Nucleolar Coefficient Research Articles

Nucleolar size in lymphocytes and haemocytes of different species

The number of nucleoli in a cell and nucleolar area vary according to the cell. We compared nucleoli in mammalian circulating lymphocytes and insect circulating haemocytes. An increased nucleolar coefficient correlated with a lowered nucleoli size. The smaller nucleolar size in mammalian lymphocytes indicates a lower proteosynthetic cellular activity in both mammalian lymphocytes and insect haemocytes. Moreover, in insect haemocytes, the smaller size of the nucleoli may reflect a lowered potential to transform into another cell type.

Circadian rhythm of the lymphocyte nucleolar area

Nucleolar area and number were evaluated in human blood lymphocytes by scanning confocal laser microscopy. Remarkable stability of both the nucleolar coefficient and the proportion of lymphocytes with different nucleolar types at various times has been shown. Significant differences of mean nucleolar area were found during the circadian rhythm, with the maximum/minimum ratio ranging from 122–191%. With respect to the various courses of this rhythm for different human subjects, we suggest that circadian rhythm in the nucleoli area is exogenous.

Nucleolar coefficient of granulocyte precursors and granulocytes after visualization of nucleoli by two different methods

To clarify differences in the incidence and number of nucleoli in the granulopoietic lineage, these nuclear components were studied in human and rabbit granulocyte precursors and granulocytes after visualization by 2 widely employed cytochemical procedures, i.e. a procedure for the demonstration of RNA and the silver reaction for the demonstration of nucleolar silver stainable proteins (SSPs). In early stages of the granulocyte proliferating compartment, substantial differences were not found between specimens in which nucleoli were visualized by both procedures. However, in contrast to specimens stained with the silver reaction, the number of cells without nucleoli was substantially larger in advanced stages of granulocyte development in specimens stained for RNA. The number of nucleoli per cell as expressed by the nucleolar coefficient was generally larger in specimens stained with the silver reaction for nucleolar SSPs. These differences were significant starting with the stage of myelocytes. Moreover, in specimens stained with the silver reaction, most of human mature granulocytes did not contain nucleoli but nucleoli were present in all mature granulocytes of rabbits. Such differences were not observed in specimens stained for RNA in which most granulocytes were without RNA-containing nucleoli. Thus, the evaluation of the presence or absence of nucleoli in specimens depended on the visualization procedure. It is likely that in micronucleoli which are characteristic for terminal differentiation of the granulocytic lineage, RNA-containing structures may be lost or are below the detection limit of the light microscope. In addition, differences in the presence of nucleoli exist apparently between human and rabbit granulocytes in specimens stained for SSPs but not in those stained for RNA.

Incidence of nucleoli in erythroblasts in patients suffering from refractory anemia of myelodysplastic syndrome.

Nucleoli of erythroblasts have been studied in patients suffering from refractory anemia (RA) of myelodysplastic syndrome (MDS) and in control patients without a disturbed erythropoiesis in order to provide information on the incidence of nucleoli and micronucleoli in these cells. Nucleoli in erythroblasts were visualized by a simple cytochemical procedure for the demonstration of RNA which facilitated the visualization not only large nucleoli but also micronucleoli in advanced stages of the erythroblastic maturation. In control patients nucleoli were detected in all stages of erythroblastic development. In patients suffering from RA of MDS, a relatively large population of polychromatic and orthochromatic erythroblasts was characterized by a loss of nucleoli accompanied by the decreased incidence of micronucleoli characteristic of these cells. In contrast to control patients, in patients suffering from RA of MDS the number of nucleoli expressed by the values of the nucleolar coefficient of erythroblasts was smaller, particularly in both the early and terminal stages of erythroblastic development. Thus in patients with RA of MDS both the abnormal loss of nucleoli and decreased number of nucleoli in erythroblasts apparently represent and reflect a further abnormality of disturbed erythropoiesis.

