title: Insulin-like peptide genes in honey bee fat body respond differently to manipulation of social behavioral physiology.
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 factor-specific 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 expression-localization 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.
authors.affiliation: University of Life Sciences, Department of Chemistry, Biotechnology and Food Science, N-1432 Aas, Norway.
authors.forename: Kari-Anne
authors.initials: KA
authors.lastname: Nilsen
authors.forename: Kate E
authors.initials: KE
authors.lastname: Ihle
authors.forename: Katy
authors.initials: K
authors.lastname: Frederick
authors.forename: M Kim
authors.initials: MK
authors.lastname: Fondrk
authors.forename: Bente
authors.initials: B
authors.lastname: Smedal
authors.forename: Klaus
authors.initials: K
authors.lastname: Hartfelder
authors.forename: Gro V
authors.initials: GV
authors.lastname: Amdam
mesh_terms: D000418:Albumins / Q000378:metabolism; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001516:Bees / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D005216:Fat Body / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000187:drug effects; D017344:Genes, Insect / Q000235:genetics*; D006458:Hemolymph / Q000187:drug effects / Q000378:metabolism; D006722:Honey; D007328:Insulin / Q000235:genetics* / Q000378:metabolism; D007605:Juvenile Hormones / Q000378:metabolism; D008954:Models, Biological; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D012919:Social Behavior; D017186:Titrimetry; D014819:Vitellogenins / Q000235:genetics / Q000378:metabolism
chemical_list: D000418:Albumins; D000596:Amino Acids; D007328:Insulin; D007605:Juvenile Hormones; D012333:RNA, Messenger; D014819:Vitellogenins