Fig. 1.

Repeat type, structure of progenitor MSY1 array, and junction primer strategy for mapping mutants. In the middle is shown a schematic structure of the donor allele, with repeat units indicated by circles and sequences given in the key. Arrows indicate primers. Below and above are shown electropherograms showing, respectively the results of typing the 1, 3 and 3, 4 repeat unit boundaries, using primer combinations Y1A⁺/JUN-1, 3 and Y1B⁺/JUN-3, 4. Junction primers are fluorescently labelled (‘F’). RFU: relative fluorescent units. The junction primers are directed at the boundaries, but also yield PCR products corresponding to other local repeats through mispriming. The putative hairpin adopted by a type 4 repeat is also shown.