The acute sensitivity of a human individual to ethanol''s intoxicating effects correlates negatively with predisposition towards alcoholism. We seek to understand mechanisms of ethanol intoxication in C. elegans to identify candidate genes and pathways that may vary in human individuals with differing acute responses to alcohol. Using forward genetics, we previously have identified the BK potassium channel encoding gene,
slo-1, as a significant mediator of the acute effects of ethanol on locomotion and egg-laying behaviors. Given that mutant animals carrying complete loss-of-function mutations in the
slo-1 gene show ethanol-induced decreases in the speed of locomotion, we surmise that there must be additional mediators of ethanol''s effects in this organism. By screening for new mutations that enhance the ethanol resistance of a
slo-1 null mutant we expect to identify genes that act additively to, and independently of,
slo-1 to mediate the effects of ethanol on locomotion. So far we have screened ~6000 randomly mutagenized haploid genomes and identified 15 mutant strains that appear to have reduced sensitivity to the effects of ethanol on locomotion compared with the
slo-1 null mutant parent animals. The increase in ethanol resistance generated in the
slo-1 mutant background by most of the new mutations varies between 10-30% depending on the strain. In addition, several of the isolated strains appear to increase the basal (untreated) speed of the
slo-1 mutant animals, which is decreased relative to wild-type animals. These changes in basal speed appear to occur without altering the degree of ethanol resistance provided by the
slo-1 mutation. These particular mutations are unlikely to affect mechanisms of ethanol intoxication but may prove useful in understanding the role of SLO-1 in regulating locomotion, as they appear to compensate to some extent for loss of SLO-1 function. Mapping of several of the mutations that appear to alter ethanol sensitivity is underway with the aim of identifying genes using a positional cloning strategy. Funded by ABMRF and NIAAA.