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Fig. 1. Ectopic Xrel3 overexpression in the marginal zone at gastrulation inhibits Xbra expression and prevents involution. Embryos were injected with Xrel3 RNA at the two-cell stage and assayed at early gastrula for the expression of Xbra. Whole mount in situ hybridization analysis was done to stain both Xrel3 and Xbra messages. Because Xrel3 is expressed at a very low level at gastrulation the turquoise staining seen in these embryos represents overexpressed, exogenous Xrel3 RNA. (A) Localization of Xrel3 to the animal pole (white arrow) does not affect Xbra expression (purple stain), shown also in panel B and this does not affect bottle cell formation (D, black arrow in panel B) or axis formation. (F) Injection in the lateral marginal zone resulted in exclusion of Xbra expression, (C) localized inhibition of bottle cell formation (arrow in panel E) and localized defects in yolk incorporation (arrow in panel G). vp—vegetal pole, d—dorsal. Scale bar = 0.5 mm. |