing dinoflagellates and green algae. Conclusions L. chlorophorum expresses plastid-targeted proteins with a range of different origins, which probably arose through endosymbiotic gene transfer (EGT) and horizontal gene transfer (HGT). The N-terminal extension of the genes is different from the extensions found in green alga and other dinoflagellates (peridinin- and haptophyte plastids). These

  4. Historic 2005 toxic bloom of Alexandrium fundyense in the west Gulf of Maine: 1. In situ observations of coastal hydrography and circulation

    NASA Astrophysics Data System (ADS)

    He, Ruoying; McGillicuddy, Dennis J.

    2008-07-01

    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 coast-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 during May 2005: waters were warmer and fresher coast-wide owing to more surface heating and river runoff; coastal currents were at least 2 times stronger than their climatological means. Surface winds were also anomalous in the form of both episodic bursts of northeast winds and a downwelling-favorable mean condition. These factors may have favored more vigorous along-shore transport and nearshore aggregation of toxic A. fundyense cells (a red tide) in 2005.

  5. Liquid chromatography coupled with tandem mass spectrometry to characterise trace levels of cyanobacteria and dinoflagellate toxins in suspended solids and sediments.

    PubMed

    Rivetti, Claudia; Gómez-Canela, Cristian; Lacorte, Silvia; Barata, Carlos

    2015-02-01

    Microcystins, anatoxins and okadaic acid are toxins produced by freshwater cyanobacteria and marine dinoflagellates. These toxins have been the responsible for the illness and death of biota and humans. To determine their presence in water during blooms, sensitive analytical methods are needed. In this study, we have developed a new liquid chromatography tandem mass spectrometry (LC-MS/MS) method for fast multiresidue determination of five toxins in suspended material and sediment samples. For each target compound, two selected reaction monitoring (SRM) transitions were optimised. Chromatographic conditions were optimised considering that the compounds analysed had different chemical structure and chromatographic behaviour. Using a Luna C18 column and specific SRM transitions, five phytotoxins were resolved. Method detection limits (MDL) for anatoxin-a, microcystins RR, LR and YR and okadaic acid were 7.1, 3.3, 81.7, 102.8 and 28.8 ng g(-1) dry weight in sediment, respectively. The developed analytical method was successfully applied to analyse the presence of toxins in suspended solids and sediment from Ebro River (NE Spain) and Ebro delta-associated lagoons. Anatoxin-a was detected downstream of the Riba-Roja reservoir with levels ranging from 20 to 1120 ng g(-1) dry weight of suspended solids. Okadaic acid was only detected in three samples collected in the Alfacs Bay (Ebro delta, Spain) affected by Dinophysis blooms in 2012. PMID:25619981

  6. Long-Range Dispersal and High-Latitude Environments Influence the Population Structure of a “Stress-Tolerant” Dinoflagellate Endosymbiont

    PubMed Central

    Pettay, D. Tye; LaJeunesse, Todd C.

    2013-01-01

    The migration and dispersal of stress-tolerant symbiotic dinoflagellates (genus Symbiodinium) may influence the response of symbiotic reef-building corals to a warming climate. We analyzed the genetic structure of the stress-tolerant endosymbiont, Symbiodinium glynni nomen nudum (ITS2 - D1), obtained from Pocillopora colonies that dominate eastern Pacific coral communities. Eleven microsatellite loci identified genotypically diverse populations with minimal genetic subdivision throughout the Eastern Tropical Pacific, encompassing 1000’s of square kilometers from mainland Mexico to the Galapagos Islands. The lack of population differentiation over these distances corresponds with extensive regional host connectivity and indicates that Pocillopora larvae, which maternally inherit their symbionts, aid in the dispersal of this symbiont. In contrast to its host, however, subtropical populations of S. glynni in the Gulf of California (Sea of Cortez) were strongly differentiated from populations in tropical eastern Pacific. Selection pressures related to large seasonal fluctuations in temperature and irradiance likely explain this abrupt genetic discontinuity. We infer that S. glynni genotypes harbored by host larvae arriving from more southern locations are rapidly replaced by genotypes adapted to more temperate environments. The strong population structure of S. glynni corresponds with fluctuating environmental conditions and suggests that these genetically diverse populations have the potential to evolve rapidly to changing environments and reveals the importance of environmental extremes in driving microbial eukaryote (e.g., plankton) speciation in marine ecosystems. PMID:24223906

