Assessment of Cytotoxicity in Flesh, Gills and Liver of Fish (Labeo rohita) Reared in Untreated and Treated Sewage Water
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Date
2019
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Punjab Agricultural University, Ludhiana
Abstract
The unregulated discharge of municipal sewage water in the water bodies acts as a major threat to the
aquatic ecosystem and is also known to induce detrimental effects to the inhabiting fauna. The present study
was designed to examine the cytotoxicity in fingerlings of Labeo rohita after exposure to untreated and
treated sewage water for different intervals. The acute toxicity test was conducted for 96 hr to determine
LC50 of the untreated sewage water (UT) using five concentrations viz. 10%, 25%, 50%, 75% and 100%.
The results of acute toxicity test depicted that 75% and 100% concentration of UT induced 100% mortality
in fingerlings in less than 48 hr and 24 hr, respectively. After determining 96 hr LC50 value of UT,
fingerlings were divided into four groups: control, treated, 1/10th of LC50 UT and 1/20th of LC50 UT. The
fingerlings were exposed and dissected at the interval of 15, 30, 45 and 60 days and additional 60 days for
recovery. The results of chronic toxicity test revealed significant decrease (p<0.05) in morphometric
parameters viz. body weight, body length, weight of liver, gills and flesh of 1/10th LC50 UT and 1/20th LC50
UT groups in comparison to control and treated groups. Significant histopathological alterations were also
observed in the gills and flesh of 1/10th and 1/20th LC50 UT group. The biochemical studies depicted a
significant decrease (p<0.05) in the level of total proteins in flesh and liver; the total lipids in flesh, however,
depicted significant increase (p<0.05) in 1/10th LC50 UT and 1/20th LC50 UT groups. The analysis of fatty
acid composition of flesh of fingerlings revealed significant decrease (p<0.05) in per cent of polyunsaturated
fatty acids (PUFA’s) and monounsaturated fatty acids (MUFA’s), however, saturated fatty acids (SFA’s)
indicated significant increase (p<0.05) in 1/10th LC50 UT and 1/20th LC50 UT groups. The evaluation of
antioxidant profile of liver revealed a significant increase (p<0.05) in the levels of LPO and specific activity
of catalase, GST and GR, however, the specific activity of SOD and GPx decreased significantly (p<0.05) in
both 1/10th LC50 UT and 1/20th LC50 UT groups. High frequency of micronucleated cells (MN) was observed
in gill cells of 1/10th LC50 UT and 1/20th LC50 UT group. DNA damage was also observed in gills and flesh
of 1/10th and 1/20th LC50 UT groups. A significant recovery (p<0.05) was observed in weight of liver and
muscles, histo-architecture of gills and flesh, biochemical parameters viz. proteins in flesh, total lipids in
flesh, PUFA’s, SFA’s, MUFA’s, oxidative stress parameters viz. LPO, SOD, catalase, GPx, GR, GST ,
frequency and number of micronucleated cells (MN) in gills cells of 1/10th LC50 UT and 1/20th LC50 UT
groups. Hence, the results of the present study implied that untreated sewage water at the level of 1/10th and
1/20th LC50 has a potential to bring alterations at cellular, organ and genetic level, and after treatment the
water is safe for use in fish culture.
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