Hepatopancreas toxicity and immunotoxicity of a fungicide, pyraclostrobin, on common carp.

Pyraclostrobin (PYR), a strobilurin fungicide, has been widely used to control fungal diseases, posing potential risk to aquatic organisms. However, the toxic effects of PYR to fish remained largely unknown. In this study, common carp (Cyprinus carpio L.) was exposed to environmentally relevant levels of PYR (0, 0.5 and 5.0 µg/L) for 30 days to assess its chronic toxicity and potential toxicity mechanism. The results showed that long-term exposure to PYR induced hepatopancreas damage as evident by increased in serum transaminase activities (AST and ALT). Moreover, PYR exposure remarkably enhanced the expressions of hsp70 and hsp90, decreased the levels of antioxidant enzymes and biomarkers and promoted the reactive oxygen species (H2O2 and O2-) and MDA contents in carp hepatopancreas. PYR exposure also upregulated apoptosis-related genes (bax, apaf-1, caspase-3 and caspase-9) and reduced anti-apoptosis gene bcl-2 in fish hepatopancreas. Moreover, PYR exposure altered the expressions of inflammatory cytokines (IL-1ß, IL-6, TNF-α and TGF-ß) in the serum and hepatopancreas and the level of NF-κB p65 in the hepatopancreas. Further research indicated that PYR exposure markedly changed the levels of immune parameters (LYZ, C3, IgM, ACP and AKP) in the serum and/or hepatopancreas, indicating that chronic PYR exposure also has immunotoxicity on fish. Additionally, we found that PYR exposure upregulated p38 and jnk MAPK transcription levels, suggesting that MAPK may be play important role in PYR-induced apoptosis and inflammatory response in the hepatopancreas of common carp. In summary, PYR exposure induced oxidative stress, triggered apoptosis, inflammatory and immune response in common carp, which can help to elucidate the possible toxicity mechanism of PYR in fish.

Biochemical and molecular impacts of glyphosate-based herbicide on the gills of common carp.

Glyphosate (GLY)-based herbicide, one of the most widely used herbicides, might cause a series of environmental problems and pose a toxicological risk to aquatic organisms. However, data on the potential hazard and toxicity mechanism of GLY to fish gills are relatively scarce. In this study, a subacute toxicity test of common carp (Cyprinus carpio L.) treated with commercial GLY at 52.08 and 104.15 mg L-1 for 7 d was conducted. The results revealed that GLY exposure significantly inhibited Na+/K+-ATPase and increased AST and ALT activities in the fish gills. The biochemical assays results revealed that GLY treatment remarkably altered the transcriptional levels of HSP70 and HSP90; inhibited the activities of SOD, CAT, GPx, GR, and T-AOC; reduced the contents of GSH, but remarkably promoted MDA and PC contents, suggesting that GLY exposure induced oxidative stress and lipids and proteins damage in the carp gills. Further research revealed that GLY exposure also promoted expression of NF-κB, iNOS, IL-1ß, IL-6, IL-8, and TNF-α; altered the levels of IL-10 and TGF-ß, indicating that GLY exposure induced inflammatory response in the fish gills. Additionally, we found that GLY exposure activated apaf-1 and bax and inhibited bcl-2, induced caspase-9 and caspase-3 expression and caused remarkable histological damage in the fish gills. These results may further enriches the toxicity mechanistic theory of GLY to fish gills, which may be useful for the risk assessment of GLY and aquatic organism protection.

Bioaccumulation of heavy metals in fish species from the Meiliang Bay, Taihu Lake, China.

In the present study, the bioaccumulation of heavy metals (Cr, Cu, Cd, Pb) content were determined in freshwater edible fishes Cyprinus carpio Linnaeus and Pelteobagrus fluvidraco, which were caught from the Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that the Cr, Cu, Cd and Pb content in the edible parts of the two fish species were much lower than Chinese Food Health Criterion (1994). However, the results showed marked differences in the four analyzed metal content between the two species and different tissues as well as significant variations. Pb content were the highest in the liver of fishes, Cd contents were almost the same in all organs of fishes, Cr contents mainly enriched in the kidney and liver, Cu contents were the highest in gills, However, the total metal bioaccumulation were greatest in the liver, gills and the lowest in the muscle. Although the total accumulations were highest in P. fluvidraco compare then C.carpio. This investigation indicated that fish products in Meiliang Bay, Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Pb. Further, this is the first report on seasonal distribution of heavy metals and proximate compositions of commercialized important edible fishes from Meiliang Bay, Taihu Lake, China.

Studies on seasonal pollution of heavy metals in water, sediment, fish and oyster from the Meiliang Bay of Taihu Lake in China.

