Fig. 1.

Late rescue of UV irradiation via injection of LiCl or XSiamois mRNA results in heterotaxia in embryos with a normal DAI. (A) One-cell embryos are exposed to UV irradiation from the vegetal side. Method 1: XSiamois mRNA is injected into a vegetal blastomere at the 16-cell stage. Method 2: LiCl is injected into a third tier blastomere at the 32-cell stage. (B) Organ situs of rescued embryos with DAI=5 compared with untreated embryos. All embryos were determined to be wild type or heterotaxic (inverted placement of at least one asymmetric organ). Of the heterotaxic embryos, the percentage with situs inversus (randomization of all three organs) is reported. Red arrowhead, heart loop; green arrowhead, gall bladder; yellow arrowhead, stomach.