Space-time characteristics of DNA synthesis in mesothelial cells of the rat after surgery at different times of the day

Differences in the DNA synthesis dynamics (according to the label index-LI) and those of mitotic activity (MA) in the mesothelium of the rat parietal peritoneum have been studied after burn performed at 9 AM, or at 9 PM. A number of peculiarities in the regeneration character are dependent on the day time of the operation. Immediately after the PM operation inhibition of both DNA synthesis and MA is manifected more distinctly and lasts longer, but then activation of the processes occurs more intensively the LI and MA values are greater than after the AM operation. Drop in the LI and MA takes place also with a greater rate after the PM operation, but their absolute values are kept higher up to the 7th day. Despite the fact that the reaction after the AM operation is comparatively weak, it is more rhythmical: against the background of general dynamics the fluctuations are more distinctly manifested, their period is nearly similar to the circadian. Increase in the proliferative activity is accompanied with a widening of the zone, where the dividing cells are situated. After the PM operation the wavy character of the process is expressed only in the pattern of the spatial organization of the regenerating mesothelium: nearly at regular intervals the area of the MA distribution becomes widen or narrow in turn. Thus, the LI and MA dynamics in the regenerating mesothelium depend on the circadian phase of the organism's state at the moment of the operation.     

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.     

Morpho-functional parameters of nucleoli in polyploid mucous and albumen cells of salivary gland in the snail Succinea lauta

Variation of some characteristics of nucleoli of polyploid mucous and albumen cells was examined in salivary glands of the snail Succinea lauta. The number, total area and Ag-protein content of nucleoli, and DNA content in each nucleus were estimated on squashed preparations incubated with AgNO3, decolorized and then Feulgen stained. The ultrastructure of nucleoli was studied by electron microscopy. Differentiated mucous cells had 4c-8c-16c-32c nuclei; albumen cells had 8c-16c-32c-64c-128c nuclei. The ultrastructure of nucleoli of the two cell types was essentially the same. Normally, a large fibrous to granular zone was observed in the nucleoli, without a clear distinction between fibrous and granular components. At the same time, aggregations of granular matter could be discerned at the periphery of nucleoli. No fibrous centers were observed. Occassionally, nucleolonema-like structures occurred. Normally each nucleolus contacted several chromosomes. On squashed preparations, the least size of nucleoli was 2-3 microm, and the largest size amounted to 14 microm in mucous cells, and to 50-80 microm in albumen cells. The number of nucleoli rose from 1-2 in tetraploid nuclei to 2-3 in 32c-nuclei, and to 5-7 in 128c-nuclei. The disparity between the ploidy levels of nuclei and the numbers of nucleoli may be due, presumably, to aggregation of chromosome NORs. The Ag-protein content in the nucleoli, and the total nucleolar area displayed a strong mutual correlation. Both parameters differed significantly by 1.5-2.2 times in mucous and albumen cells of the same ploidy level. Thus, in albumen and mucous cells the total Ag-protein content in octaploid nuclei was 3.3 and 2.2 relative units (r. u.), respectively. In 16c- and 32c-nuclei of albumen cells, it was 7.6 and 15.1 r. u.; and in the same nuclei of mucous cells--3.8 and 6.8 r. u., respectively. On the whole, in albumen cells, in the course of 4 endocycles (4c-128c), the total Ag-protein content increased by 17 times. Therefore, the mean multiplication factor for this parameter was found to be 2.05 per endocycle. In mucous cells, in the course of 3 endocycles (4c-32c), the total Ag-protein content increased by 5.2 times against 8 times expected, with the mean multiplication factor equal to 1.75 per endocycle. Thus, in the course of polyploidization of albumen and mucous cell nuclei, the gene dosage effect was fully pronounced in the former, and only partly in the latter. This differtence is due obviously to peculiarities of differentiation of the two cell types, in particular, to differences in the number of activated ribosomal genes.     

