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1.
PLoS One ; 15(6): e0235015, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32559229

RESUMO

Representatives of the marine dinophyte family Amphidomataceae produce lipophilic phycotoxins called azaspiracids (AZA) which may cause azaspiracid shellfish poisoning (AZP) in humans after consumption of contaminated seafood. Three of the four known toxigenic species are observed frequently in the eastern North Atlantic. In 2018, a research survey was performed to strengthen knowledge on the distribution and abundance of toxigenic Amphidomataceae and their respective toxins in Irish coastal waters and in the North Sea. Species-specific quantification of the three toxigenic species (Azadinium spinosum, Azadinium poporum and Amphidoma languida) was based on recently developed qPCR assays, whose performance was successfully validated and tested with specificity tests and spike experiments. The multi-method approach of on-board live microscopy, qPCR assays and chemical AZA-analysis revealed the presence of Amphidomataceae in the North Atlantic including the three targeted toxigenic species and their respective AZA analogues (AZA-1, -2, -33, -38, -39). Azadinium spinosum was detected at the majority of Irish stations with a peak density of 8.3 x 104 cells L-1 and AZA (AZA-1, -2, -33) abundances up to 1,274 pg L-1. Amphidoma languida was also present at most Irish stations but appeared in highest abundance in a bloom at a central North Sea station with a density of 1.2 x 105 cells L-1 and an AZA (AZA-38, -39) abundances of 618 pg L-1. Azadinium poporum was detected sporadically at the Irish south coast and North Sea and was rather low in abundance during this study. The results confirmed the wide distribution and frequent occurrence of the target species in the North Atlantic area and revealed, for the first time, bloom abundances of toxigenic Amphidomataceae in this area. This emphasizes the importance of future studies and monitoring of amphidomatacean species and their respective AZA analogues in the North Atlantic.


Assuntos
Biomassa , Dinoflagelados/fisiologia , Toxinas Marinhas/análise , Compostos de Espiro/análise , Dinoflagelados/metabolismo , Toxinas Marinhas/metabolismo , Mar do Norte , Água do Mar/química , Compostos de Espiro/metabolismo
2.
Toxicon ; 180: 1-10, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32246951

RESUMO

Pinnatoxins (PnTXs) are a group of emerging marine biotoxins produced by the benthic dinoflagellate Vulcanodinium rugosum, currently not regulated in Europe or in any other country in the world. In France, PnTXs were detected for the first time in 2011, in mussels from the Ingril lagoon (South of France, Mediterranean coast). Since then, analyses carried out in mussels from this lagoon have shown high concentrations of PnTXs for several months each year. PnTXs have also been detected, to a lesser extent, in mussels from other Mediterranean lagoons and on the Atlantic and Corsican coasts. In the French data, the main analog is PnTX G (low levels of PnTX A are also present in some samples). No cases of PnTXs poisoning in humans have been reported so far in France or anywhere else in the world. In mice, PnTXs induce acute neurotoxic effects, within a few minutes after oral administration. Clinical signs of toxicity include decreased mobility, paralysis of the hind legs, tremors, jumps and breathing difficulties leading to death by respiratory arrest at high doses. The French agency for food safety (ANSES) recently conducted a review of the state of knowledge related to PnTXs and V. rugosum. Based on (i) the clinical signs of toxicity in mice, (ii) the mode of action of PnTXs as nicotinic acetylcholine receptor competitive antagonists and (iii) knowledge on drugs and natural toxins with PnTX-related pharmacology, potential human symptoms have been extrapolated and proposed. In this work, a provisional acute benchmark value for PnTX G of 0.13 µg/kg bw per day has been derived from an oral acute toxicity study in mice. Based on this value and a large shellfish meat portion size of 400g, a concentration lower than 23 µg PnTX G/kg shellfish meat is not expected to result in adverse effects in humans. ANSES recommends taking into account PnTXs in the French official monitoring program for shellfish production and identified data gaps to refine health risk assessment.


Assuntos
Exposição Dietética/estatística & dados numéricos , Monitoramento Ambiental , Inocuidade dos Alimentos , Toxinas Marinhas/análise , Frutos do Mar/estatística & dados numéricos , Animais , Bivalves , Dinoflagelados , França , Humanos , Toxinas Marinhas/metabolismo , Camundongos , Medição de Risco , Alimentos Marinhos/estatística & dados numéricos , Intoxicação por Frutos do Mar
3.
Toxicon ; 180: 79-88, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32289356

