A COMPARATIVE STUDY OF THE AFTER-EFFECTS OF IRRADIATION ON THE NON-DISJUNCTION OF X-CHROMOSOME

Abstract

A comparative study of the after-effects of irradiation on the nondisjunction of X-chromosome in two lines wᵃ and Canton-S of Drosophila was carried on. Adult females were irradiated with a 3000 r dose of X-rays (200 kv) without filter. In order to study the after-effect, the females in an hour after irradiation were kept at +37° for eight hours. The after-effect of irradiation was found in both lines. In the line Canton-S the successive treatments with X-rays and high temperature gave 5.62±0.46Q% of exceptional males, a value of which is significantly higher than the arithmetic sum of the exceptional males found after independent treatments with X-rays (3.50±0,192%) and temperature (0.11 ±0.034%). Analogous results were also found in the line wa. The corresponding values for exceptional males in this line were: 4.46 ± 0.398; 1.62 ± 0.131; 0.09±0.051%, The after-effect of irradiation was found to be much higher in the radiation-resistant line wᵃ (160%) in comparison to Canton-S (56%) which is not radiation-resistant.