FISH ECO-GENOTOXICOLOGY: MICRONUCLEUS ASSAY IN FISH ERYTHROCYTES AS IN SITU BIOMARKER OF FRESHWATER POLLUTION

Shahid Mahboob1, Bilal Hussain2, Tayyaba Sultana2, Salma Sultana2 and K. A. Al-Ghanim1
 
1. Department of Zoology, College of Science P.O. Box 2455, Riyadh 11451, Saudi Arabia
Department of Zoology, GC University, Faisalabad, Pakistan
Email:shahidmahboob60@hotmail.com
 

Waste disposal from industry and urban structures in Asian rivers has resulted in deposition of variety of new toxic chemicals and organic compounds. Such activities have endangered the existence of ecosystems and their inhabitants. Changes in genome caused by genotoxic agents led to mutations and pose burden to the populations of fish species. Toxicants those induce genetic damage involve everlasting monitoring and before time detection. The unremitting input of toxicants into the freshwater bodies has led to the advancement in techniques for evaluation and monitoring the fate such ecosystems. Fishes are marvelous model animals for genotoxicological studies and provide early warnings for toxicants induced environmental alterations and degradations. Fish species may also be used to estimate the possible effects of toxicants to produce carcinogenic and teratogenic effects in human.

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 merciless toxicity level of Cd, Cu, Mn, Zn, Pb, Cr, Sn and Hg. Comet assay results indicated significant (p<0.05) DNA fragmentation in Labeo rohita as 42.21±2.06%, 31.26±2.41% and 21.84±2.21 % DNA in comet tail, tail moment as 17.71±1.79, 10.30±1.78 and 7.81±1.56, olive moment as 13.58±1.306, 8.10±1.04 5.88±0.06, respectively, from three different polluted sites of the river. Micronucleus assay showed similar findings of single micronucleus induction (MN) as 50.00±6.30‰, double MN 14.40±2.56‰, while nuclear abnormalities (NA) were found as 150.00±2.92‰. These higher frequencies of MN induction and NA were found to be the cause of reduction of 96% of population of this fish species in 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 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 biomarker of pollution load in freshwater bodies.