title: Deep sequencing and expression of microRNAs from early honeybee (Apis mellifera) embryos reveals a role in regulating early embryonic patterning.
abstract: BACKGROUND
  Recent evidence supports the proposal that the observed diversity of animal body plans has been produced through alterations to the complexity of the regulatory genome rather than increases in the protein-coding content of a genome. One significant form of gene regulation is the contribution made by the non-coding content of the genome. Non-coding RNAs play roles in embryonic development of animals and these functions might be expected to evolve rapidly. Using next-generation sequencing and in situ hybridization, we have examined the miRNA content of early honeybee embryos.
  
  
  RESULTS
  Through small RNA sequencing we found that 28% of known miRNAs are expressed in the early embryo. We also identified developmentally expressed microRNAs that are unique to the Apoidea clade. Examination of expression patterns implied these miRNAs have roles in patterning the anterior-posterior and dorso-ventral axes as well as the extraembryonic membranes. Knockdown of Dicer, a key component of miRNA processing, confirmed that miRNAs are likely to have a role in patterning these tissues.
  
  
  CONCLUSIONS
  Examination of the expression patterns of novel miRNAs, some unique to the Apis group, indicated that they are likely to play a role in early honeybee development. Known miRNAs that are deeply conserved in animal phyla display differences in expression pattern between honeybee and Drosophila, particularly at early stages of development. This may indicate miRNAs play a rapidly evolving role in regulating developmental pathways, most likely through changes to the way their expression is regulated.
authors.affiliation: Laboratory for Evolution and Development, Genetics Otago and National Research Centre for Growth and Development, Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
authors.forename: Lisa
authors.initials: L
authors.lastname: Zondag
authors.forename: Peter K
authors.initials: PK
authors.lastname: Dearden
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Wilson
mesh_terms: D000818:Animals; D001483:Base Sequence; D001516:Bees / Q000196:embryology / Q000235:genetics*; D019521:Body Patterning / Q000235:genetics*; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D017403:In Situ Hybridization; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D008969:Molecular Sequence Data; D034622:RNA Interference; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
chemical_list: D019476:Insect Proteins; D035683:MicroRNAs; D043244:Ribonuclease III