Table 1.
Nitrogen source does not affect frequency of [URE3]
| Strain | Nitrogen source | Carbon source | [URE3]/106 cells |
|---|---|---|---|
| 3385 | Proline | Galactose | 1,000 |
| Ammonia | Galactose | 1,200 | |
| Proline | Dextrose | 13 | |
| Ammonia | Dextrose | 9 | |
| 3469 | Proline | Galactose | 48 |
| Ammonia | Galactose | 176 | |
| Proline | Dextrose | 2 | |
| Ammonia | Dextrose | 2 |
Strain 3385 (MATa kar1 ura2 leu2 his- [ure-o]) and strain 3469 (MATa/MATα kar1/kar1 ura2/ura2 leu2/leu2 trp1/+ +/his-) were transformed with p644 (YEp351G-URE2) carrying URE2 under control of the GAL1 promoter (8). Transformants were grown on the indicated media for 2 days. Yeast nitrogen base without amino acids (YNB) (ammonia nitrogen source) or YNB without ammonia +2 mg/ml l-proline contained either 2% dextrose or 2% galactose + 2% raffinose. After growth, cells were suspended and plated on dextrose-ammonia with USA in place of uracil to measure [URE3] clones.