The tolerance to hypoxia is defined by a time-sensitive response of the gene regulatory network in sea urchin embryos

Abstract

Deoxygenation, the reduction of oxygen level in the oceans induced by global warming and anthropogenic disturbances, is a major threat to marine life. This change in oxygen level could be especially harmful to marine embryos that utilize endogenous hypoxia and redox gradients as morphogens during normal development. Here we show that the tolerance to hypoxic conditions changes between different developmental stages of the sea urchin embryo, possibly due to the structure of the gene regulatory networks (GRNs). We demonstrate that during normal development, bone morphogenetic protein (BMP) pathway restricts the activity of the vascular endothelial growth factor (VEGF) pathway to two lateral domains and by that controls proper skeletal patterning. Hypoxia applied during early development strongly perturbs the activity of Nodal and BMP pathways that affect VEGF pathway, dorsal-ventral (DV) and skeletogenic patterning. These pathways are largely unaffected by hypoxia applied after DV-axis formation. We propose that the use of redox and hypoxia as morphogens makes the sea urchin embryo highly sensitive to environmental hypoxia during early development, but the GRN structure provides higher tolerance to hypoxia at later stages.

The Evolution of Biomineralization through the Co-Option of Organic Scaffold Forming Networks

“…The GRN that drives skeletogenesis in the sea urchin embryos was extensively studied in the last two decades, resulting in one of the most comprehensive models of developmental GRN [ 15 , 40 , 59 , 60 , 61 , 62 , 63 ]. The GRN contains about 20 transcription factors that control a sequence of morphogenetic processes, including epithelial to mesenchymal transition, cell migration and cell fusion [ 15 , 40 , 64 , 65 ].…”