Scientists Devise Clever Way to Test Old Manuscripts’ DNA

Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0
Jim Forest, Flickr Creative Commons // CC BY-NC-ND 2.0

When encountering an obstacle, some people stop and give up, some force their way through, and others find another way around. That's what scientists in the United Kingdom have done with a delicate manuscript from the Dark Ages. Barred from taking parchment samples, the resourceful researchers instead analyzed the eraser crumbs left behind after archivists cleaned the paper. They describe their findings in an article on the prepress server bioRxiv.

Co-author and archaeologist Matthew Collins of the University of York did not start out a manuscript man. Collins had been trying to extract DNA from animal bones unearthed at a Viking settlement to learn more about the culture's use of livestock. But the bones had decayed too far to offer much in the way of genetic material. "You can imagine the frustration," Collins said in an interview with The Atlantic.

Then he realized that animal remains can be more than just bones. There are skins, too—and those, at least, we've taken some pains to preserve. At least the ones we've written on.

"You look at [archive] shelves," Collins said, "and every one of them has a skin of an animal with a date written on it."

Collins's excitement at discovering this untapped bounty of data was soon tempered when he and his collaborator, biochemist Sarah Fiddyment, learned that sampling the manuscripts was completely off-limits.

But they weren't about to give up that easily. Fiddyment spent weeks following the conservators as they worked with the fragile animal-skin paper, learning their process and watching for possible openings. Finally, she saw it: eraser crumbs.

Conservators routinely use PVC erasers to lift stains, grime, and damage from historic documents. The friction created by gently rubbing the eraser against the paper creates an electric charge that pulls in molecules of dirt and oil. And probably other things, too, Fiddyment thought.

Fiddyment, Collins, and their colleagues began collecting eraser crumbs from manuscript conservators around the world. They analyzed each document's chemical makeup and were even able to compare proteins to identify the livestock species responsible for the skin.

The next step was to look at the DNA itself. The researchers turned to the York Gospels, a leatherbound Bible with pages dating back to the year 990. By collecting another tiny pile of eraser crumbs from cleanup of eight pages, they were able to collect enough of a sample to run thorough DNA tests.

Those pages had quite a lot to say about their creation and history. The tests revealed 1000-year-old genetic material from the cows and sheep that gave the book its parchment pages. Remarkably, the DNA was so intact that the scientists could identify the cows' ancestry (something close to our modern-day Norwegian reds and Holsteins) and sex (mostly female).

The pages also contained human DNA and even bacteria, most likely from the hands and saliva of the people who made, wrote, and used the book.

Speaking to The Atlantic, parchment expert Bruce Holsinger of the University of Virginia called the findings "an exciting breakthrough."

[h/t The Atlantic]

A Simple Skin Swab Could Soon Identify People at Risk for Parkinson's

iStock.com/stevanovicigor
iStock.com/stevanovicigor

More than 200 years have passed since physician James Parkinson first identified the degenerative neurological disorder that bears his name. Over five million people worldwide suffer from Parkinson’s disease, a neurological condition characterized by muscle tremors and other symptoms. Diagnosis is based on those symptoms rather than blood tests, brain imaging, or any other laboratory evidence.

Now, science may be close to a simple and non-invasive method for diagnosing the disease based on a waxy substance called sebum, which people secrete through their skin. And it’s thanks to a woman with the unique ability to sniff out differences in the sebum of those with Parkinson's—years before a diagnosis can be made.

The Guardian describes how researchers at the University of Manchester partnered with a nurse named Joy Milne, a "super smeller" who can detect a unique odor emanating from Parkinson's patients that is unnoticeable to most people. Working with Tilo Kunath, a neurobiologist at Edinburgh University, Milne and the researchers pinpointed the strongest odor coming from the patients' upper backs, where sebum-emitting pores are concentrated.

For a new study in the journal ACS Central Science, the researchers analyzed skin swabs from 64 Parkinson's and non-Parkinson's subjects and found that three substances—eicosane, hippuric acid, and octadecanal—were present in higher concentrations in the Parkinson’s patients. One substance, perillic aldehyde, was lower. Milne confirmed that these swabs bore the distinct, musky odor associated with Parkinson’s patients.

Researchers also found no difference between patients who took drugs to control symptoms and those who did not, meaning that drug metabolites had no influence on the odor or compounds.

The next step will be to swab a a much larger cohort of Parkinson’s patients and healthy volunteers to see if the results are consistent and reliable. If these compounds are able to accurately identify Parkinson’s, researchers are optimistic that it could lead to earlier diagnosis and more effective interventions.

[h/t The Guardian]

World’s Oldest Stored Sperm Has Produced Some Healthy Baby Sheep

A stock photo of a lamb
A stock photo of a lamb
iStock.com/ananaline

It’s not every day that you stumble across a 50-year-old batch of frozen sheep sperm. So when Australian researchers rediscovered a wriggly little time capsule that had been left behind by an earlier researcher, they did the obvious: they tried to create some lambs. As Smithsonian reports, they pulled it off, too.

The semen, which came from several prize rams, had been frozen in 1968 by Dr. Steve Salamon, a sheep researcher from the University of Sydney. After bringing the sample out of storage, researchers thawed it out and conducted a few lab tests. They determined that its viability and DNA integrity were still intact, so they decided to put it to the ultimate test: Would it get a sheep pregnant? The sperm was artificially inseminated into 56 Merino ewes, and lo and behold, 34 of them became pregnant and gave birth to healthy lambs.

Of course, this experiment wasn’t just for fun. They wanted to test whether decades-old sperm—frozen in liquid nitrogen at -320°F—would still be viable for breeding purposes. Remarkably, the older sperm had a slightly higher pregnancy rate (61 percent) than sheep sperm that had been frozen for 12 months and used to impregnate ewes in a different experiment (in that case, the success rate was 59 percent).

“We believe this is the oldest viable stored semen of any species in the world and definitely the oldest sperm used to produce offspring,” researcher Dr. Jessica Rickard said in a statement.

Researchers say this experiment also lets them assess the genetic progress of selective breeding over the last five decades. “In that time, we’ve been trying to make better, more productive sheep [for the wool industry],” associate professor Simon de Graaf said. “This gives us a resource to benchmark and compare.”

[h/t Smithsonian]

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