In the sea urchin embryo, the micromeres act as a vegetal signaling center. These cells have been shown to induce endoderm; however, their role in mesoderm development has been less clear. We demonstrate that the micromeres play an important role in the induction of secondary mesenchyme cells (SMCs), possibly by activating the Notch signaling pathway. After removing the micromeres, we observed a significant delay in the formation of all mesodermal cell types examined. In addition, there was a marked reduction in the numbers of pigment cells, blastocoelar cells and cells expressing the SMC1 antigen, a marker for prospective SMCs. The development of skeletogenic cells and muscle cells, however, was not severely affected. Transplantation of micromeres to animal cells resulted in the induction of SMC1-positive cells, pigment cells, blastocoelar cells and muscle cells. The numbers of these cell types were less than those found in sham transplantation control embryos, suggesting that animal cells are less responsive to the micromere-derived signal than vegetal cells. Previous studies have demonstrated a role for Notch signaling in the development of SMCs. We show that the micromere-derived signal is necessary for the downregulation of the Notch protein, which is correlated with its activation, in prospective SMCs. We propose that the micromeres induce adjacent cells to form SMCs, possibly by presenting a ligand for the Notch receptor.
Development/DMM Virtual Meeting 2021
Development presents...
The people behind the papers – Adrian Danescu, Lisanne Rens and Joy Richman
A new paper in Development combines high-resolution live imaging and mathematical modelling to understand the dynamics of facial symmetry. In an interview, first authors Adrian Danescu and Lisanne Rens, and the corresponding author Joy Richman, tell us more.
Special issue: call for papers
The Immune System in Development and Regeneration
Guest editors: Florent Ginhoux and Paul Martin
Submission deadline: 1 September 2021
Publication: Spring 2022
Read & Publish agreement with EIFL
We are pleased to announce that researchers in 30 developing and transition economy countries can benefit from immediate and fee-free Open Access publishing in Development following a new agreement with Electronic Information for Libraries (EIFL).
We now have over 200 institutions in more than 20 countries and six library consortia participating in our read & Publish initiative. Find out more and view the full list of participating institutions.
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