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1.
Sci Total Environ ; 802: 149801, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34454155

RESUMO

Temperature may affect the production of saxitoxin (STX) and its derivatives (STXs); however, this is still controversial. Further, STX-biosynthesis gene regulation and the relation of its toxicity with temperature are not clearly understood. In the present study, we evaluated the effects of different temperatures (12 °C, 16 °C, and 20 °C) on the growth, toxin profiles, and expression of two core STX-biosynthesis genes, sxtA and sxtG, in the toxic dinoflagellate Alexandrium pacificum Alex05, isolated from Korean coasts. We found that temperature significantly affected cell growth, with maximum growth recorded at 16 °C, followed by 20 °C and 12 °C. HPLC analysis revealed mostly 12 of STXs from the tested cultures. Interestingly, the contents of STXs increased in the cells cultured at 16 °C and exposed to cold stress, compared to the 20 °C culture and heat stress; however, toxin components were much more diverse under heat stress. These toxin profiles generally matched with the sxtA and sxtG expression levels. Incubation at lower temperatures (12 °C and 16 °C) and exposure to cold stress increased sxtA and sxtG expressions in the cells, whereas heat stress showed little change or downregulated the transcription of both genes. Principal component analysis (PCA) showed low correlation between STXs eq and expressional levels of sxtA and sxtG in heat-stressed cells. These results suggest that temperature might be a crucial factor affecting the level and biosynthesis of STXs in marine toxic dinoflagellates.


Assuntos
Dinoflagelados , Saxitoxina , Dinoflagelados/genética , Expressão Gênica , Regulação da Expressão Gênica , Saxitoxina/toxicidade , Temperatura
2.
Sci Total Environ ; 804: 150252, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34798757

RESUMO

Microplastics (MPs) occur widely in marine environments, and disturb the balance of aquatic ecosystems. In this study, programmed cell apoptosis in marine dinoflagellate, Karenia mikimotoi exposed to 10 mg L-1 micro/nanoplastics (MPs/NPs; polystyrene and polymethyl methacrylate) for 72 h was assessed. Prior to the toxicity assay, MPs/NPs were dialyzed to remove possible additives. Cell viability, membrane integrity, cell apoptosis, and total DNA concentration were measured to assess programmed cell apoptosis in K. mikimotoi following exposure to MPs/NPs. A transcriptome analysis was used to explore the potential toxic mechanism of MPs to K. mikimotoi. Programmed cell apoptosis was related to the size of MPs/NPs, and NPs could more easily impair cell viability, and reduced cell membrane integrity and DNA concentration. NP particles caused continuous apoptosis of K. mikimotoi compared to MP particles. Size had the greatest effect on toxicity in K. mikimotoi. In conclusion, the results evidenced that both MPs and NPs have a negative impact on the marine dinoflagellate, K. mikimotoi. However, NPs were more harmful to K mikimotoi than MPs, highlighting the potential ecological problems associated with exposure to NPs.


Assuntos
Dinoflagelados , Apoptose , Ecossistema , Microplásticos , Plásticos
3.
Dis Aquat Organ ; 147: 13-23, 2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34734570

RESUMO

Perkinsus sp. protozoans are parasites of a wide variety of molluscs around the world and are responsible for episodes of mass mortalities and large economic losses for aquaculture industries and fisheries. The first step towards the management of infectious episodes is the reliable detection of Perkinsus species. While historic methods for diagnosis of Perkinsus sp. infections in mollusc hosts include histological, in vitro, molecular-genetic, and immunoassays, antibody-based diagnostic assays may prove most practical with development of improved reagents and techniques. This paper reviews historic developments of antibodies against Perkinsus species, and of diagnostic immunoassays. Thirteen research papers reported the development of antibodies against Perkinsus sp. or their extracellular products, mainly P. olseni and P. marinus. Nine of those tested the cross-reactivity of their antibodies against different life stages or species than the one used as immunogen. While all antibodies raised against trophozoites labelled hypnospores, several antibodies raised against hypnospores did not label trophozoites, suggesting antigenic differences between those cell types. Antibody specificity studies showed that there is antigenic heterogeneity between Perkinsus species and Perkinsus-like organisms, and also that common epitopes occur among Perkinsus species, as well as some dinoflagellates. This review summarizes the current knowledge and aims at helping the future development of Perkinsus species-specific antibodies and immunoassays.


