AgResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton 3240, New Zealand.
AgResearch Ltd., Ruakura Research Centre, Private Bag 3123, Hamilton 3240, New Zealand.
J Dairy Sci. 2018 Jan;101(1):736-751. doi: 10.3168/jds.2017-12845. Epub 2017 Nov 2.
A complex interaction between the developing bovine embryo and the growth potential of the uterine milieu it inhabits results in an embryo capable of developing past the maternal recognition stage and on to a successful pregnancy. Previously, we observed variation in the lengths of embryos recovered 8 d after bulk transfer of Day 7 in vitro-produced (IVP) blastocysts into the same uterus. Potential causes of the differential embryonic growth were examined and modeled using 2 rounds of bulk (n = 4-6) IVP transfers and recovery of these embryos 8 d later. Morphological and gene expression measurements of the embryos were determined and the progesterone concentration of the cows was measured throughout the reproductive cycle as a reflection of the status of the uterine environment. These data were used to develop and evaluate a model that describes the interaction between the uterine environment and the growth rate of the developing embryo. Expression of 6 trophectoderm genes (IFNT, TKDP1, PAG11, PTGS2, DKK1, and PDPN) was correlated with conceptus length. The model determined that if the embryo develops to blastocyst stage, the uterine environment, driven by progesterone, is a more important component than blastocyst size in the stimulation of embryonic growth rate to ensure adequate interferon tau (IFNT) for pregnancy recognition. We detected an effect of Day 7 progesterone on the expression of all 6 genes, embryonic disc size, and trophectoderm length on Day 15. We also found effects of embryo transfer size on trophectoderm length and expression of IFNT and PAG11 on Day 15. Lower energy balance over the period from transfer to recovery was associated with reduced embryo growth to Day 15, and this effect was independent of progesterone. Energy balance also affected expression of PDPN and TKDP1 on Day 15. We observed an effect of energy balance from transfer to recovery on embryo survival in cows with partial embryo losses, where embryo factors dominate embryo survival, with cows with greater energy balance having lower embryo losses. This effect was independent of energy balance 40 d before transfer and suggests that energy balance has direct, immediate effects on the embryo and maternal environment during this period. Furthermore, energy balance effects on embryo survival in cows with partial embryo losses were largely mediated by expression of TKDP1, PAG11, and PDPN. These results provide candidate signaling pathways for the effect of progesterone and energy balance on embryo growth and survival.
牛胚胎的发育与它所居住的子宫环境的生长潜力之间存在复杂的相互作用,导致胚胎能够发育到母体识别阶段,并成功怀孕。此前,我们观察到在将第 7 天的体外受精 (IVP) 囊胚批量转移到同一子宫后 8 天回收的胚胎长度存在差异。通过两轮批量 (n = 4-6) IVP 转移和 8 天后回收这些胚胎,检查并模拟了胚胎生长差异的潜在原因。对胚胎进行形态学和基因表达测量,并在整个生殖周期中测量牛的孕酮浓度,以反映子宫环境的状态。这些数据用于开发和评估一个描述子宫环境与发育中胚胎生长速度之间相互作用的模型。6 个滋养层基因 (IFNT、TKDP1、PAG11、PTGS2、DKK1 和 PDPN) 的表达与胚胎长度相关。该模型确定,如果胚胎发育到囊胚阶段,由孕酮驱动的子宫环境是刺激胚胎生长速度的更重要组成部分,以确保妊娠识别所需的足够干扰素 tau (IFNT)。我们检测到第 7 天孕酮对所有 6 个基因、胚胎盘大小和第 15 天滋养层长度的表达有影响。我们还发现胚胎转移大小对第 15 天滋养层长度和 IFNT 和 PAG11 表达的影响。从转移到恢复期间的能量平衡较低与胚胎生长到第 15 天减少有关,这种影响与孕酮无关。能量平衡还影响第 15 天 PDPN 和 TKDP1 的表达。我们观察到从转移到恢复期间的能量平衡对有部分胚胎损失的牛的胚胎存活有影响,其中胚胎因素主导胚胎存活,能量平衡较大的牛胚胎损失较少。这种影响与转移前 40 天的能量平衡无关,这表明在这段时间内,能量平衡对胚胎和母体环境有直接的、即时的影响。此外,能量平衡对有部分胚胎损失的牛的胚胎存活的影响在很大程度上是由 TKDP1、PAG11 和 PDPN 的表达介导的。这些结果为孕酮和能量平衡对胚胎生长和存活的影响提供了候选信号通路。