RESUMEN
Owing to white meat production Labeo rohita have vast economic importance, but its population has been reduced drastically in River Chenab due to pollution. Atomic absorption spectrophotometry showed a merciless toxicity level of Cd, Cu, Mn, Zn, Pb, Cr, Sn and Hg. Comet assay results indicated significant (pâ¯<â¯.05) DNA fragmentation in Labeo rohita as 42.21⯱â¯2.06%, 31.26⯱â¯2.41% and 21.84⯱â¯2.21% DNA in comet tail, tail moment as 17.71⯱â¯1.79, 10.30⯱â¯1.78 and 7.81⯱â¯1.56, olive moment as 13.58⯱â¯1.306, 8.10⯱â¯1.04 and 5.88⯱â¯0.06, respectively, from three different polluted sites on the river. Micronucleus assay showed similar findings of single micronucleus induction (MN) as 50.00⯱â¯6.30, double MN 14.40⯱â¯2.56, while nuclear abnormalities (NA) were found as 150.00⯱â¯2.92. These higher frequencies of MN induction and NA were found to be the cause of reduction of 96% of the population of this fish species in an experimental area of the River Chenab. This fish species has been found near extinction through the length of the river Chenab and few specimens in rainy seasons if restored by flood, may die in sugarcane mill season. Due to sweeping extinction Labeo rohita showed the highest sensitivity for pollution and could be used as bioindicator and DNA fragmentation in this column feeder fish species as a biomarker of the pollution load in freshwater bodies.
RESUMEN
Cirrhinus mrigala, Labeo rohita, and Catla catla are economically important fish for human consumption in Pakistan, but industrial and sewage pollution has drastically reduced their population in the River Chenab. Statistics are an important tool to analyze and interpret comet assay results. The specific aims of the study were to determine the DNA damage in Cirrhinus mrigala, Labeo rohita, and Catla catla due to chemical pollution and to assess the validity of statistical analyses to determine the viability of the comet assay for a possible use with these freshwater fish species as a good indicator of pollution load and habitat degradation. Comet assay results indicated a significant (P < 0.05) degree of DNA fragmentation in Cirrhinus mrigala followed by Labeo rohita and Catla catla in respect to comet head diameter, comet tail length, and % DNA damage. Regression analysis and correlation matrices conducted among the parameters of the comet assay affirmed the precision and the legitimacy of the results. The present study, therefore, strongly recommends that genotoxicological studies conduct appropriate analysis of the various components of comet assays to offer better interpretation of the assay data.
