[RNA polymerase II and pre-mRNA splicing factors in diplotene oocyte nuclei of the giant African gastropod Achatina fulica].
The nuclear distribution of pre-mRNA splicing factors (snRNPs and SR-protein SC35) and unphosphorylated from of RNA polymerase II (Pol II) was studied using fluorescent and immunoelectron cytochemistry in diplotene oocytes of the gastropod Achatina fulica. Association of Pol II and splicing factors with oocyte nuclear structures was analysed. The antibodies against splicing factors and Pol II were shown to label perichromatin fibrils at the periphery of condensed chromatin blocks as well as those in interchromatin regions of nucleoplasm. The revealed character of distribution of snRNPs, SC35 protein, and Pol II, together with the decondensed chromatin and absence of karyosphere, enable us to suggest that oocyte chromosomes maintain their transcriptional activity at the diplotene stage of oogenesis. In A. fulica oocytes, sparse nuclear bodies (NBs) of a complex morphological structure were revealed. These NBs contain snRNPs rather than SC35 protein. NBs are associated with a fibrogranular material (FGM), which contains SC35 protein. No snRNPs were revealed in this material. Homology of A. fulica oocyte nuclear structures to Cajal bodies and interchromatin granule clusters is discussed.
Institute of Cytology RAS, St. Petersburg.
I S
IS
Stepanova
D S
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Bogoliubov
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D022003:Cell Nucleus Structures / Q000378:metabolism / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D008540:Meiosis; D008974:Mollusca / Q000378:metabolism* / Q000648:ultrastructure; D009687:Nuclear Proteins / Q000378:metabolism; D009865:Oocytes / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D012319:RNA Polymerase II / Q000378:metabolism* / Q000648:ultrastructure; D012322:RNA Precursors / Q000378:metabolism* / Q000648:ultrastructure; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000032:analysis / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear / Q000032:analysis / Q000378:metabolism
D000911:Antibodies, Monoclonal; D002843:Chromatin; D009687:Nuclear Proteins; D012322:RNA Precursors; D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D012319:RNA Polymerase II