title: Hox gene expression in the specialized limbs of the Iberian mole (Talpa occidentalis).
abstract: Fossorial talpid moles use their limbs predominantly for digging, which explains their highly specialized anatomy. The humerus is particularly short and dorsoventrally rotated, with broadened distal and proximal parts where muscles attach and which facilitate powerful abductive movements. The radius and ulna are exceptionally robust and short. The ulna has an expanded olecranon process. The femur is generalized, but the fused tibia-fibula complex is short and robust. To understand the developmental bases of these specializations, we studied expression patterns of four 5' Hox genes in the fossorial Iberian mole (Talpa occidentalis). These genes are known to play major roles in patterning the developing limb skeleton in the mouse, with which comparisons were made (Mus musculus, C57BL/6Jico strain). We find that HoxA9 expression is spatially expanded in the developing stylopodial area in the mole forelimb, compared to the less specialized mouse forelimb and mole hind limb. HoxD9 expression does not extend into the thoracic body wall in the mole forelimb in contrast to the mouse, and is also reduced in the presumptive zeugopodium in mole forelimb, compared to mouse. Expression of HoxD11 is upregulated in the mole in the postaxial area of the hind limb zeugopod, compared to the mouse. On the other hand, HoxD13 is downregulated in the postaxial zeugopodial area in the forelimb of the mole, compared to the mouse. The differences in the expression patterns of these 5' Hox genes between Talpa and Mus are an indication of the developmental changes going hand in hand with anatomical digging adaptations in the mole adult.
authors.affiliation: Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115, Berlin, Germany.|Paläontologisches Institut und Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 , Zurich, Switzerland.
authors.forename: Constanze
authors.initials: C
authors.lastname: Bickelmann
authors.affiliation: Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115, Berlin, Germany.|Institute of Biology Leiden, Leiden University, Sylviusweg 70, 2333 BE, Leiden, The Netherlands.
authors.forename: Wessel
authors.initials: W
authors.lastname: van der Vos
authors.affiliation: Institute of Biology Leiden, Leiden University, Sylviusweg 70, 2333 BE, Leiden, The Netherlands.
authors.forename: Merijn A G
authors.initials: MA
authors.lastname: de Bakker
authors.affiliation: Departamento de Génetica, University of Granada, Avenida del Conocimiento, Granada, Armilla, 18100, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Jiménez
authors.affiliation: Central Animal Facility, Leiden University Medical Center Leiden, 2300 RC, Leiden, The Netherlands.
authors.forename: Saskia
authors.initials: S
authors.lastname: Maas
authors.affiliation: Paläontologisches Institut und Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 , Zurich, Switzerland.
authors.forename: Marcelo R
authors.initials: MR
authors.lastname: Sánchez-Villagra
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000378:metabolism; D005260:Female; D005552:Forelimb / Q000196:embryology* / Q000378:metabolism; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008971:Moles / Q000033:anatomy & histology* / Q000235:genetics*
chemical_list: D018398:Homeodomain Proteins