The Induction by Mustard Gas of Chromosomal Instabilities in Drosophila melanogaster.

Abstract

The discovery (Auerbach, 1943, 1946; Auerbach and Robson, 1946, 1947) that mustard gas is comparable to X-rays and similar physical agencies in its ability to produce mutations and chromosome rearrangements has opened up a new line of approach to the problem of gene mutation. It is to be expected that a comparative study of the mechanism by which chemical substances on the one hand and physical agencies on the other exercise their mutagenic effects, will further our understanding of the process of mutation itself. One of the first questions to be tackled in the early days of radiation genetics was the possibility of a delayed mutagenic action of irradiation (Muller, 1927; Timoféeff-Ressovsky, 1930, 1931; Grüneberg, 1931). The bulk of the evidence (see, however, Bishop, 1942) indicates that X-ray-induced mutations and chromosome breaks arise as an immediate effect of the irradiation, although after treatment of mature spermatozoa new recombinations of broken chromosomes may be delayed until the spermatozoon has entered the egg. Data obtained by Stadler (1939) suggest that after ultra-violet radiation of pollen grains the mutational process often is not completed before the treated chromosome has split into its two daughter chromatids. This results in a high proportion of mosaics. A similarly high proportion of mosaics has been found in the progeny of Drosophila ♂♂ which had been treated with mustard gas (Auerbach, 1946; Auerbach and Robson, 1946). This raises the question of a possible delayed action of the chemical mutagenic treatment.