Assuntos
Apicomplexa , Bivalves , Dinoflagelados , Animais , Aquicultura , Imunoensaio/veterinária , Moluscos
4.
Int J Syst Evol Microbiol ; 71(11)2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34739364

RESUMO

A Gram-stain-negative, aerobic, rod-shaped strain (R2A-3T) was isolated from the toxin-producing dinoflagellate Centrodinium punctatum and identified as a novel genus and new species based on a polyphasic taxonomic approach. The optimum conditions for growth of the strain were at 25 °C, pH 8.0 and in the presence of 3 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA genes and 92 core genes sets revealed that strain R2A-3T belongs to the family Nevskiaceae in the class Gammaproteobacteria and represented an independent taxon separated from other genera. The 16S rRNA gene of strain R2A-3T showed the highest sequence similarity to Polycyclovorans algicola TG408T (95.2%), Fontimonas thermophila HA-01T (94.1%) and Sinimarinibacterium flocculans NH6-24T (93.2%), and less than 92.8 % similarity to other genera in the family Nevskiaceae. The genome length of strain R2A-3T was 3608892 bp with 65.2 mol% G+C content. Summed feature 8 (comprising C18 : 1 ω7c and/or C18 : 1 ω6c) was the major fatty acid (>10 %). Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were detected as the major polar lipids. The major respiratory quinone was ubiquinone-8. According to its phylogenetic, phenotypic, chemotaxonomic and genomic features, strain R2A-3T represents a new species in the new genus of the family Nevskiaceae. It is recommended to name it Flagellatimonas centrodinii gen. nov., sp. nov. The type strain is R2A-3T (=KCTC 82469T=GDMCC 1.2523T).


Assuntos
Dinoflagelados , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Dinoflagelados/genética , Ácidos Graxos/química , Gammaproteobacteria , Fosfolipídeos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Ubiquinona
5.
Artigo em Inglês | MEDLINE | ID: mdl-34770163

RESUMO

Many Margalefidinium species are cosmopolitan harmful algal bloom (HAB) species that have caused huge economic and ecological damage. Despite extensive research on Margalefidinium species, the biodiversity and spatial-temporal dynamics of these species remain obscure. Jiaozhou Bay is an ideal area for HAB research, being one of the earliest marine survey areas in China. In this study, we carried out the first metabarcoding study on the temporal and spatial dynamics of Margalefidinium species using the 18S rDNA V4 region as the molecular marker and samples collected monthly at 12 sampling sites in Jiaozhou Bay in 2019. Two harmful Margalefidinium species (M. polykrikoides and M. fulvescens) were identified with potentially high genetic diversity (although we cannot rule out the possibility of intra-genome sequence variations). Both M. polykrikoides and M. fulvescens demonstrated strong temporal preference with a sharp peak of abundance in early autumn (September), but without showing strong location preference in Jiaozhou Bay. Our results revealed that temperature might be the main driver for their temporal dynamics. Knowledge of biodiversity and spatial-temporal dynamics of the Margalefidinium species may shed light on the understanding of mechanisms underlying strongly biased occurrences of Margalefidinium blooms recorded globally.


