At every moment from fertilisation onwards the creation of a human body requires cells, generated by cell division, to “choose” which of the many possible kinds of cell they will become. How do they decide?
One common view is that there was some step-by-step decision-making process or algorithm to follow. New research from a team of French biologists led by Alice Moussy of the Ecole Pratique des Hautes Etudes suggests that this is not the case.
The researchers microscopic video recordings and single-cell molecular analyses to observe the process of hematopoietic stem cells (cells which can become any one of a number of different kinds of blood cell). They discovered that rather than a single decision event, cell specialisation was a dynamic process involving spontaneous fluctuations between alternative cell states and selective stabilisation of certain states.
In a sense it is a trial-and-error process: each cell independently “tries out” different molecular possibilities – via turning on and off different genes – before settling into a stable state of activated genes and a corresponding shape.