Synthesis of Blood Protein by the Fat Body in the Silkworm, Bombyx mori L.

Abstract

THE concentration of protein in the blood of insects changes remarkably in the course of metamorphosis¹. I have shown that the concentration of blood protein increases after the middle period of the last larval instar² in the silkworm. It is not yet clear, however, what organ is concerned in the synthesis of blood protein in larval stage, although there are reports by Sissakian and Kuvaeva³ that blood itself synthesizes the protein in the pupal period of the silkworm. It was demonstrated that the content of protein in the fat body per individual remained almost constant after the middle period in the last larval instar, meanwhile activity to synthesize protein by the tissue was rather high in the same period^{4 5}. In order to elucidate the fate of the protein, the following experiments were carried out.