YOLK CONSUMPTION: A NOVEL TARGET FOR MICROPLASTIC TOXICITY?

Microplastic represents a class of contaminants of emerging concern due to the numerous interferences exerted on biological processes1. Among these, developmental processes should be included2 and the effects of microplastic on zebrafish and sea urchins’ embryos are now well documented3. In particular,microplastics accumulate in the yolk4 but no much attention has been dedicated to the potential effects they exert on yolk degradation during early embryogenesis. For this reason, we carried out a preliminary investigation in an oviparous model, Artemia salina. Cysts were hatched and nauplii grew for 5 days in presenceof virgin and non-virgin polystyrene fragments (mixture, max diameter 10 μm) and, for control, in presence of polystyrene microbeads (3 μm; Sigma-Aldrich). Histological analyses confirm5 that in control cysts and in nauplii at stages L1 and L2 yolk platelets are very numerous. They reduce significantly in nauplii at stage L3 and disappear in nauplii at stage L4. After microplastic exposure, no matter the type, not only cysts and nauplii at stages L1 and L2, but also a significant percentage of nauplii at stages L3 and L4 contain a vast number of yolk platelets. These are occasionally located in the gut cells, but most often are dispersed in intracellular spaces. Persisting platelets have a different glycan composition as indicated by staining with a panel of lectins (WGA, DBA, and PNA). Though preliminary, results open up an interesting new field of research. Microplastic, in fact, represents worldwide a serious emerging environmental threat to health being a proven vehicle for contaminants6. Our evidence suggests a much more direct impact onwater organisms and recruitment mechanisms.