Data derived extrapolation factors (DDEFs) for rat to human interspecies extrapolation for the HPPD inhibitor mesotrione.

In the risk assessment of agrochemicals, there has been a historical paucity of using data to refine the default adjustment factors, even though large datasets are available to support this. The current state of the science for addressing uncertainty regarding animal to human extrapolation (AFA) is to develop a "data-derived" adjustment factor (DDEF) to quantify such differences, if data are available. Toxicokinetic (TK) and toxicodynamic (TD) differences between species can be utilized for the DDEF, with human datasets being ideal yet rare. We identified a case for a currently registered herbicide, mesotrione, in which human TK and TD are available. This case study outlines an approach for the development of DDEFs using comparative human and animal data and based on an adverse outcome pathway (AOP) for inhibition of 4-hydroxyphenol pyruvate dioxygenase (HHPD). The calculated DDEF for rat to human extrapolation (AFA) for kinetics (AFAK = 2.5) was multiplied by the AFA for dynamics (AFAD = 0.3) resulting in a composite DDEF of ∼1 (AFA = 0.75). This reflects the AOP and available scientific evidence that humans are less sensitive than rats to the effects of HPPD inhibitors. Further analyses were conducted utilizing in vitro datasets from hepatocytes and liver cytosols and extrapolated to whole animal using in vitro to in vivo extrapolation (IVIVE) to support toxicodynamic extrapolation. The in vitro datasets resulted in the same AFAD as derived for in vivo data (AFAD = 0.3). These analyses demonstrate that a majority of the species differences are related to toxicodynamics. Future work with additional in vitro/in vivo datasets for other HPPD inhibitors and cell types will further support this result. This work demonstrates utilization of all available toxicokinetic and toxicodynamic data to replace default uncertainty factors for agrochemical human health risk assessment.

Using RNA-seq to characterize responses to 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor herbicide resistance in waterhemp (Amaranthus tuberculatus).

BACKGROUND: Waterhemp (Amaranthus tuberculatus (Moq.) J.D. Sauer) is a problem weed commonly found in the Midwestern United States that can cause crippling yield losses for both maize (Zea mays L.) and soybean (Glycine max L. Merr). In 2011, 4-hydroxyphenylpyruvate-dioxygenase (HPPD, EC 1.13.11.27) inhibitor herbicide resistance was first reported in two waterhemp populations. Since the discovery of HPPD-herbicide resistance, studies have identified the mechanism of resistance and described the inheritance of the herbicide resistance. However, no studies have examined genome-wide gene expression changes in response to herbicide treatment in herbicide resistant and susceptible waterhemp. RESULTS: We conducted RNA-sequencing (RNA-seq) analyses of two waterhemp populations (HPPD-herbicide resistant and susceptible), from herbicide-treated and mock-treated leaf samples at three, six, twelve, and twenty-four hours after treatment (HAT). We performed a de novo transcriptome assembly using all sample sequences. Following assessments of our assembly, individual samples were mapped to the de novo transcriptome allowing us to identify transcripts specific to a genotype, herbicide treatment, or time point. Our results indicate that the response of HPPD-herbicide resistant and susceptible waterhemp genotypes to HPPD-inhibiting herbicide is rapid, established as soon as 3 hours after herbicide treatment. Further, there was little overlap in gene expression between resistant and susceptible genotypes, highlighting dynamic differences in response to herbicide treatment. In addition, we used stringent analytical methods to identify candidate single nucleotide polymorphisms (SNPs) that distinguish the resistant and susceptible genotypes. CONCLUSIONS: The waterhemp transcriptome, herbicide-responsive genes, and SNPs generated in this study provide valuable tools for future studies by numerous plant science communities. This collection of resources is essential to study and understand herbicide effects on gene expression in resistant and susceptible weeds. Understanding how herbicides impact gene expression could allow us to develop novel approaches for future herbicide development. Additionally, an increased understanding of the prolific traits intrinsic in weed success could lead to crop improvement.

Clethodim exposure induces developmental immunotoxicity and neurobehavioral dysfunction in zebrafish embryos.

