共查询到20条相似文献,搜索用时 15 毫秒
1.
Tatsuomi Matsuoka Yoshiya Watanabe Yasuhiro Sagara Miyuki Takayanagi Yoji Kato 《Photochemistry and photobiology》1995,62(1):190-193
Abstract— In the ciliated protozoan, Blepharisma japonicum, the pink-colored pigment (blepharismin) contained in the pigment granules is believed to be the photoreceptor pigment responsible for the step-up photophobic response. When the cells partially bleached by extrusion of the pigment granules caused by cold shocks were subsequently cultured under illuminated conditions, the pigment-less granules regenerated and the cells were further bleached (pigment content below 0.5%). The photosensitivity of such colorless cells disappeared completely. In contrast, the blepharismin pigment regenerated gradually when such colorless cells were transferred to darkness. The photosensitivity of the cells also recovered with regeneration of the pigment. We found that blepharismin pigment was not photobleached in the absence of O2 . The step-up photophobic response was also completely repressed in the absence of O2 . These results strongly confirm that blepharismin is a photoreceptor pigment mediating photobehavior of Blepharisma and that O2 is required for the early step in the phototransduction of the light-excited pigment. 相似文献
2.
Kotaro T. Yamamoto William O. Smith Jr ‡ Masaki Furuya‡ 《Photochemistry and photobiology》1980,32(2):233-239
The aggregation of phytochrome purified from etiolated pea ( Pisum satirum cv. Alaska) and rye ( Secale cereale cv. Cougar) tissues was investigated by centrifugation and turbidimetry. Purified pea phytochrome (A669 /A280 = 0.88), if irradiated with red light, became precipitable in the presence of CaCl2 . The precipitation upon red-light irradiation was optimal at a Ca2- or Mg2+ concentration of 10–20 m M , was greater at increased phytochrome concentration or lower pH values, and was inhibited by 0.1 M KG. The precipitated phytochrome slowly became soluble after far-red light exposure.
Turbidity of pea phytochrome solutions after red-light irradiation also increased rapidly in the presence of either Ca2+ or Mg2+ . Far-red light exposure after the red light cancelled the turbidity increase. Rye phytochrome showed less turbidity increase than pea phytochrome and occurred only in the presence of Ca2+ . Partially degraded pea phytochrome produced by endogenous proteases in the extract did not show the turbidity increase. Undegraded pea phytochrome also associated with microsomal fractions under conditions similar to those described above, but the partially degraded phytochrome did not. 相似文献
Turbidity of pea phytochrome solutions after red-light irradiation also increased rapidly in the presence of either Ca
3.
Rabi K. Prusti Pill-Soon Song Donat-Peter Häder Maria Häderi 《Photochemistry and photobiology》1984,40(3):369-375
The effects of caffeine, ionophores and calcium flux blockers on the step-up photophobic response, phototactic orientation and the intracellularly recorded, light-induced electrical action potential were studied in the ciliate, Stentor coeruleus . Caffeine alters the absorption and CD spectra and enhances the fluorescence of the photoreceptor pigment, stentorin. Independent of its effects on the spectroscopic properties of the photoreceptor pigment, caffeine shortens the photophobic response time by enhancing the Ca2+ conductivity of membranes, while Ca2+ flux blockers (LaCI3 or ruthenium red) prolong it; both effects cancel each other. Evidence is presented that phototactic orientation is brought about by repetitive photophobic responses, since a change in the phobic response time results in a decreased accuracy of phototaxis. 相似文献
4.
RESONANCE RAMAN SPECTRA OF THE "BLUE" and THE REGENERATED "PURPLE" MEMBRANES OF Halobacterium halobium 总被引:3,自引:0,他引:3
C. Pande R. H. Callender C.-H. Chang T. G. Ebrey 《Photochemistry and photobiology》1985,42(5):549-552
Abstract— We have obtained the resonance Raman spectra of the deionized form of the purple membrane, the so called blue membrane, as well as the purple membrane regenerated by titrating the blue membrane with either Na+, Ca2 + or La3 +. All types of regenerated purple membrane have identical Raman spectra which are virtually indistinguishable from the native light-adapted bacteriorhodopsin spectrum. On the other hand, Raman data for the blue membrane suggest that it consists of essentially two pigment forms with absorption maxima around 605 and 570 nm and containing 13-cis and all-trans isomeric configurations of the chromophore. This is consistent with our chromophore extraction results which reveal that the blue membrane consists of 30% 13-cir and 70% all-trans chromophore. 相似文献
5.
