Mass Spectrometry Imaging with Isomeric Resolution Enabled by Ozone‐Induced Dissociation

Mass spectrometry imaging (MSI) enables the spatial distributions of molecules possessing different mass‐to‐charge ratios to be mapped within complex environments revealing regional changes at the molecular level. Even at high mass resolving power, however, these images often reflect the summed distribution of multiple isomeric molecules, each potentially possessing a unique distribution coinciding with distinct biological function(s) and metabolic origin. Herein, this chemical ambiguity is addressed through an innovative combination of ozone‐induced dissociation reactions with MSI, enabling the differential imaging of isomeric lipid molecules directly from biological tissues. For the first time, we demonstrate both double bond‐ and sn‐positional isomeric lipids exhibit distinct spatial locations within tissue. This MSI approach enables researchers to unravel local lipid molecular complexity based on both exact elemental composition and isomeric structure directly from tissues.     

Diet–consumer nitrogen isotope fractionation for prolonged fasting arthropods

Nitrogen acquisition for cellular metabolism during diapause is a primary concern for herbivorous arthropods. Analyses of naturally occurring stable isotopes of nitrogen help elucidate the mechanism. Relevant articles have cited (58 times up to mid-June 2011) anomalously elevated δ¹⁵N (per mil deviation of ¹⁵N/¹⁴N, relative to atmospheric nitrogen=0 ‰) values (diet–consumer nitrogen isotope fractionation; up to 12 ‰) for a prolonged fasting raspberry beetle (Byturus tomentosus Degeer (Coleoptera: Byturidae)), which feeds on red raspberries (Rubus idaeus: δ¹⁵N=～+2 ‰). Biologists have hypothesised that extensive recycling of amino acid nitrogen is responsible for the prolonged fasting. Since this hypothesis was proposed in 1995, scientists have integrated biochemical and molecular knowledge to support the mechanism of prolonged diapausing of animals. To test the validity of the recycling hypothesis, we analysed tissue nitrogen isotope ratios for four Japanese arthropods: the shield bug Parastrachia japonensis Scott (Hemiptera: Cydnidae), the burrower bug Canthophorus niveimarginatus Scott (Hemiptera: Cydnidae), leaf beetle Gastrophysa atrocyanea Motschulsky (Coleoptera: Chrysomelidae) and the Japanese oak silkworm Antheraea yamamai (Lepidoptera: Saturniidae), all of which fast for more than 6 months as part of their life-history strategy. Resulting diet–consumer nitrogen isotope discrimination during fasting ranged from 0 to 7‰, as in many commonly known terrestrial arthropods. We conclude that prolonged fasting of arthropods does not always result in anomalous diet–consumer nitrogen isotope fractionation, since the recycling process is closed or nearly closed with respect to nitrogen isotopes.     

原子吸收光谱法测定饲料中铬和锌

采用WFX-1F2B2原子吸收分光光度计测定饲料中铬和锌,本方法通过选取用窄的光谱通带来减少复杂谱线的干扰;选用的富燃料还原火焰来抑制难熔氧化物的形成,提高检测的灵敏度.同时采用加入1%硫酸钠溶液及1%柠檬酸溶液的方法来消除Fe、Ca、Cu、Mg、Mn、Si等元素对铬的干扰;加入0.1%镧盐溶液来消除其对锌的干扰,而采用标准加入法的测定方式又消除了饲料基体中其他未知因素的影响,此法同时测定了饲料中的铬、锌的含量,快速、简便、准确性高、重现性好,获得了满意的效果.     

高效液相色谱-串联质谱法同时测定饲料中9种霉菌毒素及其代谢物

应用高效液相色谱-串联质谱(HPLC-MS/MS)技术,建立了同时检测饲料中9种霉菌毒素及其代谢物的分析方法。样品加入NaCl经乙腈-水(85∶15)振荡提取后,用TC-M160多功能净化柱净化,氮气吹干,用1mL乙腈-水(1∶1)定容,Agilen C18色谱柱(150×2.1mm,3.5μm)分离,采用正负离子同时扫描的多反应监测模式进行检测,外标法定量。方法检出限为0.11~0.60μg/L,在2.0~100.0μg/L基质添加浓度范围内呈现良好的线性关系,相关系数r0.998。5.0~50.0μg/L加标范围内回收率为67.0%~103.5%,相对标准偏差15%。该法简便、快速、灵敏度高,符合对饲料中霉菌毒素的检测要求,可为相关检测提供技术支持。     

船载C+S频段共面单脉冲天线设计与应用

本文针对船载测控站空间狭小的特点,介绍了一种C+S双频段共面天线的设计。设计时采用了计算机辅助技术,确定了天线反射面和馈源喇叭的形式及相对关系尺寸。并通过仿真计算和实测结果,该天线在两个频段的方向图指标均满足设计要求,达到了天线的小型化和双频段合建目的,满足航天测量船船载设备的使用要求。     

