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Tristan Ursell Bioengineering Department May 18, 2011

Tristan Ursell Bioengineering Department May 18, 2011. Ways that bacteria communicate. Chemical quorum sensing Mechanical quorum sensing Physical interactions (conjugation) Intercellular transport ( plasmodesmata in plant cells) ??. Plant cell-cell connections.

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Tristan Ursell Bioengineering Department May 18, 2011

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  1. Tristan Ursell Bioengineering Department May 18, 2011

  2. Ways that bacteria communicate • Chemical quorum sensing • Mechanical quorum sensing • Physical interactions (conjugation) • Intercellular transport (plasmodesmata in plant cells) • ??...

  3. Plant cell-cell connections Heinlein & Epel, Int Rev Cytology 2004

  4. A hint: transfer of GFP

  5. A hint: transfer of GFP

  6. A hint: transfer of GFP

  7. A hint: transfer of GFP

  8. Contrasting View

  9. Nanotubes!

  10. Dimensions 30 - 150nm x 0.5 mm

  11. Diffusion Estimate

  12. Diffusion Estimate 1 nM = 1 molecule / bacterial cell molecules / cell Diffusion may be much slower in the tubes (1/10th).

  13. Diffusion Estimate molecules / cell 10X faster?

  14. Immuno-EM shows GFP transport

  15. How is it no one saw this before? • Not looking hard enough? • Peculiarity of this strain of Bacillus subtilis? • People did see it, but chalked it up to something else? (pili?) Seems unlikely given the history of EM… No, other species involved in this study… Maybe… (DevakiBhaya, Carnegie Institute, Stanford)

  16. What are nanotubes good for?

  17. Confers resistance bacteriostatic bactericidal

  18. From what is a nanotube made?

  19. SDS Inhibits Resistance

  20. Networks and Connections

  21. How different from conjugation? • Size of pilus / nanotube: 8nm vs. >100nm • Reliance on specific genes (?) • Efficiency: 10-4 vs. 10-7 • 100 min for transfer of whole genome

  22. B. Subtilis – S. aureusnanotubes

  23. B. subtilis-E. coli nanotubes!

  24. What is the mechanism? Presumably … • … involves (OM), cell-wall, IM fusion • … which means that two cell walls can fuse • Is this osmotically driven? Are there specific proteins involved? Can growth provide the driving force?

  25. What is the topology? Huang et al, PNAS 2008

  26. What is the topology?

  27. What is the topology?

  28. Related to physiology of stalks? Caulobactercrescentus Hyphomonas neptunium

  29. Conclusions • A general mechanism for intercellular cytoplasmic transport • Conferred resistance implies that pathogenesis is a function of community • Mechanism for ‘natural competence’ in species such as B. subtilis? • Implications for synthetic biology and experiments • Can two different species directly transfer genetic information?

  30. What is the meaning of an individual species within a complex bacterial community that exchanges hereditary and non-hereditary information?

  31. Diffusion Estimate

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