Wang Yanli, Jiang Feng, Wang Huimin, Song Tianqi, Wei Yuanyuan, Yang Meiling, Zhang Jianzhen, Kang Le
Institute of Applied Biology, Shanxi University, Taiyuan, Shanxi, China.
Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.
Sci Rep. 2015 Sep 2;5:13608. doi: 10.1038/srep13608.
Substantial accumulation of neutral sequences accounts for genome size expansion in animal genomes. Numerous novel microRNAs (miRNAs), which evolve in a birth and death manner, are considered evolutionary neutral sequences. The migratory locust is an ideal model to determine whether large genomes contain abundant neutral miRNAs because of its large genome size. A total of 833 miRNAs were discovered, and several miRNAs were randomly chosen for validation by Northern blot and RIP-qPCR. Three additional verification methods, namely, processing-dependent methods of miRNA biogenesis using RNAi, evolutionary comparison with closely related species, and evidence supported by tissue-specific expression, were applied to provide compelling results that support the authenticity of locust miRNAs. We observed that abundant local duplication events of miRNAs, which were unique in locusts compared with those in other insects with small genome sizes, may be responsible for the substantial acquisition of miRNAs in locusts. Together, multiple evidence showed that the locust genome experienced a burst of miRNA acquisition, suggesting that genome size expansion may have considerable influences of miRNA innovation. These results provide new insight into the genomic dynamics of miRNA repertoires under genome size evolution.
中性序列的大量积累导致了动物基因组大小的扩张。许多以生死方式进化的新型微小RNA（miRNA）被认为是进化中性序列。由于飞蝗基因组较大，它是确定大基因组是否含有丰富中性miRNA的理想模型。共发现了833个miRNA，并随机选择了几个miRNA通过Northern印迹和RIP-qPCR进行验证。还应用了另外三种验证方法，即使用RNAi的miRNA生物合成的加工依赖性方法、与近缘物种的进化比较以及组织特异性表达支持的证据，以提供令人信服的结果来支持飞蝗miRNA的真实性。我们观察到，与其他基因组较小的昆虫相比，飞蝗中miRNA丰富的局部重复事件是独特的，这可能是飞蝗中miRNA大量获得的原因。综合来看，多项证据表明飞蝗基因组经历了miRNA获得的爆发，这表明基因组大小的扩张可能对miRNA创新有相当大的影响。这些结果为基因组大小进化下miRNA库的基因组动态提供了新的见解。
