基因重复是新基因和新功能产生的最主要的方式之一。然而，在分子水平，新产生的重复基因如何通过通路整合而获得生物学功能以及产生适应性性状却并不清楚。
为了回答以上问题，中科院昆明动物研究所中德马普进化基因组学青年科学家小组的博士生丁昀等在导师王文研究员的指导下，对黑腹果蝇亚群（Drosophila melanogaster subgroup）里新近产生的kep1基因家族的生物学功能及分子机制进行了研究。通过序列和表达分析，他们发现其中的一个新基因nsr（novel spermatogenesis regulator）在进化过程中受到了强烈的达尔文正选择的作用，并显出了新的亚细胞定位特征。基因敲除和全转录组测序分析的结果则进一步表明，nsr通过转录后调节几个重要的Y染色体连锁的育性因子参与精子的个体化（sperm individualization）和卷曲折叠（sperm coiling）过程，并对精子轴丝结构的完整性有重要贡献。此外，外群物种里的祖先基因缺乏同nsr相似的精巢表达模式但具备相应的顺式调控元件说明：祖先基因在重复前对雄性生殖力应该无明显作用；反式调控元件的变化很可能通过赋予nsr新的表达模式而促使它经历新功能化（neofunctionalization）的过程。
该研究不但刻画了一个年轻重复基因进化的详尽历程，而且表明新近起源的年轻新基因可以通过调控已有的重要基因来建立新的功能通路和捕获多种生物学功能。同时，新基因参与古老的重要的生物学过程这一结果也有助于我们解释不同生物体同一生物学过程往往很可能由不同的基因来参与调节的普遍自然现象。
该论文已于2010年12月发表于PLoS Genetics杂志上（IF=9.532）。（生物谷Bioon.com）
生物谷推荐原文出处：
PLoS Genet. doi:10.1371/journal.pgen.1001255
A Young Drosophila Duplicate Gene Plays Essential Roles in Spermatogenesis by Regulating Several Y-Linked Male Fertility Genes
Yun Ding1,2#, Li Zhao1,2#, Shuang Yang1, Yu Jiang1,2, Yuan Chen1,2, Ruoping Zhao1, Yue Zhang1, Guojie Zhang1,2, Yang Dong1,2, Haijing Yu3, Qi Zhou1,2¤, Wen Wang1*
1 State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China, 2 Graduate University of Chinese Academy of Sciences, Beijing, China, 3 Laboratory for Conservation and Utilization of Bio-Resources and Human Genetics Center of Yunnan University, Kunming, China
Abstract
Gene duplication is supposed to be the major source for genetic innovations. However, how a new duplicate gene acquires functions by integrating into a pathway and results in adaptively important phenotypes has remained largely unknown. Here, we investigated the biological roles and the underlying molecular mechanism of the young kep1 gene family in the Drosophila melanogaster species subgroup to understand the origin and evolution of new genes with new functions. Sequence and expression analysis demonstrates that one of the new duplicates, nsr (novel spermatogenesis regulator), exhibits positive selection signals and novel subcellular localization pattern. Targeted mutagenesis and whole-transcriptome sequencing analysis provide evidence that nsr is required for male reproduction associated with sperm individualization, coiling, and structural integrity of the sperm axoneme via regulation of several Y chromosome fertility genes post-transcriptionally. The absence of nsr-like expression pattern and the presence of the corresponding cis-regulatory elements of the parental gene kep1 in the pre-duplication species Drosophila yakuba indicate that kep1 might not be ancestrally required for male functions and that nsr possibly has experienced the neofunctionalization process, facilitated by changes of trans-regulatory repertories. These findings not only present a comprehensive picture about the evolution of a new duplicate gene but also show that recently originated duplicate genes can acquire multiple biological roles and establish novel functional pathways by regulating essential genes.
