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Microtubules and filaments in ciliate contractility
Society of General Physiologists Series
|January 1, 1975
Summary
Cell body contractility in ciliates like Stentor coeruleus involves myonemes and km fibers. Calcium triggers myoneme contraction, while microtubule sliding in km fibers drives cell extension.
Area of Science:
- Cell Biology
- Biophysics
- Protozoology
Background:
- Heterotrich ciliates exhibit remarkable cell body contractility.
- This contractility is crucial for their survival and movement.
- Two primary contractile systems, myonemes and km fibers, are involved.
Purpose of the Study:
- To elucidate the molecular mechanisms underlying cell body contractility in heterotrich ciliates.
- To investigate the roles of myonemes and km fibers in contraction and extension.
- To understand the calcium-dependent processes involved.
Main Methods:
- Microscopic analysis of Stentor coeruleus.
- Investigation of contractile filament transformations.
- Examination of microtubule array dynamics within km fibers.
Main Results:
- Myoneme contractility is driven by calcium-induced conformational changes in filaments, transforming them into shorter tubular forms.
- Km fibers generate dimensional changes through the sliding of parallel microtubule arrays.
- Cross-bridge morphology suggests a role in generating or regulating microtubule sliding for cell extension.
Conclusions:
- The interaction between myonemes and km fibers provides the basis for cell body contractility in heterotrich ciliates.
- Calcium signaling plays a key role in myoneme-based contraction.
- Microtubule sliding and associated cross-bridges are essential for km fiber function and cell extension.