New microRNAs in Drosophila
MicroRNAs (miRNA) are small, endogenous RNAs that regulate the expression of mRNAs posttranscriptionally. Evolutionarily new miRNAs, like new protein-coding genes, are dominantly expressed in reproductive organs. To dissect the evolutionary dynamics of new miRNAs in Drosophila spp, we sequenced small RNAs from two species of Drosophila, including four samples from reproductive organs and one sample from imaginal discs / CNS. miRNA expression profile shows vast majority of new miRNAs are specifically expressed in testes and/or ovaries, suggesting a role of sexual selection for new miRNA evolution. Overall design: Five small RNA samples, mainly from reproductive organs of D. simulans and D. pseudoobscura were analyzed. The small RNAs were sequenced by Illumina HiSeq 2000. After triming the adapters, the 18-30 nt sequences were extracted for further study.