The many bits of positional information

• Published in: Development (Cambridge) Vol. 148; no. 2
• Main Authors: Tkačik, Gašper, Gregor, Thomas
• Format: Journal Article
• Language: English
• Published: England Company of Biologists 01.02.2021; The Company of Biologists Ltd
• Subjects: Animals; Bioengineering; Biological Evolution; Biological Physics; Body Patterning; Body Patterning - genetics; Development Biology; Humans; Imaging; Information Theory; Life Sciences; Models, Biological; Morphogenesis; Physics; Quantitative Methods; Review; Pattern formation; Shannon information; Developmental biology; Drosophila embryo; Lewis Wolpert
• ISSN: 0950-1991; 1477-9129; 1477-9129
• DOI: 10.1242/dev.176065

Half a century after Lewis Wolpert's seminal conceptual advance on how cellular fates distribute in space, we provide a brief historical perspective on how the concept of positional information emerged and influenced the field of developmental biology and beyond. We 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. We 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 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, and what fundamental limits it is subject to?