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Scientists Say DNA Can Glow in the Dark

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We’ve told you before, but we’re glad to tell you again: Just about anything will glow if you give it the opportunity. The latest entry in the ency-glow-pedia? DNA. In a recently published paper in the Proceedings of the National Academy of Sciences, researchers described seeing DNA molecules blinking like Christmas lights. 

Along with carbohydrates, fats, and proteins, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are part of the group known as macromolecules. These big molecules make up the bulk of your cells and are therefore pretty darn important. Many scientists have spent many years studying macromolecules under microscopes, but they often come up against a frustrating obstacle: stains. (No, not that Stains.)

One of the most essential tools in biology today is the fluorescent microscope, which uses fluorescent and phosphorescent light to study biological matter like tissues and cells.

Protein filaments in a cancer cell. Image credit: Howard Vindin via Wikimedia Commons // CC BY-SA 4.0

The problem is that macromolecules don’t produce light—or at least that’s what the textbooks say. And because they don’t make their own light, they have to be treated with fluorescent stains to get them to show up. But it’s a devil’s bargain. The stains are toxic to living organisms, which means that scientists end up looking at dying cells. 

The stains confuse matters as much as they help, says co-senior author and Northwestern University engineer Vadim Backman. “The cell might die in two hours, so you can still do imaging in the first half hour,” he said in a press statement. “But what exactly are you measuring? What are you actually seeing? Are you looking at real processes of the cell? Or are you looking at processes in a cell that is about to die? Nobody knows.”

Thanks to Backman and his colleagues, all that confusion could become a thing of the past. The team had been looking at nucleotides (the building blocks of DNA) under a microscope when they saw a strange flash. They realized that under normal, visible light, DNA could in fact emit a fluorescent glow. It just wasn’t doing it all of the time. 

They realized that most studies had looked at the DNA in between flashes—kind of like watching a runner after a race.

“Sprinters alternate running very, very fast and resting,” Backman says. “You might catch them when they are resting and assume they aren’t doing anything. That’s what DNA and proteins do. They fluoresce for a very short time and then rest for a very long time.”

Further experiments revealed that hitting the macromolecules with just the right wavelength of light could make them glow just as brightly as any stained tissue. 

Backman and his colleagues are hopeful that these findings will lead to less complicated microscopy in the future. He credits their success to good old-fashioned scientific curiosity. 

“It sounds cliché, but you get the answer to the question you ask,” he said. “When we actually asked the right question, we got a very different answer than expected.”

Know of something you think we should cover? Email us at tips@mentalfloss.com. 

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Whale Sharks Can Live for More Than a Century, Study Finds
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Some whale sharks alive today have been swimming around since the Gilded Age. The animals—the largest fish in the ocean—can live as long as 130 years, according to a new study in the journal Marine and Freshwater Research. To give you an idea of how long that is, in 1888, Grover Cleveland was finishing up his first presidential term, Thomas Edison had just started selling his first light bulbs, and the U.S. only had 38 states.

To determine whale sharks' longevity, researchers from the Nova Southeastern University in Florida and the Maldives Whale Shark Research Program tracked male sharks around South Ari Atoll in the Maldives over the course of 10 years, calculating their sizes as they came back to the area over and over again. The scientists identified sharks that returned to the atoll every few years by their distinctive spot patterns, estimating their body lengths with lasers, tape, and visually to try to get the most accurate idea of their sizes.

Using these measurements and data on whale shark growth patterns, the researchers were able to determine that male whale sharks tend to reach maturity around 25 years old and live until they’re about 130 years old. During those decades, they reach an average length of 61.7 feet—about as long as a bowling lane.

While whale sharks are known as gentle giants, they’re difficult to study, and scientists still don’t know a ton about them. They’re considered endangered, making any information we can gather about them important. And this is the first time scientists have been able to accurately measure live, swimming whale sharks.

“Up to now, such aging and growth research has required obtaining vertebrae from dead whale sharks and counting growth rings, analogous to counting tree rings, to determine age,” first author Cameron Perry said in a press statement. ”Our work shows that we can obtain age and growth information without relying on dead sharks captured in fisheries. That is a big deal.”

Though whale sharks appear to be quite long-lived, their lifespan is short compared to the Greenland shark's—in 2016, researchers reported they may live for 400 years. 

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Scientists Find a Possible Link Between Beef Jerky and Mania
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Scientist have discovered a surprising new factor that may contribute to mania: meat sticks. As NBC News reports, processed meats containing nitrates, like jerky and some cold cuts, may provoke symptoms of mental illness.

For a new study, published in the journal Molecular Psychiatry, scientists surveyed roughly 1100 people with psychiatric disorders who were admitted into the Sheppard Pratt Health System in Baltimore between 2007 and 2017. They had initially set out to find whether there was any connection between certain infectious diseases and mania, a common symptom of bipolar disorder that can include racing thoughts, intense euphoria, and irritability.

While questioning participants about their diet, the researchers discovered that a significant number of them had eaten cured meats before their manic episodes. Patients who had recently consumed products like salami, jerky, and dried meat sticks were more likely to be hospitalized for mania than subjects in the control group.

The link can be narrowed down to nitrates, which are preservatives added to many types of cured meats. In a later part of the study, rats that were fed nitrate-free jerky acted less hyperactive than those who were given meat with nitrates.

Numerous studies have been published on the risks of consuming foods pumped full of nitrates: The ingredient can lead to the formation of carcinogens, and it can react in the gut in a way that promotes inflammation. It's possible that inflammation from nitrates can trigger mania in people who are already susceptible to it, but scientists aren't sure how this process might work. More research still needs to be done on the relationship between gut health and mental health before people with psychiatric disorders are told to avoid beef jerky altogether.

[h/t NBC News]

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