Beilby Mary J, Al Khazaaly Sabah, Bisson Mary A
School of Physics, University of NSW, Kensington 2052, Sydney, NSW, Australia,
J Membr Biol. 2015 Feb;248(1):93-102. doi: 10.1007/s00232-014-9746-9. Epub 2014 Nov 7.
Salt sensitive Characeae Chara australis responds to 50 mM NaCl by a prompt appearance of noise in the trans-membrane potential difference (PD). The noise diminishes with time in saline and PD depolarization, leading to altered current-voltage characteristics that could be modeled with H(+)/OH(-) channels. Beilby and Al Khazaaly (JMB 230:21-34, 2009) suggested that the noise might arise from cooperative transient opening of H(+)/OH(-) channels. Presoaking cells in 10 μM melatonin over 24 h abolished the noise in some cells, postponed its appearance in others or changed its characteristics. As melatonin is a very effective antioxidant, we postulated opening of H(+)/OH(-) channels by reactive oxygen species (ROS). Measurement of ROS using dihydrodichlorofluorescein diacetate confirmed substantial reduction in ROS production in melatonin-treated cells in saline and sorbitol media. However, ROS concentration decreased as a function of time in saline medium. Possible schemes for activation of H(+)/OH(-) channels under salinity stress are considered.
盐敏感轮藻科植物南方轮藻对50 mM氯化钠的反应是跨膜电位差（PD）迅速出现噪声。在盐溶液中，噪声随时间减弱，同时PD去极化，导致电流-电压特性改变，这可以用H(+)/OH(-)通道进行建模。贝尔比和哈扎利（《分子生物学杂志》230:21 - 34，2009年）提出，噪声可能源于H(+)/OH(-)通道的协同瞬时开放。将细胞在10 μM褪黑素中预浸泡24小时，在一些细胞中消除了噪声，在另一些细胞中推迟了噪声的出现，或者改变了其特征。由于褪黑素是一种非常有效的抗氧化剂，我们推测活性氧（ROS）会导致H(+)/OH(-)通道开放。使用二氢二氯荧光素二乙酸酯测量ROS证实，在盐溶液和山梨醇培养基中，褪黑素处理的细胞中ROS产生大幅减少。然而，在盐溶液培养基中，ROS浓度随时间下降。文中考虑了盐胁迫下H(+)/OH(-)通道激活的可能机制。
