Data from: Avian offspring prenatal DNA methylation response to maternal corticosterone dosing during reproduction

Avian embryos develop in an egg composition which reflects both maternal condition and the recent environment of their mother. In birds, yolk corticosterone (CORT) influences development by impacting pre- and postnatal growth, as well as nestling stress responses and development. One possible mechanism through which maternal CORT may affect offspring development is via changes to offspring DNA methylation. We sought to investigate this, for the first time in birds, by quantifying the impact of manipulations to maternal CORT on offspring DNA methylation. We non-invasively manipulated plasma CORT concentrations of egg-laying female zebra finches (Taeniopygia castanotis) with an acute dose of CORT administered around the time of ovulation and collected their eggs. We then assessed DNA methylation in the resulting embryonic tissue and in their associated vitelline membrane blood vessels, during early development (5 days after lay), using two established methods - liquid chromatography–mass spectrometry (LC-MS) and methylation-sensitive amplification fragment length polymorphism (MS-AFLP). LC-MS analysis showed that global DNA methylation was lower in embryos from CORT-treated mothers, compared to control embryos. In contrast, blood vessel DNA from eggs from CORT-treated mothers showed global methylation increases, compared to control samples. There was a higher proportion of global DNA methylation in the embryonic DNA of second clutches, compared to first clutches. Locus-specific analyses using MS-AFLP did not reveal a treatment effect. Our results indicate that an acute elevation of maternal CORT around ovulation impacts DNA methylation patterns in their offspring. This could provide a mechanistic understanding of how a mother's experience can affect her offspring's phenotype.鸟类胚胎于卵内发育，卵的组成既反映母体生理状态，也体现其近期所处的环境。在鸟类中，卵黄皮质酮（corticosterone, CORT）可通过影响胚胎产前、产后生长及雏鸟应激反应与发育过程，调控个体发育。母体皮质酮影响子代发育的潜在机制之一，或为改变子代DNA甲基化水平。本研究首次以鸟类为模型，通过量化母体皮质酮调控对子代DNA甲基化的影响，对该假说展开探究。本研究以产卵期雌性斑胸草雀（Taeniopygia castanotis）为对象，在其排卵前后给予急性剂量的皮质酮，无创调控其血浆皮质酮浓度，并收集其所产卵。随后，本研究在胚胎发育早期（产卵后5天），采用两种成熟实验方法——液相色谱-质谱联用法（liquid chromatography–mass spectrometry, LC-MS）与甲基化敏感扩增片段长度多态性（methylation-sensitive amplification fragment length polymorphism, MS-AFLP），分别检测子代胚胎组织及其卵黄膜血管中的DNA甲基化水平。LC-MS分析结果显示，与对照组胚胎相比，皮质酮处理组母体所产胚胎的全基因组DNA甲基化水平更低；与之相反，皮质酮处理组卵的卵黄膜血管DNA的全基因组甲基化水平较对照组样本有所升高。第二窝子代胚胎的DNA全基因组甲基化比例显著高于第一窝子代。采用MS-AFLP进行位点特异性分析时，未检测到皮质酮处理的显著效应。本研究结果表明，母体在排卵前后的皮质酮急性升高，会改变子代的DNA甲基化模式，这可为阐释母体经历如何影响子代表型的机制提供新的理论依据。