The line between art and science can be confusing. Researchers studying a social bacterium that moves and feeds in coordinated swarms have unintentionally recreated something that looks a lot like a familiar masterpiece.
Individual organisms self-organize into tiny circular swarms when a certain gene is overexpressed in a bacterium.
The scene looks similar to Van Gogh's The Starry Night once the swarms are artificially colored.
D. Wall is from the University of Wyoming.
A mixture of two strains of myxobacteria, one that overexpresses TraAB and the other that is non-adhesive and non-reversing, is shown above.
Microbiologist Daniel Wall from the University of Wyoming says that their work shows how a social bacterium, known for rich sources of therapeutic natural products and as crop biocontrol agents, serves as a powerful model for studying emerging behaviors that also exhibit artistic beauty.
The night is dark. The Wikimedia Commons/Public Domain has a picture ofVincent van Gogh.
M. xanthus is a social bacterium because it needs to find and recognize relatives to survive.
The rod-shaped bacterium is better at attacking its prey after forming clumps. Each cell is capable of producing shirbents that facilitate predatory feeding.
Researchers have been fascinated by this social behavior for a long time, but they still don't have a model for their complex movements.
Wall and his colleagues discovered a single genetic switch that turned this grouping behavior on and off.
The switch specifically controls for the TraA sequence, which provides a surfacereceptor for the bacterium to recognize and attach to the partner receptor, TraB, on its kin.
The bacterium can exchange its genes with the rest of the group once it glues itself to a family member.
Lab research shows that organisms can pool their genes together to give the most powerful punch to their prey when they encounter food.
When the team overexpresses TraAB connections, all of that changes. The swarm can stick together in the first place, but it can't change its shape or direction if there's too much of this'social glue'.
The University of Wyoming.
A strain of myxobacteria that overexpresses TraAB and is non-adhesive and non-reversing is shown above.
"In normal wild-type cells, they go back and forth, back and forth, like a commuter train," says bioengineer Oleg Igoshin at Rice University.
The head and the tail become the same thing. They do it every 8 minutes.
The swarm can't switch its head to its tail because of an overexpression of TraAB.
Computational models suggested that this would happen, but the authors couldn't figure out why. The TraAB connection wasn't directly involved in the regulation of the swarm's movements.
The team suspected that the sticky quality of TraB was preventing the swarm of cells from changing direction.
"Our idea was that there is a contact- dependent signal between cells that suppresses the reversals," says Igoshin.
The cells are in contact with others all the time, but they are not permanent contacts. If TraAB overexpression makes you sticky, your neighbor will remain your neighbor for longer, and that could signal the reversals.
D. Wall is from the University of Wyoming.
Two myxobacteria strains have different types of TraA receptors that adhere to themselves but not each other.
The authors were able to verify their hunch by running this scenario in models. The usual head-to-tail swarms suddenly became rotating swirls of cells, as large as a millimeter or more, with only changes to the TraAB connection.
In the lab, it was confirmed that this happened to thebacteria in real life. The swirls can occur when a strain overexpresses stickiness and also when a strain is genetically modified to be non-reversing.
The result is a better understanding of how millions of cells coordinate their movements and it's also a fascinating picture of the world.
The study was published.
