Gymnodinium Sp Research Articles

Harmful algal bloom of the three selected coastal bays in Indonesia

The occurrences of phytoplankton bloom have recently increased in some coastal bays in Indonesia. Harmful algal blooms are now a significant problem for several coastal bays, which causes problems and economic losses to the fishing industry, harm to aquatic ecosystems, fish mortalities, and other living organisms. The negative impact also affects the marine environment, tourism, and consumer health. The most frequent algal bloom occurrences are three coastal bays: Jakarta Bay, Lampung Bay, and Ambon Bay. In particular, those three bays are the most infected areas of harmful algal bloom in this country. Samples were taken using a 20 um net plankton and directly preserved with Lugol’s solution before being identified. Some bloom maker species were identified as toxic, mainly belonging to dinoflagellates, such as Pyrodinium sp, Aleandrium sp, Gymnodinium sp, and Cochlodinium sp. And the species that most frequently cause a bloom in those coastal waters are Skeletonema, Chaetoceros, Trichodesmium, and Noctiluca. The nutrients, mainly nitrate and phosphate, are the main driving factor resulting from anthropogenic activities on the land that make the coastal waters eutrophic. This paper discusses the recent distribution, causes, and impact of harmful algal blooms in the three coastal bays in this country.

Hydrobiological and Bio-Optical Characterization of a Red Tide Occurredin Meda Creek, Porbandar, India

Red tides are becoming more common in aquatic ecosystems, particularly the coastal habitats which are highly influenced by climatic and anthropogenic activities. We provide the first report of a red tide event in Meda creek, west coast of India. Light and scanning electron microscopy were used to identify the bloom forming organism, while physicochemical, biological and biooptical parameters were determined to characterize the aquatic body of the Meda Creek. The dominant bloom forming organisms were observed as unarmored, spherical, dorsoventrally compressed flagellate with truncated apex, notched and rounded hypocone, displaced premedian cingulum and extending sulcus. The length wise size of the cell varied from 20 to 30.83μM, whereas, the width varied from 14 to 27.5μM. The organisms was identified as Gymnodinium sp. High Performance Liquid Chromatography (HPLC) and spectral profile of the bloom indicatedeleven major peaks corresponding to that of 19-but-fucoxanthin (52.75%), astaxanthin (9.62%), fucoxanthin (8.81%), Mgdv (6.45%), prasinoxanthin (3.35%), chlorophyll C2 (3.22%), neoxanthin (3.12%), antheraxanthin (3.14%), diadinoxanthin (2.63%) and diatoxanthin (1.38%). Chlorophyll a concentration in the bloom sample was 38.8μg/L. Water temperature, salinity, NH3-N, NO2-N, NO3-N, PO4-Pwere higher during the bloom period than the non-blooming ones, while metals including Fe, Zn, Cr, Mn and Co were lower. No death of aquatic biota was observed. We propose that eutrophication along with the warm and saline conditions provided enabling conditions for occurrence the bloom. Also, most of the pigments expressed have antioxidant role and might be purposeful for the survival of the organism in the extreme condition of temperature and salinity recorded. Proper management and monitoring measures might help mitigate further occurrences of this bloom in the light changing climate and increasing anthropogenic impacts.

Distribution of saxitoxin producing algae in Jakarta Bay and the implication to saxitoxin concentration in green mussel

Harmful algae blooms (HABs) have been associated with an annual incidence in Jakarta Bay. The The present study aimed to investigate the concentration of dinoflagellates producing saxitoxins (STXs) in Cilincing and Kalibaru regions and the STXs concentration in mussel species from this coastal water. A sampling of phytoplankton, green mussel (Perna viridis), and environmental parameters were measured during the transition from wet to dry season. The water nutrients of the Cilincing region, mainly nitrite and ammonia in some green mussel aquaculture, have exceeded the recommended concentration to support the eutrophication/algae bloom. The N/P ratio at the study area was between 10 and 22. Plankton identification found STXs producing dinoflagellates, i.e., Alexandrium sp. and Gymnodinium sp. Other species of dinoflagellates and diatom showed predominantly to trigger algae Bloom, such as Skeletonema sp., Chaetoceros sp., Prorocentrum sp., Gonyaulax sp., Protoperidinium sp., and Nitzchia sp. Further analysis of saxitoxin in mussel samples from Cilincing and Kalibar showed STX concentrations of 10.15 μg/100 g and 21.24 μg/100 g, respectively, which is fairly below the official maximum limit (80 μg/100 g) as set by FAO/WHO or national standard.

