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1.
Aquat Toxicol ; 228: 105619, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32937230

RESUMO

Commonly affected by changes in climate and environmental conditions, coastal areas are very dynamic environments where shellfish play an important ecological role. In this study, the oxidative stress and genotoxic responses of mussels (Mytilus galloprovincialis) exposed to paralytic shellfish toxin (PST) - producing dinoflagellates Gymnodinium catenatum were evaluated under i) current conditions (CC: 19 °C; pH 8.0), ii) warming (W: 24 °C; pH 8.0), iii) acidification (A:19 °C; pH 7.6) and iv) combined effect of warming and acidification (WA: 24 °C; pH 7.6). Mussels were fed with G. catenatum for 5 days, and to a non-toxic diet during the following 10 days. A battery of oxidative stress biomarkers and comet assay was performed at the peak of toxin accumulation and at the end of the post-exposure phase. Under CC, gills and hepatopancreas displayed different responses/vulnerabilities and mechanisms to cope with PST. While gills presented a tendency for lipid peroxidation (LPO) and genetic damage (expressed by the Genetic Damage Indicator - GDI), hepatopancreas seems to better cope with the toxins, as no LPO was observed. However, the mechanisms involved in hepatopancreas protection were not enough to maintain DNA integrity. The absence of LPO, and the antioxidant system low responsiveness, suggests DNA damage was not oxidative. When exposed to toxic algae under W, toxin-modulated antioxidant responses were observed in both gills and hepatopancreas. Simultaneous exposure to the stressors highlighted gills susceptibility with a synergistic interaction increasing DNA damage. Exposure to toxic algae under A led to genotoxicity potentiation in both organs. The combined effect of WA did not cause relevant interactions in gills antioxidant responses, but stressors interactions impacted LPO and GDI. Antioxidant responses and LPO pointed out to be modulated by the environmental conditions in hepatopancreas, while GDI results support the dominance of toxin-triggered process. Overall, these results reveal that simultaneous exposure to warming, acidification and PSTs impairs mussel DNA integrity, compromising the genetic information due to the synergetic effects. Finally, this study highlights the increasing ecological risk of harmful algal blooms to Mytilus galloprovinciallis populations.


Assuntos
Dano ao DNA , Toxinas Marinhas/toxicidade , Mytilus/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Biomarcadores/metabolismo , Ensaio Cometa , Dinoflagelados/metabolismo , Brânquias/efeitos dos fármacos , Brânquias/metabolismo , Hepatopâncreas/efeitos dos fármacos , Hepatopâncreas/metabolismo , Concentração de Íons de Hidrogênio , Peroxidação de Lipídeos/efeitos dos fármacos , Toxinas Marinhas/metabolismo , Mytilus/genética , Mytilus/metabolismo , Temperatura
2.
Environ Res ; 188: 109846, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32846638

RESUMO

Marine toxins in bivalves pose an important risk to human health, and regulatory authorities throughout the world impose maximum toxicity values. In general, bivalve toxicities due to paralytic shellfish toxins (PSTs) above the regulatory limit occur during short periods, but in some cases, it may be extended from weeks to months. The present study examines whether cockles (Cerastoderme edule), mussels (Mytilus galloprovincialis) and razor shells (Solen marginatus) naturally exposed to a bloom of Gymnodinium catenatum activated or suppressed biochemical responses as result of the presence of PSTs in their soft tissues. Toxins (C1+2, C3+4, GTX5, GTX6, dcSTX, dcGTX2+3 and dcNEO) and a set of biomarkers (ETS, electron transport system activity; GLY, glycogen; PROT, protein; SOD, superoxide dismutase; CAT, catalase; GPx, glutathione peroxidase; GST, glutathione S-transferases; LPO, lipid peroxidation; reduced (GSH) and oxidized (GSSG) glutathione contents and AChE, acetylcholinesterase activity) were determined in the three bivalve species. Specimens were harvested weekly in Aveiro lagoon, Portugal, along thirteen weeks. This period included three weeks in which bivalve toxicity exceeded largely the regulatory limit and the subsequence recovery period of ten weeks. Biochemical performance of the surveyed species clearly indicated that PSTs induce oxidative stress and neurotoxicity, with higher impact on mussels and razor shells than in cockles. The antioxidant enzymes CAT and GPx seemed to be the biomarkers better associated with toxin effects.


