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Open Access Research article

Rapid bursts of androgen-binding protein (Abp) gene duplication occurred independently in diverse mammals

Christina M Laukaitis1, Andreas Heger2, Tyler D Blakley3, Pavel Munclinger4, Chris P Ponting5 and Robert C Karn6*

Author Affiliations

1 Department of Medical Genetics, University of Washington, Seattle, USA and Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, USA

2 MRC Functional Genetics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK

3 Department of Biological Sciences, Butler University, Indianapolis, USA

4 Department of Zoology, Faculty of Sciences, Charles University in Prague, Praha, Czech Republic

5 MRC Functional Genetics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK

6 Department of Biological Sciences, Butler University, Indianapolis, USA and Department of Genome Sciences, University of Washington, Seattle, USA

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BMC Evolutionary Biology 2008, 8:46  doi:10.1186/1471-2148-8-46

Published: 12 February 2008

Abstract

Background

The draft mouse (Mus musculus) genome sequence revealed an unexpected proliferation of gene duplicates encoding a family of secretoglobin proteins including the androgen-binding protein (ABP) α, β and γ subunits. Further investigation of 14 α-like (Abpa) and 13 β- or γ-like (Abpbg) undisrupted gene sequences revealed a rich diversity of developmental stage-, sex- and tissue-specific expression. Despite these studies, our understanding of the evolution of this gene family remains incomplete. Questions arise from imperfections in the initial mouse genome assembly and a dearth of information about the gene family structure in other rodents and mammals.

Results

Here, we interrogate the latest 'finished' mouse (Mus musculus) genome sequence assembly to show that the Abp gene repertoire is, in fact, twice as large as reported previously, with 30 Abpa and 34 Abpbg genes and pseudogenes. All of these have arisen since the last common ancestor with rat (Rattus norvegicus). We then demonstrate, by sequencing homologs from species within the Mus genus, that this burst of gene duplication occurred very recently, within the past seven million years. Finally, we survey Abp orthologs in genomes from across the mammalian clade and show that bursts of Abp gene duplications are not specific to the murid rodents; they also occurred recently in the lagomorph (rabbit, Oryctolagus cuniculus) and ruminant (cattle, Bos taurus) lineages, although not in other mammalian taxa.

Conclusion

We conclude that Abp genes have undergone repeated bursts of gene duplication and adaptive sequence diversification driven by these genes' participation in chemosensation and/or sexual identification.