抄録
DNA content in the whole body of Bombyx mori remained almost unchanges for the first 2-3 days after larval-pupal ecdysis and then decreased continuously throughout subsequent development. RNA content in the whole body decreased slightly for the first 2-3 days, increased up to day 6-7 of the development and again decreased thereafter. RNA/DNA ratio in the whole body rose constantly with an initial lag period and reached a maximum 2-3 days before adult emergence. The ratio then fell slightly. A cross relationship was observed between the loss of wet weight from the fat body and the gain in the ovary and carcass, supporting that the fat body functions as a storage tissue of reserve materials. Meconium production was more prominent in males than in females, possibly reflecting a weak demand to nitrogeneous compound for the gonad growth in the males.Both the content and the concentration of nucleic acids in several tissues changes considerably in the course of pupal-adult development, reflecting histolysis and histogenesis. The most characteristic changes were found in DNA of the degenerating silkgland and the midgut. Both the tissues in histolysis showed conspicuously high levels in DNA concentration, resulting in minima of RNA/DNA ratio, which indicates that DNA decrement was not synchronized with the decrease in tissue weight and the RNA loss in these tissues. It is suspected that such delayed decrement of DNA may be attributable to the rigidity of DNA-histone complex in the chromatin.
