The Strength of Moon Jellies' Muscles Help Them Perpetually Self-Heal

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<p>
  While the field of robotics has advanced greatly in the last decade, scientists have struggled to create robot that can reliably heal themselves. Robots with soft structures, in particular, are prone to damages when navigating complex environments. Some engineers have tried giving robots “bio-inspired” characteristics, like the ability to regrow damaged parts or heal wounds, in order to counter the risk.
 </p>
<p>
  The task isn’t an easy one—most self-repair mechanisms rely on new growth. But scientists have just discovered that the moon jellyfish,
  <em>
   Aurelia aurita
  </em>
  , self-heals by undergoing a very different process: it adjusts the structure of its body.
 </p>
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<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/moon-jellyfish_2048x1152.width-990_CcPq6UK.jpg"/>
<figcaption>Just keep swimming.
        
    </figcaption>
</figure>
<p>
  The moon jellyfish is made of a gelatin-like material and can get injured rather easily, like other animals similar to it (in fact,
  <a href="http://icb.oxfordjournals.org/content/50/4/479.short">
   one study
  </a>
  estimated that 35 to 47% of seafloor invertebrates are injured). They also have radial symmetry, which means their bodies are organized around a single axis—when cut in half in any direction through the middle, the resulting two pieces are mirror images of each other. In order to move efficiently through the water, moon jellyfish need to hold this symmetry in place. So when a moon jellyfish loses a limb, it contracts and expands its body in order to re-establish the radial symmetry it needs to survive in the wild, according to Michael Abrams of the California Institute of Technology, who was the lead author of a
  <a href="http://www.pnas.org/content/early/2015/06/09/1502497112.full.pdf?sid=cb2279d3-c137-40c5-b05d-97728817db04">
   study
  </a>
  published June 15 in
  <em>
   Proceedings of the National Academy of Sciences
  </em>
  .
 </p>
<p>
  This process is called symmetrization, and it’s a natural part of the jellyfish’s lifestyle, even when uninjured; as a moon jellyfish flaps its arms, its body deforms and takes in nutrient-rich water. At the completion of this “pulse,” the jellyfish returns to its original state.
 </p>
<p>
  Here’s Sabrina Imbler,
  <a href="http://www.scientificamerican.com/article/jellyfish-gooeyness-could-be-a-model-for-self-healing-robots/">
   writing
  </a>
  for Scientific American:
 </p>
<blockquote>
<p>
   The researchers found that the muscle contractions exerted by each pulse of the jellyfish with a missing limb forced its other arms to space out equally. The sudden crowding sensation of its remaining arms caused the jellyfish to push its limbs away from one another and toward the empty space, thus forming a more stable configuration. ‘In one pulse, it may look like it’s going back to its original form,” Abrams says. “But that pulse over thousands of times makes symmetry.’
  </p>
<p>
   Imagine a wagon that has lost a front wheel. Without changing the placement of the remaining three wheels, the wagon would be stuck. Centering the remaining front wheel, however, would rebalance the vehicle as a fully functional wheelbarrow. Same function, different body.
  </p>
</blockquote>
<p>
  If scientists are able to mimic moon jellyfish’s ability to self-heal through symmetrization, they might be able to create a robot that can move efficiently and fix itself, without needing to keep the additional supplies on hand. The moon jellyfish adapts to its new body and recreates the structure it needs through a pre-existing muscle function. A robot that uses this process wouldn’t need to develop anything new—it would just restore the symmetry it needs to complete its role.
 </p>
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<div class="inline-caption">
  Learn more about bio-inspired technologies with "Making Stuff: Wilder," streaming online.
 </div>
</section>
<p>
 Photo credit:
 <a href="https://www.flickr.com/photos/warriorwoman531/8328074257/">
  Heather Paul / (CC BY-ND 2.0)
 </a>
</p>

One challenge is confirming that every crop in the field is sprayed.

