February 1, 2011

Scientist Describes Conspiracies Of Small Fellow Travelers

Those who believe in UFOs (unidentified flying objects) and extraterrestrial life frequently tell us, "We are not alone." We are not, but we do not have to look into space to find company. Our most frequent companions are the billions of bacteria that inhabit us "“ in our gut and genital tract, on our skins, our mucous membranes and elsewhere.

Just as we are social creatures, bacteria needs that sense of community to take action. Scientists call this "quorum sensing." Dr. Bonnie Bassler, professor of molecular biology at Princeton University and a Howard Hughes Medical Institute investigator, said in the 2011 Jeanette Oshman Efron Lecture in Molecular and Human Genetics at Baylor College of Medicine that the data not only show that bacteria of the same species communicate, but that they also have a more universal language through which they communicate with other bacterial species.

Interrupt the conversation

"If we could interrupt that conversation, we might be able to do therapeutics," she said.

In order to accomplish any task, "bacteria vote chemically, and those votes get counted," she said. Only when the bacteria have a "quorum" and the votes can they take action.

Bacteria can also talk across species using a special molecule Bassler calls an autoinducer. "We think bacteria scan the environment, asking the question, 'Am I alone or am I in a group?'"

Behavior modification

Perhaps a new kind of therapeutic could result from this communication. Instead of an antibiotic that kills the bacteria, "can we do behavior modification? Can we make the bacteria unable to talk or hear?" Bassler asked. While the bacteria are unable to communicate, the body's immune system might be able to find and get rid of them.

One method would be to devise a new molecule of a shape that could jam the signaling area of the bacteria "“ the receptor. A screen of a special library of small molecules controlled by the National Institutes of Health gave Bassler and her colleagues a list of some that met the requirements and seemed to be of a shape to prevent the autoinducer from communicating. Her work continues along those lines.

New techniques for seeing the "shape" of molecules and new understanding of the communications among organisms all work together to push this kind of research, which becomes more critical as the issue of antibiotic-resistant bacteria comes to the fore.

Looking inside, we find our most constant companions "“ some helpful, others detrimental. Bassler's work seeks to translate a new understanding of what they mean.


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