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Final Technical Report

Description: The work done with DOE support during this 15 year period was extensive and successful. It is best summarized by the list of 58 publications (below) which reported progress made with DOE support. These are from the grant period and a few more recent reporting on grant research. Mostly these are primary research reports in reviewed journals. There are also, however, many summary reviews in review journals and in scientific monographs, as they also are key places for reporting research progress. What we did during this grant period (and much longer) was to characterize genetic determinants for bacterial resistances to additional toxic heavy metals of DOE concern, through starting with phenotypic properties of the resistant bacteria to DNA sequence determination and characterization of the genes involved. Over the years (and as shown in the list of publications), the toxic metal-forming elements we have studied included Ag, As, Cd, Cr, and Hg. In each case, we started with basically nothing (or very little) known, progressed through quite detailed understanding, until other laboratory groups also became strongly involved in related studies. More recently, with DOE support, we were the first laboratory group in the world to identify genes for bacterial resistance to silver salts (sil genes) and the closely related silver-and-copper resistance genes cus. This was initially reported in detail in Gupta et al. (1999; see publications list below). We also identified the first toxic metal 'gene island' (multiple transcripts and perhaps 25 genes each in need of detailed study) which encodes the subunits of arsenite oxidase (which we called aso; Silver and Phung, 2005; but most other researchers have subsequently settled on aox for the gene mnemonic). Both of these systems were firsts. Now a few years later, a search on GenBank shows that each is now represented by gene families ...
Date: May 28, 2009
Creator: Silver, Simon
Partner: UNT Libraries Government Documents Department

Cometabolic bioremediation

Description: Cometabolic bioremediation is probably the most under appreciated bioremediation strategy currently available. Cometabolism strategies stimulate only indigenous microbes with the ability to degrade the contaminant and cosubstrate e.g. methane, propane, toluene and others. This highly targeted stimulation insures that only those microbes that can degrade the contaminant are targeted, thus reducing amendment costs, well and formation plugging, etc. Cometabolic bioremediation has been used on some of the most recalcitrant contaminants, e.g. PCE, TCE, MTBE, TNT, dioxane, atrazine, etc. Methanotrophs have been demonstrated to produce methane monooxygense, an oxidase that can degrade over 300 compounds. Cometabolic bioremediation also has the advantage of being able to degrade contaminants to trace concentrations, since the biodegrader is not dependent on the contaminant for carbon or energy. Increasingly we are finding that in order to protect human health and the environment that we must remediate to lower and lower concentrations, especially for compounds like endocrine disrupters, thus cometabolism may be the best and maybe the only possibility that we have to bioremediate some contaminants.
Date: February 15, 2009
Creator: Hazen, Terry C.
Partner: UNT Libraries Government Documents Department

Imaging Monoamine Oxidase in the Human Brain

Description: Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.
Date: November 10, 1999
Creator: Fowler, J. S.; Volkow, N. D.; Wang, G-J. & Logan, Jean
Partner: UNT Libraries Government Documents Department


Description: Purified and reconstituted cytochrome {und c} oxidase and mitochondria were crosslinked with biimidates in the presence and absence of cytochrome {und c}. These experiments indicate that oxidase subunit interactions are required for activity and that cytochrome {und c} mobility may be required for electron transport activity. Biimidate treatment of purified and reconstituted oxidase crosslinks all of the oxidase protomers except subunit I when {ge} 20% of the free amines are modified and inhibits steady state oxidase activity. Transient kinetics of ferrocytochrome {und c} oxidation and ferricytochrome {und a} reduction indicates inhibition of electron transfer from heme {und a} to heme {und a}{sub 3}. Crosslinking oxidase molecules to form large aggregates displaying rotational correlation times {ge} 1 ms does not affect oxidase activity. Crosslinking of mitochondria covalently binds the bc{sub 1} and {und aa}{sub 3} complexes to cytochrome {und c}, and inhibits steady-state oxidase activity considerably more than in the case of the purified oxidase. Addition of cytochrome {und c} to the purified oxidase or to {und c}-depleted mitoplasts increases inhibition slightly. Cytochrome {und c} oligomers act as competitive inhibitors of native {und c}, however, crosslinking of cytochrome {und c} to {und c}-depleted mitoplasts or purified oxidase (with dimethyl suberimidate or hetrobifunctional crosslinking reagents) results in a catalytically inactive complex.
Date: December 1, 1979
Creator: Swanson, Maurice & Packer, Lester
Partner: UNT Libraries Government Documents Department

Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge

Description: Here we examine Fe speciation within Fe-encrusted biofilms formed during 2-month seafloor incubations of sulfide mineral assemblages at the Main Endeavor Segment of the Juan de Fuca Ridge. The biofilms were distributed heterogeneously across the surface of the incubated sulfide and composed primarily of particles with a twisted stalk morphology resembling those produced by some aerobic Fe-oxidizing microorganisms. Our objectives were to determine the form of biofilm-associated Fe, and identify the sulfide minerals associated with microbial growth. We used micro-focused synchrotron-radiation X-ray fluorescence mapping (mu XRF), X-ray absorption spectroscopy (mu EXAFS), and X-ray diffraction (mu XRD) in conjunction with focused ion beam (FIB) sectioning, and highresolution transmission electron microscopy (HRTEM). The chemical and mineralogical composition of an Fe-encrusted biofilm was queried at different spatial scales, and the spatial relationship between primary sulfide and secondary oxyhydroxide minerals was resolved. The Fe-encrusted biofilms formed preferentially at pyrrhotite-rich (Fe1-xS, 0<_ x<_ 0.2) regions of the incubated chimney sulfide. At the nanometer spatial scale, particles within the biofilm exhibiting lattice fringing and diffraction patterns consistent with 2-line ferrihydrite were identified infrequently. At the micron spatial scale, Fe mu EXAFS spectroscopy and mu XRD measurements indicate that the dominant form of biofilm Fe is a short-range ordered Fe oxyhydroxide characterized by pervasive edge-sharing Fe-O6 octahedral linkages. Double corner-sharing Fe-O6 linkages, which are common to Fe oxyhydroxide mineral structures of 2-line ferrihydrite, 6-line ferrihydrite, and goethite, were not detected in the biogenic iron oxyhydroxide (BIO). The suspended development of the BIO mineral structure is consistent with Fe(III) hydrolysis and polymerization in the presence of high concentrations of Fe-complexing ligands. We hypothesize that microbiologically produced Fe-complexing ligands may play critical roles in both the delivery of Fe(II) to oxidases, and the limited Fe(III) oxyhydroxide crystallinity observed within the biofilm. Our research provides insight into the structure and ...
Date: May 22, 2008
Creator: Toner, Brandy M.; Santelli, Cara M.; Marcus, Matthew A.; Wirth, Richard; Chan, Clara S.; McCollom, Thomas et al.
Partner: UNT Libraries Government Documents Department

The Respiratory Chain of Alkaliphilic Bacteria

Description: Alkaliphilic bacteria that grow at extremely high pH are confronted by particular bioenergetic problems in carrying out oxidative phosphorylation. This project focused on the properties and adaptations of the respiratory chain. The respiratory chain as a whole, the redox poises of its components and several individual complexes of the respiratory chain of alkaliphilic Bacillus pseudofirmus OF4 have been characterized as part of this project and, importantly, this project has helped support the development of genetic tools that make B. pseudofirmus OF4 the most genetically tractable and, hence, most bioenergetically characterized extreme alkaliphile. Evidence has been obtained for a pivotal role of the cca3-type terminal oxidase in oxidative phosphorylation, especially at high pH and motifs that may be relevant to that special role have been identified.
Date: January 29, 2008
Creator: Krulwich, Terry Ann
Partner: UNT Libraries Government Documents Department

Whole-Genome Transcriptional Analysis of Chemolithoautotrophic Thiosulfate Oxidation by Thiobacillus denitrificans Under Aerobic vs. Denitrifying Conditions

Description: Thiobacillus denitrificans is one of the few known obligate chemolithoautotrophic bacteria capable of energetically coupling thiosulfate oxidation to denitrification as well as aerobic respiration. As very little is known about the differential expression of genes associated with ke chemolithoautotrophic functions (such as sulfur-compound oxidation and CO2 fixation) under aerobic versus denitrifying conditions, we conducted whole-genome, cDNA microarray studies to explore this topic systematically. The microarrays identified 277 genes (approximately ten percent of the genome) as differentially expressed using Robust Multi-array Average statistical analysis and a 2-fold cutoff. Genes upregulated (ca. 6- to 150-fold) under aerobic conditions included a cluster of genes associated with iron acquisition (e.g., siderophore-related genes), a cluster of cytochrome cbb3 oxidase genes, cbbL and cbbS (encoding the large and small subunits of form I ribulose 1,5-bisphosphate carboxylase/oxygenase, or RubisCO), and multiple molecular chaperone genes. Genes upregulated (ca. 4- to 95-fold) under denitrifying conditions included nar, nir, and nor genes (associated respectively with nitrate reductase, nitrite reductase, and nitric oxide reductase, which catalyze successive steps of denitrification), cbbM (encoding form II RubisCO), and genes involved with sulfur-compound oxidation (including two physically separated but highly similar copies of sulfide:quinone oxidoreductase and of dsrC, associated with dissimilatory sulfite reductase). Among genes associated with denitrification, relative expression levels (i.e., degree of upregulation with nitrate) tended to decrease in the order nar > nir > nor > nos. Reverse transcription, quantitative PCR analysis was used to validate these trends.
Date: April 22, 2006
Creator: Beller, H R; Letain, T E; Chakicherla, A; Kane, S R; Legler, T C & Coleman, M A
Partner: UNT Libraries Government Documents Department

