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When Pig Genomes Fly

11/14/2012
Sarah C.P. Williams

The genomes of a dozen pig species reveal the intricacies of hog evolution as well as pigs’ similarities with humans that may prove useful for biomedical research.


The genomes of a dozen pig species—from commercially bred animals to wild boars—have for the first time been fully sequenced. The complete genomes offer insight into how pigs have evolved over the past million years and what genes are most similar to their human counterparts.

Pig genomes help explain diversity within the species. Credit: Don Hamerman





The members of the International Swine Genome Sequencing Consortium from around the world sequenced the genomes of 50 individual pigs. In the past, only portions of these genomes have been sequenced. From this data, researchers mapped out about 60,000 single nucleotide polymorphisms (SNPs) and designed a SNP chip that’s been in use for the past few years. But the full genomes, published November 14 in Nature (1), offer new information.

“Firstly, for agriculture and animal breeding purposes, this is very important,” said study author Martien Groenen of Wageningen University in The Netherlands. Researchers can now identify genetic variations between commercial pig species that can affect health and disease resistance.

In addition, the data sheds light on pig evolution. “You can trace back roughly one million years to when the Asian and European boar split,” said Groenen. But in the 18th and 19th century, breeders in Europe began importing Asian breeds to mix with their pigs. “We were surprised by the amount of Chinese genetic material still present in European breeds,” he said.

And researchers found some specific genes that are unique in pigs. For example, the genus has the largest number of olfactory receptor genes of any animal with a sequenced genome, which explains the pig’s sensitive sense of smell and ability to seek out things like truffles. Their taste receptors, however, have had additions over time making them weaker, which is one reason pigs can tolerate food that humans find unappealing.

The pig genomes also give an understanding of how pigs can become even better models for human health. Already, pigs are used as models for human hearts and cardiovascular systems. Their physiology and organ size is more similar to humans than most animals.

“What was interesting is that you can find several positions which seem to be fixed in pigs which correlate to disease genes in humans,” said Groenen. Specifically, the team found 112 amino acids that are the same as ones implicated in human disease, including risk factors for diabetes, obesity, dyslexia, and Alzheimer’s disease.

“We can now start to look at variation between pigs in these genes,” said Groenen. “If you find variation in pigs similar to the variation in humans, that can help us study complex diseases like diabetes.” His team is already planning the analysis of 70 more pigs.

References

  1. Groenen MAM, Archibald AL, Uenishl H, Tuggle CK, et al. 2012. Analysis of pig genome provide insight into porcine demography and evolution. Nature 491:393-397

Keywords:  sequencing pig genomics