Identification and comparative analysis of long non-coding RNAs in the brain of fire ant queens in two different reproductive states

Background Many long non-coding RNAs (lncRNAs) have been extensively identified in higher eukaryotic species. The function of lncRNAs has been reported to play important roles in diverse biological processes, including developmental regulation and behavioral plasticity. However, there are no reports of systematic characterization of long non-coding RNAs in the fire ant Solenopsis invicta . Results In this study, we performed a genome-wide analysis of lncRNAs in the brains of S. invicta from RNA-seq. In total, 1,393 novel lncRNA transcripts were identified in the fire ant. In contrast to the annotated lncRNA transcripts having at least two exons, novel lncRNAs are monoexonic transcripts with a shorter length. Besides, the transcriptome from virgin alate and dealate mated queens were analyzed and compared. The results showed 295 differentially expressed mRNA genes (DEGs) and 65 differentially expressed lncRNA genes (DELs) between virgin and mated queens, of which 17 lncRNAs were highly expressed in the virgin alates and 47 lncRNAs were highly expressed in the mated dealates. By identifying the DEL:DEG pairs with a high association in their expression (Spearman’s | rho |> 0.8 and p -value < 0.01), many DELs were co-regulated with DEGs after mating. Furthermore, several remarkable lncRNAs ( MSTRG.6523 , MSTRG.588 , and nc909 ) that were found to associate with particular coding genes may play important roles in the regulation of brain gene expression in reproductive transition in fire ants. Conclusion This study provides the first genome-wide identification of S. invicta lncRNAs in the brains in different reproductive states. It will contribute to a fuller understanding of the transcriptional regulation underpinning reproductive changes.