Tuesday, 26/05/2020 at 11:30 (online, please contact guglielmo.militello@ehu.eus)

Abstract

Paper available (open access) here:
https://www.frontiersin.org/articles/10.3389/fphys.2019.01170/full

The question addressed in this talk is how multicellular systems realise functionally integrated physiological entities by organising their intercellular space. 

From a perspective centred on physiology and integration, biological systems are often characterised as organised in such a way that they realise metabolic self-production and self-maintenance. The existence and activity of their components rely on the network they realise and on the continuous management of the exchange of matter and energy with their environment. One of the virtues of the organismic approach focused on organisation is that it can provide an understanding of how biological systems are functionally integrated into coherent wholes.

Organismic frameworks have been primarily developed by focusing on unicellular life. Multicellularity, however, presents additional challenges to our understanding of biological systems, related to how cells are capable to live together in higher-order entities, in such a way that some of their features and behaviours are constrained and controlled by the system they realise. Whereas most accounts of multicellularity focus on cell differentiation and increase in size as the main elements to understand biological systems at this level of organisation, these factors are insufficient to provide an understanding of how cells are physically and functionally integrated in a coherent system.

To address these issues, I present a new theoretical framework of multicellularity. The thesis is that one of the fundamental theoretical principles to understand multicellularity, which is missing or underdeveloped in current accounts, is the functional organisation of the intercellular space. From this perspective, the capability to be organised in space plays a central role in this context, as it enables (and allows to exploit all the implications of) cell differentiation and increase in size, and even specialised functions such as immunity. The extracellular matrix plays a crucial active role in this respect, together with the strategies employed by multicellular systems to exert control upon internal movement and communication. Finally, I show how the organisation of space is involved in some of the failures of multicellular organisation, such as aging and cancer.

To participate online, please contact: guglielmo.militello@ehu.eus.

Date: 12/05/2020, at 11:30

Abstract: The concept of identity is used both (i) to distinguish a system as a particular material entity that is conserved as such in a given environment (token-identity: i.e., identity as permanence or endurance over time), and (ii) to relate a system with other members of a set (type-identity: i.e., identity as an equivalence relationship). Biological systems are characterized, in a minimal and universal sense, by a highly complex and dynamic, far-from-equilibrium organization of very diverse molecular components and transformation processes (i.e., ‘genetically-instructed cellular metabolisms’) that maintain themselves in constant interaction with their corresponding environments, including other systems of similar nature. More precisely, all living entities depend on a deeply convoluted organization of molecules and processes (a naturalized von Neumann constructor architecture) that subsumes, in the form of current individuals (autonomous cells), a history of ecological and evolutionary interactions (across cell populations). So one can defend, on those grounds, that living beings have an identity of their own from both approximations: (i) and (ii). These transversal and trans-generational dimensions of biological phenomena, which unfold together with the actual process of biogenesis, must be carefully considered in order to understand the intricacies and metabolic robustness of the first living cells, their underlying uniformity (i.e., their common biochemical core) and the eradication of previous –or alternative– forms of complex natural phenomena. Therefore, a comprehensive approach to the origins of life requires conjugating the actual properties of the developing complex individuals (fusing and dividing protocells, at various stages) with other, population-level features, linked to their collective-evolutionary behaviour, under much wider and longer-term parameters. On these lines, I will argue that life, in its most basic sense, here on Earth or anywhere else, demands crossing a high complexity threshold and that the concept of ‘inter-identity’ can help us realize the different aspects involved in the process.

The talk will be given on 28/04/2020 at 11:30. For participating, please contact guglielmo.militello@ehu.eus

Tuesday 07 April at 11:30, Online (please contact Guglielmo Militello, guglielmo.militello@ehu.eus, to participate)

Abstract: In this seminar we will share some ideas about the type of non-equilibrium physico-chemical processes from which more complex, protometabolic reaction pathways and transformation cycles can develop. The concepts of self-organization and self-assembly will be discussed, describing some concrete examples to illustrate them, and explaining why we consider they are relevant but not rich enough to account for minimal forms of metabolism. Autonomy, instead, will be suggested as a more adequate theoretical construct to grasp/explore metabolic dynamics, to be distinguished from a collection of coupled chemical reactions by a set of relational criteria that we are currently working on.

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.