Rapid and Visual Detection of Heterodera schachtii Using Recombinase Polymerase Amplification Combined with Cas12a-Mediated Technology

Heterodera schachtii is a well-known cyst nematode that causes serious economic losses in sugar beet production every year. Rapid and visual detection of H. schachtii is essential for more effective prevention and control. In this study, a species-specific recombinase polymerase amplification (RPA) primer was designed from a specific H. schachtii sequence-characterized amplified region (SCAR) marker. A band was obtained in reactions with DNA from H. schachtii, but absent from nontarget cyst nematodes. The RPA results could be observed by the naked eye, using a lateral flow dipstick (LFD). Moreover, we combined CRISPR technology with RPA to identify positive samples by fluorescence detection. Sensitivity analysis indicated that 10⁻⁴ single cysts and single females, 4⁻³ single second-stage juveniles, and a 0.001 ng genomic DNA template could be detected. The sensitivity of the RPA method for H. schachtii detection is not only higher than that of PCR and qPCR, but can also provide results in <1 h. Consequently, the RPA assay is a practical and useful diagnostic tool for early diagnosis of plant tissues infested by H. schachtii. Sugar beet nematodes were successfully detected in seven of 15 field sugar beet root samples using the RPA assay. These results were consistent with those achieved by conventional PCR, indicating 100% accuracy of the RPA assay in field samples. The RPA assay developed in the present study has the potential for use in the direct detection of H. schachtii infestation in the field.     

全二维气相色谱-飞行时间质谱分析香紫苏油中的挥发性成分

建立了香紫苏油的全二维气相色谱-飞行时间质谱指纹图谱,根据质谱库检索、保留指数验证,或参照标准化合物及文献报道,共定性了183个物质,占峰面积的96.75％,其中正构烷烃、芳香环物质和非芳香环物质在DB-Petro×DB- 17ht柱系统上实现了明显的族组分分离,主要成分为乙酸芳樟酯(15.11％)、芳樟醇(9.32％...     

HPLC-MS/MS测定化妆品中的NDELA

化妆品以d8-NDELA为内标,经提取净化后,采用HPLC-MS/MS测定NDELA(N-亚硝基二乙醇胺)。提取净化时水溶性样品以水作溶剂,用C18柱固相萃取,水不溶性样品用二氯甲烷进行液液萃取。该方法线性范围为5.0 ng/mL～80 ng/mL,NDELA定量限为50μg/kg,回收率85%～104%。实验结果表明,该方法灵敏、准确、重复性好。     

Metabolic Alteration Analysis of Steroid Hormones in Niemann–Pick Disease Type C Model Cell Using Liquid Chromatography/Tandem Mass Spectrometry

Niemann–Pick disease type C (NPC) is an autosomal recessive disease caused by a functional deficiency of cholesterol-transporting proteins in lysosomes, and exhibits various clinical symptoms. Since mitochondrial dysfunction in NPC has recently been reported, cholesterol catabolism to steroid hormones may consequently be impaired. In this study, we developed a comprehensive steroid hormone analysis method using liquid chromatography/tandem mass spectrometry (LC–MS/MS) and applied it to analyze changes in steroid hormone concentrations in NPC model cells. We investigated the analytical conditions for simultaneous LC–MS/MS analysis, which could be readily separated from each other and showed good reproducibility. The NPC phenotype was verified as an NPC model with mitochondrial abnormalities using filipin staining and organelle morphology observations. Steroid hormones in the cell suspension and cell culture medium were also analyzed. Steroid hormone analysis indicated that the levels of six steroid hormones were significantly decreased in the NPC model cell and culture medium compared to those in the wild-type cell and culture medium. These results indicate that some steroid hormones change during NPC pathophysiology and this change is accompanied by mitochondrial abnormalities.     

Protein Profiling of Blood Samples from Patients with Hereditary Leiomyomatosis and Renal Cell Cancer by Surface-Enhanced Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Hereditary leiomyomatosis and renal cell cancer (HLRCC) is an extremely rare syndrome with autosomal dominant inheritance. HLRCC is characterized by a predisposition to leiomyomas of the skin and the uterus as well as renal cell carcinoma. The disease-related gene has been identified as fumarate hydratase (fumarase, FH), which encodes an enzyme involved in the mitochondrial tricarboxylic acid cycle. Protein profiling may give some insight into the molecular pathways of HLRCC. Therefore, we performed protein profiling of blood samples from HLRCC patients, their family members, and healthy volunteers, using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) coupled with IMAC-Cu chips. For hierarchical clustering analysis, we used the 45 peaks that revealed significant differences in single-marker analysis over the range from 1500 to 15,000 m/z. Heat map analysis based on the results of clustering distinguished the HLRCC kindred from non-HLRCC subjects with a sensitivity of 94% and a specificity of 90%. SELDI-TOF MS profiling of blood samples can be applied to identify patients with HLRCC and to assess specific molecular mechanisms involved in this condition.     

