Application of proteomics to understand the molecular mechanisms behind meat quality

The proteome is expressed from the genome, influenced by environmental and processing conditions, and can be seen as the molecular link between the genome and the functional quality characteristics of the meat. In contrast to traditional biochemical methods where one protein is studied at a time, several hundred proteins can be studied simultaneously. Proteomics is a promising and powerful tool in meat science and this is reflected by the increasing number of studies emerging in the literature using proteomics as the key tool to unleash the molecular mechanisms behind different genetic backgrounds or processing techniques of meat. Thus understanding the variations and different components of the proteome with regard to a certain meat quality or process parameter will lead to knowledge that can be used in optimising the conversion of muscles to meat. At present, there has been focus on development of techniques and mapping of proteomes according to genotypes and muscle types. In the future, focus should be more towards understanding and finding markers for meat quality traits. This review will focus on the methods used in the published proteome analyses of meat, with emphasis on the challenges related to statistical analysis of proteome data, and on the different topics of meat science that are investigated.     

牛乳中蛋白质的快速测定

在用国标法测定牛乳中的蛋白质时,采用多孔井式电加热炉对牛乳样品进行消化,在加入适量廉价的催化剂后,将消化炉的电压调至220v时,消化一份牛乳样品仅需100～105min.试验结果表明,本方法具有精密(变异系数=0.62%)、准确、稳定、简单、快速、安全等优点,可以满足批量样品的检测需要.     

泌乳月份及部分乳成分与牛乳中体细胞数关系的相关性研究

本研究利用陕西省西安市草滩牛场第五奶牛场62头泌乳牛2003年8个月的DHI记录资料,对泌乳月份及部分乳成分与牛乳中体细胞数的关系进行了研究.结果表明,体细胞数与日产奶量,日产奶量与乳蛋白率、乳脂率呈极显著的负相关(P＜0.01),体细胞数与乳蛋白率与乳脂率之间无显著相关关系(P＞0.05),乳蛋白率与乳脂率呈极显著的正相关(P＜0.01).5、7和10月份样品平均体细胞数较高,分别为789×103mL-1,696×103mL-1、1031×103mL-1,3月份样品平均体细胞数最低为390×103mL-1.     

A proteomic approach to detect lactosylation and other chemical changes in stored milk protein concentrate

Milk proteins undergo chemical changes such as lactosylation, deamidation and protein cross-linking during processing and storage of milk products. A proteomic technique combining two-dimensional gel electrophoresis and mass spectrometry was used to investigate chemical modifications to proteins, in milk protein concentrate (MPC80), during storage. Lactosylation, deamidation and protein cross-linking were observed on 2-DE gels. They were storage temperature-, humidity- and time-dependent. Lactosylated whey proteins were well separated on 2-DE in vertical stacks of spots. The masses of the spots varied by multiples of 324, indicating the attachment of lactose to lysine residues in the proteins. The trypsin-digested spots of α-lactalbumin were analysed by MALDI-TOF mass spectrometry, which indicated multiple lactosylation sites. The lactose adducts on gels were quantified by image analysis, allowing development of adducts over time to be monitored. The results show that proteomics can be used for the detection and quantification of chemical modifications to proteins in stored MPC80.     

牛奶蛋白纤维纯纺纱试验

为了探讨牛奶蛋白纤维纺纱工艺，根据牛奶蛋白纤维的性能特点和纺纱实践，分析了影响牛奶蛋白纤维成纱的主要因素。确定了合理的工艺参数，梳棉采用增大锡林针齿工作角，增大锡林与盖板隔距，并条采用“重加压，大隔距”工艺原则，粗纱选择较大捻系数，细纱采用不处理胶辊。从而提高成纱质量。     

Effects of tea polyphenols on the post-mortem integrity of large yellow croaker (Pseudosciaena crocea) fillet proteins

Tea polyphenols (TP) are known to be important for the post-mortem deterioration of fish muscle and can enhance food quality. To shed light on the influence of TP on the status of large yellow croaker muscle proteins, control and treated fillets (0.1% TP, 0.2% TP and 0.3% TP, w/v) were analysed periodically for myofibrillar protein functional properties (Ca²⁺-ATPase activity, surface hydrophobicity, total sulfhydryl content, emulsion stability index and rheological behaviour). Degradation of the myofibrillar protein myosin could be clearly observed; several proteins were also observed to vary in abundance following post-mortem storage for 25 days. The present study offers new evidence that TP have an effective impact on muscle protein integrity post-mortem.     

Proteins in longissimus muscle of Korean native cattle and their relationship to meat quality

Proteomic profiling by two-dimensional gel electrophoresis and mass spectrometry of longissimus dorsi muscle tissue from Korean native cattle identified seven proteins that are differentially expressed in animals producing low and high quality grade beef. The expression level of alpha actin is increased in high quality grade beef and the expression levels of T-complex protein 1 (TCP-1), heat shock protein beta-1 (HSP27), and inositol 1,4,5-triphosphate receptor type1 (IP3R1), a new protein to be associated with meat quality, are increased in low quality grade beef. In particular, the quantitation of HSP27 and IP3R1 by both silver staining and immunoblotting correlated well with intramuscular fat content, meat tenderness, and free calcium levels. The data suggest that HSP27 and IP3R1 are potential meat quality biomarkers and their identification provides new insight into the molecular mechanisms and pathways associated with overall beef quality.     

