title: Reconstruction and in vivo analysis of the extinct tbx5 gene from ancient wingless moa (Aves: Dinornithiformes).
abstract: BACKGROUND
  The forelimb-specific gene tbx5 is highly conserved and essential for the development of forelimbs in zebrafish, mice, and humans. Amongst birds, a single order, Dinornithiformes, comprising the extinct wingless moa of New Zealand, are unique in having no skeletal evidence of forelimb-like structures.
  
  
  RESULTS
  To determine the sequence of tbx5 in moa, we used a range of PCR-based techniques on ancient DNA to retrieve all nine tbx5 exons and splice sites from the giant moa, Dinornis. Moa Tbx5 is identical to chicken Tbx5 in being able to activate the downstream promotors of fgf10 and ANF. In addition we show that missexpression of moa tbx5 in the hindlimb of chicken embryos results in the formation of forelimb features, suggesting that Tbx5 was fully functional in wingless moa. An alternatively spliced exon 1 for tbx5 that is expressed specifically in the forelimb region was shown to be almost identical between moa and ostrich, suggesting that, as well as being fully functional, tbx5 is likely to have been expressed normally in moa since divergence from their flighted ancestors, approximately 60 mya.
  
  
  CONCLUSIONS
  The results suggests that, as in mice, moa tbx5 is necessary for the induction of forelimbs, but is not sufficient for their outgrowth. Moa Tbx5 may have played an important role in the development of moa's remnant forelimb girdle, and may be required for the formation of this structure. Our results further show that genetic changes affecting genes other than tbx5 must be responsible for the complete loss of forelimbs in moa.
authors.forename: Leon
authors.initials: L
authors.lastname: Huynen
authors.forename: Takayuki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ogura
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Craig D
authors.initials: CD
authors.lastname: Millar
authors.forename: Michael
authors.initials: M
authors.lastname: Hofreiter
authors.forename: Craig
authors.initials: C
authors.lastname: Smith
authors.forename: Sara
authors.initials: S
authors.lastname: Mirmoeini
authors.affiliation: Environmental Futures Centre, Griffith University, 170 Kessels Road, Nathan Qld 4111, Australia. D.lambert@griffith.edu.au.
authors.forename: David M
authors.initials: DM
authors.lastname: Lambert
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics; D030161:Avian Proteins / Q000235:genetics* / Q000378:metabolism; D005075:Biological Evolution; D002645:Chickens; D051526:Fibroblast Growth Factor 10 / Q000235:genetics; D005426:Flight, Animal; D005552:Forelimb / Q000196:embryology*; D006801:Humans; D051379:Mice; D009520:New Zealand; D046108:Palaeognathae / Q000235:genetics* / Q000502:physiology; D020310:Struthioniformes / Q000196:embryology; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D030161:Avian Proteins; D051526:Fibroblast Growth Factor 10; D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5; D009320:Atrial Natriuretic Factor