RESUMO
The reproduction toxicity of pubertal exposure to Microcystin-LR (MC-LR) and the underlying mechanism needs to be further investigated. In the current study, pubertal male ICR mice were intraperitoneally injected with 2⯵g/kg MC-LR for four weeks. Pubertal exposure to MC-LR decreased epididymal sperm concentration and blocked spermatogonia proliferation. In-vitro studies found MC-LR inhibited cell proliferation of GC-1 cells and arrested cell cycle in G2/M phase. Mechanistically, MC-LR exposure evoked excessive reactive oxygen species (ROS) and induced DNA double-strand break in GC-1 cells. Besides, MC-LR inhibited DNA repair by reducing PolyADP-ribosylation (PARylation) activity of PARP1. Further study found MC-LR caused proteasomal degradation of SIRT6, a monoADP-ribosylation enzyme which is essential for PARP1 PARylation activity, due to destruction of SIRT6-USP10 interaction. Additionally, MG132 pretreatment alleviated MC-LR-induced SIRT6 degradation and promoted DNA repair, leading to the restoration of cell proliferation inhibition. Correspondingly, N-Acetylcysteine (NAC) pre-treatment mitigated the disturbed SIRT6-USP10 interaction and SIRT6 degradation, causing recovered DNA repair and subsequently restoration of cell proliferation inhibition in MC-LR treated GC-1 cells. Together, pubertal exposure to MC-LR induced spermatogonia cell cycle arrest and sperm count reduction by oxidative DNA damage and simultaneous SIRT6-mediated DNA repair failing. This study reports the effect of pubertal exposure to MC-LR on spermatogenesis and complex mechanism how MC-LR induces spermatogonia cell proliferation inhibition.
Assuntos
Toxinas Marinhas , Microcistinas , Sirtuínas , Espermatogônias , Animais , Masculino , Camundongos , Apoptose , Proliferação de Células , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Camundongos Endogâmicos ICR , Microcistinas/metabolismo , Microcistinas/toxicidade , Sêmen , Sirtuínas/efeitos dos fármacos , Sirtuínas/metabolismo , Espermatogônias/efeitos dos fármacos , Espermatogônias/metabolismoRESUMO
Domoic acid (DA) is a marine neurotoxin produced as a defence compound by diatom Pseudo-nitzschia. Although its toxicity is well known in marine mammals and fish, data on DA cyto/genotoxicity in human non-target cells is still limited. Hence, we aimed to study the effect of DA (0.001-10 µg/mL) on cell viability and proliferation kinetics of human hepatocellular carcinoma (HepG2) cells as well as DNA damage induction after 4, 24 and 72 h of exposure. The results revealed that DA up to 10 µg/mL did not elicit significant changes in HepG2 cell viability, proliferation and cell cycle at applied conditions. DA did not generate DNA double-strand breaks, while it exhibited significant dose- and time-dependent increase of DNA damage in the form of either DNA single-strand breaks or alkali labile sites. Additionally, increased malondialdehyde level after DA treatment indicated oxidative damage to lipids. Altogether, the results showed that neurotoxin DA induced only minor adverse genotoxic effects in non-target HepG2 cells that most probably occurred resulting from the oxidative stress. However, additional research is needed to further elucidate the mechanisms of DA toxicity, particularly in terms of chronic exposure, as well as to understand its potential influence on human non-target cells.
Assuntos
Diatomáceas , Neurotoxinas , Animais , DNA/metabolismo , Diatomáceas/metabolismo , Células Hep G2 , Humanos , Ácido Caínico/análogos & derivados , Ácido Caínico/toxicidade , Mamíferos , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Neurotoxinas/toxicidadeRESUMO
Scombroid poisoning, systemic mastocytosis, and hereditary alpha tryptasemia all present with episodes that resemble allergic reactions. Knowledge regarding systemic mastocytosis and hereditary alpha tryptasemia is quickly evolving. Epidemiology, pathophysiology, and strategies to identify and diagnose are discussed. Evidence-based management in the emergency setting and beyond is also explored and summarized. Key differences are described between these events and allergic reactions.
