Abstract

Two group A phages, P9c/2 and P4/2, were studied. Their density, sedimentation velocity, and biochemical properties were compared. Their densities were determined by density gradient centrifugation in 38.3% cesium chloride. Sedimentation velocity was used to determine their molecular weights. To accomplish this, the DNA of P9c/2 and P4/2 was labeled with tritium and T2 DNA, labeled with 32P, was used as a standard. The DNA of P9c/2 and P4/2 was separately mixed with T2 DNA and centrifuged in a 0-15% sucrose gradient. The molecular weights were calculated using the formula D2/D1= (M2/M1)0.35.The amount of DNA in a phage suspension was determined using a modification of the Dische Diphenylamine test for DNA. The amount of protein was determined using a modification of the techniques of Lowry.

From this study, the density of P9c/2 was found to be 1.52. The density of P4/2, previously determined in our laboratory, was 1.50. The molecular weight of P9c/2 was calculated to be 22.94x106 ± 1.53 daltons and that of P4/2,16.61x106 daltons. P9c/2 had a DNA content of 1.21x10-16 gm/pfu and a protein content of 1.32x10 gm/pfu. Thus DNA constitutes 47.8% of the phage particle and protein 52.2%. In contrast, the DNA content of P4/2 previously determined in our laboratory was 1.26x10-16 gm/pfu. Thus DNA constitutes 43.6% of the P4/2 phage particle and protein 56.4%.

Since the density of DNA in cesium chloride is much higher than is protein, a higher density for P9c/2 than for P4/2 is consistent with a larger amount of DNA in the former phage. Since all the DNA in a bacteriophage is in the form of a single molecule, all three determinations of phage density, biochemical analysis of the phage and sedimentation velocity of the phage DNA, give evidence to indicate that the molecule of P9c/2 DNA is larger than that of P4/2.

LLU Discipline

Biology

Department

Biology

School

Graduate School

First Advisor

Robert L. Nutter

Second Advisor

Leonard R. Bullas

Third Advisor

Elmer A. Widmer

Degree Name

Master of Arts (MA)

Degree Level

M.A.

Year Degree Awarded

1970

Date (Title Page)

8-1970

Language

English

Library of Congress/MESH Subject Headings

Salmonella; DNA, Bacterial

Type

Thesis

Page Count

vii; 37

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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