Abstract— White light irradiation of a microsomal fraction from etiolated plants affects their ATP-dependent Ca2+ accumulation by inhibiting active uptake and enhancing passive efflux. The succinate-dependent mitochondrial Ca2 + accumulation as well is decreased by light. The wavelength dependence of these light effects as well as their low quantum yield suggest non-phototransformable protochloro-phyll(ide) [PChl(ide)] to be the photoreceptor. PChlide has been isolated from corn leaves pretreated with 5-amino levulinic acid. Addition of Pchlide causes photosensitization of an otherwise light insensitive microsomal Ca2+ accumulation. The observed light effect may be due to contamination of the mitochondrial as well as the microsomal fractions with PChl(ide)‡ containing particles. Irradiation of the intact tissue leads to the almost complete disappearance of the light effect on the in vitro Ca2 + accumulation. 相似文献
6.
Abstract— Bleached purple membrane normally binds Ca2+ and Mg2+ , which can be removed by the divalent cation chelator ethylenediaminetetraacetic acid (EDTA). Regeneration of pigments from EDTA-treated bleached membrane (apomembrane) and retinal leads to the formation of blue membrane at pH 4.8, and purple membrane at neutral pH. The pigments take much longer to regenerate than with un-deionized apoprotein. Adding back cations to the deionized apomembrane only partially speeds up the regeneration process. Like native purple membrane, the regenerated purple membrane also undergoes a photocycle and shows a light-induced proton release and uptake, although with much slower kinetics than the native species. Thus, cations control the kinetics of pigment regeneration, and also some aspects of the pigment's conformation which controls the photocycle kinetics. The removal and replacement of the cations is not completely reversible, suggesting the cations are not merely bound in the double layer. 相似文献
7.
Radomir Konjevi† Jitendra P. Khurana Kenneth L. Poff† 《Photochemistry and photobiology》1984,39(6):789-792
Abstract
The shape of the fluence-response relationship for the phototropic response of the JK224 strain of Arabidopsis thaliana depends on the fluence rate and wavelength of the actinic light. At low fluence rate (0.1 μmol m-2 s-1 ), the response to 450-nm light is characterized by a single maximum at about 9 μmol m-2 . At higher fluence rate (0.4 μmol m-2 s-1 ), the response shows two maxima, at 4.5 and 9 μmol m-2 . The response to 510-nm light shows a single maximum at 4.5 μmol m-2 . Unilateral preirradiation with high fluence rate (25 μmol m-2 s-1 ) 510-nm light eliminates the maximum at 4.5 μmol m-2 in the fluence response curve to a subsequent unilateral 450-nm irradiation, while the second maximum at 9 μmol m-2 is unaffected. Based on these results, it is concluded that a single photoreceptor pigment has been altered in the JK224 strain of Arabidopsis thaliana. 相似文献
The shape of the fluence-response relationship for the phototropic response of the JK224 strain of Arabidopsis thaliana depends on the fluence rate and wavelength of the actinic light. At low fluence rate (0.1 μmol m
8.
Abstract— Effects of extracellular Ca2+ concentration and papaverine on the PIII response of the electroretinogram and the dark adaptation process of the visual cells were studied in the isolated, aspartate-treated bullfrog retina. The amplitudes of both the fast and slow PIII responses are increased in 0.01 m M Ca2+ solution, but decreased in Ca2+ -free solution containing 1 m M EDTA. The application of 0.1 m M papaverine in the presence of 1 m M Ca2+ led to the enhancement of the slow PIII response at lower stimulus intensity and the prolongation of the slow PIII response, but these effects of papaverine on the response were lost when Ca2+ was removed from the bathing fluid. The half-time of recovery of the fast PIII response amplitude after switching off the adapting light was a linear function of the amount of bleached rhodopsin. Papaverine in the absence of Ca2+ produced about 2-fold increase in the half-time of recovery of the response. These findings suggest that chemical reactions which are sensitive to papaverine in the absence of Ca2+ are implicated in the dark adaptation process of the visual cells. 相似文献
9.