Nucleolar coefficient and cytochemistry of human blood monocytes

Nucleoli in peripheral blood monocytes represented mostly by micronucleoli were investigated by means of cytochemical procedures for the demonstration of RNA, proteins of silver stained nucleolus organizer region, nucleophosmin, nucleolin and fibrillarin. The values of the nucleolar coefficient (mean number of nucleoli per cell) were influenced by the procedure used for the visualization of nucleoli. The differences in the values of the nucleolar coefficient of monocytes in one and the same person using above mentioned procedures suggested that micronucleoli in blood monocytes represent heterogeneous nuclear structures and only some of them possess both RNA and characteristic nucleolar proteins. Therefore, the procedures used for the visualization of nucleoli must be always taken into consideration when the values of the nucleolar coefficient are evaluated.

The silver-staining technique--a tool for characterizing lymphocyte populations in mammalian peripheral blood.

Nucleolus organizer regions (NORs) of the peripheral blood lymphocytes (PBL) of 9 mammalian species were analyzed by means of a silver-staining procedure. Species-specific NOR patterns were demonstrated. The number of NOR chromosomes was positively correlated with the nucleolar coefficient, and negatively correlated with the relative frequencies of uninucleolar cells in PBL interphase.

Nucleolar changes in maturing avian erythroblasts and erythrocytes.

Maturing erythroblasts and erythrocytes were studied in chickens and adult hens to provide more information on the presence and frequency of various nucleolar types in these cells. Nucleoli were present at all stages of erythroblastic and erythrocytic development except in the case of a few reticulocytes and the mature erythrocytes. The number of nucleoli per cell (expressed as the nucleolar coefficient) reached a maximum at the stage of the polychromatic erythroblast. Early erythroblasts were characterized by the presence of compact nucleoli or nucleoli with nucleolonemata. Rings shaped nucleoli and micronucleoli increased in number with further maturation. Cells of the final erythroblast stage (orthochromatic erythroblasts) contained mostly micronucleoli, and micronucleoli alone were present in reticulocytes and mature erythrocytes.

Interstrain differences in number, size and morphology of vesicular gland cell nucleoli in intact, castrated and testosterone-treated mice.

SUMMARY The nucleoli of vesicular gland cells from intact, castrated and testosterone-treated mice of strains A and C57Bl/10 were studied in smears specifically stained for the demonstration of RNA-containing structures using the light microscope. The size, number and morphology of vesicular gland cell nucleoli were found to be influenced by testosterone. After castration the size of the nucleoli and the percentage of nucleoli actively engaged in RNA synthesis decreased and the nucleolar coefficient (NC) increased. After testosterone treatment of intact as well as castrated animals the size of the nucleoli and the percentage of active nucleoli increased and the NC diminished. Interstrain differences were calculated for all values obtained. In C57Bl/10 animals the NC was always higher and the size of nucleoli, as well as the percentage of active nucleoli, were always lower than in strain A mice.

Nucleoli of human odontoblasts

Nucleoli of human odontoblasts were studied in smears stained with buffered toluidine blue at pH 5, for the demonstration of RNP-containing structures, including nucleoli. The odontoblasts were obtained from 5 premolars removed for orthodontic reasons. Three teeth were fully developed, in the two others the apical foramen was still widely open. One hundred odontoblasts were examined in each case. The results show that human odontoblasts possess 1–4 nucleoli, the mean nucleolar coefficient being 2.12. Out of all odontoblasts from fully developed teeth, 97–99 per cent contained ring-shaped nucleoli typical for the reversibly inhibited synthesis of the RNA. In two less developed teeth, 12–14 per cent out of all the odontoblasts contained nucleoli with nucleolonemas and/or compact nucleoli, which represent active nucleolar types in the production of RNA. The nuclear diameter of odontoblasts was 11.6 μm, the nucleolar diameter of ring-shaped nucleoli was 0.72 μm and that of active nucleoli 1.50 μm. The presence of ring-shaped nucleoli in differentiated odontoblasts suggests that these cells are in a reversible state which can be stimulated for production of new ribonucleoprotein structures and thus for the synthesis of proteins engaged in the formation of reparative dentine.

Genetic studies on mouse nucleoli

Significant intraspecies differences in the number of nucleoli of lymphocytes and liver cells of highly inbred mouse strains were observed. The values of nucleolar coefficient in F 1 hybrids fell between the values of the parental strains and the NC of the Bel animals were close to the parental line to which the back-cross was done. Preliminary results for ten wild mice are given.