Insulin-like peptide genes in honey bee fat body respond differently to manipulation of social behavioral physiology

Kari Anne Nilsen, Kate E. Ihle, Katy Frederick, M. Kim Fondrk, Bente Smedal, Klaus Hartfelder, Gro Amdam

Research output: Contribution to journalArticle

65 Scopus citations

Abstract

Nutrient sensitive insulin-like peptides (ILPs) have profound effects on invertebrate metabolism, nutrient storage, fertility and aging. Many insects transcribe ILPs in specialized neurosecretory cells at changing levels correlated with life history. However, the major site of insect metabolism and nutrient storage is not the brain, but rather the fat body, where functions of ILP expression are rarely studied and poorly understood. Fat body is analogous to mammalian liver and adipose tissue, with nutrient stores that often correlate with behavior. We used the honey bee (Apis mellifera), an insect with complex behavior, to test whether ILP genes in fat body respond to experimentally induced changes of behavioral physiology. Honey bee fat body influences endocrine state and behavior by secreting the yolk protein precursor vitellogenin (Vg), which suppresses lipophilic juvenile hormone and social foraging behavior. In a two-factorial experiment, we used RNA interference (RNAi)-mediated vg gene knockdown and amino acid nutrient enrichment of hemolymph (blood) to perturb this regulatory module. We document factorspecific changes in fat body ilp1 and ilp2 mRNA, the bee's ILP-encoding genes, and confirm that our protocol affects social behavior. We show that ilp1 and ilp2 are regulated independently and differently and diverge in their specific expressionlocalization between fat body oenocyte and trophocyte cells. Insect ilp functions may be better understood by broadening research to account for expression in fat body and not only brain.

Original languageEnglish (US)
Pages (from-to)1488-1497
Number of pages10
JournalJournal of Experimental Biology
Volume214
Issue number9
DOIs
StatePublished - May 2011

Keywords

  • Division of labor
  • Nutrition
  • Peripheral insulin-like signaling
  • RNA-interference
  • Vitellogenin

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science

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