Assuntos
Baías , Dinoflagelados , Biodiversidade , China , Proliferação Nociva de Algas
6.
Artigo em Inglês | MEDLINE | ID: mdl-34769984

RESUMO

The Western Pacific is the most oligotrophic sea on Earth, with numerous seamounts. However, the plankton diversity and biogeography of the Western Pacific in general and the seamount regions in particular remains largely unexplored. In this project, we quantitatively analyzed the composition and distribution patterns of plankton species in the Western Pacific seamount regions by applying metabarcoding analysis. We identified 4601 amplicon sequence variants (ASVs) representing 34 classes in seven protist phyla/divisions in the Western Pacific seamount regions, among which Dinoflagellata was by far the most dominant division. Among the 336 annotated phytoplankton species (including species in Dinoflagellata), we identified 36 harmful algal bloom (HAB) species, many of which displayed unique spatial distribution patterns in the Western Pacific seamount regions. This study was the first attempt in applying ASV-based metabarcoding analysis in studying phytoplankton and HAB species in the Western Pacific seamount regions, which may facilitate further research on the potential correlation between HABs in the Western Pacific seamount regions and coastal regions.


Assuntos
Dinoflagelados , Proliferação Nociva de Algas , Planeta Terra , Fitoplâncton/genética , Plâncton/genética
7.
J Environ Sci (China) ; 109: 123-134, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34607661

RESUMO

Modified clay (MC), an effective material used for the emergency elimination of algal blooms, can rapidly reduce the biomass of harmful algal blooms (HABs) via flocculation. After that, MC can still control bloom population through indirect effects such as oxidative stress, which was initially proposed to be related to programmed cell death (PCD) at molecular level. To further study the MC induced cell death in residual bloom organisms, especially identifying PCD process, we studied the physiological state of the residual Prorocentrum donghaiense. The experimental results showed that flocculation changed the physiological state of the residual cells, as evidenced by growth inhibition and increased reactive oxygen species production. Moreover, this research provides biochemical and ultrastructural evidence showing that MC induces PCD in P. donghaiense. Nuclear changes were observed, and increased caspase-like activity, externalization of phosphatidylserine and DNA fragmentation were detected in MC-treated groups and quantified. And the mitochondrial apoptosis pathway was activated in both MC-treated groups. Besides, the features of MC-induced PCD in a unicellular organism were summarized and its concentration dependent manner was proved. All our preliminary results elucidate the mechanism through which MC can further control HABs by inducing PCD and suggest a promising application of PCD in bloom control.


Assuntos
Dinoflagelados , Apoptose , Argila , Floculação , Proliferação Nociva de Algas
8.
Toxicon ; 203: 104-114, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34662628

RESUMO

We evaluated the accumulation of okadaic acid (OA), a diarrhetic toxin, and the antioxidant responses in the marine annelid Laeonereis acuta exposed to the benthic toxigenic dinoflagellate Prorocentrum cf. lima. Nontoxic Tetraselmis sp. was used as a control diet. Living cells of the two algae were supplied as food to animals kept in agar medium for 72 h. To assess the significance of the observed effects, our experimental design treated the algal species (diet), algal cell densities, and exposure time as fixed factors. Responses of the organisms were assessed through oxidative stress biomarkers (glutathione-S-transferase [GST], catalase [CAT], reduced glutathione [GSH] and lipid peroxidation [LPO]). Toxin accumulation was measured by LC-MS/MS in whole-body homogenates after 12, 24 and 72 h of exposure. Worms exposed to the toxigenic dinoflagellate gradually accumulated OA, with toxin levels directly related to the cell density of Prorocentrum cf. lima. Worms fed with Prorocentrum cf. lima exhibited decreased CAT activity, increased LPO levels - both interactively affected by algal species and time - and decreased GSH levels, which were interactively affected by algal species and cell density. Higher LPO levels, along with the inhibition of CAT and GSH, clearly indicated an oxidative stress situation in worms exposed to the toxigenic dinoflagellate. Laeonereis acuta accumulated moderate OA levels and may act as a vector of OA to food webs in estuarine areas under high Prorocentrum cf. lima abundance.


