Velásquez A E, Veraguas D, Cabezas J, Manríquez J, Castro F O, Rodríguez-Alvarez L L
Department of Animal Science, Faculty of Veterinary Sciences, Universidad de Concepcion, Avenida Vicente Mendez 595, Chillan, Chile.
Zygote. 2019 Dec;27(6):398-404. doi: 10.1017/S0967199419000509. Epub 2019 Oct 2.
Quality of in vitro-produced embryos is influenced by changes in gene expression in response to adverse conditions. Gene markers for predicting 'good embryos' do not exist at present. We propose that the expression of pluripotency markers OCT4-SOX2-NANOG in D9 (day 9) bovine demi-embryos correlated with development at D13 (day 13). Day 8 in vitro-produced blastocysts were split in two cloned halves, one half (D9) was subjected to analysis of pluripotency markers and the other was kept in culture until D13 of development. Embryo development was scored and correlated with its own status at D9 and assigned to one of two categories: G1, arrested/dead; or G2, development up to D13. SOX2 and NANOG expression levels were significantly higher in embryos from G1 and there was also negative correlation between SOX2 and embryo survival to D13 (G3; r = -0.37; P = 0.03). We observed a significant reduction in the expression of the three studied genes from D9 to D13. Furthermore, there was a correlation between the expression of pluripotency markers at D9 and embryo diameter and the expression of trophoblastic markers at D13 (TP1-EOMES-FGF4-CDX2-TKDP1). Finally, the quotient between the relative expression of SOX2 and OCT4 in the D9 blastocysts from G1 and G2 showed that embryos that were considered as competent (G2) had a quotient close to one, while the other group had a quotient of 2.3 due to a higher expression of SOX2. These results might indicate that overexpression of SOX2 at the blastocyst stage had a negative effect on the control of embryonic developmental potential.
体外生产胚胎的质量受基因表达变化影响，这些变化是对不利条件的响应。目前不存在预测“优质胚胎”的基因标志物。我们提出，第9天（D9）牛半胚中多能性标志物OCT4 - SOX2 - NANOG的表达与第13天（D13）的发育相关。将第8天体外生产的囊胚分成两个克隆半胚，其中一半（D9）用于分析多能性标志物，另一半继续培养至发育第13天。对胚胎发育进行评分，并将其与D9时自身状态相关联，分为两类：G1，停滞/死亡；或G2，发育至D13。G1组胚胎中SOX2和NANOG的表达水平显著更高，并且SOX2与胚胎存活至D13（G3）之间也存在负相关（r = -0.37；P = 0.03）。我们观察到从D9到D13，所研究的三个基因的表达显著降低。此外，D9时多能性标志物的表达与胚胎直径以及D13时滋养层标志物（TP1 - EOMES - FGF4 - CDX2 - TKDP1）的表达之间存在相关性。最后，G1和G2组D9囊胚中SOX2与OCT4相对表达的商表明，被认为有发育能力的胚胎（G2）的商接近1，而另一组由于SOX2表达较高，商为2.3。这些结果可能表明囊胚期SOX2的过表达对胚胎发育潜能的控制有负面影响。