The Molecular Basis for Metabolic and Energetic Diversity

Description: We have used experimental and computational analysis of R. sphaeroides photosynthesis and other gene expression networks (Kaplan, Gomelsky, Donohue) (3-9, 12, 13, 15-18, 20). We have identified many new candidate photosynthesis genes with expression patterns that varied as a function of light intensity. Results from these experiments suggest there are many more light-regulated aspects of the photosynthetic lifestyle of this bacterium than previously appreciated. Ongoing genetic analysis confirms that mutations in some of these newly-identified photosynthesis block the ability of cells to use solar energy in the laboratory. We also carried out transcriptome and computational analysis of individual R. sphaeroides regulons. This identified additional genes that are directly regulated by individual transcription factors and refined the consensus sequence for master regulators of photosystem development. We also showed that PpsR indirectly regulates genes that do not contain the PpsR-binding sites, e.g. puf and puhA operons. This suggests that PpsR plays a more global role as a regulator of photosystem development than what was assumed before. A similar computational and microarray analysis of PrrA target genes has identified many new candidate promoters that are controlled by this master regulator of photosynthesis. We have begun bioinformatic, genetic and biochemical experiments aimed at elucidating the interactions of transcriptional pathways controlling photosystem development (PrrBA and AppA-PpsR). We carried out computational analysis designed to cluster oxygen-dependent genes in R. sphaeroides based on the transcriptome data for cells grown between 30% and 0% oxygen. As a result, new statistical tools for clustering expression profiles from DNA microarrays have been developed. We have analyzed the assembly, bioenergetic role and regulatory functions of the aerobic respiratory chain (Donohue, Edwards, Hosler, Kaplan)(10, 11, 14)(Hiser, 2000-4612). We have used computational, genetic and biochemical approaches to map the flow of electrons through the major bioenergetic pathways of this bacterium. From this, we ...
Date: March 19, 2007
Creator: Timothy Donohue, PI
Partner: UNT Libraries Government Documents Department

Biochemistry of Dissimilatory Sulfur Oxidation

Description: The long term goals of this research were to define the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during the dissimilatory oxidation of sulfur practiced by various species of the thiobacilli. Specific adhesion of the thiobacilli to elemental sulfur was studied by electrical impedance, dynamic light scattering, laser Doppler velocimetry, and optical trapping methods. The conclusion is that the thiobacilli appear to express specific receptors that enable the bacteria to recognize and adhere to insoluble sulfur. The enzyme tetrathionate oxidase was purified from two species of the thiobacilli. Extensive structural and functional studies were conducted on adenosine 5'-phosphosulfate reductase purified from cell-free extracts of Thiobacillus denitrificans. The kinetic mechanism of rhodanese was studied.
Date: May 30, 2003
Creator: Blake II, R.
Partner: UNT Libraries Government Documents Department

Hydride transfer made easy in the oxidation of alcohols catalyzed by choline oxidase

Description: Choline oxidase (E.C. catalyzes the two-step, four-electron oxidation of choline to glycine betaine with betaine aldehyde as enzyme-associated intermediate and molecular oxygen as final electron acceptor (Scheme 1). The gem-diol, hydrated species of the aldehyde intermediate of the reaction acts as substrate for aldehyde oxidation, suggesting that the enzyme may use similar strategies for the oxidation of the alcohol substrate and aldehyde intermediate. The determination of the chemical mechanism for alcohol oxidation has emerged from biochemical, mechanistic, mutagenetic, and structural studies. As illustrated in the mechanism of Scheme 2, the alcohol substrate is initially activated in the active site of the enzyme by removal of the hydroxyl proton. The resulting alkoxide intermediate is then stabilized in the enzyme-substrate complex via electrostatic interactions with active site amino acid residues. Alcohol oxidation then occurs quantum mechanically via the transfer of the hydride ion from the activated substrate to the N(5) flavin locus. An essential requisite for this mechanism of alcohol oxidation is the high degree of preorganization of the activated enzyme-substrate complex, which is achieved through an internal equilibrium of the Michaelis complex occurring prior to, and independently from, the subsequent hydride transfer reaction. The experimental evidence that support the mechanism for alcohol oxidation shown in Scheme 2 is briefly summarized in the Results and Discussion section.
Date: June 8, 2008
Creator: Gadda, G.; Orville, A.; Pennati, A.; Francis, K.; Quaye, O.; Yuan, H. et al.
Partner: UNT Libraries Government Documents Department

