Turing patterning with and without a global wave

Area of Science:

• Developmental Biology
• Morphogenesis
• Pattern Formation

Background:

• Periodic patterning is crucial for tissue development, seen in chicken feather formation.
• Feather germs initially form in a hexagonal array, propagating from the midline.
• In vitro studies suggested simultaneous germ formation, hinting at a missing global factor.

Purpose of the Study:

• To identify the global event responsible for the coordinated feather germ wave.
• To elucidate the molecular and mechanical mechanisms underlying feather patterning.

Main Methods:

• Investigated the role of Ectodysplasin A (EDA) and Fibroblast Growth Factor 20 (FGF20) in feather development.
• Utilized in vitro reconstitution and in vivo observations of chicken dorsal skin.
• Analyzed mechanochemical coupling between cell aggregates and signaling waves.

Main Results:

• A spreading Ectodysplasin A (EDA) wave was identified as the global event.
• Fibroblast Growth Factor 20 (FGF20)-cell aggregates mediate mechanochemical coupling.
• Absence of this global wave in flightless birds correlates with disrupted hexagonal patterning.

Conclusions:

• The global EDA wave, coupled with FGF20-mediated mechanochemistry, orchestrates periodic feather germ formation.
• This mechanism explains the difference between in vivo and in vitro feather patterning.
• Disruption of the global wave mechanism leads to irregular feather patterning, as seen in flightless birds.