Proportion of phytochrome in the Pfr form after saturating irradiation by red light is only about 85%. 

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#Id: 9851

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Both phytochromes and cryptochromes entrain the circadian clock in Arabidopsis.

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Blue light depolarizes membrane of hypocotyl cells and inhibits of growth rate.

This membrane depolarization is caused by the activation of anion channels, which facilitates the efflux of anions such as chloride.

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an anion channel blocker, NPPB (5-nitro-2-[4-phenylbutylamino]- benzoate), prevents the blue light–dependent membrane depolarization and decreases the inhibitory effect of blue light on hypocotyl elongation.

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Phototropins (phots) are involved in directing organ, chloroplast, and nuclear movements, solar tracking, and stomatal opening

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In Mougeotia, the photoreceptors regulating chloroplast movement consist of a fusion between phytochrome and a phototropin known as neochrome, and show typical bilin binding as well as red/far-red reversibility.

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#Id: 9856

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Mougeotia appears to have evolved the ability to exploit red light as a signal to induce a response (chloroplast movement) that is typically mediated by blue light.