Fichas
Quorum sensing
Fichas del conjunto (24)
- 1What is bioluminscence?symbiosis with luminescent bacteria such as Vibrio fischerii and animals
- 2What animals have bioluminscence?Bobtail squid, flashlight fish, Dragon fish
- 3What are some other strange stories that show bioluminescence?-Sailors over the centuries have reported occasions where the sea glows
-Famously appears in Jules Verne's "20,000 leagues under the sea"
- 225 reported cases in the last 100 years
-In 2005 some interesting evidence was observed - 4How big was the bioluminescent milky sea from space?-Approx 15,400-km^2 area
-(as large as counties Limerick, Cork and Kerry combined)
-Total poluation is estimated at 4x10^22 cells = 40 billion trillion - 5How does V. fischeri emit light in culture?-Emits light when grown in flasks
-But only after they have grown in some time
-Light emission occurs late in growth, similar to production of secondary metabolites - 6What is the experiment to see if it is regulated by growth phase?Take supernatant (take spent medium) of culture 1 at end of growth
-Add it to culture 2 at start of growth
-Result: light emission early in growth not at the end of growth
Conclusion: There is something in the culture medium which induces luminscence - 7What is Homoserine lactones (HSL)?accumulate in the medium of luminescent bacteria, but not in certain non-luminescent mutants
- 8What is the proof of HSL?addition of chemically synthesized HSL induces light emission
- 9How does light get emitted?-Light emitting cells produce HSL at a continuous low level
-LuxR is a membrane bound sensor that binds HSL
-At higher cell densities HSL accumulates and activates LuxR
-LuxR activates transcription of the lux operon
Results: Very strong increase in HSL production (positive feedback) and luminescence
- 10What is Quorum?minimum number of cells need to be present
- 11What is quorum sensing?Allows cells to survey their environment for cells of their own species and to communicate with them
-Quorum sensing involves the sharing and detection of specific small molecules
-Once a sufficient concentration of the signaling molecule is present, specific gene expression is triggered
-Regulatory pathways of some prokaryotes regulated by cell density
-Quorum sensing is an example of a global regulatory system used by bacteria - 12What is the main important in quorum sensing?Expression of a group of genes is dependent on the cell density
-This makes sense when success is only going to be achieved when there are a sufficient number of bacteria
e.g. Invasion of a host (virulence) production of certain antibiotics bioluminescence
-Bacteria of different species can eavesdrop on each other by detecting different HSL - 13What is lactone lingo?
- 14What are the collective behaviours of quorum sensing?
- 15What are Cheater cells?Protease secretion can be used to allow bacteria to gain nutrients from some substrates
-can be under the control of QS
-some cells have been observed to not react to QS signal but still gain benefit - 16What do gram positive bacteria use to communicate?Oligopeptides
- 17What do gram negative bacteria use to communicate with each other?N-acyl homoserine lactone
- 18What is an example of an autoinducer-2?Tetrahydroxytetramethoxyform (THMF)- allows for interspecies crosstalk
- 19How does the spahylococcus aureus Autoinducing peptide work?Methicillin-resistant Staphylococcus aureus- biofilms makes it resistant = need a lot of bacteria to produce biofilm
- 20How does quorum sensing work in virulence?Pathogenic: Pseudomonas aeruginosa
-free growing in liquid culture
-cells reach a certain cell density a transformation occurs
-Multiple genes triggered to transform cells into a biofilm which is cells attached to a semisolid matrix (extracellular polymers to stick cells together)
-Increased pathogenicity and antibiotic resistance
- 21How does quorum sensing as a drug target?-Interspecies inhibition
-Inhibitor molecules designed to block signaling (analogous bind irreversibly)
-Potential to switch expression of virulence factors off (hormones that bind to HSL)
- 22How does quorum-sensing inhibitors blocks pseudomonas aeruginosa virulence?
- 23How does the bobtail squid use bioluminescence?-The bobtail squid is nocturnal, buries itself in the seabed during the day
-It uses Vibrio fischeri as for counter illumination at night
-Vibrio fischeri lives of nutrients provide by the squid
-Vibrio fischeri resides in crypts in a specialized light organ of the squid
-Both squid and bacterium display strong daily transcriptional rhythms (Circadian) and daily fluctuation in light emission
-The squid expels 95% of bacteria in the morning- reducing light emission
-Bacteria regrow during the day- back at full strength at night - 24What is the mechanism of quorum sensing in bobtail squid?-Cryptochromes regulates circadian rhythm
-Escry1 is located the squid's light organ
-Escry 1 Expression responds to
>Blue light not day light
>MAMPs (microbe-associated molecular pattern)
BOTH ARE REQUIRED FOR Escry1 CYCLING
Información
- Descripción
- University Microbiology Fichas sobre Quorum sensing, creado por Adrianna Bialecka el 11/02/2025.
- Creado por
- Adrianna Bialecka
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