In-vitro metabolism of O,O-diethyl S-(N-methylcarbamoylmethyl) phosphorodithioate by mouse liver

The in-vitro metabolism of O,O-diethyl S-(N-methylcarbamoymethyl) phosphorodithioate in mouse liver was studied. The major route of metabolism was via the mixed-function oxidases present in the microsomal fraction, which formed the oxygen analogue, O,O-diethyl hydrogen phosphorothioate and diethyl hydrogen phosphate upon addition of nicotinamide-adenine dinucleotide phosphate (NADPH). In the absence of NADPH, the carboxylic acid analogue (S-carboxymethyl O,O-diethyl phosphorodithioate) was isolated only from the microsomal fraction. Addition of glutathione to the 100 000 g supernatant resulted in no metabolism of the parent compound. However, addition of glutathione to the 10 000 g supernatant resulted in the carboxylic acid formed by amidase activity being further metabolised to O,O-diethyl hydrogen phosphorodithioate by a glutathione-dependent reaction.     

Residues of atrazine, simazine, linuron and diuron after repeated annual applications in a peach orchard

Annual applications of the herbicides atrazine, simazine, linuron and diuron at 45 kg/ha were made to the same plots for 9 consecutive years from 1963 to 1971 in a peach (Prunus persica (L.) Batsch.) orchard located on sandy loam soil near Harrow, Ontario. Soil samples from these plots were collected in late October for the last 3 years (1969–1971) and trees were cut down in December, 1969. Herbicide residues were determined by bioassays based on the fresh and dry weight of oats (Avena sativa L.) and in one year results were confirmed by chemical analysis. Significant accumulation of herbicides was not observed. The maximum residue levels measured in October over the 3 years of sampling were 7′3 kg/ha for diuron, 3–8 kg/ha for linuron, 1–6 kg/ha for simazine and 04 kg/ha for atrazine in the top 15 cm of the soil profile. Simazine and atrazine showed a rapid decrease in amount after treatment but diuron and linuron were degraded more slowly. Measurable residues of all herbicides were confined to the upper 15 cm of the soil profile and the majority of herbicide remained in the 0–5-cm soil layer. Oats were planted in the orchard plots from 1972 to 1974 to follow the disappearance of the herbicides. All herbicides caused highly significant yield decreases in 1972, atrazine causing the least (38%) and diuron the greatest (86%) reductions. Diuron reduced the yield of oats in 1973 and caused a highly significant decrease in the weight of young oat plants in 1974.     

Metabolism of the herbicides chlorotoluron, diuron, linuron, simazine, and atrazine by CYP1A9 and CYP1C1 from Japanese eel (Anguilla japonica)

Through the use of a number of bioconversion experiments we demonstrated that P450 proteins (CYP1A9 and CYP1C1) from Japanese eel (Anguilla japonica) metabolized a number of herbicides and the drug phenacetin. We performed bioconversion experiments in which substrates were added directly to incubation medium. The resulting metabolites were extracted and analyzed by high-performance liquid chromatography. Proteins CYP1A9 and CYP1C1 metabolized 50 nmol of the drug phenacetin to yield 12.1 and 1.1 nmol of product (acetaminophen), respectively. Further incubation of CYP1A9 with 50 nmol of the herbicides chlorotoluron, diuron, linuron, simazine, or atrazine yielded 16.5, 18.5, 7.3, 1.6, or 0.8 nmol of product, respectively. CYP1C1 also metabolized linuron, diuron, and simazine yield 5.4, 4.6, or 0.7 nmol of product, respectively. Next, polyclonal antibody was isolated by immunizing with two conjugated-peptides (amino acid residues 272–290 and 294–310) of CYP1A9. This antibody did not recognize human CYP1A2 or CYP1C1. Western blotting using the antibody revealed one band in the livers of Japanese eel and tilapia (Oreochromis niloticus). Theses results suggest that CYP1A9 and CYP1C1 metabolize herbicides, and that CYP1A9 is an useful biomarker of contamination when detected with this antibody.     

