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Hox genes are evolutionarily conserved developmental regulatory genes that function, in part, to pattern the anterior-posterior (AP) axis of organs and organ systems during animal embryonic development. Hoxa5, specifically, is shown to be expressed in the spinal cord, somites, or transient compartments giving rise to the vertebrae and ribs, developing gut, lungs, and limbs of the mouse (Mus musculus). The cis-regulatory elements (CREs), or short DNA sequences, that direct Hoxa5 expression in these embryonic domains have been mapped and functionally tested in the mouse as well. Similar Hoxa5 expression patterns have been observed in chicken (Gallus gallus), American alligator (Alligator mississipiensis), and dogfish shark (Scyliorhinus canicular), but have shown divergence in the anterior limit of expression within the somites. Specifically, while mouse expression begins in somite 3, chicken, alligator, and shark begin in 8, 9, and 9, respectively. Further, no Hoxa5a expression has been observed in the somites for teleost fish. Here, we present the Hoxa5 expression pattern within brown anole (Anolis sagrei) lizard embryos. Our data shows that Hoxa5 within the lizard has an anterior limit of expression in somite 6, exhibiting a more similar expression pattern to that of mouse, chicken, alligator, and shark than to teleost fishes. Furthermore, our comparative genomic DNA sequence analyses display that most of the functional CREs mapped in the mouse are conserved among the tetrapods, but not with the shark or teleost fishes. Our analyses suggest that divergent Hoxa5 expression patterns result from divergence within their respective CREs.

Keywords: Hox genes, Anolis sagrei, cis-regulatory elements, Hoxa5 gene expression, embryonic development, somite


File nameDate UploadedVisibilityFile size
20 Jul 2022
2.99 MB
20 Jul 2022
2.99 MB



  • Subject
    • Biology

  • Institution
    • Gainesville

  • Event location
    • Nesbitt 3110

  • Event date
    • 25 March 2022

  • Date submitted

    20 July 2022

  • Additional information
    • Acknowledgements:

      Adam Davis