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 Polymers Based on Boron?
18.01.2018 | Julius-Maximilians-Universität Würzburg

nachricht Bioengineered soft microfibers improve T-cell production
18.01.2018 | Columbia University School of Engineering and Applied Science

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Polymers Based on Boron?

18.01.2018 | Life Sciences

Bioengineered soft microfibers improve T-cell production

18.01.2018 | Life Sciences

World’s oldest known oxygen oasis discovered

18.01.2018 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>