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
|Contact: Kelly Dawe|
University of Georgia