POLYGENIC DETERMINATION OF QUININE AVERSION AMONG MICE

There are substantial differences among inbred mouse strains in avoidance of quinine solutions in two-bottle preference tests. A Mendelian cross-breeding experiment was conducted to test the hypothesis that a single locus Qui has a major influence on quinine aversion. Inbred strains C57Bl/6J (B6, avoider) and C3HeB/FeJ (C3, indifferent) were progenitors Of two Segregating generations. Phenotypic ratios for 100-mu-M and 30-mu-M quinine sulfate (QSO4) in these generations were not consistent with ratios expected for a single gene. Frequency distributions for individual preference ratios were more characteristic of a polygenic trait. An outbred strain (CFW/Crl) which displays segregation for the Soa locus was tested for both QSO4 and sucrose octa-acetate (SOA) avoidance- Correlated avoidance patterns for the two bitter compounds were found in these mice. A Soa effect might not have been seen in the C3.B6 cross because both strains are relatively poor SOA avoiders. A second Mendelian cross was made between strains C3 and SWR/J (SW, SOA and QSO4 avoider). One segregating generation was tested with both compounds. In these mice. as in the CFW population, QSO4 aversion was correlated with SOA aversion. These results suggest that quinine aversion is polygenic, that there is a relationship between SOA sensitivity and quinine sensitivity, and that this association may be the result of variation at the Soa locus.