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Mini Project #2: Micro and Macro Communication: Unification in Purpose

Susan Dorfman's picture

Mini Project #2:

Micro and Macro Communication: Unification in Purpose

As we sit around the table sharing experiences and concerns as educators, we have moved forward in a progression to achieve co-constructive dialogue. As in previous Summer Institutes, Paul models and guides us in the process. So, now I am thinking about how I will try to do the same type of facilitation in my classes even more successfully than before. When the July/August issue of Smithsonian magazine arrived by snail mail, I noticed an article written by Natalie Angier, my favorite science writer. Her narrative is clear, engaging, and well researched. She is a gifted communicator who wrote an article about the work of a researcher who appreciates more than most the power of communication.

Bonnie Bassler studies “quorum sensing” or how “microbes communicate with each other” and the importance of that communication in the “building of the vast interlocking infrastructure of life” necessary for macrobes such as humans.  The chemical language of bacterial communication is complex enough to inform bacteria about the other bacterial species in their environment as well as size of the population. When a critical mass of bacterial cells accumulate, the bacteria band together to perform surprisingly large tasks like decomposing a large mammal or causing dental decay. The coordination required is achieved through a specific chemical language that is species specific as well as another that is general and understood by other species of bacteria. From a public health point of view, this new story could offer the alternative mechanism of interrupting bacterial communication to diminish bacterial virulence when current antibiotics fail.

The example given in the article is that of cystic fibrosis, a lethal condition that is genetically based and congenital. In this disease, cell membranes do not transport chloride ions normally. The chloride concentration becomes abnormally high outside the cell and results in the accumulation of excessive mucus in the pancreas, lungs, digestive tract, and other organs. The effects are many but one is chronic bronchitis. Research suggests that the excessive chloride inhibits a naturally occurring antibiotic made by some body cells. Colonies of pseudomonas bacteria persists in the respiratory system. These colonies become virulent when the bacteria release quorum-sensing molecules that start the colonies operating as a group.  Children who inherit copies of the mutated gene from both parents die before the age of 5 unless they receive ongoing treatment with antibiotics and procedures to clear the mucus from the respiratory passageways. Even with treatment, children may live only into their 20’s and 30’s, with few living beyond. The article suggests that interrupting the chemical message to coalesce could stop the uncontrollable, virulent infection.

To look on the bright side, excuse my attempt at a pun, quorum-sensing also operates when bacteria such as Vibrio fischeri luminesce. Crowded conditions are necessary. If the bacteria separate in the sea, the glowing terminates. Researchers in Bassler’s lab isolated the molecule that signals the coalescence of V.fischeri. Bassler found a different “autoinducer” molecule in a related bacterial species called V.harveyi. She later discovered a third molecule to which both species responded. Further testing revealed other bacterial species responsive to this third or universal autoinducer. Bassler’s lab has extended their studies to different bacterial species to determine the effect of the universal molecule when it is delivered alone or in combination with a specific quorum-sensing molecule. For example, cholera bacteria become extremely virulent only when they receive their specific quorum-sensing molecule and the universal one in combination.

This article got me thinking about communication between cells, between the unconscious and conscious brain, and between and among people like those in our Summer Institute and in our classrooms. To add to Angier’s final sentence, “With people, as with bacteria, nothing is stronger than community, united in purpose by just the right words” or molecules


1.       Angier, Natalie, “Listening to Bacteria,” Smithsonian, July/August, 2010, pages 76-82.

2.       Campbell, Neil A., Reece, Jane B., Biology, 8th ed. 2008, Pearson Benjamin Cummings, San Francisco, page 278.


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