  7. Osmotic stress does not trigger brevetoxin production in the dinoflagellate Karenia brevis

    PubMed Central

    Sunda, William G.; Burleson, Cheska; Hardison, D. Ransom; Morey, Jeanine S.; Wang, Zhihong; Wolny, Jennifer; Corcoran, Alina A.; Flewelling, Leanne J.; Van Dolah, Frances M.

    2013-01-01

    With the global proliferation of toxic harmful algal bloom species, there is a need to identify the environmental and biological factors that regulate toxin production. One such species, Karenia brevis, forms nearly annual blooms that threaten coastal regions throughout the Gulf of Mexico. This dinoflagellate produces brevetoxins, which are potent neurotoxins that cause neurotoxic shellfish poisoning and respiratory illness in humans, as well as massive fish kills. A recent publication reported that a rapid decrease in salinity increased cellular toxin quotas in K. brevis and hypothesized that brevetoxins serve a role in osmoregulation. This finding implied that salinity shifts could significantly alter the toxic effects of blooms. We repeated the original experiments separately in three different laboratories and found no evidence for increased brevetoxin production in response to low-salinity stress in any of the eight K. brevis strains we tested, including three used in the original study. Thus, we find no support for an osmoregulatory function of brevetoxins. The original publication also stated that there was no known cellular function for brevetoxins. However, there is increasing evidence that brevetoxins promote survival of the dinoflagellates by deterring grazing by zooplankton. Whether they have other as-yet-unidentified cellular functions is currently unknown. PMID:23754363

  8. Quantitative estimation of Holocene surface salinity variation in the Black Sea using dinoflagellate cyst process length

    NASA Astrophysics Data System (ADS)

    Mertens, Kenneth Neil; Bradley, Lee R.; Takano, Yoshihito; Mudie, Petra J.; Marret, Fabienne; Aksu, Ali E.; Hiscott, Richard N.; Verleye, Thomas J.; Mousing, Erik A.; Smyrnova, Ludmila L.; Bagheri, Siamak; Mansor, Mashhor; Pospelova, Vera; Matsuoka, Kazumi

    2012-04-01

    Reconstruction of salinity in the Holocene Black Sea has been an ongoing debate over the past four decades. Here we calibrate summer surface water salinity in the Black Sea, Sea of Azov and Caspian Sea with the process length of the dinoflagellate cyst Lingulodinium machaerophorum. We then apply this calibration to make a regional reconstruction of paleosalinity in the Black Sea, calculated by averaging out process length variation observed at four core sites from the Black Sea with high sedimentation rates and dated by multiple mollusk shell ages. Results show a very gradual change of salinity from ˜14 ± 0.91 psu around 9.9 cal ka BP to a minimum ˜12.3 ± 0.91 psu around 8.5 cal ka BP, reaching current salinities of ˜17.1 ± 0.91 psu around 4.1 cal ka BP. The resolution of our sampling is about 250 years, and it fails to reveal a catastrophic salinization event at ˜9.14 cal ka BP advocated by other researchers. The dinoflagellate cyst salinity-proxy does not record large Holocene salinity fluctuations, and after early Holocene freshening, it shows correspondence to the regional sea-level curve of Brückner et al. (2010) derived from Balabanov (2007).

  9. Long-term dinoflagellate culture performance in a commercial photobioreactor: Amphidinium carterae case.

    PubMed

    Fuentes-Grünewald, C; Bayliss, C; Fonlut, F; Chapuli, E

    2016-10-01

    The aim of this work was to study the culture performance of a dinoflagellate in a commercial photobioreactor. The results obtained during this long-term experiment allow to confirm that Amphidinium carterae is a promising dinoflagellate that can be exploited successfully in closed systems, in semi-continuous mode in indoor and outdoor environments. The average results in an indoor 5cm light-path 320L photobioreactor were, in terms of specific growth rate (0.29d(-1)), duplication time (3.1d(-1)) and dry biomass productivity (78mgL(-1)d(-1)). Specific compounds production was found including ω3 and ω6 fatty acids and, pigments (Peridinin, β-carotene). These promising results, besides unique characteristics found during the exploitation period such as resistance to mechanical stress, self-control of contaminant organisms, and quick cells aggregation when the culture is not in turbulence conditions, makes A. carterae one of the new target species suitable for commercially exploitation on an industrial scale. PMID:27395001

