Abstract
A mutant gene for retarded growth in Bombyx mori larvae has been discovered in a strain of w2 oew homozygotes. The skin of the retarded larvae at the 2nd and 3rd molting stages is reddish brown with a glossy appearance, and the body size is short like that of the narrow breast (nb) mutant. It was clear from the genetic study that the retarded glossy larvae are produced by heterozygosity of a dominant gene and that homozygotes die at the embryonic stage of blastokinesis. Linkage analysis showed that gene was linked with the nb gene located at 0.0 map unit on chromosome 19, and the recombination value between both genes was estimated at 23.3%. Furthermore, this mutant gene was confirmed to be allelic with the Gl gene located on the same chromosome and was designated as glossy retarded, GlR.
