[Cajal bodies in nuclei of oocytes from the scorpion fly Panorpa communis]

The absence of nucleoli and rRNA synthesis in oocyte nuclei of the scorpion fly, Panorpa communis, was demonstrated using hybridization in situ. The immunocytochemical characteristics of a single large nuclear body of P. communis oocytes has been done which enabled us to recognize this structure as a Cajal body (CB). A marker of CBs coilin was detected in CBs of P. communis oocytes in addition to Sm-epitope of small nuclear RNPs (snRNPs), trimethylguanosine cap of snRNAs, and non-snRNP splicing factor, SC35. Besides, inactive hyperphosphorylated and nonphosphorylated forms of RNA polymerase II were also found in CBs. We put forward a suposition on possible roles of CBs in P. communis oocytes. On the one hand, CBs take part in the storage of RNA transcription and processing components to be used later during embryogenesis. On the other hand, they provide the primary assembly and redistribution of pre-mRNA transcription and processing components of the oocyte itself.