RESUMO
Here we investigated dynamic properties of the piNG-body, large perinuclear granule that was discovered previously in spermatocytes of Drosophila. The piNG-body contains ribonucleoprotein complexes involved in piRNA-silencing of genome repeats including transposons in premeiotic spermatocytes with aid of short piRNAs. Confocal microscopy of fixed and native preparations demonstrates that the piNG-body is mobile structure which does not occupy a stationary position near nuclear surface relative to chromosomal territories. FRAP-analysis reveals a high exchange rate of RNA helicase Vasa in the piNG-body and small perinuclear granules with the cytozol Vasa pool. Disruption of microtubule assembly of cytoskeleton does not affect to stability of the piNG-body and small granules. We suppose that the combination of piNG-body mobility and permanent molecular exchange of Vasa protein provides an efficient "scanning" of total volume of the cytoplasm of primary spermatocytes and timely recognition and destruction of unwanted transcripts of the repetitive elements of genome.
