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Clams Are Giving Each Other Cancer

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The clams are dying. Since at least the 1970s, soft-shell clams (Mya arenaria) from Canada to Maryland have been plagued with a mysterious disease. This month, researchers announced that they’d finally identified the disease: clam leukemia.

Clam leukemia?!

Clams are simple creatures. They don’t have legs, or brains, or faces. But they do have hearts, and those hearts pump hemolymph (the clam version of blood) throughout their bodies. It’s in this hemolymph that the cancer has taken hold.

For years, scientists suspected that the clam-killing disease was caused by a virus. Then a team of researchers specializing in microbiology, cancer, and marine biology examined the clams’ DNA.

What they found inspired more questions than answers. The clams had cancer—and it was contagious.

Nearly all cancers are a one-shot deal, and can’t be passed from one animal to another. Until recently, there were only two known contagious cancers in the world. One is a dog STD called Canine Transmissible Venereal Tumor. The other is Devil Facial Tumor Disease, which is transmitted when one Tasmanian devil bites another one on the face.

But clams aren’t humping, and since they don’t have faces, they’re definitely not biting each other. How, then, is the cancer passed from one clam to the next? The researchers aren’t totally sure, but they think that the cancer cells may be released into the water. Clams are filter feeders, sucking up liters of water every hour. If a few clam-cer cells happened to be in the neighborhood, they could easily find themselves a new home.

Nobody knows how one clam’s leukemia could become contagious. So where did those free-floating cancer cells come from? To find out, the scientists sequenced cancer cells from clams all up and down the East Coast. Yet again, the answer was mind-boggling: the genes were all identical, which means that every clam’s cancer had all come from a single, original host. That’s one unfortunate clam—which got cancer more than 40 years ago. That clam’s cancer cells scooted off into the ocean, where they found another host, whose cancer cells eventually scooted off into the ocean … and now it’s 2015. The cancer has traveled hundreds of miles, and we’ve got a whole lot of sick clams.

And it may not just be clams. Mussels, oysters, and cockles are all afflicted with similarly mysterious illnesses. As long as people want to eat shellfish, these researchers will have jobs.

Thankfully, only clams can get clam-cer. Eating seafood and swimming in the ocean are still safe for humans. As safe as they’ve ever been, anyway.

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Medicine
Charles Dickens Museum Highlights the Author's Contributions to Science and Medicine

Charles Dickens is celebrated for his verbose prose and memorable opening lines, but lesser known are his contributions to science—particularly the field of medicine.

A new exhibition at London’s Charles Dickens Museum—titled "Charles Dickens: Man of Science"—is showcasing the English author’s scientific side. In several instances, the writer's detailed descriptions of medical conditions predated and sometimes even inspired the discovery of several diseases, The Guardian reports.

In his novel Dombey and Son, the character of Mrs. Skewton was paralyzed on her right side and unable to speak. Dickens was the first person to document this inexplicable condition, and a scientist later discovered that one side of the brain was largely responsible for speech production. "Fat boy" Joe, a character in The Pickwick Papers who snored loudly while sleeping, later lent his namesake to Pickwickian Syndrome, otherwise known as obesity hypoventilation syndrome.

A figurine of Fat Boy Joe
Courtesy of the Charles Dickens Museum

Dickens also wrote eloquently about the symptoms of tuberculosis and dyslexia, and some of his passages were used to teach diagnosis to students of medicine.

“Dickens is an unbelievably acute observer of human behaviors,” museum curator Frankie Kubicki told The Guardian. “He captures these behaviors so perfectly that his descriptions can be used to build relationships between symptoms and disease.”

Dickens was also chummy with some of the leading scientists of his day, including Michael Faraday, Charles Darwin, and chemist Jane Marcet, and the exhibition showcases some of the writer's correspondence with these notable figures. Beyond medicine, Dickens also contributed to the fields of chemistry, geology, and environmental science.

Less scientifically sound was the author’s affinity for mesmerism, a form of hypnotism introduced in the 1770s as a method of controlling “animal magnetism,” a magnetic fluid which proponents of the practice believed flowed through all people. Dickens studied the methods of mesmerism and was so convinced by his powers that he later wrote, “I have the perfect conviction that I could magnetize a frying-pan.” A playbill of Animal Magnetism, an 1857 production that Dickens starred in, is also part of the exhibit.

A play script from Animal Magnetism
Courtesy of the Charles Dickens Museum

Located at 48-49 Doughty Street in London, the exhibition will be on display until November 11, 2018.

[h/t The Guardian]

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Health
Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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