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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 2
Displaying 1-10 of 10 articles from this issue
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Noriyuki Sagata, Takahiro Nakahash, Koichiro Shiokawa, Kiyotaka Yamana1978 Volume 3 Issue 2 Pages 71-78
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSPoly(A)-containing RNA synthesis was studied in isolated cells from Xenopus laevis embryos at various stages of early development. Sedimentation analysis revealed little stage-dependent differences in the distribution; the size was heterogeneous and ranged from >40S to 18S, with an average of 25S (ca. 1.4 × 106 daltons). The total amount of newly synthesized poly(A)-containing RNA increased sharply as development proceeded. On a per-cell basis, however, the synthesis of poly(A)-containing RNA was much more active in blastula cells than in later embryonic cells.View full abstractDownload PDF (769K) -
Richard C. K. Yen, Morgan Harris1978 Volume 3 Issue 2 Pages 79-88
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSChloramphenicol resistance, a dominant marker, is readily transferred between Chinese hamster cells by fusing enucleated cytoplasts from resistant cells to a sensitive recipient strain. Isolation of cytohybrids depends on complementary selection for recessive characteristics present in recipient cells, e.g. resistance to bromodeoxyuridine. Sources of background variation in this system have been examined to determine the efficiency of cytoplasmic marker transfer. The frequency of mutants resistant to both chloramphenicol and bromodeoxyuridine was minimal in the parent strains used. Dual resistance was found to arise, however, by segregation within hybrids formed between nucleated cells present as contaminants in cytoplast fusion mixtures. Background variation may also simulate cytoplasmic transfer of nuclear markers from donor cells (e.g. resistance to ouabain). Cytohybrids resistant to both ouabain and chloramphenicol were in fact isolated from cytoplast fusion mixtures by selection with ouabain and bromodeoxyuridine. Such variants appeared to originate by mutation to ouabain resistance in recipient cells followed by cytoplasmic transfer of the chloramphenicol resistance marker.View full abstractDownload PDF (1006K) -
Syoichi Yamashita, Shigeru Okada, Keiki Hayashi(Fang), Yuji Baba, Sati ...1978 Volume 3 Issue 2 Pages 89-93
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe chromosomes were counted in cells of erythroid bone marrow and spleen of anemic mice, rats and rabbits. Diploid chromosome numbers were evident in most observed cells; however in a few cells, a hypo-ploid state was observed. The G-band karyotype did not revealed a regular absence of chromosomes. This suggests that the hypoploid number is an artifact resulting from inadequate chromosome preparation. The data indicate that in the mouse, rat and rabbit, the number of erythroblast chromosomes is main-tained at diploid level through the nucleated period and is not reduced in differentiation.View full abstractDownload PDF (343K) -
Tadahiro Shiomi, Koki Sato1978 Volume 3 Issue 2 Pages 95-102
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA temperature-sensitive mutant (ts2) of murine leukemic L5178Y cells accumulates aberrant mitotic cells and subsequently, multinucleate cells upon exposure to a restrictive temperature. Temperature-shift experiments using synchronized cell populations demonstrate that the execution point of ts2 cells is located between the early and mid S phase in the cell cycle. Mutant cells can achieve cell division when they are shifted down by the time of karyokinetic stage. However, multinucleate cells, once formed, are unable to undergo cytokinesis even though transferred to a permissive temperature. Cytofluorometric analysis indicates that unequal chromosome distribution among daughter nuclei takes place during multinucleation. The mechanism of defective karyo-and cyto-kinesis in ts2 cells is discussed.View full abstractDownload PDF (748K) -
Koichi Igarashi, Shuichi Ikeyama, Masao Takeuchi, Yukio Sugino1978 Volume 3 Issue 2 Pages 103-112