RNA Spray Could Make GMOs Obsolete

<p>
</p>
<p>
 As Scotland moves forward to
 <a href="http://www.theguardian.com/environment/2015/aug/09/scotland-to-issue-formal-ban-on-genetically-modified-crops">
  ban genetically modified crops
 </a>
 , Monsanto is developing a way to alter crops without touching their genes.
</p>
<div class="related"></div>
<p>
 Through RNA interference, or the process of temporarily barring gene expression, Monsanto scientists have been able to stop the Colorado potato beetle from eating crops. Instead of modifying the crop’s genes, they’ve sprayed RNA that shuts down a gene the insects need to survive directly onto the crops. When the beetles eat the plant, the ingested RNA will eventually cause them to die through inhibiting the necessary gene.
</p>
<p>
 Antonio Regalado, reporting at MIT Technology Review, explains RNA interference further:
</p>
<blockquote>
<p>
 The mechanism is a natural one: it appears to have evolved as a defense system against viruses. It is triggered when a cell encounters double-stranded RNA, or two strands zipped together—the kind viruses create as they try to copy their genetic material. To defend itself, the cell chops the double-stranded RNA molecule into bits and uses the pieces to seek out and destroy any matching RNA messages. What scientists learned was that if they designed a double-stranded RNA corresponding to an animal or plant cell’s own genes, they could get the cells to silence those genes, not only those of a virus.
</p>
</blockquote>
<p>
 Other companies, all of which are hoping to avoid the controversy they face when they genetically modify crops directly, are exploring the genetic spray alternative to GMOs. These sprays can be created and applied quickly, providing protection if the plants are infested by a never-before-seen virus or insect. They could even be used to endow plants with advantageous, temporary traits. For example, farmers could spray RNAis that bestow corn plants with drought-resistance, saving a harvest during hot, dry weather.
</p>
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<p>
 Such sprays can only turn off genes for a few days or weeks at a time, so all efforts would be temporary. If a new set of insect invaders enters the field of crops weeks after the last RNA spray, the plants would no longer be protected. But the approach has it’s benefits, too, because the plants’ genes that were affected to help them survive in a water shortage would revert back to their original states when the water shortage ends. This means they could thrive in both conditions. In addition to that, if insects evolve to survive the RNA spray, the scientists could switch which gene they’re affecting. Monsanto is hoping to improve the sprays to last for months—some scientists have already been successful in creating these long-lasting sprays.
</p>
<p>
 Since the spray target specifics genes that only that certain targeted insects have, it wouldn’t affect beneficial bugs that currently suffer from pesticide use, such as bees. This differentiates the spray from traditional insecticides, which are indiscriminate killers.
</p>
<p>
 Despite the lack of evidence of harmful effects of the spray, it will most likely face stiff opposition. Some worry the spray will be hard to control, and wind could blow it to surrounding areas. Others argue that the RNA interference might silence important genes in humans when we eat the crops, but no trustworthy studies so far have shown that to be true.
</p>
<div class="newsletter"></div>
<p>
 Photo Credit: Public Domain
</p>

<p>Through RNA interference, or the process of temporarily barring gene expression, Monsanto scientists have been able to stop a pest from eating crops by spraying RNA that shuts down a gene the insects need to survive directly onto the plants.</p>

Blood tests can be used to determine which of a patient's genes are being expressed.

