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Assignment 1.1.2
Self-organized
Without any preconceived construct, independent entities interact with each other and spontaneously develop patterns, orders, and predictable behaviors.
Quorum Sensing
Quorum sensing is based on the idea of Microbial Intelligence where single cells show cooperative or adaptive behaviors in populations of like and unlike cells. It communicates with the surrounding cells through chemical signaling that induces physiological or behavioral change and in turn influences the colony structure. (could be understood as chemical brainwash)
In quorum sensing, all bacteria can talk to each other. They make chemical words, recognize those words, and turn on group behaviors that are only successful when all of the cells participate in unison. It controls the gene expression and influences the cell population density. A most relevant example is the virulent.
How is virulence so harmful?
What makes the virulence so harmful is the collective action among many cells. Bacterias enter the body, they stay dormant and start growing with the little molecules. They recognize when they have reached the right number and all of the bacteria launch their virulence attack together and thus overcome a large host.
Pseudomonas aeruginosa.
This is a bacteria that kills people who have cystic fibrosis. Kills immune compromised people and causes infection when you get a stent or breathing tube.
Quorum sensing is the major contributor of this virus. As Pseudomonas grows, it make and releases small molecules (red triangles), the molecules then increase in proportion to cell number. When the bacteria detect the presence of those molecules, as a collective, all the bacteria forms a biofilm that sit on surfaces and attached to tissue. They they group together to secrete the toxins that make us sick.
There are many receptors and signal cells. Two receptors LasR and RhIR,recognize the AHL signals. They each recognize different versions of the signal and respond to it.
Many cells are shared among the population of molecules and works in a cooperative behavior.
Within this cooperative relationship, an example byproduct is lasB(protease elastase) which is produced when the virus strain grow on medium containing casein as the only energy source. Elastase is produced to break down casein into components for the virus to use for carbon and energy.
Placed Pseudomonas in the petri plate. The bacteria has spread out collectively to the edges - Biofilm Formation (which is what happens to the tissues)
Social cheaters(in a cooperative population): they themselves do not product elastase to break down casin, so they extract the by-products from other cooperating bacteria.
The medical field has attempted to counter this virus by changing the molecular structure of the signal molecule and turning it into an inhibitor that prevents the action of quorum sensing.
The quorum sensing allows molecules to establish an autonomous order through the mechanism of chemical signaling. Providing a strange retrospect on the formation of social order through logical chemical interactions and the basic molecular makeup.
References
Quorum sensing - Wikipedia
Quorum sensing: Bacteria talks | Bonnie Bassler - Bing video
Modulation of Pseudomonas aeruginosa Quorum Sensing by Glutathione | Journal of Bacteriology (asm.org)
How do sea stars move without a brain? The answer could impact robotics and more (phys.org)
Locomotion in Star Fish | Invertebrates (notesonzoology.com)
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