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PubMed2002

Testis morphometry, seminiferous epithelium cycle length, and daily sperm production in domestic cats (Felis catus).

There is very little information regarding the testis structure and function in domestic cats, mainly data related to the cycle of seminiferous epithelium and sperm production. The testis weight in cats investigated in the present study was 1.2 g. Compared with most mammalian species investigated, the value of 0.08% found for testes mass related to the body mass (gonadosomatic index) in cats is very low. The tunica albuginea volume density (%) in these animals was relatively high and comprised about 19% of the testis. Seminiferous tubule and Leydig cell volume density (%) in cats were approximately 90% and 6%, respectively. The mean tubular diameter was 220 microm, and 23 m of seminiferous tubule were found per testis and per gram of testis. The frequencies of the eight stages of the cycle, characterized according to the tubular morphology system, were as follows: stage 1, 24.9%; stage 2, 12.9%; stage 3, 7.7%; stage 4, 17.6%; stage 5, 7.2%; stage 6, 11.9%; stage 7, 6.8%; and stage 8, 11 %. The premeiotic and postmeiotic stage frequency was 46% and 37%, respectively. The duration of each cycle of seminiferous epithelium was 10.4 days and the total duration of spermatogenesis based on 4.5 cycles was 46.8 days. The number of round spermatids for each pachytene primary spermatocytes (meiotic index) was 2.8, meaning that significant cell loss (30%) occurred during the two meiotic divisions. The total number of germ cells and the number of round spermatids per each Sertoli cell nucleolus at stage 1 of the cycle were 9.8 and 5.1, respectively. The Leydig cell volume was approximately 2000 microm3 and the nucleus volume 260 microm3. Both Leydig and Sertoli cell numbers per gram of testis in cats were approximately 30 million. The daily sperm production per gram of testis in cats (efficiency of spermatogenesis) was approximately 16 million. To our knowledge, this is the first investigation to perform a more detailed and comprehensive study of the testis structure and function in domestic cats. Also, this is the first report in the literature showing Sertoli and Leydig cell number per gram of testis and the daily sperm production in any kind of feline species. In this regard, besides providing a background for comparative studies with other fields, the data obtained in the present work might be useful in future studies in which the domestic cat could be utilized as an appropriate receptor model for preservation of genetic stock from rare or endangered wild felines using the germ cell transplantation technique.

Animals↗
PubMed1996

[Inhibitory action of Chinese compound prescription for reinforcing vital energy and invigorating blood circulation on cancer cell multiplication].

Experiments have proved that the Chinese compound prescription for reinforcing vital energy and invigorating blood circulation markedly helps to improve the morphology of cancer cell nucleolus and membrane surface microvillus, amend the composition of microtubulin and facilitate intercellular gap junctional communication. Cell cycle kinetics shows that the multiplication of cancer cells in human stomach is checked mainly at G2M stage.

Adenocarcinoma, Mucinous↗
PubMedDate not supplied

[Role of the nucleolus in plant cell response to environmental physical factors].

Contemporary data on ultrastructural reconstruction and changes in functional nucleolus activity in plant cells affected by physical environmental factors are presented. The main attention is paid to modifications of ribosomal gene expression under these conditions and induced changes in r-chromatin structure and ribosomal DNA localization. Recent data on fine nucleolus structure and molecular aspects of its organization as well as influence of microgravitation and clinostating on structural and functional organization of plant nucleoli are reported.

Adaptation, Biological↗
PubMed1987

Anti-NOR 90. A new autoantibody in scleroderma that recognizes a 90-kDa component of the nucleolus-organizing region of chromatin.

We identified a patient (CAG) with scleroderma whose serum contained a high titer of IgG class antibodies that stained nucleoli in a pattern of independent tiny spots. When tested on isolated chromosomes, these antibodies selectively stained the nucleolus-organizing regions (NOR) of chromosomes 13, 14, 15, 21, and 22. These staining patterns were not altered when substrate cells and chromosomes were treated with RNase, 0.1 M HC1, or 4 M urea, but they were abolished by treatment with DNase and trypsin. Immunoblots performed with serum CAG on isolated nucleolar substrates identified a protein antigen of approximately 90 kDa. Antibodies affinity-purified from this protein selectively stained nucleoli and NOR chromosomal regions. Therefore, this protein is the antigen that accounts for the ability of serum CAG to recognize the NOR. In a search for the NOR 90-kDa specificity among 254 patients with various rheumatic diseases, we found nine additional patients whose sera stained metaphase chromosomes selectively at the NOR. Sera from five of them (three with scleroderma, two of unknown diagnosis) recognized a protein that electrophoretically co-migrated with the CAG antigen. Thus, scleroderma is present in at least four of six who appear to have this specificity. We conclude that autoantibodies to the NOR 90-kDa antigen have an association with scleroderma and may be useful diagnostically and as a probe for further studies of the biology of the cell nucleolus.

