State of the hypothalamo-hypophyseal neurosecretory system of rabbits in anaphylactic shock]

With the aid of morphometric and histochemical methods a study was made of the hypothalamo-hypophyseal neurosecretory system of rabbits in anaphylactic shock. The following occurred in rabbits which survived the shock: an enlargement of the perikarions and reduction in the size of the nuclei and nucleoli of the neurosecretory cells; the content of the neurosecretory substance was increased in the whole neurosecretory system. In rabbits which perished from shock the nuclei and the nucleoli of the neurosecretory cells diminished to a lesser extent, perikarion measurements remained unchanged and the content of the neurosecretory substance in the posterior lobe of the hypophysis fell. Thus, in the animals which survived the shock the processes of synthesis of the neurohormones by the neurosecretory cells were sharply activated, but the secretion of the neurohormones from the posterior lobe of the hypophysis was inhibited; in animals which perished from shock the activation of the hormone formation in the neurosecretory cells was less pronounced, but the processes of the secretion of the neurohormones from the posterior lobe were apparently intensified.     

A quantitative study of Ag-positive nucleolar segments revealed by silver staining in the interphase nuclei of trophoblast cells from the rat placental connective zone

A cytomorphological study was made of silver stained nucleoli in interphasic nuclei of trophoblast cells from the rat placenta connective zone, in addition to calculation of Ag-positive spherules in the nucleoli. The prevalent number of Ag-positive nucleolar spherules in the nuclei was 6, corresponding to the number of nucleolar organizers (NOR's) in the diploid chromosome complement of the rat. The mean number of Ag-positive spherules in the nucleoli progressively increase in the course of polyploidization from 2c to 32c; variability of the spherule number also increasing. The mean area of nucleoli is found to increase in proportion to the ploidy degree. A high correlation is found between the number of Ag-positive spherules and the area of nucleoli in the nucleus (r = 0.78). This appropriateness is exhibited at all the ploidy levels. The number of Ag-spherules and the area of nucleoli are found to depend slightly on the number of nucleoli. The possibility to use the number of Ag-positive spherules as a criterion of the activity of the NOR in interphasic nuclei is discussed.     

Number of nucleoli in various cell types of the mouse

The nucleoli of cells of the adult mouse were examined by staining with toluidine blue after removal of deoxyribonucleic acid from tissue sections by deoxyribonuclease treatment. The nuclei of each cell type examined contained one or more nucleoli. This was observed even in lymphocytes and neuroglia, although these cells have occasionally been described as anucleolated. In mature spermatids and spermatozoa, however, it was not possible to detect a nucleolus. The distribution of the number of nucleoli in many diploid cells exhibited a mode of two or three nucleoli per nucleus, and a range from 1 to 6 nucleoli. In presumedly diploid hepatic nuclei, the maximum number of nucleoli was six; but in presumedly tetraploid hepatic nuclei, it was 11. Thus, nearly twice as many nucleoli are present when the chromosome number is doubled. In view of this observation, it is suggested that six nucleolar organizers are present in the diploid chromosomal complement of the mouse. However, through failure of some nucleolar organizers or more probably through fusion of nucleoli, the number of these organelles in most nuclei is less than six.     

The number of nucleoli in peripheral blood lymphocytes of the Chernobyl accident liquidators]

The number of nucleoli in lymphocyte nuclei was compared in the peripheral blood of the Chernobyl liquidators and non-irradiated persons (control). The former was significantly distinguished from the latter (p < 0.01) by the parameter "the number of nucleoli in lymphocytes", mean numbers of nucleoli per nucleus in these being 1.18 and 1.12, respectively. The increased number of nucleoli in lymphocytes of the Chernobyl liquidators may be associated with cytogenetic radiation effects.     

Localization of phosphoprotein C23 to nucleolar structures and to the nucleolus organizer regions

After extraction of Novikoff hepatoma nucleoli with 4 M urea/3 M LiCl, phosphoprotein C23 was isolated by DEAE-cellulose and Bio-Rad AG3-X4A column chromatography. Immunization of rabbits with the highly purified protein C23 resulted in the production of a specific antibody as determined by Ouchterlony diffusion analysis. When the immunoperoxidase method was used to localize protein C23 in cells, it was found in ‘fibrillar centers’ (nucleolonemas) in nucleoli. Protein C23 was also demonstrated to be present on the nucleolus organizer regions (NORs) of metaphase chromosomes.     

Tissue and sex differences in the expression of nucleoli in mouse somatic cells.