Dinoflagellate cyst assemblages in surface sediment from Jakarta Bay

Dinoflagellate cysts play an essential role in the initiation, recurrence and geographical expansion of harmful algal blooms (HABs). The horizontal distribution and abundance of dinoflagellate cysts in marine sediments provide essential information in giving early warnings of the presence of toxic species and possible continuing recurrence of HABs in a given area. This research carried out in the waters of Jakarta Bay. Sediment samples collected from thirteen sampling stations using TFO gravity corer 2.1 cm diameter from sediment thickness 0-4 cm. The results showed that resting cysts belong to Gonyaulax, Alexandrium, Scrippsiella, Protoperidinium, Gymnodinium, Gyrodinium. Two of them, namely Gymnodinium sp and Alexandrium sp, known as toxic species. Cysts in the sediment thickness 0-4 cm mainly dominated by the group of Gonyaulax (Gonyaulacoid). Cyst abundance in the sediment depth-layer 0-2 cm is higher than in depth-layer 2-4 cm. The number of dino-cysts in sediment layer 0-2 cm ranged from 2.984 – 22.298 cysts cm−3 while in the layer 2-4 cm the amount varies from 1.063 – 8.132 cysts cm−3 of wet sediment. The result revealed that dino-cyst abundance is higher in the deposit collected from locations near to the coast. The assemblages of dinoflagellate resting cysts seemed to have a relation with some hydrological parameters.

Effects of suspended particles on the growth of two dominant phytoplankton species of Bohai Bay, China

Suspended particles (SP) are increasing dramatically in Bohai Bay, China and may affect the growth and composition of phytoplankton assembly. To determine the effects of SP on the growth of two dominant phytoplankton species, Phaeodactylum tricornutum Bohlin and Gymnodinium sp., we cultured and tested their growth characteristics under SP concentrations ranging from 0gL−1 to 0.8gL−1. Our results show that the increase in the SP concentrations results in significant decrease in the maximum cell densities and the maximum specific growth rates of these two species. The half maximal inhibitory concentration (IC50) of SP to P. tricornutum and Gymnodinium sp. were 1.07gL−1 and 0.68gL−1 respectively, indicating the inhibitory effect of SP on Gymnodinium sp. was greater than on P. tricornutum. These results suggest that SP inhibits the growth of the two algal species and P. tricornutum is more tolerant to SP than Gymnodinium sp.

Reproduction and respiration of a climate change indicator species: effect of temperature and variable food in the copepod Centropages chierchiae

The abundance of the calanoid copepod Centropages chierchiae has increased at the northern limits of its distribution in recent decades, mainly due to oceanic climate forcing, suggesting this as a key species in monitoring climate change. Laboratory experiments were conducted to study the combined effect of temperature, food type and concentration on the egg production rate (EPR) and hatching success (HS) of C. chierchiae. Females were fed on two monoalgal diets (Gymnodinium sp. and Phaeodactylum tricornutum) at two food concentrations and at three different temperatures (13, 19, 24°C). Respiration rates of both genders were measured at four different temperatures (8, 13, 19, 24°C). EPR was significantly different between temperatures and food concentrations, the maximum EPR being attained when the copepods were exposed to high food levels and at 19°C. Prey type significantly influenced EPR; feeding on P. tricornutum resulted in higher egg production than Gymnodinium sp. HS was significantly lower at 13°C than at 19 and 24°C and higher with Gymnodinium sp. Respiration rates were sex independent and increased exponentially with temperature. To maintain basal metabolism, the minimum food intake of P. tricornutum ranged between 0.4 and 1.8 µg C and for Gymnodinium sp. between 0.03 and 0.13 µg C. Food intake was always higher than the metabolic demands, except for the highest temperature tested (24°C). The present results confirm the sensitivity of C. chierchiae to temperature variations and may help in understanding the successful expansion of its distribution towards northern latitudes.

