Autophagy is required for sea urchin oogenesis and early development

Autophagy is a major intracellular pathway for the degradation and recycling of cytosolic components.Emerging evidence has demonstrated its crucial role during the embryo development of invertebratesand vertebrates. We recently demonstrated a massive activation of autophagy in Paracentrotus lividusembryos under cadmium stress conditions, and the existence of a temporal relationship betweeninduced autophagy and apoptosis. Although there have been numerous studies on the role of autophagyin the development of different organisms, information on the autophagic process during oogenesis orat the start of development in marine invertebrates is very limited. Here we report our recent data onthe occurrence of autophagy at these key phases of development. In order to investigate autophagytrends we performed in vivo assays to detect autophagolysomes, as well as in situ analysis with anti-LC3antibody to detect autophagosomes before the fusion with lysosomes. From data generated throughconfocal laser scanning microscopy and quantification of autophagic signals we have drawn severalunequivocal conclusions. The results showed a copious and rising number of autophagic organelles thathad specific localization. Interestingly the increase in autophagy that occurred just after fertilizationhas been proved to be crucial for correct initiation of the developmental programme: irreversibledevelopmental delays and morphologic anomalies were induced by short autophagic inhibition. Thiswork focused on the sea urchin model system and corroborates evidence on the need for self-digestionduring development, enriching the knowledge on autophagy, a biological mechanism belonging toevolutionarily different organisms.