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Volume 9 (1984)
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Volume 9, Issue 3
Displaying 1-10 of 10 articles from this issue
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Nobuyoshi Shimizu, Yoshiko Shimizu, Keith Miskimins1984 Volume 9 Issue 3 Pages 203-212
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe have conjugated epidermal growth factor (EGF) with the A subunit of ricin (RICa) via a dithiopropionyl linkage. The EGF-RICa conjugate was competitive with [125I]EGF for binding to cell surface EGF receptors. Entry of the conjugate into cells was seen within 10 min at 37°C and inhibition of protein synthesis was seen within 90 min. The blockage of protein synthesis continued for more than 20 h in sensitive cells. Protein synthesis in EGF receptor-deficient cells was not affected. The conjugate killed human epidermoid carcinoma (A431) cells, mouse 3T3 fibroblasts and Chinese hamster lung (CHL) cells with identical efficiencies (ED50=2 × 10-9 M). The EGF-RICa conjugate was used as a selection agent and several resistant variants were isolated from CHL cells. These variants showed various degrees of [125I]EGF binding capacity. Some other characteristics of the variants are also described.View full abstractDownload PDF (2654K) -
Masaru Toriyama, Sachiko Endo, Hikoichi Sakai1984 Volume 9 Issue 3 Pages 213-224
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMitotic apparatuses (MAs) isolated from sea urchin eggs contained clusters of granular material in their centrospheres. After cold treatment and mild agitation, the MA fraction formed asters when combined with tubulin. Many microtubules grew 1rom isolated centrospheres most of which were covered with astral residues. Homogenization of the isolated MA fraction dispersed the centrospheres which broke into fragments or into aggregates of small granules that formed small asters when tubulin was added. Electron microscopy showed that more than ten microtubules were nucleated from a granular aggregate composed of several 90-nm granules.
The aster-forming activity was lost with time when the MAs were kept at 0°C. Only glycerol stabilized this activity. The aster-forming activity also was heat labile and trypsin sensitive, but it was resistant to RNase treatment. When the dispersed MAs were extracted with a buffer solution of high ionic strength, aster-forming activity was recovered only in the extract; that is, when the extract had been dialyzed against a solution of low ionic strength, the fine granules self assembled and retained their aster-forming ability.View full abstractDownload PDF (9777K) -
Yuji Moriyasu, Teruo Shimmen, Masashi Tazawa1984 Volume 9 Issue 3 Pages 225-234
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe vacuolar pH (pHv) was modified by vacuolar perfusion of internodal cells of Chara australis. After perfusion, the cell was incubated in artificial pond water. The cell sap was isolated after various incubation periods and its pH was measured with a glass pH microelectrode. The time course of pHv change also was measured in situ with an intracellular pH-sensitive antimony electrode. When the natural cell sap (pH 5) was replaced with artificial cell sap of pH 6.0, the pH gradually returned to 5. This recovery process was inhibited by DCCD, an inhibitor of H+-ATPase. When the natural cell sap was replaced with an artificial cell sap of pH 4.2, the pH quickly shifted to the alkaline direction (reaching a pH of 6, after which it returned to the original value, pH 5), or it returned directly to the original value. This process was not inhibited by DCCD. Our results indicate that the pHv is regulated by the balance between the active influx of H+ into the vacuole provided by the H+-pump of the tonoplast and the passive efflux of H+ from the vacuole.View full abstractDownload PDF (825K) -
Yuji Moriyasu, Teruo Shimmen, Masashi Tazawa1984 Volume 9 Issue 3 Pages 235-246
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe vacuolar pH of Chara internodal cells was modified by vacuolar perfusion, and changes in membrane potential and membrane resistance of the tonoplast in response to the vacuolar pH (pHv) change were studied by anesthetizing the cell with 110 mM KC1 in the external medium. Under this condition the responses of the vacuolar potential (Evo) and re-sistance (Rvo) are assumed to reflect the responses of the tonoplast. Evo showed scarcely any sensitivity to the pH, when the KC1 concentration of the vacuole ([KCl]v) was high (100 mM), but it changed by 30 mV in response to changes in the pHv from 5.5 to 7.5 when the [KCl]v was as low as 0.1 mM. This pHv sensitivity of Evo was suppressed by DCCD, an inhibitor of H+-ATPase.
