Partial exclusion of bacteriophage T2 by T4: An early function of the second linkage group

Evidence for exclusion as an early function of phage T4 was obtained along the following lines: a) In crosses of T2 and T4am 122, a mutant of an early phage enzyme, T2 is virtually eliminated from the progeny; b) there is no net synthesis of DNA in the mixed complexes of the non-permissive host; furthermore, there is a loss of DNA, not found in the monocomplexes of T4am 122; this suggests a specific breakdown of T2 DNA; c) a cross was made between T4 and a partially non-excludable, otherwise T2-like phage strain that did not exclude standard type T2. The gene responsible for exclusion segregated in an almost normal way and appeared to reside in-betweenh⁺ andr at the beginning of the map segment of T4 for the early functions.The frequencies with which the genes of T2 were recovered in the progeny of this cross showed polarity, i.e. the frequency of the T2 genes along the segment of the early functions increased gradually from 0.26 for the adsorption properties to 0.44 for the UV sensitivity of T2 in correlation with the position of the genes on the map.There is a stronger effect of exclusion and a more pronounced polarity of the frequencies of recovered genes of T2 whenE. coli CR 63 is used as a host instead ofE. coli B.This work was carried out partially within the frame of the association between Euratom and the University of Leiden embodied in contract nr. 052-64-1 BIAN.