The present study, seasonal pollution of heavy metals (Pb, Cd, Cr and Cu) in water, sediment, tissues of fish Carassius carassius and oyster Crassostrea gigas were determined at seven sampling sites from Meiliang Bay, Taihu Lake during one year calendar, 2016. The total heavy metal concentrations in water samples were higher in winter and summer than in spring and autumn season, whereas in sediment they were higher in winter and summer seasons, respectively. The trend of metal mean contents found in the fish and oyster were in decreasing order of Pb > Cu > Cr > Cd and Pb > Cu > Cr > Cd, respectively. The tissues of fish and oyster captured during winter and summer accumulated a higher significant different amount of metals relative to other season, which was attributed to a higher influx of agricultural waste, sewage and sludge by heavy rainfall and floods. In addition, the pollution load index (PLI) values were above one (>1), indicating an advanced decline of the sediment quality, and contamination factor (CF) confirmed that the sediment samples were moderate to high contamination by Pb and Cr. Thus, comparative studies with seasonal pollution of heavy metals in Meiliang Bay of Lake Taihu regions indicate considerable heavy metal enrichment in water, sediments as well as in various organs of fish and oyster. Finally, our results indicated that the metal concentration values increased statistically significant different related to season (p < 0.001). The determination of heavy metal stress biomarkers in fish along with seasonal variations may serve as a convenient approach during pollution bio-monitoring programme.

Effects of exposure to multiple heavy metals on biochemical and histopathological alterations in common carp, Cyprinus carpio L.

Heavy metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of exposure to mixtures of essential and toxic metals (Cr, Cd and Pb) on biochemical, immunotoxicity level and morphological characteristics of the various tissues of a biomarker freshwater fish common carp using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days, under controlled laboratory conditions. Tissue accumulation of the metals was measured using Atomic Absorption Spectrophotometric techniques. Chromium, cadmium and lead accumulation in muscle, gills, liver, kidney and intestine, tissue of common carp exposed to mixture metals for 30 days increased significant compared with control group (p < 0.001). However, the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) levels was significant altered in various tissues of exposed fish. Besides, the lipid peroxidation (LPO) was significant (p < 0.001) increased. Moreover, the tumor necrosis factor - α (TNF-α), interleukin (IL-6), and interferon-γ (IFN-γ) contents in tissues of muscle, gills, liver, kidney and intestine were increased significant compared with control fish (p < 0.001). In addition, microscopic examination of the main alterations in general morphology of fish gills included spiking and fusion of secondary lamellae, formation of club-shaped filaments epithelium in the interlamellar regions and hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish exposed to metal mixture for a longer duration (30 days). These results of this study clearly demonstrate that concentration individual and mixtures of metals in aquatic systems will greatly influence the cytokine alterations may result in an immune suppression or excessive activation in the treated common carp as well as may cause immune dysfunction or reduced immunity. In conclusion, toxicity of multiple metal mixtures of Cr, Cd and Pb has antioxidant and immunotoxic effects on C. carpio.

Effects of heavy metals on antioxidants and expression of HSP70 in different tissues of Milk fish (Chanos chanos) of Kaattuppalli Island, Chennai, India.

Distribution of heavy metals and its associated oxidative stress, ultrastructure and expression of HSP 70 were studied in varies tissues of Chanos chanos collected from polluted sites compared with the fish collected from less polluted sites of Kaattuppalli Island. The concentrations of copper, lead, zinc, cadmium, manganese and iron were quantified in gills and liver. The results showed marked differences between the two sites as well as significant variations within the tissues. The decreasing trend of metals in the tissues of fish sampled from both polluted and less polluted sites was in the order of Fe>Mn>Zn>Cu>Pb>Cd. Overall, the highest metal concentrations were found in the fish collected from polluted sites. Similarly increase of antioxidant enzymes biomarkers due to heavy metals was also evident in gills and liver of the fish collected from polluted sites. These tissues were further investigated by scanning and electron microscopy and the results were compared with the reference less polluted sites. The presence of large lipid droplets in liver and increase of mucous cells in gills were some of the most noticeable alterations observed and were related to heavy metal contaminants. It is concluded that scanning, ultrastructural and useful of HSP70 biomarkers for heavy metal induced oxidative stress, and demonstrate that precautions need to be taken in polluted sites of Kaattuppalli Island in order to prevent heavy metal pollution that can occur in the future.

Impact of metals on histopathology and expression of HSP 70 in different tissues of Milk fish (Chanos chanos) of Kaattuppalli Island, South East Coast, India.

Histological and Immunohistochemical studies were carried out to document the possible impact of heavy metal contamination in different tissues of Chanos chanos. Heavy metals such as Cu, Pb, Zn, Cd, Mn and Fe were predominant in water, sediment and biota of Kaattuppalli Island and varied significantly between two different sites. Histological changes such as swelling of muscle fiber and break down of muscle bundles were noted in the muscle. Similarly gill filament cell proliferation, increase in intercellular spaces and primary and secondary lamellar epithelium were evident in gills. The hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish collected from polluted site compared to that from the less polluted site. The impact of pollution was also assessed in different tissues by immunohistochemistry using primary antibody (mouse monoclonal HSP70 antibody 1:2000) and secondary antibody (HRP conjugated antibody) for expression of stress protein. Immunostaining analysis showed expression of HSP70 with high intensity in the tissues of fish collected from polluted site compared to less polluted sites. Further, HSP70 positive cells were analyzed from six locations per fish tissue section. One-way analysis of variance (ANOVA) followed by least significant difference (LSD) was used to check if the expression was significant. Results indicate that the values are statistically significant at the two different sampling sites (P<0.05).