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1.
Ecotoxicol Environ Saf ; 195: 110474, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32200147

RESUMO

In the present study, we characterized the potential toxin genes for polyketide synthase (PKS) and saxitoxin (STX) biosynthesis using the transcriptomes of two non-STX producing dinoflagellates Amphidinium carterae and Prorocentrum micans. RNA sequencing revealed 94 and 166 PKS contigs in A. carterae and P. micans, respectively. We first detected type III PKS, which was closely related to bacteria. In addition, dozens of homologs of 20 STX biosynthesis genes were identified. Interestingly, the core STX-synthesizing genes sxtA and sxtB were only found in P. micans, whereas sxtD was detected in A. carterae alone. Bioinformatic analysis showed that the first two core genes (sxtA and sxtG) had a low sequence similarity (37.0-67.6%) and different domain organization compared to those of other toxigenic dinoflagellates, such as Alexandrium pacificum. These might result in the breakdown of the initial reactions in STX production and ultimately the loss of the ability to synthesize the toxins in both dinoflagellates. Our findings suggest that toxin-related PKS and sxt genes are commonly found in non-STX producing dinoflagellates. In addition to their involvement in the synthesis of toxins, our result indicates that genes may also have other molecular metabolic functions.


Assuntos
Dinoflagelados/genética , Evolução Molecular , Policetídeo Sintases/genética , Saxitoxina/biossíntese , Dinoflagelados/enzimologia , Dinoflagelados/metabolismo , Deleção de Genes , Filogenia , Análise de Sequência de RNA , Transcriptoma
2.
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
3.
Mar Drugs ; 18(2)2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32033403

RESUMO

Saxitoxin is an alkaloid neurotoxin originally isolated from the clam Saxidomus giganteus in 1957. This group of neurotoxins is produced by several species of freshwater cyanobacteria and marine dinoflagellates. The saxitoxin biosynthesis pathway was described for the first time in the 1980s and, since then, it was studied in more than seven cyanobacterial genera, comprising 26 genes that form a cluster ranging from 25.7 kb to 35 kb in sequence length. Due to the complexity of the genomic landscape, saxitoxin biosynthesis in dinoflagellates remains unknown. In order to reveal and understand the dynamics of the activity in such impressive unicellular organisms with a complex genome, a strategy that can carefully engage them in a systems view is necessary. Advances in omics technology (the collective tools of biological sciences) facilitated high-throughput studies of the genome, transcriptome, proteome, and metabolome of dinoflagellates. The omics approach was utilized to address saxitoxin-producing dinoflagellates in response to environmental stresses to improve understanding of dinoflagellates gene-environment interactions. Therefore, in this review, the progress in understanding dinoflagellate saxitoxin biosynthesis using an omics approach is emphasized. Further potential applications of metabolomics and genomics to unravel novel insights into saxitoxin biosynthesis in dinoflagellates are also reviewed.


Assuntos
Dinoflagelados/genética , Dinoflagelados/metabolismo , Saxitoxina/biossíntese , Saxitoxina/química , Vias Biossintéticas , Cianobactérias/metabolismo , Genômica , Metabolômica , Neurotoxinas/metabolismo , Biossíntese de Proteínas , Proteômica , Saxitoxina/metabolismo , Transcriptoma
4.
Ecotoxicol Environ Saf ; 192: 110265, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32045784

RESUMO

Diarrheic shellfish poisoning (DSP) toxins are produced by harmful microalgae and accumulate in bivalve mollusks, causing various toxicity. These toxic effects appear to abate with increasing DSP concentration and longer exposure time, however, the underlying mechanisms remain unclear. To explore the underlying molecular mechanisms, de novo transcriptome analysis of the digestive gland of Perna viridis was performed after Prorocentrum lima exposure. RNA-seq analysis showed that 1886 and 237 genes were up- and down-regulated, respectively after 6 h exposure to P. lima, while 265 genes were up-regulated and 217 genes were down-regulated after 96 h compared to the control. These differentially expressed genes mainly involved in Nrf2 signing pathways, immune stress, apoptosis and cytoskeleton, etc. Combined with qPCR results, we speculated that the mussel P. viridis might mainly rely on glutathione S-transferase (GST) and ABC transporters to counteract DSP toxins during short-term exposure. However, longer exposure of P. lima could activate the Nrf2 signaling pathway and inhibitors of apoptosis protein (IAP), which in turn reduced the damage of DSP toxins to the mussel. DSP toxins could induce cytoskeleton destabilization and had some negative impact on the immune system of bivalves. Collectively, our findings uncovered the crucial molecular mechanisms and the regulatory metabolic nodes that underpin the defense mechanism of bivalves against DSP toxins and also advanced our current understanding of bivalve defense mechanisms.