RESUMO

Physiological plasticity gives HABs species the ability to respond to variations in the surrounding environment. The aim of this study was to examine morphological and physiological variability in Alexandrium pacificum R.W. Litaker (Group IV) (former Alexandrium catenella) blooming in Annaba bay, Algeria. Monoclonal cultures of up to 30 strains of this neurotoxic dinoflagellate were established by the germination of single resting cysts from the surface sediment of this southern Mediterranean marine ecosystem. Ribotyping confirmed formally for the first time that A. pacificum is developing in Eastern Algerian waters. Toxin analyses of A. pacificum strains revealed substantial intraspecific variability in both the profile and toxin amount. However, the toxin profile of most strains is characterized by the dominance of GTX6 (up to 96 mol %) which is the less toxic paralytic molecule. The toxin concentrations in the isolated strains varied widely between 3.8 and 30.82 fmol cell-1. We observed an important variation in the growth rate of the studied A. pacificum strains with values ranging from 0.05 to 0.33 d-1. The lag time of the studied strains varied widely and ranged from 4 to 20 days. The intraspecific diversity could be a response to the selection pressure which may be exerted by different environmental conditions over time and which can be genetically and in turn physiologically expressed. This study highlights, for the first time, that the sediment of a limited area holds an important diversity of A. pacificum cysts which give when germinate populations with noticeable physiological plasticity. Consequently, this diversified natural populations allow an exceptional adaptation to specific environmental conditions to outcompete local microalgae and to establish HABs which could explain why this dinoflagellate is successful and expanding worldwide.


Assuntos
Dinoflagelados/fisiologia , Toxinas Marinhas/análise , Argélia , Baías , Ecossistema , Toxinas Marinhas/metabolismo , Intoxicação por Frutos do Mar , Toxinas Biológicas , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
4.
Aquat Toxicol ; 222: 105422, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32112996

RESUMO

The proliferations of cyanobacteria are increasingly prevalent in many rivers and water bodies due especially to eutrophication. This work aims to study in female medaka fish the toxicity, the transfer and the depuration of the anatoxin-a, a neurotoxin produced by benthic cyanobacterial biofilms. This work will provide answers regarding acute toxicity induced by single gavage by anatoxin-a and to the risks of exposure by ingestion of contaminated fish flesh, considering that data on these aspects remain particularly limited. The oral LD50 and NOAEL of a single dose of (±)-anatoxin-a were determined at 11.50 and 6.67 µg.g-1, respectively. Subsequently, the toxico-kinetics of the (±)-anatoxin-a was observed in the guts, the livers and the muscles of female medaka fish for 10 days. Anatoxin-a was quantified by high-resolution qTOF mass spectrometry coupled upstream to a UHPLC chromatographic chain. The toxin could not be detected in the liver after 12 h, and in the gut and muscle after 3 days. Overall, the medaka fish do not appear to accumulate (±)-anatoxin-a and to largely recover after 24 h following a single sub-acute oral liquid exposure at the NOAEL.


Assuntos
Toxinas Marinhas/toxicidade , Neurotoxinas/toxicidade , Oryzias/metabolismo , Tropanos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Cianobactérias/metabolismo , Eutrofização , Feminino , Trato Gastrointestinal/efeitos dos fármacos , Trato Gastrointestinal/metabolismo , Dose Letal Mediana , Fígado/efeitos dos fármacos , Fígado/metabolismo , Toxinas Marinhas/metabolismo , Modelos Teóricos , Músculos/efeitos dos fármacos , Músculos/metabolismo , Neurotoxinas/metabolismo , Nível de Efeito Adverso não Observado , Rios/química , Toxicocinética , Tropanos/metabolismo , Poluentes Químicos da Água/metabolismo
5.
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
6.
Chemosphere ; 248: 126101, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32045977

RESUMO

Calcium decline and cyanobacterial blooms pose a serious threat to the crustacean zooplankton Daphnia, which has a high demand for calcium. In the present study, we exposed two different clones of Daphnia pulex to different combinations of calcium concentrations (0.1, 0.5, 1.0, 5.0, 10.0 mg L-1) and food types (100% Chlorella; 80% Chlorella and 20% non-toxic Microcystis; 80% Chlorella and 20% toxic Microcystis) for 16 days, recorded the key life-history traits, and then used an exponential rise function to fit the traits. Results showed toxic Microcystis and low calcium together negatively affected the survival, development, and reproduction of Daphnia. The negative effect of non-toxic Microcystis and low calcium only affected the development and reproduction. The survival time and reproductive performance increased exponentially with increasing calcium concentration and then approached an asymptotic maximum. Both non-toxic and toxic Microcystis reduced the asymptotic maximum of the reproductive performance. The rising rate at which they reached the asymptotes differed significantly among the three food types; i.e., the reproductive performance of Daphnia was affected in a wider range of calcium concentrations under bad food quality. The findings indicated that Microcystis impaired the tolerance of Daphnia to low calcium, which may cause serious consequences in freshwater ecosystems.