Assuntos
Cardiidae , Toxinas Marinhas , Intoxicação por Frutos do Mar , Animais , Humanos , Toxinas Marinhas/toxicidade , Portugal , Frutos do Mar/análise
3.
Toxicon ; 184: 215-228, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32593754

RESUMO

An assessment of the major pigments and neurotoxins and a description of the phytoplankton community were carried out within the coastal region of Rio de Janeiro State (Brazil), during winter and the following spring of 2018. Overall, six stations were investigated for oceanographic conditions (with CTD casts). Filtered water samples were used to estimate the chlorophyll a (CHL-a), carotenoids (CAR), and phycobiliproteins (PHY) using UV-Vis spectrophotometry, as well as the quantification of saxitoxins (STX) and domoic acid (DA), through High Performance Liquid Chromatography (HPLC). Planktonic organisms were counted using sedimentation chambers of different volumes and an inverted microscope. A cluster analysis, SIMPER, and ANOSIM were applied to the phytoplankton data along with diversity indexes, and non-parametric statistics to phycotoxins and pigments. There was a significant difference between the winter and spring phytoplankton community, associated with the mixed layer depth (r2 = -0.626, p < 0.05) and temperature (r2 = 0.641, p < 0.05). Phytoplankton biomass and C:CHL-a indicated a higher production during the winter than in spring, with the potentially toxic genus Pseudo-nitzschia responsible for 12.79% of autotrophic abundance (SIMPER output). Pigments showed a slight increase in CAR during spring, while PHY remained at trace concentrations. Both the DA and STX were quantified in winter and spring, but with significant differences only for STX between the sampling periods. Among the 71 taxa, 11 were identified as potentially toxic with an emphasis on STX-producing dinoflagellates and cyanobacteria, such as Alexandrium sp., Gymnodinium spp. along with Trichodesmium spp. Season-related environmental variability may be the major driving force modulating the mixed assemblage of species that support different levels of phycotoxins.


Assuntos
Monitoramento Ambiental , Toxinas Marinhas/toxicidade , Fitoplâncton , Biomassa , Brasil , Clorofila A , Cianobactérias , Diatomáceas , Dinoflagelados , Ácido Caínico/análogos & derivados , Toxinas Marinhas/análise , Neurotoxinas , Estações do Ano , Água do Mar , Trichodesmium
4.
Toxicon ; 181: 91-101, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32371068

RESUMO

The toxigenic dinoflagellate Ostreopsis cf. ovata is known to produce a range of palytoxin (PLTX) - related compounds named ovatoxins (OVTX). O. cf. ovata presents a wide variability in toxin production and its toxic profile is strain-specific. Several OVTXs, denominated from -a to -h and -l have been reported from different strains of this benthic microalgae up to now, mainly in Mediterranean isolates. However, less is known about the toxin profile of the strains present in the Atlantic coasts of Europe. In this work, strains of O. cf. ovata isolated from the South coast of Portugal mainland (Algarve) and Selvagens Island (Madeira, Portugal) were cultured and tested for toxicity by hemolytic assay. Toxin profiles were qualitatively elucidated by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS). The strain from Algarve presented lower toxic potency than the strain from Selvagens island (12.3 against 54.8 pg of PLTX equivalents per cell) showing in both cases the characteristic toxin profile of Mediterranean strains. The major component, OVTX-a, was concomitant with OVTX from -b to -g and isobaric PLTX. Regarding the morphological characteristics of these strains, as well as their toxin fingerprint, it is likely they are closely related to strains from Mediterranean coasts. The present study reports for the first time the occurrence of several OVTX congeners and iso-PLTX in O. cf. ovata from Portuguese waters. This study provides valuable information to characterize the risk of OVTXs-related outbreaks in Portugal.