Gene by Disease Interaction on Orbitofrontal Gray Matter in Cocaine Addiction

Description: Chronic cocaine use has been associated with structural deficits in brain regions having dopamine receptive neurons. However, the concomitant use of other drugs and common genetic variability in monoamine regulation present additional structural variability. We therefore examined variations in gray matter volume (GMV) as a function of lifetime drug use and the monoamine oxidase A (MAOA) genotype in cocaine use disorders (CUD) and healthy controls.
Date: December 5, 2010
Creator: Alia-Klein, N.; Alia-Klein, N.; Parvaz, M.A.; Woicik, P.A.; Konova, A.; Maloney, T. et al.
Partner: UNT Libraries Government Documents Department

Characterization of Laccase-like Multicopper Oxidases (LMCOs) in Arabidopsis thaliana

Description: Laccase-like multicopper oxidases (LMCOs) have repeatedly been associated with the process of lignification in plants, and previous work suggested that these enzymes might be acting as specific marker for highly localized, small-scale lignification events in tissues not typically thought of as lignified. However, plant LMCOs typically occur as members of gene families and different family members can display disparate enzyme activities and overlapping patterns of expression in bulk tissues. This study used reporter genes and knockout mutants to document the involvement of a specific Arabidopsis thaliana LMCO family member (At2g30210 ) in early root development, specifically with development of endodermal tissues. Expression of the gene product was found to be under the control of sucrose levels, but the gene also responded to fluctuations in salt concentrations. The expression patterns of this gene were consistent with its involvement in the formation of suberin in the Casparian strip of root endodermis. An additional LMCO (At5g58910) displayed a more generalized expression in the radicles emergent seedlings. Additional members of the Arabidopsis LMCO family (At2g29130, At5g01190, and At5g05390) were also investigated with reporter gene constructs and knockout mutants. Expression of these LMCOs was associated with lignifying xylem, and the genes had over-lapping expression. Single knockout mutants did not display obvious phenotypes, suggesting that the gene products might have degenerate functionality that could compensate for loss of a single LMCO function.
Date: June 9, 2008
Creator: Dean, Jeffrey F.D.
Partner: UNT Libraries Government Documents Department

Structure and Biochemestry of Laccases from the Lignin-Degrading Basidiomycete, Ganoderma lucidum

Description: G. lucidum is one of the most important and widely distributed ligninolytic white rot fungi from habitats such as forest soils, agricultural soils, and tropical mangrove ecosystems and produce laccases as an important family of lignin modifying enzymes. Biochemically, laccases are blue multi copper oxidases that couple four electron reduction of molecular oxygen to water. There is a growing interest in the use of laccases for a variety of industrial applications such as bio-pulping and biobleaching as well as in their ability to detoxify a wide variety of toxic environmental pollutants. These key oxidative enzymes are found in all the three domains of life: Eukaryota. Prokarya, and Archaea. Ganoderma lucidum (strain no.103561) produces laccase with some of the highest activity (17,000 micro katals per mg of protein) reported for any laccases to date. Our results showed that this organism produces at least 11 different isoforms of laccase based on variation in mol. weight and/or PI. Our Studies showed that the presence of copper in the medium yields 15- to 20-fold greater levels of enzyme by G. lucidum. Dialysation of extra cellular fluid of G. lucidum against 10mM sodium tartrate (pH5.5) gave an additional 15 to 17 fold stimulation of activity with an observed specific activity of 17,000 {micro}katals/mg protein. Dialysis against acetate buffer gave five fold increase in activity while dialysis against glycine showed inhibition of activity. Purification by FPLC and preparative gel electrophoresis gave purified fractions that resolved into eleven isoforms as separated by isoelectric focusing, and the PI,s were 4.7, 4.6, 4.5, 4.3, 4.2, 4.1, 3.8, 3.7, 3.5, 3.4 and 3.3. Genomic clones of laccase were isolated using G. lucidum DNA as a template and using inverse PCR and forward/reverse primers corresponding to the sequences of the conserved copper binding region in the N-terminal domain of one of ...
Date: June 30, 2005
Creator: C.A.Reddy, PI
Partner: UNT Libraries Government Documents Department

