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Volume 2 (1977)
- Issue 4 Pages 267-
- Issue 3 Pages 159-
- Issue 2 Pages 61-
- Issue 1 Pages 1-
Volume 2, Issue 2
Displaying 1-10 of 10 articles from this issue
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Nobuyuki Nishioka, Akio Matsukage, Taijo Takahashi1977 Volume 2 Issue 2 Pages 61-70
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDNA polymerase α of mouse myeloma MOPC104E cells was resolved into at least three active types which were designated forms A, B and C in order of elution from DEAE cellulose column. Eighty-four percent of total DNA polymerase α activity of mouse myeloma MOPC104E cells was found localized in nuclei isolated using Ca2+-containing medium. Forty percent of total nuclear activity was released upon treatment with salt-free medium, and most of the remaining activity was extracted with media containing 0.15 or 0.3 M KCl. The major species of 0 M KC1 extract was form C of DNA polymerase α, while the activity in 0.15 M KC1 extract was mainly composed of form B. The KC1 concentration required for extraction of form B from the nuclei seemed to coincide with that required for the elution of DNA polymerase α from native DNA cellulose column. These observations suggest that form B is in the complex with DNA or chromatin structure in nucleus whereas form C is free from the structure.View full abstractDownload PDF (1003K) -
G.A. Rockwell, Atuhiro Sibatani1977 Volume 2 Issue 2 Pages 71-79
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCalf thymocytes, freshly suspended in a protein-free minimum essential medium quickly lost viability at 3 × 105 but not at 1 × 107 cells/ml. For technical reasons [3H]thymidine incorporation into DNA was routinely used as a relative index of cell viability. The non-dialyzable fraction of a conditioned medium and of a cell-free extract obtained from thymocytes reversed the loss of viability at lower population density. An effective assay system was devised aiming at the isolation of the active factor. Calf serum and simple proteins like serum albumin and cytochrome c were without effect, and the former did not affect the activity of the factor. However, the factor was not highly species-or organ-specific. The abundance of the factor in thymocytes seemed to vary much less than the responsiveness to the factor of thymocytes from different animals.View full abstractDownload PDF (896K) -
Hiroyuki Shimonaka, Yoshinori Nozawa1977 Volume 2 Issue 2 Pages 81-89
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe subcellular localization and thermally-induced transition of adenylate cyclase activity were studied in a thermotolerant strain of Tetra-hymena pyriformis. A close relationship was present between adenylate cyclase activity and the cell growth cycle. Maximum cyclase activity was found in early stationary phase cells. Adenylate cyclase activity was found primarily associated with the surface membrane, pellicle, The activity of adenylate cyclase in pellicle membrane was measured as a function of temperature. Arrhenius plots of its membrane activity were found to be triphasic. A marked change occurred at about 28°C and small discontinuities were present at around 15°C. Freeze-cleavage electron microscopic observations of pellicle membranes revealed that membrane-intercalated particles began to form aggregation clusters at decreasing temperatures, and below the transition point (28°C) of cyclase activity a remarkable phase separation was formed. These results from enzymatic and morphological studies of pellicle membranes suggest that the thermally-induced transition of adenylate cyclase activity may reflect altered physical states of membrane lipid caused by temperature changes.View full abstractDownload PDF (3848K) -
Minoru Amano, Takiko Akino-Sugiyama, Harumi Munakata-Yoshida, Nobuko S ...1977 Volume 2 Issue 2 Pages 91-100
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe RNA molecular species synthesized in nuclei were com- pared by the DNA-RNA hybridization technique in normal rat liver and rat ascites hepatoma AH-130 cells. The nuclear RNA (n-RNA) of normal rat liver cells was characterized by a greater amount of AU-rich RNA sedimenting heterogeneously than n-RNA of hepatoma cells. The newly synthesized n-RNA of hepatoma cells contained about 50 % of ribosomal RNA while that of normal rat liver contained 30 %. The hepatoma cells seemed to synthesize the same RNA molecular species as rat liver cells but the RNA molecular species which migrated out of the nucleus into the cytoplasmic polysomal frac- tion were different. Polysomal RNAs in normal rat liver did not contain some RNA molecular species which existed in the hepatoma polysomal fraction, suggesting that the transport of n-RNA to the cytoplasm associated with polysomes was different between hepatoma cells and normal liver cells.View full abstractDownload PDF (997K) -
Shinji Matsumoto1977 Volume 2 Issue 2 Pages 101-109
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMitotic delay by UV-irradiation was examined in G2 or M phase in naturally synchronous plasmodia of Physarum polycephalum. The mitotic delay curve indicated a linear decrease against the time of irradiation in G2. Extrapolation ofthe delay line in G2 to zero delay gave an intersection point which probably coresponded to the transition point from G2to M, that is, the time of the signal for mitosis. The point was at 50 min prior to metaphase. The slope change of the delay curve suggests that UV-irradiation inhibits the production of a substance responsible for triggering mitosis rather than inactivate the function of a preexisting triggering substance. The delay was partially cancelled by adding the crude lysate of non-irradiated cells. This effect was strongest when the lysate wasfrom late G2 cells.View full abstractDownload PDF (844K) -