Assuntos
Dinoflagelados , Toxinas Marinhas/toxicidade , Cromatografia Líquida , Portugal
5.
Toxicon ; 182: 59-65, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32428516

RESUMO

This study evaluated the performance of an easy-cultivation device for the mass culture of Alexandrium minutum (A. minutum), a dinoflagellate that produces paralytic shellfish toxins (PSTs). Five culture conditions including three different sizes of containers (250 mL conical flask, 500 mL beaker, and 20 L jar) in two different environments (out-incubator and incubator) were compared in terms of growth and PSTs production. Compared with the incubator environment, the out-incubator environment had more fluctuations in temperature and light intensity. Results showed that the cell densities of A. minutum increased in all groups, especially in the conical flask (I, out-incubator, 6.29×106 cells/mL) and the beaker (IV, incubator, 7.28×106 cells/mL). When cultured in the 20 L jar under out-incubator condition, the algae had the lowest cell density (2.82×106 cells/mL) but the highest toxicity (93.42 ± 2.55×10-6 MU/cell). The negative correlation between average growth rate and single-cell toxicity could be explained by biocompatibility, thereby indicating that the low growth rate led to high toxicity. HPLC-FLD showed that the cellular toxicity increased due to the quantitative increase in GTX1/4, which are the more toxic derivatives. The PSTs types consistently contained GTX1/4 and GTX2/3. The differences in algae growth and toxin-production could be due to changes in bacteria (out-incubator) and CO2 (incubator) with vessel size. The effects of environmental factors on algae are strain specific. The out-incubator device can be applied for large-scale cultivation of A. minutum considering the algae density and toxin-producing ability.


Assuntos
Dinoflagelados/fisiologia , Toxinas Marinhas/toxicidade , Animais , Cromatografia Líquida de Alta Pressão , Frutos do Mar , Temperatura
6.
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
7.
Ecotoxicol Environ Saf ; 194: 110444, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32169726

RESUMO

Nodularin (NOD) is a kind of cyanobacterial toxins. It is of concern due to elicit severe genotoxicity in humans and animals. The comprehensive evaluation of NOD-induced adverse effects in living organisms is urgently needed. This study is aimed to report the developmental toxicity and molecular mechanism using zebrafish embryos exposed to NOD. The embryonic toxicity induced by NOD is demonstrated by inhibition of embryo hatching, increase in mortality rate, abnormal heart rate, embryonic malformation as well as defects in angiogenesis and common cardinal vein remodeling. NOD triggered a decreased rate of angiogenesis through inhibiting endothelial cells migration. NOD induced embryonic cell apoptosis and DNA damage, which can be alleviated by antioxidant N-acetyl-L-cysteine. NOD significantly caused oxidative damage as indicated by changes in reactive oxygen species, superoxide dismutase, catalase, glutathione and malondialdehyde. NOD also altered the expression of vascular development-genes (DLL4, CDH5, VEGFA, VEGFC) and apoptosis-related genes (BAX, BCL-2, P53, CASPASE 3). Taken together, NOD induced adverse effect on zebrafish embryos development, which may be associated with oxidative stress and apoptosis through the activation of P53-BAX/BCL-2-CASPASE 3-mediated pathway.


Assuntos
Toxinas Bacterianas/toxicidade , Embrião não Mamífero/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Peptídeos Cíclicos/toxicidade , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/embriologia , Animais , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Dano ao DNA , Células Endoteliais/metabolismo , Humanos , Malondialdeído/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Peixe-Zebra/metabolismo
8.
PLoS Negl Trop Dis ; 14(3): e0008060, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32163415

