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Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III. January 1944.

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Title:	Studies on the Chemical Nature of the Substance [15 of 23]
Alternative Title:	Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III
Creator:	Avery, Oswald T.
Contributor:	MacLeod, Colin M.
Publisher:	Journal of Experimental Medicine
Date:	1944-01-00
Subject:	Cellular signal transduction
Description:	From the Journal of Experimental Medicine Vol. 79, No. 1.
Type:	Text
Format:	text/plain
Language:	en
Identifier:	avery-pg15.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:	OSWALD T. AVERY, COLIN M. MACLEOD, AND MACLYN MCCARTY 151 optically visible boundary. Thus in both the electrical and centrifugal fields, the behavior of the purified substance is consistent with the concept that bio- logical activity is a property of the highly polymerized nucleic acid. Ultraviolet absorption curves showed maxima in the region of 2600 A and minima in the region of 2350 A. These findings are characteristic of nucleic acids. Qua,iditative Determination of Biological Activity.-In its highly purified state the material as isolated has been found to be capable of inducing transformation in amounts ranging from 0.02 to 0.003 yg. Preparation 44, the purification of which was carried out at low temperature and which had a nitrogen-phosphorus TABLE IV Titration of Transforming Activity of Preparation 44 Transforming principle 1 Quadruplicate tests 3 4 Preparation 44' 2 Amount Diffuse Colony Diffuse Colony Diffuse Colony Diffuse Colony Dilution added growth form growth form growth form growth form A8. 10-2 1.0 -E. SIII SIII -F Sill Sill l0-2.G 0.3 sill Sill -F. Sill SIII 10-3 0.1 -I- SIII -F Sill -f- SIII SIII 10-3.5 0.03 -I- sill sill Sill SIII 10-4 0.01 Sill sill Sill -1. Sill 10-4.5 0.003 R only sill R only sill 10-5 0.001 R " R only R " R only Control None R " R " R " R " ' Solution from which dilutions were made contained 0.5 mg. per cc. of purified material. 0.2 cc. of each dilution added to quadruplicate tubes containing 2.0 cc. of standard serum broth. 0.05 cc. of a 10' dilution of a blood broth culture of R36A is added to each tube. ratio of 1.58, exhibited high transforming activity. of this preparation is given in Table IV. Titration of the activity A solution containing 0.5 mg. per cc. was serially diluted as shown in the protocol. 0.2 cc. of each of these dilutions was added to quadruplicate tubes containing 2.0 cc. of standard serum broth. All tubes were then inoculated with 0.05 cc. of a 10-4 dilution of a 5 to 8 hour blood broth culture of R36A. Transforming activity was determined by the procedure described under Method of titration. The data presented in Table IV show that on the basis of dry weight 0.003 leg. of the active material brought about transformation. Since the reaction system containing the 0.003 leg. has a volume of 2.25 cc., this represents a final concentration of the purified substance of 1 part in 600,000,000.