While it's easy to see that pigs and humans are very different, beneath the skin are striking similarities, researchers at the University of Illinois are finding.
The researchers say their work comparing the two species' genomes, or DNA maps, eventually could give medical researchers information they need to develop treatments for clogged arteries, cancer or other human diseases.
"When we look at the DNA sequence, we're a lot alike," said Jonathan Beever, an animal geneticist at the university's Urbana-Champaign campus who spent nearly two years compiling the genome comparison with UI colleague Lawrence Schook and graduate student Stacey Meyers. "The pig is just a spectacular model for humans."
A genome is the complete set of genetic instructions for making an organism - a master plan of sorts. The components of that plan, genes, are carried on DNA molecules that organize themselves into chromosomes, according to a primer on genetics published by the Human Genome Project.
A side-by-side comparison shows at least 173 places on pig and human chromosomes where the genes match, Beever said.
It is not unusual for mammals to have identical genes. But the same gene might work with other genes to control something very different in a pig than in a human, and learning where each gene lies on the genome should help determine what role it plays in the animal's makeup, Schook said.
The new comparative map gets researchers closer to that goal, he said, comparing the progress to reading a book.
"If you look at where we've been before, we were happy if we were breaking down into book chapters," he said. "Now we're getting to sentences. The next step is to go to words and letters."
The map provides a starting point for researchers who, until now, have had to "hunt and peck" to find matching genes, said Gary Rohrer, a geneticist with the USDA's Meat Animal Research Center in Clay Center, Neb. "Rather than having to write the book, you can read the book and find the answer out," he said.
Those answers could help researchers understand and treat diseases of both species because genetic diseases might look the same in a pig as in a human, Schook said.
For instance, side-by-side comparison of a gene that predisposes a person to develop cardiovascular plaque would allow researchers to look at the variation that contributes to the disease and compare it to the same genetic sequence in the pig and test treatments, he said.
"You can do radiation therapies and other treatments that are difficult to use in smaller animals," Schook said.
The next step, or getting to the "words and letters" described by Schook, is determining how genes line up on each DNA molecule in the swine genome, a process called sequencing. Schook and Beever hope to begin that work within six months, Schook said.
Sequencing of the human genome was completed in 2003, and the first draft of the bovine, or cow, genome was finished last year.
The swine genome sequencing project will be led from the University of Illinois working with the Sanger Institute, a genomic research center in England, Schook said.
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