Phytoplankton community composition in nearshore coastal waters of Louisiana

Phytoplankton community compositions within near-shore coastal and estuarine waters of Louisiana were characterized by group diversity, evenness, relative abundance and biovolume. Sixty-six taxa were identified in addition to eight potentially harmful algal genera including Gymnodinium sp. Phytoplankton group diversity was lowest at Vermillion Bay in February 2008, but otherwise ranged between 2.16 and 3.40. Phytoplankton evenness was also lowest at Vermillion Bay in February 2008, but otherwise ranged between 0.54 and 0.77. Dissolved oxygen increased with increased biovolume (R2=0.85, p<0.001) and biovolume decreased with increased light attenuation (R2=0.34, p=0.007), which supported the importance of light in regulating oxygen dynamics. Diatoms were dominant in relative abundance and biovolume at almost all stations and all cruises. Brunt–Väisälä frequency was used as a measure of water column stratification and was negatively correlated (p=0.02) to diatom relative percent total abundance.

Gyrodiniellum shiwhaense n. gen., n. sp., A New Planktonic Heterotrophic Dinoflagellate from the Coastal Waters of Western Korea: Morphology and Ribosomal DNA Gene Sequence

The heterotrophic dinoflagellate Gyrodiniellum shiwhaense n. gen., n. sp. is described from live cells and from cells prepared for light, scanning electron, and transmission electron microscopy. Also, sequences of the small subunit (SSU) and large subunit (LSU) of rDNA have been analyzed. The episome is conical, while the hyposome is ellipsoid. Cells are covered with polygonal amphiesmal vesicles arranged in 16 horizontal rows. Unlike other Gyrodinium-like dinoflagellates, the apical end of the cell shows a loop-shaped row of five elongate amphiesmal vesicles. The cingulum is displaced by 0.3-0.5 × cell length. Cells that were feeding on the dinoflagellate Amphidinium carterae Hulburt were 9.1-21.6 μm long and 6.6-15.7 μm wide. Cells of G. shiwhaense contain nematocysts, trichocysts, a peduncle, and pusule systems, but they lack chloroplasts. The SSU rDNA sequence is >3% different from that of the six most closely related species: Warnowia sp. (FJ947040), Lepidodinium viride Watanabe, Suda, Inouye, Sawaguchi & Chihara, Gymnodinium aureolum (Hulburt) Hansen, Gymnodinium catenatum Graham, Nematodinium sp. (FJ947039), and Gymnodinium sp. MUCC284 (AF022196), while the LSU rDNA is 11-12% different from that of Warnowia sp., G. aureolum, and Nematodinium sp. (FJ947041). The phylogenetic trees show that the species belongs in the Gymnodinium sensu stricto clade. However, in contrast to Gymnodinium spp., cells lack nuclear envelope chambers and a nuclear fibrous connective. Unlike Polykrikos spp., cells of which possess a taeniocyst-nematocyst complex, G. shiwhaense has nematocysts but lacks taeniocysts. It differs from Paragymnodinium shiwhaense Kang, Jeong, Moestrup & Shin by possessing nematocysts with stylets and filaments. Gyrodiniellum shiwhaense n. gen., n. sp. furthermore lacks ocelloids, in contrast to Warnowia spp., Nematodinium spp., and Proterythropsis spp. Based on morphological and molecular data, we suggest that the taxon represents a new species within a new genus.

