ago1 and dcr1 mutants are defective for G1 arrest and mating after nitrogen limitation. (A) FACS analyses of log phase (+Nitrogen) and nitrogen starved (-Nitrogen) TV294, Δago1 (TV292), Δdcr1 (TV293), and Δrdp1 (TV296) cultures. Insets at the right show the morphologies of yeast cells under nitrogen-deficient conditions. (B and C) Mating mixtures were incubated at 30°C for 18-30 h on malt extract plates and scored for zygote production microscopically. (B) Mating frequencies of TV294, Δago1 (TV292), Δdcr1 (TV293), and Δrdp1 (TV296) crossed with FY261 (parental type) or JC261K (Δago1). The low level of self-mating in strains FY261 and JC261K presumably occurs due to mating type switching. (C) Mating frequencies for homothallic wild-type (h90) or homothallic ago1 null (h90Δago1) strains under nitrogen-deficient or low glucose/low nitrogen condition. (D) 4,6-diamidino-2-phenylindole-stained and corresponding differential interference contrast (DIC) images of TV294, Δago1, Δdcr1, and Δrdp1 strains cultured under normal growth (unstarved), nitrogen starvation (-Nit.) and low glucose/low nitrogen (LowGluc./LowNit.) conditions. Average cell lengths for each strain (unstarved condition) are shown at the bottoms of the DIC panels.