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Different cadmium (Cd)-accumulated rice genotypes (Erjiunan 1 and Fupin 36) were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation. Aeration in the nutrient solution influenced the agronomic characteristics induced by Cd-stress, such as the increases of rice root length and root vigor, but the reductions of plant height and shoot dry weight. Aeration also alleviated the decreasing effects of Cd stress on antioxidant enzyme activities and soluble protein, malonaldehyde and nicotianamine contents in rice. Moreover, with aeration treatment, the accumulation and bioavailability of metal elements changed significantly, with a Cd increase and an Fe reduction in both rice genotypes. In addition, at the molecular level, aeration upregulated the expression of Fe-inducible genes (such as OsIRT1, OsNRAMP1, OsYSL15 and OsNAS3). Furthermore, as a Cd2+/Fe2+ transporter, the high transcription level of OsNRAMP1 can elevate the Cd uptake and translocation in rice due to the Fe reduction caused by aeration and Cd-exposure, which indicated that OsNRAMP1 might play a crucial role in the effect of aeration on Cd uptake and accumulation.

Triclabendazole (TCB) is widely used for prevention and treatment of parasitic infections in animals. Improper use can result in drug residues in animal tissues and cause health problems to humans through consumption. A simple and reliable analytical method for the determination of TCB and its metabolites in bovine and goat muscle using liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed and validated. Analytes were extracted using acetonitrile and purified using enhanced matrix removal cartridge. Chromatographic separation was carried out on a BEH Shield RP18 column. The analytes were detected in positive‐mode electrospray ionization mass spectrometry using multiple reaction monitoring. Average recoveries of 96.1%–105.6% with coefficients of variation of 1.9%–8.4% were obtained at fortification levels of 0.5, 2.5, 25, and 50 μg/kg for TCB and 5.0, 25, 250, and 500 μg/kg for its metabolites (triclabendazole sulfoxide, triclabendazole sulfone, and keto‐TCB). A good linear regression was obtained with the mixed standard solutions in the range of 0.05–20 μg/L for TCB and 0.5–200 μg/L for its metabolites. The limit of quantification and limit of detection ranged from 0.05 to 0.75 μg/kg and from 0.1 to 1.5 μg/kg, respectively. Moreover, this method was successfully applied to 33 real samples. [ABSTRACT FROM AUTHOR]

