title: Opposing effects of oxidative challenge and carotenoids on antioxidant status and condition-dependent sexual signalling.
abstract: Several recent hypotheses consider oxidative stress to be a primary constraint ensuring honesty of condition-dependent carotenoid-based signalling. The key testable difference between these hypotheses is the assumed importance of carotenoids for redox homeostasis, with carotenoids being either antioxidant, pro-oxidant or unimportant. We tested the role of carotenoids in redox balance and sexual signalling by exposing adult male zebra finches (Taeniopygia guttata) to oxidative challenge (diquat dibromide) and manipulating carotenoid intake. As the current controversy over the importance of carotenoids as antioxidants could stem from the hydrophilic basis of commonly-used antioxidant assays, we used the novel measure of in vivo lipophilic antioxidant capacity. Oxidative challenge reduced beak pigmentation but elicited an increase in antioxidant capacity suggesting resource reallocation from signalling to redox homeostasis. Carotenoids counteracted the effect of oxidative challenge on lipophilic (but not hydrophilic) antioxidant capacity, thereby supporting carotenoid antioxidant function in vivo. This is inconsistent with hypotheses proposing that signalling honesty is maintained through either ROS-induced carotenoid degradation or the pro-oxidant effect of high levels of carotenoid-cleavage products acting as a physiological handicap. Our data further suggest that assessment of lipophilic antioxidant capacity is necessary to fully understand the role of redox processes in ecology and evolution.
authors.affiliation: Institute of Vertebrate Biology, v.v.i., The Czech Academy of Sciences, Květná 8, Brno 603 65, Czech Republic.|Charles University in Prague, Faculty of Science, Department of Zoology, Viničná 7, 128 44 Praha 2, Czech Republic.
authors.forename: Oldřich
authors.initials: O
authors.lastname: Tomášek
authors.affiliation: Charles University in Prague, Faculty of Science, Department of Zoology, Viničná 7, 128 44 Praha 2, Czech Republic.
authors.forename: Barbora
authors.initials: B
authors.lastname: Gabrielová
authors.affiliation: Institute of Chemical Technology Prague, Technická 5, 166 28 Praha 6, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Kačer
authors.affiliation: Institute of Experimental Botany, v.v.i., The Czech Academy of Sciences, Rozvojová 313, 165 02 Praha 6, Czech Republic.|Department of Quality of Agricultural Products, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences, Kamýcká 1176, 165 21 Praha 6, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Maršík
authors.affiliation: Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences, Kamýcká 1176, 165 21 Praha 6, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Svobodová
authors.affiliation: Institute of Chemical Technology Prague, Technická 5, 166 28 Praha 6, Czech Republic.
authors.forename: Kamila
authors.initials: K
authors.lastname: Syslová
authors.affiliation: Charles University in Prague, Faculty of Science, Department of Zoology, Viničná 7, 128 44 Praha 2, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Vinkler
authors.affiliation: Institute of Vertebrate Biology, v.v.i., The Czech Academy of Sciences, Květná 8, Brno 603 65, Czech Republic.|Charles University in Prague, Faculty of Science, Department of Zoology, Viničná 7, 128 44 Praha 2, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Albrecht
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism*; D046369:Finches / Q000502:physiology*; D006801:Humans; D008297:Male; D018384:Oxidative Stress; D012726:Sexual Behavior, Animal; D015398:Signal Transduction
chemical_list: D000975:Antioxidants; D002338:Carotenoids