Transgenic <i>Xenopus</i> embryos from sperm nuclear transplantations reveal FGF signaling requirements during gastrulation

TLDR

The method introduces plasmids into decondensed sperm nuclei via restriction enzyme‑mediated integration (REMI). Using REMI‑mediated transgenesis, the authors produced hundreds of diploid embryos per day and showed that a dominant‑negative FGF receptor disrupts mesoderm marker maintenance during gastrulation while leaving neural patterning intact.

Abstract

ABSTRACT We have developed a simple approach for large-scale trans-genesis in Xenopus laevis embryos and have used this method to identify in vivo requirements for FGF signaling during gastrulation. Plasmids are introduced into decondensed sperm nuclei in vitro using restriction enzyme-mediated integration (REMI). Transplantation of these nuclei into unfertilized eggs yields hundreds of normal, diploid embryos per day which develop to advanced stages and express integrated plasmids nonmosaically. Trans-genic expression of a dominant negative mutant of the FGF receptor (XFD) after the mid-blastula stage uncouples mesoderm induction, which is normal, from maintenance of mesodermal markers, which is lost during gastrulation. By contrast, embryos expressing XFD contain well-patterned nervous systems despite a putative role for FGF in neural induction.