Abstract— Etiolated turions of Spirodela polyrhiza are positively photoblastic and show a phytochrome-mediated low fiuence germination response. The far-red light (FR) reversibility decreased with the delay of FR irradiation (lag phase 1.06 ± 0.03 days after red light irradiation; half-maximal response 1.9 days). The action of the far-red-absorbing form of phytochrome (Pfr) was only realized by a germination response if exogenously applied Ca2 + was present. Calcium step-down (from 1 mM to 0.9 μ M Ca2 +) and Ca2 + step-up (from 0.9 μ M to 1 m M Ca2 +) experiments were carried out to determine the Ca2 +-sensitive phase. There was no time gap between the two phases determined by the step-down and step-up experiments but a clear coincidence of both curves. Pulse treatments (24 h) with Ca2 + (1 m M ) showed the upper part of this common curve to represent the most Ca2 +-sensitive phase. The Ca2 +-sensitive phase was within the Pfr-requiring phase. After reversion of Pfr by FR pulses there was only a negligible response to the high Ca2 +-concentration, independent of the delay between the red light (R) and FR pulses. These results are compatible with the assumption of Ca2 + acting as a second messenger of Pfr. However, the Ca2 +-insensitivity in the first 12 h after the R pulse points against this hypothesis. 相似文献
10.
POLYNOIDIN: A MEMBRANE PHOTOPROTEIN ISOLATED FROM THE BIOLUMINESCENT SYSTEM OF SCALE-WORMS 总被引:1,自引:1,他引:1
Marie-Therese Nicolas Jean-Marie Bassot Osamu Shimomura 《Photochemistry and photobiology》1982,35(2):201-207
Abstract— In order to isolate and purify the luminescence system of scale-worms, the scales were homogenized and extracted in the presence of Triton X-100. After chromatography on Bio-Gel A-5m, Sephadex G-75 and DEAE-cellulose, a single peak in luminescence activity was obtained. It showed properties of a membrane protein having a high mol. wt (about 500000) with characteristics of a photoprotein. The photoprotein, for which we suggest the name polynoidin , emits light in response to several reagents that can produce superoxide or hydroxyl radicals, such as H2 O2 plus Fe2+ , but the luminescence is not triggered by Ca2 + . Oxygen is an absolute requirement for the luminescent reaction. The luminescence has a maximum at 510 nm. The photoprotein is not fluorescent when excited at 350 nm either before or after the luminescent reaction, thus differing distinctly from the green-fluorescent riboflavin in photosomes which is easily separated at the first step of the purification. We suggest a mechanism of the in vivo luminescence of scale worms in which the production of superoxide or hydroxyl radicals by the oxidation of reduced riboflavin could be regulated by Ca2+ . 相似文献
11.
Abstract— The opsin of the visual pigment (P521) of the Tokay gecko rapidly regenerates four spectrally different photopigments with the 9-cis and 11-cis isomers of both the vitamin A,- and A2 -aldehydes. The opsin displays the classic stereospecificity for both A1 - and A2 -series of isomers. The two photopigments regenerated with 9-cis- and ll-cw-3-dehydroretinals respond to chloride and nitrate ions as do the comparable pigments formed with 9-cis- and 11-ris-retinal. The result is a family of pigments absorbing with spectral maxima ranging from 464 to 540 nm, a span of some 3000 cm-1 . The photosensitivity of all four pigments was determined and found to be in relative order: 100% (11-cis-A2 ), 77% (11- cis -A2 ), 36% (9- cis -A,) and 14% (9- cis -A2 ). 相似文献
12.
