Author

Barbara Dyer

Publication Date

1978

Document Type

Dissertation/Thesis

First Advisor

Frampton, Elon W.

Degree Name

M.S. (Master of Science)

Department

Department of Biological Sciences

LCSH

Cyanobacteria||Plants, Effect of radiation on||Anacystis nidulans||DNA

Abstract

An analysis was made of gamma ray-induced single-strand scissions and their subsequent repair in the deoxyribonucleic acid (DNA) of the cyanobacterium (blue-green-alga) Anacystis nidulans. The DNA of exponentially growing cells was labeled with tritiated deoxyadenosine before the cells were irradiated with doses of 20 or 30 kilorads supplied by a ¹³⁷cesium source. Irradiated cells were returned to growth conditions, and samples were removed for analysis on linear5-20% alkaline sucrose gradients a 1 h intervals for a period of 4 h. The sedimentation coefficients (s[sub 20,w]) and molecular weight values of individual fractions from the gradients were calculated by a computer program and indicated that irradiation resulted in a reduction in the size of the single-stranded DNA recovered. Incubation under growth conditions for 1 h resulted in the recovery of larger pieces of DNA, but further incubation resulted in molecules with a reduced average molecular weight. The largest DNA fragment recovered from unirradiated cells had an s[sub 20,w] of approximately 144, yielding a molecular weight value of 3.88 X 10⁸ daltons. Exposure to a 30 kilorad dose produced about 77 single-strand breaks in the genome.

Comments

Includes bibliographical references.||Includes illustrations.

Extent

vii, 48 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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