硝磺·莠去津550克/升悬浮剂高效液相色谱分析方法研究

本文采用高效液相色谱法,以乙腈＋0.05%H3PO4为流动相,使用ZORBAX80魡Extend-C18色谱柱和二极管阵列检测器,在222nm波长下对硝磺草酮和莠去津进行同柱分离和定量分析。结果表明,该方法测得硝磺草酮、莠去津的线性相关系数为1.0000、0.9998;标准偏差为0.05、0.14;变异系数为1.05%、0.30%;平均回收率为99.8%、100.0%。     

Leaching of atrazine and hexazinone from Abies nordmanniana (Steven) spach plantations

The content of the herbicides atrazine and hexazinone was measured in drainage water from seven to ten-year-old plantations grown with Abies nordmanniana (Steven) Spach on two clayey soils in Denmark. The concentrations of atrazine varied between 0.06 and 7.79 μg litre^?1. The concentrations of hexazinone were different at the two locations, ranging from 0.07 to 2.09 μg litre^?1 at Bremersvold and from 3.47 to 42.66 μg litre^?1 at Koege. Metabolites of both herbicides were identified.     

Metabolic aspects of the toxicology of diazinon. I. Hepatic metabolism in the sheep,cow, pig,guinea-pig,rat, turkey,chicken and duck

The phosphorothionate insecticide diazinon was incubated with liver microsomes from the sheep, cow, pig, guinea-pig, rat, turkey, chicken and duck. Metabolism by liver slices of most of these species was also examined. Hydroxydiazinon, isohydroxydiazinon, dehydrodiazinon, their oxons and diazoxon were identified and determined quantitatively or semi-quantitatively. An eighth metabolite was tentatively identified as the 6-aldehyde analogue of diazinon. Yields and rates of production of these metabolites varied greatly between species. Production of oxons was not generally correlated with susceptibility to diazinon poisoning, although it was lowest in the least susceptible animal, the sheep. The degradation of oxons by liver slices was too slow to explain the low toxicity of diazinon to the mammals. The relative importance of hepatic and extrahepatic metabolism in determining toxicity to vertebrates is discussed.     

Animal metabolism of propham (isopropyl carbanilate): The fate of residues in alfalfa when consumed by the rat and sheep

Alfalfa was root-treated with [¹⁴C]propham (isopropyl carbanilate[¹⁴C-phenyl(U)]) for 7 days and then harvested and freeze-dried. Rats and sheep were orally given either ¹⁴C-labeled alfalfa roots ([¹⁴C]root) or ¹⁴C-labeled alfalfa shoots ([¹⁴C]shoot). When the [¹⁴C]root was given, 6.5–11.0% of the ¹⁴C was excreted in the urine and 84.6–89.4% was excreted in the feces within 96 h after treatment. Less than 3% of the ¹⁴C remained in the carcass (total body—gastrointestinal tract and contents) 96 h after treatment. When [¹⁴C]shoot was given, 53.2–55.2% of the ¹⁴C was excreted in the urine, 32.1–43.4% was excreted in the feces, and the carcass contained 0.2–1.1% of the ¹⁴C 96 h after treatment. When the insoluble fraction (not extracted by a mixture of CHCl₃, CH₃OH, and H₂O) of both alfalfa roots and shoots was fed to rats, more than 86% of the ¹⁴C was excreted in the feces and less than 3% remained in the carcass 96 h after treatment. The major radiolabeled metabolites in the urine of the sheep fed ¹⁴C shoot were purified by chromatography and identified as the sulfate ester and the glucuronic acid conjugates of isopropyl 4-hydroxycarbanilate. Metabolites in the urine of the sheep treated with [¹⁴C]root were tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline. The combined urine of rats dosed with [¹⁴C]shoot and [¹⁴C]root contained metabolites tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline.     

