Cell Structure and Function
Online ISSN : 1347-3700
Print ISSN : 0386-7196
ISSN-L : 0386-7196
Volume 12, Issue 6
Displaying 1-8 of 8 articles from this issue
  • Emiko Sano, Masahiko Iizuka, Sigeyasu Kobayashi
    1987 Volume 12 Issue 6 Pages 509-517
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Glucocorticoid hormones promoted the growth of fibroblast cells derived from human neonatal foreskins and prolonged their life span in a microcarrier culture system that used Eagle's minimum essential medium (MEM) supplemented with fetal calf serum (FCS). But, these hormones suppressed cell growth in conventional monolayer cultures.
    Precolostrum newborn calf serum (PNCS) was the only species that sup-ported the serial propagation of fibroblast cells on microcarriers, possibly because of its high content of hydrocortisone (HC).
    Fibroblast cells grown on microcarriers in the presence of glucocorticoid hormones maintained their ability to produce interferon (IFN)-β in a super-induction method with poly I : poly C and antimetabolites. These cells had more than 93 % diploidy and no chromosomal aberration or translocation.
    Use of PNCS for the cultivation of human fibroblast cells has high potential for providing a microcarrier culture system for the mass production of human IFN-β.
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  • Kimiko Murakami-Murofushi, Kazuko Nakamura, Jiro Ohta, Takao Yokota
    1987 Volume 12 Issue 6 Pages 519-524
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The sterol contents of the myxoamoebae of Physarum poly-cephalum were examined and compared to those of the diploid plasmodia of Physarum. Most of the sterol components were unsaturated, the major species being poriferasterol. The myxoamoebae also contained Δ5-ergostenol and 22-dihydroporiferasterol. The molar ratio of these three species of unsaturated sterols was 80 : 15 : 5.
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  • Tetsuro Horikoshi, Tohru Yoshioka, Yosinobu Kubota, Keiji Yanagisawa
    1987 Volume 12 Issue 6 Pages 525-537
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    The fluorescent dyes, rhodamine 6G and 123, which specifi-cally stain mitochondria, were used to examine changes in mitochondria that follow malignant transformation. The spatial distribution and shapes of mitochondria differ in untransformed and malignant-transformed cells. In untransformed C3H/10T1/2 clone 8 cells, the mitochondria were distributed radially around the nucleus, and each had a fibrous shape. In chemically transformed MCA clone 16 cells, the mitochondria were distributed randomly in the cytoplasm, and each was shaped like a short rod. Another important mitochondrial change after malignant transformation was the change in the time course of fluorescence emission from the rhodamine present in the mitochondria. A slow increase in fluorescence, which was instantaneous at the time of excitation irradiation occurred in untransformed but not in transformed cells. This slow fluorescence emission, peculiar to untransformed cells was affected by proton ionophore but not by calcium ionophore treatment. The difference in the time courses of fluorescence emission for untransformed and transformed cells may reflect differences in the quenching of the dye fluorescence. The data reported provide evidence that mitochondria are affected by malignant cell transformation.
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  • G.A. Rockwell, G. Johnson, A. Sibatani
    1987 Volume 12 Issue 6 Pages 539-548
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Human keratinocytes have been serially cultivated in low(0.015 mM) and high (1.8 mM) calcium containing medium. The calcium concentration of the growth medium significantly influenced the cell growth period in vitro. Cells grown in low calcium medium underwent 35-40 popu-lation doublings over 16-17 passages, while cells grown in high calcium medium ceased to proliferate after 20 population doublings over 7 passages. Changing the keratinocytes from one in vitro environment to the other drasti-cally altered the lifespan in culture of populations derived from the same primary tissue. The degree of DNA methylation of human keratinocytes was shown to decrease with age in both high and low calcium culture conditions but does not appear to be associated with differentiation.