Organic light emitting diodes (OLEDS) and OLED-based structurally integrated optical sensors

Description: General introduction to OLED basics and OLED-based structurally integrated sensors was provided in chapter 1 and chapter 2. As discussed in chapter 3, OLEDs were developed or improved using novel engineering methods for better charge injection (increased by over 1 order of magnitude) and efficiency. As the excitation sources, these OLEDs have preferred characteristics for sensor applications, including narrowed emission, emission at desired wavelength, and enhanced output for reduced EL background, higher absorption and improved device lifetime. In addition to OLEDs with desired performance, sensor integration requires oxidase immobilization with the sensor film for O<sub>2</sub>-based biological and chemical sensing. Nanoparticles such as ZnO have large surface area and high isoelectric point (~9.5), which favors enzyme immobilization via physical adsorption as well as Coulombic bonding. In chapter 4, it was demonstrated that ZnO could be used for this purpose, although future work is needed to further bond the ZnO to the sensor film. In chapter 5, single unit sensor was extended to multianalyte parallel sensing based on an OLED platform, which is compact and integrated with silicon photodiodes and electronics. Lactate and glucose were simultaneously monitored with a low limit of detection 0.02 mM, fast response time (~1 minute) and dynamic range from 0-8.6 ppm of dissolved oxygen. As discovered in previous work, the dynamic range covers 0-100% gas phase O<sub>2</sub> or 0-40 ppm dissolved oxygen at room temperature. PL decay curve, which is used to extract the decay time, is usually not a simple exponential at high O<sub>2</sub> concentration, which indicates that O<sub>2</sub> is not equally accessible for different luminescent sites. This creates a challenge for data analysis, which however was successfully processed by stretched exponential as shown in chapter 6. This also provides an insight about the distribution of O<sub>2</sub>:dye collisional quenching rate due to microheterogeneity. Effect of TiO<sub>2</sub> ...
Date: January 1, 2010
Creator: Cai, Yuankun
Partner: UNT Libraries Government Documents Department

Structurally Integrated Photoluminescence-Based Lactate Sensor Using Organic Light Emitting Devices (OLEDs) as the Light Source

Description: Multianalyte bio(chemical) sensors are extensively researched for monitoring analytes in complex systems, such as blood serum. As a step towards developing such multianalyte sensors, we studied a novel, structurally integrated, organic light emitting device (OLED)-based sensing platform for detection of lactate. Lactate biosensors have attracted numerous research efforts, due to their wide applications in clinical diagnosis, athletic training and food industry. The OLED-based sensor is based on monitoring the oxidation reaction of lactate, which is catalyzed by the lactate oxidase (LOX) enzyme. The sensing component is based on an oxygen-sensitive dye, Platinum octaethyl porphyrin (PtOEP), whose photoluminescence (PL) lifetime {tau} decreases as the oxygen level increases. The PtOEP dye was embedded in a thin film polystyrene (PS) matrix; the LOX was dissolved in solution or immobilized in a sol-gel matrix. {tau} was measured as a function of the lactate concentration; as the lactate concentration increases, {tau} increases due to increased oxygen consumption. The sensors performance is discussed in terms of the detection sensitivity, dynamic range, and response time. A response time of {approx}32 sec was achieved when the LOX was dissolved in solution and kept in a closed cell. Steps towards development of a multianalyte sensor array using an array of individually addressable OLED pixels were also presented.
Date: August 9, 2006
Creator: Qian, Chengliang
Partner: UNT Libraries Government Documents Department

''Aged'' (dense) circulating red cells contain normal concentrations of ATP

Description: A newly-developed technique for determination of the ATP content of individual red cells to the densest, and hence presumably the oldest, cells from normal human blood was applied. It was found that these cells contain normal concentrations of ATP, although the net content of ATP is decreased. The essence of the technique is suspension of red cells in autologous plasma containing luciferin and luciferase, lysis of the cells with a pulse from a laser, and counting of the photoemissions resulting from reaction of the released ATP with the luciferase. These data appear to disprove the otherwise plausible hypothesis of Lichtman that red cells decline exponentially in ATP content as they age, by one of the suggested tests of this hypothesis. The data suggest an alternative hypothesis: red cells maintain an approximately constant concentration of ATP as they age, and red cell destruction is caused by factors other than cellular ATP.
Date: January 1, 1978
Creator: Kirkpatrick, F.H.; Muhs, A.G.; Kostuk, R.K. & Gabel, C.W.
Partner: UNT Libraries Government Documents Department

