Photosensory transduction in ciliates. IV. Modulation of the photomovement response of Blepharisma japonicum by cGMP.
The effect of various modulators of cytoplasmic guanosine 3',5'-cyclic monophosphate (cGMP) level on the step-up photophobic responses in Blepharisma japonicum has been investigated to clarify the possible role of cGMP in the mechanism of photosensory signal transduction. Membrane-permeable analogs of cGMP, 8-bromo-guanosine 3',5'-cyclic monophosphate or dibutyryl cGMP, caused a marked dose-dependent prolongation of the latency for the photophobic response, resulting in inhibition of the photophobic response in Blepharisma japonicum. A similar effect was observed when cells were treated with 3'-isobutylmethylxanthine (IBMX), a phosphodiesterase inhibitor, and pertussis toxin, a G-protein activity modulator. The G-protein activator, fluoroaluminate, and 6-anilino-5,8-quinolinedione (LY 83583), an agent which effectively lowers the cytoplasmic cGMP level, significantly enhanced the photoresponsiveness of these ciliates to visible light stimuli. These results suggest that cellular cGMP serves as a signal modulator in the photophobic response of Blepharisma japonicum.
Fabczak
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Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw.
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D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D002465:Cell Movement / Q000187:drug effects / Q000528:radiation effects; D002772:Cholera Toxin / Q000494:pharmacology; D016798:Ciliophora / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology*; D008027:Light; D037342:Pertussis Toxin; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000634:Aminoquinolines; D010566:Virulence Factors, Bordetella; C016276:8-bromocyclic GMP; D003995:Dibutyryl Cyclic GMP; D002772:Cholera Toxin; C041715:6-anilino-5,8-quinolinedione; D037342:Pertussis Toxin; D006152:Cyclic GMP; D015056:1-Methyl-3-isobutylxanthine