Assuntos
Adaptação Fisiológica/efeitos dos fármacos , Cálcio/metabolismo , Daphnia/efeitos dos fármacos , Traços de História de Vida , Toxinas Marinhas/toxicidade , Microcystis/metabolismo , Zooplâncton/efeitos dos fármacos , Animais , Cálcio/farmacologia , Chlorella/metabolismo , Relação Dose-Resposta a Droga , Ecossistema , Água Doce/química , Toxinas Marinhas/metabolismo , Microcystis/crescimento & desenvolvimento , Reprodução/efeitos dos fármacos
7.
Aquat Toxicol ; 220: 105399, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896464

RESUMO

There is little information in scientific literature as to how conditions created by a microcystin (MC) producing cyanobacterial bloom affect the oxidant/antioxidant, biotransformation and neurotoxicity parameters in adult frogs in situ. We investigated biochemical parameters in the skin and muscle of Pelophylax kl. esculentus from Lake Ludas (Serbia) by comparing frogs that live on the northern bloom side (BS) of the lake with those that inhabit the southern no-bloom side (NBS). A higher protein carbonylation level and lower antioxidant defense system capability in the skin of frogs living in conditions of the cyanobacterial bloom were observed. Inhibition of glutathione-dependent machinery was the major mechanism responsible for the induction of cyanobacterial bloom-mediated oxidative stress in frog skin. On the other hand, the detected higher ability of muscle to overcome bloom prooxidant toxicity was linked to a higher efficiency of the biotransformation system through glutathione-S-transferase activity and/or was the consequence of indirect exposure of the tissue to the bloom. Our results have also revealed that the cyanobacterial bloom conditions induced the cholinergic neurotransmitter system in both tissues. This study provides a better understanding of the ecotoxicological impact of the MC producing cyanobacterial bloom on frogs in situ. However, further investigations of the complex mechanism involved in cyanobacterial bloom toxicity in real environmental conditions are required.


Assuntos
Toxinas Bacterianas/toxicidade , Cianobactérias/metabolismo , Eutrofização , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Músculos/efeitos dos fármacos , Rana esculenta/metabolismo , Pele/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Toxinas Bacterianas/metabolismo , Biotransformação , Cianobactérias/crescimento & desenvolvimento , Monitoramento Ambiental , Lagos/química , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Músculos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Rana esculenta/crescimento & desenvolvimento , Sérvia , Pele/metabolismo , Poluentes Químicos da Água/metabolismo
8.
Ecotoxicol Environ Saf ; 183: 109477, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31369939

RESUMO

The increasing eutrophication of freshwater and brackish habitats globally has led to a corresponding increase in the occurrence of harmful cyanobacterial blooms. Cyanobacteria can produce highly toxic substances such as microcystins (MCs) that affect the health of livestock, wildlife, and humans. The present study broaden the understanding of cyanobacteria ecology and MC dynamics in the field, focusing on the estimation of the production and sedimentation rates of MCs in a natural habitat. The nutrient concentrations of the reservoir water and sediment pore water were monitored at 3-h intervals for 24 h during the summer cyanobacterial bloom. The DIN uptake rate of Microcystis in the Isahaya reservoir was estimated and the large-scale blooms in the reservoir were largely controlled by the interactions between rainfall and nutrient levels in the warm season. By using calculations based on the nitrogen budgets and tracking changes of the MC concentrations in the water column, the total MC production and sedimentation rates were estimated to be 52.2 kg MCs d-1 and 21.5 kg MCs d-1, respectively. Although MCs could be degraded in the environment, the MC sedimentation still comprised 41% of the in-water production.


Assuntos
Toxinas Bacterianas/análise , Baías/microbiologia , Toxinas Marinhas/análise , Microcistinas/análise , Toxinas Bacterianas/metabolismo , Baías/química , Ecossistema , Eutrofização , Sedimentos Geológicos/química , Japão , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Microcystis/metabolismo , Nitrogênio/metabolismo , Nutrientes , Estações do Ano
9.
Mar Drugs ; 17(8)2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31349621

RESUMO

Sea anemone venom contains a complex and diverse arsenal of peptides and proteins of pharmacological and biotechnological interest, however, only venom from a few species has been explored from a global perspective to date. In the present study, we identified the polypeptides present in the venom of the sea anemone Anthopleura dowii Verrill, 1869 through a transcriptomic and proteomic analysis of the tentacles and the proteomic profile of the secreted mucus. In our transcriptomic results, we identified 261 polypeptides related to or predicted to be secreted in the venom, including proteases, neurotoxins that could act as either potassium (K+) or sodium (Na+) channels inhibitors, protease inhibitors, phospholipases A2, and other polypeptides. Our proteomic data allowed the identification of 156 polypeptides-48 exclusively identified in the mucus, 20 in the tentacles, and 88 in both protein samples. Only 23 polypeptides identified by tandem mass spectrometry (MS/MS) were related to the venom and 21 exclusively identified in the mucus, most corresponding to neurotoxins and hydrolases. Our data contribute to the knowledge of evolutionary and venomic analyses of cnidarians, particularly of sea anemones.


