The transcription factor bhlh paraxis in Xenopus laevis dorsal fin.

SANCHEZ R.S.; MONACO M.E.; SANCHEZ S.S.

Buenos Aires, Argentina

Congreso; 4th International Meeting of the Latin American Society of Developmental Biology (LASDB); 2008

Latin American Society of Developmental Biology (LASDB)

In the amphibian embryo, the mature dorsal fin is a single keel-shaped out-pocketing of the dorsal epidermis that is supported by mesenchymal cells and extracellular matrix. The dorsal fin develops as a result of inductive signals from the Neural Crest (NC). The epidermis in the nascent fin undergoes cell proliferation and extends dorsally, accompanied by an accumulation of extracellular matrix. During tailbud stages, mesenchymal cells derived of the trunk NC migrate into the fin matrix, which differentiate in pigment cells during the early tadpole stages.Recent studies of dorsal fin development in the axolotl and frog indicate that, in addition to the trunk NC population, cells originally located in the dorsomedial region of the somite also contribute to the fin mesenchyme. In Xenopus laevis, Wnt11-R is expressed in both population cells, before and during the migration process to the dorsal fin. In this work we studied the expression of the transcription factor bHLH paraxis, a somitic marker, during later stages of Xenopus development. We showed that expression domain of paraxis persists in the dorsal somite and appears in the dorsal fin. The Wnt11-R expression was also confirmed in the same regions of paraxis. In order to establish if Wnt signalling pathway is related to paraxis expression in the dorsal fin, we carried out experiments using an inhibitor of the Wnt signaling pathway, the valproic acid. In vivo experiments show that valproic acid-treated embryos present altered dorsal fin and no paraxis expression. These data suggest that paraxis is regulated by Wnt signaling pathway and these molecules are probably involved in the structure maintenance of dorsal fin in X. laevis.