Inhibition of eFGF expression in Xenopus embryos by antisense mRNA

We studied the effects in Xenopus embryos of overexpression of antisense RNA complementary to the messenger RNA of eFGF. We show that the expression of sense RNA can be severely depressed in the presence of an excess of antisense RNA. This occurs by both partial destruction of the message and by a depression of translation of the residual message. The diminution of inducing activity of eFGF, measured in animal cap assays either by activation of the Brachyury gene or by morphology, parallels the reduction of translation. Endogenous eFGF expression is reduced to a similar extent, again by a combination of mRNA destruction and inhibition of translation. This shows that the overexpression of antisense RNA is, contrary to general opinion, a potentially useful technique for studying gene function in Xenopus embryos. However, in the case of eFGF, there is little or no overall phenotypic effect on whole embryos. This is probably because of the presence of several other FGFs with overlapping expression domains in the early embryo.