Dark adaptation and

Mueller-Limmroth, W. and B. Schmidt (1961b). The human ERG after glare in the course of early dark adaptation and its modification by adaptinol (German). Med. Welt 27 1413-1421. 

Lamb, TD and Pugh, EN, 2004. Dark adaptation and the retinoid cycle of vision. Prog Retin Eye Res 23, 307-380. 

Mata, NL, Tzekov, RT, Liu, XR, Weng, J, Birch, DG, and Travis, GH, 2001. Delayed, dark-adaptation and lipofuscin accumulation in abcr+/- mice Implications for involvement of ABCR in age-related macular degeneration. Invest Ophthalmol Vis Sci 42, 1685-1690. 

In addition to the classical symptoms of zinc deficiency mentioned above, the following unusual conditions have been reported liver and spleen enlargement, abnormal dark adaptation and abnormalities of taste. Several laboratory procedures for diagnosing zinc deficiency are available. Measurement of zinc levels in plasma is useful in certain cases. Levels of zinc in the red cells and hair may be used for assessment of body zinc status. More accurate and useful parameters are neutrophil zinc determination and quantitative assay of alkaline phosphatase activity in neutrophils. Determination of zinc in 24 h urine may help diagnose deficiency if sickle cell disease, chronic renal disease and liver cirrhosis are ruled out. A metabolic balance study may clearly distinguish zinc-deficient subjects. 

The effect of light on CD spectra at various solvent compositions, for a polymer containing 85 mol% spiropyran units, is shown in Figure 11. When methanol concentration is below 5%, both the dark-adapted and the irradiated samples show the typical CD pattern of disordered polypeptides. In HFP/MeOH = 90/10, the sample kept inthedark is random coil, whereas the sample exposed to light displays the standard CD pattern of the a-helix. The intensity of the bands indicates that under these conditions light causes the full conversion from random coil to 100% a-helix. With increasing methanol con-... 

Phosphorylation is a necessary, but not sufficient, condition for quenching metarhodopsin II it also has to bind the protein arrestin before it loses the bound retinaldehyde and is converted to metarhodopsin III. Then, it is de-phosphorylated by protein phosphatase 2A and a calcium-activated protein phosphatase. It is this dephosphorylation of metarhodopsin III that is correlated with dark adaptation and regeneration of active rhodopsin by binding to... 

Nakaishi, H., Matsumoto, H., Tominaga, S., and Hirayama, M., Effects of black current anthocyanoside intake on dark adaptation and VDT work-induced transient refractive alteration in healthy humans, (erratum appears in Alternative Med. Rev., 6, 60, 2001), Alternative Med. Rev., 5, 553-562, 2000. 

The multiline spectrum shows some resemblance to that of a mixed valence cluster Mn - Mn or Mn - Mn [88,89,97] and with a computer simulation of a tetramer spectrum such as 3Mn - Mn [90]. Precise agreement, however, is lacking so far. The form and number of the lines depend on the period of dark adaptation and the illumination temperature and are sensitive to the presence of inhibitors of O2 evolution [91,92]. The signal is orientation-dependent, i.e. it has a fixed geometry with respect to the membrane [93]. 

The precise mechanism whereby digoxin produces a toxic effect may involve inhibition of Na K -activated adenosine triphosphatase, an enzyme that plays a vital role in maintaining normal cone receptor function.This would explain the drug-induced interference with both dark adaptation and color vision. 

Impairment of dark adaptation with or without excessive glare sensitivity has been reported with isotretinoin therapy in doses of 1 mgAg of body weight daily.These complaints may be associated with an abnormal ERG or abnormal EOG. Once therapy is discontinued, both the abnormal dark adaptation and abnormal ERG usually resolve within several months. 

A range of radionuclides was chosen including pure beta emitters, beta/gamma emitters and electron capture radionuclides. These radionuclides were used to prepare single nuclide sets of calibration standards with a matrix typical of that routinely encountered (Table 1). The quench level was varied by altering the ratio of aqueous fraction to cocktail whilst maintaining the total volume of liquid in the vial. The set of calibration standards were dark-adapted and then counted to determine the measurement efficiency over a range of quench levels. 

Fig. 2. EPR spectra (measured at 13 K) of the subchloroplast particle TSF-I dark-adapted and frozen in the dark (top spectrum) and the same sample subsequently illuminated at 13 K. Unpublished results of B Ke and H Beinert (1972).

The possible effects of specific cysteine replacement was monitored by EPR spectroscopy, as shown in Fig. 8 (A), where panels (a) and (b) show the EPR spectra of the dark-adapted and illuminated states, respectively, of the reconstituted complex containing the mutant, PsaC Cys-14->Asp protein. The protocol for the preparation of the sample is described at the top of the figure. The reconstituted complex [P700-Ao Ai-FeS-X]-FeS-A/B-PsaD PsaE where the secondary electron acceptors were present in the oxidized state was prepared by freezing the sample in the dark. The EPR spectrum was then measured [spectrum (a)] and once again for the same sample under illumination [spectmm (b)], both at 15 K. 

B.W. Bailey, et al., (2003). Constraints on the conformation of the cytoplasmic face of dark-adapted and light-excited rhodopsin inferred from antirhodopsin antibody imprints. Protein Sci. 12, 2453-2475. 

Figure 1. Qb binding site of different bRC. The structures were superimposed with the Kabsch algorithm (12) considering all displayed molecular components except the two quinones and residue L2I0. The Qb of the dark-adapted and light-exposed crystal structures from Rb. sphaeroides (10) are displayed in black and white, respectively. Qb from Rps. viridis (3, 4) is depicted in gray. Residues common to all three structures, are taken from the light-exposed structure ofRb. sphaeroides. Further residues from Rps. viridis are depicted in gray and denoted in brackets. (Drawn with Molscript (61).)...

In previous studies, we investigated different ET, protein-protein association and cofactor binding reactions of photosynthetic proteins using various theoretical methods 13-21). Here, we focus on the ET process from Qa to Qb in the dark-adapted and light-exposed bRC from Rb. sphaeroides. It was found that the rate of this ET reaction diminished by several orders of magnitude (22) if the bRC from Rb. sphaeroides was frozen in the dark-... 

The reduction of Qb is coupled to a conformational rearrangement. The crystal structures of the dark-adapted and the light-exposed RC from Rb. sphaeroides were solved and the conformational changes were characterized structurally (16). In the two structures, the Qb was found in two different positions, proximal or distal to the non-haem iron. Because Qb was found mainly in the distal position in the dark and only in the proximal position under illumination, the two positions have been attributed mostly to the oxidized and... 

We need about 5000 observers to obtain a satisfactory average, both for the dark-adapted and the light-adapted hiunan eye. Note that we can compare any color In terms of red -i- green -i- blue to a monochromatic color. 

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