Clethodim is one of the most widely used herbicides in agriculture, but its potential negative effects on aquatic organisms are still poorly understood. This study examined the effects of clethodim on zebrafish at aspects of early stage embryonic development, immune toxicity, cell apoptosis and locomotor behavior. Firstly, clethodim exposure markedly decreased the survival rate, body length, and heart rate and resulted in a series of morphological abnormalities, primarily spinal deformities (SD) and yolk sac edema, in zebrafish larvae. Secondly, the number of immune cells was substantially reduced but the levels of apoptosis and oxidative stress were significantly increased in a dose-dependent manner upon clethodim exposure. Thirdly, we evaluated the expression of some key genes in TLR signaling including TLR4, MyD88, and NF-κB p65 and they were all up-regulated by exposure to 300 µg/L clethodim. Meanwhile, some proinflammatory cytokines such as TNF-α, IL-1ß, IL8, and IFN-γ were also activated in both the mock and the TLR4-KD conditions. Moreover, the locomotor behaviors and the enzymatic activities of AChE were obviously inhibited but the levels of acetylated histone H3 were greatly increased by clethodim exposure. In addition, incubation of zebrafish larvae with acetylcholine receptor (AChR) agonist carbachol can partially rescue the clethodim-modulated locomotor behavior. Taken together, our results suggest that clethodim has the potential to induce developmental immunotoxicity and cause behavioral alterations in zebrafish larvae. The information presented in this study will help to elucidate the molecular mechanisms underlying clethodim exposure in aquatic ecosystems.

Design, synthesis and anticonvulsant evaluation of fluorinated benzyl amino enaminones.

Inspite of progress made for the discovery of novel antiepileptic drugs, epilepsy remains an unmet medical need. We synthesized nine trifluoromethylated enaminone derivatives and tested them for their anticonvulsant activity using maximal electroshock seizure (MES) test, subcutaneous pentylenetetrazole (scPTZ) test, and rotorod test for neurotoxicity. Among the compounds tested 3-(4-fluoro-3-(trifluomethyl)benzylamino)-5-(trifluoromethyl)cyclohex-2-enone (4f) showed ED50 of 23.47 mg/kg, when given orally to rats, 3-(4-chlorophenylamino)-5-(trifluoromethyl)cyclohex-2-enone (5a), which was previously reported by us but for which no quantitative data was available at the time, exhibited an ED50 of 62.39 mg/kg. Under the same conditions commercially available carbamazepine showed an ED50 of 28.20 mg/kg. There were no neurotoxicity observed upto a dose of 300 mg/kg for all the tested compounds. Compounds 4f and 5a represent good lead compounds for further development.

Acute and chronic toxicity of herbicides and their mixtures measured by Aliivibrio fischeri ecotoxicological assay.

The purpose of our work was to determine the acute and chronic toxicity of three of the EU's most common herbicides - mesotrione, S-metolachlor, terbuthylazine - and their mixtures by Aliivibrio fischeri ecotoxicological assays. While comparing the sensitivity of the acute (30 min) Microtox® standard assay with the chronic (25 h) test adapted to microtiter plate, joint effects (antagonism, additive effect and synergism) to the bioluminescence inhibition (consequently the metabolic damage) in A. fischeri were also determined by Combination Index (CI) method. 30 min of exposure to mesotrione and S-metolachlor resulted in a relatively low acute toxicity (EC50 values were 118 and 265 mg/L), while terbuthylazine did not cause bioluminescence inhibition at all. Results showed that the chronic toxicity of S-metolachlor and terbuthylazine to A. fischeri (EC5010h = 59.2 and 4.9 mg/L and EC5015h = 54.0 and 9.6 mg/L, respectively) is larger by at least one order of magnitude than that after 30 min of contact time. Considering mesotrione no significant difference was experienced in toxicity. Regarding the EC50 values, all of the mixtures had synergistic joint effects in the acute assay. However, in the chronic test all the mixtures showed antagonistic responses with the exception of mesotrione and S-metolachlor (ratio 1:1) combination, which also had additive and synergistic effects after 10 and 15 h of exposure, similarly to the short-term test. This is also the first report of the joint effects of these herbicides. The chronic test is a more sensitive indicator to the active ingredients; both acute and chronic assays supply valuable data of the toxic properties of the pesticides. Moreover, the short- and long-term joint effects of their mixtures supporting a more accurate and reliable risk assessment.

Assessment of cyclohexanone toxicity in inhalation-exposed F344 rats and B6C3F1 mice: applications in occupational health.

