Meiotic segregation patterns in wild-type and <i>GAL-POL1</i> strains.

Tetrads were examined from AMC45 (wild-type) and AMC20 (GAL-POL1). Cells from the two strains were sporulated under identical conditions on plates containing either high or low levels of galactose. CentiMorgan distances in parentheses for the HPH–TRP1 and TRP1–URA3 intervals are calculated without NPDs [32]; in the HPH–URA3 interval, distances in parentheses are calculated using only those NPDs that are the result of a 4-strand double crossovers around TRP1 (see text for details). Spore viability was 93% (wild-type, high galactose), 82% (GAL-POL1, high galactose), 90% (wild-type, low galactose), and 62% (GAL-POL1, low galactose). Sporulation efficiency was 17% (wild-type, high galactose), 19% (GAL-POL1, high galactose), 18% (wild-type, low galactose), and 17% (GAL-POL1, low galactose). PD, parental ditype; T, tetratype; NPD, nonparental ditype; cM, centiMorgans; nd, not determined because the expected value was 0. *Expected NPD tetrads if there is no interference, calculated using Stahl Lab Online Tools “A Better Way” (http://molbio.uoregon.edu/~fstahl/ and [35]). †Chi-square test, one degree of freedom. ‡Degree of interference, calculated as 1 − (NPDobs/NPDexp). §Since there was no significant difference in the proportion of tetrad classes in cells sporulated on high and low galactose media for the wild-type cells, these data were combined.