Assuntos
Angioedema/diagnóstico , Hipersensibilidade/diagnóstico , Toxinas Marinhas/biossíntese , Angioedema/fisiopatologia , Mimetismo Biológico , Humanos , Hipersensibilidade/fisiopatologia , Toxinas Marinhas/metabolismo , Triptases/análise , Triptases/deficiênciaRESUMO
The bloom-forming toxic dinoflagellate Alexandrium catenella was first detected in southern Chile (39.5-55° S) 50 years ago and is responsible for most of the area's cases of paralytic shellfish poisoning (PSP). Given the complex life history of A. catenella, which includes benthic sexual cysts, in this study, we examined the potential link between latitude, toxicity, and sexual compatibility. Nine clones isolated from Chilean Patagonia were used in self- and out-crosses in all possible combinations (n = 45). The effect of latitude on toxicity, reproductive success indexes, and cyst production was also determined. Using the toxin profiles for all strains, consisting of C1, C2, GTX4, GTX1, GTX3, and NeoSTX, a latitudinal gradient was determined for their proportions (%) and content per cell (pg cell-1), with the more toxic strains occurring in the north (-40.6° S). Reproductive success also showed a latitudinal tendency and was lower in the north. None of the self-crosses yielded resting cysts. Rather, the production of resting cysts was highest in pairings of clones separated by distances of 1000-1650 km. Our results contribute to a better understanding of PSP outbreaks in the region and demonstrate the importance of resting cysts in fueling new toxic events. They also provide additional evidence that the introduction of strains from neighboring regions is a cause for concern.
Assuntos
Dinoflagellida/genética , Dinoflagellida/metabolismo , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Chile , DNA Espaçador Ribossômico/genética , Eutrofização , Toxinas Marinhas/genética , ReproduçãoRESUMO
Microcystin-leucine arginine (MC-LR) is a kind of toxin produced by cyanobacterial, resulting in decrease of testosterone levels in serum and leading to impaired spermatogenesis. Gonadotropin-releasing hormone (GnRH) neurons play crucial roles in the regulation of testosterone release. Meanwhile, it has been demonstrated that MC-LR is capable of entering the GnRH neurons and inducing apoptosis. Nevertheless, the molecular mechanism of MC-LR induced apoptosis of GnRH neurons remains elusive. In present study, we found that MC-LR inhibited the cell viability of GT1-7 cells. In addition, we discovered apoptosis of GnRH neurons and GT1-7 cells treated with MC-LR. And increased intracellular ROS production and the release of intracellular Ca2+ were all observed following exposure to MC-LR. Furthermore, we also found the endoplasmic reticulum stress (ERs) and autophagy were activated by MC-LR. Additionally, pretreatment of the ERs inhibitor (4-Phenyl butyric acid) reduced the apoptotic rate of GT1-7 cells comparing with MC-LR exposure alone. Comparing with MC-LR treatment alone, apoptotic cell death was increased by pretreatment of GT1-7 cells with an autophagy inhibitor (3-methyladenine). Together, our data implicated that the treatment of MC-LR induced the apoptosis of GnRH neurons by activating the ERs resulting in a decrease of serum testosterone level in mice. Autophagy is a protective cellular process which was activated by ER stress and thus protected cells from apoptosis upon MC-LR exposure.
Assuntos
Estresse do Retículo Endoplasmático , Microcistinas/toxicidade , Testosterona/sangue , Animais , Apoptose , Arginina/metabolismo , Bioensaio , Sobrevivência Celular , Cianobactérias/metabolismo , Hormônio Liberador de Gonadotropina/metabolismo , Leucina/metabolismo , Masculino , Toxinas Marinhas/metabolismo , Camundongos , Microcistinas/metabolismo , Neurônios/metabolismo , Testosterona/metabolismoRESUMO
Nemerteans (ribbon worms) employ toxins to subdue their prey, but research thus far has focused on the small-molecule components of mucus secretions and few protein toxins have been characterized. We carried out a preliminary proteotranscriptomic analysis of putative toxins produced by the hoplonemertean Amphiporus lactifloreus (Hoplonemertea, Amphiporidae). No variants were found of known nemertean-specific toxin proteins (neurotoxins, cytotoxins, parbolysins or nemertides) but several toxin-like transcripts were discovered, expressed strongly in the proboscis, including putative metalloproteinases and sequences resembling sea anemone actitoxins, crown-of-thorn sea star plancitoxins, and multiple classes of inhibitor cystine knot/knottin family proteins. Some of these products were also directly identified in the mucus proteome, supporting their preliminary identification as secreted toxin components. Two new nemertean-typical toxin candidates could be described and were named U-nemertotoxin-1 and U-nemertotoxin-2. Our findings provide insight into the largely overlooked venom system of nemerteans and support a hypothesis in which the nemertean proboscis evolved in several steps from a flesh-melting organ in scavenging nemerteans to a flesh-melting and toxin-secreting venom apparatus in hunting hoplonemerteans.