Targeted analysis and determination of β‐agonists,hormones, glucocorticoid and psychiatric drugs in feed by liquid chromatography with electrospray ionization tandem mass spectrometry

A comprehensive strategy combining a quantitative method was developed for 30 banned drugs including β‐agonists, hormones, glucocorticoid and psychiatric drugs in swine and chicken feeds. This rapid, simple and effective extraction method was based on matrix solid‐phase dispersion and electrospray ionization tandem mass spectrometry. The quantitative method was validated after previous statistical optimization of the main parameters of matrix solid‐phase dispersion. The limit of quantification of dopamine hydrochloride, chlormadinone acetate, melengestrol acetate, testosterone propionate, nandrolone and midazolam was 2 μg/kg and that of the other 24 drugs was 1 μg/kg. The recoveries of β‐agonists, hormones, glucocorticoid and psychiatric drugs spiked in swine and chicken feeds at a concentration range of 1–8 μg/kg were above 70.1% with inter‐day relative standard deviations less than 15.8%. The analytical strategy was applied to 100 feed samples collected from a local market in Wuhan (China). Clenbuterol, ractopamine and melengestrol acetate were identified and quantified at the level 0.2～3.5 μg/kg. The rapid and reliable method can be used to efficiently separate, characterize and quantify the residues of 30 banned drugs in swine and chicken feeds with advantages of simple pretreatment and environmental friendly nature.     

Hydrogels with Dynamically Controllable Mechanics and Biochemistry for 3D Cell Culture Platforms

Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix(ECM)are crucial to maintain cellular properties and behaviors.Thus,developing materials that can recapitulate the dynamic attributes of the ECM is highly desired for threedimensional(3 D)cell culture platforms.To this end,we sought to develop a hydrogel system that would enable dynamic and reversible turning of its mechanical and biochemical properties,thus facilitating the control of cell culture to imitate the natural ECM.Herein,a hydrogel with dynamic mechanics and a biochemistry based on an addition-fragmentation chain transfer(AFCT)reaction was constructed.Thiol-modified hyaluronic acid(HA)and allyl sulfide-modifiedε-poly-L-lysine(EPL)were synthesized to form hydrogels,which were non-swellable and biocompatible.The reversible modulus of the hydrogel was first achieved through the AFCT reaction;the modulus can also be regulated stepwise by changing the dose of UVA irradiation.Dynamic patterning of fluorescent markers in the hydrogel was also realized.Therefore,this dynamically controllable hydrogel has great potential as a 3 D cell culture platform for tissue engineering applications.     

Determination of 1-Lysine in Feeds by Fluorometric Method Based on 1-Lysine Oxidase

Abstract

Feeds or feed stuffs were hydrolyzed by acid to liberate 1-lysine. Homovanillic acid, peroxidase and 1-lysine oxidase were used to produce the fluorescence substance corresponding to 1-lysine. A computerized fluorometer was used for the measurement (up to 0.7 mg/1 of 1-lysine in the optical cell) and the time required for the measurement was about 1 min. The reproducibility was 1.0% in CV. Recovery tests and comparative tests against the conventional method were carried out. The effects of various experimental conditions on the fluorescence response were discussed.     

Radio-Detoxication of Olive Cake

The possibility of reducing toxic substances in olive by-products subjected as animal feed stuffs after oil extraction was investigated.

Total phenols in fresh olive fruits were 0.6%(fruit),0.7%(woody pit) and 0.31%in cakes after extraction. Irradiation of the olive cake powder at different doses (0,10,50 and 100 kGy) was done as a trial to remove the toxic substances. The results proved that irradiation decreases total phenols of olive cake from 0.31% (control) to 0.21, 0.16 and 0.08%at the doses used, respectively.

Subcutaneously injected ethanolic extract of unirradiated or irradiated (with 10 kGy) olive cake was lethal to the rats, while at 50 and 100 kGy all rats survived.

Liver and heart functions were measured in terms of activities of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), total protein and lactic acid dehydrogenase (LDH). In addition, plasma total lipids, cholesterol, triglycerides, glucose and blood heamoglobin were measured.

Results obtained showed that the toxic substances in olive cake induced toxicosis symptoms with the experimental rats treated with the irradiated (50 kGy) samples. The toxic compounds could be destroyed at an irradiation dose level of 100 kGy without harmful effects on liver and heart functions as well as heamoglobin, carbohydrate and lipid metabolisms. After further investigations, irradiation with 100 kGy shall be recommended to be used for detoxication of olive by-products for animal feeding without deleterious side effects.