All issues
Volume 6 (1981)
- Issue 4 Pages 301-
- Issue 3 Pages 201-
- Issue 2 Pages 93-
- Issue 1 Pages 1-
Volume 6, Issue 3
Displaying 1-12 of 12 articles from this issue
- |<
- <
- 1
- >
- >|
-
Differential Heat Treatment of the Nitella Internodal Cell and Its Relation to Cytoplasmic StreamingJames C. W. Chen, Noburo Kamiya1981 Volume 6 Issue 3 Pages 201-207
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCytoplasmic streaming in internodal cells of Nitella was reversibly or irreversibly stopped by supraoptimal temperatures depending on the temperature and duration of incubation. To analyze the effects of high temperature on the streaming endoplasm and on the stationary cortical layer, the two were temporarily separated by a method of centrifugation developed by the authors (2). Streaming resumed when the cortex alone was heat-treated at 47.5°C for 3 min while the endoplasm was kept intact. In the reciprocal case, no streaming was observed. This demonstrates that one or more factors, that are heat-labile and essential for the streaming to occur, must reside in the endoplasm and not in the cortex. This result supports the idea that myosin, which is far more labile to heat than actin, is located in the endoplasm.View full abstractDownload PDF (760K) -
Akira Sono, Kengo Sakaguchi1981 Volume 6 Issue 3 Pages 209-216
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe suppression by protein synthesis inhibitors of chemically or physically induced sister chromatid exchanges (SCEs) in the euchromatin and heterochromatin of individual chromosomes, as well as in each cell cycle phase, were analyzed for Chinese hamster cells. Suppression in the euchromatin was more prominent than in the heterochromatin, and depended on the agents and chromosomes involved. Cell cycle studies demonstrated the dependence of this effect on DNA replication. The relationships among sister chromatid exchange, cycloheximide-suppression and DNA replication are also discussed here.View full abstractDownload PDF (756K) -
Tetsuko Noguchi, Kenji Tanaka, Katsumi Ueda1981 Volume 6 Issue 3 Pages 217-229
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSFreeze-fracture replicas of the cisternal membranes of dictyo-somes, large vesicle (LV) membranes and plasma membranes in the green alga, Micrasterias crux-melitensis, were examined by electron microscopy. Intra-membrane particles were evenly distributed in the cisternal membranes in resting cells. In growing cells, the particle density decreased from the centre to the periphery of the cisternal membranes and was greatly diminished at the vesiculated parts. The particle density in LV membranes was about twenty percent that in cisternal membranes, but equivalent generally in the plasma membranes of growing daughter semicells. The possibility of the direct supply of LV membranes to the plasma membrane is discussed. In the plasma mem-branes of fully grown cells, rosette complexes with a hexagonal array were observed. Each rosette consisted of six particles. These complexes were assumed to correlate with microfibril formation in the cell wall.View full abstractDownload PDF (2051K) -
Hiroko Hama-Inaba, Takeshi Tanaka, Koki Sato1981 Volume 6 Issue 3 Pages 231-244
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe temperature-sensitive mutant, ts 39, has been shown to undergo micronucleation upon exposure to a non-permissive temperature (39°C), a phenomenon which resembles micronucleation induced by colchicine. Ts 39 cells, however, have the same sensitivity to colchicine as their parent cells. The amount of colchicine-binding activity of intracellular materials in ts 39 cells cultured at a permissive temperature (33.5°C) was essentially equal to that for parent cells, and the amount after exposure to 39°C (0-3 days) was directly proportional to the number of viable cells. These results suggest that both the nature and amounts of tubulin in ts 39 cells do not differ from those in the parent cells.
The morphological alteration of ts 39 cells preceding micronucleation was studied using adhering cells derived from ts 39. The nuclei of almost all cells were deformed and lobulated, and some of them appeared to segment into multimicronuclei. Mutant cells in suspension showed similar morphological changes. Cell cycle and cytofluorometric studies were performed and the results suggest that multimicronucleation starts during the period of mitotic and G1-phase after exposure to non-permissive temperatures.View full abstractDownload PDF (10399K) -
Seto-Ohshima Seto-Ohshima, Nobuyuki Wakayama, Takehiko Amano1981 Volume 6 Issue 3 Pages 245-253
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSLocalization and properties of concanavalin A-binding sites (CABS) on the cells of the clonal muscle cell, L6 were investigated by two methods. Using fluorescent concanavalin A (Con A), only occasionally could even faint fluorescence be detected on myoblasts in young cultures. As proli-feration proceeded, the intensity of fluorescence increased and became localized on the boundaries where the cells came into contact with each other. This distribution was not affected by the treatment with EGTA, triton X-100 or colchicine, suggesting that neither the Ca2+, lipid matrix nor the microtubule contributed to the maintenance of the distribution. Cytochalasin B (CB), however, caused the CABS to rearrange as well as morphological changes in the cells. Using Con A and hemocyanin, very low CABS densities were found on young myoblasts. In contrast to the results with fluorescent Con A, dense labelling was found on over the entire cell surface of myoblasts in confluent cultures. Many myotubes had CABS but densities varied from cell to cell. The effects of CB in localizing CABS were also observed by the hemocyanin method which demonstrated that most CABS on L6 cells were affected directly and/or indirectly by CB.View full abstractDownload PDF (8035K) -
Tsuneyoshi Kuroiwa, Shigeyuki Kawano, Takahito Suzuki, Soryu Nishibaya ...1981 Volume 6 Issue 3 Pages 255-262
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSEthidium bromide has been shown to be useful as a probe to observe mitochondrial nuclei (mt-nuclei) in the moving mitochondria in live cells. In Physarum polycephalum, a double staining technique, using ethidium bromide and dimethylaminostyrylmethylpyridiniumiodine, detects both changes in mitochondrial distribution and orientation, and changes in the shape of the mt-nucleus during the mitochondrial division cycle. The results show that when dumbbell-shaped mitochondria in live cells divide to form daughter mito-chondria, each mt-nucleus also divides, separating into the daughter mito-chondria.View full abstractDownload PDF (4826K) -
Sadahiro Watanabe, Yasuko M.Morimoto, Noriyuki Shiraishi, Akiyoshi San ...1981 Volume 6 Issue 3 Pages 263-267
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effects of biscoclaurine alkaloids on ADP-or collagen-induced platelet aggregation were examined as alkaloids are known to inhibit lipid peroxidation (1, 7) and stabilize labilized biomembranes (8, 9). Most alkaloids greatly inhibit the platelet aggregation induced by ADP or collagen. This inhibition was concentration dependent and significantly higher where there was collagen aggregation.View full abstractDownload PDF (447K) -
Hisao Miyata, Machiko Miyata, Michio Ito1981 Volume 6 Issue 3 Pages 269-277
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe relationship between cell size and division delay due to a single heat shock has been investigated in individual cells of Schizosaccharomyces pombe. The heat shock was applied to an asynchronously growing culture, to a hydroxyurea-synchronized culture in which the cell size was larger than normal, and a hydroxyurea-synchronized culture incubated in a starvation medium which could divide twice but barely elongated. After the heat shock was applied, cells were transferred to a small chamber and observed continuously.
