Genetic activities of 4-chloromethylbiphenyl, the 4-hydroxy derivative and benzyl chloride in the soma and germ line of Drosophila melanogaster.

The genetic activities of 4CMB, 4HMB and BC were assayed as regards the induction of somatic alterations in gene expression on an unstable w+ locus with an intragenic TE and all the simultaneously induced germinal mutations on the X-chromosome carrying this locus. The compounds were applied topically in solution at equimolar doses on late embryos and newly hatched larvae. The somatic events were scored as aberrantly pigmented eye sectors in the emerging adult males and the germinal mutations in their F2 progeny, according to the Muller-5 technique. The somatic events were expressed as red or while mosaic eye sectors; the former could be an outcome of the repression or deletion of the zeste-regulatory proximal subunits of w+ locus, and the latter generally attributable to deletions (w-) within its structural part. All 3 compounds were effective in the induction of red sectors at the higher tested doses (0.5-2.0 mM) and the level of this activity was virtually the same for 4CMB and 4HMB, but was 2-fold higher for BC. In contrast, the frequencies of the simultaneously scored white sectors were not raised significantly above the controls with 4CMB, but showed decisive increases above this level with both 4HMB and BC. The germinal X-chromosome mutations (recessive lethals and visibles) were only induced at the highest tested dose (2.0 mM), and their frequencies were virtually the same for all 3 compounds reaching a common level of about 0.6%, which is some 3-fold the normal control level for the test system. Specific-locus mutability at the TE w+ was suggestively positive only with BC.