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Zhangjie Chu - One of the best experts on this subject based on the ideXlab platform.
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characterization of a novel Butachlor biodegradation pathway and cloning of the debutoxylase dbo gene responsible for debutoxylation of Butachlor in bacillus sp hys 1
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Yang Gao, Lei Jin, Hui Shi, Zhangjie ChuAbstract:Bacillus sp. strain hys-1, which was isolated from active sludge, could degrade >90% Butachlor at a concentration of 100 mg/L within 7 days. The present work revealed that strain hys-1 could mineralize Butachlor via the following pathway: Butachlor was initially metabolized to 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide by debutoxylation and then transformed to form 2-chloro-N-(2,6-diethylphenyl)acetamide by N-demethylation. Subsequently, it was converted to 2,6-diethylaniline and further mineralized into CO2 and H2O. In addition, the catalytic efficiency of crude cell extracts descended as follows: alachlor > acetochlor > Butachlor. Furthermore, a novel 744 bp gene responsible for transforming Butachlor into 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide was cloned from strain hys-1 and the encoding debutoxylase was designated Dbo. Then Dbo was expressed in Escherichia coli BL21 (DE3) and purified using Ni–nitrilotriacetic acid affinity chromatography. Dbo displayed the highest activity against bu...
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Characterization of a Novel Butachlor Biodegradation Pathway and Cloning of the Debutoxylase (Dbo) Gene Responsible for Debutoxylation of Butachlor in Bacillus sp. hys‑1
2015Co-Authors: Yang Gao, Lei Jin, Hui Shi, Zhangjie ChuAbstract:Bacillus sp. strain hys-1, which was isolated from active sludge, could degrade >90% Butachlor at a concentration of 100 mg/L within 7 days. The present work revealed that strain hys-1 could mineralize Butachlor via the following pathway: Butachlor was initially metabolized to 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide by debutoxylation and then transformed to form 2-chloro-N-(2,6-diethylphenyl)acetamide by N-demethylation. Subsequently, it was converted to 2,6-diethylaniline and further mineralized into CO2 and H2O. In addition, the catalytic efficiency of crude cell extracts descended as follows: alachlor > acetochlor > Butachlor. Furthermore, a novel 744 bp gene responsible for transforming Butachlor into 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide was cloned from strain hys-1 and the encoding debutoxylase was designated Dbo. Then Dbo was expressed in Escherichia coli BL21 (DE3) and purified using Ni–nitrilotriacetic acid affinity chromatography. Dbo displayed the highest activity against Butachlor at pH 6.5 and 30 °C. Metal ions played an important role in Dbo activity. To the best of the authors’ knowledge, this is the first report that strain hys-1 can mineralize Butachlor by a novel metabolic mechanism and the first identification of a gene encoding Butachlor debutoxylase
Guo Nian Zhu - One of the best experts on this subject based on the ideXlab platform.
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exposure to Butachlor causes thyroid endocrine disruption and promotion of metamorphosis in xenopus laevis
Chemosphere, 2016Co-Authors: Qiangwei Wang, Wenjun Gui, Guo Nian ZhuAbstract:Butachlor is extensively applied in rice paddy ecosystem in china, and has been widespread contaminant in the aquatic environment. Here, Xenopus laevis was used for the evaluation of teratogenesis developmental toxicity, and disruption of thyroid system when exposure to different concentrations of Butachlor by window phase exposure. Acute toxicity investigation shown that 96 h-LC50 value of Butachlor was 1.424 mg L(-1) and 0.962 mg L(-1) for tadpoles (starting from stages 46/47) and embryos (starting from stages 8/9), respectively. Exposure to Butachlor caused malformation, including abnormal eye, pericardial edema, enlarged proctodaeum and bent tail. Window phase exposure test indicated that Butachlor significantly promote the contents of whole-body thyroid hormones (THs, T3 and T4) at higher levels, indicating thyroid endocrine disruption. At 7 days, exposure to Butachlor up-regulated the mRNA expression of genes involved in THs synthesis and metabolism (tshα, tg, tpo and dio1) and THs receptors (trα and trβ). At 14 days, up-regulation of the mRNA expression of genes related to THs synthesis and metabolism (tshα, tshβ, tg, tpo, dio1, dio2 and ttr) and THs receptors (trβ) were also observed after the exposure to Butachlor. At 21 days, Butachlor up-regulated the mRNA expression of tshα, tg, tpo genes and down-regulated the mRNA expression of tshβ, tg, dio1, ttr and trα genes. These results showed that Butachlor could change the mRNA expression of genes involved in the HPT axis and increase whole-body thyroid hormones levels of X. laevis tadpoles in a dose- and time-dependent manner, causing thyroid endocrine disruption and developmental toxicity.
