Activity of nucleoli in cells of different type in early embryogenesis of Pinus sylvestris L

Early embryogeny of Pinus silvestris L. is characterized by suspensory system formation consisting of several cell generation formed by apical cell fissions. A comparative analysis was made of quantitative characteristics of nucleoli of two functionally different cell types: the apical cells of meristematic nature, and specialized cells resulting from mitotic cycle of suspensory cells. We determined the number of nucleoli and their diameters, the character of distribution and variability of these indices for cells of different types. It has been shown that in the cell cycle, changes of qualitative parameters of nucleoli in cells of secondary suspensors are most dynamic. A conclusion is made that in P. sylvestris L. early embryogeny differences in nucleolar activity and mechanisms of its regulation occur in suspensory cells of different generations. On the basis of differences in nucleolar activity observed in suspensory cells of the same generation, certain mechanisms of competition between cleavage polyembryos of this species are suggested.     

ISOLATION AND PROPERTIES OF LIVER CELL NUCLEOLI

1. The significance of the term nucleolus has been discussed. 2. A detailed method for the isolation of nucleoli from already isolated rat or cat liver nuclei has been presented. 3. The presence of DNA in isolated liver cell nucleoli has been indicated by histochemical methods. 4. The percentages of DNA and RNA in the isolated nucleoli have been determined by chemical analysis. 5. The specific activities of aldolase, arginase, and catalase have been determined for two subnuclear fractions and for the isolated nucleoli of rat and cat liver, and the relative amounts of these enzymes in the same subnuclear fractions and nucleoli of rat liver have been measured. 6. The significance of the above findings has been discussed and consideration has been given to what types of isolated nuclei might best serve as starting material for the isolation of nucleoli. 7. A new hypothesis has been presented that nucleoli of the liver cell type may function primarily in furnishing (directly or indirectly) templates for the synthesis of the particular enzymes that must govern the chemistry of mitosis.     

Morphofunctional features of the nucleoli in glandular hyperplasia and endometrial cancer]

The morphofunctional peculiarities of epithelial cells nucleoli in patients with glandular hyperplasia and endometrial cancer has been studied on the cytological smears from endometrium stained with silver nitrate were investigated. The patterns of nucleolonemic nucleoli content and high activity of nucleolar organizers in cancer of corpus uteri are revealed.     

Correlation of nucleolar activity and nucleolar vacuolation in plant cells

In root meristematic cells nucleolar structure varies with the cell cycle. Apart from normal meristematic nucleoli one finds nucleoli with a big central vacuole surrounded by a loose cortex with individual fibrillar centres [22] clearly visible within it. There are also intermediate structures between both nucleolar types. In Pisum sativum nuclear tissue, the structure of the vacuolated nucleoli is similar and appears in periods of high metabolic activity during megasporogenesis. In both tissues, vacuolated nucleoli incorporate tritiated uridine more actively than 'normal' nucleoli. In this work the structure of spontaneous nucleolar vacuoles is compared with that induced by drugs such as cordycepin, and FUdR. The vacuolated nucleolus with its increased surface corresponds to a transient structure which not only shows higher metabolic activity but also supplies a storing and/or transporting mechanism for nucleolar products.     

Cytogenetic features of the differential diagnosis of lymphoid thymomas, small-cell non-Hodgkin lymphomas and undifferentiated small cell lung carcinoma

The predominance of compact and nucleolonemic types of nucleoli in undifferentiated small cell carcinoma of lung, the prevalence of micronucleoli and ring-shaped types of nucleoli in lymphoid thymoma and the increase of the level of micronucleoli in small cell non-Hodgkin's lymphoma have been established.     

Peculiarities of mitosis and nucleolar characteristics of the birch plantlets under antropogenous pollution

A study was made of some cytogenetic characteristics (mitotic activity, the level and spectrum of pathological mitosis, nucleolar features in root tip cells) in birch plantlets. The seeds were collected in four districts of Voronezh and in the ecologically clean territory. The index of mitotic activity has a considerable resistance to anthropogenous pollution. In the experimental areas, the level and spectrum of pathological mitosis increase. In contaminated areas we observed changes of nucleolar characteristics (the increased surface area of nucleoli and their higher number in cells, the increased number of cells with highly active types of nucleoli, the appearance of residual nucleoli). These changes can be considered as possible mechanisms of adaptation to stress due to antropogenous pollution. It is suggested that the use of such indices as single nucleolar surface area or the level of pathological mitosis may be perspective for cytogenetic monitoring of the environment, and for prognostification of environmental conditions suitable or unsuitable for the human health.     

Morphofunctional characteristics of neurosecretory cells of the supraoptic nucleus of rats with parathyroprival hypocalcemia]

Humori-positive neurosecretory cells of the supraoptic nucleus of the hypothalamus have been investigated during various time of parathyroprival hypocalcemia after extirpation of the parathyroid glands. Contents of total and ionized calcium, phosphorus in blood serum have been estimated. Volume of nuclei and nucleoli has been measured. In 5 days functional activity of the supraoptic nucleus increases (lightly stained cells predominate, volume of the nuclei and nucleoli increases). In subsequent 15-30 days its activity decreases (increase in amount of dark-stained cells, nucleolar volume decreases). In 60 days there is a tendency to restoration of neurosecretion.     

