Studies of the molecular and physiological mechanisms altered by exposure to microplastics during embryo development in Danio rerio

Details

Supervisors

Kestemont, Patrick ; Cornet, Valérie

Faculty

Faculté des sciences

Degree label

Master [120] en biologie des organismes et écologie, à finalité approfondie

Abstract

The current challenges facing our planet are increasingly highlighted by scientific research. Notably, plastic pollution, a clear indicator of human impact on the environment, is a growing concern. Between plastic degradation and the industrial production of microbeads, plastic particles are ubiquitous in the environment. The destination for most plastic particles is the oceans. However, most aquatic organisms are oviparous. This makes the development phase, which is crucial for organisms, even more sensitive to external contaminants. Even though the chorion is a protective barrier, it has pores for the exchange of gases, nutrients, and water. Therefore, some contaminants can pass through this chorion and reach the embryo directly. Our study focuses on the impact of plastic particles and their size, which potentially accentuates their harmfulness to developing organisms in egg. To answer this, we used the zebrafish embryo as a model because the transparency and its similarities of embryonic development with vertebrates, provide important interests. About plastic particles, the classification according to their size is difficult to establish and is still debated. But our study, to distinguish the impacts of MPs and NPs on the embryonic development of zebrafish Danio rerio, supports the fact that the distinction between MPs and NPs is important. Indeed, our results show that the chorion plays a protective role against MPs (5 μm) by preventing them from passing. However, NPs (250 nm) can interact directly with the embryo by passing through the pores of the chorion. Embryos exposed to NPs beads, appear to be hypoactive, have a higher rate of apoptosis in the eye and delayed hatching. Then, after hatching, NPs-exposed larvae show higher oxygen consumption and different stress response behavior than control larvae exposed to MPs. NPs also seem neurotoxic and to alter energy allocations, which could induce growth retardation in zebrafish embryos and alterations in environmental perception in the larvae. While embryos and larvae exposed to MPs, do not show significant difference with controls. But the expression of sod and cyp1a genes reveals that there are molecular effects induced by MPs and NPs.