Assuntos
Anelídeos , Dinoflagelados , Animais , Antioxidantes , Cromatografia Líquida , Ácido Okadáico/toxicidade , Espectrometria de Massas em Tandem
9.
Ecotoxicol Environ Saf ; 227: 112905, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34673413

RESUMO

Diarrheic shellfish poisoning (DSP) toxins are widely distributed over the world, causing diarrhea, vomiting, and even tumor in human. However, bivalves, the main carrier of the DSP toxins, have some tolerant mechanisms to DSP toxins, though it remains unclear. In this study, we scrutinized the role of Jun N-terminal kinases (JNK) in tolerance of DSP toxins and the relationship between JNK, apoptosis and nuclear factor E2-related factor/antioxidant response element (Nrf2/ARE) pathways. We found that the phosphorylated level of JNK protein was significantly increased both in hemocytes (6 h) and gills (3 h) of the mussel Perna viridis after short-term exposure to DSP toxins-producing dinoflagellate Prorocentrum lima. Exposure of P. lima induced oxidative stress in mussels. Hemocytes and gills displayed different sensitivities to the cytotoxicity of DSP toxins. Exposure of P. lima activated caspase-3 and induced apoptosis in gills but did not induce caspase-3 and apoptosis in hemocytes. The short-term exposure of P. lima could activate Nrf2/ARE signaling pathway in hemocytes (6 h), while longer-term exposure could induce glutathione reductase (GR) expression in hemocytes (96 h) and glutathione-S-transferases (GST) in gills (96 h). Based on the phylogenetic tree of Nrf2, Nrf2 in P. viridis was closely related to that in other mussels, especially Mytilus coruscus, but far from that in Mus musculus. The most likely phosphorylated site of Nrf2 in the mussels P. viridis is threonine 504 for JNK, which is different from that in M. musculus. Taken all together, the tolerant mechanism of P. viridis to DSP toxins might be involved in JNK and Nrf2/ARE signaling pathways, and JNK play a key role in the mechanism. Our findings provide a new clue to further understand tolerant mechanisms of bivalves to DSP toxins.


Assuntos
Dinoflagelados , Perna (Organismo) , Animais , Humanos , Sistema de Sinalização das MAP Quinases , Toxinas Marinhas/toxicidade , Camundongos , Filogenia
10.
Eur J Protistol ; 81: 125835, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34715455

RESUMO

Thecadinium is a morphologically heterogenous marine benthic genus. Its polyphyly has been discussed. After redefinition of the sensu stricto genus, sensu lato taxa now need reclassification. Heterotrophic, morphologically closely related species were studied in detail. Molecular phylogenetic data for three of the four known species (T. ornatum, T. acanthium, T. ovatum) and new morphological data were obtained, leading to an emended thecal plate pattern, including the presence of an apical pore complex and an additional hypothecal plate. The results confirm the close relationship of the species and justify the description of Carinadinium gen. nov., characterized by the tabulation APC 3/4' 1/0a 6″ 6c 5s 5‴ 2'‴, an epithecal plate of special morphology, an apical flange, a ventral pore, antapical appendages, a descending cingulum and lateral cell flattening. The genus can be separated into two sub-clades, one with a third precingular 'dimple'-plate, four apical and no anterior intercalary plates and the other with a 'multi-pimple'-plate as third precingular or its homolog plate, three apical and one anterior intercalary plate. Carinadinium is phylogenetically related to the planktonic genera Protoceratium, Pentaplacodinium, and Ceratocorys (family Protoceratiaceae), and clearly belongs into the order Gonyaulacales, but with uncertain family affiliation.


Assuntos
Dinoflagelados , Dinoflagelados/genética , Filogenia , Plâncton
11.
PLoS One ; 16(10): e0259161, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34705875

RESUMO

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.


Assuntos
Biomassa , Dinoflagelados/metabolismo , Eutrofização , Dióxido de Carbono/metabolismo , Dinoflagelados/crescimento & desenvolvimento , Temperatura Alta , Nitrogênio/metabolismo , Luz Solar
12.
Aquat Toxicol ; 240: 105985, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34634712

