Gradient sensing limit of an elongated cell with orientational control

Area of Science:

• Cell biology
• Biophysics
• Systems biology

Background:

• Eukaryotic cells use chemotaxis to navigate chemical gradients by sensing concentrations at their surface.
• Previous research on gradient estimation accuracy often simplified cell shapes (e.g., circular) or assumed fixed elongated orientations.
• The influence of dynamic cell shape regulation on chemotaxis estimation limits remains largely unexplored.

Purpose of the Study:

• To investigate the theoretical limits of gradient estimation accuracy in eukaryotic cells with dynamically regulated elongated shapes.
• To determine how adaptive cell shape orientation impacts the efficiency of chemotaxis.
• To elucidate the interplay between cell shape, signal sensing, and chemotactic control.

Main Methods:

• Analysis of the stationary solution of the Bayesian nonlinear filtering equation.
• Application of diffusion approximation to ligand-receptor binding dynamics.
• Utilized the Laplace method for posterior expectation under high signal-to-noise ratio conditions to derive analytical expressions.

Main Results:

• Derived an analytical expression for the estimation limit of chemical gradients.
• Demonstrated that optimal estimation accuracy is achieved when the cell's elongated axis is oriented perpendicular to the gradient direction.
• Numerical simulations confirmed the analytical findings regarding shape-dependent estimation improvement.

Conclusions:

• Adaptive regulation of cell shape, specifically orientation, can significantly enhance chemotactic gradient estimation accuracy.
• Cells may strategically adjust their shape to optimize sensing and improve chemotactic efficiency.
• This study provides a framework for understanding how cellular morphology and control mechanisms are integrated for effective gradient sensing.