Crossover frequency and crossover interference

StrainaIntervalbNo. PDNo. TNo. NPDTotalcMap
NPDob/NPDex (P)fDeviation
from wild typeg
Chromosome V
TID1CAN1-URA3409923341366410.19 (<0.0001)
URA3-HOM3455859521366430.34 (<0.0001)
HOM3-TRP2109426841366110.50 (0.16)
tid1CAN1-URA3361628381027421.00.37 (<0.0001)0.01
URA3-HOM3363608561027461.10.63 (0.0003)0.007
HOM3-TRP2617386241027262.4*0.96 (0.84)<0.0001
tid1-pTID1CAN1-URA3331797471175460.90.32 (<0.0001)0.001
URA3-HOM3320804511175470.90.38 (<0.0001)0.35
HOM3-TRP282834251175160.70.31 (0.006)0.39
Chromosome III
TID1URA3-LEU281331621131140.14 (0.0013)
LEU2-MAT509594281131340.42 (<0.0001)
URA3-MAT346728571131470.40 (<0.0001)
tid1URA3-LEU21002186511939.10.651.25 (0.62)0.045
LEU2-MAT462670611193431.30.70 (0.005)<0.0001
URA3-MAT425681871193501.10.95 (0.60)0.0005
DMC1-YEpRAD54URA3-LEU291927631198120.33 (0.046)
LEU2-MAT529641281198340.37 (<0.0001)
URA3-MAT379772471198440.31 (<0.0001)
dmc1Δ-YEpRAD54URA3-LEU21038197412398.90.741.0 (1.0)0.61
LEU2-MAT599581591239381.11.1 (0.41)<0.0001
URA3-MAT542617801239441.01.3 (0.03)<0.0001
  • a a Strains used were as follows. Chromosome V: TID1, MSY1172 × MSY1174; tid1, MSY622 × MSY626; tid1-YCpTID1, MSY626 × MSY818. Chromosome III: TID1, NKY1543 × MSY1153; tid1, MSY962 × MSY964; DMC1-YEpRAD54, MSY1176 × MSY1178; dmc1Δ-YEpRAD54, MSY1068 × MSY1072. TID1 and DMC1-YEpRAD54 controls carry the same number of functional copies of the amino acid biosynthetic gene used to mark the tid1 and dmc1 deletion alleles as do strains carrying the deletion alleles (e.g., if the mutant strain is tid1Δ::LEU2/tid1Δ::LEU2 leu2/leu2, the wild-type control is TID1/TID1 LEU2/LEU2). Controls were designed in this way because previous work showed amino acid auxotrophy can alter gene conversion frequency (Abdullah and Borts 2001). Additional control experiments showed that absence of the amino acid biosynthetic genes used as markers in This study altered conversion frequency slightly, but did not substantially alter crossover frequency or crossover interference (data not shown).

  • b For chromosome V, URA3 refers to the normal URA3 locus. For chromosome III URA3 and LEU2 refer to insertions of those genes at the HIS4 locus (see Figure 1).

  • c Only four-spore-viable tetrads that did not show non-Mendelian segregation were included.

  • d See materials and methods for method of calculation. Only four-spore-viable tetrads that did not show non-Mendelian segregation were used to calculate map distances.

  • e Ratio of map distance for mutant over wild-type control. Asterisk indicates significant differences between mutant and wild type.

  • f The fraction of NPDs expected (see materials and methods) divided by the fraction of NPDs observed. P values in parentheses indicate significant differences between NPDob and NPDex.

  • g P values indicating significance of differences between PD, T, and NPD frequencies between mutants and isogenic wild-type controls.