Multiple types of calcium signals are associated with cell division in zebrafish embryo

Recent studies suggested that a Ca2+ signal is involved in the regulation of cell division. For example, using a confocal imaging technique, we have shown that a localized Ca2+ elevation was clearly associated with the onset of cytokinesis in zebrafish embryo [Chang and Meng (1995) J. Cell Biol. 131:1539-1545]. This finding was later confirmed in studies using aequorin as a Ca2+ probe. Here, we used a 4-D confocal measurement technique to further characterize the properties of the Ca2+ signal associated with cell division. We found evidence that there were three types of Ca2+ signals associated with different stages of cell cleavage in embryonic cell. The first type was repetitive Ca2+ spikes that emerged several minutes before the first cell cleavage began. These Ca2+ spikes were first distributed broadly over the central region of the blastodisc and then gradually localized in the equatorial region; they appeared to play the role of determining the position of the first cleavage plane. The second type was a calcium wave that propagated along the cleavage furrow and appeared to guide the furrow extension during the progression of cytokinesis. The third type was a group of post-cleavage calcium spikes that appeared to be responsible for furrow deepening and maintenance of the contractile band. When this type of Ca2+ transient was blocked by injecting BAPTA or heparin, cell cleavage regressed and the structure of the contractile band could no longer be maintained. Microsc. Res. Tech. 49:111-122, 2000. (C) 2000 Wiley-Liss, Inc.