NILE TILAPIA AS BIO INDICATOR TO ESTIMATE THE CONTAMINATION OF WATER USING SDS-PAGE AND RAPDPCR TECHNIQUES

Abstract

The present study used Nile tilapia (Oreochromis niloticus) as an biological marker to revealed the concentrations of some heavy metals (Cu, Pb and Cd) in water, gills and muscles of fish collected from four sites in Egypt {Maryuot Lake, Manzala Lake and the River Nile (Mansura)} which are polluted by industrial effluents, waste municipal and agricultural drainage water that is discharged directly into them in addition to Ismailia Canal (Abassa) as control. Analysis of water samples showed that Abassa site was the lowest concentration of copper, cadmium and lead (0.18, 0.0 and 0.2 ppm, respectively) while, Manzala Lake site showed the highest concentration (16.38, 2.87 and 10.1, respectively) and heavy metals in the water samples of Abassa site were within the permissible limits. Abassa site showed the lowest concentrations of the three heavy metals in gill and muscle while, Manzala Lake site indicated the highest concentrations. Copper and cadmium in gill and muscle samples of Abassa site and muscle samples of Mansoura site were within the permissible limits. Polyacrylamid gel electrophoresis was used to study protein banding pattern variation in tested fish and was showed variation in number of phenotypic bands and the variation between and within each site was clear. Protein locus (55 KDa) in 90% of Mansoura samples and also protein locus (32 KDa) in all samples were missed compared to control Site. Maryuot Lake samples demonstrated loss of protein loci (55 and 60 KDa) in 100% of samples and appeared a new protein locus (163 KDa) with ratio of 75%. Manzalla samples compared with control were missed protein locus (60 KDa) in all samples and appeared a new protein locus (163 KDa) in 25% of samples. Appear of a new protein locus (163 KDa) in Maryuot and Manzalla Lakes considered as a resistance protein for pollution. Results of RAPD with the five primers showed that the total No. of fragments were 55 with average 11 fragments which ranged from 140 to 2323 bp approximately. The total polymorphism was 87.27% and the total polymorphic fragments were 48 with average 9.6 fragments per primer. The different band profile (appearance/ disappearance) between polluted fishes and control fishes was shown. Results of RAPD and protein electrophoresis showed that heavy metals were genotoxic to Nile Tilapia fish.