Fig. 1

Knocking out TRβ gene in Xenopus tropicalis does not affect early development. a Genomic structure of X. tropicalis TRβ gene and the CRISPR-short guide RNA (sgRNA) targeting TRβ. There are two known transcripts for X. tropicalis TRβ, each with 7 exons (boxes). The TRβ specific sgRNA was designed to target exon 2 present in both transcripts. The sgRNA sequences are shown in red. b Schematic diagram depicting the sequence of the sgRNA targeted region in the wild type and a TRβ mutant (5 base out-of-frame deletion) animal. Arrows represent primers used for genotyping: the forward primer F and the reverse primer R, respectively. c Mendelian distribution of 4-day old (around stage 45/46) or stage 54 tadpoles obtained from mating two TRβ^(+/−) animals. Genotyping PCR was carried out by using tail tip genomic DNA of randomly selected 4-day old (stage 45/46) and stage 54 tadpoles, the onset of metamorphosis, and the results were close to the expected Mendelian distribution for the three expected genotypes. d Knocking out TRβ does not affect the developmental rate up to the onset of metamorphosis (stage 54). The time in days for each animal obtained from mating two TRβ^(+/−) frogs to reach stage 54 was recorded and presented with the mean, marked as a line, and standard error (SE). No significant difference was observed for the 3 genotypes. e Knocking out TRβ does not affect the animal size and morphology at stage 54. The total body length and snout-vent length were measured on randomly selected animals at stage 54 and presented with the mean, marked as a line, and standard error (SE). No significant difference was observed for the 3 genotypes