Cell Structure and Function
Online ISSN : 1347-3700
Print ISSN : 0386-7196
ISSN-L : 0386-7196
Volume 17, Issue 5
Displaying 1-10 of 10 articles from this issue
  • Juan Tong Li, Nozomi Yamaguchi, Masakazu Kita, Jiro Imanishi
    1992 Volume 17 Issue 5 Pages 257-261
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    It is well known that interferons inhibit cell growth. However, we found that human interferon-γ (HuIFN-γ) enhanced the growth of human osteosarcoma cells, HOS-Y1 cells, in a dose-dependent manner. This enhancing effect was found only under the following conditions: when the cells were precultured for 2 or 3 days and then treated with HuIFN-γ for 2, 3, or 4 days, and when the cells were seeded at a density of 1, 000 or 2, 000 cells/well. The degree of enhancement of cell growth was maximum when the cells were precultured at a density of 1, 000 cells/well for 3 days and then treated with HuIFN-γ for 2 days. The enhancing effect of HuIFN-γ disappeared in the presence of anti-HuIFN-γ antibody. In addition, it was found that the conditioned medium from HOS-Y1cells enhanced the growth of HOS-Y1 cells, and that the conditioned medium from HOS-Y 1cells cultured with HuIFN-γ enhanced the cell growth more than that from cells cultured without HuIFN-γ. Epidermal growth factor (EGF), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and transforming growth factor-β1(TGF-β1) did not enhance the growth of HOS-Y1 cells. These results suggest that HuIFN-γ enhanced the cell growth by augmenting the production of unknown growth factor(s) in HOS-Y1cells via an autocrine mechanism.
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  • Hiromi Hosoya, Tohru Marunouchi
    1992 Volume 17 Issue 5 Pages 263-269
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    U937 cells were differentiated into macrophages after being treated with 12-o-tetradecanoylphorbol- 13-acetate (TPA) for the first two days and dedifferentiated with daily medium renewal for 10 days. Cell proliferation slowed down and the number of cells reached the maximum level on day 2. By day 4, all of the cells had spread and attached firmly to the culture dish, and more than 90% of the cells expressed the Fc-receptor and produced superoxide anion. From there on, the number of adherent, living cells decreased gradually to about half the initial count. Most of the cells eliminated from the culture by cell death were in the S phase at the time of TPA treatment. After day 8, the number of cells expressing macrophage-specific phenotypes gradually decreased, cell adhesion was weakened, and at the same time, DNA synthesis was initiated anew. The cells became round and began to proliferate as floating cells on days 9 to 10, and thereafter they became sensitive to the second round of TPA treatment. On the basis of all the results taken together, it is suggested that fully differentiated U937 cells were dedifferentiated after being cultured with frequent medium renewal.
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  • Kenji Sorimachi, Sunao Yamazaki, Yosihiro Yasumura
    1992 Volume 17 Issue 5 Pages 271-276
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    Reuber rat hepatoma cells (R-Y121B) cultured at 0.5% serum accumulated apoalkaline phosphatase in intact cells. When R-Y121B cells were cultured in the presence of bovine serum albumin, alkaline phosphatase activity increased in the cells, and the associated increase in enzyme activity differed amongst bovine serum albumin preparations. The treatment of bovine serum albumin with activated charcoal not only enhanced the effect of serum albumin on alkaline phosphatase activity, but also cancelled the differences due to different preparations of serum albumin. In contrast, no effect from serum albumin was observed in the increase of alkaline phosphatase activity in R-Y121B cell homogenates incubated at 37°C. The activated-charcoal treatment of bovine serum albumin increased the amount of Zn2+ bound to the protein. When R-Y121B cells were cultured with bovine serum albumin, the concentration of Zn2+ in the cytosol fraction slightly increased. However, the effect of serum albumin on Zn2+ concentration in the cytosol fractions was independent of charcoal treatment. It was concluded that serum albumin with Zn2+ induces the activation of apoalkaline phosphatase due to Zn2+ binding.
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  • Shin-ichi Hisanaga, Sachiko Endo, Nobutaka Hirokawa, Hikoichi Sakai, J ...
