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Volume 3 (1978)
- Issue 4 Pages 279-
- Issue 3 Pages 145-
- Issue 2 Pages 71-
- Issue 1 Pages 1-
Volume 3, Issue 1
Displaying 1-8 of 8 articles from this issue
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Kenzo Ohtsuka, Yuji Tonomura1978 Volume 3 Issue 1 Pages 1-9
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe previously reported that the beating rate of single myocardial cells cultured in a conditioned medium (CM) was higher than that of cells cultured in a fresh medium. We have characterized and partially purified the beating-stimulating factor(s) of cultured myocardial cells from a conditioned medium of mouse embryonic cells.
The beating-stimulating factor(s) had stable activity for more than one month when it was freeze-dried in 0.1 M sucrose and stored at -20°C. The factor(s) was non-dialyzable and was heat-labile. It was inactivated by treatment with trypsin, pronase or hyaluronidase, but not with neuraminidase. These results strongly suggest that the beating-stimulating factor(s) is a glycoprotein(s). When concentrated CM was filtered on Sephadex G-200, the main peak of activity appeared in almost the same fractions as in those for that of hemoglobin. The SDS-polyacrylamide gel electrophoretogram of crude CM showed more than 20 protein bands and about 10 bands stainable by periodic acidSchiff (PAS). In contrast, the electrophoretogram of the active peak on Sephadex G-200 showed about 10 protein bands and one PAS-stainable band.View full abstractDownload PDF (877K) -
Kyozo Tsukamoto1978 Volume 3 Issue 1 Pages 11-23
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSBovine adenovirus type 3 (BAV3) causes abortive infection and induces cellular DNA synthesis in the mouse cell line, C3H2K.
A clone, N-1, was selected from this cell line after infection with BAV3 in the presence of 5-fluorodeoxyuridine. In this clone, cellular DNA synthesis was not induced by BAV3 infection, but became inducible in N-1 cells when the temperature of the culture was raised to 41°C-42°C prior to infection by BAV3. Heat-activated N-1 cells again became insensitive to BAV3 infection after prolonged cultivation at the normal temperature of 37°C. The addition of cycloheximide did not prevent activation of N-1 cells by heat, but it did prevent the activated N-1 cells from returning to their original state of being insensitive to BAV3 infection when cultivated at 37°C. Viral mRNA synthesis, which was followed by the induction of cellular DNA synthesis, was transiently detected only when N-1 cells were heat-treated before virus infection. Penetration into the cell and the uncoating of BAV3 proceeded in N-1 cells almost as normally as in C3H2K cells. Though the N-1 clone was selected by a procedure involving BAV3 infection, N-1 cells did not contain a detectable amount of the BAV3 DNA sequence as determined by analysis of DNA-DNA reassociation kinetics. The significance of these results is discussed.View full abstractDownload PDF (1299K) -
Katsumi Ueda, Yoko Tan, Fumihiko Sato, Yasuyuki Yamada1978 Volume 3 Issue 1 Pages 25-30
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSProtoplasts from mesophyll cells from leaves of Nicotiana tabacum and cultured cells of Rauwolfia serpentina were used. When polyethylene glycol was added to a mixture of these protoplasts, some protoplasts phagocytotically ingested another whole protoplast into their vacuoles. Phagocytosis occurred not only between protoplasts of the same species but also between those of different species. At the initial contact of two protoplasts, the cytoplasm between the plasma membrane and the tonoplast of the ingesting protoplast migrated from the area of contact and an invagination developed containing the other protoplast which was finally incorporated into the vacuole by closure of the invagination.View full abstractDownload PDF (680K) -
Shinjiro Kawai, Ken-ichi Tanaka1978 Volume 3 Issue 1 Pages 31-37
