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Masakatsu Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Action Spectrum of Light Pulse-Induced Membrane Depolarization in Pulvinar Motor Cells of Phaseolus
2016Co-Authors: Yuichiro Nishizaki, Mamoru Kubota, Kimiko Yamamiya, Masakatsu WatanabeAbstract:In addition to circadian changes in the membrane potential and leaf movement, light applied to the pulvinus causes changes in both the membrane potential and the pulvinar movement in Phaseolus vulgar is L. Even after a short pulse of light, a transient depolarization of the mem-brane occurs and leaf movement is observed. Decreases of turgor pressure of the motor cells are always preceded by the depolarization. The direction of the leaf movement can be explained by the decrease of turgor pressure in the motor cells on the irradiated side of the pulvinus. Using the Okazaki Large Spectrograph at the National Institute for Basic Biology, we determined the Action spec-trum of the membrane depolarization induced by light pulses (30 s) in motor cells of Phaseolus. The pulvinus was left exposed to air during measurement of the membrane potential with microelectrodes. The Action Spectrum obtain-ed was in the range of 300 to 730 nm. It had the highest peak at 460 nm with lower peaks at 380 nm and 420 nm. Almost no sensitivity was observed at wavelengths shorter than 360 nm and longer than 520 nm. Red and far-red light had no effect on the depolarization of the motor cell. The features of the Action Spectrum are almost the same as those of the Blue-Type response in plants
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Action Spectrum for the suppression of arylalkylamine n acetyltransferase activity in the two spotted spider mite tetranychus urticae
Photochemistry and Photobiology, 2009Co-Authors: Takeshi Suzuki, Masakatsu Watanabe, Norimitsu Izawa, Takuya Takashima, Makio TakedaAbstract:An Action Spectrum was obtained for the suppression of arylalkylamine N-acetyltransferase (NAT) activity in the two-spotted spider mite Tetranychus urticae by irradiating the mite with monochromatic lights of various wavelengths using the Okazaki Large Spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence–response curves were obtained for wavelengths between 300 and 650 nm by irradiating the mite for 4 h day−1. The samples were frozen after the third exposure. A negative correlation between the logarithmic fluence rate and NAT activity was detected in the range of 0.01–1 μmol m−2 s−1 for wavelengths between 300 and 500 nm and in the range of 0.1–10 μmol m−2 s−1 for wavelengths between 550 and 650 nm. The constructed Action Spectrum indicated that the photoreceptors mediating the circadian and/or photoperiodic systems might be UV-A- and blue-type photoreceptors with absorption peaks at 350 and 450 nm.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 micromol m(-2) s(-1) photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20-30 micromol m(-2) s(-1), whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 micromol m(-2) s(-1), probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed Action Spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV-A-type photoreceptor with absorption peaks at 320, 340 and 400 nm.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:Abstract To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 μmol m−2 s−1 photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20–30 μmol m−2 s−1, whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 μmol m−2 s−1, probably due to an inhibition of photosynthetic a...
Christian Wiencke - One of the best experts on this subject based on the ideXlab platform.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 micromol m(-2) s(-1) photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20-30 micromol m(-2) s(-1), whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 micromol m(-2) s(-1), probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed Action Spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV-A-type photoreceptor with absorption peaks at 320, 340 and 400 nm.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:Abstract To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 μmol m−2 s−1 photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20–30 μmol m−2 s−1, whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 μmol m−2 s−1, probably due to an inhibition of photosynthetic a...
Gudrun Krabs - One of the best experts on this subject based on the ideXlab platform.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 micromol m(-2) s(-1) photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20-30 micromol m(-2) s(-1), whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 micromol m(-2) s(-1), probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed Action Spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV-A-type photoreceptor with absorption peaks at 320, 340 and 400 nm.
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a monochromatic Action Spectrum for the photoinduction of the uv absorbing mycosporine like amino acid shinorine in the red alga chondrus crispus
Photochemistry and Photobiology, 2004Co-Authors: Gudrun Krabs, Masakatsu Watanabe, Christian WienckeAbstract:Abstract To determine the Action Spectrum for photoinduction of the ultraviolet (UV)-absorbing mycosporine-like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 μmol m−2 s−1 photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20–30 μmol m−2 s−1, whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 μmol m−2 s−1, probably due to an inhibition of photosynthetic a...
Eduardo Zeiger - One of the best experts on this subject based on the ideXlab platform.
