Frampton, Elon W.
M.S. (Master of Science)
Department of Biological Sciences
Plasmid deoxyribonucleic acid (DNA) was isolated from cells labeled with [³H] uracil or [³H]deoxyadenosine by preparative equilibrium density gradient centrifugation using ethidium bromide-cesium chloride gradients. Subsequent velocity sedimentations on neutral sucrose gradients (5-20%) disclosed a major peak of radioactivity with a sedimentation constant of 54 to 57S as calculated by comparison with an internal standard and by a computer program, respectively. Exposure of the plasmid DNA to ionizing radiation before centrifugation converted it to a lower S value consistent with the conversion of covalently closed circular DNA (CCC DNA) to open circular DNA. Based on the S constants for the CCC DNA, the molecular weight of the plasmid is in the range of 30 to 34 x 10⁶ daltons, end there are about 4 copies per genome. A variety of treatments did not eliminate the plasmid and its possible function remains undetermined.
Heaton, Duane, "Characterization of the plasmid deoxyribonucleic acid in Anacystis nidulans" (1976). Graduate Research Theses & Dissertations. 1755.
vi, 55 pages
Northern Illinois University
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