Assuntos
Perfilação da Expressão Gênica , Invertebrados/genética , Invertebrados/metabolismo , Toxinas Marinhas/genética , Toxinas Marinhas/metabolismo , Proteoma , Proteômica , Transcriptoma , Animais , Bases de Dados GenéticasRESUMO
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
Dinoflagellida/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/metabolismoRESUMO
Cyanobacteria harmful algal blooms (CHABs) are primarily caused by man-made eutrophication and increasing climate-change conditions. The presence of heavy metal runoff in affected water systems may result in CHABs alteration to their ecological interactions. Certain CHABs produce by-products, such as microcystin (MC) cyanotoxins, that have detrimentally affected humans through contact via recreation activities within implicated water bodies, directly drinking contaminated water, ingesting biomagnified cyanotoxins in seafood, and/or contact through miscellaneous water treatment. Metallothionein (MT) is a small, metal-sequestration cysteine rich protein often upregulated within the stress response mechanism. This study focused on zinc metal resistance and stress response in a toxigenic cyanobacterium, Microcystis aeruginosa UTEX LB 2385, by monitoring cells with (0, 0.1, 0.25, and 0.5 mg/L) ZnCl2 treatment. Flow cytometry and phase contrast microscopy were used to evaluate physiological responses in cultures. Molecular assays and an immunosorbent assay were used to characterize the expression of MT and MC under zinc stress. The results showed that the half maximal inhibitory concentration (IC50) was 0.25 mg/L ZnCl2. Flow cytometry and phase contrast microscopy showed morphological changes occurred in cultures exposed to 0.25 and 0.5 mg/L ZnCl2. Quantitative PCR (qPCR) analysis of selected cDNA samples showed significant upregulation of Mmt through all time points, significant upregulation of mcyC at a later time point. ELISA MC-LR analysis showed extracellular MC-LR (µg/L) and intracellular MC-LR (µg/cell) quota measurements persisted through 15 days, although 0.25 mg/L ZnCl2 treatment produced half the normal cell biomass and 0.5 mg/L treatment largely inhibited growth. The 0.25 and 0.5 mg/L ZnCl2 treated cells demonstrated a ~40% and 33% increase of extracellular MC-LR(µg/L) equivalents, respectively, as early as Day 5 compared to control cells. The 0.5 mg/L ZnCl2 treated cells showed higher total MC-LR (µg/cell) quota yield by Day 8 than both 0 mg/L ZnCl2 control cells and 0.1 mg/L ZnCl2 treated cells, indicating release of MCs upon cell lysis. This study showed this Microcystis aeruginosa strain is able to survive in 0.25 mg/L ZnCl2 concentration. Certain morphological zinc stress responses and the upregulation of mt and mcy genes, as well as periodical increased extracellular MC-LR concentration with ZnCl2 treatment were observed.
