Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.08.09.242933v1?rss=1 Authors: Layous, M., Khalaily, L., Gildor, T., Ben-Tabou de-Leon, S. Abstract: Deoxygenation, the reduction of oxygen level in the oceans induced by global warming and anthropogenic disturbances, is a major threat to marine life. Acute diurnal changes in oxygen levels could be especially harmful to vertebrate and sea urchin embryos that utilize endogenous hypoxia gradients to drive morphogenetic events during normal development. Here we show that the tolerance to hypoxic conditions changes between different developmental stages of the sea urchin embryo, due to the structure of the gene regulatory network (GRN). Specifically, Nodal signaling, bone morphogenetic protein (BMP) and the vascular endothelial growth factor (VEGF) pathways, are strongly disturbed by hypoxia during early embryogenesis, but are largely unaffected by hypoxia applied after dorsal-ventral axis formation. These pathways regulate hypoxia-induced vascularization in vertebrates which could suggest that they are a part of an evolutionary conserved program that uses hypoxia to drive morphogenesis. We propose that the structure of the GRN, that includes positive and negative feedback and feedforward loops, increases its resilience to changes of the initial hypoxia gradients and could help the embryos tolerate transient hypoxic conditions. Copy rights belong to original authors. Visit the link for more info