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  • Yoshiki Shiba, Sumadhi Sastrodihardjo, Yasuto Sasaki, Yoshinobu Kanno
    1987 Volume 12 Issue 6 Pages 549-558
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    We have investigated the effects of various types of collagen and a tumor-promoting phorbol ester on intercellular contacts and the organi-zation of actin in human amnion epithelial FL cells and mouse fibroblast 3T3-A31 cells. Our purpose was to investigate how modulation of interactions between cells and the substratum leads to alterations in intercellular contacts and organization of actin filaments. When cells were cultured on dishes coated with a solution containing type I collagen, but not type IV, changes were induced in the morphology of FL cells and their intercellular contacts. Type I collagen also caused changes in the organization of their actin filaments, al-though no such effects were observed with 3T3-A31 cells. In contrast, 12-0-tetradecanoylphorbol-13-acetate (TPA) caused morphological changes, disso-ciation of groups of cells, and reorganization of actin filaments in cultures of FL and 3T3-A31 cells. It also disrupted the sites of adhesion of FL cells to the substratum. Both type I collagen and TPA rapidly induced spreading of FL cells in the absence of serum. However, cis-hydroxyproline, known to inhibit secretion of collagen, did not suppress the TPA-induced dissociation of groups of FL cells. These results suggest that the interactions with type I collagen of epithelial FL cells, but not of fibroblastic 3T3-A31 cells, tend to disorganize cellular morphology, intercellular contacts, and actin filaments in ways similar to, but not directly related to, the effects of TPA.
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  • Tsuyoshi Takasuka, Sadahiko Ishibashi, Toshinori Ide
    1987 Volume 12 Issue 6 Pages 559-565
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    When growth-arrested GC-7 cells, a cell line from African green monkey kidney, are stimulated with 10% calf serum, they enter S phase 14-15 h later. Cytochalasin D at 0.6 μg/ml blocks the entrance into S phase, and inhibits, though only partially, the increase in protein synthesis after serum stimulation. Since partial inhibition of protein synthesis by cycloheximide interferes with accumulation of labile proteins and thus blocks the entrance of serum-stimulated cells into S phase, the effects of these two inhibitors are compared. Cytochalasin D at lower concentrations reduced the rate of entry into S phase without affecting the length of the prereplicative phase, whereas cycloheximide extended the prereplicative phase dose dependently without affecting the rate of entry into S phase. Cytochalasin D affected neither individual [35S]methionine-labeled spots on two-dimensional polyacrylamidegel nor degradation of cellular proteins. These results indicate that cytochalasin D, though it intereferes with protein synthesis, blocks prereplicative progression of serum-stimulated GC-7 cells in a different manner than cycloheximide.
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  • Tadatomo Ogawa, Masao Hyodo, Seiji Ihara, Masataka Takekoshi, Kaori Mi ...
    1987 Volume 12 Issue 6 Pages 567-574
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    High-frequency transfection of mouse FM3A cells, grown in suspension, with plasmid pSV2neo DNA was achieved by incubation of the cells with DNA plus polybrene for 6 h followed by an osmotic shock with a hypertonic NaCl solution. When incubated for 20 min at 34°C, FM3A cells showed resistance to the osmolarity change from 0.1 to 9.0% NaCl in the medium. Within this concentration range, 5-7 % gave the highest efficiency of transfection. Both linear and circular forms of plasmid DNA produced transformants with equal efficiency. This method was simple, reproducible, and carrier DNA was not required. The efficiency was about 100 times higher than that of the method with DNA-calcium phosphate precipitates. Trans-formed cells were stable and different numbers of plasmid DNA copies were detected.
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  • Kazuto Katoh, Yoshiko Takahashi, Sigeo Hayashi, Hisato Kondoh
    1987 Volume 12 Issue 6 Pages 575-580
    Published: 1987
    Released on J-STAGE: April 18, 2008
    JOURNAL FREE ACCESS
    Cell lines, such as those of teratocarcinoma and embryonic stem cells, fail to support high G418 resistance after transfection of neo vectors. To alleviate this, we modified pSV2-neo in two steps, first with tandem promoters of SV40 early genes and HSVtk, then by removing an improper met codon located immediately upstream of the authentic initiator codon in the mRNA sequence. In the final product, pSTneoB, the neo transcription unit has Xhol sites at both ends. pSTneoB yields G418-resistant transformants of teratocarcinoma cells at dramatically higher efficiencies than pSV2-neo. This vector extends the application of G418 selection in gene transfer to a wider range of cell types.
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