Differential gene expression between developing queens and workers in the honey bee, Apis mellifera

Many insects show polyphenisms, or alternative morphologies, which are base d on differential gene expression rather than genetic polymorphism. Queens and workers are alternative forms of the adult female honey bee and represe nt one of the best known examples of insect polyphenism. Hormonal regulatio n of caste determination in honey bees has been studied in detail, but litt le is known about the proximate molecular mechanisms underlying this proces s, or any other such polyphenism. we report the success of a molecular-gene tic approach for studying queen- and worker-specific gene expression in the development of the honey bee (Apis mellifera). Numerous genes appear to be differentially expressed between the two castes. Seven differentially expr essed loci described here belong to at least five distinctly different evol utionary and functional groups. Two are particularly promising as potential regulators of caste differentiation, One is homologous to a widespread cla ss of proteins that bind lipids and other hydrophobic ligands, including re tinoic acid. The second locus shows sequence similarity to a DNA-binding do main in the Ets family of transcription factors. The remaining loci appear to be involved with downstream changes inherent to queen- or worker-specifi c developmental pathways. Caste determination in honey bees is typically th ought of as primarily queen determination; our results make it clear that t he process involves specific activation of genes in workers as well as in q ueens.