New Blood Test Predicts Future Suicide Attempts

<p>
</p>
<p>
 About one million people per year commit suicide—or about one person every 40 seconds. However, a new blood test could help determine if a patient is or will be suicidal. It could drastically improve the chances of survival.
</p>
<div class="ad"></div>
<p>
 The need for such a test arises more often than you might think. Doctors in emergency rooms sometimes can’t identify if patients intentionally overdosed or injured themselves or if the incidents were accidental, impeding the doctors’ ability to decide treatment plans for a patient. Alexander Niculescu of Indiana University developed a blood test and questionnaire that can predict who within a group of men with psychological disorders will develop suicidal feelings in the next year.
</p>
<p>
 Sally Adee, reporting for New Scientist, explains:
</p>
<blockquote>
<p>
 To develop the test, over several years Niculescu’s team took blood samples from 217 men undergoing various psychiatric treatments. They compared changes in gene expression in 37 of them who developed suicidal feelings with previously published work and with post-mortem samples of 26 men who had killed themselves. They identified 11 gene changes that could be biological markers for spotting people who might be considering suicide, and they monitored these same markers in a test group of 265 men with psychiatric conditions.
</p>
</blockquote>
<p>
 The questionnaire asked the subjects about their physical energy as well as their feelings about their accomplishments, but avoided direct questions about suicide. In a trial of 108 people, the scientists’ predictions of suicidal ideation was 92% accurate, and in a second trial of 157 people, they predicted which men would be hospitalized from a suicide attempt that year with 71% accuracy.
</p>
<p>
 The test was especially accurate when predicting suicidal thoughts within the next year in people with bipolar disorder, predicting correctly 98% of the time. It even predicted with 94% accuracy who would make a serious suicide attempt that would require hospitalization.
</p>
<div class="related"></div>
<p>
 Other methods to detect psychiatric disorders are often subjective, but this test uses biomarkers, or biological indicators of a disease. In this case, the biomarker is in the patient’s gene expression as measured by the RNA levels in their blood. (Translation of DNA to RNA is the first step when a gene is expressed. Many of our genes are not expressed at any given time.) Still, biomarkers aren’t a panacea because the genetic biomarkers won’t occur in all patients with a psychiatric disorder. Plus, if doctors start to rely on them heavily, they could overlook the correct disease if the patient doesn’t have the biomarkers for it.
</p>
<p>
 There are doubts about its effectiveness on the general population, since only 16 people out of every 100,000 commit suicide. Right now, the test could provide too many false positives and false negatives for use in the general population to be safe, but could be helpful for those already diagnosed with psychological disorders, since doctors could make further decisions on treatment of those patients, including the length of hospital stays and medication.
</p>
<p>
 Photo Credit: Public Domain
</p>

<p>Scientists have developed a test that can predict if someone will attempt suicide—and whether it will require hospitalization.</p>

Universal Flu Vaccine Could End Annual Shots

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<p>
  Winter comes with the threat of influenza, and in recent years, it’s become an annual routine to get a flu shot. However, in a few years, your autumn flu shot could be your last.
 </p>
<p>
  A newly created vaccine protects from eight different flu strains simultaneously. The results in tests on mice were promising, and scientists hope to move on to testing ferrets next, according to the study published in the journal mBio.
 </p>
<p>
  Current flu vaccines only protect against whichever strains U.S. health officials think could be the most prevalent that year. Even with an annual flu shot, you’re still susceptible to other strains of the virus—and the vaccine that’s picked isn’t always the correct choice for that year. For example, the vaccine selected last year was only about 19% effective against the most predominant strain.
 </p>
<figure class="richtext-image full-width">
<img alt="H1N1 influenza virus" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/h1n1-influenza-virus_ql0sz8Z.width-990_5TO6gX9.jpg"/>
<figcaption>The vaccine could protect against many flu strains, including H1N1, seen here.
        
    </figcaption>
</figure>
<p>
  Scientists at the National Institute of Allergy and Infectious Diseases (NIAID) created the new, more effective vaccine that could potentially protect against influenza across the board. They did this by creating a virus-like particle which was studded with 16 representative proteins from four major strains, H1, H3, H5, and H7. The proteins, called hemagglutinin, are what help influenza particles bind to our cells and allow them to be infected with the viruses genome. Today’s influenza vaccines, on the other hand, merely contain specific antigens which help train the immune system, but only for the selected strains.
 </p>
<p>
  Robert Preidt, reporting for of U.S. News &amp; World Report, explains the results further:
 </p>
<blockquote>
<p>
   The NIAID scientists developed a vaccine meant to protect against a number of flu strains. The vaccine protected 95 percent of mice against eight different flu strains, compared with 5 percent of mice that received mock vaccinations.
  </p>
</blockquote>
<p>
  In addition to that, the mice were still protected from influenza six months post vaccination—even the older mice. This means that the vaccine could work well for seniors, something doctors have struggled with in the past. With this form of the vaccine, researchers won’t have to fit the vaccine to the virus; it would be effective against whatever strain comes their way.
 </p>
<p>
  This research comes at the same time as a
  <a href="http://www.popsci.com/new-antibody-staves-several-flu-strains-once" target="_blank">
   discovery of a new antibody
  </a>
  that could strengthen flu vaccines so that they are more likely protect against the most powerful strains of the virus, including H1N1.
 </p>
</section>
<p>
 Image credit: National Institute of General Medical Sciences
</p>