An analytical method was established to simultaneously determine prochloraz and three metabolites N-propyl-N-[2-(2,4,6-trichlorophenoxy)ethyl] urea(BTS44595), N-formyl-N-propyl-N-[2-(2,4,6-trichlorophenoxy)ethyl] urea(BTS44596), and 2,4,6-trichlorophenol(BTS45186) in fruits and vegetables. The analysis was performed by liquid chromatography – tandem mass spectrometry (LC-MS/MS) in the positive and negative ion-switching multiple reaction modes (MRM). The analytes were extracted using acetonitrile. The extract was further purified by dispersive solid phase extraction. The linearity of the matrix-matched calibration curves was verified with correlation coefficients (r) greater than 0.9975. Recoveries in fruits and vegetables were conducted at four appropriate concentrations. The average recoveries of the method ranged from 80% to 105%, and the relative standard deviations were less than 15%. The limits of detection and quantification of the analytes in fruits and vegetables were from 0.1 to 1 µg/kg and 0.5 to 5 µg/kg, respectively. The method was validated and demonstrated to be suitable for the determination of prochloraz and three metabolites in fruits and vegetables. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency is one of the most common micronutrient deficiencies limiting crop production globally, especially in arid regions because of decreased availability of iron in alkaline soils. Sweet potato [ Ipomoea batatas (L.) Lam.] grows well in arid regions and is tolerant to Fe deficiency. Here, we report that the transcription of type I H+-pyrophosphatase (H+- PPase) gene Ib VP1 in sweet potato plants was strongly induced by Fe deficiency and auxin in hydroponics, improving Fe acquisition via increased rhizosphere acidification and auxin regulation. When overexpressed, transgenic plants show higher pyrophosphate hydrolysis and plasma membrane H+- ATPase activity compared with the wild type, leading to increased rhizosphere acidification. The Ib VP1-overexpressing plants showed better growth, including enlarged root systems, under Fe-sufficient or Fe-deficient conditions. Increased ferric precipitation and ferric chelate reductase activity in the roots of transgenic lines indicate improved iron uptake, which is also confirmed by increased Fe content and up-regulation of Fe uptake genes, e.g. FRO2, IRT1 and FIT. Carbohydrate metabolism is significantly affected in the transgenic lines, showing increased sugar and starch content associated with the increased expression of AGPase and SUT1 genes and the decrease in β-amylase gene expression. Improved antioxidant capacities were also detected in the transgenic plants, which showed reduced H2O2 accumulation associated with up-regulated ROS-scavenging activity. Therefore, H+- PPase plays a key role in the response to Fe deficiency by sweet potato and effectively improves the Fe acquisition by overexpressing Ib VP1 in crops cultivated in micronutrient-deficient soils. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency is one of the most common micronutrient deficiencies limiting crop production globally, especially in arid regions because of decreased availability of iron in alkaline soils. Sweet potato [Ipomoea batatas (L.) Lam.] grows well in arid regions and is tolerant to Fe deficiency. Here, we report that the transcription of type I H + -pyrophosphatase (H + -PPase) gene IbVP1 in sweet potato plants was strongly induced by Fe deficiency and auxin in hydroponics, improving Fe acquisition via increased rhizosphere acidification and auxin regulation. When overexpressed, transgenic plants show higher pyrophosphate hydrolysis and plasma membrane H + -ATPase activity compared with the wild type, leading to increased rhizosphere acidification. The IbVP1-overexpressing plants showed better growth, including enlarged root systems, under Fe-sufficient or Fe-deficient conditions. Increased ferric precipitation and ferric chelate reductase activity in the roots of transgenic lines indicate improved iron uptake, which is also confirmed by increased Fe content and up-regulation of Fe uptake genes, e.g. FRO2, IRT1 and FIT. Carbohydrate metabolism is significantly affected in the transgenic lines, showing increased sugar and starch content associated with the increased expression of AGPase and SUT1 genes and the decrease in β-amylase gene expression. Improved antioxidant capacities were also detected in the transgenic plants, which showed reduced H 2 O 2 accumulation associated with up-regulated ROS-scavenging activity. Therefore, H + -PPase plays a key role in the response to Fe deficiency by sweet potato and effectively improves the Fe acquisition by overexpressing IbVP1 in crops cultivated in micronutrient-deficient soils., (© 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

A method was developed for the simultaneous determination of flonicamid and its metabolite [N-(4-trifluoromethylnicotinoyl) glycine (TFNG), 4-trifluoromethylnicotinic acid (TFNA) and 4-trifluoromethylnicotinamide (TFNA-AM)] in cucumbers and apples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with liquid-liquid extraction. The sample was extracted twice with phosphate buffer solution (pH 7.0), and the extract was adjusted to pH 1.5 - 2.0, then an aliquot of the extract (3 mL) was extracted with ethyl acetate. The final extract was dried under nitrogen and the residue was dissolved in 0.1% formic acid in water/methanol (80/20, v/v). The sample was analyzed by LC-MS/MS and quantified with the external standard calibration curve method. The detection limits of flonicamid, TFNG, TFNA and TFNA-AM were 0.17, 0.20, 0.35 and 0.60 microg/kg, respectively. The average recoveries of flonicamid and its metabolites in cucumbers and apples were 82.9% - 104.1%. In the intra-assay, the relative standard deviations were 3.6% - 6.9% at the spiked levels of 5.0 - 2 000 microg/kg. There were good linear correlations (the calibration coefficients were above 0.998) between the peak areas and the concentrations of flonicamid and its metabolites in the range of 0.5 - 200 microg/L. The volume of organic solvent used in the whole pretreatment procedure was only 6 mL. The method is accurate, highly sensitive and stable for the determination of flonicamid and its metabolites.

A method for the determination of robenidine residue in chicken tissues and eggs by high performance liquid chromatography (HPLC) was established. The samples were extracted with acetonitrile and purified by an HLB solid-phase extraction (SPE) cartridge. The extract was analyzed by HPLC with acetonitrile-0.05 mol/L NH4H2PO4 buffer (6:4, v/v, pH 6.5) as the mobile phase. The flow rate of the mobile phase was 1.0 mL/min and detection wavelength was 317 nm. There was a good linear correlation between the peak areas and the concentrations of robenidine in the range of 10-1000 microg/L. The limit of detection (S/N = 3) was 10 microg/L, and the limit of quantification (S/N = 10) was 15 microg/kg. The recoveries of robenidine were 73.1%-88.7% at the spiked levels of 15, 50 and 100 microg/kg. The results demonstrate that the method is easy, fast, sensitive, and suitable for the confirmation and quantification of robenidine residue in chicken tissues and eggs. The clean-up effect, sensitivity, accuracy and precision can all meet the analysis requirement.

A method was developed for the determination of emamectin benzoate residue in cabbage and mushroom using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. The sample was extracted with ethyl acetate. Further cleanup was performed on a propylsulfonic acid solid phase extraction cartridge, followed by the derivatization with trifluoroacetic anhydride in the presence of N-methylimidazole. The amount of derivatized emamectin benzoate was determined by fluorescence detector after separation by HPLC. The detection limit was 0.10 microg/kg for cabbage and mushroom samples. The recoveries of emamectin benzoate in cabbage and mushroom samples were 78.6%-84.9%. The inter-day relative standard deviation (RSD) and intra-day RSD were 2.7%-6.0% and 3.1%-8.9%, respectively, at the fortified levels of 1.0-20.0 microg/kg. The calibration curve of emamectin benzoate in vegetables at the concentration range of 0.002 mg/L to 0.10 mg/L was linear (r = 0.9999).

A method has been developed to determine residual stilbenes such as diethylstilbestrol (DES), dienestrol (DIS) and hexestrol (HS) in animal tissues using solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). The procedures for extraction, cleanup on an LC-Si solid phase extraction cartridge and derivatization of stilbenes were established and optimized. The analytes were detected by mass spectrometer with electron impact source in selected ion monitoring mode (EI/SIM), and quantified with an external standard calibration curve method. Linear calibration curves were obtained in the concentration ranges from 5 to 500 microg/L for HS and from 10 to 1000 microg/L for DES and DIS (the correlation coefficients were above 0.99). Recoveries of the stilbenes were 73.0%-86.5%, and the relative standard deviations were between 1.0% and 7.2%. The limits of detection were 0.30 microg/kg for cis-DES, 0.10 microg/kg for trans-DES and HS and 0.15 microg/kg for DIS in pork and swine liver.

A method was developed for determining residual sulfonamides (SAs) such as sulfamethazine (SM2), sulfamonomethoxine (SMM), sulfamethiazole (SMZ), sulfadimethoxine (SDM) and sulfaquinoxaline (SQ) in pork and chicken using solid-phase extraction (SPE) and high performance liquid chromatography (HPLC) with a photodiode array detector. The samples were extracted with ethyl acetate. An NH2 column was used for clean up. For the HPLC determination, an Intersil ODS-2 column was used with a mixture of methanol-acetonitrile-water-acetic acid (2: 2: 9: 0.2, v/v) as the mobile phase. The detection limits (S/N = 3) were 3 microg/kg for SM2, SMM and SMZ, and 7 microg/kg for SDM and SQ. The quantitation limits (S/N = 10) were 10 microg/kg for SM2, SMM and SMZ, and 25 microg/kg for SDM and SQ. The linear ranges were 30 - 5 000 microg/L for SM2, SMM and SMZ, and 60 - 5 000 microg/L for SDM and SQ. The recoveries were between 73.2% and 97.3% with the relative standard deviations between 2.5% and 11.6% originated from the spiked level of 50 microg/kg.