Mercuric chloride-induced oxidative stress, genotoxicity, haematological changes and histopathological alterations in fish Channa punctatus (Bloch, 1793).

The present study was undertaken to investigate the adverse effects of mercuric chloride (HgCl2 ) overload in the fish Channa punctatus. Two sublethal test concentrations of HgCl2 (1/20th and 1/10th of 96 h LC50 i.e., 0.03 mg l-1 (low concentration) and 0.07 mg l-1 (high concentration), respectively, were used for exposure. Blood, liver and kidney tissues of the control and exposed specimens were sampled at intervals of 15, 30, and 45 days to assess alterations in oxidative stress, genotoxicity haematological parameters and histopathology. Significant changes in Hb%, RBC count, WBC count, antioxidant enzyme activity, i.e., superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and glutathione reductase (GR), were recorded. Micronuclei (MN) induction, nuclear abnormalities (NAs) and histopathological alterations were also observed in the exposed fish. Significant (P < 0.05) increase in the activities of SOD, CAT, GSH and GR was observed. After 45 days, a decrease in the level of GSH and GR was noticed which suggests an undermined anti-oxidative defence system in the fish exposed to HgCl2 . Histological examination of the liver and kidney showed serious tissue injury and histological alterations. Significant increases in MN and NA frequencies reveal the DNA damage in erythrocytes of fish, and haematological changes show the toxicological potential of HgCl2 . The observed changes in the antioxidant defence system, genotoxicity and haematological and histological changes in the present study provide the most extensive insight into HgCl2 stress in C. punctatus.

Dietary inclusion of Withania somnifera and Asparagus racemosus induces growth, activities of digestive enzymes, and transcriptional modulation of MyoD, MyoG, Myf5, and MRF4 genes in fish, Channa punctatus.

The present study explores growth potential of two medicinal herbs, Withania somnifera (Ashwagandha or 'A') and Asparagus racemosus (Shatavari or 'S') after their dietary inclusion in fish, Channa punctatus (13.5 ± 2 g; 11.5 ± 1 cm). Three hundred well-acclimatized fish were distributed into 10 groups- C (Control), S1 (1% S), S2 (2% S), S3 (3% S), A1 (1% A), A2 (2% A), A3 (3% A), AS1 (1% A and S), AS2 (2% A and S), and AS3 (3% A and S), each having 10 specimens. Fish were fed with these diets for 60 days. The study was performed in triplicate. Growth indices- weight gain (WG), specific growth rate percentage (SGR%), feed intake (FI), and condition factor (CF), after 30 and 60 days, were found significantly (p < 0.05) up-regulated in all the groups, except S1, when compared to the C. A significant (p < 0.05) increase in final body weight (FBW) was noticed in all the groups, except S1, after 60 days. Relative to the control group, activities of lipase and amylase in the gut tissue were elevated in all groups, at both sampling times, with the exception of lipase in S1 at 60 days, and amylase in S1 at day 30 and day 60 and S2 at day 60. The mRNA expression of myogenic regulatory factors (MRFs) was also found to be significantly (p < 0.05) up-regulated with the highest fold changes recorded in AS3 for myoD (3.93 ± 0.91); myoG (6.71 ± 0.30); myf5 (4.40 ± 0.33); MRF4 (4.94 ± 0.21) in comparison to the C.

Oxidative stress, inflammation, and steatosis elucidate the complex dynamics of HgCl2 induced liver damage in Channa punctata.

Water bodies are highly pollution-prone areas in which mercury (Hg) is considered as a major menace to aquatic organisms. However, the information about the toxicity of mercuric chloride (HgCl2) in a vital organ such as the liver of fish is still inadequate. This study aimed to assess the impact of mercuric chloride (HgCl2) exposure on the liver of Channa punctata fish over 15, 30, and 45 days, at two different concentrations (0.039 mg/L and 0.078 mg/L). Mercury is known to be a significant threat to aquatic life, and yet, information regarding its effects on fish liver remains limited. The results of this study demonstrate that exposure to HgCl2 significantly increases oxidative stress markers, such as lipid peroxidation (LPO) and protein carbonyls (PC), as well as the levels of serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) in the fish. Additionally, the transcriptional and protein analysis of specific genes and molecules associated with necroptosis and inflammation, such as ABCG2, TNF α, Caspase 3, RIPK 3, IL-1ß, Caspase-1, IL-18, and RIPK1, confirm the occurrence of necroptosis and inflammation in the liver. Histopathological and ultrastructural examinations of the liver tissue further reveal a significant presence of liver steatosis. Interestingly, the upregulation of PPARα suggests that the fish's body is actively responding to counteract the effects of liver steatosis. This study provides a comprehensive analysis of oxidative stress, biochemical changes, gene expression, protein profiles, and histological findings in the liver tissue of fish exposed to mercury pollution in freshwater environments.

Copper-induced Genotoxicity, Oxidative Stress, and Alteration in Transcriptional Level of Autophagy-associated Genes in Snakehead Fish Channa punctatus.

