Esterase polymorphisms in Microtus ochrogaster: interaction and linkage

Three polymorphic loci have been identified in the prairie vole, Microtus ochrogaster. Together they control a group of plasma esterases which can be separated using starch gel electrophoresis. A structural locus, Es-1, produces an enzyme which from genetic evidence appears to be a dimer. The allele Es-1 ^a produces a wholly active subunit, and homozygotes give a single enzyme band. The product of the second allele, Es-1 ^o, cannot form active enzyme on its own but will dimerize with the Es-1 ^a subunit, giving a hybrid enzyme with a slower electrophoretic mobility than the pure Es-1 ^a enzyme. The third allele, Es-1 ^–, has no detectable product. A second structural locus, Es-2, is linked to Es-1. The allele Es-2 ^a produces a single enzyme band, but the second allele Es-2 ^– has no detectable product. A modifier locus, Me, changes the mobility of the Es-1 enzymes. Me ^f is dominant over me ^s, and in homozygotes for me ^s the mobility is reduced.This work was supported by National Science Foundation Grant GB6273.This is contribution No. 869 from that Department.