Divergent composition and transposon-silencing activity of small RNAs in mammalian oocytes

We found piRNAs with different lengths represented the predominant small RNA species in oocytes from the 12 explored species, except mouse. We found endo-siRNAs resulted from the truncated Dicer isoform were mouse-specific, and os-piRNAs associating with PIWIL3 in human oocytes are widespread in mammals and are typically with low levels of the 2'-3'-O-methylation. The sequences of many highly expressed piRNA clusters are fast-evolving compared with their syntenic genomic locations, and the TE families distributing in the conserved piRNA clusters are various between species. Profiling small RNAs and mRNA in oocytes from 12 animals.本研究发现，在本次探究的12个物种的卵母细胞中，除小鼠外，不同长度的piRNA（piwi-interacting RNA）为主要的小RNA类型；由截短型Dicer同工体产生的内源性小干扰RNA（endo-siRNA）为小鼠所特有，而在人类卵母细胞中与PIWIL3结合的os-piRNA在哺乳动物中广泛存在，且通常呈现低水平的2'-3'-O-甲基化修饰。相较于同线基因组区域，大量高表达piRNA簇的序列呈现快速演化特征，分布于保守piRNA簇中的转座因子（TE）家族在不同物种间存在显著差异。本数据集对12种动物卵母细胞内的小RNA与信使RNA（mRNA）开展了表达谱分析。