Attractive internuclear force drives the collective behavior of nuclear arrays in Drosophila embryos
Fig 2
Characteristic features of the packing pattern and the collective motion pattern of the nuclear array in a representative Drosophila embryo from NC11 to NC14.
(A) A representative heat map of the projected nuclear density along the AP axis of the embryo from NC11 to NC14, i.e., rescaled developmental time from 90 min to 150 min after embryo deposition (AED) at 25°C (see S1 Text). Black triangles label the start time point of chromosome segregation during mitotic phase (M phase) 11, 12 and 13. (B) The dynamics of hexatic bond-orientational order parameter φarray (see Materials and methods). The black arrows 1, 2 and 3 label three time intervals around M phase 11, 12 and 13 showing the minimum order parameter. (C) Bar graph (mean ± standard deviation (SD)) comparing anterior (~5–15% EL) or posterior (~85–95% EL) density and the maximal density in the middle of the embryo during interphase. Student’s t-test results: interphase 12 (anterior, p<0.01; posterior, p<0.01; embryo number n = 4); interphase 13 (anterior, p<0.01; posterior, p = 0.015; n = 4); interphase 14 (anterior, p<0.01; posterior, p<0.01; n = 4). (D) A representative heat map of the nuclear speed projected along the AP axis of the embryo from NC11 to NC14. Positive and negative direction point to the posterior and anterior pole, respectively. (E) Dynamics of the order parameter of the collective motion (φspeed, see Materials and methods) from NC11 to NC14. APi (i = 6–8) corresponds to the ith bin with the width of 10% EL from the anterior pole (for the other bins, see S6 Fig). The markers 1, 2 and 3 label three time windows that show high motion collectivity in (D) and (E). (F) Bar graph comparing the maximal wave crest of the first half period and the second half period of the AP speed standing wave. Student’s t test results: NC12 (p<0.01; n = 4); NC13 (p<0.01; n = 4); NC14 (p<0.01; n = 4). (G) The corresponding dynamics of the nuclear density, speed, smoothed φarray and smoothed φspeed of the nuclear array after the onset of anaphase 12 shown in (A-D).