Eventos

Speaker: Dr. Aida Rodríguez-Nuevo

Senior Postdoctoral Researcher, Oocyte Biology & Cellular Dormancy Group, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST).

Abstract

The conservation of the germline becomes essential when zooming out from cell biology into species fitness. Oocytes, the female germ cells that become eggs, form before birth and remain viable for several decades before fertilization. Yet, little is known about the mechanisms employed by oocytes to deliver a pristine cytoplasm to the next generation, after decades of being formed. We discovered that oocytes evade the production of reactive oxygen species by remodelling the mitochondrial electron transport chain through elimination of complex I. Combining live-cell imaging and proteomics in human and Xenopus oocytes, we find that early oocytes exhibit greatly reduced levels of complex I. This is accompanied by a highly active mitochondrial unfolded protein response, which is indicative of an imbalanced electron transport chain. Biochemical and functional assays confirm that complex I is neither assembled nor active in early oocytes. Thus, we report a physiological cell type without complex I in animals. Complex I suppression represents an evolutionarily conserved strategy that allows longevity while maintaining biological activity in long-lived oocytes.