Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rice centromere, supposedly quiet genetic domain, surprises

12.01.2004


Probing the last genomic frontier of higher organisms, an international team of scientists has succeeded in sequencing a little understood - but critical - genetic domain in rice.



In doing so, the group, led by Jiming Jiang, a professor of horticulture at the University of Wisconsin-Madison, and C. Robin Buell of the Institute for Genomic Research in Rockville, Md., has exposed a supposedly barren region of a rice chromosome known as the centromere. The work, published in the current (Jan. 11) online editions of the journal Nature Genetics, reveals for the first time that a native centromere, typically composed of enormous spans of indecipherable, non-coding DNA, contains active genes.

The feat promises to help fill in a key genetic void and enhance the scientific understanding of chromosomes, the molecular structures that are found in all animal and plant cells, and are the essential carriers of hereditary information, enabling the processes of cell division and replication.


At a practical level, the work is a necessary step toward science’s long-term goal of creating an artificial chromosome for plants, says Jiang. Such a tool, now available only for humans and yeast, would be an invaluable aid to scientific study and a precursor to precision plant engineering techniques.

"This is a significant step," says Jiang. "This is the first centromere to be sequenced at this level for any higher organism."

The centromere of rice, says Jiang, lent itself to sequencing because, unlike centromeres from other organisms, it is of a manageable size. Most centromeres are composed of vast stretches of what was once called "junk DNA," seemingly nonsense genetic sequences with no apparent coding function.

"They’re humongous," Jiang explains. The DNA within centromeres is "highly repetitive, and it is resistant to mapping, cloning and sequencing," he says.

The finding of active genes was a surprise, says Jiang. The newly discovered rice centromere genes, whose functions are unknown, belie the idea that the centromere is an enormous molecular wasteland composed only of non-coding DNA.

"This is the first time active genes have been found in a native centromere," according to Jiang. "There are at least four active genes" interspersed in the DNA of the rice centromere.

The centromere is one of three essential elements of every chromosome. In addition to centromeres, chromosomes are composed of telomeres, genetic sequences that cap and protect the ends of chromosomes, and a site known as the "origin of replication" or "ori," where the actual business of genetic replication takes place. With all three components in hand, it would be possible, in theory, to construct an artificial chromosome.

In most organisms, including the critical model organisms such as the mouse, the fruit fly Drosophila melanogaster and the plant Arabidopsis thaliana, centromeres have proved to be nearly intractable for sequencing.

The rice centromere is accessible, says Jiang, because the centromere of rice chromosome 8 lacks the vast tracts of repetitive non-coding DNA common to most species. And that there are active genes in the centromeres of rice provides an intriguing window to evolution. It may be that the centromere sequenced by the team led by Jiang is in its early evolutionary stages.

The evolutionary progression of the centromeres, Jiang suggests, may be analogous to how temperate forests evolve from more diverse ecosystems to climax forests where a single species of tree dominates. In the rice centromere, it may be that evolution has not yet purged active genes to be replaced by the long and repetitive blocks of DNA that mark the centromeres of most organisms.

In addition to Jiang and Buell, co authors of the Nature Genetics paper include lead author Kiyotaka Nagaki, also of UW-Madison; Zhukuan Cheng of the Chinese Academy of Sciences; Shu Ouyang, Mary Kim and Kristine M. Jones of the Institute for Genomic Research; and Paul B. Talbert and Steven Henikoff of the Howard Hughes Medical Institute at the Fred Hutchinson Cancer Research Center on Seattle.


- Terry Devitt (608) 262-8282, trdevitt@wisc.edu

Terry Devitt | EurekAlert!
Further information:
http://www.wisc.edu/

More articles from Life Sciences:

nachricht Maelstroms in the heart
22.02.2018 | Max-Planck-Institut für Dynamik und Selbstorganisation

nachricht Decoding the structure of the huntingtin protein
22.02.2018 | Max-Planck-Institut für Biochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

The RWI/ISL-Container Throughput Index started off well in 2018

22.02.2018 | Business and Finance

FAU researchers demonstrate that an oxygen sensor in the body reduces inflammation

22.02.2018 | Health and Medicine

Histology in 3D: new staining method enables Nano-CT imaging of tissue samples

22.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>