The effect of low light intensities on oxidative stress induced by short-term chilling in Dunaliella salina teod

Abstract

Under circumstances where electron transport is restricted, such under low temperature condition, oxidative stress may occur even at optimal or low-light intensities. Short-term-effects of light intensities (20 or 100 μmol m -2 sec-1), on the levels of 6 enzymatic, two nonenzymatic antioxidants, chl a, chl b, total carotenoid and β-carotene, on the antioxidant response of Dunaliella salina under cold temperature (13°C) were quantified after 24 h stress treatments. The activity of superoxide dismutase (SOD) increased, under 13°C/100 μmol m-2 sec-1, whereas ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), superoxide dismutase and pyrogallol peroxidase activities were induced under 13°C/20 μmol m-2 sec-1. The cells exhibited an increase in reduced ascorbate and reduced glutathione (GSH) coincident with a marked increase in oxidized glutathione (GSSG), at 13°C/100 μmol m -2 sec-1. There were no marked changes in ascorbate or glutathione pools at 13°C/20 μmol m-2 sec-1, which are similar to those at 28°C/100 μmol m-2 sec-1. Chlorophylls and carotenoids reduction were also observed under chilling treatments, which were more reduced by the higher light intensity (13°C/100 μmol m-2 sec-1). The results of present study indicated various antioxidants responds to different combinations of chilling and low light intensities, in D. salina. These responses are very sensitive to small increase in the light intensity. © 2006 Asian Network for Scientific Information.