Autoantibodies↗
PubMed1982

Changes in the size and structure of the nucleolus of columnar cells during their migration from crypt base to villus top in rat jejunum.

An image analyser was used to measure the area of the nucleolus and its component parts in columnar cells at six levels of the jejunal epithelium, corresponding to stages in cell migration from crypt base to villus top. In columnar cells of crypt base, which function as stem cells for the epithelium, the nucleolus is large (3.1 micron2), irregular and reticulated. As cells migrate up the crypt, divide and differentiate, the nucleolus decreases in size (1.7 micron2) and becomes spherical, but remains reticulated. In the fully differentiated cells of the midvillus, however, the nucleolus becomes small (0.9 micron2) and compact. At the villus top, as the cells display early signs of degeneration, the nucleolus is further compacted (0.5 micron2). Most nucleolar components also decrease in size. Pars fibrosa (about 19% of the nucleolar area in crypt base) and pars granulosa (about 70%) decrease in proportion to the rest of the nucleolus, except in mid-villus and villus top where loss of pars granulosa predominates. In contrast, the total area of fibrillar centres remains constant (about 0.1 micron2), even though individual centres are small and numerous in crypt base, larger and fewer at higher levels, and they coalesce into a single structure in villus top. The other nucleolar components are also segregated into distinct, but adjacent, areas at this level. The changes in size and structure of the nucleolus taking place during the migration of columnar cells can be correlated with the maturation of the cells and the loss of their ability to synthesize ribosomal RNA.

Animals↗
PubMed1979

Changes in the activity of RNA polymerase detected in situ and the intensity of 3H uridine incorporation into the nucleolus and the nucleus of interphase cells in antheridial filaments of Chara vulgaris L.

Analogously as in the 32-cell stage [20], in the 4-, and 8-cell generations of antheridial filaments of Chara vulgaris, the activity of DNA dependent RNA polymerase detected in situ as well as the 3H uridine incorporation increase in the middle S phase and in the middle G2 phase, while they decrease considerably at the end of S phase and in late G2 phase. The diphasic changes occur both in the nucleolar and extranucleolar (nucleoplasmic) activity of RNA polymerase as well as in the 3H uridine incorporation. However, the maximum nucleolar activity, in both S and G2 phases, precedes the peak of nucleoplasmic activity. During the increased nucleolar activity RNA polymerase (as calculated per nucleus) shows a higher level as compared with nucleoplasmic RNA polymerase, whereas the intensity of 3H uridine incorporation into nucleous and nucleoplasm is similar. It may be supposed that the incubation environment containing Mg2+ used in vitro is more stimulating for the nucleolar RNA polymerase than for the nucleoplasmic RNA polymerase. The mean transcriptional activity of the nucleus and the activity of RNA polymerase in the 8-cell generation is about 20% lower than in the 4-cell generation, in proportion to the decrease in cell sizes.

Cell Cycle↗
PubMed1994

Effects of lead on root growth, cell division, and nucleolus of Allium cepa.

The effects of different concentrations of lead nitrate on root growth, cell division, chromosome morphology and nucleolus in root tip cells of Allium cepa were studied. The concentrations of lead nitrate (Pb(NO(3))(2)) were 10(-7), 10(-6), 10(-5), 10(-4), 10(-3) and 10(-2) m. It was observed that lead reduces root growth and causes mitotic irregularities, including c-mitosis, anaphase bridges, and chromosome stickiness. Also, interphase cells with micronuclei, irregularly shaped nuclei and nuclei with decomposed nuclear material were noticed. The c-mitotic effect reached its maximum in the meristem at above 10(-4) m Pb, when practically almost all the anomalous dividing cells are of this type. After treatment with Pb, there were many similar silver-stained particulate materials scattered in the nucleus in short, rounded meristem cells and in long, oblong root cap cells.

Journal Article↗
PubMed1999

AgNOR of human interphase cells in relation to acrocentric chromosomes.

