Quentin Devalloir a le plaisir de vous convier à la soutenance de sa thèse intitulée : Effets de stresseurs multiples (pollution et qualité nutritionnelle) sur l’immunocompétence du mulot sylvestre. La soutenance aura lieu jeudi 22 juin 2023 à 16h dans l’Amphi Duffieux (bâtiment Propédeutique, la Bouloie, Besançon).

Invitation à télécharger ICI

Composition du jury

• Supervisors
   Pr Renaud Scheifler
   Pr Nico van den Brink
• Examiners
   Pr Bruno Faivre
   Pr Christy Morrissey
   Dr Frédéric Angelier
   Dr Aurélie Goutte
• Invited members
   Dr Clémentine Fritsch
   Dr Cécile Grand

Abstract
Effects of multi stressors (pollution, nutritional quality) on the immunocompetence of wood mice
In a rapidly changing environment, multiple stressors can affect the health of wild animals. Among these stressors, exposure to pollutants and low nutritional quality can enhance physiological disorders and modulate the ability of the immune system to respond efficiently to an infection, a phenomenon called immunocompetence. Exposure to toxic metals, like cadmium and lead, affects the structure and the functioning of immune cells, while micronutrients like selenium are dietary compounds having beneficial effects on the immune response when taken in adequate amounts. However, the influence of micronutrients on the effect of toxic metals has been mainly studied in laboratory experiments but remains obscure in wild animals. The present thesis aimed to disentangle the influence of exposure to toxic metals and of nutritional quality on the immunocompetence of a small mammal, the wood mouse. Chapter 1 reviewed the ability of some beneficial micro elements or vitamins to alleviate the damage to the immune system caused by exposure to toxic metals in wild and captive mammals. In Chapter 2, free ranging wood mice were captured in sites exhibiting high and low levels of soil pollution by cadmium and lead and were either immediately challenged (using lipopolysaccharides of bacteria, LPS) or challenged after five days of captivity with standard or selenium deficient food. Immune response was affected by exposure to cadmium and lead through endocrine disturbances. Wild animals exposed to elevated levels of toxic metals displayed higher inflammatory responses to immune challenge, while individuals maintained in captivity for five days showed lower immune responses when fed a selenium deficient diet. The characterisation of the immune response of wild animals is, generally speaking, constrained by the lack of appropriate methods since most methods and markers have been developed on laboratory animals. For this reason, Chapter 3 was dedicated to the development of blood reference intervals for wood mice and other rodent species. Reference intervals are commonly used in medicine or veterinary science for health diagnoses but are very scarce for free ranging non domestic species. Variations in blood cell counts were found to be affected by season and location of wood mouse populations rather than by biological parameters (age, sex...). The use of reference intervals allowed to sort healthy from unhealthy individuals of a given population by using a non lethal approach In line with this, Chapter 4 proposed non lethal methods to assess health and inflammatory status in wood mice. A pro inflammatory cytokine (TNF-α), a mediator of the inflammation, was measured in blood and spleen cells of wild caught captive wood mice. An increase of inflammatory markers was found in wild caught captive wood mice challenged with LPS. Altogether, these results suggested that nutritional quality has a positive influence on the immunocompetence of wild animals chronically exposed to toxic metals. Immunomarkers and blood reference intervals provided relevant tools for assessing the immunocompetence of wood mice.