Wheat Drought-Responsive Grain Proteome Analysis by Linear and Nonlinear 2-DE and MALDI-TOF Mass Spectrometry

A comparative proteomic analysis of drought-responsive proteins during grain development of two wheat varieties Kauz (strong resistance to drought stress) and Janz (sensitive to drought stress) was performed by using linear and nonlinear 2-DE and MALDI-TOF mass spectrometry technologies. Results revealed that the nonlinear 2-DE had much higher resolution than the linear 2-DE. A total of 153 differentially expressed protein spots were detected by both 2-DE maps, of which 122 protein spots were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified differential proteins were mainly involved in carbohydrate metabolism (26%), detoxification and defense (23%), and storage proteins (17%). Some key proteins demonstrated significantly different expression patterns between the two varieties. In particular, catalase isozyme 1, WD40 repeat protein, LEA and alpha-amylase inhibitors displayed an upregulated expression pattern in Kauz, whereas they were downregulated or unchanged in Janz. Small and large subunit ADP glucose pyrophosphorylase, ascorbate peroxidase and G beta-like protein were all downregulated under drought stress in Janz, but had no expression changes in Kauz. Sucrose synthase and triticin precursor showed an upregulated expression pattern under water deficits in both varieties, but their upregulation levels were much higher in Kauz than in Janz. These differentially expressed proteins could be related to the biochemical pathways for stronger drought resistance of Kauz.     

Assessment of Isoprostanes in Human Plasma: Technical Considerations and the Use of Mass Spectrometry

Oxygenated lipid mediators released from non‐enzymatic peroxidation of polyunsaturated fatty acids (PUFA) are known to have functional roles in humans. Notably, among these lipid mediators, isoprostanes molecules are robust biomarkers of oxidative stress but those from n‐3 PUFA are also bioactive molecules. In order to identify and assess the isoprostanes, the use of mass spectrometry (MS) for analysis is preferable and has been used for over two decades. Gas chromatography (GC) is commonly coupled to the MS to separate the derivatized isoprostanes of interest in biological samples. In order to increase the accuracy of the analytical performance, GC–MS/MS was also applied. Lately, MS or MS/MS has been coupled with high‐performance liquid chromatography to assess multiple isoprostane molecules in a single biological sample without derivatization process. However, there are limitations for the use of LC–MS/MS in the measurement of plasma isoprostanes, which will be discussed in this review.     

应用SPME与GC/MS测定烟叶中的生物碱

采用固相微萃取吸附烟叶样品中的生物碱 ,通过GC/MS进行生物碱的分离鉴定。此法用于烟叶生物碱的分析测定 ,极大简化了烟叶样品的前处理过程 ,缩短了整个分析测定时间。分析结果稳定可靠 ,具有较高的可信度和可比性     

杭白菊浸膏热裂解产物的GC/MS分析

用热失重(TG)技术以及在线热裂解(Py)技术对杭白菊浸膏热裂解产物进行了研究。TG曲线显示主要失重区间在120~620℃,质量损失高达87%,选取了失重比较大的几个温度点(300、400、550、620℃)和800℃作为裂解温度,以气相色谱-质谱法(GC/MS)分析其在不同温度下的裂解产物,并对添加不同量杭白菊浸膏的中试卷烟进行了评吸。结果表明:300、400、550、620、800℃裂解温度下检测到的挥发性热裂解产物分别为20种、29种、28种、26种,21种;550℃下杭白菊裂解产物主要是醛类、酮类、酯类和呋喃类物质;550℃时开始出现有害物质,且有害物质的量随着温度的升高而提高;杭白菊浸膏能够显著改善卷烟抽吸品质,赋予卷烟一种特殊的自然风味。     

