Abstract
To investigate the distance between Nd-s and Fib-L on the 14th chromosome of Bombyx mori, a three-point test cross involving U, Nd-s, and Fib-L was carried out. The crossover frequency between U and Fib-L or U and Nd-s was 24.6%. Crossingover between Fib-L and Nd-s was not observed. These results indicate that Fib-L is closely linked with Nd-s. In the fibroin slightly secreted into the lumen of the posterior silk gland of the Nd-s mutant silkworm, fibroin L-chain was not detectable. A possibility that the Nd-s phenotype is caused by a mutation in the L-chain gene, is discussed.
