Induction of Genotoxic Damage in Fish as Revealed by the Micronucleus Test and the Comet Assay Following In Vivo Exposure to Marine Toxin Okadaic Acid

Abstract

Okadaic acid (OA) involved in Diarrheic Shellfish Poisoning (DSP) is a marine toxin produced by dinoflagellates such as Prorocentrum sp. Although the neurotoxic properties of DA are well documented, very little is known regarding in vivo genotoxicity of OA on aquatic organisms, especially on fish. In the present paper, an in vivo study on the genotoxic effects of OA was carried out on a model fish Oreochromis niloticus using the micronucleus test and the comet assay. The fish were exposed to three different doses of okadaic acid via intraperitoneal injection. Ethyl methane sulphonate (EMS) at a single dose of 5 mg/l was used as positive control. Analysis of micronuclei, nuclear abnormalities and DNA damage were carried out on peripheral erythrocytes sampled at intervals of 24, 48 and 72 h post treatment. Our results revealed significant increases in the frequencies of micronuclei, nuclear abnormalities as well as DNA strand breaks indicating the genotoxic potential of OA on fish.