The role of diet on microbiome shaping and outcomes in host defensive behaviour and immune defence unveiled through a multiomic approach

• Applicant: Paula Cabral Eterovick, Ph.D.
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Sensory and Behavioural Biology ; Microbial Ecology and Applied Microbiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546565602

Animals have been evolving with symbiotic/commensal microorganisms since their origin. This resulted in an intricate relationship where animals control to some extent microbe colonization of specific parts of their bodies whereas these microbe communities, known as microbiomes, influence from host nutrient assimilation to immune defence and behaviour. Environmental impacts influence host health as well as microbiome composition and gene expression, which, in their turn, may either prevent or aggravate host health deterioration. Food availability and nutritional value are fundamental for host health, microbiome assembly, and also likely to be affected by environmental changes. Thus, I propose to study the effect of diets with varying nutritional quality and protein content on host microbiome composition, gene expression and protein synthesis (both from the host and the microbiome) and how the observed responses to food quality are likely to reflect on host ability to survive, more specifically represented by their mobility (as a surrogate for ability to escape predation) and immune response to pathogen infection. Because amphibians with a larval stage are good indicators of ecosystem health, I will use larvae of Rana temporaria as model organisms. The fungus Batrachochytrium dendrobatidis, responsible for many amphibian population declines and species extinctions worldwide, will be used as a model pathogen due to its relevance for amphibian conservation. I will use recently hatched tadpoles from five clutches initially maintained in water from the original habitat to allow for microbiome colonization. Afterwards tadpoles from each clutch will be individually reared until metamorphosis in rested filtered tap water and receive one of three food types varying in nutritional quality and protein levels. Tadpole and froglet body condition, developmental rate, mobility, and froglet immune defense will be compared among clutches (to account for the influence of genetic background) and food treatments, as well as their microbiomes and potential metabolic pathways (sequences of chemical reactions) underlying the observed outcomes. I expect diet types to promote the establishment of different microbiomes, which will mediate different metabolic pathways and produce different outcomes in host body condition, developmental rate, mobility, and immune defense. I also expect that the metabolic pathways with differing abundances among experimental groups, associated with host physiological/behavioral responses, will bring new information on the important role of microbiomes in promoting host health under varying scenarios of food availability. These results will add to the knowledge about host/microbiome evolution and its potential contributions to species survivorship in a changing world.

• DFG Programme: Research Grants