Assuntos
Venenos de Cnidários/genética , Venenos de Cnidários/metabolismo , Muco/metabolismo , Anêmonas-do-Mar/genética , Anêmonas-do-Mar/metabolismo , Transcriptoma/genética , Animais , Toxinas Marinhas/metabolismo , Neurotoxinas/genética , Neurotoxinas/metabolismo , Peptídeo Hidrolases/genética , Peptídeo Hidrolases/metabolismo , Peptídeos/genética , Peptídeos/metabolismo , Proteômica/métodos , Espectrometria de Massas em Tandem/métodos
10.
ACS Chem Biol ; 14(5): 941-948, 2019 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-30983320

RESUMO

Small molecules that bind to voltage-gated sodium channels (VGSCs) are promising leads in the treatment of numerous neurodegenerative diseases and pain. Nature is a highly skilled medicinal chemist in this regard, designing potent VGSC ligands capable of binding to and blocking the channel, thereby offering compounds of potential therapeutic interest. Paralytic shellfish toxins (PSTs), produced by cyanobacteria and marine dinoflagellates, are examples of these naturally occurring small molecule VGSC blockers that can potentially be leveraged to solve human health concerns. Unfortunately, the remarkable potency of these natural products results in equally exceptional toxicity, presenting a significant challenge for the therapeutic application of these compounds. Identifying less potent analogs and convenient methods for accessing them therefore provides an attractive approach to developing molecules with enhanced therapeutic potential. Fortunately, Nature has evolved tools to modulate the toxicity of PSTs through selective hydroxylation, sulfation, and desulfation of the core scaffold. Here, we demonstrate the function of enzymes encoded in cyanobacterial PST biosynthetic gene clusters that have evolved specifically for the sulfation of highly functionalized PSTs, the substrate scope of these enzymes, and elucidate the biosynthetic route from saxitoxin to monosulfated gonyautoxins and disulfated C-toxins. Finally, the binding affinities of the nonsulfated, monosulfated, and disulfated products of these enzymatic reactions have been evaluated for VGSC binding affinity using mouse whole brain membrane preparations to provide an assessment of relative toxicity. These data demonstrate the unique detoxification effect of sulfotransferases in PST biosynthesis, providing a potential mechanism for the development of more attractive PST-derived therapeutic analogs.


Assuntos
Toxinas Marinhas/metabolismo , Frutos do Mar , Animais , Biocatálise , Encéfalo/metabolismo , Camundongos , Sulfotransferases/metabolismo , Canais de Sódio Disparados por Voltagem/metabolismo
11.
Toxins (Basel) ; 11(4)2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30965634

RESUMO

The dinoflagellate Alexandrium minutum (A. minutum) which can produce paralyticshellfish toxins (PSTs) is often used as a model to study the migration, biotransformation,accumulation, and removal of PSTs. However, the mechanism is still unclear. To provide a new toolfor related studies, we tried to label PSTs metabolically with 15N stable isotope to obtain 15N-PSTsinstead of original 14N, which could be treated as biomarker on PSTs metabolism. We then culturedthe A. minutum AGY-H46 which produces toxins GTX1-4 in f/2 medium of different 15N/Pconcentrations. The 15N-PSTs' toxicity and toxin profile were detected. Meanwhile, the 15N labelingabundance and 15N atom number of 15N-PSTs were identified. The 14N of PSTs produced by A.minutum can be successfully replaced by 15N, and the f/2 medium of standard 15N/P concentrationwas the best choice in terms of the species' growth, PST profile, 15N labeling result and experimentcost. After many (>15) generations, the 15N abundance in PSTs extract reached 82.36%, and the 15Natom number introduced into GTX1-4 might be 4⁻6. This paper innovatively provided the initialevidence that 15N isotope application of labeling PSTs in A. minutum is feasible. The 15N-PSTs asbiomarker can be applied and provide further information on PSTs metabolism.


