Fig. 1
From: An epigenetically inherited UV hyper-resistance phenotype in Saccharomyces cerevisiae
UV exposure induces hyper-resistance to subsequent UV exposure (UVHR). Quantitative UV double-exposure survival assays were done on log-phase yeast cultures (strain BY4741) using a Philips 30 W G30T8 UV lamp at 254 nm. Cultures were serially diluted and plated in duplicate on YEPD agar, exposed to UV, and then incubated in the dark for ~ 6 days. Colonies were counted and used to calculate relative survival frequencies. Assays were done a minimum of three times, with mean ± 1 SE reported for each condition (*p < 0.01). A. Yeast cells were exposed to two sequential rounds of UV radiation, first on suspended cells at 50 J/m2 (+ UV), along with a mock-exposed control (−UV), followed by a 1 h incubation at 30 °C, and then plating and UV exposure to varying secondary dosages (as indicated on the X axis). B. Same as A, except with varying initial exposure dosages (25, 50, and 100 J/m2, respectively). *, statistically significant differences found at the indicated UV secondary dosages (p < 0.01 for all pairwise comparisons, with the following exceptions: at 50 J/m2, only + UV50 versus + UV100 and −UV versus + UV100 differences are significant; for all other comparisons, p > 0.05; at 100 J/m2, −UV versus + UV25, p > 0.05; at 150 and 200 J/m2, −UV versus + UV100, p = 0.03; at 200 J/m2, + UV25 versus + UV50 and + UV100, p > 0.05). C. Same as A, except with a 4 h incubation period. D. Same as A, except with varying incubation times, as indicated on X axis. The graph displays fold difference in survival (+ UV relative to −UV) based on secondary exposure survival at 200 J/m2. Values for 1- and 4-h incubation assays are derived from a and c. Values for the 7-, 10-, 16-, and 22-h incubations are derived from assays reported in Additional file 1: Figure S1