  10. Spatial distribution of the phytoplankton in the White Sea during atypical domination of dinoflagellates (July 2009)

    NASA Astrophysics Data System (ADS)

    Ilyash, L. V.; Zhitina, L. S.; Belevich, T. A.; Shevchenko, V. P.; Kravchishina, M. D.; Pantyulin, A. N.; Tolstikov, A. V.; Chultsova, A. L.

    2016-05-01

    The species composition and biomass of phytoplankton, concentrations of chlorophyll a (Chl a) and nutrients, and accompanying hydrophysical conditions have been studied in the White Sea on July 6-11, 2009. The temperature of the surface water layer was lower than the multiyear average in July. Dinoflagellates dominated in the entire studied area; this was not the typical event for July. We suggest that domination of dinoflagellates was caused by low water temperature, when the nutrient regeneration rate was insufficient to support diatom growth. The abundance of microalgae and the structure of the phytoplankton community depended on the water structure. Variations in the phytoplankton community structure were caused not by substitution of specific species but rather by variability of the abundance of a single species, Heterocapsa triquetra. The highest phytoplankton biomass has been recorded in weakly stratified waters, where tidal mixing supplied the income of inorganic nutrients. The income of nutrients to the photic layer was limited in the stratified waters of Dvina Bay during the summer low-water period, so the phytoplankton abundance was low. We suggest that the lens of surface desalinated water presumably originated from the outlet of the Dvina River was registered in the central part of the White Sea.

  11. Cellulose Synthesis Is Coupled to Cell Cycle Progression at G1 in the Dinoflagellate Crypthecodinium cohnii

    PubMed Central

    Kwok, Alvin C.M.; Wong, Joseph T.Y.

    2003-01-01

    Cellulosic deposition in alveolar vesicles forms the “internal cell wall” in thecated dinoflagellates. The availability of synchronized single cells, the lack of secondary deposition, and the absence of cellulosic cell plates at division facilitate investigation of the possible roles of cellulose synthesis (CS) in the entire cell cycle. Flow cytograms of cellulosic contents revealed a stepwise process of CS in the dinoflagellate cell cycle, with the highest rate occurring at G1. A cell cycle delay in G1, but not G2/M, was observed after inhibition of CS. A cell cycle inhibitor of G1/S, but not G2/M, was able to delay cell cycle progression with a corresponding reduction of CS. The increase of cellulose content in the cell cycle corresponded well to the expected increase of surface area. No differences were observed in the cellulose to surface area ratio between normal and fast-growing G1 cells, implicating the significance of surface area in linking CS to the coupling of cell growth with cell cycle progression. The coupling of CS to G1 implicates a novel link between CS and cell cycle control, and we postulate that the coupling mechanism might integrate cell wall integrity to the cell size checkpoint. PMID:12692327

  12. Evidence for an Inorganic Carbon-Concentrating Mechanism in the Symbiotic Dinoflagellate Symbiodinium sp.1

    PubMed Central

    Leggat, William; Badger, Murray R.; Yellowlees, David

    1999-01-01

    The presence of a carbon-concentrating mechanism in the symbiotic dinoflagellate Symbiodinium sp. was investigated. Its existence was postulated to explain how these algae fix inorganic carbon (Ci) efficiently despite the presence of a form II Rubisco. When the dinoflagellates were isolated from their host, the giant clam (Tridacna gigas), CO2 uptake was found to support the majority of net photosynthesis (45%–80%) at pH 8.0; however, 2 d after isolation this decreased to 5% to 65%, with HCO3− uptake supporting 35% to 95% of net photosynthesis. Measurements of intracellular Ci concentrations showed that levels inside the cell were between two and seven times what would be expected from passive diffusion of Ci into the cell. Symbiodinium also exhibits a distinct light-activated intracellular carbonic anhydrase activity. This, coupled with elevated intracellular Ci and the ability to utilize both CO2 and HCO3− from the medium, suggests that Symbiodinium sp. does possess a carbon-concentrating mechanism. However, intracellular Ci levels are not as large as might be expected of an alga utilizing a form II Rubisco with a poor affinity for CO2. PMID:10594111