RESUMO

Alexandrium affine is a global harmful algal bloom (HAB)-forming dinoflagellate. In this study, the effect of non-toxin-producing A. affine on the gill and liver tissues of red seabream, Pagrus major, was analyzed over 24 h exposure and 2 h depuration phases. After exposure to three concentrations of A. affine (4,000, 6,000, and 7,000 cells mL-1), survival rates, respiration rates, immunities (lysozyme, total Ig), hepatic biomarkers (alanine aminotransferase, ALT; aspartate aminotransferase, AST; and alkaline phosphatase, ALP), lipid peroxidation (malondialdehyde, MDA), and antioxidant defense systems (glutathione, GSH; catalase, CAT; superoxide dismutase, SOD; glutathione peroxidases, GPx; and glutathione reductase, GR) were analyzed in gill and liver tissues. Dose-dependent decreases in survival and respiration rates were detected in red seabream. A. affine levels of to 6,000 and 7,000 cells mL-1 induced immunosuppression and hepatic impairment in both tissues, as measured by significant decreases in lysozyme activity, total Ig level, ALT, AST, and ALP content. The levels of GSH, CAT, SOD, GPx, and GR were significantly decreased in the gills and liver in response to 7,000 cells mL-1 of A. affine at 24 h, and MDA was elevated. However, different response patterns were observed between tissues in response to 4,000 cells mL-1. Activity of antioxidant defense enzymes was significantly elevated in the liver but decreased in the gills. This suggests that the gills were more vulnerable than the liver. In the case of 6,000 and 7,000 cells mL-1 treatments, higher susceptibility was also detected at 3 h in the gill compared to the overall responses of each parameter measured in liver. Taken together, direct attachment of A. affine to the gill tissue strongly affects immunity and antioxidant capacity of red seabream even after a short exposure period. These results could be helpful for understanding HAB-mediated effects in marine fish.


Assuntos
Dinoflagelados , Dourada , Poluentes Químicos da Água , Animais , Antioxidantes/metabolismo , Catalase/metabolismo , Dinoflagelados/metabolismo , Brânquias/metabolismo , Imunidade Inata , Peroxidação de Lipídeos , Fígado/metabolismo , Estresse Oxidativo , Dourada/metabolismo , Superóxido Dismutase/metabolismo , Poluentes Químicos da Água/efeitos adversos
13.
Nat Commun ; 12(1): 5731, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34593802

RESUMO

As coral reefs struggle to survive under climate change, it is crucial to know whether they have the capacity to withstand changing conditions, particularly increasing seawater temperatures. Thermal tolerance requires the integrative response of the different components of the coral holobiont (coral host, algal photosymbiont, and associated microbiome). Here, using a controlled thermal stress experiment across three divergent Caribbean coral species, we attempt to dissect holobiont member metatranscriptome responses from coral taxa with different sensitivities to heat stress and use phylogenetic ANOVA to study the evolution of gene expression adaptation. We show that coral response to heat stress is a complex trait derived from multiple interactions among holobiont members. We identify host and photosymbiont genes that exhibit lineage-specific expression level adaptation and uncover potential roles for bacterial associates in supplementing the metabolic needs of the coral-photosymbiont duo during heat stress. Our results stress the importance of integrative and comparative approaches across a wide range of species to better understand coral survival under the predicted rise in sea surface temperatures.


Assuntos
Aclimatação/genética , Antozoários/microbiologia , Dinoflagelados/genética , Resposta ao Choque Térmico , Microbiota/genética , Animais , Antozoários/fisiologia , Região do Caribe , Recifes de Corais , Dinoflagelados/metabolismo , Evolução Molecular , Redes e Vias Metabólicas/genética , Fotossíntese/genética , Filogenia , Simbiose/genética
14.
Environ Monit Assess ; 193(10): 648, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34523030

RESUMO

Harmful algal blooms (HABs) have been serious environmental problems in the Persian Gulf and Oman Sea in recent years. There has been an increase in occurrence of HABs in coastal waters of Hormuzgan Province (to the north of the Persian Gulf and Oman Sea) in recent decade, due to eutrophication as a result of human activities. In this review, HAB phenomena in coastal waters of Hormuzgan Province are summarized, including, causative species, timing and the location of blooms during a 35-year time span from 1980 to 2015. This review illustrates that 436 algal blooms have been recorded in the north of the Persian Gulf, formed by 17 species of phytoplankton; 270 of harmful dinoflagellate (Margalefidinium polykrikoides) blooms have led to huge catastrophic impacts on the economy, environment, and society. In addition, most algal blooms (49%) have occurred in the coasts of Bandar Abbas. The data in this review suggest supporting the establishment of an algal bloom monitoring and control program in the coastal waters of the northern part of the Persian Gulf and Oman Sea (Hormuzgan Province).