Assuntos
Dinoflagelados/metabolismo , Expressão Gênica/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Perna (Organismo)/efeitos dos fármacos , Animais , Regulação para Baixo , Perfilação da Expressão Gênica , Toxinas Marinhas/metabolismo , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Perna (Organismo)/genética , Perna (Organismo)/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Alimentos Marinhos , Intoxicação por Frutos do Mar , Regulação para Cima
5.
Chemosphere ; 241: 125083, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683425

RESUMO

The increasing inflow of nitrogen (N) substrates into marine nearshore ecosystems induces proliferation of harmful algal blooms (HABs) of dinoflagellates, such as potentially toxic invasive species Prorocentrum minimum. In this study, we estimated the influence of NO3-, NH4+ and urea on transcription levels and urea transporter dur3 and nitrate transporter nrt2 genes expression in these dinoflagellates. We identified dur3 and nrt2 genes sequences in unannotated transcriptomes of P. minimum and other dinoflagellates presented in MMETSP database. Phylogenetic analysis showed that these genes of dinoflagellates clustered to the distinct clade demonstrating evolutionary relationship with the other known dur3 and nrt2 genes of microalgae. The evaluation of expression levels of dur3 and nrt2 genes by RT-qPCR revealed their sensitivity to input of the studied N sources. Dur3 expression levels were downregulated after the supplementation of additional N sources and were 1.7-2.6-fold lower than in the nitrate-grown culture. Nrt2 expression levels decreased 1.9-fold in the presence of NH4+. We estimated total RNA and DNA synthesis rates by the analysis of incorporation of 3H-thymidine and 3H-uridine in batch and continuous cultures. Addition of N compounds did not affect the DNA synthesis rates. Transcription levels increased up to 12.5-fold after the N supplementation in urea-limited treatments. Investigation of various nitrogen sources as biomarkers of dinoflagellate proliferation due to their differentiated impact on expression of dur3 and nrt2 genes and transcription rates in P. minimum cells allowed concluding about high potential of the studied parameters for future modeling of HABs under global N pollution.


Assuntos
Dinoflagelados/genética , Nitrogênio/metabolismo , Proteínas de Transporte de Ânions , Dinoflagelados/metabolismo , Ecossistema , Proliferação Nociva de Algas/fisiologia , Proteínas de Membrana Transportadoras , Nitratos/metabolismo , Filogenia , Ureia/metabolismo
6.
Chemosphere ; 241: 124968, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31606578

RESUMO

The solute carriers (SLCs) are membrane proteins that transport many endogenous and exogenous substances such as xenobiotic toxins. Bivalve mollusks, mainly feeding on microalgae, show marked capacity to accumulate paralytic shellfish toxins (PSTs), the most common and hazardous marine biotoxins produced by dinoflagellates. Exploring the SLCs related to PST accumulation in bivalve could benefit our understanding about the mechanisms of PST bioavailability in bivalve and the adaptations of these species. Herein, we provided the first systematic analysis of SLC genes in mollusks, which identified 673 SLCs (PySLCs, 48 subfamilies) in Yesso scallop (Patinopecten yessoensis), 510 (48 subfamilies) in Pacific oyster (Crassostrea gigas), and 350 (47 subfamilies) in gastropod owl limpet (Lottia gigantea). Significant expansion of subfamilies SLC5, SLC6, SLC16, and SLC23 in scallop, and SLC46 subfamily in both scallop and oyster were revealed. Different PySLC members were highly expressed in the developmental stages and adult tissues, and hepatopancreas harboured more specifically expressed PySLCs than other tissues/organs. After feeding the scallops with PST-producing dinoflagellate, 131 PySLCs were regulated and more than half of them were from the expanded subfamilies. The trend of expression fold change in regulated PySLCs was consistent with that of PST changes in hepatopancreas, implying the possible involvement of these PySLCs in PST transport and homeostasis. In addition, the PySLCs from the expanded subfamily were revealed to be under positive selection, which might be related to lineage-specific adaptation to the marine environments with algae derived biotoxins.


