Marine Dinoflagellate Research Articles

A simple protocol for the isolation of proteorhodopsins of the dinoflagellate Oxyrrhis marina.

For the first time, native proteorhodopsins of the marine dinoflagellate Oxyrrhis marina were isolated. Total cell membrane fractions were minced in a bead beater and solubilized with the detergent Triton X-100. Subsequent sucrose density gradient centrifugation resulted in three or four red-colored bands. Nonsolubilized, but still red colored, membranes sedimented at the bottom. For each of these bands, absorbance maxima were registered at approximately 514-516 nm with shoulders toward shorter wavelengths (470-490 nm). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the uppermost band represented free retinal chromophore, as it contained no protein. The other bands were almost pure proteorhodopsin fractions as the banding patterns showed one major protein of 25 kDa. Tryptic, in-gel digestion of the 25 kDa proteins and of faint protein bands above and below 25 kDa was followed by mass spectrometry, confirming these protein bands to consist, nearly exclusively, proteorhodopsins. Only single peptides of few other proteins were detected. In total, at least seven predicted proteorhodopsin protein sequences were experimentally verified.

Recent findings of paralytic shellfish toxins linked to the genus Alexandrium Halim in Mediterranean mollusc production areas

Paralytic shellfish poisoning is a human intoxication syndrome associated with the consumption of seafood that has been contaminated with paralytic shellfish toxins (PSTs), a group of natural neurotoxic alkaloids produced by marine dinoflagellates, including some Alexandrium species. This study presents findings of PSTs in mussels (Mytilus galloprovincialis) during 2018–2019 in several mollusc production areas of Sardinia (Italy, western Mediterranean). Investigations of the presence and abundance of PST-producing microalgal species in marine water and of the toxins associated with shellfish were carried out concomitantly. Overall, the results suggested a spatio-temporal expansion of Alexandriumpacificum and Alexandriumminutum in recent years, with an increasing number of PSTs present in molluscs and increased occurrences of toxicity cases. Liquid chromatography with fluorescence detection determined the toxin profile to be composed primarily of the carbamate gonyautoxin-5 and N-sulphocarbamoyltoxins 1 and 2. The study highlights the potential high risk to consumers of poisoning by bivalve molluscs bred in Sardinia, where shellfish production is a very important industrial sector. For this reason, routine monitoring is strongly recommended in order to mitigate any harm to human health as well as negative socio-economic consequences.

Gondwana biostratigraphy and geology of West Bengal Basin, and its correlation with adjoining Gondwana basins of India and western Bangladesh

Integrated biostratigraphic and geological studies on the drilled exploratory boreholes of West Bengal Basin have revealed the presence of very thick distinctive Permo-Triassic Gondwana successions in the subsurface, and widely recognized across the basin below the latest Jurassic–Early Cretaceous Rajmahal Traps. Precise geological age of identified Gondwana lithounits of this basin is inferred on the basis of associated palynofloral assemblages along with their correlation with the adjoining Gondwana basins. In addition, two Gondwanic grabens are recognized below the pericratonic set-up whose presence in this basin, till now, are poorly understood. Detailed palynological studies on the Gondwana successions in the key boreholes of this basin enable recognition of 12 established palynological zones ranging from Early Permian (Asselian) to Middle Triassic (Ladinian). Lower Gondwana (Permian) palynofloras of this basin resemble earlier recorded palynofloras from the Talchir, Barakar and Raniganj formations of Indian Gondwana basins, suggesting the occurrence of well-developed above Lower Gondwana lithounits in this basin and the absence of Karharbari and Barren Measures formations which are marked by the non-depositional hiatuses. Upper Gondwana successions (Triassic) of the basin are represented by the Early and Middle Triassic palynofloras only that resemble Panchet and Supra-Panchet (Molangdighi Formation) palynofloral assemblages, and indicate the absence of Late Triassic succession of Upper Gondwana. Newly acquired geological and Bouguer anomaly data, and spatial distribution of Gondwana bearing boreholes across the basin suggest that the boreholes of CHK-A, GB-A, HRP-A, AMD-A, PLS-A and MNG-A fall in a well-defined NNE–SSW aligned graben, defined as the ‘Chandkuri–Palasi–Bogra Gondwanic Graben’ which includes Chandkuri and Palasi Gondwana basins in Indian part and Bogra Gondwana Basin in western Bangladesh where thick Gondwana successions are recognised in the subsurface sections of Singra (Singra-1X, Kuchma-X1, Bogra-X1), Jamalganj (EDH-1, 6) and Barapukuria (GDH-40, 43) coalfields. Gondwana bearing boreholes in the western margins of West Bengal Basin (GLS-A, GLS-B, GLS-C) represent a quite separate Gondwana basin of ‘Galsi’ which is located in the southern part of the N–S trending ‘Purnea–Rajmahal–Galsi Gondwanic Graben’. Latest Jurassic–Early Cretaceous Rajmahal Traps cap the Gondwana successions in the above Gondwana basins of West Bengal Basin along with Bogra and Rajmahal Gondwana basins. Rajmahal Traps and its infra- and intertrappean beds are exlcuded from the Gondwana cycle as these beds are marked by the Early Cretaceous marine dinoflagellate cysts, and the Rajmahal volcanism took place after a very long time gap from Late Triassic to Late Jurassic (ca. 78 my). Rajmahal Traps and its infra- and intertrappean beds indeed represent the post-Gondwana syn-rift sequence in West Bengal, Mahanadi and Rajmahal basins, and closely related with the break-up of Indian Plate from the East Gondwanaland during Tithonian (ca. 150 Ma). The post-trappean Late Cretaceous successions mark the initiation of passive-margin phase in this basin with the deposition of marine Bolpur and Ghatal formations.

