title: Antioxidants and embryo phenotype: is there experimental evidence for strong integration of the antioxidant system?
abstract: Organisms have evolved complex defense systems against oxidative stress. Bird eggs contain maternally derived antioxidants that protect embryos from oxidative damage. The antioxidant system components are thought to be integrated, but few studies have analyzed the covariation between antioxidant concentrations, embryo 'oxidative status' and morphology. In addition, no study has tested the effects of experimental change in yolk antioxidant concentration on other antioxidants, on their reciprocal relationships and on their relationships with embryo oxidative status or growth, which are expected if antioxidants defenses are integrated. In yellow-legged gull (Larus michahellis) embryos, we analyzed the covariation between several antioxidants, markers of 'oxidative status' [total antioxidant capacity (TAC), concentration of pro-oxidants (TOS), lipid peroxidation (LPO) and protein carbonylation (PC)] in the yolk, liver and brain, and morphology. Yolk and liver antioxidant concentrations were positively correlated reciprocally and with embryo size, and positively predicted TAC but not oxidative status. TOS and LPO were positively correlated in the liver, while TAC and LPO were negatively correlated in the brain. Weak relationships existed between antioxidants and TOS, PC and LPO. The effects of antioxidants on oxidative status and morphology were non-synergistic. An experimental physiological increase in yolk vitamin E had very weak effects on the relationships between other antioxidants or oxidative status and vitamin E concentration, the concentration of other antioxidants or oxidative status; the covariation between other antioxidants and oxidative status, and relationships between morphology or oxidative status and other antioxidants, challenging the common wisdom of strong functional relationships among antioxidants, at least for embryos in the wild.
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Cristina Daniela
authors.initials: CD
authors.lastname: Possenti
authors.affiliation: Department of Animal Science, University of Yüzüncü Yil, Van 65090, Turkey.
authors.forename: Filiz
authors.initials: F
authors.lastname: Karadas
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Graziano
authors.initials: G
authors.lastname: Colombo
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Caprioli
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Rubolini
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Aldo
authors.initials: A
authors.lastname: Milzani
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Isabella Dalle
authors.initials: ID
authors.lastname: Donne
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Saino
authors.affiliation: Department of Biosciences, University of Milan, via Celoria 26, Milan I-20133, Italy marco.parolini@unimi.it.
authors.forename: Marco
authors.identifier: 0000-0003-0226-1709
authors.initials: M
authors.lastname: Parolini
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D046091:Charadriiformes / Q000196:embryology* / Q000378:metabolism; D004530:Egg Yolk / Q000378:metabolism; D004531:Eggs / Q000032:analysis; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism*; D005260:Female; D015227:Lipid Peroxidation; D018384:Oxidative Stress; D050050:Protein Carbonylation
chemical_list: D000975:Antioxidants
keywords: Bivariate mixed models; Larus michahellis; Maternal effects; Morphological traits; Oxidative status; Vitamin E