  13. A nanoscale secondary ion mass spectrometry study of dinoflagellate functional diversity in reef-building corals.

    PubMed

    Pernice, Mathieu; Dunn, Simon R; Tonk, Linda; Dove, Sophie; Domart-Coulon, Isabelle; Hoppe, Peter; Schintlmeister, Arno; Wagner, Michael; Meibom, Anders

    2015-10-01

    Nutritional interactions between corals and symbiotic dinoflagellate algae lie at the heart of the structural foundation of coral reefs. Whilst the genetic diversity of Symbiodinium has attracted particular interest because of its contribution to the sensitivity of corals to environmental changes and bleaching (i.e. disruption of coral-dinoflagellate symbiosis), very little is known about the in hospite metabolic capabilities of different Symbiodinium types. Using a combination of stable isotopic labelling and nanoscale secondary ion mass spectrometry (NanoSIMS), we investigated the ability of the intact symbiosis between the reef-building coral Isopora palifera, and Symbiodinium C or D types, to assimilate dissolved inorganic carbon (via photosynthesis) and nitrogen (as ammonium). Our results indicate that Symbiodinium types from two clades naturally associated with I. palifera possess different metabolic capabilities. The Symbiodinium C type fixed and passed significantly more carbon and nitrogen to its coral host than the D type. This study provides further insights into the metabolic plasticity among different Symbiodinium types in hospite and strengthens the evidence that the more temperature-tolerant Symbiodinium D type may be less metabolically beneficial for its coral host under non-stressful conditions. PMID:24902979

  14. Concentration-dependent organization of DNA by the dinoflagellate histone-like protein HCc3

    PubMed Central

    Chan, Yuk-Hang; Wong, Joseph T. Y.

    2007-01-01

    The liquid crystalline chromosomes of dinoflagellates are the alternative to the nucleosome-based organization of chromosomes in the eukaryotes. These nucleosome-less chromosomes have to devise novel ways to maintain active parts of the genome. The dinoflagellate histone-like protein HCc3 has significant sequence identity with the bacterial DNA-binding protein HU. HCc3 also has a secondary structure resembling HU in silico. We have examined HCc3 in its recombinant form. Experiments on DNA-cellulose revealed its DNA-binding activity is on the C-terminal domain. The N-terminal domain is responsible for intermolecular oligomerization as demonstrated by cross-linking studies. However, HCc3 could not complement Escherichia coli HU-deficient mutants, suggesting functional differences. In ligation assays, HCc3-induced DNA concatenation but not ring closure as the DNA-bending HU does. The basic HCc3 was an efficient DNA condensing agent, but it did not behave like an ordinary polycationic compound. HCc3 also induced specific structures with DNA in a concentration-dependent manner, as demonstrated by atomic force microscopy (AFM). At moderate concentration of HCc3, DNA bridging and bundling were observed; at high concentrations, the complexes were even more condensed. These results are consistent with a biophysical role for HCc3 in maintaining extended DNA loops at the periphery of liquid crystalline chromosomes. PMID:17412706

  15. Bloom development and transport of toxic Alexandrium fundyense populations within a coastal plume in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Keafer, Bruce A.; Churchill, James H.; McGillicuddy, Dennis J.; Anderson, Donald M.