Javier Catalán Juan C. Del Valle Fernando Fabero Norman A. Garcia 《Photochemistry and photobiology》1995,61(2):118-123
Abstract— The mechanism for photodegradation of the ultraviolet photostabilizer 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (TIN P) upon direct and dye-sensitized (singlet molecular oxygen [O2 (1Δg )]-mediated) irradiation was studied. From the experimental TIN P photodegradation rate data, and low temperature (77 K) fluorescence and phosphorescence quantum yields, one can conclude that the photodegradative process involves phosphorescent states of TIN P. The open conformer of TIN P quenches O2 (1 Δg ) by physical scavenging with a rate constant (kq ) in dimethylsulfoxide of 2.8 times 106 M -1 s-1 . The intramolecular hydrogen-bonded conformer does not appreciably interact with O2 (1 Δg ). In the presence of a relatively high concentration of OH- (either 5 times 10-2 M KOH in ethanol or water at pH 13), the ionic form of TIN P (with an ionized phenol group) physically and chemically quenches O2 (1 Δg ). The reaction rate constant ( k r ) is 1 times 10 8 M -1 s-1 , and the ratio k q / k r is approximately three in alkaline aqueous media. 相似文献
13.
E. Ben-Hur M. Green A. Prager R. Kol I. Rosenthal 《Photochemistry and photobiology》1987,46(5):651-656
Abstract— The concentrations of Na+ , K+ , Ca2+ , Mg2+ and CI− ions in the cytoplasm of octopus photoreceptor cells were determined before and after illumination by electron probe X-ray microanalysis. The concentrations of these elements in the dark-adapted photoreceptor cells were: Na+ , 68.4; K+ , 111.4; Ca2+ , 4.0; Mg2+ , 16.4; and CI− , 102.9 m M /kg of cytoplasm. Illumination raised the concentration of Na+ by 58 m M and that of Cl− by 23 m M and reduced the K+ concentration by 47 m M /kg of cytoplasm. A trace increase of intracellular Ca2+ and a trace decrease of Mg2+ were observed. These results confirm the hypothesis that sodium ions flow in on illumination, and suggest the influx of chloride ions and the outflux of potassium ions during illumination. The intracellular concentrations of Na+ , K+ and Cl+ can give the basis for calculating the ion permeability of ion channels in octopus photoreceptor cell membranes, using values of the membrane potentials obtained by electrophysiological studies 相似文献
14.
Photosensitivity (Kλ ) of a visual pigment is the product of the molecular absorption coefficient (αλ ) and the quantum efficiency for photoconversion (γ). Among the invertebrates, many visual pigments are stable not only in the rhodopsin (R) conformation but also as the photoproduct, metarhodopsin (M), We here employ a method for determining the photosensitivities of the two stable pigments of a rhodopsin-metarhodopsin pair, using kinetic analysis of fluorescence from metarhodopsin combined with measurements of spectral absorption made before and after saturation at the isosbestic wavelength of the pigment pair. A curve fitting technique, in which a theoretical function is scaled for best fit to the measured absorption spectrum of the photosteady-state mixture, yields values for the photosensitivity of rhodopsin at λ.max , the ratio of quantum efficiencies for rhodopsin—metarhodopsin interconversion, and the fractional composition of the steady-state mixture. With knowledge of the molecular extinction coefficient, the absolute values of quantum efficiency can be calculated. For crayfish ( Orconectes, Procambarus ) rhodopsin, measured in isolated rhabdoms, Kmax = 1.05 x 10-16 cm2 at 535 nm with >7λR→M0.69. These values are similar to the photosensitivity and quantum efficiency of bleaching of vertebrate rhodopsins in digitonin solution (Dartnall, 1972). For the metarhodopsin, Kmax = 1.02 x 10-16 cm2 at 510 nm, and λM-R = 0.49. 相似文献
15.
