Strain Differences in Minimum Anesthetic Concentrations in Drosophila melanogaster

Abstract

An ether-resistant strain of D. melanogaster was maintained since the appearance of 1 female mutant in 1961. Sensitivity was defined using mortality as an endpoint when exposed to a high concentration of diethylether; this does not necessarily mean that anesthetic requirements are higher in the resistant strain. The difference in anesthetic potency between the ether-resistant strain (Eth-29) and 1 of the sensitive strains (bw;st;svn) was studied. The median effective dose (ED50) for halothane was 0.0096 atm in females and 0.0091 atm in males of the bw;st;svn strain, while in the Eth-29 strain the ED50 was 0.0148 atm in both sexes. The ED50 values for chloroform anesthesia were 0.0051 atm in females and 0.0050 atm in males of the bw;st;svn strain and 0.0100 atm in the Eth-29 strain in both sexes. Strain differences in response to the 2 anesthetics were statistically significant. The Eth-29 strain shows a cross-resistance to both halothane and chloroform anesthesia. Reciprocal crosses between the 2 strains revealed that the resistance to halothane anesthesia was a sex-linked recessive trait and that the resistance to chloroform anesthesia was an autosomal incompletely dominant trait.