title: High resistance to oxidative damage in the Antarctic midge Belgica antarctica, and developmentally linked expression of genes encoding superoxide dismutase, catalase and heat shock proteins.
abstract: Intense ultraviolet radiation, coupled with frequent bouts of freezing-thawing and anoxia, have the potential to generate high levels of oxidative stress in Antarctic organisms. In this study, we examined mechanisms used by the Antarctic midge, Belgica antarctica, to counter oxidative stress. We cloned genes encoding two key antioxidant enzymes, superoxide dismutase (SOD) and catalase (Cat), and showed that SOD mRNA was expressed continuously and at very high levels in larvae, but not in adults, while Cat mRNA was expressed in both larvae and adults but at a somewhat reduced level. SOD mRNA was expressed at even higher levels in larvae that were exposed to direct sunlight. Catalase, a small heat shock protein, Hsp70 and Hsp90 mRNAs were also strongly upregulated in response to sunlight. Total antioxidant capacity of the adults was higher than that of the larvae, but levels in both stages of the midge were much higher than observed in a freeze-tolerant, temperate zone insect, the gall fly Eurosta solidaginis. Assays to measure oxidative damage (lipid peroxidation TBARS and carbonyl proteins) demonstrated that the Antarctic midge is highly resistant to oxidative stress.
authors.affiliation: Department of Entomology, Ohio State University, Columbus, OH 43210, USA. lopez-martinez.1@osu.edu
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Lopez-Martinez
authors.forename: Michael A
authors.initials: MA
authors.lastname: Elnitsky
authors.forename: Joshua B
authors.initials: JB
authors.lastname: Benoit
authors.forename: Richard E
authors.initials: RE
authors.lastname: Lee
authors.forename: David L
authors.initials: DL
authors.lastname: Denlinger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002683:Chironomidae / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000201:enzymology; D015227:Lipid Peroxidation; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D050050:Protein Carbonylation; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D014199:Trehalose / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000975:Antioxidants; D006360:Heat-Shock Proteins; D019476:Insect Proteins; D014199:Trehalose; D002374:Catalase; D013482:Superoxide Dismutase