Variation in 3DPCR Taq polymerase background mutation rate across the PCR block. (A) White spots correspond to PCR-positive samples for a 176 bp fragment of human TP53. Those samples indicated by an asterisk were cloned and sequenced. (B) Mutation matrices for A10- and D8-derived sequences; transitions were invariably of the type N->T,A; the number of bases sequenced is given by n. (C) Distribution of the number of CG->TA transitions per clone. (D) A collection of the most highly mutated sequences. To compact the data, only variable sites are shown, their positions being identified above. Nucleotide positions should be read from top to bottom. To the right are the numbers of mutations per clone (mut) and the minimum number of recombination events (rec) to explain the complexity. Zones of recombination are highlighted in grey shading when possible. (E) 5′ Dinucleotide context for the G->A and C->T transitions, with the expected values shown as horizontal bars.