Navigation Links
Evolution is as complicated as 1-2-3
Date:9/19/2012

EAST LANSING, Mich. A team of researchers at Michigan State University has documented the step-by-step process in which organisms evolve new functions.

The results, published in the current issue of Nature, are revealed through an in-depth, genomics-based analysis that decodes how E. coli bacteria figured out how to supplement a traditional diet of glucose with an extra course of citrate.

"It's pretty nifty to see a new biological function evolve," said Zachary Blount, postdoctoral researcher in MSU's BEACON Center for the Study of Evolution in Action. "The first citrate-eaters were just barely able to grow on the citrate, but they got much better over time. We wanted to understand the changes that allowed the bacteria to evolve this new ability. We were lucky to have a system that allowed us to do so."

Normal E. coli can't digest citrate when oxygen is present. In fact, it's a distinct hallmark of E. coli. They can't eat citrate because E. coli don't express the right protein to absorb citrate molecules.

To decipher the responsible mutations, Blount worked with Richard Lenski, MSU Hannah Distinguished Professor of Microbiology and Molecular Genetics. Lenski's long-term experiment, cultivating cultures of fast-growing E. coli, was launched in 1988 and has allowed him and his teammates to study more than more than 56,000 generations of bacterial evolution.

The experiment demonstrates natural selection at work. And because samples are frozen and available for later study, when something new emerges scientists can go back to earlier generations to look for the steps that happened along the way.

"We first saw the citrate-using bacteria around 33,000 generations," Lenski explained. "But Zack was able to show that some of the important mutations had already occurred before then by replaying evolution from different intermediate stages. He showed you could re-evolve the citrate-eaters, but only after some of the other pieces of the puzzle were in place."

In the Nature paper, Blount and his teammates analyzed 29 genomes from different generations to find the mutational pieces of the puzzle. They uncovered a three-step process in which the bacteria developed this new ability.

The first stage was potentiation, when the E. coli accumulated at least two mutations that set the stage for later events. The second step, actualization, is when the bacteria first began eating citrate, but only just barely nibbling at it. The final stage, refinement, involved mutations that greatly improved the initially weak function. This allowed the citrate eaters to wolf down their new food source and to become dominant in the population.

"We were particularly excited about the actualization stage," Blount said. "The actual mutation involved is quite complex. It re-arranged part of the bacteria's DNA, making a new regulatory module that had not existed before. This new module causes the production of a protein that allows the bacteria to bring citrate into the cell when oxygen is present. That is a new trick for E. coli."

The change was far from normal, Lenski said.

"It wasn't a typical mutation at all, where just one base-pair, one letter, in the genome is changed," he said. "Instead, part of the genome was copied so that two chunks of DNA were stitched together in a new way. One chunk encoded a protein to get citrate into the cell, and the other chunk caused that protein to be expressed."


'/>"/>

Contact: Layne Cameron
layne.cameron@cabs.msu.edu
517-353-8819
Michigan State University
Source:Eurekalert  

Related biology news :

1. Leading evolutionary scientist to discuss how genome of bacteria has evolved
2. An evolutionary surprise
3. Ancient Egyptian cotton unveils secrets of domesticated crop evolution
4. Did climate change shape human evolution?
5. A University of Tennessee professors hypothesis may be game changer for evolutionary theory
6. Analysis of stickleback genome sequence catches evolution in action
7. Study shows unified process of evolution in bacteria and sexual eukaryotes
8. Rapid method of assembling new gene-editing tool could revolutionize genetic research
9. Whats in a surname? New study explores what the evolution of names reveals about China
10. Scientists trace evolutionary history of what mammals eat
11. Not by DNA alone: How the epigenetics revolution is fostering new medicines
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Evolution is as complicated as 1-2-3
(Date:5/3/2016)... 3, 2016  Neurotechnology, a provider of high-precision ... Automated Biometric Identification System (ABIS) , a complete ... MegaMatcher ABIS can process multiple complex biometric transactions ... of fingerprint, face or iris biometrics. It leverages ... and MegaMatcher Accelerator , which have been ...
(Date:4/26/2016)... LONDON , April 26, 2016 ... EdgeVerve Systems, a product subsidiary of Infosys (NYSE: ... a partnership to integrate the Onegini mobile security ... (Logo: http://photos.prnewswire.com/prnh/20151104/283829LOGO ) The ... enhanced security to access and transact across channels. ...
(Date:4/15/2016)...  A new partnership announced today will help ... in a fraction of the time it takes ... life insurance policies to consumers without requiring inconvenient ... Diagnostics, rapid testing (A1C, Cotinine and HIV) and ... weight, pulse, BMI, and activity data) available at ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... ... June 23, 2016 , ... ... regulatory and technical consulting, provides a free webinar on Performing Quality ... 13, 2016 at 12pm CT at no charge. , Incomplete investigations are still ...
(Date:6/23/2016)... , June 22, 2016  Amgen (NASDAQ: ... of the QB3@953 life sciences incubator to ... health. The shared laboratory space at QB3@953 was created ... a key obstacle for many early stage organizations - ... of the sponsorship, Amgen launched two "Amgen Golden Ticket" ...
(Date:6/22/2016)... , June 22, 2016 Cell ... will allow them to produce up to one ... one lot within one week. These high-quality, consistent ... laboriously preparing cells and spend more time doing ... through a proprietary, high-volume manufacturing process that produces ...
(Date:6/22/2016)... 2016  According to Kalorama Information, the dominant ... market include significant efforts in automation as well ... and affordable sequencers, say the healthcare market research ... including sample prep materials.  The healthcare market research ... for Next Generation Sequencing (NGS) , highlights major ...
Breaking Biology Technology: