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THE MECHANISMS OF TROPISTIC REACTIONS AND THE STRYCHNINE EFFECT IN DAPHNIA
1Laboratory of General Physiology, Harvard University, Cambridge.
The Journal of General Physiology
|October 30, 2009
Summary
Strychnine exposure reverses Daphnia
Area of Science:
- Zoology
- Animal Behavior
- Neuroscience
Background:
- Daphnia exhibit complex tropisms, including phototropism and galvanotropism.
- Understanding the mechanisms underlying these responses is crucial for behavioral ecology.
Purpose of the Study:
- To investigate the mechanisms of tropism in Daphnia.
- To test assumptions regarding the control of tropism sign and body orientation.
Main Methods:
- Experiments involving Daphnia exposed to strychnine solutions.
- Observation of phototropism and galvanotropism sign reversals.
- Analysis of body orientation during tropistic responses.
Main Results:
- Strychnine induced a reversal of phototropism from negative to positive.
- Strychnine also reversed galvanotropism from anodic to cathodic.
- Body orientation remained consistent despite sign changes in tropism.
Conclusions:
- The mechanisms controlling the sign of tropism are distinct from those controlling body orientation.
- Changes in tropism sign are mediated by reciprocal innervation of antagonistic muscles in swimming appendages.
- Environmental factors like illumination and chemical agents like strychnine can alter tropism sign.
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