Figure 4

MMQPCR and TRF analyses of genomic DNA samples digested with Bal 31.

(a) Evolution of the relative T/S ratio during a Bal 31 time course digestion. Arabidopsis wild type bulk genomic DNA samples were digested with Bal 31 during different periods of time and analyzed by MMQPCR. The ratios of telomeric versus CYP5 amplification products (T/S) were determined following the standard curve method. Two different MMQPCR reactions, rendering two different T/S ratios, were performed for each incubation time with Bal 31. A graphic representation of relative T/S ratio versus Bal 31 incubation time is shown together with a regression line. Relative T/S ratios represent the percentage of T/S ratio remaining after each Bal 31 incubation time. (b) TRF analyses of the Bal 31 digested DNA samples. The same samples used to perform the MMQPCR amplifications were analyzed by Southern blot hybridization with a telomeric probe after digestion with the restriction enzyme Tru9I. The migration distances of molecular size markers are indicated in the left. The contrast of the image has been adjusted to better detect the limits of the hybridization signals corresponding to 40 and 60 minutes as they are very faint due to their high level of spreading. Therefore, the intensities of the hybridization signals do not reflect DNA amounts. Note that the lower limit of the hybridization signal at 40 minutes is around 1.6 Kbp whereas the lower limit at 60 minutes is ill-defined.