Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Stressed cells spark DNA repair missteps and speed evolution


When Dr. Susan Rosenberg, professor of molecular and human genetics at Baylor College of Medicine, first published her finding that the mutation rate increased in bacteria stressed by starvation, sometimes resulting in a rare change that benefited the bacteria, it was controversial.

In a report in the current issue of the journal Molecular Cell, she and her colleagues describe not only how it happens but also show that this only occurs at a special time and place in the stressed cells.

It all begins with the way that the cell repairs breaks in the double strands of DNA that are its genetic blue print. Usually, when this happens, special protein machinery in the cell copies the missing DNA from another chromosome and rejoins the broken ends around the newly synthesized genetic material.

"It fixes the hole in the DNA by copying similar information," said Rosenberg. However, when the process goes wrong, the repair process introduces errors into the DNA.

When graduate student Rebecca G. Ponder set up a system so that she could control where the break in DNA occurred, she found that errors occurred right next to the break in the stressed cells, and that the rate of errors was 6,000 fold higher than in cells whose DNA was not broken. "It’s really about local repair," said Rosenberg. Not only that, but subsequent experiments proved that this mechanism of increased mutation at sites of DNA repair occurs only in the cells under stress. "Even if you get a break in a cell, it won’t process it in a mutagenic way," said Rosenberg. "The cell repairs it, but does not make mutations unless the cell is stressed."

The findings support the notion that the increased mutation rate may give the cells a selective advantage, she said. Faced with starvation, most cells do not increase their mutation rate. Then if food becomes available again, they do well.

Among the small percentage that do increase mutations, most of the errors are neutral, not affecting cells at all. Many are deleterious, resulting in cell death. But a small percentage is advantageous, allowing the cells to survive in an adverse environment.

The fact that the changes in the rate of mutation occur only in a certain physical space at a certain time gives the cells advantage because it reduces the risk to the whole colony. DNA breaks occur only rarely in each individual cell. If the mutations are restricted in time and space, it reduces the risk that the mistakes in repair will affect some other gene. It can also enhance the likelihood of two mutations occurring in the same gene or neighboring genes.

"This can speed evolution of complex protein machines." Rosenberg said.

Ross Tomlin | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Strong, steady forces at work during cell division
20.10.2016 | University of Massachusetts at Amherst

nachricht Disturbance wanted
20.10.2016 | Max Delbrück Center for Molecular Medicine in the Helmholtz Association

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>