COMPARATIVE AUTOSOMAL LINKAGE IN MAMMALS: GENETICS OF ESTERASES IN MUS MUSCULUS AND RATTUS NORVEGICUS

James E. Womack ¹ and Mark Sharp ²

¹ The Jackson Laboratory, Bar Harbor, Maine 04609
² Department of Biology, Abilene Christian College, Abilene, Texas 79601

Recombination between Esterase-4 and Esterase-2 in the rat was not observed in 278 backcross offspring. Es-4 is thus included within the "esterase cluster" in Linkage group V. A new map of this region was constructed and the relationship of the four esterase loci was found to be: Es-4–(9.6 ± 1.6 cM)–Es-2, Es-4–(1.5 ± 0.7 cM)–Es-3 . Homology of this region with a region of Linkage Group XVIII (Chromosome 8) of the mouse was proposed on the basis of tissue distribution, subcellular localization and response of enzymes to inhibitors. Specifically, rat Es-1 was suggested as the homolog of mouse Es-2, rat Es-2 as the homolog of mouse Es-1, and rat Es-4 as the homolog of mouse Es-6. An autosomal segment comprising at least 15 cM of the rat and mouse genomes appears to have remained relatively intact with respect to genetic content during rodent speciation. In addition, a new polymorphism for mouse esterase was described. The locus was designated Esterase-10 (Es-10) and proposed as the mouse homolog of human Esterase D. Linkage of Es-10 with nucleoside phosphorylase-1 (Np-1) on Chromosome 14 was established.