Tonoplast vesicles were prepared from an internodal cell, and the effect of MgATP on their internal pHs was studied by estimating the accumulation of neutral red. A high accumulation of the pigment was found when MgATP was present in the external medium, but the color faded away when ATP was absent. These results together with the effect of DCCD on the Evo indicate that there is an ATP-dependent electrogenic H+-pump in the tonoplasts of Chara internodal cells and that this electrogenicity is very small under normal conditions in which the natural cell sap contains about 100 mM KC1.
Membrane characteristics of the tonoplast were compared with those of the plasmalemma with respect to their passive permeabilities to K+ and H+ and to the pump conductance.View full abstractDownload PDF (1047K) -
Toshikatsu Nakabayashi, Hiroh Ikezawa1984 Volume 9 Issue 3 Pages 247-263
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe release of plasma-membrane-bound enzymes by phos-phatidylinositol-specific phospholipase C obtained from Bacillus thuringiensis was investigated. Among the ectoenzymes of plasma membrane tested, alkaline phosphodiesterase I was released markedly from rat kidney cortex slices, in addition to alkaline phosphatase and 5'-nucleotidase. Other membrane-bound enzymes; alanine aminopeptidase, leucine aminopeptidase, dipeptidyl peptid-ase, leucine aminopeptidase, dipeptidyl peptidase IV, esterase and γ-glutamyl transpeptidase could not be liberated from the treated slices.
Alkaline phosphodiesterase I was released linearly from rat kidney slices with the concentration of phosphatidylinositol-specific phospholipase C, but little enzyme was released from rat liver slices. Alkaline phosphodiesterase I separated from kidney tissue with n-butanol still retained phosphatidylinositol and was transformed into a lower molecular weight form by phosphatidylino-sitol-specific phospholipase C. This suggests an important function for phos-phatidylinositol in the binding of alkaline phosphodiesterase I to the plasma membrane of rat kidney cells.
The alkaline phosphodiesterase I released from rat kidney had a molecular weight of about 240, 000 and an isoelectric point (pI) of 5.4. The enzyme hydrolyzed the phosphodiester linkage of p-nitrophenyl-thymidine 5'-monophosphate at pH 8.9 and had a Km value of 0.3 mM. The enzyme was activated by Mg2+ and Ca2+, but was inhibited by EDTA. Strong inhibition took place on the addition of adenosine 5'-phosphosulfate or the nucleotide pyrophosphates, i.e., UDP-galactose and a, β-methylene ATP.View full abstractDownload PDF (1908K) -
Yasuo Takano, Katsuyuki Imai, Atsushi Tanaka, Ken Fujimori, Masaoki Ya ...1984 Volume 9 Issue 3 Pages 265-277
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMouse peritoneal macrophages that had been treated with a monovalent carboxylic ionophore, monensin, selectively secreted lysosomal and nonlysosomal granular enzymes into the medium. When macrophages were incubated with 1 to 10 μM monensin, the release of β-glucuronidase, β-hexo-saminidase and β-galactosidase was stimulated time and does dependently. Neither the β-glucosidase nor acid phosphatase, enzymes bound to the lyso-somal membranes, however, were released by monensin. Neutral α-glucosidase, shown recently to be localized in nonlysosomal granules of macrophages (15), was released by monensin at concentrations lower than those required for lysosomal enzyme release. Increased release of lysosomal enzymes also took place in a manner similar to that seen with monensin-treated macrophages after treatment of macrophages with weak bases, chloroquine and ammonium chloride. Neutral α-glucosidase, however, was not released when chloroquine was present in concentrations that stimulated the release of lysosomal enzymes. The UDP-galactosyltransferase activity of the Golgi apparatus in the macrophages markedly decreased after treatment with low concentration of monensin.View full abstractDownload PDF (1365K) -
Hiroshi Maeda, Tetsuuo Morinaga, Isao Mori, Katsuhide Nishi1984 Volume 9 Issue 3 Pages 279-290
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSEffects of human alpha-1-acid glycoprotein (AG) on the passage of human red blood cell(s) (RBC) through membrane filters with micropores were examined in vitro. RBCs, with a mean major diameter of 7.2 μm, that had been suspended at 1% in physiological phosphate-buffered saline (PBS), were filtered through membrane filters of various pore diameters under positive pressure. The percentages of cells that passed through the micropores and of cells hemolyzed during filtration were determined.
