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| Bolige, Aoen; Goto, Ken. |
| Little is known about the photoreceptors involved in the photoperiodism of unicellular organisms, which we elucidated by deriving their action spectra. The flagellated alga Euglena gracilis exhibits photoperiodism, with a long-day response in cell reproduction. The underlying clock is a circadian rhythm with photoinductive capability, peaking at subjective dusk and occurring at the 26th hour in continuous darkness (DD) when transferred from continuous light (LL); it regulates photoinduction, a high-irradiance response (HIR), of a dark-capability of progressing through cell division. We derived the action spectra by irradiating E. gracilis with monochromatic light for 3 h at around the 26th hour; the action maxima occurred at 380, 450–460, 480, 610, 640,... |
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Palavras-chave: Cell division cycle; Complementary chromatic adaptation; Circadian; Euglena; End-of-day; Photoperiodism; Phytochrome; Shade avoidance. |
| Ano: 2007 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/719 |
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| Bolige, Aoen; Goto, Ken. |
| Irradiance spectra change spatiotemporally, and angiosperms adapt accordingly, mainly through phytochromes. This study challenges the long-held belief that the flagellated alga Euglena gracilis lacks phytochromes and is therefore unaffected by spectral changes. We photoautotrophically cultured the alga under continuous light (LL), then transferred it to darkness. After about 26 h in darkness, different irradiations for 3 h enabled cell division in dark-arrested G2 cells evoking a high-irradiance response (HIR). The spectral characteristics of the irradiation during the LL period (pre-irradiation) defined the spectral sensitivity in the subsequent dark period. LL with light rich in the red spectrum led to a HIR to the red spectrum (R-HIR), whereas light... |
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Palavras-chave: Cell division; Circadian rhythms; End-of-day; Euglena; Photoperiodism; Phytochrome; Shade avoidance. |
| Ano: 2007 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/720 |
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