TABLE 1

Segregation pattern of Gfp+ allelic loxP recombinants in tetrads

Gal+ (hr)Count of tetrad classes
0:4 Gfp+1:3 Gfp+2:2 Gfp+TotalNobs/Nexp
046837186654673.9
130254473735093.7
235743813739925.6
43915526397346.4
  • Cre recombinase was induced with 0.03% galactose in synchronized meiotic cultures at the time point indicated, as described in Peoples et al. (2002). Unambiguous four-spore tetrads were evaluated for the number of Gfp+ spores by fluorescence light microscopy (Figure 1). The Nobs/Nexp ratio was determined as the ratio of observed to expected 2:2 Gfp+ tetrads under the assumptions of Papazian (1952) as described in Figure 2. Using the χ2 method found at the Stahl Lab Online Tools, P-values for all time points were ≪0.001, indicating a significant deviation from random expectations.