CISTOS DE DINOFLAGELADOS DO HOLOCENO DA PLANÍCIE COSTEIRA DE SANTA CATARINA (POÇO PSC-03): DESCRIÇÕES TAXONÔMICAS E IMPLICAÇÕES PALEOAMBIENTAIS

Estudos palinológicos de detalhe abordando cistos de dinoflagelados quaternários de depósitos sedimentares brasileiros são relativamente escassos. A análise palinológica de sedimentos do Holoceno do poço PSC-03 (27º53'22"S; 48º39'04'' W) perfurado na Planície Costeira de Santa Catarina, sul do Brasil, revelou associações palinológicas abundantes e diversificadas que incluem palinomorfos terrestres (esporos, grãos de pólen, fungos, algas de água doce) e marinhos (cistos de dinoflagelados, palinoforaminíferos). A não exposição das amostras a métodos agressivos, tais como oxidação e acetólise, durante o processamento laboratorial permitiu a recuperação de cistos da Família Protoperidiniaceae. Três gêneros (Brigantedinium spp., Lejeunecysta spp., Spiniferites spp.) e quatro espécies (Brigantedinium simplex, Selenopemphix nephroides, S. quanta, Operculodinium centrocarpum) de cistos de dinoflagelados são descritos e ilustrados aqui, constituindo uma das associações fósseis mais diversificadas do grupo para o Holoceno brasileiro. A associação de cistos de dinoflagelados sugere ambiente marinho marginal, com águas superficiais susceptíveis a variação de salinidade e alta concentração de nutrientes.

Nioella ostreopsis sp. nov., isolated from toxic dinoflagellate, Ostreopsis lenticularis.

A novel short-rod-shaped bacterial strain with poly-β-hydroxybutyric acid granules inside, designated as Z7-4T, was isolated from a culture of a marine dinoflagellate with palytoxin-producing capacity, Ostreopsis lenticularis OS06, collected from the East China Sea. Cells of Z7-4T were Gram-stain-negative, non-motile, strictly aerobic, 0.9-1.2 µm wide and 2.0-3.9 µm long. Growth occurred in 1-4 % (w/v) NaCl, at 15-37 °C and at pH 5.0-10.0, with optimum growth in 3.5 % (w/v) NaCl, at 30 °C and at pH 7.0. Analysis of 16S rRNA gene sequence revealed that Z7-4T shared the highest 16S rRNA gene sequence similarities with Nioella aestuarii JCM 30752T (98.8 %), followed by Nioella sediminis KCTC 42144T (98.6 %) and Nioella nitratireducens KCTC 32417T (96.9 %). Phylogenetic analysis based on nearly complete 16S rRNA gene sequences revealed that Z7-4T clearly represented a member of the genus Nioella within the family Rhodobacteraceae. The respiratory quinone of Z7-4T was identified as Q-10. Polar lipids of Z7-4T were phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, three unidentified aminophospholipids and one unidentified phospholipid. The major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The DNA G+C content of Z7-4T was 63.0 mol%. DNA-DNA hybridization values of the isolate against the closely related type strains were far below the 70 % limit for species delineation. The average nucleotide identity and in silico DNA-DNA genome hybridization relatedness between Z7-4T and the closely related members of the genus Nioella, N. sediminis KCTC 42144T and N. nitratireducens KCTC 32417T, were 91.1 and 46.3 %, and 79.3 and 19.4 %, respectively. On the basis of the results of polyphasic analysis, Z7-4T is proposed to represent a novel species of the genus Nioella, for which the name Nioella ostreopsis sp. nov. is proposed. The type strain of Nioella ostreopsis is Z7-4T (=KCTC 62459T=CCTCC AB 2017231T).

