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The Response of Bacterial Growth and Division to Osmotic Shock PowerPoint Presentation
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The Response of Bacterial Growth and Division to Osmotic Shock

The Response of Bacterial Growth and Division to Osmotic Shock

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The Response of Bacterial Growth and Division to Osmotic Shock

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  1. The Response of Bacterial Growthand Division to Osmotic Shock Rico Rojas Huang and TheriotLabs Simbios Center for Biomedical Computation Stanford Biophysics Seminar

  2. How do bacterial cells grow and divide: What are the mechanical forces that drive these processes? How do bacterial cells grow and divide: What are the mechanical forces that drive these processes? How are these forces controlled by chemistry? How do bacterial cells grow and divide: What are the mechanical forces that drive these processes?

  3. Bacteria cells are enclosed by a cell wall, a cross-linked polymer network. How do you controllably ‘grow’ and divide a polymer network?

  4. The cell wall bears considerable load due to high internal osmotic pressure. Gram negatives: P1 atm (h3nm) Gram positives: P10 atm (h30nm) E. coli, wall stained with WGA Does cell wall expansion, and therefore cell growth, depend on osmotic pressure?

  5. Measuring the response of E. coli to oscillatory osmotic shock

  6. Dissecting this data reveals a simple mechanism of wall synthesis.

  7. Model: in E. coli synthesis is rate limiting, but osmotic pressure is required.

  8. Bacillus subtilis exhibits a more drastic response to osmotic shock.

  9. The growth rate of B. subtilisrings in response to downshock.

  10. The existence of ringing predicts that we should be able to drive resonance.

  11. Potential Feedback Mechanisms Pressure Model: osmotic shock triggers nonlinear feedback in osmoregulation. Synthesis Model: osmotic shock results in an imbalance of wall precursors.

  12. Ringing depends on the availability of wall precursors.

  13. Staphylococcus aureusdivision.

  14. Lytic enzymes are distributed around the division plane. Yamada et al., 1996

  15. S. aureusdivides extremely fast. Thanks to Tim Lee

  16. Measuring the response ofS. aureusto oscillatory osmotic shock

  17. Osmotic pressure drives S. aureus division.

  18. Conclusions/Working Models: B. subtilis E. coli S. aureus

  19. Thank You!