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Toxins Sep 2016Diarrhetic shellfish poisoning (DSP) is a gastrointestinal disorder caused by the consumption of seafood contaminated with okadaic acid (OA) and dinophysistoxins (DTXs).... (Review)
Review
Diarrhetic shellfish poisoning (DSP) is a gastrointestinal disorder caused by the consumption of seafood contaminated with okadaic acid (OA) and dinophysistoxins (DTXs). OA and DTXs are potent inhibitors of protein phosphatases 2A, 1B, and 2B, which may promote cancer in the human digestive system. Their expression in dinoflagellates is strongly affected by nutritional and environmental factors. Studies have indicated that the level of these biotoxins is inversely associated with the growth of dinoflagellates at low concentrations of nitrogen or phosphorus, or at extreme temperature. However, the presence of leucine or glycerophosphate enhances both growth and cellular toxin level. Moreover, the presence of ammonia and incubation in continuous darkness do not favor the toxin production. Currently, studies on the mechanism of this biotoxin production are scant. Full genome sequencing of dinoflagellates is challenging because of the massive genomic size; however, current advanced molecular and omics technologies may provide valuable insight into the biotoxin production mechanism and novel research perspectives on microalgae. This review presents a comprehensive analysis on the effects of various nutritional and physical factors on the OA and DTX production in the DSP toxin-producing Prorocentrum spp. Moreover, the applications of the current molecular technologies in the study on the mechanism of DSP toxin production are discussed.
Topics: Bacterial Physiological Phenomena; Diarrhea; Diet; Dinoflagellida; Humans; Marine Toxins; Okadaic Acid; Pyrans; Shellfish Poisoning
PubMed: 27669302
DOI: 10.3390/toxins8100272 -
Cell Cycle (Georgetown, Tex.) Jun 2023The dinoflagellate specializes its metabolism to perform different tasks better at specific times of day. For example, cells are specialized for photosynthesis during... (Review)
Review
The dinoflagellate specializes its metabolism to perform different tasks better at specific times of day. For example, cells are specialized for photosynthesis during the day and bioluminescence and cell division at night. These rhythms are circadian as they are controlled by an endogenous circadian clock whose mechanism is currently unknown. Despite this, the metabolic rhythms follow coordinated changes in gene expression that occur at a translational level. These changes are revealed by ribosome profiling, a surrogate measure of protein synthesis rates in vivo. Lingulodinium regulates the synthesis rate of over three thousand transcripts. Peak synthesis rates for the different transcripts are clustered around three different times over a light/dark cycle. Furthermore, transcripts involved in the same metabolic process are coordinately regulated. We review the basic principles underlying the correlation of coordinated translation of cell metabolic pathway enzymes with known circadian rhythms, and offer examples where previously unsuspected rhythms are suggested by synchronized changes in gene expression.
Topics: Dinoflagellida; Ribosome Profiling; Circadian Rhythm; Circadian Clocks; Protein Biosynthesis
PubMed: 37125841
DOI: 10.1080/15384101.2023.2206771 -
Proceedings of the National Academy of... Jul 2022Many cells specialize for different metabolic tasks at different times over their normal ZT cycle by changes in gene expression. However, in most cases, circadian gene...
Many cells specialize for different metabolic tasks at different times over their normal ZT cycle by changes in gene expression. However, in most cases, circadian gene expression has been assessed at the mRNA accumulation level, which may not faithfully reflect protein synthesis rates. Here, we use ribosome profiling in the dinoflagellate to identify thousands of transcripts showing coordinated translation. All of the components in carbon fixation are concurrently regulated at ZT0, predicting the known rhythm of carbon fixation, and many enzymes involved in DNA replication are concurrently regulated at ZT12, also predicting the known rhythm in this process. Most of the enzymes in glycolysis and the TCA cycle are also regulated together, suggesting rhythms in these processes as well. Surprisingly, a third cluster of transcripts show peak translation at approximately ZT16, and these transcripts encode enzymes involved in transcription, translation, and amino acid biosynthesis. The latter has physiological consequences, as measured free amino acid levels increase at night and thus represent a previously undocumented rhythm in this model. Our results suggest that ribosome profiling may be a more accurate predictor of changed metabolic state than transcriptomics.
