Structure and Function of the Genome of Coliphage T5

Abstract
Separated strands of ligated DNA from coliphage T5+ and single‐stranded fragments purified from alkaline‐denatured DNA were used in DNA‐DNA annealing experiments. The products of such experiments were analyzed by analytical ultracentrifugation to equilibrium in a CsCl density gradient as well as by electron microscopy. Pycnometric analyses showed that the heavy strand is the uninterrupted strand, whereas the light strand is the ligated form of the nicked strand. All fragments of length shorter than one half of the complete DNA molecule are derived from the light strand. A new arrangement of the single‐stranded fragments of the T5+ chromosome has been deduced from electron microscopic analysis and has resulted in a new model of the physical structure of the DNA of T5+.