The breakdown of the restriction mechanism in zygotes of Escherichia coli

In zygotes from matings between Hfr, F′ or F+ donors of E. coli K and F− recipients of E. coli B the restriction of λ. K and λ.C is 100 times less than in unmated B cells. This decrease in the capacity of zygotes to restrict phage λ is transient and is not related to the transfer of genes controlling host-induced modification during the cross.