BACKGROUND: Cyclohexanone is a chemical used in various industries and many workers are exposed to it. Therefore, in this study, we determined the toxicity of cyclohexanone in inhalation-exposed F344 rats and B6C3F1 mice, so as to apply the findings in hazard and risk assessments. METHODS: Ten male and 10 female rats and mice per test group were exposed to cyclohexanone vapors at 0, 100, 250, and 625 ppm concentrations for 6 h per day, 5 d per week, and for 13 weeks. All rats and mice were killed after the exposure period. Clinical signs, body weight, feed intake, and ophthalmoscopy findings were recorded during the exposure period, and hematology, blood biochemistry, organ weights, gross findings, and histopathology were evaluated thereafter. RESULTS: The following findings were noted in cyclohexanone-exposed F344 rats: increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, increased liver weight, and bile duct hyperplasia in the males exposed to 250 and 625 ppm cyclohexanone, increased ALT levels and bile duct hyperplasia in the females exposed to 625 ppm cyclohexanone, and increased blood urea nitrogen (BUN) and tubular basophilia in the renal cortex in the males exposed to 625 ppm cyclohexanone. On the other hand, B6C3F1 mice exposed to cyclohexanone showed no obvious exposure-related effects. CONCLUSION: Based on the findings, the no-observed-adverse-effect level (NOAEL) was determined to be 100 ppm in F344 rats and >625 ppm in B6C3F1 mice. Therefore, 2 ppm was revealed as the derived no-effect level (DNEL) for cyclohexanone.

Effects of the herbicide mesotrione on soil enzyme activity and microbial communities.

Mesotrione (2-[4-(methylsulfonyl)-2-nithobenzoyl]-1, 3-cyclohexanedione) is a selective triketone herbicide that has been widely used in corn production for the past 15 years. However, its potential for risk to soil ecosystems is poorly documented. The present study investigated the soil enzyme activity and soil microbial community responses to a 20 days' mesotrione exposure at doses of 0.1, 1.0 and 5.0 mg/kg. On days 2, 5, 10 and 20, activities of soil ß-glucosidase, urease and acid phosphatase, soil microbe abundances, soil microbial community structure and abundance of the AOA-amoA and AOB-amoA genes were measured. Results showed that activities of urease and acid phosphatase were relatively stable, with no difference found between the mesotrione-treated group and control at the end of exposure. But ß-glucosidase activity was reduced in the 5.0 mg/kg mesotrione treatment. In the 1.0 and 5.0 mg/kg mesotrione-treated soil, abundance of bacteria, fungi and actinomycetes all were reduced. In the 0.1 mg/kg mesotrione-treated soil, only fungi abundance was reduced by the end of the exposure. The analysis of terminal restriction fragment length polymorphism (T-RFLP) revealed soil microbial community structure could be affected by mesotrione at all experimental doses, and microbial diversity declined slightly after mesotrione exposure. Abundance of AOA-amoA and AOB-amoA genes were reduced markedly in 1.0 and 5.0 mg/kg mesotrione-treated soil. The present study suggests that mesotrione at higher doses might induce negative impacts on soil microbes, a finding which merits additional research and which should be accounted for when application of this herbicide is considered.

Mesotrione herbicide does not cause genotoxicity, but modulates the genotoxic effects of Atrazine when assessed in mixture using a plant test system (Allium cepa).

Mesotrione (MES) is an herbicide from the triketone family and has been used as an alternative to Atrazine (ATZ), which was banned in some countries due to its toxicity to non-target organisms. Despite being considered an eco-friendly herbicide, data from the literature about the harmful effects of MES in its pure form and/or in combination with other herbicides is still scarce. Aimed at assessing the potential of MES to induce cell death and DNA damage, seeds of Allium cepa (higher plant, monocotyledon) were exposed to this herbicide, pure and in mixture with ATZ, and the number of dividing cells (cytotoxicity), chromosomal aberrations (CA, genotoxicity) and micronuclei (MN, mutagenicity) were then quantified. The pure MES (1.8 to 460 µg/L) did not show either cytotoxicity or genotoxicity/mutagenicity under the tested conditions. The genotoxicity of ATZ (1.5 to 400 µg/L), previous reported in the literature, was confirmed herein. The assessment of MES + ATZ mixtures (1.8 + 1.5; 7 + 6.25; 30 + 25 µg/L, respectively) showed that MES, at low concentrations, enhance the genotoxicity of ATZ (potentiation), since the significant frequencies of CA and MN were greater than the ones expected in additive effects. Taking together, MES in its pure form seems to be a safe alternative to ATZ regarding the capacity to damage (at cellular and DNA levels) non-target plants (Monocots); however, MES in combination with ATZ appeared to act as a co-mutagen at low concentrations.

