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1.
Mar Environ Res ; 160: 105010, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32907730

RESUMO

The underlying mechanisms of bacterioplankton community assembly and interspecies interactions during harmful algal blooms remain largely unclear. Using 16S rRNA gene amplicon sequencing, we analyzed the bacterioplankton communities over the continuous course of saxitoxin-producing Gymnodinium catenatum blooms and two diatom (i.e., Skeletonema costatum and Chaetoceros curvisetus) blooms in an anthropogenically controlled and eutrophic bay, East China Sea. The succession of bacterioplankton communities correlated with changes in the dynamics of algal species. Deterministic versus stochastic bacterioplankton community assemblage processes were quantified, demonstrating that stochastic processes increased when algal blooms happened. The occurrence of algal blooms caused weaker bacterioplankton interspecies interactions and higher degrees of cooperative activities, changed keystone taxa and diminished the stability of bacterial communities. These findings consequently have important implications for our understanding of bacterioplankton community ecology during algal blooms.


Assuntos
Diatomáceas , Dinoflagelados , Proliferação Nociva de Algas , China , Dinoflagelados/genética , Dinoflagelados/crescimento & desenvolvimento , RNA Ribossômico 16S
2.
Aquat Toxicol ; 227: 105591, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32853898

RESUMO

The effects of allelopathy and the potential harm of several isolated allelochemicals have been studied in detail. Microorganisms in the phycosphere play an important role in algal growth, decay and nutrient cycling. However, it is unknown and often neglected whether allelochemicals affect the phycosphere. The present study selected a phenolic acid protocatechuic acid (PA) - previously shown to be an allelochemical. We studied PA at a half maximal effective concentration of 0.20 mM (30 mg L-1) against Scrippsiella trochoidea to assess the effect of PA on its phycosphere in an acute time period (48 h). The results showed that: 1) OTUs (operational taxonomic units) in the treatment groups (31.4 ± 0.55) exceeded those of the control groups (28.2 ± 1.30) and the Shannon and Simpson indices were lower than the control groups (3.31 ± 0.08 and 0.84 ± 0.02, 3.45 ± 0.09 and 0.88 ± 0.01); 2) Gammaproteobacteria predominated in the treatment groups (44.71 ± 2.13 %) while Alphaproteobacteria dominated in the controls (67.17 ± 3.87 %); 3) Gammaproteobacteria and Alphaproteobacteria were important biomarkers in the treatment and control groups respectively (LDA > 4.0). PA improved the relative abundance of Alteromonas significantly and decreased the one of Rhodobacteraceae. PICRUSt analysis showed that the decrease of Rhodobacterceae was closely related with the decline of most functional genes in metabolism such as amino acid, carbohydrate, xenobiotics, cofactors and vitamins metabolism after PA-treated.


Assuntos
Alelopatia/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos dos fármacos , Hidroxibenzoatos/farmacologia , Microbiota/efeitos dos fármacos , Feromônios/farmacologia , Alelopatia/genética , Bacteroidetes/efeitos dos fármacos , Bacteroidetes/genética , Bacteroidetes/isolamento & purificação , Dinoflagelados/genética , Dinoflagelados/crescimento & desenvolvimento , Microbiota/genética , Proteobactérias/efeitos dos fármacos , Proteobactérias/genética , Proteobactérias/isolamento & purificação
3.
Aquat Toxicol ; 222: 105454, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32179335

