This May Be Why You Crave That Burger

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iStock

You’re minding your own business when it hits you: the overwhelming desire for a juicy burger. Where did that sudden meat-need come from? Scientists at Johns Hopkins University may have an answer: a circuit inside your brain that seems to cause protein cravings. The researchers published their findings in the journal Science.

Animals like us need nutrients like protein in order to keep going. Many scientists believe that food cravings are our bodies’ way of motivating us to seek those nutrients out. Yet the exact neurological source of these craving impulses has been something of a mystery.

The authors of the current study started very, very small, looking at cells and circuits in the brains of fruit flies. Activities like mating can increase a fly’s protein cravings, so the researchers decided to focus on female flies that had recently had sex. The scientists monitored the flies' little brains while withholding the bugs’ favorite protein-rich meal of yeast. As the flies’ protein hunger increased, the researchers saw a small circuit of neurons they dubbed DA-WED light up.

To double-check that these cells were in fact craving-related, the scientists shut them down, then offered the recently mated females access to as much yeast as they wanted. But while the circuits were off, the yeast just didn’t seem all that appealing.

Shutting down the DA-WED cells didn’t make the flies drink any less water, nor did it make them eat less in general. They just didn’t feel like getting their yeast on.

These are early findings yet. More research will be needed to confirm the craving/brain cell link in flies, and we’ll definitely need more experiments before we can say the same is true in people. And the average burger also contains two other addictive substances: fat and refined carbohydrates (in the bun).

Still, this paper is an interesting start.

“Further characterization of these and related circuit mechanisms should help delineate the fundamental principles governing protein-specific hunger,” the authors say. “A better understanding of how animals choose to consume protein may also have implications for the treatment of obesity.”

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

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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
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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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