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Fig. 3 iYSN convergence movements are impaired in MZoep mutant embryos. (A,B,D-F) iYSN trajectories in wild-type (A) and MZoep (B,D-F) embryos at the two-somite stage (11 hpf) in dorsal (A,B), paraxial (D), lateral (E) and ventral (F) view. Images are z-projections. Some of the nuclear trajectories obtained using Motion Tracking Software are shown. Circles indicate the endpoint of each track. The white lines in A,B,D mark the dorsal midline of the embryo. Animal pole is towards the top. (A) In wild-type (wt) embryos, iYSN converge from lateral and paraxial regions towards the dorsal side of the embryo, and undergo longitudinal movements along the anteroposterior axis of the gastrula. (B) In MZoep, iYSN from lateral and paraxial regions fail to converge to the dorsal side, but still undergo longitudinal movements in an anterior direction. (C) Comparison of the speed of iYSN movements between wild-type (wt) and MZoep embryos. The average speed of iYSN is similar in wild-type and MZoep embryos [P=0.7412; n=6 (wt); n=2 (MZoep)]. By contrast, the net dorsal speed is significantly lower in MZoep embryos compared with wild type [P<0.0001; n=6 (wt); n=2 (MZoep)]. The negative MZoep value indicates that the net dorsal movement of the nuclei is away from the dorsal midline. Unpaired Student's t-tests were performed to test the differences between mean values. Error bars represent the standard error of the mean. (D-F) iYSN from paraxial, lateral and ventral regions in MZoep mutants show little convergence movements to the dorsal side. In F, the embryo is slightly tilted, and thus some lateral iYSN are observed on the right side of the image moving away from the dorsal region.