Assuntos
Dinoflagelados/patogenicidade , Regulação da Expressão Gênica/efeitos dos fármacos , Pectinidae/genética , Proteínas Carreadoras de Solutos/genética , Animais , Transporte Biológico , Dinoflagelados/metabolismo , Homeostase , Intoxicação por Frutos do Mar , Toxinas Biológicas/toxicidade
7.
Aquat Toxicol ; 218: 105360, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31765943

RESUMO

Labile dissolved organic carbon (DOC) is a major pollutant in coastal marine environments affected by anthropogenic impacts, and may significantly contribute to coral bleaching and subsequent mortality on coastal reefs. DOC can cause bleaching indirectly through the rapid proliferation of copiotrophic and pathogenic bacteria. Here we demonstrate that labile DOC compounds can also impair the coral-dinoflagellate symbiosis by directly affecting coral physiology on both the host and algal symbiont level. In a controlled aquarium experiment, we monitored over several weeks key physiological parameters of the tropical coral Stylophora pistillata exposed to ambient and elevated labile DOC levels (0.1 and 1.0 mM) in combination with low and high nitrogen (i.e. ammonium) conditions (0.2 and 4.0 µM). At the symbiont level, DOC exposure under low ammonium availability decreased the photosynthetic efficiency accompanied by ∼75 % Chl a and ∼50 % symbiont cell reduction. The photosynthetic functioning of the symbionts recovered once the DOC enrichment ceased indicating a reversible shift between autotrophic and heterotrophic metabolism. At the host level, the assimilation of exogenous DOC sustained the tissue carbon reserves, but induced a depletion of the nitrogen reserves, indicated by ∼35 % decreased protein levels. This suggests an imbalanced exogenous carbon to nitrogen supply with nitrogen potentially limiting host metabolism on the long-term. We also demonstrate that increased ammonium availability delayed DOC-induced bleaching likely by keeping symbionts in a photosynthetically competent state, which is crucial for symbiosis maintenance and coral survival. Overall, the present study provides further insights into how coastal pollution can de-stabilize the coral-algal symbiosis and cause coral bleaching. Therefore, reducing coastal pollution and sustaining ecological integrity are critical to strengthen the resilience of coral reefs facing climate change.


Assuntos
Compostos de Amônio/farmacologia , Antozoários/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Compostos Orgânicos/toxicidade , Simbiose/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antozoários/metabolismo , Processos Autotróficos , Mudança Climática , Recifes de Corais , Dinoflagelados/metabolismo , Processos Heterotróficos , Oceano Índico , Fotossíntese/efeitos dos fármacos
8.
Chemosphere ; 244: 125485, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31809929

RESUMO

Microplastics are widespread emerging marine pollutants that have been found in the coral reef ecosystem. In the present study, using Cladocopium goreaui as a symbiont representative, we investigated cytological, physiological, and molecular responses of a Symbiodiniaceae species to weeklong microplastic exposure (Polystyrene, diameter 1.0 µm, 9.0 × 109 particles L-1). The density and size of algal cells decreased significantly at 7 d and 6-7 d of microplastic exposure, respectively. Chlorophyll a content increased significantly at 7 d of exposure, whereas Fv/Fm did not change significantly during the entire exposure period. We observed significant increases in superoxide dismutase activity and caspase3 activation level, significant decrease in glutathione S-transferase activity, but no change in catalase activity during the whole exposure period. Transcriptomic analysis revealed 191 significantly upregulated and 71 significantly downregulated genes at 7 d after microplastic exposure. Fifteen GO terms were overrepresented for these significantly upregulated genes, which were grouped into four categories including transmembrane ion transport, substrate-specific transmembrane transporter activity, calcium ion binding, and calcium-dependent cysteine-type endopeptidase activity. Thirteen of the significantly upregulated genes encode metal ion transporter and ammonium transporter, and five light-harvesting protein genes were among the significantly downregulated genes. These results demonstrate that microplastics can act as an exogenous stressor, suppress detoxification activity, nutrient uptake, and photosynthesis, elevate oxidative stress, and raise the apoptosis level through upregulating ion transport and apoptotic enzymes to repress the growth of C. goreaui. These effects have implications in negative impacts of microplastics on coral-Symbiodiniaceae symbiosis that involves C. goreaui.


