Genetics of Zoarces populations

Three esterase isozynie systems, I, II, and III, are present simultaneously in eye tissue, gonads and hemolysate from Zoarces. Two of these systems, II and III, are also present in brain tissue. All three esterases react specifically with short-chained aliphatic alpha esters. Since molecular variations occur independently in the three systems, they are controlled by at least three different loci, Est I, Est II, and Est III. In a population in Kalö Cove, near Aarhus, Est I and Est III are polymorphic, while Est II is monomorphic. Est I has one common active allele and one common silent allele. Est III has two common active alleles in the population. Extensive data showing that Est III segregates its alleles one-to-one are presented. Est III recombines freely with the previously described loci PgmI and PgmII. Like the Pgm loci, EstIII shows certain deviating segregations which is most likely due to the occurrence of double or multiple matings per brood.