Introduction:
Noise serves functional roles in biology across different scales,
contrary to intuition. At the micro-scale, biased Brownian motion of the
Myosin head over the Actin filament results in muscle
contraction1,2. At the macro scale, intrinsic
variations in velocity and direction among individual fishes bring about
collectivity in fish schooling3. At the intermediate
mesoscale heterogeneity in the position and alignment of ciliated cells
in the lung tissue facilitates optimal ciliary flow
clearance4. Biological tissues display heterogeneity
in terms of biochemical and mechanical processes within the
cells5. Part of this heterogeneity is deterministic,
such as variations arising from cellular differentiation into distinct
cell types6–9. However, a lot of biological
heterogeneity is observed as stochastic noise10–14.
While the role of deterministic heterogeneity in tissues is intuitive,
stochastic heterogeneity is often characterized as
noise15 and the physiological relevance of this noise
remain largely elusive. We explore the relevance of stochastic
heterogeneity in epithelial function in the following section.