DNA From a Shark Tooth Embedded in a Man's Foot for 25 Years Identifies the Culprit

Blacktip shark
Blacktip shark
Sahil Miyani, iStock / Getty Images Plus

It was unclear what species of shark attacked Jeff Weakley while he was surfing off Flagler Beach, Florida in 1994. Whether it was a tiger shark, bull shark, great white shark, or some other predator didn't matter at the time—his priority was swimming to safety before the shark could take another bite.

Twenty-five years later, the wound on Weakley's right foot has healed, and he's had plenty of time to wonder what exactly bit him on that beach trip. By analyzing a tooth fragment that was lodged in his foot for more than two decades, a team of scientists has finally given him an answer, the Ocala StarBanner reports.

Bits of shark tooth have come loose from Weakley's foot several times since he was attacked in 1994. The third time it happened, in fall 2018, he collected the shard and sent it to the Florida Program for Shark Research, a part of the Florida Museum of Natural History in Gainesville. He had just read an article about the program's work identifying shark species using the DNA from their teeth, and he suspected the team might be able to do the same with his tooth fragment.

His hunch was correct: The scientists analyzed the sample and confirmed that the shark that had bit Weakley a quarter-century earlier had been a blacktip shark (Carcharhinus limbatus). That finding was made possible by years of hard work. Over more than two decades, the program has amassed a database of shark DNA containing reference samples for roughly 70 percent of all known shark, skate, ray, and chimera species. Luck was also on their side: The researchers had feared that Weakley's immune system would have destroyed any DNA in the shark's tooth, but when it arrived at the lab, there was enough to make the identification.

Shark attacks are common in movies and TV, but much less so in real life. You're more likely to be struck by lighting or die from the flu than be the victim of a shark attack. When sharks do bite humans, it's often because they've mistaken them for a prey animal, and they'll usually let the victim go once they've realized their error. This is likely how Weakley escaped his shark attack with his foot mostly intact.

[h/t Ocala StarBanner]

Here’s What You Need to Know About the New Coronavirus

jarun011/iStock via Getty Images
jarun011/iStock via Getty Images

This morning, the Centers for Disease Control and Prevention (CDC) confirmed the second case of the recently discovered coronavirus in the U.S. Find out what it is, where it is, how to avoid it, and all the other need-to-know information about the illness below.

What is the new coronavirus?

Coronaviruses are a group of viruses named for the crown-shaped spikes that cover their surfaces (corona is the Latin word for crown). According to the CDC, human coronaviruses can cause upper-respiratory tract illnesses, including the common cold, and can sometimes lead to more severe lower-respiratory tract issues like pneumonia or bronchitis.

Because this latest coronavirus, 2019-nCoV, is so new, health officials are currently trying to figure out how it works and how to treat it. It’s not the first time a potent new coronavirus has caused an international outbreak: SARS-CoV originated in Asia and spread to more than two dozen countries in 2003, and MERS-CoV first infected people in Saudi Arabia before spreading across the globe in 2012.

Where is the coronavirus outbreak happening?

The majority of cases are in China, which counts more than 800 confirmed diagnoses. Most are in Wuhan, a city in China’s Hubei province where 2019-nCoV was first detected last month. Additional cases have been reported in South Korea, Japan, Singapore, Hong Kong, Macao, Taiwan, Thailand, and Vietnam.

The CDC has confirmed two U.S. cases—a man in his thirties outside Seattle, and a 60-year-old woman in Chicago—both of whom had recently returned from trips to Wuhan. A CDC official said another 63 potential cases are being investigated in 22 states, and airports in New York, Chicago, Los Angeles, Atlanta, and San Francisco are conducting health screenings on passengers arriving from China.

Chinese officials have shut down transportation to and from Wuhan. Tourist spots like Beijing’s Forbidden City, Shanghai Disneyland, and a portion of the Great Wall are also closed temporarily.

What are the symptoms of the new coronavirus?

Symptoms are similar to those caused by a cold or the flu, including fever, dry cough, and breathing difficulty. The New York Times reported that as of Friday morning, 25 people in China have died from the virus, and most of them were older men with preexisting health conditions like cirrhosis, diabetes, and Parkinson’s disease.

How does the new coronavirus spread?

Because most of the early cases of 2019-nCoV were traced back to a seafood and meat market in Wuhan, health officials think the virus originally spread from infected animals to humans, but it’s now being transmitted from person to person.

Though scientists are still studying exactly how that happens, the leading theory is that it travels in tiny droplets of fluid from the respiratory tract when a person coughs or sneezes.

How do you avoid the new coronavirus?

The CDC is warning everyone to avoid any nonessential trips to Wuhan, and to avoid animals or sick people if you’re traveling elsewhere in China. If you’ve been to China in the last two weeks and experience any of the symptoms listed above, you should seek medical attention immediately—and you should call the doctor’s office or emergency room beforehand to let them know you’re coming.

Otherwise, simply stick to the precautions you’d normally take when trying to stay healthy: Wash your hands often with soap and water, cover your nose and mouth when coughing or sneezing, stay away from sick people, and thoroughly cook any meat or eggs before eating them.

Should you be worried about the new coronavirus?

The global health community is taking 2019-nCoV seriously in order to curb the outbreak as quickly as possible, but you shouldn’t panic. The CDC maintains that it’s a low-risk situation in the U.S., and public health officials are echoing that message.

“We don’t want the American public to be worried about this, because their risk is low,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told USA Today.

[h/t USA Today]

Has An Element Ever Been Removed From the Periodic Table?

lucadp/iStock via Getty Images
lucadp/iStock via Getty Images

Barry Gehm:

Yes, didymium, or Di. It was discovered by Carl Mosander in 1841, and he named it didymium from the Greek word didymos, meaning twin, because it was almost identical to lanthanum in its properties. In 1879, a French chemist showed that Mosander’s didymium contained samarium as well as an unknown element. In 1885, Carl von Weisbach showed that the unknown element was actually two elements, which he isolated and named praseodidymium and neodidymium (although the di syllable was soon dropped). Ironically, the twin turned out to be twins.

The term didymium filter is still used to refer to welding glasses colored with a mixture of neodymium and praseodymium oxides.

One might cite as other examples various claims to have created/discovered synthetic elements. Probably the best example of this would be masurium (element 43), which a team of German chemists claimed to have discovered in columbium (now known as niobium) ore in 1925. The claim was controversial and other workers could not replicate it, but some literature from the period does list it among the elements.

In 1936, Emilio Segrè and Carlo Perrier isolated element 43 from molybdenum foil that had been used in a cyclotron; they named it technetium. Even the longest-lived isotopes of technetium have a short half-life by geological standards (millions of years) and it has only ever been found naturally in minute traces as a product of spontaneous uranium fission. For this reason, the original claim of discovery (as masurium) is almost universally regarded as erroneous.

As far as I know, in none of these cases with synthetic elements has anyone actually produced a quantity of the element that one could see and weigh that later turned out not to be an element, in contrast to the case with didymium. (In the case of masurium, for instance, the only evidence of its existence was a faint x-ray signal at a specific wavelength.)

This post originally appeared on Quora. Click here to view.

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