Citric acid-sonication method for the isolation of nucleoli

A simple method has been developed for the isolation of nucleoli of Novikoff hepatoma ascites cells from nuclei prepared by the citric acid procedure. The purity of the nucleoli is equivalent to that of nucleoli isolated by the sucrose-Ca²⁺ method [3, 16]. Chemical compositions and RNA profiles were virtually identical to those reported earlier [3, 10, 16]. In addition, the nucleoli isolated by this method had no ribonuclease activity. The average yield of 64% is higher than that of the method employing sucrose and Ca²⁺. This method has been successful both for cells obtained directly from ascites fluid and for cells incubated in minimal Eagle's medium for 16 h. For the latter condition, the sucrose-Ca²⁺ method did not yield satisfactory results [13].     

Studies on nucleoli in rosetting T and B lymphocytes of the human peripheral blood

The incidence of various nucleolar types was studied in human rosetting lymphocytes to provide an information on nucleolar types present in T and B lymphocytes of the peripheral blood. The results clearly demonstrate that both T and B lymphocytes of the peripheral blood mostly contain ring shaped nucleoli ("resting nucleoli") and less frequently other nucleolar types such as nucleoli with nucleolonemata or compact nucleoli ("active nucleoli") and micronucleoli ("inactive nucleoli"). Since all known nucleolar types and particularly micronucleoli may be observed in both T and B lymphocytes, nucleoli in these cells cannot indicate the type or origin of these cells but simply the state of the nucleolar RNA synthesis.     

Correlative morphological and cytochemical observations on the nucleoli and nuclear bodies during avian oogenesis.

A correlative morphological and cytochemical study has been made of the nucleoli and nuclear bodies in the growing oocytes of the crow (Corvus splendens) and common myna (Acridotheres tristis). The nucleoli show morphological and cytochemical changes during oocyte growth, which are described in detail. In young oocytes at diplotene stage, two to six nucleoli, which are attached to condensed diplotene chromosomes, show RNA, lysine-rich histones and some non-histones, the proteins contain S-S and SH groups. In subsequent stages of oocyte growth, the cortex of nucleolus also develops arginine-rich histones whereas the medulla shows lysine-rich histones. The significance of both morphological and cytochemical changes of nucleoli has been discussed in relation to oocyte growth. Seven types of nuclear bodies are described. They are composed of proteins and carbohydrates. Their shape, size and structure vary during different stages of oocyte growth. Finally, their material is transported into the ooplasm.     

Number, volume and size distribution of nucleoli in rat neurosecretory cells with suppressed and stimulated secretion

The nucleoli in the neurons of the supraoptic nucleus were investigated in the rat. This was performed after the secretion of vasopressin had been suppressed by water load, after the secretion had been stimulated by water deprival and in normal rats which had water ad libitum. The cells with high secretory activity had large single nucleoli. The cells with low secretory activity had less nucleolar volume, and a substantial part of the cells contained two nucleoli.     

Ultrastructure and functions of ring-shaped nucleoli, fibrillar centers and nucleolar vacuoles

Evidence on the ultrastructure of ring-shaped nucleoli in several cell types is reviewed. Detailed attention is paid to these structures in PEK culture cells after the action of actinomycin D, to infiltrating carcinomas of human breast after different degrees of malignization, and to hepatocytes of 11 day old chick embryos. On the basis of our own and literary data, the ring-shaped nucleoli are classified into two groups: 1) those with centrally located fibrillar centres, and 2) those containing large central vacuole. Connections of fibrillar centres with the nucleolus organizer regions in the interphase nucleolus and mitotic chromosomes are considered in detail. Literary and our own data on the genesis and functional activity of ring-shaped nucleoli with the central vacuole, as well as nucleoli with different degrees of vacuolization (vacuolized nucleoli) are specially analyzed. Cellular function, properties and significance of the central vacuole in low differentiated cells are discussed.     

Characteristics of ribosomal RNA synthesis in the blood lymphocytes of chronic lympholeukemia patients

A study was made of the number of silver grains over the nucleoli and of the content of ribosomes in the lymphocyte cytoplasm for six healthy persons and for 20 patients with chronic lymphatic leukemia. Besides ratios of compact, nucleolonemic and ring types of nucleoli were evaluated in addition to counts of the specific radioactivity of mature 28S rRNA in lymphocytes. In the majority of cases examined, cells with 1 or 2 nucleoli of compact and nucleolonemic types were seen dominating. The number of silver grains over the nucleoli in the control healthy persons did not differ from that in patients who did not receive any treatment, which contrasted with high value grain counts in the treated patients. The lymphocyte ribosome contents varied within the normal and decreased values in both the patient groups. The specific radioactivity in 28S rRNA leukemic lymphocytes was significantly lower in groups of patients with low ribosome contents than in those with the normal ones. The data suggest that in the leukemic cells with a high or unaltered activity of ribosome cistrons and low ribosome levels rRNA processing is broken.     

Nucleolar variations during the ontogenesis of diploid and tetraploid cyprinid species

Studying the quantitative characteristics of nucleoli in cells of several cyprinid species ( Cyprinus carpio, Carassius auratus gibelio, Carassius auratus auratus, Aristichthys nobilis, Ctenopharyngodon idella, Hypophthalmichthys molitrix ) has shown a definite programme that controls genetically changes in the nucleolar characteristics during fish ontogenesis. In embryogenesis, the nucleolar activity, which has been estimated from the number and size of nucleoli, decreased; this process was realized dissimilarly in diploid and tetraploid cells. A correlation between the nucleolar characteristics and the body mass of juvenile fish was found. Parameters of the nucleolar activity were closely related to the physiological state of mature organisms and featured tissue specificity, rhythmicity, and high level of heritability.