cyanoginosin-lr and Fish-Diseases

Microcystin-LR (MC-LR) is a potent hepatotoxin for which a substantial gap in knowledge persists regarding the underlying molecular mechanisms of liver toxicity and injury. Although long non-coding RNAs (lncRNAs) have been extensively studied in model organisms, our knowledge concerning the role of lncRNAs in liver injury is limited. Given that lncRNAs show low levels of sequence conservation, their role becomes even more unclear in non-model organisms without an annotated genome, like whitefish (

Topics: Animals; Chemical and Drug Induced Liver Injury, Chronic; Fish Diseases; Liver; Marine Toxins; Microcystins; MicroRNAs; Molecular Sequence Annotation; RNA, Long Noncoding; RNA, Messenger; Salmonidae; Sequence Analysis, RNA; Transcriptome

Caspase-8, an initiator caspase, plays a vital role in apoptosis. In this study, caspase-8-like (named as Cicaspase-8-like), a homologue of caspase-8, was identified in grass carp (Ctenopharygodon idella). The full-length cDNA sequence of CiCaspase-8-like was 1409 bp and contained a 162 bp 5'-UTR, a 239 bp 3'-UTR and a 1008 bp coding sequence. The putative amino acids sequence was 335 residues long, including a large subunit (P20) and a small subunit (P10), but lacking conserved death effector domains. A histidine active site DHSQMDAFVCCVLSHG and a cysteine active-site motif KPKLFFIQACQG were found in P20. Phylogenetic analysis showed that Cicaspase-8-like clustered with the caspase-8 and caspase-8-like of other fish and grouped closely with Carassius auratus caspase-8-like. Quantitative real-time PCR revealed that the Cicaspase-8-like mRNA were expressed constitutively in all tested tissues from healthy grass carp, with high expression level in the blood, spleen, liver and gill, indicating its role in immune reaction. The expression of Cicaspase-8-like mRNA was decreased significantly in the liver because of the stress caused by microcystin-LR (MC-LR) (75 and 100 μg MC-LR/kg BW) at 24 h and 96 h post injection (P < 0.05), but it was increased significantly in grass carp treated with 25 μg MC-LR/kg BW at 24 h (P < 0.05) post injection. Cleaved fragments of Cicaspase-8-like were observed using western blot analysis, and the expression of Cicaspase-8-like protein was increased after MC-LR treatments. Moreover, the expression of both caspase-9 and caspase-3 mRNA increased significantly after treatment with the three doses of MC-LR. TUNEL assay results showed remarkable changes in apoptosis after the MC-LR treatment. These results suggest that Cicaspase-8-like is an important caspase and plays an essential role in MC-LR-induced apoptosis.

Topics: Amino Acid Sequence; Animals; Carps; Caspase 8; Fish Diseases; Fish Proteins; Gene Expression Profiling; Gene Expression Regulation; Immunity, Innate; Marine Toxins; Microcystins; Phylogeny; Sequence Alignment

Cyanobacterial blooms exert negative impacts on fisheries and water management authorities. Recently, it has gained global attention, as elevated earth warming and environmental pollution are accelerating algal growth. Oreochromis niloticus (O. niloticus) is a worldwide and the most commonly cultured fish in Egypt. The biological interaction of the living organisms to the surrounding environment must continuously be assessed to predict future effects of the ongoing hazards on fish. The study was designed to examine the possible biological and biochemical response of O. niloticus exposed to different concentrations of microcystins crude extract (containing microcystin-LR). Three equal groups of O. niloticus were assigned for intraperitoneal injection of three different doses: 100, 200, and 400 μg m(-1) dried aqueous microcystins extract, for 10 days. Clinical, condition factor (K) and hepatosomatic index (HIS) were estimated. Biochemical alterations were evaluated via lipid peroxidation, DNA fragmentation assay and electrophoretic analysis of fragmented DNA using agarose gel electrophoresis. The results showed that there were discernible behavioral and clinical alterations. Significant differences in K and HIS were observed between treatments. Also, significant elevations were observed in lipid peroxidation level and in the DNA fragmentation percentage in the exposed fish to the doses of 200 and 400 μg m(-1) of microcystins crude extract. The current study addresses the possible toxic effects of microcystins crude extract to O. niloticus. The results cleared that microcystins crude extract (containing MC-LR) is toxic to O. niloticus in time- and dose-dependent manners.

Topics: Animals; Chemical and Drug Induced Liver Injury; Cichlids; DNA Fragmentation; Dose-Response Relationship, Drug; Egypt; Fish Diseases; Lipid Peroxidation; Marine Toxins; Microcystins; Microcystis; Oxidative Stress; Water Pollutants, Chemical

Fish suffer from anemia and hypovolemic hypotensive shock after in vivo exposure with microcystins.However, except for in vivo causes for anemia and hypotension, an in vitro study of fish erythrocytes exposed to MC is necessary. For a better understanding of hematology toxicity of MC, the main aim of the present study was to investigate the toxic effects of microcystin on fish erythrocytes in vitro. Crucian carp erythrocytes were incubated in vitro with microcystin-LR (MC-LR) at doses of 0, 1, 10, 100 and 1,000 nM.The level of lipid peroxidate significantly increased in MC-LR treatment groups. Glutathione decreased after exposure to MC-LR. The activities of antioxidative enzymes, including superoxide dismutase, catalase,glutathione peroxidase and glutathione-S-transferase,were significantly increased after exposure with MC-LR.The hemolysis was significantly increased, while the activities of acetylcholinesterase, Na?–K?-ATPase and Ca2?–Mg2?-ATPase were significantly decreased. In addition, pathological alterations in agglomerated and jagged erythrocytes were observed in blood smears. The findings indicate that damages to erythrocytes should also be responsible for anemia and hypotensive shock or even death.

