Expression and evolution of lincRNAs in Drosophila pseudoobscura using RNA-Seq. Kevin G Nyberg, Carlos A Machado. Department of Biology University of Maryland, College Park, MD 20742.

   Long intergenic noncoding RNAs, or lincRNAs, are known to function in processes like dosage compensation and stem cell regulation, but little is known about how they evolve, especially among closely related species. Here, we use RNA-Seq to identify lincRNAs in Drosophila pseudoobscura and characterize their expression and the selective forces that influence their evolution. We generated sex-specific RNA-Seq libraries at four different developmental stages (1st instar larvae, 3rd instar larvae, pupae, and 7-day adults) and in adult gonads and carcasses. Transcripts were identified and screened for signatures of protein-coding ability to generate a list of putative lincRNAs. LincRNA expression was then characterized in terms of sex, developmental regulation, and tissue localization. With multiple genome lines now publicly available from the pseudoobscura subgroup, we used sequence-based neutrality tests to look for evidence of selection on lincRNAs. We found that many lincRNAs show developmental and sex-specific regulation. In addition, some lincRNAs in D. pseudoobscura show evidence of selection.