Assuntos
Cloretos/farmacologia , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Microcystis/efeitos dos fármacos , Compostos de Zinco/farmacologia , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Metalotioneína/genética , Microcystis/genética , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismoRESUMO
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/métodosRESUMO
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 Argonautas/genética , Proteínas Argonautas/metabolismo , Toxinas Bacterianas/metabolismo , Linhagem Celular Tumoral , Toxinas de Cianobactérias , 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 adversosRESUMO
New C-11 hydroxyl metabolites of paralytic shellfish toxins (PSTs) have been reported in shellfish. To gain further information on these metabolites, as well as the potential for formation of phase-II metabolites and acyl esters of PSTs, bivalves were fed with the PSTs-producing dinoflagellate Alexandrium pacificum (strain ATHK). Through independent experiments, scallops (Chlamys farreri) were fed for 9â¯days and mussels (Mytilus galloprovincialis) for 5â¯days plus an additional 5â¯days of depuration, with representative samples taken throughout. Several common PSTs (C1-4, GTX1-6 and NEO) and metabolites including M1, M3, M5, M7, M9, M2 and M8 were detected in the hepatopancreas of scallops during toxin accumulation and in the hepatopancreas of mussels during both toxin accumulation and elimination periods. The relative molar ratio of metabolites to precursor molecules was used to estimate relative metabolic conversion rates. Conversion rates of C1/2 and GTX2/3 were higher than those of C3/4 and GTX1/4, in scallops and mussels. The first metabolites observed in both bivalve species investigated were M1/3, which are formed from C1/2. However, the conversion of GTX2/3 to M2 was more complete than other biotransformation reactions in both mussels and scallops. In general, metabolic conversion of PSTs was observed after a shorter time and to a greater extent in mussels than in scallops in the exposure period. No acyl esters or conjugation products of PSTs with glucuronic acid, glutathione, cysteine and taurine were detected by liquid chromatography with high resolution tandem mass spectrometry in the samples investigated. Additionally, only GTX1/4 and GTX2/3 were detected in the kidney of scallops, which demonstrates that PSTs are mainly metabolized through the hepatic metabolism pathway in bivalves. This work improves the understanding of PST metabolism during toxin accumulation and depuration in commercially harvested shellfish.
Assuntos
Bivalves/fisiologia , Exposição Ambiental , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Mytilus/fisiologia , Paralisia/patologia , Pectinidae/metabolismo , Intoxicação por Frutos do Mar/patologia , Animais , Bivalves/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Toxinas Marinhas/química , Metaboloma , Mytilus/efeitos dos fármacos , Espectrometria de Massas em Tandem , Fatores de Tempo , Poluentes Químicos da Água/toxicidadeRESUMO
Controlled laboratory experiments were conducted to test the effects of copper (Cu2+) and butyltins (BuT) on the growth, photosynthetic activity and toxin content of two HABs (Harmful Algal Blooms) dinoflagellates, the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata. Microalgae were exposed to increasing concentrations of Cu2+ (10-4 to 31â¯nM) or BuT (0.084 to 84â¯nM) for seven days. When considering the growth, EC50 values were 0.16 (±0.09) nM and 0.03 (±0.02) nM of Cu2+ for A. catenella and O. cf. ovata, respectively. Regarding BuT, EC50 was 14.2 (±6) nM for O. cf. ovata, while A. catenella growth inhibition appeared at BuT concentrations ≥27â¯nM. Photosynthetic activity of the studied dinoflagellates decreased with increasing Cu and BuT concentrations. For O. cf. ovata, the response of this physiological parameter to contamination was less sensitive than the biomass. Cu exposure induced the formation of temporary cysts in both organisms that could resist adverse conditions. The ovatoxin-a and -b concentrations in O. cf. ovata cells increased significantly in the presence of Cu. Altogether, the results suggest a better tolerance of the planktonic A. catenella to Cu and BuT. This could result in a differentiated selection pressure exerted by these metals on phytoplankton species in highly polluted waters. The over-production of toxins in response to Cu stress could pose supplementary health and socio-economic threats in the contaminated marine ecosystems where HABs develop.
