Friday, August 28, 2009

Research duo finds cause for disorders



Issue date: 8/28/09
A University professor and graduate student pinpointed a cause of chromosome defects in corn - a major agricultural breakthrough that may further scientific understanding of chromosome disorders such as Down syndrome in humans.

Plant biology professor Kelly Dawe and recently graduated doctoral student Xuexian Li led the research, both spending years on the project, Dawe said.

"This project was one of my ideas I had in my first grant proposal," he said. "It took a while to organize the tools, methods and people."

The pair's hard work paid off, and the research was featured in the advance online publication of the journal Nature Cell Biology this month.

In the study, Dawe and Li found that the loss or degradation of key proteins found in the kinetochore - a protein structure that pulls chromosomes apart - can increase the chance of chromosomes not dividing correctly during meiosis.

Meiosis is the process by which a cell halves the number of chromosomes from 46 to 23 to divide and create sperm and egg sex cells. The final stages of chromosome separation may not happen correctly if the egg is fertilized later in life, Dawe said.

Other researchers are intrigued by the overall implications of the study as well.

"These findings provide new directions on how to conduct similar research in mammals," said Patricia Hunt, Washington State University professor and specialist in reproductive biology and meiosis. "We're riding on the coattails of researchers like Kelly [Dawe] with these big discoveries."

Hunt said Dawe and Li's developments provide new information about the first stage of meiotic division - a complex process scientists are working to understand better.

Since Hunt's interest is in human models, she said analyzing similar structures in human eggs in vitro (examined outside of the body in a laboratory setting) can further enhance researchers' understanding of how some individuals end up with too few or too many chromosome copies.

"These problems arise in the egg. Approximately 10 percent of human pregnancies are chromosomally-abnormal," Hunt said in a telephone interview Tuesday.

"By the time a woman is in her 40s, around half of her eggs are chromosomally-abnormal."

Because women carry their eggs from birth, Dawe and Hunt said eggs degrade and sometimes fail to function properly, much like other aging cells.

Above all, Dawe and Li's research directly influences genetic engineering in agriculture and corn production.

"The research helps to achieve my goal of creating an 'artificial chromosome vector' for crop improvement - a method of adding traits to crops in novel ways," Dawe said. "The idea is to identify all the pieces of a normal chromosome, and then to reconstruct them in a small chromosome that can carry genes of interest."

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