Anomalous Segregation in Crosses of Escherichia coli

Abstract

Segregation in crosses of the bacterium E. coli of the linked group of loci S, Gal, Ara, Xyl, and Mal is such that these cannot be arranged in an unambiguous linear sequence by the usual methods. This anomaly is interpreted as due to an excess of double crossovers too great to be attributable to irregularities in chromosome pairing, and not such as could result from a selective mechanism (inversion, ring chromosome, or combination of lethal genes) acting against single crossovers. This negative interference in crossing-over seems to occur in all chromosome regions tested.