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effects of Butachlor on reproduction and hormone levels in adult zebrafish danio rerio
Experimental and Toxicologic Pathology, 2013Co-Authors: Juhua Chang, Shaoying Liu, Shengli Zhou, Minghua Wang, Guo Nian ZhuAbstract:Butachlor, a chloracetamide herbicide, is widely used in China. In the present study, paired adult male and female zebrafish (Danio rerio) were exposed to various concentrations of Butachlor (0, 25, 50 and 100 μg/L) for 30 days, and the effects on reproduction and endocrine disruption were evaluated using fecundity, condition factor (CF), gonadosomatic index (GSI), liver somatic index (LSI), plasma vitellogenin (VTG), sex steroids and thyroid hormone levels as endpoints. Our results showed that the mean fecundity rates were significantly decreased at 50 and 100 μg/L Butachlor during the 30-day exposure period. At the end of the exposure period, no significant changes were observed in CF and LSI in both females and males, while GSI was significantly reduced in males at 50 and 100 μg/L Butachlor. At 100 μg/L Butachlor, plasma testosterone (T) and 17β-estradiol (E2) levels were significantly decreased in females, while plasma VTG level was significantly increased in males. Plasma thyroxine (T4) and triiodothyronine (T3) levels were significantly increased at 50 and 100 μg/L Butachlor in males, and at 100 μg/L in females. This work demonstrated that Butachlor adversely affected the normal reproductive success of zebrafish, and disrupted the thyroid and sex steroid endocrine systems, which provides the basis for the estimated ecological risk during Butachlor exposure.
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effects of Butachlor on estrogen receptor vitellogenin and p450 aromatase gene expression in the early life stage of zebrafish
Journal of Environmental Science and Health Part A-toxic\ hazardous Substances & Environmental Engineering, 2012Co-Authors: Juhua Chang, Wenjun Gui, Minghua Wang, Guo Nian ZhuAbstract:Butachlor has adverse effects on fecundity and disrupts sex hormone homeostasis in adult zebrafish, but the underlying molecular mechanisms are still unclear. In the present study, zebrafish (Danio rerio) embryos were exposed to various concentrations of Butachlor from 2 h post-fertilization (hpf) to 30 days post-fertilization (dpf). The transcription of genes involved estrogen receptors (ERα, ERβ1 and ERβ2), vitellogenins (VTG I and II), and cytochrome P450 aromatase (CYP19a) was analyzed by real-time quantitative PCR. The results showed that there was no significant alteration in the expression of VTGI, ERα, ERβ1, ERβ2 and CYP19a after 30 days of Butachlor exposure, whereas the transcription of VTG II gene was significantly up-regulated in zebrafish exposed to 100 μg/L Butachlor. It is suggested that Butachlor may be a weak estrogen, and more endpoints need to be investigated to assess the effects of Butachlor on the hypothalamus–pituitary–gonadal axis of zebrafish.
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evaluation of dna damage in chinese toad bufo bufo gargarizans after in vivo exposure to sublethal concentrations of four herbicides using the comet assay
Ecotoxicology, 2008Co-Authors: Xiao Hui Yin, Le Zhang, Guo Nian Zhu, Hui Sheng ZhuangAbstract:Chinese toad, Bufo bufo gargarizans, is frequently found in rice fields, muddy ponds, wetlands and other aquatic ecosystems in China. Because of its habitat, it has many chances of being exposed to pesticides, such as acetochlor, Butachlor, chlorimuron-ethyl, and paraquat, which are extensively used in rice or cereal fields. Amphibians may serve as model organisms for determining the genotoxic effects of pollutants contaminating these areas. In the present study DNA damage was evaluated in the Chinese toad using the comet assay, as a potential tool for the assessment of ecogenotoxicity. The first step was to determine the acute toxicity of the above-mentioned herbicides. In acute tests, tadpoles were exposed to a series of relatively high concentrations of acetochlor, Butachlor, chlorimuron-ethyl, and paraquat for 96 h. The LC50 (96 h) of acetochlor, Butachlor, chlorimuron-ethyl and paraquat were measured as 0.76, 1.32, 20.1 and 164 mg·l−1, respectively. Also, negative effects on the behavior of tadpoles were observed with acetochlor, Butachlor, and paraquat. Secondly, the comet assay was used for detecting DNA damage in Chinese toad tadpoles exposed to sublethal concentrations of four herbicides. Significant (P < 0.05) concentration-dependent increase in DNA damage (as indicated by tail length, tail moment, olive tail moment) were observed from erythrocytes of tadpoles exposed to sublethal concentrations of acetochlor, Butachlor, paraquat, and methyl methanesulfonate, except chlorimuron-ethyl. To our knowledge, this is the first report describing the use of Bufo bufo gargarizans for genotoxicity assessment of herbicides.