Mono- and digalactosyldiacylglycerol composition of dinoflagellates. III. Four cold-adapted, peridinin-containing taxa and the presence of trigalactosyldiacylglycerol as an additional glycolipid

Despite their importance in marine and freshwater microalgal assemblages, cold-adapted dinoflagellates have been the subject of few comprehensive lipid studies, particularly with respect to those lipids that comprise plastid membranes. In an effort to understand the differences between warm- and cold-adapted dinoflagellate glycolipid composition, four peridinin-containing, cold-adapted dinoflagellates were surveyed for intact forms of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), two common plastid lipids, using positive-ion electrospray ionization/mass spectrometry (ESI/MS) and electrospray ionization/mass spectrometry/mass spectrometry (ESI/MS/MS). It was determined that the dominant forms of MGDG and DGDG in these cold-adapted, peridinin-containing dinoflagellates possessed C18 fatty acids and did not, with the exception of a 20:5/18:5 form of DGDG in a cold-adapted Gymnodinium sp. from the Baltic Sea, have C20 fatty acids. This finding is in contrast to an earlier study of 35 peridinin-containing, warm-adapted dinoflagellates, which discovered a cluster dominated by C18 fatty acids and a cluster dominated by both C20 and C18 fatty acids. The key difference in MGDG and DGDG production between the former group and the cold-adapted dinoflagellates examined in this study is that the cold-adapted species’ DGDG fatty acids were less saturated. Each cold-adapted dinoflagellate possessed both 18:5/18:5 and 18:5/18:4 DGDG, while most of the warm-adapted dinoflagellates contained only 18:5/18:4 DGDG. This survey also revealed the presence of a putative 18:1/14:0 trigalactosyldiacylglycerol (TGDG) as a dominant glycolipid in Gymnodinium sp. TGDG, previously unreported in dinoflagellates, was also discovered in Gymnodinium sp. in the forms of 18:1/16:0 and 18:1/18:1 TGDG, as minor lipids. Since the fatty acids associated with TGDG are not those found with dominant forms of MGDG or DGDG, TGDG may be produced by a different biosynthetic pathway.

Preliminary survey of potentially harmful dinoflagellates in Nigeria´s coastal waters.

In many coastal states the presence and impacts of harmful dinoflagellates have been investigated and documented in the literature. Scientists and government officials in many countries routinely monitor their coastal waters for harmful algae in order to prevent harvesting of contaminated seafood. But this is not the case for Nigeria, a coastal state in the Gulf of Guinea, West Africa. The present work reports findings from a first attempt to monitor potentially harmful algae in the coastal waters of Nigeria. Samples were collected from specific locations that included a coastal sea, a lagoon, estuaries and creeks along Nigeria's coastline in November 1999 and April 2001. Potentially harmful dinoflagellates recorded during these periods included 3 Ceratium species, 5 Dinophysis species, 3 Gonyaulax species, 1 Gymnodinium sp, 1 Lingulodinium species, 4 Prorocentrum species and 1 Scrippsiella species. The potential ecological and human health risks associated with similar species in the literature are highlighted.

Plankton origin of particulate dimethylsulfoniopropionate in a Mediterranean oligotrophic coastal and shallow ecosystem

