牛初乳与牛常乳中乳脂肪球膜蛋白质的组成及功能的对比研究

利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electropheresis,SDS-PAGE)将牛初乳与牛常乳中乳脂肪球膜蛋白质的组成部分进行分离鉴定,发现牛初乳与牛常乳中乳脂肪球膜蛋白质的组成存在较大的差异,且在牛初乳中鉴定出628种乳脂肪球膜蛋白质,牛常乳中鉴定出487种乳脂肪球膜蛋白质.由基因本体(gene ontology,GO)功能注释分析发现,在生物过程中生物调控作用是牛初乳和牛常乳中乳脂肪球膜的主要生物过程.在分子功能上,牛初乳的乳脂肪球膜蛋白质的绑定作用大于牛常乳.在细胞组成上,牛初乳乳脂肪球膜蛋白质参与细胞外区域远远大于牛常乳.通过京都基因与基因组百科全书系统(Kyoto Encyclopedia of Genes and Genomes,KEGG)代谢通路分析可知,牛初乳和牛常乳乳脂肪球膜蛋白质参与的代谢途径不同,表明牛初乳在日后的生产加工中更具有利用价值.     

人初乳与牛初乳中乳脂肪球膜蛋白质组成的对比研究

通过十二烷基硫酸钠-聚丙烯酰氨凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)将人初乳与牛初乳中乳脂肪球膜蛋白进行分离并结合液-质联用技术鉴定,在人初乳乳脂肪球膜蛋白中鉴定出l 076种蛋白质,牛初乳乳脂肪球膜蛋白中鉴定出682种蛋白质,其中人初乳中有757种特异性表达蛋白质,牛初乳中有363种特异性表达蛋白质,两者有319种相同表达蛋白质.通过基因本体(gene ontolpgy,GO)功能注释分析发现,人初乳乳脂肪球膜蛋白在生物过程中发挥的作用高于牛初乳,尤其表现在细胞组成组织功能上;在分子功能上,人初乳乳脂肪球膜蛋白主要体现在结合作用方面:在细胞组成上,与牛初乳乳脂肪球膜蛋白相比人初乳乳脂肪球膜参与的细胞组成均较多,其中在细胞胞内区的组成上参与最多.通过京都基因与基因组百科全书系统(Kyoto Encyclopedia of Genes and Genomes,KEGG)代谢通路分析可知,人初乳乳脂肪球膜蛋白中有15种蛋白参与了与消化吸收相关的KEGG通路-酶酵解.     

乳脂肪球膜的研究进展

乳脂肪球膜(milk fat globule membrane,MFGM)是包裹乳脂肪球的薄膜,由于其含有蛋白质和极性脂质的特殊组成被广泛用作食品或非食品领域中的乳化剂、稳定剂及营养物质载体等。此外,MFGM被证明具有丰富的营养价值。本文综述MFGM的结构、组成成分、分离制备及营养功能的研究进展,介绍MFGM制备脂质体包埋生物活性物质的新技术,为开发利用MFGM提供一定的参考依据。     

谷氨酰胺转氨酶可提高牛乳脂肪球的稳定性

日前德国科学家Hinz等以全脂乳及不同脂肪含量的调配乳为原料研究了谷氨酰胺转氨酶的交联作用对乳脂肪球的影响。结果显示，谷氨酰胺转氨酶的交联作用不会影响乳中脂肪球的大小，但可能会使乳脂肪球膜上的某些组分之间发生交联，进而阻碍乳脂肪球的聚集，     

过滤器辅助样品前处理法测定乳脂肪球膜蛋白质的研究

牛乳是世界上消费最广泛的乳类,并为消费者提供必需的营养物质。牛乳包括蛋白质,脂肪,糖类,维生素和矿物质。蛋白质是牛乳的重要组成部分,包括酪蛋白、乳清蛋白及乳脂肪球膜蛋白质。牛乳乳脂肪球被乳脂肪球膜覆盖,乳脂肪球膜是一个含有3层膜的膜结构,其上附着或者包含蛋白质。近些年来,对于乳中蛋白质的鉴定成为新的研究热点。随着蛋白质组学技术的发展,鉴定出的蛋白质的种类和数量都在增加。但是由于乳脂肪球膜的特殊性质,在牛乳乳脂肪球膜蛋白质的鉴定中,缺乏方便快捷及效果好的方法。作者运用过滤器辅助样品前处理法（FASP）结合纳升液相质谱（NanoLC-MS/MS）测定牛乳乳脂肪球膜蛋白质的种类和数量,共鉴别出169种蛋白质,是目前鉴别数量最大的一种方法。此方法的建立为今后乳脂肪球膜蛋白质研究领域提供一种方便快捷准确的试验工具。     

