Navigation Links
Duke-NIEHS team shows how DNA repairs may reshape the genome

DURHAM, N.C. Researchers at Duke University Medical Center and at the National Institute of Environmental Health Sciences (NIEHS) have shown how broken sections of chromosomes can recombine to change genomes and spawn new species.

"People have discovered high levels of repeated sequences in the genomes of most higher species and spun theories about why there are so many repeats," said Lucas Argueso, Ph.D., a research scholar in Duke's Department of Molecular Genetics and Microbiology. "We have been able to show with yeast that these repeated sequences allow the formation of new types of chromosomes (chromosome aberrations), and represent one important way of diversifying the genome."

The scientists used X-rays to break yeast chromosomes, and then studied how the damage was repaired. Most of the chromosome aberrations they identified resulted from interactions between repeated DNA sequences located on different chromosomes rather than from a simple re-joining of the broken ends on the same chromosome.

Chromosome aberrations are a change in the normal chromosome complement because of deletion, duplication, or rearrangement of genetic material. On rare occasions, the development of one of these new chromosome structures is beneficial, but more often DNA changes can be detrimental, leading to problems like tumors.

"Every so often the rearrangements may be advantageous," Argueso said. "Those particular differences may prove to be more successful in natural selection and eventually you may get a new species."

The radiation-induced aberrations in yeast were initially detected by co-author Jim Westmoreland in the NIEHS Laboratory of Molecular Genetics and the molecular dissection was done by Duke's Argueso.

In the yeast used for this study, the repeated DNA sequences account for about 3 percent of the genome. In higher species, like humans, about half of the genome consists of these repeated sequences, "which makes for an Achilles heel among humans," Argueso said. "If you have a break in this repeated part, you can repair not only from the same chromosome, but also from a similar repeated sequence in many other places in the genome."

Sequencing the genomes of different humans has turned up a surprising amount of structural variation between individuals, said Thomas D. Petes, Ph.D., chair of Duke molecular genetics and microbiology and co-author of the yeast study. "We expected to see primarily single base pair changes or small deletions and insertions. No one expected to see that one person would have two copies of a gene, while others would have one or three copies of the same gene."

These human studies also showed that many of the rearrangements found in humans are at sites of repeated DNA, which may occur through a mechanism similar to what this study found in yeast.

Petes said this work with yeast also could prove relevant to cancer research. "Most solid tumors have a high level of these rearrangements, as well as a high level of extra chromosomes; recombination between repeated genes is clearly one way of generating rearrangements, although some rearrangements also occur by other pathways," he said. "It is an evolutionary battle between normal cells and tumor cells. One way that tumor cells can break free of normal cell growth regulation is to rearrange their genomes."


Contact: Mary Jane Gore
Duke University Medical Center

Related biology news :

1. Nano vaccine for hepatitis B shows promise for third world
2. Experimental chemotherapy regimen shows promise in treating advanced lung cancer
3. New breastfeeding study shows most moms quit early
4. When our protective armor shows weakness
5. Lab study shows methadone breaks resistance in untreatable forms of leukemia
6. Immunotherapy in high-risk pediatric sarcomas shows promising response
7. New study shows compounds from soy affect brain and reproductive development
8. OSU study shows exposure to bad air raises blood pressure
9. Study shows parasites outweigh predators
10. Study shows increased education on nanotech, human enhancement increases public concerns
11. Sociological research shows combined impact of genetics, social factors on delinquency
Post Your Comments:
(Date:8/15/2017)... 15 2017   ivWatch LLC , a medical device company ... today announced receipt of its ISO 13485 Certification, the global standard ... Organization for Standardization (ISO®). ... Model 400 Continuous Monitoring device for the early detection of IV ... "This is an important milestone for ...
(Date:5/23/2017)... the first robotic gym for the rehabilitation and functional motor sense evaluation ... Genoa, Italy . The first 30 robots will be available from ... . The technology was developed and patented at the IIT laboratories ... Technology thanks to a 10 million euro investment from entrepreneur Sergio Dompè. ... ...
(Date:4/19/2017)... April 19, 2017 The global ... landscape is marked by the presence of several large ... held by five major players - 3M Cogent, NEC ... accounted for nearly 61% of the global military biometric ... in the global military biometrics market boast global presence, ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... CA, USA (PRWEB) , ... October 11, 2017 , ... ... to take place on 7th and 8th June 2018 in San Francisco, CA. The ... influencers as well as several distinguished CEOs, board directors and government officials from around ...
(Date:10/11/2017)... (PRWEB) , ... October 11, 2017 , ... Disappearing forests ... the lives of over 5.5 million people each year. Especially those living in larger ... startup Treepex - based in one of the most pollution-affected countries globally - decided ...
(Date:10/10/2017)... ... October 10, 2017 , ... ... targeted antibody-drug conjugate (ADC) therapeutics, today confirmed licensing rights that give it ... Nanoparticle), a technology developed in collaboration with Children’s Hospital Los Angeles (CHLA). ...
(Date:10/10/2017)... , Oct. 10, 2017 SomaGenics announced ... the NIH to develop RealSeq®-SC (Single Cell), expected to ... profiling small RNAs (including microRNAs) from single cells using ... highlights the need to accelerate development of approaches to ... "New techniques for measuring levels of ...
Breaking Biology Technology: