Differentially expressed microRNAs between queen and worker larvae of the honey bee (Apis mellifera)

Although the honey bee queen and worker have identical genomes, they exhibit morphological, behavioral, and reproductive differences. Queen larvae (QL) and worker larvae (WL) have different gene and protein expression profiles and different DNA methylation profiles. MicroRNAs (miRNAs) play an important role in regulating gene expression and cell biological processes. To examine the roles of miRNAs in caste differentiation, we analyzed small RNA profiles in 4-day-old QL and WL (Apis mellifera). The results demonstrated that the small RNAs with a length of 22 nt showed significant difference between the two castes. By comparison with mirBase 19.0, we identified 61 known miRNAs in QL and WL; 17, 24 and 20 of these miRNAs were respectively up-regulated, equally expressed, and down-regulated in QL compared with WL. These differentially expressed miRNAs were involved in many signaling pathways related to caste differentiation.