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Linear/exponential amplification

Subkhankulova T, Livesey FJ. Comparative evaluation of linear and exponential amplification techniques for expression profiling at the single-cell level. Genome Biol 2006 7 R18. [Pg.16]

Taq Pol can also be employed as an auxilliary enzyme which just fulfills the need to prepare ample amounts of template DNA (either ssDNA or dsDNA). Single-stranded DNA templates can be readily generated by a nonstandard PCR strategy known as asymmetric PCR. Compared with symmetric PCR, which in essence corresponds to the standard PCR, the asymmetric PCR employs one of the two primers about 100-fold more than the other primer such that, after a certain number of exponential amplification which exhausts the limiting primers, linear amplification of ssDNA is attained. [Pg.421]

A comparison of the covalent connectivity associated with each of these architecture classes (Figure 1.7) reveals that the number of covalent bonds formed per step for linear and branched topology is a multiple (n = degree of polymerization) related to the monomer/initiator ratios. In contrast, ideal dendritic (Class IV) propagation involves the formation of an exponential number of covalent bonds per reaction step (also termed G = generation), as well as amplification of both mass (i.e. number of branch cells/G) and terminal groups, (Z) per generation (G). [Pg.13]

These designs avoid the possible stress developed in stepped horns. The amplification factor for either a linear or an exponential horn is the ratio of the end diameters (not areas as with stepped). The linear taper is the easier design to manufacture but its potential magnification is normally restricted to a factor of approx. 4-fold. The exponential taper offers higher magnification factors than the linear taper. Its shape makes it more difficult to manufacture but the small diameter of the working end and its length make it particularly suited to micro applications. [Pg.282]

If two PGR primers include elements that cannot be replicated, an exponential expansion is reduced to arithmetic accumulation. However, if multiple nested sets of internal primers (also nonreplicable) are included, product accumulation (at least in theory) can approach that of PCR. This process is known as linked linear amplification. It requires a polymerase, several sets of nested primer pairs, and thermal cycling similar to PCR. ... [Pg.1418]

Chemiluminescence from S- or P-containing compounds is obtained by combustion in a hydrogen-rich flame. Both the excited HPO radicals formed and the Sj dimers can emit a chemiluminescence spectrum which allows the selective detection of S (eg, at 394 nm) and P (526 nm) using suitable filters and a photomultiplier tube for signal amplification [26]. This flame photometric detector shows a non-linear realtionship between concentration and output signal in the sulfur mode which in theory should be quadratic (owing to the dimer formation). However, in practive, exponential coefficients of between 1 and 2 are found. Electronic linearization of the output signal is therefore necessary. [Pg.138]

The real-time PCR fluorescence curve generated by the sequence detection system is composed of four distinct phases. When PCR product and reporter signal accumulate beyond background fluorescence levels, the reaction enters the exponential detection phase. At this point the amplification plot crosses a user-defined detection threshold which is set above the background fluorescence noise, preferable at the beginning of the exponential phase. The fractional cycle number at which the reaction crosses the threshold (C ) is related inversely to the initial template DNA concentration. As PCR products continues to accumulate, the ratio of Taq DNA polymerase to amplified products decreases, resulting in nonexponential accumulation of amplicons. At this point the reaction enters the linear phase. Once PCR product ceases to accumulate due to assay depletion, AR values remain relatively constant and the reaction enters the plateau phase. [Pg.61]

PCR there is no direct relation of DNA input to amplified target hence classical RT-PCR assays have to be stopped at least in linear phase. The exponential range of amplification has to be determined for each transcript empirically by amplifying equivalent amounts of cDNA over various cycles of the PCR or by amplifying dilutions of cDNA over the same number of PCR cycles. [Pg.3471]

At the outset of standard PCR conditions, primers and dNTPs are 10 and 10 ° times, respectively, in excess over the template, while Taq Pol is in the lowest molar excess of 10. After a 10 -fold amplification of target, enzymes become totally occupied and the primer to template ratio decreases, promoting self-annealing of the strands. Eventually the reaction begins to saturate the exponential rate of accumulation is attenuated to a linear rate at a product concentration near 10 nM (1 pmol in the standard reaction) and finally reaches a plateau at —100 nM (43). Whether the efficiency decreases rapidly or slowly depends on several variables (a) initial concentrations and respective balance of dNTPs and/or prim-... [Pg.414]

In the exponential phase, the number of DNA copies increases exponentially under ideal reaction conditions. As the reaction cycles continue to increase, reagents are used and the efficiency of template amplification decreases. Amplification fails to occur in an exponential way, and the PCR enters into the plateau stage. Since it is the C, value that will be used for analyses, log-linear and plateau data serve as little more than confirmation that the amplification process proceeded in a standard way. [Pg.1015]


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Exponential amplification

Linear amplification

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