December 15, 2017

 

 Modified pigs better at enduring cold, according to study

Posted Nov. 29, 2017

Researchers in China used gene editing to create pigs that are better at maintaining body temperatures early in life and leaner as adults.

The change could reduce neonatal deaths of piglets from hypothermia, improve animal welfare, and improve production, according to a scientific article published online Oct. 23 in the Proceedings of the National Academy of Sciences. The abstract for the article, "Reconstitution of UCP1 using CRISPR/Cas9 in the white adipose tissue of pigs decreases fat deposition and improves thermogenic capacity," is available at http://jav.ma/UCP1pigs.

The research team added a mouse protein gene, uncoupling protein 1, to the swine genome. In most mammals, the UCP1 protein leaks protons across the inner mitochondrial membrane of brown adipose tissue cells, dissipating energy as heat.

​Using a mouse protein gene, Chinese researchers created pigs that are less prone to hypothermia at the neonatal stage and leaner as adults. (Photo by Jianguo Zhao, PhD)

Ancestors of modern pigs lived in tropical and subtropical climates and lost their functioning version of the UCP1 protein about 20 million years ago, the article authors wrote, citing genetic analysis published in 2006 (PLoS Genet 2006;2:e129). Pigs lack functional brown adipose tissue because of the UCP1 gene disruption, but the researchers were able to edit the swine genome with a mouse gene in a porcine UCP1 pseudogene locus.

The modified pigs maintained body temperatures better than nonmodified pigs did during acute cold exposure. They also had more lean meat without changes in physical activity or food demands, the article states.

The gene expression decreased fat deposition by about 5 percent. The authors also wrote that the tendency of pigs to accumulate fat may be related to their lack of the UCP1 gene and their susceptibility to cold.