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The present study aimed at assessing the singular and combined effects of water copper and polyvinyl chloride microplastic (MPVC) on intestinal copper accumulation, histopathological damage, and stress‐/immune‐related genes' expression in common carp, Cyprinus carpio. Four groups of fish were maintained in triplicate: control (kept in clean water), Cu (exposed to 0.25 mg/L of copper), MPVC (exposed to 0.5 mg/L of MPVC), and Cu‐MPVC (exposed to 0.25 mg/L of copper + 0.5 mg/L of MPVC). After 14‐day exposure, the fish of Cu and Cu‐MPVC treatments exhibited significantly higher intestinal copper contents, compared to the fish of control and MPVC treatments. In this regard, the Cu‐MPVC fish had significantly higher copper content than the Cu fish. Exposure to copper and/or MPVC significantly upregulated the intestinal heat shock protein 70 (hsp70), cytochrome P450 family 1 subfamily A member 1 (cyp1a1), lysozyme (lys), defensin (def), mucin 2 (muc2), and mucin 5 (muc5) expression. The highest expression of hsp70, cyp1a1, lys, and def was related to Cu‐MPVC treatment; whereas, the highest expression of muc2 and muc5 was observed in Cu and MPVC treatments. Exposure to copper and/or MPVC induced intestinal damage, which Cu‐MPVC fish exhibited the highest severity. The present study revealed that exposure to copper and/or MPVC causes intestinal histopathological damage and upregulation in stress‐ and immune‐related genes' expression. The most serious effects were observed in Cu‐MPVC treatment that might be due to additive effects of copper and MPVC and/or higher copper accumulation in this treatment.

Malachite green (MG) is a multi-application dye with raised concern as aquatic toxicant. Cyprinus carpio fingerlings were exposed to MG and simultaneously fed with Emblica officinalis (EO) fruit extract to mitigate the MG induced nephrotoxicity. MG exposure developed depressed activity of antioxidant enzymes such as catalase, superoxide dismutase, glutathione-s-transferase, and reduced glutathione, while levels of malondialdehyde got significantly (p < .05) elevated after 60 days MG exposure. H&E staining revealed increased intracellular space, vacuolation, fluid-filled spaces, damaged brush border lining of proximal convoluted tubule (PCT), focal necrosis, nuclear transformations and shrunken glomerulus. Further, Transmission electron microscope study detailed structural cytotoxicity with the appearance of the heterochromatic nucleus, electron-dense lysosomal bodies, damaged brush border lining of PCT, and necrosis; glomerulus exhibited erythrocyte infiltration and fused pedicels of podocyte. While, EO extract supplemented diet culminated in the restoration of the renal cytoarchitecture and significantly (p < .05) enhanced activity of antioxidant enzymes.

No abstract

Malachite green (MG) dye, besides coloring is used as an effective aquaculture therapeutic. The present study assesses the mitigating ability of Emblica officinalis (EO) fruit extract against the dye induced chronic (60 days) cyto-toxicity in Cyprinus carpio. For this, four experimental groups were maintained: group I—control, group II—MG, group III—EO (positive control), group IV—MG + EO. The study was made at three tiers: detailing structural anomalies using a light microscope and transmission electron microscope (TEM), biochemical estimation of antioxidant enzymes, and lipid peroxidation and molecular analysis of expression patterns of HSP70, and CYP1A genes. MG intoxication resulted in necrosis, cytoplasmic vacuolation, glycogen depletion, abundant macrophages, loss of cell integrity and prominent nuclear alterations. Significant (p < 0.05) inhibition in the activities of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST) and reduced glutathione (GSH), along with an elevation in malondialdehyde (MDA) levels, occurred after 60 days of MG exposure. CYP1A and HSP70 genes presented a significant change in their expression in MG treated fish. Whereas oral supplementation with EO significantly restored the histo-architecture, normalized the altered enzymatic activity, reduced the oxidative stress level and downregulated the expression of HSP70 and CYP1A genes. Thus, it can be concluded that EO acted as an effective ameliorant against malachite green induced cyto-toxicity in Cyprinus carpio.

No abstract

Blood is a sensitive bioindicator of stress observed by organisms in response to toxicants. Erythrocytic morphological abnormalities serve as a reliable determinant of fish health. Malachite green, a multifunctional dye was assessed for toxicity in Cyprinus carpio. Dye‐induced blood toxicity has been determined through biochemical and ultra structural endpoints at 15, 30 and 60 days in the fish. Further, an attempt has been made to combat the adverse effects of the toxicant through supplementation with Emblica officinalis. Electron microscopic study depicted erythrocytic remodelling in form of surface blebbing, lobopodial projections and shrinkage; appearance of crenate, acanthocytes, echinocytes, dacrocytes, spherocytes and rhomboidal cells. Hepatic marker enzymes showed significantly (p < 0.05) elevated levels of biomarker enzymes, alkaline phosphatase, serum glutamate oxaloacetate transaminase and serum glutamate pyruvate transaminase. Contrarily feeding with E. officinalis extract (1,000 mg/kg feed) significantly attenuated biochemical and morphological alterations, indicating the protective efficacy of E. officinalis. Both toxicity and attenuation observed were in exposure‐dependent manner.

Electron microscope (EM) was developed in 1931 and since then microscopical examination of both the biological and non‐biological samples has been revolutionized. Modifications in electron microscopy techniques, such as scanning EM and transmission EM, have widened their applicability in the various sectors such as understanding of drug toxicity, development of mechanism, criminal site investigation, and characterization of the nano‐molecule. The present review summarizes its role in important aspects such as toxicity assessment and disease diagnosis in special reference to SARS‐COV2. In the biological system, EM studies have elucidated the impact of toxicants at the ultra‐structural level in various tissue in conformity to physiological alterations. Thus, EM can be concluded as an important tool in toxicity assessment and disease prognosis.