Studies of postmeiotic chromosomes have been impeded by the thick exine of immature pollen grains. Chromosome staining of immature and adult pollen grains through conventional 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 be...

Heteropteran chromosomes are holokinetic; during mitosis, sister chromatids segregate parallel to each other but, during meiosis, kinetic activity is restricted to one pair of telomeric regions. This meiotic behaviour has been corroborated for all rod bivalents. For ring bivalents, we have previously proposed that one of the two chiasmata releases ¢rst, and a telokinetic activity is also achiev...

The objective of this study was to investigate the prognostic value of microvessel density (MVD) in uterine leiomyosarcoma (LMS) and peritumoral area (PA) as evaluated by CD31 expression and argyrophilic nucleolar organizer region (AgNOR) count in endothelial cells. Tissue specimens from 66 patients with uterine LMS were examined. There were no significant differences in the mean MVD between tu...

Ribosomal gene compensation and magnification that might be detected on a whole-plant basis was not found in maize. Plants monosomic for chromosome 6 (the NOR chromosome) were compared with monosomic-8 and monosomic-10 plants, disomic sibs, and parental lines. Assuming no rDNA compensation, monosomic-6 plants showed approximately the decrease expected in rRNA cistron number. Monosomic-8 had a n...

* The work reported has been done under USPHS grant GM 9912. t Career Scientist, Health Research Council of the City of New York. 1 Hungerford, D., J. Morphol., 97, 497 (1955). 2Beatty, R. A., Chromosoma, 8, 585 (1957). Levan, A., T. C. Hsu, and H. F. Stich, Hereditas, 48, 677 (1962). 4Ford, E. H. R., and D. H. M. Woollam, Exptl. Cell Res., 32, 320 (1963). 6 Crippa, M., Chromosoma, 15, 301 (196...

Rabbit antibodies to RNA polymerase I from a rat hepatoma have been used to localize the enzyme in a variety of cells at the light and electron microscopic level. In interphase cells the immunofluorescence pattern indicated that polymerase I is contained exclusively within the nucleolus. That this fluorescence, which appeared punctated rather than uniform, represented transcriptional complexes ...

The analysis of microsporogenesis in endogamous plants of popcorn (S5 to S7) showed several and distinct interchanges which involve the nucleolus organizer (chromosome 6). The detection of cells with interchanges was facilitated by the presence of two nucleoli of different sizes in contrast to normal ones with a single big nucleolus. Interchange points do not always seem to be at the same place...

Biogenesis of eukaryotic ribosomes occurs mainly in a specific subnuclear compartment, the nucleolus, and involves the coordinated assembly of ribosomal RNA and ribosomal proteins. Identification of amino acid sequences mediating nucleolar localization of ribosomal proteins may provide important clues to understand the early steps in ribosome biogenesis. Human ribosomal protein S9 (RPS9), known...