RESUMO

The northeast (NE) region of Brazil commonly goes through drought periods, which favor cyanobacterial blooms, capable of producing neurotoxins with implications for human and animal health. The most severe dry spell in the history of Brazil occurred between 2012 and 2016. Coincidently, the highest incidence of microcephaly associated with the Zika virus (ZIKV) outbreak took place in the NE region of Brazil during the same years. In this work, we tested the hypothesis that saxitoxin (STX), a neurotoxin produced in South America by the freshwater cyanobacteria Raphidiopsis raciborskii, could have contributed to the most severe Congenital Zika Syndrome (CZS) profile described worldwide. Quality surveillance showed higher cyanobacteria amounts and STX occurrence in human drinking water supplies of NE compared to other regions of Brazil. Experimentally, we described that STX doubled the quantity of ZIKV-induced neural cell death in progenitor areas of human brain organoids, while the chronic ingestion of water contaminated with STX before and during gestation caused brain abnormalities in offspring of ZIKV-infected immunocompetent C57BL/6J mice. Our data indicate that saxitoxin-producing cyanobacteria is overspread in water reservoirs of the NE and might have acted as a co-insult to ZIKV infection in Brazil. These results raise a public health concern regarding the consequences of arbovirus outbreaks happening in areas with droughts and/or frequent freshwater cyanobacterial blooms.


Assuntos
Morte Celular/efeitos dos fármacos , Microcefalia/patologia , Envenenamento/complicações , Envenenamento/patologia , Saxitoxina/toxicidade , Infecção por Zika virus/complicações , Infecção por Zika virus/patologia , Animais , Toxinas Bacterianas/análise , Toxinas Bacterianas/toxicidade , Encéfalo/patologia , Brasil/epidemiologia , Células Cultivadas , Modelos Animais de Doenças , Surtos de Doenças , Feminino , Humanos , Incidência , Toxinas Marinhas/análise , Toxinas Marinhas/toxicidade , Camundongos Endogâmicos C57BL , Microcistinas/análise , Microcistinas/toxicidade , Modelos Teóricos , Neurotoxinas/análise , Neurotoxinas/toxicidade , Saxitoxina/análise , Água/química
9.
Ecotoxicol Environ Saf ; 195: 110465, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32199217

RESUMO

Complementary studies at different levels of the biological organization are fundamental to fully link environmental exposure to marine benthic dinoflagellate toxins and their effects. In order to contribute to this transdisciplinary evaluation, and for the first time, the present study aims to study the effects of Gambierdiscus excentricus, Ostreopsis cf. ovata, Prorocentrum hoffmannianum and Prorocentrum lima extracts on seven functionally different mammalian cell lines: HEK 293, HepG2, HNDF, H9c2(2-1), MC3T3-E1, Raw 264.7 and SH-SY5Y. All the cell lines presented cell mass decrease in a concentration-dependence of dinoflagellate extracts, exhibiting marked differences in cell toxicity. Gambierdiscus excentricus presented the highest effect, at very low concentrations with EC50,24h (i.e., the concentration that gives half-maximal response after a 24-h exposure) between 1.3 and 13 cells mL-1, followed by O. cf. ovata (EC50,24h between 3.3 and 40 cells mL-1), and Prorocentrum species (P. lima: EC50,24h between 191 and 1027 cells mL-1 and P. hoffmannianum: EC50,24h between 152 and 783 cells mL-1). Cellular specificities were also detected and rat cardiomyoblast H9c2(2-1) cells were in general the most sensitive to dinoflagellate toxic compounds, suggesting that this cell line is an animal-free potential model for dinoflagellate toxin testing. Finally, the sensitivity of cells expressing distinct phenotypes to each dinoflagellate extract exhibited low relation to human poisoning symptoms.


Assuntos
Dinoflagelados , Toxinas Marinhas/toxicidade , Animais , Linhagem Celular , Células HEK293 , Células Hep G2 , Humanos , Camundongos , Células RAW 264.7 , Ratos
10.
Harmful Algae ; 92: 101744, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32113611

