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Two dimensional pattern formation

Two dimensional pattern formation. A synthetic multicellular system for programmed pattern formation (Nature 2005, 434:1130-1134). Jingyao Guo. Pattern formation. A hallmark of coordinated cell behaviour in both single and multicellular organisms.

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Two dimensional pattern formation

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  1. Two dimensional pattern formation A synthetic multicellular system forprogrammed pattern formation (Nature 2005, 434:1130-1134) Jingyao Guo

  2. Pattern formation • A hallmark of coordinated cell behaviour in both single and multicellular organisms. • Typically involves cell–cell communication and intracellular signal processing.

  3. The ring-like patterns formed by receiver cells based on the chemical gradients of an acyl-homoserine lactone (AHL) signal.

  4. Principle The band-detect multicellular system programs E. colireceiver cells to fluoresceonly at intermediate distances from sender cells.

  5. Inside receiver cells

  6. HD3 mutation HD1 mutation Plasmids • b: Plasmid map for senders. • c, d: The high-detect (c) and low-detect (d)plasmids that implement the band-detect operation. • The high-detect component determines the AHL threshold above which GFP expression is muted. • The low-detect component determines the lowest concentration of AHL that elicits GFP response.

  7. Experiments Simulated and experimental liquid-phase behaviour of high-detect and band-detect networks. The liquid-phase dosage responses of three HD strains showed inverse correlations to AHL concentrations with different sensitivities. hypersensitive LuxR (HD1) wild-type LuxR (HD2) reduced-copy-number plasmid (HD3) BD1 BD2 BD3

  8. Experiments Bullseyepattern as captured with a fluorescence microscope after incubation overnightwith senders in the middle of an initially undifferentiated ‘lawn’ of BD2-Red and BD3 cells (b) / BD1 and BD2-Red cells(c).

  9. The ring formation activity of BD2 cells over thecourseof 36 h. Experiments • No fluorescence for the first 15 h. • Low levels of fluorescence emerged about 10 mm from the senders. • Fluorescence values then increased significantly between 5 and 18 mm from the senders. • Fluorescence values stabilized after about 32 h, reaching a steady-state maximum at 10 mm. • No observable shift in the position of high fluorescence over the duration of the experiment.

  10. Twosimulations of the band-detect network with two different sets ofkinetic rates. Experiments • Both show position shift. • The rate constant for LacI decay has the strongest correlation with fluorescence response timesand positional shift. • The stability of LacI affects how closely GFP expression in thereceivers reports on the establishment of the AHL gradient from thesenders. • Before GFP expression can begin, AHL has to activate theproduction of CI, and LacI levels must subsequently decline.

  11. Experiments Form more elaborate patterns by placing multiple sender disks in different configurations.

  12. Significances • Naturally occurring developmental processes; • Tissue engineering; • Biomaterial fabrication; • Biosensing.

  13. Thanks.

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