Alterations of photophobic motile response in Stentor by cyclic guanosine 3 ',5 '-monophosphate-elevating agents

Citation
M. Walerczyk et S. Fabczak, Alterations of photophobic motile response in Stentor by cyclic guanosine 3 ',5 '-monophosphate-elevating agents, ACT PROTOZ, 40(2), 2001, pp. 153-157
Citations number
27
Categorie Soggetti
Biology
Journal title
ACTA PROTOZOOLOGICA
ISSN journal
00651583 → ACNP
Volume
40
Issue
2
Year of publication
2001
Pages
153 - 157
Database
ISI
SICI code
0065-1583(200105)40:2<153:AOPMRI>2.0.ZU;2-Z
Abstract
The effects of exogenous cyclic nucleotides and modulators of the cyclic nu cleotide signaling pathway on the step-up photophobic response have been st udied in the ciliate Stenter coeruleus. To attain this, the latency time fo r the ciliary stop response and the ciliary reversal duration has been esti mated using microscope videorecording and dark-field macro-photography. Mem brane-permeable, slowly hydrolyzable analogs of cyclic GMP, 8-Br-cGMP and d b-cGMP, significantly increase the latency time of ciliary stop response an d decrease the period of ciliary reversal. By contrast, cyclic AMP analogs, 8-Br-cAMP or db-cAMP, had no measurable effect on the photophobic response parameters. The effects of the exogenous cGMP are mimicked by the applicat ion of the non-specific PDE inhibitor IBMX or zaprinast, a specific cGMP-PD E inhibitor. These behavioral observations suggest that in vivo, the intern al level of presumed cGMP, but not cAMP, is possibly a limiting factor for the time course of the motile avoiding response of Stenter, and they furthe r support the hypothesis that cGMP metabolism may play a role in photosigna l transduction in these cells.