Does a morphogen gradient slow the segmentation clock? A live fluorescent reporter based biophysical investigation

• Applicant: Dr. Andrew Oates
• Subject Area: Developmental Biology
• Term: from 2010 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 175758032

The segmented architecture of the vertebrate body arises during embryogenesis by the rhythmic and sequential formation of cell blocks called somites from the presomitic mesoderm (PSM). This rhythm comes from an oscillatory genetic network in the cells of the PSM termed the segmentation clock. In order to form somites, the cells of the PSM must stop oscillating as they exit the PSM and differentiate. Gradients of Wnt and Fgf signaling extending across the PSM are thought to regulate this exit wavefront, but how this happens is not understood. In particular, it is not known whether the cells suddenly arrest their oscillations at the wavefront, or whether they slow their oscillations gradually, forming a frequency profile across the PSM. Furthermore, the relationship between the frequency profile and the signaling gradients has never been examined. One hypothesis is that the frequency of the slowing cells is directly controlled by the local concentration along these signaling gradients. Most of what is known about this tissue-level, rhythmic pattern generating system is inferred from static snapshots of gene expression patterns, but the questions raised here need to be answered using live dynamic imaging techniques. This proposal seeks to test these frequency profile 1 hypotheses in live zebrafish embryos using timelapse imaging and quantitative analysis of fluorescent reporters of both the signaling gradients and the segmentation clock oscillations.

• DFG Programme: Research Grants