Proteomic Analysis of the Follicular Fluid of Tianzhu White Yak during Diestrus

The aim of this study was to identify differentially expressed proteins in the follicular fluid of Tianzhu white yak during diestrus. Follicles obtained from female yak were divided into four groups according to their diameter: 0–2, 2–4, 4–6 mm, and greater than 6 mm. The follicular fluid was directly aspirated from the follicles and mixed according to follicular size, and two-dimensional gel electrophoresis was carried out on the crude follicular fluid samples. Thirty-four differentially expressed spots were generated from these four sizes of follicles. Fourteen of these spots were analyzed by MALDI-TOF/TOF-MS and identified as: AS3MT, VDP, ANKRD6, C10orf107 protein, MRP4, MAPKAP1, AGO3, profilin-β-actin, SPT2 homolog, AGP, AR, RNF20, obscurin-like-1, and one unnamed protein. These proteins were first reported in follicular fluid, in addition to VDP and AGP. Based on existing knowledge of their function and patterns of expression, we hypothesize that most of these differentially expressed proteins play a role in ovarian follicular growth and development, dominant follicle selection, or follicular atresia and development of oocytes; however, the function of the other differentially expressed proteins in reproduction remains ambiguous.     

Proteomic analysis of differentially expressed proteins in bovine milk during experimentally induced Escherichia coli mastitis

The objectives of the current study were to profile changes in protein composition using 2-dimensional gel electrophoresis on whey samples from a group of 8 cows before and 18 h after infection with Escherichia coli and to identify differentially expressed milk proteins by peptide sequencing using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry post source decay. Only proteins present in whey fractions of all 8 cows were sequenced to avoid reporting a protein response unique to only a subset of infected cows. Despite the overwhelming presence of casein and β-lactoglobulin, the low abundance proteins transthyretin, lactadherin, β-2-microglobulin precursor, α-1-acid glycoprotein, and complement C3 precursor could be identified in whey samples from healthy cows. Whey samples at 18 h postinfection were characterized by an abundance of serum albumin, in spots of varying mass and isoelectric point, as well as increased transthyretin and complement C3 precursor levels. Also detected at 18 h postinoculation were the antimicrobial peptides cathelicidin, indolicidin, and bactenecin 5 and 7, and the proteins β-fibrinogen, α-2-HS-glycoprotein, S100-A12, and α-1-antiproteinase. Most notable was the detection of the acute phase protein α-1-acid glycoprotein in mastitic whey samples, a result not previously reported. In contrast to methods used in previous proteomic analyses of bovine milk, the methods used in the current study enabled the rapid identification of milk proteins with minimal sample preparation. Use of a larger sample size than previous analyses also allowed for more robust protein identification. Results indicate that examination of the protein profile of whey samples from cows after inoculation with E. coli could provide a rapid survey of milk protein modulation during coliform mastitis and aid in the identification of biomarkers of this disease.     

超高压对食品中微生物的影响

超高压是一种新型食品加工技术,已广泛应用于食品的非热加工。在超高压条件下微生物的细胞壁、细胞膜被破坏,引起细胞形态结构的改变;微生物细胞内的结构蛋白、酶等在超高压条件下被钝化,导致微生物正常的代谢功能和增殖能力被破坏;在超高压条件下微生物的蛋白组和基因组也产生了一定的变化,许多与抗逆有关的蛋白质和基因表达上调。     

碰撞诱导解离和高能碰撞解离方式进行蛋白质组学分析的比较

为了比较碰撞诱导解离（collision induced dissociation,CID）和高能碰撞解离（high energy collision dissociation,HCD）两种离子裂解模式在蛋白质组学分析方面的差异,分别应用这两种模式对牛血清白蛋白和细胞裂解物进行分析。通过比较所鉴定到的多肽和蛋白数目,发现在牛血清白蛋白中,HCD碎裂方法所得的谱图匹配率和多肽Mascot得分均较高,表明其质谱图质量较好。在复杂样品细胞裂解物分析中,CID碎裂方法鉴定到的谱图数、多肽数和蛋白数目均较多,表明该模式的灵敏度较高;HCD碎裂方法所得的谱图匹配率和Mascot得分均较高,表明其质谱图质量较好。因此,这两种模式均可用于大规模蛋白质组学分析,CID模式可提供更高的灵敏度,而HCD模式则可获得更高质量的质谱谱图。