Differential acid-base regulation in various gills of the green crab Carcinus maenas: Effects of elevated environmental pCO2

Comp Biochem Physiol A Mol Integr Physiol. 2013 Jan;164(1):54-65. doi: 10.1016/j.cbpa.2012.09.016. Epub 2012 Sep 26.

Abstract

Euryhaline decapod crustaceans possess an efficient regulation apparatus located in the gill epithelia, providing a high adaptation potential to varying environmental abiotic conditions. Even though many studies focussed on the osmoregulatory capacity of the gills, acid-base regulatory mechanisms have obtained much less attention. In the present study, underlying principles and effects of elevated pCO(2) on acid-base regulatory patterns were investigated in the green crab Carcinus maenas acclimated to diluted seawater. In gill perfusion experiments, all investigated gills 4-9 were observed to up-regulate the pH of the hemolymph by 0.1-0.2 units. Anterior gills, especially gill 4, were identified to be most efficient in the equivalent proton excretion rate. Ammonia excretion rates mirrored this pattern among gills, indicating a linkage between both processes. In specimen exposed to elevated pCO(2) levels for at least 7 days, mimicking a future ocean scenario as predicted until the year 2300, hemolymph K(+) and ammonia concentrations were significantly elevated, and an increased ammonia excretion rate was observed. A detailed quantitative gene expression analysis revealed that upon elevated pCO(2) exposure, mRNA levels of transcripts hypothesized to be involved in ammonia and acid-base regulation (Rhesus-like protein, membrane-bound carbonic anhydrase, Na(+)/K(+)-ATPase) were affected predominantly in the non-osmoregulating anterior gills.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acclimatization
  • Acid-Base Equilibrium / genetics*
  • Ammonia / metabolism
  • Animals
  • Brachyura / genetics
  • Brachyura / physiology*
  • Carbon Dioxide / metabolism*
  • Carbonic Anhydrases / genetics
  • Carbonic Anhydrases / metabolism
  • Gene Expression Regulation
  • Gills / cytology
  • Gills / metabolism*
  • Hemolymph / metabolism
  • Hydrogen-Ion Concentration
  • Male
  • Potassium / metabolism
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • Real-Time Polymerase Chain Reaction
  • Salinity
  • Seawater
  • Sodium Chloride / pharmacology
  • Sodium-Potassium-Exchanging ATPase / genetics
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • Water-Electrolyte Balance

Substances

  • RNA, Messenger
  • Carbon Dioxide
  • Sodium Chloride
  • Ammonia
  • Carbonic Anhydrases
  • Sodium-Potassium-Exchanging ATPase
  • Potassium