Abstract— The responses of stomata from Paphiopedilum harrisianum , Orchidaceae, to light and CO2 were studied in epidermal peels. Stomatal opening under red light was indistinguishable from that in darkness, whereas blue light promoted opening above dark levels. The ineffectiveness of red light in causing stomatal opening was confirmed in the presence of 100 μ M KCN; average apertures in both darkness and red light were 53% of those measured in the absence of the inhibitor, whereas under blue irradiation, the KCN inhibition was only 30%, with average apertures two-fold of those measured under red light or darkness. Fluence rate response curves under blue light were typical of a single photoreceptor; removal of CO2 increased aperture values without a significant light-CO2 interaction. The lack of a stomatal red light response contrasts with results obtained in species with chlorophyllous stomata in which red light consistently causes stomatal opening, and suggests that the previously reported red light responses in stomata from intact Paphiopedilum leaves resulted from indirect effects, such as depletion of intercellular CO2 by mesophyll photosynthesis. In isolation, Paphiopedilum stomata appear to rely on a blue light photosystem for their responses to light and fail to open under red light because of their lack of guard cell chloroplasts. 相似文献
16.
Marc Dellinger Fernanda Ricchelli Giuliana Moreno Christian Salet 《Photochemistry and photobiology》1994,60(4):368-372
Abstract After 24 h incubation with Photofrinm® (PF), photodynamic action has been studied on Ca2+ transport in CV-1 cells. A moderate increase of the cytosolic free Ca2+ concentration [Ca2+ ] is observed immediately after a dose of irradiation which yields a survival rate of less than 5% at 48 h. In parallel, studies on digitonin-permeabilized cells indicate that such a treatment inhibits endoplasmic reticulum Ca2+ uptake with few alterations of this process in mitochondria. In contrast, ADP-stimulated respiration is impeded and intracellular ATP level decreases. It is suggested that direct damage to endoplasmic reticulum as well as mitochondrial disturbance are the primary mechanisms responsible for a nontransient elevation of [Ca2+] i preceding cell death. 相似文献
17.
Giuliana Valduga Santiago Nonell Elena Reddi Giulio Jori Silvia E. Braslavsky 《Photochemistry and photobiology》1988,48(1):1-5
Abstract— Zn(II)phthalocyanine (ZnPc) generates O2 (1 Δg ) with a quantum yield of ca. 0.4 upon photocxcitation at 354 or 600 nm in ethanolic solution as determined by time-resolved phosphorescence studies at 1270 nm and photooxidation experiments using 1,3-diphenylisobenzofuran (DPBF) as substrate. The quantum yield of photooxidation slightly increases upon incorporation of ZnPc into unilamellar liposomes of dipalmitoylphosphatidylcholine. Under our irradiation conditions (600 nm, 18° C, and short light exposure times), DPBF(5–50 μM) undergoes photooxidation by a pure Type II mechanism; the rate constant for the O2 (1 Δg ) + DPBF reaction is (1.1 ±0.1) x 109 M-1 s_1 in ethanol solution and determined to be about two orders of magnitude smaller when both ZnPc and DPBF are embedded into liposomes. 相似文献
18.
Abstract— The absorption spectra of the membrane-bound and of the digitonin-solubilized visual pigment of crayfish Astacus leptodactylus were investigated by conventional spectrophotometry. A method was developed to isolate purified rhabdoms almost entirely free from screening pigments from a single retina. The quantity of isolated and purified rhabdoms from a single retina was sufficient to measure the absorption spectra of the visual pigment.
The absorption spectra of the chromoprotein system (R and M) show that both the membrane-bound and the digitonin-solubilized visual pigment isomers are stable at 0°C and pH 7.0. Rhodopsin and metarhodopsin are photoreversible under these conditions without any light-induced denaturation. The difference spectra for the chromoprotein isomers and those of different photostationary states yield maximal values for ΔE at 570 and 485 nm.
