Design and Performance of the Okazaki Large Spectrograph for Photobiological Research

Elementary Processes of Photoperception by Phytochrome A for High-Irradiance Response of Hypocotyl Elongation in Arabidopsis,

“…Intermittent irradiation with monochromatic light for 1 min with intervals of 2 min of darkness was carried out using the Okazaki large spectrograph (Watanabe et al, 1982). Fluence-response curves in the phyB mutant and the phyAphyB mutant were determined at 20 different wavelengths from 320 to 780 nm at intervals of 10 to 67 nm.…”

“…2), we were able to analyze the relative efficacy of different wavelengths of light for inducing equivalent hypocotyl inhibition responses. The Okazaki large spectrograph and its threshold boxes were designed and built so that monochromatic lights are intermittently exposed in desired fluence rates at wavelengths of 250 to 1,000 nm (Watanabe et al, 1982). Etiolated seedlings with hypocotyls shorter than 2 mm were intermittently irradiated with monochromatic light in 3-min cycles for 24 h, then kept in darkness for 5 d, and their hypocotyl lengths were measured.…”

“…We describe here elementary processes of photoperception by PhyA for inhibition of hypocotyl elongation by cyclical pulse irradiation generated by LEDs, the action spectrum by intermittent irradiation generated by the Okazaki large spectrograph (Watanabe et al, 1982), and the opposite effects of R and FR light pulses on the response. We discuss why PhyA-mediated inhibition of hypocotyl elongation occurs under continuous (and intermittent) irradiation with FR light but not with R light (Nagatani et al, 1993;Parks and Quail, 1993;Whitelam et al, 1993), despite both PhyA (Butler et al, 1959) and PhyB (Abe et al, 1989) showing similar absorption spectra with peaks in the R light region of the spectrum.…”

Action Spectrum for Resetting the Circadian Phototaxis Rhythm in the CW15 Strain of Chlamydomonas

“…In most of the experiments described herein, the bright light pulses were monochromatic light (±2 nm about the specified wavelength), generated by the OLS (24 …”

An Unforeseen Voyage to the World of Phytochromes

“…To avoid failure, Hitachi had built a 1/10 model of our planned spectrograph the first year, and we tested it, finding several points to improve. Then they successfully manufactured the Okazaki large spectrograph (34). Now, anyone can determine action spectra precisely and quickly using computer-controlled threshold sample boxes that were automatically set at chosen wavelengths by a preprogrammed computer-operated carrier and exposed to monochromatic light of chosen photon fluence rate and timing (34).…”