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Applied and Environmental Microbiology, November 2005, p. 6508-6514, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.6508-6514.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Characterization of Enzymatic Antioxidants in the Lichen Ramalina lacera and Their Response to Rehydration

Lior Weissman,1,{dagger} Jacob Garty,1,2 and Ayala Hochman3*

Department of Plant Sciences,1 Institute for Nature Conservation Research,2 Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel3

Received 26 February 2005/ Accepted 15 June 2005

Lichens are slow-growing associations of fungi and green algae or cyanobacteria. This symbiotic association forms a common thallus that does not possess roots or a waxy cuticle and depends mainly on atmospheric input of mineral nutrients. The lifestyle of most lichens is composed of alternating periods of desiccation with low metabolic activity and hydration that induces increase in their metabolism. We have previously shown that rehydration of the naturally desiccated lichen Ramalina lacera resulted in a rapid increase in photosynthesis and was accompanied by a burst of intracellular production of reactive oxygen species and nitric oxide, as well as a transient decrease in water-soluble antioxidant capacity. We report here on enzymatic antioxidants of R. lacera and their response to rehydration. Native gel electrophoresis of crude extracts of R. lacera stained for superoxide dismutase (SOD) activity revealed four Fe-SOD and four Mn-SOD electromorphs that are synthesized by the alga, a Cu/Zn-SOD and a Mn-SOD that are the product of the fungus, and two catalases synthesized one by the fungus and the other by the algae. In addition, we detected glutathione reductase and glucose-6-phosphate dehydrogenase activities in crude extracts of R. lacera. Rehydration of the thalli resulted in a decrease in SOD activity of all forms, and a transient decrease in total catalase activity, as well as a decrease in the antioxidant auxiliary enzymes glutathione reductase and glucose-6-phosphate dehydrogenase.

* Corresponding author. Mailing address: Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel. Phone: 972-3-6409886. Fax: 972-3-6406834. E-mail: ayalah{at}tauex.tau.ac.il.

{dagger} Present address: Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224.

Applied and Environmental Microbiology, November 2005, p. 6508-6514, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.6508-6514.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.





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