6-Benzylidene-2-[4-(pyridin-3-ylcarboxy)benzylidene]cyclohexanones: A novel cluster of tumour-selective cytotoxins.

Novel cytotoxins 3-5 containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore are disclosed. The compounds in series 3 and 5 have the potential to liberate niacin which may reduce some of the side effects of antineoplastic compounds. 3a-c emerged as the most potent cytotoxic compounds with IC50 values in the low micromolar range against human Molt4/C8 and CEM CD4+ T-lymphocytes as well as murine L1210 leukemia cells. QSAR studies revealed that cytotoxic potencies were negatively correlated with the magnitude of the Hammett sigma values of the aryl substituents. The compounds 3a-e displayed tumour-selective toxicity against human HL-60, HSC-2, HSC-3 and HSC-4 neoplasms as compared to human HGF, HPC and HPLF nonmalignant cells. A representative potent compound 3a caused PARP1 cleavage and G0/G1 cell cycle arrest in HSC-2 cells. These compounds are well tolerated in mice at doses up to and including 300mg/kg of the compounds and no mortalities were noted after 4h. The stability studies undertaken did not reveal that a representative compound 3a underwent hydrolysis to the related phenol 2a. Some guidelines for further analog development of the novel esters 3 were made.

Ketamine Analog Methoxetamine Induced Inflammation and Dysfunction of Bladder in Rats.

The novel synthetic psychoactive ketamine analog methoxetamine is reportedly being used for recreational purposes. As ketamine use can result in urinary dysfunction, we conducted the present study to investigate how methoxetamine affects the bladder. A cystometry investigation showed that female Sprague-Dawley rats experienced increased micturition frequency bladder dysfunction after receiving a daily intraperitoneal injection of 30 mg/kg methoxetamine or ketamine for periods of 4 or 12 weeks. Histologic examinations of rat bladder tissue revealed damaged urothelium barriers, as well as evidence of inflammatory cell infiltration and matrix deposition. The drug-treated rats showed significantly upregulated levels of pro-inflammatory cytokines such as IL-1ß, IL-6, CCL-2, CXCL-1, CXCL-10, NGF, and COX-2. In addition, interstitial fibrosis was confirmed by increased levels of collagen I, collagen III, fibronectin and TGF-ß. Besides direct toxic effect on human urothelial cells, methoxetaminealso induced the upregulation related cytokines. Our results indicate that long term methoxetamine treatment can induce bladder dysfunction and inflammation in rats. Methoxetamine was confirmed to produce direct toxic and pro-inflammatory effects on human urothelial cells. Methoxetamine-associated bladder impairment may be similar to ketamine-induced cystitis.

Cross-resistance patterns to ACCase-inhibitors in American sloughgrass (Beckmannia syzigachne Steud.) homozygous for specific ACCase mutations.

American sloughgrass is a troublesome annual grass weed in winter wheat field rotated with rice in China. The overreliance on acetyl-coenzyme A carboxylase (ACCase) inhibiting herbicides has resulted in resistance evolution in this weed. In this study, the cross-resistance patterns to fenoxaprop-p-ethyl, clodinafop-propargyl, fluazifop-p-butyl, haloxyfop-p-methyl, sethoxydim, clethodim and pinoxaden were established using purified plants individually homozygous for specific mutant ACCase alleles. Results indicated that 1781Leu allele endows high-level resistance to APPs, CHDs and pinoxaden while confers moderate resistance to haloxyfop-p-methyl. The 2027Cys and 2041Asn alleles endow high-level resistance to APPs and pinoxaden and lower level resistance to CHDs. The 2078Gly allele confers high-level resistance to all herbicides tested in this study, however, moderate resistance to sethoxydim. The 2096Ala very likely endows high-level resistance to fluazifop-p-butyl, haloxyfop-p-methyl and moderate resistance to sethoxydim. In addition, one undefined resistance mechanism was involved in population SD-04.

