Journal article

Co-option of the cardiac transcription factor Nkx2.5 during development of the emu wing

Peter G Farlie, Nadia M Davidson, Naomi L Baker, Mai Raabus, Kelly N Roeszler, Claire Hirst, Andrew Major, Mylene M Mariette, David M Lambert, Alicia Oshlack, Craig A Smith



The ratites are a distinctive clade of flightless birds, typified by the emu and ostrich that have acquired a range of unique anatomical characteristics since diverging from basal Aves at least 100 million years ago. The emu possesses a vestigial wing with a single digit and greatly reduced forelimb musculature. However, the embryological basis of wing reduction and other anatomical changes associated with loss of flight are unclear. Here we report a previously unknown co-option of the cardiac transcription factor Nkx2.5 to the forelimb in the emu embryo, but not in ostrich, or chicken and zebra finch, which have fully developed wings. Nkx2.5 is expressed in emu limb bud mesenchyme and matur..

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Funding Acknowledgements

Special thanks to Phil and Penny Henley of Emu Logic and Michael Hastings of Hastings Ostrich Farm for helpful advice and eggs. This project was supported by funding from the Australian Research Council to D.M.L. and C.A.S. and from the National Health and Medical Research Council Australia to P.G.F. The Murdoch Children's Research Institute is supported by the Victorian Government's Operational Infrastructure Program.