Department of Neuroscience, Uppsala University, Uppsala, Sweden.
Neurogenetics. 2011 Aug;12(3):211-21. doi: 10.1007/s10048-011-0290-9. Epub 2011 Jul 12.
Long-term divergent selection for low or high body weight from the same founder population has generated two extremely divergent lines of chickens, the high- (HWS) and low-weight (LWS) selected lines. At selection age (56 days), the lines differ by more than nine times in body weight. The HWS line chickens are compulsive feeders, whereas in the LWS line, some individuals are anorexic and others have very low appetite. Previous studies have implicated the central nervous system and particularly the hypothalamus in these behavioural differences. Here, we compared the mRNA expression in hypothalamus tissue from chickens on day 4 post-hatch using oligonucleotide arrays and found that the divergent selection had resulted in minor but multiple expression differences. Differentially expressed genes were enriched in processes 'DNA metabolism, repair, induction of apoptosis and metabolism'. Several differentially expressed genes participate in the regulation of neuronal plasticity and development, including apoptosis, or are neurotransmittor receptor subtypes. Less change was seen when comparing hypothalamic neuropeptide mediators of appetite such as the melanocortin receptors. The genomic locations of these differentially expressed genes were then compared to the locations of growth QTLs and to a genome-wide map of chromosomal regions that have been under divergent selection between the lines. The results indicate which differentially expressed hypothalamic genes have responded to the divergent selection and that the results predict that it is more likely to find causative genes among these most differentially expressed genes. Because of such differential gene expression in hypothalamus, the lines may adapt behaviourally different particularly to the post-hatch situation when independent feeding to obtain energy is established.
长期以来，从同一创始种群中对低体重或高体重进行的分歧选择产生了两条截然不同的鸡系，即高体重（HWS）和低体重（LWS）选择系。在选择年龄（56 天）时，两条线的体重差异超过九倍。HWS 线的鸡是强迫喂食者，而在 LWS 线中，一些个体厌食，而另一些则食欲极低。先前的研究表明，中枢神经系统，特别是下丘脑，参与了这些行为差异。在这里，我们比较了孵化后第 4 天来自鸡的下丘脑组织中的 mRNA 表达，使用寡核苷酸阵列，发现分歧选择导致了微小但多种表达差异。差异表达的基因在“DNA 代谢、修复、凋亡诱导和代谢”等过程中富集。几个差异表达的基因参与神经元可塑性和发育的调节，包括凋亡或神经递质受体亚型。当比较食欲的下丘脑神经肽调节剂（如黑素皮质素受体）时，变化较小。然后将这些差异表达基因的基因组位置与生长 QTL 的位置以及两条线之间存在分歧选择的全基因组染色体区域图谱进行比较。结果表明，差异表达的下丘脑基因对分歧选择有反应，并且结果预测，在这些差异表达最明显的基因中更有可能找到因果基因。由于下丘脑的这种差异基因表达，这些系可能表现出不同的行为，特别是在独立觅食以获得能量的孵化后阶段。
