title: Characterization of superoxide dismutases in anoxia- and hyperoxia-tolerant symbiotic cnidarians.
abstract: Many cnidarians, such as sea anemones, contain photosynthetic symbiotic dinoflagellates called zooxanthellae. During a light/dark cycle, the intratentacular O(2) state changes in minutes from hypoxia to hyperoxia (3-fold normoxia). To understand the origin of the high tolerance to these unusual oxic conditions, we have characterized superoxide dismutases (SODs) from the three cellular compartments (ectoderm, endoderm and zooxanthellae) of the Mediterranean sea anemone Anemonia viridis. The lowest SOD activity was found in ectodermal cells while endodermal cells and zooxanthellae showed a higher SOD activity. Two, seven and six SOD activity bands were identified on native PAGE in ectoderm, endoderm and zooxanthellae, respectively. A CuZnSOD was identified in both ectodermal and endodermal tissues. MnSODs were detected in all compartments with two different subcellular localizations. One band displays a classical mitochondrial localization, the three others being extramitochondrial. FeSODs present in zooxanthellae also appeared in endodermal host tissue. The isoelectric points of all SODs were distributed between 4 and 5. For comparative study, a similar analysis was performed on the whole homogenate of a scleractinian coral Stylophora pistillata. These results are discussed in the context of tolerance to hyperoxia and to the transition from anoxia to hyperoxia.
authors.affiliation: UMR 1112 INRA-UNSA, Faculté des Sciences, Université de Nice Sophia-Antipolis, BP 71, F-06108, Cedex 02, Nice, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Richier
authors.forename: Pierre-Laurent
authors.initials: PL
authors.lastname: Merle
authors.forename: Paola
authors.initials: P
authors.lastname: Furla
authors.forename: Delphine
authors.initials: D
authors.lastname: Pigozzi
authors.forename: François
authors.initials: F
authors.lastname: Sola
authors.forename: Denis
authors.initials: D
authors.lastname: Allemand
mesh_terms: D000818:Animals; D003063:Cnidaria / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008027:Light; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*; D012615:Sea Anemones / Q000378:metabolism; D012623:Seawater / Q000032:analysis; D013482:Superoxide Dismutase / Q000378:metabolism*; D013559:Symbiosis; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D013482:Superoxide Dismutase; D010100:Oxygen