Ca²⁺ signaling during embryonic cytokinesis in animal systems

In this chapter, we provide a review of the literature that describes the role of Ca²⁺ signaling during embryonic cytokinesis in animal systems. We begin with a historic overview (starting with the earliest reports published in the latter part of the nineteenth century) that gives some of the first descriptions linking Ca²⁺ with cell division in embryos. This introductory overview also outlines the different techniques that were used and developed over time, from the pre-Ca²⁺ imaging days through to the sophisticated approaches that are available today for directly visualizing Ca²⁺ signals in living cells. In the remainder of the chapter, we describe the more recent advances in cytokinetic Ca²⁺-signaling research, starting where the introduction finished, in the 1990s. Reports of the various Ca²⁺ signals visualized during cytokinesis in fish, amphibian, echinoderm, and insect embryos using both fluorescent and luminescent Ca²⁺ probes are described, as well as the investigations carried out to determine both the requirement of elevated Ca²⁺ during cytokinesis and the source of the Ca²⁺ involved in this process. The current hypotheses regarding the possible roles and targets of the different cytokinetic Ca²⁺ signals observed are also briefly discussed.