Kazuhiro Fujikawa

Yolk of a “scanty vitellin” mutant, vit, of Bombyx mori is lacking in vitellin and 30 kDa proteins

A novel mutant named “scanty vitellin” (vit) of Bombyx mori, induced by N-methyl-N-nitrosourea, was analyzed for yolk proteins by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The ovary of vit/vit pupae was lacking in vitellin and the 30 kDa proteins that are yolk constituents synthesized outside the ovary. However, the vit/vit ovary had a normal amount of the egg-specific protein, a yolk component synthesized by the ovarian follicular epithelial cells. On the other hand, vitellogenin and the 30 kDa proteins, which are the precursors of yolk proteins, were abundant in the haemolymph of vit/vit female pupae. These results indicate that the mutant gene interferes with the uptake of the extraovarian yolk precursors into the oocyte.