A temperature effect on nondisjunction of the X chromosomes among eggs from aged Drosophila females.

Abstract

The effects of temperature and aging on the frequency of nondisjunction inDrosophila melanogaster eggs were investigated. At 25°C offspring arising from 3–5 day old control females had a nondisjunction frequency (0.943/1000 offspring) very similar to that for females who were 24–26 or 27 days old when eggs were collected (1.044/1000 offspring). When females were aged for the same length of time at 10°C the frequency of nondisjunctional exceptions increased to 3.368 per 1000 offspring. These results indicate that aging the females at 25°C does not increase the nondisjunction rate over that obtained from non-aged females raised at 25°. The increase in nondisjunction frequencies when the females were aged at 10°C reflects an influence of temperature on the meiotic process inDrosophila melanogaster. At the low temperature eggs were also aged since few or no eggs were laid during the aging process. Thus in addition to a temperature effect on nondisjunction rates at 10°C there may also be an age effect.