Genetic analysis ofEscherichia coli K-12 stows that the unequal genetic contribution of the two parents to the progeny can be explained by the assumption of a highly localized disturbance in segregation, whereby a locus or small regionE of a chromosome is contributed to most of the progeny by theF — parent only. The position of this regionE, as inferred from haploid segregation data, shows a remarkable correlation with the position of the ‘eliminated segment’ which is haploid, and mostly ofF — origin, in otherwise diploid ‘heterozygotes’. In addition, segregations are disturbed "by irregular pairing, which determines apparent negative interference, and seriously biases the assessment of gene order and estimation of linkage unless taken in proper consideration. The simplest representation calls for a single linkage group, carrying in the middle the elimination locusE, and thus dividing the single chromosome into two practically independent segregation groups. Although this picture may need further refinement, as there may be more than one elimination locus or break defining the extremes of the eliminated region, it has permitted consistent mapping of the markers investigated so far.
TheHfr mating-type behaves as a locus close to, or identical with,E. The possible relationships ofE, Hfr/F + and the lambda prophage have been discussed.
Volume 100, 2021
Continuous Article Publishing mode
Click here for Editorial Note on CAP Mode