We report here dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) levels as a function of plankton communities and abiotic factors over a 12-month cycle in the Mediterranean oligotrophic coastal and shallow ecosystem of Niel Bay (N.W. Mediterranean Sea, France). Total particulate DMSP (DMSP p ) and DMS concentrations were highly seasonal, peaking during a spring (April) bloom at 8.9 nM and 73.9 nM, respectively. Significant positive correlations were found between total DMSP p concentration and the abundance or biomass of the dinoflagellate Prorocentrum compressum (Spearman's rank correlation test: r = 0.704; p = 0.011). Similarly, DMS concentrations peaked during the development of blooms of P. compressum and Gymnodinium sp. There seemed to be a positive relationship between the chlorophyll a to pheopigment ratio and DMS concentrations, suggesting that DMS was released during phytoplankton growth. High DMS levels recorded in the shallow Niel Bay may also result from the activity of benthic macroalgae, and/or macrophytes such as Posidonia spp., or the resuspension of sulfur species accumulating in sediments. The fractionation of particulate DMSP into three size classes (>90 μm, 5–90 μm and 0.2–5 μm) revealed that 5–90 μm DMSP-containing particles made the greatest contribution to the total DMSP p pool (annual mean contribution = 62%), with a maximal contribution in April (96%). This size class consisted mainly of dinoflagellates (annual mean contribution = 68%), with P. compressum and Gymnodinium sp. the predominant species, together accounting for up to 44% of the phytoplankton present. The positive correlation between DMSP concentration in the 5–90 μm size class and the abundance of P. compressum (Spearman's rank correlation test: r = 0.648; p = 0.023) suggests that this phytoplankton species would be the major DMSP producer in Niel Bay. The DMSP collected in the >90 μm fraction was principally associated with zooplankton organisms, dominated by copepods (nauplii and copepodites). DMSP >90, not due to a specific zooplankton production, resulted from the phytoplankton cells ingested during grazing. The concomitant peaks of DMS concentration and zooplankton abundance suggest that zooplankton may play a role in releasing DMSP and/or DMS through sloppy feeding.

Development of rRNA and rDNA-targeted probes for fluorescence in situ hybridization to detect Heterosigma akashiwo (Raphidophyceae)

Heterosigma akashiwo (Hada) is a fragile, fish-killing alga. Efforts to understand and prevent blooms due to this harmful species to mitigate the impact on aquaculture require the development of methods for rapid and precise identification and quantification, so that adequate warning of a harmful algal bloom may be given. Here, we report the development and application of rRNA and rDNA-targeted oligonucleotide probes for fluorescence in situ hybridization (FISH) to aid in the detection and enumeration of H. akashiwo. The designed probes were species specific, showing no cross-reactivity with four common HAB causative species: Prorocentrum micans Ehrenberg, P. minimum (Pavillard) Schiller, Alexandrium tarmarense (Lebour) Balech, and Skeletonema costatum (Greville) Cleve, or with four other microalgae, including Gymnodinium sp. Stein, Platy-monas cordiformis (Karter) Korsch, Skeletonema sp.1 Greville and Skeletonema sp.2. The rRNA-targeted probe hybridized to cytoplasmic rRNA, showing strong green fluorescence throughout the whole cell, while cells labeled by rDNA-targeted probe exhibited exclusively fluorescent nucleus. The detection protocols were optimized and could be completed within an hour. For rRNA and rDNA probes, about a corresponding 80% and 70% of targeted cells could be identified and quantified during the whole growth circle, despite the inapparent variability in the average probe reactivity. The established FISH was proved promising for specific, rapid, precise, and quantitative detection of H. akashiwo.

Preliminary identification of three new isolates in genus Alexandrium (Dinophyceae) from China sea area

The 5.8S ribosomal DNA sequences (5.8S rDNA) and their flanking regions, internal transcribed spacer 1 and spacer 2 (ITS1 and ITS2) of three new isolates in genus Alexandrium (Alexandrium sp. qd1, Alexandrium sp. qd2, Alexandrium sp. gz) from China were amplified, sequenced, and subjected to phylogenetic analysis. Alexandrium sp. gz and Alexandrium sp. qd1 were grouped with high bootstrap values with four strains/species, i.e., A. catenella South Korea strain, A. catenella Japan strain, and two from China, Alexandrium sp. AC03 and Alexandrium sp. AN01 being proposed to be A. catenalla in a previous study. Then Alexandrium sp. gz and Alexandrium sp. qd1 were identified as Alexandrium catenella. As A. catenella was isolated from Qingdao and Guangzhou sea areas, it supposedly distributed at least in these two areas and was genetically different. Alexandrium sp. qd2 differed greatly from species in Alexandrium. It clustered with Symbiodinium californium, Symbiodinium sp. G15 and Gymnodinium sp. Zhao 01 with 100% bootstrap value; so Alexandrium sp. qd2 affiliates to genus Symbiodinium, and is probably a free-living Symbiodinium species.

