Fine-grained pattern formation in the eye and inner ear of chick embryos
Pau Formosa-Jordan, Dept. Structure and Constituents of Matter, University of Barcelona

During embryonic development, cells initially equivalent become distinct, differentiating into various kinds of cells in an orderly manner and creating spatial patterns. In the cases I will explore in this talk, patterning arises from the direct interaction between adjacent cells. This interaction occurs through the binding of two different proteins belonging to the Notch signaling pathway, the Notch receptor and its ligand, each anchored in the cell membrane of adjacent cells. It is well known that this cell-to-cell interaction enables the creation of a positive intercellular feedback that drives fine-grained patterning of two different cell types. Neural differentiation in the embryonic chick retina is a paradigmatic example of fine-grained pattern formation mediated by the Notch signaling pathway. In this case, a pattern of neural and non-neural cells emerges first in the center of this tissue and spreads out defining a differentiation wavefront. Our experimental data shows that there is Notch-independent ligand expression ahead of the wavefront. Through mathematical modeling we predict that this ligand expression has crucial implications for the pattern formed, shape and velocity of the differentiation wavefront. In this talk, I will also present our recent theoretical results on the fine-grained pattern of sensory cells in the chick inner ear. This pattern emerges thanks to two distinct intercellular Notch-mediated feedback loops that operate sequentially in the tissue. Based on new experimental data, I will show our predictions on how these feedback loops are orchestrated.

[1] Pau Formosa-Jordan, Marta Ibanes, Saul Ares, and Jose Maria Frade (2012) Regulation of neuronal differentiation at the neurogenic wavefront. Development, 139, 2321-2329.
[2] Pau Formosa-Jordan, Marta Ibanes, Saul Ares, and Jose Maria Frade (2013) Lateral inhibition and neurogenesis: novel aspects in motion. International Journal of Developmental Biology, 57:341-350. [3] Jelena Petrovic*, Pau Formosa-Jordan*, Juan Camilo Luna, Marta Ibanes, Joana Neves and Fernando Giraldez. Lateral induction and lateral inhibition depend on Notch signal strength in the developing inner ear (Manuscript under revision in Development)

* Equal contributors

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