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At least 19 recordsLinked to original sources
PubMed1989

Combined supercritical-fluid chromatography/mass spectrometry in the analysis of diuron in plasma using on-line phase-system switching.

On-line sample pretreatment by means of the phase-system switching approach is an interesting technique for the analysis of aqueous samples, e.g., plasma, by means of supercritical-fluid chromatography. In order to analyse plasma samples the following analytical procedure is used. The plasma sample is injected on to a short precolumn, which is washed with water and subsequently dried with nitrogen. Next, the solutes are desorbed with the supercritical mobile phase, analysed with packed-column supercritical-fluid chromatography and detected with either a UV detector or a mass spectrometer, equipped with a moving-belt interface. The herbicide diuron is selected as a test compound to study the feasibility of this approach. Using a selective detector the procedure is sufficiently sensitive to detect diuron in plasma, but not appropriate to detect the diuron metabolites in a post-mortem plasma sample. These have been identified with liquid chromatography/mass spectrometry. The detection limit of diuron in plasma using the procedure described is about 30 ng/mL.

Chromatography, High Pressure Liquid↗
PubMed1986

DNA sequence analysis of diuron-resistant mutations in the mitochondrial cytochrome b gene of Saccharomyces cerevisiae.

Diuron (3-[3,4-dichlorophenyl]-1,1-dimethylurea), an inhibitor of mitochondrial respiration, blocks the yeast respiratory chain between cytochrome b and c1. Diuron-resistant mutants of Saccharomyces cerevisiae have been selected and several mutations localized to the mitochondrial cytochrome b gene. The present paper identifies specific DNA base changes within the cytochrome b gene conferring diuron-resistance. DNA sequence analysis was done utilizing primer extension of crude mitochondrial RNA preparations in the presence of reverse transcriptase. Five independent diuron-resistant mutations have been sequenced.

Amino Acid Sequence↗
PubMed1981

The rapidly metabolized 32,000-dalton polypeptide of the chloroplast is the "proteinaceous shield" regulating photosystem II electron transport and mediating diuron herbicide sensitivity.

Mild trypsin treatment of Spirodela oligorrhiza thylakoid membranes leads to partial digestion of the rapidly metabolized, surface-exposed, 32,000-dalton protein. Under these conditions, photoreduction of ferricyanide becomes insensitive to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], an inhibitor of photosystem II electron transport. Preincubation of thylakoids with diuron leads to a conformational change in the 32,000-dalton protein, modifying its trypsin digestion and preventing expression of diuron insensitivity. Finally, light affects the susceptibility of the 32,000-dalton protein to digestion by trypsin. In other experiments, thylakoids specifically depleted in the 32,000-dalton protein were found to be deficient in electron transport at the reducing side of photosystem II but not at the oxidizing side or in photosystem I activities. Thus, the rapidly metabolized 32,000-dalton thylakoid protein in Spirodela chloroplasts fulfills the requirements of the hypothesized "proteinaceous shield" [Renger, G. (1976) Biochim. Biophys. Acta 440, 287-300] regulating electron flow through photosystem II and mediating diuron sensitivity.

Chloroplasts↗
PubMed1989

Increased diuron resistance in the joint expression of mutations located at the DIU2, DIU3 and DIU4 loci of Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, diuron blocks the respiratory pathway at the level of the bc1 complex. Two mitochondrially inherited loci, DIU1 and DIU2, located in the cytochrome b gene, and two nuclearly inherited loci, DIU3 and DIU4, have previously been identified. The present work genetically characterizes two double mutants. One mutant, Diu-217, carries two nuclearly inherited mutations, diu3-217a and diu-217b; the second mutant, Diu-783, carries the previously described nuclear mutation diu3-783 and a mitochondrial mutation diu2-783. Each mutation, independent of its location, exhibits a weak diuron resistance. The joint expression of two or three mutations leads to a cumulative or a cooperative enhanced diuron-resistant phenotype.

Alleles↗
PubMed1982

Aerobic degradation of diuron by aquatic microorganisms.