    2005-09-01

    Toxic Alexandrium fundyense blooms in the western Gulf of Maine (GOM) are a common occurrence, causing paralytic shellfish poisoning (PSP) each spring. In contrast, high A. fundyense abundances and PSP toxicity commonly occur later in the summer in the eastern GOM and the Bay of Fundy. The objective of this study was to determine if the bloom dynamics of the two areas are linked early in the bloom season when initial outbreaks of toxicity are reported. A. fundyense cell abundance and hydrographic data were acquired during three cruises in May and June, 2001 spanning areas of the western and eastern GOM. Surface drifters also were released into the nearshore coastal flow of the eastern GOM. These data provide a coherent view of the springtime evolution of toxic A. fundyense blooms in the GOM and the influence of both small- and large-scale circulation. Early in the bloom season (May), the bulk of the A. fundyense population was consistently observed in an alongshore band of cells in the eastern GOM associated with relatively low-salinity water (<32) that likely originated from inputs further upstream in the coastal flow, predominantly the St. John River in the Bay of Fundy. At that time, the western GOM was virtually devoid of cells. In June, the population was bifurcated, with one branch extending alongshore into the western GOM and the other into the offshore waters of the interior GOM. This pattern was consistent with circulation models of the coastal GOM that unambiguously revealed a bifurcated flow with the branch nearest the coast directed alongshore to the western GOM. The most significant finding of this study is that A. fundyense populations along the eastern Maine coast were delivered along an "inside track" relative to the core of the eastern segment of the Maine Coastal Current. The transport pathway carried cells across the mouth of Penobscot Bay and into the western GOM coincident with outbreaks of nearshore PSP toxicity. The transport is influenced by

  16. DINOFLAGELLATE CYST RECORDS AND HUMAN DISTURBANCE IN TWO NEIGHBORING ESTUARIES, NEW BEDFORD HARBOR AND APPONAGANSETT BAY, MASSACHUSETTS, USA

    EPA Science Inventory

    The dinoflagellate cyst records in sediments from New Bedford Harbor and Apponagansett Bay demonstrate sensitivity to environmental change caused by human activity in the watersheds over the last 500 years. Changes in the species richness, as well as absolute and relative abundan...

  17. ENVIRONMENTAL FACTORS INFLUENCING THE SPATIAL DISTRIBUTION OF DINOFLAGELLATE CYST ASSEMBLAGES IN SHALLOW LAGOONS IN SOUTHERN NEW ENGLAND (USA)

    EPA Science Inventory

    Surface sediment samples from 24 sites within eleven back-barrier lagoons of Rhode Island and Massachusetts (USA) contain abundant (200-6000 cysts cm-3) and diverse (up to 40 taxa) dinoflagellate cyst assemblages. The lowest cyst concentrations and diversity are observed in lagoo...

  18. PHYLOGENETIC RELATIONSHIP OF THE RED TIDE DINOFLAGELLATE GYMNODINIUM BREVE TO OTHER MEMBERS OF THE GENERA GYMNODINIUM AND GYRODINIUM

    EPA Science Inventory

    Phylogenetic relationships between the red-tide dinoflagellate Gymnodinium breve and other members of the genera Gymnodinium and Gyrodinium have not been studied at the molecular level. G. breve is most noted for its production of brevetoxin, which has been linked to extensive f...

  19. BIO-OPTICAL CHARACTERIZATION OF THE DINOFLAGELLATE GYMNODINIUM BREVE AND THE DIATOM THALASSIOSIRA WEISSFLOGII IN OUTDOOR TANKS

    EPA Science Inventory

    The bio-optical signatures of harmful algal blooms can be used to define ocean color satellite algorithms. We characterized the bio-optical properties of nutrient-replete cultures of the red tide dinoflagellate Gymnodinium breve and the diatom Thalassiosira weissflogii. We cultur...

  20. A novel cyclophilin gene from the dinoflagellate Prorocentrum minimum and its possible role in the environmental stress response.

    PubMed

    Ponmani, Thangaraj; Guo, Ruoyu; Ki, Jang-Seu

    2015-11-01

    Cyclophilins (CYPs) are a family of proteins that bind to cyclosporine and are thought to be involved in the stress response. In dinoflagellate algae, CYPs may function as a survival strategy in cells exposed to environmental stressors. Here, we identified a novel cyclophilin gene (referred to as PmCYP, comprising a 516-bp open reading frame, encoding a 171-aa protein with a molecular mass of 17.5kDa) from the dinoflagellate Prorocentrum minimum, and evaluated the role of dinoflagellate CYP in cells exposed to environmental pollutants copper and polychlorinated biphenyl. In addition, we assessed the cytoprotective role of nitric oxide in relation to the expression of PmCYP. These stressors strongly affected the physiology of the cells, as judged by cell counting, reactive oxygen species (ROS) imaging, and photosynthetic parameters (Fv/Fm and PIABS). PmCYP expression was significantly (P<0.05) induced upon exposure of the cells to all the test pollutants used in this study. These clearly indicate that PmCYP plays a vital role in the oxidative stress response in dinoflagellate survival, although the gene was initially known only for its housekeeping function. PMID:26150195

