Changes in phx1 + mRNA level during vegetative cell growth and nutrient starved conditions. (A) Expression profile of phx1+ gene during growth. RNA samples from wild type (JH43) cells grown in EMM for different lengths of culture time were analyzed for phx1+ mRNA by Northern blot. The sampling time corresponds to early exponential (EE, at around 12 h), mid-exponential (ME, 20 h), late exponential (LE, 28 h), early stationary (ES, 36 h), and late stationary (LS, 60 h) phases, following inoculation with freshly grown cells to an initial OD600 of 0.02. (B) Induction of phx1+ mRNA by nutrient starvation. Prototrophic wild type cells (972) were grown in EMM to OD600 of 0.5 ~ 1 and then transferred to modified EMM without NH4Cl (EMM-N) or with low (0.5%) glucose, for further incubation. At 3, 6, 9 and 12 h after media change, cells were taken for RNA analysis by qRT-PCR. The amount of phx1+ mRNA was measured by qRT-PCR, along with that of act1+ mRNA as an internal control. Average induction folds from three independent experiments were presented with standard deviations.