Assuntos
Dinoflagelados/metabolismo , Toxinas Marinhas/metabolismo , Isótopos de Nitrogênio , Biomarcadores , Dinoflagelados/efeitos dos fármacos , Dinoflagelados/crescimento & desenvolvimento , Marcação por Isótopo , Isótopos de Nitrogênio/farmacologia
12.
Aquat Toxicol ; 210: 251-261, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30878793

RESUMO

The dinoflagellate Alexandrium minutum produces toxic compounds, including paralytic shellfish toxins, but also some unknown extracellular toxins. Although copper (Cu) is an essential element, it can impair microalgal physiology and increase their toxic potency. This study investigated the effect of different concentrations of dissolved Cu (7 nM, 79 nM and 164 nM) on A. minutum allelochemical potency, here defined as negative effects of a protist on competing protists through the release of chemicals. This was studied in relation to its physiology. The effects of Cu were assessed on A. minutum growth, reactive oxygen species level, photosynthesis proxies, lipid metabolism, exudation of dissolved organic compounds, allelochemical potency and on the associate free bacterial community of A. minutum. Only the highest Cu exposure (164 nM) inhibited and delayed the growth of A. minutum, and only in this treatment did the allelochemical potency significantly increase, when the dissolved Cu concentration was still toxic. Within the first 7 days of the high Cu treatment, the physiology of A. minutum was severely impaired with decreased growth and photosynthesis, and increased stress responses and free bacterial density per algal cell. After 15 days, A. minutum partially recovered from Cu stress as highlighted by the growth rate, reactive oxygen species level and photosystem II yields. This recovery could be attributed to the apparent decrease in background dissolved Cu concentration to a non-toxic level, suggesting that the release of exudates may have partially decreased the bioavailable Cu fraction. Overall, A. minutum appeared quite tolerant to Cu, and this work suggests that the modifications in the physiology and in the exudates help the algae to cope with Cu exposure. Moreover, this study shows the complex interplay between abiotic and biotic factors that can influence the dynamic of A. minutum blooms. Modulation in allelochemical potency of A. minutum by Cu may have ecological implications with an increased competitiveness of this species in environments contaminated with Cu.


Assuntos
Cobre/toxicidade , Dinoflagelados/efeitos dos fármacos , Microalgas/efeitos dos fármacos , Feromônios/metabolismo , Poluentes Químicos da Água/toxicidade , Dinoflagelados/metabolismo , Dinoflagelados/microbiologia , Toxinas Marinhas/metabolismo , Microalgas/metabolismo , Microbiota/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos
13.
Toxicol Lett ; 307: 17-25, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30825503

RESUMO

13-Desmethylspirolide C (13-SPX-C) is a phycotoxin produced by dinoflagellates which can accumulate in shellfish. 13-SPX-C induces neurotoxic effects in rodents through blockade of nicotinic acetylcholine receptors. As no human intoxication has been to date attributed to the consumption of 13-SPX-C-contaminated seafood, this toxin is not regulated according to the Codex Alimentarius. Nevertheless, shellfish consumers can be exposed to 13-SPX-C via shellfish consumption. In order to follow the fate of the toxin after ingestion and to verify whether metabolic detoxification could explain the lack of human intoxications, we assessed the metabolism of 13-SPX-C using several in vitro liver systems. First, both phase I and II reactions occurring with rat and human liver S9 fractions were screened. Our results indicated that 13-SPX-C was almost completely metabolized with both rat and human liver S9. Using a receptor binding assay towards nicotinic acetylcholine receptors we demonstrated that the resulting metabolites showed less affinity towards nicotinic acetylcholine receptors than 13-SPX-C. Finally, we showed that 13-SPX-C induced a pronounced increase of gene expression of the drug-metabolizing enzyme cytochrome P450 (CYP) CYP1A2. The role of this CYP in 13-SPX-C metabolism was clarified using an innovative in vitro tool, CYP1A2-Silensomes™. In summary, this study highlights that liver first-pass metabolism can contribute to the detoxification of 13-SPX-C.


Assuntos
Fígado/metabolismo , Toxinas Marinhas/metabolismo , Compostos de Espiro/metabolismo , Animais , Citocromo P-450 CYP1A2/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Técnicas In Vitro , Fígado/efeitos dos fármacos , Ratos , Reação em Cadeia da Polimerase em Tempo Real
14.
Prostate ; 79(7): 798-812, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30900311

