title: Expression of aquaporin-3 and -8 mRNAs in the parr and smolt stages of sockeye salmon, Oncorhynchus nerka: effects of cortisol treatment and seawater acclimation.
abstract: This study aimed to examine the role of 2 aquaporin (AQP) isoforms (AQP3, and -8) in sockeye salmon (Oncorhynchus nerka) in response to a hyperosmotic challenge from freshwater to seawater (SW) during the parr and smoltification (smolt) stages. AQP3 mRNA was primarily detected in the osmoregulatory organs, such as gills, while AQP8 mRNA was primarily found in the intestine. These results suggested that AQP isoforms play a role in osmoregulation in specific osmoregulatory organs. Similarly, AQP3 mRNA expression in the gills (mean values:1.06 ± 0.05 [parr] and 1.29 ± 0.07 [smolt]) was significantly higher than AQP8 mRNA levels (parr: 0.04 ± 0.003; smolt: 0.14 ± 0.004), and in the intestine, AQP8 mRNA expression (parr: 0.89 ± 0.007; smolt: 1.91 ± 0.03) was significantly higher than AQP3 mRNA levels (parr: 0.24 ± 0.006; smolt: 0.83 ± 0.005); these expression patterns were similar in vivo and in vitro. Additionally, AQP mRNA levels were lower in cortisol treated than in control groups. Therefore, these results suggest that AQPs play important roles in the water absorption mechanisms associated with multiple AQP isoforms, and that cortisol enhances the hypo-osmoregulatory capacity of fish in SW, and also controls the expression of AQPs in a hyperosmotic environment.
authors.affiliation: Division of Marine Environment and BioScience, Korea Maritime University, Busan 606-791, Korea.
authors.forename: Young Jae
authors.initials: YJ
authors.lastname: Choi
authors.forename: Hyun Suk
authors.initials: HS
authors.lastname: Shin
authors.forename: Na Na
authors.initials: NN
authors.lastname: Kim
authors.forename: Sung Hwoan
authors.initials: SH
authors.lastname: Cho
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
authors.forename: Jehee
authors.initials: J
authors.lastname: Lee
authors.forename: Cheol Young
authors.initials: CY
authors.lastname: Choi
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D051400:Aquaporin 3 / Q000235:genetics* / Q000378:metabolism; D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005618:Fresh Water; D018507:Gene Expression Regulation, Developmental; D005880:Gills / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D054712:Salinity; D012474:Salmon / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012623:Seawater
chemical_list: D020346:Aquaporins; D029941:Fish Proteins; D051400:Aquaporin 3; D006854:Hydrocortisone