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Volume 18, Issue 1
Displaying 1-6 of 6 articles from this issue
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Taka-aki OHKAWA1993 Volume 18 Issue 1 Pages 3-12
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSAlthough ionic and metabolic gradients across membranes in living cells are known to be vital to cell functioning, in plants both the stiffness of cell wall and complexity of the cell compartmentalization sometimes prevent the study of membrane transport. This difficulty has, however, largely been overcome with the aid of two techniques, one employing a vibrating electrode1) and the other a patch clamp (Hamill et al., Pflügers Arch., 391, 85 (1981)). The former technique has revealed the ionic currents which flow locally around various type of cells. In the introduction to the present article, the relation of local currents with several physiological phenomena, such as pollination and cell polarity, is reviewed. The patch-clamp technique has directly led to the development of research strategies, not only on the plasma membrane, but also on the vacuolar membrane and other intracellular organelles. In fact, various types of ion channels, such as voltage-dependent, Ca2+-regulated, and phytohormone-modulated channels, have been found in plant cells. In the latter half of this article, the properties of several ion channels in the plasma and vacuolar membranes of characean cells which were identified using the patch clamp are reviewed, and their physiological functions are summarized.View full abstractDownload PDF (1609K) -
Ryogo Hirata, Yasuhiro Anraku1993 Volume 18 Issue 1 Pages 13-23
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe yeast vacuole is a primary storage compartment, which also serves as a degradative organelle like the animal cell lysosome. The lumen of the vacuole is acidified by the vacuolar membrane H+-ATPase, the best-known member of the V-type ATPases of eukaryotic cells. This H+-ATPase is a multisubunit enzyme consisting of at least eight polypeptides with apparent molecular masses of 100, 69, 60, 42, 36, 32, 27, and 17, kDa. The genes (VMA) for seven of these subunits have been isolated, and their deletions have been constructed. These uma deletion mutants were defective in vacuolar acidification and showed common growth phenotypes : sensitive to pH and Ca2+ in the medium and deficient in respiration (Pet-). The screening for yeast calcium-sensitive mutants (cls) that are also Pet-have identified three novel genes, VMA 11-VMA 13. VMA 11 and VMA 13 encode putative subunits of the vacuolar membrane H+-ATPase. The VMA 12 gene product is not included in the enzyme but is required for the assembly and/or targeting of the enzyme.View full abstractDownload PDF (1699K) -
Kunihiro KASAMO1993 Volume 18 Issue 1 Pages 24-33
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe plant plasma membrane H+-ATPase couples ATP hydrolysis to proton transport across the plasma membrane, thereby establishing the driving force for solute transport into and out of plant cells. As such, the H+-ATPase participates in a number of cellular processes important to the overall physiology of plants. From biochemical studies and recent application of molecular approaches, the molecular structure and function of the plasma membrane H+-ATPase have been characterized. This review summarizes currently available informations on the molecular structure and function of the plant plasma membrane H+-ATPase. Especially, the interaction between the H+-ATPase molecules and phospholipids on proton pumping is also discussed.View full abstractDownload PDF (1728K) -
Shoji SHIMOMURA, Shinichiro WATANABE1993 Volume 18 Issue 1 Pages 34-42
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSAuxin is a plant hormone that regulates cell growth and cell differentiation. Auxin moves basipetally from the shoot apex to the basal region along a polar axis of plant. This movement has been believed to be performed through a cell-to-cell transport mediated by specific carriers located in the plasmalemma. Recently, evidence indicating that the plasmalemma of plant cells is one of the targeting sites of auxin has been reported. Exogenously applied antibodies raised against a microsomal auxin-binding protein inhibit cellular responses to auxin, and membrane-impermeable auxin derivatives mimic free auxins in cellular responses. In addition, several enzymic functions found in plasmalemma have been reported to be regulated directly by auxin. These findings indicate that both the auxin receptor and the signaltransduction machinery, in addition to the auxinflux carries, locate in the plasmalemma of plant cells.View full abstractDownload PDF (1550K) -
Studies On Distribution and Reverse Osmosis Properties of Cellulose Acetate Derivatives for AlcoholsHaruhiko Ohya, Huang Jicai, Yoichi Negishi1993 Volume 18 Issue 1 Pages 43-52
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSThe particles of cyanoethyl cellulose acetate (CACN), hydroxypropyl cellulose acetate (CAHP) and cellulose acetate have been prepared from the solutions containing the same components as reverse osmosis (RO) membrane casting solutions. The pore sizes in particles obtained have been measured by means of gel chromatography. The distribution properties for alcohols have been studied by liquid chromatography. It was found that alcohols were attracted to the surfaces of these membrane materials. The Kd values increased with the increase of carbon numbers of n-alkyl alcohols and followed the order of n->iso->sec->tert-alcohols with different structure. The separation properties of RO membranes casted from these materials for alcohols have also been investigated. It was found that the solute rejection for n-alkyl alcohols reached a maximum when the alcohol molecule containing three carbon atoms and the order of solute rejection of tert->sec--iso-> n-alcohols with different structure existed. The experimental results from liquid chromatography and reverse osmosis have been discussed according to the polar effect (Taft number σ*), nonpolar effect (Small number s*) and steric effect (Steric parameter Es) of the substituent groups in alcohols. Some relations have been found.View full abstractDownload PDF (1146K) -
Hiroyuki Shirahama1993 Volume 18 Issue 1 Pages 53-63
Published: January 01, 1993
Released on J-STAGE: March 04, 2011
JOURNAL FREE ACCESSIn this article I have reviewed (blood) proteins adsorption onto synthetic polymer surfaces, i. e., onto polymeric microspheres. First, the surface characteristics of polymeric microspheres (polymer latices) were examined. As a result, hydrogel polymer layers, e. g., poly (acrylamide) (poly-AAm) and poly (2-hydroxyethyl methacrylate) (poly-HEMA) layers were found to exist on the microsphere surfaces of styrene (St) /AAm and St/HEMA copolymers (P (St/AAm) and P (St/HEMA)), respectively. Subsequently, singular and competitive protein adsorption onto polymeric microspheres was investigated as a function of pH and ionic strength, surface characteristics of microspheres, coexistent electrolyte ions. Each protein showed the maximum adsorption near its isoelectric point. The amounts adsorbed onto hydrophilic P (St/AAm) and P (St/HEMA) microspheres were much smaller than that onto hydrophobic polystyrene (PS) microsphere, particularly in the neutral and alkaline pH regions. Fibrinogen adsorbed preferentially from the protein mixture of albumin, γ-globulin, and fibrinogen. Further, the adsorbability of heat-denatured albumin was studied. Compared with the native component of the protein, the denatured components adsorbed preferentially onto microspheres.View full abstractDownload PDF (1478K)
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