Characterization of Ring-Like F-Actin Structure as a Mechanical Partner for Spindle Positioning in Mitosis
Figure 1
Identification of a ring-like F-actin structure during mitosis.
(A) The distribution of F-actin in different phases of mitosis in HeLa cells. Asynchronized cells were fixed and co-stained for F-actin (red), microtubule (green) and DNA (blue). A ring-like F-actin structure appears during metaphase and anaphase and was indicated by the arrows (a, b, c). Scale bar, 5 µm. (B) The representative immunofluorescence images of two cells with cytoplasmic F-actin. Cell A represents the cells with slightly rotated spindles, and Cell B represents the cells with distinctly rotated spindle. The boxed areas are shown magnified in the right panels. Scale bar, 5 µm. (C) Multiple-layer images of Cell A and Cell B. The plane passing through the midpoint of spindle poles and parellel to substrate is chosen as Z = 0, and the images in Fig. 1B is taken at the plane Z = 0. The distance between layer Z and layer Z+1 is 0.2 µm. Scale bar, 5 µm. (D) Astral microtubules and cytoplasmic F-actin structure cross and distribute differently in cytoplasm. The yellow arrows indicate the detailed distribution of astral microtubules. The cytoplasmic F-actin structure distributes around the spindle continuously. The boxed areas are shown magnified 16 times in the bottom panels. Scale bar, 5 µm.