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Study Links Depression With Gut Bacteria Imbalance

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The future of depression treatment might be chilling in the dairy case. A study published earlier this year in Nature Scientific Reports said that beneficial bacteria commonly found in yogurt can help relieve depression-like symptoms in mice.

Over the last few decades, scientists have begun exploring the connections between our brains and all the microbes that live on and inside our bodies, and they've learned that those little microbes have an awful lot of power. Some studies have shown that bacterial imbalances can affect nervous system function, while others have suggested that people with bacterial imbalances may be more prone to anxiety and depression.

To test these hypotheses, researchers at the University of Virginia decided to begin at the overlap between the nervous system and mood: stress. Stress increases depression risk; it also affects, and is affected by, the function of the nervous system.

The scientists began by collecting a group of unlucky mice and subjecting them to a variety of intense stressors. Some were kept in crowded cages; others had to sit under strobe lights or listen to loud noises. Predictably, the stressful situations took a toll, and the mice began exhibiting what the researchers called “despair behavior.”

The researchers collected poop samples from the mice before and after the stress sessions, then ran genetic analyses to determine the species and quantities of bacteria living in each mouse’s gut. The results showed that the stress resulted in a pretty significant drop in a microbe called Lactobacillus—the same type of so-called "good" bacteria found in yogurt.

But the rodents’ despair would not prove permanent. The researchers began giving the mice small doses of Lactobacillus with their meals, and, over time, their symptoms resolved.

Lead author Alban Gaultier. Image Credit: Josh Barney | University of Virginia Health System

 
"This is the most consistent change we've seen across different experiments and different settings we call microbiome profiles," co-author Ioana Marin said in a statement. "This is a consistent change. We see Lactobacillus levels correlate directly with the behavior of these mice."

The team hopes to take their experiments into the human body next. Lead author Alban Gaultier said he has “big hope” that probiotics could someday augment or even replace side-effect–heavy antidepressant drugs. “It would be magical just to change your diet,” he said, “to change the bacteria you take, and fix your health—and your mood.”

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Belly Flop Physics 101: The Science Behind the Sting
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Belly flops are the least-dignified—yet most painful—way of making a serious splash at the pool. Rarely do they result in serious physical injury, but if you’re wondering why an elegant swan dive feels better for your body than falling stomach-first into the water, you can learn the laws of physics that turn your soft torso a tender pink by watching the SciShow’s video below.

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What's the Saltiest Water in the World?
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Saltwater is common around the world—indeed, salty oceans cover more than two-thirds of the globe. Typical saltwater found in our oceans is about 3.5% salt by weight. But in some areas, we find naturally occurring saltwater that's far saltier. The saltiest water yet discovered is more than 12 times saltier than typical seawater.

Gaet’ale is a pond in Ethiopia which currently holds the record as the most saline water body on Earth. The water in that pond is 43.3% dissolved solids by weight—most of that being salt. This kind of water is called hypersaline for its extreme salt concentration.

In the video below, Professor Martyn Poliakoff explains this natural phenomenon—why it's so salty, how the temperature of the pond affects its salinity, and even why this particular saltwater has a yellow tint. Enjoy:

For the paper Poliakoff describes, check out this abstract.

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