Degradation of diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl-urea] by microorganisms obtained from pond water and sediment was determined under aerobic conditions. Enrichment procedures were used to isolate cultures capable of degrading the herbicide. Several mixed fungal/bacterial and mixed bacterial cultures were isolated that could degrade diuron. The mixed cultures degraded 67-99% of the added diuron forming from six to seven products which were separated via TLC. The major degradation product detected in most culture extracts was 3,4-dichloroanaline. Other identified products formed were 3-(3,4-dichlorophenyl)-1-methyl-urea and 3-(3,4-dichlorophenyl)urea.

Aerobiosis↗
PubMed1989

Nuclearly inherited diuron-resistant mutations conferring a deficiency in the NADH--or succinate--ubiquinone oxidoreductase activity in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, diuron, antimycin and myxothiazol block the respiratory pathway at the bc1 complex level. Nuclearly inherited mutations located at the DIU3 and DIU4 loci confer in vitro resistance to diuron and cross-resistance to antimycin and myxothiazol at the NADH oxidase level. The mutant strains do not exhibit diuron resistance at the quinol-cytochrome-c oxidoreductase level. Thus, the apparent resistance does not seem to be the result of a modification of the inhibitory sites. Instead, the quinone reduction rate was found to be altered in the mutant. The diu3 mutations lead to a deficiency of the NADH--ubiquinone oxidoreductase activity, and the diu4 mutations to a deficiency of the succinate--ubiquinone oxidoreductase activity. On the basis of the model of Kröger and Klingenberg, a decrease of quinone reduction could explain the resistance to the bc1 complex inhibitors. Thus, the apparent resistance to the bc1 complex inhibitors was found to be due to a modification of the electron transfer kinetics.

Antimycin A↗
PubMedDate not supplied

Levels of 3,3',4,4'-tetrachloroazobenzene in diuron and linuron herbicide formulations.

Levels of 3,3',4,4'-tetrachloroazobenzene (TCAB) were determined by capillary gas chromatography (GC) with electron-capture detection (ECD) in 25 samples of diuron and linuron formulations obtained from the Canadian market. Acidic aqueous methanol was used to retain urea herbicide and the neutral TCAB was allowed to partition into hexane. Silica gel was used for cleanup of the hexane extract, followed by GC/ECD determination. Recovery data obtained at 4 different spiking levels (i.e., 0.3, 0.1, 1.0, and 5.0 ppm) in linuron averaged 93, 86, 85, and 97%, respectively. For diuron, spiking was done at 0.5, 1.0, and 5.0 ppm levels and the corresponding average percent recoveries were 95, 101, and 104. The TCAB contamination level observed in diuron on a 100% active ingredient basis ranged from 0.15 to 3.38 ppm, whereas in linuron, it varied from 0.91 to 10.28 ppm.

Azo Compounds↗
PubMed1988

Molecular basis for resistance to antimycin and diuron, Q-cycle inhibitors acting at the Qi site in the mitochondrial ubiquinol-cytochrome c reductase in Saccharomyces cerevisiae.

The bc1 complex of the mitochondrial respiratory chain transfers electrons from ubiquinol to cytochrome c oxidase. Cytochrome b, a transmembranous protein, is thought to form a transmembrane electron circuit, transferring electrons between two ubiquinone redox sites, (Qi) and (Qo), respectively, near the inner and outer sides of the inner mitochondrial membrane. Antimycin and diuron appear to block cytochrome b oxidation-reduction at one ubiquinone site, presumably Qi. The cytochrome b gene is carried by the organelle DNA. Yeast mutants resistant to antimycin and diuron have been previously isolated and mapped to specific loci of the cytochrome b gene. In the present work the mutated amino acid residues from nine antimycin- and three diuron-resistant mutants have been identified by sequencing the relevant segments of the resistant cytochrome b gene. The sequencings were performed by primer extension in the presence of dideoxynucleotides on total mitochondrial RNA preparations using reverse transcriptase. Regions of the cytochrome b protein affecting the inhibitor and putative quinone-binding sites have been defined.

Amino Acid Sequence↗
PubMed1978

Bromacil and diuron residue levels in Florida citrus soils.