Assuntos
Dinoflagelados , Monitoramento Ambiental , Surtos de Doenças , Proliferação Nociva de Algas , Humanos , Oceano Índico , Omã
15.
Curr Microbiol ; 78(11): 3996-4003, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34522978

RESUMO

Marine phycosphere hosts cross-kingdom algae-bacteria interactions playing a variety of crucial roles in aquatic ecosystems especially for the prevention and control of harmful algal blooms (HABs). During the investigation of structural composition of phycosphere microbiota (PM) of diverse marine HAB dinoflagellates, a Gram-negative, strictly aerobic, non-motile and rod-shaped bacterium designated LZ-17T was isolated from the phycosphere of highly toxic Alexandrium catenella LZT09. The 16S rRNA gene sequence analysis and the multilocus sequence analysis (MLSA) based on five protein-coding housekeeping genes (atpD, gyrB, mutL, topA and rpoD) indicated that strain LZ-17T was affiliated to the genus Maritimibacter within the family Rhodobacteraceae, and closely related to Maritimibacter alkaliphilus HTCC2654T (99.1%), 'Maritimibacter harenae' DP07T (97.9%) and M. lacisalsi X12M-4T (95.7%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain LZ-17T and the type strain of M. alkaliphilus were 96.9% and 74.7%. However, strain LZ-17T could be clearly distinguished from its closest by the phenotypical and phenotypical characteristics. Strain LZ-17T contained Q-10 as its major isoprenoid quinone, and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), C16:0 and C16:0 2-OH as the predominant fatty acids (>10%). The major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylcholine. The DNA G + C content was 64.3 mol%. Based on the polyphasic taxonomic characterization, strain LZ-17T represents a novel species of the genus Maritimibacter, for which the name Maritimibacter alexandrii sp. nov. is proposed, with the type strain LZ-17T (=CCTCC 2019005T = KCTC 72193T).


Assuntos
Dinoflagelados , Microbiota , Rhodobacteraceae , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Ácidos Graxos , Fosfolipídeos , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
16.
Water Res ; 204: 117625, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34530224

RESUMO

Coastal harmful algal blooms (HABs), commonly termed 'red tides', have severe undesirable consequences to the marine ecosystems and local fishery and tourism industries. Increase in nitrogen and/or phosphorus loading is often regarded as the major culprits of increasing frequency and intensity of the coastal HAB; however, fundamental understanding is lacking as to the causes and mechanism of bloom formation despite decades of intensive investigation. In this study, we interrogated the prokaryotic microbiomes of surface water samples collected at two neighboring segments of East China Sea that contrast greatly in terms of the intensity and frequency of Prorocentrum-dominated HAB. Mantel tests identified significant correlations between the structural and functional composition of the microbiomes and the physicochemical state and the algal biomass density of the surface seawater, implying the possibility that prokaryotic microbiota may play key roles in the coastal HAB. A conspicuous feature of the microbiomes at the sites characterized with high trophic state index and eukaryotic algal cell counts was disproportionate proliferation of Vibrio spp., and their complete domination of the functional genes attributable to the dissimilatory nitrate reduction to ammonia (DNRA) pathway substantially enriched at these sites. The genes attributed to phosphorus uptake function were significantly enriched at these sites, presumably due to the Pi-deficiency induced by algal growth; however, the profiles of the phosphorus mineralization genes lacked consistency, barring any conclusive evidence with regard to contribution of prokaryotic microbiota to phosphorus bioavailability. The results of the co-occurrence network analysis performed with the core prokaryotic microbiome supported that the observed proliferation of Vibrio and HAB may be causally associated. The findings of this study suggest a previously unidentified association between Vibrio proliferation and the Prorocentrum-dominated HAB in the subtropical East China Sea, and opens a discussion regarding a theoretically unlikely, but still possible, involvement of Vibrio-mediated DNRA in Vibrio-Prorocentrum symbiosis. Further experimental substantiation of this supposed symbiotic mechanism may prove crucial in understanding the dynamics of explosive local algal growth in the region during spring algal blooms.


