2005 Volume 74 Issue 2+3 Pages 53-57
In 1995, a new brown egg mutant was discovered in one race of the domestic silkworm, Bombyx mori, which has been held at the National Institute of Agrobiological Science. The mutant resources were maintained in recessive genes and showed typical maternal inheritance which had been reported in the mutant, b-1. Complementation tests revealed that the mutant gene shared an allele of the well-described brown egg mutant, b-2. Hence, the newly discovered gene was named b-2s , and mapped on the 6th chromosome (29.1 cM). On the other hand, in the reciprocal cross experiment between b-2s and b-2na, F1 and F2 moths produced only brown eggs, while F3 moths produced normal egg color batches separated from the mutant batches. The segregation of the normal eggs may be derived from a recombination of the genes. The recombination rate of between b-2s and b-2na was calculated at approximately 1.85 cM.
