• Open Access

Towards a molecular definition of worker sterility: differential gene expression and reproductive plasticity in honey bees

Authors

  • G. J. Thompson,

    1. School of Biological Sciences, University of Sydney, Sydney NSW, Australia; and Visual Sciences and ARC Center for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia
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  • R. Kucharski,

    1. School of Biological Sciences, University of Sydney, Sydney NSW, Australia; and Visual Sciences and ARC Center for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia
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  • R. Maleszka,

    1. School of Biological Sciences, University of Sydney, Sydney NSW, Australia; and Visual Sciences and ARC Center for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia
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  • B. P. Oldroyd

    1. School of Biological Sciences, University of Sydney, Sydney NSW, Australia; and Visual Sciences and ARC Center for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, Canberra, ACT, Australia
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  • Microarray data meet MIAME standards and have been deposited at ArrayExpress (http://www.ebi.ac.uk/arrayexpress/) with accessions: E-MEXP-699, E-MEXP-705.

  • Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2·5, which does not permit commercial exploitation.

Graham J Thompson, School of Biological Sciences, University of Sydney, Sydney NSW Australia 2006, Australia. Tel.: +61 29036 5216; fax: +61 29351 4771; e-mail: gthompson@usyd.edu.au

Abstract

We show that differences in the reproductive development of honey bee workers are associated with locus-specific changes to abundance of messenger RNA. Using a cross-fostering field experiment to control for differences related to age and environment, we compared the gene expression profiles of functionally sterile workers (wild-type) and those from a mutant strain in which workers are reproductively active (anarchist). Among the set of three genes that are significantly differentially expressed are two major royal jelly proteins that are up-regulated in wild-type heads. This discovery is consistent with sterile workers synthesizing royal jelly as food for developing brood. Likewise, the relative underexpression of these two royal jellies in anarchist workers is consistent with these workers’ characteristic avoidance of alloparental behaviour, in favour of selfish egg-laying. Overall, there is a trend for the most differentially expressed genes to be up-regulated in wild-type workers. This pattern suggests that functional sterility in honey bee workers may generally involve the expression of a suite of genes that effectively ‘switch’ ovaries off, and that selfish reproduction in honey bee workers, though rare, is the default developmental pathway that results when ovary activation is not suppressed.

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