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CAFFEINE‐ENHANCED PHOTOMOVEMENT IN THE CILIATE, STENTOR COERULEUS
Author(s) -
Prusti Rabi K.,
Song PillSoon,
Häder DonatPeter,
Häderi Maria
Publication year - 1984
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1984.tb04600.x
Subject(s) - phototaxis , biophysics , caffeine , pigment , ciliate , fluorescence , chemistry , calcium , membrane potential , biology , botany , optics , physics , ecology , organic chemistry , endocrinology
The effects of caffeine, ionophores and calcium flux blockers on the step‐up photophobic response, phototactic orientation and the intracellularly recorded, light‐induced electrical action potential were studied in the ciliate, Stentor coeruleus . Caffeine alters the absorption and CD spectra and enhances the fluorescence of the photoreceptor pigment, stentorin. Independent of its effects on the spectroscopic properties of the photoreceptor pigment, caffeine shortens the photophobic response time by enhancing the Ca 2+ conductivity of membranes, while Ca 2+ flux blockers (LaCI 3 or ruthenium red) prolong it; both effects cancel each other. Evidence is presented that phototactic orientation is brought about by repetitive photophobic responses, since a change in the phobic response time results in a decreased accuracy of phototaxis.