Using simultaneous detection of fluorescence in situ hybridization (FISH) to acrocentric chromosome centromeres and argyrophilic nucleolar organizer regions (AgNOR), we investigated the number of AgNOR and involvement pattern of acrocentric chromosomes in the nucleoli in various types of human interphase cells. The number of AgNOR of normal gastric mucosal epithelial cells was 2.27 +/- 1.18 and was higher than that of lymphocytes (1.08 +/- 0.28) and lower than that of gastric cancer (7.76 +/- 3.21). The number of acrocentric chromosome centromere signals of normal gastric mucosal epithelial cells was higher than that of normal leukocytes (P < 0.000), and lower than that of gastric cancer (P < 0.000). The acrocentric chromosome centromere signals in the lymphocytes and neutrophils were only half of that expected for diploid cells, perhaps related to acrocentric chromosome association. The proportion of acrocentric chromosomes attached to AgNOR in gastric cancer (0.88 +/- 0.22) was significantly higher than that of normal gastric mucosal epithelial cells (0.72 +/- 0.35, P = 0.007). In conclusion, acrocentric chromosome association appears to be present in circulating leukocytes even in interphase. The number of AgNORs and proportion of acrocentric chromosomes involved in AgNORs in human interphase cells may vary according to cell types. This could play a significant role in rDNA transcription and determination of cell phenotype, including malignant change.

Cell Division↗
PubMed2003

Nucleoli in large (giant) bi- and multinucleate cells after apoptosis-inducing photodynamic treatment.

The present experimental study was undertaken to provide information on nucleolar changes accompanying the apoptotic process in large or giant binucleate and multinucleate cells (LBMNCs). Such cells were present in a small but constant percentage in cultures of HL-60 cells. The apoptotic process was induced by photodynamic treatment (PDT) by means of 5-aminolaevulinic acid (ALA) as the precursor of the photosensitizer protoporphyrin IX and irradiation with broad spectrum blue light (BL). Nucleolar changes in LBMNCs were characterized by marked reduction or disappearance of silver stained particles representing AgNORs in nucleoli including the large ones. In addition, PDT also significantly reduced the number of nucleoli regardless of their size. These changes apparently reflected the decrease or cessation of nucleolar biosynthetic activities and resembled those which were previously observed in naturally maturing bone marrow megakaryocytes (Janoutová et al., 2001).

Aminolevulinic Acid↗
PubMed1989

[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.

Animals↗
PubMed2001

Human acrocentric chromosomes with transcriptionally silent nucleolar organizer regions associate with nucleoli.

Human ribosomal gene repeats are distributed among five nucleolar organizer regions (NORs) on the p arms of acrocentric chromosomes. On exit from mitosis, nucleoli form around individual active NORs. As cells progress through the cycle, these mini-nucleoli fuse to form large nucleoli incorporating multiple NORs. It is generally assumed that nucleolar incorporation of individual NORs is dependent on ribosomal gene transcription. To test this assumption, we determined the nuclear location of individual human acrocentric chromosomes, and their associated NORs, in mouse> human cell hybrids. Human ribosomal genes are transcriptionally silent in this context. Combined immunofluorescence and in situ hybridization (immuno-FISH) on three-dimensional preserved nuclei showed that human acrocentric chromosomes associate with hybrid cell nucleoli. Analysis of purified nucleoli demonstrated that human and mouse NORs are equally likely to be within a hybrid cell nucleolus. This is supported further by the observation that murine upstream binding factor can associate with human NORs. Incorporation of silent NORs into mature nucleoli raises interesting issues concerning the maintenance of the activity status of individual NORs.

Animals↗
PubMed1992

Phosphorylation of the Rex protein of human T-cell leukemia virus type I.

Rex protein, the posttranscriptional regulator of human T-cell leukemia virus type I (HTLV-I), is required for the control of viral structural protein expression and virus replication. Rex is a phosphoprotein found predominantly in the cell nucleolus, whose function is thought to be regulated by its nucleolar localization and phosphorylation. Therefore, we investigated the in vivo phosphorylation of Rex protein in more detail. Phosphorylation of Rex occurred in all HTLV-I-infected cell lines examined in vivo, primarily at serine residues and to a very small extent at threonine residues. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) led to significant but transient enhancement of the incorporation of [32P]orthophosphate into Rex protein. N-terminal truncation of Rex protein abolished TPA-dependent phosphorylation. Chymotryptic digestion of phosphorylated Rex yielded two phosphopeptides. In vivo phosphorylation sites were identified as serine residues 70 and 177 and threonine residue 174. Serine 70 was a TPA-dependent phosphorylation site within a regulatory domain. We have already shown that the protein kinase C inhibitor H-7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine) specifically blocked accumulation of viral unspliced gag-pol mRNA. Therefore, the phosphorylation at serine 70 may be involved in the regulation of Rex function in response to extracellular stimuli.

Amino Acid Sequence↗