Rhythmicity of the activity of the supraoptic and paraventricular nuclei of the hypothalamus of the C57Bl mouse

Rhythmical changes in the activity of the neurosecretory processes have been compared in the supraoptic (SON) and paraventricular (PVN) nuclei in the C57Bl mice hypothalamus during vernal equinox. Parts of the neurosecretory cells, being at stages of synthesis, excretion and accumulation of secrete, volumes of the cell nuclei and nucleoli survey as criteria of their activity. Similar feature for the rhythmic of both nuclei studied is the highest activation of the processes during day time, when mice are resting; this is demonstrated as the maximal amount of actively synthesizing cells, maximal volumes of the cell nuclei and nucleoli. The peculiarities of the rhythmic display in the activity is manifested as a greater ability of the SON cells to accumulate neurosecrete. The accumulation of the secretory material in the SON cells precedes to the period of its maximal activity (1-7 PM) characterized: by making the cells free from the secrete and by a maximal increasing the volume of the nucleoli. In the PVN intensified display of the activity is noted at early hours of the day, and the amount of the cells not containing the secrete--at 6 PM. Lack of the neurosecrete accumulation in the PVN cells speaks in favour of more steady than in the SON cells excretion of the secrete. This demonstrates a more even maintenance of neurohormones concentration in the organism.     

Nuclear Bodies of Stage 6 Oocytes ofRana temporariaContain Nucleolar and Coiled Body Proteins

The genetically inactive stage 6 oocyte nuclei ofRana temporariacontain certain nuclear bodies that label with nucleolus-specific and coiled body (CB)-specific antibodies. We designate them multicomponent bodies (MCBs) to reflect their mixed composition. Morphologically, each MCB contains five distinct zones: zone I composed of electron-dense fibrils similar to the dense fibrillar component (DFC) of the typical eukaryotic nucleoli; zone II resembled the fibrillar material of the inactive agranular nucleoli of stage 6 oocytes; zone III consisted of fine filamentous material corresponding to the fibrillar center (FC) of lower electron density seen in the typical nucleoli; and zones IV and V contained packed coiled threads typical of CBs. Of these, zone IV was seen in the interior of MCBs and contained tightly packed coiled threads (20 nm thick), while zone V occurred at the periphery and consisted of similar threads but loosely packed and electron dense. The material of both zones IV and V resembled that of CBs. To determine the composition of these zones, we extracted oocytes with a buffer that removes chromatin and most of the soluble proteins and processed them for immunogold labeling with a variety of antibodies. Anti-p80 coilin antibody predominantly labeled zone IV and, to a lesser extent, zone V. Anti-snRNP antibody also showed a similar labeling pattern. Anti-fibrillarin antibody predominantly labeled zone I and to a lesser extent zones IV and V. Anti-B23 antibody labeled all zones. These observations suggest that MCBs contain both nucleolar and CB material. We postulate that MCBs represent storage structures which provide material needed for the early stage of embryogenesis. The demonstration of MCBs further supports the close interrelationship between nucleoli and CBs.     

Cytology of experimental mesotheliomas induced with crocidolite asbestos

The cellular features of 12 pleural and 5 peritoneal effusions, derived from experimental mesotheliomas induced with crocidolite asbestos in white rats, are described. The fluids were obtained 11 to 18 months after the introduction of asbestos into the body cavity. The morphologic characteristics of the cytoplasm, nuclei and nucleoli in the neoplastic mesothelial cells were studied using the Pappenheim, periodic acid-Schiff and Smetana stains. Nearly all effusions examined contained numerous normal and abnormal mitoses. Cell configurations suggestive of amitotic divisions were also observed. The study of the morphologic features of mesothelial cells in effusions in experimental asbestos-induced mesotheliomas may contribute to the understanding of the neoplastic transformation of the mesothelium.     

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.     

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.     

