Projekt

Zurück zur Übersicht

Evolutionary adaptation of gut and microbiome to chronic malnutrition in Drosophila

Titel Englisch Evolutionary adaptation of gut and microbiome to chronic malnutrition in Drosophila
Gesuchsteller/in Kawecki Tadeusz
Nummer 162732
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Département d'Ecologie et d'Evolution Faculté de Biologie et de Médecine Université de Lausanne
Hochschule Universität Lausanne - LA
Hauptdisziplin Zoologie
Beginn/Ende 01.02.2016 - 31.01.2019
Bewilligter Betrag 600'000.00
Alle Daten anzeigen

Alle Disziplinen (3)

Disziplin
Zoologie
Oekologie
Experimentelle Mikrobiologie

Keywords (6)

adaptation; evolution; drosophila; microbiome; host-parasite interaction; genomics

Lay Summary (Französisch)

Lead
Beaucoup d’espèces animales doivent surmonter des épisodes de famine. On peut donc s’attendre à ce que la sélection naturelle ait conduit à l’évolution d’adaptations spécifiques améliorant la tolérance des organismes à la malnutrition. Il est dans certains cas possible de révéler ces adaptations en étudiant la réponse physiologique de l’individu soumis à la malnutrition. Cependant, une façon plus certaine de les mettre en évidence, consiste à repérer quels variants génétiques sont favorisés dans des populations soumises à la malnutrition sur plusieurs générations. Cette approche, désignée par le terme d’« évolution expérimentale », nous permet, dans les conditions du laboratoire, d’étudier en temps réel les changements évolutifs qui se produisent dans des populations de mouches du vinaigre (Drosophila) maintenues depuis bientôt 200 générations dans des conditions de malnutrition au stade larvaire.
Lay summary

Le but de ce projet est de comprendre comment la modification de la physiologie de ces larves peut leur permettre de mieux exploiter la nourriture de médiocre qualité. Nous nous intéressons notamment à la physiologie et à la structure du système digestif, en quantifiant l’efficacité de la digestion et de l’absorption des nutriments ; il s’agit aussi de comprendre la sensibilité accrue des individus des populations soumises à la malnutrition aux pathogènes intestinaux. Parallèlement, nous analysons l’expression des gènes sur l’ensemble du génome ainsi que la composition du métabolome afin d'identifier les mécanismes moléculaires sous-jacents à la tolérance à la malnutrition. Un troisième volet de notre étude concerne l’adaptation des bactéries commensales hébergées dans l’intestin des drosophiles (le microbiote intestinal) qui participent à la digestion des nutriments, au milieu nutritionnellement pauvre auquel leur hôte est soumis. Chez l’humain, il a été suggéré que les adaptations permettant de tolérer la malnutrition pouvaient en partie expliquer la susceptibilité aux maladies métaboliques ainsi que certains problèmes médicaux liés à l’âge ("thrifty genotype hypothesis"). Dans la mesure où les voies de signalisation impliquées dans la réponse à la nutrition sont similaires chez l’humain et la mouche, nos travaux de recherche pourront participer à une meilleure compréhension de processus touchant à la santé et au bien-être humain.

Direktlink auf Lay Summary Letzte Aktualisierung: 03.12.2015

Lay Summary (Englisch)

Lead
Many animal species must live through periods of famine. The ability to survive, develop and even reproduce under such nutritional stress must have been favored by natural selection, leading to the evolution of specific adaptations improving malnutrition tolerance. While some of these adaptations can be inferred from flexible physiological responses of individual animals to malnutrition, a more direct way to study such adaptations is to which traits change genetically in populations regularly exposed to malnutrition over many generations. We use such an "experimental evolution" approach: we study in real time evolutionary changes in laboratory populations of fruit flies (Drosophila) exposed to chronic juvenile (larval) malnutrition for over 200 generations.
Lay summary