  1. Dinoflagellates: Fossil motile-stage tests from the upper cretaceous of the Northern New Jersey coastal plain

    USGS Publications Warehouse

    May, F.E.

    1976-01-01

    Fossil dinoflagellate tests have been considered to represent encysted, nonmotile stages. The discovery of flagellar porelike structures and probable trichocyst pores in the Upper Cretaceous genus Dinogymnium suggests that motile stage tests are also preserved as acid-resistant, organic-walled microfossils.

  2. CHEMOSENSORY ATTRACTION OF ZOOSPORES OF THE ESTUARINE DINOFLAGELLATES, PFIESTERIA PISCICIDA AND P. SHUMWAYAE, TO FINFISH MUCUS AND EXCRETA. (R825551)

    EPA Science Inventory

    Toxic strains of the estuarine dinoflagellates, Pfiesteria piscicida and P. shumwayae, can cause fish death and disease, whereas other estuarine `lookalike' species such as cryptoperidiniopsoids have not been ichthyotoxic under ecologically rel...

  3. Heat-Stress and Light-Stress Induce Different Cellular Pathologies in the Symbiotic Dinoflagellate during Coral Bleaching

    PubMed Central

    Downs, C. A.; McDougall, Kathleen E.; Woodley, Cheryl M.; Fauth, John E.; Richmond, Robert H.; Kushmaro, Ariel; Gibb, Stuart W.; Loya, Yossi; Ostrander, Gary K.; Kramarsky-Winter, Esti

    2013-01-01

    Coral bleaching is a significant contributor to the worldwide degradation of coral reefs and is indicative of the termination of symbiosis between the coral host and its symbiotic algae (dinoflagellate; Symbiodinium sp. complex), usually by expulsion or xenophagy (symbiophagy) of its dinoflagellates. Herein, we provide evidence that during the earliest stages of environmentally induced bleaching, heat stress and light stress generate distinctly different pathomorphological changes in the chloroplasts, while a combined heat- and light-stress exposure induces both pathomorphologies; suggesting that these stressors act on the dinoflagellate by different mechanisms. Within the first 48 hours of a heat stress (32°C) under low-light conditions, heat stress induced decomposition of thylakoid structures before observation of extensive oxidative damage; thus it is the disorganization of the thylakoids that creates the conditions allowing photo-oxidative-stress. Conversely, during the first 48 hours of a light stress (2007 µmoles m−2 s−1 PAR) at 25°C, condensation or fusion of multiple thylakoid lamellae occurred coincidently with levels of oxidative damage products, implying that photo-oxidative stress causes the structural membrane damage within the chloroplasts. Exposure to combined heat- and light-stresses induced both pathomorphologies, confirming that these stressors acted on the dinoflagellate via different mechanisms. Within 72 hours of exposure to heat and/or light stresses, homeostatic processes (e.g., heat-shock protein and anti-oxidant enzyme response) were evident in the remaining intact dinoflagellates, regardless of the initiating stressor. Understanding the sequence of events during bleaching when triggered by different environmental stressors is important for predicting both severity and consequences of coral bleaching. PMID:24324575

  4. A universal driver of macroevolutionary change in the size of marine phytoplankton over the Cenozoic.

    PubMed

    Finkel, Z V; Sebbo, J; Feist-Burkhardt, S; Irwin, A J; Katz, M E; Schofield, O M E; Young, J R; Falkowski, P G