RBCs suspended in PBS did not pass through micropores that had an average pore diameter of 3μm; instead hemolysis took place. Neither temper-ature nor applied pressure affected cell passage; but when AG at 0.1 mg/ml or above was added to an RBC-suspension, it promoted cell passage through the 3μm micropores and reduced the degree of hemolysis.
The effects of AG were dose dependent up to a concentration of 0.5 mg/ml. The addition of AG to an RBC-suspension that contained 90 % human serum had the same additive effects. Washing AG-treated RBCs with normal saline produced a marked decrease in cell passage through the 3μm pores.
Fluorescence antibody staining revealed that the exogenous AG was localized on the membrane surface of the RBCs. Our results suggest that the AG bound to the surface of the RBCs acts as a lubricant between the RBCs and the wall of the micropore; this would facilitate RBC-passage through the micropores.View full abstractDownload PDF (1180K) -
Kazuko Kawashima, Shizuo Sato, Mitsuo Izawa1984 Volume 9 Issue 3 Pages 291-304
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSA 110K-dalton phosphoprotein previously was isolated from the nucleoli of mouse ascites sarcoma cells. The localization of this phospho-protein in the nucleoli was confirmed by an indirect immunofluorescence assay with rabbit antisera to the phosphoprotein.
This phosphoprotein formed a complex of 280K daltons with a non-phosphoprotein of 32K daltons in a molar ratio of 1 to 1. The protein complex dissociated in the presence of 6 M guanidine hydrochloride or 1 % sodium dodecylsulphate.
The nucleolus-specific phosphoprotein complex bound preferentially to nucleolar DNAs other than the ribosomal RNA gene in vitro and located in nucleosomes prepared from the nucleoli.
The major phosphoamino acid in the phosphoprotein was phosphoserine, and slight though significant amounts of phosphotyrosine and phospho-threonine also were detected. These phosphorylated amino acids were con-centrated in a specific polypeptide fragment of about 30K daltons obtained by partial digestion with V8 protease. The phosphoprotein was phosphorylated in vitro by the protein kinase activity presented in the complex itself.View full abstractDownload PDF (1163K) -
Chikako Sato, Kimiko Nishizawa, Nobuo Yamaguchi1984 Volume 9 Issue 3 Pages 305-309
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSRat SV-3Y1 cells were stained with double immunofluores-cence. Treatment of cells with detergent and salt removed about 80 % of the antigens and revealed immunofluorescent flecks of the SV40 large T antigen and p53 bound to the nuclear skeleton. These flecks exactly corresponded to the fluorescent spots produced by antibodies against microtubule associated protein-1. The MAP-1 analogues may function in the initiation of DNA synthesis through the interaction with T-antigen and p53.View full abstractDownload PDF (515K) -
Kimiko Murakami-Murofushi, Akiko Hiratsuka, Jiro Ohta1984 Volume 9 Issue 3 Pages 311-315
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSHaploid myxamoebae of the true slime mold, Physarum poly-cephalum contained an acid protease that had a highly acidic pH optimum of 1.4. This enzyme was not considered to have-SH groups, DAN-Cu2+ reactive-carboxyl groups, or an aspartic acid moiety in its active center. Its activity appeared to decrease with time during mating and the subsequent differ-entiation into the diploid, multinuclear plasmodia.View full abstractDownload PDF (453K)
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