NEWS | IN DEPTH
California. “We think of them as the humming-
birds of the marine mammal world.”
In recent years, however, researchers in
Denmark, the Netherlands, and elsewhere
have shown that some porpoises can be cap-
tured and kept in captivity. Those advances
convinced Gulland that it was worth explor-
ing the strategy with the vaquita, and last
year she convened an expert team in the
Netherlands to assess the idea’s feasibility.
Each phase of the process would pose
challenges, the team concluded. Locating
the elusive cetaceans in the choppy, murky
waters of the gulf is tricky; the team even
suggested exploring the use of trained bottlenose dolphins, such as those kept by the U.S.
Navy, to help with the hunt. Once located, the
team envisions herding vaquitas into lightweight surface gillnets, which are safer than
conventional nets—a tactic that’s been used
to place satellite tags on harbor porpoises
in Greenland. Then, they would use a moist
stretcher to transport each animal to a soft-sided net pen, and likely later a large artificial
pool, along the gulf’s coast. There, they would
figure out how to feed and care for the animals, and attempt to persuade them to breed.
The ultimate goal would be to release some
parents and offspring back into the wild once
the threat of gillnets has been mitigated.
The first vaquita capture could occur in
2017, if further study supports the idea, a
recent CIRVA report notes. The likely first
target would be a young male, Gulland says,
because a loss in that demographic group
would be least harmful to the population if
things go awry.
WWF’s Vidal fears, however, that the
strategy could take the pressure off Mexican
authorities to crack down on illegal fishing.
“Species need to recover in the wild,” he adds.
Vidal notes that Mexico’s Guadalupe fur
seal, which was hunted nearly to extinction
in the 19th century, has rebounded without
CIRVA biologists acknowledge the strategy’s limitations. “There’s no point in putting
vaquitas into a sanctuary if they’re just going
to be killed once you release them,” Gulland
says. But they say capturing a few vaquitas—
rather than the entire population, as was
done with condors and ferrets—could provide an insurance policy against extinction.
If history is any guide, they’ll have to act
fast. In 2006, Taylor was on a team that
hoped to capture baiji, an endangered freshwater dolphin that lived in China’s Yangtze
River, and relocate the animals to protected
lakes. But it was too late: The researchers
never found any baiji, and the species was
declared functionally extinct. j
Ben Goldfarb is a freelance writer in New
Last September, in a move that took researchers by surprise, the National Institutes of Health (NIH) announced it would not fund controversial ex- periments that add human stem cells to animal embryos. Now, the agency
says it is ready to move forward with some
so-called chimera studies as long as they
pass a special agency ethics review. In a
draft policy released last week, NIH said it
will take an especially close look at studies
that add human cells to very early embryos
of certain animals or insert them into an
Biomedical scientists generally welcomed
the proposal, which could open the way to
growing human organs in animals or study-
ing human brain disease in monkeys. “I ap-
plaud the actions NIH is taking to advance
this area of research in a responsible and
timely manner,” says developmental bio-
logist Juan Carlos Izpisua Belmonte of the
Salk Institute for Biological Studies in San
Diego, California, whose application for a
prestigious NIH research award was put
on hold last fall because of the moratorium
on chimera studies. But some were left try-
ing to parse exactly what NIH’s policy will
mean. “We still don’t know what the out-
come will be case by case,” says Sean Wu,
a stem cell researcher at Stanford Uni-
versity in Palo Alto, California, who co-
authored a letter to Science last year oppos-
ing the moratorium.
At issue are experiments in which scientists introduce human pluripotent stem
cells—cells that can turn into any kind of
tissue—into early embryos of mice and
other laboratory animals and then let the
animals develop. Such experiments can be
used to study human development, generate disease models, and potentially grow
human organs and tissues for transplantation. Several scientists, including Izpisua
Belmonte, have already begun using non-NIH research funds to inject stem cells into
pig or sheep embryos, in an effort to grow
human pancreases or other organs inside
the animals. But the public has been leery
of such experiments, with some scientists
and ethicists worrying that they could produce an animal with humanlike cognitive
abilities or lead to a human embryo growing inside an animal. Several countries
already restrict this research by law (see
Responding to growing interest in us-
ing chimeras to produce human organs,
NIH decided last fall to suspend reviews of
new funding applications while the agency
NIH plans to fund human-
animal chimera research
Agency would subject experiments—such as growing
human organs in pigs—to extra ethical review
The legal landscape for chimera studies
Most countries don’t explicitly permit or forbid human-animal chimera research, but a few have relevant laws or
policies on funding for such work.
France Law forbids creating a chimeric human embryo, but is less clear on whether adding human
cells to animal embryos is allowed.
United Kingdom Regulations issued in January require extra ethical review for human-animal chimera
experiments that involve nonhuman primate cells, germ cells, or the brain, or that affect
an animal’s appearance or behavior.
Germany Law forbids combining a human embryo with animal cells, but not the introduction of
human cells into an animal embryo.
Japan Law limits research on human-animal chimeric embryos, not allowing development
beyond the appearance of the primitive streak or transfer into an animal. A bioethics
panel recently proposed more permissive, case-by-case review.
United States No legal prohibition, but advisory bodies have recommended limits on breeding chimeras
and adding human cells to primate embryos. After a funding pause, the National
Institutes of Health now proposes case-by-case review.
By Jocelyn Kaiser