Sherman, Timothy D , Major, Kelly , Henley, William .
Cellular Response to Oxidative Stress in Halotolerant Chlorophytic Algae.
Studies that target extreme environments, and the microbes that inhabit them, offer invaluable insight into the mechanisms of stress tolerance and are likely to contribute to our understanding of the synergistic effects of multiple stressors in heavily-impacted ecosystems. Moreover, microbial communities represent a largely untapped resource for potentially unique and economically useful organisms. This study is the first in a series designed to investigate the mechanisms of tolerance to oxidative stress in a halotolerant isolate of Dunaliella from the Salt Plains National Wildlife Refuge, Oklahoma. This alga is an extremophile that can survive in salinities ranging from 5 to >300 ppt, withstand prolonged exposure to high temperatures of 38-45oC, and grow in light intensities up to that of full sun. Our measurements of photosynthetic physiological compensation indicate that acclimation to high salinity confers tolerance to other oxidative stressors (i.e., high temperature, high light and herbicide exposure) in this isolate. For example, during temperature trials, cells acclimated to high salt exhibited maximum rates of photosynthesis (Pmax) and values for light-harvesting efficiency (alpha) that were higher than those of cells acclimated to low salt when exposed to high temperature. We conducted parallel experiments with the well-characterized salt-tolerant Dunaliella salina [UTEX 200]. At present, we are integrating these traditional physiological analyses with recently developed proteomics approaches to further examine physiological and biochemical compensation and the role(s) that gene expression regimes might play in achieving tolerance to oxidative stress.
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1 - University of South Alabama, Dept. of Biological Sciences, Life Sci. Bldg. Room 124, Mobile, AL, 36688, USA
2 - University of South Alabama, Dept. of Biological Sciences
3 - Oklahoma State University, Dept. of Botany
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM