Colourimetric genetic screening by visual inspection. The Eppendorf tubes contain, from left to right: (A) dye only; (B) dye, PNA and wild-type DNA; (C) dye, PNA and 2MU DNA; (D) dye, PNA and 1MU DNA; (E) dye, PNA and ΔF508. Row 1 was taken after adding the dye to the hybridised samples and before the final heating. The rest of the rows (2–5) were all taken after the final heating to ∼95°C during cooling to room temperature. The rows of samples are taken in sequence with the last being row 5, i.e. the temperature decreases towards the bottom. The time elapsed after taking the samples out of the ∼95°C water bath until all of the DNA–PNA samples had turned purple was ∼1 min.