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Mar 27 2006
Researchers
Create Pigs that Produce Heart-Healthy Omega-3 Fatty Acids
COLUMBIA, Mo. -- Researchers report
they have created pigs that produce omega-3 fatty acids, which
are known to improve heart function and help reduce the risks for
heart disease, representing the first cloned, transgenic
livestock in the world that can make the beneficial compound. The
research could be a boost to both farmers and health-conscious
consumers seeking an alternative and safer source of omega-3
fatty acids. Currently, the only way for humans to realize the
benefits of omega-3 fatty acids is by taking dietary supplements
or by eating certain types of fish that also contain high levels
of mercury.
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Genetically
Altered Pigs
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The results, which are
being published by Nature Biotechnology, are the work of a team
assembled by Yifan Dai of the University of Pittsburgh School of
Medicine that includes researchers from Randy Prather's group at
the University of Missouri-Columbia National Swine Resource and
Research Center, the laboratory of Jing X. Kang at Massachusetts
General Hospital (MGH), and the laboratories of Dai and Rhobert
Evans at the University of Pittsburgh.
To stimulate
production of omega-3 fatty acids in pigs, a team led by Dai
transferred a gene, known as fat-1, to pig primary fetal
fibroblasts, the cells that give rise to connective tissue.
Prather's group then created the transgenic pigs from these cells
using a method called nuclear transfer cloning. The transgenic
pig tissues were then analyzed for omega-3 fatty acids in Kang's
lab at MGH and by Dai and Evans at Pitt. The fat-1 gene is
responsible for creating an enzyme that converts less desirable,
but more abundant, omega-6 fatty acids in the animals to omega-3
fatty acids. The results could lead to a better understanding of
cardiovascular function not only in pigs, but in humans as well.
"Pigs and humans have a similar physiology,"
said Prather, distinguished professor of reproductive biology in
Mizzou's College of Agriculture, Food and Natural Resources and a
corresponding author with Dai. "We could use these animals
as a model to see what happens to heart health if we increase the
omega-3 levels in the body. It could allow us to see how that
helps cardiovascular function. If these animals are put into the
food chain, there could be other potential benefits. First, the
pigs could have better cardiovascular function and therefore live
longer, which would limit livestock loss for farmers. Second,
they could be healthier animals for human consumption."
"While fish, especially salmon and tuna, is one of
the best food sources of omega-3 fatty acids, we have been warned
to limit consumption because of high mercury levels," said
Dai, an associate professor of surgery at the University of
Pittsburgh School of Medicine's Thomas E. Starzl Transplantation
Institute. "These animals could represent an alternative
source as well as be an ideal model for studying cardiovascular
disease and autoimmune disorders."
"Livestock
with a health ratio of omega-3 to omega-6 fatty acids may be a
promising way to re-balance the modern diet without relying
solely on diminishing fish supplies or supplements," Kang
said.
The transgenic pigs were created using technology
developed by Kang of MGH, an associate professor of medicine at
Harvard Medical School and co-lead author with MU's Liangxue Lai
of the current report. Kang's group created the first omega-3
rich mammals (mice) and published that work in Nature in 2004.
Because of this earlier study, Dai initiated the collaboration
with the aim of creating cloned transgenic pigs capable of making
omega-3 fatty acids.
The production of these pigs will
now provide researchers with opportunities to conduct studies not
previously possible. For example, researchers in MU's College of
Veterinary Medicine Department of Biomedical Sciences now plan to
study the omega-3 pigs. Harold Laughlin, chair of the MU
biomedical services department, uses pigs to study the
cardiovascular benefits of exercise because a pig's
cardiovascular system is similar to a human's. Now he plans to
incorporate these unique pigs into his research to determine how
higher omega-3 levels and exercise could affect the
cardiovascular system.
In addition to Prather and Lai at
MU, Kang at MGH and Dai and Evans at Pitt, other authors include
Rongfeng Li, Hwan Yul Yong, Yanhong Ho, David M. Wax, Clifton N.
Murphy, August Rieke, Melissa Samuel, Michael L. Lihville and
Scott W. Korte, all of MU; Jingdong Wang of MGH and Harvard
Medical School; and William T. Witt and Thomas E. Starzl, of the
University of Pittsburgh.
Their research was supported by
the National Institutes of Health, the American Cancer Society
and an unrestricted gift to the Thomas E. Starzl Transplantation
Institute from the Robert E. Eberly Program for Transplant
Innovation.
Source
/ Credit: University of Missouri / Columbia
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