ABSTRACT
Thiobacillus ferrooxidans AP19-3 has a novel NADH-dependent sulfite reductase in the periplasmic space. The gene responsible for the appearance of NADH-dependent sulfite reductase activity was cloned into a vector plasmid pBR322 to give a 5.7-kb hybrid plasmid, pTHS1, which contains a 1.3-kb DNA fragment of T. ferrooxidans AP19-3. When pTHS1 was used to transform sulfite reductase deficient E. coli mutants, strain AT2455 (cysG), JM246 (cysI), and AT2427 (cysJ), it complemented only the E. coli cysG mutation. Since cysG codes for S-adenosyl-L-methionine: uroporphyrinogen III methyltransferase, the enzyme involved in siroheme synthesis, the results indicate that the DNA region that codes for S-adenosyl-L-methionine: uroporphyrinogen III methyltransferase is present in a T. ferrooxidans 1.3 kb DNA fragment on pTHS1.
Subject(s)
Escherichia coli/genetics , Genetic Complementation Test , Methyltransferases/genetics , Thiobacillus/genetics , DNA, Bacterial , Mutation , NAD/metabolism , Oxidoreductases Acting on Sulfur Group Donors/metabolism , PlasmidsABSTRACT
Twenty-four conventional chest radiographs with small solitary pulmonary nodules were digitized to analyze optical density gradient. An index number, that could reflect sharpness and contrast of tumor lung interface, was calculated to differentiate benign from malignant pulmonary nodules. In four of 12 patients with benign non-calcified nodules, the index number allowed correct classification as a benign lesion.