Photoreceptor electric potential in the phototaxis of the alga Haematococcus pluvialis

Litvin, F. F.; Sineshchekov, Oleg A.; Sineshchekov, V.A.

doi:10.1038/271476a0

Cited by 148 publications

(105 citation statements)

References 15 publications

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“…CHRs are thought to be the photoreceptors that, in vivo, mediate the photoreceptor current I P in the eye of Chlamydomonas and related algae (Litvin et al, 1978;Harz and Hegemann, 1991;Holland et al, 1996;Ehlenbeck et al, 2002). The photoreceptor current triggers phototactic and photophobic responses.…”

Section: Introductionmentioning

confidence: 99%

Channelrhodopsin-1 Initiates Phototaxis and Photophobic Responses inChlamydomonasby Immediate Light-Induced Depolarization

et al. 2008

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Channelrhodopsins (CHR1 and CHR2) are light-gated ion channels acting as sensory photoreceptors in Chlamydomonas reinhardtii. In neuroscience, they are used to trigger action potentials by light in neuronal cells, tissues, or living animals. Here, we demonstrate that Chlamydomonas cells with low CHR2 content exhibit photophobic and phototactic responses that strictly depend on the availability of CHR1. Since CHR1 was described as a H þ -channel, the ion specificity of CHR1 was reinvestigated in Xenopus laevis oocytes. Our experiments show that, in addition to H þ , CHR1 also conducts Na þ , K þ , and Ca 2þ . The kinetic selectivity analysis demonstrates that H þ selectivity is not due to specific translocation but due to selective ion binding. Purified recombinant CHR1 consists of two isoforms with different absorption maxima, CHR1 505 and CHR1 463 , that are in pH-dependent equilibrium. Thus, CHR1 is a photochromic and protochromic sensory photoreceptor that functions as a light-activated cation channel mediating phototactic and photophobic responses via depolarizing currents in a wide range of ionic conditions.

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Section: Introductionmentioning

confidence: 99%

Channelrhodopsin-1 Initiates Phototaxis and Photophobic Responses inChlamydomonasby Immediate Light-Induced Depolarization

et al. 2008

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“…This directional sensitivity of the receptor, in combination with cellular rotation around the longitudinal axis, enables the cell to detect the direction of light by scanning the surrounding light conditions (Foster and Smith, 1980;Schallar and Uhl, 1997;Isogai et al, 2000). Upon light reception, the photoreceptor induces an inward current at the eyespot [photoreceptor current (PRC)] and depolarizes the membrane (Litvin et al, 1978;Harz and Hegemann, 1991). Depolarization then produces a Ca 2+ influx through voltage-dependent Ca 2+ channels on the flagellar membrane, resulting in an increase in the intraflagellar Ca 2+ concentration (Beck and Uhl, 1994;Pazour et al, 1995;Yoshimura et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Phototactic activity inChlamydomonas'non-phototactic' mutants deficient in Ca2+-dependent control of flagellar dominance or in inner-arm dynein

Okita

Isogai

Hirono

et al. 2005

Journal of Cell Science

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In the mechanism underlying the phototactic behavior of Chlamydomonas, Ca2+ has been thought to control the dominance between the two flagella so as to steer the cell to correct directions. A newly isolated mutant, lsp1, that displays weak phototaxis was found to be defective in this Ca2+-dependent shift in flagellar dominance; in demembranated and reactivated cell models, the trans flagellum (the flagellum farthest from the eyespot) beat more strongly than the other (the cis flagellum) in about half of the cells regardless of the Ca2+ concentration between <10-9 M and 10-6 M, a range over which wild-type cell models display switching of flagellar dominance. This is unexpected because ptx1, another mutant that is also deficient in flagellar dominance control, has been reported to lack phototactic ability. We therefore re-examined ptx1 and another reportedly non-phototactic mutant, ida1, which lacks inner arm dynein subspecies f (also called I1). Both were found to retain reduced phototactic abilities. These results indicate that both Ca2+-dependent flagellar dominance control and inner-arm dynein subspecies f are important for phototaxis, but are not absolutely necessary. Analysis of the flagellar beat frequency in lsp1 cell models showed that both of the flagella beat at the frequency of the cis flagellum in wild type. In addition, lsp1 and ptx1 were found to be deficient in determining the sign of phototactic migration. Hence, the Ca2+-dependent flagellar dominance control detected in demembranated cells might be involved in the determination of the sign of phototaxis. The gene responsible for the lsp1 mutation was identified by phenotype rescue experiments and found to have sequences for phosphorylation.

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“…The beat frequency of the two flagella of Chlamydomonas changes transiently during 30CL400 ms after a transition from darkness to continuous light (Ruffer and Nultsch, 1990). The lightinduced change of the transmembrane potential of Huematococcus appears after a step-up stimulus and relaxes in approximately 300 ms (Litvin et al, 1978). These and other typical transient responses are summarized in Table 2.…”

Section: Effector Adaptationmentioning

confidence: 96%

“…In Haematococcus, a close relative of Chlamydomonas, a light step up induces a transient depolarization of the membrane potential (Litvin et al, 1978). The available evidence suggests that the signal transduction leading to flagellar reversal evolves in this sequence; perception by the rhodopsin photoreceptor, membrane depolarization and Ca2+ influx into the cell.…”

Section: The Role Of Calcium and Calmodulinmentioning

confidence: 99%

Photosensory Adaptation in Aneural Organisms*

Galland

1991

Photochem & Photobiology

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Photoreceptor electric potential in the phototaxis of the alga Haematococcus pluvialis

Cited by 148 publications

References 15 publications

Channelrhodopsin-1 Initiates Phototaxis and Photophobic Responses inChlamydomonasby Immediate Light-Induced Depolarization

Channelrhodopsin-1 Initiates Phototaxis and Photophobic Responses inChlamydomonasby Immediate Light-Induced Depolarization

Phototactic activity inChlamydomonas'non-phototactic' mutants deficient in Ca2+-dependent control of flagellar dominance or in inner-arm dynein

Photosensory Adaptation in Aneural Organisms*

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