Bilal Hussain

Variation in genotoxic susceptibility and biomarker responses in Cirrhinus mrigala and Catla catla from different ecological niches of the Chenab River

A large number of methods have been applied to evaluate genotoxic damage in different aquatic species. Comet assay, as a method for detecting DNA alterations, and micronucleus test, as an index of chromosomal damage are the most widely used and authentic methods in laboratory and field studies. The primary objective of the study was to evaluate the genotoxic effects of heavy metals generated by toxic industrial effluents and various kinds of pollutants from urban and agricultural areas and domestic waste on Catla catla and Cirrhinus mrigala due to water pollution in the Chenab River, Pakistan. The heavy metals Cd, Cu, Mn. Zn, Pb, Cr, Sn, and Hg were detected by atomic absorption spectrophotometry from water samples collected from predetermined sampling sites. All the physicochemical parameters and heavy metals were found to exceed the upper limits recommended by various agencies. Comet assays showed significant (p < 0.05) DNA damage in C. mrigala compared to C. catla for tail length and olive tail moment from three different sites. Significant (p < 0.05) differences were reported between fish collected from polluted sites and farmed fish, but only non-significant (p > 0.05) findings were observed between fish collected from farmed and non-polluted upstream waters. Micronucleus assays showed similar findings for single and double micronucleus induction in C. catla and C. mrigala. A significantly (p < 0.05) higher micronuclei induction and percent tail DNA was observed in C. mrigala specimen collected from the polluted site. These findings infer that DNA damage could be used as a biomarker of pollution load and its early monitoring by using simple and reliable techniques such as the comet and micronucleus assays, expedient methods for toxicity screening of aquatic environments. Regular monitoring is necessary to assess eco-health of the Chenab River by choosing perhaps C. mrigala, being a bottom feeder, as a bioindicator that could provide more reliable information to determine the status of the environmental quality of the river.

Effect of pollution on DNA damage and essential fatty acid profile in Cirrhinus mrigala from River Chenab

The objective of this study was to evaluate the effect of anthropogenic pollution on DNA damage and the fatty acid profile of the bottom dweller fish (Cirrhinus mrigala), collected from the River Chenab, in order to assess the effect of the toxicants on the quality of the fish meat. The levels of Cd, Hg, Cu, Mn, Zn, Pb, Cr and Sn and of phenols from this river were significantly higher than the permissible limits set by the USEPA. Comet assays showed DNA damage in Cirrhinus mrigala collected from three different sampling sites in the polluted area of the river. Significant differences were observed for DNA damage through comet assay in fish collected from polluted compared to control sites. No significant differences were observed for DNA damage between farmed and fish collected from upstream. The micronucleus assay showed similar trends. Fish from the highly polluted sites showed less number of fatty acids and more saturated fatty acids in their meat compared to fish from less polluted areas. Several fatty acids were missing in fish with higher levels of DNA in comet tail and micronucleus induction. Long-chain polyunsaturated fatty acids, eicosapentaenoic acid (20:5n-3) was found missing in the fish from polluted environment while it was found in considerable amount in farmed fish 7.8±0.4%. Docosahexaenoic acid (22:6n-3) also showed significant differences as 0.1±0.0 and 7.0±0.1% respectively, in wild polluted and farmed fishes.

Forensic STR profiling based smart barcode, a highly efficient and cost effective human identification system

In forensic science, the human identification is the major goal in criminal cases and in paternity dispute, based on DNA profiling of individual. Analysis of short tandem repeat (STRs) markers used as a reliable technique for this purpose. In this study the main objective was to develop a human identification based on DNA fingerprinting using Human Identification Barcode System (HIBS). HIBS may be used to provide a unique molecular signature of human in the form of a barcode. DNA was isolated from blood by using PCR technique to detect bands to design human barcode using self-designed system. HIBS is a web based application that can be accessed via www.hibs.com.pk. HIBS can be accessed with internet access and may be introduced on security checkpoints to identify an individual based on his own DNA instead of conventional procedures of identification. The barcode generated through DNA fingerprinting will be stored in a HIBS, and may also be a part of CNIC. It may be successfully used against suicide bombers, target killers, etc., as even a single blood spot, a few skin cells, root of the hair etc., to identify such culprits. It may also be effectively used to relieve the individuals with false accusations.

Use of statistical analysis to validate ecogenotoxicology findings arising from various comet assay components

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.