Topics: Amino Acids; Circadian Rhythm; Dinoflagellida; Protein Biosynthesis; RNA, Messenger; Ribosomes; Transcription, Genetic
PubMed: 35858433
DOI: 10.1073/pnas.2122335119 -
Genomics Nov 2020Zooxanthellae and coral can form an intracellular symbiotic system. Yet, little is known about the molecular mechanism underlying this symbiosis. In this study, we...
Zooxanthellae and coral can form an intracellular symbiotic system. Yet, little is known about the molecular mechanism underlying this symbiosis. In this study, we characterized the symbiosis based on analyses of gene expression at the single-cell level. Among 9110 single coral cells, we identified 4871 symbiotic cells based on the detection of both coral and zooxanthellae gene transcripts within a single cell. Using the bioinformatics tool Seurat, symbiotic cells were further clustered into five groups, 52 genes exhibited differential expression between groups. We proposed an index called the "symbiosis index", to indicate the degree of gene expression of both species in a single symbiotic cell. Interestingly, the index differed distinctly among the five groups. The symbiosis index was highly correlated with the expression of the coral gene gfas1.m1.6761 (ANKRD40), which encodes ankyrin repeat domain-containing protein 40 and is involved in DNA replication (r = 0.76). Two metabolism-related genes, DAGLA and betaGlu, were highly expressed in cells with a high symbiosis index. Four zooxanthellae genes, PRPF19, ATRN, aAA-ATPases and AK812-SmicGene44833, exhibited substantial changes in expression levels when zooxanthellae lived within coral. A trajectory analysis suggested that cells with a higher symbiosis index may be derived from those with a lower index during coral colony development. Taken together, our results provide evidence for zooxanthellae residing within coral, forming a symbiotic system. The symbiosis index is an effective indicator of different cell groups, with lineage relationships among groups. Additionally, we identified specific genes that exhibit expression changes in the symbiotic system.
Topics: Animals; Anthozoa; Cluster Analysis; Dinoflagellida; RNA-Seq; Single-Cell Analysis; Symbiosis
PubMed: 33096259
DOI: 10.1016/j.ygeno.2020.10.019 -
Toxins Nov 2022In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and...
In September and November 2016, eight marine sampling sites along the coast of the southeastern Gulf of Mexico were monitored for the presence of lipophilic and hydrophilic toxins. Water temperature, salinity, hydrogen potential, dissolved oxygen saturation, inorganic nutrients and phytoplankton abundance were also determined. Two samples filtered through glass fiber filters were used for the extraction and analysis of paralytic shellfish toxins (PSTs) by lateral flow immunochromatography (IFL), HPLC with post-column oxidation and fluorescent detection (FLD) and UHPLC coupled to tandem mass spectrometry (UHPLC-MS/MS). Elevated nutrient contents were associated with the sites of rainwater discharge or those near anthropogenic activities. A predominance of the dinoflagellate was found with abundances of up to 10 cells L. Identification of the dinoflagellate was corroborated by light and scanning electron microscopy. Samples for toxins were positive by IFL, and the analogs NeoSTX and STX were identified and quantified by HPLC-FLD and UHPLC-MS/MS, with a total PST concentration of 6.5 pg cell. This study is the first report that confirms the presence of PSTs in in Mexican waters of the Gulf of Mexico.
Topics: Humans; Shellfish Poisoning; Marine Toxins; Tandem Mass Spectrometry; Gulf of Mexico; Dinoflagellida; Shellfish; Saxitoxin
PubMed: 36356010
DOI: 10.3390/toxins14110760 -
Toxins Jul 2023Species of the marine dinoflagellate genus are known to produce various potent biotoxins and can form noxious blooms that cause mass mortalities of fish and shellfish....
