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Volume 6 (1981)
- Issue 4 Pages 301-
- Issue 3 Pages 201-
- Issue 2 Pages 93-
- Issue 1 Pages 1-
Volume 6, Issue 4
Displaying 1-11 of 11 articles from this issue
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Takashi Sekiya, Yoshiko Banno, Yoshinori Nozawa1981 Volume 6 Issue 4 Pages 301-312
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSUsing filipin, a sterol-specific polyene antibiotic, we examined the redistribution of cholesterol molecules present at an early stage of degranu-lation (release of heparin-protein complexes) in rat peritoneal mast cells with freeze-fracture electron microscopy. Isolated mast cells first were stimulated to undergo degranulation with compound 48/80 (1 μg/ml) for 3 sec, then were treated with a glutaraldehyde solution containing filipin (50 μg/ml) for 30 min. Freeze-fractures of the plasma membrane of these cells showed small depressions which lacked filipin-cholesterol complexes. These are the first recognizable membrane alterations and are suggested to correspond to the initial sites of fusion between the plasma and granule membranes. Subsequent-ly, these depressions became bulges. Filipin-cholesterol complexes are absent from the portion of the bulges in close contact with the plasma membrane, probably because the bulges have not yet fused with the underlying granule membrane. These complexes also were absent from the periphery of the two apposed membranes at exocytotic sites during fusion. Even after fusion was complete, no complexes appeared in the circumferential zone where the plasma membrane and the secretory granule membrane had fused. Our results suggest that membrane cholesterol is reorganized at the fusion sites between the plasma and granule membranes during mast cell secretion, and that this alteration in the organization of cholesterol in the plasma membrane represents an initial event during mast cell secretion. A hypothetical model for the sequential changes in the plasma membrane during degranulation is proposed.View full abstractDownload PDF (1479K) -
Shintaro Iwashita, Ichiro Yahara1981 Volume 6 Issue 4 Pages 313-327
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSUsing a sensitive method to determine the amount of fibro-nectin (FN), we investigated the release of cellular FN in C3H mouse fibro-blasts, which depends upon the progress of the cell cycle. Cells first labeled with [14C]leucine and arrested in confluent culture were trypsinized and re-plated in fresh medium containing [14C]leucine with or without 1 mM hydroxy-urea (HU). The cell number in the untreated culture increased 1.3-fold 36 h after replating, whereas HU-treated cells neither entered the S phase nor divided. The synthesis, turnover and rebinding of FN to cells were almost the same for both cultures. The amounts of FN released into the medium also were the same for untreated and HU-treated cultures. These results indicate that FN was not released into the medium specifically before or during the rounding up of mitotic cells. Immunofluorescence observations using a specific antibody directed against FN showed the presence of FN networks on the surface of the substratum, which surrounded the point at which mitotic cells were attached. In addition, for about half the population of mitotic cells no FN was detected on the cell surfaces. Because of these results, we suggest that when mitotic cells become round, they leave FN in networks on the substratum.View full abstractDownload PDF (1662K) -
Tetsuo Katsumoto1981 Volume 6 Issue 4 Pages 329-339
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSSimian virus 40 (SV40)-transformed macrophages, clonal line 28-12, and its subline, 28-12(Ara), were used to study morphological changes associated with their growth. Actively growing 28-12 cells were SV40 T-antigen-positive and had thick bundles of microfilaments, a few micro-tubules, and immature nuclei, whereas stationary 28-12 cells had no SV40 T-antigen or a markedly reduced amount of it, and possessed a network pattern of microfilaments similar to that of cultivated macrophages, many microtubules and mature nuclei. 28-12(Ara) cells had a low growth rate, a slightly reduced amount of SV40 T-antigen, a network pattern of microfilaments, significantly fewer microtubules and moderately mature nuclei.
These results suggest that the high growth rate, which is possibly induced by viral products, converts the microfilament distribution from a network to a bundle pattern, the microtubule assembly in the pseudopodia from large to small quantities and the nuclear profile from a mature to an immature one.View full abstractDownload PDF (10215K) -
Akira Mizoguchi, Tsuguo Mizuochi, Yoshiji Kitazume, Gakuzo Tamura, Aki ...1981 Volume 6 Issue 4 Pages 341-346
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effect of tunicamycin, a specific inhibitor of the bio-synthesis of the asparagine-linked sugar chains of glycoproteins, on spicule formation of sea urchin embryos was investigated. Formation of spicules of bizarre shape and abnormal birefringence preceded by disorganized primary mesenchyme cells was observed in the presence of the drug under a polarizing microscope.View full abstractDownload PDF (2477K) -
Yoshimasa Nishihara, Masanobu Miyahara, Kozo Utsumi1981 Volume 6 Issue 4 Pages 347-356