Copper (Cu) is an essential and important trace element for some significant life processes for most organisms. However, an excessive amount of Cu can be highly toxic. The present study was conducted to elucidate the oxidative stress-induced alteration in transcriptional level of autophagy-related genes in the liver and kidney tissue of fish Channa punctatus after treatment with three different sublethal concentrations of CuSO4 for 28 days. All the studied enzymatic and non-enzymatic oxidative stress markers viz. superoxide dismutase-SOD, catalase-CAT, glutathione peroxidase-GPx, glutathione reductase-GR, and glutathione-GSH showed an increase in their activity levels in the treated groups in a dose-dependent manner. Particularly SOD and CAT have shown a significant hike in activity levels. ROS levels in blood cells increased significantly (p < 0.05) in all the treated groups, i.e., Group II-1/20th of 96 h-LC50 (0.2 mg/L), Group III-1/10th of 96 h-LC50 (0.4 mg/L), and Group IV-1/5 h of 96 h-LC50 (0.8 mg/L) of Cu2+ in a dose-dependent manner as compared to control (Group I). The upregulation in mRNA levels of autophagy-related genes Microtubule-associated protein 1 light chain 3 (LC3), Gamma-aminobutyric acid receptor-associated protein precursor (Gabarap), and Golgi-associated ATPase enhancer of 16 kDa (GATE16), autophagy-related 5 (ATG5) was observed while mammalian target of rapamycin (mTOR) showed downregulation in the liver and kidney tissue of fish. The decrease in mTOR and increase in ATG5 gene expression projects autophagic vesicle formation due to oxidative stress. There was significant induction in micronuclei (MN) frequency in all the treated groups. The highest frequency of MN induced by Cu2+ was recorded in Group IV after 28 days of the exposure period. Thus, it can be concluded that the available information about Cu2+-induced oxidative stress-mediated autophagy in the liver and kidney of fish C. punctatus remains largely unclear to date, so to fill the aforesaid gap, the present study was undertaken, which gives an insight for the mechanisms of autophagy induced by Cu2+ in fish.

In vivo assessment of dichlorvos induced histological and biochemical impairments coupled with expression of p53 responsive apoptotic genes in the liver and kidney of fish, Channa punctatus (Bloch, 1793).

Sub-lethal exposure of dichlorvos induces oxidative stress, consequent genetic instability and apoptosis coupled with impairments in biochemical, histopathological and transcription of genes in Channa punctatus. Exposure of 5% (0.041 mg/L; E2) and 10% (0.082 mg/L; E3) of 96 h-LC50 of dichlorvos significantly (p < 0.05) elevated the reactive oxygen species (ROS) generation and activities of SOD and CAT, as compared to control (E1) after 30 d. The maximum reduction in reduced glutathione (GSH) was recorded in the liver (18.53 ± 0.81 µg/mg of protein) and kidney (19.32 ± 0.97 µg/mg of protein); while the total protein contents were also found reduced, 278.38 ± 8.40 µg/mL (liver) and 248.44 ± 7.28 µg/mL (kidney), after 30 days in E3, in comparison to respective controls. Further, significant (p < 0.05) induction in micronuclei (MN) and apoptotic cells (AC), in a dose- and exposure-based manner were also recorded. Moreover, a significant (p < 0.05) up-regulation of p53 (2.51-fold in liver), bax (2.03-fold in liver; 1.99-fold in kidney) and casp3a (2.26-fold in liver; 2.10-fold in kidney) together with an elevated expression of cat (1.73-fold in liver; 1.12-fold in kidney), p53 (1.27-fold in kidney) and apaf-1 (1.72-fold in liver) in fish exposed to higher dose of dichlorvos for 30 d evidently reflects geno-toxicological potential of referenced pesticide. Disturbed biochemical and molecular parameters evince that the fish experienced oxidative stress as is further supported by prominent pathological observations in liver and kidney. Findings are, thus, helpful in organ-specific molecular scanning against aquatic toxicants like dichlorvos.

Biomonitoring of Heavy Metals in River Ganga Water, Sediments, Plant, and Fishes of Different Trophic Levels.

In this study, the pattern of metals concentration in water, sediment, plants, and three edible fish species (Channa striata, Labeo rohita, and Catla catla) of different trophic levels, captured from Jajmau (Kanpur), an important fishery area of river Ganga in Uttar Pradesh, India was examined. The heavy metals, Ni, Pb, Fe, Cu, Zn, Cd, Cr, and Co, were estimated in the liver, kidney, muscles, and gill tissues of abovesaid species of fish. The highest metal concentration was reported in the bottom feeder fish as compared with the column and surface feeders. The result obtained after analysis of water sample reflects the order of occurrence of heavy metals as Fe > Cr > Pb > Ni > Cd > Zn > Cu > Co. Sediments analysis indicates high concentration of Fe and Cr, making the entire environment from top to bottom, stressful. Target hazard quotient (THQ) and hazard index (HI) of the three species suggest a potential risk to the health of consumers, the humans. Thus, it is inevitable that the river Ganga should be closely monitored to safeguard human health. Graphical Abstract.

A protective study of curcumin associated with Cr6+ induced oxidative stress, genetic damage, transcription of genes related to apoptosis and histopathology of fish, Channa punctatus (Bloch, 1793).

Ameliorative potential of curcumin against Cr6+-induced eco-toxicological manifestations was assessed in liver of exposed Channa punctatus (Actinopterygii) in six groups for 45 d; Group I as control. Group II with 3 mg/L of curcumin; group III with 7.89 mg/L of Cr6+. Groups IV, V and VI were simultaneously co-exposed with 7.89 mg/L of Cr6+ and three different curcumin concentrations, 1, 2, and 3 mg/L, respectively. In group III, SOD-CAT, GR significantly (p < 0.05) increased; decreased GSH level; elevated MN and AC frequencies; and a significant (p < 0.05) up-regulation of cat (2.72-fold), p53 (1.73-fold), bax (1.33-fold) and apaf-1 (2.13-fold) together with a significant (p < 0.05) down-regulation of bcl-2 (0.51-fold). Co-exposure significantly (p < 0.05) brought down activities of SOD-CAT, GR, raised GSH, decreased micronuclei and apoptotic frequencies along with recovery of histopathological anomalies in liver. This study establishes the protective role of curcumin against Cr6+-induced hepatotoxicity in fish.