RESUMO

Recent oil spill responses such as the Deepwater Horizon event have underscored the need for crude oil ecotoxicological threshold data for shallow water corals to assist in natural resource damage assessments. We determined the toxicity of a mechanically agitated oil-seawater mixture (high-energy water-accommodated fraction, HEWAF) of a sweet crude oil on a branched stony coral, Pocillopora damicornis. We report the results of two experiments: a 96 h static renewal exposure experiment and a "pulse-chase" experiment of three short-term exposure durations followed by a recovery period in artificial seawater. Five endpoints were used to determine ecotoxicological values: 1) algal symbiont chlorophyll fluorescence, 2) a tissue regeneration assay and a visual health metric with three endpoints: 3) tissue integrity, 4) tissue color, and 5) polyp behavior. The sum of 50 entrained polycyclic aromatic hydrocarbons (tPAH50) was used as a proxy for oil exposure. For the 96 h exposure dose response experiment, dark-adapted maximum quantum yield (Fv/Fm) of the dinoflagellate symbionts was least affected by crude oil (EC50 = 913 µg/L tPAH50); light-adapted effective quantum yield (EQY) was more sensitive (EC50 =  428 µg/L tPAH50). In the health assessment, polyp behavior (EC50 = 27 µg/L tPAH50) was more sensitive than tissue integrity (EC50 = 806 µg/L tPAH50) or tissue color (EC50 = 926 µg/L tPAH50). Tissue regeneration proved to be a particularly sensitive measurement for toxicity effects (EC50 = 10 µg/L tPAH50). Short duration (6-24 h) exposures using 503 µg/L tPAH50 (average concentration) resulted in negative impacts to P. damicornis and its symbionts. Recovery of chlorophyll a fluorescence levels for 6-24 h oil exposures was observed in a few hours (Fv/Fm) to several days (EQY) following recovery in fresh seawater. The coral health assessments for tissue integrity and tissue color were not affected following short-term oil exposure durations, but the 96 h treatment duration resulted in significant decreases for both. A reduction in polyp behavior (extension) was observed for all treatment durations, with recovery observed for the short-term (6-24 h) exposures within 1-2 days following placement in fresh seawater. Wounded and intact fragments exposed to oil treatments were particularly sensitive, with significant delays observed in tissue regeneration. Estimating ecotoxicological values for P. damicornis exposed to crude oil HEWAFs provides a basis for natural resource damage assessments for oil spills in reef ecosystems. These data, when combined with ecotoxicological values for other coral reef species, will contribute to the development of species sensitivity models.


Assuntos
Antozoários/efeitos dos fármacos , Monitoramento Biológico/métodos , Recifes de Corais , Petróleo/toxicidade , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Antozoários/crescimento & desenvolvimento , Antozoários/metabolismo , Clorofila A/metabolismo , Dinoflagelados/efeitos dos fármacos , Dinoflagelados/crescimento & desenvolvimento , Ecossistema , Louisiana , Poluição por Petróleo/análise , Água do Mar/química
4.
PLoS One ; 15(3): e0229556, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32196504

RESUMO

The heterotrophic microalgae Crypthecodinium cohnii was usually cultivated in complex medium containing glucose, yeast extract and sea salt. For the preparation of DHA with highest purity, a new defined medium without the yeast extract was developed. Different inoculated densities, C/N ratios, temperatures, culture volumes and glucose additions were investigated to optimize the algal growth rate and DHA production. The growth period in C. cohnii was shortened from 12-14 days to 7-8 days, the OD600 was enhanced from 2.0 to 3.0, the glucose consumption was accelerated and used up on day 3-4, and the DHA content in culture were increased from 10 to 45 nmoles/300 µl batch. It was found that C. cohnii had optimal growth and DHA accumulation in 25 °C, 0.2 inoculated density, 5-10 C/N ratio, 5:1 air/culture volume ratio. This is the first time DHA production using C.cohnii has been optimized in synthetic medium. This allows preparation of uniformly radiolabeled 13C- and 14C-DHA.


Assuntos
Meios de Cultura/química , Dinoflagelados/crescimento & desenvolvimento , Ácidos Docosa-Hexaenoicos/biossíntese , Biomassa , Dinoflagelados/metabolismo , Fermentação/fisiologia , Microalgas/crescimento & desenvolvimento
5.
Mar Pollut Bull ; 151: 110825, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056617

RESUMO

The emergence of a red tide resulting in yellow-brownish discoloration of waters in Porto Cesareo bay (Italy) during July-August 2018 is reported. The species responsible for the bloom was the dinoflagellate Margalefidinium cf. polykrikoides. Cell densities reached 9.1 × 106 cells L-1 during the initial outbreak. A second peak was observed about three weeks later reaching 6.7 × 105 cells L-1. Study of live specimens showed great variation in cell size and shape. Different cyst morphotypes were found in the water samples and in the sediment. For the first time, we followed several stages of the life cycle of M. cf. polykrikoides in natural samples. Fish die-offs in the bay were not observed, however this high-density bloom may have caused consequences on the ecosystem (amount of mucilage on the beach) and in turn, on tourism that is the main activity in the area during the summer season.


