Adjustments of molecular key components of branchial ion and pH regulation in Atlantic cod (Gadus morhua) in response to ocean acidification and warming.

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
• Main Authors: Michael, Katharina, Kreiß, Cornelia, Hu, Marian Y.A., Koschnick, Nils, Bickmeyer, Ulf, Dupont, S., Pörtner, Hans-Otto, Lucassen, Magnus
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: ELSEVIER SCIENCE INC 2016
• Subjects: atlantic cod; Gadus morhua; Ocean acidification
• Online Access: https://epic.awi.de/id/eprint/40410/; https://epic.awi.de/id/eprint/40410/1/Michael_etal2016.pdf; https://hdl.handle.net/10013/epic.47473; https://hdl.handle.net/10013/epic.47473.d001

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 4weeks of exposure to ambient and future PCO2 levels (550μatm, 1200μatm, 2200μatm) 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