Assuntos
Dinoflagelados/fisiologia , Microplásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Antozoários/metabolismo , Apoptose , Clorofila A , Recifes de Corais , Dinoflagelados/metabolismo , Ecossistema , Oxirredução , Estresse Oxidativo , Fotossíntese , Poliestirenos/metabolismo , Poliestirenos/toxicidade , Simbiose , Poluentes Químicos da Água/metabolismo
9.
Chemosphere ; 238: 124661, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31472350

RESUMO

Toxicities of the marine algae Alexandrium minutum and its excreted gonyautoxins (GTXs) to the marine crustacean Artemia salina were investigated. Mortality was observed for neither larvae nor adult A. salina exposed to A. minutum at a density of 5000 cells/mL or 0.5 µM GTX2/3. After exposure, the full transcriptome of adult A. salina was assembled and functionally annotated. A total of 599,286 transcripts were obtained, which were clustered into 515,196 unigenes. Results of the transcriptional effect level index revealed that direct exposure to the toxic algae A. minutum caused greater alterations in the transcriptome than did exposure to the extracellular product GTX2/3. Mechanisms of effects were different between exposure of A. salina to A. minutum cells or GTX2/3. Exposure to A. minutum modulated formation of the ribonucleoprotein complex and metabolism of amino acids and lipids in A. salina. Exposure to GTX2/3 exposure inhibited expression of genes related to metabolism of chitin, which might result in disruption of molting process or disturbed sheath morphogenesis. Overall, effects on transcription observed in this study represent the first report based on application of next generation sequencing techniques to investigate the transcriptomic response of A. salina exposed to an environmentally realistic level of A. minutum or GTX2/3.


Assuntos
Artemia/genética , Saxitoxina/análogos & derivados , Transcriptoma/efeitos dos fármacos , Animais , Artemia/fisiologia , Quitina/genética , Quitina/metabolismo , Dinoflagelados/citologia , Dinoflagelados/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Saxitoxina/farmacologia , Saxitoxina/toxicidade
10.
Chemosphere ; 238: 124560, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31437632

RESUMO

Plastics are the most abundant marine debris globally dispersed in the oceans and its production is rising with documented negative impacts in marine ecosystems. However, the chemical-physical and biological interactions occurring between plastic and planktonic communities of different types of microorganisms are poorly understood. In these respects, it is of paramount importance to understand, on a molecular level on the surface, what happens to plastic fragments when dispersed in the ocean and directly interacting with phytoplankton assemblages. This study presents a computer-aided analysis of electron paramagnetic resonance (EPR) spectra of selected spin probes able to enter the phyoplanktonic cell interface and interact with the plastic surface. Two different marine phytoplankton species were analyzed, such as the diatom Skeletonema marinoi and dinoflagellate Lingulodinium polyedrum, in absence and presence of polyethylene terephthalate (PET) fragments in synthetic seawater (ASPM), in order to in-situ characterize the interactions occurring between the microalgal cells and plastic surfaces. The analysis was performed at increasing incubation times. The cellular growth and adhesion rates of microalgae in batch culture medium and on the plastic fragments were also evaluated. The data agreed with the EPR results, which showed a significant difference in terms of surface properties between the diatom and dinoflagellate species. Low-polar interactions of lipid aggregates with the plastic surface sites were mainly responsible for the cell-plastic adhesion by S. marinoi, which is exponentially growing on the plastic surface over the incubation time.


Assuntos
Diatomáceas/metabolismo , Dinoflagelados/metabolismo , Microalgas/crescimento & desenvolvimento , Fitoplâncton/metabolismo , Plásticos/metabolismo , Polietilenotereftalatos/metabolismo , Ecossistema , Espectroscopia de Ressonância de Spin Eletrônica , Microalgas/metabolismo , Oceanos e Mares , Água do Mar/química , Resíduos/análise
11.
Mar Drugs ; 17(10)2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31652489

RESUMO

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.