[Regulation of terpene metabolism]. Annual progress report, March 15, 1991--March 14, 1992

Description: This report describes accomplishments over the past year on understanding of terpene synthesis in mint plants and sage. Specifically reported are the fractionation of 4-S-limonene synthetase, the enzyme responsible for the first committed step to monoterpene synthesis, along with isolation of the corresponding RNA and DNA cloning of its gene; the localization of the enzyme within the oil glands, regulation of transcription and translation of the synthetase, the pathway to camphor biosynthesis,a nd studies on the early stages and branch points of the isoprenoid pathway.
Date: December 31, 1992
Creator: Croteau, R.
Partner: UNT Libraries Government Documents Department

Drug metabolizing enzyme systems and their relationship to toxic mechanisms

Description: The metabolism and toxicity of 3-methylfuran (3-MF) are described. The major product of metabolic activation of 3-MF appears to be disemicarbazones. Cursory description of toxic effects of 3-MF on lung and kidneys are provided. 18 refs.
Date: January 1, 1983
Creator: Boyd, M.R.; Ravindranath, V.; Burka, L.T.; Dutcher, J.S.; Franklin, R.B.; Statham, C.N. et al.
Partner: UNT Libraries Government Documents Department

Measurement of adenosine triphosphate (ATP) content in single red blood cells using the firefly bioluminescent reaction

Description: A unique optical instrument is described which uses the firefly bioluminscent reaction to measure adenosine triphosphate (ATP) levels in single red blood cells. The method allows chemical content level to be associated with individual cell features. The optical instrument consists of a phase contrast microscope to view cells, a pulsed argon-ion laser to rupture the cell membrane, and a photon counting system to measure the bioluminescent yield. The technique has been calibrated against a standard ATP measurement using bulk analysis methods. The ATP loss mechanism for blood cells in a controlled depletion experiment was also investigated.
Date: January 1, 1977
Creator: Kostuk, R.K.; Muhs, A.G.; Kirkpatrick, F.H. & Gabel, C.W.
Partner: UNT Libraries Government Documents Department

Alterations in the metabolism of benzo(a)pyrene in syrian hamster embryo (SHE) cells pretreated with phenolic antioxidants

Description: Inhibition of chemical- or raddiation-induced neoplasia has been observed in animals whose diets were supplemented with antioxidants commonly used as food additives. Inhibition of the carcinogenicity of benzo(a)pyrene (BaP) or of 7,12-dimenthylbenz(a)anthracene (DMBA) - in rats has been achieved by the addition of the phenolic antioxidants butylated hydroxyanisole (BHA) or butylated hydroxytoluene (BHT) to the diet. Our data suggest that in SHE cells antioxidants inhibit the overall metabolism of BaP to its various oxidized moieties including 7,8-diol- and 7,8,9,10-tetrol-BaP. A plausible explanation for our results with SHE cells is that the antioxidants interact directly with AHH, thus inhibiting AHH metabolic capacity. From analysis of nuclear material from SHE cells (+- antioxidants) incubated for 36 hours with BaP at 1 ..mu..g/ml, it is calculated that 4.6, 2.4 and 2.9 pmol BaP are bound to the DNA isolated from 10/sup 7/ nuclei of control, BHA-(20 ..mu..g/ml) and p-MP-(10 ..mu..g/ml) treated cultures, respectively.
Date: January 1, 1983
Creator: Strniste, G.F.; Okinaka, R.T. & Chen, D.J.
Partner: UNT Libraries Government Documents Department

[Regulation of terpene metabolism]

Description: This report describes accomplishments over the past year on understanding of terpene synthesis in mint plants and sage. Specifically reported are the fractionation of 4-S-limonene synthetase, the enzyme responsible for the first committed step to monoterpene synthesis, along with isolation of the corresponding RNA and DNA cloning of its gene; the localization of the enzyme within the oil glands, regulation of transcription and translation of the synthetase, the pathway to camphor biosynthesis,a nd studies on the early stages and branch points of the isoprenoid pathway.
Date: January 1, 1992
Creator: Croteau, R.
Partner: UNT Libraries Government Documents Department