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Benjamin S. Wortman1; Shafiya M.S. Khan; Amber L. Rittgers; John McGinnis; Michael A. White; Adam Davis

An Analysis of Hoxa3 Gene Expression and Regulation across Gnathostomes

Benjamin S. Wortman¹, Shafiya M.S. Khan², Amber L. Rittgers³, John McGinnis¹, Michael A. White¹, and Adam Davis^4*

¹Department of Genetics, University of Georgia, Athens GA 30602, USA. ²Department of Physical Therapy, Brenau University, Gainesville GA 30501, USA. ³Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta GA 30322, USA. ⁴Department of Biology, University of North Georgia, Oakwood GA 30566, USA. ^*Corresponding author.

eBio, No. 12 (2024)

Abstract
Hoxa3 is an evolutionarily conserved developmental regulatory gene that is expressed within the posterior rhombomeres (r) and pharyngeal arches (PA). Previous molecular genetic studies have shown that Hoxa3 in tetrapods and smaller spotted catsharks, as well as hoxa3a, hoxa3aα and hoxa3aβ in teleost fishes, show a conserved anterior limit of expression in r5 and PA3. Further, a conserved enhancer region, termed the r5/r6 region, upstream of Hoxa3 in the mouse and chicken was shown to direct Hoxa3 expression at these anterior limits. In this study, we show that Hoxa3 of Anolis sagrei (brown anole) and hoxa3a of Gasterosteus aculeatus aculeatus (three-spine stickleback) exhibit conserved anterior limits of expression. However, our bioinformatics analyses show that, while Hoxa3 in brown anoles and other tetrapods, the coelacanth, the smaller spotted catshark, and the spotted gar, exhibit conservation with the functional sequences tested in mice and chickens, these sequences have diverged in teleost fishes. This divergence may be due to the whole-genome duplication that occurred in the lineage leading to teleosts.

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