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMorphological changes in a cell line from rat glioma induced in vitro by exposure to dibutyryl adenosine cyclic 3', 5'-monophosphate (db-cAMP) and other agents were studied. Db-cAMP, adenosine cyclic 3', 5'-monophosphate (cAMP) plus theophylline or cholera toxin plus theophylline caused shrinkage of parts of the cytoplasm and converted apparently immature cells to cells with oligodendroglial or astroglial morphology. This morphological alteration induced by db-cAMP proceeded rapidly and was completed within an hour. The morphological alteration induced by db-cAMP and cAMP was reversible, but that mediated by cholera toxin was not reversible. Cytochalasin B also induced a morphological alteration similar to that induced by db-cAMP. Agents such as colcemid counteracted the effects of db-cAMP, cAMP and cholera toxin. These findings suggest that the intra-cellular level of cAMP may affect the organization of microtubules and resultin inducting morphological changes in this glial cell line.View full abstractDownload PDF (997K) -
Teruo Shimmen1978 Volume 3 Issue 2 Pages 113-121
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe rate of cytoplasmic streaming (v) was measured with reference to intracellular ATP and Mg2+ concentrations in tonoplast-free cells prepared by replacing the cell sap with EGTA-containing medium. The relation of v versus [ATP]i was a rectangular hyperbola. The ATP concentration for half saturation of v was 0.08 mM in Nitella axillaris and 0.06 mM in Chara corallina. From the results it is concluded that ATP is saturated for cytoplasmic streaming in normal cells, since the ATP concentration in the normal cytoplasm is about 0.5 mM. The relation between [Mg2+]i and v differed from that between [ATP]i and v. Stable cytoplasmic streaming was observed only when [Mg2+]i was equal to or higher than [ATP]i. The inhibition of cytoplasmic streaming by depletion of ATP was completely reversible but that by depletion of Mg2+ was irreversible. ADP supported streaming. This may be explained by assuming that ATP was synthesized from ADP by the action of adenyl kinase in the cell.View full abstractDownload PDF (890K) -
Masazumi Sameshima, Tokeo Muroyama, Yohichi Hashimoto, Takuzo Yamada1978 Volume 3 Issue 2 Pages 123-128
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSIn axenic strains of Dictyostelium discoideum, approximately one-fourth of vegetative amoebae were multinucleated throughout the growth phase, and synchronous mitosis were observed in these cells. In contrast to vegetative amoebae, all spores of these strains were mononucleated. The percentage of multinucleated amoebae in strain A-3 increased to nearly 70 % when the temperature was raised to 27°C from 22°C, but it decreased during prolonged incubation at 27°C. Karyokinesis proceeded at a constant rate even at 27°C. These results indicate that cytokinesis in this strain is not co-ordinated with karyokinesis. The number of multinucleated cells was drastically reduced in amoebae grown on both live and dead bacteria. Polystyrene latex particles, the diameter of bacteria, did not affect the rate of production.View full abstractDownload PDF (636K) -
Tetsuo Ueda, Yonosuke Kobatake1978 Volume 3 Issue 2 Pages 129-139
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSVariations in the surrounding temperature altered membrane activities at the critical temperature, Tc=15°C in plasmodium of the true slime mold Physarum polycephalum. Changes in the membrane and zeta potentials, which were induced by chemical stimuli, decreased when the temperature decreased below Tc. The adsorption energy of a -CH2- group on the membrane changed discretely by about 100 cal/mol at Tc. Decreasing the temperature sharply diminished the extension of psuedopodia by a factor of 1/10 at TC, while the motive force of protoplasmic streaming remained con-stant. This suggests that the formation of pseudopodia and the generation of motive force are different functions in ameboid motility. Results indicate that the surface membrane of the plasmodium undergoes a conformational change at Tc. The mechanisms of chemoreception and motility in plasmodium are discussed.View full abstractDownload PDF (997K) -
Shogo Nakamura, Ritsu Kamiya1978 Volume 3 Issue 2 Pages 141-144
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSFlagellar motility was studied in detergent-treated cells of Chlamydomonas with a dark-field microscope equipped with high-powered illumination. Flagella tended to split into two or three fibers in the presence of ATP and detergent. Some of split fibers showed oscillatory bending motion.View full abstractDownload PDF (343K) -
1978 Volume 3 Issue 2 Pages e1
Published: 1978
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDownload PDF (11K)
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