Correlation of the genetic and physical maps of phage T1

A series of BglII- and Sau3A-derived fragments of phage T1 DNA were cloned into the plasmid vector pLV59 and the clones were tested for their ability to complement and recombine with infecting genomes of am mutants representing all known T1 essential genes. The resulting data were used to correlate the T1 genetic and physical maps. This analysis led to the following conclusions: the large map distances observed at the left (early) end of the genetic map arise partly from increased genetic recombination at the chromosomal left end and partly from increased physical distances between identified genetic markers in this region, the right chromosomal end is also recombinogenic, genes 3.5 to 18, which occupy the right two-thirds of the DNA molecule, are tightly compacted with little space for additional protein-specifying sequences in this region.