TABLE 7

Genetic alterations leading to loss of the hemizygous URA3 marker on chromosome III

ClassesFrequencya
(×105)
Ratio
(%)
Loss of chromosome III6.855
Interchromosal recombination
    Allelic crossing over (with loss of chromosome III)4.337
0.252.1
    Gene conversion0.0320.27
    Ectopic crossing over0.635.5
Intrachromosomal deletion (MAT-HMR deletion)0.312.6
Intragenic point mutation0.00710.060
Total12100
  • a The frequency of each class was estimated by multiplying the frequency of 5-FOAr Leu- cells (6.8 × 10-5), 5-FOAr Leu+ Ade- cells (4.9 × 10-5), and 5-FOAr Leu+ Ade+ cells (0.35 × 10-5) by the corresponding ratio of the examined clones of each phenotype, respectively, as explained in the text.