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Volume 9 (1984)
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Volume 9, Issue 4
Displaying 1-9 of 9 articles from this issue
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Small Nuclear RNA-Protein Complex Anchors on the Actin Filaments in Bovine Lymphocyte Nuclear MatrixHiroshi Nakayasu, Kiyoshi Ueda1984 Volume 9 Issue 4 Pages 317-325
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWhen the nuclear matrix from bovine lymphocytes was digest-ed by RNase-depleted trypsin, the bulk of the matrix proteins, except actin, were hydrolyzed. The digestion left rapidly sedimented spherical structures (trypsin-treated nuclear matrix), which mainly were composed of actin (Nakayasu, H. and K. Ueda. Exp. Cell Res. 143, 55-62, 1983). Almost all the small nuclear RNAs of the original nuclear matrix remained associated with these actin spheres after trypsin digestion.
By sonication, the small nuclear RNPs (snRNPs) in both untreated and trypsin-treated nuclear matrices were solubilized in association with proteinous filaments of various size. The sedimentation pattern of these snRNP complexes was not changed by the digestion of the bulk of the proteins. The snRNP complex was adsorbed on rabbit muscle myosin-Sepharose then eluted by the addition of 5 mM ATP. We concluded that snRNPs are associated with actin filaments in the nuclear matrix of bovine lymphocytes.View full abstractDownload PDF (9304K) -
Kouichi Yamada, Fumio Hanaoka, Hirohisa Kato, Masa-atsu Yamada1984 Volume 9 Issue 4 Pages 327-336
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA cell lysate system by which DNA repair (unscheduled) syn-thesis induced by DNA damaging agents can be measured at high sensitivity as previously reported (9, 18) was characterized. Time-course experiments in which the in vivo incubation time with hydroxyurea and arabinofuranosyl cytosine after UV irradiation was changed suggested that the number of single strand gaps increased in the presence of these drugs. Alkaline sucrose density gradient analysis of prelabeled DNA revealed that the repair apparatus in the drug-treated cells was not irreversibly impaired. Product DNA in this lysate system was compared with that of an in vitro replication system on alkaline CsC1 equilibrium density gradient, and the results showed that DNA synthesis in the lysate system was "repair-type" synthesis. When the cells were labeled with 5-bromo-2'-deoxyuridine (BrdUrd) in vivo and then labeled with [3H] dTTP in vitro, the photolysis of BrdUrd-labeled DNA decreased the molecular weight, indicating that DNA synthesis in the cell lysate was a continuation of DNA repair in vivo.View full abstractDownload PDF (1130K) -
Akiko Seto-Ohshima, Satoko Kitajima, Mamoru Sano, Kanefusa Kato, Akira ...1984 Volume 9 Issue 4 Pages 337-344
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCalmodulin is a small, acidic, calcium-binding protein thought to regulate many cellular functions. In the brain of the adult mouse, calmodulin was found immunohistochemically to localize mainly in the neurons. In the developing brain, the immunoreactivity to anti-calmodulin antibody appeared early in the cells in the low brain stem but late in the cerebral cortex, hippo-campus, and cerebellum, except for the deep cerebellar nuclei. The cells in the major proliferative layer present during early development, such as the matrix cells in the cerebral cortex and the cells in the external granular layer in the cerebellum, did not show the immunoreactivity. In the cerebral cortex, the migrating cells and the cells in the cortical plate were also negative while the deep cortical cells, which had probably settled in their final position, became positive. The comparison of these results with the immunohistochemical appearance of neuron specific enolase, a characteristic protein in the brain, suggested that calmodulin appeared with some maturation of the neurons as neuron specific enolase.View full abstractDownload PDF (1013K) -
Yoshihiro Tsutsui, Shinsuke Saga, Munemitsu Hoshino1984 Volume 9 Issue 4 Pages 345-355
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMonoclonal antibodies were prepared from mice that had been immunized with the nuclear matrix from chick embryonal erythrocytes. Seven stable clones were obtained by an ELISA that used nuclear lysate as the solid phase. Six clones of them reacted with the nuclear matrix, and one reacted with nuclear components other than the matrix. Immunoblotting showed that one clone recognized the 72K polypeptide, two clones recognized the 69K poly-peptide and three clones recognized both the 69K and 44K polypeptides. Indirect immunofluorescence that used antibodies to the nuclear matrix showed homogenous nuclear fluorescence in cultured chick embryonal fibro-blasts, and intense fluorescence was present in the peripheral part of the nucleus in thin-sectioned chick emblyos. Only weak nuclear fluorescence was seen in fibroblasts from humans and rats when two of the antibodies which recognized only 69K polypeptide were used. The rest of the antibodies to the nuclear matrix produced no nuclear fluorescence in human and rat fibroblasts. The metaphase-rich population of chick embryonal fibroblasts were stained diffusely over the entire cytoplasm, but not the chromosomes, when antibodies to the nuclear matrix were used. These results indicate that monoclonal antibodies we prepared are directed to the major proteins of the nuclear matrix that correspond to the lamin A and B defined in rat liver.View full abstractDownload PDF (1096K) -
Koozi Matuoka, Youji Mitsui, Sei-itsu Murota1984 Volume 9 Issue 4 Pages 357-367
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSPrevious studies showed that cell surface heparan sulfate (HS) is involved in density-dependent growth regulation of normal human cells. In this study the effects of HS on proliferation of transformed cells were studied in vitro. Exogenously added HS prepared from normal tissues (rat kid-ney and bovine kidney) enhanced growth of transformed human and animal cells (gamma ray-or virus-transformed WI-38, and HeLa cells and chemically induced mouse hepatoma cells), but inhibited that of normal human and animal cells (WI-38, 3T3, and rabbit liver cells). HS was less effective on growth of both normal and transformed human cells at higher cell density. Although the exogenous HS did not bind to cells tightly, HS was found to affect cell growth not by modulation of growth-related substances in the medium, but through contact with the cell surface. HS preparation from tumour cells (mouse hepatoma cells) exerted similar effects on cell growth. Heparin, structurally similar to HS, inhibited growth of both normal and transformed human cells. These findings suggest that : 1. HS plays a particular function in contact regulation of cell proliferation. 2. Transformation-related changes in the structure of HS molecules do not much affect the function of HS. 3. The cellular transformation, however, is accompanied by alteration in the growth-regulating system sensitive to extracellular HS.View full abstractDownload PDF (1180K) -
K. Shiokawa, A. Saito, H. Kageura, K. Higuchi, K. Koga, K. Yamana1984 Volume 9 Issue 4 Pages 369-380
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDorsal, ventral, animal and vegetal half-embryos of Xenopus laevis were isolated at the 8-cell stage, and their synthesis of protein examined during 12 h of culture. The kinetics of the uptake and incorporation of [35S]-methionine did not differ greatly among the four kinds of half-embryos. Two-dimensional gel electrophoreses showed that there were no detectable differences in the pattern of protein synthesis for the four types of half-embryos, at least during the first 6 h of culture which covered the period from the cleavage to late blastula stage. The patterns, however, changed greatly, espe-cially between those of the animal and vegetal half-embryos, during the latter 6 h of culture which covered the period from the early gastrula to early neurula stage.
