Figure 5.

Truncation in the TRIO GEFD1 Reduces Head Size in X. tropicalis

(A) X. tropicalis eggs from a single female for each of two biological replicates (with parents from different genetic backgrounds) were fertilized with frozen sperm and injected at the one-cell stage with CRISPR-Cas targeting the genome as shown. Representative micrographs for each condition are shown (black and white photos) (all tadpoles are shown in Figure S3). Performing the GEFD1 and GEFD2 frameshift in a tubb2B.GFP X. tropicalis showed that forebrain deformities had occurred in 6/8 GEFD1 truncation tadpoles, which was not the case for GEFD2 frameshift. Representative micrographs for each condition are shown (color photos) (all tadpoles are shown in Figure S4).

(B) Comparing the head diameter of the tadpoles carrying truncations in the GEFD1 (hs: Gln 1489^∗ = xt Gln 1450) and GEFD2 (hs: Leu 2031^∗ = xt Leu 1994) domains showed that GEFD1 truncations caused microcephaly, whereas GEFD2 truncations had no effect. Quantification is shown for eight individuals measured (all tadpoles are shown in Figure S3).