DNA research: How's your zebrafish?
The Norman Transcript
April 25, 2006
Years after helping scientists around the world complete the Human Genome Project -- mapping the 23 sets of human chromosomes -- University of Oklahoma Professor Bruce Roe is leading a team to research DNA in chimpanzees, baboons and zebrafish.
Zebrafish?
Roe said a particular chromosome in zebrafish, a small, striped fish that grows up to 2 inches long, is remarkably similar to the one he studied for the human genome project.
"Ninety percent of genes in Chromosome 22 are in the zebrafish," he said. "And what takes us nine months to do (in the womb) takes zebrafish five days."
The work of Roe and other scientists will be celebrated today during National DNA Day, an annual event that started in 2003 to honor the 50th anniversary of the DNA double helix discovery.
Roe compares models of the DNA double helix to Christmas trees with many lights. There are more than 3 billion of those chemical building block bases, or "lights," in humans, grouped into about 25,000 genes within the 23 sets of chromosomes.
The OU professor was part of an international team that in 1999 became the first to completely map a human chromosome. It took $40 million and four years of collaboration among laboratories in England, Japan and Roe's in Oklahoma to sequence Chromosome 22.
The complete Human Genome Project was completed in 2003 by scientists in labs around the world.
It's a field that has fascinated Roe throughout his 35-year career, and one he said is relevant to every person.
"You want to know what the chemical basis for living systems is," Roe said. "Why do we look like our parents and grandparents; if my mother gets breast cancer and my grandmother had breast cancer, then why am I at risk?"
By mapping every human chromosome, scientists can look further into how and when genes work, what happens when they don't, and how to isolate and identify mutated ones. In other words, scientists are beginning to see which light bulbs have dimmed or burned out on the massive Christmas tree.
That, in turn, leads to knowing health risks well ahead of time along with developing medicines that target defective DNA traits.
"For cures based on the genome, the answer is no," Roe said. "But treatment of a disease if you take drug X, then the answer is yes."
Roe spoke of a man he knows with leukemia who is managing to live with the cancer. Thanks to scientists' knowledge of genes, he can take a "drug that specifically inhibits an altered gene protein."
"He still has leukemia," Roe said, "but he's free of symptoms."
The research also has early detection in overdrive. Blood samples taken a few years ago could be used for no more than a dozen genetic tests. Now, Roe said, the same sample can be used to test for more than 50 traits and conditions.
Genetic research continues in Oklahoma. After completing the Chromosome 22 work, Roe and his team studied DNA in mice for three years and have since moved on to the chimpanzees, baboons and zebrafish.
They're also studying alfalfa and soybean genetics for plant disease resistance, along with two fungi that infect many plants, from cotton to fruit trees to grasses.
About 60 students and lab technicians work with Roe, with students ranging from undergraduate to postdoctoral.
Hung-Chun "James" Yu, a doctoral student from Taiwan, was at his desk Friday looking intently at zebrafish DNA data while eating Italian food from a plastic dish. He couldn't wait to explain what it all meant.
In addition to their similarity to human genes, Yu said, studying zebrafish embryos has other advantages: they're both transparent and tiny, so they can be studied in their entirety under a microscope.
"I've always been interested in biology since high school, and biochemistry has become a hot topic," he said. "Since coming here, I've learned how powerful biochemistry can be."
Advancing equipment is a testament to that power. In 1995, the OU lab had machines that could sequence 20,000 DNA bases a day, and two years later it bought 14 machines that could process 200,000 of those "light bulbs" a day.
The university bought three machines in 2004 that sequenced 1 million bases in a day, but now it has a machine that can sequence 70 million bases in one day.
"In the last three weeks, we've sequenced six bacteria," Roe said. "Each has only 3 or 4 million bases, but you have to run it 20 times. They say make a list and check it twice, well, we check it 20 times.
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