Abstract
Distribution and behavior of nucleic acids in the virus diseased cells were investigated on the midgut epithelium of silkworm larva, Bombyx mori L.
1. From the observations by means of supravital staining and histochemical method, it wasascertained that in the feeding time of the healthy larva RNA is generally distributed in the cytoplasm of cylindrical cell of the midgut, and DNA is generally rich and is constant in quantity.
2. It was observed that RNA is contained abundantly in several nucleoli in some of the nucleus of cylindrical cell. Among the heavily virus diseased cells the degenerated nuclei, which are narrow and irregular in shape, are sometimes observed and they are stained pale or remain unstained. This fact seems to show that the nucleus of diseased cell is deficient in DNA
3. In the newly hatched larvae and in the larvae shortly after ecdysis RNA is poor in quantity in midgut cells, and increases in quantity after feeding.
4. From the facts that RNA contents in the nucleus of cylindrical cell usually increase prior to the increase of the cytoplasmic RNA contents, it may be considered that there are close relation between the behaviors of RNA both in nucleus and cytoplasm.
5. In the early stage ef cytoplasmic polyhedrosis the cytoplasm of cylindrical cells begin to contain a large quantity of RNA, especially onthe outside of nuclear membrane, on the top of the cell and around the forming polyhedra. However, RNA decreases after completion of polyhedra formation.
6. RNA is contained abundantly in the posterior division of the midgut epithelium in the feeding larva, less in the anterior one and the least in the middle.
