Articolo in rivista, 1993, ENG

Photosensory transduction in ciliates. Role of intracellular pH and comparison between Stentor Coeruleus and Blepharisma japonicum

Fabczak H., Fabczak S., Song P.-S., Checcucci G., Ghetti F., Lenci F.

Department of Cell Biology, Institute of Experimental Biology, Polish Academy of Science, Warsaw (Poland). Department of Chemistry and Institute for Cellular and Molecular Photobiology, University of Nebraska, Lincoln, NE 68588-0304 (USA). Instituto Biofisica-CNR, Pisa 56100 (Italy)

To test the hypothesis that light signal transduction in the unicellular ciliates Stentor coeruleus and Blepharisma japonicum involves a change in intracellular pH as an initial signal following photoexcitation, we studied the dependence of the photophobic responses of the cells to changes in extracellular pH and to reagents that specifically affect intracellular pH. The extracellular pH can modify not only the intracellular pH, but can even reverse the sign of the pH gradient across the cell membrane. Thus, as predicted by the hypothesis, low extracellular pH reversibly inhibited the photophobic response of the ciliates. The intracellular pH-modulating reagents tested included ammonium chloride, a membrane-permeable weak acid that lowers the intracellular pH, and the protonophores carbonylcyanide m-chlorophenyl-hydrazone (CCCP) and carbonylcyanide p-(trifluoromethoxy)-phenyl-hydrazone (FCCP), which collapse the pH gradient across the cell membrane. The low pH and protonophore treatments caused a gradual inhibition of the photophobic responses in both ciliates. The observed reduction of the responsiveness of the cells to visible light can be attributed to the alteration of the intracellular pH, which is suggested to play a specific role in the photosensory transduction in both Stentor coeruleus and Blepharisma japonicum.

Journal of photochemistry and photobiology. B, Biology (Print) 21 (1), pp. 47–52

Keywords

Intracellular pH, Light signal, Photophobic response, Photomovement, Blepharisma japonicum, Stentor coeruleus

CNR authors

Checcucci Giovanni, Lenci Francesco, Ghetti Francesco

CNR institutes

ID: 267238

Year: 1993

Type: Articolo in rivista

Creation: 2013-10-28 12:06:16.000

Last update: 2013-10-28 12:06:16.000

External links

OAI-PMH: Dublin Core

OAI-PMH: Mods

OAI-PMH: RDF

External IDs

CNR OAI-PMH: oai:it.cnr:prodotti:267238