Species of the marine dinoflagellate genus are known to produce various potent biotoxins and can form noxious blooms that cause mass mortalities of fish and shellfish. To date, harmful blooms of the species have been reported in Korea, but was recently recorded off the southern coast of Korea. Here, we developed a quantitative real-time PCR (qRT-PCR) assay with specific primer pairs for the accurate detection and quantification of these two similar-looking unarmored species, and and investigated their distribution and dynamics in Korean coastal waters. Overall, had not only a wider distribution, but also higher cell abundances (15-2553 cells L) than (3-122 cells L) in surface waters. Of 18 sampling sites, the two species were found to coexist at two sites. During monitoring at a fixed station (S5), was generally predominant over ; however, the two species exhibited similar dynamics and occasionally co-occurred. Both species showed similar physiological responses to temperature and salinity, requiring similar conditions for optimum growth. These results suggest that blooms of the two species may co-occur and induce a synergistic adverse effect on marine environments.
Topics: Animals; Dinoflagellida; Real-Time Polymerase Chain Reaction; Temperature; Republic of Korea; Harmful Algal Bloom
PubMed: 37505738
DOI: 10.3390/toxins15070469 -
PloS One 2021There is little information on the impacts of climate change on resource partitioning for mixotrophic phytoplankton. Here, we investigated the hypothesis that light...
There is little information on the impacts of climate change on resource partitioning for mixotrophic phytoplankton. Here, we investigated the hypothesis that light interacts with temperature and CO2 to affect changes in growth and cellular carbon and nitrogen content of the mixotrophic dinoflagellate, Karlodinium veneficum, with increasing cellular carbon and nitrogen content under low light conditions and increased growth under high light conditions. Using a multifactorial design, the interactive effects of light, temperature and CO2 were investigated on K. veneficum at ambient temperature and CO2 levels (25°C, 375 ppm), high temperature (30°C, 375 ppm CO2), high CO2 (30°C, 750 ppm CO2), or a combination of both high temperature and CO2 (30°C, 750 ppm CO2) at low light intensities (LL: 70 μmol photons m-2 s-2) and light-saturated conditions (HL: 140 μmol photons m-2 s-2). Results revealed significant interactions between light and temperature for all parameters. Growth rates were not significantly different among LL treatments, but increased significantly with temperature or a combination of elevated temperature and CO2 under HL compared to ambient conditions. Particulate carbon and nitrogen content increased in response to temperature or a combination of elevated temperature and CO2 under LL conditions, but significantly decreased in HL cultures exposed to elevated temperature and/or CO2 compared to ambient conditions at HL. Significant increases in C:N ratios were observed only in the combined treatment under LL, suggesting a synergistic effect of temperature and CO2 on carbon assimilation, while increases in C:N under HL were driven only by an increase in CO2. Results indicate light-driven variations in growth and nutrient acquisition strategies for K. veneficum that may benefit this species under anticipated climate change conditions (elevated light, temperature and pCO2) while also affecting trophic transfer efficiency during blooms of this species.
Topics: Biomass; Carbon Dioxide; Dinoflagellida; Eutrophication; Hot Temperature; Nitrogen; Sunlight
PubMed: 34705875
DOI: 10.1371/journal.pone.0259161 -
PloS One 2019Dinoflagellates from the Symbiodiniaceae family and corals have an ecologically important endosymbiotic relationship. Scleractinian corals cannot survive for long...
Dinoflagellates from the Symbiodiniaceae family and corals have an ecologically important endosymbiotic relationship. Scleractinian corals cannot survive for long periods without their symbionts. These algae, also known as zooxanthellae, on the other hand, thrives outside the coral cells. The free-living populations of zooxanthellae are essential for the resilience of the coral to environmental stressors such as temperature anomalies and ocean acidification. Yet, little is known about how ocean acidification may affect the free-living zooxanthellae. In this study we aimed to test morphological, physiological and biochemical responses of zooxanthellae from the Symbiodinium genus isolated from the coral Mussismilia braziliensis, endemic to the Brazilian coast, to acidification led by increased atmospheric CO2. We tested whether photosynthetic yield, cell ultrastructure, cell density and lipid profile would change after up to 16 days of exposure to pH 7.5 in an atmospheric pCO2 of 1633 μatm. Photosynthetic yield and cell density were negatively affected and chloroplasts showed vesiculated thylakoids, indicating morphological damage. Moreover, Symbiodinium fatty acid profile drastically changed in acidified condition, showing lower polyunsaturated fatty acids and higher saturated fatty acids contents, when compared to the control, non-acidified condition. These results show that seawater acidification as an only stressor causes significant changes in the physiology, biochemistry and ultrastructure of free-living Symbiodinium.
