Comparação da expressão dos genes Dapper com a de marcadores moleculares para desenvolvimento dos membros de aves (Gallus gallus) / Comparison of the expression pattern of the Dapper genes with the expression of molecular markers for limb development in chicken (Gallus gallus)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2011

RESUMO

The acquisition of vertebrates limbs represents an important novelty for this group and allowed the expansion of vertebrates through the Biosphere. The molecular basis of limbs development are under intense investigation, and the role of several genes and signaling molecules begin to be understood both within the context of axis determination as well as in the patterning of tissues and structures. The Dapper (Dpr) gene family has been associated with different processes of vertebrates embryogenesis, from the coordination of morphogenetic movements during gastrulation to morphogenesis of structures as different as brain, eyes and heart. However, nothing is known about the role of these genes in limb development, am important domain of Dpr expression during the embryogenesis of vertebrates. Preliminary results of in situ hybridization in chicken embryo obtained in our laboratory had already shown the expression of these genes in limb, suggesting that they could play an important role in the ontogeny of these structures. Thus, in this study the Dpr1 and Dpr2 expression pattern was characterized by in situ hybridization between stages HH24 and HH34 of chicken development. We also determined the expression of the molecular markers MyoD (skeletal muscle) and Sox9 (cartilage) and stained limbs at the different stages with alcian blue, that labels the extracellular matrix of cartilage. The results revealed that, at stage HH24, Dpr1 expression is observed in the proximal and medial mesenchyme in the fore and hindlimb buds but avoids the autopod. At this stage, the expression of Dpr2 is clearly associated with mesenchymal condensations of pre-chondrogenic cells. At stage HH25, Dpr1 and Dpr2 transcripts were found for the first time in the autopod, delimiting a region with the shape of the cartilaginous templates of the developing digits. At stage HH28, Dpr1 is still expressed around the developing digits, and transcripts are found at high levels in the tarsi and carpi precursors. In turn, Dpr2 is expressed strongly in the first and fifth digits of the forelimbs and hindlimbs, as well as in the digit blastemas. Finally, at stage HH34, Dpr1 and Dpr2 transcripts are concentrated in the developing joints, while Dpr2 is also expressed in ectodermal tendons and developing skin appendages. This study strongly supports the hypothesis that Dpr1 and Dpr2 play a role in the process of chondrogenesis before the formation of the limb bones in birds as well as the development of other structures such as tendons and skin appendages

ASSUNTO(S)

condrogênese desenvolvimento muscular genes dapper extremidades - crescimento e desenvolvimento chondrogenesis muscle development dapper genes extremities

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