Live-cell imaging of rapid calcium dynamics using fluorescent, genetically-encoded GCaMP probes with Aspergillus fumigatus

Calcium signalling plays a fundamental role in fungal intracellular signalling. Previous approaches (fluorescent dyes, bioluminescent aequorin, genetically encoded cameleon probes) with imaging rapid subcellular changes in cytosolic free calcium ([Ca2+]c) in fungal cells have produced inconsistent results. Recent data obtained with new fluorescent, genetically encoded GCaMP probes, that are very bright, have resolved this problem. Here, exposing conidia or conidial germlings to high external Ca2+, as an example of an external stressor, induced very dramatic, rapid and dynamic [Ca2+]c changes with localized [Ca2+]c transients and waves. Considerable heterogeneity in the timing of Ca2+ responses of different spores/germlings within the cell population was observed.

Automated summary

The use of new fluorescent, genetically encoded GCaMP probes has resolved inconsistencies in previous methods for observing calcium signaling in fungal cells. Exposing fungal conidia or germlings to high external Ca2+ induces dramatic, rapid, and dynamic changes in calcium signaling. Substantial variability in the timing of calcium responses among different spores/germlings within the cell population is observed.