A decades-long investigation of acute metabolism-based hepatotoxicity by herbal constituents: a case study of pennyroyal oil.

Herbal supplements are often regarded as "natural", and are, therefore, considered by many to be safer than pharmaceuticals; however, the adverse effects of these supplements are under-reported in many cases. Many herbal supplements, such as pyrrolizidine alkaloids, kava, chaparral and germander, are known to induce liver injury, which, in general, is one of the main toxicity liabilities observed in the clinic and accounts for about half of total liver failures. One example is the hepatotoxicity of pennyroyal oil, which is ingested as an abortifacient, among other uses. For three decades, the late Professor Sidney Nelson contributed to our understanding of the mechanism of toxicity of pennyroyal and broadened our understanding of chemical toxicology. Here we present the studies and review the findings on acute hepatotoxicity of pennyroyal oil. These studies involved the isolation and characterization of pennyroyal components, determination of the appropriate animal models, identification of the structural requirement for toxicity and determination of the target enzymes and the enzymes involved in the process of bioactivation. Studies with stable isotope labeled pennyroyal metabolites, pulegone and menthofuran, furthered our understanding of the role of cytochrome P450 in the oxidation of these compounds. This review presents the investigational tools used in the study of pennyroyal oil, allowing the reader to not only appreciate these methods but also utilize them to tackle and better understand metabolism-based toxicity in their own projects.

Methoxetamine-related deaths in the UK: an overview.

OBJECTIVE: The goal of this study is to provide an update on the data given on methoxetamine (MXE)-related fatalities that occurred in 2011-2013, presented at the Second International Conference on Novel Psychoactive Substances. METHODS: Fatalities involving MXE were extracted from the database of the National Programme on Substance Abuse Deaths, which receives information on drug-related deaths from Coroners in the UK and Islands (Isle of Man, Jersey, Guernsey) and other data suppliers. RESULTS: Eight cases, received by 3 September 2013, in which MXE was found at post-mortem and/or directly implicated in the death and/or mentioned in the Coroner's verdict are described. The median age at death was 27 years, with the majority of White ethnicity (6/8) and male (7/8). MXE was used together with other substances in 7/8 cases. MXE was found at post-mortem in all cases, directly implicated in the deaths of four and likely to have had an influence in two. CONCLUSIONS: More research needs to be conducted into its health effects and toxicity potential. Health care professionals should be made aware of the potential health harms of MXE, in order to develop early intervention measures and minimise the number of MXE-related poisonings and fatalities.

Multiple resistance to ACCase and AHAS-inhibiting herbicides in shortawn foxtail (Alopecurus aequalis Sobol.) from China.

Shortawn foxtail (Alopecurus aequalis) is a troublesome grass weed infesting winter wheat and oilseed rape productions in China. Fenoxaprop-p-ethyl and mesosulfuron-methyl failed to control shortawn foxtail of AHSX-1 population collected from a wheat field in Shou County, Anhui province. Molecular analyses revealed that Asp2078Gly mutation of ACCase and Trp574Leu mutation of AHAS were present in plants of the AHSX-1 population. The homozygous plants were isolated and cultured until seed maturity. Whole-plant herbicide bioassays were conducted in the greenhouse using the purified seeds of F1 generation. Dose-response experiments showed that the AHSX-1 population has evolved a very high level resistance to fenoxaprop-p-ethyl (RI = 275) and mesosulfuron-methyl (RI = 788). To determine the sensitivity to other herbicides, assays were conducted at the single recommended rate of each herbicide. Based on the results, the AHSX-1 population was considered to be highly resistant to clodinafop-propargyl, pyroxsulam and flucarbazone-sodium, moderately or highly resistant to quizalofop-p-ethyl, clethodim, sethoxydim and pinoxaden, and susceptible to isoproturon and chlorotoluron. This is the first report of Asp2078Gly mutation in shortawn foxtail and the two robust dCAPS markers designed could quickly detect Asp2078 and Trp574 mutations in ACCase and AHAS gene of shortawn foxtail, respectively.

Resistance of American sloughgrass (Bechmannia syzigachne) populations to ACCase-inhibiting herbicides involves three different target site mutations from China.

