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Quorum Sensing and Biofilms

Quorum Sensing and Biofilms. Quorum Sensing Basics . Bacteria constantly release signal molecules If cell density is not big enough  nothing happens Threshold density all bacteria simultaneously carry out gene expression “Quorum Sensing” from counting as to take a vote before acting .

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Quorum Sensing and Biofilms

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  1. Quorum Sensing and Biofilms

  2. Quorum Sensing Basics • Bacteria constantly release signal molecules • If cell density is not big enough  nothing happens • Threshold density all bacteria simultaneously carry out gene expression • “Quorum Sensing” from counting as to take a vote before acting

  3. Gram Negative Bacteria • Acylhomoserine lactones (AHL molecules) • Easy transport of molecules outside of cells

  4. Gram Positive Bacteria • Precursor Oligopeptides • Must be exported via active transport proteins

  5. Inter Species Communication • Al-2 molecule is universal • Produced by LuxS enzyme from dihydroxypentanedione substrate

  6. Biofilms • Microorganisms form layer with proteins, DNA and long chain sugars • Often pathogenic • Concern for health and food industry • Spoiled food • Biofilms in cystis fibrosis • Quorum sensing plays big role in the high cell density communication and virulence

  7. Biofilms Today • Scientists are investigating varied bio-film formations and mutations that could help decrease formation • Looking at mutant luxS enzymes and other quorum sensing systems • Disrupt quorum sensingdisruptbiofilm formation and virulence

  8. Ep-CAM Gene Silencing in Craniopharyngiomas

  9. Background • Benign epithelial brain tumor common in children • Cannot spread but presses on vital structures • Can cause stunted growth, obesity, diabetes insipidus, and other morbidity • Hard to remove due to strong adherence to important structures • Often reoccurs

  10. Ep-CAM Glycoprotein • Ep-CAM gene expression is highly over expressed • Produces Ep-CAM glycoprotein adhesion molecule • Is linked to tumor genesis and metastasis • Makes tumor strongly adherent

  11. Craniopharyngioma

  12. Competing Technologies • Radiotherapy • Kills healthy cells • High risk of second cancer in children and adolescents

  13. Design • Silencing Ep-CAM gene by inhibiting transcription through methylation of the promoter region

  14. Inducing Bacteria Ep-CAM glycoprotein Receptor AerotolerantE.Coli bacteria engineered to produce invasin protein and produce m5c DNA methyltransferase enzymes on signal Calcification material Receptor

  15. Invasin and m5c Production Bacteria Produces m5c methyltransferase enzymes Invasin proteins

  16. Invading Tumor Cells B-1 Integrin receptor Invasin Proteins Tumor cell

  17. Inside Cell Ep-CAM promoter M5c DNA methyltrasnferase enzymes

  18. Inhibition of RNA Polymerase Binding RNA Polymerase Ep-CAM Transcription

  19. AND Gate Truth Table

  20. Inverter Logic Gate Truth Table

  21. Advantages • No damage to healthy cells • Easy to administer • No radioactive material • Helps surgeons remove tumor • Decrease reoccurrence

  22. Possible Problems • Ep-CAM promoter region specific methylation • Laboratory precaution while working with cells with invasin • Precautions to keep bacteria from evolving and reproducing out of control

  23. Testing • Testing on tissue culture and many other steps before reaching human testing • Similar system could be tweaked and developed for other cancers

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