Assuntos
Antibacterianos/biossíntese , Organismos Aquáticos/metabolismo , Dinoflagelados/metabolismo , Éteres/metabolismo , Toxinas Marinhas/biossíntese , Alquilação , Antibacterianos/toxicidade , Vias Biossintéticas/genética , Biologia Computacional , Dinoflagelados/genética , Éteres/toxicidade , Toxinas Marinhas/toxicidade
12.
Eur J Protistol ; 71: 125642, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31654920

RESUMO

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.


Assuntos
Metabolismo dos Carboidratos , Argila/parasitologia , Dinoflagelados/metabolismo , Glutationa/metabolismo , Argila/química , Proliferação Nociva de Algas
13.
Mar Drugs ; 17(10)2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31652521

RESUMO

Azaspiracids (AZAs) are marine biotoxins including a variety of analogues. Recently, novel AZAs produced by the Mediterranean dinoflagellate Azadinium dexteroporum were discovered (AZA-54, AZA-55, 3-epi-AZA-7, AZA-56, AZA-57 and AZA-58) and their biological effects have not been investigated yet. This study aimed to identify the biological responses (biomarkers) induced in mussels Mytilus galloprovincialis after the bioaccumulation of AZAs from A. dexteroporum. Organisms were fed with A. dexteroporum for 21 days and subsequently subjected to a recovery period (normal diet) of 21 days. Exposed organisms accumulated AZA-54, 3-epi-AZA-7 and AZA-55, predominantly in the digestive gland. Mussels' haemocytes showed inhibition of phagocytosis activity, modulation of the composition of haemocytic subpopulation and damage to lysosomal membranes; the digestive tissue displayed thinned tubule walls, consumption of storage lipids and accumulation of lipofuscin. Slight genotoxic damage was also observed. No clear occurrence of oxidative stress and alteration of nervous activity was detected in AZA-accumulating mussels. Most of the altered parameters returned to control levels after the recovery phase. The toxic effects detected in M. galloprovincialis demonstrate a clear biological impact of the AZAs produced by A. dexteroporum, and could be used as early indicators of contamination associated with the ingestion of seafood.


Assuntos
Dinoflagelados/metabolismo , Doenças Transmitidas por Alimentos/prevenção & controle , Toxinas Marinhas/toxicidade , Mytilus/efeitos dos fármacos , Alimentos Marinhos/toxicidade , Compostos de Espiro/toxicidade , Animais , Doenças Transmitidas por Alimentos/etiologia , Hemócitos/efeitos dos fármacos , Toxinas Marinhas/biossíntese , Mar Mediterrâneo , Mutagênese/efeitos dos fármacos , Mytilus/genética , Estresse Oxidativo/efeitos dos fármacos
14.
Environ Pollut ; 255(Pt 1): 113149, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31522007

RESUMO

Antibiotics have been widely detected in the ocean and have various impacts on the environment, while knowledge of their chronic influence on phytoplankton, especially red tide algae, is still limited. Dinoflagellates and green algae are common phytoplankton in marine ecosystems. The former is the main red tide algae, and the latter is an important primary producer. We investigated the long-term responses of two representative algae, Prorocentrum lima and Chlorella sp., to two common antibiotics (sulfamethoxazole (SMX) and norfloxacin (NFX)) at environmentally relevant levels (10 and 100 ng/L) during simulated natural conditions. The cell density and activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)) were analyzed. The results showed that the influence of each antibiotic on Chlorella sp. was not significant (p > 0.05) during the first 10 days, but the influence of the antibiotics later began to show significant inhibition (p < 0.05) compared with the control group, especially during mixed exposure. P. lima was not inhibited, but its cell density increased. SMX had a superior stimulation effect on P. lima. The three enzymes activities of P. lima increased, and the antioxidant mechanism was not seriously impacted. However, for Chlorella sp., the activity of SOD increased while the activities of CAT and POD decreased, suggesting that this algae's antioxidant system was unbalanced due to oxidative stress. Based on our results, the growth of P. lima was different from green algae Chlorella sp. as well as other inhibited marine algae (such as diatom, golden algae) studied in previous studies. Therefore, as a typical pollutant in the ocean, antibiotics may play a positive role in the bloom of dinoflagellate red tides.


