title: Adjustments of molecular key components of branchial ion and pH regulation in Atlantic cod (Gadus morhua) in response to ocean acidification and warming.
abstract: Marine teleost fish sustain compensation of extracellular pH after exposure to hypercapnia by means of efficient ion and acid-base regulation. Elevated rates of ion and acid-base regulation under hypercapnia may be stimulated further by elevated temperature. Here, we characterized the regulation of transepithelial ion transporters (NKCC1, NBC1, SLC26A6, NHE1 and 2) and ATPases (Na(+)/K(+) ATPase and V-type H(+) ATPase) in gills of Atlantic cod (Gadus morhua) after 4 weeks of exposure to ambient and future PCO2 levels (550 μatm, 1200 μatm, 2200 μatm) at optimum (10 °C) and summer maximum temperature (18 °C), respectively. Gene expression of most branchial ion transporters revealed temperature- and dose-dependent responses to elevated PCO2. Transcriptional regulation resulted in stable protein expression at 10 °C, whereas expression of most transport proteins increased at medium PCO2 and 18 °C. mRNA and protein expression of distinct ion transport proteins were closely co-regulated, substantiating cellular functional relationships. Na(+)/K(+) ATPase capacities were PCO2 independent, but increased with acclimation temperature, whereas H(+) ATPase capacities were thermally compensated but decreased at medium PCO2 and 10 °C. When functional capacities of branchial ATPases were compared with mitochondrial F1Fo ATP-synthase strong correlations of F1Fo ATP-synthase and ATPase capacities generally indicate close coordination of branchial aerobic ATP demand and supply. Our data indicate physiological plasticity in the gills of cod to adjust to a warming, acidifying ocean within limits. In light of the interacting and non-linear, dose-dependent effects of both climate factors the role of these mechanisms in shaping resilience under climate change remains to be explored.
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Michael
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Kreiss
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, The Sven Lovén Centre for Marine Sciences, Kristineberg, 45178 Fiskebäckskil, Sweden.
authors.forename: Marian Y
authors.initials: MY
authors.lastname: Hu
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Nils
authors.initials: N
authors.lastname: Koschnick
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Bickmeyer
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, The Sven Lovén Centre for Marine Sciences, Kristineberg, 45178 Fiskebäckskil, Sweden.
authors.forename: Sam
authors.initials: S
authors.lastname: Dupont
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany.
authors.forename: Hans-O
authors.initials: HO
authors.lastname: Pörtner
authors.affiliation: Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, 27570 Bremerhaven, Germany. Electronic address: Magnus.Lucassen@awi.de.
authors.forename: Magnus
authors.initials: M
authors.lastname: Lucassen
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002245:Carbon Dioxide / Q000737:chemistry; D057231:Climate Change; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D048389:Gadus morhua / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006863:Hydrogen-Ion Concentration; D008297:Male; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*; D013696:Temperature
chemical_list: D029941:Fish Proteins; D002245:Carbon Dioxide; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases
keywords: Acid–base regulation; Fish gills; Marine teleost; NBC1; Na(+)/HCO(3)(−) co-transporter 1