In each strain, the vast majority (on typical 86.three ) of your SNP positions remained heterozygous as in the parental strain. Having said that, a substantial fraction (on typical 13.7 ) of SNP positions are homozygous for either parental origin (Fig two, S4 Table), demonstrating that the RTG strains are recombined. Remarkably, the total quantity of polymorphisms exhibiting LOH varies from 15.two to 27.8 among the RTG strains, demonstrating that the RTG course of action generates a high degree of genetic diversity.Mother and daughter RTG pairs exhibit complementary genotypesNext, we analyzed the segregation at all SNP positions inside the 15 pairs of mother-daughter RTG strains. Because the RTG strains remained diploid, the genotyping of RTG pairs gives tetradlike information regarding the segregation pattern with the 4 chromatids derived from of a single meiotic cell that underwent RTG. On average, we observed that for 98.six in the SNPPLOS Genetics | DOI:ten.1371/journal.pgen.February 1,6 /Recombination upon Reversion of MeiosisFig 2. Genome-wide genotype in the six RTG strains obtained upon arginine prototroph choice. The relative frequency on the 3 genotypes (homozygous S288c in red, homozygous SK1 in blue and heterozygous S288c/SK1 in grey) is indicated within the legend boxes. doi:10.1371/journal.pgen.1005781.gpositions, the genetic data segregated two:two in mother and daughter RTG pairs. Among them, 89.two carry a heterozygous genotype in each mother-daughter cells, as the parent diploid. Conversely, ten.eight from the SNP positions segregating as two:2 carry a homozygous genotype with opposite parental alleles in the mother and daughter cells (S8 Fig and S4 Table). This is exemplified in Fig 3 in which the genotype of your mother strain (RTG11-M) includes 16.three of homozygous SNP positions, with 10.three from S288c and six from SK1, while the genotype of the daughter strain (RTG11-D), contains 16.two of homozygous SNP positions, but using the reverse percentage of parental alleles: five.7 S288c and ten.3 SK1. The homozygous SNP positions exhibiting a two:2 segregation pattern, grouped as tracts with reciprocal genotypes, correspond to LOH events resulting from reciprocal exchanges among non-sister chromatids. As a result, the meiotic cell that exits from meiosis (i.e. the mother cell) inherits two non-sister chromatids and the bud (i.e. the daughter cell) inherits the other two non-sister chromatids, as expected from a profitable re-entry into mitosis inside the absence of DNA replication. The nonsister chromatids are frequently but not normally recombined. As observed for the chosen RTG strains (Technique 1, see Fig 1), the absolute frequency of acquired homozygosity is extremely diverse from one RTG pair to a different. In this dataset of 15 RTG pairs, we observed 136 reciprocal LOH tracts (rLOH) (S5 and S6 Tables), using a wide variation, from 1 to 34 tracts per RTG pair.PLOS Genetics | DOI:ten.1371/journal.pgen.February 1,7 /Recombination upon Reversion of MeiosisFig 3. Genotype evaluation of the mother and daughter RTG strains. (A) Genotype of the RTG11-M and Title Loaded From File RTG11-D cells. (B) For comparison, the genotype in the RTG11-M and RTG11-D chromosomes are shown on leading of one another, revealing that they have complementary LOH regions. The zoom-ins of distinct varieties of event is shown around the ideal.