In Mus musculus, the nucleolus organizer regions (NORs), or sites of ribosomal RNA-encoding genes, map at three chromosomal pairs. A silver procedure was modified to stain nucleoli in interphasic somatic cells of mice. The number of nucleoli per cell nucleus was determined in squashed cells of kidney, liver and pancreas obtained from male and female mice. In liver and pancreas cells the average number of nucleoli per cell was 4.84 and 4.66, respectively, and only 2.83 in kidney cells (p < 0.001). Less than 8% of pancreas cells and about 15% of liver cells contained more than 6 nucleoli per cell, which was the maximum expected number. In addition, the number of nucleoli per cell was significatively different (p < 0.01) when male and female liver or pancreas cells (not kidney cells) were compared. In both cases, female cells presented more nucleoli than the respective male cells. Assuming that the available NORs are the same, the variable number of nucleoli in the examined cell types would be the consequence of a tissue specific NOR regulation. The apparent influence of sex on this regulation is noted.     

Ultrastructure of the ring-shaped nucleoli in the hepatocytes of chick embryos]

The fine structure of ring-shaped nucleoli in hepatocytes of chick embryos at different terms of development was studied. Structural differences were shown between annular nucleoli and nucleoli with typical nucleolonemal organization. Ring-shaped nucleoli, as a rule, are devoid of nucleolonemal structure and their fibrillar component is reduced. The material which fills the central cavity always appears similar to the nucleoplasm in its structure. On the basis of serial sections, we propose that central cavity is isolated from the nucleoplasm. From the hypotonical treatment and EDTA staining application it is concluded that the central cavity of ring-shaped nucleoli contains DNP associated with the intranucleolar chromatin. The number of these nucleoli increased after the injection of a liver homogenate cytoplasmic fraction extracted from adult hen. The physiological significance of such nucleoli is discussed.     

RNA synthesis in the circular nucleoli of hepatocytes]

By analysis of serial sections it has been revealed that the so-called ring-like nucleoli of hepatocytes consist of a cavity with an amorphous contents surrounded by fibrillar and granular material. Such nucleoli are sometimes encountered in normal animals; the number of ring-like nucleoli increases considerably in chronic pathological process caused by repeated CCl4 injections. The capacity of RNA synthesis in the ring-like nucleoli was revealed by means of electron-microscopic autoradiography.     

Change in morphometric parameters in silver-stained nucleoli from hepatocytes of rats with liver cirrhosis and during rehabilitation from it]

Silver-stained nucleoli of rat hepatocytes were studied in norm, in liver cirrhosis produced by CCl4 poisoning and after cessation of the poisoning. Morphometric parameters of nucleoli were measured using a Videotest computer image analyser. Under cirrhosis the mean number of nucleoli per nucleus was determined to exceed their normal number by 1.27 times. The total volume of nucleoli in the nucleus also exceeded the normal level (by 1.15 times). 3 months after the end of CCl4-poisoning, these parameters decreased almost to normal values. A statistically significant correlation was revealed between the number of nucleoli and their total volume (0.881). Changes of the parameters also correlated with the total protein content in the hepatocytes. Possible reasons for this correlation are discussed. The ratio of the number of chromosomal NORs to the mean number of nucleoli in the nucleus is proposed to be used as a feature for comparative analysis of functional status of nucleoli in the nuclei of different ploidy and in cells of different animal species.     

Comparison of impact of EMCV replication on the nuclear apparatus of NIH 3T3 and HEp-2 cells

We have investigated differences between the actions of encephalomyocarditis virus (EMCV) on cytometric indices in cultured NIH 3T3 and HEp-2 cells, which are characterized by different levels of transformation. HEp-2 cells surviving 48 h after EMCV infection showed lower nuclear ploidy, reduced nuclear area, fewer nucleoli and a higher percentage of euploid cells. There was a significant increase of nucleolar/nuclear DNA 6-24 h after EMCV infection. However, EMCV had markedly different effects on NIH 3T3 cells: there was a consistent increase in population ploidy, but the average number of nucleoli and the number of euploid cells in the population remained constant. The nucleolar/nuclear DNA ratio was almost unchanged. These different viral effects might be explained by the contrasting levels of differentiation of the cultured cell lines. The number of nucleoli does not depend on the amount of nuclear DNA in either viral-infected or intact cells but on the euploidy-to-aneuploidy ratio. The ratio of the sums of the nucleolar perimeters to the nuclear perimeter increases linearly with the number of nucleoli per nucleus in both intact and virus-infected cells. In both cell lines, the amount of DNA per nucleolus decreases as the number of nucleoli increases.     

