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Independent Functions of Viral Protein and Nucleic Acid in Growth of Bacteriophage. September 20, 1952.

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Title:	Independent Functions of Viral Protein and Nucleic Acid in Growth of Bacteriophage [6 of 18]
Creator:	Chase, Martha
Contributor:	Hershey, Alfred Day, 1908
Publisher:	Journal of General Physiology
Date:	1952-09-20
Subject:	Molecular biology Molecular genetics
Description:	From the Journal of General Physiology Vol. 36, No. 1.
Type:	Text
Format:	text/plain
Language:	en
Identifier:	hersheychase-pg06.jpg
Source:	Master scanned with Epson GT-10000+ flatbed scanner at 600 dpi.
Rights:	http://osulibrary.orst.edu/specialcollections/coll/pauling/dna/copyright.html
Full Text:	44 VIRAL PROTEIN AND NUCLEIC ACID IN BACTERIOPHAGE GROWTH that shown in Table III, and the content of P" was only slightly less after lysis. The phage liberated during freezing and thawing was also titrated in this experiment. The lysis occurred without appreciable liberation of phage in suspensions frozen up to and including the 16th minute, and the 20 min- ute sample yielded only five per bacterium. Another sample of the culture formalinized at 30 minutes, and centrifuged without freezing, contained 66 per cent of the P12 in non-sedimentable form. The yield of extracellular phage at 30 minutes was 108 per bacterium, and the sedimented material consisted largely of formless debris but contained also many apparently intact cell membranes. T.ULE III Sensitization of Intracellular Phage to DA'ase by Freezing, Thawing, and Fixation with Formaldehyde Unadsorbed Infected cells phage frozen, frozen, thawed, Infected cells i thawed, fixed fixed fixed only Low speed sediment fraction Total P12.................................... 71 ,96 Acid-soluble... . . . ........ . . . . . . . . . . . . . . . . . . . 0 0.5 Acid-soluble after DNase................... . . 59 28 Low speed supernatant fraction Total P12.................................... 29 14 Acid-soluble.......................... ....... 1 0.8 0.4 Acid-soluble after DNase............... . . . . . . 11 21 5.5 The figures express per cent of total P12 in the original phage, or its adsorbed fraction. We draw the following conclusions from the experiments in which cells infected with P32-labeled phage are subjected to freezing and thawing. 1. Plnage DNA becomes sensitive to DNAse after adsorption to bacteria in buffer under conditions in which no known growth process occurs (Benzer, 1912; D ulbecco, 1952). 2. The cell membrane can be made permeable to DNase under conditions that do not permit the escape of either the intracellular P3= or the bulk of the cell contents. 3. Even if the cells lyse as a result of freezing and thawing, permitting escape of other cell constituents, most of the P3'= derived from phage remains inside the cell membranes, as do the mature phage progeny. 4. The intracellular P3' derived from phage is largely freed during spon- taneous lysis accompanied by phage liberation.