Primer sequences and PCR details.¹

1An initial denaturation step (95°C for 15 mins – hot start PCR, or 94°C for 1 min); DNA amplification (initially 40 cycles, with 25 cycles in nested reactions) of strand separation at 94°C for 40 sec, 1 min of primer annealing, followed by strand extension at 72°C for 20 sec plus 1 sec/cycle; and a final extension step at 72°C, were used for all PCR amplifications. 2The DRa primer was biotinylated at the 5′ end to enable subsequent detection of amplified DNA by reverse hybridization.