正选择驱动褪黑激素受体MT1与MT2基因的分化

 【目的】研究褪黑激素受体（melatonin receptor，MTNR）基因的进化模式，为褪黑激素受体基因相关功能的研究提供理论参考。【方法】利用生物信息学的方法和软件对来自11个物种的褪黑激素受体1a（MT1）和褪黑激素受体1b（MT2）基因的系统发生关系、基因相似性、选择压力、选择方向等进行系统地分析。【结果】MT1和MT2基因可能由共同祖先基因通过基因重复产生， MT1可能保持着源基因的功能，MT2为新产生的功能基因。MT1基因在物种间的相似性极显著高于MT2基因（P＜0.01）；MT1基因主要受纯化选择，MT2基因受到显著的正选择；MT1与MT2基因均承受着较强的选择压力，且选择压力在2基因间无显著差异（P＞0.05）。【结论】MT1基因主要受纯化选择可能是MT1基因与动物季节性繁殖关联研究结论不统一的原因，MT2基因受正选择提示正选择可能是驱动MT2与MT1发生分化的重要动力。

Positive Selection Driven the Differentiation of Melatonin Receptor MT1 and MT2 Genes

【Objective】 This paper focused on molecular evolution of melatonin receptor (MTNR) genes for providing clues of gene biological function. 【Method】By using bioinformatics methods and softwares,  the phylogenetic tree, genetic similarity, selection pressures and selection direction of melatonin receptor 1a (MT1) and melatonin receptor 1b (MT2) genes from 11 species were analyzed.【Result】MT1 and MT2 genes might come from a duplication of a common ancestor gene, MT1 might be keeping most functions of the parental gene and MT2 might be a new functional gene. The genetic similarity of MT1 genes among species was significantly higher than MT2 (P＜0.01). MT1 gene was undergone purifying selection while MT2 was under significant positive selection. Both of MT1 and MT2 were undergone strong selection pressure and there was no significant difference in selection pressure (P＞0.05) between the two genes.【Conclusion】Purifying selection for MT1 gene could explain the discrepancy of the association of MT1 gene with seasonal reproduction in animals and positive selection for MT2 gene showed that positive selection might be the main force driving the differentiation of MT2 and MT1.