Simultaneous steroids measurement in dogs with hyperadrenocorticism using a column-switching liquid chromatography-tandem mass spectrometry method

We developed an analytical method using an on-line column-switching liquid chromatography with triple quadrupole mass spectrometry (LC/MS/MS) for quantifying multiple steroids in serum. Using the developed method, we evaluated the serum concentration of nine steroids (cortisol, corticosterone, cortisone, 11-deoxycortisol, 21-deoxycortisol, deoxycorticosterone, progesterone, 17α-OH-progesterone and aldosterone) in dogs with hyperadrenocorticism (HAC). Serum was mixed with stable isotope internal standards and thereafter purified by the automated column-switching system. The limit of detection ranged 2–16 pg/ml for nine steroids. In the baseline samples, five steroids (cortisol, corticosterone, cortisone, 11-deoxycortisol, and 17α-OH-progesterone) were detected in all dogs. The concentrations of cortisone, 11-deoxycortisol, and 17α-OH-progesterone in dogs with HAC (n=19) were significantly higher those in dogs without HAC (n=15, P<0.02). After the adrenocorticotropic hormone stimulation test, six steroids (cortisol, corticosterone, cortisone, 11-deoxycortisol, 17α-OH-progesterone, and deoxycorticosterone) were above the limit of quantification in all dogs. Cortisol, corticosterone, cortisone, and deoxycorticosterone concentrations of dogs with HAC were significantly higher than those of dogs without HAC (P<0.02). In addition, 11-deoxycortisol and 17α-OH-progesterone concentration was higher in dogs with HAC than in dogs without HAC (P=0.044 and P=0.048, respectively). The on-line column-switching LC/MS/MS would be feasible for measuring multiple steroids in dog serum. The results suggest that cortisone, 11-deoxycortisol, and 17α-OH-progesterone would be related to HAC. Further studies are warranted to assess the clinical feasibility of steroid profile in dogs with HAC.     

饲料中主要霉菌毒素液相色谱串联质谱同时测定技术研究进展

饲料中霉菌毒素是我国畜禽养殖业中存在的主要危害因素之一。在饲料中常见、且对动物健康造成严重损害的霉菌毒素有6种,即黄曲霉毒素B1、呕吐毒素、T-2毒素、赭曲霉毒素A、玉米赤霉烯酮、伏马毒素B1。本文全面深入分析了国内外对这6种主要霉菌毒素检测技术的最新研究,对其方法过程和性能特点(提取剂、净化方法、定量方法、回收率等)进行了系统比较,为我国建立饲料中这6种霉菌毒素高效、经济、环境友好的同时检测技术标准提供经验。     

Fish proteins not lipids are the major nutrients limiting the use of vegetable ingredients in catfish nutrition

The objective of this study was to determine the major nutrient limiting growth and lipid metabolism in African catfish fed diets composed of vegetable ingredients. Four diets were formulated from contrasted meal (fish meal: FM; vegetable meal: VM) and oil (fish oil: FO; vegetable oil: VO) sources. Replacement of FO by VO did not affect specific growth rate (SGR) and feed efficiency, whereas lower values were recorded in the case of FM replacement. LC‐PUFAs muscle contents were higher in fish fed control FMFO diet than in fish fed vegetable ingredients. However, the decrease in docosahexaenoic acid (DHA) concentration in FMVO group was limited compared to VM groups despite the same low DHA level in those three diets. These results may suggest an activation of LC‐PUFA biosynthesis from PUFA precursors brought with vegetable oils in FMVO group. This hypothesize is reinforced by the significant stimulation of elovl5 gene expression in liver and intestine from fish fed FMVO. Therefore, this study demonstrated that African catfish is able to bioconvert LC‐PUFAs at a significant biological level when FO is replaced by VO whereas the use of plant proteins has strong detrimental effects on growth performances.     

What proteomic analysis of the apoplast tells us about plant–pathogen interactions

Plant pathogens have developed different strategies during their evolution to infect and colonize their hosts. In the same way, plants have evolved different mechanisms acting against potential pathogens trying to infect and colonize their tissues. Regulation of a wide variety of proteins is required in order to perceive the pathogen and to activate the plant defence mechanisms. The apoplast is the first compartment where these recognition phenomena occur in most plant–pathogen interactions, allowing the exchange of different molecules and facilitating inter‐ and intracellular communication in plant cells. Proteomic analysis of the apoplast in recent years has found the initial biochemical responses involved in pathogen recognition and early defence responses. However, this proteomic approach requires some specific experimental conditions to obtain an extract free of cytoplasmic proteins and nonprotein contaminants that affect the subsequent stages of separation and quantification. Obtaining the highest proportion of proteins from the apoplastic space in infected tissues requires different steps such as extraction of apoplastic washing fluids and preparation of total secreted proteins (protein precipitation, solubilization, separation and digestion). Protein identification using mass spectrometry techniques and bioinformatics tools identifying peptides for the extracellular exportation is required to confirm the apoplastic location. This review compiles the most commonly used techniques for proteomic studies, focusing on the early biochemical changes occurring in the apoplast of plants infected by a wide range of pathogens. The scope of this approach to discover the molecular mechanisms involved in the plant–pathogen interaction is discussed.     

