Strains were grown in synthetic complete medium containing 0.7% (wt/vol) yeast nitrogen base (BD Difco) and 2% (wt/vol) α-d-glucose (Sigma) at 30°C. Cells were washed three to five times and starved in nitrogen starvation medium with 0.17% (wt/vol) yeast nitrogen base without amino acids and ammonium sulfate (BD Difco) and 2% (wt/vol) α-d-glucose buffered at pH 6.2 using 50 mM MES-KOH as described in Suzuki et al. (2011) (link), supplemented with the nucleobases adenine, guanine, cytosine, and thymidine at a final concentration of 0.4 mM each or NAC (Sigma) at a final concentration of 10 mM when indicated.
To analyze respiratory competence, cells were plated onto YPD plates containing 1% (wt/vol) yeast extract (Serva), 2% (wt/vol) bacto-peptone (Merck), and 2% (wt/vol) α-d-glucose, and colony color was assessed and quantified. Because all strains contained the ade2 mutation, on YPD, white and sectored colonies were classified as respiratory deficient and red colonies were classified as respiratory competent.