Topics: Animals; Anthozoa; Atmosphere; Carbon Dioxide; Carbonates; Cell Proliferation; Dinoflagellida; Fatty Acids; Hydrogen-Ion Concentration; Photosynthesis; Seawater
PubMed: 31381568
DOI: 10.1371/journal.pone.0220130 -
Toxins May 2010The Greek coastal waters are subjected to harmful algal bloom (HAB) phenomena due to the occurrence of species characterized as toxic (TX), potentially toxic (PT), and... (Review)
Review
The Greek coastal waters are subjected to harmful algal bloom (HAB) phenomena due to the occurrence of species characterized as toxic (TX), potentially toxic (PT), and non-toxic, high biomass (HB) producers causing harm at multiple levels. The total number of (TX), (PT) and (HB) algae reported in this work are 61, but only 16 species have been associated with the occurrence of important HABs causing damage in the marine biota and the water quality. These phenomena are sporadic in time, space and recurrence of the causative species, and are related to the anthropogenically-induced eutrophication conditions prevailing in the investigated areas.
Topics: Biomass; Cyanobacteria; Databases, Factual; Diatoms; Dinoflagellida; Ecosystem; Greece; Haptophyta; Harmful Algal Bloom; Mediterranean Sea; Seawater; Stramenopiles; Toxins, Biological
PubMed: 22069623
DOI: 10.3390/toxins2051019 -
Harmful Algae May 2022Harmful algal blooms responsible for mass mortalities of marine organisms have been rare in Hokkaido, northern Japan, although fish-killing blooms have been frequently...
Harmful algal blooms responsible for mass mortalities of marine organisms have been rare in Hokkaido, northern Japan, although fish-killing blooms have been frequently reported from western Japanese coasts. In September-November 2021, a huge and prolonged cold-water bloom occurred along the Pacific coast of eastern Hokkaido, and was associated with intensive mortalities of sea urchin, fish, octopus, shellfish, etc. In this study, morphology and phylogeny of the dominant and co-occurring unarmored dinoflagellates of the Kareniaceae in the bloom were examined by using light microscopy, scanning electron microscopy and molecular phylogeny inferred from ITS and LSU rDNA (D1-D3) sequences. Morphological observation and molecular phylogeny showed that the dominant species was Karenia selliformis, with co-occurrences of other kareniacean dinoflagellates, Kr. longicanalis, Kr. mikimotoi, Karlodinium sp., Takayama cf. acrotrocha, Takayama tuberculata and Takayama sp. The typical cell forms of Kr. selliformis in the bloom were discoid, dorsoventrally flattened, and 35.3-43.6 (39.4 ± 2.1) µm in length, which was larger than the cell sizes in previous reports. Transparent cells of Kr. selliformis, lacking chloroplasts or having a few shrunken chloroplasts and oil droplets, were also found. Cells of Kr. selliformis showed morphological variation, but the species could be distinguished from other co-occurring Karenia species by the nucleus positioned in the hypocone and chloroplasts numerous (46-105) in number and small (2.9-4.6 µm) in diameter. Cell density of Kr. selliformis exceeding 100 cells mL was recorded in the temperature range of 9.8-17.6 °C. The rDNA sequences determined from Kr. selliformis in the blooms of Hokkaido, Japan in 2021 were identical to those from the bloom in Kamchatka, Russia in 2020.
Topics: Animals; DNA, Ribosomal; Dinoflagellida; Harmful Algal Bloom; Japan; Phylogeny; Water
PubMed: 35550287
DOI: 10.1016/j.hal.2022.102204