Genome-wide mapping of conserved microRNAs and their host transcripts in Tribolium castaneum

MicroRNAs (miRNAs) are endogenous 22-nt RNAs,which play important regulatory roles by post-transcriptional gene silencing. A computational strategy has been developed for the identification of conserved miRNAs based on features of known metazoan miRNAs in red flour beetle (Tribolium castaneum),which is regarded as one of the major laboratory models of arthropods. Among 118 putative miRNAs,47% and 53% of the predicted miRNAs from the red flour beetle are harbored by known protein-coding genes (intronic) and genes located outside (intergenic miRNA),respectively. There are 31 intronic miRNAs in the same transcriptional orientation as the host genes,which may share RNA polymerase Ⅱ and spliceosomal machinery with their host genes for their biogenesis. A hypothetical feed-back model has been proposed based on the analysis of the relationship between intronic miRNAs and their host genes in the develop-ment of red flour beetle.