Extrachromosomal DNA and its activity in RNA synthesis in oogonia and oocytes in the pupal ovary of Creophilus maxillosus (Staphylinidae, Coleoptera-Polyphaga).

The participation of extrachromosomal DNA (extra DNA) in RNA synthesis in the nuclei of terminal oogonial cells and oocytes in the pupal ovary of Creophilus maxillosus (Staphylinidae, Coleoptera) was examined by autoradiography. It was found that extra DNA in the nuclei of terminal oogonial cells, although predominantly in a condensed and heterochromatic state, produces numerous nucleoli and incorporates 3H-uridine during the interphases between successive differential divisions. Moreover, it was shown that extra DNA is active in RNA synthesis at the same stage of pupal development in which it is synthesized and accumulated, i.e. in the nuclei of terminal oogonial cells. As soon as the oocyte forms RNA synthesis ceases in the extrachromosomal DNA body cells showed that nucleolar material does not disappear during division but remains, at least partly, connected with the extra DNA body.