RESUMO

BACKGROUND: Microcystin-leucine arginine (MC-LR) could disrupt prostate development and cause prostate hyperplasia. But whether and how maternal and before-weaning MC-LR exposure causes prostate hyperplasia in male offspring by changing expression profile of P-element-induced wimpy (PIWI)-interacting RNAs (piRNAs) have not yet been reported. METHODS: From the 12th day in the embryonic period to the 21st day after offspring birth, three groups of pregnant mice that were randomly assigned were exposed to 0, 10, and 50 µg/L of MC-LR through drinking water followed by the analyses of their male offspring. Abortion rate and litter size of maternal mice were recorded. The prostate histopathology was observed. Differential expressed piRNAs of prostate were screened by piRNA microarray analysis. Murine prostate cancer cell line (RM-1) was used for further mechanism study. Luciferase report assay was used to determine the relationship between piRNA-DQ722010 and polypeptide 3 (Pik3r3). RESULTS: The downregulated expression of piRNA-DQ722010 was the most significant in piRNA microarray analysis in 10 µg/L MC-LR treated group, while Pik3r3 was significantly upregulated, consistent with the results that a distinct prostatic epithelial hyperplasia was observed and phosphoinositide-3-kinase (PI3K)/protien kinase B (AKT) signaling pathway was activated. Pik3r3 was verified as the target gene of piRNA-DQ722010. In addition, we found MC-LR decreased the expression of PIWI-like RNA-mediated gene silencing 2 (Piwil2) and 4 (Piwil4) both in vivo and in vitro, and both Piwil4 and Piwil2 could regulate the expression of DQ722010. CONCLUSION: MC-LR caused downregulation of piRNA-DQ722010 and PIWI proteins, while piRNA-DQ722010 downregulation promoted activation of PI3K/AKT signaling pathway inducing prostate hyperplasia by upregulating the expression of Pik3r3. In contrast, piRNA-DQ722010 downregulation may be attributed to PIWI proteins downregulation.


Assuntos
Toxinas Bacterianas/efeitos adversos , Células Epiteliais/metabolismo , Toxinas Marinhas/efeitos adversos , Exposição Materna/efeitos adversos , Microcistinas/efeitos adversos , Próstata/patologia , Neoplasias da Próstata/metabolismo , RNA Interferente Pequeno/biossíntese , Animais , Arginina/efeitos adversos , Proteínas Argonauta/genética , Proteínas Argonauta/metabolismo , Toxinas Bacterianas/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Água Potável/microbiologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Feminino , Água Doce/microbiologia , Hiperplasia , Leucina/efeitos adversos , Masculino , Toxinas Marinhas/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Análise em Microsséries , Microcistinas/metabolismo , Fosfatidilinositol 3-Quinases/biossíntese , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Gravidez , Próstata/efeitos dos fármacos , Próstata/metabolismo , Neoplasias da Próstata/etiologia , Neoplasias da Próstata/patologia , Isoformas de Proteínas , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Poluição da Água/efeitos adversos
15.
BMC Mol Biol ; 20(1): 7, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808304

RESUMO

BACKGROUND: A major cause of phytoplankton mortality is predation by zooplankton. Strategies to avoid grazers have probably played a major role in the evolution of phytoplankton and impacted bloom dynamics and trophic energy transport. Certain species of the genus Pseudo-nitzschia produce the neurotoxin, domoic acid (DA), as a response to the presence of copepod grazers, suggesting that DA is a defense compound. The biosynthesis of DA comprises fusion of two precursors, a C10 isoprenoid geranyl pyrophosphate and L-glutamate. Geranyl pyrophosphate (GPP) may derive from the mevalonate isoprenoid (MEV) pathway in the cytosol or from the methyl-erythritol phosphate (MEP) pathway in the plastid. L-glutamate is suggested to derive from the citric acid cycle. Fragilariopsis, a phylogenetically related but nontoxic genus of diatoms, does not appear to possess a similar defense mechanism. We acquired information on genes involved in biosynthesis, precursor pathways and regulatory functions for DA production in the toxigenic Pseudo-nitzschia seriata, as well as genes involved in responses to grazers to resolve common responses for defense strategies in diatoms. RESULTS: Several genes are expressed in cells of Pseudo-nitzschia when these are exposed to predator cues. No genes are expressed in Fragilariopsis when treated similarly, indicating that the two taxa have evolved different strategies to avoid predation. Genes involved in signal transduction indicate that Pseudo-nitzschia cells receive signals from copepods that transduce cascading molecular precursors leading to the formation of DA. Five out of seven genes in the MEP pathway for synthesis of GPP are upregulated, but none in the conventional MEV pathway. Five genes with known or suggested functions in later steps of DA formation are upregulated. We conclude that no gene regulation supports that L-glutamate derives from the citric acid cycle, and we suggest the proline metabolism to be a downstream precursor. CONCLUSIONS: Pseudo-nitzschia cells, but not Fragilariopsis, receive and respond to copepod cues. The cellular route for the C10 isoprenoid product for biosynthesis of DA arises from the MEP metabolic pathway and we suggest proline metabolism to be a downstream precursor for L-glutamate. We suggest 13 genes with unknown function to be involved in diatom responses to grazers.


