Biological systems, from cells to organisms, must respond to the ever-changing environment in order to survive and function. This is not a simple task given the often random nature of the signals they receive, as well as the intrinsically stochastic, many-body and often self-organized nature of the processes that control their sensing and response and limited resources. Despite a wide range of scales and functions that can be observed in the living world, some common principles that govern the behavior of biological systems emerge. Here I review two examples of very different biological problems: information transmission in gene regulatory networks and diversity of adaptive immune receptor repertoires that protect us from pathogens. I discuss the trade-offs that physical laws impose on these systems and show that the optimal designs of both immune repertoires and gene regulatory networks display similar discrete tiling structures. These solutions rely on locally non-overlapping placements of the responding elements (genes and receptors) that, overall, cover space nearly uniformly.
Les systèmes biologiques, depuis la cellule jusqu'à l'organisme, ne peuvent survivre et fonctionner que s'ils s'adaptent aux changements continuels de l'environnement. Ce n'est pas une tâche aisée, à cause de la nature aléatoire des signaux qu'ils reçoivent, de la nature collective et souvent autoorganisée des phénomènes qui contrôlent leur réponse, et aussi en raison de la limitation des ressources. Malgré la diversité des échelles et des fonctions qu'on observe dans le monde vivant, on peut faire apparaître quelques principes généraux qui gouvernent le comportement des systèmes biologiques. Je considère ici deux exemples très différents de problèmes biologiques : la transmission de l'information dans les réseaux de régulation des gènes et le système immunitaire adaptatif qui nous protège des agents pathogènes. Je discute les compromis que les lois physiques imposent à ces systèmes, et je montre que la structure optimale des systèmes immunitaires comme des réseaux de régulation des gènes est organisée de façon semblable, en forme de pavage discret. Ces solutions correspondent à des dispositions sans recouvrement des unités de réponse (gènes et récepteurs) qui remplissent l'espace de façon presque uniforme.
Mots-clés : Solutions de pavage, Régulation stochastique des gènes, Répertoires immunitaires, Optimisation en biologie
Aleksandra M. Walczak 1
@article{CRPHYS_2015__16_8_761_0,
author = {Aleksandra M. Walczak},
title = {Tiling solutions for optimal biological sensing},
journal = {Comptes Rendus. Physique},
pages = {761--772},
publisher = {Elsevier},
volume = {16},
number = {8},
year = {2015},
doi = {10.1016/j.crhy.2015.09.004},
language = {en},
}
Aleksandra M. Walczak. Tiling solutions for optimal biological sensing. Comptes Rendus. Physique, Volume 16 (2015) no. 8, pp. 761-772. doi : 10.1016/j.crhy.2015.09.004. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2015.09.004/
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