Fig. 1

Agarose gel showing results for each of the three groups of (individual) genomic DNA samples produced by nested PCR of regions of the small (SSU) and large (LSU) subunits of the nuclear ribosomal RNA genes. Group 1: Well-defined ‘positive’ samples containing DNA of particular Cryptosporidium taxa, with no ‘cross-amplification’. Group 2: Representative samples with substantial cross-amplification but no evidence of the presence of Cryptosporidium. Group 3: Representative ‘negative’ samples with no cross-amplification or evidence of the presence of Cryptosporidium DNA (cf. Methods section). The marker is a 100 bp ladder, plus a 1500 bp band (top). No-template controls were included in primary and secondary PCR runs (negative controls 1 and 2, respectively). For full description of samples and methods, see Methods section