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Volume 9 (1984)
- Issue 4 Pages 317-
- Issue 3 Pages 203-
- Issue 2 Pages 105-
- Issue 1 Pages 1-
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Volume 9, Issue 2
Displaying 1-11 of 11 articles from this issue
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Fumiaki Ito, Sachiko Ito, Nobuyoshi Shimizu1984 Volume 9 Issue 2 Pages 105-115
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSEpidermal growth factor (EGF) was derivatized at the amino terminus with N-succinimidyl 3-(2-pyridyldithio)propionate and then cross-linked to the cysteinyl residues of α2-macroglobulin (α2M) via disulfide bonds. The EGF-α2M conjugate delivered EGF into dense lysosomal fractions through binding to α2M receptors in a variant of mouse Swiss/3T3 fibroblasts, NR-6, which are deficient in EGF receptors. The conjugate stimulated DNA synthesis in Swiss/ 3T3 cells, but it did not stimulate DNA synthesis in NR-6 cells. This differential stimulation was due to the conjugate's binding to EGF receptors since bacitracin, which completely inhibits [125I]α2M binding to its receptors, inhibited conjugate binding by 80%. Thus, EGF bound to and internalized through α2M receptors does not function as a mediator for DNA stimulation. The mechanisms of action of the conjugate are discussed in relation to the role of receptor-mediated endocytic pathways.View full abstractDownload PDF (1709K) -
Kazuhiro Ishii, Hiromi Sakamoto, Jun-ichi Furuyama, Masao Hanaoka1984 Volume 9 Issue 2 Pages 117-123
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSWe developed a test medium for cytidine deaminase in order to examine the distribution of this enzyme in cultured cell lines. The growth of various mammalian cell lines was tested in culture medium containing 2 μM pyrazofurin and 100 μM cytidine. Enzymological assays for the enzyme also were made spectrophotometrically with cell extracts. A good correlation was found between results of cell growth tests and the levels of enzyme activity. Twelve of twenty cell lines were killed in the test medium, but the remaining lines showed good growth. The levels of enzyme activities were lower in the former lines than in the latter. The critical level of enzyme activity required to support cell growth was approximately 30 units per mg protein. These findings indicate that culture medium containing 2 μM py-razofurin and 100 μM cytidine serves as a test medium for cytidine deaminase. The possibility that the cytidine deaminase may be useful in determining the embryonic origin of cultured cell lines is discussed, based on the growth properties of various cultured cell lines in the test medium.View full abstractDownload PDF (652K) -
Takehisa Sando, Kunio Konno, Nobuko Takei, Terufumi Sakamoto, Tokuhiko ...1984 Volume 9 Issue 2 Pages 125-133
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSRat liver cytosol catalase was purified by making use of its interaction with deoxycholate and by the various methods used to purify peroxisomal catalase. The purified preparation was both enzymatically and immunologically identical with the purified peroxisomal catalase, but differed in its chromatographic behaviour and electrophoretic mobility. Amino acid analysis also revealed a slight difference between the two catalase molecules.View full abstractDownload PDF (736K) -
Yasuaki Yoshimoto, Noburo Kamiya1984 Volume 9 Issue 2 Pages 135-141
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSSaponin models of the plasmodial strand of Physarum polycephalum were constructed to study how Ca2+ and ATP regulate the generation of tension. ATP-induced isometric tension in a saponin model increased with an increase in ATP concentration until maximum tension (0.3-1.7 mg) was reached at about 1 mM. The sensitivity of the model to ATP was heightened three to five times in a basic solution containing an ATP-regenerat-ing system, the maximum tension (0.3-0.6 mg) being reached at 0.2 to 0.3 mM ATP. Contraction of the model also depended on the Ca2+ concentration irrespective of the presence or absence of the ATP-regenerating system. The optimal pCa was 7.0, and tension decreased with a Ca2+ concentration above or below this value. These results indicate that the tension generated in the plasmodial strand of Physarum in vivo may be regulated by ATP and/or Ca2+.View full abstractDownload PDF (679K) -
Takashi Sekiya, Tadaomi Takenawa, Yoshinori Nozawa1984 Volume 9 Issue 2 Pages 143-155
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSUsing filipin and freeze-fracture electron microscopy, we ex-amined the distribution of membrane cholesterol during the fusion of myo-blasts in vitro. The early stages of fusion were characterized by the depletion of cholesterol from the membrane apposition sites, at which the plasma mem-branes of two adjacent cells were in close contact. At first, filipin-cholesterol complexes were absent from the plasma membrane of one cell only and were distributed homogeneously on the membrane of the other cell. Eventually, both of the closely apposed membranes became almost completely free the filipin-cholesterol complexes. Membrane fusion took place at several points within the filipin-cholesterol complex-free areas. In later stages, the cytoplasms of the fusing cells became confluent by fenestration of the plasma membranes formed with the filipin-cholesterol complex-free regions. Our observations suggest that membrane cholesterol is reorganized at these fusion sites and that fusion initiated by the juxtaposition of the cholesterol-free areas of each plasma membrane of the adjacent cells.View full abstractDownload PDF (2305K) -
Kazuki Sato, Akira Kawahara, Minoru Amano1984 Volume 9 Issue 2 Pages 157-165
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe effects of estrogen on the uridine uptake into cells were examined in primary cultures of liver parenchymal cells from Xenopus laevis. The total uptake of [3H]uridine into the estrogen-treated cells and its incorpora-tion into RNA were about 1.5 times higher than the values for control cells. The uptake of [3H]adenosine and its incorporation into RNA were not affected by estrogen. An experiment in which liver parenchymal cells were double labeled with [3H]uridine and [3H]adenosine showed that estrogen elevated the specific radioactivity of the UTP pool 1.4-fold the value found for the control cells, but that of the ATP pool was not altered by estrogen. Short term labeling revealed that estrogen did not significantly alter the rate of the initial uptake of [3H]uridine into the cells, but it did stimulate [3H]uridine phosphorylation about 1.7-fold. Uridine kinase activity measured in cell-free extacts of hepatocytes treated with estrogen had a value 1.6 times that of the control cells. These data indicate that the stimulation of [3H]uridine uptake and phosphorylation in Xenopus laevis hepatocytes in the presence of estrogen is caused by the enhancement of uridine kinase activity.View full abstractDownload PDF (980K) -
Morihiko Nakamura, Kei Takahashi, Hiroyuki Naora, Tokugoro Tsunematsu1984 Volume 9 Issue 2 Pages 167-179
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSMonoclonal antibodies against human plasminogen activator urokinase have been produced. A G62 hybridoma-producing antibody (IgG) was purified on a DEAE-cellulose column, and it proved useful for the measurement, identification and purification of antigens that had approximate molecular weights of 55-and 33-Kdaltons.
