Scientists Have Figured Out Why Marimo Balls Only Float During the Day

Shaunacy Ferro, Mental Floss
Shaunacy Ferro, Mental Floss

Scientists have solved a long-running mystery surrounding marimo, the fuzzy balls of green algae that Japan considers a national treasure.

Though marimo are known for nestling adorably at the bottom of rivers and lakes, they’re not always bottom dwellers. They sink at night, but during they day, they float—and until now, researchers weren’t quite sure why. As Atlas Obscura reports, a new study gets to the bottom of the mystery: It’s photosynthesis.

The study, published in Current Biology, finds that floating and sinking are natural byproducts of the marimo’s circadian rhythm driven by photosynthesis.

During the day, bubbles form within the spherical balls of Aegagropila linnaei algae, making them float to the surface of the water. In order to find out what drives the formation of these bubbles, researchers from the University of Bristol used a chemical that blocks photosynthesis. They found that bubbles didn’t form on chemically altered marimo, nor did the algae balls float, even when they were exposed to 48 hours of constant light.

Once they knew that photosynthesis was key to marimo buoyancy, the researchers exposed their lab-grown marimo to different light conditions in order to test whether their circadian rhythm plays a role in floating. The marimo were exposed to 12 hours of darkness and 12 hours of light during the day, then transferred to an environment with constant dim, red lighting for a few days. When the researchers then exposed these algae balls to bright light at the beginning of the day—mimicking the natural light cycle—they found that the marimo floated to the top of the water quicker than they did if they were exposed to bright light in the middle of the day. Basically, the marimo had jet lag.

The researchers suggest that this day-night buoyancy cycle might help the marimo maximize the amount of light they get each day. Since there’s less light at lower depths (like at the bottom of a lake), marimo float to the top of the water to maximize their potential for photosynthesis each day.

Marimo are endangered in the wild, and are no longer found in many of the lakes that were once teeming with the balls of algae. Given that photosynthesis drives the marimo’s daily cycle, these population changes could be due to pollution changing how much light penetrates the water in those lakes, according to Dora Cano-Ramirez, the study’s first author.

[h/t Atlas Obscura]

9 Fascinating Facts About the Vagus Nerve

The vagus nerve is so named because it “wanders” like a vagabond, sending out sensory fibers from your brainstem to your visceral organs. The vagus nerve, the longest of the cranial nerves, controls your inner nerve center—the parasympathetic nervous system. And it oversees a vast range of crucial functions, communicating motor and sensory impulses to every organ in your body. New research has revealed that it may also be the missing link to treating chronic inflammation, and the beginning of an exciting new field of treatment for serious, incurable diseases. Here are nine facts about this powerful nerve bundle.

1. THE VAGUS NERVE PREVENTS INFLAMMATION.

A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis. The vagus nerve operates a vast network of fibers stationed like spies around all your organs. When it gets a signal for incipient inflammation—the presence of cytokines or a substance called tumor necrosis factor (TNF)—it alerts the brain and draws out anti-inflammatory neurotransmitters that regulate the body’s immune response.

2. IT HELPS YOU MAKE MEMORIES.

A University of Virginia study in rats showed that stimulating their vagus nerves strengthened their memory. The action released the neurotransmitter norepinephrine into the amygdala, which consolidated memories. Related studies were done in humans, suggesting promising treatments for conditions like Alzheimer’s disease.

3. IT HELPS YOU BREATHE.

The neurotransmitter acetylcholine, elicited by the vagus nerve, tells your lungs to breathe. It’s one of the reasons that Botox—often used cosmetically—can be potentially dangerous, because it interrupts your acetylcholine production. You can, however, also stimulate your vagus nerve by doing abdominal breathing or holding your breath for four to eight counts.

4. IT'S INTIMATELY INVOLVED WITH YOUR HEART.

The vagus nerve is responsible for controlling the heart rate via electrical impulses to specialized muscle tissue—the heart’s natural pacemaker—in the right atrium, where acetylcholine release slows the pulse. By measuring the time between your individual heart beats, and then plotting this on a chart over time, doctors can determine your heart rate variability, or HRV. This data can offer clues about the resilience of your heart and vagus nerve.

5. IT INITIATES YOUR BODY'S RELAXATION RESPONSE.

When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. The vagus nerve’s tendrils extend to many organs, acting like fiber-optic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.

6. IT TRANSLATES BETWEEN YOUR GUT AND YOUR BRAIN.

Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials". Your gut feelings are very real.

7. OVERSTIMULATION OF THE VAGUS NERVE IS THE MOST COMMON CAUSE OF FAINTING.

If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak. You’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.

8. ELECTRICAL STIMULATION OF THE VAGUS NERVE REDUCES INFLAMMATION AND MAY INHIBIT IT ALTOGETHER.

Neurosurgeon Kevin Tracey was the first to show that stimulating the vagus nerve can significantly reduce inflammation. Results on rats were so successful, he reproduced the experiment in humans with stunning results. The creation of implants to stimulate the vagus nerve via electronic implants showed a drastic reduction, and even remission, in rheumatoid arthritis—which has no known cure and is often treated with the toxic drugs—hemorrhagic shock, and other equally serious inflammatory syndromes.

9. VAGUS NERVE STIMULATION HAS CREATED A NEW FIELD OF MEDICINE.

Spurred on by the success of vagal nerve stimulation to treat inflammation and epilepsy, a burgeoning field of medical study, known as bioelectronics, may be the future of medicine. Using implants that deliver electric impulses to various body parts, scientists and doctors hope to treat illness with fewer medications and fewer side effects.

How to Relieve a Tension Headache in 10 Seconds, According to a Physical Therapist

iStock.com/SIphotography
iStock.com/SIphotography

The source of a pounding headache isn't always straightforward. Sometimes over-the-counter painkillers have no effect, and in other cases all you need is a glass of water to ease the pain. When it comes to a specific type of a headache, Prevention recommends a treatment that takes about 10 seconds—no fancy medications or equipment required.

If you're experiencing pain throughout your head and neck, you may have a tension headache. This type of headache can happen when you tense the muscles in your jaw—something many people do when stressed. This tightening triggers a chain reaction where the surrounding muscles in the head and neck become tense, which results in a painful, stiff feeling.

Fortunately, there's a way to treat tension headaches that's even easier than popping an Advil. David Reavy, a physical therapist known for his work with NFL and NBA athletes, recently suggested a solution to Prevention writer Christine Mattheis called the masseter release. To practice it yourself, look for the masseter muscle—the thick tissue that connects your jawbone to your cheekbone on either side of your face—with your fingers. Once you've found them, press the spots gently, open your mouth as wide as you can, close it, and repeat until you feel the muscle relax. Doing this a few times a day helps combat whatever tension is caused by clenching your jaw.

If that doesn't work, it's possible that the masseter muscle isn't the source of your headache after all. In that case, read up on the differences among popular pain killers to determine which one is the best match for your pain.

[h/t Prevention]

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