Biochemical Genetics of Bombyx mori (Silkworm)

Abstract

Publisher Summary This chapter presents a description of the biochemical genetics of Bombyx mori (Silkworm). The amylase functions in digestive and body fluids of many races of silkworms are controlled by two different genes. If the symbol Ae is used to represent a positive amylase in digestive fluid versus ae (negative amylase) and the symbol Be as a positive amylase in body fluid versus be (negative amylase), four types of gene combinations can be formed: Ae, Be; Ae, be; ae, Be; and ae, be. These four types were actually found in many races of silkworms and they also have been obtained artificially by means of mating. It is of interest that the two genes Ae and Be are located in close proximity in the same chromosome. The amylase activities differ according to the developmental period of the silkworm, even if an individual possessing the gene Ae or Be is taken into consideration. For example: if the amylase activity in digestive fluid is low in the early stage of the fifth-instar larva, it increases gradually to a peak in the middle stage and decreases again in the mature stage just before spinning. A similar phenomenon is observed in the amylase activity of the body fluid. Moreover, it has been ascertained that the gene Ae controls amylase not only in the digestive fluid, but also in the salivary gland, the crop, and other tissues or organs.