Abstract
We have isolated plaque-forming λ particles carrying different segments of the temperate phage Mu DNA. These hybrids were obtained by heat induction of dilysogens in which Mu was inserted into the lac genes in λplac5 cI857S7. The hybrid DNA molecules, derived from three different insertions of Mu, were digested with the specific endonucleases of Hemophilus influenzae, and the resulting fragments were separated by polyacrylamide gel electrophoresis. Comparison of the fragments produced from λplac5 cI857S7, Mu, and the presumptive hybrids confirmed that a part of the λ genome had been deleted and that portions of Mu DNA had been added. The amount of Mu DNA present did not correspond to the amount of λ DNA absent. Analysis of the fragments obtained from the vegetative Mu DNA indicated that both ends of Mu DNA are variable in length.