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. 2016 Mar 22;15(3):553–562. doi: 10.1111/acel.12466

Figure 6.

Figure 6

Rif1 protects telomere‐free chromosome ends. (A) Association of Rif1‐HA, expressed from the ADH1 promoter, with the margins of a DSB in strains with a JKM139 background, expressing the HO‐nuclease from a galactose‐induced promoter (Lee et al., 1998). Strains were grown overnight on raffinose; galactose was added at time 0 and samples collected every second hour. Galactose induces GAL‐HO‐nuclease to cut at the MATa locus. Because the donor locus is missing, repair by recombination is prevented (Lee et al., 1998). The numbers on the X‐axis indicate the distance from the DSB. The legend indicates the time (h) in galactose. (B) The fraction of cells that adapted, e.g. escaped from arrest by producing at least another large bud/cell. JKM139 and derivates from overnight raffinose cultures were incubated on galactose at 30 °C, to induce a DSB. ADH1‐RIF1 (i) and (ii) are independent strains with RIF1 under the ADH1 promoter. After 4 h, large‐budded cells were separated by sonication, transferred to galactose plates and incubated at 30 °C. Cells were examined every second hour by microscopy. (C) As in B, except that the fraction of micro‐colonies formed after 24 h on galactose plates is presented. The micro‐colonies consist of the following number of cells and buds: 2 (grey columns), 3–4 (white) and 5–10 (black). (D) Cartoon explaining the effect of Rif1 in cells with a chromosome break.