Linkage analyses among five esterase loci in the laboratory rat (Rattus norvegicus).

A cluster of esterase loci has been identified on a segment of a rat linkage group V; however, the linear order of all the loci has not been established. We estimated the recombination frequencies of two locus combinations among five esterase loci (Es-1, Es-2, Es-3, Es-4, and Es-Si) and the linear order of the loci by using three sets of backcross matings: (1) (K:W x IS) x IS, (2) (K:W x IS) x IS, and (3) (SHR x W) x W). The linear order was determined to be ES-1-ES-4-ES-2-ES-3-ES-Si, although the order of ES-2 and Es-4 remains tentative. The sex-influenced esterase (Es-Si) was demonstrated to be distinct from Es-1 and was proposed to be Es-Si locus with two alleles of Es-Si(a) (positive) and Es-Si(b) (null).