Soutenance publique de thèse de doctorat en Sciences biologiques - Mathilde Oger

Neurodevelopmental disruption in zebrafish: investigating the roles of polystyrene micro- and nanoparticles-mediated methylmercury toxicity

Jury

• Prof. Frédéric SILVESTRE (UNamur), Président
• Prof. Patrick KESTEMONT (UNamur), Secrétaire
• Dr Valérie CORNET (UNamur)
• Prof. Eli THORÉ (UNamur)
• Prof. Jérôme CACHOT (Université de Bordeaux)
• Dr Krishna DAS (Université de Liège)

Résumé

Plastic pollution has emerged as a pervasive environmental threat, with micro- and nanoplastics (MPs and NPs) accumulating across ecosystems and organisms, including humans. Their ability to adsorb and transport contaminants raises critical concerns for both environmental and public health.

This thesis investigates the developmental neurotoxicity of MPs and NPs in zebrafish (Danio rerio), emphasizing the influence of particle size and mixture toxicity. NPs were shown to cross the embryonic chorion, disrupt physiological functions, and induce anxiety-like behaviour, whereas MPs mainly altered gene expression related to neurodevelopment. When co-exposed with methylmercury (MeHg), NPs enhanced MeHg accumulation in the brain and sensory organs, exacerbating its neurotoxic effects. Notably, the mixture induced severe hypoactivity, impaired lipid metabolism and neurotransmission, and increased mortality.

These findings highlight the critical need to assess plastic particle toxicity not only in isolation but also in environmentally relevant mixtures. NPs, due to their small size and high reactivity, may act as vectors for toxicants like MeHg, amplifying their effects during sensitive developmental stages.

 

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