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Fig. 1
Determining integration time of the Tol2 transposon following injection in 1–2 cell embryos.
(A) A plasmid construct containing the ubiquitously expressed Xenopus ef1α promoter driving GFP (Xef1α>GFP) and flanked by Tol2 transposon arms was co-injected with transposase mRNA into 1–2 cell embryos. (B) Following injection, typical mosaic Xef1α>GFP expression at 2 days. Note that a small minority of cells, in a wide variety of tissues, is labeled throughout the embryo. (C) Model relating the size of the germ cell precursor (GCP) population at the time of integration of the Xef1α>GFP transposon to transmission rates from F0 founders to their F1 progeny. (D) F0 founders grouped by the developmental stages at which integration took place, as inferred from the number of calculated GCPs. Number of GCPs based on previous counts of vasa mRNA expressing cells at various stages of development [30], [31]. Note that the majority of integration events occur after the mid blastula transition and prior to the end of the shield stage (59% unadjusted, 75% adjusted).