Related Experiment Videos
Hyperpolarization- and depolarization-activated Ca2+ currents in Paramecium trigger behavioral changes and cGMP
J E Schultz1, Y Guo, G Kleefeld
1Faculty of Chemistry and Pharmacy, University of Tübingen, 72076 Tübingen, Germany.
The Journal of Membrane Biology
|April 1, 1997
Summary
In Paramecium, calcium ion (Ca2+) fluxes triggering behavioral changes are separate from those causing cyclic guanosine monophosphate (cGMP) production. These distinct Ca2+ pathways indicate different cellular responses to stimuli.
Area of Science:
- Cell Biology
- Neuroscience
- Biochemistry
Background:
- Calcium ions (Ca2+) play crucial roles in cellular signaling, influencing behavior and biochemical pathways.
- In Paramecium, Ca2+ fluxes are known to regulate ciliary function and swimming behavior.
- The relationship between Ca2+ entry, behavioral responses, and intracellular signaling molecules like cyclic guanosine monophosphate (cGMP) requires further elucidation.
Purpose of the Study:
- To investigate the compartmentalization and functional distinctness of Ca2+ fluxes in Paramecium.
- To determine whether Ca2+ entry stimulating behavioral responses is coupled to cGMP biosynthesis.
- To differentiate the roles of hyperpolarization- and depolarization-activated Ca2+ currents.
Main Methods:
- Utilized ethanol for deciliation, colchicine to inhibit reciliation, and amiloride to modulate ion fluxes in Paramecium.
- Monitored cGMP biosynthesis and stereotypic swimming behavior as indicators of Ca2+ entry.
- Employed permeabilized cells and cell-free enzyme assays to exclude persistent effects of ethanol on cellular components.
Main Results:
- Both colchicine and amiloride induced a transient ciliary augmentation (fast swimming), indicating hyperpolarization and coupled cGMP formation.
- Ethanol-deciliated cells showed no response to depolarization, but recovered swimming behavior, while cGMP formation remained depressed.
- Amiloride treatment dissociated hyperpolarization-elicited behavior from cGMP formation, demonstrating separate pathways.
Conclusions:
- Depolarization- and hyperpolarization-stimulated behavioral responses and cGMP formation in Paramecium are not coupled.
- Behavioral changes are initiated by Ca2+ inward currents of lower magnitude compared to those triggering intracellular cGMP formation.
- This study reveals distinct Ca2+ signaling pathways mediating behavioral and biochemical responses in Paramecium.