Abstract
In a series of crosses between related strains of 2 alleles of the pdx-1 locus, the rate of production of prototrophs in different crosses varies by at least a factor of 2. Proximal and distal outside marker distribution in the prototrophs from different crosses also varies. No evidence of simple genetic control of the variability is found. The most likely order of the 2 pdx-1 allele sites with respect to the outside markers is derived.