Assuntos
Dinoflagelados/crescimento & desenvolvimento , Ecossistema , Monitoramento Ambiental , Animais , Baías , Proliferação Nociva de Algas , Itália , Mar Mediterrâneo , Água do Mar
6.
Nat Commun ; 11(1): 108, 2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31913264

RESUMO

In cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases.


Assuntos
Dinoflagelados/fisiologia , Anêmonas-do-Mar/metabolismo , Simbiose , Animais , Carbono/metabolismo , Dinoflagelados/genética , Dinoflagelados/crescimento & desenvolvimento , Glutamato Sintase/genética , Glutamato Sintase/metabolismo , Glutamato-Amônia Ligase/genética , Glutamato-Amônia Ligase/metabolismo , Nitrogênio/metabolismo , Anêmonas-do-Mar/enzimologia , Anêmonas-do-Mar/genética
7.
Ecotoxicol Environ Saf ; 191: 110226, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31981955

RESUMO

Since 2006, harmful dinoflagellate blooms of Cochlodinium geminatum have infrequently occurred in the Pearl River Estuary, South China. During late October to early November in 2018, C. geminatum blooms occurred again in the region. To investigate the blooming mechanism in certain temporal conditions, we analysed the changes in the environmental parameters and phytoplankton community structure during and after the bloom. The results indicated that the water temperature and salinity had large impacts on the bloom. During the C. geminatum bloom, the phytoplankton community structure changed and the number of dominant species decreased. After the bloom, the species number and abundance of diatoms increased, as the species diversity was recovering. Retinal was detected in the field samples and cultured C. geminatum. It has been demonstrated to exist in some algae species (e.g. Cyanophyta, Chlorophyta, Bacillariophyta, and Euglenophyt), and our results indicates that such teratogens also exist in dinoflagellates. The highest concentration of retinal was detected during the bloom. This result indicates that the retinal content may accumulate during a bloom. Retinal has been demonstrated to be a teratogenic agent and may therefore present a potential risk to aquatic organisms during a bloom episode. This research provided more comprehensive information concerning the ecological influences of C. geminatum blooms.


Assuntos
Dinoflagelados/química , Dinoflagelados/crescimento & desenvolvimento , Estuários , Retinoides/análise , Teratogênios/análise , China , Clorófitas/química , Diatomáceas/isolamento & purificação , Fenômenos Ecológicos e Ambientais , Fitoplâncton/isolamento & purificação , Rios , Salinidade
8.
Ecotoxicol Environ Saf ; 190: 110180, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31927195

RESUMO

This paper studied the allelopathic effect of Cylindrotheca closterium on the growth of Prorocentrum donghaiense, the model of harmful algal blooms in aquatic environment, by the co-culture tests and bioassay-guided fraction methods. The growth of P. donghaiense in co-cultures was observably suppressed by C. closterium, and P. donghaiense biomass in C/P = 3: 1 group increased slowly with a low growth rate of 0.18 d-1 after 4 days. Petroleum ether (PE) extract derived from C. closterium filtrates was isolated by C18 column and the allelopathy of all isolated fractions for P. donghaiense was investigated. After 96 h cultivation, the inhibition ratio of PE-Ⅲ and PE-Ⅷ fractions on P. donghaiense could reach up to 70.2% and 64.3% at the concentration of 10-fold when compared to control, while the other fractions displayed relatively low inhibitory effects on P. donghaiense. PE-Ⅲ and PE-Ⅷ fractions also decreased the chlorophyll content and maximum quantum yield of photosystem II (Fv/Fm) of P. donghaiense cells. The activities of superoxide dismutase (SOD), one of antioxidant enzymes, reduced around 8.3% and 13.7% following exposure to 2-fold PE-Ⅲ and PE-Ⅷ, and was significantly decreased following higher exposure concentrations. After 96 h of 10-fold PE-Ⅲ and PE-Ⅷ treatments, Catalase (CAT) activity reduced to 44.86% and 46.42% of that observed in the control group. At the same time, a significant increase in malondialdehyde (MDA) contents was observed. These findings suggested that PE-Ⅲ and PE-Ⅷ fractions contained main allelochemicals and possibly acted as promising algistatic agents for emergency handling of P. donghaiense blooms.


