Sensitivity of mismatch detection. Slides were printed and fluorescence measured using the standard methods described in Materials and methods. (a) Fluorescence from reporters containing from zero to four mismatches to the target 12 mer (5'-Cy5-GCG TTG GCA CTG). Mismatched bases are in bold. (b) Fluorescence from reporters containing from zero to six mismatches to the target 20 mer (5'-Bodipy-GAC CTC CCG GAC ACG CAC CT). A single mismatch reduces the binding of the 12 mers by 64% and of the 20 mers by 25%. Mismatched positions are in bold.