Hisao Yamaguchi, Shigehito Ishiguro, Yoshikane Oka, Hiroshi Miyamoto1977 Volume 2 Issue 2 Pages 111-118
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA selection method was developed using a specially designed culture flask that increased the yield of synchronous L-cells. As many as 1.5 × 106 cells of which 90 % were in mitosis were obtained after five cell harvests carried out at 1.5 h intervals. The cell populations consisted of 8.3% interphases, 9.6% prophases, 31.2% metaphases, 5.2% anaphases and 45.7% telophases. The fractions of metaphase and telophase were higher than fractions from exponentially multiplying cultures. Cells completed the subsequent cell cycle in 23 h. The cell cycle stages had the same durations as normal cultures. The storage of harvested cells for 12 to 18 h at 0°C caused a short delay in completion of the first mitosis, but exerted no significant prolongation of the subsequent cell cycle.View full abstractDownload PDF (2410K) -
Kosaku Izutsu, Hidemi Sato, Hiroshi Nakabayashi, Natsue Aoki1977 Volume 2 Issue 2 Pages 119-133
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMeiotic spindle and chromosome movements were studied during spermatocyte divisions in Chrysochraon japonicus and Trilophidia annulata with a sensitive polarizing microscope. When the nuclear envelope disintegrated, birefringent astral fibers invaded the karyoplasm pushing some chromosomes toward the mid-region of the developing spindle. During prometaphase the birefringence (BR) of the kinetochore fibers fluctuated, and fibers at this period often exhibited lateral oscillations. By full metaphase, the kinetochore fibers BR became stable. BR of the continuous fibers was rather weak throughout meiosis. During anaphase in most cells, the kinetochore fibers shortened at a constant rate of 0.7 μm per minute at 28°C. In some cells the rate of shortening slowed down in late anaphase. The overall spindle length increased during anaphase, although considerable fluctuations were observed. The number of microtubules per kinetochore fiber estimated from measured BR and fiber thickness using the Wiener equation was consistent with the direct count of microtubules on electron micrographs.View full abstractDownload PDF (1934K) -
Miyoko Kubo, Nobuaki Sawada1977 Volume 2 Issue 2 Pages 135-144
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe differentiation process of the Perinereis brevicirris spermatozoa was observed by the electron microscope to examine the mode of intercellular communication at different stages of synchronized germ cell differentiation. Spermatogonia in large clusters were framed by a thin cytoplasmic envelope and appeared to be divided into several blocks by cytoplasmic processes. Spermatogonia in one block were connected to each other by desmosomes and intercellular bridges. At the spermatocyte stage, the blocks in large clusters became independent small clusters from which cells detached by meiotic divisions. These cells showed neither connection with the cytoplasmic central mass nor cytoplasmic communications, except for desmosomes, and accordingly no synchrony was observed in cell differentiation. In spermatids, the smallest group was composed of four cells which were connected by a cytoplasmic bridge. During spermiogenesis, a filamentous acrosomal rod extended through the nucleus, and nuclear condensation followed. In spermatozoa, a dense material was observed in the intranuclear space near the central axis on the condensed chromatin. Mg2+-ATPase activity was found on the dense material. The functional significance of ATPase is discussed.View full abstractDownload PDF (12117K) -
Kinya Koizumi, Keiko Tamiya-Koizumi, Tatsuzo Fujii, Kiyohide Kojima1977 Volume 2 Issue 2 Pages 145-153
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSPhospholipid analyses were made on whole cells and isolated plasma membranes (PM) of six different lines of Yoshida ascites hepatoma and normal liver. The hepatoma PM had lower percentage levels of choline phosphoglycerides and phosphatidylinositol, and higher percentages of sphingomyelin, phosphatidylethanolamine and phosphatidylserine in total phospholipids than liver PM. Similar tendencies were observed in the whole cell phospholipids, although such trends were not observed in the mitochondrial or microsomal fractions. The lysophospholipid percentages in hepatoma PM were lower than those in liver PM. Hepatomas had higher percentage levels of plasmalogen in total phospholipids than normal liver, in both whole cells and PM. PM from island-forming hepatomas contained more plasmalogen than PM from their free-cell sublines. Localization of plasmalogen was observed in PM and certain intracellular organelles of island-forming hepatomas by histochemical plasmal reaction.View full abstractDownload PDF (2618K) -
Kozo Inaba, Akitaka Doi, Isamu Nisida1977 Volume 2 Issue 2 Pages 155-158
Published: 1977
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe cell growth inhibiting activity found in rat liver microsomal fraction was largely due to arginase but another factor seemed to partly influence the inhibition. The injection of the arginase-rich fraction isolated from liver microsomes into tumor-bearing mice prolonged the survival time of the animals.View full abstractDownload PDF (365K)
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