Mapping of in vivo messenger RNAs for bacteriophage phiX-174.

In vivo messenger RNA for bacteriophage phiX174 was fractionated in agarose gels into a number of discrete species ranging in size from 0.23 X 10(6) to 2.3 X 10(6) daltons. These RNA species were eluted from the gels and hybridized to specific fragments derived from phiX-174 replicative form DNA by cleavage with restriction enzymes. A map of the orientation of in vivo messenger RNAs with respect to the bacteriophage genetic map was constructed. This map indicated that initiation of messenger RNA occurred before gene B, gene C or D, and probably before gene A and that termination occurred after genes E, F, G, and H. Termination of transcription at any particular site appeared not to be entirely effective such that a number of overlapping transcripts with the same 5'-terminus was observed. Messenger RNA for gene A seemed to be relatively unstable.