For immunochemical measurements and purification, a competitive enzymelinked immunosorbent assay (ELISA) and affinity chromatography using antibody-immobilized Sepharose 4B were developed. The ELISA has sensitivity to 20 p mole antigen molecules. The binding capacity of the antigen on the affinity column was evaluated on SDS-polyacrylamide slab gels as well as by fibrin autography and ELISA. Results showed that there was quantitative purification with no loss of enzyme activity in the one-step procedure.
Western blotting and affinity binding showed antigenic bands with apparent molecular weights of 55-and 33-Kdaltons. Because the 55-Kdalton form contains 33-and 22-Kdalton components connected by a disulfide bond, the epitope domain is present on the 33-Kdalton chain.
Using this antibody, we examined human kidney sections by direct immunofluorescence to locate the antigen. It was found in epithelial cells of convoluted segments, in glomerulus cells and in capillary endothelial cells, evidence that renal tubular cells synthesize the antigen which then is secreted in urine.View full abstractDownload PDF (1235K) -
Takeo Terasaki1984 Volume 9 Issue 2 Pages 181-185
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe distribution of anti-RNA antibody-binding sites on the surfaces of Ehrlich ascites tumor cells was studied by membrane immuno-fluorescence after binding anti-RNA antibody on the cell surfaces. Results showed that the cells formed caps after incubation with anti-RNA antibody at 4°C and the elevation of their temperature to 37°C. Pronase treatment of the cell surfaces completely inhibited reactivity with anti-RNA antibody. These results suggest that the RNAs on the surfaces of Ehrlich ascites tumor cells are linked to membrane protein membrane-bound cytoskelton complexes.View full abstractDownload PDF (439K) -
Masazumi Sameshima1984 Volume 9 Issue 2 Pages 187-192
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSDictyostelium discoideum grew and differentiated normally on cellulosedialysis membranes placed on agar plates. This permitted the examina-tion of cells at various stages of development, including cells during aggrega-tion. Cells were preserved well and fixed for electron microscopy by brief ex-posure to acrolein vapore followed by immersion in glutaraldehyde solution.View full abstractDownload PDF (698K) -
Takako Ohno-Shosaku, Hiroko Hama-Inaba, Yasunobu Okada1984 Volume 9 Issue 2 Pages 193-196
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe technique of electric pulse-induced cell fusion (electro-fusion) was used to obtain heterokaryons between normal human lymphoblasts (HSC93) and mouse leukemic lymphoblasts (MCN151). The two types of cells were brought into contact in the cell suspension by dielectrophoresis with an alternating electric field (0.8 kV/cm, 100 kHz) in the presence of calcium ions and pronase E. Cell fusion was induced by giving two successive electric pulses (3.3 and 5 kV/cm, 10 μsec). Prior treatment of human (but not mouse) lymphoblasts with neuraminidase improved fusion efficiency. Diffe-rential staining of the two types of cells with Janus Green and Neutral Red showed that about 40 % of the viable fused cells underwent heterokaryonic fusion. We concluded that electrofusion is an efficient method for obtaining heterokaryons from human and mouse lymphoblasts.View full abstractDownload PDF (370K) -
Takemi Enomoto, Yasunori Tawaragi, Yoshinari Watanabe, Masayuki Seki, ...1984 Volume 9 Issue 2 Pages 197-202
Published: 1984
Released on J-STAGE: April 18, 2008
JOURNAL FREE ACCESSThe requirements of cofactor DNA for DNA-dependent ATPases B and C3 were analyzed in detail. ATPase B and C3 required the pre-sence of a polynucleotide for their activities. Among the DNAs tested, ATP-ase B showed a preference for poly(dT) as its cofactor. The other deoxyhomo-polymers, except poly(dG) and heat-denatured DNA also were effective. The alternating polydeoxyribonucleotide, poly[d(A-T) ] had an efficiency 23 that of heat-denatured DNA. Unlike ATPase B, ATPase C3 showed almost no activity with deoxyhomopolymers. The most effective cofactor for ATPase C3 so far tested is poly[d(A-T) ]. Relatively high activity was obtained with heat-denatured DNA. The high activity of ATPase B with poly(dT) was reduc-ed by the addition of poly(dA). The addition of noncomplementary homo-polymers did not affect enzyme activity. ATPase C3 activity in the presence of 10 μM poly(dT) increased gradually with concentrations of poly(dA) up to 20 μM, after which it decreased. Almost no increase in activity was observed when noncomplementary homopolymers were added. The relatively high activ- ity of ATPase C3 with heat-denatured DNA was suggested by its high sensitivity to ethidium bromide to be due to the double-stranded region in the heat-denatured DNA formed by self-annealing.View full abstractDownload PDF (570K)
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