Silver staining of the nucleoli of pig embryonic kidney cells during the hyperactivation and inhibition of the synthesis of nucleolar RNA by UV microirradiation

Silver staining of the nucleoli in pig embryo kidney cells (PK) was studied during the cell cycle and also upon mature nucleoli modifications induced by UV microirradiation. During anaphase only four silver-stained granules were revealed in each daughter set of chromosomes in the four nucleolus-organizing regions (NORs). In the following 1-2 hours, the number of granules in the NORs rapidly increased up to 25-30 per nucleus. During the next 20-25 hours of the cell cycle, the number of silver-stained granules was slowly doubling as the nucleoli grew in size. UV microirradiation of one nucleolus in the nucleus with two nucleoli induced a profound degradation of the injured nucleolus and a compensatory hypertrophy of the intact one. Such nucleolar modifications were accompanied by redistribution of the silver-stained granules between the injured and non-injured nucleoli and by alterations in the levels of nucleolar RNA synthesis in the NORs. These data support a hypothesis that silver-stained proteins may be involved in the regulation of the nucleolar activity.     

Morphofunctional parameters of the nucleoli during development of polyploid nutrient cells of gonads from the snail Succinea lauta

Ag-protein contents, integral area and number of nucleoli in polyploidizing nuclei of gonadal nutrient cells of the snail Succinea lauta were estimated on the squashed preparations by means of morphometry and cytophotometry. 8 NORs of different size were found in haploid chromosome set of prophase spermatocytes (n = 22), but usually 1-2 nucleoli per 2c DNA are present in the nutrient cell nuclei. During genome multiplication from 2c to 32c-64c the Ag-proteins content of nucleoli increased proportionally to gene dosage, but irregularly: before 8c-level the coefficient of increasing in each endocycle was more than 2; from 8c to 16c it was 2; after 16c-level it usually decreased to 1.6-1.3. This dynamics reflects the effects of several factors on nucleolar activity: endomitotic polyploidy (gene dosage effect), differentiation and rhythmic functioning of tissue. Increasing indexes of integral area and the number of nucleoli during polyploidization were significantly less, than increasing index of Ag-proteins. The lag of nucleolar area for 4 cycles (2c-32c) was 32%, and number of nucleoli per diploid set decreased from 2 to 1. It may be due to NOR aggregation corresponding chromosomes. The photometric index of Ag-protein content more adequately reflects in the nucleolar activity during development and functioning of tissues.     

Laser microbeam irradiation of the juxtanucleolar region of prophase nucleolar chromosomes

To further understand the function of the nucleolus organizer (NO), especially as it relates to the mitotic cycle, we extended our previous irradiation studies to prophase chromosomes and nucleoli. The juxtanucleolar region of nucleolar chromosomes was irradiated with the argon laser microbeam, and cells were observed for several days. Nuclei with two nucleoli were generally chosen for irradiation because of their two clear secondary constrictions. Summarized results are as follows: (1) When either one or several juxtanucleolar sites of both or all nucleoli are irradiated, the mitotic process is blocked and the cells return to interphase. (2) When only the chromosomes associated with the largest nucleolus are irradiated, mitosis is also blocked. (3) When the juxtanucleolar regions of the smallest nucleolus are irradiated, the cells generally go into metaphase and complete division, but with a reduction in the number of resulting nucleoli. (4) When the nucleoli themselves are irradiated, mitosis proceeds and daughter nuclei show no reduction in nucleolar number. (5) When chromosomes are randomly irradiated at non-juxtanucleolar regions, the nucleus divides and produces the same number of nucleoli in each daughter nucleus as were present in the mother cell.     

Number of nucleoli as an index of the proliferative activity of cells in vitro

The number of nucleoli in cells is commonly insignificant (from 1 to 2). It may increase under numerous normal (regeneration) and pathological conditions. The data obtained suggest that activation of the nucleoli and the increase in the number cannot be specific characteristics of any pathological condition. Any disorders of tissue proliferative homeostasis will result in a change in the ratio of proliferative and resting cells and increase in the number of nucleoli.     

Localization of phosphoprotein C23 in nucleoli by immunological methods

Antiserum to a major phosphorylated nucleolar protein. C23 (MW 103000, pI 5.2) from Novikoff hepatoma was produced in rabbits. By immunodiffusion analysis, the antiserum produced precipitin bands and with various crude extracts of nucleoli, but not with extranucleolar or cytosol fractions. The specificity of the antibody was assessed using acid-urea polyacrylamide gel electropherograms of acid-soluble nucleolar proteins in which the separated proteins were transferred to nitrocellulose sheets. The purified antibody reacted predominantly with protein C23 as visualized by the immunoperoxidase procedure. By the indirect immunofluorescence technique, protein C23 was localized predominantly to nucleoli of Novikoff hepatoma or normal rat liver cells. In Novikoff hepatoma cells, traces of fluorescence were seen near the inner layer of the nuclear envelope. Additional narrow regions of fluorescence extended from the nucleoli into the extranucleolar areas of some Novikoff cells. The nucleolar areas of fluorescence were smaller but brighter in the normal liver than in Novikoff hepatoma, consistent with the small size of rat liver nucleoli. These data indicate that the major location of protein C23 is the nucleolus.     