    1992 Volume 17 Issue 5 Pages 277-285
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    The ultrastructure of detergent-resistant cytoskeletons in the noncortical cytoplasm of sea urchin eggs was studied by quick-freeze, deep-etch electron microscopy. Two different cytoskeletal organizations were identified in the detergent-treated sea urchin eggs. They were distinguished by the presence or the absence of long actin filaments and probably correspond to the cortex and the noncortical cytoplasm, respectively. The non-cortical cytoplasm was composed of a complex network (designated here as the ground network) of filaments 6 to 13 nm in diameter, that interconnected aggregates of small globular materials, yolk granules and a meshwork of uniform filaments (8-9 nm in diameter). The 6 to 13 nm filaments comprising the ground network were branched and associated with filaments of the same or other sizes, resulting in the formation of an extremely complex network. The meshwork of 8-9 nm filaments was homogeneousin composition and constitutes a novel structure which has not been previously described. The 8-9 nm filaments were connected to one another at their ends, forming a meshwork of polygons. Meshworks, ranging up to 3 μm in diameter, were distributed throughout the non-cortical cytoplasm of the egg. Similar cytoplasmic structures were also observed in fertilized eggs.
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  • Roberto di Primio, Oriana Trubiani, F.J. Bollum
    1992 Volume 17 Issue 5 Pages 287-292
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    The ability to overproduce terminal transferase through recombinant DNA technology should provide alternate means for generating sufficient quantities for structural and mechanistic study of this creative DNA polymerase. In this work we have investigated, at electron mocroscope level, the morphological modification and ultrastructural localization of synthesized human terminal transferase occurring in Sf-9 cells during recombinant baculovirus infection time. The results obtained showed that TdT is localized and stored only at the cytoplasmic level; the nucleus did not show any specific site able to link the neosynthesized TdT. The amount of the enzyme, estimate by immunostaining analysis, increased with the viral infection time. Morphological changes occurring during viral infection consist mainly of variations of cellular surface, different size and shape of cytoplasmic organdies and modification of nuclear components.
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  • Mika Hatai, Kazuhiko Takahara, Hidetaka Hashi, Ikunoshin Kato, Yoshihi ...
    1992 Volume 17 Issue 5 Pages 293-300
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    An expression vector pTF7520-Col-V-In, which encodes a fusion protein of the cell-binding domain of fibronectin (C277) and the insulin- and heparin-binding domain of the α1 chain of human type V collagen, was constructed. E. coli transfected with this plasmid synthesized a 50-kDa fusion protein. This fusion protein, C277-V, was purified from the crude extract by a single step heparin HPLC.Similar amounts of insulin bound to purified C277-V and to theα1 chain of type V collagen as judged by the binding of peroxidase-conjugated insulin. Cell-adhesive activity of C277-V was lower than that of the original fibronectin fragment C274, but similar numbers of cells adhered to both protein substrates when the culture dishes were coated with 1 mM of each protein. Insulin bound to the C277-V substratum stimulated the growth of mouse mammary tumor MTD cells in serum-free culture medium.
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  • Yukiko Shimada, Tomoko Kasakura, Michiyo Yokota, Yoshihiko Miyata, Hir ...
    1992 Volume 17 Issue 5 Pages 301-309
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    Under unfavorable conditions for growth, haploid myxoamoebae of Physarum polycephalum retracted their pseudopodia and changed their cell shape into disk-like form, after which they constructed the cell walls to form microcysts. These morphological changes of haploid cells were associated with changes in intracellular distribution of actin filaments. Staining with phalloidin showed that actin filaments were almost uniformly distributed throughout the cytoplasm of the myxoamoebae. Whenthese cells were transferred to a cyst-inducing medium, the actin structures changed into short rods or dots, after which the rods/dots disappeared in the microcysts. Anincubation of the myxoamoebaein the cyst-inducing medium caused the synthesis of several proteins, among which a 66-kD protein was most prominently induced. The morphological changes and the induction of the 66-kD protein was pronounced at elevated temperatures, e.g. 40°C. The 66-kD protein was not induced, however, when plasmodia of the same species were incubated at 40°C. W efound that the 66- kD protein was co-precipitated with polymerized actin and bound to ATP-agarose. A double staining of the disk-shaped cells with anti-66-kD protein antibody and phalloidin revealed superimposable localization of the 66-kD protein and actin filaments in the short rods or dots. Although the induction of the 66-kD protein was enhanced at high temperatures, the protein was immunologically unrelated to the common heat shock proteins, HSP70 and HSP90, those are highly conserved during evolution. These results indicate that the 66-kD protein is a novel heat shock protein which is specifically expressed during cyst formation.
