Featured Research

from universities, journals, and other organizations

Growing bacteria keep time, know their place

Date:
October 8, 2013
Source:
Duke University
Summary:
Working with a synthetic gene circuit designed to coax bacteria to grow in a predictable ring pattern, scientists have revealed an under-appreciated contributor to natural pattern formation: Time.

Ring patterns form in a micro-colony of engineered bacteria.
Credit: Stephen Payne, Pratt School of Engineering, Duke.

Working with a synthetic gene circuit designed to coax bacteria to grow in a predictable ring pattern, Duke University scientists have revealed an underappreciated contributor to natural pattern formation: time.

Related Articles


In a series of experiments published Oct. 8, 2013, in the journal Molecular Systems Biology, associate professor of biomedical engineering Lingchong You and his colleagues show that their engineered gene circuit functions as a timing mechanism, triggering a predictable ring growth pattern that adjusts to the size of its environment.

The unexpected result provides a potential explanation for how organs such as the heart and lungs know when to stop growing and runs counter to established theories, one of which dates back to computer pioneer Alan Turing. The finding also lays a foundation for engineering patterned bacteria as a biological scaffold for new materials such as metallic films, which have potential applications in the energy field.

"Everywhere you look in nature there are patterns, many of them very beautiful and even inspirational," said You. "Our work adds another dimension to the general principles of pattern formation."

Turing's ideas guided theories of pattern formation in biology for decades. He imagined biological patterns arose from the interaction of chemicals he termed "morphogens" that initiated and directed patterns by triggering on- or off-switches, depending on their concentration in a particular location. In a theoretical treatise published in 1952, Turing used math to show how these morphogens could move in space, revealing patterns that mimic those seen in animal skins and leaf shapes.

But like persistent myths, theories can also become entrenched. You and his colleagues became puzzled when a synthetic gene circuit they built to test Turing's model didn't create the growth pattern they were expecting.

Using molecular biology techniques, he and his colleagues had programmed the common laboratory bacterium E. coli to produce two molecules. One served as the "on" switch that spreads throughout the growing colony. The other served as the "off" switch that would be triggered by an increasing concentration of the "on" signal.

The researchers also engineered the bacteria to produce fluorescent colors so they could watch patterns form. But as the colonies grew, the emerging patterns didn't behave as predicted. They were much smaller than the research team expected based on how fast the "on" signal should diffuse.

To solve the mystery, the scientists added a high concentration of the "on" signal to the growth chamber, flooding the bacteria with the signal. The bacteria formed the same distinctive ring pattern over the same time, which showed they weren't responding to changes in the concentration of the "on" signal in space.

Instead, the researchers reasoned that the "on" signal served as a timing cue. The research team then created a mathematical model of the timing mechanism and predicted how the cells would respond to changes in the size of their growth chamber.

"By serving as a timing cue, the morphogen 'on' signal enables the system to sense and respond to the size of the environment," said You. "The larger the area, the longer it takes for the morphogen to accumulate to a high enough concentration to trigger pattern formation. As such, a larger area will lead to a larger ring pattern."

Follow-up experiments confirmed the model, and provided a simple example of how growing organs may be able to sense the size of their environment -- and when it's time to stop growing -- potentially solving a persistent mystery in developmental biology.

You and his colleagues plan to use the artificial gene circuit to create more complex biological patterns, both to further explore general principles of pattern formation and to serve as scaffolds for making new materials, such as thin metal films for energy applications.


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Stephen Payne, Bochong Li, Yangxiaolu Cao, David Schaeffer, Marc D Ryser, Lingchong You. Temporal control of self-organized pattern formation without morphogen gradients in bacteria. Molecular Systems Biology, 2013; 9 DOI: 10.1038/msb.2013.55

Cite This Page:

Duke University. "Growing bacteria keep time, know their place." ScienceDaily. ScienceDaily, 8 October 2013. <www.sciencedaily.com/releases/2013/10/131008152216.htm>.
Duke University. (2013, October 8). Growing bacteria keep time, know their place. ScienceDaily. Retrieved January 25, 2015 from www.sciencedaily.com/releases/2013/10/131008152216.htm
Duke University. "Growing bacteria keep time, know their place." ScienceDaily. www.sciencedaily.com/releases/2013/10/131008152216.htm (accessed January 25, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, January 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Florida Might Legalize Black Bear Hunting

Florida Might Legalize Black Bear Hunting

Newsy (Jan. 24, 2015) A string of black bear attacks has Florida officials considering lifting the ban on hunting the animals to control their population. Video provided by Newsy
Powered by NewsLook.com
Ebola Killing Large Portion Of Ape Population

Ebola Killing Large Portion Of Ape Population

Newsy (Jan. 23, 2015) Experts estimate Ebola has wiped out one-third of the world&apos;s gorillas and chimpanzees. Video provided by Newsy
Powered by NewsLook.com
Controversy Shrouds Captive Killer Whale in Miami

Controversy Shrouds Captive Killer Whale in Miami

Reuters - Light News Video Online (Jan. 23, 2015) Activists hope the National Oceanic and Atmospheric Agency (NOAA) will label killer whales endangered, allowing lawyers to sue a Miami aquarium to release an orca into the wild after 44 years. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
‘Healthy’ Foods That Surprisingly Pack on Pounds

‘Healthy’ Foods That Surprisingly Pack on Pounds

Buzz60 (Jan. 23, 2015) Some &apos;healthy&apos; foods are actually fattening. Fitness and nutrition expert John Basedow (@JohnBasedow) shines a light on the sneaky foods like nuts, seeds, granola, trail mix, avocados, guacamole, olive oil, peanut butter, fruit juices and salads that are good for you...but not so much for your waistline. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins