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Philippe Psaila/SCIENCE SOURCE (EGG); Fernando G Baptista,/National Geographic Stock (bottom) U R became infection wiped all of them out. The brooding in the early 1980s, a fungal But soon after researchers discovered gastric- her mouth! developed, themotherburpedthemoutof her stomach.Whenthebabyfrogswerefully the eggswhole.Hertadpolesgrewinside once themalefertilizedthem,sheswallowed that at least some of them will survive and plants, there’s a better chance When an ecosystem has a wide variety of declined in many areas as species die off. reason is to increase California. “That’s plausible now.” Greely, a bioethicist at Stanford University in sloth—things our ancestors saw,” says Hank cat, or a woolly mammoth, or a giant ground species that have been extinct much longer. resurrect the baby-burping , as well as the artificial manipulation of living things—to Scientists are trying to use brooding frog may come back to life. eviving a a eviving from a frozen carcass. frozen a from cell mammoth viable How to Make a species back from extinction. from back species This strange species fascinated scientists. Why bring back extinct species? One Now, three decades later, the gastric- “Just imagine looking at a saber-toothed 1 cientists may be able to use a frozen cell from a mammoth that’s been dead for thousands of years to bring the bring to years of thousands for dead been that’s mammoth a from cell frozen a use to able be may Scientists nucleus of a of nucleus the Isolate extinct. female laidhereggsinwater, and thing aboutthisfrogwasthatthe gastric-brooding frog.Thestrange to averyoddamphibian:the ntil the1980s,Australiawashome S pecies mammoth nucles , which has biotechnology— mammoth nucleus. mammoth the with it replace and elephant an of egg 2 n elephant—the mammoth’s closest living relative—would carry the baby clone. baby the carry relative—would living closest mammoth’s elephant—the An nucleus from the the from nucleus the Remove

elephant egg and the DNA inside its nuclei begins to break when an dies, its cells decompose years ( identical copies, of those animals for many living animals to create determines an animal’s traits. carries the hereditary information that contain an organism’s intact 5 years ago, the first thing he needed was an the gastric-brooding frog. leading the team that’s trying to bring back of New South Wales in Australia. Archer is Archer, a paleontologist at the University and diversity of the natural world,” says Mike focused on trying to increase the complexity climate change. natural disasters, disease outbreaks, or WOO genetic material genetic injecting pipette A Scientists have been using nuclei from When Archer set out to revive the frog “All of these ‘de-extinction’ projects are EGG it begin dividing. begin it make to cell the stimulate cally 3 nucleus from one of its cells. Nuclei see Cloning Timeline, p. 10). But or electri- or Chemically LLY Mamm DNA. This chemical clones, or genetically years to develop. to years two almost take will of an elephant. an of 4 egg in place in egg the holding pipette A www.scholastic.com/scienceworld in the uterus the in egg the Place

It ot to a baby mammoth. baby a to birth gives elephant the successful, is 5 Transfer: clone. a create to material genetic with egg an injects researcher a microscope, a h www.scholastic.com www.scholastic.com

