Fig. 1

Mesendodermal cells display runs and tumbles during directed migration. a Schematic of the single cell transplantation experiments where mesendoderm progenitor cells are transplanted into a wt or MZoep host. b Lateral view of a host embryo (ectodermal nuclei are labeled with Histone-Alexa 647 in blue) at 60 % epiboly (7hpf) with an example track of a control (green) mesendoderm cell transplanted into the lateral germ ring margin at 50 % epiboly (5.5hpf). Scale bar = 50 μm. c Two-dimensional probability density of the alignment index (A) and scaled speed (S), P(A,S), calculated for mesendodermal cells transplanted into wt hosts (n = 18). The blue dashed line shows the linear fit to the maximum values of P(A,S) for A. The red dashed line is the line, perpendicular to the maximum, defining the threshold above which a portion of a trajectory is considered to be a run phase (also in d). The intersection point is at A = 0.52, corresponding to the local minimum between the global maximum and the nearest local maximum of P(A,S) along the maximum line (displayed in d). d One-dimensional cross-section of P(A,S) along the maximum line, S*(A). e Instantaneous speed of single mesendoderm cells transplanted into wt and MZoep hosts during run and tumble phases. N = 854 runs and 478 tumbles in MZoep hosts (23 cells) and 1317 runs and 484 tumbles in wt hosts (18 cells). Statistical significance by t-test. f Exemplary three-dimensional cell trajectory displaying run (dark green) and tumbling phases (light green). The points represent cell positions over time. Scale bar = 50 μm. g Two-dimensional probability density P(A,S), calculated for mesendodermal cells transplanted into MZoep hosts (N = 23). Lines as in c. The intersection point is at A = 0.3. h Like “d” for probability density in “g”