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  • Edésio José Tenorio de Melo, Tecia Ulisses de carvalho, ...
    1992 Volume 17 Issue 5 Pages 311-317
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    Fluorescence microscopy, using dyes which specifically label mitochondria, endoplasmic reticulum and the Golgi complex, and transmission electron microscopy, were used to analyze the changes which occur in the organization of these structures during interaction of Toxoplasma gondii with host cells. In uninfected cells the mitochondria are long filamentous structures which radiate from the nuclear region toward the cell periphery. After parasite penetration they become shorter and tend to concentrate around the parasite-containing vacuole (parasitophorous vacuole) located in the cytoplasm of the host cell. The mitochondria of extracellular parasites, but not of those located within the parasitophorous vacuole, were also stained by rhodamine 123. Labeling with DiOC6, which binds to elements of the endoplasmic reticulum, in association with transmission electron microscopy, revealed a concentration of this structure around the parasitophorous vacuole. The membranelining this vacuole was also stained, suggesting that components of the endoplasmic reticulum are also incorporated into this membrane. The Golgi complex, as revealed by staining with NBD-ceramide and electron microscopy, maintains its perinuclear position throughout the evolution of the intracellular parasitism.
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  • Sumio Ishijima, Yukihisa Hamaguchi
    1992 Volume 17 Issue 5 Pages 319-323
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    As a first step towards understanding the function and mechanism of spiral movement of spermatozoa swimming through a medium, the direction of rolling (rotational movement of the spermatozoa around their long axis) and that of yawing (circular motion of spermatozoa upon the surface of a glass microscope slide and coverslip) were examined for golden hamster and sea urchin spermatozoa.
    Most golden hamster spermatozoa yawed clockwise over the upper surface of a glass slide when viewed from above, whereas in most sea urchin spermatozoa yawing was counterclockwise. Under the lower surface of a coverslip, the direction of yaw of golden hamster or of sea urchin spermatozoa was reversed. Most golden hamster spermatozoa rolled counterclockwise as seen from the anterior end, whereas all examined sea urchin spermatozoa rolled clockwise relative to the observer. On the basis of quantitative analysis of the proportion of spermatozoa rolling (or yawing) clockwise to those rolling (or yawing) counterclockwise, a close relationship between the direction of rolling motion and that of yawing motion was shown for both golden hamster and sea urchin spermatozoa.
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  • Kunihiko Ohtani, Akio Suzumura, Makoto Sawada, Tohru Marunouchi, Izumi ...
    1992 Volume 17 Issue 5 Pages 325-333
    Published: 1992
    Released on J-STAGE: March 27, 2006
    JOURNAL FREE ACCESS
    A permanent glial cell line has been established from the neonatal mouse primary mixed glial cell cultures by transfection with replication origin-defective simian virus 40 DNA. This cell line, designated OS3, has morphological similarity to type-2 astrocyte and expresses an astrocyte-specific marker, glial fibrillary acidic protein (GFAP), when cultured in the presence of 10% calf serum (CS). OS3 cells do not express the O4 antigen, galactocerebroside (GalC) and A2B5 under this culture condition. When cultured in a medium containing 2% CS or a chemically defined medium, these cells undergo morphological transformation. Someof these cells express O4 antigen and/or GalC, and the percentage of GFAP positive cells decreases under these conditions. Thus depending on the culture conditions, the OS3 cells display either type-2 astrocyte properties or immature oligodendrocyte characteristics. Furthermore, the OS3 cells show similar responses to the various growth factors as do oligodendrocyte/type-2 astrocyte (O-2A) progenitors. Therefore, the OS3 cell line is an unique mouse bipotential permanent O-2A lineage cell line which may be useful to analyze the developmental properties of these glial cells.
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