添加牛奶碱性蛋白牛奶对大鼠骨密度的影响

探讨添加牛奶碱性蛋白(MBP)牛奶对正常大鼠骨密度的影响。将50只SD大鼠分为低钙对照组、碳酸钙、低、中、高5个剂量组。分别采用含钙40,80,96mg/kg及含3.3,6.7,8mg牛奶碱性蛋白,检测体质量、骨密度、骨钙以及钙吸收率等指标。结果表明,各剂量组对大鼠体质量在3个月中未见显著差异;各剂量组大鼠股骨干重、股骨远心端骨密度、股骨中点骨密度、骨钙质量分数均明显高于低钙对照组;高剂量组的钙表现吸收率明显高于碳酸钙对照组。根据《保健食品检验与评价技术规范》推断,添加牛奶碱性蛋白的牛奶产品对大鼠具有增加骨密度作用。     

人胰液双向凝胶电泳分离技术的建立和优化

目的建立并优化人胰液蛋白质组的双向凝胶电泳分离方法。方法通过比较几种常用的体液处理方法,确定了一种适于人胰液的蛋白质样品处理方法。经过一维等电聚焦和二维SDS-PAGE电泳后,有效分离了人胰液蛋白质组。结果通过优化胰液蛋白质提取、上样量和固相IPG胶条分离范围的选择等步骤,建立了人胰液双向凝胶电泳的方法,并获得了分辨率较高、重复性较好的双向凝胶电泳图谱。结论丙酮沉淀与双向凝胶电泳技术的结合是研究人胰液蛋白质组的一种有效的方法。胰液双向凝胶电泳方法的优化可为今后开展疾病相关的胰液蛋白质组学研究提供技术基础。     

牛奶蛋白纤维氨纶包芯纱的生产

为了顺利生产牛奶蛋白纤维氨纶包芯纱,对各工序纺纱工艺参数进行了优选.生产前对牛奶蛋白纤维进行预处理,清梳工序采用低速度、大隔距、多梳少打、均匀混和、快转移、小张力的工艺原则,并条采用顺牵伸,粗纱适当加大捻度、减少后区牵伸倍数,细纱采用重加压、大后区隔距、小后区牵伸、小钳口隔距等技术措施.措施实施后,成纱质量好,条干均匀.     

牛奶蛋白纤维混纺弹力纱的开发

介绍了牛奶蛋白纤维的特性,牛奶蛋白纤维既有天然蚕丝的优良特性,又有合成纤维的性能特征,可纺性能良好,是一种全新的纺织材料.牛奶蛋白细号涤纶棉混纺弹力包芯纱的生产采用牛奶蛋白纤维与细号涤纶棉包混和制条,再与棉纤维精梳条混和纺制氨纶包芯纱的工艺路线.     

Tencel纤维牛奶蛋白纤维混纺纱的生产

为开发Tencel纤维牛奶蛋白纤维混纺纱，对纺纱工艺流程和工艺参数进行了设计和优选。根据两种原料纤维长度和细度较为接近、都不合杂质的特点，选择了在清棉工序进行混和的纺纱方案。通过对牛奶蛋白纤维进行预处理、优化纺纱各工序工艺参数、合理控制车间温湿度，成功开发出了适合于加工高档服饰的混纺纱线。     

牛奶蛋白纤维的吸湿性和电学性能研究

通过测量牛奶蛋白纤维和腈纶纤维的吸放湿平衡回潮率及纤维比电阻,对两种纤维的吸放湿性能和电学性能进行了对比研究,并通过软件拟合出两种纤维的吸放湿回归方程。实验结果表明,牛奶蛋白纤维的吸放湿平衡回潮率远高于腈纶纤维,吸湿滞后性显著;不同温湿度下牛奶蛋白纤维的质量比电阻小于腈纶纤维,且两种纤维的质量比电阻均随着湿度的增大而减小,随着温度的增加而增大。     

Comparative analysis of cells and proteins of pumpkin plants for the control of fruit size

Common pumpkin plants (Cucurbita maxima) produce fruits of 1-2kg size on the average, while special varieties of the same species called Atlantic Giant are known to produce a huge fruit up to several hundred kilograms. As an approach to determine the factors controlling the fruit size in C.?maxima, we cultivated both AG and control common plants, and found that both the cell number and cell sizes were increased in a large fruit while DNA content of the cell did not change significantly. We also compared protein patterns in the leaves, stems, ripe and young fruits by two-dimensional (2D) gel electrophoresis, and identified those differentially expressed between them with mass spectroscopy. Based on these results, we suggest that factors in photosynthesis such as ribulose-bisphosphate carboxylase, glycolysis pathway enzymes, heat-shock proteins and ATP synthase play positive or negative roles in the growth of a pumpkin fruit. These results provide a step toward the development of plant biotechnology to control fruit size in the future.     

