Haemolymph control of sericin gene expression studied by organ transplantation.

A factor that affects synthesis of sericin mRNAs of Bombyx mori was analyzed by organ transplantation and allatectomy. When silk glands of the third instar larvae were transplanted into the abdomen of fifth instar larvae, substantial amounts of sericin mRNAs were induced in the transplant. The induced sericin gene activity was suppressed upon re-transplantation into the abdomen of fourth instar larvae and induced again when the second hosts grew up to fifth instar larvae. An allatectomy performed on fourth instar larvae promoted production of these mRNAs, suggesting that the synthesis of sericin mRNA is regulated by the titer of juvenile hormone.