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. Author manuscript; available in PMC: 2017 Oct 26.
Published in final edited form as: Cell Rep. 2017 Sep 5;20(10):2490–2500. doi: 10.1016/j.celrep.2017.08.051

Fig. 1. Overview of screening method.

Fig. 1

(A) Diagram of selectable ADE2 and URA3 cassettes. The ADE2 marker contains a short artificial intron with only 63 (GAA) repeats, while the URA3 marker contains a longer artificial intron with 100 (GAA) repeats. (B) Screening procedure: Cells are mutagenized and grown on complete (YPD) media. Colonies form, and those that turn red (ADE2 inactivation) are spread on sections of a plate containing the selective drug 5FOA. For each strain with a high number of 5FOA-resistant colonies (URA3 inactivation), four individual 5FOA colonies were tested via PCR for repeat length. C. Example PCRs for amplification of (GAA)n repeats in both cassettes. The URA3 (GAA)100 repeat consistently expands in strains containing genuine repeat expansion trans-modifiers (right), while remaining at wild-type length in strains containing off-target modifiers (left). The ADE2 (GAA)63 repeat does not appear to expand in any strains.