Computational and transcriptional evidence for microRNAs in the honey bee genome

BACKGROUND: Noncoding microRNAs (miRNAs) are key regulators of gene expression in eukaryotes. Insect miRNAs help regulate the levels of proteins involved with development, metabolism, and other life history traits. The recently sequenced honey bee genome provides an opportunity to detect novel miRNAs in both this species and others, and begin to infer the roles of miRNAs in honey bee development.
RESULTS: Three independent computational surveys of the assembled honey bee genome identified a total of 68 non-redundant candidate miRNAs, several of which appear to have previously unrecognized orthologs in the Drosophila genome. A subset of these candidate miRNAs were screened for expression by qRT-PCR and/or genome tiling arrays and most predicted miRNA's were confirmed as being expressed in at least one honey bee tissue. Interestingly, the transcript abundance for several known and novel miRNAs displayed caste or age-related differences in honey bees. Genes in proximity to miRNAs in the bee genome are disproportionately associated with the GO terms "physiological process", "nucleus" and "response to stress".
CONCLUSIONS: Computational approaches successfully identified miRNAs in the honey bee and indicated previously unrecognized miRNAs in the well-studied Drosophila melanogaster genome despite the 280MYA distance between these insects. Differentially transcribed miRNAs are likely to be involved in regulating honey bee development, and arguably in the extreme developmental switch between sterile worker bees and highly fertile queens.

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