International Study Reinforces Pig's Importance to Human Health Research

AMES, Iowa -- The first complete sequence of the pig genome by a team of researchers including Iowa State University animal scientists has provided a genetic comparison of the domesticated pig and its wild cousins and offers clues to how the animal evolved, according to an article in the journal Nature.

The study includes comparisons of the human, mouse, dog, horse, cow and pig genomes, which promises to expand the ways pigs are used in human health and medical research. The project found variants in 112 genes in the pig genome that were identical to variants implicated in human diseases, including aberrations associated with obesity, diabetes, dyslexia, Parkinson's disease and Alzheimer's disease, the researchers reported.

The article in Nature appears as the cover story of the Nov. 15 issue. Iowa State animal science professors Max Rothschild, James Reecy and Chris Tuggle contributed to the project conducted by the International Swine Genome Sequencing Consortium.

"This effort represents a truly international effort involving several American universities and many universities and research centers worldwide," said Rothschild, who serves as the U.S. Pig Genome Coordinator and is a member of the International Swine Genome Sequencing Consortium's steering committee. He and his team studied duplicated segments within the genome and their role in controlling traits.

"The sequencing of the pig genome is a milestone in a long process that started with man's domestication of the pig to produce food and offers new opportunities for animal geneticists to understand what genes do and what traits of economic importance they control to improve food production," he said.

The genome of the common farm pig was compared to the genetic makeup of 10 wild boars from locations in Europe and Asia. The genetic evidence found that the pig emerged in Southeast Asia, expanded into Europe and began being domesticated about 10,000 years ago.

The comparison with other mammals' genomes found a rapid evolution of genes in the pig associated with immune response and the sense of smell. Pigs, along with rats, have the greatest number of functional olfactory receptor genes possessed by any species reflecting the importance of smell in a scavenging animal.

Tuggle led the analysis of the genes involved in immune response, using the new pig genome sequence to locate and describe approximately 1,400 such genes. It was the largest effort of the project, and involved more than 40 scientists in six countries, including several undergraduates in his lab.

"The pig genome sequence provided us the tools to demonstrate that genes in the pig immune system are more similar to those in the human, in comparison with the genes found in the cow or mouse genomes," Tuggle said.

Reecy was part of the project's data analysis group that developed resources and mechanisms to easily share and move data between consortium members.

"With access to the pig genome sequence, researchers now have a scaffold with which to integrate information on nutrition, reproduction, meat science, growth and development, and basic biology, which will tremendously benefit production agriculture, as well as biomedical research," Reecy said.

In addition to the findings about the pig's genome that have impact for human medicine the results presented from the study could impact how we improve the pig as an important food animal species, Rothschild said.

Rothschild credited financial support from several sources, including the College of Agriculture and Life Sciences at Iowa State, the Iowa Pork Producers Association, the National Pork Board and the U.S. Department of Agriculture, for making the research possible.

More than 100 authors helped in this milestone event and included Lawrence Schook, University of Illinois vice president for research; Martien Groenen, a professor at Wageningen University in The Netherlands; and Alan Archibald, a professor of The Roslin Institute at the University of Edinburgh.