title: Biased gene expression in early honeybee larval development.
abstract: BACKGROUND
  Female larvae of the honeybee (Apis mellifera) develop into either queens or workers depending on nutrition. This nutritional stimulus triggers different developmental trajectories, resulting in adults that differ from each other in physiology, behaviour and life span.
  
  
  RESULTS
  To understand how these trajectories are established we have generated a comprehensive atlas of gene expression throughout larval development. We found substantial differences in gene expression between worker and queen-destined larvae at 6 hours after hatching. Some of these early changes in gene expression are maintained throughout larval development, indicating that caste-specific developmental trajectories are established much earlier than previously thought. Within our gene expression data we identified processes that potentially underlie caste differentiation. Queen-destined larvae have higher expression of genes involved in transcription, translation and protein folding early in development with a later switch to genes involved in energy generation. Using RNA interference, we were able to demonstrate that one of these genes, hexamerin 70b, has a role in caste differentiation. Both queen and worker developmental trajectories are associated with the expression of genes that have alternative splice variants, although only a single variant of a gene tends to be differentially expressed in a given caste.
  
  
  CONCLUSIONS
  Our data, based on the biases in gene expression early in development together with published data, supports the idea that caste development in the honeybee consists of two phases; an initial biased phase of development, where larvae can still switch to the other caste by differential feeding, followed by commitment to a particular developmental trajectory.
authors.forename: Rosannah C
authors.initials: RC
authors.lastname: Cameron
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Duncan
authors.affiliation: Laboratory for Evolution and Development, Gravida, the National Centre for Growth and Development and Genetics Otago, Department of Biochemistry, University of Otago, Dunedin, Aotearoa-New Zealand. peter.dearden@otago.ac.nz.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Dearden
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001516:Bees / Q000235:genetics* / Q000254:growth & development*; D002352:Carrier Proteins / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000235:genetics; D007814:Larva / Q000235:genetics / Q000254:growth & development; D020411:Oligonucleotide Array Sequence Analysis
chemical_list: D002352:Carrier Proteins; D019476:Insect Proteins; C092382:arylphorin-binding proteins, insect