Visceral organ situs after formin inhibition.

(A) Representative images of formin-modulated stage 46 tadpoles displaying normal organ situs (ss), situs inversion (si), or heterotaxia (ht), as determined by the direction of heart looping (outlined by dashed red line) and gut coiling (outlined by dashed violet line), ventral view. (B) Formin inhibitor SMIFH2 had no effect on organ situs in the tadpoles treated during cleavage (N = 5) and reduced the proportion of tadpoles with normal organ laterality after treatment with 10 μM SMIFH2 during gastrulation and neurulation (N = 5). a, anterior; ht, heterotaxia; l, left; p, posterior; r, right; si, situs inversus; ss, situs solitus. Cyan arrows indicate heart ventricle, yellow arrows indicate truncus arteriosus. ***, p-value = 0,00006552 compared with the DMSO control, two-proportions z-test with Bonferroni correction; N, number of experiments. Numbers at the base of columns represent number of analyzed embryos.