Portland State University. Department of Biology
John W. Myers
Date of Award
Master of Science (M.S.) in Biology
1 online resource (74 p.)
Plasmids, Arsenic, R factors, Bacterial genetics
The trivalent (arsenite) and pentavalent (arsenate) forms of arsenic are introduced into the environment through the use of arsenic in herbicides, pesticides, fertilizers, and the smelting of arsenic-bearing ores. Bacteria resistant to arsenic are readily isolated from surface waters, sewage, and clinical infections. Although some bacterial resistance is provided by inducible phosphate transport systems that discriminate against arsenate, marked resistance is carried on bacterial plasmids.
A 6.9 kilobase fragment previously derived from one such plasmid, R45, and containing the genes for inducible resistance to arsenite and arsenate was ligated into the cloning vectors puce and pUC9 in opposite orientations and transformed into Escherichia coli JM 105. Insertion into the multiple cloning site of the pUC vectors places the inserted fragment under the inducible control of the lac operon promoter. An attempt was made to determine the direction of transcription in the fragment by growth in 10-3 M isopropyl-β-D-thiogalactoside prior to challenge with arsenite.
Coons, Terry M., "Restriction mapping and expression of recombinant plasmids containing the arsenic resistance genes of the plasmid R45" (1986). Dissertations and Theses. Paper 3597.