RESUMO

The dinoflagellate genus Alexandrium comprises species that produce highly potent neurotoxins known as paralytic shellfish toxins (PST), and bioactive extracellular compounds (BEC) of unknown structure and ecological significance. The toxic bloom-forming species, Alexandrium minutum, is distributed worldwide and adversely affects many bivalves including the commercially and ecologically important Pacific oyster, Crassostrea gigas. In France, recurrent A. minutum blooms can co-occur with C. gigas spawning and larval development, and may endanger recruitment and population renewal. The present study explores how A. minutum affects oyster early development by exposing embryos and larvae, under controlled laboratory conditions, to two strains of A. minutum, producing only BEC or both PST and BEC. Results highlight the major role of BEC in A. minutum toxicity upon oyster development. The BEC strain caused lysis of embryos, the most sensitive stage to A. minutum toxicity among planktonic life stages. In addition, the non-PST-producing A. minutum strain inhibited hatching, disrupted larval swimming behavior, feeding, growth, and induced drastic decreases in survival and settlement of umbonate and eyed larvae (9 and 68 %, respectively). The findings indicated PST accumulation in oyster larvae (e.g. umbonate stages), possibly impairing development and settlement of larvae in response to the PST-producing strain. This work provides evidences that A. minutum blooms could hamper settlement of shellfish.


Assuntos
Crassostrea , Dinoflagelados , Toxinas Marinhas , Animais , França , Larva , Toxinas Marinhas/toxicidade
11.
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
12.
PLoS One ; 15(2): e0228414, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32032360

RESUMO

As reef-building corals are increasingly being exposed to persistent threats that operate on both regional and global scales, there is a pressing need to better understand the complex processes that diminish coral populations. This study investigated the impacts of the Florida red tide dinoflagellate Karenia brevis and associated brevetoxins on selected facets of coral biology using Porites astreoides as a model system. When provided with choice assays, P. astreoides larvae were shown to actively avoid seawater containing red tide (5×105 cells L-1-7.6×106 cells L-1) or purified brevetoxins (0.018 µg mL-1 brevetoxin-2 and 0.0018 µg mL-1 brevetoxin-3). However, forced exposure to similar treatments induced time-dependent physiological and behavioral changes that were captured by PAM fluorometry and settlement and survival assays, respectively. Adult fragments of P. astreoides exposed to red tide or associated brevetoxins displayed signs of proteomic alterations that were characterized by the use of an iTRAQ-based quantitative proteomic analysis. The novel use of this technique with P. astreoides demonstrated that protein regulation was highly contingent upon biological versus chemical treatment (i.e. live K. brevis vs. solely brevetoxin exposure) and that several broad pathways associated with cell stress were affected including redox homeostasis, protein folding, energy metabolism and reactive oxygen species production. The results herein provide new insight into the ecology, behavior and sublethal stress of reef-building corals in response to K. brevis exposure and underscore the importance of recognizing the potential of red tide to act as a regional stressor to these important foundation species.


Assuntos
Dinoflagelados/patogenicidade , Ecossistema , Exposição Ambiental/efeitos adversos , Proliferação Nociva de Algas/fisiologia , Larva/metabolismo , Toxinas Marinhas/toxicidade , Oxocinas/toxicidade , Proteoma/análise , Animais , Proliferação Nociva de Algas/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Proteômica
13.
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
14.
Toxicon ; 174: 48-56, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31989929

RESUMO

Paralytic shellfish poisoning is a human intoxication syndrome associated with the consumption of seafood that has been contaminated with paralytic shellfish toxins (PSTs), a group of natural neurotoxic alkaloids produced by marine dinoflagellates, including some Alexandrium species. This study presents findings of PSTs in mussels (Mytilus galloprovincialis) during 2018-2019 in several mollusc production areas of Sardinia (Italy, western Mediterranean). Investigations of the presence and abundance of PST-producing microalgal species in marine water and of the toxins associated with shellfish were carried out concomitantly. Overall, the results suggested a spatio-temporal expansion of Alexandriumpacificum and Alexandriumminutum in recent years, with an increasing number of PSTs present in molluscs and increased occurrences of toxicity cases. Liquid chromatography with fluorescence detection determined the toxin profile to be composed primarily of the carbamate gonyautoxin-5 and N-sulphocarbamoyltoxins 1 and 2. The study highlights the potential high risk to consumers of poisoning by bivalve molluscs bred in Sardinia, where shellfish production is a very important industrial sector. For this reason, routine monitoring is strongly recommended in order to mitigate any harm to human health as well as negative socio-economic consequences.