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close correspondence between the Action spectra for the blue light responses of the guard cell and coleoptile chloroplasts and the spectra for blue light dependent stomatal opening and coleoptile phototropism
Proceedings of the National Academy of Sciences of the United States of America, 1996Co-Authors: Miguel A Quinones, Eduardo ZeigerAbstract:Fluorescence spectroscopy was used to characterize blue light responses from chloroplasts of adaxial guard cells from Pima cotton (Gossypium barbadense) and coleoptile tips from corn (Zea mays). The chloroplast response to blue light was quantified by measurements of the blue light-induced enhancement of a red light-stimulated quenching of chlorophyll a fluorescence. In adaxial (upper) guard cells, low fluence rates of blue light applied under saturating fluence rates of red light enhanced the red light-stimulated fluorescence quenching by up to 50%. In contrast, added blue light did not alter the red light-stimulated quenching from abaxial (lower) guard cells. This response pattern paralleled the blue light sensitivity of stomatal opening in the two leaf surfaces. An Action Spectrum for the blue light-induced enhancement of the red light-stimulated quenching showed a major peak at 450 nm and two minor peaks at 420 and 470 nm. This Spectrum matched closely an Action Spectrum for blue light-stimulated stomatal opening. Coleoptile chloroplasts also showed an enhancement by blue light of red light-stimulated quenching. The Action Spectrum of this response, showing a major peak at 450 nm, a minor peak at 470 nm, and a shoulder at 430 nm, closely matched an Action Spectrum for blue light-stimulated coleoptile phototropism. Both Action spectra match the absorption Spectrum of zeaxanthin, a chloroplastic carotenoid recently implicated in blue light photoreception of both guard cells and coleoptiles. The remarkable similarity between the Action spectra for the blue light responses of guard cells and coleoptile chloroplasts and the spectra for blue light-stimulated stomatal opening and phototropism, coupled to the recently reported evidence on a role of zeaxanthin in blue light photoreception, indicates that the guard cell and coleoptile chloroplasts specialize in sensory transduction.
Mitchio Okumura - One of the best experts on this subject based on the ideXlab platform.
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role of oh stretch torsion coupling and quantum yield effects in the first oh overtone Spectrum of cis cis hoono
Journal of Chemical Physics, 2005Co-Authors: Anne B Mccoy, Andrew K Mollner, Joseph S Francisco, Mitchio OkumuraAbstract:A joint theoretical and experimental investigation is undertaken to study the effects of OH-stretch/HOON torsion coupling and of quantum yield on the previously reported first overtone Action Spectrum of cis-cis HOONO (peroxynitrous acid). The minimum energy path along the HOON dihedral angle is computed at the coupled cluster singles and doubles with perturbative triples level with correlation consistent polarized quadruple zeta basis set, at the structure optimized using the triple zeta basis set (CCSD(T)/cc-pVQZ//CCSD(T)/cc-pVTZ). The two-dimensional ab initio potential energy and dipole moment surfaces for cis-cis HOONO are calculated as functions of the HOON torsion and OH bond length about the minimum energy path at the CCSD(T)/cc-pVTZ and QCISD/AUG-cc-pVTZ (QCISD—quadratic configuration interAction with single and double excitation and AUG-augmented with diffuse functions) level of theory/basis, respectively. The OH-stretch vibration depends strongly on the torsional angle, and the torsional potential possesses a broad shelf at ~90°, the cis-perp conformation. The calculated electronic energies and dipoles are fit to simple functional forms and absorption spectra in the region of the OH fundamental and first overtone are calculated from these surfaces. While the experimental and calculated spectra of the OH fundamental band are in good agreement, significant differences in the intensity patterns are observed between the calculated absorption Spectrum and the measured Action Spectrum in the 2nuOH region. These differences are attributed to the fact that several of the experimentally accessible states do not have sufficient energy to dissociate to OH+NO2 and therefore are not detectable in an Action Spectrum. Scaling of the intensities of transitions to these states, assuming D0=82.0 kJ/mol, is shown to produce a Spectrum that is in good agreement with the measured Action Spectrum. Based on this agreement, we assign two of the features in the Spectrum to Delta n=0 transitions (where n is the HOON torsion quantum number) that are blue shifted relative to the origin band, while the large peak near 7000 cm^–1 is assigned to a series of Delta n=+1 transitions, with predominant contributions from torsionally excited states with substantial cis-perp character. The direct absorption Spectrum of cis-cis HOONO (6300–6850 cm^–1) is recorded by cavity ringdown spectroscopy in a discharge flow cell. A single band of HOONO is observed at 6370 cm^–1 and is assigned as the origin of the first OH overtone of cis-cis HOONO. These results imply that the origin band is suppressed by over an order of magnitude in the Action Spectrum, due to a reduced quantum yield. The striking differences between absorption and Action spectra are correctly predicted by the calculations.
