Oreochromis niloticus: An Ideal Model to Assess the Extent of Pollution in Aquatic Environment

Presence of heavy metals effectuate chemical pollution in water which deteriorates human health as well as animals and when they consume the contaminated water, it results in severe ailments. Harmful substances get accumulated and induce toxicity to aquatic the life which are playing a major role in aquatic ecosystems¹.

Therefore, the evaluation of biological impacts on aquatic vertebrate as well as invertebrate species is employed to determine water pollution as it provides significant information regarding bioavailability as well as effective concentration levels. In this regard, genotoxic agents that produce DNA changes at subtoxic exposure levels are of special concern. As, clastogenic (chromosome breaking) compounds leads towards modified reproductive results, genetic diseases as well as cancer².

Oreochromis niloticus is regarded as one of the most commercial and widespread freshwater fish species. A variety of species of tilapia have been recommended by several researchers as test models for both cytogenetic as well as molecular inveigations³.

Accordingly, scientists carried out a novel research in order to explore the ability of copper sulfate (CuSO₄) as well as lead acetate (CHCOO)₃ Pb in inducing chromosomal aberrations in aquatic organisms. For this purpose, Oreochromis niloticus was selected as a test material⁴.

During this experiment, the research team evaluated the LC₅₀ of the two chemicals and the data indicated that LC₅₀ of copper sulfate and lead acetate were 40.6 and 422.5 mg L^-1, respectively. Afterward, scientists studied the impact of both chemicals on fish chromosomes and mitotic indices⁴.

This research showed that gill cells of the tested fish by copper sulfate and lead acetate exhibit lower mitotic activity as compared to the control group. However, both the chemicals were noted to be a positive inducer of macro-DNA damage and displayed different types of aberrations.

Conclusively, water pollution, particularly with heavy metals, possess a clastogenic effect on fishes and it can cause health risks among humans through chronic consumption of these fishes. This study also suggested that O. niloticus can be utilized in order to examine the degree of pollution in the aquatic environment.

REFERENCES

1. De Gregori, I., H. Pinochet, D. Delgado, N. Gras and I. Munoz, 1994. Heavy metals in bivalve mussels and their habitats from different sites along the Chilean Coast. Bull. Environ. Contam. Toxicol., 52: 261-268.
2. Bunton, T.E., 1999. Use of Non-Mammalian Species in Bioassays for Carcinogenicity. In: The Use of Short and Medium-Term Tests for Carcinogen and Data on Genetic Effects in Carcinogenic Hazard Evaluation, McGregor, D.B., J.M. Rice and S. Venitt (Eds.). IARC Scientific Publication No. 146, International Agent for Research on Cancer, Lyon, pp: 151-183.
3. Martins, C., A.P. Wasko, C. Oliveira, F. Porto-Foresti, P.P. Parise-Masltempi, J.M. Wright and F. Foresti, 2002. Dynamics of 5S rDNA in the tilapia (Oreochromis niloticus) genome: Repeat units, inverted sequences, pseudogenes and chromosome loci. Cytogenet. Genome Res., 98: 78-85.
4. Mohamed, M.M., S.A. El-Fiky, Y.M. Soheir and A.I. Abeer, 2008. Cytogenetic studies on the effect of copper sulfate and lead acetate pollution on Oreochromis niloticus fish. Asian J. Cell Biol., 3: 51-60.