Regardless of the experimental situation, the period from the end of heat treatment to cell division was negatively proportional to cell size at the end of heat shock, except that the time from the end of heat shock to division in cells larger than a particular size was consistently minimal. In addition, cells grown in a rich medium, regardless of the cell size at the end of heat shock, divided at the critical size which had been found for exponentially proliferating cells, but cells larger than the particular size divided above the critical size. Homeo-stasis at division also was maintained in shocked cells grown in a rich medium.
Our results are explained by the "set-back" hypothesis (22) and are discussed in relation to our "effector-producer" hypothesis (14).View full abstractDownload PDF (804K) -
Keiji Okuyama, Noriyuki Sagata, Koichiro Shiokawa, Kiyotaka Yamana1981 Volume 6 Issue 3 Pages 279-282
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSXenopus oocytes and eggs were fractionated into post-mito-chondrial supernatant and pellet fractions, after which the content of poly(A) sequences and their size distribution were analyzed. It was found that, while the poly(A) content in the post-mitochondrial supernatant fraction remained constant during oocyte maturation, that in the pellet fraction decreased signi-ficantly without any change in its sequence length. This decrease in poly(A)content as has recently been reported to occur during oocyte maturation can thus be confined to the pellet fraction.View full abstractDownload PDF (400K) -
Yoshiki Shiba, Taira Enomoto, Yasuto Sasaki, Yoshinobu Kanno1981 Volume 6 Issue 3 Pages 283-287
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effects of lectins on hydra (Hydra japonica) were investi-gated in order to clarify the mechanics of its feeding response. Concanavalin agglutinin (Con A) induced rapid and prolonged tentacle contractions, but did not induce marked contractions of the body column. Lotus tetragonolobus agglutinin (Lotus A) and Ulex europeus agglutinin-1 (UEA-1) had effects similar to those of Con A, but rather induced the tentacles to make movements of a contracting-extending nature. Other lectins, including peanut agglutinin, soybean agglutinin, Dolichos biflorus agglutinin, wheat germ agglutinin, poke-weed mitogen, red kidney bean agglutinin and succinyl Con A did not cause contractions. Discontinuing the Con A, Lotus A or UEA-1 resulted in an extension of previously contracted tentacles. Lectin-induced contractions were rapid and reversible. The above results suggest that the binding by lectins to mannose-and fucose-residues of cell surfaces causes hydra tentacles to rapidly contract.View full abstractDownload PDF (546K) -
Hiroshi Sakagami, Senwa Unten, Kunio Konno1981 Volume 6 Issue 3 Pages 289-293
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSIn order to investigate the relationship between mouse myeloid leukemia (M1) cell differentiation and growth potential, M1 cells were differ- entiated to various extents by treatment with 0-3 × 10-5 M dexamethasone. When the strength of the induced lysozyme or phagocytic activity was plotted as a function of DNA synthesis, a negative correlation was found. The induc- tion of differentiation depended more on the specific rate of DNA synthesis than on the concentration of dexamethasone
The present work, together with previous results (8), suggests the high probability that differentiation-associated properties are almost exclusively expressed by non-replicating M1 cells.View full abstractDownload PDF (420K) -
Paul J.Higgins1981 Volume 6 Issue 3 Pages 295-300
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effect of the polar solvent dimethylsulfoxide on the synthe-sis and secretion of albumin and alpha-fetoprotein was studied in an establishe line of mouse hepatoma cells (BW1). Incubation of BW1 cells with dimethyl-sulfoxide led to a marked enhancement in the cellular content of albumin and alpha-fetoprotein (42 and 94 % for albumin and 118 and 154 % for alpha-fetoprotein in 0.5 and 1 % dimethylsulfoxide-containing growth medium, respectively) as well as in the extra-cellular accumulation of these proteins.The albumin contribution to total BW1 cell-associated protein increased with exposure to increasing concentrations of dimethylsulfoxide in the medium.In contrast, while the alpha-fetoprotein content, per 106 hepatocytes increased as a function of dimethylsulfoxide concentration, synthesis of alpha-fetopro-tein relative to total cellular protein was maximal in 0.5 % dimethylsulfoxide and was not further stimulated upon exposure of the cells to higher concentra-tions of the polar solvent.View full abstractDownload PDF (580K)
- |<
- <
- 1
- >
- >|