No. of double-crossover tetrads involving | ||||
---|---|---|---|---|

Relevant genotype | Two strands | Three strands | Four strands | P-value |

Wild type | 138 | 287 | 114 | 0.11 |

mms4Δ | 16 | 25 | 19 | 0.37 |

mlh1Δ | 30 | 55 | 26 | 0.86 |

msh5Δ | 17 | 24 | 16 | 0.48 |

mlh1Δ msh5Δ | 24 | 48 | 27 | 0.87 |

Tetrads displaying the tetratype class at both the

*URA3-LYS2*and the*LYS2-HIS3*intervals were examined for chromatid interference.*P*-values derived from χ^{2}analysis indicate the probability that the number of tetrads with exchanges involving two, three, and four chromatids follows a 1:2:1 neutral distribution of double crossovers.*P*-values <0.05 indicate a deviation from neutrality.