Influence of age and prolongation of larval life on the occurrence of spontaneous mutations in drosophila

Abstract

A study was made of the effect of age and anabolism on the frequency of sex-linked lethal mutations in Drosophila melanogaster. Two sets of experimental flies were used; the first eggs laid by them . furnished the control material. In one experimental set the males and females were kept together individually on standard yeasted food (high anabolism), and in the other set the females, after being inseminated, were removed from the males and kept on syrup food (low anabolism). The flies of both sets were transferred every 4th day till the 26th and 25th days, respectively, after mating, when they were finally placed on standard yeasted food for the laying of eggs. The flies (F1) derived from these eggs were tested for the presence of sex -linked lethals. Temperature (23°C) and other conditions were maintained as constant as possible.

The following are the results:

1. The frequency of sex-linked lethals is reduced significantly in both the male and female germ cells produced in old age, as compared with those produced while young.

2. Old age combined with low anabolism of the germ cells seems to result in,the same degree of reduction in the frequency of lethal mutations in female germ cells as old age combined with high anabolism (adequate food and mating).

3. The ageing of the sperm inside the spermathecae of females having low anabolic processes gives a lower rate of sex-linked lethals than that found in the non-aged sperm.

4. There is some indication of a tendency for the frequency of lethals to be reduced more by ageing in the case of the male than of the female germ cells.