Comparison between the micronucleus frequencies of kidney and gill erythrocytes in Tilapia fish, following mitomycin C treatment

The frequencies of mitomycin C and cyclophosphamide-induced kidney and gill erythrocyte micronuclei were compared in Tilapia rendalli and Oreochromis niloticus. Cyclophosphamide (CP) and mitomycin C (MMC) were previously used to investigate fish sensitivity to micronuclei induction in kidney erythrocytes. Fish were treated with a single dose of cyclophosphamide (40 mg/kg) or mitomycin C (2 mg/kg). Peripheral blood samples and kidney blood samples were obtained, 1, 2, 3, 5, 7, and 15 days after the intra-abdominal injection of MMC. T. rendalli showed to be more sensitive than O. niloticus to micronuclei production. Both compounds were used at the maximum tolerated dose (MTD), and mitomycin C proved to be more toxic than cyclophosphamide. The frequency of micronucleated erythrocytes observed varied significantly among the treated individuals. The difference between the kidney and gill micronuclei frequencies was not significant. Higher levels of micronucleated erythrocytes were observed in Tilapia rendalli than in O. niloticus. T. rendalli produced erythrocytes with deformed nuclei, which O. niloticus did not.