Redox regulation of phototactic migration in the green alga Chlamydomonas reinhardtii and its possible application

Abstract

Most flagellated green algae swim toward or away from the light source, i.e., display positive or negative phototaxis. Usually, the sign of phototaxis, positive or negative, is variable depending on various factors, but the mechanism that controls it has been unclear. Using Chlamydomonas reinhardtii, an excellent model organism for studying phototaxis, we have recently shown that cellular redox poise plays a key role; cells show positive phototaxis when treated with reactive oxygen species (ROS), whereas they show negative phototaxis when treated with ROS quenching reagents. Here we discuss the possible mechanism of the redox regulation of phototactic sign, questions to be clarified in the future and its possible application.

Keywords: :

• Chlamydomonas
• cilia
• flagella
• green algae
• phototaxis
• redox

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Acknowledgments

We thank Drs Ichiro Terashima and Ko Noguchi (University of Tokyo) for the measurement of photosynthetic activity of Chlamydomonas cells after treatment with the redox reagents and for their helpful discussion and Dr Ritsu Kamiya (University of Tokyo) for his critical reading of the manuscript. This work was supported by a grant from Japan Society for Promotion of Sciences (#22770189) to K.W. and a grant from the Asahi Glass Foundation to K.W.