棉绢丝牛奶蛋白纤维混纺弹力纱的开发

为开发棉绢丝牛奶蛋白纤维混纺弹力纱,根据原料的不同特点,重点对牛奶蛋白纤维进行预处理,优选了原料混和方案和混纺比,改装了弹力牵伸装置;同时优化纺纱各工序工艺参数、合理控制车间温湿度。通过关键技术的攻关,有效解决了成纱毛羽多、棉结多、成纱条干差等技术难题。使纺纱质量达到了客户要求。     

Proteomic analysis of semimembranosus and biceps femoris muscles from Bayonne dry-cured ham

The aim of the study was to delineate and compare the proteomic maps of two muscles of dry-cured ham: the biceps femoris and the semimembranosus. For this purpose, we used two-dimensional electrophoresis on a subcellular muscle fraction: insoluble protein in low ionic strength buffer. After protein identification by MALDI-TOF mass spectrometry and bioinformatic analyses, we found differences in expression levels in the two muscles. Seventy-three proteins or fragments were differentially expressed: 43 were over-represented in semimembranosus and 30 in biceps femoris. Although the study was performed on the insoluble protein fraction in low strength ionic buffer, protein and fragment identifications by mass spectrometry showed that most of the proteins were involved in energy metabolism. The differences observed between the two muscles can be explained by the differences in salt and moisture content in the course of dry-cured ham processing.     

纳米锌牛奶蛋白纤维与棉混纺纱的生产

为顺利纺制纳米锌牛奶蛋白纤维与棉50/50 14.7 tex混纺纱,选用1.5 dtex×38 mm的纳米锌牛奶蛋白纤维及优质新疆长绒棉进行混纺.根据两种纤维的特点,通过纺纱实践,对纺纱各工序进行了工艺优化:如纳米锌牛奶纤维在纺纱前加油剂,以消除静电;采用二步混并的方法,保证纱线正确混比;粗纱、细纱工序采用"低速、大隔距、小钳口"等,最终实现成纱质量优良的效果.     

基于质谱技术的蛋白质组学在水产品鉴伪中的研究进展

目前, 水产品类的物种掺假问题是食品安全领域广泛关注的热点, 这种掺假行为不仅欺骗消费者, 侵害其经济利益, 而且由于水产中隐藏的过敏原等, 对人类健康造成潜在危害。而基于质谱技术的蛋白质组学技术为食品真伪鉴别提供了一个新的思路, 能够对物种特异性生物标志物进行鉴定和定量, 为确证物种的真实属性、来源和含量提供了有力的技术平台。利用该技术发现并确定了多个物种的特异性生物标志物蛋白或肽段, 并成功将其应用于实际产品的真伪鉴别中。本文详细介绍了质谱技术、蛋白质组学定性、定量分析以及工作流程, 对该技术在常见的水产品, 如鱼、虾、贝类产品中的应用进行了综述, 并对发展方向和应用前景进行了展望, 为有效的鉴别水产品的真伪提供参考。     

Serum Protein Aggregates in the High-Heated Milk and Their Gelation Properties in Rennet-Induced Milk Gel

The influence of different heat treatments on the protein aggregates and changes in gelation properties of rennet-induced milk gels were investigated. In the heated milk, a visible difference in milk serum proteins was found resulting from the formation of protein aggregates. Meanwhile, the size of protein aggregates increased from 25 to 170 nm with increasing the intensity of heat treatment. Furthermore, the differences in textural variables of rennet gels were found among the heat treatments using the principal component analysis. The water holding capacity and cheese curd yield of rennet gels obtained from the heated milk were significantly greater than those of raw milk (p < 0.05). It was also found heat treatments above 80°C could endow rennet-induced milk gels with novel textural properties.     

Assay of advanced glycation endproducts in selected beverages and food by liquid chromatography with tandem mass spectrometric detection

Food and beverages contain protein glycation adducts--both early-stage adducts and advanced glycation endproducts. We determined the concentrations of glycation adducts in selected food and beverages by liquid chromatography with triple quadrupole mass spectrometric detection. Cola drink contained low concentrations of glycation free adducts, whereas pasteurised and sterilised milk were rich sources of heat-stable glycation adduct residues--Nepsilon-carboxymethyl-lysine and Nepsilon-carboxyethyl-lysine. Laboratory rodent food was a rich source of advanced glycation endproducts. Measurement of glycation adducts in 24 h urine samples of normal and diabetic rats indicated that < 10% of glycation adduct residue consumption was excreted. Induction of diabetes by streptozotocin led to a 2-fold increase in urinary excretion of Nepsilon-carboxymethyl-lysine and a 27-fold increase in urinary excretion of methylglyoxal-derived hydroimidazolone Ndelta-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine - the latter was decreased by high-dose thiamine therapy that also prevented the development of nephropathy. We conclude that cola drinks are a poor source of glycation adduct whereas thermally processed milk is rich in glycation adducts. Dietary glycation adducts residues probably have low bioavailability. Experimental diabetes is associated with a marked increase in exposure to endogenous formation of methylglyoxal-derived hydroimidazolone which is linked to the development of diabetic nephropathy.