Morphogenesis cell-based modelling in developmental biology Walter - - PowerPoint PPT Presentation

Morphogenesis

cell-based modelling in developmental biology

Walter de Back

Collegium Budapest Institute for Advanced Study

Animal Coat Pattern's, Turing's Patterns Morphogenesis, Cellular Potts model Dictyostelium d., Evolution of morphogenesis

Patterns

Turing Patterns

Alan Turing, 1950

Turing Patterns

Murray 1981

Varying parameters such as relative diffusion, domain size and shape, many patterns are possible

Patterns

Turing: The stripes are easy, but what about the horse part?

From Genes to Organisms Via the Cell

• Neo-Darwinism:

– Genetic reductionism, esp. in the era of genomics – Organisms cannot be reduced to their genes

• Need for a theory of morphogenesis

– Development: genotype-phenotype mapping – How does it influence evolution?

• Inter-cellular vs. Intra-cellular mechanisms

– Cell-based modelling

Cell sorting through diff. adhesion

Glazier, Graner, 1991

• Cell migrate and sort

themselves based on different intercellular adhesion properties

• Cell-oriented models

– Cells are point-like entities – Cells are spherical – Cells are flexible deformable entities that try to optimize shape

Cellular Potts model

aka Glazier-Graner-Hogeweg model

• Two-scale cellular automata model
• Biological cell consist of many lattice sites with same ’state’

– Properties: type, volume, growth constant, etc.

• Between cells:

– Free energy bond Jij where i and j are the types of the cells – Sites changes state as to minimize free energy

• Dd morphodynamics:
• Aggregation
• Stream formation
• Slug formation
• Slug phototaxis
• Fruiting body culmination
• Minimizing the role of gene regulation, instead:
• cell signalling
• cell adhesive movements

Dictyostelium

Evolution of morphologenesis

Hogeweg, 2005

• Putting it back together

– Within cell dynamics (gene regulation) – Between cell dynamics (adhesion, signalling) – Evolutionary dynamics (fitness differentiation)