Found! Ancient Stars That Paved the Way for Life

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<p>
  A team of astronomers this week announced the discovery of a galaxy that contains stars from the very first generation after the Big Bang—the ones we have to thank for life on Earth.
 </p>
<p>
  When the first stars in our universe died and exploded, they would gush hydrogen and helium into space, causing thermonuclear reactions. These reactions eventually formed elements that are now abundant in the universe, including oxygen, carbon, and iron, the key ingredients to life and the reason for our existence today.
 </p>
<figure class="richtext-image full-width">
<img alt="Artist’s impression of CR7: the brightest galaxy in the early Universe" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/cr7.width-990_0S5YwkC.jpg"/>
<figcaption>An artist's impression of CR7
        
    </figcaption>
</figure>
<p>
  This ancient galaxy is three times as luminous of any other known galaxy, according to their paper published in The Astrophysical Journal. Since it came into existence only 800 million years after the Big Bang, the light from the galaxy has been travelling for 12.9 billions years to reach Earth. As far as astronomers can tell, the galaxy is a bright blue cloud consisting of only hydrogen and helium, and since the earliest stars were only made up as hydrogen, helium, and small amounts of lithium, it’s likely they were among the first stars in the universe.
 </p>
<p>
  David Sobral, a professor at Portugal’s University of Lisbon, led the team of astronomers and decided to name this galaxy CR7, or Cosmos Redshift 7, after the universe dating technique. (He admitted that Cristiano Ronaldo, number seven on the Portuguese national soccer team, was also inspiration for the name.)
 </p>
<p>
  The stars in CR7 contain the building blocks for most of the stars that exist today, including our solar system’s sun. Today’s younger stars contain a mix of heavier elements, called metals and are in the spiral arms and younger parts of galaxies.
 </p>
<p>
  In the mid-twentieth century, astronomers first noticed that in the oldest parts of galaxies stars are older and have fewer metals. Because of this, they realized that the earliest stars must have consisted almost entirely of hydrogen and helium. Stars in CR7 fit this profile, what astronomers call Population III stars.
 </p>
<p>
  Here’s Dennis Overbye, reporting for The New York Times:
 </p>
<blockquote>
<p>
   While the blue cloud is metal-free, according to spectral measurements, the color of the rest of the galaxy is consistent with more evolved stars making up most of its mass. This suggests, they write, that the Population III stars there are late bloomers of a sort, forming from leftover clouds of pristine material as the galaxy was sending out its light 12.9 billion years ago.
  </p>
</blockquote>
<p>
  So while the stars in CR7 are truly old, they’re not quite the absolute oldest stars in the universe.
 </p>
<p>
  The science isn’t quite settled, though. There is a remote possibility that the light is coming from a primordial cloud—containing only hydrogen and helium and created by the Big Bang—that skipped becoming a star and then collapsed into a black hole. But that’s never been seen before, so to rule it out, they’ll be training the Hubble and James Webb space telescopes on that part of the sky.
 </p>
</section>
<p>
 Photo credit: ESO
</p>

Endangered Sawfish Are Cloning Themselves to Stave Off Extinction

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<div class="add-container clearfix" id="add-block-placer">
</div>
<p>
  Recently, off southwest Florida, researchers found evidence of virgin births of an unlikely sort—those of a sawfish. They’re the first known cases of vertebrates reproducing asexually in the wild.
 </p>
<p>
  Asexual reproduction isn’t unusual in nature—bacteria and many invertebrates employ it—but it isn’t often seen in species with a backbone. Some captive animals, including snakes and sharks, have been known to reproduce asexually, but never in the wild until now.
 </p>
<figure class="richtext-image full-width">
<img alt="" class="richtext-image full-width" src="https://www.pbs.org/wgbh/nova/media/images/sawfish.width-990_GSFAj71.jpg"/>
<figcaption>Sawfish are cartilaginous fish with a large rostrum that's laced with electrosensitive pores.
        
