5.Time dependent induction of genotoxicity and cytotoxicity by thiodicarb in Calotes versicolor
Nisha Shrivastava and Tumul Singh
In the present work three very sensitive biomarkers chromosomal aberrations (CA), micronucleus (MN) and mitotic index (MI) has been used to test the genotoxic and cytotoxic potentials of thiodicarb, a carbamate insecticide in the bone marrow of Calotes versicolor. Adult male garden lizards were acclimatized for one week in the laboratory and then injected intraperitoneally with a daily dose of 13.33 mg/kg body weight (1/3rd LD50) of thiodicarb. The bone marrow was used for scoring (CA), (MN) and (MI). Chromosomal aberrations in the form of numerical and structural changes were observed in the treated group. Numerical changes included aneuploidy with a general pattern of monosomy and the structural changes included gaps, breaks, additions and deletions. Frequencies of CA in the form of gaps increased significantly after 14th (P≤ 0.05), 21st (P≤ 0.005) and 28th day (P≤ 0.0005) of treatment. Breaks increased significantly (P≤ 0.05) after 21st day and deletions increased significantly (P≤ 0.05) after 28th day of treatment. MN frequencies increased significantly after 21st and 28th day P≤ 0.005 and 0.0005 respectively. No significant change in frequencies of MI was observed till 14th day. However, after 21st day MI frequencies decreased significantly (P≤ 0.05) in the treated group. This study thus, reveals that thiodicarb induces genotoxicity and cytotoxicity in a time dependent manner in the bone marrow cells of Calotes versicolor.