Assuntos
Cobre/toxicidade , Dinoflagellida/efeitos dos fármacos , Compostos Orgânicos de Estanho/toxicidade , Fotossíntese/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Biomassa , Dinoflagellida/crescimento & desenvolvimento , Dinoflagellida/metabolismo , Toxinas Marinhas/metabolismo , Microalgas/efeitos dos fármacos , Microalgas/metabolismo , Plâncton/efeitos dos fármacos , Plâncton/metabolismo , Poluentes Químicos da Água/químicaRESUMO
Cancer cell cytotoxicity was used to guide the isolation of nine new swinholide-related compounds, named samholides A-I (1-9), from an American Samoan marine cyanobacterium cf. Phormidium sp. Their structures were determined by extensive analysis of 1D and 2D NMR spectroscopic data. The new compounds share an unusual 20-demethyl 44-membered lactone ring composed of two monomers, and they demonstrate structural diversity arising from geometric isomerization of double bonds, sugar units with unique glyceryl moieties and varied methylation patterns. All of the new samholides were potently active against the H-460 human lung cancer cell line with IC50 values ranging from 170 to 910 nM. The isolation of these new swinholide-related compounds from a marine cyanobacterium reinvigorates questions concerning the evolution and biosynthetic origin of these natural products.
Assuntos
Antineoplásicos/metabolismo , Antineoplásicos/farmacologia , Cianobactérias/metabolismo , Toxinas Marinhas/metabolismo , Toxinas Marinhas/farmacologia , Antineoplásicos/química , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Toxinas Marinhas/químicaRESUMO
In order to assess the effects of Fe-enrichment on the growth and domoic acid (DA) production of the toxigenic diatom Pseudo-nitzschia multiseries, static cultures that received the addition of different iron (Fe) concentrations were maintained for 30 days. Intra- and extracellular DA concentrations were evaluated over time, and growth and chain-formation were compared to those of non-toxic diatoms, Bacillaria sp. Growth rates of P. multiseries (µ = 0.45-0.73 d-1) were similar among cultures containing different Fe concentrations. Likewise, the similar incidence and length of P. multiseries stepped cell chains (usually 2-4; up to 8-cell long) among the treatments reinforces that the cultures were not growth-inhibited under any condition tested, suggesting an efficient Fe acquisition mechanism. Moreover, DA concentrations were significantly higher under the highest Fe concentration, indicating that Fe is required for toxin synthesis. Bacillaria sp. reached comparable growth rates under the same Fe concentrations, except when the dissolved cell contents from a P. multiseries culture was added. The 50-70% reduction in cell density and 70-90% decrease in total chlorophyll-a content of Bacillaria sp. at early stationary growth phase indicates, for the first time, an allelopathic effect of undetermined compounds released by Pseudo-nitzschia to another diatom species.
Assuntos
Alelopatia/efeitos dos fármacos , Diatomáceas/fisiologia , Ferro/farmacologia , Toxinas Marinhas/metabolismo , Neurotoxinas/metabolismo , Alimentos Marinhos/toxicidade , Técnicas de Cultura de Células/métodos , Células Cultivadas , Clorofila/metabolismo , Clorofila A , Diatomáceas/efeitos dos fármacos , Humanos , Ácido Caínico/análogos & derivados , Ácido Caínico/metabolismo , Ácido Caínico/toxicidade , Toxinas Marinhas/toxicidade , Neurotoxinas/toxicidadeRESUMO
PTX-2 is a marine biotoxin frequently found in shellfish that can lead to food intoxication in humans. Information regarding PTX-2 metabolism is scarce, and little is known of its effect on xenobiotic-metabolizing enzymes (XME) or its molecular pathways. The aim of this study was consequently to examine PTX-2 Phase I metabolism using rat and human liver S9 fractions, and also to assess the capability of PTX-2: (i) to modulate the gene expression of a panel of Phase I (CYP450) and II (UGT, SULT, NAT, and GST) enzymes, as well as the Phase III or 0 (ABC and SLCO) transporters in the human hepatic HepaRG cell line using qPCR; (ii) to induce specific CYP450 in HepaRG cells measured by immunolabeling detection and the measurement of the cells' activities; and (iii) to activate nuclear receptors and induce CYP promoter activities in HEK-T and HepG2 transfected cell lines using transactivation and reporter gene assay, respectively. Our results indicate that PTX-2 hydroxylation occurred with both rat and human S9 fractions. Whereas PTX-2 mostly upregulated the gene expression of CYP1A1 and 1A2, no induction of these two CYP activities was observed. Lastly, PTX-2 did not act as an agonist of CAR or PXR. Due to its effects on some key XME, more attention should be paid to possible drug-drug interactions with phycotoxins, especially as shellfish can accumulate several phycotoxins as well as other kinds of contaminants.