Cell Structure and Function
Online ISSN : 1347-3700
Print ISSN : 0386-7196
ISSN-L : 0386-7196
Volume 1, Issue 4
Displaying 1-11 of 11 articles from this issue
  • Kiyoharu Oono, Yasuo Hotta
    1976 Volume 1 Issue 4 Pages 299-312
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Three intervals of DNA synthesis in Lilium microsporocytes-premeiotic S-phase, delayed zygotene replication and pachytene repair synthe-sis-were analyzed with respect to chromosome compaction. Chromatin was prepared from isolated nuclei and fractionated into a condensed and a diffuse component. Glutaraldehyde was used in a parallel procedure to crosslink chro-matin that might be compacted but unstable in the fractionation procedure. Nuclei in premeiotic S-phase had a much larger fraction of condensed chro-matin rescued by glutaraldehyde than those in any other stage. Virtually no DNA replication occurred in this fraction until the last interval of S-phase. Zygotene replication occurred mainly in the diffuse chromatin fraction and the distribution remained so after completion of replication. Pachytene repair syn-thesis occurred mainly in condensed chromatin. Generally, sequences with high C0t value fractionated preferentially with diffuse chromatin but the opposite was the case for pachytene nuclei. Digestion with staphylococcal nuclease revealed no significant differences in nucleosome organization of condensed and diffuse chromatin.
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  • Takao Matsuura, Hisao Ueyama, Kiyoshi Ueda
    1976 Volume 1 Issue 4 Pages 313-320
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The uptake of thymidine and uridine in Tetrahymena pyriformis was investigated using the glass membrane filter method. The uptake of both of these nucleosides at 2 μM was temperature-and energy-dependent. The optimal pH was 5.5. The uptake of both was competitively inhibited by other nucleosides. Thymidine and uridine were considered to be transported by carrier mediated systems, and these mechanisms are discussed.
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  • Guy Marie-Sainte
    1976 Volume 1 Issue 4 Pages 321-325
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    It has been established that 3H-thymidine inadequately labels the various lymphocytoid populations of the rat. Recently, 3H-deoxycytidine was shown to label these cells more adequately. The purpose of the present work was to verify if, as 3H-thymidine, 3H-deoxycytidine is incorporated only during the first 45 minutes following its injection. Rats were sacrificed at various intervals, up to 24 hours, after receiving an intravenous dose of one or the other DNA precursors. Radioautographs of their lymphoid organs revealed that, unlike 3H-thymidine, the incorporation of 3H-deoxycytidine continues during 24 hours after injection.
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  • Akira Yamashita, Megumu Miyamoto, Hiroto Naora
    1976 Volume 1 Issue 4 Pages 327-335
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The labelling pattern of 3H-labelled uridine incorporation into RNA was studied by autoradiography in small lymphocytes obtained from the efferent lymph of normal sheep lymph nodes. Heavily labelled small lym-phocytes were always observed in the sheep lymphocyte population. They constituted 3.6 % of the total population. Antigen-stimulation did not alter the number of heavily labelled small lymphocytes. The majority of small lympho-cytes contained only one or two nucleoli, but 5 to 8 percent of the population possessed more than five nucleoli. The possibility was considered that the heterogeneity of small lymphocytes in RNA labelling may be associated with the development of nucleoli and that the heavily labelled small lymphocytes were engaged in particular functions being actively pursued in the efferent lymph.
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  • Yoshio Misumi, Shunichi Kurata, Bungo Sakaguchi, Koichiro Shiokawa, Ki ...
    1976 Volume 1 Issue 4 Pages 337-343
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Cells from Xenopus kidneys were cultured. Incorporations of 3H-uridine, 3H-thymidine and 14C-protein hydrolyzate were examined, and synthesized RNA was electrophoretically analyzed. The synthesis of RNA, DNA and protein was found to take place at different rates at different phases and the synthesis of ribosomal RNA, as well as other macromolecules, was quite active during the early logarithmic phase. The number and size of nucleoli varied markedly during culture, and these changes were correlated with the activity of cellular RNA synthesis.
