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The role of H+/OH channels in saline pathology of Chara australis : brief history / Mary Beilby in Botany letters, vol. 165, n°1 (Année 2018)
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Titre : The role of H+/OH channels in saline pathology of Chara australis : brief history Type de document : Livre Auteurs : Mary Beilby, Auteur ; Virginia Shepherd, Auteur ; Marketa Absolonova, Auteur Année de publication : 2018 Article en page(s) : pp. 45-54 Langues : Anglais Mots-clés : H+/OH channels Chara australis salinity stress current-voltage characteristics membrane potential difference noise fluorescent pH measurement Résumé : "The pH banding pattern, observed in Chara and Nitella early last century, suggests that there are H+ or OH− conducting channels in the alkaline bands of the characean plasma membrane. If the cells are exposed to high pH medium, pHo, these channels become the dominant membrane conductance: High pH state. Goldman-Hodgkin-Katz (GHK) equation can model the current-voltage (I/V) characteristics of this state with either H+ or OH− as permeant ion. However, H+ requires unrealistically large increases in channel conductance/number parameter as pHo increases. Recently we discovered a typical spiky noise in the membrane potential difference (PD) of salt sensitive Chara australis, appearing immediately upon exposure to saline. The H+/OH− channels are thought to open transiently in small patches all over the cell, while negative membrane PD does not support their open state/s. As the membrane PD depolarizes due to inhibition of the proton pump by salinity, the H+/OH− channels remain open to dominate the I/V characteristics, which can also be modeled by GHK equation. The addition of 1 mM ZnCl2, the main known blocker of animal H+ channels, abolishes both the PD noise and the H+/OH− I/V characteristics in high pH state and in salt stressed cells. Confocal microscopy and fluorescein isothiocyanate (FITC)-dextran illuminate the pH changes around cells and reveal transient bright spots early in saline exposure, becoming more numerous and fixed in space with time in saline APW." Type de publication : périodique Référence biblio : Beilby M., Shepherd V., Absolonova M., 2018 - The role of H+/OH channels in saline pathology of Chara australis : brief history. Botany letters, 165 (1) : 45-54. Permalink : http://www.cbnbrest.fr/catalogue_en_ligne/index.php?lvl=notice_display&id=67205
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