Assuntos
Diatomáceas/química , Dinoflagelados/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos dos fármacos , Herbicidas/farmacologia , Feromônios/farmacologia , Alelopatia , Biomassa , Clorofila/metabolismo , Dinoflagelados/crescimento & desenvolvimento , Herbicidas/isolamento & purificação , Feromônios/isolamento & purificação , Complexo de Proteína do Fotossistema II/metabolismo
9.
Aquat Toxicol ; 218: 105371, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31790939

RESUMO

Harmful algal bloom (HAB) toxins have severe negative impacts on marine mammals, particularly for Florida bottlenose dolphins (Tursiops truncatus) which frequently experience mass mortality events. Dolphins on the Florida Atlantic coast inhabit a region endemic to two HAB species, Karenia brevis and Pyrodinium bahamense, which produce the neurotoxins brevetoxin (PbTx) and saxitoxin (STX), respectively. Although toxic HABs and associated dolphin mortality events have been reported from this region, there is a lack of available data necessary for comparing toxin exposure levels between bloom ('exposed') conditions and non-bloom ('baseline') conditions. Here we present a 10-year dataset of PbTx and STX concentrations detected in dolphins stranding in this region, and compare the toxin loads from HAB-exposed dolphins to those detected in dolphins recovered in the absence of a HAB. We analyzed liver tissue samples from dead-stranded dolphins (n = 119) recovered and necropsied between 2002-2011, using an enzyme-linked immunosorbent assay (ELISA) modified for use with mammalian tissues. For dolphins recovered during baseline conditions, toxin-positive samples ranged in concentration from 0.27 to 1.2 ng/g for PbTx and from 0.41 to 1.9 ng/g for STX. For K. brevis-exposed dolphins, concentrations of up to 12.1 ng PbTx/g were detected, and for P. bahamense-exposed dolphins, concentrations of up to 9.9 ng STX/g were detected. Baseline PbTx values were similar to those reported in other regions where K. brevis blooms are more frequent and severe, but HAB-exposed PbTx values were considerably lower relative to these other regions. Since no baseline STX dolphin data exist for any region, our data serve as a first step towards establishing reference STX values for potential dolphin mortality events associated with STX-producing blooms in the future. This study demonstrates that although HABs in eastern Florida are only infrequently associated with dolphin mortalities, the presence of toxins in these animals may pose significant health risks in this region.


Assuntos
Golfinho Nariz-de-Garrafa/metabolismo , Monitoramento Ambiental/métodos , Proliferação Nociva de Algas , Toxinas Marinhas/análise , Oxocinas/análise , Saxitoxina/análise , Poluentes Químicos da Água/análise , Animais , Dinoflagelados/crescimento & desenvolvimento , Ensaio de Imunoadsorção Enzimática , Florida , Fígado/química , Fígado/metabolismo , Toxinas Marinhas/toxicidade , Oxocinas/toxicidade , Rios/química , Saxitoxina/toxicidade , Poluentes Químicos da Água/toxicidade
10.
Toxins (Basel) ; 11(12)2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31861242

