[V ŽIVO!] Prof. Dr. Gašper Tkačik (IST Austria): The many bits of positional information
Half a century after Lewis Wolpert's seminal conceptual advance on how cellular fates distribute in space, I provide a brief perspective on how the concept of positional information emerged and influenced the field of developmental biology and beyond. I focus on a modern interpretation of this concept in terms of information theory, largely centered on its application to cell specification in the early Drosophila embryo. I will argue that a true physical variable (position) is encoded in local concentrations of patterning molecules, that this mapping is stochastic, and that the processes by which positions and corresponding cell fates are determined based on these concentrations need to take such stochasticity into account. With this approach, we can shift the focus from biological mechanisms, molecules, genes and pathways to quantitative systems-level questions: where does positional information reside, how it is transformed and accessed during development, what fundamental limits it is subject to, and what predictions can it help us make?