Journal Article

The Making of a Queen: TOR Pathway Is a Key Player in Diphenic Caste Development

Patel, Avani, Emore, Christine, Hunt, Greg, Fondrk, M. Kim, Kaftanoglu, Osman, Frederick, Katy, Amdam, Gro V.

2007

Overview

Honey bees (Apis mellifera) provide a principal example of diphenic development. Excess feeding of female larvae results in queens (large reproductives). Moderate diet yields workers (small helpers). The signaling pathway that links provisioning to female developmental fate is not understood, yet we reasoned that it could include TOR (target of rapamycin), a nutrient- and energy-sensing kinase that controls organismal growth. Here, the role of Apis mellifera TOR (amTOR) in caste determination is examined by rapamycin/FK506 pharmacology and RNA interference (RNAi) gene knockdown. We show that in queen-destined larvae, the TOR inhibitor rapamycin induces the development of worker characters that are blocked by the antagonist FK506. Further, queen fate is associated with elevated activity of the Apis mellifera TOR encoding gene, amTOR, and amTOR gene knockdown blocks queen fate and results in individuals with worker morphology. A much-studied insect dimorphism, thereby, can be governed by the TOR pathway. Our results present the first evidence for a role of TOR in diphenic development, and suggest that adoption of this ancestral nutrient-sensing cascade is one evolutionary pathway for morphological caste differentiation in social insects.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Animal behavior / Animals / Apis mellifera / Bees / Bees - physiology / Behavior, Animal - physiology / Caste determination / Caste differentiation / Developmental Biology/Developmental Evolution / Dimorphism / Drosophila / European honeybee / Evolutionary Biology/Genomics / Female / Females / Foraging behavior / Gene expression / Gene Expression Regulation, Developmental / Genetics and Genomics/Functional Genomics / Genetics and Genomics/Gene Function / Hierarchy, Social / Honey / Insects / Insulin / Intracellular Signaling Peptides and Proteins - antagonists & inhibitors / Intracellular Signaling Peptides and Proteins - genetics / Intracellular Signaling Peptides and Proteins - metabolism / Laboratories / Larva - growth & development / Larva - metabolism / Larvae / Life sciences / Metabolism / Morphology / Nutrients / Pharmacology / Protein-Serine-Threonine Kinases - antagonists & inhibitors / Protein-Serine-Threonine Kinases - genetics / Protein-Serine-Threonine Kinases - metabolism / Provisioning / Queens / Rapamycin / Ribonucleic acid / RNA / RNA, Small Interfering - pharmacology / RNA-mediated interference / Signal transduction / Sirolimus - pharmacology / Tacrolimus / TOR protein / TOR Serine-Threonine Kinases / Workers (insect caste)