The genetics of tasting in mice VII. Glycine revisited, and the chromosomal location ofSacandSoa

Abstract

SummaryPrevious work which appeared to show that some strains of mice taste glycine solutions as bitter has been found to be in error. The bitterness came from copper glycinate which formed in the brass drinking spouts. Taste testing with copper glycinate shows that the genetical data identifying the geneGlbare still valid. The close linkage ofGlbandRuahas been confirmed. Most strains of mice prefer glycine solution to water, presumably because the glycine tastes sweet. The degree of preference for glycine is correlated with the degree of preference for other sweet substances such as saccharin or acesulfame. The genedpaappears not to be involved.The sweetness tasting geneSachas been mapped to chromosome 4 at 8·1 ± 3·4 cM distal toNppa(formerlyPnd). The bitterness tasting geneSoais very closely linked toPrpon chromosome 6 (no recombinants among 67 backcross progeny). It is suggested that the sweetness and bitterness tasting genes have descended from a common ancestral tasting gene which existed before the tetraploidization of the genome which took place in early vertebrate evolution.