title: Gene expression profiling in gills of the great spider crab Hyas araneus in response to ocean acidification and warming.
abstract: BACKGROUND
  Hypercapnia and elevated temperatures resulting from climate change may have adverse consequences for many marine organisms. While diverse physiological and ecological effects have been identified, changes in those molecular mechanisms, which shape the physiological phenotype of a species and limit its capacity to compensate, remain poorly understood. Here, we use global gene expression profiling through RNA-Sequencing to study the transcriptional responses to ocean acidification and warming in gills of the boreal spider crab Hyas araneus exposed medium-term (10 weeks) to intermediate (1,120 μatm) and high (1,960 μatm) PCO2 at different temperatures (5°C and 10°C).
  
  
  RESULTS
  The analyses reveal shifts in steady state gene expression from control to intermediate and from intermediate to high CO2 exposures. At 5°C acid-base, energy metabolism and stress response related genes were upregulated at intermediate PCO2, whereas high PCO2 induced a relative reduction in expression to levels closer to controls. A similar pattern was found at elevated temperature (10°C). There was a strong coordination between acid-base, metabolic and stress-related processes. Hemolymph parameters at intermediate PCO2 indicate enhanced capacity in acid-base compensation potentially supported by upregulation of a V-ATPase. The likely enhanced energy demand might be met by the upregulation of the electron transport system (ETS), but may lead to increased oxidative stress reflected in upregulated antioxidant defense transcripts. These mechanisms were attenuated by high PCO2, possibly as a result of limited acid-base compensation and metabolic down-regulation.
  
  
  CONCLUSIONS
  Our findings indicate a PCO2 dependent threshold beyond which compensation by acclimation fails progressively. They also indicate a limited ability of this stenoecious crustacean to compensate for the effects of ocean acidification with and without concomitant warming.
authors.affiliation: Integrative Ecophysiology, Alfred Wegener Institute, Bremerhaven, Germany. Lars.Harms@awi.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Harms
authors.forename: Stephan
authors.initials: S
authors.lastname: Frickenhaus
authors.forename: Melanie
authors.initials: M
authors.lastname: Schiffer
authors.forename: Felix Christopher
authors.initials: FC
authors.lastname: Mark
authors.forename: Daniela
authors.initials: D
authors.lastname: Storch
authors.forename: Christoph
authors.initials: C
authors.lastname: Held
authors.forename: Hans-Otto
authors.initials: HO
authors.lastname: Pörtner
authors.forename: Magnus
authors.initials: M
authors.lastname: Lucassen
mesh_terms: D000818:Animals; D003386:Brachyura / Q000033:anatomy & histology / Q000235:genetics*; D002245:Carbon Dioxide / Q000633:toxicity*; D004579:Electron Transport; D004734:Energy Metabolism; D020869:Gene Expression Profiling / Q000379:methods*; D005786:Gene Expression Regulation; D005880:Gills / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008297:Male; D018384:Oxidative Stress; D012623:Seawater / Q000737:chemistry*; D017423:Sequence Analysis, RNA / Q000379:methods*; D013696:Temperature
chemical_list: D002245:Carbon Dioxide