Haliea alexandrii sp. nov., isolated from phycosphere microbiota of the toxin-producing dinoflagellate Alexandrium catenella.

A Gram-negative, aerobic, non-motile, non-spore-forming and rod-shaped bacterium, named strain LZ-16-2T, was isolated from the phycosphere microbiota of the paralytic shellfish poisoning toxin-producing marine dinoflagellate Alexandrium catenella LZT09. Strain LZ-16-2T grew optimally at 28 °C at pH 6.5 and with 3 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain LZ-16-2T fell within the genus Haliea and was most closely related to Haliea salexigens DSM 19537T, with which the new isolate exhibited 98.5 % 16S rRNA gene sequence similarity. The major respiratory quinone was Q-8. The predominant cellular fatty acids were C17 : 1 ω8c, summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), C17 : 1 ω6c, C11 : 0 3-OH and C17 : 0. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The average nucleotide identity and in silico DNA-DNA genome hybridization relatedness values between strain LZ-16-2T and its closest relative, H. salexigens DSM 19537T, were 92.8 and 55.1 %, respectively. The DNA G+C content was 61.3 mol%. Differential phenotypic properties and phylogenetic distinctiveness distinguished strain LZ-16-2T from all other members of the genus Haliea. On the basis of the polyphasic characterization, strain LZ-16-2T represents a novel species of the genus Haliea, for which the name Haliea alexandrii sp. nov. is proposed. The type strain is LZ-16-2T (=KCTC 62344T=CCTCC AB2017229T).

Saccharospirillum alexandrii sp. nov., isolated from the toxigenic marine dinoflagellate Alexandrium catenella LZT09.

A Gram-stain-negative, strictly aerobic, non-motile and non-pigmented spirillum, designated strain LZ-5T, was isolated from cultures of the paralytic shellfish poisoning (PSP) toxin-producing marine dinoflagellate Alexandrium catenella LZT09 collected from the Zhoushan sea area in the East China Sea during an algal bloom. The isolate grew at 4-40 °C (optimum, 25-33 °C) and pH 5.0-9.0 (optimum, 7.5) in the presence of 0.5-10 % (w/v) NaCl (optimum, 4.0 %). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain LZ-5T clearly belonged to the genus Saccharospirillum of the family Saccharospirillaceae. Strain LZ-5T shared highest 16S rRNA gene sequence similarity with Saccharospirillum impatiens EL-105T (98.9 %), Saccharospirillum mangrovi HK-33T (97.2 %), Saccharospirillum correiae CPA1T (96.8 %), Saccharospirillum salsuginis YIM-Y25T (96.8 %) and Saccharospirillum aestuarii IMCC 4453T (95.1 %). The average nucleotide identity and in silico DNA-DNA hybridization between strain LZ-5T and the two most closely related Saccharospirillum strains, S. impatiens EL-105T and S. mangrovi HK-33T, were 82.2 and 19.3 %, and 72.2 and 13.2 %, respectively. The predominant respiratory quinone of strain LZ-5T was Q-8, and the major fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and C16 : 0. The polar lipids of strain LZ-5T were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylcholine (PC), glycolipid (GL), two unidentified glycophospholipids (GPLs), three unidentified aminophospholipids (APLs) and two unidentified lipids. The genomic DNA G+C content was 57.2 mol%. On the basis of this polyphasic characterization, strain LZ-5T represents a novel species of the genus Saccharospirillum, for which the name Saccharospirillum alexandrii sp. nov. is proposed. The type strain is LZ-5T (=KCTC 62460T=CCTCC AB2017232T).

