INRAE, Université de Tours, BOA, Nouzilly, 37380, France.
BMC Genomics. 2024 May 2;25(1):438. doi: 10.1186/s12864-024-10323-0.
Nutrient availability during early stages of development (embryogenesis and the first week post-hatch) can have long-term effects on physiological functions and bird metabolism. The embryo develops in a closed structure and depends entirely on the nutrients and energy available in the egg. The aim of this study was to describe the ontogeny of pathways governing hepatic metabolism that mediates many physiological functions in the pHu + and pHu- chicken lines, which are divergently selected for the ultimate pH of meat, a proxy for muscle glycogen stores, and which differ in the nutrient content and composition of eggs.
We identified eight clusters of genes showing a common pattern of expression between embryonic day 12 (E12) and day 8 (D8) post-hatch. These clusters were not representative of a specific metabolic pathway or function. On E12 and E14, the majority of genes differentially expressed between the pHu + and pHu- lines were overexpressed in the pHu + line. Conversely, the majority of genes differentially expressed from E18 were overexpressed in the pHu- line. During the metabolic shift at E18, there was a decrease in the expression of genes linked to several metabolic functions (e.g. protein synthesis, autophagy and mitochondrial activity). At hatching (D0), there were two distinct groups of pHu + chicks based on hierarchical clustering; these groups also differed in liver weight and serum parameters (e.g. triglyceride content and creatine kinase activity). At D0 and D8, there was a sex effect for several metabolic pathways. Metabolism appeared to be more active and oriented towards protein synthesis (RPS6) and fatty acid β-oxidation (ACAA2, ACOX1) in males than in females. In comparison, the genes overexpressed in females were related to carbohydrate metabolism (SLC2A1, SLC2A12, FoxO1, PHKA2, PHKB, PRKAB2 and GYS2).
Our study provides the first detailed description of the evolution of different hepatic metabolic pathways during the early development of embryos and post-hatching chicks. We found a metabolic orientation for the pHu + line towards proteolysis, glycogen degradation, ATP synthesis and autophagy, likely in response to a higher energy requirement compared with pHu- embryos. The metabolic orientations specific to the pHu + and pHu- lines are established very early, probably in relation with their different genetic background and available nutrients.
胚胎发生和孵化后第一周早期的营养供应会对生理功能和鸟类代谢产生长期影响。胚胎在封闭的结构中发育，完全依赖于蛋中可用的营养物质和能量。本研究旨在描述调控肝代谢的途径的个体发生，这些途径介导 pHu+和 pHu-鸡系的许多生理功能，这两个鸡系是通过肉的最终 pH 值（肌肉糖原储存的代表）进行差异选择的，其蛋中的营养成分和组成也存在差异。
我们确定了 8 个基因簇，这些基因簇在胚胎第 12 天（E12）和孵化后第 8 天（D8）之间表现出共同的表达模式。这些簇不是特定代谢途径或功能的代表。在 E12 和 E14 时，pHu+和 pHu-系之间差异表达的大多数基因在 pHu+系中表达上调。相反，E18 时差异表达的大多数基因在 pHu-系中表达上调。在 E18 的代谢转变期间，与几种代谢功能（如蛋白质合成、自噬和线粒体活性）相关的基因表达减少。在孵化时（D0），根据层次聚类，有两个不同的 pHu+雏鸡组；这些组在肝脏重量和血清参数（如甘油三酯含量和肌酸激酶活性）上也存在差异。在 D0 和 D8 时，几个代谢途径存在性别效应。与雌性相比，雄性的代谢似乎更活跃，偏向于蛋白质合成（RPS6）和脂肪酸β氧化（ACAA2、ACOX1）。相比之下，雌性中高表达的基因与碳水化合物代谢有关（SLC2A1、SLC2A12、FoxO1、PHKA2、PHKB、PRKAB2 和 GYS2）。
本研究首次详细描述了胚胎早期发育和孵化后雏鸡不同肝代谢途径的演变。我们发现 pHu+系的代谢方向是蛋白水解、糖原降解、ATP 合成和自噬，这可能是对与 pHu-胚胎相比更高的能量需求的反应。pHu+和 pHu-系特有的代谢方向很早就建立起来了，这可能与它们不同的遗传背景和可用营养物质有关。