Zones of sexual dimorphism in the cortico-medial group of nuclei of the amygdaloid complex

With the aim to reveal sex demorphic zones by means of caryometry, 22 zones of the cortico-medial group of the amygdaloid complex (AC) nuclei have been investigated in rats (15 males and 10 females). Per each zone investigated 200 cellular nuclei are measured. Parameters characterizing distribution of the neuronal nuclei volumes in the zones studied are calculated, influence of the sex factor on the nuclear size are revealed by means of variance analysis. Basing on the results of the investigation, a complete idea on topography of the sex demorphic zones in the territory of the cortico-medial group of the AC nuclei is given. These zones are predominantly localized in the anterior and posterior parts of the AC, situating mainly in the rostral and caudal areas of the medial and cortical nuclei. The results demonstrate existence of the rostro-caudal gradient in the structural-functional organization of the cortico-medial group of the AC nuclei and prove that before suggested division of the AC into anterior, central and posterior parts is correct. It is possible to suppose that the cause of accumulated and still accumulating in the literature contradictions on functional differentiation of the AC is lack of registration of sex differences and of the rostro-caudal gradient in organization of this cerebral formation.     

The dynamics of postmitotic reassembly of the nucleolus

Mammalian cell nucleoli disassemble at the onset of M-phase and reassemble during telophase. Recent studies showed that partially processed preribosomal RNA (pre-rRNA) is preserved in association with processing components in the perichromosomal regions (PRs) and in particles called nucleolus-derived foci (NDF) during mitosis. Here, the dynamics of nucleolar reassembly were examined for the first time in living cells expressing fusions of the processing-related proteins fibrillarin, nucleolin, or B23 with green fluorescent protein (GFP). During telophase the NDF disappeared with a concomitant appearance of material in the reforming nuclei. Prenucleolar bodies (PNBs) appeared in nuclei in early telophase and gradually disappeared as nucleoli formed, strongly suggesting the transfer of PNB components to newly forming nucleoli. Fluorescence recovery after photobleaching (FRAP) showed that fibrillarin-GFP reassociates with the NDF and PNBs at rapid and similar rates. The reentry of processing complexes into telophase nuclei is suggested by the presence of pre-rRNA sequences in PNBs. Entry of specific proteins into the nucleolus approximately correlated with the timing of processing events. The mitotically preserved processing complexes may be essential for regulating the distribution of components to reassembling daughter cell nucleoli.     

Nucleolar size in parallel with ribosomal RNA synthesis at diapause termination in the eggs of Bombyx mori

The eggs of Bombyx mori, both in diapause and nondiapause, were subjected to cytological examination of nucleoli and measurement of RNA precursor incorporation (2 hours) into ribosomal RNA. In diapause eggs, the nucleoli were very small and the rate of ribosomal RNA synthesis was the lowest of the samples tested. Most cells in diapause possessed nuclei with one nucleolus. In contrast, the eggs activated from diapause by long chilling attained the largest size of nucleoli and the highest rate of ribosomal RNA synthesis. A significant proportion of the cell nuclei still had only one nucleolus at this stage. Three days after activation, the eggs exhibited intermediate levels in both the size of nucleoli and the rate of ribosomal RNA synthesis. At this stage, about half of the egg cell nuclei had two nucleoli.This paper is dedicated with respect and admiration to Professor D.F. Poulson, who has made many significant contributions on the genetics, embryology and cytology of Drosophila as well as other Insecta, in commemoration of his retirement     

自然灾害胁迫下区域生态脆弱性动态——以四川省清平乡为例

利用四川省绵竹市清平乡2008年“5·12”汶川地震后航空遥感图像和2010年“8·13”特大山洪泥石流灾后无人机低空遥感图像,结合清平乡2006年土地利用现状图、1∶5万地形图与野外调查资料,对清平乡生态脆弱性进行评估和分析.结果表明：清平乡2010年“8·13”特大山洪泥石流灾后生态不脆弱、一般脆弱、中度脆弱、脆弱和极脆弱区的面积比例分别为1.9%、7.9%、18.7%、23.0%和48.5%,生态极脆弱和生态脆弱区总面积达238.45 km²,占全乡总面积的71.5%,清平乡生态环境整体上已经非常脆弱;受这两次特大自然灾害的胁迫作用,清平乡生态脆弱性明显增强,生态脆弱和极脆弱区面积比“5·12”汶川地震前增加12.4%,生态极脆弱区面积是“5·12”汶川地震前面积的1.67倍;清平乡生态脆弱性动态演化主要表现为生态脆弱性等级由脆弱演化为极脆弱.复杂的地形条件是导致清平乡生态脆弱的关键因素.     