多功能柱净化液相色谱–质谱–质谱法测定牛奶中黄曲霉毒素M_1

建立了简单、快速测定牛奶中黄曲霉毒素M1的液相色谱–质谱–质谱确证方法。样品经乙腈/水溶液(V/V,86/14)提取,226多功能柱净化,离心、吹干、定容和过滤,高压液相Xtera色谱柱(150 mm×2.1 mm×5μm)分离,选用0.1%甲酸溶液和乙腈/甲醇(V/V,50/50)作为流动相,采用外标法定量。结果经方法学研究验证,LOD=0.15 ng/mL,LOQ=0.5 ng/mL,线性相关系数R=0.9961;两种浓度加标回收率为71.5%和83.5%,相对标准偏差为2.7%和8.4%。该方法具有预处理简单、检测速度快、灵敏度高的优点,可适用于牛奶中黄曲霉毒素M1的确认和准确定量检测。     

Determination of Bile Acids in Piglet Bile by Solid Phase Extraction and Liquid Chromatography-Electrospray Tandem Mass Spectrometry

An LC/MS/MS‐based method was developed for the determination of individual bile acids (BA) and their conjugates in porcine bile samples. The C18‐based solid‐phase extraction (SPE) procedure was optimized so that all 19 target BA and their glycine and taurine conjugates were collected with high recoveries for standards (89.1–100.2 %). Following this, all 19 compounds were separated and quantified in a single 12 min chromatographic run. The method was validated in terms of linearity, sensitivity, accuracy, precision, and recovery. An LOD in the low ppb range with measured precisions in the range of 0.5–9.3 % was achieved. The recoveries for all of the 19 analytes in bile samples were all >80 %. The validated method was successfully applied to the profiling of BA and their conjugates in the bile from piglets treated with exogenous glucagon‐like peptide‐2 (GLP‐2) in a preclinical model of neonatal parenteral nutrition‐associated liver disease (PNALD). The method developed is rapid and could be easily implemented for routine analysis of BA and their conjugates in other biofluids or tissues.     

液相色谱-串联质谱法测定进出口人参、西洋参中蚜灭磷等6种农药

建立了人参、西洋参中凝胶色谱-固相萃取-液相色谱-串联质谱法测定蚜灭磷、吡虫啉、涕灭威、甲基内吸磷、甲硫威、辛硫磷6种农药的分析方法。样品经丙酮超声提取,凝胶色谱(GPC)净化后,固相萃取(SPE)净化,在HPLC/MS/MS多反应监测(MRM)模式下进行了定性和定量分析方法。在上述检测方法条件下,所测的6种农药的最低检出限为0.01 mg/kg,回收率范围为79.2%~107.3%,线性范围为0.01~0.2 mg/kg。     

Ultra‐Performance Liquid Chromatography‐Mass Spectrometry Analysis of Free and Esterified Oxygenated Derivatives from Docosahexaenoic Acid in Rat Brain

Docosahexaenoic acid (DHA), a prominent long‐chain fatty acid of the omega‐3 family, is present at high amount in brain tissues, especially in membrane phospholipids. This polyunsaturated fatty acid is the precursor of various oxygenated lipid mediators involved in diverse physiological and pathophysiological processes. Characterization of DHA‐oxygenated metabolites is therefore crucial for better understanding the biological roles of DHA. In this study, we identified and measured, by ultrahigh‐performance liquid chromatography coupled with tandem mass spectrometry, a number of oxygenated products derived from DHA in exsanguinated and nonexsanguinated brains. These metabolites were found both in free form and esterified in phospholipids. Interestingly, both (R)‐ and (S)‐monohydroxylated fatty acid stereoisomers were observed free and esterified in phospholipids. Monohydroxylated metabolites were the main derivatives; however, measurable amounts of dihydroxylated products such as protectin DX were detected. Moreover, exsanguination allowed discriminating brain oxygenated metabolites from those generated in blood. These results obtained in healthy rats allowed an overview on the brain oxygenated metabolism of DHA, which deserves further research in pathophysiological conditions, especially in neurodegenerative diseases.     

