title: Antioxidant defences in hydrated and desiccated states of the tardigrade Paramacrobiotus richtersi.
abstract: Reactive oxygen species (ROS) are formed in all aerobic organisms, potentially leading to oxidative damage of all biological molecules. A number of defence mechanisms have developed to protect the organism from attack by ROS. Desiccation tolerance is correlated with an increase in the antioxidant potential in several organisms, but the regulation of the antioxidant defence system is complex and its role in desiccation-tolerant organisms is not yet firmly established. To determine if anhydrobiotic tardigrades have an antioxidant defence system, capable of counteracting ROS, we compared the activity of several antioxidant enzymes, the fatty acid composition and Heat shock protein expression in two physiological states (desiccated vs. hydrated) of the tardigrade Paramacrobiotus richtersi. In hydrated tardigrades, superoxide dismutase and catalase show comparable activities, while in desiccated specimens the activity of superoxide dismutase increases. Both glutathione peroxidase and glutathione were induced by desiccation. The percentage of fatty acid composition of polyunsaturated fatty acids and the amount of thiobarbituric acid reactive substances are higher in desiccated animals than in hydrated ones. Lastly, desiccated tardigrades did not differ significantly from the hydrated ones in the relative levels of Hsp70 and Hsp90. These results indicate that the possession of antioxidant metabolism could represent a crucial strategy to avoid damages during desiccation in anhydrobiotic tardigrades.
authors.affiliation: Dipartimento di Scienze Molecolari Applicate ai Biosistemi, DiSMAB, Università degli Studi di Milano, Via D. Trentacoste, 220134 Milan, Italy. angelamaria.rizzo@unimi.it
authors.forename: Angela M
authors.initials: AM
authors.lastname: Rizzo
authors.forename: Manuela
authors.initials: M
authors.lastname: Negroni
authors.forename: Tiziana
authors.initials: T
authors.lastname: Altiero
authors.forename: Gigliola
authors.initials: G
authors.lastname: Montorfano
authors.forename: Paola
authors.initials: P
authors.lastname: Corsetto
authors.forename: Patrizia
authors.initials: P
authors.lastname: Berselli
authors.forename: Bruno
authors.initials: B
authors.lastname: Berra
authors.forename: Roberto
authors.initials: R
authors.lastname: Guidetti
authors.forename: Lorena
authors.initials: L
authors.lastname: Rebecchi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D003890:Desiccation; D005227:Fatty Acids / Q000032:analysis; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D007448:Invertebrates / Q000737:chemistry / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005227:Fatty Acids; D006360:Heat-Shock Proteins; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase