Isolation of the giant ramified nuclei of the posterior silk glands of Bombyx mori

The posterior silk glands of Bombyx mori are highly differentiated to produce fibroin, the specific cocoon protein. We have now succeeded in isolating the nuclei from the posterior silk gland cells, and a giant arborescent nucleus with a strikingly complicated morphology was observed. Biochemical analysis of the composition of the nuclei confirmed the existence of the four core histones in equimolar quantities and H1 histone. The isolated nuclei obtained here might be prerequisite for the study of the structure of the giant polyploid nucleus and its relation to the tissue-specific fibroin gene expression.