Research Progress in the Biosynthetic Mechanisms of Marine Polyether Toxins.

Marine polyether toxins, mainly produced by marine dinoflagellates, are novel, complex, and diverse natural products with extensive toxicological and pharmacological effects. Owing to their harmful effects during outbreaks of marine red tides, as well as their potential value for the development of new drugs, marine polyether toxins have been extensively studied, in terms of toxicology, pharmacology, detection, and analysis, structural identification, as well as their biosynthetic mechanisms. Although the biosynthetic mechanisms of marine polyether toxins are still unclear, certain progress has been made. In this review, research progress and current knowledge on the biosynthetic mechanisms of polyether toxins are summarized, including the mechanisms of carbon skeleton deletion, pendant alkylation, and polyether ring formation, along with providing a summary of mined biosynthesis-related genes. Finally, future research directions and applications of marine polyether toxins are discussed.

Palynofloral diversity and palaeoenvironments of early Eocene Akri lignite succession, Kutch Basin, western India

This study presents palynological analysis of lignite-bearing succession of Akri lignite mine, Kutch, Gujarat, and discussed the implications of the recovered palynomorphs for age, palaeovegetation and palaeoenvironments. A diverse palynological assemblage consisting of algal and fungal remains, pteridophytic spores, angiosperm pollen and dinoflagellate cysts has been recorded. The lower part of the succession (samples 1–5) is dominated by marine dinoflagellate cysts along with palm pollen belonging to family Arecaceae. The upper part of the succession (samples 6–8, 11) is dominated by terrestrial palynomorphs attributed to megathermal families (Bombacaceae, Ctenolophonaceae, Dipterocarpaceae, Meliaceae) followed by mangrove and back-mangrove elements. An early Ypresian age is inferred for the Akri lignite deposit, whereas a middle Ypresian–early Lutetian age is assigned to the post-lignite succession based on the age-diagnostic dinoflagellate cysts and spore-pollen assemblage. Furthermore, based on the distribution of marine and terrestrial palynomorphs, two palynological assemblages (A and B) have been recognised that are apparently controlled by changing depositional environment. The overall palynological assemblage points to a dense tropical rainforest that thrived in the vicinity of the depositional basin under high precipitation regime of warm and humid climate. The peat accumulation took place in a near-shore coastal swamp which was interrupted by fluctuating marine influences, followed by increased siliciclastic influx in a low-salinity coastal swamp dominated by mangroves. Moreover, the palynological comparison suggests that widespread lignite-bearing successions in the western Indian region are in part coeval and belong to the early Eocene (Ypresian) age.

Dactylodinium arachnoides sp. nov. (Borghiellaceae, Dinophyceae): a new marine dinoflagellate with a loop-shaped apical structure complex and tubular membranous extrusomes

ABSTRACTThe morphology and phylogeny of an enigmatic marine dinoflagellate were examined using LM, SEM, TEM, and molecular phylogeny inferred from rDNA. Cells were elliptical with a conical epicone and a hemispherical hypocone. They measured c. 24.7 µm long, with a cingulum descending approximately twice its own width. Amphiesmal vesicles were thick and transparent, and were supported by translucent ridges at the suture, which were distinctive and visible by light microscopy. A large peduncle extending to the anterior was accommodated in the anterior sulcal extension. A nucleus was usually located in the hypocone, and chloroplasts were distributed peripherally. The apical structure complex was loop-shaped, originating from the right side of the anterior sulcal extension and extending upward to encircle the dorsal side of the cell apex in an anticlockwise direction. TEM showed trichocysts with lateral hairs, a pyrenoid penetrated by cytoplasmic insertions containing tubules, and an eyespot comprising globules within the chloroplast. Cells also had tubular extrusomes, unique in dinoflagellates, composed of a membrane stacked in a vesicle, and formed a long membranous tube with 2–4 finger-like terminal branches after being released from the vesicle. Molecular phylogenies showed the affinity of the species to Dactylodinium pterobelotum in the family Borghiellaceae. We propose Dactylodinium arachnoides sp. nov. for the dinoflagellate described here. It shares the characteristic traits of amphiesmal vesicles, a peduncle, a pyrenoid, and trichocysts with D. pterobelotum, whereas the number of amphiesmal vesicles, the loop-shaped apical structure complex, eyespot type A, and tubular membranous extrusomes are distinct.

