Inducible protective processes in animal systems .5. Clastogenic adaptation triggered by low-dose of methyl methanesulfonate (mms) in poecilocerus-pictus

The monofunctional alkylating agent methyl methanesulfonate (MMS) was used to study the induction of inducible protective processes (clastogenic adaptation) in meiotic cells of the grasshopper, Poecilocerus pictus. After a low (conditioning) dose of 0.012 M and challenging with a high (challenging) dose of 0.048 M MMS after 2 h time-lag, the incidence of chromosomal anomalies in metaphase I, II and anaphase I and II stages was found to be significantly less (P < 0.05) compared to that of the additive effect of both the conditioning and the challenging doses. The data suggest that the low dose of MMS rendered the meiotic cells more resistant to the clastogenic effects of a subsequent high dose of MMS employed. These results lend further support to the earlier report from the same laboratory where a low dose of ethyl methanesulfonate (EMS) was found to render protection against a high dose of the same clastogen in meiotic cells of P. pictus. Furthermore, it is clear from the results that conditioning by the methylating (MMS) agent in cells is less effective in comparison with that of the ethylating (EMS) agent.