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effects of tetrachlorobiphenyl (TCB) isomers on the osmotic fragility and shape of human erythrocytes were examined. Low concentrations of 2, 3, 2', 3'-, 2, 4, 2', 4'-and 2, 5, 2', 5'-TCB protected erythrocytes from hypotonic hemolysis, but at high concentrations, these compounds greatly promoted hypotonic hemolysis. Along with the anti-hemolytic effect, the compounds caused alterations in cell shape that ranged from normal discocytes to cup-formed cells and to spherocytes. Thus, these compounds can be classified as cup-formers. The alterations in shape were brought about by conditions in which the membranes were protected from hypotonic hemolysis. The break point in the Arrhenius plot for hypotonic hemolysis was decreased by about 3°C when 2, 3, 2', 3'-TCB was added. Therefore, these compounds increase fluidity of the bilayer, which is clearly demonstrated by the ability of 2, 3, 2', 3'-TCB to lower the break point temperature, which enables it to protect erythrocytes from osmotic swelling. By contrast, 2, 6, 2', 6'-and 3, 4, 3', 4'-TCB neither protected erythrocytes from hypotonic hemolysis nor altered cell shape. The relation between these phenomena and chemical structure is discussed.View full abstractDownload PDF (2437K) -
Fumio Hanaoka, Kyosuke Nagata, Yoshinari Watanabe, Takemi Enomoto, Mas ...1981 Volume 6 Issue 4 Pages 357-365
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe have established procedures for the accumulation of an S phase population of FM3A cells grown in the mouse. Mice were kept for 5 days after intraperitoneal inoculation with 1 x 106 FM3A cells, then they were treated with 100 μg of 5-fluoro-2'-deoxyuridine for 16 h. When the FM3A cells were taken from the mice and cultured in vitro, more than 70% of the cells synthesized DNA, and the cell number increased 1.8-fold after 14 h. DEAE-cellulose column chromatography of the nuclear extract fraction showed that the synchronized cells contained about three times the activity for DNA polymerase a than that of random cells. Activity in the cytoplasmic fraction remained at the same level.View full abstractDownload PDF (748K) -
Katsuhiko Yamamoto, Akira Niwa, Yosihiro Yasumura1981 Volume 6 Issue 4 Pages 367-374
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSR-Y121B cells derived from a rat Reuber hepatoma cell line have been grown serially in arginine-and glutamine-deprived, ornithine-supplemented Eagle's minimum essential medium. This cell line has the biochemical machinery to synthesize urea. It produces urea from ornithine via the urea cycle pathway. The synthesis of urea depends on the concentration of ornithine and acetylglutamate. There was no definite amino acid found to be the urea nitrogen source in R-Y121B cells.View full abstractDownload PDF (827K) -
Akitaka Doi, Osamu Hatase, Masahisa Shimada, Tetuhide H. Murakami, Tom ...1981 Volume 6 Issue 4 Pages 375-383
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSSurface structures of the gill epithelia of a yellowtail, Seriola quinqueradiata were observed with a scanning electron microscope after ex-posure to sea bloom. The fish was on the verge of death 45 min after exposure in a circuit tank containing a quantity of plankton, including Gymnodinium. Morphological changes in the gill epithelia of the primary and secondary lamellae were observed on the afferent side. Pavement cells of the afferent side were swollen remarkably, but cells on the efferent side were intact. Chloride and mucous cells with many cellular extensions appeared in the epithelia of the afferent edge of the primary lamellae. Chloride cells were found on the interlamellar space of the secondary lamellae as well. These chloride and mucous cells, however, could not be seen clearly on gill filaments exposed to normal sea water.
The significance of morphological changes due to lower salinity and their relation to the toxic effects of plankton are discussed.View full abstractDownload PDF (938K) -
Shogo Nakamura1981 Volume 6 Issue 4 Pages 385-393
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe isolated two strains of Chlamydomonas mutants (RL-10, RL-11) which exhibit only flagellar-type beating and which always swim back-ward. Flagella from these two mutants were similar in that they maintained their flagellar-type beating over a wide range of Ca2+ concentrations after being demembranated and reactivated in the presence of Mg-ATP. The RL-11 flagellar axoneme changed its amplitude of beating at a Ca2+ concentration of ca. 10-6 M, whereas the RL-10 axoneme showed no sensitivity to Ca2+. In temporary dikaryons of RL-10 (plus mating type) and RL-11 (minus mating type), all four flagella could beat in the normal ciliary mode, evidence that the mutations in the two strains were complementary. Electron microscopy of thin-section specimens showed no structural alterations in the mutant flagella. Several alterations in the SDS gel electrophoretic patterns of the mutant ax-onemes were found.View full abstractDownload PDF (893K) -
Kazuhiko R.Utsumi1981 Volume 6 Issue 4 Pages 395-401
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe higher order structure of chromosomes of Raji cells has been investigated with a field emission type scanning electron microscope after the chromosomes had undergone surface-spreading. Metaphase chromosomes were seen as a mass of fibers about 336±42 Å in mean diameter with a range of 226 Å to 429 Å. Chromosome fibers had twisted loops with nodules. The organization of the fibers in the construction of the metaphase chromosomes was neither regular nor periodic. The kinetochore region was discernible as a clear constriction, but it had no characteristic structure except for several chromosome fibers parallel to the axis of the chromatids.View full abstractDownload PDF (855K) -
Kei Takahashi, Yutaka Tashiro1981 Volume 6 Issue 4 Pages 403-407
Published: 1981
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSPolyacrylamide gel electrophoretic analyses of the nucleosomal histone H1 from rat liver nuclei showed that mononucleosomes and dinucleo-somes, which were rapidly released from rat liver nuclei by digestion with DN-ase II, preferentially contained one subclass of histone H1 (H1B) and lacked another (H1A). In contrast, nucleosomes released by longer digestion had both H1A and H1B. The specific regions of chromatin which contain histone H1B seem to be more susceptibleto DNase II, thus nucleosomes containing histone H1B are released selectively from these regions.View full abstractDownload PDF (432K)
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