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Synthesis of a reaction-diffusion French flag pattern
A central question of morphogenesis is the unfolding of genetic information into successive steps of complexification of an initially relatively simple egg or a bud. Experiments show that very often cellular differentiation is preceded by formation of a chemical cue, a morphogen pre-pattern. For example, during the development of the Drosophila blastoderm a simple initial morphogen gradient is interpreted to create three regions of space with different chemical compositions. This particular pre-patterning process was called a French Flag formation. I will first discuss theoretical considerations that provide heuristics for an experimental realization of this process. Then I will present our recent work on artificial morphogenesis. Using these heuristics and DNA synthetic biology we have generated an experimental system capable of separating the reaction volume into two or three chemically distinct parts in response to an initial smooth gradient of a morphogen. To mimic a real morphogenetic act where a transient chemical pre-patterning is followed by a permanent change on the tissue level, we coupled the chemical output of our French flag system to an aggregation of microbeads, creating thus a prototype of a morphogenetic material.