This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wing, J. P. Search for Related Content PubMed PubMed Citation Articles by Wing, J. P.

Integration and Induction of Phage P22 in a Recombination-deficient Mutant of Salmonella typhimurium¹

Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48104

ABSTRACT

Phage P22 can integrate as prophage into a recombination-deficient (Rec^–) strain of Salmonella typhimurium. At 37 C, the integration efficiency is only 10% that in Rec⁺ infection, but at 25 C the efficiencies in Rec^– and Rec⁺ hosts are similar. Rec^– lysogens cannot be induced by ultraviolet irradiation or by treatments with the chemical inducing agents streptonigrin or mitomycin C. Heat induction of Rec^– cells lysogenic for a temperature-sensitive c₂ mutant (ts c₂) is normal, showing that the Rec^– cell has the machinery necessary for prophage excision. Ultraviolet irradiation of Rec^– (ts c₂) lysogens prior to heat induction does not prevent the formation of infective centers after temperature shift. Thus, the noninducibility of Rec^– lysogens is not due to destruction of the prophage as a result of ultraviolet irradiation. Deoxyribonucleic acid-ribonucleic acid (RNA) hybridization experiments demonstrate that no increase in phage-specific RNA synthesis occurs after ultraviolet irradiation of a Rec^– (c⁺) lysogen. The Rec^– mutant appears to lack part of the mechanism required to destroy the phage repressor and allow the initiation of early phage functions such as messenger RNA synthesis. A similar conclusion was reached previously for an Escherichia coli Rec^– strain.

² Predoctoral trainee of the NIH (USPHS 5 T01-GM00071-10), Department of Human Genetics, University of Michigan Medical School, Ann Arbor.

¹ Taken from a thesis submitted by the author to the University of Michigan in partial fulfillment of the requirements for the Ph.D. degree, 1967.