Host-microbiota co-immunity : An intimate relationship that goes beyond defense Position paper for PTPBio

Resident microorganisms, known as the microbiota, are essential for many physiological functions including protection against pathogens. Microbiota is indeed required for proper immune system development and function, and can also host-independently protect against infections. Thus, a coconstructed view of host defense involving both host and microbiota, named “co-immunity”, has been proposed, and the idea of an “immunological holobiont” has been suggested. Yet this view of coimmunity might be too limited, as experimental work has shown that the immune system is involved in functions other than defense, essentially development and repair. Microbiota, through coimmunity, is thereby most likely involved in these functions, although strong evidence is currently lacking. Moreover, as our point of view is mainly host-centered, we may miss the implications of coimmunity at broaderscales, including cellular and populational levels. Intriguingly, co-immunity effects could be beneficial for one function and/or one level, while detrimental for others. All these elements should be taken into consideration for microbiota manipulation, in order to avoid potentially harmful side effects

Plasticity in Cancer Cell Populations: Biology, Mathematics and Philosophy of Cancer

International audienc

“Microbiota, symbiosis and individuality summer school” meeting report

How does microbiota research impact our understanding of biological individuality? We summarize the interdisciplinary summer school on “Microbiota, symbiosis and individuality: conceptual and philosophical issues” (July 2019), which was supported by a European Research Council starting grant project “Immunity, DEvelopment, and the Microbiota” (IDEM). The summer school centered around interdisciplinary group work on four facets of microbiota research: holobionts, individuality, causation, and human health. The conceptual discussion of cutting-edge empirical research provided new insights into microbiota and highlights the value of incorporating into meetings experts from other disciplines, such as philosophy and history of science

The Self Model and the Conception of Biological Identity in Immunology

The self/non-self model, first proposed by F.M. Burnet, has dominated immunology for sixty years now. According to this model, any foreign element will trigger an immune reaction in an organism, whereas endogenous elements will not, in normal circumstances, induce an immune reaction. In this paper we show that the self/non-self model is no longer an appropriate explanation of experimental data in immunology, and that this inadequacy may be rooted in an excessively strong metaphysical conception of biological identity. We suggest that another hypothesis, one based on the notion of continuity, gives a better account of immune phenomena. Finally, we underscore the mapping between this metaphysical deflation from self to continuity in immunology and the philosophical debate between substantialism and empiricism about identity

Considering Intra-individual Genetic Heterogeneity to Understand Biodiversity

In this chapter, I am concerned with the concept of Intra-individual Genetic Hetereogeneity (IGH) and its potential influence on biodiversity estimates. Definitions of biological individuality are often indirectly dependent on genetic sampling -and vice versa. Genetic sampling typically focuses on a particular locus or set of loci, found in the the mitochondrial, chloroplast or nuclear genome. If ecological function or evolutionary individuality can be defined on the level of multiple divergent genomes, as I shall argue is the case in IGH, our current genetic sampling strategies and analytic approaches may miss out on relevant biodiversity. Now that more and more examples of IGH are available, it is becoming possible to investigate the positive and negative effects of IGH on the functioning and evolution of multicellular individuals more systematically. I consider some examples and argue that studying diversity through the lens of IGH facilitates thinking not in terms of units, but in terms of interactions between biological entities. This, in turn, enables a fresh take on the ecological and evolutionary significance of biological diversity

The Problem of Functional Boundaries in Prebiotic and Inter-Biological Systems

International audienceThe concept of organisational closure, interpreted as a set of internally produced and mutually dependent constraints, allows understanding organisms as functionally integrated systems capable of self-production and self-maintenance through the control exerted upon biosynthetic processes and the exchanges of matter and energy with the environment. One of the current challenges faced by this theoretical framework is to account for limit cases in which a robust functional closure cannot be realised from within. In order to achieve functional sufficiency and persist, prebiotic or biological systems may need to recruit external constraints or expand their network of control interactions to include other autonomous systems. These phenomena seem to contrast with the very idea of closure and the capability of living systems to specify their functional boundaries from within. This paper will analyse from an organisational perspective the role of environmental scaffolds and of different classes of intersystem interactions in prebiotic and su-pra-organismal biological scenarios, and show how the theoretical framework based on the notion of closure can account for these cases

