Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists find first active ’jumping genes’ in rice

09.01.2003

University of Georgia researchers studying rice genomes under a National Science Foundation Plant Genome Research Program award have identified the species’ first active DNA transposons, or "jumping genes."

The research is published in the Jan. 9 edition of the journal Nature.

In collaboration with researchers from Cornell, Washington University and Japan, geneticist Susan Wessler also discovered the first active "miniature inverted-repeat transposable element," or "MITE," of any organism.

Rice (Oryza sativa), an important food crop worldwide, has the smallest genome size of all cereals at 430 million base pairs of DNA. About 40 percent of the rice genome comprises repetitive DNA that does not code for proteins and thus has no obvious function for the plant. Much of this repetitive sequence appears to be transposons similar to MITEs. But like most genomes studied to date, including the human genome, the function of this highly repeated so-called "junk DNA" has been a mystery. The discovery of active transposons in rice provides startling new insights into how genomes change and what role transposons may play in the process.

Active DNA transposons can move new copies of DNA to different places in the genome. To hunt for active DNA transposons, the researchers made use of the publicly available genome sequences for two subspecies of rice, japonica and indica. The researchers reasoned that in plants where such transposons move actively there would be multiple copies of an almost identical sequence. If they could find the conserved sequences in the two rice genomes, then they could test for transposon movement in cell cultures because the number of elements should have increased over time.

Using this approach, the researchers found a repeated sequence of 430 base pairs that was identified as a candidate for an active MITE because of the high degree of sequence conservation among the copies. Recognizing that it shared common size and other characteristics with MITEs, they named it "mPing" for "miniature Ping." They calculated that the entire genome of japonica rice contained about 70 copies of mPing, while indica rice had about 14 copies. When they looked in indica rice cell cultures, the number of mPing elements increased, suggesting that it was indeed actively transposing.

It was puzzling to understand how mPing could transpose, since MITEs do not code for any proteins and are thus unable to move on their own. The researchers reasoned that there must be another "autonomous" transposon that encodes proteins, enabling itself and other related elements to move. To find this autonomous element, the researchers compared the mPing sequence with the japonica and indica rice genome sequences to look for longer, related elements. They found two candidates: a long version called the "Ping" sequence and another shorter sequence they named "Pong." Ping lacked functional coding sequence and was also found only in japonica rice as a single copy. On the other hand, Pong was present in high copy numbers in all varieties, contained appropriate coding sequences, and also increased in number along with mPing during cell culture. This led the researchers to suspect that Pong, not Ping, is the autonomous element that causes mPing to transpose. It is also possible, the researchers speculate, that Ping and Pong may co-activate mPing in some cases.

Wessler and her collaborators have shed new light on the idea that transposons may be instrumental in promoting the diversity of plants during domestication. Their work meshes with an idea, raised almost 20 years ago by Nobel Prize-winning maize geneticist Barbara McClintock, that transposons are part of the dynamic forces shaping plant genomes.

The research findings will help researchers unravel the events leading to the origin, spread, and disappearance of miniature transposons. Remarkably, MITEs make up a large part of the non coding DNA in plant genomes. Through studies of transposons such as MITEs, researchers will begin to understand the impact of so called "junk DNA" on the dynamic structure and function of the genomes of all organisms.

Julie A. Smith | National Science Foundation
Further information:
http://www.nsf.gov
http://www.nsf.gov/home/news.html

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>