Identification and quantification of the toxic dinoflagellate Gymnodinium sp. with competitive enzyme-linked immunosorbent assay (cELISA)

Polyclonal antibodies were raised against Gymnodinium sp. by immunizing rabbits with cells of the axenic strain. Based on the species-specific antiserum, an indirect competitive enzyme-linked immunosorbent assay (cELISA) was developed to identify and quantify Gymnodinium sp. A standard curve was established to correlate the cELISA signal to cell amount on a logit-log basis in the linear range between 24 and 6,250,000 cells, and the equation deducted was ln[ A/( A 0 − A)]= 4.9193 − 1.1006 log[cell amount] ( R 2 = 0.9948, n = 5). The detection limit was found to be 12 cells. The intra-assay and inter-assay coefficients of variation (CVs) were 5.8% and 9.7%, respectively. Field samples collected from Jiaozhou Bay, China were used to assess the robustness of the method. The results showed high agreement with that of cell-counting with a light microscope. The good reproducibility and precision of the cELISA implied that this new technique could be used for fast quantification of Gymnodinium sp.

Inhibition of DNA topoisomerases I and II, and growth inhibition of human cancer cell lines by a marine microalgal polysaccharide

We have previously reported purification of an extracellular polysaccharide GA3P, d-galactan sulfate associated with l-(+)-lactic acid, produced by a toxic marine microalga Dinoflagellate Gymnodinium sp. A 3 (GA3), and induction thereby of apoptosis on human myeloid leukemia K562 cells. In the present report, we show that the GA3P is a potent inhibitor of DNA topoisomerase (topo) I and topo II, irrespective of the presence or absence of the lactate group. Dextran sulfate also showed similar level of inhibition of topo I and topo II. We also demonstrated that, unlike camptothecin (CPT) or teniposide (VM-26), the inhibition of topo I or topo II by the polysaccharide does not involve accumulation of DNA-topo I/II cleavable complexes, clearly showing that they are not topo poisons but catalytic inhibitors with dual activity. Furthermore, the polysaccharide, when added to the reaction mixture with CPT or VM-26, inhibited stabilization of cleavable complex induced by the latter compounds. In addition, when added to the reaction mixture after the formation of the cleavable complexes by topo poisons, CPT for topo I and VM-26 for topo II, either GA3P or dextran sulfate diminished the amount of the complexes already accumulated, i.e. reversal of the reaction. These results suggest that the polysaccharides bind to the enzymes with high affinities, and that, as for topo I/II inhibition, the GA3P shares a common mechanism with dextran sulfate. As examined in vitro with a human cancer cell line panel, GA3P exhibited significant cytotoxicity against a variety of cancer cells. These findings show that the polysaccharide GA3P would prove to be a potential anticancer chemotherapeutic agent with dual activity of topo I and topo II catalytic inhibition.

The effect of growth phase on the lipid class, fatty acid and sterol composition in the marine dinoflagellate, Gymnodinium sp. in batch culture

We have studied the effects of growth phase on the lipid composition in batch cultures of Gymnodinium sp. CS-380/3 over 43 days of culturing. The lipid content increased two fold, from late logarithmic (day 6) to linear growth phase (day 22) then decreased at stationary phase (day 43) while the lipid yield (mg l −1) increased 30-fold from day 6 to 30 mg l −1 at day 43. Changes in fatty acid content mirrored those observed for the total lipid, while the sterol content continued to increase with culture age through to stationary phase. The largest changes occurred in the lipid classes, especially the polar lipids and triacylglycerols (oil). The proportion of triacylglycerols increased from 8% (of total lipids) at day 6 to 30% at day 43, with a concomitant decrease in the polar lipid fraction. The proportions of 16:0 and DHA [22:6(n-3)] increased while those of 18:5(n-3) and EPA [20:5(n-3)] decreased with increasing culture age. The proportion of the major sterol, dinosterol, decreased from 41% (day 6) to 29% (day 43), while the major dinostanol epimer (23 R,24 R) increased from 33% (day 6) to 38% (day 22). Despite small changes in the proportion of the main sterols, the same sterols were present at all stages of growth, indicating their value as a chemotaxonomic tool for distinguishing between strains within the same genus. Growth phase could be a useful variable for optimising the oil and DHA content with potential for aquaculture feeds and a source of DHA-rich oils for nutraceuticals.

