Mutant frequency, measurement

Mutant frequency is the number of spi plaques out of the tottil number of rescued plaques measured in E. coli XLI Blue host bacteria not carrying the P2 phage DNA. 

A central question concerning the use of a particular locus to measure chemically induced mutation is whether that particular locus is representative of other loci. The ability of the lymphoblast line HH-4, a WI-L2 subclone, to form colonies in the absence of a feeder layer enabled us to isolate clonal lines that are heterozygous for TK and to develop a mutation assay based on loss of TK. We have also been able to develop an assay based on ouabain (OU) resistance. We have now begun to compare induced mutant frequencies at the tk, hgprt, and Na /K ATPase loci. 

The vibrational frequency of the special pair P and the bacteriochlorophyll monomer B have also been extracted from the analysis of the Raman profiles [39,40,42,44,51]. Small s group has extensively performed hole-burning (HB) measurements on mutant and chemically altered RCs of Rb. Sphaeroides [44,45,48-50]. Their results have revealed low-frequency modes that make important contribution to optical features such as the bandwidth of absorption line-shape, as well as to the rate constant of the ET of the RCs. 

The bacterial and mammalian cell assays for gene mutation were developed to measure statistically significant increases in the numbers of mutant colonies derived from rare events many millions of exposed cells must be plated out to allow the assessment of mutation frequency. The Salmonella typhimurium reverse mutation assay ( Ames test) is carried out in a variety of different mutant strains selected to identify the various classes of mutation. The test generates many hundreds of Petri dishes for counting and is not practical for profiling. 

Fig. 6.5. Numerical simulation of quantum beats measurements of DLL mutant RCs of Rb. capsulatus with 80 fsec pump pulse. Two vibrational frequencies are included in the simulation. The box with broken line indicates the time region in which the phase evolution of the vibrational quantum beams can be seen clearly.

Fig. 2.1. Selection of advantageous variants. The individual curves show selection and fixation of mutants in populations of N = 10000 individuals according to the equation x(t) = x0/ xo + (1 — xo)exp(—st). Time t is measured in generations or replication steps, x0 is the initial frequency of the new variant in the population, and s =f -f is its selective advantage. The curves shown above use initial conditions of a single copy in the population, x = 0.0001.

Fig. 10. ESEEM spectra for TID and T2D Fet3p. The upper spectrum of the type 2 Cu(II) site (TID mutant) was collected at 2690 G with t = 260 ns. The lower spectrum of the type 1 Cu(II) site (T2D mutant) was collected at 2825 G with t = 250 ns. The measurement conditions were as follows microwave frequency, 8.80 GHz microwave power, 43 dB sample temperature, 4.2 K. The sample was 0.5 mM Fet3p in MES buffer, pH 6.0, containing 25% ethylene glycol (Aznar et al., 2002).

Boxer s group [2] first made a ns-laser photolysis apparatus with a super-conducting magnet. The sample was excited at 532 or 600 nm with a frequency-doubled YAG pumped dye laser (8ns, fwhm) and was probed at 860 nm with a laser diode. The maximum field of their magnet was 5 T. With this apparatus, they measured the quantum yield of triplet states (detected optically in quinone-depleted photosynthetic reaction centers (RCs) from R. spheroids, R-26 mutant, as a function of applied magnetic strength and temperature. The reaction scheme for qinone-depleted RCs is shown in Fig. 12.1. Here, the singlet and triplet radical-ion pair (RIP) are represented by [D" A ] and [D A ], respectively, and the rate constants of the S-T conversion of RIP, the recombination from [D A ], and the recombination from [D A ] are denoted by hsT, ks, and kj, respectively. 

Still another advantage is the small number of chromosomes, namely, four pairs, three of which, the sex chromosomes and the two major pairs of autosomes, contain most of the known genetic loci. This advantage is exploited in tests which measure the frequency with which a chromosome has one or more lethal or visible mutants obviously, in this case the more genes in such a chromosome the more efficient and economical the test. 

DNA single-strand break frequency was measured by alkaline elution [16] and sister chromatid exchanges (SCEs) were assayed by the method described by Wolff [32]. Hypoxanthine-guanine phosphoribosyl transferase (HPRT 6-thioguanine) and Na/K ATPase (ouabain) resistant mutants of CHO were determined by the methods described by Cleaver [7]. Repair replication after MMS treatment was measured in isopycnic gradients [8]. 

Fig. 5. The regulatory gene, araC. The gene is divided into six sections by the deletions. The numbers above the small vertical line represent the site of C mutants ordered by three-factor reciprocal crosses and are placed at relative distances from one another based on recombination frequencies. (C/0/ to CI9 = 3.65 recombination units.) Other C mutant sites ordered by three-factor reciprocal crosses but without distance measurements are indicated only by a number (42,49,57). The order of several of the C mutant sites was confirmed by mapping with the deletion mutants indicated. mutants C 1-I0, C 60-67) isolated as resistant to o-fucose inhibition were mapped by recombination frequency. The position of mutant site C67, C 2, C4, and C 70 as being within the C gene was verified by deletion mapping. mutants (100 and over) isolated from a dK strain were ordered by deletion mapping. The star represents a nonsense mutation.

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