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDifferentiating cells of Dictyostelium discoideum were spinlabeled with 5-nitroxide stearic acid or phosphatidylcholine spin labels, and the electron spin resonance spectra of the cells were measured. There was no difference in the flexibility of the lipid bilayer in the membranes between preaggregation cells and disaggregated slug cells. The temperature dependence of the overall splitting value for 5-nitroxide stearic acid was also indistinguishable for the two cell types in the range of 4°C to 25°C. Two distinct inflection points were observed at 15°C and 19.5°C in the temperature dependence, suggesting the presence of a phase transition in the lipid bilayer portion of the membranes. We thus concluded that there is no change in the membrane fluidity of the cells on formation of a multicellular organization. In addition, trypsinization of slug cells, which enhances Con A-induced redistribution of the Con A-binding sites on the cell surface (Kawai, in preparation), did not cause any change in the flexibility of the lipid bilayer. This suggests that the increased mobility of the sites has no apparent correlation to the bulk membrane fluidity.View full abstractDownload PDF (741K) -
Hisao Miyata, Machiko Miyata, Michio Ito1978 Volume 3 Issue 1 Pages 39-46
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSVarious sized individual fission yeast cells, Schizosaccharomyces pombe, enclosed in small culture chambers were examined to see whether the size of the mother cells is related to the behavior of the cell cycle in the daughter cells. The lengths of the doubling time estimated from the elongation rates were similar regardless of the length of the mother cells. The final lengths of daughter cells from mother cells smaller than 20 μm were not related to the initial size, but the final lengths of cells larger than 20 μm showed a linear relationship to the initial size. The period of the cell cycle in the daughter cells was negatively proportional to the length of mother cells smaller than 20 μm, but the period was constant in cells larger than 20 μm with a relative value about 0.6 that of the normal cells. The relation of these results to the mechanism which maintains a particular cell size in proliferating cells is discussed.View full abstractDownload PDF (757K) -
Tomio Hayama, Masashi Tazawa1978 Volume 3 Issue 1 Pages 47-60
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe transcellular osmosis induced both slow membrane de-polarization (<50 mV sec-1) and cessation of cytoplasmic streaming in the endosmotic cell half of an internodal cell of Nitella flexilis. Membrane depo-larization and streaming cessation occurred in cells made inexcitable by bathing in 10 mM KC1, suggesting that Ca2+ in the external medium is not essential for streaming cessation.
Depolarization preceded the streaming cessation, suggesting that some membrane event induced by endosmosis may directly induce the streaming cessation. The larger the rate of depolarization, the stronger the streaming inhibition and the shorter the time needed for the cessation. The maximum rate of depolarization of the action potential was more than 10 times that of osmosis-induced depolarization. The all-or-none nature of the streaming cessation accompanying the action potential is interpreted as indicating that the rate of depolarization is high enough to always cause instant cessation.
Streaming cessation was observed even when the membrane potential was clamped at the same level as before the start of transcellular osmosis. The membrane electromotive force and membrane resistance decreased significantly as in the case where themembrane potential was not clamped.View full abstractDownload PDF (1358K) -
Masanobu Miyahara, Kaname Aono, Jorge Sancho Queseda, Kunio Shimono, Y ...1978 Volume 3 Issue 1 Pages 61-65
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe action of cepharanthie, a biscoclaurine alkaloid, on disturbances of the mitochondrial function caused by snake venom, phospholipase A2, lysolecithin, lead and high temperature was examined. The alkaloid protected mitochondria from damage caused by these treatments. The results suggest that the alkaloid protects biomembranes from various damage with no effect of its own at a low concentration.View full abstractDownload PDF (415K) -
Kazuhiro Ishii, Akira Matsumoto1978 Volume 3 Issue 1 Pages 67-70
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSSuspended 3T3 cells are highly resistant to immune cytolysis with antibodies and complement. This lytic resistance was not ascribed to the loss of surface antigens in the suspended 3T3 cells as demonstrated in a previous report (6). When treated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), however, 3T3 cells in suspension became highly sensitive to immune cytolysis and decreased in cell-aggregability. A concomitant observation was that most MNNG-treated cells had morphologically altered microvilli. This indicates that the occurrence of microvilli is related to the resistance to immune cytolysis of the suspended 3T3 cells.View full abstractDownload PDF (1740K)
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