Nоn-disjunction of chromosomes produced by X-rays of different wave length and intensity

Abstract

The experiment was designed to study the mechanism of non-disjunction of x-chromosome by irradiation of Drosophila females with X-rays. The non-disjunction of X-chromosome is detected by the frequent occurrence of XO males. For the study of the problem, the females were irradiated with a single dose (3000 r) using radiation of different wave length and intensity. In order to show the after-effect, an additional treatment by -37° for 8 hours was carried in one hour after irradiation. Hard X-ravs (with short wave lengths) seem to be more effective (2.81 ±0.163%), that soft (those with longer wave lengths) (1.84±0.124% and 0.97±0.12<S%). The after-effect of hard rays (4.45±0.379%) differs from that of soft rays (1.70 ± 0.145 % and i .29 ±0.161 % ). Soft rays with greater intensity appear to be more effective (1.84±0.I24%), than those with lower intensity (0.97± 1.128%). On the basis of this results it may in- suggested that Л'-rays of different quality produce different types of chromosomal breaks, which form the basis of the mechanism of chromosomal non-disjunction.