The nucleoli in 4 regions of the root meristem of Zea mays have been examined and the time spent in each of the phases of the nucleolar cycle has been calculated from estimates of the rates of mitosis and the fraction of cycling cells in each region. The nucleolar cycles have been fitted to the mitotic cycles of cycling cells in the same regions. The timing of activity of the r-RNA genes differ...

The nucleolus is the site of ribosome biosynthesis, but is now known to have other functions as well. In the present study we have investigated how the distribution of signal recognition particle (SRP) RNA within the nucleolus relates to the known sites of ribosomal RNA synthesis, processing, and nascent ribosome assembly (i.e., the fibrillar centers, the dense fibrillar component (DFC), and th...

Nucleoli are the product of nucleolus organizing region activity (NOR) of specific chromosomes. Their basic function is to synthetise ribosomal RNA precursors and promote the maturation and assemblage of preribosomal RNP molecules. Information on rRNA-coding gene activity can be provided by the analysis of the number and size of nucleoli in the prophase of the first meiotic division. The morpho...

Protein phosphorylation and dephosphorylation has been recognized as an essential mechanism in the regulation of cellular metabolism and function in various tissues. Serine and threonine protein phosphatases (PP) are divided into four categories: PP1, PP2A, PP2B, and PP2C. At least four isoforms of PP1 catalytic subunit in rat, PP1α, PP1γ1, PP1γ2, and PP1δ, were isolated. In the present study, ...

Nucleostemin plays an essential role in maintaining the continuous proliferation of stem cells and cancer cells. The movement of nucleostemin between the nucleolus and the nucleoplasm provides a dynamic way to partition the nucleostemin protein between these two compartments. Here, we show that nucleostemin contains two nucleolus-targeting regions, the basic and the GTP-binding domains, that ex...

studies of postmeiotic chromosomes have been impeded by the thick exine of immature pollen grains. chromosome staining of immature and adult pollen grains through conven-tional acetocarmine procedure is tedious and often leads to unsatisfactory results. an acetocarmine stain, used in conjugation with carnoy’s solution as fixative for 72 hrs or until the chlorophyll-containing tissues of spike b...