Zhongzhen Liu - One of the best experts on this subject based on the ideXlab platform.
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a new adsorption model to quantify the net contribution of minerals to Butachlor sorption in natural soils with various degrees of organo mineral aggregation
Geoderma, 2014Co-Authors: Zhongzhen Liu, Xinquan Shen, P C BrookesAbstract:The effect of interactions between soil minerals and organic matter as a function of aggregate size on Butachlor sorption was quantified in natural soils with various degrees of organo-mineral aggregation. The smallest size clay microaggregates sorbed most Butachlor (58% to 71%) and the fine sand fraction sorbed the least (less than 4.3%). When normalized to organic carbon, Butachlor sorption to the clay microaggregates was even smaller than to the silt and sand fractions under specific soil conditions. The sum of sorption to the different fractions was, on average, above 78% greater than sorption to the bulk soils, with the greatest differences in the soils with relatively higher ratios of clay to soil organic carbon (RCO). This suggests that minerals can physically protect favorable sorption sites within soil organic matter (SOM), and inhibit Butachlor sorption by influencing SOM physical conformation. Comparisons of changes in Butachlor sorption coefficients (both Kd and Koc) in two different series of soils, with the same mineral components but gradients of total organic carbon (TOC) and RCO values also showed that minerals can directly contribute to soil Butachlor sorption processes, which may be even more pronounced in soils with relative higher RCOs. A new adsorption model was proposed and verified to quantify the net contribution of minerals to Butachlor sorption, based upon 38 different soils. This study has increased our ability to quantify the positive direct contribution of soil minerals and their negative indirect contribution through associated effects on SOM physical conformation during Butachlor sorption in natural soils.
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how do amorphous sesquioxides affect and contribute to Butachlor retention in soils
Journal of Soils and Sediments, 2013Co-Authors: Zhongzhen Liu, Fang ZengAbstract:Sorption and desorption of Butachlor were simultaneously investigated on synthesized pure amorphous hydrated Fe oxides (AHOs Fe), and soils both with and without surface coating of AHOs Fe, with special interest towards how amorphous sesquioxides affect and contribute to Butachlor retention in soils. The AHOs Fe was artificially synthesized pure materials. Two soils with contrasting physicochemical properties selected for study were black soil and latosol, belonging to permanent charged soil and variable charged soil, respectively. Both soils were further treated using AHOs Fe for detecting the differentiation from native soils regarding Butachlor retention produced after the soils were surface-coated by AHOs Fe. A sorption experiment was conducted using a batch equilibrium technique, and desorption was carried out immediately following sorption by three sequential dilution. Hysteresis index (HI) values were calculated to investigate desorption hysteresis by developing desorption isotherms concentration dependent and time dependent, respectively. The sorption capacity for Butachlor increased in the order of AHOs Fe, uncoated soils, and soils with surface coating of AHOs Fe. The sorption capacity of both soils significantly increased after surface coating by AHOs Fe (p < 0.01), with a bigger increase achieved by black soil (52.0 %) as compared with that by latosol (45.3 %). Desorption of Butachlor was coincidently hysteretic on AHOs Fe, and soils both uncoated and coated, whereas variation in desorption hysteresis was different between AHOs Fe and soils with increasing Butachlor sorption loading, indicating different sorption mechanisms were operative for AHOs Fe and soils across the entire Butachlor concentration range. Hysteresis of Butachlor desorption was weakened after the soils were surface coated by AHOs Fe, as suggested by the changed HI values. With high specific surface area and highly reactive surfaces, the “active” AHOs Fe originally has a relatively high sorption capacity and affinity for Butachlor. While in natural soils, where the inevitable association derived from soil organic matter (SOM) would restrain AHOs Fe from sequestrating Butachlor directly, AHOs Fe may likely contribute in a mediator way by coordinating active sites both on and within SOM. This may enhance the availability of sorption domains both on and within soils, thereby achieved an enhanced but more reversible retention for Butachlor in soils after their surfaces were coated by AHOs Fe. This study has extended the observations of the role of noncrystalline sesquioxides in retention of pesticides such as Butachlor from pure clay mineral systems to natural soils.
