Navigation Links
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.


'"/>

Source:Baylor College of Medicine


Related biology news :

1. Wisconsin scientists grow critical nerve cells
2. Spleen may be source of versatile stem cells
3. Researchers discover way to make cells in the eye sensitive to light
4. Priming embryonic stem cells to fulfill their promise
5. Lack of enzyme turns fat cells into fat burners
6. Poor prenatal nutrition permanently damages function of insulin-producing cells in the pancreas
7. Elusive HIV shape change revealed; Key clue to how virus infects cells
8. Mouse brain cells rapidly recover after Alzheimers plaques are cleared
9. Enzyme allows B cells to resist death, leading to leukemia
10. Scientists rid stem cell culture of key animal cells
11. Genetically modified natural killer immune cells attack, kill leukemia cells
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:8/23/2018)... ... 22, 2018 , ... Lajollacooks4u is proud to have hosted a variety of groups this year ... such as Illumina, Qualcomm, Hewlett Packard, Sequenom and more, have all visited the La Jolla-based ... , Part of the reason clientele return is due to Lajollacooks4u’s signature team-building format, a ...
(Date:8/21/2018)... (PRWEB) , ... August 21, 2018 , ... ... throughput screening (HTS) solutions, Bellbrook Labs is dedicated to offering customers a successful ... assays, visitors will find a seamless transition between products, with relevant details such ...
(Date:8/17/2018)... ... August 16, 2018 , ... Today, the FSH ... announced that its Colorado Chapter will be holding its 3rd annual Walk & ... at the Philip S. Miller Park, advocates for public awareness and is raising funds ...
Breaking Biology News(10 mins):
(Date:9/1/2018)... (PRWEB) , ... August 31, 2018 , ... ... research results of the impact of a proprietary biofield energy treated nutraceutical supplement ... assessed biomarkers for immune function response and blood, as well as, organ-specific inflammation. ...
(Date:8/29/2018)... N.Y. (PRWEB) , ... August 28, 2018 , ... ... leading online retailer of contact lenses, has been ranked in 1138th place on ... growing private companies. , The list represents the most successful companies within ...
(Date:8/26/2018)... South Korea (PRWEB) , ... August 24, 2018 ... ... scientific paper on that stem cell-derived exosomes dramatically relieves atopic dermatitis and inhibits ... Therapy. , According to the paper, the symptoms of mice having severe ...
(Date:8/17/2018)... ... August 16, 2018 , ... The opening of the ... acquired Chemko Technical Services in 2016. Chemko had a well established local presence, servicing ... at KSC on projects such as the ongoing work at the Mobile Launch Platform ...
Breaking Biology Technology: