Strains and cultures
Yeast strains are shown on table 1. Strains BR450 and NI150 are spontaneous ura3 - mutants of the respective type strains obtained by plating strains on 5-FOA medium (Synthetic Complete Medium lacking uracil, see below, to which is added a small quantity of uracil; 50mg/L, and 5-fluoro-orotic acid, 1g/L). These alleles of ura3 were sequenced by Eurofin GenomicsTM France. In C. bracarensis , the ura3 gene, CABR0s13e0133 has a deletion encompassing nt 240-657 with respect to the first nucleotide (nt) of the start codon, and in C. nivariensis , the ura3 gene,CANI0s15e01067 has a deletion encompassing nt 488-610 with respect to the first nt of the start codon. (Gene names from http://www-archbac.u-psud.fr/genomes/nakaseomycetes/nakaseomycetes.html).
Yeast strains are grown in broth or on plates at 30°C, in YPD (non-selective, 1 % Yeast Extract, 1 % Peptone, 2 % glucose), in Synthetic Complete medium lacking uracil, methionine, and cysteine (induction conditions for the MET3 promoter, SC-Ind, 1.67 % Yeast Nitrogen Base without amino acids, 0.5 % ammonium sulfate, 2 % glucose, supplemented with adenine and all amino acids except methionine and cysteine), and SC-Ind supplemented with 2 mM each of methionine and cysteine (repression conditions for the MET3 promoter, SC-Rep). For growth of cells without the plasmid as controls in the induction experiments, 2 mM uracil is added to the SC-Ind and to the SC-Rep medium. When repression, but no selection is needed, cells are grown in YPD supplemented with 2 mM each of methionine and cysteine (YPD-Rep). For Synthetic Complete media, pH is brought to 5.8 by addition of drops of 5M NaOH until correct pH is reached.