Relation between the nuclei and the nucleoli during cell differentiation in roots of Vicia faba volumetric and cytochemical analysis

Summary The behaviour of the nuclei and the nucleoli of roots of Vicia faba during cell differentiation was studied quantitatively. The relations between these cell constituents and the polyploidy was analysed. The study was made on isolated nuclei and nucleoli and on plastic sections. A method for the isolation of nuclei and nucleoli of secondary roots fixed in formol was modified and another developed for material fixed in ethanol/acetic acid mixture. The volumetric investigation showed that the nuclear volume increases while the nucleolar decreases during cell differentiation. The mean number of nucleoli decreases. In Vicia faba there is no relation between the ploidy and the volume of nuclei and nucleoli; the protein synthesis rate has an influence on the size of these organelles. Quantitative investigation has shown the proportionality of dry weight, DNA, total protein, histone, protein-bound lysine and arginine content of the nuclei and their ploidy. The same experiments made on nucleoli showed linear relation between their content and volume. The concentration of analysed substances in constant in nucleoli.     

Prorocentrum属涡鞭毛虫核仁的观察

迄今未能在光学显微镜下观察到Prerocentrum属的涡鞭毛虫有核仁。本文作者用伊红的酒精溶液和用甲基缘—派若宁法染色,也未能在Prerocentrum micans和Proro-centrum cassubica的细胞核中显示出核仁来。但是在用专门为显示单细胞生物的核仁组织者区（NOR）而改进了的Ag—1法进行染色时,这两种涡鞭毛虫的核仁都会被染作鲜明的深褐色或深黑色,而身体的所有其他部份,包括染色体,全都不着色。染色适当时可以看出,实际上只是核仁的中央部分被染上色。在电镜下可见,此时所有的银粒全部是集中在核仁的纤维区中。染色的结果表明,Prorocentrum cassbica只有一个扁园形的小核仁,后者是贴附在核膜上,其NOR通常是作O形或C形。与P.cassubica不同,P.micans的核仁的数量变化很大,可以有一个至七个;其核仁的大小与形状同样也变化很大;其NOR的形状也复杂多变。发现P.micans的核仁数量与个体的生活状况有一定的关联:向老的培养液中加入等量的新的培养液一天以后,具有三个核仁的个体是最多的（占三分之一）,具有4—6个核仁的个体占28.5％,只有一个核仁的个体只占8.6％;加入新培养液三天后,具两个核仁的个体变成是最多的（占38.8％）,具4—6个核仁的个体降为占18.4％;加入新培养液一个月以后,只有一个核仁的个体是最多的（占3     

Morphology and index of nucleoli in malignant lymphomas

The significance of morphology and the number of lymphocyte nucleoli was evaluated by electronmicroscopic sections of malignant lymphomas. It was not only the number and the size of nucleoli which characterized malignant lymphomas differing in histological respect, but above all the different morphology of the nucleoli. The prognostic significance of the nucleolus can be illustrated, if malignant lymphomas of a low grade malignancy with a preponderance of micronucleoli and a low nucleolar index are compared with a significantly higher nucleolar index and markedly increased macronucleoli. These differences are further supplemented by additional morphological properties of nucleoli in malignant lymphomas.     

On the nucleoli of the dinoflagellate Prorocentrum

To date no nucleolus had been observed in Prorocentrum under the light microscope. The author failed to show the nucleoli of P. micans and P. cassubica with eosin in 70% alc or with methyl green-pyronin. But when these dinoflagellates were treated with an Ag-1 technique which had been improved for demonstrating NORs in unicellular organisms, nucleoli were stained dark brown or black, while all other parts showed no colour. When the materials were stained well, only the central part of the nucleolus was stained. Under the electron microscope, it was observed that all the silver grains were concentrated in the pars fibrosa of the nucleolus. P. cassubica had only one small oblate nucleolus attached to the nuclear envelope, with NOR usually in the shape of the letters O or C. P. micans had 1–7 nucleoli of various sizes and shapes with NORs in various complicated forms. The number of nucleoli bore a certain relationship to the living state of the dinoflagellate. One day after fresh medium was added, cells with 3 nucleoli were most common, and 28.5% of the individuals had 4–6 nucleoli. Cells having only one nucleolus accounted for 8.6%. 3 days after, cells with 2 nucleoli became dominant, and those with 4–6 decreased to 18.4%. After a month, cells with 1 nucleolus became most abundant, cells having 4 nucleoli decreased to 2.4%, and no cells had 5 or 6 nucleoli.