Yellow clay modulates carbohydrate and glutathione responses in the harmful dinoflagellate Cochlodinium polykrikoides and leads to sedimentation

The marine dinoflagellate Cochlodinium polykrikoides is a harmful algal bloom (HAB) species that severely impacts the environment and causes huge economic losses. Yellow clay (YC), considered to be a non-toxic and naturally-occurring material, represents an important step towards the direct control of HABs. In the present study, we evaluated the physiological and biochemical effects of YC on C. polykrikoides after exposures of up to 72 h. We observed little physiological changes in growth rate, chlorophyll a, lipid peroxidation, antioxidant enzymatic activities of superoxide dismutase and catalase, and activity of alkaline phosphatase after exposure to YC. Interestingly, YC significantly increased total carbohydrate and glutathione levels, affecting the physiology of the cells. These results indicate that total carbohydrate content may play an important role in cell–clay aggregation and it could be the main underlying mechanism that mitigates HAB cells via sedimentation.

Identification of a Novel Saxitoxin Analogue, 12β-Deoxygonyautoxin 3, in the Cyanobacterium, Anabaena circinalis (TA04).

Saxitoxin (STX) and its analogues, the potent voltage-gated sodium channel blockers, are biosynthesized by freshwater cyanobacteria and marine dinoflagellates. We previously identified several biosynthetic intermediates in the extract of the cyanobacterium, Anabaena circinalis (TA04), that are primarily produced during the early and middle stages in the biosynthetic pathway to produce STX. These findings allowed us to propose a putative biosynthetic pathway responsible for STX production based on the structures of these intermediates. In the present study, we identified 12β-deoxygonyautoxin 3 (12β-deoxyGTX3), a novel STX analogue produced by A. circinalis (TA04), by comparing the retention time and MS/MS fragmentation pattern with those of synthetic standards using LC–MS. The presence of this compound in A. circinalis (TA04) is consistent with stereoselective enzymatic oxidations at C11 and C12, and 11-O-sulfation, during the late stage of STX biosynthesis, as proposed in previous studies.

Draft Genome Sequence of Marinobacter sp. Strain LZ-6, Isolated from the Toxic Dinoflagellate Alexandrium catenella.

Here, we report the draft genome sequence of Marinobacter sp. strain LZ-6, isolated from the cell culture of a toxic marine dinoflagellate, Alexandrium catenella LZT09. A total of 4,405 predicted protein-coding genes were revealed, including those associated with initial biosynthesis of the key intermediate of paralytic shellfish poisoning toxins (PSTs), namely saxitoxin, and with toxic compound extrusion.

Environmental drivers of paralytic shellfish toxin producing Alexandrium catenella blooms in a fjord system of northern Southeast Alaska

Paralytic shellfish poisoning (PSP) is a persistent problem that threatens human health and the availability of shellfish resources in Alaska. Regular outbreaks of marine dinoflagellates in the genus Alexandrium produce paralytic shellfish toxins (PSTs) that make shellfish consumption unsafe, and impose economic hardships on Alaska’s shellfish industry. Phytoplankton and environmental monitoring spanning 2008–2016, and a pilot benthic cyst survey in 2016, were focused in the Juneau region of Southeast Alaska to investigate Alexandrium catenella distributions and conditions favorable to bloom development. Overwintering Alexandrium cysts were found in near-shore sediments throughout the study region. Alexandrium catenella cells were present in the water column across a range of sea surface temperatures (7–15 °C) and surface salinities (S = 4–30); however, an optimal temperature/salinity window (10–13 °C, 18–23) supported highest cell concentrations. Measurable levels of PSTs were associated with lower concentrations (100 cells L−1) of A. catenella, indicating high cell densities may not be required for shellfish toxicity to occur. Several interacting local factors were identified to support A. catenella blooms: 1) sea surface temperatures ≥7 °C; 2) increasing air temperature; 3) low to moderate freshwater discharge; and 4) several consecutive days of dry and calm weather. In combination, these bloom favorable conditions coincide with toxic bloom events during May and June in northern Southeast Alaska. These findings highlight how integrated environmental and phytoplankton monitoring can be used to enhance early warning capacity of toxic bloom events, providing more informed guidance to shellfish harvesters and resource managers in Alaska.

