ABSTRACT
Biological oxidation of cyclic alcohols normally results in formation of the corresponding dicarboxylic acids, which are further metabolized and enter the central carbon metabolism in the cell. We isolated an Acinetobacter sp. from an industrial wastewater bioreactor that utilized cyclohexanol as a sole carbon source. A cosmid library was constructed from Acinetobacter sp. strain SE19, and oxidation of cyclohexanol to adipic acid was demonstrated in recombinant Escherichia coli carrying a SE19 DNA segment. A region that was essential for cyclohexanol oxidation was localized to a 14-kb fragment on the cosmid DNA. Several putative open reading frames (ORFs) that were expected to encode enzymes catalyzing the conversion of cyclohexanol to adipic acid were identified. Whereas one ORF showed high homology to cyclohexanone monooxygenase from Acinetobacter sp. strain NCIB 9871, most of the ORFs showed only moderate homology to proteins in GenBank. In order to assign functions of the various ORFs, in vitro transposon mutagenesis was performed using the cosmid DNA as a target. A set of transposon mutants with a single insertion in each of the ORFs was screened for cyclohexanol oxidation in E. coli. Several of the transposon mutants accumulated a variety of cyclohexanol oxidation intermediates. The in vitro transposon mutagenesis technique was shown to be a powerful tool for rapidly assigning gene functions to all ORFs in the pathway.
Subject(s)
Acinetobacter/genetics , Adipates/metabolism , Bacterial Proteins , Cyclohexanols/metabolism , Genes, Bacterial , Multigene Family , Acinetobacter/growth & development , Acinetobacter/isolation & purification , Aldehyde Oxidoreductases/genetics , Base Sequence , Cloning, Molecular , Cosmids , DNA, Bacterial , Molecular Sequence Data , Oxidation-Reduction , Trans-Activators/geneticsABSTRACT
Molecular orbital spectral predictions suggest that 2,5,7,10,12,15,17,20-octaaza-21H, 23H-porphine has a visible spectral range closely matching that of chlorophyll-a. Since the octaazaporphine is, in its core, a simple derivative of an (HCN)12 oligomer, this fact, together with its spectral properties, would suggest that it occupies a high rank as a primordial porphinic solar energy transducer for photochemistry essential to life's formation. The demonstration that the mass 324 hexahydrooctaazaporphine is formed in protic media by the cyclotetramerization of imidazol-4-aminohydroxonium ion or the derived nitrenium ion, and that a mass 318 species consonant with that of the Huckel aromatic octaazaporphine is observed in the course of these studies, strongly supports the proposed octaazaporphine synthesis in a prebiotic hydrocyanic acid milieu.
Subject(s)
Hydrogen Cyanide/chemistry , Hydrogen Cyanide/radiation effects , Nitroimidazoles/chemical synthesis , Origin of Life , Porphyrins/chemical synthesis , Sunlight , Chlorophyll/chemistry , Chlorophyll A , Ions , Nitrogen Compounds/chemistry , Photochemistry , Spectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationABSTRACT
Fresh-brewed regular coffee at concentrations of 25, 50, and 100% was consumed ad libitum as the sole fluid intake of F1 Sprague-Dawley rats (55 male and 55 female/group), derived from P0-treated females which were provided 50% coffee for about 5 weeks prior to copulation and throughout gestation and lactation. P0 males, P0 control females, and two groups of F1 control rats received tap water. Ten rats/sex/level were killed and examined after 1 year; survivors were killed after 2 years. Smaller mean body weights (50 and 100% coffee concentrations) occurred with increased feed and liquid consumption. Mean serum alkaline phosphatase, bilirubin, BUN, and calcium values occasionally were elevated. Serum cholesterol levels at 2 years were elevated in males (25 and 100%) and at 1 and 2 years in females (100%). Bone calcium was slightly reduced in females consuming 25 or 100% coffee for 1 year, but not after 2 years. Treatment-related increases in relative weights of lungs, kidneys, liver, and epididymides were recorded. Significantly increased mortality was observed in females receiving 50 or 100% coffee. There also was some evidence of a relationship between coffee consumption and the number of primary tumor-bearing animals; however, this finding appeared ambiguous, dependent on the assumption that tumors were the probable cause of death.
Subject(s)
Abnormalities, Drug-Induced , Caffeine/toxicity , Carcinogens , Fetus/drug effects , Neoplasms/chemically induced , Animals , Body Weight/drug effects , Bone and Bones/analysis , Calcium/analysis , Female , Male , Pregnancy , Rats , Rats, Inbred StrainsABSTRACT
Polyvinyl chloride (PVC) films used for food wraps contain significant concentrations of plasticizers, along with other additives. The rate of migration of these plasticizers to foods and food-simulating solvents is the principal concern of this paper, which reviews prior experimental studies and presents new data for radiolabelled dioctyl adipate. Analytical models are described to correlate many of the data, criteria are presented for identifying the controlling step in the mechanism of transfer of plasticizer from PVC films into foods and food-simulating solvents, and tentative recommendations are offered for the selection of food simulants and for the type of experiment necessary to allow an unambiguous interpretation of the data.