Abstract
Fibroin large subunit of a parent strain of silkworm was shown to give a single band on SDS-polyacrylamide gel electrophoresis. From the mobility of the band, fibroin large subunits from various parent strains of silkworm were classified into three groups, that is, fast (F), moderate (M), and slow (S) moving groups. On the other hand, the large subunit from the hybridized silkworm obtained by the cross between two parent strains of silkworm exhibited two bands having slightly different mobilities, which were the same to those of its parent silkworms, respectively. By carrying out F1 hybridization and backcrossing of the F1 with each of their parents, it was concluded that the alleles which control the fibroin phenotype are codominant each other.
