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DARK ADAPTATION AND THE DARK GROWTH RESPONSE OF PHYCOMYCES.
1Laboratory of General Physiology, Harvard University, Cambridge.
The Journal of General Physiology
|October 30, 2009
Summary
The fungus Phycomyces exhibits a delayed "dark growth" response to light changes, with faster reactions following brighter light. This study investigates the underlying photochemistry of this fungal growth phenomenon.
Area of Science:
- Mycology
- Plant Physiology
- Photobiology
Background:
- Fungal sporangiophores, like those of Phycomyces, display complex responses to light stimuli.
- Understanding these responses is crucial for elucidating phototropism and growth regulation in fungi.
Purpose of the Study:
- To investigate the kinetics and characteristics of the "dark growth" response in light-adapted Phycomyces sporangiophores.
- To explore the relationship between light intensity, adaptation, and the latent period of the dark growth response.
Main Methods:
- Observing and measuring the elongation rate of Phycomyces sporangiophores under controlled light and dark conditions.
- Analyzing the reaction time and adaptation rates in response to varying light intensities.
Main Results:
- A temporary decrease in elongation rate (dark growth response) occurs after a latent period upon sudden darkening.
- The reaction time is inversely related to the intensity of prior illumination.
- The rate of dark adaptation is proportional to the logarithm of the preceding light intensity.
Conclusions:
- The dark growth response in Phycomyces involves a distinct latent period and is influenced by prior light exposure.
- A model suggesting a photostationary state, where reaction rates are proportional to the logarithm of light intensity, best explains the observed phenomena.
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