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Furanos/metabolismo , Fígado/metabolismo , Toxinas Marinhas/metabolismo , Piranos/metabolismo , Animais , Linhagem Celular , Linhagem Celular Tumoral , Sistema Enzimático do Citocromo P-450/genética , Expressão Gênica , Humanos , Macrolídeos , Proteínas de Membrana Transportadoras/genética , Ratos , Receptores de Hidrocarboneto Arílico/genética , Transferases/genética , Xenobióticos/metabolismoRESUMO
Microcystins are globally the most commonly occurring freshwater cyanotoxins, causing acute poisoning and chronically inducing hepatocellular carcinoma. However, the detection and toxicological study of microcystins is hampered by the limited availability and high cost of pure toxin standards. Biosynthesis of microcystin variants in a fast-growing heterologous host offers a promising method of achieving reliable and economically viable alternative to isolating toxin from slow-growing cyanobacterial cultures. Here, we report the heterologous expression of recombinant microcystin synthetases in Escherichia coli to produce [d-Asp3]microcystin-LR and microcystin-LR. We assembled a 55 kb hybrid polyketide synthase/nonribosomal peptide synthetase gene cluster from Microcystis aeruginosa PCC 7806 using Red/ET recombineering and replaced the native promoters with an inducible PtetO promoter to yield microcystin titers superior to M. aeruginosa. The expression platform described herein can be tailored to heterologously produce a wide variety of microcystin variants, and potentially other cyanobacterial natural products of commercial relevance.
Assuntos
Toxinas Bacterianas/biossíntese , Toxinas Bacterianas/genética , Cianobactérias/genética , Escherichia coli/genética , Microbiologia Industrial/métodos , Toxinas Marinhas/biossíntese , Toxinas Marinhas/genética , Microcistinas/química , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Proteínas de Bactérias/genética , Toxinas Bacterianas/metabolismo , Cianobactérias/enzimologia , Toxinas de Cianobactérias , Toxinas Marinhas/metabolismo , Microcistinas/biossíntese , Microcistinas/genética , Microcistinas/metabolismo , Família Multigênica/genética , Peptídeo Sintases/genética , Regiões Promotoras Genéticas/genéticaRESUMO
Cyanobacteria were present on the earth 3.5 billion years ago; since then they have colonized almost all terrestrial and aquatic ecosystems. They produce a high number of bioactive molecules, among which some are cyanotoxins. Cyanobacterial growth at high densities, forming blooms, is increasing in extension and frequency, following anthropogenic activities and climate changes, giving rise to some concern for human health and animal life exposed to cyanotoxins. Numerous cases of lethal poisonings have been associated with cyanotoxins ingestion in wild animal and livestock. In humans few episodes of lethal or severe human poisonings have been recorded after acute or short-term exposure, but the repeated/chronic exposure to low cyanotoxin levels remains a critical issue. The properties of the most frequently detected cyanotoxins (namely, microcystins, nodularins, cylindrospermopsin and neurotoxins) are here critically reviewed, describing for each toxin the available information on producing organisms, biosynthesis/genetic and occurrence, with a focus on the toxicological profile (including kinetics, acute systemic toxicity, mechanism and mode of action, local effects, repeated toxicity, genotoxicity, carcinogenicity, reproductive toxicity; human health effects and epidemiological studies; animal poisoning) with the derivation of health-based values and considerations on the risks for human health.
