Nutritionally driven differential gene expression leads to heterochronic brain development in honeybee castes

PLoS One. 2013 May 30;8(5):e64815. doi: 10.1371/journal.pone.0064815. Print 2013.

Abstract

The differential feeding regimes experienced by the queen and worker larvae of the honeybee Apis mellifera shape a complex endocrine response cascade that ultimately gives rise to differences in brain morphologies. Brain development analyzed at the morphological level from the third (L3) through fifth (L5) larval instars revealed an asynchrony between queens and workers. In the feeding phase of the last larval instar (L5F), two well-formed structures, pedunculi and calyces, are identifiable in the mushroom bodies of queens, both of which are not present in workers until a later phase (spinning phase, L5S). Genome-wide expression analyses and normalized transcript expression experiments monitoring specific genes revealed that this differential brain development starts earlier, during L3. Analyzing brains from L3 through L5S1 larvae, we identified 21 genes with caste-specific transcription patterns (e.g., APC-4, GlcAT-P, fax, kr-h1 and shot), which encode proteins that are potentially involved in the development of brain tissues through controlling the cell proliferation rate (APC4, kr-h1) and fasciculation (GlcAT-P, fax, and shot). Shot, whose expression is known to be required for axon extension and cell proliferation, was found to be transcribed at significantly higher levels in L4 queens compared with worker larvae. Moreover, the protein encoded by this gene was immunolocalized to the cytoplasm of cells near the antennal lobe neuropiles and proximal to the Kenyon cells in the brains of L4 queens. In conclusion, during the larval period, the brains of queens are larger and develop more rapidly than workers' brains, which represents a developmental heterochrony reflecting the effect of the differential feeding regime of the two castes on nervous system development. Furthermore, this differential development is characterized by caste-specific transcriptional profiles of a set of genes, thus pointing to a link between differential nutrition and differential neurogenesis via genes that control cell proliferation and fasciculation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bees / cytology
  • Bees / genetics*
  • Bees / growth & development*
  • Brain / cytology
  • Brain / growth & development*
  • Brain / metabolism
  • Feeding Behavior*
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Developmental*
  • Larva / cytology
  • Larva / genetics
  • Larva / growth & development
  • Neurogenesis / genetics
  • Nucleic Acid Hybridization
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Time Factors

Substances

  • RNA, Messenger

Grants and funding

This work was funded by grants from Fundação de Amparo à Pesquisa de Minas Gerais (FAPEMIG grant APQ-01714-10; http://www.fapemig.br/), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq grants No 473748/2008-8; 473157/2010-1; http://www.cnpq.br/), and Financiadora de Estudos e Projetos (FINEP/PROINFRA 01/2008, LABSBIOEX UNIFAL-MG) to ARB; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP grant 2005/03926-5; http://www.fapesp.br/) to ZLPS. JV was an undergraduate recipient of a fellowship from FAPEMIG; VB was an undergraduate recipient of a fellowship from CNPq; ACGF was the recipient of a fellowship from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; http://www.capes.gov.br/), and ADB is supported by a FAPESP Doctoral fellowship (Proc. 2009/05675-0). LMRM was the recipient of a postdoctoral fellowship from FAPESP (2009/00810-7). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.