Telomere Addition Site mapping by LM-PCR. 2A. LM-PCR strategy, described in the Materials and Methods, and in Results. The native 5'P at the end of the MAC DNA telomere is indicated in red, and the telomere G4T4 repeats are indicated in green. Short, thick arrows indicate primers. Ligation to the 3'OH of the anchor linker is indicated by an inverted caret; anchor primer 7A is indicated by hollow arrows. The asterisk at the end of the display primer indicates its 5' 32P label. 2B. Autoradiogram of electrophoresis gel displaying end-labeled display products derived from a multi-TAS region. TAS positions are determined as described in the text, by running the display chains (central lane) next to the lanes of sequencing reactions derived from the MIC DNA that is processed. Four display bands and corresponding TAS positions on the MIC DNA sequence lanes are marked with black diamonds. This early CR-R result has not been further analyzed: analysed results are shown in Figures 3 and 4. Sequencing lanes derived from a cloned P1-anchor PCR product are run on the other side of the central display lane. This clone carries a product with telomere repeats added to its dot-marked dT, represented by the second-slowest, marked display band. Along side these lanes are diagrammed the extent of the 7A anchor primer, ligated to the 5'P of the telomere G4T4 repeats.