OOGENESIS IN TURBELLARIANS OF THE GENUS GEOCENTROPHORA (LECITHOEPITHELIATA, PRORHYNCHIDAE) STUDIED BY LIGHT
AND ELECTRON MICROSCOPY. VI. IMMUNOGOLD LABELING LOCALIZATION OF SOME COMPONENTS ESSENTIAL FOR RNA POLYMERASE II
TRANSCRIPTION IN PERICHROMATIN REGIONS OF G. BALTICA OOCYTES
D. S. Bogolyubov
Institute of Cytology RAS, St. Petersburg;
e-mail: dmitr@mail.cytspb.rssi.ru
The female gonad (germovitellarium) of the lecithoepitheliate turbellarians has a special type of organization.
It consists of the peculiar follicles in which the oocytes develop surrounded by the yolk cells (vitellocytes).
While an oocyte grows, chromatin remains to be decondensed, and the karyosphere is not formed. Using immunogold
labeling microscopy we studied a distribution of RNA polymerase II, transcriptional coactivators CBP/p300, and
TATA-box binding protein in the perichromatin regions of Geocentrophora baltica oocytes. We found these
components of RNA polymerase II transcription to be associated with the perichromatin fibrils (PFs). We suggest that
the presence of numerous PFs in the perichromatin regions of G. baltica oocytes reflects the active state of
the nucleus during the unusual alimentary oogenesis of Lecithoepitheliata.
Key words: Platyhelminths, Lecithoepitheliata, oogenesis, oocyte nucleus, perichromatin fibrils,
transcription-associated proteins, immunogold labeling microscopy
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