Superorganisms of the protist kingdom : a new level of biological organization

The concept of superorganism has a mixed reputation in biology-for some it is a convenient way of discussing supra-organismal levels of organization, and for others, little more than a poetic metaphor. Here, I show that a considerable step forward in the understanding of superorganisms results from a thorough review of the supra-organismal levels of organization now known to exist among the “unicellular” protists. Limiting the discussion to protists has enormous advantages: their bodies are very well studied and relatively simple (as compared to humans or termites, two standard examples in most discussions about superorganisms), and they exhibit an enormous diversity of anatomies and lifestyles. This allows for unprecedented resolution in describing forms of supra-organismal organization. Here, four criteria are used to differentiate loose, incidental associations of hosts with their microbiota from “actual” superorganisms: (1) obligatory character, (2) specific spatial localization of microbiota, (3) presence of attachment structures and (4) signs of co-evolution in phylogenetic analyses. Three groups-that have never before been described in the philosophical literature-merit special attention: Symbiontida (also called Postgaardea), Oxymonadida and Parabasalia. Specifically, it is argued that in certain cases-for Bihospites bacati and Calkinsia aureus (symbiontids), Streblomastix strix (an oxymonad), Joenia annectens and Mixotricha paradoxa (parabasalids) and Kentrophoros (a ciliate)-it is fully appropriate to describe the whole protist-microbiota assocation as a single organism (“superorganism”) and its elements as “tissues” or, arguably, even “organs”. To account for this level of biological complexity, I propose the term “structured superorganism”

The emerging structure of the Extended Evolutionary Synthesis: where does Evo-Devo fit in?

The Extended Evolutionary Synthesis (EES) debate is gaining ground in contemporary evolutionary biology. In parallel, a number of philosophical standpoints have emerged in an attempt to clarify what exactly is represented by the EES. For Massimo Pigliucci, we are in the wake of the newest instantiation of a persisting Kuhnian paradigm; in contrast, Telmo Pievani has contended that the transition to an EES could be best represented as a progressive reformation of a prior Lakatosian scientific research program, with the extension of its Neo-Darwinian core and the addition of a brand-new protective belt of assumptions and auxiliary hypotheses. Here, we argue that those philosophical vantage points are not the only ways to interpret what current proposals to ‘extend’ the Modern Synthesis-derived ‘standard evolutionary theory’ (SET) entail in terms of theoretical change in evolutionary biology. We specifically propose the image of the emergent EES as a vast network of models and interweaved representations that, instantiated in diverse practices, are connected and related in multiple ways. Under that assumption, the EES could be articulated around a paraconsistent network of evolutionary theories (including some elements of the SET), as well as models, practices and representation systems of contemporary evolutionary biology, with edges and nodes that change their position and centrality as a consequence of the co-construction and stabilization of facts and historical discussions revolving around the epistemic goals of this area of the life sciences. We then critically examine the purported structure of the EES—published by Laland and collaborators in 2015—in light of our own network-based proposal. Finally, we consider which epistemic units of Evo-Devo are present or still missing from the EES, in preparation for further analyses of the topic of explanatory integration in this conceptual framework

The many faces of biological individuality

Biological individuality is a major topic of discussion in biology and philosophy of biology. Recently, several objections have been raised against traditional accounts of biological individuality, including the objections of monism (the tendency to focus on a single individuality criterion and/or a single biological field), theory-centrism (the tendency to discuss only theory-based individuation), ahistoricity (the tendency to neglect what biologists of the past and historians of biology have said about biological individuality), disciplinary isolationism (the tendency to isolate biological individuality from other scientific and philosophical domains that have investigated individuality), and the multiplication of conceptual uncertainties (the lack of a precise definition of “biological individual” and related terms). In this introduction, I will examine the current philosophical landscape about biological individuality, and show how the contributions gathered in this special issue address these five objections. Overall, the aim of this issue is to offer a more diverse, unifying, and scientifically informed conception of what a biological individual is