Fig. 2.

TRα regulates metamorphic timing. (a) TRα knockout tadpoles develop faster. One representative animal is shown for each of the three genotypes: wild type, heterozygous, and homozygous TRα knockout siblings. Dashed boxes in the left panel were enlarged and shown in the right panel. Note that the homozygous TRα knockout tadpole had significantly larger and more advanced hindlimb buds. (b) TRα knockout tadpoles develop into more advanced stages. The stage of individual sibling tadpoles in the three genotypes was plotted with the median (darker solid line) for each genotype shown in the figure. Note that homozygous TRα knockout tadpole reached a median stage of 51 while the wild-type and TRα heterozygous knockout tadpoles reached a median stage of 47.5. (c) TRα knockout tadpoles initiate metamorphosis, i.e., reaching stage 54, at a younger age. The age in days for each tadpole to reach stage 54 was plotted with the median (darker solid line) for each genotype shown in the figure. “**” indicates significant difference between homozygous knockout and the other groups (P < 0.01). See [38] for more details