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

Mallo, N., Lamas, J., de Felipe, A.-P., Sueiro, R.-A., Fontenla, F. and Leiro, J.-M. (2016) Role of H+-pyrophosphatase activity in the regulation of intracellular pH in a scuticociliate parasite of turbot: Physiological effects. Experimental Parasitology, 169, pp. 59-68. (doi: 10.1016/j.exppara.2016.07.012) (PMID:27480055)

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Abstract

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), Ca2+ 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 Ca2+ storage). We evaluated the effects of Ca2+ 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 Ca2+ metabolism regulators led to alkalinization and a decrease in H+-PPase expression in trophozoites. Addition of NaCl led to proton release, intracellular Ca2+ 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.

Item Type:Articles
Additional Information:This study was financially supported by grants AGL2014-57125- R and AGL2014-53190-REDC from the Ministerio de Economía y Competitividad (Spain), by grant GPC2014/069 from the Xunta de Galicia (Spain), and by PARAFISHCONTROL project. This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 634429.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Mallo, Dr Natalia
Authors: Mallo, N., Lamas, J., de Felipe, A.-P., Sueiro, R.-A., Fontenla, F., and Leiro, J.-M.
College/School:College of Medical Veterinary and Life Sciences > School of Infection & Immunity
Journal Name:Experimental Parasitology
Publisher:Elsevier
ISSN:0014-4894
ISSN (Online):1090-2449
Published Online:30 July 2016

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