[article] 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 | in Botany letters > vol. 165, n°1 (Année 2018) . - pp. 45-54
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