The [<i>SWI</i>⁺] prion encourages diverse mating partners.

Abstract

<p>(A) A diagram showing the mating tendencies of [<i>SWI</i>⁺] and [<i>swi</i>^<i>−</i>] haploids (budding yellow cell). Left: A [<i>swi</i>^<i>−</i>] cell will readily switch its mating type after dividing and mate with its own daughter. The resulting diploid cannot out-cross with diverse mating partners (orange cell). Right: In the [<i>SWI</i>⁺] pioneering state, mating-type switching is inhibited, and thus mother cells cannot mate with their own daughters. This increases the likelihood that they will mate with genetically diverse partners. Note that after normal mating-type switching, an additional generation may occur before mating, after which the four haploids involved can mate in pairs (not depicted). (B) Relative out-crossing efficiencies of [<i>swi</i>^<i>−</i>] cells (blue) and [<i>SWI</i>⁺] cells (red). Elimination of the prion from the [<i>SWI</i>⁺] strain (“cured”) returns its out-cross ratio to the low state. The ratio was calculated by normalizing to the mating efficiency of <i>ho</i>^<i>−</i> control cells (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.2003476#pbio.2003476.s002" target="_blank">S2A Fig</a>). Error bars indicate standard deviation (<i>n</i> = 3). Numerical data and the flow cytometry gating strategy are available from the Dryad Digital Repository: <a href="https://doi.org/10.5061/dryad.d5r16" target="_blank">http://dx.doi.org/10.5061/dryad.d5r16</a>.</p