FIG 4 .
Rapid and transient nuclear accumulation of the transcription factor Gaf1 in response to nitrogen stress. (A) Gaf1 accumulates in the nucleus in response to nitrogen stress. Wild-type cells carrying Gaf1-GFP were grown in minimal medium (EMM) or proline medium (Pro24h) or transferred from EMM to proline-containing medium (Pro1h), low-glucose medium (low G1h), no-nitrogen medium (EMM-N1h), or EMM with rapamycin (EMM+R) for 1 h. (B and C) Time course analysis of the translocation of Gaf1 from the cytoplasm into the nucleus following a shift from minimal to proline media. Wild-type cells carrying Gaf1-GFP were grown to mid-log phase in minimal medium (EMM) and shifted to proline (Pro) for 10 min, 20 min, 30 min, 1 h, 2 h, 4 h, or 6 h. Cells were scored for intracellular Gaf1-GFP localization using criteria described in Materials and Methods. Nuclei were stained with DRAQ5. Cells were visualized by differential interference contrast (DIC) microscopy. Scale bar, 10 µm.