Chapter 13 - Sensory Photoreceptors and Light Control of Flagellar Activity

Abstract

This chapter broadly covers the sensory photoreceptors and light control of flagellar activity wherein behavioral light responses, light signaling elements, rhodopsins as photoreceptors and blue light sensitive flavin-based photoreceptors are elaborated. Chlamydomonas displays distinct behavioral responses to light. The most basic responses are directional changes of swimming upon absorption of single photons. The first part defines the behavioral light responses and introduces the strains. It also includes various methods of studying the behavioral light responses. The rhodopsins absorb red photons of the intensive monitoring light with significant efficiency. In bright-field microscopy, the eyespot is seen peripherally near the cell's equator as a conspicuous, single orange-red spot. The study of sensory photoreceptors in Chlamydomonas is especially appealing because the reactions can be triggered both in vivo and in vitro with unparalleled precision. Seven rhodopsins, two cryptochromes, and one phototropin have been identified as sensory photoreceptors in Chlamydomonas.