重金属镉对三种潮虫的毒性效应及其回避行为研究

选择潮虫亚目三种常见种:普通卷甲虫Armadillidium vulgare(Latreille,1804),多霜腊鼠妇Porcellionides pruinosus(Brandt,1833)和中华蒙潮虫Mongoloniscus sinensis(Dollfus,1901)为研究对象,以农田自然土壤为实验土壤,人工添加重金属镉(Cd)进行毒理研究。结果表明:(1)急性毒性试验采取滤纸接触法和自然土壤法开展Cd对三种潮虫的急性毒性试验,三者的半致死浓度(LC50)大小关系为:A.vulgareP.pruinosusM.sinensis,说明不同潮虫对Cd的忍耐限度和敏感程度不同。(2)三种潮虫对Cd的富集强弱关系为:M.sinensisP.pruinosusA.vulgare。说明陆生等足类能存活于一定浓度的污染土壤中,但不同潮虫对Cd的富集能力不同。(3)三种潮虫对土壤中Cd均表现出明显的回避行为反应,回避能力大小关系为:A.vulgareP.pruinosusM.sinensis。与急性毒性试验的测试终点LC50相比,潮虫行为测试终点对土壤中重金属镉的反应更为敏感。根据实验结果,中华蒙潮虫体内Cd的富集量随着Cd浓度的增加呈上升趋势,所以其富集能力和耐受性强于普通卷甲虫和多霜腊鼠妇,在将来有望成为土壤重金属污染生物修复的首选动物类群。     

Development of liquid chromatography mass spectrometry method for analysis of organic N monomers in soil

The aim of this study was to develop an analytical procedure based on liquid chromatography-mass spectrometry (LC–MS) for analysis of monomeric organic N compounds in soil extracts. To benchmark the developed LC–MS method it was compared with a capillary electrophoresis–mass spectrometry (CE–MS) method recently used for analysis of small organic N monomers in soil. The separation was optimized and analytical performance assessed with 69 purified standards, then the LC–MS method was used to analyse soil extracts. Sixty-two out of 69 standards were analysable by LC–MS with separation on a hydrophilic interaction liquid chromatography column. The seven compounds that could not be analysed were strongly cationic polyamines. Limits of detection for a 5 μL injection ranged between 0.002 and 0.38 μmol L⁻¹, with the majority (49 out of 62) having limits of detection better than 0.05 μmol L⁻¹. The overall profile and concentration of small organic N monomers in soil extracts was broadly similar between LC–MS and CE–MS, with the notable exception of four ureides that were detected by LC–MS only. In soil extracts that had been concentrated ten-fold the detection and quantification of (some) organic N compounds was compromised by the presence of large amounts of inorganic salts. The developed LC–MS method offered advantages and disadvantages relative to CE–MS, and a combination of the two methods would achieve the broadest possible coverage of organic N in soil extracts.     

水产品中三聚氰胺含量的快速检测方法研究

[目的]参考国家标准建立水产品中三聚氰胺含量的检测方法。[方法]分剐用高效液相色谱法和液相色谱／质谱联用法检测水产品样品液中的三聚氰胺含量。[结果]高效液相色谱法和液相色谱／质谱联用法都能较好地检测三聚氰胺含量,但其检测限不同。利用高效液相色谱法检测三聚氰胺含量的检测限为2．0mg／kg,出峰时间为7．25min。利用液相色谱／质谱联用法检测三聚氰胺含量的检测限为0．01mg／kg。高效液相色谱法检测三聚氰胺含量的浓度-峰面积曲线为：y=22．3513＋46．3807x,R=0．9984。液相色谱／质谱联用法检测三聚氰胺含量的浓度-峰面积曲线为：y=39．7025＋16．2646x,R=0．9957。[结论]液相色谱／质谱联用法的检测时间更短,灵敏度更高,检测效果更好,但检测成本较高。高效液相色谱法检测效果略差,但更经济实用。