Rotor-Gene Q MDx CE User Manual 02/2022
106
6.6.6
Comparative quantitation
Comparative quantitation compares the relative expression of samples to a control sample in a run
when a standard curve is not available. This is frequently used in microarray analysis. Warton and
coworkers (2004)* provide an example of this technique.
1.
To perform the analysis, select
Other
and then
Comparative quantitation
in the
Analysis
window. Double-click on the channel to analyze.
2.
Choose a control sample using the drop-down menu on the right-hand side of the screen
below the toggler.
3.
The results are automatically calculated and displayed in the
Comparative Quantitation Results
window below the graph.
The first columns of the
Comparative Quantitation Results
window show the sample number and
name. The
Takeoff
column gives the takeoff point of the sample. The second derivative of the
amplification plot produces peaks corresponding to the maximum rate of fluorescence increase in
the reaction. The takeoff point is defined as the cycle at which the second derivative is at 20% of
the maximum level, and indicates the end of the noise and the transition to the exponential phase.
This graph shows a second derivative of an amplification plot, showing the relative positions of the
second derivative peak and the takeoff point.
* Warton, K., Foster, N.C., Gold, W.A., and Stanley, K.K. (2004) A novel gene family induced by acute inflammation in
endothelial cells. Gene
342
, 85.