RESUMO

Ciguatera poisoning (CP) is a foodborne disease caused by the consumption of seafood contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genera Gambierdiscus and Fukuyoa. The toxin production and toxin profiles were explored in four clones of G. polynesiensis originating from different islands in French Polynesia with contrasted CP risk: RIK7 (Mangareva, Gambier), NHA4 (Nuku Hiva, Marquesas), RAI-1 (Raivavae, Australes), and RG92 (Rangiroa, Tuamotu). Productions of CTXs, maitotoxins (MTXs), and gambierone group analogs were examined at exponential and stationary growth phases using the neuroblastoma cell-based assay and liquid chromatography-tandem mass spectrometry. While none of the strains was found to produce known MTX compounds, all strains showed high overall P-CTX production ranging from 1.1 ± 0.1 to 4.6 ± 0.7 pg cell-1. In total, nine P-CTX analogs were detected, depending on strain and growth phase. The production of gambierone, as well as 44-methylgamberione, was also confirmed in G. polynesiensis. This study highlighted: (i) intraspecific variations in toxin production and profiles between clones from distinct geographic origins and (ii) the noticeable increase in toxin production of both CTXs, in particular CTX4A/B, and gambierone group analogs from the exponential to the stationary phase.


Assuntos
Dinoflagelados/metabolismo , Toxinas Biológicas/metabolismo , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Dinoflagelados/crescimento & desenvolvimento , Camundongos , Polinésia , Especificidade da Espécie , Toxinas Biológicas/toxicidade
11.
Mar Pollut Bull ; 145: 105-117, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590766

RESUMO

The Beagle Channel is a remote subantarctic environment where mussel aquaculture initiatives have existed since the early 1990s. Here we analyze phytoplankton biomass and composition, and the occurrence of harmful microalgae species and their toxins at three sites during the period 2015-2016. The occurrence of potentially harmful algae was observed throughout the study period, including toxigenic dinoflagellates such as Alexandrium catenella (Group I of the A. tamarense complex), A. ostenfeldii, Dinophysis acuminata, Gonyaulax spinifera, Azadinium sp., and the diatoms Pseudo-nitzschia australis and P. fraudulenta. Toxic dinoflagellates were detected in low densities whereas a Pseudo-nitzschia bloom was observed in late February. Isolates of A. catenella and P. delicatissima sensu stricto were phylogenetically characterized. The toxin profile of A. catenella was dominated by GTX4, while P. delicatissima sensu stricto showed no production of the neurotoxin domoic acid in culture conditions. The results provide base-line information for the management of harmful algal blooms in this little explored subantarctic area.


Assuntos
Aquicultura , Diatomáceas/química , Dinoflagelados/química , Toxinas Marinhas/análise , Fitoplâncton/química , Animais , Biomassa , Diatomáceas/classificação , Diatomáceas/crescimento & desenvolvimento , Dinoflagelados/classificação , Dinoflagelados/crescimento & desenvolvimento , Proliferação Nociva de Algas , Microalgas/química , Microalgas/classificação , Microalgas/crescimento & desenvolvimento , Fitoplâncton/classificação , Fitoplâncton/crescimento & desenvolvimento , América do Sul
12.
Environ Pollut ; 255(Pt 2): 113299, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31585405

RESUMO

Lipophilic marine algal toxins (LMATs) pose a potential threat to the health of marine shellfish consumers and marine breeding industries. In this study, LMATs in dissolved phases (DP) and particulate phases (PP) in the seawater of Jiaozhou Bay were accurately determined over four seasons to understand their composition, level, phase partitioning, spatiotemporal variation, and potential sources in aquatic environments of a typical semi-closed mariculture bay. Various LMATs, such as okadaic acid (OA), dinophysistoxin-1 (DTX1), dinophysistoxin-2 (DTX2), gymnodimine (GYM), 13-desmethyl spirolide C (SPX1), pectenotoxin-2 (PTX2), pectenotoxin-2 seco acid (PTX2 SA), and pectenotoxin-11 (PTX11), were detected in DP and PP; of these, OA and PTX2 were the dominant LMATs in DP and PP, respectively. The average proportion of ΣLMATs in DP (97.5%) was significantly higher than that in PP (2.5%), which indicates that LMATs are predominantly partitioned into DP. The total concentrations of LMATs in DP ranged from 4.16 ng/L to 23.19 ng/L (mean, 13.35 ng/L) over four seasons. The highest levels of LMATs in DP and PP were found in summer (mean, 16.71 ng/L) and spring, respectively, while the maximum variety of LMATs was found in autumn. This result suggests that seasonal changes could influence the composition, concentration, and phase partitioning of LMATs in aquatic environments of a coastal semi-closed mariculture bay. ΣLMAT concentrations were higher in the western region than in the eastern region of the bay, where shellfish may have a greater risk of exposure. Dinophysis acuminata, Dinophysis fortii, and Prorocentrum minimum were the potential sources of LMATs in the aquaculture seawater. Overall, various LMATs occurred in the semi-closed mariculture bay, and the persistence and bioavailability of these toxins in aquaculture seawater should be determined in future research.


