Self-transformation generates merodiploids.

<p>(A) Increased survival of lethal transformants after transformation with <i>codY</i>::<i>trim</i> (grey bars) or <i>codY</i>::<i>spc</i> (black bars) cassettes in presence of chromosomal DNA from R800 or D39. (B) Maps of <i>codY+</i> and <i>codY</i>::<i>trim</i> loci, and detection of <i>codY</i>- (red, scodY1-scodY2 primers) and <i>trim</i>-specific (blue, strim1/strim2 primers) sequences by PCR in Trim^R clones recovered from transformation with either <i>codY</i>::<i>trim</i> PCR alone (#1–10), or <i>codY</i>::<i>trim</i> PCR in presence of R800 chromosomal DNA (#11–20). (C) Detection of TD junction by PCR with CJ242/merod-b primers in clones #1–5 and #11–15 from <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003819#pgen-1003819-g003" target="_blank">Figure 3B</a>. 9/10 of these clones possessed the TD junction. The one clone without the TD junction (clone #1, R3022) was found to possess an additive insertion of the <i>codY</i>::<i>trim</i> cassette in close proximity to the <i>codY</i> locus, creating a very small TD (See <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003819#pgen.1003819.s004" target="_blank">Figure S4B</a>–E). (D) PFGE analysis of chromosomal DNA from clone #11 (R3023), digested by <i>Sma</i>I and hybridized with <i>codY</i>-specific probe. Open red arrow, expected wild-type <i>codY</i> ethidium bromide stained band; closed red arrowhead, R3023 <i>codY</i> fragment, expected for <i>codY</i>⁺/<i>codY</i>::<i>trim</i> merodiploid; open red arrowhead, wild-type <i>codY</i> band weakly present in R3023. Although the lanes shown were part of the same initial gel/membrane, lanes present between them have been removed to simplify comparison between lanes. (E) Representation of the R_2/1 hybrid at the TD junction in R3023 identified by sequencing, layout as in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003819#pgen-1003819-g002" target="_blank">Figure 2B</a>.