Development of tolerance to ethanol in relation to the alcohol dehydrogenase locus in Drosophila melanogaster 1. Adult and egg-to-adult survival in relation to ADH activity

Strains of Drosophila melanogaster homozygous either for the AdhF or the AdhS allele, were kept on food supplemented with ethanol. After 90 generations these strains (FFE and SSE) were tested for tolerance to ethanol and compared with control strains (FFN and SSN) from regular food. The E strains showed increased tolerance to ethanol, both in the adult and in the juvenile life stages. In the adults the increase in tolerance was not accompanied by an increase in ADH activity. In the juvenile life stages there were significant differences in ADH activity between the E and N strains, both on regular food and on food containing ethanol. However, ADH activity was not the only factor involved in the increased tolerance to ethanol. The Adh genotype of the mother was of paramount importance to egg-to-adult survival because of a maternal effect on ethanol tolerance in the eggs and first instar larvae. Furthermore developmental times of the E strains were longer than those of the corresponding N strains. It is concluded that the adaptation to ethanol-containing food was not realised in the same way in the FFE and SSE strains