Assuntos
Diatomáceas/genética , Diatomáceas/metabolismo , Ácido Caínico/análogos & derivados , Toxinas Marinhas/genética , Toxinas Marinhas/metabolismo , Redes e Vias Metabólicas/genética , Eritritol/análogos & derivados , Eritritol/metabolismo , Herbivoria , Ácido Caínico/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , Fosfatos Açúcares/metabolismo
16.
Toxins (Basel) ; 11(1)2019 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-30669577

RESUMO

The physiological and toxicological characteristics of Dinophysis acuminata have been increasingly studied in an attempt to better understand and predict diarrhetic shellfish poisoning (DSP) events worldwide. Recent work has identified prey quantity, organic nitrogen, and ammonium as likely contributors to increased Dinophysis growth rates and/or toxicity. Further research is now needed to better understand the interplay between these factors, for example, how inorganic and organic compounds interact with prey and a variety of Dinophysis species and/or strains. In this study, the exudate of ciliate prey and cryptophytes were investigated for an ability to support D. acuminata growth and toxin production in the presence and absence of prey, i.e., during mixotrophic and phototrophic growth respectively. A series of culturing experiments demonstrated that the addition of ciliate lysate led to faster dinoflagellate growth rates (0.25 ± 0.002/d) in predator-prey co-incubations than in treatments containing (1) similar levels of prey but without lysate (0.21 ± 0.003/d), (2) ciliate lysate but no live prey (0.12 ± 0.004/d), or (3) monocultures of D. acuminata without ciliate lysate or live prey (0.01 ± 0.007/d). The addition of ciliate lysate to co-incubations also resulted in maximum toxin quotas and extracellular concentrations of okadaic acid (OA, 0.11 ± 0.01 pg/cell; 1.37 ± 0.10 ng/mL) and dinophysistoxin-1 (DTX1, 0.20 ± 0.02 pg/cell; 1.27 ± 0.10 ng/mL), and significantly greater total DSP toxin concentrations (intracellular + extracellular). Pectenotoxin-2 values, intracellular or extracellular, did not show a clear trend across the treatments. The addition of cryptophyte lysate or whole cells, however, did not support dinoflagellate cell division. Together these data demonstrate that while certain growth was observed when only lysate was added, the benefits to Dinophysis were maximized when ciliate lysate was added with the ciliate inoculum (i.e., during mixotrophic growth). Extrapolating to the field, these culturing studies suggest that the presence of ciliate exudate during co-occurring dinoflagellate-ciliate blooms may indirectly and directly exacerbate D. acuminata abundance and toxigenicity. More research is required, however, to understand what direct or indirect mechanisms control the predator-prey dynamic and what component(s) of ciliate lysate are being utilized by the dinoflagellate or other organisms (e.g., ciliate or bacteria) in the culture if predictive capabilities are to be developed and management strategies created.


Assuntos
Cilióforos/química , Criptófitas/química , Dinoflagelados/crescimento & desenvolvimento , Dinoflagelados/metabolismo , Toxinas Marinhas/metabolismo , Furanos/metabolismo , Ácido Okadáico/metabolismo , Piranos/metabolismo
17.
Environ Pollut ; 246: 827-836, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30623839

RESUMO

Harmful algal blooms are a threat to aquatic organisms and coastal ecosystems. Among harmful species, the widespread distributed genus Alexandrium is of global importance. This genus is well-known for the synthesis of paralytic shellfish toxins which are toxic for humans through the consumption of contaminated shellfish. While the effects of Alexandrium species upon the physiology of bivalves are now well documented, consequences on reproduction remain poorly studied. In France, Alexandrium minutum blooms have been recurrent for the last decades, generally appearing during the reproduction season of most bivalves including the oyster Crassostrea gigas. These blooms could not only affect gametogenesis but also spawning, larval development or juvenile recruitment. This study assesses the effect of toxic A. minutum blooms on C. gigas reproduction. Adult oysters were experimentally exposed to A. minutum, at environmentally realistic concentrations (102 to 103 cells mL-1) for two months during their gametogenesis and a control group, not exposed to A. minutum was fed with a non-toxic dinoflagellate. To determine both consequences to next generation and direct effects of A. minutum exposure on larvae, the embryo-larval development of subsequent offspring was conducted with and without A. minutum exposure at 102 cells mL-1. Effects at each stage of the reproduction were investigated on ecophysiological parameters, cellular responses, and offspring development. Broodstock exposed to A. minutum produced spermatozoa with decreased motility and larvae of smaller size which showed higher mortalities during settlement. Embryo-larval exposure to A. minutum significantly reduced growth and settlement of larvae compared to non-exposed offspring. This detrimental consequence on larval growth was stronger in larvae derived from control parents compared to offspring from exposed parents. This study provides evidence that A. minutum blooms, whether they occur during gametogenesis, spawning or larval development, can either affect gamete quality and/or larval development of C. gigas, thus potentially impacting oyster recruitment.