Assuntos
Aquicultura , Dinoflagelados , Toxinas Marinhas/toxicidade , Moluscos , Animais , Humanos , Itália , Mytilus , Frutos do Mar , Intoxicação por Frutos do Mar
15.
J Agric Food Chem ; 68(5): 1427-1435, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31913622

RESUMO

A number of new C-11 hydroxyl metabolites (so-called M-toxins) of paralytic shellfish toxins (PSTs) have been discovered in contaminated shellfish, and trace amounts have also been detected in some strains of PST-producing microalgae. To investigate the chemical conversion and stability of M-toxins, mussel extracts were purified with solid-phase extraction cartridges (Oasis HLB) and Biogel P-2 resin columns and four partially purified M-toxin fractions were stored at different temperatures (-20, 4, and 20 °C) and pH values (3, 4, and 5). The concentrations and profiles of M-toxins in these fractions were analyzed using liquid chromatography coupled with tandem mass spectrometry for 27 weeks. Results further confirmed the chemical conversion pathway M1 → M3 → M5 and determined for the first time two new transformation pathways: M2 → M4 → M6 and neosaxitoxin (NEO) → M10. The half-lives of M1, M2, M4, and M10 were calculated using a first-order degradation kinetics model, which indicated that the degradation of all M-toxins was dependent upon the temperature and pH, increasing with rising temperature and pH. In comparison to M4 and M10, M1 was more sensitive to the temperature, followed by M2. Results suggest that M-toxins should be maintained at a low temperature (-20 °C) and low pH (3) for their prolonged storage. M-toxins were less stable than all of the common analogues of PSTs, which may be beneficial for shellfish to achieve rapid detoxification through transformation of PSTs to M-toxins. These new findings are of significance because they enable further understanding of the metabolism of PSTs and their detoxification mechanisms in contaminated shellfish.


Assuntos
Bivalves/química , Toxinas Marinhas/química , Frutos do Mar/toxicidade , Animais , Cromatografia Líquida de Alta Pressão , Contaminação de Alimentos/análise , Concentração de Íons de Hidrogênio , Toxinas Marinhas/toxicidade , Estrutura Molecular , Frutos do Mar/análise , Espectrometria de Massas em Tandem , Temperatura
16.
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
17.
Environ Pollut ; 259: 113890, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31918145

RESUMO

Eutrophication and warming lead to frequent occurrence of cyanobacterial blooms, which significantly impact on zooplankton. Freshwater zooplankton Daphnia adopts two distinct ways of reproduction: asexual (parthenogenetic) reproduction for rapidly reproducing many offspring in favorable environment and sexual reproduction for producing resting eggs as seed bank to survive in harsh environments. Daphnia pulex has worse performance in growth and reproduction under the exposure to toxic cyanobacteria Microcystis aeruginosa and tends to allocate less energy to reproduction in the case of insufficient food. However, the relative reproductive allocation strategy (energy allocation) of D. pulex individuals exposed to toxic M. aeruginosa is still unclear. Here we tested the relative reproductive performance of D. pulex fed on solely Chlorella pyrenoidosa (high quality food) or Chlorella mixed with toxic M. aeruginosa (low quality food), based on the parthenogenetic reproduction (life-history experiments) and sexual reproduction (population experiments). The results showed that under low quality food conditions, D. pulex reproduced fewer offspring which were also smaller and thus led to a reduced absolute output in parthenogenetic reproduction, but produced ephippia in the same size and quantity compared to those cultured under high quality food conditions. However, as the body size of maternal D. pulex cultured under low quality food conditions decreased, the relative reproductive allocation significantly increased in both parthenogenetic and sexual reproduction, compared to those cultured under high quality food conditions. In conclusion, D. pulex tend to allocate relatively more energy to reproduction under Microcystis conditions, which is a reasonable strategy for it to decentralize the risks from low-quality food.


