Abstract
Electrophoretic variations in the integument esterase of the silkworm, Bombyx mori L., were found. The esterase was classified into the six fundamental isozyme types, O, A, B, C, AB and AC. The mode of inheritance of these isozymes was studied and confirmed that they are controlled by codominant alleles, IesO, IesA, IesB, IesC, IesAB and IesAC respectively. The esterase activities in individuals with compound types, AB or AC, were approximately twice as high as that in the single band type. These individuals seemed to be homozygotes for the genes IesAB or IesAC, which might be occurred by the duplication of primitive genes, IesA and IesB or IesA and IesC.
Frequencies of these codominant genes in the silkworm population were calculated from the results of 202 strains investigated. The frequencies of the Ies genes C, B, AC, AB, O, and A were 0.44, 0.25, 0.21, 0.08, 0.01 and 0.01, respectively.
