IAS-Research Talk by Gabriel Piedrafita: Tissue-level cell-fate coordination underpins epithelial clone competition dynamics: theoretical modeling to open a conceptual discussion

Date and time: September 25, Tuesday, 11:30 a.m.

Location: Carlos Santamaría Building, Room B14.

Speaker: Gabriel Piedrafita, Wellcome Trust Sanger Institute (Cambridge, UK)

Title: Tissue-level cell-fate coordination underpins epithelial clone competition dynamics: theoretical modeling to open a conceptual discussion

Abstract: Epithelia are among the simplest mammalian tissues. Yet, little is known about how epithelial cells organize and orchestrate their fates (whether to divide, differentiate or die) to guarantee the turnover while preserving tissue homeostasis. Over a decade, theoretical models have been proposed according to which individual progenitor cell behavior would accommodate toautonomous, random fate choices, with remarkably good fits – at a statistical level – on lineage-tracing data from transgenic mice. It was my aim in this work to revisit these studies, and re-evaluate previous paradigms with an emphasis on bringing statistical-physics descriptions closer to the biological phenomenology at the cell level. By means of new experimental data and mathematical modeling, I will show how epithelial homeostasis can conform to simple rules where niche-sensing and collective cell-fate coordination play a predominant role. I would like to finish discussing how this domain of tissue-level communication would necessary constrain and impact on mutant clonal expansion, contributing to an internal control of tumourogenesis, letting the topic open for further debate.

IAS-Research Seminar by Miguel Aguilera: “Integrated information and autonomy in the thermodynamic limit”

Date and time: June 26, Tuesday, 11:30 a.m.

Location: Carlos Santamaría Building, Room B14.

Speaker: Miguel Aguilera (sci@maguilera.net)

Title: Integrated information and autonomy in the thermodynamic limit

Abstract: The concept of autonomy is fundamental for understanding biological organizationand the evolutionary transitions of living systems. Understanding how a system constitutes itself as an individual, cohesive, self-organized entity is a fundamental challenge for the understanding of life. However, it is generally a difficult task to determine whether the system or its environment has generated the correlations that allow an observer to trace the boundary of a living system as a coherent unit. Inspired by the framework of integrated information theory, we propose a measure of the level of integration of a system as the response of a system to partitions that introduce perturbations in the interaction between subsystems, without assuming the existence of a stationary distribution. With the goal of characterizing transitions in integrated information in the thermodynamic limit, we apply this measure to kinetic Ising models of infinite size using mean field techniques. Our findings suggest that, in order to preserve the integration of causal influences of a system as it grows in size, a living entity must be poised near critical points maximizing its sensitivity to perturbations in the interaction between subsystems. Moreover, we observe how such a measure is able to delimit an agent and its environment, being able to characterize simple instances of agent-environment asymmetries in which the agent has the ability to modulate its coupling with the environment.