Imaging intercellular calcium waves during late epiboly in intact zebrafish embryos

Abstract

Through the injection of f-aequorin and the use of a photon imaging microscope, we have previously reported that a rhythmic series of intercellular Ca2+ waves circumnavigate zebrafish embryos over a 10 h period during gastrulation and axial segmentation. These waves first appear at about 65% epiboly and continue to arise every 5-10 min up to at least the 16-somite stage. In response to our publication, it was suggested that the waves may be an artefact caused by dechorionation of the embryos and would not be observed during the development of intact embryos (i.e. those with chorions). Here we demonstrate (again initially by aequorin imaging) that the rhythmic intercellular Ca2+ waves that traverse the blastoderm margin can also be observed in embryos that have an intact chorion. In addition, the appearance time, propagation pathway, velocity, duration and Ca2+ rise of the waves, as well as the interwave interval and the timing of wave onset, are approximately the same in both dechorionated embryos and those with an intact chorion. Furthermore, by loading intact embryos with Ca2+-green dextran at the single-cell stage and then using scanning confocal microscopy to obtain high-resolution images, we confirm the presence of circumferential Ca2+ waves and show that they pass through a population of deep cells located at the blastoderm margin. The confirmation of these pan-embryonic Ca2+ waves in zebrafish further corroborates our earlier suggestion that such waves might play a fundamental role in normal embryonic patterning during the gastrula period.

Cell signaling, beyond cytosolic calcium in eukaryotes

“…The same toolkit that coordinates cell division and interactions during embryogenesis [13] is also responsible for the rise in [Ca 2+ ] cyt and depletion of the endoplasmic pool of calcium that precedes apoptosis [14].…”

Regulator of G Protein Signaling 3 Modulates Wnt5b Calcium Dynamics and Somite Patterning

“…Zebrafish embryos demonstrate Ca 2+ release dynamics during epiboly, gastrulation, convergent extension and organogenesis [12]–[21]. Two distinct types of Ca 2+ release events, aperiodic transient fluxes found mainly in the enveloping layer and dorsal forerunner cells [17], [18], [22], [23] and sustained increases in Ca 2+ levels in the deep cell layer and yolk syncytial layer [24], [25], have been described.…”

MicroRNA-3906 Regulates Fast Muscle Differentiation through Modulating the Target Gene homer-1b in Zebrafish Embryos

“…Therefore, we asked whether Homer-1b plays a role in fast-twitch muscle differentiation through modulating [Ca 2+ ] i . To address this question, we injected calcium green-1, which can combine with intracellular calcium and release a green fluorescent signal [40], [41], in the one-cell stage of zebrafish embryos. Co-injection of tetramethylrhodamine, which is not affected by calcium ions [42], but appears as a red fluorescent signal, served as an internal control to monitor the volume of each injection.…”