荷斯坦奶牛乳与牦牛乳的差异蛋白质组学分析

本试验利用蛋白质组学方法分析荷斯坦奶牛乳与牦牛乳乳清与乳脂肪球膜中的差异蛋白,比较功能差异,为开发不同品种牛乳提供帮助。通过离心法分离荷斯坦奶牛乳与牦牛乳的乳清与乳脂,分别提取蛋白,通过串联质谱标签（TMT）法进行蛋白质定性与定量分析,得到差异蛋白;对差异蛋白进行GO功能注释、KEGG代谢通路、蛋白质互作（PPI）等生物信息学分析。结果显示：牦牛乳的乳脂、乳蛋白、乳糖、总固形物和非乳脂固形物含量均显著高于荷斯坦奶牛乳（P<0.05）。在2种牛乳乳清中共鉴定到可信蛋白641种,在乳脂肪球膜中共鉴定到可信蛋白543种;在乳清中筛选出差异蛋白268种,其中牦牛乳比荷斯坦奶牛乳上调70种,下调198种;在乳脂肪球膜中筛选出差异蛋白267种,其中牦牛乳比荷斯坦奶牛乳上调68种,下调199种。GO功能注释及富集分析表明2种牛乳的乳清和乳脂肪球膜差异蛋白均主要富集在细胞外空间、小分子结合和免疫反应等方面。KEGG注释及富集分析表明2种牛乳的乳清和乳脂肪球膜差异蛋白主要富集在金黄色葡萄球菌感染、补体与凝血级联等通路。差异蛋白互作网络分析发现2种牛乳的乳清差异蛋白中甘油醛-3-磷酸脱氢酶（GAPD...     

饲料与环境对牛奶质量的影响

牛奶的成分分为水和固形物两大部分。固形物,包括脂肪、蛋白质、乳糖、矿物质和维生素等物质,各种物质含量的多少,影响着牛奶的质量。乳脂肪 乳脂率是衡量牛奶质量的重要指标。乳脂肪中绝大部分(约95％)是甘油三酸酯,另外还     

BTN1A1的研究进展

嗜乳脂蛋白(BTN1A1)是包括BTN2A1、BTN2A2、BTN3A1、BTN3A2和BTN3A3等多个成员的乳脂肪球膜蛋白家族;BTN1A1与乳脂滴的合成和分泌密切相关,研究主要对BTN1A1基因结构和功能进行综述,并为提高乳脂率提供一定的理论支持。     

乳脂肪球膜主要膜蛋白功能的研究进展

嗜乳脂蛋白（butyrophilin，Btn）、黄嘌呤氧化还原酶（XOR）和乳脂肪球表面生长因子8 （MFG-E8）是乳脂肪球膜的３种主要膜蛋白。最近的研究发现，Btn和XOR在乳脂肪的分泌阶段是必不可少的。而MFG E8在乳腺泌乳晚期及衰退期，对清除凋亡的乳腺上皮细胞起着重要作用。     

中国荷斯坦牛和藏黄牛乳上皮黏蛋白的遗传多态性

上皮黏蛋白MUC1是一种相对分子质量高的糖蛋白。在乳分泌过程中,MUC1随着包裹在乳脂肪球上的上皮细胞顶膜一同进入乳中[1]。对乳MUC1的研究显示,除小鼠外,人、牛、山羊、马、豚鼠等的乳MUC1在SDS聚丙烯酰胺凝胶电泳(SDS PAGE)上均表现出多态性,可显示来自双亲的2个共显性等位基     

Dimensional analysis of milk fat globules in sow milk: effects of the lactation stage and fat content and comparison with vaccine milk

To assess the differences in the granulometry of milk fat globules between swine and bovine species, milk samples from 30 lactating sows were analyzed for fat globule dimensions and compared with cow milk samples. Results showed differences between the fat globules: sow milk presents reduced globule diameters compared with cow milk (volume-weighted diameter 2.62 vs. 3.27 µm, p < 0.001) and reduced interglobular distance. A positive relationship was observed between milk fat content and globule diameter, while a slight, insignificant inverse trend was detected between the day of lactation and fat globule diameter. These complex interactions between milk lipids, globule membrane proteins, and globule dimensions provide a better understanding of digestion/absorption phenomena in the design of milk replacers.

