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Volume 7 (1982)
- Issue 4 Pages 295-
- Issue 3 Pages 193-
- Issue 2 Pages 91-
- Issue 1 Pages 1-
Volume 7, Issue 1
Displaying 1-9 of 9 articles from this issue
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Kazuhiro Nagata, Junji Sagara, Yasuo Ichikawa1982 Volume 7 Issue 1 Pages 1-7
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe found that the polymerization of actin was inhibited in the cytoplasm of D- line cells, derived from M1 line, which have lost their ability to differentiate to motile cells during a series of experiments designed to discover how contractile proteins work in the induction of cell motility in a myeloid leukemia cell line (Ml). Serial fractionation by DEAE chromatography, 55-80% saturated ammonium sulfate, Sephadex G150 gel filtration and hydroxylapatite chromatography gave an active fraction that inhibited the polymerization of skeletal muscle actin. This inhibitor (API) was trypsin sensitive, heat labile and had a molecular weight of about 71, 000. The API did not depolymerize F actin.View full abstractDownload PDF (705K) -
Tomoko Kozu, Tatsuo Yagura, Takeshi Seno1982 Volume 7 Issue 1 Pages 9-19
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSIn rapidly proliferating Ehrlich ascites tumor cells, DNA polymerase activity has been found which utilizes poly(dC) as a template without added primer. The DNA polymerase responsible for this activity and its stimulating factor were partially purified as reported previously (26). To obtain information on the role of this novel activity in DNA replication, subcellular location and developmental change were studied. The DNA polymerase activity in a crude extract prepared from Ehrlich ascites cells that utilizes single-stranded DNA was characterized by mixing it with purified DNA polymerase and by trypsin digestion. We thus obtained evidence that the activity in crude extract was the same as that of the purified enzyme. The activity in a subcellular fraction, prepared by the procedure using cytochalasin B induced enucleation, was determined. More than 98 % of the activity was found in the karyoplast. We then measured the levels of activity in the spleen and in cardiac muscle, both of which show the characteristic pattern of cellular proliferation during postnatal development. In both tissues, the levels of activity were correlated positively with the rate of DNA synthesis. These results suggest that this novel DNA polymerase activity participates in DNA replication.View full abstractDownload PDF (1197K) -
Akira Tamura, Kunihiko Morita, Tatsuzo Fujii, Kiyohide Kojima1982 Volume 7 Issue 1 Pages 21-27
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe lipid bilayer of the membrane of human erythrocytes from which most sialic acid residues on the outer surface had been removed was digested by phospholipase from outside the medium or treated by the incorpora-tion of exogenous amphiphilic lipid, then it was electrophoresed. After treat-ments that caused the additional exposure of the dissociable polar head group of the amphiphilic lipid to the outer medium, the electrophoretic mobility of the treated cells increased as the pH of the suspending medium rose. This show-ed that there was an increase in the negative charges in the immediate vicinity of the lipid bilayer surface of the membrane. The possible effect of the dissocia-tion of exposed head groups in the lipids on the morphology of the membrane is discussed.View full abstractDownload PDF (683K) -
Miyako H. Takegami, Michio Ito1982 Volume 7 Issue 1 Pages 29-38
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe cytological effects of hydroxyurea (HU), an inhibitor of DNA synthesis, were examined on mitotic and meiotic divisions in lily micro-sporocytes. Microsporocytes in premeiotic stages and meiotic prophase were cultured in vitro for discrete periods in the presence of the inhibitor at various concentrations. Hydroxyurea interfered with mitotic development if admini-stered to cells during the late S or early G2 phase of premeiosis, when cells undergo mitotic division by explantation. When applied during leptonema, the main effects were the suppression of meiotic development and the produc-tion of sticky chromosomes. The affected cells progressed through early pro-phase without showing any gross cytological abnormalities ; the inhibition of DNA synthesis by hydroxyurea during zygonema did not interfere with synapsis. On further culture, cells did not progress beyond prophase; but remained suspended in some stage of lateprophase. Chromosome stickiness was the response of cells cultured with hydroxyurea during pachynema for a prolonged period. The relevance of these observations to microsporocyte development is discussed.View full abstractDownload PDF (1672K) -
Yasunori Kanaho, Takashi Sato, Tatsuzo Fujii1982 Volume 7 Issue 1 Pages 39-48
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSPlatelet aggregation elicited by collagen or thrombin was inhibited by cepharanthine in a concentration-dependent manner. The in-hibition of thrombin-induced aggregation was correlated with the inhibition of arachidonate-release from the phospholipids of the membrane, notably from phosphatidylcholine.
