ABSTRACT

Possible phenotypic impairments associated with maternal stress during gestation in beef cattle may be explained by epigenetic effects. This study examined the impact of prenatal transportation stress on DNA methylation of lymphocytes of Brahman cows over the first 5 years of life. Methylation analysis through reduced representation bisulphite sequencing was conducted on DNA from lymphocytes from 28 paired samples from 6 prenatally stressed (PNS) and 8 control (Control) females obtained initially when they were 28 days of age and 5 years of age. There were 14,386 CpG (C = cytosine; p = phosphate; G = guanine) sites differentially methylated (P < 0.01) in 5-yr-old Control cows compared to their lymphocyte DNA at 28 days of age, this number was slightly decreased in 5-yr-old PNS with 13,378 CpG sites. Only 2,749 age-related differentially methylated CpG sites were seen within PNS females. There were 2,637 CpG sites differentially methylated (P < 0.01) in PNS cows relative to Controls at 5 years of age. There were differentially methylated genes in 5-yr-old cows that contributed similarly to altered gene pathways in both treatment groups. Canonical pathways altered in PNS compared to Control cows at 5 years of age were mostly related to development and growth, nervous system development and function, and immune response. Prenatal stress appeared to alter the epigenome in Brahman cows compared to Control at 5 years of age, which implies a persistent intervention in DNA methylation in lymphocytes, and may confer long-lasting effects on gene expression, and consequently relevant phenotypic changes.

摘要

肉牛妊娠期间与母体压力相关的可能表型损伤可以用表观遗传效应来解释。本研究检查了产前运输压力对婆罗门奶牛生命前 5 年淋巴细胞 DNA 甲基化的影响。通过减少代表性亚硫酸氢盐测序对来自 28 对样本的淋巴细胞 DNA 进行甲基化分析，这些样本来自 6 名产前应激 (PNS) 和 8 名对照 (Control) 女性，最初在 28 日龄和 5 岁时获得。有 14,386 个 CpG（C = 胞嘧啶；p = 磷酸盐；G = 鸟嘌呤）位点差异甲基化（P< 0.01) 在 5 岁对照奶牛中，与 28 日龄时的淋巴细胞 DNA 相比，这个数字在 5 岁 PNS 中有 13,378 个 CpG 位点略有下降。在 PNS 女性中仅观察到 2,749 个与年龄相关的差异甲基化 CpG 位点。有 2,637 个 CpG 位点差异甲基化（P< 0.01) 在 PNS 奶牛中相对于 5 岁时的对照。5 岁奶牛中存在差异甲基化基因，这对两个治疗组中基因通路的改变做出了类似的贡献。与 5 岁时的对照奶牛相比，PNS 中改变的典型途径主要与发育和生长、神经系统发育和功能以及免疫反应有关。与 5 岁时的对照组相比，产前压力似乎改变了婆罗门奶牛的表观基因组，这意味着对淋巴细胞 DNA 甲基化的持续干预，并可能对基因表达产生长期影响，从而导致相关的表型变化。