Salinity-induced noise in membrane potential of Characeae Chara australis: effect of exogenous melatonin.
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.
School of Physics, University of NSW, Kensington 2052, Sydney, NSW, Australia, m.j.beilby@unsw.edu.au.
Mary J
MJ
Beilby
Sabah
S
Al Khazaaly
Mary A
MA
Bisson
D044784:Chara / Q000187:drug effects* / Q000378:metabolism*; D008550:Melatonin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects* / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D054712:Salinity; D012965:Sodium Chloride / Q000494:pharmacology
D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D008550:Melatonin