Ecdysone metabolism by soluble enzymes from three species of diptera and its inhibition by the insect growth regulator TH-6040

Homogenates of larvae, pupae, and adults of house flies (Musca domestica L.), flesh flies (Sarcophaga bullata Parker), and blow flies (Phormia regina (Meigen)) have been examined for enzymes which convert α- and β-ecdysone to apolar products. Most of the activity was found in the soluble fraction from house flies and flesh flies but none of the blow fly fractions was active. Two enzymes seem to be involved in the ecdysone metabolism, one requiring NADPH and the other functioning without this cofactor. The product of the latter enzyme is thought to be the 3-dehydro-ecdysone. This product is further converted to the 3α-hydroxy isomer of ecdysone by the NADPH-requiring enzyme. On feeding the insect growth regulator TH-6040 (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea) to larvae at dietary levels ranging from 0.3 to 10 ppm, the activity of the enzyme producing the 3-dehydro product is reduced by 20 to 82%. It is suggested that the growth regulator exerts its effect on pupal-adult ecdysis through its inhibition of ecdysone metabolism.     

Improved control of clubroot (Plasmodiophora brassicae) by a mixture of a fungicide and a plant defense inducer

Journal of Plant Diseases and Protection - The mixtures of 10 % cyazofamid SC and 25 % methiadinil SC were selected at different concentrations in root irrigation treatment of...     

Longevity of a mixture of acetamiprid and bifenthrin (Transport(TM) ) at the termiticidal application rate

BACKGROUND: The 30 month longevity, mobility and insecticidal activity of a combination of acetamiprid and bifenthrin currently marketed in the United States for the prevention of termite infestation in buildings was investigated in greenhouse and laboratory studies. RESULTS: Acetamiprid dissipated to below the limit of detection within 7 months of application, while bifenthrin remained in the soil at levels sufficient to kill termites for the duration of the study. Acetamiprid was detected in decreasing amounts in eluates of treated soil from months 1 to 4, while no bifenthrin was detected in eluates at any time. The treated soil remained toxic to termites for the 30 month duration of the study. Two indices of synergy between technical‐grade acetamiprid and bifenthrin demonstrated that it is unlikely that there would be any synergism between the two active ingredients in the field. The presence of vegetation did not have a significant effect on the longevity of bifenthrin, except at intermediate times, where residues in the treated soil were higher in vegetated plots, depending on depth and time. CONCLUSIONS: Acetamiprid has a short residual time in soil, and this formulation's effectiveness beyond about 7 months against subterranean termites is due to the bifenthrin content. Copyright © 2011 Society of Chemical Industry     

Test of the Root Zone Water Quality Model (RZWQM) for predicting runoff of atrazine, alachlor and fenamiphos species from conventional-tillage corn mesoplots

The Root Zone Water Quality Model (RZWQM) is a comprehensive, integrated physical, biological and chemical process model that simulates plant growth and movement of water, nutrients and pesticides in a representative area of an agricultural system. We tested the ability of RZWQM to predict surface runoff losses of atrazine, alachlor, fenamiphos and two fenamiphos oxidative degradates against results from a 2-year mesoplot rainfall simulation experiment. Model inputs included site-specific soil properties and weather, but default values were used for most other parameters, including pesticide properties. No attempts were made to calibrate the model except for soil crust/seal hydraulic conductivity and an adjustment of pesticide persistence in near-surface soil. Approximately 2.5 (+/- 0.9), 3.0 (+/- 0.8) and 0.3 (+/- 0.2)% of the applied alachlor, atrazine and fenamiphos were lost in surface water runoff, respectively. Runoff losses in the 'critical' events--those occurring 24 h after pesticide application--were respectively 91 (+/- 5), 86 (+/- 6) and 96 (+/- 3)% of total runoff losses for these pesticides. RZWQM adequately predicted runoff water volumes, giving a predicted/observed ratio of 1.2 (+/- 0.5) for all events. Predicted pesticide concentrations and loads from the 'critical' events were generally within a factor of 2, but atrazine losses from these events were underestimated, which was probably a formulation effect, and fenamiphos losses were overestimated due to rapid oxidation. The ratios of predicted to measured pesticide concentrations in all runoff events varied between 0.2 and 147, with an average of 7. Large over-predictions of pesticide runoff occurred in runoff events later in the season when both loads and concentrations were small. The normalized root mean square error for pesticide runoff concentration predictions varied between 42 and 122%, with an average of 84%. Pesticide runoff loads were predicted with a similar accuracy. These results indicate that the soil-water mixing model used in RZWQM is a robust predictor of pesticide entrainment and runoff.     