     

乳脂肪球膜组成及分离提取技术研究进展

乳中的脂肪以脂肪球的形态存在，被3 层膜包裹，称之为乳脂肪球膜（milk fat globule membrane，MFGM）。由于MFGM生物学功能和乳化潜力的相关报道，MFGM引发了广泛研究。本文综述MFGM的结构、组成、分离提取方法以及不同分离提取方法中工艺参数变化对MFGM组成的影响。     

牛乳脂肪球粒径研究进展

乳中脂肪主要以乳脂肪球（milk fat globule，MFG）形式从哺乳动物的乳腺中分泌到乳中，MFG粒径从?0.2 μm到15.0 μm不等，不同粒径MFG影响新生儿的健康及乳制品的理化特性。MFG粒径主要由乳腺上皮细胞中的?脂滴调控，脂滴大小的调控因素包括细胞内甘油三酯水平及其合成与水解过程中参与的酶、膜磷脂、脂滴融合等。本文主要综述MFG的合成和结构、MFG粒径对牛乳营养及乳制品加工的影响、脂滴融合对MFG粒径的调控，为?MFG粒径的应用提供参考。     

Fat globule membrane of sow milk as a target for adhesion of K88-positive Escherichia coli

Membrane adhesion of K88-positive Escherichia coli was studied on intestinal brush-border membranes on 237 Finnish Landrace pigs. Forty-one per cent of the brush-border membrane preparations aggregated E. coli (positive adhesion). Similar dualism of adherence/nonadherence was observed on sow milk fat globule membranes. Washed milk fat globules (washed cream) can be used as a convenient source of material for adhesion studies. Bacterial adherence on to milk fat globules is evident as agglutination of the globules (dark-field microscopy). By this procedure the sows can be typed according to their receptor phenotype. This simple principle of fat globule agglutination due to receptors for K88-positive E. coli might be complicated by SigA-mediated bacterial adherence. Fat globule membranes were shown to contain SigA, which may act as a mediator of bacterial adherence onto fat globules. The significance of this adhesive property of milk fat globule might be to provide alternative receptors for E. coli thus preventing bacterial adhesion on to gastro-intestinal epithelium of the offspring. Sow milk fat globules can be used for typing E. coli for membrane adhesiveness. The adhesiveness of the strains showed a good correlation with the presence of the K88 antigen, as well as the hydrophobicity of the bacterial strain as determined by an association on Phenyl-Sepharose beads.     

共轭亚油酸诱导的奶牛低脂乳症中脂肪球膜甘油磷脂的组成差异分析

旨在分析共轭亚油酸(CLA)诱导奶牛低脂乳症对牛乳脂肪球膜甘油磷脂含量的影响.选取体况相近、泌乳中期的10头荷斯坦奶牛进行自身前后对照设计,试验期12 d,第1天至第6天每头牛饲喂基础日粮+CLA 400 g·d-1,第7天至第12天恢复为饲喂基础日粮,每天记录产奶量及采食量,分析乳成分及乳脂肪球(MFG)粒径参数,对...     

Association of bovine secretory immunoglobulins with milk fat globule membranes

Milk IgA was seen to be largely associated with milk fat globules ( of the sIgA in whole milk). Isolated fat globules became agglutinated by anti-IgA and to a lesser degree by anti-IgM but not by anti-IgG₁ or anti-IgG₂ (microscopic plate agglutination). Absorption studies using anti-bovine sIgA showed that the cream contained some 16 times more IgA than the repective whey. Isolated milk fat globule membranes released IgA and SC when treated by Triton X 100 as demonstrated by double gel diffusion. IgA was the only membrane-associated component showing cross-reactivity with serum proteins in immunoelectrophoresis. An antiserum prepared against fat globule membranes showed strong anti-IgA activity. IgA from whey became absorbed into washed cream. The specificity of MFGM associated immunity was demonstrated by analysing the capacity of cream, isolated from mastitic cows, to bind homologous labelled bacteria (cream-rising test).     