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can assessing for potential contribution of soil organic and inorganic components for Butachlor sorption be improved
Journal of Environmental Quality, 2011Co-Authors: Zhongzhen Liu, Haizhen Wang, Jian Zhang, Jiachun ShiAbstract:Sorption of Butachlor to various types of common soil components was investigated. Six pure minerals (montmorillonite [Mont], kaolinite [Kaol], Ca homoionic montmorillonite [Ca-Mont] and kaolinite [Ca-Kaol], amorphous hydrated Al and Fe oxides [AHOs-Al, AHOs-Fe]), four soil alkali-extractable pure humic acids (HAs), and the four corresponding HAs originated real unmodified and HO-treated soils were selected as the representative sorbents. Results showed that the HAs played a crucial role, and clay minerals (especially Mont) also showed an important effect in Butachlor sorption. The AHOs may likely influence only in a mediator way by enhancing the availability of sorption domains of HAs. By removing 78% (on average) of the total organic carbon (TOC) from the soils with HO, the content ratio of clay to TOC (RCO) increased by an average of 367% and became >60. This change simultaneously decreased the sorption capacity of soils (40%, on average). Considering that the surface sorption domain on clay minerals may be highly exposed and more competitive after the partial removal of soil organic matter (SOM), this reaffirmed the potential contribution from clay minerals. It can thus be inferred that in the real soil where SOM and clay minerals are associated, the coating of clay minerals may have weakened the partition function of SOM or blocked some sorption domain within SOM, resulting in a decreased sorption of Butachlor. Therefore, clay minerals, especially 2:1 type expanding minerals, may play a dual function vs. SOM content for the sorption of Butachlor in soil.
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Butachlor sorption in organically rich soil particles
Soil Science Society of America Journal, 2010Co-Authors: Zhongzhen Liu, Na Ding, Tahir Hayat, Haizhen WangAbstract:The herbicide Butachlor [N-(butoxymethyl)-2-chloro-N-(2,6-diethylphenyl)acetamide] is a pre-emergence herbicide belonging to the chloroacetanilide group used widely to control grasses in Asian countries. Butachlor has toxicity to aquatic organisms and earthworms and can induce apoptosis in mammalian cells. This study used a batch equilibration method to investigate Butachlor sorption by different size organomineral fractions of a black soil. About 60 to 70% ofButachlorwas adsorbed on the clay size fraction, 30 to 40% on the silt fraction, and <0.3% by the fine sand fraction. For the clay fraction, the nonlinearity of adsorption was significant in the low equilibrium concentration range. For the silt and fine sand fractions, the isotherms were near linear across the concentration range studied. Butachlor adsorption on a clay fraction treated with H 2 O 2 showed that the degree of nonlinearity became smaller, and the value of the normalized sorption coefficient for organic C (K oc ) was much higher than that of the untreated clay fraction. Mineral colloids might have a dual function in the Butachlor adsorption process. For an adsorbent with a very low soil organic matter (SOM) content, mineral colloids could enhance Butachlor adsorption because of their high exposed mineral surface, which would result in higher K oc values. For an adsorbent with a high SOM content, mineral colloids might weaken the SOM partition function because of their strong association with and coating of SOM, which would result in lower K oc values. These results are useful to better understand the adsorption mechanism of anthropogenic organics in different components and size fractions of soils.
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the ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide Butachlor in soils
Environmental Pollution, 2008Co-Authors: Zhongzhen Liu, Panming Huang, Ghulam JilaniAbstract:Thirteen soils collected from 11 provinces in eastern China were used to investigate the Butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the Butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for Butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed Butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed Butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface.
Yang Gao - One of the best experts on this subject based on the ideXlab platform.
