51社区黑料

Synopsis

Cells rely on chemical cues to navigate migration, yet the reliability of these cues is constrained by transport physics and the stochastics of molecular interactions. The first part of this work considers autologous chemotaxis, i.e., cells migrating by following gradients they produce themselves. Using both analytical transport theory and simulation, it is shown that at low density, cells can sustain directional migration. However, at increasing density, overlapping secretions cause the resulting chemical environment to become homogenized. For concentration fields beyond a certain predictable limit, their bias toward directionality vanishes and single-cell chemotaxis fails. This failure is not complete: cell aggregates are able to recover directional guidance by using their collective geometry and thus effectively reintroduce asymmetry of the field via multi-cell sensing.

This section examines cells as they navigate environments with more than one, and possibly antagonistic, cue. Through the measurement of the information content of each message and comparison with behavioral outputs, it is determined that certain systems bias cues based on their statistical validity and come close to achieving optimal integration of information. Others privilege intrinsic biases even if this means decreased information acquisition and infer that cells are optimizing goals beyond gross sensing accuracy, e.g., robustness to noise or energetic thrift.

Together, these results show that there are cell functions at the borderline of physical constraints, sometimes leading to failure as crowding suppresses gradients, yet they also work out methods, through collective control and integration of several cues, of augmenting their sense of the environment.