November 25, 2014 | David F. Coppedge

Let's Get [Thankful for the] Physical

Wonders of the human body continue to pour forth from scientific research, providing more reasons to give thanks.

Cartilage sensor:  Football players should give thanks that their cartilage can sense forceful injury.  “We live with the same cartilage—the tissue that connects our joints—for a lifetime,” Medical Xpress says.  “And since we can’t readily make new cartilage cells, we had better figure out how to keep what we have healthy.”  Researchers at Duke were pleasantly surprised.  “The most exciting thing about this study was that it shows that cells in your cartilage, which people don’t think of as a typical sensory cell, have multiple sensory systems,” one said. Another commented, “These cells are very complex in their ability to sense their mechanical environment.”  Physical activity is actually good for cartilage, the article says.  Use it or lose it.

Fallopian one-way tube:  How do female fallopian tubes know which direction to send the egg?  Scientists know that cilia beat inside the walls of the tube, creating a unidirectional flow.  But how do those cells arrange in the right direction to begin with?  When the tissues grow in the embryo, there is no preferred direction, Japanese researchers found, according to Medical Xpress.  Over time, a preferred orientation arises, thanks to a protein named Celsr1.  The process amazed one of the researchers:

The research fellow Dongbo Shi, the first author of this article, said: “It was a hard job for me to line up the cellist’s chairs on stage in the right direction before a classic concert, even though there are less than ten chairs. It is very surprising that our organs consist of millions of cells and these cells are aligned accurately and efficiently. I hope to uncover the intriguing mechanisms of how cells are properly lined up”.

Bone self-repair:  Babies can do a trick adults would like to learn: how to self-repair their bones.  Nature says, “Infant bone fractures heal without any medical intervention, thanks to muscle contractions and tissue growth that together move the bone fragments back into place.”

Tick off the old clock:  “Human existence is basically circadian,” a piece on PhysOrg begins. “Most of us wake in the morning, sleep in the evening, and eat in between. Body temperature, metabolism, and hormone levels all fluctuate throughout the day, and it is increasingly clear that disruption of those cycles can lead to metabolic disease.” But how does our circadian clock work?  Research at the University of Pennsylvania shows a new role for proteins called enhancers. Along with corresponding transcription factors, the enhancers allow different cycles to switch on and off independently of other cycles, so that you don’t fall asleep which eating a Thanksgiving meal.

Why skin color?  It can be a racy subject, but Ann Gibbons wants to shed light on why human skin varies from light to dark.  In Science Magazine, she explores various hypotheses, mainly those of anthropologist Nina Jablonski, who thinks skin faces a tradeoff between UV protection and Vitamin D absorption.  “Although skin color is a poor way to classify humans, Jablonski says it does have real implications for health.”  Trying to place the adaptive tradeoff in an evolutionary context, though, is fraught with emotion and storytelling, as Jablonski learned in 2000:

In that paper, Jablonski proposed an evolutionary scenario for dark skin: Like chimpanzees, our ancient ancestors in Africa originally had fair skin covered with hair. When they lost body hair in order to keep cool through sweating, perhaps about 1.5 million years ago, their naked skin became darker to protect it from folate-destroying UV light.

This idea is still controversial. “It’s a valid theory and it’s intriguing, but it’s obscure to the folate community,” says Robert Berry, a pediatric epidemiologist at the Centers for Disease Control and Prevention in Atlanta. “There’s virtually no evidence to prove it or disprove it.” …

Jablonksi is spreading an evolutionary perspective that many still haven’t quite absorbed, says Harvard University immunologist Barry Bloom. “The message that people still don’t understand that just knocks your socks off is that we were all born white on the planet and then we all became black,” he says. Then “some of us got to Europe where being black wasn’t a great advantage, and we became white again.”

Maybe it’s best to leave the evolution out of it and just recognize that people have the genetic ability to adapt to the amount of sunlight they normally live in.  Obviously, dark- and light-skinned people are doing fine in all kinds of environments.  They also have the wisdom to wear clothes, make sunscreen, and take Vitamin D supplements.  Too much speculating could foment old fights about racial geopolitics.

A little help from our friends:  What’s your first emotional reaction to the words “bacteria” and “virus”?  Actually, our lives probably depend more on these passengers than we like to think.  Science Magazine says that the body’s bacteria may keep our brains healthy.  Even more surprising, in another piece by Science Magazine‘s writer Elisabeth Pennisi, “viruses help keep our gut healthy.”  How many knew that the gut biota we have become accustomed to treating with respect includes viruses?  Noroviruses, for instance, have a bad rap for causing diarrhea on cruise ships.  Experiments on mice, though, show that infected mice were better able to recover from disease and antibiotics.  It will be “hugely controversial” to consider noroviruses as beneficial (New Scientist recommends still washing your hands), but your digestion of a Thanksgiving meal might just depend on all your tiny helpers.

A gene for long life?  Medical Xpress tells about a “favorable variant” in the CETP gene that confers on its carriers a higher probability of living past 90 or even 100, partly by raising the level of good cholesterol (HDL).  The carriers not only live longer; they live healthier, too.  Can you get this “longevity gene”?  No, but some day you may be able to buy a longevity pill.  “Drug companies have already begun working on CETP inhibitors, with the hope of mimicking the process by which the gene raises HDL.”

Designed selection:  Try to design a hoop that can let basketballs in but keep ping pong balls out.  That’s what the nuclear pore complex does, researchers at University College London found.  Science Daily says that because of this ability, the filter keeps “unwelcome visitors” from invading the cell nucleus.  How does it work?  The pore has strands outside that look like spaghetti.  The strands trap unwanted small invaders.  “Larger molecules, like messenger RNA, can only pass when accompanied by chaperone molecules. These chaperones, called nuclear transport receptors, have the property of lubricating the strands and relaxing the barrier, letting the larger molecules through.”  How fast does this work?  Oh, a leisurely several thousand times per second.

Make like a bat:  Philosopher Thomas Nagel famously asked, “What is it like to be a bat?” (see ENV).  Well, ask a blind person.  Science Magazine says that people have the ability to learn to echolocate a bit like a bat, using “batlike sonar.”  This should be a fun experiment for the kids at home.  Maybe they should wear a helmet, like Daniel Kish, a blind boy who uses echolocation to ride his bike.  Emily Underwood says that “the entire body, neck, and head are key to ‘seeing’ with sound—an insight that could assist blind people learning the skill.”  The skill is much more highly developed in bats and dolphins, of course.

Smell that turkey aroma:  At Thanksgiving, think about what PNAS says: “The mammalian olfactory system is capable of detecting and discriminating a vast and diverse array of small organic molecules or odorants. Complex blends of these chemicals are finally perceived as a unified odor object—for example, a rose contains dozens of active compounds.”  The sense of smell is so complex, it is one of the final senses to submit to detailed understanding.  One thing we know; the smell of Mom’s cooking can create pleasant memories that last a lifetime.

There are more wonders going on inside us than we can imagine.  The more the detail, the more incredible to think they are the result of blind, unguided natural processes.  We hope you will be thankful for your equipment this season, and treat it with care.

 

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