Genetic variants of protease inhibitors against fungal protease and alpha-chymotrypsin from hemolymph of the silkworm, Bombyx mori.

Many electrophoretic variants of hemolymph inhibitors of proteases from Aspergillus melleus and pancreatic alpha-chymotrypsin were found using 126 silkworm strains. Six inhibitors of the fungal protease were detected and eight of chymotrypsin; the distribution of inhibitors among Japanese, Chinese, and European races was investigated. Comparison of electrophoretic patterns from F1 hybrids and parents showed that the offspring produce inhibitors of both parental types. Segregation in F2 and backcrossing suggest that the expression of each inhibitor is controlled in most cases by a pair of alleles which are responsible for strong and null bands. Two bands of fungal protease inhibitors C and D were controlled by codominant alleles. These results suggest that polymorphism of hemolymph protease inhibitors in the silkworm would be a useful experimental system for the study of the genetic control of protease inhibitors.