Emerging marine pollutants: metal nanoparticles and sea urchin coelomocytes immune response.

Harmful effects of metal nanoparticles (NPs) on marine organisms is becoming a hot topic and a major environmental concern, as sea water superficial sediments represent the ultimate sink for these emerging contaminants. Experiments showing the possible impact of NPs were carried out by the use of the sea urchin, Paracentrotus lividus, as a 3Rs-compatible model. NPs were found inside coelomocytes, the immune cells of the sea urchin, after their forced ingestion, indicating their ability to cross the endotelial intestine barrier, and confirming the macrophage-like activity of coelomocytes. NPs were phagocytosized and accumulated inside the cells, as demonstrated by Field Emission Gun-Environmental Scanning Electron Microscope (FEG-ESEM) coupled with Energy Dispersive X-Ray Spectroscopy (EDS) and staining of the intracellular membranes (ER) by the DiOC6 fluorochrome observed with confocal microscopy. Functional expression of stress biomarkers, analyzed by biochemical measurements, immuno-cytochemistry and immuno-blotting, demonstrated appreciable significantly correlated alterations, according to the different NP tested.