American sloughgrass [Beckmannia syzigachne (Steud.) Fernald] is a problematic annual grass weed in winter wheat fields of China, which causes great loss of wheat yield. Repeated use of acetyl-CoA carboxylase (ACCase)-inhibiting herbicides during the last two decades to control this weed has been selected for resistance in American sloughgrass in Jiangsu province. In this study, whole-plant dose-response assays were conducted to investigate the level of resistance in four resistant American sloughgrass populations (LY, JH, BYJ and BYP) to four ACCase-inhibiting herbicides belonging to aryloxyphenoxypropionates, cyclohexanediones, and phenylpyrazolines groups under greenhouse conditions. Based on resistance factor (RF), three populations, LY, BYJ and BYP, were highly resistant to fenoxaprop-P-ethyl, clodinafop propargyl, sethoxydim and pinoxaden. JH plants exhibited resistance to fenoxaprop-P-ethyl and clodinafop propargyl, but showed much lower RF values for sethoxydim and pinoxaden. Molecular analysis of resistance revealed that resistance in all the four populations was target site-based. Results confirmed that substitutions of Ile-1781-Leu, Ile-2041-Asn and Asp-2078-Gly, respectively, in LY, JH and BYJ/BYP, are responsible for diverse sensitivity to different ACCase-inhibiting herbicides in these populations. The substitution at position 1781 had been reported, while it is the first report of Ile-2041-Asn and Asp-2078-Gly mutations that corresponded to resistance in American sloughgrass.

Cytotoxicity on Allium cepa of the two main sulcotrione photoproducts, xanthene-1,9-dione-3,4-dihydro-6-methylsulphonyl and 2-chloro-4-mesylbenzoic acid.

The cytotoxic effects of 2-chloro-4-mesylbenzoic acid (CMBA) and xanthene-1,9-dione-3,4-dihydro-6-methylsulphonyl (XDD), the two main photoproducts of sulcotrione, were investigated on Allium root meristematic cells at different concentrations. Degradation of sulcotrione was correlated to mitotic index decrease, together with increasing anomaly and c-mitosis frequencies. Mitotic index significantly decreased with increasing XDD and CMBA concentrations. Cell frequency with abnormal chromosomes increased with CMBA or XDD application rates. In contrast, CMBA induced a low micronucleus rate even for high concentrations while XDD increased the micronucleus ratio. C-mitoses, chromosomal aberrations due to an inactivation of the spindle, were enhanced by CMBA treatments but not by XDD. The photochemical degradation process of the pesticide can change the risk for the environment.

Soil surface colonization by phototrophic indigenous organisms, in two contrasted soils treated by formulated maize herbicide mixtures.

Soil phototrophic microorganisms, contributors to soil health and food webs, share their particular metabolism with plants. Current agricultural practices employ mixtures of pesticides to ensure the crops yields and can potentially impair these non-target organisms. However despite this environmental reality, studies dealing the susceptibility of phototrophic microorganisms to pesticide mixtures are scarce. We designed a 3 months microcosm study to assess the ecotoxicity of realistic herbicide mixtures of formulated S-metolachlor (Dual Gold Safeneur(®)), mesotrione (Callisto(®)) and nicosulfuron (Milagro(®)) on phototrophic communities of two soils (Limagne vertisol and Versailles luvisol). The soils presented different colonizing communities, with diatoms and chlorophyceae dominating communities in Limagne soil and cyanobacteria and bryophyta communities in Versailles soil. The results highlighted the strong impairment of Dual Gold Safeneur(®) treated microcosms on the biomass and the composition of both soil phototrophic communities, with no resilience after a delay of 3 months. This study also excluded any significant mixture effect on these organisms for Callisto(®) and Milagro(®) herbicides. We strongly recommend carrying on extensive soil studies on S-metolachlor and its commercial formulations, in order to reconsider its use from an ecotoxicological point of view.

Target-site mechanism of ACCase-inhibitors resistance in American sloughgrass (Beckmannia syzigachne Steud.) from China.