Assuntos
Toxinas Bacterianas/metabolismo , Toxinas Bacterianas/toxicidade , Cianobactérias/metabolismo , Medição de Risco/métodos , Alcaloides , Animais , Produtos Agrícolas , Toxinas de Cianobactérias , Água Potável , Contaminação de Alimentos , Humanos , Toxinas Marinhas/metabolismo , Toxinas Marinhas/toxicidade , Microcistinas/metabolismo , Microcistinas/toxicidade , Neurotoxinas/toxicidade , Peptídeos Cíclicos/toxicidade , Alimentos Marinhos , Testes de Toxicidade/métodos , Uracila/análogos & derivados , Uracila/toxicidadeRESUMO
Due to eutrophication processes in our water bodies, cyanobacterial blooms can develop worldwide. Most of these blooms are toxic. The most prominent cyanobacterial toxins are the group of the microcystins, which are cyclic heptapeptides, currently with more than 100 congeners known. The biotransformation of microcystins starts with the conjugation to the cell internal tripeptide glutathione, catalysed by glutathione S-transferase enzymes. This conjugate is further broken down to a cysteine conjugate, enhancing the cell internal transport and excretion of the conjugated toxin from the organisms. Still many questions remain open, thinking on an obviously good working detoxification system on the one side and the often seen negative effects up to the death of humans on the other sides.
Assuntos
Toxinas Bacterianas/metabolismo , Cianobactérias/metabolismo , Glutationa/metabolismo , Toxinas Marinhas/metabolismo , Redes e Vias Metabólicas , Microcistinas/metabolismo , Animais , Toxinas Bacterianas/toxicidade , Biotransformação , Toxinas de Cianobactérias , Sistema Enzimático do Citocromo P-450/metabolismo , Glutationa/toxicidade , Humanos , Toxinas Marinhas/toxicidade , Microcistinas/toxicidadeRESUMO
In recent years, cyanobacterial blooms have dramatically increased and become an ecological disaster worldwide. Cyanobacteria are also known to produce a wide variety of toxic secondary metabolites, i.e. cyanotoxins. Microcystins (MCs), a group of cyclic heptapeptides, are considered to be one of the most common and dangerous cyanobacterial toxins. MCs can be incorporated into the cells via organic anion transporting polypeptides (Oatps). It's widely accepted that inhibition of protein phosphatases (PPs) and induction of oxidative stress are the main toxic mechanisms of MCs. MCs are able to induce a variety of toxic cellular effects, including DNA damage, cytoskeleton disruption, mitochondria dysfunction, endoplasmic reticulum (ER) disturbance and cell cycle deregulation, all of which can contribute to apoptosis/programmed cell death. This review aimed to summarize the increasing data regarding the intracellular biochemical and molecular mechanisms of MC-induced toxicity and cell death.
Assuntos
Apoptose , Toxinas Bacterianas/toxicidade , Cianobactérias/metabolismo , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Animais , Apoptose/efeitos dos fármacos , Toxinas Bacterianas/análise , Toxinas Bacterianas/metabolismo , Ciclo Celular/efeitos dos fármacos , Cianobactérias/química , Toxinas de Cianobactérias , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/genética , Citoesqueleto/metabolismo , Citoesqueleto/patologia , Dano ao DNA/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Humanos , Toxinas Marinhas/análise , Toxinas Marinhas/metabolismo , Microcistinas/análise , Microcistinas/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Estresse Oxidativo/efeitos dos fármacos , Fosfoproteínas Fosfatases/antagonistas & inibidoresRESUMO
Okadaic acid is known as a diarrheal shellfish poison. It is thought that there is no specific target organ for okadaic acid after it has been absorbed into the body. However, the details of its pharmacokinetics are still unknown. In this study, we demonstrated that okadaic acid was more toxic to the hepatocyte-specific uptake transporter OATP1B1- or OATP1B3-expressing cells than control vector-transfected cells. In addition, PP2A activity, which is a target molecule of okadaic acid, was more potently inhibited by okadaic acid in OATP1B1- or OATP1B3-expressing cells compared with control vector-transfected cells. The cytotoxicity of okadaic acid in OATP1B1- or OATP1B3-expressing cells was attenuated by known substrates of OATP1B1- and OATP1B3, but not in control vector-transfected cells. Furthermore, after uptake inhibition study using OATP1B3-expressing cells, Dixon plot showed that okadaic acid inhibited the uptake of hepatotoxin microcystin-LR, which is a substrate for OATP1B1 and OATP1B3, in a competitive manner. These results strongly suggested that okadaic acid is a substrate for OATP1B3 and probably for OATP1B1, and could be involved in unknown caused liver failure and liver cancer. Since okadaic acid possesses cytotoxicity and cell proliferative activity by virtue of its known phosphatase inhibition activity.