The widespread use of herbicides in Florida citrus groves raises the possibility of residue accumulation following repeated applications. To determine residue levels of commonly used herbicides, soil samples were taken from large experimental plots in commercial groves in Polk and Hardee Counties. Bromacil and diuron had been applied in combination at both locations for 7-8 years. Analyses of samples showed low levels of both herbicides at various soil depths to 60 cm. Only a small amount of bromacil was detectable one year after applications, but diuron levels were higher. Continuous applications at recommended rates and frequencies have resulted in maximum bromacil and diuron levels of 3.9 percent and 13.1 percent, respectively, of their total application.

Bromouracil↗
PubMed1989

Two nuclearly inherited loci conferring increased diuron resistance to NADH oxidase in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, diuron blocks the respiration pathway at the level of the bc1 complex. Nuclear diuron-resistant mutations which confer in vitro resistance to mitochondrial NADH oxidase have been identified. Five mutations were found to be clustered at two distinct nuclear loci DIU3 and DIU4. The distance between the two loci was estimated to be about 36.7 cM. These loci do not appear to be centromere-linked and did not show a linkage to any of the genes coding for bc1 complex subunits. DIU3 and DIU4 loci might, therefore code for other components of the respiratory chain.

Alleles↗
PubMed1988

Two changes of the same nucleotide confer resistance to diuron and antimycin in the mitochondrial cytochrome b gene of Schizosaccharomyces pombe.

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and antimycin, both inhibitors of mitochondrial respiration, block electron flow between cytochromes b and c1. Mutants resistant to either drug have been selected using Schizosaccharomyces pombe strains with an extrachromosomally inherited mutator. In analogy to Saccharomyces cerevisiae these mutational sites were assumed to map in the cytochrome b gene. DNA sequence analysis showed that two changes in the same nucleotide are responsible for resistance to antimycin and diuron. Analysis of resistant and sensitive progeny of crosses between the mutants and the wild type confirmed the correlation between mutational alteration and resistant phenotype.

Amino Acid Sequence↗
PubMed1989

Tumour initiatory activity of a herbicide diuron on mouse skin.

In the present investigation, the tumour initiating activity of a herbicide diuron 3-(3,4 dichlorophenyl)-1,1 dimethyl urea has been observed following multiple topical applications at a dose of 250 mg/kg body weight in a standard two-stage initiation-promotion protocol on mouse skin for carcinogenicity testing. It was found that 9 applications of the herbicide given on the interscapular region in a thrice weekly schedule up to 3 weeks and followed, after 1 week, by the repeated 3 times per week application of a known skin tumour promoter 12-O-tetradecanoyl phorbol 13-acetate (TPA), 5 micrograms dissolved in 100 microliters of acetone in the same initiated area, led to the development of benign skin tumours. However, a single dose of diuron, used for each application as above and followed by repeated TPA applications, with the same dose and painting schedule as in the case of multiple applications, failed to initiate tumour development.

Animals↗
PubMed1979

Genetic localization of diuron- and mucidin-resistant mutants relative to a group of loci of the mitochondrial DNA controlling coenzyme QH2-cytochrome c reductase in Saccharomyces cerevisiae.

