Animal Bioscience Research Department, Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland.
Animal Bioscience Research Department, Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Dunsany, Co. Meath, Ireland; School of Veterinary Medicine, Veterinary Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland.
Theriogenology. 2018 Jul 1;114:301-307. doi: 10.1016/j.theriogenology.2018.04.008. Epub 2018 Apr 12.
Current bovine pregnancy detection methods are not reliable until at least day 28 post artificial insemination (AI). The bovine estrous cycle is approximately 21 days; consequently, producers miss an opportunity to rebreed at the next estrous event. Therefore, commercial interest exists for the discovery of novel biomarkers of pregnancy which could reliably detect pregnancy status at or before day 21 of pregnancy. The objective of the present study was to use liquid chromatography tandem mass spectrometry (LC-MS/MS) to perform a global, label-free, proteomics study on (i) milk whey and (ii) extracellular vesicle (EV) enriched milk whey samples, from day 21 of pregnancy, compared with day 21 of the estrous cycle, in order to identify potential protein biomarkers of early pregnancy. The estrous cycles of 10 dairy cows were synchronized, they went through one (control) estrous cycle and these cows were artificially inseminated during the following estrus. These cows were confirmed pregnant by ultrasound scanning. Milk whey samples were collected on day 21 of the estrous cycle and on day 21 post AI. Milk whey samples and EV enriched milk whey samples were analyzed by LC-MS/MS and subsequent analyzes of the label-free quantitative data was performed in MaxQuant and Perseus. Four proteins (APOB, SPADH1, PLIN2 and LPO) were differentially expressed between the proteomes of milk whey from day 21 of pregnancy and day 21 of the estrous cycle (P < 0.05). Ten proteins (PIGR, PGD, QSOX1, MUC1, SRPRA, MD2, GAPDH, FOLR1, GPRC5B and HHIPL2) were differentially expressed between the proteomes of EV enriched milk whey from day 21 of pregnancy and day 21 of the estrous cycle (P < 0.05). These proteins are potential milk whey biomarkers of early pregnancy.
目前，牛的妊娠检测方法在人工授精后至少第 28 天才能可靠进行。牛的发情周期约为 21 天；因此，生产者错过了在下一次发情时再次配种的机会。因此，人们对发现新的妊娠生物标志物非常感兴趣，这些标志物可以在妊娠第 21 天或之前可靠地检测妊娠状态。本研究的目的是使用液相色谱串联质谱（LC-MS/MS）对妊娠第 21 天的牛奶乳清和（ii）富含细胞外囊泡（EV）的牛奶乳清样本进行全面、无标记的蛋白质组学研究，与发情周期的第 21 天相比，以鉴定早期妊娠的潜在蛋白质生物标志物。10 头奶牛的发情周期被同步，它们经历了一个（对照）发情周期，在随后的发情期进行了人工授精。这些奶牛通过超声扫描确认怀孕。在发情周期的第 21 天和人工授精后的第 21 天收集牛奶乳清样本。使用 LC-MS/MS 分析牛奶乳清样本和富含 EV 的牛奶乳清样本，随后在 MaxQuant 和 Perseus 中对无标记定量数据进行分析。在妊娠第 21 天的牛奶乳清和发情周期第 21 天的牛奶乳清的蛋白质组中，有 4 种蛋白质（APOB、SPADH1、PLIN2 和 LPO）表达不同（P<0.05）。在妊娠第 21 天的富含 EV 的牛奶乳清和发情周期第 21 天的富含 EV 的牛奶乳清的蛋白质组中，有 10 种蛋白质（PIGR、PGD、QSOX1、MUC1、SRPRA、MD2、GAPDH、FOLR1、GPRC5B 和 HHIPL2）表达不同（P<0.05）。这些蛋白质是早期妊娠牛奶乳清的潜在生物标志物。
