Faculty Profiles - KATSUHARA Maki

Papers - KATSUHARA Maki

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Mechanism of calcium‐dependent salt tolerance in cells of Nitellopsis obtusa: role of intracellular adenine nucleotides

M. KATSUHARA, M. TAZAWA

Plant, Cell & Environment 13 ( 2 ) 179 - 184 1990

Language：English Publishing type：Research paper (scientific journal)

Abstract. The tonoplasts of internodal cells of Nitellopsis were removed by perfusing the vacuoles with media containing a Ca2 chelator, EGTA. Treatment of tonoplast‐free cells with 100 mol m3 NaCl induces a large membrane depolarization, a drastic decrease in the membrane resistance and an increase in Na+ influx. These events are identical to those that occur in intact cells subjected to high NaCl. These responses to NaCl are prevented if 10 mol m3 Ca2+ is supplied together with 100 mol m3 NaCl. The protective effect of Ca2+ is evident only when the intracellular ATP concentration exceeds 0.1 mol m3 and does not occur full when the intracellular ATP is removed. AMP at concentrations greater than 0.5 mol m3 or 0.25 mol m3 AMPPNP can replace ATP. It is concluded that ATP does not act as an energy source nor as a substrate for protein phosphorylation. ATP seems to exert its effects as a coeffector with Ca2+ in regulating the Na+ permeability of the plasma membrane. Copyright © 1990, Wiley Blackwell. All rights reserved

DOI： 10.1111/j.1365-3040.1990.tb01290.x

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ATP-regulated ion channels in the plasma membrane of a characeae alga, Nitellopsis obtusa

Maki Katsuhara, Tetsuro Mimura, Masashi Tazawa

Plant Physiology 93 ( 1 ) 343 - 346 1990

Language：English Publishing type：Research paper (scientific journal) Publisher：American Society of Plant Biologists

Using the patch-clamp technique, we recorded single-channel currents across the excised patch of the plasma membrane of Nitellopsis. Both K+ and Na+ can pass this channel, but currents were not carried by Cl-. Upon the addition of ATP or AMP to the cytoplasmic side, the frequency of channel opening decreased. This is the first report on an ATP-regulated channel in plant cells.

DOI： 10.1104/pp.93.1.343

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Patch-clamp study on a Ca2+-regulated K+ channel in the tonoplast of the brackish characeae lamprothamnium succinctum

Maki Katsuhara, Tetsuro Mimura, Masashi Tazawa

Plant and Cell Physiology 30 ( 4 ) 549 - 555 1989

Language：English Publishing type：Research paper (scientific journal) Publisher：Oxford University Press

Cytoplasmic drops were prepared from internodal cells of the brackish Characeae Lamprothamnium succinctum. Applying the patch-clamp technique to single drops covered with tonoplast, we demonstrated the presence of Ca2+-regulated K+ channels in the tonoplast. In a cell-attached mode, the selectivity of such channels for K+ was about 50 times that for Na+. This channel showed a tendency to rectify in an outward direction. In the negative region of the pipette voltage, the conductance of this channel was 50 pS, while it was 100 pS in the positive voltage region. When the pipette voltage was increased above 50 mV, two conductance levels were found in the cell-attached mode as well as in the excised patch (cytoplasmic-side-out patch), which was obtained by pulling the patch pipette from the cytoplasmic drop under conditions of low levels of Ca2+. Using the excised patch, we controlled the level of Ca2+ on the cytoplasmic side of the channels. At a low level of Ca2+ (pCa=8) on the cytoplasmic side, the open frequency was very low and the opening time was short. An increase in Ca2+ on the cytoplasmic side (pCa = 5) increased both the frequency and the duration of opening. However, the conductance of the channels did not change. This regulation by Ca2+ of the K+ channels was reversible, that is, addition of EGTA on the cytoplasmic side inactivated the channels. The present study demonstrates a direct action of Ca2+ on the K+ channels. The physiological role of the K+ channel in the regulation of turgor in Lamprothamnium is discussed. © 1989 The Japanese Society of Plant Physiologists (JSPP).

DOI： 10.1093/oxfordjournals.pcp.a077774

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Rapid cytoplasmic alkalization and dynamics of intracellular compartmentation of inorganic phosphate during adaptation against salt stress in a halotolerant unicellular green alga dunaliella tertiolecta:³¹P-nuclear magnetic resonance study Reviewed

Kuchitsu, K., Katsuhara, M., Miyachi, S.

Plant and Cell Physiology 30 ( 3 ) 407 - 414 1989

ATP IS ESSENTIAL FOR CALCIUM-INDUCED SALT TOLERANCE IN NITELLOPSIS-OBTUSA

M KATSUHARA, M TAZAWA

PROTOPLASMA 138 ( 2-3 ) 190 - 192 1987

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