Title: Control of Segmentation Timing in the Zebrafish Notochord

Abstract: Many developmental processes require coordination across multiple cells to achieve a common function. One way to achieve this harmony is through control
of developmental timing, regulated by genetic species acting as biological timekeepers. In this talk, I will discuss evidence of an oscillatory system in the zebrafish notochord’s outermost epithelial sheath layer. This oscillator, reported by an ERK sensor, demonstrates a periodicity of roughly 10 hours with cells attaining synchronous states across several hundred microns along the notochord length. Interestingly, this periodicity is similar to the time interval between appearance of new domains of Notch expression, a process recently characterized as a segmentation program. This program lays down segments at regular time intervals along the head to tail axis of the notochord. We have found that ERK activity transitions to an oscillatory state around 4.5 days post fertilization and that blocking oscillator activity blocks segment addition to the notochord. Our ongoing work is aimed at decoding molecular players that could build this oscillator system.

Host: Julio Monti Belmonte