Dark variant

Mutatox test (Johnson, 1991 Microbics, 1995). The Mutatox test is based on the use of a dark variant of the luminescent bacterium Vibrio fischeri. This bacterium is a well known organism used for evaluation of acute toxic effects... 

Principle/Procedure Genotoxic effects of aqueous soil extracts are measured. The strain is a dark variant of the luminescent bacteria and poorly emits light during growth cycles. In the presence of genotoxic materials, light production is restored. 

The mutagenic activity of chemical substances can be assessed by means of the Ames test [109]. In analogy to this test which is based on the reversion of certain changes in the phenotype of mutants caused by the mutagen, one can use the reversion of a dark variant of Photobacterium leiognathi to the luminous one by mutagens, such as mitomycin C. This can be detected in nanogram amounts [110]. 

Figure 1 A stepwise view of the Verlet integration algorithm and its variants, (a) The basic Verlet method, (b) Leap-frog integration, (c) Velocity Verlet integration. At each algorithm dark and light gray cells indicate the initial and calculating variables, respectively. The numbers in the cells represent the orders m the calculation procedures. The arrows point from the data that are used in the calculation of the variable that is being calculated at each step.

The variant was found In a 22 year old woman with chronic hemolytic anemia characterized by a persistent retlculocytosls, development of gallstones requiring cholecystectomy, frequent episodes of jaundice, dark urine, and falling PCV value. Her mother, maternal grandfather, and sister have a similar clinical picture In all patients red cell enzymes are elevated with a retlculocytosls of about 10%, and 2,3-DPG levels are normal ... 

Nifosi R, Ferrari A, Arcangeli C, Tozzini V, Pellegrini V, Beltram F (2003) Photoreversible dark state in a tristable green fluorescent protein variant. J Phys Chem B 107 1679-1684... 

Method A A solution of 0.5 mmol of (2/ /S ,3R/S )-2,3-dialkyl-1,4-diarylbutane and 0.125 mL (1.0 mmol) of boron trifluoride-diethyl ether complex in 2 mL of trifluoroacctic acid is added to a suspension of 0.12 g (0.26 mmol) of thallium(III) oxide in 2 mL of trifluoroacetic acid at — 40°C to +25CC under an argon atmosphere. The dark colored solution is stirred until the reaction is complete, diluted with ethyl acetate, then washed successively with water (twice) and sat. aq NaCl. Evaporation of the dried extract gives the crude product. In a variant of this method the boron trifluoride-diethyl ether complex can be omitted. 

The intrinsically low intensity of Raman scattering strongly influences both the sensitivity and penetration depth of SORS and its variants. Dominant noise components (photon shot noise or thermal/dark count [1]) can be minimised relative to signal by increasing absolute signal levels. In many Raman systems, collection optics, laser power and other relevant parameters are usually maximised for optimum performance of the system current detectors (CCD devices), for example, have detection efficiencies approaching 100%. Typically, acquisition time provides the only straightforward means available... 

The flowers of Lupinus succulentus are predominantly dark blue. Rarely, variants occur which are light blue, pink, or entirely white flowered. These are all conditioned by recessive alleles, viz., dd for light blue, pp for pink, and bb for white. All three dominant genes, D, P, and B, are required for the expression of the dark blue color. The presence or absence of a band of dark pigmentation across the seed coat, Figure 1, was found to segregate in most populations the recessive ss is bandless. 

Eschenmoser [15] has recently alluded to the concepts of structure-directed synthesis and autochthonous reactivity — the propensity of certain systems to undergo reactions as a consequence of their intrinsic molecular structural factors — within the context of certain biomolecules, particularly the organic cofactor, vitamin B12. The formation of the AD ring junction in the corrin ligand had to be regarded as a major hurdle in any proposed chemical synthesis of cobyric acid (5) (Fig. 2), and hence of vitamin B12. However, driven initially by the desire to identify a dark, and therefore potentially biomimetic, variant of the photochemical... 

The X-ray scattering profiles of T6, T15, and T23 were measured under continuous illumination. Due to the long lifetime of the M intermediate for the truncated form, we can expect that more than 90% of the protein is in the PYPm state under continuous illumination [41]. Figure 7.3 shows the intensity profiles of the M intermediates of the truncated PYP variants compared with those obtained for their dark states. Significant differences between the two states were observed for each truncated PYP. The profiles of the PYPm intermediates of the three truncated PYP variants are similar with two broad peaks... 

Fig. 3.18. Generation of large binary-patterned libraries ofAroQ chorismate mutase genes. (A) A two-stage strategy was adopted involving separate randomization and selection of functional variants ofthe HI (light gray) and H2/H3 helices (dark gray), followed by combination of functional binary-patterned segments from the initial libraries and reselection. In the final constructs, 80 % of the protein was randomized. (B) The...

Nickel Trifluoride Syntheses. As a dry solid, NiFa decomposed to produce a dark brown (nearly black) material which gave an X-ray powder diffraction pattern which showed it to have a rhombohedral variant of the pyrochlore structure (see below and Table 1) ... 

Fig. 5 Bright-field and dark-field imaging (A) BF image of lamellar y/ 2 titanium aluminide (B) corresponding SAD pattern (see Fig. 4) (C) and (D) DF images of the reflections marked in (B). Each of these reflections is characteristic for one twin variant of tetragonal y-TiAl appearing with high intensity in the corresponding DF image. (View this art in color at www.dekker.com.)...

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