The normal disc shape of the washed platelets with a few pseudopods was transformed to a sphere due to treatment with cepharanthine at a concentra-tion which considerably inhibited aggregation. Washing the cepharanthine-treated platelets with a calcium-free solution changed the spherical shape back to the disc shape and abolished the inhibition of aggregation.
These results suggest that cepharanthine disturbs the plasma membrane due to its incorporation into the membrane, which results in the change in shape of the membrane and the inhibition of aggregation.View full abstractDownload PDF (1014K) -
Yasuhiro Yamaguchi, Yoshihiro Asakura, Seiji Matsumoto, Masako Osumi, ...1982 Volume 7 Issue 1 Pages 49-59
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA method for the mass isolation of polytene nuclei of T. akamushi is described. Isolated nuclei were studied with light and electron microscopy, SDS-gel electrophoresis and DNA fragment analysis after micrococcal nuclease digestion. Histones were the major components of the chromosomal proteins. A number of non-histone proteins with a wide range of molecular weights were present, but their quantities were relatively low. The sizes of the DNA fragments cleaved by micrococcal nuclease suggested the presence of nucleosomal structures in the polytene chromosomes. The size of the DNA repeat was about 200 base pairs.View full abstractDownload PDF (1096K) -
Hiroya Kamei1982 Volume 7 Issue 1 Pages 61-70
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe relationships between anchorage-independent growth and cytochalasin B (CB)-induced multinucleation in cloned BHK-21 cells and their chemical transformants were studied. Clones of BHK-21 cells derived from flat colonies grown on plastic, that were selected for their extremely low growth on agar plates (Ag- clones), had low CB-multinucleated cell rates (% of cells with more than 3 nuclei), whereas parent BHK-21 cells could grow on an agar plate and had high CB-multinucleated ceil rates. Transformants (agar colonies) were induced in a Ag- clone (L77) after treatment with MNNG and several days of expression time. At least two types of transformants were distinguishable by their agar colony morphologies; globular and dispersing. The clones derived from the transformants retained their ability to grow on an agar plate. Most showed increased CB-multinucleated cell rates when compared to parent L77 cells irrespective of the agar colony type. These results indicate that anchorage-independent growth and CB-multinucleation are closely related in BHK-21 cells and their clones, and that both properties can be induced simultaneously during chemical transformation.View full abstractDownload PDF (960K) -
Tatsuichi Iwamura, Kenji Katoh, Takao Nishimura1982 Volume 7 Issue 1 Pages 71-86
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe chloroplast DNA (chDNA) in the unicellular green alga, Chlorella, consists of at least two DNA species. The major component (ch-DNAM) has the corrected "practical density" in CsCl of 1.7100 gm/ml, which is almost the same as the value for major nuclear DNA (nDNAM); the minor component has the value 1.6860 gm/ml. During the cell cycle effected by synchronous culture under a light-dark regimen, chDNA was synthesized near the middle of the light phase before nDNA synthesis. The content of chDNA quadrupled during the synthetic period. This fact corresponds to the observations that four chloroplasts can be found in large cells at about the end of the light phase and four daughter cells are produced from one mother cell at the end of the cell cycle. The algal chDNA was labelled actively with 14CO2 or [3H]thymidine during its synthesis.
To determine whether chDNA replicates semi-conservatively, we examined the density-labelling and density-shift of chDNA during its synthesis in the cell cycle. Since chDNAM has almost the same buoyant density as that of nDNAM in CsCl, we made CsCl equilibrium density gradients in preparative ultracentri-fuge on the total cell DNA containing chDNA which had been preferentially labelled with [3H]thymidine or 14CO2 during its synthesis. We here report the successful demonstration of the semi-conservative mode of replication in chDNAM, and discuss the remarkable characteristics of this algal chDNA.View full abstractDownload PDF (3770K) -
Naoyuki Miura, Tsuyoshi Uchida, Yoshio Okada1982 Volume 7 Issue 1 Pages 87-90
Published: 1982
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSSeven hybridomas that produce monoclonal antibodies to HVJ proteins were obtained. Three produce antibodies that react with HN protein, one an antibody that reacts with F protein, one an antibody that re-acts with NP protein and two, antibodies that react with P protein. Some properties of these antibodies are described.View full abstractDownload PDF (2364K)
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