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Published on: February 26, 2016
Photosensory transduction in unicellular eukaryote Blepharisma
1Department of Biology, Kochi University, Kochi 780-8520, Japan. tmatsuok@cc.kochi-u.ac.jp
The Journal of Experimental Zoology
|May 15, 2001
Summary
Blepharisma protozoa use pink blepharismins as a pH indicator to sense light. Light triggers a decrease in H+ concentration, signaling a photophobic response.
Area of Science:
- Cell biology
- Photobiology
- Protozoology
Background:
- Blepharisma exhibits a step-up photophobic response.
- This response involves a photosensory complex with blepharismins and a 200-kDa membrane protein.
- These components are located in pigment granules beneath the plasma membrane.
Purpose of the Study:
- To investigate the role of blepharismins in phototransduction.
- To utilize blepharismins as an endogenous pH indicator.
- To elucidate the mechanism of photophobic response signaling in Blepharisma.
Main Methods:
- Measuring fluorescence intensity of isolated blepharismins at varying H+ concentrations.
- Observing changes in fluorescence intensity in response to light stimulation in intact cells.
- Correlating fluorescence changes with H+ concentration shifts.
Main Results:
- Blepharismin fluorescence intensity is sensitive to H+ concentration.
- Light stimulation caused a decrease in fluorescence in the anterior cell region.
- This suggests a localized drop in H+ concentration upon light exposure.
Conclusions:
- Blepharismins function as a pH indicator in vivo.
- Phototransduction involves H+ translocation across pigment granule membranes.
- This process leads to increased cytosolic H+ concentration near the plasma membrane, mediating the photophobic response.
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