Most of the birds's adaptations for migration have a neuroendocrine origin, triggered by changes in photoperiod and the patterns of Earth's magnetic field. Migration phenomenology has been well described in the past decades, yet the genetic structure behind it remains terra incognita. We used RNA-Seq data to investigate which biological functions are linked with the seasonal brain adaptations of a long-distance trans-continental migratory passerine, the Northern Wheatear (Oenanthe oenanthe). We sequenced the wheatear's transcriptomes at three different stages: lean birds, a characteristic phenotype before the onset of migration, during fattening, and at their maximal migratory body mass. We identified a total of 15,357 genes in the brain of wheatears, of which 84 were differentially expressed. These were mostly related to nervous tissue development, angiogenesis, ATP production, innate immune response, and antioxidant protection, as well as GABA and dopamine signalling. The expression pattern of differentially expressed genes is correlated with typical phenotypic changes before migration, such as hyperphagia, migratory restlessness, and a potential increment in the visual and spatial memory capacities. Our work points out, for future studies, biological functions found to be involved in the development of the migratory phenotype -a unique model to study the core of neural, energetic and muscular adaptations for endurance exercise. Comparison of wheatears' transcriptomic data with two other studies with similar goals shows no correlation among the trends in the gene expression. It highlights the complexity and diversity of adaptations for long-distance migration in birds.

中文翻译：

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迁徙鸣禽大脑中的转录组签名。

大多数鸟类的迁徙适应都是神经内分泌起源的，这是由光周期的变化和地球磁场的模式触发的。迁移现象学在过去的几十年中得到了很好的描述，但其背后的遗传结构仍然是未知的。我们使用RNA-Seq数据研究了哪些生物学功能与长途跨大陆候鸟（北麦翁（Oenanthe oenanthe））的季节性大脑适应性相关。我们在三个不同的阶段对麦穗的转录组进行了测序：瘦肉鸟，迁徙开始前，育肥期间和最大迁徙体重的特征表型。我们在麦穗的大脑中鉴定出总共15357个基因，其中84个是差异表达的。这些主要与神经组织发育，血管生成，ATP产生，先天免疫反应和抗氧化保护以及GABA和多巴胺信号传导有关。差异表达基因的表达模式与迁徙前典型的表型变化有关，例如食欲亢进，迁徙不安以及视觉和空间记忆能力的潜在增加。我们的工作指出，在未来的研究中，发现与迁移表型有关的生物学功能是研究耐力运动的神经，能量和肌肉适应核心的独特模型。麦穗转录组数据与其他两个目标相似的研究的比较表明，基因表达趋势之间没有相关性。