Inducible protective processes in animal systems. IX. Potentiality of adaptive response by nicotinamide in MMS adapted meiotic cells of grasshopper Poecilocerus pictus

The discovery of adaptive response E. coli induced by low doses of alkylating agent has lead to an extensive research in understanding the existence of such process. There are reports on adaptive response in in vivo and in vitro systems. Recently we also have shown such phenomena in in vivo grasshopper Poecilocerus pictus and mouse test systems. Different repair enzymes are implicated in this process viz. O⁶-methyI guanine methyl transferase, poly (ADP-ribose) polymerase etc. In the present study an attempt has been made to understand the involvement of PARP in methyl methane sulfonate (MMS)-induced adaptive response in meiotic cells of grasshopper P. pictus by employing nicotinamide, an inhibitor of PARP. Three sets of experiments viz. pre-, inter-, and post- treatment of Nicotinamide were carried out. The results of these experiments have revealed that there is a reduction in the frequency of chromosomal anomalies compared to combined treatment at all recovery times tested indicating the enhancement of adaptive response by nicotinamide. These results are discussed in the light of involvement of PAR.P in adaptive response.