These results are evidence that equal qualitative and quantitative maternal mRNA-dependent protein synthesis takes place in the four types of embryonic regions, including the vegetal half-embryos, although later in the post-blastular stages, syntheses of region-specific proteins start that are dependent on new genome expression.View full abstractDownload PDF (1270K) -
Takashi Sekiya, Yoshinori Nozawa1984 Volume 9 Issue 4 Pages 381-389
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effect of the local anesthetic dibucaine on the membrane ultrastructure of sterol-manipulated Tetrahymena pyriformis (NT-1 strain) was studied by freeze-fracture electron microscopy. Dibucaine-treated, ergosterol-replaced Tetrahymena cells had marked alterations in their plasma membranes. IMP-free small depressions (exoplasmic fracture face) and protrusions (protoplasmic fracture face) were formed on the plasma membranes which was in contact with the outer alveolar membrane. In addition, large IMP-free surface "blebs" covered with hexagonally-arranged depressions and protrusions ap-peared on both the plasma and outer alveolar membranes. These "blebs" were pinched off when the membranes were severely affected.
Our previous study (28) demonstrated that the plasma membrane of dibucaine-treated native Tetrahymena cells that contain tetrahymanol showed vertical displacement of its intramembranous particles and that subsequently a smooth, flat surface appeared. Therefore, the structural changes in ergosterol-replaced membranes produced by dibucaine differ strikingly from changes in the native membranes. The remarkable difference in the ultrastructural de-formation of the plasma membrane probably is due to a difference in the membrane lipid composition induced by sterol-manipulation.View full abstractDownload PDF (1148K) -
Hiroshi Nakada, Shiro Matsuura, Takaya Sawamura, Yutaka Tashiro1984 Volume 9 Issue 4 Pages 391-406
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDirect ferritin immunoelectron microscopy was used to visualize the asialoglycoprotein receptor in various rat liver subcellular fractions. The cytoplasmic surfaces of cytoplasmic organelles such as the rough and smooth microsomes, Golgi cisternae and lysosomes showed hardly any ferritin label exception for the slight labeling of secretory granules found mainly in the light Golgi fraction (GF1). Occasionally, however, open membrane sheet structures, smooth vesicular or tubular structures heavily labeled with ferritin, were present in all these subcellular fractions. These structures probably cor-respond to fragmented sinusoidal or lateral hepatocyte plasma membranes recovered to these subcellular fractions. When the limiting membranes of the secretion granules were partially broken by mechanical force, a number of ferritin particles frequently were seen attached in large clusters to the luminal surface of the membrane, the cytoplamsic surface of the corresponding domain being slightly labeled. These observations are strong evidence that the receptor protein is never translocated vertically throughout the intracellular transport from ER to plasma membrane via Golgi apparatus and from plasma membrane back to trans-Golgi elements and also in lysosomes, always exposing the major antigenic sites to the luminal or extracellular surface and the minor counter-parts to the cytoplasmic surface of the membranes. The receptor protein also is suggested to be concentrated in clusters on the luminal surface of secretion granules when they form on the trans-side of the Golgi apparatus.View full abstractDownload PDF (2249K) -
Tatsuzo Fujii, Kinya Koizumi, Keiko Tamiya-Koizumi, Kiyohide Kojima1984 Volume 9 Issue 4 Pages 407-410
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSCell electrophoresis of erythrocytes taken from AH 7974 hepatoma-bearing rats showed a marked decrease in the surface negative charge, as represented by a decrease in cell mobility. This change in the erythrocyte membrane began during the stationary phase of growth of transplanted tumor cells and became more pronounced in the late phase, during which time a marked decrease in the amount of sialidase-sensitive sialic acid present in the plasma membrane also took place. The erythrocytes of AH 7974F-bearing rats (which died from tumor growth much earlier than the AH 7974-bearing rats) had a similar, but less marked, decrease in their electrophoretic mobility and in the amount of sialidase-sensitive sialic acid present. These erythrocytes all had somewhat abnormal cell morphology, their shapes being slightly spherocytic.View full abstractDownload PDF (339K)
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