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Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Published on: September 20, 2011
Gravity perception and signal transduction in single cells.
1DLR (German Aerospace Establishment) Institute of Aerospace Medicine, Department of Biology, Cologne, Germany.
Acta Astronautica
|October 1, 1995
Summary
The giant amoeba Physarum polycephalum exhibits gravitaxis, orienting itself using gravity. This study reveals its acceleration-sensing mechanism involves changes in cyclic adenosine monophosphate (cAMP) signaling.
Area of Science:
- Cell Biology
- Biophysics
- Astrobiology
Background:
- Cellular signal processing shares fundamental mechanisms across unicellular and multicellular organisms.
- Free-living cells, like Physarum polycephalum, utilize gravity for spatial orientation (gravitaxis).
- Understanding cellular responses to gravity is crucial for astrobiology and fundamental cell biology.
Purpose of the Study:
- To investigate the gravitaxis and gravity-modulated contraction rhythms of Physarum polycephalum.
- To determine the acceleration-sensitivity threshold of the gravireceptor in Physarum polycephalum.
- To elucidate the signal transduction pathway involved in the cell's response to acceleration stimuli.
Main Methods:
- Experiments included 180-degree turn tests, simulated near-weightlessness (clinostat), and actual spaceflight (Spacelab D1, IML-1, IML-2).
- Acceleration-sensitivity threshold was determined to understand stimulus perception.
- Ground-based experiments analyzed second messenger levels, specifically cyclic adenosine monophosphate (cAMP).
Main Results:
- Physarum polycephalum demonstrated gravitaxis and modulation of its rhythmic contractions by gravity.
- The IML-2 experiment provided data on the gravireceptor's acceleration-sensitivity threshold.
- Acceleration stimuli were found to induce changes in intracellular cAMP levels.
Conclusions:
- Physarum polycephalum's response to acceleration involves a conserved second messenger pathway.
- The findings suggest a commonality in signal transduction mechanisms for gravity response across different organisms.
- This research provides insights into the biophysical basis of cellular graviperception.
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