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Volume 12, Issue 3
Displaying 1-7 of 7 articles from this issue
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Akira WATANABE1987 Volume 12 Issue 3 Pages 118-131
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSDepartment of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444 Excitation of the neuronal membrane is generally believed to result from the conformational change of the membrane channel molecules. In order to detect such a molecular change by optical means, measurements of the optical activity change of the nerve were preformed. The reason for selecting this method is that the concentration of the channel in a living nerve is low (about 20nM in the lobster nerve), and the optical activity measurement can be performed with a low concentration sample. An optical apparatus was constructed for detecting optical activity change of the lobster nerve. Since the nerve shows birefringence changes when the nerve is excited, it was necessary to separate the birefringence signal from the signal due to the change in optical rotation. The optical rotation signal showed a faster time course than that of the birefringence signal. The amplitude of the change sometimes reached 2×10-4 degree. The direction was variable, being either an increase or a decrease of the dextrorotation. A possible explanation for this diversity is that the direction of the optical rotation probably depends on the angle between the direction of helices in the channel molecules and the direction of propagation of the light beam, and the observed change in optical rotation is a difference between large dextrorotatory and levorotatory changes.View full abstractDownload PDF (2449K) -
Koji YODA, Hiroshi KADOKURA, Makari YAMASAKI1987 Volume 12 Issue 3 Pages 132-143
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSMicroorganisms secrete proteins into medium or translocates them in specific locations in the cell. The mechanisms of translocation and secretion of proteins in microorganisms and in mammalian organella are found to be similar in many respects. Most proteins to be localized outside of cytoplasm have an amino-terminal extension called signal sequence. Genetic studies in Escherichia coli were effectively done in place of biochemical studies in mammalian cells. Analyses of mutations in signal sequence proved this peptide is essential for translocation or secretion. Machinery essential for protein translocation or secretion has been found in mammalian cells such as Signal Recognition Particle or its receptor on endoplasmic reticulum. Though such machinery is yet to be found in microorganisms, existence of their counterparts is supported by analysis of temperature-sensitive mutations such as secA or secY defective in protein translocation and secretion. In vitro translocation and secretion systems using inverted bacterial membrane vesicles showed many proteins can translocate or secrete not only co-translationally but also post-translationally, i. e. after the protein synthesis has been completed. In vitro systems were also effectively studied to show that ATP is a major energy source of protein translocation or secretion.View full abstractDownload PDF (1898K) -
Rikuo OCHI1987 Volume 12 Issue 3 Pages 145-157
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSMacroscopic Ca channel currents of a single cardiac muscle are composed of numerous single Ca channel currents. The elementary current were obtained from isolated guinea pig ventricular myocytes using cell-attached patch clamp technique. In response to voltage steps, channel opening occurred singly or in bursts of closely spaced unitary current amplitude (ca. 1 pA) separated by wider shut intervals. A three-state sequential scheme (Closed-Closed-Open) fits to the activation kinetics which is voltage-dependent. At single channel the voltage-dependent inactivation is manifested by the increase of blank sweeps at depolarized holding potentials. The blank sweeps occur even at sufficiently hyperpolarized holding potentials, where current-containing sweeps and blanks appear in clusters. Adrenaline increased the channel availability, i.e. decreased the percentage of blanks by increasing the average number of consecutive current-containing sweeps. A Ca agonist BAY K 8644 increased markedly the channel open time and increased the open state probability of the channel.View full abstractDownload PDF (1228K) -
Masakazu YOSHIKAWA, Takashi YUKOSHI, Kohei SANUI, Naoya OGATA, Takeo S ...1987 Volume 12 Issue 3 Pages 158-164
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSMembrane polarity value, ET (25 °C), was an effective index in order to prepare membrane materials for water-ethanol separation by pervaporation technique. Hydrophobic synthetic polymer membranes, poly (methyl methacrylate-co-styrene) membranes, having hydrogen-bonding site (ester group) as a fixed carrier, showed wide separation properties toward water-ethanol mixture. Separation properties changed from the water permeable membrane to the ethanol permeable one in accord with compositions of membrane materials, that is, chemical compositions of poly (methyl methacrylate-co-styrene).View full abstractDownload PDF (708K) -
Jun-ichi ANZAI, Yasushi HASEBE, Masahiko SHIMADA, Akihiko UENO, Tetsuo ...1987 Volume 12 Issue 3 Pages 165-167
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe magnitude of photoinduced membrane potential across a poly (vinyl chloride) /spirobenzopyran membrane highly depended upon the urease-catalysed decomposition reaction of urea on the surface of the membrane.View full abstractDownload PDF (250K) -
Atsuo WATANABE, Mitsutoshi NAKAJIMA, Toshio OHTANI, Tohru OHI, Hiroshi ...1987 Volume 12 Issue 3 Pages 168-172
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSStudies of Zr (IV) and Fe (III) dynamic ultrafiltration membranes were carried out on porous ceramic supports. Molecular weight cut-off values of these membranes could be controlled by pH conditions during membrane formation and depended on a kind of membrane materials, such as Zr (IV) and Fe (III) colloids. The pH condition which was changing from pH 2.2 to pH 3 or pH 4 during membrane formation, gave a more tight moleculal weight cut-off rather than the constant pH condition. The molecular weight cut-off of the Zr (IV) dynamic membrane, formed by pH changing condition, was smaller than that of the Fe (III) dynamic membrane.
It is supposed that the Zr (IV) colloid particles, entered into the ceramic support, were very fine in the low pH condition and grew into larger particles with changing up of pH condition during membrane formation and made the pass way of solutes thinner.View full abstractDownload PDF (591K) -
Haruhiko OHYA, Yoshiyuki TASAKA, Yohichi NEGISHI, Kanji MATSUMOTO1987 Volume 12 Issue 3 Pages 173-176
Published: May 01, 1987
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSDried membranes heat treated at lower temperature less than 80°C did not virtually permeate gases when vacuum dried at room temperature but membranes dried at -25°C shows good permeability and did not shows good separation of CO2-CH4 gaseous mixture.
90°C heat treated membrane dried at -25°C shows ca. 5 times larger permeability than that dried at room temperature and both membranes show almost the same separation factor for CO2CH4 gaseous mixture.
70°C heat treated membrane dried at -25°C shows hysteresis phenomenon on the relation between permeation flux and pressure difference.View full abstractDownload PDF (434K)
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