Figure 2. EGA and translation appear normal in cybrid embryos.

(A) Transcription of key embryonic genes is normal in [l]xt cybrids. Real-time RT-PCRs were carried out to compare relative mRNA/total RNA quantities for the indicated genes in stage 10.25 [l]xt cybrid embryos as compared to that in txt. Relative mRNA quantities were found to be identical for Vegt and Xbra at stage 10.25 between txt and [t]xt (unpublished data). Error bars represent the standard deviation between three to six replicate experiments, each of which is the average of three to six single embryos. No significant difference was found (p>0.05; two-tailed t test) for any of the genes tested. (B) Xbra protein is synthesized normally from the X. tropicalis genome by the X. laevis cytoplasm. Western blot analysis was carried out to evaluate Xbra protein levels in stage 11 embryos of the indicated combinations. ^§ [l]xt embryos never morphologically reach stage 11, but they were harvested when [l]xl siblings reached stage 11. Ran was used as a loading control as it is present at the same concentration in the eggs of both species [67]. (C) Quantification of pixel intensity indicates a significant (∼2-fold) increase in Xbra protein concentration at stage 11 in txt relative to lxl (p = 0.014; one-tailed t test with unequal variance; n = 4).