Effect of a paired mixture of aldrin and formothion on carbohydrate metabolism in a fish, Heteropneustes fossilis

Exposure of the Indian catfish (Heteropneustes fossilis) to a high sublethal concentration, 0.114 ppm (0.8 of the 96-hr LC₅₀) of a mixture of aldrin and formothion, added in a one-to-one ratio, for 3, 6, 12, 48, and 96 hr affected carbohydrate metabolism. Muscle glycogen decreased significantly at 6 and 48 hr; hepatic glycogen content declined at 3, 6, 12, and 48 hr in exposed fish. Blood glucose levels in fish were significantly decreased at 3, 12, 48, and 96 hr. Mean value of blood pyruvate was significantly depressed at 3 hr. Blood lactate levels were elevated at 3, 6, 12, and 96 hr in pesticide-treated fish. The observed effects of the mixture of aldrin and formothion on carbohydrate metabolism in fish could prove useful as a rapid method for evaluating toxicity of pesticides and other toxicants.     

Degradation of atrazine and isoproturon in the unsaturated zone: a study from Southern England

The potential for degradation of atrazine or isoproturon in the unsaturated zone of two boreholes was studied under laboratory conditions. Intact and uncontaminated samples were obtained from regular depths of 0–16.45 m and 0–9 m using a percussion coring technique. The results showed that the deep unsaturated zone contained micro-organisms capable of degrading atrazine or isoproturon. The rate of degradation was much faster in surface soil than in most unsaturated materials of both boreholes. The amount of atrazine remaining six months after incubation also varied between the two boreholes. A relatively small amount of atrazine was lost from sterilised samples, suggesting a significant role for microbial degradation. The addition of nutrient and energy sources into materials of low degradation capacity did not enhance the degradation of atrazine. Degradation rate was more related to the presence of a competent microbial population rather than to the presence of indigenous organic matter. However, the competent micro-organisms are more likely to be present when the organic matter content is high. The type and activity of these micro-organisms and their physical environment may have considerable influence on atrazine degradation and are likely to be responsible for much of the variation in the rate of degradation observed at different depths. © 1999 Society of Chemical Industry     

Toxicity,penetration, and metabolism of AC 217,300 (AMDRO) in the tobacco budworm (Heliothis virescens) by various methods of application

Penetration was found to be the major factor in the selective toxicity of AC 217,300 in Heliothis virescens larvae. When applied topically in either acetone or dimethyl sulfoxide solutions, less than 3 and 11%, respectively, of the applied dose penetrated the cuticle after 72 hr. Ingestion resulted in tissue residues of 45–55% of the applied dose, and increased toxicity 40 to 140-fold over topical application. Five primary metabolites were tentatively identified by cochromatography with authentic standards. At least 10 other minor metabolites were detected. The lack of insecticidal activity with any of the known metabolites, as well as the tissue residues and metabolic profile, suggested that AC 217,300 is the actual toxicant.     

Cellular and biochemical effects induced by atrazine on blood of male Japanese quail (Coturnix japonica)

Atrazine a potent endocrine disruptor herbicide is broadly used to control rapidly growing unwanted weeds in various cereals crops which induce adverse effects both in mammalian and avian species. In present study 96 mature male Japanese quail (Coturnix japonica) were procured and randomly kept in eight groups (A to H) each having 12 birds. Atrazine was administered orally at 0, 10, 25, 50, 100, 250 and 500 mg/kg body weight to all experimental groups. The mitomycin C at 2 mg/kg body weight was given to the birds of group B which served as a positive control. From each group 4 birds were randomly selected and harvested at day 15, 30 and 45. A significant (P < 0.05) decrease in serum total protein, serum albumin and serum testosterone values were recorded at day 45 in all treated groups. A significant increase in serum ALT and AST concentration was also recorded. Moreover, morphological alterations in nucleus of erythrocytes were also observed including blebbed nuclei, notched nuclei, lobed nuclei, vacuolated cells, binucleated cell, and cell with pear shaped and micronucleus. Overall, our results show that atrazine at higher doses induces significant serum biochemical alterations and changes in nucleus of erythrocytes.     

