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Scientists Create "Low-Fat" Pigs Using CRISPR

posted by martyb on Tuesday October 24 2017, @09:30PM   
from the CRISPR-y-bacon dept.

takyon writes:

Scientists at the Chinese Academy of Sciences have used the CRISPR gene editing technique to create pigs with less body fat. The GMO pigs may be better from both a cost and animal welfare standpoint:

Here's something that may sound like a contradiction in terms: low-fat pigs. But that's exactly what Chinese scientists have created using new genetic engineering techniques.

In a paper [DOI: 10.1073/pnas.1707853114] [DX] published Monday in the Proceedings of the National Academy of Sciences, the scientists report that they have created 12 healthy pigs with about 24 percent less body fat than normal pigs.

The scientists created low-fat pigs in the hopes of providing pig farmers with animals that would be less expensive to raise and would suffer less in cold weather. "This is a big issue for the pig industry," says Jianguo Zhao of the Institute of Zoology at the Chinese Academy of Sciences in Beijing, who led the research. "It's pretty exciting."

[...] The animals have less body fat because they have a gene that allows them to regulate their body temperatures better by burning fat. That could save farmers millions of dollars in heating and feeding costs, as well as prevent millions of piglets from suffering and dying in cold weather. "They could maintain their body temperature much better, which means that they could survive better in the cold weather," Zhao said in an interview.

Previously: "Double-Muscled" Pigs Created Using Simple Gene Modification
eGenesis Bio Removes PERV From Pigs Using CRISPR
PETA Claims That Cambodian Farmers Are Breeding "Double-Muscled" Mutant Pigs

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Original Submission

• Much better, but how efficient (Score: 0) by Anonymous Coward on Wednesday October 25 2017, @06:57PM

  by Anonymous Coward on Wednesday October 25 2017, @06:57PM (#587493)

  Usually I comment on these with the idea that instead of "editing", pre-existing mutants were selected (mostly this is a problem with the KO NHEJ studies). This doesn't seem plausible here since they properly sequenced across the splice junctions. I couldn't totally check the results without the plasmid sequence but I'll accept it.

  However, the main claim to fame for CRISPR is efficiently doing this. I don't think they showed any efficiency here. They say:

  Here, we report application of a CRISPR/Cas9-mediated, homologous recombination (HR)-independent approach to efficiently insert mouse adiponectin-UCP1 into the porcine endogenous UCP1 locus.
  [...]
  Three of 26 cell colonies were identified as positive for forward integration (11.54%)

  This 11% value is what they are calling "efficient". I'll allow that 11% could be considered efficient, but this calculation for 26 colonies out of how many original cells? It sounds like they started with multiple 96-well plates (ie many more cells than 26):

  Primary pig PEFs were isolated as previously reported (60). Cas9-gRNA plasmids were cotransfected into cultured PEF cells by nucleofection. Forty-eight hours after transfection, cells were harvested using 0.25% trypsin/EDTA (Gibco), and the cell density was calculated using a handheld automated cell counter (Millipore). Single cells were plated in each well of 96-well plates by limiting dilution and cultured for ∼10 d in cell culture medium supplemented with 2.5 ng/mL basic fibroblast growth factor (Sigma). The medium was replaced every 4 d. Confluent cell colonies were propagated and genotyped by PCR and sequencing.

  So it is actually 3/N, where N is however many cells they started with. Just looking at the 26 plates that grew to confluence is not the right way to judge the efficiency of the process.