Assuntos
Baías/química , Dinoflagelados/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Toxinas Marinhas/análise , Água do Mar/química , Animais , Aquicultura , China , Crustáceos/química , Estações do Ano , Frutos do Mar/análise
13.
Mar Pollut Bull ; 149: 110488, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31421564

RESUMO

To understand and predict the outbreak of red tides, which are often dominated by mixotrophic dinoflagellates (MTDs), the effects of "top-down" control by co-occurring predators on red-tide MTDs should be taken into consideration. We studied the numerical and functional responses of the tintinnid ciliate Favella ehrenbergii feeding on two red-tide MTDs, Scrippsiella trochoidea and Heterocapsa triquetra, under single and mixed prey conditions. Our results suggest that a mixed diet could support a better growth of predators compared to a monodiet. In addition, the predators preferred to graze S. trochoidea in the mixed diets, suggesting that predators may switch their feeding preference. The grazing by tintinnid predators could potentially inhibit the outbreaks of red tides dominated by MTDs. The findings in this study provide basic data and new insights for understanding the complex predator-prey relationships in marine microbial food webs, and the dynamics of red tides dominated by MTDs.


Assuntos
Dinoflagelados , Cadeia Alimentar , Proliferação Nociva de Algas , Animais , Dieta , Dinoflagelados/crescimento & desenvolvimento , Comportamento Predatório
14.
Mar Drugs ; 17(9)2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31443393

RESUMO

Azaspiracids (AZAs) are microalgal toxins that can accumulate in shellfish and lead to human intoxications. To facilitate their study and subsequent biomonitoring, purification from microalgae rather than shellfish is preferable; however, challenges remain with respect to maximizing toxin yields. The impacts of temperature, growth media, and photoperiod on cell densities and toxin production in Azadinium spinosum were investigated. Final cell densities were similar at 10 and 18 °C, while toxin cell quotas were higher (~3.5-fold) at 10 °C. A comparison of culture media showed higher cell densities and AZA cell quotas (2.5-5-fold) in f10k compared to f/2 and L1 media. Photoperiod also showed differences, with lower cell densities in the 8:16 L:D treatment, while toxin cell quotas were similar for 12:12 and 8:16 L:D treatments but slightly lower for the 16:8 L:D treatment. AZA1, -2 and -33 were detected during the exponential phase, while some known and new AZAs were only detected once the stationary phase was reached. These compounds were additionally detected in field water samples during an AZA event.


Assuntos
Dinoflagelados/metabolismo , Toxinas Marinhas/biossíntese , Microalgas/metabolismo , Frutos do Mar/toxicidade , Monitoramento Biológico/métodos , Técnicas de Cultura de Células/métodos , Meios de Cultura/química , Dinoflagelados/crescimento & desenvolvimento , Doenças Transmitidas por Alimentos/etiologia , Doenças Transmitidas por Alimentos/prevenção & controle , Humanos , Toxinas Marinhas/toxicidade , Microalgas/crescimento & desenvolvimento , Fotoperíodo , Compostos de Espiro/toxicidade , Temperatura
15.
Sci Total Environ ; 694: 133396, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31401512

RESUMO

The Arabian Sea is prone to large-scale algal blooms during winter monsoon annually. However, it is unclear why dinoflagellate, especially Noctiluca scintillans, replaced diatoms as the main bloom species. Based on in situ, remote sensing and numerical-model data off Pakistan, we found a stratified water with less salty, suitable temperature (~24 °C) and low-light conditions at the subsurface, as well as the organic nutrient accumulation and silicate limitation, were crucial for the growth of N. scintillans and outcompeting diatoms. The superposition of cyclonic eddy promoted N. scintillans pumping to surface and forming large-scale bloom. Subsequently, the shading effect of surface bloom caused the disappearance of subsurface chlorophyll maximum layer. This result suggests that the combined effects of nutrient structure and hydrodynamics play an important role in the prevalence of N. scintillans.