Assuntos
Dinoflagelados , Microbiota , Vibrio , Proliferação de Células , Dinoflagelados/genética , Proliferação Nociva de Algas
17.
Aquat Toxicol ; 239: 105950, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34474269

RESUMO

Diarrheic shellfish poisoning toxins (DSP toxins) are a set of the most important phycotoxins produced by some dinoflagellates. Studies have shown that DSP toxins have various toxicities such as genotoxicity, cytotoxicity, and immunotoxicity to bivalve mollusks. However, these toxicities appear decreasing with exposure time and concentration of DSP toxins. The underlying mechanism involved remains unclear. In this study, small RNA sequencing was performed in the digestive gland of the mussel Perna viridis after exposure to DSP toxins-producing dinoflagellate Prorocentrum lima for different time periods. The potential roles of miRNAs in response and detoxification to DSP toxins in the mussel were analyzed. Small RNA sequencing of 12 samples from 72 individuals was conducted by BGISEQ-500. A total of 123 mature miRNAs were identified, including 90 conserved miRNAs and 33 potential novel miRNAs. After exposure to P. lima, multiple important miRNAs displayed some alterations. Further miRNA target prediction revealed some important genes involved in cytoskeleton, apoptosis, complement system and immune stress. qPCR demonstrated that miR-71_5, miR-750_1 and novel_mir4 were significantly up-regulated at 6 h after exposure to P. lima, while miR-100_2 was significantly down-regulated after 96 h of exposure. Accordingly, putative target genes of these differentially expressed miRNAs experienced some changes. After 6 h of DSP toxins exposure, NHLRC2 and C1q-like were significantly down-regulated. After 96 h of DSP toxins exposure, NHLRC2 was significantly up-regulated. It is reasonable to speculate that the mussel P. viridis might respond to DSP toxins through miR-750_1, novel_mir4 and miR-71_5 regulating the expression of relevant target genes involved in apoptosis, cytoskeleton, and immune response, etc. This study might provide new clues to uncover the toxic response of bivalve to DSP toxins and lay a foundation for revealing the roles of miRNAs in the environmental adaptation in shellfish.


Assuntos
Dinoflagelados , MicroRNAs , Perna (Organismo) , Intoxicação por Frutos do Mar , Poluentes Químicos da Água , Animais , Dinoflagelados/genética , Humanos , Toxinas Marinhas/toxicidade , MicroRNAs/genética , Perna (Organismo)/genética , Poluentes Químicos da Água/toxicidade
18.
Physiol Biochem Zool ; 94(6): 394-410, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34542375

RESUMO

AbstractReactive oxygen species (ROS) may damage cellular components but may also contribute to signaling that mitigates damage. In this context, the role of ROS in the stress response that leads to coral bleaching was investigated in three series of experiments with octocorals Sarcothelia sp. and Sympodium sp. Using video and fluorescent microscopy, the first experiments examined ROS and symbiont migration. Colonies mildly stressed with increased temperature and light showed increases in both ROS and numbers of migrating symbionts compared with stress-free controls. Symbionts migrating in the gastrovascular lumen may escape programmed cell death and provide a reservoir of healthy symbionts once conditions return to normal. In the second series of experiments, colonies were mildly stressed with elevated temperature and light. During stress, treated colonies were incubated in seawater enriched with two concentrations of bicarbonate (1 and 3 mmol/L), while controls were incubated in normal seawater. Bicarbonate enrichment provides additional carbon for photosynthesis and at some concentrations diminished the ROS emissions of stressed colonies of Sympodium sp. and Sarcothelia sp. In all experiments, the latter species tended to exhibit more ROS. Sympodium sp. contains Cladocopium sp. symbionts, which are less tolerant of stress, while Sarcothelia sp. contains the more resistant Durusdinium sp. Indeed, in direct comparisons, Sarcothelia sp. experienced higher levels of ROS under stress-free conditions and thus is conditioned to endure the stress associated with bleaching. Generally, ROS levels provide important insight into the cnidarian stress response and should be measured more often in studies of this response.


