A distinct class of small RNAs arises from pre-miRNA-proximal regions in a simple chordate. A distinct class of small RNAs arises from pre-miRNA-proximal regions in a simple chordate

We report the comprehensive sequencing of small RNA libraries created from different developmental stages of the basal chordate, Ciona intestinalis. Surprisingly, half of the identified miRNA loci encode not two, but up to four distinct small RNAs. These additional RNAs, termed “moRs”, are generated from sequences adjacent to the predicted ~60-nt pre-miRNA. moRs appear to be produced by RNAse-III-like processing, are ~20-nt in length, have 5’-monophosphate and 3’-hydroxl termini, and like miRNAs, are developmentally regulated. Overall design: Sequencing of small RNA libraries from 4 stages of Ciona intestinalis. Ciona_LarvaMir309_RNASeq and Dmel_Toll10b_RNASeq are sequencing runs to detect if the expression of these RNA products is specific to Ciona or not. An ectopic transcript of the Drosophila melanogaster miR-309 locus was expressed in Ciona to see if it processed the miRs differently than Drosophila melanogaster. The Dmel sequence is from the endogenous case and is a control for comparison.

本研究报道了源自基底脊索动物柄海鞘（Ciona intestinalis）不同发育阶段的小分子RNA文库的全面测序结果。令人意外的是，已鉴定的微RNA(miRNA)位点中，有一半编码的并非2种，而是最多4种不同的小分子RNA。这些额外的RNA被命名为"moRs"，它们由预测的约60 nt的前体微RNA(pre-miRNA)相邻区域的序列产生。moRs似乎通过类似核糖核酸酶III(RNAse III)的加工方式生成，长度约为20 nt，具有5'-单磷酸和3'-羟基末端，且与微RNA类似，其表达受发育调控。整体实验设计：对柄海鞘（Ciona intestinalis）4个发育阶段的小分子RNA文库进行测序。Ciona_LarvaMir309_RNASeq与Dmel_Toll10b_RNASeq这两项测序实验用于检测此类RNA产物的表达是否为柄海鞘所特有。研究人员将黑腹果蝇（Drosophila melanogaster）miR-309位点的异位转录本在柄海鞘中进行表达，以探究其对微RNA的加工方式是否与黑腹果蝇存在差异。Dmel序列取自内源表达场景，作为比对对照。