XWNT-11 - A MATERNALLY EXPRESSED XENOPUS WNT GENE

We have isolated and characterized a novel Xenopus wnt gene, Xwnt-11, whose expression pattern and overexpression phenotype suggest that it may be important for dorsal-ventral axis formation. Xwnt-11 mRNA is pr esent during oogenesis and embryonic development through swimming tadp ole stages. Xwnt-11 mRNA is ubiquitous in early oocytes and is localiz ed during mid-oogenesis. By late oocyte stages, Xwnt-11 mRNA is locali zed to the vegetal cortex, with some mRNA in the vegetal cytoplasm. Af ter egg maturation, Xwnt-11 mRNA is released from the vegetal cortex a nd is found in the vegetal cytoplasm. This early pattern of Xwnt-11 mR NA localization is similar to another vegetally localized maternal mRN A, Vg1 (D. A. Melton (1987) Nature 328, 80-82). In the late blastula, Xwnt-11 mRNA is found at high levels in the dorsal marginal zone. As g astrulation proceeds, Xwnt-11 mRNA appears in the lateral and ventral marginal zone and, during tadpole stages, it is found in the somites a nd first branchial arch. Injection of Xwnt-11 mRNA into UV-ventralized embryos can substantially rescue the UV defect by inducing the format ion of dorsal tissues. The rescued embryos develop somitic muscle and neural tube; however, they lack notochord and anterior head structures .