Adaptation light

Phosducin regulates light adaptation in retinal rods... 

FIGURE 10.25 The photocycle of light-adapted halorhodopsin (liR), shown in the presence and absence of chloride. The superscripts indicate the maxima of the difference spectra between IrR and the intermediates. 

Fox DA, Katz LM. 1992. Developmental lead exposure selectively alters the scotopic ERG component of dark and light adaptation and increases rod calcium content. Vision Res 32 249-255. 

Sineshchekov, O. A., V. D. Trivedi et al. (2005). Photochromicity of Anabaena sensory rhodopsin, an atypical microbial receptor with a cw-retinal light-adapted form. J. Biol. Chem. 280(15) 14663-14668. 

A17 Retina inner nuclear layer Light adaptation -... 

Figure 4. Radiation pattern emitted from orbiting electrons when the velocities are much smaller than (A) or comparable to (B) the speed of light. (Adapted from Ref. 20.)...

The time constant b in light adaptation after a small step-up was found to be... 

Dose-dependent increase in swimming speed in light-adapted larvae 30... 

Figure 12.18 Schematic representation of a linear motor powered by light Adapted from V. Balzani, A. Credi and M. Venturi, Light-powered molecular-scale machines , Pure and Applied Chemistry Volume 75, No. 5,541-547 International Union of Pure and Applied Chemistry IUPAC 2003...

Fig. 2.34. Sample chromatogram of light-adapted Z. marina leaf sample. Peak identification 1 = neoxanthin, 2 = violaxanthin, 3 = antheraxanthin, 4 = lutein, 5 = zeaxanthin 6 = chlorophyll b, 1 = chlorophyll a, 8 = / -carotene. Reprinted with permisson from P. J. Ralph et al. [76].

Our work aims at identifying, by subpicosecond broadband transient absorption and gain spectroscopy, the primary photochemical steps of the phototransduction process in Blepharisma japonicum, more specifically in the light-adapted form of the organism (blue cell) for which the photoactive pigment is oxyblepharismin [5] (see Scheme 1) and the associated macromolecule is a large non-soluble protein (200 kDa) [6]. 

Red-cell (dark adapted) Blepharisma japonicum were cultured in Pisa, in the dark, at 23 °C, in the presence of the Enterobacter aerogenes bacterium as food supply [7]. Blue-cell (light adapted) Blepharisma japonicum were produced by in vivo photoconversion of blepharismin into oxyblepharismin under a low intensity cold white lamp (below 10 W/m2). Blue cells were washed, collected by low speed centrifugation and resuspended in a 20-mM sodium cholate solution. The chromoprotein was obtained by FPLC chromatography of this preparation, on a hydroxyapatite column. The applied eluent was a phosphate buffer (pH 7.4), first 0.05 M and then 0.2 M. This ionic strength step affects the affinity of the biomolecules with the hydroxyapatite [8]. 

Figure 8. Fluorescence decay of Pr phytochrome (124 kDa) excitation at Aexc = 640 nm, emission measured at Aero — 680 nm. The semilogarithmic plots of the measured decay (curve with signal noise) and the decay function calculated from best-fit kinetics parameters obtained by single-decay analysis (thin line superimposed on measured decay) are shown. In the inset the calculated lifetimes xf 3 and relative amplitudes Rf 3 of the decay components are given. On top, a weighted residuals plot (sigma) indicates the deviations of these computer-fitted parameters from the measured decay, with the value of the squared reduced error (y2) in the inset. The fluorescence decay of the red-light adapted Pr + Pfr mixture exhibited a comparable triexponential behaviour. (After Figure 4 in Holzwarth et al. [76].)...

The steady-state UV (protein) fluorescence spectra of Pr and of the red-light adapted Pr + Pfr mixture (Figure 11) reveal no significant difference at Aexc = 295 nm, a wavelength which preferentially excites Trp and minimizes the excitation of tyrosine residues. 

Figure 11. Corrected stationary UV (protein) fluorescence spectra of 124-kDa P, phytochrome and of the red-light adapted mixture Pr + Pfr at 275 K A c = 295 nm (Holzwarth et al. [108]).

Figure 12. UV (protein) fluorescence decay of the red-light adapted mixture P, + Pfr (124kDa) at 275 K Aelc = 295 nm, = 330 nm. Inset calculated lifetimes t(t,P)i -4 and relative amplitudes Rftrp)1 -4 °f the decay components calculated by single-decay analysis. Top weighted residuals plot and autocorrelation function of the residuals. The fluorescence decay of pure Pr exhibited a comparable tetraexponential behaviour (Holzwarth et al. [108]).

TABLE 2 Lifetimes and Approximate Maxima of Time-Resolved UV (Protein) Fluorescence Spectra of 124-kDa Pr Phytochrome from Oat and of the Red-Light Adapted Pr + Pfr Mixture at 275 K [78, 108 ... 

Real pigment differences among leaf or other plant tissues of different light adaptation or developmental stages, and among fruit tissue... 

Loss of visual acuity, reduced color vision, and altered light adaptation developed in a 42-year-old woman 2 weeks after she started to take a high protein diet and melatonin 1 mg/day (17). She had also been taking sertraline for the past 4 years. Her vision improved within 2 months of stopping the melatonin and the high protein diet. 

Pugh, E.N., Jr., Nikonov, S., and Lamb, T.D. (1999). Molecular mechanisms of vertebrate photoreceptor light adaptation. Curr. Opin. Neurobiol. 9 410-418. 

Fig. 3. Zinc oxide powder particle of 10 5 cm diameter, (a) Dark adapted, (b) light adapted (adapted from Ruppel, Gerritsen and Rose 461)...

Fig. 19.14 Time course of the concentration of oxalic and oxamic acids during the degradation of 157 mg dm-3 paracetamol solutions in 0.05 M Na2S04 + H2SO4 of pH 3.0 at 300 mA and at 35°C using a Pt/02 cell with the following catalysts (open square) 1 mM Cu2+, (filled square) 1 mM Cu2 + UVA light, (open triangle) 1 mM Fc2+, (filled triangle) 1 mM Fe2+ + UVA light, (open diamond) 1 mM Fe2+ + 1 mM Cu2 1, and (filled diamond) 1 mM Fe2+ + ImM Cu2 1 + UVA light [adapted from Sires et al. (2006)]...

Neale, P.J. and Melis, A. 1986. Algal photosynthetic membrane complexes and the pho-tosynthesis-irradiance curve a comparison of light-adaptation responses in Chlamydomonas reinhardtii (Chlorophytaj. J. Phycol. 22, 531-538. 

The ground state of bacteriorhodopsin, also called the initial, light-adapted, BR, or resting state, refers to the protein with a relatively... 

Figure 2. Absorption spectra of retinal isomers and rhodopsins. [Retinal spectra (in hexane at room temperature) are reproduced from refs. 52, 168, and 174.] The spectra of rhodopsin and iso-rhodopsin (A > 350 nm) are for digitonin-solubilized preparations in aqueous glycerol mixtures at 4°K (ref. 287), and room temperature (A < 350 nm. ref. 6). (Those of light-adapted (BrML) and dark-adapted (BRjjgg) bacteriorhodopsin, both for aqueous7membrane suspensions at room temperature, are reproduced from refs. 259 and 377.

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