PhD defense in french
Teams : IVEP (CRCA-CBI) & NNCED (CIRIMAT)
Supervisors : Audrey Dussutour (CRCA-CBI) & Emmanuel Flahaut (CIRIMAT)
Committee members :
- Mme Anna Bencsik, ANSES site de lyon, Rapporteure
- Mme Catherine Santaella, CNRS Institut de Biosciences et Biotechnologies d’Aix-Marseille Université, Rapporteure
- Mme Mélanie Auffan, CNRS CEREGE, Examinatrice
- Mme Noélie Davezac, CNRS CRCA-CBI, Examinatrice
- Mme Audrey Dussutour, CNRS CRCA-CBI, Directrice de thèse
- Emmanuel Flahaut, CNRS CIRIMAT, Co-directeur de thèse
Abstract :
Carbon nanotubes (CNTs) are carbon nanomaterials with industrial development having reached a stage of maturity enabling them to be used in many everyday applications (composite materials, coatings, energy storage, biomedical, etc.). They are a source of concern for human and environmental health because they can be released into the environment at each stage of their life cycle (production, use and end-of-life of finished products). Even though studies relating to their potential impact on health and the environment started some fifteen years ago, many questions remain unanswered.
The aim of this thesis is to assess the effects of CNTs (we used double-walled CNTs (DWCNTs) as representatives of all the different types of CNTs) on an emerging cellular model at the interface between environmental toxicology and cellular toxicology: the myxomycete Physarum polycephalum. On the one hand, P. polycephalum lives mainly in soil litter, a medium that receives and concentrates pollution, where it plays an essential role in the ecosystem by actively participating in the recycling of organic matter. In addition, the simple organization of P. polycephalum (a unicellular eukaryote) enabled us to assess the internalization and bioaccumulation of CNTs within the cell. Finally, the behavioral complexity of P. polycephalum (problem solving and adaptation of their behavior to environmental diversity) enabled us to measure the effects of CNTs on different behavioral variables such as migration speed and decision making. We first demonstrated that CNTs are internalized in the cell, do not bioaccumulate and are rapidly excreted. We then demonstrated that CNTs induce variable effects on the behavior of P. polycephalum (slowed or accelerated speed, optimal or non-optimal decision-making), which differ depending on the strain used, the duration of exposure, the exposure concentration and the substrate used. By combining exposure to CNT with other stress factors (aversive compound, ageing, temperature), we observed a behavioral response that remains extremely variable.
This work shows that CNTs have moderate and difficult-to-quantify effects on the behavioral response of P. polycephalum. In the future, it will be interesting to examine the effects of CNTs on the physiological and molecular response of this organism.
© Photo : Romain Hacquet – @aker.romain
University Paul Sabatier - Toulouse III