Assuntos
Antozoários , Dinoflagelados , Animais , Temperatura Alta , Espécies Reativas de Oxigênio , Simbiose
19.
Harmful Algae ; 108: 102096, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34588118

RESUMO

Marine microalgae produce a variety of specialised metabolites that have toxic effects on humans, farmed fish, and marine wildlife. Alarmingly, many of these compounds bioaccumulate in the tissues of shellfish and higher trophic organisms, including species consumed by humans. Molecular methods are emerging as a potential alternative and complement to the conventional microscopic diagnosis of toxic or otherwise harmful microalgal species. Quantitative PCR (qPCR) in particular, has gained popularity over the past decade as a sensitive, rapid, and cost-effective method for monitoring harmful microalgae. Assays targeting taxonomic marker genes provide the opportunity to identify and quantify (or semi-quantify) microalgal species and importantly to pre-empt bloom events. Moreover, the discovery of paralytic shellfish toxin biosynthesis genes in dinoflagellates has enabled researchers to directly monitor toxigenic species in coastal waters and fisheries. This review summarises the recent developments in qPCR detection methods for harmful microalgae, with emphasis on emerging toxin gene monitoring technologies.


Assuntos
Dinoflagelados , Microalgas , Animais , Dinoflagelados/genética , Pesqueiros , Microalgas/genética , Reação em Cadeia da Polimerase em Tempo Real , Frutos do Mar
20.
Harmful Algae ; 108: 102097, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34588119

RESUMO

The effects of harmful algae on bivalve physiology are complex and involve both physiological and behavioural responses. Studying those responses is essential to better describe and predict their impact on shellfish aquaculture and health risk for humans. In this study we recorded for two months the physiological response of the blue mussel Mytilus edulis from Eastern Canada to a one-week exposure to a paralytic shellfish poisoning producing dinoflagellate strain of Alexandrium catenella, isolated from the St Lawrence estuary, Canada. Mussels in a 'control' treatment were fed continuously with a non-toxic diet, while mussels in a 'starvation' treatment were fed the same non-toxic diet the first week and subsequently starved for seven weeks. Mussels in a 'toxic' treatment received A. catenella for one week before being starved until the end of the experiment. Over a two-month experiment we monitored shell and tissue growth, filtration capacity, respiration rate, byssal attachment strength, valve opening behaviour, and toxin content in tissues. Mussels fed normally on the toxic dinoflagellate and accumulated an average of 51.6 µg STXeq 100 g-1 after one week of exposure. After seven weeks of depuration, about half of the specimen showed levels around 18 µg STXeq 100 g-1. The condition index of exposed mussels ('toxic' treatment) decreased rapidly from the start as compared to mussels that received a one-week non-toxic diet ('starvation' treatment). Oxygen consumption rates increased in the 'toxic' treatment before leveling out with that of mussels from the 'starvation' treatment. Valve opening amplitude was lower in the 'toxic' treatment during and following the exposure. Average valve closure duration was higher right after the exposure, during the peak of mussel tissue intoxication. No significant change in byssal thread strength was observed through time in each treatment but less force was required to detach mussels from the 'toxic' and 'starvation' treatments. The number of byssus threads produced by mussels exposed to the toxic dinoflagellate was also lower than in the control group. These results represent advancements in our understanding of the impacts of harmful algae on bivalves and contribute to the development of mitigation measures necessary to both the safety of consumers and the sustainability of aquaculture operations.


Assuntos
Dinoflagelados , Mytilus , Intoxicação por Frutos do Mar , Animais , Toxinas Marinhas , Alimentos Marinhos
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