Extended Data Fig. 1: Transient cell fusion results in ectopic meiosis in the P cell.
From: Gamete fusion triggers bipartite transcription factor assembly to block re-fertilization
a, Box-and-whiskers plot (see Methods) reports the lifetime of the fusion focus visualized by the indicated fluorophores in homothallic wild-type and pak2Δ mating cells. Kruskal–Wallis P value is reported. b, Wild-type control for data presented in Fig. 1b. Time-lapse of homothallic wild-type mating cells expressing GFP–α-tubulin in green and nuclear marker Uch2–mCherry in magenta. Note karyogamy in the outlined mating pair, meiotic spindles (arrows) and spores (arrowhead). c, Micrographs of cells in mating mixtures of homothallic wild-type and pak2Δ strains with lys1 chromosomal loci labelled by LacO:GFP–NLS–LacI system in green and nuclei visualized by Uch2–mCherry in magenta. Arrows point to spores that lack the lys1 locus. d, Wild-type control for data presented in Fig. 1d. Note the formation of the fusion focus (empty arrowhead), labelled by Myo52–GFP in the M cell and Myo52–tdTomato in the P cell, followed by exchange of cytosolic GFP expressed from the P-cell-specific pmap3 promoter and spore formation (full arrowheads). e, Time-lapse showing mating of homothallic pak2Δ cells expressing GFP from the M-cell-specific pmam2 promoter. Note that the GFP exchange is followed by fusion pore closure and build-up of the GFP signal only in the M cells (arrows), whereas P cells form spores (arrowheads). f, P and M cells with indicated genotypes were induced to mate on solid medium. Two days later, we quantified frequencies of phenotypes indicated in the insets of Fig. 1a, n > 200. g, Quantification of sporulation phenotypes of wild-type and pak2Δ diploid cells upon nitrogen starvation, n = 3 experiments with n = 500 cells each. h, Time-lapse showing transient fusion between wild-type P cells and GFP-expressing fus1Δ M cells. Persistent GFP signal difference between partners indicated fusion pore sealing. Note spore formation (arrowhead) only in the wild-type P cell. i, Time-lapse showing mating of h + fus1Δ mutant P cell and GFP-expressing wild-type M cells. Note that transient fusion between indicated partners is followed by resealing of the fusion pore, as visualized by continued accumulation of GFP only in the M cell, and sporulation (arrowheads) in the P cell.