    2007-12-18

    The size structure of phytoplankton assemblages strongly influences energy transfer through the food web and carbon cycling in the ocean. We determined the macroevolutionary trajectory in the median size of dinoflagellate cysts to compare with the macroevolutionary size change in other plankton groups. We found the median size of the dinoflagellate cysts generally decreases through the Cenozoic. Diatoms exhibit an extremely similar pattern in their median size over time, even though species diversity of the two groups has opposing trends, indicating that the macroevolutionary size change is an active response to selection pressure rather than a passive response to changes in diversity. The changes in the median size of dinoflagellate cysts are highly correlated with both deep ocean temperatures and the thermal gradient between the surface and deep waters, indicating the magnitude and frequency of nutrient availability may have acted as a selective factor in the macroevolution of cell size in the plankton. Our results suggest that climate, because it affects stratification in the ocean, is a universal abiotic driver that has been responsible for macroevolutionary changes in the size structure of marine planktonic communities over the past 65 million years of Earth's history. PMID:18077334

  5. Transcriptomic response of the red tide dinoflagellate, Karenia brevis, to nitrogen and phosphorus depletion and addition

    PubMed Central

    2011-01-01

    Background The role of coastal nutrient sources in the persistence of Karenia brevis red tides in coastal waters of Florida is a contentious issue that warrants investigation into the regulation of nutrient responses in this dinoflagellate. In other phytoplankton studied, nutrient status is reflected by the expression levels of N- and P-responsive gene transcripts. In dinoflagellates, however, many processes are regulated post-transcriptionally. All nuclear encoded gene transcripts studied to date possess a 5' trans-spliced leader (SL) sequence suggestive, based on the trypanosome model, of post-transcriptional regulation. The current study therefore sought to determine if the transcriptome of K. brevis is responsive to nitrogen and phosphorus and is informative of nutrient status. Results Microarray analysis of N-depleted K. brevis cultures revealed an increase in the expression of transcripts involved in N-assimilation (nitrate and ammonium transporters, glutamine synthetases) relative to nutrient replete cells. In contrast, a transcriptional signal of P-starvation was not apparent despite evidence of P-starvation based on their rapid growth response to P-addition. To study transcriptome responses to nutrient addition, the limiting nutrient was added to depleted cells and changes in global gene expression were assessed over the first 48 hours following nutrient addition. Both N- and P-addition resulted in significant changes in approximately 4% of genes on the microarray, using a significance cutoff of 1.7-fold and p ≤ 10-4. By far, the earliest responding genes were dominated in both nutrient treatments by pentatricopeptide repeat (PPR) proteins, which increased in expression up to 3-fold by 1 h following nutrient addition. PPR proteins are nuclear encoded proteins involved in chloroplast and mitochondria RNA processing. Correspondingly, other functions enriched in response to both nutrients were photosystem and ribosomal genes. Conclusions Microarray analysis

  6. Assessing strength and dynamics of the Oligocene Antarctic Circumpolar Current using organic-walled dinoflagellate cysts

    NASA Astrophysics Data System (ADS)

    Bijl, P.; Houben, A. J.; Sangiorgi, F.; Brinkhuis, H.

    2013-12-01

    The Oligocene Epoch (33.9-23 Ma) is the time interval in the Cenozoic that saw the establishment of a continental-scale Antarctic ice-sheet. Numerical modelling studies suggest that alongside continental ice, first sea-ice conditions may have started along the East Antarctic Margin, but this conclusion lacks support from field evidence. Other numerical models predict that hysteresis effects within the ice sheet will make a continental-size Antarctic ice sheet rather insensitive to warming. In contrast, deep-water benthic foraminiferal oxygen isotope records across the Oligocene suggest dramatic waxing and waning of Antarctic ice sheets. The role of opening of Southern Ocean Gateways on the process of building and sustaining Antarctic continental ice has been questioned in the past. Particularly uncertain is the timing of the installation of a strong Antarctic Circumpolar Current (ACC), and the dynamics of its strength in the earlier phases of Gateway throughflow. Integrated Ocean Drilling Expedition 318 drilled the Antarctic Margin in 2010, and recovered sediments from the early phase of Antarctic glaciation. With this record, we can now evaluate the robustness of the results of the numerical models and the oceanographic changes with field data. Sediments recovered from Site U1356 yields a thick and relatively complete (albeit compromised by core gaps) Oligocene succession both of which are chrono-stratigraphically well-calibrated with use of nannoplankton- dinocyst- and magnetostratigraphy. Notably, this record yields well-preserved dinoflagellate cysts (dinocysts). Dinocysts are the fossilizable remains of dinoflagellates, some of which are today specifically linked to the high (seasonal) productivity of the ecosystems associated with sea-ice and oceanic fronts. In the earliest Oligocene, just after the onset of Antarctic glaciation, we document the installation of dinoflagellate cyst assemblages that bear remarkable similarity with those of the present

