pizza club - october 2016 - eugen
TRANSCRIPT
Can Microbial Communities be understood as Multicellular Organisms and vice versa?
Pizza Club – Eugen Bauer
Chondromyces crocatus
Anabaena
Escherichia coli
Bacteria as Multicellular Organisms, James Shapiro, Scientific American, 1988
Motivation
• Multicellular eukaryotes have been compared with each other, but not with bacteria• Is it worthwhile to do this comparison, if not then why?
• What is the basic mechanism of differentiation?
• Use same methods to study microbial communities as well as multicellular systems• In particular computational methods
Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote
Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote
Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote
Cell Differentiation (in C.elegans)
Developmental Biology 6th edition, Gilbert, 2000
Two modes of differentiation:
1. Asymmetric cell division• Cell polarity• Internal concentration• Structural differences
2. Induction by other cells• Diffusion via gradients• Cell to cell contact• Gap-junctions
Spatial and temporal transcription in development
Hoescht dye P-granules
Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote
Cell Differentiation (in B.subtilis)
Liu et al, Nature, 2015
• Glutamine is needed to grow (biomass)
• Glutamate + Ammonium Glutamine
• Ammonium can be produced under limiting conditions
Trade off between competition and cooperation Spatial and temporal nutrient gradients lead to differentiation
Multicellularity Comparison
Prokaryotes / Biofilms
• Extrinsic signals
• Spatio-temporal nutrient gradients
• Reversible differentiation (all cells are the same)
• Differentiation through metabolism
• Quorum sensing / metabolic exchange
• Darwinistic processes
• Egoistic cell interest
Eukaryotes / Tissues
• In- and extrinsic signals
• Spatio-temporal transcription factors
• Re- and Irreversible differentiation
• Differentiation through epigenetics
• Cell to cell interactions / diffusion
• Cellular Darwinism
• Cellular determination
Modeling Tissues & CommunitiesDependent
Autonomous
Mixed bag “Superorganism” model
Free exchange of compoundsCommon objective
Egoistic objective, free exchange
No transparency / interactions
Biofilms
Tissues
Discussion
• Development of microbial communities and eukaryotic multicellularity has some common patterns (e.g. spatial-temporal gradients)
• Differentiated microbes are more autonomous than differentiated (determined) cells
• Darwinistic processes govern microbial communities
• Different modeling approaches to represent cellular dependencies
• Further reading: Cellular Darwinism