Development of ethanol tolerance in relation to the alcohol dehydrogenase locus in Drosophila melanogaster. II. The influence of phenotypic adaptation and maternal effect on survival on alcohol supplemented media

Abstract

The role of phenotypic adaptation and maternal effects in the survival of Drosophila melanogaster on media supplemented with alcohol was investigated. Egg-to-adult survival depends on the age at which the eggs are transferred from regular to ethanol-containing food. Eggs transferred at an age of 8 hours or less, produce significantly more adults than eggs transferred after 14 hours. This phenomenon is not observed when eggs are exposed only temporarily to ethanol at different ages. Phenotypic adaptation was also observed on food supplemented with propanol, butanol and hexanol for strains not selected for ethanol tolerance. Maternal effects had a great influence on egg-to-adult survival on ethanol-supplemented food. Eggs homozygous for the Adh'1 allele showed a significantly better survival on 4 per cent ethanol food when laid by ADH-positive mothers, than laid by ADH-negative mothers. This maternal effect was probably caused by maternal ADH and not by maternal mRNA. Phenotypic adaptation and maternal effect are both important in the survival of D. melanogaster on food containing alcohol, especially in the case of selection during pre-adult life stages.

Selection against Adh null alleles in Drosophila melanogaster

“…These results confirm earlier conclusions that ADH takes a paramount position in the detoxification of alcohols and that genotypes who lack or have reduced ADH activity (as in the case of heterozygotes for Adh°a nd Adh positive alleles) possess increased mortalities even at low ethanol concentrations (David et al, 1976;Kamping and Van Delden, 1978;Kerver and Rotman, 1987). When using the combined viability estimates for the construction of a curve of Adh° frequency decline on ethanol food a perfect fit with the observed curve in the F/ 0 populations is obtained.…”

“…A genotype's survival in the presence of alcohols in toxic concentrations is positively correlated with its in vitro ADH activity. Homozygotes for Adh null mutants are extremely sensitive to ethanol and experience high mortalities at alcohol concentrations too low to harm ADH positive flies (David et a!., 1976; Kerver and Rotman, 1987). Besides its detoxifying role, ADH may perform other metabolic functions:…”

Ethanol and acetic-acid tolerances in Drosophila melanogaster: similar maternal effects in a cross between 2 geographic races

“…The most striking observation is that physiological differences between reciprocal F i s, which are initiated in the embryo, persist until the adult stage. By contrast, maternal effects on ADH activity, described by Kerver and Rotman (1987), disappeared much earlier in the larval stages. We do not know which metabolic pathway is involved in the maternal influence observed in crosses between European and Afrotropical flies.…”

“…Ethanol tolerance is based on the presence of a very abundant alcohol dehydrogenase (ADH), and null mutants are very sensitive (David et al 1976). On the other hand, flies that are heterozygous for a null and a normal allele exhibit a normal tolerance (Kerver and Rotman, 1987 (David and Bocquet, 1975;David et al, 1988 (Chakir et al, 1993). It remained possible that, in spite of having the same electrophoretic allele and the same protein (see Kreitman, 1983) Middleton and Kacser (1983) .…”

Regulatory differences in developmental expression of alcohol dehydrogenase are related to interspecies differences in ethanol tolerance of Drosophila

“…In general, ethanol as a selective agent can act either at the preadult or adult stages of Drosophila. It was shown earlier that in D. melanogaster, the adaptation to ethanol-rich media was mainly accomplished during the juvenile life stages and that the maternal ADH has a significant role in that process (Kerver & van Delden, 1985;Kerver & Rotman, 1987). In the virilis phylad of Drosophila, ADH is not maternally encoded and zygotic transcription of Adh is not seen until the 24th hour of embryogenesis (G. Ranganayakulu, unpublished data).…”