Navigation Links
UGA researchers propose model for disorders caused by improper transmission of chromosomes

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
University of Georgia

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:
(Date:5/23/2017)... 2017  Hunova, the first robotic gym for the rehabilitation and functional ... in Genoa, Italy . The first 30 robots will ... USA . The technology was developed and patented at ... IIT spin-off Movendo Technology thanks to a 10 million euro investment from ... click: ...
(Date:5/16/2017)... --  Bridge Patient Portal , an enterprise patient ... Systems , an electronic medical record solutions developer ... a partnership to build an interface between the ... products, including Centricity Practice Solution (CPS), Centricity Business ... integrations will allow healthcare delivery networks using GE ...
(Date:4/24/2017)... WASHINGTON , April 24, 2017 ... counsel and partner with  Identity Strategy Partners, LLP ... "With or without President Trump,s March 6, ... Foreign Terrorist Entry , refugee vetting can be instilled ... refugee resettlement. (Right now, all refugee applications are ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... DuPont Pioneer and recently ... have entered into a multiyear collaboration to identify and characterize novel CRISPR-Cas nucleases. ... for gene editing across all applications. , Under the terms of the agreement, ...
(Date:10/12/2017)... ... , ... AMRI, a global contract research, development and manufacturing ... and quality of life, will now be offering its impurity solutions as a ... requirements for all new drug products, including the finalization of ICH M7 earlier ...
(Date:10/11/2017)... ... October 11, 2017 , ... The CRISPR-Cas9 ... enabling overexpression experiments and avoiding the use of exogenous expression plasmids. The simplicity ... for performing systematic gain-of-function studies. , This complement to loss-of-function studies, such ...
(Date:10/11/2017)... ... October 11, 2017 , ... Proscia Inc ., ... a Webinar titled, “Pathology is going digital. Is your lab ready?” with Dr. ... best practices and how Proscia improves lab economics and realizes an increase in ...
Breaking Biology Technology: