Studies on X-Ray Induced Detrimentals in the Second Chromosome of Drosophila Melanogaster

Abstract

HE great majority of experiments with Drosophila on radiation T induced mutations centers about questions of lethal mutations.Several investigations are, however, also made on mutations with less drastic effects, and it seems as if, during the last decade, the interest has switched over to mutations of this kind. The present investigation deals with different questions concerning x-ray induced subvitals in the second chromosome of D. melanogaster. The frequency of such mutations are considered and the comparisons made are in some instances also combined with the effects of different degrees of environmental stresses. MATERIALThe wild type flies used in the experiments were extracted from a Canton S stock. The flies were first made co-isogenic by making the crosses outlined in Fig. 1. As may be seen, (matings 1-5) the second chromosome al* Cy It" spa (abbreviated Cy) was used as marker and crossing over suppressor during the isogenisation. Later it was substituted by the chromosome al' Cy It" L' spa (abbreviated Cy L ; Fig. 1, mating 6 and onwards). The matings 1, 2, 3 and 4 were made in several replicates. In one of these the progeny of mating 4 was 26+, 53 Cy, 49 D 89 Cy D, which is in good agreement with the expected proportions 1: 2: 2: 4 (P between 0.7 and 0.8). The parents of mating 5 showed in this replicate good fertility; this replicate was, therefore, used as the foundation stock from which all ))wild type, chromosomes of the present study emanate. In a sideline the chromosomes al' Cy It" sps and ru h D8 Ins CXF ca (abbreviated Cy D) were retained on the male side