At neutral pH, 0°C, Λmax of rhodopsin is 530 nm. Irradiation with light of Λ= 630 to 640 nm isomerizes rhodopsin nearly quantitatively to metarhodopsin with Λmax , of 500 nm. The molar extinction coefficient of metarhodopsin is greater than that of rhodopsin by a factor of ˜ 1.41. each measured at its respective Λmax Metarhodopsin can be isomerized to rhodopsin by irradiating at Λ > 630 nm. As the absorption spectra of the two chromoprotein isomers overlap, only part of the metarhodopsin can be reversed to rhodopsin. The maximal photoreversion can be achieved by irradiating at 460 nm. The stability of the digitonin-solubilized chromoprotein is remarkably dependent on temperature. Warming the digitonin extract of rhabdoms from 0 to 20 or 30°C caused a shift of the rhodopsin spectrum to shorter wavelengths (Λmax = 485 nm) accompanied by a decrease of EΛmax by about 30%. 相似文献
The absorption spectra of the chromoprotein system (R and M) show that both the membrane-bound and the digitonin-solubilized visual pigment isomers are stable at 0°C and pH 7.0. Rhodopsin and metarhodopsin are photoreversible under these conditions without any light-induced denaturation. The difference spectra for the chromoprotein isomers and those of different photostationary states yield maximal values for ΔE at 570 and 485 nm.
At neutral pH, 0°C, Λ
19.
Giuliano ColombettiFrancesco LenciPill-Soon Song† 《Photochemistry and photobiology》1982,36(5):609-611
Extracellular K+ ions above a critical concentration induce ciliary reversal in unstimulated Stentor coeruleus and suppress step-up photophobic response. This threshold concentration of K+ ions depends on the extracellular Ca2+ concentration, and the subsequent backward gyration and light-sensitivity suppression seem to depend on the relative concentrations of K+ and Ca2+ . The concentration of Ca2+ necessary to overcome K+ -mediated inhibition of phobic response and backward swimming increases non-linearly with increasing K+ concentration. The Ca2+ -blocking agent. D-600, selectively inhibits photophobic responses of Stentor , thus further confirming the role of Ca2+ ions in photosensory transduction of this ciliate. 相似文献
20.
INDUCTION OF LEAF UNROLLING BY PHYTOCHROME and ACETYLCHOLINE IN ETIOLATED WHEAT SEEDLINGS 总被引:1,自引:0,他引:1
Abstract-Phytochrome regulates the unrolling of primary leaf sections from 8-day-old dark-grown wheat ( Triticum aeslivum L. cv. Arminda) seedlings. Red light (R)-stimulated unrolling of leaf sections pretreated in 1 m M ethylene-bis-(β-aminoethylether)- N,N,N',N' -tetraacetic acid (EGTA) if 1 m M CaCl2 was added during a 30 min treatment period including and following irradiation. Nifedipine at 1 μ M (a Ca2 +-channel antagonist) applied 10 min before R prevented the R stimulation of leaf unrolling. The Ca2 +-channel agonist Bay K-8644 (1 μ M ) and acetylcholine (ACh, 1 mY M ) stimulated unrolling of leaf sections prewashed in EGTA in darkness, if 1 m M CaCl2 was present in the medium during a 30 min treatment period. Acetylcholine also induced leaf unrolling in the absence of Ca2 + when 100 μ M NaCl was present in the medium. Apart from ACh, only carbamylcholine out of the choline derivatives tested was active in induction of leaf unrolling in the presence of 1 m M Ca2 +. The ACh receptor antagonists, atropine (10 μ M ) AND D-tubocurarine (10 μ M ), nullified the ACh-induced Ca2 +- and Na+-dependent leaf unrolling, respectively. Muscarine and nicotine, agonists of ACh, at 1 μ M stimulated leaf unrolling in the presence of Ca2 + and Na+, respectively. The ACh-induced Ca2 +-dependent leaf unrolling was reduced by 1 μ M Nifedipine, 10 μ M Li+ and 10 μ M "calmodulin" inhibitor, trifluoperazine (TFP), whereas only TFP was active in the reduction of the Na+-dependent ACh-induced leaf unrolling response. It is proposed that leaf unrolling of dark-grown primary wheat leaves can be regulated by phytochrome and by activation of two different types of ACh receptors. 相似文献