Bovine milk fat globules do not inhibit C5a chemotactic activity

The C5a complement fragment is a potent inflammatory molecule but its contribution to the inflammatory response of the mammary gland remains uncertain. One of the unresolved questions is the possible interference of whole milk with C5a. In this study, the chemotactic activity ofpurifled bovine C5a was tested in the presence of whole or skimmed milk. Milk from healthy glands acted as a chemoattractant, which could mask any inhibitory effect on C5a activity. To circumvent milk activity, washed milk fat globules were incubated with optimal (1 nM) or suboptimal (0.1 nM) concentrations of C5a, and the eventual chemoattractant activity was measured. There was no reduction in C5a-induced migration through a polycarbonate filter or shape-change of neutrophils. The concentrations of C5a determined by ELISA in the fluid phase were not reduced after incubation with the fat globules. It can be concluded that bovine milk fat globules do not trap or degrade C5a. Although these results do not explain the inhibitory effect of whole milk in the C5a-induced recruitment of neutrophils in milk, they suggest that milk does not inhibit the second major activity of C5a (apart from chemotaxis), i.e. the stimulation of phagocytic and bactericidal activities of neutrophils.     

Measurement of phagocytosis of 32P-labeled Staphylococcus aureus by bovine leukocytes: lysostaphin digestion and inhibitory effect of cream.

A procedure to measure phagocytosis by blood and milk neutrophils was developed. One milliliter of heat-killed 32P-labeled Staphylococcus aureus ([32P]SA) (180-200 X 10(6) CFU), 1 ml of phosphate-buffered saline solution (PBSS), and 2 ml of serum, whole milk, skimmed milk, whey, or PBSS were incubated in duplicate for 60 minutes at 37 C. Isolated blood or milk nuetrophils (polymorphonuclear leukocytes (PMN), 25 X 10(6) cells/ml; 1 ml) were added and incubated at 37 C for 30 minutes. Unphagocytosed [32P]SA organisms were lysed by incubation with 5 ml of lysostaphin (10 U) at 37 C for 30 minutes, and the PMN and phagocytosed T2P]SA were removed by centrifugation. Radioactivity of the supernatant was determined in a scintillation spectrometer and was used in estimate the percentage of [32P]SA phogocytosed. With this procedure, 25 assays in duplicate could be conducted each day with an expected coefficient of variation between duplicates of 5.6%. Blood PMN phagocytosed 80, 44, 74, 72, and 11% of the [32P]SA when incubated in serum, whole milk, skimmed milk, whey, and PBSS, respectively. Mik PMN phagocytosed 78, 44, 72, 74, and 22%, respectively. The addition of cream to either skimmed milk or serum reduced phagocytosis of [32P]SA by both blood and milk PMN. The inhibitory effect of cream was verified by the microscopic observation that PMN containing large quantities of ingested fat contained fewer S aureus. Seemingly, PMN upon entering the alveoli of the mammary gland become less efficiently phagocytic for bacteria, because of the presence of milk fat globules. This phef intramammary infection by invading mastitic pathogens.     

日粮组成对牛奶中乳成分合成与调控机制影响的研究

牛奶中乳蛋白和乳脂肪含量的高低直接关系到牛奶的品质和风味。牛奶中乳蛋白主要可以分为酪蛋白和乳清蛋白两种类型,其合成代谢过程均受到mTOR信号分子通路、JAK-STAT信号分子通路、GCN2-eIF2a信号分子通路的影响。牛奶中乳脂肪主要为三酰基甘油酯、磷脂等,对于牛奶的营养和风味均有重要影响,其受到脂肪酸相关酶ACACA、FAS、SCD1的调控。饲料营养是影响牛奶中乳蛋白和乳脂肪的关键因素之一,包括精粗饲料配比及饲料添加剂的应用等方面。本文对牛奶中乳蛋白和乳脂肪的合成调控机理,及日粮组成对其的影响机制进行阐述,为改善乳品质提供参考。