中文摘要：

母亲的 Wnt11 为在 Xenopus 胚胎的 Spemann 组织者的形成必要、足够。Xnr3 和 Siamois 在组织者正式就职期间作为母亲的 Wnt11/-catenin 的直接目标基因被识别了。母亲的 XTcf3 的弄空导致了 Xnr3 和 Siamois 的宫外的表示，建议 -catenin/XTcf3 的活动严格地在早 Xenopus 胚胎被调整。这里，我们证明 Xenopus mga (Xmga ) 是为背面的轴形成要求的母亲的基因。Overexpression 实验显示老鼠 Mga 加强在组织者特定的基因的正式就职的 -catenin 的活动。母亲的 Xmga 的弄空导致组织者基因和 ventralization 显型的表示的戏剧的减少，显示 Xmga 为 -catenin 功能和组织者形成被要求。XTcf3 的弄空不能在弄空 Xmga 的胚胎救组织者基因表示和轴形成，建议 Xmga 在组织者正式就职期间的 XTcf3 是下游的。我们断定母亲的 Xmga 在组织者形成和 Xenopus 胚胎的背面的开发期间为 -catenin 的函数是批评的。到我们的知识，这第一次是一份报告含有在调整 Wnt 发信号的 Mga。

英文摘要：

Maternal Wntll is both necessary and sufficient for the formation of Spemann organizer in Xenopus embryo. Xnr3 and Siamois have been identified as the direct target genes of maternal Wntll/β-catenin during organizer in- duction. The depletion of maternal XTcf3 resulted in the ectopic expression of Xnr3 and Siamois, suggesting the ac- tivity of β-catenin/XTcf3 is strictly regulated in the early Xenopus embryos. Here, we show that Xenopus mga （Xmga） is a maternal gene required for dorsal axis forma- tion. Overexpression experiments indicate that mouse Mga potentiates the activity of β-catenin in the induction of organizer-specific genes. Depletion of maternal Xmga results in the dramatic decrease of the expression of organizer genes and ventralization phenotype, indicating that Xmga is required for β-catenin function and organ- izer formation. Depletion of XTcf3 cannot rescue organ- izer gene expression and axis formation in Xmga-depleted embryos, suggesting Xmga is downstream of XTcf3 during organizer induction. We conclude that maternal Xmga is critical for the function of β-catenin during organizer for- marion and dorsal development of Xenopus embryo. To our knowledge, this is a report for the first time to impli- cate Mga in regulating Wnt signaling.