RESUMEN
Specificity of regulation of genes expression at the transcriptional and posttranscriptional levels is typical for spermatogenesis in Drosophila and mammals, including humans. It becomes apparent in the existence of testis specific NXF (nuclear export factor). We have shown that the Dm NXF1 (SBR) protein is present in considerable amounts at all stages of the spermatogenesis. Using the antibody for the C-terminal part of the Dm NXF1 protein we have shown the cytoplasmic localization of the Dm NXF1 protein at early stages of the spermatogenesis. This protein is localized in the nuclear envelope at the stage of rounded spermatid. During the period of elongation, the Dm NXF1 protein has a polar localization, and is located only along one side of the extended spermatid nucleus. At the stage of spermatid individualization, this protein in the form of large cytoplasmic granules moves to the tail of the spermatozoon.