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.     

Activities of DNA polymerases and RNA polymerases detected in situ in growing and differentiating cells of root cortex.

Activities of DNA polymerases and RNA polymerases were studied by autoradiographic methods in growing and differentiating root cortex cells of Zea mays - a species in which endomitosis occurs - and Tulipa kaufmanniana - in which this process does not occur. In Tulipa kaufmanniana, the highest activity of DNA polymerase appears in the nuclei of meristematic zone during the S phase of the cell cycle. In Zea mays, endomitotic replication of DNA occurs in all growth and differentiation zones and the activity of DNA polymerase in the nuclei is similar to that in the meristematic zone. In both species, nuclear RNA synthesis, measured with 3H uridine incorporation, is highest in the meristematic zone and declines steadily with development. Activity of nuclear RNA polymerase is present in all developmental zones in both species and is similar to that in the meristematic zone. 3H uridine incorporation into nucleoli decreases markedly in both species, whereas the activity of nucleolar RNA polymerase remains at a high level in all root segments in Zea mays and decreases slightly in Tulipa kaufmanniana. It is argued that the differences between the incorporation of 3H uridine and that or 3H UMP may be caused by a reduction of the pool of endogenous ribonucleoside triphosphates. Marked activities of DNA polymerase and RNA polymerase in cytoplasm are possibly related to the growth and division of plastids and mitochondria.     

Occurrence of amitotic division of trophoblast cell nuclei in blastocysts of the western spotted skunk (Spilogale putorius latifrons)

A cytogenetic examination of spreaded cells of diapausing and early activated blastocysts obtained from 7 female western spotted skunks was performed. Mitosis was not observed in 1626 cells obtained from 9 diapausing blastocysts; however, 12 (1.5%) figures of diploid mitosis were seen in 851 cells from 5 early activated embryos. Diameter of the cell nuclei varied from 4 to 29 microm during diapause, and from 5 to 40 microm in activated blastocyst, and the heterogeneity in nuclear size was significantly different between diapausing and activated embryos (P<0.01). About 80% of nuclei from diapausing blastocysts measured 9 to 16 microm, whereas a similar percentage of nuclei from activated blastocysts ranged from 15 to 27 microm. Many enlarged nuclei exhibited morphological features characteristic of mammalian polytene (i.e. endopolyploid with polytenic organization of chromosomes) trophoblast cells. The number of silver stained nucleoli in all the nuclei did not exceed 2, which corresponds to the number of nucleolus organizers in the diploid karyotype in this species of skunk and suggests the polytene organization of chromosomes in enlarged nuclei. About 10% of large interphase nuclei were observed to undergo amitosis, i.e. direct division by constriction. The resulting nuclear fragments in diapausing blastocysts usually had normal morphology and active nucleoli. In activated embryos, nearly 15% of amitotically divided nuclei appeared to be dividing into fragments of unequal size, one of which had normal cell nuclear morphology and extremely large silver positive nucleoli, and the other fragment exhibited signs of cell death. We interpret these data as indicating that 1) amitotic division of trophoblast endopolyploid cell nuclei in the skunk blastocysts may generate new trophoblast cells which contribute to increased cell number during both diapause and activation stages, and 2) activation of blastocysts after diapause is related to the production of trophoblast cells with enhanced synthetic capabilities.     