Diuron-resistance, DIU (Colson et al., 1977), antimycin-resistance, ANA (Michaelis, 1976; Burger et al., 1976), funiculosin-resistance, FUN (Pratje and Michaelis, 1977; Burger et al., 1977) and mucidin-resistance, MUC (Subik et al., 1977) are each coded by a pair of genetic loci on the mit DNA of S. cerevisiae. In the present paper, these respiratiory-competent, drug-resistant loci are localized relative to respiratory-deficient BOX mutants deficient in coenzyme QH2-cytochrome c reductase (Kotylak and Slonimski, 1976, 1977) using deletion and recombination mapping. Three drug-resistant loci possessing distinct mutated allelic forms are distinguished. DIU1 is allelic or closely linked to ANA2, FUN1 and BOX1; DIU2 is allelic or closely linked to ANA1, MUC1 and BOX4/5; MUC2 is allelic to BOX6. The high recombinant frequencies observed between the three loci (13% on the average for 33 various combinations analyzed) suggest the existence of either three genes coding for three distinct polypeptides or of a single gene coding for a single polypeptide but subdivided into three easily separable segments. The resistance of the respiratory-chain observed in vitro in the drug-resistant mutants and the allelism relationships between respiratory-competent, drug-resistant loci and coQH2-cyt c reductase deficient, BOX, loci strongly suggest that each of the three drug-resistant loci codes for a structural gene-product which is essential for the normal coQH2-cyt c reductase activity and is obviously a good candidate for a gene product of the drug-resistant loci mapped in this paper. Polypeptide length modifications of cytochrome b were observed in mutants deficient in the coQH2-cyt c red and localized at the BOX1, BOX4 and BOX6 genetic loci (Claisse et al., 1977, 1978) which are precisely the loci allelic to drug resistant mutants as shown in the present work. Taken together these two sets of data provide a strong evidence in favor of the idea that there exist three non contiguous segments of the mitochondrial DNA sequence which code for a single polypeptide sequence of cytochrome b. In each segment mutations which modify the polypeptide sequence can occur leading to the loss (BOX mutants) or to a modification (drug resistant mutants) of the enzyme activity.

Antifungal Agents↗
PubMed1977

Induction of hepatic microsomal enzymes by diuron, phenobenzuron, and metabolites in rats.

Microsomal liver enzymes are induced in rats which are fed a diet containing 1000 ppm of phenobenzuron, a phenylurea herbicide, for 7 days: All parameters measured are about 50% higher than control values. This increase is lower after 14 feeding days. Diuron and 3,4-dichloroaniline have a similar, although lower, effect than phenobenzuron. Two other metabolites have no action on microsomal enzymes. The transitory and weak inducing effect of these phenylureas is interesting when compared to other organochlorine pesticides.

Animals↗
PubMed1984

3,3',4,4'-Tetrachloroazobenzene and 3,3',4,4'-tetrachloroazoxybenzene in technical grade herbicides: propanil, diuron, linuron, and neburon.

The levels of 3,3',4,4'-tetrachloroazobenzene (TCAB) and 3,3',4,4'-tetrachloroazoxybenzene (TCAOB) were determined by gas chromatography-electron capture detection in 20 samples of 3,4-dichloroaniline-derived herbicides. The concentrations of TCAB in technical grade propanil, diuron, linuron, and neburon from a variety of manufacturers ranged from 0.10 to 28.40 mg/kg. No relevant difference was found between the two different herbicide classes analyzed.

Azo Compounds↗
PubMed1990

Dose-related induction of rat hepatic drug-metabolizing enzymes by diuron and chlorotoluron, two substituted phenylurea herbicides.

Dose-related induction of various hepatic drug-metabolizing enzymes has been investigated after short-term treatment of rats by diuron and chlorotoluron, a dichlorinated and a monochlorinated phenylurea herbicide, respectively. Results suggest that 'saturation' of the induction system of benzo(a)pyrene monooxygenase, 7-ethoxycoumarin O-deethylase and 7-ethoxyresorufin O-deethylase activities may occur in the same range of the molar doses of both compounds, and with the dichlorinated herbicide at much higher activities. Induction of epoxide hydrolase, UDP-glucuronyltransferase and glutathione S-transferases also shows saturation curves in the function of molar doses. However, the structural difference is not reflected in the enhancement of enzyme activities.

7-Alkoxycoumarin O-Dealkylase↗
PubMedDate not supplied

Liquid chromatographic determination of the herbicide diuron and its metabolite 3,4-dichloroaniline in asparagus.

A liquid chromatographic method is presented for the determination of the phenylurea herbicide diuron and its major metabolite, 3,4-dichloroaniline in asparagus. The method involves a simple isolation step using dichloromethane extraction, followed by reversed phase chromatography on a C18 column, using a basic aqueous-organic eluent and UV detection at 254 nm. The limit of determination is 0.02 mg/kg for both analytes.

Aniline Compounds↗