Navigation Links
UGA researchers propose model for disorders caused by improper transmission of chromosomes
Date:8/16/2009

Parents of healthy newborns often remark on the miracle of life. The joining of egg and sperm to create such delightful creatures can seem dazzlingly beautiful if the chromosome information from each parent has been translated properly into the embryo and newborn.

The darker side is that when extra copies of chromosomes or fewer than the normal 46 (23 from each parent) are present, tragic birth defects can occur. Now, scientists at the University of Georgia have developed a model system for plants and animals that shows the loss of a key structural protein can lead to the premature separation of one DNA copy called a chromatid.

The new model shows for the first time that the loss of this protein can lead to aneuploidythe name given to birth disorders caused by extra or too few chromosomes. Disorders caused by errors in the proper transmission of chromosomes from each parent are uncommon but tragic nonetheless. Best known may be Down Syndrome, which is caused by an extra copy of chromosome 21. Many errors in chromosome transmission are so severe that miscarriages usually occur.

"As we know, human females have all the eggs they will ever have from the time of birth, and so as they age, the protein structures on chromosomes also age," said Kelly Dawe, a geneticist and plant biologist at UGA. "If an egg is fertilized late in life, the final stages of chromosome separation may not occur properly. The goal of the work, which was done in maize, is to find out which parts of the chromosomes are most sensitive to failure. We now believe that proteins in a structure called the kinetochore are among the most sensitive to degradation or mutation. That may be a clue as to why older women have more problems with these kinds of chromosomal disorders when giving birth than younger women."

The research was published today in the journal Nature Cell Biology. Co-author on the paper is former University of Georgia graduate student Xuexian Li.

Irregularities in chromosome number are usually caused during a biological event called meiosis, in which the number of chromosomes per cell is halved and, in animals, results in the formation of gametes or sex cells. While the biology of meiosis has been known for more than a century, major questions remain about how all the constituent cell parts must coordinate to make the process successful.

During the two stages of meiosis, chromosomes are first separated by type, ensuring that only one of each gene is represented and then separated in half again in preparation for fertilization. The authors showed that the first stage is orchestrated in part by the kinetochore that attaches chromosomes to the rest of the cell. When they suppressed a kinetochore protein called MIS12, the chromosomes no longer separated by type and jumped to the second stage before completing the first. These failures closely mimic those seen in eggs from older women.

The cell division processes that Dawe and Li studied have implications for other diseasessuch as canceras well. And yet a genuine payoff may come in the form of genetically improved lines of corn.

Dawe's work opens the possibility of a more positive outcome: the ability to engineer so-called "artificial chromosomes" with useful genes into corn varieties. Though that may be years off, it could offer a way to create lines that could resist drought, disease and insect pests without harming the environment.

Researchers are racing to design artificial chromosomes that behave like natural ones. With such an engineered chromosome, the positives traits researchers could give to corn plants would be almost limitless.

"You could really put genes in there at will, stacking traits that would make the plants able to withstand problems that now limit production greatly all over the world," said Dawe. "But to get from theory to practice, we will need a much clearer understanding of meiosis."

Unfortunately, most early generation artificial chromosomes have failed at meiosis in a nearly identical manner as plants with reduced MIS12. By manipulating MIS12 or other similar proteins, Dawe hopes to correct these defects.


'/>"/>

Contact: Kelly Dawe
kelly@plantbio.uga.edu
706-542-1658
University of Georgia
Source:Eurekalert

Related biology news :

1. Researchers develop new, more-sensitive assay for detecting DNA methylation in colon cancer
2. NIH-funded researchers sequence exomes of 12 people
3. USC researchers identify regulatory genetic sequences that may predict risk for prostate cancer
4. K-State lab gives researchers the tools to study porcine circovirus associated diseases
5. Hebrew U. researchers shed light on the brain mechanism responsible for processing of speech
6. SLAC researchers reveal the dance of water
7. McGill/JGH researchers successfully reverse multiple sclerosis in animals
8. EMBO pioneers pension plan for internationally mobile postdoctoral researchers
9. Mary had a lot of lambs: Researchers identify way to accelerate sheep breeding
10. University of Hawaii at Manoa researchers reveal ocean acidification at Station ALOHA
11. UBC researchers find first-ever wanderlust gene in tiny bony fish
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:2/2/2016)... YORK , Feb. 2, 2016 ... of the bioinformatic market by reviewing the recent ... enabled tools that drive the field forward. Includes ... to: Identify the challenges and opportunities that ... providers and software solution developers, as well as ...
(Date:2/2/2016)... Technology Enhancements Accelerate Growth of X-ray Imaging ... and computed radiography markets in Thailand ... Indonesia (TIM). It provides an in-depth analysis ... as regional market drivers and restraints. The study offers ... market attractiveness, both for digital and computed radiography. Market ...
(Date:2/2/2016)... Calif. , Feb. 2, 2016  Based ... market, Frost & Sullivan recognizes US-based Intelligent Retinal ... Frost & Sullivan Award for New Product Innovation. ... in North America , is ... the rapidly growing diabetic retinopathy market. The IRIS ...
Breaking Biology News(10 mins):
(Date:2/8/2016)... Inc. (NYSE: DPLO) announced today that its new website has gone live. On Thursday, Feb. 4, ... Visit the new site: www.diplomat.is ... ... ... "The goal was to reimagine the website and create a smarter, ...
(Date:2/6/2016)... ... ... The Center for Excellence in Education (CEE) will sponsor a Bite of Science ... 2016. This Bite of Science session, hosted by the Smithsonian-Mason School of Conservation, ... in Front Royal, VA from 5:00 p.m. to 8:00 p.m. The dinner is for ...
(Date:2/5/2016)... ATCC, the premier global biological materials resource ... and life science researchers that are working to address ... CDC website . --> CDC ... a single-stranded RNA virus of the Flaviviridae family, genus ... Chikungunya Viruses. Zika virus is transmitted to humans primarily ...
(Date:2/5/2016)... 5, 2016 On Thursday, February 11, ... for community, health and disaster services, and the ... to enhance care coordination and service delivery for the ... need and to better connect service providers to the ... San Diego has handled more than ...
Breaking Biology Technology: