Fig. 3

DNA synthesis and selective nucleotide incorporation opposite urea (Ua) by DNA polymerase δ (panels A and B) and DNA polymerase ε (panel C). DNA polymerase δ (154 ng) and DNA polymerase ε (50 μU) ware incubated with templates containing G (lanes 1–5) or Ua (lanes 6–10) and 100 μM of each of the four dNTPs (lanes 5 and 10) or 100 μM of a single dNTP (N = C, G, A, or T) (lanes 1–4 and 6–9). Lane M contained no enzyme and are negative controls. The background darkness of panel A has been adjusted in panel B, and only the part of the gel around the 30-mer full length products is shown