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9 something else: inserting buried mammoth fossils scientists working on the cell nucleus of the and, in a few cases, the these projects should extinct frog into the egg of frigid conditions have be very careful. Many of another species. He started helped preserve some the environments that collecting eggs laid by great DNA. A group of South extinct species once barred frogs, a common Korean and Russian inhabited have changed species in Australia. researchers hopes to use since they lived there, Over the next few years, this material to bring he says. If a long-gone Archer’s team injected thou- mammoths back to life species is reintroduced, sands of one day (see How to it could become an eggs with gastric-brooding Make a Woolly COMING BACK? The gastric- invasive species that brooding frog, now extinct, frog nuclei. None of them Mammoth, p. 9). birthed babies through its mouth. upsets the current grew. But the researchers Ben Novak, a biolo- ecosystem. kept trying and adjusting gist at the University GONE FOR NOW: Some conservation- their technique. of California, Santa Passenger pigeons ists also worry that if were hunted to Finally, about two years Cruz, wants to use extinction in the 1800s. scientists can bring ago, one of the eggs started genetic techniques to extinct animals back, dividing. When Archer tested bring back the extinct no one will care about the growing ball of cells, or passenger pigeon. These keeping endangered embryo, he found gastric- sleek, gray-blue birds species from becoming brooding frog DNA inside. used to flock over the extinct in the first place. “That told us that the Northeastern U.S. in “If this were to MAMMOTH down. This makes cloning an extinct species extinct animal’s DNA was driving the devel- groups of a billion or undercut efforts to MUMMY: This baby o mm on s (2009) mammoth’s body, much harder than cloning a living one. opment of a new frog,” he says. more. But by the late conserve currently discovered under Luckily, back in the 1970s, another 1800s, they had been existing species, that Core permafrost in W ikimedia C Siberia in 2007, scientist had frozen some gastric-brooding De-Extinction Plans hunted to extinction by trappers who sold would be a tragedy,” says Greely. Question still had some DNA frog tissue and saved it. Archer examined So far, none of the eggs have grown past them for people to eat. Bringing them back Archer doesn’t think that will happen. In inside. cells from the frozen sample and was excited the embryo stage into baby frogs. Archer and would help restore biodiversity to the forest fact, he says, the cloning techniques scientists Should scientists

to find that their nuclei appeared intact. his colleagues aren’t sure why. But if they can D ie go Z oo (2003); ecosystems in which they lived, says Novak. develop to bring back extinct species could try to bring back

The next step was to find an egg. In solve that problem, says Archer, “I’m hopeful S a n be used to breed endangered animals too. extinct species? traditional cloning, scientists take an egg that within a few years we should have this Ethical Concerns Many of the species scientists want to Cite evidence cell from a female of the same species and frog back.” Technology may have made it possible bring back became extinct because people from the article remove its nucleus. Then they replace it with Archer’s attempt is the farthest along, but to bring back extinct species. But does that hunted them or ruined their habitats, argues to support your the nucleus of a regular cell from the body other teams of scientists want to use similar mean it’s a good idea? Archer. Humans even helped spread the opinion. of the individual they want to clone. When techniques to bring back other extinct R ST New/Re u te r s (2001); Hank Greely, the Stanford bioethicist, fungus that killed off gastric-brooding frogs. the egg starts to divide, the new cells contain species, like the woolly mammoth. These studies the ethical implications of technolo- “They shouldn’t be gone, and we did copies of the donor animal’s DNA. hairy relatives of elephants roamed the frozen gies like cloning. He thinks de-extinction it,” says Archer. “I think we have a moral

But no one had saved any gastric-brooding tundra of Siberia until they died out about E S OURC ( p i g e on ); has many potential benefits, including responsibility to try to fix what we broke.” frog eggs. That meant Archer had to try 5,000 years ago. Scientists have found many helping ecosystems recover. But Greely says —Mara Grunbaum hell U K /Re u te r s (1996) c M it k/ S C IE NC E coc ay L k (1952); Je ff k J (1952);

cloning oc

TIMELINE T hi n kst Scientists first cloned op );

animals more than 60 E ); e S OURC ( frog Ge org g es (t

years ago. Since then, 1952 1996 I ma 2001 2003 2009

breakthroughs in cloning Scientists create the first cloned animal—a Dolly the sheep, the first mammal cloned y/ S C IE NC E Researchers clone the first domestic Cells from a dead banteng, a type of Scientists report that they used frozen technology have brought

tadpole—by extracting a cell nucleus from using the body cell of an adult animal, is L i br a r cat. The kitten is named CC, for “Copy wild Asian cattle, produce a healthy cells to clone the bucardo, an extinct o

them closer to being able t A FP/Gettyo sti/

a developing embryo and inserting it into born in Scotland. Dolly becomes famous v Cat.” Some companies begin offering cloned calf—raising hope that cloning Spanish goat. But the clone, born with to revive extinct species. an egg that has had its nucleus removed. and brings lots of attention to cloning. to clone pets—but it’s very expensive. can help save endangered species. lung defects, lived only seven minutes. A N T Ph o Ria N o

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