Integument pattern formation involves genetic and epigenetic controls operated at different levels: feather arrays simulated by a Digital Hormone Model

T.-X. Jiang, R. Wideltz, Wei-Min Shen, Peter Will, D. Wu, C. Lin, J. Jung, and C. Chuong. Integument pattern formation involves genetic and epigenetic controls operated at different levels: feather arrays simulated by a Digital Hormone Model. Int. J. Dev. Biol., 48:117–135, 2004.

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Abstract

Pattern formation is a fundamental morphogenetic process. Models based on genetic and epigenetic control have been proposed but remain controversial. Here we use feather morphogenesis for further evaluation. Adhesion molecules and/or signaling molecules were first expressed homogenously in feather tracts (restrictive mode, appear earlier) or directly in bud or inter-bud regions (de novo mode, appear later). They either activate or inhibit bud formation, but paradoxically co-localize in the bud. Using feather bud reconstitution, we showed that completely dissociated cells can reform periodic patterns without reference to previous positional codes. The patterning process has the characteristics of being self-organizing, dynamic and plastic. The final pattern is an equilibrium state reached by competition, and the number and size of buds can be altered based on cell number and activator/inhibitor ratio, respectively. We developed a Digital Hormone Model which consists of (1) competent cells without identity that move randomly in a space, (2) extracellular signaling hormones which diffuse by a reaction-diffusion mechanism and activate or inhibit cell adhesion, and (3) cells which respond with topological stochastic actions manifested as changes in cell adhesion. Based on probability, the results are cell clusters arranged in dots or stripes. Thus genetic control provides combinational molecular information which defines the properties of the cells but not the final pattern. Epigenetic control governs interactions among cells and their environment based on physical-chemical rules (such as those described in the Digital Hormone Model). Complex integument patterning is the sum of these two components of control and that is why integument patterns are usually similar but non-identical. These principles may be shared by other pattern formation processes such as barb ridge formation, fingerprints, pigmentation patterning, etc. The Digital Hormone Model can also be applied to swarming robot navigation, reaching intelligent automata and representing a self-re-configurable type of control rather than a follow-the-instruction type of control.

BibTeX Entry

@Article{	  jiang2004integument-pattern-formation-involves,
  abstract	= {Pattern formation is a fundamental morphogenetic process.
		  Models based on genetic and epigenetic control have been
		  proposed but remain controversial. Here we use feather
		  morphogenesis for further evaluation. Adhesion molecules
		  and/or signaling molecules were first expressed
		  homogenously in feather tracts (restrictive mode, appear
		  earlier) or directly in bud or inter-bud regions (de novo
		  mode, appear later). They either activate or inhibit bud
		  formation, but paradoxically co-localize in the bud. Using
		  feather bud reconstitution, we showed that completely
		  dissociated cells can reform periodic patterns without
		  reference to previous positional codes. The patterning
		  process has the characteristics of being self-organizing,
		  dynamic and plastic. The final pattern is an equilibrium
		  state reached by competition, and the number and size of
		  buds can be altered based on cell number and
		  activator/inhibitor ratio, respectively. We developed a
		  Digital Hormone Model which consists of (1) competent cells
		  without identity that move randomly in a space, (2)
		  extracellular signaling hormones which diffuse by a
		  reaction-diffusion mechanism and activate or inhibit cell
		  adhesion, and (3) cells which respond with topological
		  stochastic actions manifested as changes in cell adhesion.
		  Based on probability, the results are cell clusters
		  arranged in dots or stripes. Thus genetic control provides
		  combinational molecular information which defines the
		  properties of the cells but not the final pattern.
		  Epigenetic control governs interactions among cells and
		  their environment based on physical-chemical rules (such as
		  those described in the Digital Hormone Model). Complex
		  integument patterning is the sum of these two components of
		  control and that is why integument patterns are usually
		  similar but non-identical. These principles may be shared
		  by other pattern formation processes such as barb ridge
		  formation, fingerprints, pigmentation patterning, etc. The
		  Digital Hormone Model can also be applied to swarming robot
		  navigation, reaching intelligent automata and representing
		  a self-re-configurable type of control rather than a
		  follow-the-instruction type of control. },
  author	= {T.-X. Jiang and R. Wideltz and Wei-Min Shen and Peter Will
		  and D. Wu and C. Lin and J. Jung and C. Chuong},
  journal	= {Int.\ J.\ Dev.\ Biol.},
  pages		= {117--135},
  title		= {Integument pattern formation involves genetic and
		  epigenetic controls operated at different levels: feather
		  arrays simulated by a Digital Hormone Model},
  volume	= {48},
  year		= {2004}
}