A review of rare, poorly known, and morphologically problematic extant marine organic-walled dinoflagellate cyst taxa of the orders Gymnodiniales and Peridiniales from the Northern Hemisphere

Abstract Dinoflagellates are a major component of the modern plankton. Of the 2192 species of marine free-living dinoflagellates presently described, an increasing number are being shown to produce resting cysts (probably hypnozygotes) within their life cycle. With rare exception, only the resting cysts fossilize, so they are of central importance in tracing the history of dinoflagellates through geological time. Cysts of many of the more common dinoflagellate species have distinctive morphologies allowing their geographic and stratigraphic occurrences to be traced. An ever-increasing number of taxa are also being shown to produce distinctive and geologically preservable cysts, potentially enhancing our knowledge of the diverse representation of dinoflagellates through time. Here the organic-walled cysts of 73 rare, poorly known or morphologically problematic marine dinoflagellate cyst species belonging to the orders Gymnodiniales (nine species) and Peridiniales (64 species) are reviewed, described and illustrated, and their stratigraphic ranges assessed. The names Echinidinium aculeatum and Echinidinium transparantum are validated.

Omics Analysis for Dinoflagellates Biology Research.

Dinoflagellates are important primary producers for marine ecosystems and are also responsible for certain essential components in human foods. However, they are also notorious for their ability to form harmful algal blooms, and cause shellfish poisoning. Although much work has been devoted to dinoflagellates in recent decades, our understanding of them at a molecular level is still limited owing to some of their challenging biological properties, such as large genome size, permanently condensed liquid-crystalline chromosomes, and the 10-fold lower ratio of protein to DNA than other eukaryotic species. In recent years, omics technologies, such as genomics, transcriptomics, proteomics, and metabolomics, have been applied to the study of marine dinoflagellates and have uncovered many new physiological and metabolic characteristics of dinoflagellates. In this article, we review recent application of omics technologies in revealing some of the unusual features of dinoflagellate genomes and molecular mechanisms relevant to their biology, including the mechanism of harmful algal bloom formations, toxin biosynthesis, symbiosis, lipid biosynthesis, as well as species identification and evolution. We also discuss the challenges and provide prospective further study directions and applications of dinoflagellates.

Trends in Dinophysis abundance and diarrhetic shellfish toxin levels in California mussels (Mytilus californianus) from Monterey Bay, California

Diarrhetic shellfish toxins (DSTs) are produced by the marine dinoflagellate, Dinophysis, as well as select species of benthic Prorocentrum. The DSTs can bioaccumulate in shellfish and cause gastrointestinal illness when humans consume high levels of this toxin. Although not routinely monitored throughout the U.S., recent studies in Washington, Texas, and New York suggest DSTs may be widespread throughout U.S. coastal waters. This study describes a four-year time series (2013–2016) of Dinophysis concentration and DST level in California mussels (Mytilus californianus) from Santa Cruz Municipal Wharf (SCMW) in Monterey Bay, California. Results show a maximum Dinophysis concentration of 9404 cells/L during this study and suggest Dinophysis persists as a member of the background phytoplankton community throughout the year. In California mussels, DSTs were found at persistent low levels throughout the course of this study, and exceeded the FDA guidance level of 160 ng/g 19 out of 192 weeks sampled. Concentrations of Dinophysis alone are a positive but weak predictor of DST level in California mussels, and basic environmental variables (temperature, salinity, and nutrients) do not sufficiently explain variation in Dinophysis concentration at SCMW. This study demonstrates that Dinophysis in Monterey Bay are producing DSTs that accumulate in local shellfish throughout the year, occasionally reaching levels of concern.