First record of a fish-killing Gymnodinium sp. bloom in Kuwait Bay, Arabian Sea: chronology and potential causes

Significant natural and aquaculture fish deaths in Kuwait Bay occurred from September to October of 1999 and were attributed to a bloom of the dinoflagellate Gymnodinium sp. A chronology of the bloom event suggests that a period of low winds and stable water-column structure preceded the bloom. Maximum cell concentrations of Gymnodinium sp. (>6 × 10 6 cells l -1 ) were also immediately preceded by a more than 20-fold increase in mean inorganic nitrogen concentrations (up to 60 µM) and elevated inorganic phosphate concentrations. This, combined with elevated inorganic and or- ganic nutrient concentrations within the bloom, suggests that coastal nutrient eutrophication was likely to have contributed significantly to bloom development and support. Termination of the Gymno- dinium sp. bloom coincided with a bloom of the non-toxic ciliate Mesodinium rubrum, which appeared as large red patches in Kuwait Bay. While no adverse human health effects were associated with the bloom, closure of shellfish and selected finfish (largely mullet Liza macrolepis) markets resulted in sig- nificant economic losses to the region. The occurrence of this toxic algal bloom event, the first within the Arabian Sea, highlights the need for monitoring and research programs in the Arabian Sea and Kuwait Bay that focus on nutrients and eutrophication, in addition to oil related pollution issues.

Phytoplankton in Kongsfjorden, Spitsbergen, July 1996

Abstract Based on the analysis of phytoplankton samples collected 10–16 July 1996 at 16 stations throughout Kongsfjorden, a list of ca 40 algal species is given, and the phytoplankton and chlorophyll a fluorescence spatial distribution is discussed. Data on the abundance of larger nanoplankton (> 5 em) and microphytoplankton (> 20 urn) from 7 stations are presented. The total number of algal cells (TNC), the abundance of the most frequent species (the chrysophytc Dinobryon balticum), and that of dinoflagellates and their correlation with fluorescence intensity are considered separately. High positive correlation coefficient was calculated for TNC for all 7 stations. The dinofiagellate abundance showed high positive correlation with fluorescence at 2 stations in the innermost fjord, close to the glacier, due to Gymnodinium sp. At the remaining 5 stations, negative correlation between dinoflagellates and fluorescence was calculated. Das Phytoplankton des Kongsfjordes (Spitzbergen) wurde auf 16 Stationen vom...

New analogue of gymnodimine from a Gymnodinium species.

A spiroimine, gymnodimine B (1), was isolated from cells recovered by filtration from cultures of a marine dinoflagellate, Gymnodinium sp. Its structure was identified by one- and two-dimensional NMR spectroscopy and mass spectrometry. Gymnodimine B is similar in structure to gymnodimine (2) but contains an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18.

Induction of apoptosis and inhibition of DNA topoisomerase-I in K-562 cells by a marine microalgal polysaccharide

We have previously purified an extracellular polysaccharide, D-galactan sulfate associated with L(+)-lactic acid, produced from a marine microalga Dinoflagellate Gymnodinium sp. A 3 (GA3). The GA3 polysaccharide, irrespective of presence or absence of lactic acid, exhibited significant cytotoxicity, which is based on an induction of apoptotic cell death, toward human myeloid leukemia K562 cells. Furthermore, we found that the GA3 polysaccharide with or without lactic acid possesses an inhibitory effect on topoisomerase-I (topo-I). The potent cytotoxic effect of GA3 polysaccharide may result from its inhibitory effect on topo-I, because the topo-I inhibition is known to trigger apoptotic cell death.