Electrophoretic analysis of the OCS products. Concatamers obtained using primer set 2 (Table 1) are indicated by arrows. (A) The PCR products (1–3 nM) were combined and subjected to 15, 20, 25, 30, 35 and 40 thermal cyclings (lanes 1–6) in the presence of 0.2 µM each terminal primer. (B) AmpliTaq (lanes 1–4), Pfu (lanes 5–8) and KOD-plus (lanes 9–12) DNA polymerases were used in both the amplification and catenation steps. The concatenation reaction proceeded for 35 cycles using 6.4 nM (lanes 1, 5 and 9), 3.2 nM (lanes 2, 6 and 10), 1.6 nM (lanes 3, 7 and 11) and 0.8 nM (lanes 4, 8 and 12) amplification products. M, 100 bp ladder size marker.