Restriction cleavage maps of coliphages 186 and P2.

The restriction enzymes BamHI, Bg/II, EcoRI, HindIII, PstI, XbaI and XhoI have been used to cleave DNA isolated from the related coliphages P2 and 186 for analysis on 1% agarose gels. Three approaches were used to map the sites of cleavage: a) analysis dependent upon the existence of cohesive termini and availability of viable P2-186 hybrids; b) analysis of double digests and redigests of isolated fragments with a second enzyme and c) analysis of partial digests by transfer to nitrocellulose and hybridization with a single fragment. This last approach and the results obtained from it are detailed in a separate paper (Saint and Egan, 1979). The number of sites of each enzyme are as follows: a) 186, BamHI-7, Bg/II-1, EcoRI-3, HindIII-2, PstI-22, XbaI-0 and Xho-I-1; b) P2, BamHI-3, Bg/II-2, EcoRI-3, HindIII-0, PstI-O, XbaI-1 and XhoI-O. All of these sites have been mapped with the exception of PstI for 186, where only the five sites in the right 35% (the control region) have been mapped.