Assuntos
Diatomáceas/crescimento & desenvolvimento , Dinoflagelados/crescimento & desenvolvimento , Monitoramento Ambiental , Eutrofização , Paquistão , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Água do Mar , Temperatura
16.
Gene ; 711: 143950, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31255736

RESUMO

The marine dinoflagellate Alexandrium minutum is known to produce saxitoxins that cause paralytic shellfish poisoning in human worldwide through consumption of the contaminated shellfish mollusks. Despite numerous studies on the growth physiology and saxitoxin production of this species, the knowledge on the molecular basis of nutrient uptakes in relation to toxin production in this species is limited. In this study, relative expressions of the high-affinity transporter genes of nitrate, ammonium, and phosphate (AmNrt2, AmAmt1 and AmPiPT1) and the assimilation genes, nitrate reductase (AmNas), glutamine synthase (AmGSIII) and carbamoyl phosphate synthase (AmCPSII) from A. minutum were studied in batch clonal culture condition with two nitrogen sources (nitrate: NO3- or ammonium: NH4+) under different N:P ratios (high-P: N:P of 14 and 16, and low-P: N:P of 155). The expression of AmAmt1 was suppressed in excess NH4+-grown condition but was not observed in AmNrt2 and AmNas. Expressions of AmAmt1, AmNrt2, AmNas, AmGSIII, AmCPSII, and AmPiPT1 were high in P-deficient condition, showing that A. minutum is likely to take up nutrients for growth under P-stress condition. Conversely, relative expression of AmCPSII was incongruent with cell growth, but was well correlated with toxin quota, suggesting that the gene might involve in arginine metabolism and related toxin production pathway. The expression of AmGSIII is found coincided with higher toxin production and is believed to involve in mechanism to detoxify the cells from excess ammonium stress. The gene regulation observed in this study has provided better insights into the ecophysiology of A. minutum in relation to its adaptive strategies in unfavorable environments.


Assuntos
Técnicas de Cultura Celular por Lotes/métodos , Dinoflagelados/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Compostos de Amônio/metabolismo , Dinoflagelados/metabolismo , Regulação da Expressão Gênica , Nitratos/metabolismo , Fosfatos/metabolismo , Saxitoxina/genética , Estresse Fisiológico
17.
Elife ; 82019 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-31317866

RESUMO

Coral reefs are some of the most important and ecologically diverse marine environments. At the base of the reef ecosystem are dinoflagellate algae, which live symbiotically within coral cells. Efforts to understand the relationship between alga and coral have been greatly hampered by the lack of an appropriate dinoflagellate genetic transformation technology. By making use of the plasmid-like fragmented chloroplast genome, we have introduced novel genetic material into the dinoflagellate chloroplast genome. We have shown that the introduced genes are expressed and confer the expected phenotypes. Genetically modified cultures have been grown for 1 year with subculturing, maintaining the introduced genes and phenotypes. This indicates that cells continue to divide after transformation and that the transformation is stable. This is the first report of stable chloroplast transformation in dinoflagellate algae.


Assuntos
Cloroplastos/genética , Dinoflagelados/genética , Genética Microbiana/métodos , Transformação Genética , Dinoflagelados/crescimento & desenvolvimento , Expressão Gênica , Instabilidade Genômica , Fenótipo
18.
Mar Pollut Bull ; 144: 196-204, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179988

RESUMO

Although many achievements have been made in studies on the relationship between Symbiodiniaceae and coral bleaching, there is little information on the responses of Symbiodiniaceae to coral thermal bleaching in the South China Sea (SCS). In this study, Symbiodiniaceae communities and the effective quantum yield (ФPSII) of healthy and bleached massive corals from the SCS were compared. The results indicated that the Symbiodiniaceae communities and ФPSII values showed coral bleaching-dependent variations. Specifically, the relative abundances of the rare putatively thermally tolerant Durusdinium sp. (D1) and the Symbiochlorum hainanensis increased significantly in the bleached corals. In addition, bleached Porites lutea was mainly associated with the putatively thermally tolerant Cladocopium sp. (C15 and C91) and exhibited the highest ФPSII value compared with other bleached corals. These results highlight that the rare putatively thermally tolerant algae and coral species-specific algae may be important for understanding thermal bleaching of corals.


