Autophagy during development of sea urchin embryos

Autophagy is a highly regulated mechanism that enhances cell eukaryotic survival under various environmental and cellular stresses, by breakdown and recycling of macromolecules and organelles. Here we report that in Paracentrotus lividus embryos autophagic process occur, at a lesser extend during physiological development and at greater levels after a cadmium treatment. By Acridine Orange staining, we found that embryonic cells exposed to cadmium display green fluorescence in cytoplasm and nucleus, and show considerable red fluorescent dots in cytoplasm. This evidence suggests formation of acidic auto-phagolysosomal vacuoles. By Neutral Red vital staining, specific for lysosomes and cellular acid compartments, we obtained analogous results. These data have been sustained by anti-LC3 antibody detection (specific marker of autophagy). By Western blot we found a peak of physiological autophagy at late gastrula stage, while in treated embryos autophagy seem to anticipate massive apoptosis, probably for providing the energy for the removal of apoptotic cells or, alternately, as a less deleterious defence strategy for the safeguard of development program