Plant Copper Amine Oxidases: Key Players in Hormone Signaling Leading to Stress-Induced Phenotypic Plasticity

Polyamines are ubiquitous, low-molecular-weight aliphatic compounds, present in living organisms and essential for cell growth and differentiation. Copper amine oxidases (CuAOs) oxidize polyamines to aminoaldehydes releasing ammonium and hydrogen peroxide, which participates in the complex network of reactive oxygen species acting as signaling molecules involved in responses to biotic and abiotic stresses. CuAOs have been identified and characterized in different plant species, but the most extensive study on a CuAO gene family has been carried out in Arabidopsis thaliana. Growing attention has been devoted in the last years to the investigation of the CuAO expression pattern during development and in response to an array of stress and stress-related hormones, events in which recent studies have highlighted CuAOs to play a key role by modulation of a multilevel phenotypic plasticity expression. In this review, the attention will be focused on the involvement of different AtCuAOs in the IAA/JA/ABA signal transduction pathways which mediate stress-induced phenotypic plasticity events.     

The assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines and some of their precursors

Herein, the assessment of commercial beef and chicken bouillons in terms of heterocyclic aromatic amines (HAAs) and some of their precursors was evaluated. Creatine and creatinine levels were ranged between 0.57–0.80 and 0.28–0.94 mg g⁻¹, respectively. Glutamic acid was found to be the most abundant amino acid in both bouillons. 2-amino-3,7,8-trimethylimidazo[4,5-ƒ]quinoxaline (7,8-DiMeIQx, up to 0.03 ng g⁻¹) was the only quantified analyte in beef bouillons, whereas it (up to 0.08 ng g⁻¹) was determined in addition to 2-amino-3-methylimidazo[4,5-ƒ]quinoxaline (IQx, up to 0.08 ng g⁻¹) in chicken bouillons. Creatine, creatinine and free amino acid composition did not have the capacity to initiate the formation of HAAs. Therefore, bouillons do not pose risk in terms of HAAs. However, it should be noted that multiple factors, such as the substrate amount and production conditions, may affect the results. Glutamic acid content is remarkable in commercial bouillons sold in Turkey.     

电喷雾质谱法示踪钨回收过程离子的转化路径

将环隙式离心萃取器(ACCs)与电喷雾飞行时间质谱(ESI-TOF-MS)相结合，在线监测了回收过程中的钨萃取行为(宏观)和钨形态的转化路径(微观)，发现宏观萃取反应和微观离子形态转化同时发生并相互补充。伯胺N1923萃取钨在144 s内即可达到萃取平衡，萃取率高达98%以上，同时，酸钨比n(H)/n(W)是一个关键变量，当酸钨比n(H)/n(W)=2.4时，全流程钨回收率超过93%。最后，得到了基于钨形态监测的萃取机理，同时，减少原料液中W1含量，增加W10含量，可有效提高钨回收效率。     

复合香辛料亚硝化抑制剂对西式培根品质的影响

研究对N-亚硝胺具有阻断作用的复合香辛料亚硝化抑制剂（composite spice nitrosation inhibitor，CSNI） 在西式培根中的应用效果。设计4 组实验：1）阴性对照（negative control，NC）组：以原料肉质量计，配 制由0.06%亚硝酸钠、9%食盐、1.5%复合磷酸盐、5%白糖等组成的腌制液，注射量为20%；2）阳性对照 （positive control，PC）组：在NC组基础上添加0.055%异抗坏血酸钠；3）CSNI组：在NC组中添加CSNI； 4）PC＋CSNI组：在PC组中添加CSNI。制成西式培根，分别对西式培根成品和烧烤（200 ℃，5 min）西式培根进 行感官评定、pH值、红度值（a*）、硫代巴比妥酸反应物（thiobarbituric acid reactive substances，TBARs）值、亚 硝酸盐残留量、生物胺含量及N-亚硝胺含量测定。结果表明：相比NC、PC组，PC＋CSNI组西式培根成品的感官 评分最高，TBARs值（0.24 mg/kg）、亚硝酸盐残留量（20.48 mg/kg）和生物胺总量（184.68 mg/kg）均处于较低 水平，CSNI对N-亚硝胺的形成（总量为9.29 μg/kg），特别是N-二甲基亚硝胺的形成有显著的阻断效果，且CSNI的 添加对产品的pH值和a*均未造成显著影响；西式培根烧烤后，由于水分和脂肪溶出，致使烧烤西式培根的亚硝酸 盐残留量、生物胺含量和N-亚硝胺含量总体呈升高趋势，但均未超过相关规定的限量值。     

液相色谱-串联质谱法测定腐乳中的生物胺

建立了一种使用液相色谱-串联质谱（LC-MS/MS）技术检测腐乳中9种生物胺的方法。样品经5%三氯乙酸水溶液提取后，进行液相色谱-串联质谱法测定，采用外标法定量。对检测方法进行方法学验证，9种生物胺在质量浓度为10～200 ng/mL范围内线性相关系数R2＞0.999，方法检出限为0.03 mg/kg，定量限为0.1 mg/kg，回收率在85%～101%之间，相对标准偏差（RSD）在0.9%～4.8%之间。该方法结果精密、准确、重复性好、操作简单，适用于腐乳中9种生物胺的测定。     

