In absence of <i>sin1</i>, prechordal plate cells migrate slower and less persistently.

<p>(A) Tracks of prechordal plate nuclei in one representative embryo injected with a control morpholino or the <i>sin1</i> morpholino, dorsal and lateral views (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118474#pone.0118474.s003" target="_blank">S2 Movie</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118474#pone.0118474.s004" target="_blank">S3 Movie</a>). (B) Field of instantaneous speed in the prechordal plate (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0118474#sec015" target="_blank">Materials and Methods</a>). Arrows indicate speed vectors, speed norm is colour-coded. Two-dimensional projections on the three planes have been plotted. (C) Instantaneous speed (measured on 2-minute intervals) of prechordal plate cells and endodermal cells, in embryos injected with the <i>sin1</i> morpholino or a control morpholino. Speed of prechordal plate cells is reduced in <i>sin1</i> loss of function, whereas speed of endodermal cells, used as a control, is not affected. (D) Same as in B, but colour-coding represents the direction of the movement. (E) Orientation of cell movements relative to the direction of the animal pole. In absence of <i>sin1</i>, cell movements are less directed towards the animal pole. (F) Cell persistence, measured as the ratio between the net displacement of the cell and the total length path over ten minute intervals. In absence of <i>sin1</i>, persistence of prechordal plate cells is reduced whereas persistence of endodermal cells is not.