%0 Journal Article
%T HOXA13 and HOXD13 expression during development of the syndactylous digits in the marsupial Macropus eugenii
%A Keng Yih Chew
%A Hongshi Yu
%A Andrew J Pask
%A Geoffrey Shaw
%A Marilyn B Renfree
%J BMC Developmental Biology
%D 2012
%I BioMed Central
%R 10.1186/1471-213x-12-2
%X We describe the development of the tammar limbs at key stages before birth. There was marked heterochrony and the hindlimb developed more slowly than the forelimb. Both tammar HOXA13 and HOXD13 have two exons as in humans, mice and chickens. HOXA13 had an early and distal mRNA distribution in the tammar limb bud as in the mouse, but forelimb expression preceded that in the hindlimb. HOXD13 mRNA was expressed earlier in the forelimb than the hindlimb and was predominantly detected in the interdigital tissues of the forelimb. In contrast, the hindlimb had a more restricted expression pattern that appeared to be expressed at discrete points at both posterior and anterior margins of the limb bud, and was unlike expression seen in the mouse and the chicken.This is the first examination of HOXA and HOXD gene expression in a marsupial. The gene structure and predicted proteins were highly conserved with their eutherian orthologues. Interestingly, despite the morphological differences in hindlimb patterning, there were no modifications to the polyalanine tract of either HOXA13 or HOXD13 when compared to those of the mouse and bat but there was a marked difference between the tammar and the other mammals in the region of the first polyserine tract of HOXD13. There were also altered expression domains for both genes in the developing tammar limbs compared to the chicken and mouse. Together these findings suggest that the timing of HOX gene expression may contribute to the heterochrony of the forelimb and hindlimb and that alteration to HOX domains may influence phenotypic differences that lead to the development of marsupial syndactylous digits.The limbs are highly variable structures between different mammalian and vertebrate species [1] enabling them to adapt and exploit new habitats. The vertebrate limb has served as a key model for understanding the signalling pathways controlling patterning and morphogenesis [2]. Limb patterning genes and pathways have been well describe
%U http://www.biomedcentral.com/1471-213X/12/2