Polystyrene latex particles bearing primary amine groups via soap‐free emulsion polymerization

Polystyrene latexes were prepared in the presence of an amino‐containing functional comonomer, N‐(3‐aminopropyl)methacrylamide hydrochloride (APMH), via soap‐free batch emulsion polymerization initiated by the cationic initiator 2,2′‐azobis(2‐amidinopropane) dihydrochloride. These latexes were characterized by studying the influence of the ionic comonomers on the polymerization kinetics, particle size, surface charge density and colloidal properties. The synthesized latexes were monodisperse with a final size between 100 and 600 nm depending on the APMH concentration. The initial polymerization rate and the particle number increased in accordance with the Smith–Ewart theory for soap‐free styrene emulsion polymerization with a hydrophilic functional comonomer. The final functionalization rate of the particles has been particularly studied with the intention of fitting the prepared latexes to be used in the immobilization of biological molecules for biological sample preparation and diagnostic applications. © 2020 Society of Chemical Industry     

重组培根加工过程中N-亚硝胺及其前体物质含量的动态变化

为了明确重组培根加工过程中N-亚硝胺含量的动态变化及其影响因素，监测原料肉、腌制、蒸煮、烟熏加工环节中pH值及亚硝酸盐、生物胺、N-亚硝胺含量的动态变化，同时考察重组培根的感官品质。结果表明：随着加工的进行，重组培根pH值和亚硝酸盐残留量均呈现先上升后下降的趋势；在监测的8 种生物胺中，原料肉中仅检出精胺，随着重组培根加工的进行，生物胺的种类不断丰富，含量逐渐升高，烟熏显著加速了生物胺的生成；原料肉中仅检测出N-二甲基亚硝胺（N-nitrosodimethylamine，NDMA）和N-亚硝基吡咯烷（N-nitrosopyrrolidin，NPYR）；腌制后可检出N-甲基乙基亚硝胺（N-nitrosomethylethylamine，NMEA）、N-二丙基亚硝胺（N-nitrosodipropylamine，NDPA）、N-二丁基亚硝胺（N-nitrosodibutylamide，NDBA）和N-亚硝基哌啶（N-nitrosopiperidine，NPIP），NDMA含量超过了国标限量； 蒸煮后新增N - 二乙基亚硝胺（ N - n i t r o s o d i e t h y l a m i n e ，NDEA）和N-亚硝基吗啉（N- n i trosomorpholine，NMOR），且NDMA、NDPA、NDBA、NPIP含量显著升高（P＜0.05）；烟熏过程中N-亚硝胺总量显著增加（P＜0.05），烟熏6～9 h增幅最大；重组培根的感官评分随着烟熏时间的延长显著提高（P＜0.05）。综合食用安全性和感官评分，建议制作重组培根时选择腌制16 h，热熏法（55±2） ℃烟熏6h。     

Stability of the Gossypol-Amine Adducts Used for Chromatographic Measurement of Total and Isomeric Gossypol

The stability of the gossypol amine adducts used for chromatographic determination of gossypol was studied. After extraction and complexation with R-(−)-2-amino-1-propanol, the samples were diluted into an acetonitrile/phosphate buffer solution as described in AOCS Recommended Practice Ba 8a-99. The solutions were then stored under different conditions before being analyzed by reverse-phase chromatography. Samples stored in the dark at −80 °C or at −20 °C showed little change in peak size over 30 days. Samples stored in the dark at −4 °C or at room temperature showed a measurable reduction in gossypol peak size over the study period. Samples stored in the light at room temperature showed the greatest reduction with only 25% of the initial gossypol detectable after 30 days. The rate of degradation followed first-order kinetics. The rate of decrease in gossypol peak size did not differ for the different gossypol matrices studied, i.e., cottonseed kernels, cottonseed meal, or pure gossypol-acetic acid; nor did it differ for the individual gossypol enantiomers. The results indicate that these gossypol Schiff's base adducts can be transported on dry ice before chromatography with minimal concern for their stability.     

贮藏温度对青方腐乳生物胺和理化性质的影响

以市售的青方腐乳为原料，研究了开盖后贮藏在不同温度下其生物胺含量、水分活度（Aw）、pH值、氨基酸态氮的动态变化，探讨了生物胺与理化指标之间的相关性。结果显示，青方腐乳在不同温度下贮藏至15 d时总生物胺含量＞1 000 mg/kg，且组胺含量＞100 mg/kg，酪胺含量在贮藏至30 d时（除25 ℃第30天）＞100 mg/kg，均超过了相关标准推荐的限量值；在不同贮藏温度下，青方腐乳水分活度＞0.8，pH变化规律基本一致，在第15天达到最大，4 ℃贮藏时，氨基酸态氮含量随贮藏时间的延长而增大。相关性分析结果表明，理化指标的变化与生物胺存在一定的关系，pH与苯乙胺、尸胺、组胺和亚精胺呈极显著正相关（P＜0.01）。结果表明，为了食用安全，腐乳开盖后应尽量在15 d内食用完。