Peculiarities of behaviour of taiga (Ixodes persulcatus) and sheep (Ixodes ricinus) ticks (Acarina: Ixodidae) determined by different methods

A comparison of the behavioural peculiarities of Ixodes persulcatus Schulze, 1930 (north-western population, Russia) and Ixodes ricinus (L., 1758) from western Russia and Denmark was determined by using two methods. Method 1 involved a sojourn of ticks on vertical plastic sticks and showed that the questing behaviour of I. ricinus nymphs was dependent on temperature and relative humidity (RH). A significantly greater number of nymphs quested at 22 degrees C and 100% RH than at 18 degrees C. When the humidity was reduced to 30% all of the nymphs departed. In the second method, the activity of ticks on an inclined "ticksdrome" was estimated. The activity of I. ricinus adults from the Danish population was 1.2 times greater than that of ticks from Russia. Females of the species studied and specimens from all study areas were more active than all other stages of development. The locomotor activity of both adult and immature I. ricinus that were infected with Borrelia burgdorferi sensu lato was suppressed when compared with uninfected specimens. The locomotor activity of I. persulcatus females infected by borreliae with exoskeleton anomalies was 1.3 times greater (P<0.05) than that of infected ticks without anomalies. Our data showed that infected females with exoskeleton anomalies could crawl faster on a human and reach uncovered parts of the body that are vulnerable for attachment and feeding. A study of locomotor activity and questing behaviour may be useful for comparing the risk for different tick species and populations to transmit tick-borne pathogens.     

Removal of paraquat and atrazine from water by montmorillonite‐(Ce or Zr) phosphate cross‐linked compounds

The adsorption of paraquat (1,1′‐dimethyl‐4,4′‐bipyridilium dichloride) and atrazine (6‐chloro‐N ²‐ethyl‐N ⁴‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) from aqueous solution onto two montmorillonite‐(Ce or Zr) phosphate cross‐linked compounds at different temperatures (288 K and 308 K) has been studied using batch experiments. The adsorption isotherms obtained for paraquat on both adsorbents may be classified as H‐type of the Giles classification, which suggests that paraquat molecules are strongly adsorbed on the samples. For the adsorption of atrazine, L‐type isotherms were obtained for both montmorillonite‐(Ce or Zr) phosphate compounds, which suggests that these compounds have a medium affinity for this herbicide. The increase in temperature from 288 K to 308 K did not have any clear effect on the adsorption process of paraquat on either adsorbent whereas atrazine adsorption decreased slightly as temperature increased, possibly due to a mainly physical process. Fourier transform infrared (FTIR) spectroscopic studies revealed that at the pH generated by the adsorbents, the cationic herbicide interacted to a greater extent with the negatively charged surface of the adsorbents than did atrazine. For both herbicides, the Ce‐montmorillonite adsorbent showed a higher adsorption capacity than the Zr‐montmorillonite adsorbent. © 2000 Society of Chemical Industry     

Cloning and expression of an atrazine inducible cytochrome P450, CYP4G33, from Chironomus tentans (Diptera: Chironomidae)

Previous studies performed in our laboratory have measured the effect of atrazine exposure on cytochrome P450-dependent monooxygenase activity and have found increased activity in midge larvae (Chironomus tentans) as a result of atrazine exposure (1-10 ppm). Here we report the cloning and expression of a specific C. tentans CYP4 gene that is responsive to atrazine induction with an open reading frame of 1678 bp which encodes a putative protein of 559 amino acid residues. Alignments of deduced amino acid sequences with other insect P450 genes and phylogenetic analysis indicated a high degree of similarity to other insect CYP4 genes. Northern blotting analysis employing a fragment of 1200 bp from the CYP4 gene as a probe indicated that the CYP4 gene was expressed in all developmental stages, but was expressed at highest levels in late instar larvae. Additionally, over-expression of CYP4 in C. tentans exposed to atrazine (10 mg/l) confirms the ability of atrazine to induce specific P450 genes and provides insight into potential consequences of atrazine exposure in aquatic organisms.