Inactivation of Bacteriophages by Decay of Incorporated Radioactive Phosphorus

Abstract

It was observed by Hershey, Kamen, Kennedy, and Gest (1951) that bacteriophages are unstable if they contain radiophosphorus p82 of high specific activity. From day to day, progressively decreasing fractions of such populations of radioactive phage are still able to form plaques when plated on a sensitive bacterial strain, and the rate of loss of infective titer depends on the specific activity of the P= assimilated. It is the purpose of this communication to present experiments in which these observations of Hershey et al.have been extended to the study of the lethal effects of ps~ decay in various strains of bacteriophage at various temperatures and to the examination of some of the biological properties of the inactivated bacteriophage particles. Some of these experiments have already been reported in preliminary form . Materials and MethodsBacteriophages T1, T2, T3, TS, TT, and their host, E. ¢oli B/r, and phage )~ and its host, E. co~i strain K12S, were used in this study. Strain B/r, a radiation-resistant mutant derived from strain B, was kindly supplied to us by Dr. Aaron Novick.Glycerol-casamino acid medium refers to a medium devised by Fraser and Jerrel (1953). H medium is a glycerol-lactate medium of the following composition per liter of distilled water: 1.5 gin. KC1, 5 gln. NaC1, 1 gin. NH4C1, 0.25 gin. MgSO4.TH~O, 10 "4 N CaC12, 0.07 M sodium lactate, 2 gin. glycerol, 0.5 gin. bacto-peptone Difco and 0.5 grn. bacto-easamino acids Dffco. H medium contains 6 reg./liter total phosphorus, of which 5 reg./liter are supplied by the easamino acids and I reg./liter by the peptone. Control experiments show that this phosphorus is assimilated by cultures of E. coli neither more nor less readily than inorganic phosphate. The techniques described by Adams (1950) were employed for the general procedures of bacteriophagy.

A Study of the Retention and the Mutagenic Mode of Action of Radioactive Phosphorus in Drosophila Melanogaster

“…In this way efficiencies of about 0.1 for the disintegration of Pas have llerii obtained both for the "suicide" of bacteriophage (HERSHEY et , STENT 1953, STENT and FUERST 1955 and for the inactivation of bacteria (FUERST and STENT 1956). Indeed, this figure of 1/10 is used by LEVINTHAL (1956) for the deduction of the number of Pa' atoms incorporated per bacteriophage particle from the number of inactivations observed.…”

Phosphorus-32 in the Phage Group: radioisotopes as historical tracers of molecular biology

“…Because, according to the Watson–Crick model, DNA is double-stranded, a single break in the polynucleotide backbone—due to either the replacement of a phosphorus-32 atom by sulfur-32 upon radioactive decay or the energy released by the decay—would not disrupt the DNA molecule. But a second break across from the first would break the double-helical chain (Stent & Fuerst, 1955, pp. 454–456).…”

The Release and Stability of the Large Subunit of Dna From T2 and T4 Bacteriophage

“…(12). The supernatants were poured off, and a small amount removed for determining the inactivation rate by suicide (13,14). Another addition of 2 X 10 ° Serratia cells was made and the mixture treated with DNAase and RNAase (at final concentration of 5 3" per ml.…”

“…Effect of p32 Decay on Heat Stability.--In addition to the possibility that a p32 decay breaks the opposite polynucleotide chain, there is a certainty that it interrupts the polynucleotide chain in which it resides (14). To a large extent this single chain breakage is similar to the enzymatic degradation of DNA, a process which proceeds by the cleaving of single phosphorus-ester linkages (21).…”