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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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A Fruitful Scoop for Ancient DNA
16 July 1998 6:30 pm
In the movie Jurassic Park, a collector snapped up hundreds of thousands of mosquitoes preserved in amber for DNA they had sucked from dinosaurs. In the real world, however, amber has yielded no reproducible traces of ancient genetic material. Now researchers report in tomorrow's Science that the treasure of ancient DNA can instead be gleaned from a less glamorous material: fossil feces. Such droppings may be able to provide a wealth of clues about the ecology and relationships of extinct animals--and perhaps even about early humans.
Last year geneticist Svante Pääbo of the University of Munich and his colleagues made headlines when they extracted DNA from a Neandertal bone (Science, 11 July 1997, p. 176). But the team hadn't been having any luck with the well-preserved samples of fossilized dung, called coprolites, left by an extinct ground sloth about 20,000 years ago in Gypsum Cave near Las Vegas, Nevada. The problem seemed to be Maillard products--sugar-rich tangles of proteins and nucleic acids that prevent DNA amplification.
Then the team heard about a chemical called N-phenacylthiazolium bromide (PTB), which cleaves the same kind of bonds that may entangle DNA in the Maillard products. Extracts from the sloth coprolite treated with PTB yielded sequences of mitochondrial DNA, presumably from intestinal cells shed into the feces. The team also snagged a wide variety of plant DNA from the coprolite--clues to the vegetarian sloth's diet. They identified sequences from eight plant families, including grasses, yucca, grapes, and mint. DNA analysis may help identify plants chewed beyond recognition, says molecular biologist Hendrik Poinar.
Still, some paleontologists caution that DNA from dung may not reveal everything its proponents hope for. Changes in coprolite contents could simply reflect seasonal shifts rather than pointing to causes of extinction, says Russ Graham, a paleontologist at the Denver Museum of Natural History. The technique may not work on coprolites found in warmer or wetter conditions, or on very ancient samples, as most DNA is thought to degrade within 100,000 years, says Poinar. Despite such caveats, "I'm gathering as much poop as I can," Poinar says. "There's going to be a run on feces."