Evidence for Compartmentalized Calcium Dynamics from Scale-Dependent Imaging Measurements

Abstract

As one of the most essential cell processes, calcium signalling reveals cellular responses to stimuli. The different spatial scales used to measure each signal can impact the activity observed. This study explores whether the measurement scale will impact any activity observed using a high-resolution time-lapse (TIFF) file. Circular regions of interest were used to vary the measurement scale, including radii ranging from 2.0 pixels to 20.0 pixels. To measure change in calcium signal activity, I compared variability (ΔF/F₀) and signal amplitude (signal-to-noise ratio or SNR) across each spatial scale. Smaller spatial scales reflected the highest signal variance (≈ 0.0033), revealing highly localized fluctuations, consistent with stochastic calcium dynamics in cellular microdomains. Larger spatial scales had a lower variance (≈ 0.0003) but also a significantly smaller amplitude (≈ 5.13). The larger scale captured a more stable dynamic but also lost some signal due to averaging with background pixels, revealing a contrasting dynamic in an integrated cellular region. The results showed that calcium signalling is spatially organized, revealing a distinct dynamic in a localized compartment in comparison to an integrated cellular region.