Structural characteristics of the mediastinal pleura and its blood vessels

By means of impregnation of the microcirculatory bed vessels after V. V. Kupriyanov and transmissive electron microscopy, topological picture of hemomicrovessels has been estimated in the glomerular constructions of the dog mediastinal pleura. The composition of cell elements and peculiarities in distribution of the latter in the zone of the milk spots are examined. Their structural characteristics are manifested as presence of mesothelium of a decomplexated type accumulation of macrophagal and lymphocyto-plasma cells, glomerular organization of the capillary network and postcapillary venules, two types of endothelial lining of the metabolic microvessels. The role of the milk spots in ensuring immune protection, in migration of macrophages and in filtration of the pleural liquid is discussed.     

Growth,mitosis and morphogenesis of the simple liver acinus in neonatal rats

Radioautography after ³H-thymidine injection, blockage of mitosis due to colchicine and camera lucida drawings were used to study growth, mitosis and morphogenesis in the simple liver acinus of Rappaport in neonatal rats. Hepatic parenchymal cell plates are irregularly arranged and thick from birth to 4 days postpartum. By 10 days the plates begin to assume the adult configuration, irregular and thick in acinar zone 1 (periportal) but straight and thin in acinar zone 3 (pericentral). After a single injection of ³H-thymidine at birth the distribution of labeled nuclei among the hepatic acinar zones was such that zone 1 contained most, zone 3 least, and zone 2 an intermediate amount. This relationship remained constant out to 10 days postpartum. The amount of labeled cells within each zone varied, reaching its highest values at 2 days in zones 1 and 2 but not until 4 days in zone 3. Similar to the distribution of labeled nuclei, frequency of mitosis also exhibited a constant relationship of zone 1 > zone 2 > zone 3, but peaks of cell division within each zone were not always present. All three zones displayed a peak of mitosis at 4 days, whereas a second mitotic peak at 10 days was attained only by cells in zones 1 and 2.Conclusions are: (1) The neonatal liver is an expanding cell population with most of the expansion confined to acinar zones 1 and 2, (2) the period of 4–6 days postpartum is critical and could be the time when acinar metabolic zones are forming, (3) the irregular arrangement of cell plates in the center of the acinus (zone 1) may act to dampen arterial pulsations and allow adequate mixing of arterial and venous blood, (4) immediate postnatal growth of the liver acinus, as shown by an increase in its width, is due primarily to an increase in cell number since individual cell size does not increase.     

Histocytological characteristics of Eucalyptus urophylla?��?Eucalyptus grandis shoot apical meristems of different physiological ages

Histocytological characteristics of Eucalyptus urophylla × Eucalyptus grandis shoot apical meristems (SAMs) were described, comparing five outdoor and in vitro sources of akin genotypes differing in their physiological age. The size and the number of cells of the five zones identified within each SAM, i.e. the two tunica layers (L1 and L2), the central mother cells (CMC), the peripheral zone (PZ) and the combination of these four zones (4CZ) varied according to physiological age and plastochron phase. These five zones were significantly larger with higher numbers of cells for SAMs from mature and juvenile trees than for those from physiologically rejuvenated, in vitro mature and in vitro juvenile plants. However, these origin-related differences were not significant for SAMs in their early plastochron phase, to become obvious in a more advanced plastochron stage. Individual cell and nuclear measurements confirmed the rationale of distinguishing within SAM zones, characterized by specific cell and nuclear sizes liable to vary according to physiological age. The various histocytological investigations carried out established that SAM cell characteristics appeared to be the more reliable indicators of phase change. This was particularly true for the nucleoplasmic ratio and for more qualitative differences observed also at the nuclear level. SAM nuclei of the two in vitro origins were more evenly stained by naphtol blue-black, uniformly light for the juvenile source, whereas the mature source showed also darker nuclei. In contrast, SAM nuclei from outdoor origins had more chromocenters, darker and diffusely spread for the mature source than for the rejuvenated and the juvenile origins, where they were more peripherally distributed and where the nucleoli appeared more clearly. These results were discussed with respect to physiological ageing and in vitro culture influence, and suggest a determining influence of SAM cell nuclei on phase change phenomenon of arborescent species.