Wednesday, November 11, 2015: 12:50 PM
150G (Salt Palace Convention Center)
The growth and patterning of developing epithelia result in tissues with spatially heterogeneous mechanical properties. Differential mechanical force distributions are increasingly recognized to provide important feedback into the control of an organ’s final size and shape. However, the ability to quantitatively probe the mechanical properties of tissues is still in its infancy. As a second messenger that integrates and relays mechanical information to the cell, calcium ions (Ca2+) are a prime candidate for providing important information on both the overall mechanical state of the tissue and resulting behavior at the individual-cell level during development. Still, how the spatiotemporal properties of Ca2+ transients reflect the underlying mechanical characteristics of tissues is still poorly understood. Here we use an established model system for epithelial tissue, the Drosophila wing imaginal disc, to investigate how tissue properties impact the propagation of Ca2+ transients induced by single cell laser ablations. Because experimentally manipulating mechanical properties is difficult to do without also impacting cellular differentiation, a computational model of calcium transients is employed to investigate how cell size and cell elongation (anisotropy) affect the spatiotemporal patterning of intercellular calcium flashes. We find that single cell ablations lead to intercellular Ca2+ transients that show spatially non-uniform characteristics across the proximal-distal (PD) axis of the larval wing imaginal disc and that relative Ca2+ flash anisotropy is principally explained by the local cell shape anisotropy. Further, Ca2+ velocities are relatively uniform throughout the wing disc, irrespective of cell size or anisotropy. This can be explained by the opposing effects of cell diameter and cell elongation on intercellular Ca2+ propagation. Thus, intercellular Ca2+ transients follow lines of mechanical tension at velocities that are largely independent of tissue heterogeneity and reflect the mechanical state of the underlying tissue.