Assuntos
Antibacterianos/farmacologia , Chlorella/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Proliferação Nociva de Algas/efeitos dos fármacos , Norfloxacino/farmacologia , Sulfametoxazol/farmacologia , Poluentes da Água/farmacologia , Antioxidantes/metabolismo , Catalase/metabolismo , Chlorella/metabolismo , Dinoflagelados/metabolismo , Ecossistema , Peroxidase/metabolismo , Peroxidases/metabolismo , Superóxido Dismutase/metabolismo , Fatores de Tempo
15.
Protist ; 170(5): 125680, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31563792

RESUMO

Marine unarmored dinoflagellates in the family Kareniaceae are known to possess chloroplasts of haptophyte origin, which contain fucoxanthin and its derivatives as major carotenoids, and lack peridinin. In the present study, the first species with the peridinin-type chloroplast in this family, Gertia stigmatica gen. et sp. nov., is described on the basis of ultrastructure, photosynthetic pigment composition, and molecular phylogeny inferred from nucleus- and chloroplast-encoded genes. Cells of G. stigmatica were small and harboring a chloroplast with an eyespot and two pyrenoids. The apical structure complex was straight, similar to Karenia and Karlodinium. Under transmission electron microscopy, the chloroplast was surrounded by two membranes, and the eyespot was composed of a single layer of osmiophilic globules (eyespot type A); this was never previously reported from the Kareniaceae. High performance liquid chromatography demonstrated the chloroplast contains peridinin, and neither fucoxanthin nor 19'-acyloxyfucoxanthins was identified. A phylogeny based on nucleus-encoded rDNAs suggested a position of G. stigmatica in the Kareniaceae, but not clustered within the previously described genera, i.e., Karenia, Karlodinium and Takayama. A phylogeny of chloroplast-encoded psbA, psbC and psbD indicated the chloroplast is of peridinin-type typical of dinoflagellates, but the most related species remains unclear.


Assuntos
Organismos Aquáticos , Carotenoides , Cloroplastos , Dinoflagelados/classificação , Organismos Aquáticos/classificação , Organismos Aquáticos/citologia , Organismos Aquáticos/metabolismo , Carotenoides/metabolismo , Cloroplastos/classificação , Cloroplastos/metabolismo , Dinoflagelados/citologia , Dinoflagelados/metabolismo , Especificidade da Espécie
16.
PLoS One ; 14(9): e0222327, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31509600

RESUMO

The ecological success of shallow water reef-building corals has been linked to the symbiosis between the coral host and its dinoflagellate symbionts (herein 'symbionts'). As mixotrophs, symbiotic corals depend on nutrients 1) transferred from their photosynthetic symbionts (autotrophy) and 2) acquired by host feeding on particulate organic resources (heterotrophy). However, coral species differ in the extent to which they depend on heterotrophy for nutrition and these differences are typically poorly defined. Here, a multi-tracer fatty acid approach was used to evaluate the trophic strategies of three species of common reef-building coral (Galaxea fascicularis, Pachyseris speciosa, and Pocillopora verrucosa) whose trophic strategies had previously been identified using carbon stable isotopes. The composition and various indices of fatty acids were compared to examine the relative contribution of symbiont autotrophy and host heterotrophy in coral energy acquisition. A linear discriminant analysis (LDA) was used to estimate the contribution of polyunsaturated fatty acids (PUFA) derived from various potential sources to the coral hosts. The total fatty acid composition and fatty acid indices revealed differences between the more heterotrophic (P. verrucosa) and more autotrophic (P. speciosa) coral hosts, with the coral host G. fascicularis showing overlap with the other two species and greater variability overall. For the more heterotrophic P. verrucosa, the fatty acid indices and LDA results both indicated a greater proportion of copepod-derived fatty acids compared to the other coral species. Overall, the LDA estimated that PUFA derived from particulate resources (e.g., copepods and diatoms) comprised a greater proportion of coral host PUFA in contrast to the lower proportion of symbiont-derived PUFA. These estimates provide insight into the importance of heterotrophy in coral nutrition, especially in productive reef systems. The study supports carbon stable isotope results and demonstrates the utility of fatty acid analyses for exploring the trophic strategies of reef-building corals.


