Review of the current status of the mei-9a test for chromosome loss in Drosophila melanogaster: an assay with radically improved detection capacity for chromosome lesions induced by methyl methanesulfonate (MMS), dimethylnitrosamine (DMN), and especially diethylnitrosamine (DEN) and procarbazine.

A review of previous findings as well as new data are included in the present paper on recent investigations by Zimmering and co-workers regarding a radical improvement in the detection capacity of the conventional test for chromosome loss to assay for induced chromosome lesions/breakage. The improvement has been achieved through the use of mei-9a repair-deficient P1 females to which treated males are mated. 4 compounds have been tested including MMS, DMN, DEN and procarbazine. Not only has the mei-9a test yielded significantly higher frequencies of induced chromosome loss with MMS and DMN than the conventional test, preliminary data, in fact, providing evidence of a positive response in the mei-9a test at a concentration one order of magnitude below that producing no effect in the conventional test, but, more critically, it has permitted detection of highly significant increases in induced chromosome loss with DEN and procarbazine, compounds proving negative in the conventional tests for chromosome loss and heritable translocations at all concentrations employed including those producing substantial to high frequencies of recessive lethals.