Localization of RNA transcription sites in insect oocytes using microinjections of 5-bromouridine 5'-triphosphate.

In the present study we used 5-bromouridine 5'-triphosphate (BrUTP) microinjections to localize the transcription sites in oocytes of insects with different types of the ovarium structure: panoistic, meroistic polytrophic, and meroistic telotrophic. We found that in an insect with panoistic ovaries (Acheta domesticus), oocyte nuclei maintain their transcription activity during the long period of oocyte growth. In insects with meroistic ovaries (Tenebrio molitor and Panorpa communis), early oocyte chromosomes were found to be transcriptionally active, and some transcription activity still persist while the karyosphere, a compact structure formed by all condensed oocyte chromosomes, begins to develop. At the latest stages of karyosphere development, no anti-Br-RNA signal was registered in the karyosphere.