Multiple biomarker responses (serum biochemistry, oxidative stress, genotoxicity and histopathology) in Channa punctatus exposed to heavy metal loaded waste water

Abstract

Experiments were conducted to investigate the health of fish Channa punctatus inhabiting heavy metal-loaded waste water. Heavy metals in the order of Fe > Mn > Zn > Co > Ni > Cu = Cr were present in the waste water. Gills had high metal load followed by liver and then kidney. Albumin, albumin to globulin (A:G) ratio, triglyceride, high density lipoprotein (HDL) and very low density lipoprotein (VLDL) were found to be lower but phospholipid, low density lipoprotein (LDL), total protein, lipid and cholesterol were higher as compared to the reference. Oxidative stress markers such as superoxide dismutase (SOD), catalase (CAT), glutathione S transferase (GST) and lipid peroxidation (LPO) were significantly higher in all tissues, whereas reduced glutathione (GSH) levels were comparatively low. Damage to DNA was observed with significantly higher mean tail length of comets in the exposed fish gill cells (30.9 µm) followed by liver (24.3 µm) and kidney (20.6 µm) as compared to reference fish (5.2, 4.8 and 5.9 µm respectively). Histopathology in gill, liver and kidney also showed marked damage. Integrated biochemical, oxidative stress, genotoxicity and histopathological findings are valuable biomarkers for native fish adaptive patterns, and monitoring of water quality/pollution of freshwater ecosystems.

Figure 1

Oxidative stress biomarkers in C. punctatus inhabiting in reference and contaminated water. All values are expressed as mean ± SEM, (n = 10); statistically significant at *p < 0.05; **p < 0.01; SOD (superoxide dismutase), CAT (catalase), GST (glutathione S transferase), GSH (reduced glutathione), LPO (lipid peroxidation).

Figure 2

[I]. DNA damage as visualized by comet assay in reference site and panethi reservoir in gill, liver and kidney cells. (a, c and e) are the reference groups and (b, d and f) are the exposed groups of gill, liver and kidney cells of C. punctatus respectively. [II]. Mean tail length (µm) of DNA comets in C. punctatus in gill, liver and kidney tissues collected from reference and exposed samples. All values are given as mean ± SEM, (n = 10); Level of significance established at *p < 0.05

Figure 3

Histopathology of gill of C. punctatus inhabiting in reference and contaminated water. (a) Gill of reference fish; (b, c and d) Gill of exposed fish; PL (primary lamellae), PC (pillar cell), E (erythrocyte), C (cartilage), SL (secondary lamellae), LF (lamellar fusion), GB (gill bridging), EL (epithelial lifting), HP (hyperplasia), N (necrosis), LS (lamellar swelling). Scale bar = 20 µm.

Figure 4

Histopathology of liver of C. punctatus inhabiting in reference and contaminated water. (a) Reference liver; (b, c and d) Liver of exposed fish; S (sinusoid), BV (blood vessel), P (pancreatic tissue), E (erythrocyte), H (hepatocyte), N (necrosis), V (vacuolization), PN (pyknotic nuclei), DP (degeneration of pancreatic tissue), HM (haemorrhage), CBV (congestion of blood vessel), LG (lipid granules). Scale bar = 20 µm.

Figure 5

Histopathology of kidney of C. punctatus inhabiting in reference and contaminated water. (a) Reference kidney; (b, c and d) Kidney of exposed fish; G (glomeruli), BS (bowman's space), RT (renal tubule), H (haemopoietic tissue), IBS (increased bowmans space), DG (damaged glomeruli), DRT (damaged renal tubule), N (necrosis), HRT (hypertrophied renal tubule), V (vacuolation), HP (hyperplasia), CRT (constricted renal tubule), CG (constricted glomeruli), GF (granuloma formation) and PN (pyknotic nuclei). Scale bar = 20 µm.