Assuntos
Toxinas Bacterianas , Chlorella , Daphnia , Toxinas Marinhas , Microcistinas , Microcystis , Animais , Toxinas Bacterianas/toxicidade , Daphnia/efeitos dos fármacos , Daphnia/metabolismo , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Microcystis/química , Reprodução/efeitos dos fármacos
18.
Mar Drugs ; 18(1)2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31936833

RESUMO

Respiratory exposure to marine phycotoxins is of increasing concern. Inhalation of sea spray aerosols (SSAs), during harmful Karenia brevis and Ostreopsis ovata blooms induces respiratory distress among others. The biogenics hypothesis, however, suggests that regular airborne exposure to natural products is health promoting via a downregulation of the mechanistic target of rapamycin (mTOR) pathway. Until now, little scientific evidence supported this hypothesis. The current explorative in vitro study investigated both health-affecting and potential health-promoting mechanisms of airborne phycotoxin exposure, by analyzing cell viability effects via cytotoxicity assays and effects on the mTOR pathway via western blotting. To that end, A549 and BEAS-2B lung cells were exposed to increasing concentrations (ng·L-1 - mg·L-1) of (1) pure phycotoxins and (2) an extract of experimental aerosolized homoyessotoxin (hYTX). The lowest cell viability effect concentrations were found for the examined yessotoxins (YTXs). Contradictory to the other phycotoxins, these YTXs only induced a partial cell viability decrease at the highest test concentrations. Growth inhibition and apoptosis, both linked to mTOR pathway activity, may explain these effects, as both YTXs were shown to downregulate this pathway. This proof-of-principle study supports the biogenics hypothesis, as specific aerosolizable marine products (e.g., YTXs) can downregulate the mTOR pathway.


Assuntos
Aerossóis/farmacologia , Exposição Ambiental , Pulmão/efeitos dos fármacos , Toxinas Marinhas/farmacologia , Serina-Treonina Quinases TOR/metabolismo , Células A549 , Aerossóis/toxicidade , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Proliferação Nociva de Algas , Humanos , Técnicas In Vitro , Toxinas Marinhas/toxicidade , Oxocinas/farmacologia , Transdução de Sinais/efeitos dos fármacos
19.
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
20.
Chemosphere ; 241: 125060, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629243

RESUMO

Eutrophication of freshwater bodies increases the occurrence of toxic cyanobacterial blooms. The cyanobacterial toxin cylindrospermopsin (CYN) is receiving great interest due to its increasing presence in waterbodies. However, the toxic effects of CYN on zebrafish development are poorly understood, especially the toxicological mechanism, which is still unclear. In this study, we examined the adverse effects of CYN on embryonic development in zebrafish. CYN (2-2000 nM) exposure decreased embryos survival rate, hatching rate, body length and eye size in a concentration-dependent manner and caused abnormalities in embryo morphology, including pericardial edema, spinal curvature, tail deformity, uninflated swim bladder, cardiac and vascular defects. CYN at concentrations of 20 nM or higher significantly increased ROS level and promoted cell apoptosis in zebrafish embryos. To preliminarily elucidate the potential mechanism of zebrafish developmental toxicity caused by CYN, we examined the expression of oxidative stress- and apoptotic-related genes. CYN could promote the expression of oxidative stress-related genes (SOD1, CAT and GPx1) and induce changes in transcriptional levels of apoptotic-related genes (p53, Bax and Bcl-2). Taken together, CYN induced adverse effects on zebrafish embryos development, which may associate with oxidative stress and apoptosis. These outcomes will advance our understanding of CYN toxicity, environmental problems and health hazards caused by climate changes and eutrophication.


Assuntos
Toxinas Bacterianas/toxicidade , Desenvolvimento Embrionário/efeitos dos fármacos , Microcistinas/efeitos dos fármacos , Uracila/análogos & derivados , Peixe-Zebra/embriologia , Animais , Apoptose/efeitos dos fármacos , Cianobactérias/patogenicidade , Embrião não Mamífero/efeitos dos fármacos , Eutrofização , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , Uracila/toxicidade , Peixe-Zebra/metabolismo
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