Determination of IgG levels in bovine bulk milk samples from different regions of Spain

Colostrum addition to milk for consumption is an unlawful practice. Furthermore, the higher whey protein/casein ratio of colostrum compared with milk causes severe technological problems. A high concentration of immunoglobulins has been generally accepted as an index of colostrum presence in milk. In this work, the levels of IgG have been determined by a non-competitive ELISA in 3,248 bulk bovine milk samples from different regions of Spain throughout one year. The mean value for IgG concentration obtained from all the samples was 0.257±0.122 mg/ml, within the range generally considered as acceptable for mature milk. The mean concentration obtained for all the samples collected in the spring was 0.288±0.125 mg/ml, significantly higher than the values found at the other seasons. The finding of some samples with very high values of IgG would suggest that the determination of immunoglobulin levels periodically would be a good parameter to control milk quality.     

棉酚及其氧化物与牛血清蛋白相互作用的研究

利用紫外-可见吸收光谱和荧光光谱法研究棉酚及其氧化物与牛血清蛋白(bovine serum albumin,BSA)的结合作用。实验结果表明,棉酚及其氧化物与牛血清蛋白相互作用而引起的荧光猝灭机制均属于动态和静态的联合猝灭,BSA发射峰蓝移。通过计算各个结合参数得出:棉酚及其氧化物与BSA的结合常数在105数量级,说明棉酚及其氧化物与BSA有很强的结合,结合位点均为1;热力学参数ΔH0、ΔS0和ΔG0,表明棉酚及其氧化物与BSA结合的主要作用力为疏水作用力和氢键。根据Forster的非辐射能量转移理论,计算供体(BSA)与受体(棉酚及其氧化物)间的结合距离r分别为2.94 nm和3.12 nm,它们都能以能量转移的方式与BSA发生作用。紫外-可见光谱、同步荧光光谱和三维荧光光谱的研究结果表明,棉酚及其氧化物与BSA的结合引起了BSA的构象变化。     

Determination of testosterone esters and nortestosterone esters in animal blood serum by LC-MS/MS

A sensitive and robust confirmatory method for determination of steroid esters in blood serum is essential for reliable monitoring of possible illegal use of steroid hormones as growth promoters in meat production. A previously used sample preparation methodology was improved. The procedure consists of protein precipitation and removal of phospholipids by dispersive SPE Supel? QuE Z-Sep (Sigma-Aldrich) followed by clean-up on alumina column and LC-MS/MS measurement. The modified method has been validated according to Commission Decision 2002/657/EC. Validation parameters for determination of six testosterone esters and five nortestosterone esters in bovine and porcine blood serum are presented in this article. Decision limits for all analytes were observed in the range 10–20 pg mL^?1. The method described is considerably robust for bovine and porcine serum analyses and can be applied both for screening and confirmatory determination in routine residue monitoring.     

牛乳中不同部分蛋白质的组成及功能分析

本研究通过SDS-PAGE电泳将牛乳中不同蛋白质组成部分进行分离鉴定发现,乳脂肪球膜中存在201种蛋白,乳清中存在96种蛋白,酪蛋白中存在21种蛋白,乳粒中存在43种蛋白,其中有27种相同表达的蛋白。通过GO功能注释分析发现,在生物过程中乳脂肪球膜蛋白发挥的作用大于乳清、乳粒蛋白,尤其是生物的调控作用;在分子功能上,牛乳蛋白的主要分子功能是结合作用,其中乳脂肪球膜蛋白的结合作用最强;而乳粒蛋白参与的转运活性分子功能大于乳脂肪球膜、乳清蛋白。在细胞组成上,与乳清、乳粒蛋白相比乳脂肪球膜蛋白参与的细胞组成均较多,而在细胞膜的组成上乳粒蛋白参与较多。通过京都基因与基因组百科全书(KEGG)代谢通路分析可知,乳脂肪球膜、乳清、乳粒中的蛋白均参与过氧化物酶体增殖物激活受体信号通路。对牛乳蛋白质组成进行研究,不仅能够增加牛乳的利用率,并且为日后以乳脂肪球膜、乳粒蛋白作为原料生产乳制品提供理论依据。     

Factors affecting in vitro formation of tannin-protein complexes

In interaction of condensed tannins from Desmodium intortum and Lotus pedunculatus and tannic acid (hydrolysable tannin) with salivary mucoproteins (from sheep and goats), plant leaf proteins and bovine serum albumin were evaluated. These studies were carried out over a pH range of 2-0-9-0 and different inorganic ion conditions to simulate conditions in which dietary proteins would interact with tannins in a ruminant digestive tract. Insoluble tannin-protein interactions were found at pH 4–5–5–5 for bovine serum albumin and 3–5–5–5 for plant leaf protein. The present study showed that pH alone was not the sole determinant for tannin-protein complex formation, since tannin-protein complexation was found in the pH range 6-0–6-5 when different inorganic ions were added to the solutions. Insoluble complexes were not formed with salivary proteins, although precipitation by tannic acid was achieved at 5°C. This suggests that tannins may form soluble rather than insoluble complexes with salivary proteins. It was concluded that purified F1 leaf protein (the major protei occurring in leaf tissue) ought to be used as the test protein for evaluating tannin-protein interactions for in vitro assay procedures. Using this method it was calculated that 27–43% and 19–40% of available plant protein may interact with condensed tannins from Desmodium intortum and Lotus pedunculatus, respectively.     

