STIPS algorithm enables tracking labyrinthine patterns and reveals distinct rhythmic dynamics of actin microridges.

Abstract

Tracking and motion analyses of semi-flexible biopolymer networks from time-lapse microscopy images are important tools that enable quantitative measurements to unravel the dynamic and mechanical properties of biopolymers in living tissues, crucial for understanding their organization and function. Biopolymer networks are challenging to track due to continuous stochastic transitions, such as merges and splits, which cause local neighbourhood rearrangements over short time and length scales. To address this, we propose the STIPS algorithm (Spatio Temporal Information on Pixel Subsets) to track these events by creating pixel subsets that link trajectories across frames. Using this method, we analysed actin-enriched protrusions, or 'microridges,' which form dynamic labyrinthine patterns on squamous cell epithelial surfaces, mimicking 'active Turing-patterns.' Our results reveal two distinct actomyosin-based rhythmic dynamics in neighbouring cells: a common pulsatile mechanism between 2 and 6.25 minutes period governing both fusion and fission events contributing to pattern maintenance, and cell area pulses predominantly exhibiting 10-minutes period.