Computational modelling of cell chain migration reveals mechanisms that sustain follow-the-leader behaviour

Follow-the-leader chain migration is a striking cell migratory behaviour observed during vertebrate development, adult neurogenesis and cancer metastasis. Although cell–cell contact and extracellular matrix (ECM) cues have been proposed to promote this phenomenon, mechanisms that underlie chain migration persistence remain unclear. Here, we developed a quantitative agent-based modelling framework to test mechanistic hypotheses of chain migration persistence. We defined chain migration and its persistence based on evidence from the highly migratory neural crest model system, where cells within a chain extend and retract filopodia in short-lived cell contacts and move together as a collective. In our agent-based simulations, we began with a set of agents arranged as a chain and systematically probed the influence of model parameters to identify factors critical to the maintenance of the chain migration pattern. We discovered that chain migration persistence requires a high degree of directional bias in both lead and follower cells towards the target. Chain migration persistence was also promoted when lead cells maintained cell contact with followers, but not vice-versa. Finally, providing a path of least resistance in the ECM was not sufficient alone to drive chain persistence. Our results indicate that chain migration persistence depends on the interplay of directional cell movement and biased cell–cell contact

The Evolutionary Path of the Law

What lessons can legal scholars learn from the life and work of W. D. "Bill" Hamilton, a lifelong student of nature? From my small corner of the legal Academia, three aspects of Bill Hamilton’s work in evolutionary biology stand out in particular: (i) Hamilton’s simple and beautiful model of social behavior in terms of costs and benefits; (ii) his fruitful collaboration with the political theorist Robert Axelrod and their unexpected yet elegant solution of the Prisoner’s Dilemma, an important game or puzzle that had defied solution until Hamilton and Axelrod came along; and (iii) Hamilton’s conception of science generally -- and in particular his view of the process of scientific justification -- as a form of trial advocacy. In this review of Ullica Segerstråle’s recently-published biography of Bill Hamilton, the author briefly recounts and reviews each one of these important contributions