American sloughgrass (Beckmannia syzigachne) is a troublesome weed in winter wheat field rotated with rice in China. Fenoxaprop-p-ethyl and pinoxaden were observed failing to control American sloughgrass in the same filed in Lujiang county in 2011 and 2012, respectively. Whole-plant bioassay was conducted to determine the resistance to fenoxaprop-p-ethyl, pinoxaden and other herbicides in American sloughgrass. Dose-response experiment indicated that Lujiang population was highly resistant to fenoxaprop-p-ethyl (199.8-fold), pinoxaden (76.2-fold), clodinafop-propargyl (334.1-fold) and sethoxydim (15.9-fold); moderately resistant to clethodim (6.3-fold), susceptible to mesosulfuron-methyl, flucarbazone-sodium, pyroxsulam and isoproturon. Partial gene of CT domain was cloned and sequenced to confirm the molecular mechanism of resistance to ACCase-inhibiting herbicides. A Trp2027Cys mutation was found in Lujiang population according to the sequencing result. This mutation is the molecular mechanism of resistance to fenoxaprop-p-ethyl in Lujiang population. Furthermore the Trp2027Cys mutation very likely results in cross resistance to clodinafop-propargyl and pinoxaden in Lujiang population. 103 mutant homozygotes were detected from the 108 plants tested using a rapid dCAPS method developed in this paper. This is the first report of pinoxaden resistance and a mutation at position of 2027 for American sloughgrass.

Genotoxicity of sulcotrione pesticide and photoproducts on Allium cepa root meristem.

Contamination by toxic agents in the environment has become matters of concern to agricultural countries. Sulcotrione, a triketone herbicide used to control dicotyledonous weeds in maize culture is rapidly photolyzed on plant foliage and generate two main photoproducts the xanthene-1,9-dione-3,4-dihydro-6-methylsulfonyl and 2-chloro-4-mesylbenzoic acid (CMBA). The aim of this study was to analyze the potential toxicity of the herbicide and the irradiated herbicide cocktail. Cytotoxicity and genotoxicity of non irradiated and irradiated sulcotrione were investigated in Allium cepa test. The sulcotrione irradiation was monitored under sunlight simulated conditions to reach 50% of phototransformation. Concentrations of sulcotrione in the range 5 × 10(-)(9)-5 × 10(-)(5)M were tested. Cytological analysis of root tips cells showed that both non irradiated and irradiated sulcotrione caused a dose-dependent decrease of mitotic index with higher cytotoxicity for the irradiated herbicide which can lead to 24.2% reduction of mitotic index compared to water control. Concomitantly, chromosomal aberrations were observed in A.cepa root meristems. Both non irradiated sulcotrione and irradiated sulcotrione induced a dose-dependent increase of chromosomal abnormalities frequencies to a maximal value of 33.7%. A saturating effect in anomaly frequencies was observed in meristems treated with high concentrations of non irradiated sulcotrione only. These data suggest that photolyzed sulcotrione cocktail have a greater cytotoxicity and genotoxicity than parent molecule and question about the impact of photochemical process on environment.

Methoxetamine toxicity reported to the National Poisons Information Service: clinical characteristics and patterns of enquiries (including the period of the introduction of the UK's first Temporary Class Drug Order).

OBJECTIVE: To report the demographic and clinical characteristics of cases of methoxetamine toxicity reported to The National Poisons Information Service (NPIS) by healthcare professionals. To assess the pattern of enquiries from health professionals to the UK NPIS related to methoxetamine, including the period of the making of the UK first Temporary Class Drug Order (TCDO). METHODS: All telephone enquiries to and user sessions for TOXBASE, the NPIS on-line information resource, related to methoxetamine (and synonyms 'MXE', 'mket' and '2-(3-methoxyphenyl)-2-(ethylamino)cyclohexanone') were reviewed from 1 April 2010 to 1 August 2012. Data were compared for the 3 months before and after the TCDO. RESULTS: There were 47 telephone enquiries and 298 TOXBASE sessions regarding methoxetamine during the period of study. Comparing the 3 months before and after the TCDO, TOXBASE sessions for methoxetamine fell by 79% (from 151 to 32) and telephone enquiries by 80% (from 15 to 3). Clinical features reported by enquirers were consistent with case reports of analytically confirmed methoxetamine toxicity and typical toxidromes were of stimulant (36%), reduced consciousness (17%), dissociative (11%) and cerebellar (6.4%) types, but also particularly featured acute disturbances in mental heath (43%). CONCLUSIONS: Structured NPIS data may reveal trends in drugs of abuse use and toxicity when interpreted within their limitations. Since April 2012, there have been fewer enquiries to NPIS from clinicians, indicating reduced presentations with suspected methoxetamine toxicity to healthcare services. It is unclear if this is related to the TCDO made on 5 April 2012.