In this project, we aim to understand how the physiology of malnutrition-adapted Drosophila larvae changed to enable them cope better with poor-quality food. One aspect of the project focuses on the physiology and structure of the digestive system, quantifying the efficiency of nutrient digestion and absorption, as well as aiming to understand the reasons for an increased susceptibility of the malnutrition-adapted populations to intestinal pathogens. In parallel, we are analyzing genome-wide gene expression data and will combine them with state-of-the-art analysis of metabolites to identify molecular pathways underlying malnutrition tolerance. A third aspect of the project focuses on the adaptation of gut microbiota, i.e., the commensal bacteria that live in Drosophila gut and help them to acquire nutrients, in response to the host feeding regime. Adaptations to tolerate malnutrition have been proposed to be partially responsible for human vulnerability to metabolic diseases and some age-related medical problems (the "thrifty genotype hypothesis"). As responses to nutrition involve similar signaling pathways in human and flies, our research will throw light on processes that are also relevant for human health and well-being.

Direktlink auf Lay Summary Letzte Aktualisierung: 03.12.2015

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Verbundene Projekte

Nummer Titel Start Förderungsinstrument
143939 Evolutionary adaptation to chronic malnutrition in Drosophila 01.12.2012 Projektförderung (Abt. I-III)

Abstract

The general aim of the proposed research is to understand how evolution shapes the physiology of animal gut and its microbiome in response to chronic exposure to juvenile malnutrition, an important ecological stress factor for many animal species, including human ancestors. The project uses experimental evolution, with D. melanogaster as the model system. It consists of three interrelated subprojects. First, we will study evolutionary changes in gut physiology that enhance the ability of Drosophila larvae to tolerate chronic larval malnutrition. We will take advantage of six replicate experimental Drosophila populations that evolved for >170 generations on an extremely nutrient-poor larval food. These Selected populations now survive much better and grow markedly faster on the poor food than Control populations of the same origin, indicating that they have evolved adaptations allowing them to cope better with malnutrition. We will test the hypothesis that they extract more nutrients from the low-quality food than the Control larvae, and quantify potential underlying mechanisms, including greater volume and surface of the gut, higher expression and activity of digestive enzymes, greater absorption rate of digested nutrients and changes in the peritrophic matrix. The evolutionary responses of those traits will be compared to their phenotypically plastic (physiological) responses to poor food, allowing us to assess to what degree the latter predict the former. We will also quantify these processes in the adults in order to understand the apparent trade-off between larval and adult tolerance to malnutrition previously found in these populations.Second, we will aim to identify causes of lower resilience of the malnutrition-tolerant populations to intestinal pathogens. We discovered that larvae and adults of the Selected populations described above evolved greater susceptibility to disintegration of their intestinal wall upon infection with a virulent pathogen (Pseudomonas entomophila), despite showing a similar immune response and being able to clear the pathogens as effectively as the Controls. We will test two potential mechanisms, increased permeability of the peritrophic matrix and impairment of gut repair based on intestinal stem cells. The results will throw light on mechanisms of an apparent evolutionary trade-off between the dual roles of the gut in nutrient acquisition and protection from pathogens.In the third subproject the focus shifts from evolution of Drosophila to evolution of its commensal microbiome - we will study how adaptation of the microbiome to host's malnutrition affects the host's own fitness. On the one hand, commensal microbes better adapted to poor nutritional conditions may be able to thrive better, enhancing their beneficial effect on the host. On the other hand, natural selection under nutritional limitation may favor commensal species or strains which are better at competing with the host for the scarce nutrients, at the expense of host fitness. We will test these contradictory predictions by allowing controlled microbiomes to evolve in association with the host under poor versus standard nutritional regime, and using microbiome transplants to test their effects on the host's performance.Evolutionary adaptations of our ancestors to periodic malnutrition and responses of microbiome to nutrition have both been implicated in the human susceptibility to disease. Our study would throw light on such putative links in a model species.
-