  7. Marine Ecomechanics

    NASA Astrophysics Data System (ADS)

    Denny, Mark W.; Gaylord, Brian

    2010-01-01

    The emerging field of marine ecomechanics provides an explicit physical framework for exploring interactions among marine organisms and between these organisms and their environments. It exhibits particular utility through its construction of predictive, mechanistic models, a number of which address responses to changing climatic conditions. Examples include predictions of (a) the change in relative abundance of corals as a function of colony morphology, ocean acidity, and storm intensity; (b) the rate of disturbance and patch formation in beds of mussels, a competitive dominant on many intertidal shores; (c) the dispersal and recruitment patterns of giant kelps, an important nearshore foundation species; (d) the effects of turbulence on external fertilization, a widespread method of reproduction in the sea; and (e) the long-term incidence of extreme ecological events. These diverse examples emphasize the breadth of marine ecomechanics. Indeed, its principles can be applied to any ecological system.

  8. Simultaneous screening for lipophilic and hydrophilic toxins in marine harmful algae using a serially coupled reversed-phase and hydrophilic interaction liquid chromatography separation system with high-resolution mass spectrometry.

    PubMed

    Chen, Junhui; Gao, Liyuan; Li, Zhaoyong; Wang, Shuai; Li, Jingxi; Cao, Wei; Sun, Chengjun; Zheng, Li; Wang, Xiaoru

    2016-03-31

    The presence of toxins in harmful algal blooms (HABs) poses considerable concerns because of their potential adverse effects on ecological environments and human health. When marine HABs occur, efficient screening and identification of toxins in different kinds of HAB algae remains a challenge. In this study, the applicability of serial coupling of reversed-phase liquid chromatography (RPLC) and hydrophilic interaction chromatography (HILIC) combined with high resolution mass spectrometry (HR-MS) for the simultaneous screening and identification of various kinds of known lipophilic and hydrophilic toxins in HAB algae was investigated for the first time. Ultrasound-assisted extraction (UAE) was explored to extract both lipophilic and hydrophilic toxins in algae simultaneously. As in most cases, toxin standards were not available; therefore, an identification procedure based on accurate mass data and chromatographic behavior was proposed. According to this procedure, eight known lipophilic toxins and 11 hydrophilic toxins were successfully detected in a single injection, and the proposed method was validated. Satisfactory sensitivity, repeatability (RSD <14.87%) and recovery (89.4-105.8%) of the method were achieved. A major advantage of the proposed method is that it can almost detect members of all eight groups of marine algal toxins in a single run. Using this method, several known toxins in different marine toxigenic algae including Alexandrium tamarense, Alexandrium minutum and Prorocentrum lima were successfully observed and identified. This work demonstrates that RPLC/HILIC-HR-MS combined with an accurate mass list of known marine algal toxins may be used as a powerful tool for screening of different classes of known toxins in marine harmful algae. PMID:26965334

  9. Optofluidic characterization of marine algae using a microflow cytometer.

    PubMed

    Hashemi, Nastaran; Erickson, Jeffrey S; Golden, Joel P; Ligler, Frances S

    2011-09-01

    The effects of global warming, pollution in river effluents, and changing ocean currents can be studied by characterizing variations in phytoplankton populations. We demonstrate the design and fabrication of a Microflow Cytometer for characterization of phytoplankton. Guided by chevron-shaped grooves on the top and bottom of a microfluidic channel, two symmetric sheath streams wrap around a central sample stream and hydrodynamically focus it in the center of the channel. The lasers are carefully chosen to provide