Mass Spectrometry,Ion Mobility Separation and Molecular Modelling: A Powerful Combination for the Structural Characterisation of Substituted Cyclodextrins Mixtures

When working on the synthesis of substituted cyclodextrins (CDs), the main challenge remains the analysis of the reaction media content. Our objective in this study was to fully characterise a complex isomers mixture of Lipidyl-βCDs (LipβCD) obtained with a degree of substitution 1 (DS = 1) from a one-step synthesis pathway. The benefit of tandem mass spectrometry (MS/MS) and ion mobility separation hyphenated with mass spectrometry (IM-MS) was investigated. The MS/MS fragment ion‘s relative intensities were analysed by principal component analysis (PCA) to discriminate isomers. The arrival time distribution (ATD) of each isomer was recorded using a travelling wave ion mobility (TWIM) cell allowing the determination of their respective experimental collision cross section (CCS_exp). The comparison with the predicted theoretical CCS (CCS_th) obtained from theoretical calculations propose a regioisomer assignment according to the βCD hydroxyl position (2, 3, or 6) involved in the reaction. These results were validated by extensive NMR structural analyses of pure isomers combined with molecular dynamics simulations. This innovative approach seems to be a promising tool to elucidate complex isomer mixtures such as substituted cyclodextrin derivatives.     

Analysis of Ink/Coating Penetration on Paper Surfaces by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) in Conjunction with Principal Component Analysis (PCA)

Time-of-Flight Secondary ion mass Spectrometry (ToF-SIMS), in conjunction with Principal Component Analysis (PCA), has been used to characterize the spatial distribution of the chemical components of ink, both on the surface and in the Z-direction of coated papers. Preliminary work was performed on commercial ink-jet printing paper and on commercially available photopaper to establish that ToF-SIMS, in conjunction with PCA, could help characterise ink/coating distribution. To illustrate further that ToF-SIMS/PCA could differentiate the individual components making up the ink, pigment-based and dye-based inks were applied to two coated papers (PCC + SA and PCC + starch + PVA) using an inkjet printer. This approach shows that high spatially resolved images obtained by ToF-SIMS allows a depth profile to be obtained, thereby allowing the correlation between ink distribution at the surface and in the Z-direction to be evaluated in relation to the coating formulation.     

Analysis of Ink/Coating Penetration on Paper Surfaces by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) in Conjunction with Principal Component Analysis (PCA)

Time-of-Flight Secondary ion mass Spectrometry (ToF-SIMS), in conjunction with Principal Component Analysis (PCA), has been used to characterize the spatial distribution of the chemical components of ink, both on the surface and in the Z-direction of coated papers. Preliminary work was performed on commercial ink-jet printing paper and on commercially available photopaper to establish that ToF-SIMS, in conjunction with PCA, could help characterise ink/coating distribution. To illustrate further that ToF-SIMS/PCA could differentiate the individual components making up the ink, pigment-based and dye-based inks were applied to two coated papers (PCC + SA and PCC + starch + PVA) using an inkjet printer. This approach shows that high spatially resolved images obtained by ToF-SIMS allows a depth profile to be obtained, thereby allowing the correlation between ink distribution at the surface and in the Z-direction to be evaluated in relation to the coating formulation.     

液相色谱-串联质谱法测定进出口多种食用活动物体液及肉中四环素类药物残留量

建立了固相萃取-液相色谱-串联质谱法测定多种食用活动物猪、牛和羊的尿液及其血液,鸡的血液,鱼肉、虾肉、蛇肉和田螺肉中4种四环素类药物的分析方法。所测样品经0.1 mol/L Na2EDTA-Mcllvain缓冲溶液(p H 4.0(±0.5))提取后,以Oasis HLB固相萃取柱净化富集,在HPLC/MS/MS多反应监测(MRM)模式下进行了定性和定量分析。在上述检测条件下,所测的4种四环素类药物的最低检出限为1.00μg/kg,平均回收率为88.50%~96.70%,线性范围为1.00~100.00μg/L。     

气相色谱-质谱法分析杜克蓝莓果实挥发油的化学成分

用常规水蒸气蒸馏法提取杜克蓝莓果实中的挥发油,并用气相色谱-质谱法分析了其化学成分。共分离鉴定出32种化学成分,主要为2,4-二叔丁基苯酚〔相对质量分数(下同),16.54%〕、二棕榈酸抗坏血酸酯(13.48%)、环十二烷(7.37%)、8-甲基-十七烷(7.25%)、7,9-二叔丁基-1-氧杂螺[4.5]癸-6,9-二烯-2,8-二酮(6.39%)、8-己基-十五烷(6.15%)、(E)-9-十八烯(5.60%)、正二十四烷(4.38%)、十四酸(4.38%)、2,6-二叔丁基对苯醌(2.25%)和壬胺(2.07%)。