Featured Research

from universities, journals, and other organizations

Time In A Bottle: Scientists Watch Evolution Unfold

Date:
October 19, 2009
Source:
Michigan State University
Summary:
A 21-year experiment that distills the essence of evolution in laboratory flasks not only demonstrates natural selection at work, but could lead to biotechnology and medical research advances, researchers say.

E. coli cultures in the laboratory of Michigan State University evolutionary biologist Richard Lenski.
Credit: Greg Kohuth, Michigan State University

A 21-year Michigan State University experiment that distills the essence of evolution in laboratory flasks not only demonstrates natural selection at work, but could lead to biotechnology and medical research advances, researchers said.

Charles Darwin's seminal Origin of Species first laid out the case for evolution exactly 150 years ago. Now, MSU professor Richard Lenski and colleagues document the process in their analysis of 40,000 generations of bacteria, published this week in the international science journal Nature.

Lenski, Hannah Professor of Microbial Ecology at MSU, started growing cultures of fast-reproducing, single-celled E. coli bacteria in 1988. If a genetic mutation gives a cell an advantage in competition for food, he reasoned, it should dominate the entire culture. While Darwin's theory of natural selection is supported by other studies, it has never before been studied for so many cycles and in such detail.

"It's extra nice now to be able to show precisely how selection has changed the genomes of these bacteria, step by step over tens of thousands of generations," Lenski said.

Lenski's team periodically froze bacteria for later study, and technology has since developed to allow complete genetic sequencing. By the 20,000-generation midpoint, researchers discovered 45 mutations among surviving cells. Those mutations, according to Darwin's theory, should have conferred some advantage, and that's exactly what the researchers found.

The results "beautifully emphasize the succession of mutational events that allowed these organisms to climb toward higher and higher efficiency in their environment," noted Dominique Schneider, a molecular geneticist at the Université Joseph Fourier in Grenoble, France.

Lenski's long-running experiment itself is uniquely suited to answer some critical questions -- such as whether rates of change in a bacteria's genome move in tandem with its fitness to survive.

"The coupling between genomic and adaptive evolution is complex and can be counterintuitive," Lenski concluded. "The genome was evolving along at a surprisingly constant rate, even as the adaptation of the bacteria slowed down a lot. But then suddenly the mutation rate jumped way up, and a new dynamic relationship was established."

A mutation involved in DNA metabolism arose around generation 26,000, causing the mutation rate everywhere else in the genome to increase dramatically. The number of mutations jumped to 653 by generation 40,000, but researchers surmise that most of the late-evolving mutations were not helpful to the bacteria.

Gene mutations involved in human DNA replication are involved in some cancers. Many of the patterns observed in the experiment also occur in certain microbial infections, "and cancer progression is a fundamentally similar evolutionary process," observed collaborator Jeffrey Barrick. "So what we learn here can help us better understand the course of these diseases."

Barrick, a postdoctoral researcher in MSU's Department of Microbiology and Molecular Genetics, developed computational tools to discover and validate often complex mutations. "We know an astounding amount about the details of evolution in these little Erlenmeyer flasks," he said.

The Nature paper involved collaboration with scientists from South Korea as well as France and MSU. The research, said genomics team leader Jihyun Kim of the Korea Research Institute of Bioscience and Biotechnology, "is not only useful in understanding the tempo and mode of evolution, but can serve as a nice framework for practical applications in biotechnology, such as improving the performance or productivity of an industrial strain."

Thousands of generations later, the MSU experiment continues to evolve. "Like a lot of science, our study answers some questions but raises many others," Lenski said.

The research has been supported by the National Science Foundation and the Defense Advanced Research Projects Agency.

 

 


Story Source:

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


Journal Reference:

  1. Jeffrey E. Barrick, Dong Su Yu, Sung Ho Yoon, Haeyoung Jeong, Tae Kwang Oh, Dominique Schneider, Richard E. Lenski & Jihyun F. Kim. Genome evolution and adaptation in a long-term experiment with Escherichia coli. Nature, 2009; DOI: 10.1038/nature08480

Cite This Page:

Michigan State University. "Time In A Bottle: Scientists Watch Evolution Unfold." ScienceDaily. ScienceDaily, 19 October 2009. <www.sciencedaily.com/releases/2009/10/091018141716.htm>.
Michigan State University. (2009, October 19). Time In A Bottle: Scientists Watch Evolution Unfold. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2009/10/091018141716.htm
Michigan State University. "Time In A Bottle: Scientists Watch Evolution Unfold." ScienceDaily. www.sciencedaily.com/releases/2009/10/091018141716.htm (accessed April 18, 2014).

Share This



More Fossils & Ruins News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Couple Finds Love Letters From WWI In Attic

Couple Finds Love Letters From WWI In Attic

Newsy (Apr. 17, 2014) — A couple found love letters from World War I in their attic. They were able to deliver them to relatives of the writer of those letters. Video provided by Newsy
Powered by NewsLook.com
Erotic Art Offers Glimpse of China's 'lost' Sexual Philosophy

Erotic Art Offers Glimpse of China's 'lost' Sexual Philosophy

AFP (Apr. 16, 2014) — Explicit Chinese art works dating back centuries go on display in Hong Kong, revealing China's ancient relationship with sex. Video provided by AFP
Powered by NewsLook.com
French Historians Fight to Save Iconic La Samaritaine Buildings

French Historians Fight to Save Iconic La Samaritaine Buildings

AFP (Apr. 15, 2014) — Parisians and local historians are fighting to save one of the French capital's iconic buildings, the La Samaritaine department store. Duration: 01:42 Video provided by AFP
Powered by NewsLook.com
Bee Fossils Provide Insight Into Ice Age Environment

Bee Fossils Provide Insight Into Ice Age Environment

Newsy (Apr. 12, 2014) — Archeologists have found many fossils in the La Brea Tar Pits, including those of saber-tooth tigers and mammoths. Video provided by Newsy
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:
from the past week

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