Role of H(+)-pyrophosphatase activity in the regulation of intracellular pH in a scuticociliate parasite of turbot: Physiological effects

• Published in: Experimental Parasitology
• Main Authors: Mallo Seijas, Natalia, Lamas Fernández, Jesús, Felipe González, Ana Paula de, Sueiro Benavides, Rosa Ana, Fontenla Iglesias, Francisco, Leiro Vidal, José Manuel
• Other Authors: Universidade de Santiago de Compostela. Departamento de Microbioloxía e Parasitoloxía, Universidade de Santiago de Compostela. Instituto de Acuicultura, Universidade de Santiago de Compostela. Instituto de Investigación e Análises Alimentarias
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier
• Subjects: Philasterides dicentrarchi; Intracellular pH; Calcium; ATP; H+-PPase; Osmoregulation; Lamas; Leiro; Turbot
• Online Access: http://hdl.handle.net/10347/18174; https://doi.org/10.1016/j.exppara.2016.07.012

This is the accepted manuscript of the following article: Mallo, N., Lamas, J., de Felipe, A.P., Sueiro, R.A., Fontenla, F. & Leiro, J.M. (2016). Role of H(+)-pyrophosphatase activity in the regulation of intracellular pH in a scuticociliate parasite of turbot: Physiological effects. Experimental Parasitolology, 169, 59-68. doi:10.1016/j.exppara.2016.07.012 The scuticociliatosis is a very serious disease that affects the cultured turbot, and whose causal agent is the anphizoic and marine euryhaline ciliate Philasterides dicentrarchi. Several protozoans possess acidic organelles that contain high concentrations of pyrophosphate (PPi), Ca(2+) and other elements with essential roles in vesicular trafficking, pH homeostasis and osmoregulation. P. dicentrarchi possesses a pyrophosphatase (H(+)-PPase) that pumps H(+) through the membranes of vacuolar and alveolar sacs. These compartments share common features with the acidocalcisomes described in other parasitic protozoa (e.g. acid content and Ca(2+) storage). We evaluated the effects of Ca(2+) and ATP on H (+)-PPase activity in this ciliate and analyzed their role in maintaining intracellular pH homeostasis and osmoregulation, by the addition of PPi and inorganic molecules that affect osmolarity. Addition of PPi led to acidification of the intracellular compartments, while the addition of ATP, CaCl2 and bisphosphonates analogous of PPi and Ca(2+) metabolism regulators led to alkalinization and a decrease in H(+)-PPase expression in trophozoites. Addition of NaCl led to proton release, intracellular Ca(2+) accumulation and downregulation of H(+)-PPase expression. We conclude that the regulation of the acidification of intracellular compartments may be essential for maintaining the intracellular pH homeostasis necessary for survival of ciliates and their adaptation to salt stress, which they will presumably face during the endoparasitic phase, in which the salinity levels are lower than in their natural environment This work was financially supported by the ...