Topics: Anemia; Animals; Antioxidants; Catalase; Erythrocytes; Fish Diseases; Fish Proteins; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Goldfish; Hemolysis; In Vitro Techniques; Lipid Peroxidation; Marine Toxins; Microcystins; Shock

Planktothrix rubescens belongs to the most ubiquitous cyanobacterial species in mesotrophic and oligotrophic lakes in the pre-alpine regions. In most of these lakes, coregonids are among the dominant species of the ichthyofauna with great importance for the professional fishery. A possible link between the occurrence of toxic Planktothrix blooms and the recurrent slumps in coregonid yields has been suggested. Indeed, acute toxic effects of microcystins and other cyanobacterial toxins have been shown for various fish species. However, chronic exposure scenarios appear to be more common and thus more environmentally realistic than acute intoxications. The aim of this study was therefore to investigate the physiological stress response and organ pathology in coregonids sub-chronically exposed to ambient water containing low, medium and high P. rubescens densities, known to be typical of pre-alpine lakes. Coregonid hatchlings were exposed in four tanks containing 0 (sham-control) and approximately 1500 (low), 15,000 (medium) and 55,000 (high) P. rubescens cells/ml for up to 28 days. Temperature, oxygen concentration, pH-value, P. rubescens cell density and microcystin concentration were recorded and the fish were observed for behavioural changes and examined for parasite infestations. Gill ventilation rates, general condition factors and mortalities were determined and liver, kidney, gut and gill were assessed histopathologically and immunhistologically. Depending on the cell density, exposed fish showed behavioural changes, including increased ventilation rates possibly representing a physiological stress response. Susceptibility to ectoparasitic infestation and increased mortality in exposed fish suggested P. rubescens associated effects on fish fitness. Histopathological alterations in liver, gastrointestinal tract and kidney, which were also immunopositive for microcystin suggested causality of tissue damage and the presence of microcystins. In contrast, observed gill pathology appeared to result primarily from mechanical abrasion and irritation due to ectoparasitic infestation. The current exposure experiment confirmed the hypothesis that subchronic and chronic exposure to low cyanobacterial cell densities and hence microcystins can exacerbate physiological stress and sustained pathological alterations in exposed coregonids. The study therefore supports the theory that P. rubescens blooms may be causal to the observed weight reduction and hence fitness o

Topics: Animals; Blood Glucose; Cyanobacteria; Fish Diseases; Fresh Water; Gastrointestinal Tract; Gills; Immunohistochemistry; Kidney; Liver; Marine Toxins; Microcystins; Random Allocation; Respiration; Salmonidae

Microcystins (MCs) have been reported to induce oxidative stress in aquatic organisms including fish. The effect of acute exposure to toxic cyanobacterial material containing MCs on antioxidant enzymes and lipid peroxidation has been studied in liver, kidney and gills of tilapia fish (Oreochromis niloticus). Fish were orally exposed to a single dose of cyanobacterial cells containing 120 microg/fish MC-LR and sacrificed at 24 and 72 h. The activities of glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) enzymes in the studied organs decreased in general 24 and 72 h after the dose application, although elevation of CAT and GR was found in liver at 72 h post exposure in comparison to 24h values. In contrast, the lipid peroxidation level increased significantly in all the studied organs with the liver (3.6-fold) proving to be the most affected. Protein oxidation was also increased 1.5-fold in the liver. However, recovery in these parameters was observed in liver 72 h after exposure. The results show that an acute dose of MCs does not induce an adaptative response of the antioxidant enzymes, as a sub-chronic exposure to MCs in tilapia fish does, but a general decrease in them with an initial recovery of the oxidative damage after 72 h, expressed as enhancement of CAT and GR activities and a reduction of LPO and protein oxidation in comparison to 24h values.

Topics: Animals; Catalase; Cichlids; Cyanobacteria; Fish Diseases; Gills; Glutathione Peroxidase; Glutathione Reductase; Kidney; Liver; Male; Marine Toxins; Microcystins; Oxidative Stress; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances

Evidence is presented that links microcystins to a severe liver disease that occurs in Atlantic salmon that are netpen-reared in coastal British Columbia. Liquid chromatography-linked protein phosphatase bioassay analysis of extracts of liver tissue taken from Atlantic salmon afflicted with netpen liver disease showed the presence of an inhibitor of protein phosphatase that was chromatographically indistinguishable from microcystin-LR. Analysis of liver tissue from healthy control fish showed a complete absence of microcystin-LR. Intraperitoneal injection of microcystin-LR into healthy Atlantic salmon re-created the pathologic changes of netpen liver disease, including diffuse necrosis and hepatic megalocytosis.

Topics: Animals; Aquaculture; Chromatography, Liquid; Fish Diseases; Liver Diseases; Marine Toxins; Microcystins; Peptides, Cyclic; Phosphoprotein Phosphatases; Salmon