Figure 2.

The cig1Δ cig2Δ puc1Δ mutant arrest in G1 after a single round of cell division in nitrogen-free medium. Wild-type and cig1Δ cig2Δ puc1Δ mutant cells grown at 25°C in minimal medium were centrifuged, washed four times in minimal medium without nitrogen, and resuspended in minimal medium without nitrogen at 25°C. Samples were taken for FACS analysis and protein and RNA preparation at the indicated times. (A) Flow cytometry analysis of h⁹⁰ wild type and h⁹⁰ cig1Δ cig2Δ puc1Δ mutants after nitrogen starvation at 25°C. (B) DAPI and calcofluor staining of cells before (t = 0h) and 4 h after (t = 4h) nitrogen starvation. Arrowheads show cells undergoing conjugation. (C) Rum1 protein and mRNA levels. Anti-tubulin antibodies and 18S rRNA were used as protein- and RNA-loading controls.