title: Antioxidant capacity develops with maturation in the deep-diving hooded seal.
abstract: Maturation in hooded seals is characterized by the rapid development of their physiological diving capacity and is accompanied by increases in oxidant production but not oxidative damage. To test the hypothesis that the antioxidant system of hooded seals develops as they transition from a terrestrial to an aquatic environment, we obtained the complete cDNA sequence that encodes the NF-E2-related factor 2 (Nrf2), a central regulator of the antioxidant response, and compared Nrf2 mRNA and protein expression levels in muscle samples from neonate, weaned pups and adult hooded seals, along with glutathione (GSH) levels and the activity/protein content of the antioxidant enzymes catalase, glutathione peroxidase (GPx), peroxyredoxin VI (PrxVI), thioredoxin 1 (Trx1), thioredoxin reductase (TrxR), glutaredoxin 1 (Glrx1), glutathione disulphide reductase, glutathione S-transferase and glutamate-cysteine ligase. The Nrf2 of the hooded seal is 1822 bp long and encodes a protein of 606 amino acids with a leucine zipper domain and Keap1-mediated proteosomal degradation residues, which are key for Nrf2 function and regulation. Although neither Nrf2 mRNA nor Nrf2 nuclear protein content are higher in adults than in pups, GSH levels along with GPx, PrxVI, Trx1, TrxR and Glrx1 activity/protein content increase with maturation, suggesting that the potential for peroxide removal increases with development in hooded seals, and that these enzymes contribute to the regulation of the intracellular redox state and the prevention of oxidative damage in these deep-diving mammals.
authors.affiliation: School of Natural Sciences, University of California Merced, 5200 N Lake Road, Merced, CA 95343, USA. jvazquez-medina@ucmerced.edu
authors.forename: José Pablo
authors.initials: JP
authors.lastname: Vázquez-Medina
authors.forename: José Guadalupe
authors.initials: JG
authors.lastname: Soñanez-Organis
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Burns
authors.forename: Tania
authors.initials: T
authors.lastname: Zenteno-Savín
authors.forename: Rudy M
authors.initials: RM
authors.lastname: Ortiz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D054477:Glutaredoxins / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D008969:Molecular Sequence Data; D051267:NF-E2-Related Factor 2 / Q000235:genetics* / Q000378:metabolism; D010545:Peroxides / Q000378:metabolism; D046048:Seals, Earless / Q000254:growth & development* / Q000378:metabolism*; D016415:Sequence Alignment; D013880:Thioredoxin-Disulfide Reductase / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism
chemical_list: D000975:Antioxidants; D054477:Glutaredoxins; D051267:NF-E2-Related Factor 2; D010545:Peroxides; D013879:Thioredoxins; D002374:Catalase; D005979:Glutathione Peroxidase; D013880:Thioredoxin-Disulfide Reductase; D005978:Glutathione