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characterization of a novel Butachlor biodegradation pathway and cloning of the debutoxylase dbo gene responsible for debutoxylation of Butachlor in bacillus sp hys 1
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Yang Gao, Lei Jin, Hui Shi, Zhangjie ChuAbstract:Bacillus sp. strain hys-1, which was isolated from active sludge, could degrade >90% Butachlor at a concentration of 100 mg/L within 7 days. The present work revealed that strain hys-1 could mineralize Butachlor via the following pathway: Butachlor was initially metabolized to 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide by debutoxylation and then transformed to form 2-chloro-N-(2,6-diethylphenyl)acetamide by N-demethylation. Subsequently, it was converted to 2,6-diethylaniline and further mineralized into CO2 and H2O. In addition, the catalytic efficiency of crude cell extracts descended as follows: alachlor > acetochlor > Butachlor. Furthermore, a novel 744 bp gene responsible for transforming Butachlor into 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide was cloned from strain hys-1 and the encoding debutoxylase was designated Dbo. Then Dbo was expressed in Escherichia coli BL21 (DE3) and purified using Ni–nitrilotriacetic acid affinity chromatography. Dbo displayed the highest activity against bu...
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Characterization of a Novel Butachlor Biodegradation Pathway and Cloning of the Debutoxylase (Dbo) Gene Responsible for Debutoxylation of Butachlor in Bacillus sp. hys‑1
2015Co-Authors: Yang Gao, Lei Jin, Hui Shi, Zhangjie ChuAbstract:Bacillus sp. strain hys-1, which was isolated from active sludge, could degrade >90% Butachlor at a concentration of 100 mg/L within 7 days. The present work revealed that strain hys-1 could mineralize Butachlor via the following pathway: Butachlor was initially metabolized to 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide by debutoxylation and then transformed to form 2-chloro-N-(2,6-diethylphenyl)acetamide by N-demethylation. Subsequently, it was converted to 2,6-diethylaniline and further mineralized into CO2 and H2O. In addition, the catalytic efficiency of crude cell extracts descended as follows: alachlor > acetochlor > Butachlor. Furthermore, a novel 744 bp gene responsible for transforming Butachlor into 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide was cloned from strain hys-1 and the encoding debutoxylase was designated Dbo. Then Dbo was expressed in Escherichia coli BL21 (DE3) and purified using Ni–nitrilotriacetic acid affinity chromatography. Dbo displayed the highest activity against Butachlor at pH 6.5 and 30 °C. Metal ions played an important role in Dbo activity. To the best of the authors’ knowledge, this is the first report that strain hys-1 can mineralize Butachlor by a novel metabolic mechanism and the first identification of a gene encoding Butachlor debutoxylase
Zhongyun Chen - One of the best experts on this subject based on the ideXlab platform.
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effects of Butachlor on microbial enzyme activities in paddy soil
Journal of Environmental Sciences-china, 2002Co-Authors: Hang Min, Zhongyun ChenAbstract:This paper reports the influences of the herbicide Butachlor (n-butoxymethl-chloro-2', 6'-diethylacetnilide) on microbial respiration, nitrogen fixation and nitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that after application of Butachlor with concentrations of 5.5 micrograms/g dried soil, 11.0 micrograms/g dried soil and 22.0 micrograms/g dried soil, the application of Butachlor enhanced the activity of dehydrogenase at increasing concentrations. The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0 micrograms/g dried soil of Butachlor. The hydrogen peroxidase could be stimulated by Butachlor. The soil respiration was depressed within a period from several days to more than 20 days, depending on concentrations of Butachlor applied. Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.
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effects of Butachlor on microbial populations and enzyme activities in paddy soil
Journal of Environmental Science and Health Part B-pesticides Food Contaminants and Agricultural Wastes, 2001Co-Authors: Yangfang Ye, Zhongyun Chen, Weixiang Wu, Du YufengAbstract:This paper reports the influences of the herbicide Butachlor (n-butoxymethl-chloro -2′,6′ -diethylacetnilide) on microbial populations, respiration, nitrogen fixation andnitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that the number of actinomycetes declined significantly after the application of Butachlor at different concentrations ranging from 5.5μg g−1 to 22.0μg g−1 dried soil, while that of bacteria and fungi increased. Fungi were easily affected by Butachlor compared to the bacteria. The growth of fungi was retarded by Butachlor at higher concentrations. Butachlor however, stimulated the growth of anaerobic hydrolytic fermentative bacteria, sulfate-reducing bacteria (SRB) and denitrifying bacteria. The increased concentration of Butachlor applied resulted in the higher number of SRB. Butachlor inhibited the growth of hydrogen-producing acetogenic bacteria. The effect of Butachlor varied on methane-producing bacteria (MPB) at different ...