Assuntos
Antozoários/crescimento & desenvolvimento , Dinoflagelados/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Fotossíntese/fisiologia , Pigmentação/fisiologia , Adaptação Fisiológica , Animais , Antozoários/fisiologia , China , Temperatura Alta , Água do Mar/química
19.
Biopreserv Biobank ; 17(6): 520-529, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31194572

RESUMO

Dinoflagellates of the genus Symbiodinium form symbiotic relationships with corals, other marine invertebrates, and protists; thus, they are considered as important species in coral reef ecosystems. If Symbiodinium could be successfully cryopreserved, the cell bank generated could prove to be a valuable resource for researchers interested in basic biological research of Symbiodinium-invertebrate symbioses. Herein, successful cryopreservation of clade D Symbiodinium was achieved using a two-step freezing protocol. Symbiodinium cells were exposed to cryoprotectants (CPAs) for 30 minutes before being vapor frozen for 20 minutes in liquid nitrogen (LN2); afterward, cells were immediately immersed in LN2 for 2 hours or 10 days. The initial experiment was conducted with the following CPAs at 1, 2, and 3 M concentrations: methanol, dimethyl sulfoxide, glycerol, ethylene glycol (EG), and propylene glycol (PG). It was found that infiltration with 2 M EG and PG yielded cells with the highest percentage viability. Upon thawing, culture of these Symbiodinium was carried out for 2 months in a growth chamber, and cells continued to grow and proliferate over this period. This represents successful cryopreservation of a dominant reef coral symbiont, a feat that will ideally aid in future research of this important lineage of dinoflagellate.


Assuntos
Criopreservação/métodos , Crioprotetores/farmacologia , Dinoflagelados/citologia , Animais , Antozoários/parasitologia , Dimetil Sulfóxido/farmacologia , Dinoflagelados/crescimento & desenvolvimento , Etilenoglicol/farmacologia , Glicerol/farmacologia , Metanol/farmacologia , Propilenoglicol/farmacologia , Simbiose , Termotolerância
20.
PLoS One ; 14(6): e0218183, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31194825

RESUMO

The blooms of Noctiluca in the Gulf of Oman and the Arabian Sea have been intensifying in recent years, posing now a threat to regional fisheries and the long-term health of an ecosystem supporting a coastal population of nearly 120 million people. We present the results of a local-scale data analysis to investigate the onset and patterns of the Noctiluca blooms, which form annually during the winter monsoon in the Gulf of Oman and in the Arabian Sea. Our approach combines methods in physical and biological oceanography with machine learning techniques. In particular, we present a robust algorithm, the variable-length Linear Dynamic Systems (vLDS) model, that extracts the causal factors and latent dynamics at the local-scale along each individual drifter trajectory, and demonstrate its effectiveness by using it to generate predictive plots for all variables and test macroscopic scientific hypotheses. The vLDS model is a new algorithm specifically designed to analyze the irregular dataset from surface velocity drifters, in which the multivariate time series trajectories are having variable or unequal lengths. The test results provide local-scale statistical evidence to support and check the macroscopic physical and biological Oceanography hypotheses on the Noctiluca blooms; it also helps identify complementary local trajectory-scale dynamics that might not be visible or discoverable at the macroscopic scale. The vLDS model also exhibits a generalization capability (as a machine learning methodology) to investigate important causal factors and hidden dynamics associated with ocean biogeochemical processes and phenomena at the population-level and local trajectory-scale.


Assuntos
Algoritmos , Dinoflagelados/crescimento & desenvolvimento , Oceanos e Mares , Monitoramento Ambiental , Modelos Lineares , Modelos Biológicos , Água do Mar
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