Assuntos
Crassostrea/efeitos dos fármacos , Crassostrea/crescimento & desenvolvimento , Dinoflagelados/metabolismo , Exposição Ambiental/efeitos adversos , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Animais , França
18.
ISME J ; 13(1): 64-75, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30108304

RESUMO

Many species of phytoplankton produce toxins that may provide protection from grazing. In that case one would expect toxin production to be costly; else all species would evolve toxicity. However, experiments have consistently failed to show any costs. Here, we show that costs of toxin production are environment dependent but can be high. We develop a fitness optimization model to estimate rate, costs, and benefits of toxin production, using PST (paralytic shellfish toxin) producing dinoflagellates as an example. Costs include energy and material (nitrogen) costs estimated from well-established biochemistry of PSTs, and benefits are estimated from relationship between toxin content and grazing mortality. The model reproduces all known features of PST production: inducibility in the presence of grazer cues, low toxicity of nitrogen-starved cells, but high toxicity of P-limited and light-limited cells. The model predicts negligible reduction in cell division rate in nitrogen replete cells, consistent with observations, but >20% reduction when nitrogen is limiting and abundance of grazers high. Such situation is characteristic of coastal and oceanic waters during summer when blooms of toxic algae typically develop. The investment in defense is warranted, since the net growth rate is always higher in defended than in undefended cells.


Assuntos
Dinoflagelados/metabolismo , Toxinas Marinhas/metabolismo , Fitoplâncton/metabolismo , Animais , Metabolismo Energético/fisiologia , Modelos Biológicos , Nitrogênio/metabolismo , Fitoplâncton/classificação
19.
Mar Pollut Bull ; 137: 430-443, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30503452

RESUMO

Morphological and phylogenetic analysis showed that the Gambierdiscus isolate from Bolinao, Philippines belongs to the species of G. carpenteri. It was morphologically more similar to the Merimbula strain than the subtropical Florida Keys strain. Growth and toxin production were also investigated at varying levels of temperature, salinity, and irradiance. Gambierdiscus are known to grow favorably in a low light environment. However, this study showed high growth rates of G. carpenteri even at high irradiance levels. Generally, cells produced more toxins at lower treatment levels. Highest cellular toxin content recorded was 7.48 ±â€¯0.49 pg Pbtx eq/cell at culture conditions of 25 °C, 100 µmol photons m-2 s-1, and salinity of 26. Growth rate and toxin production data suggest that cells produced more toxins during the slowest growth at certain range of treatments. This information gives insight into how changes in environmental conditions may affect toxin production and growth of G. carpenteri.


Assuntos
Dinoflagelados/classificação , Dinoflagelados/crescimento & desenvolvimento , Toxinas Marinhas/metabolismo , Dinoflagelados/metabolismo , Ecossistema , Filipinas , Filogenia , Salinidade , Temperatura , Clima Tropical
20.
Harmful Algae ; 80: 158-170, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30502809

RESUMO

Strains of the freshwater filamentous, benthic cyanobacterium Scytonema crispum Agardh isolated from six sites in subtropical south-east Queensland were characterised using a combination of phenotypic and genetic traits. Morphologically, the strains were consistent with the description of Scytonemataceae sensu stricto, and the description of Scytonema crispum. However, phylogenetic analysis of the 16S rRNA gene, the 16S-23S rRNA operon, and the nifH gene revealed that these strains and three others from outside Australia formed a monophyletic clade distinct from Scytonema and other species in the Scytonemataceae. Collectively, this data suggests this group is sufficiently evolutionarily distinct to be placed in a new family, Heteroscytonemataceae fam. nov. Accordingly, the taxon previously known as S. crispum has been transferred to a new genus Heteroscytonema gen nov., as H. crispum. Some strains of H. crispum exhibited facultative production of paralytic shellfish toxins (PSTs). The concentration of PSTs produced by individual strains varied widely, from 2.7 µg g-1 to 171.3 µg g-1, and included C toxins, decarbamoyl saxitoxin (dcSTX), gonyautoxins (GTX2, GTX3 and GTX5), saxitoxin (STX) and uncharacterised PSTs. The majority of the Australian strains produced dcSTX as the dominant saxitoxin analogue, a significant finding given that dcSTX has approximately half the relative toxicity of STX. The PST profile varied within and between Australian strains of H. crispum and in strains collected from New Zealand and the United States. The sxtA gene, one of the determinants for the production of PSTs, was present in all strains in which PSTs were detected. The discovery of PST-producing H. crispum in the headwaters of a major drinking water reservoir presents a serious risk for potential human and animal exposure to these neurotoxic compounds and further highlights the importance of monitoring benthic cyanobacteria populations for potentially toxigenic species.


Assuntos
Toxinas Bacterianas/metabolismo , Cianobactérias/classificação , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Filogenia , Biodiversidade , Cianobactérias/metabolismo , Queensland , RNA Ribossômico 16S/química , Saxitoxina/análise , Saxitoxina/química , Análise de Sequência de DNA
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