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  • Sunao Iwata, Masa-oki Yamada
    1976 Volume 1 Issue 4 Pages 345-354
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The presence of free ribosomal proteins was examined using anti-γ-globulin prepared against ribosomal proteins of Escherichia coli B. The anti-γ-globulin did not react with ribosome-free soluble proteins of E. coli cells by double diffusion test, immunoprecipitation test or gel filtration. Moreover, anti-γ-globulin did not react with any fractions of soluble proteins obtained by carboxymethyl cellulose-, DEAE-cellulose-or Sephadex G75-column chromatography. By mixing labeled ribosomes with unlabeled soluble proteins and vice versa and by comparing the specific activities of the ribosomes before and after mixing, ribosomal proteins were found to not exchange with any soluble protein in vitro. These results indicate that there is no pool of ribosomal protein in E. coli cells.
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  • Yoshiyuki Tohno, Setsuko Tohno, Akira Takakusu
    1976 Volume 1 Issue 4 Pages 355-365
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Rat ascites hepatoma chromatin was dissociated in 2 M NaCl-5 M urea-50 mM sodium acetate (pH 6.0) and reconstituted by gradient dialysis against decreasing concentrations of NaCl in the presence of urea. The mode of reassociation of chromatin protein components with DNA was examined mainly by gel electrophoresis. Histone 1 bound to DNA during dialysis against 5 M urea containing decreasing concentrations of NaCl from 0.4 to 0.2 M, and other histone fractions bound to DNA in dialysis at NaCl concentrations from 0.3 to 0.1 M. Binding of histones to DNA was almost completed in 0.1 M NaCl-5 M urea, but about one-half of the died with DNA at this step. Some electrophoretically separated CNH proteins reassociated with DNA at almost the same time that histones bound to DNA, and other proteins reassociated with DNA after completion of binding of histones to DNA.
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  • Hidenori Hayashi, Tetsuya Suga, Shinkichi Niinobe
    1976 Volume 1 Issue 4 Pages 367-376
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Partially purified peroxisomal core containing and not containing the light component was isolated from the liver homogenate of the rat and used for formation of the core complex bearing D-amino acid oxidase (DAAO). When either core preparation was vigorously stirred in the DAAO preparation at 0°C for 30 min and then centrifuged at 20, 000g for 30 min, the urate oxidase activity as a core marker was found in the pellet in which a small amount of DAAO activity was also found. The peroxisomal core containing the light component had a tendency to constitute the core-DAAO complex more easily than core without the component. The light component was extracted from the partially purified core (100-fold over the liver homogenate). The light component had a high cholesterol content. An experiment on reconstitution of the approximate native core complex using preparations of the light component, DAAO and the highly purified core (about 450-fold over the liver homogenate) showed that the peroxisomal core complex seemed to consist of urate oxidase, other peroxisomal oxidases, such as DAAO, and the light component, and also showed that DAAO and the light component probably underwent some interactions when binding to the core.
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  • Masamichi J.Ueda, Masatoshi Takeichi
    1976 Volume 1 Issue 4 Pages 377-388
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The effect of divalent cations on cell-to-cell and cell-to-substrate adhesions was studied using two different types of chicken embryonic cells (fibroblastic and neural retina cells). Mn2+, Co2+, Mg2+ and Ca2+ were effective in promoting the aggregation of fibroblastic cells, while Sr2+ and Ba2+ were not effective. Among these ions, Ca2+ showed some unique effects on cell aggregation. Aggregation was initiated immediately after the addition of Mn2+, Co2+ or Mg2+ whereas with Ca2+ a lag period was always observed. When the medium contained both Ca2+ and Mg2+, the aggregate size formed was bigger than that formed with either ion at an equimolar concentration. The divalent cation dependence of fibroblastic cell adhesion to non-cellular substrate was essentially the same as that of cell-to-cell adhesion. The aggregation of neural retina cells specifically depended on the presence of Ca2+. For adhesion of neural retina cells to non-cellular substrate, however, Ca2+ was not effective, and only Mn2+ or Co2+ was effective. These results suggest two different mechanisms in cell adhesion.
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  • Satoru Murakami, Reiko Kunieda
    1976 Volume 1 Issue 4 Pages 389-392
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
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  • Toshihisa Kusano, Miwa Kato, Isao Yamane
    1976 Volume 1 Issue 4 Pages 393-396
    Published: 1976
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Orotic aciduria is a rare autosomal recessive disease. The homozygous patients have megaloblastic anemia and pancytopenia. The patients also excrete large quantities of orotic acid in urine. Most and perhaps all of the disease symptoms respond to dietary supplementation of uridine. We undertook a search for auxotrophic variants in mammalian cells in vitro, as a possible model system for inherited human biochemical diseases. The present study reports on the induction and isolation of variant Chinese hamster cells requiring uridine for in vitro growth.
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