Detection of bovine DNA in raw and heat-processed foodstuffs, commercial foods and specific risk materials by a novel specific polymerase chain reaction method

The identification of beef in animal foods is a major concern not only for the prevention of commercial fraud, but also to avoid safety risks deriving from the presence of prohibited bovine material that might be harmful to both human and animal health. Here we report a novel set of bovine-specific primers, CYTbos1 (forward) and CYTbos2 (reverse), which allow the specific amplification of a 115 base pair fragment of the bovine cytochrome b gene (cytb) between nt 844 (mitochondrial site 15,590) and nt 958 (mitochondrial site 15,704), no cross-reaction being observed with DNA from another 12 frequent commercial meat species. The polymerase chain reaction product obtained is cleaved specifically by endonucleases ScaI and TspE1 to achieve further confirmation evidence. The sensitivity of the proposed method was 0.025%. The CYTbos primers successfully detected bovine DNA in meat samples processed for 20 min at 133 °C/300 kPa or for 2 h at 121 °C. CYTbos primers also detected bovine DNA in heat-processed commercial meat products exhibiting a complex nature, as well as in bovine specific risk materials. The proposed polymerase chain reaction method, aimed at detecting a small and specific fragment of the bovine mitochondrial DNA, may be especially useful for the direct identification of bovine DNA in foodstuffs subjected to severe heating under overpressure conditions.     

聚丙烯酰胺凝胶电泳研究硫酸铵盐析分离猪血清IgG

通过聚丙烯酰胺凝胶电泳对硫酸铵盐析分离猪血清G型免疫球蛋白进行了研究，结果显示pH值7．4时，猪血清IgG主要沉淀区间为硫酸铵饱和度25-40％，10倍稀释猪血清IgG最佳硫酸铵沉淀参数为：pH值7．4，硫酸铵饱和度37％，此时IgG得率为80．5％，纯度为72．9％。沉淀的血清蛋白中还含有约12％白蛋白和9％其它γ-球蛋白。沉淀时IgG活性保持不变。     

黑果枸杞花青素提取物对大鼠急性痛风性关节炎的作用

为研究黑果枸杞花青素提取物(anthocyanin extract of Lycium ruthenicum Murr., AEL)对急性痛风性关节炎(acute gouty arthritis, AGA)大鼠的作用,将60只雄性SD大鼠,随机分为正常对照组、模型对照组、阳性对照组、AEL高剂量组(238.0mg/kg)和AEL低剂量组(59.5mg/kg),每组12只,分为2批,每批6只。第一批动物灌胃2周,第二批动物灌胃4周后,采用50mg/mL微晶型尿酸钠(microcrystalline sodium urate, MSU) 0.2mL注射到大鼠右踝关节诱导大鼠急性痛风性关节炎模型,评价AEL对AGA大鼠踝关节肿胀和跛行步态的改善效果。所有动物继续灌胃至5周,采用质量分数2.5%的氧嗪酸钾饲料喂食诱导高尿酸血症模型,测定造模2h、3h后大鼠的血清尿酸水平。研究发现,与模型对照组比较,灌胃2周,AEL高剂量能明显缓解大鼠造模6h后踝关节肿胀,改善跛行步态;灌胃4周,AEL高、低剂量均能明显缓解大鼠造模后6h、24h踝关节肿胀和改善造模6h后跛行步态,AEL高剂量还能明显改善造模24h后跛行步态;灌胃5周后,AEL高、低剂量均能明显抑制氧嗪酸钾导致的大鼠血清尿酸升高。结果表明,AEL能从抗炎和降尿酸两个方面对大鼠急性痛风性关节炎表现出明显改善作用。     

鸭血浆胆碱酯酶的分离纯化和性质的研究

将鸭血浆用0．2mol／L pH7．2磷酸盐缓冲溶液等体积稀释后，以硫酸铵为盐析剂进行二次盐析、再经DEAE-52离了交换层析和Sephadex G-200凝胶过滤层析对胆碱酯酶进行分离纯化，可获得电泳纯的胆碱酯酶，纯化倍数为278．5倍，酶活回收为17．8％。实验表明，该酶的最适温度为37℃，最适pH为7．8，有过量底物抑制现象。     

Sensory acceptability of raw and extruded bovine rumen protein in processed meat products

The use of bovine rumen protein (raw and extruded) as a replacement for extruded soy protein concentrate in three meat products (pork sausage, chicken hamburger, and kibbe) was investigated. Similarity between rumen and soy protein meat products was assessed using triangle tests and sensory acceptability evaluated by consumer panelists using a nine-point hedonic scale. The addition of raw rumen protein was detected in all meat product types tested, while extruded rumen protein was only detected in kibbe. The addition of raw rumen protein decreased the acceptability of pork sausage aroma and flavor, but improved kibbe appearance, texture and overall acceptability. The addition of extruded rumen protein reduced the acceptability of chicken hamburger texture, but improved pork sausage flavor. Replacement of soy protein by bovine rumen protein is feasible based upon sensory results, but depended upon its form and the type of meat product to which it was added.