Assuntos
Antozoários/crescimento & desenvolvimento , Antozoários/metabolismo , Ácidos Graxos/metabolismo , Animais , Processos Autotróficos , Carbono , Isótopos de Carbono , Recifes de Corais , Dinoflagelados/metabolismo , Ácidos Graxos/análise , Processos Heterotróficos , Ilhas do Oceano Índico , Fotossíntese , Simbiose/fisiologia
17.
J Agric Food Chem ; 67(34): 9667-9682, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31415166

RESUMO

This study assessed the feasibility of an NMR metabolomics approach coupled to multivariate data analysis to monitor the naturally present or stresses-elicited metabolites from a long-term (>170 days) culture of the dinoflagellate marine microalgae Amphidinium carterae grown in a fiberglass paddlewheel-driven raceway photobioreactor. Metabolic contents, in particular, in two members of the amphidinol family, amphidinol A and its 7-sulfate derivative amphidinol B (referred as APDs), and other compounds of interest (fatty acids, carotenoids, oxylipins, etc.) were evaluated by altering concentration levels of the f/2 medium nutrients and daily mean irradiance. Operating with a 24 h sinusoidal light cycle allowed a 3-fold increase in APD production, which was also detected by an increase in hemolytic activity of the methanolic extract of A. carterae biomass. The presence of APDs was consistent with the antitumoral activity measured in the methanolic extracts of the biomass. Increased daily irradiance was accompanied by a general decrease in pigments and an increase in SFAs (saturated fatty acids), MUFAs (monounsaturated fatty acids), and DHA (docosahexaenoic acid), while increased nutrient availability lead to an increase in sugar, amino acid, and PUFA ω-3 contents and pigments and a decrease in SFAs and MUFAs. NMR-based metabolomics is shown to be a fast and suitable method to accompany the production of APD and bioactive compounds without the need of tedious isolation methods and bioassays. The two APD compounds were chemically identified by spectroscopic NMR and spectrometric ESI-IT MS (electrospray ionization ion trap mass spectrometry) and ESI-TOF MS (ESI time-of-flight mass spectrometry) methods.


Assuntos
Dinoflagelados/metabolismo , Macrolídeos/química , Espectroscopia de Ressonância Magnética/métodos , Metabolômica/métodos , Microalgas/metabolismo , Carotenoides/química , Carotenoides/metabolismo , Dinoflagelados/química , Ácidos Graxos/química , Ácidos Graxos/metabolismo , Macrolídeos/metabolismo , Microalgas/química , Análise Multivariada
18.
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
19.
PLoS One ; 14(8): e0220130, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31381568

RESUMO

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.


Assuntos
Antozoários/microbiologia , Dinoflagelados/citologia , Animais , Atmosfera/química , Dióxido de Carbono/análise , Dióxido de Carbono/química , Carbonatos/química , Proliferação de Células/efeitos dos fármacos , Dinoflagelados/efeitos dos fármacos , Dinoflagelados/metabolismo , Dinoflagelados/fisiologia , Ácidos Graxos/metabolismo , Concentração de Íons de Hidrogênio , Fotossíntese/efeitos dos fármacos , Água do Mar/química
20.
Mol Biol Rep ; 46(6): 5955-5966, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31407247

RESUMO

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 1238 bp and contained a dinoflagellate spliced leader sequence, a 906 bp open reading frame (301 amino acids), and a poly (A) tail. The gene was coded on the nuclear genome with one 174 bp 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.


Assuntos
Dinoflagelados/genética , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Sequência de Aminoácidos/genética , Animais , Sequência de Bases/genética , Clonagem Molecular/métodos , DNA Complementar/genética , Dinoflagelados/metabolismo , Fases de Leitura Aberta/genética , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , Filogenia , RNA Mensageiro/genética , Espécies Reativas de Oxigênio/metabolismo , Alinhamento de Sequência
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