Retinoic acid in Xenopus laevis head mesoderm differentiation.

IBARRA M.A.; MÓNACO M.E.; VILLECCO E.I.; SÁNCHEZ S.S.

San Miguel de Tucumán, Tucumán, Argentina.

Congreso; XLV Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2009

SAIB

Retinoic Acid is known to pattern many tissues during vertebrate embryonic development. There have been many studies analyzing the effects of exogenous Retinoic Acid on neural tube and neural derivatives during Xenopus laevis embryonic development. Those studies showed that retinoic acid avoid the formation of anterior neural structures and stated Retinoic Acid as a posteriorising factor, however its role in antero-posterior patterning in other embryonic tissues remains unclear. In this study we aim to clarify whether retinoic acid has any effect on head mesoderm in Xenopus embryos. We analyzed the alterations by over-expression of the enzyme Cyp26 (RA degrading enzyme) in the head mesoderm territory. We found that the expression pattern of Tbx1 and Pitx2 (specific head mesoderm molecular markers) is altered in the RA-free territories. We also cultured Xenopus embryos from stages 11 to 20 in NAM containing different concentration of Retinoic Acid. Embryos were fixed in glutaraldehyde and the ectoderm (epidermis and neural tissue) was removed with forceps in order to expose the mesoderm layer. Morphological modifications in head mesoderm were analyzed by Scanning Electron Microscopy. We found that the mesoderm tissue was diminished in the anterior region of the treated embryos. Altogether our results suggest that Retinoic Acid signaling could be involved in the head mesoderm set up.