Regulation of intracellular pH in cnidarians: response to acidosis in Anemonia viridis

• Main Authors: Laurent, Julien, Venn, Alexander A, Tambutté, Eric, Ganot, Philippe, Allemand, Denis, Tambutté, Sylvie
• Format: Dataset
• Language: English
• Published: PANGAEA 2013
• Subjects: Acid-base regulation; Alkalinity; total; standard deviation; Anemonia viridis; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cnidaria; Coast and continental shelf; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Mediterranean Sea; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; intracellular; standard error; Potentiometric; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.837087; https://doi.org/10.1594/PANGAEA.837087

The regulation of intracellular pH (pHi) is a fundamental aspect of cell physiology that has received little attention in studies of the phylum Cnidaria, which includes ecologically important sea anemones and reef-building corals. Like all organisms, cnidarians must maintain pH homeostasis to counterbalance reductions in pHi, which can arise because of changes in either intrinsic or extrinsic parameters. Corals and sea anemones face natural daily changes in internal fluids, where the extracellular pH can range from 8.9 during the day to 7.4 at night. Furthermore, cnidarians are likely to experience future CO2-driven declines in seawater pH, a process known as ocean acidification. Here, we carried out the first mechanistic investigation to determine how cnidarian pHi regulation responds to decreases in extracellular and intracellular pH. Using the anemone Anemonia viridis, we employed confocal live cell imaging and a pH-sensitive dye to track the dynamics of pHi after intracellular acidosis induced by acute exposure to decreases in seawater pH and NH4Cl prepulses. The investigation was conducted on cells that contained intracellular symbiotic algae (Symbiodinium sp.) and on symbiont-free endoderm cells. Experiments using inhibitors and Na-free seawater indicate a potential role of Na/H plasma membrane exchangers (NHEs) in mediating pHi recovery following intracellular acidosis in both cell types. We also measured the buffering capacity of cells, and obtained values between 20.8 and 43.8 mM per pH unit, which are comparable to those in other invertebrates. Our findings provide the first steps towards a better understanding of acid-base regulation in these basal metazoans, for which information on cell physiology is extremely limited.