The State of Knowledge of Harmful Algal Blooms of Margalefidinium polykrikoides (a.k.a. Cochlodinium polykrikoides) in Latin America

The marine dinoflagellate Margalefidinium polykrikoides is a harmful species that has affected aquaculture, fisheries and tourism activities. It produces reactive oxygen species (ROS) as well as hemolytic and neurotoxic-like substances that have been associated with mass mortalities of marine organisms. It has a tropical and subtropical distribution that has mainly affected Asia and North America. The economic impacts for aquaculture industries have been estimated to be up to US$140M. In Latin America, no economic estimates have been performed. Harmful algal blooms by M. polykrikoides are more frequent in Mexico and Central America. Proliferations of this dinoflagellate are associated with winds, upwelling, convergence areas, local convection of seawater, and eutrophication of coastal areas by nitrogen and phosphorus compounds from rainwater runoff, as well as agricultural and aquaculture activities, into coastal waters. Eco-physiological and toxicological studies have provided detailed descriptions of the growth of algal strains from these regions and the harmful effects on fish and shrimp, as well as the role the production of ROS and polyunsaturated fatty acids in their toxicity. It is also possible that M. polykrikoides has an ecological role in the regulation of blooms of other harmful algae. In this contribution, we review the records of harmful algal blooms of M. polykrikoides in Latin America and the research that has been conducted with this species.

Revisiting the taxonomy of the “Dinophysis acuminata complex’’ (Dinophyta)’

Marine dinoflagellates of the genus Dinophysis are well known for producing diarrhetic shellfish poisoning (DSP) toxins and/or pectenotoxins which have a significant impact on public health as well as on marine aquaculture. Out of more than 80 Dinophysis species recorded so far, D. cf. acuminata is the most commonly observed in coastal areas worldwide. Due to their highly similar morphological features, however, an accurate discrimination of the various D. cf. acuminata species such as D. acuminata, D. ovum, and D. sacculus under light microscopy has proven to be a difficult task to accomplish. Hence, these species have thus far been referred to as the “Dinophysis acuminata complex”. Recent studies showed a discrimination between local strains of D. acuminata and D. ovum from Galician, northwestern Spain, using the mitochondrial cox1 gene as a genetic marker in addition to commonly used morphological features such as size and contour of the large hypothecal plates, shape of the small cells formed as part of their polymorphic life-cycle, development of the left sulcal list and ribs, and length of the right sulcal list. In the present study, attempts were made to discriminate between D. acuminata and D. ovum following single-cell isolation of 54 “D. acuminata complex” collected from Korean coastal waters, based on the abovementioned traits. Morphological data showed that all the traits analyzed overlapped between the two species. The mitochondrial cox1 (cytochrome c oxidase subunit I) gene sequences of every isolate were also determined, but a genetic distinction between D. acuminata and D. ovum could not be confirmed, suggesting that the cox1 gene is not a suitable genetic marker for discrimination between the two species. The results of this study suggest that the morphological variations observed within the “D. acuminata complex” may have been caused by several factors (e.g. different geographical locations, seasonal changes, and different environmental conditions), and that D. acuminata and D. ovum may be the same species.

Molecular cloning and oxidative-stress responses of a novel manganese superoxide dismutase (MnSOD) gene in the dinoflagellate Prorocentrum minimum.

Dinoflagellate algae are microeukaryotes that have distinct genomes and gene regulation systems, making them an interesting model for studying protist evolution and genomics. In the present study, we discovered a novel manganese superoxide dismutase (PmMnSOD) gene from the marine dinoflagellate Prorocentrum minimum, examined its molecular characteristics, and evaluated its transcriptional responses to the oxidative stress-inducing contaminants, CuSO4 and NaOCl. Its cDNA was 1238bp and contained a dinoflagellate spliced leader sequence, a 906bp open reading frame (301 amino acids), and a poly (A) tail. The gene was coded on the nuclear genome with one 174bp intron; signal peptide analysis showed that it might be localized to the mitochondria. Real-time PCR analysis revealed an increase in gene expression of MnSOD and SOD activity when P. minimum cells were separately exposed to CuSO4 and NaOCl. In addition, both contaminants considerably decreased chlorophyll autofluorescence, and increased intracellular reactive oxygen species. These results suggest that dinoflagellate MnSOD may be involved in protecting cells against oxidative damage.