    </figcaption>
</figure>
<p>
  Smalltooth sawfish are critically endangered, with their population hovering at only 1–5% of its original size. As a result, their population density is significantly lower, meaning it’s harder for females to find males to mate with, which could force females to undergo what’s called facultative parthenogenesis. (Parthenogenesis is reproduction without a fertilized egg, while facultative means they’re not required to reproduce sexually, but can if the circumstances arise.)
 </p>
<p>
  For the endangered sawfish, asexual reproduction could help prop up the species, but only if the parthenogens—the term for the asexually produced offspring—are fertile, something we won’t know until they’re a bit older.
 </p>
<p>
  Researches captured 190 sawfish over nine years, according to a study published on this week in Current Biology. Thanks to DNA evidence, there is little doubt that some of these sawfish are clones of their mothers. The scientists compared microsatellites, or the genetic fingerprints, of the captured sawfish and found that the microsatellites of sawfish siblings and half siblings matched between 25% and 50% of the time. In the sawfish that weren’t related, less than 10% of their microsatellites matched. However, in seven sawfish, it was a different story.
 </p>
<p>
  Cathleen O’Grady, writing at Ars Technica:
 </p>
<blockquote>
<p>
   The seven outliers, though, had matches of 84 to 100 percent. Two of the seven outlier sawfish were unrelated to any of the other five, suggesting they each had a different mother. Five of them, however, all seem to have shared a single mother, meaning they were possibly from a single brood. All seven were female—parthenogens can’t have a different sex from their mothers.
  </p>
<p>
   It is technically possible for matches to be so high in individuals produced by normal sexual reproduction, but the chances are extremely low. For the sawfish with a match on 84 percent of the examined microsatellites, it’s one in 437 billion. For those with a 100 percent match, it’s one in 239 trillion.
  </p>
</blockquote>
<p>
  Given smalltooth sawfish are not the only endangered cartilaginous fish, scientists think that parthenogenesis might occur in other species in the wild, too. Fortunately, other teams won’t necessarily have to scour the oceans for evidence. The researchers are encouraging their colleagues to check existing DNA databases for other similar genetic patterns, perhaps among similarly endangered species.
 </p>
</section>
<p>
 Photo credit:
 <a href="http://commons.wikimedia.org/wiki/File:Pristis_pectinata_-_Georgia_Aquarium_Jan_2006.jpg">
  David Iliff/Wikimedia Commons (CC BY-SA)
 </a>
</p>

This artist rendition of Kepler 452b shows what the planet could look like.

Scientists Spot Earth's Near-Identical Twin 1,400 Light-Years Away

<div class="related"></div>
<p>
 On the heels of Stephen Hawking and Yuri Milner’s announcement of a
 <a href="http://www.popsci.com/stephen-hawking-yuri-milner-and-frank-drake-announce-worlds-most-extensive-search-alien-life">
  $100-million search
 </a>
 for extraterrestrial life, NASA has just found the planet that, so far, most closely resembles Earth—and it has the potential to host life.
</p>
<p>
 The Kepler Space Telescope, which has discovered over 4,000 potential exoplanets (1,000 of which are confirmed), recently identified Kepler 452b, a planet 1,400 light-years from Earth, according to the
 <a href="http://iopscience.iop.org/1538-3881/150/2/56/article">
  study
 </a>
 published in
 <i>
  The Astronomical Journal
 </i>
 . The planet orbits its sun in 385 days—incredibly close to Earth’s 365-day year. Kepler 452b sits in an ideal “Goldilocks” zone for the creation of life, where temperatures are moderate enough for liquid water.
</p>
<p>
 However, astronomers are skeptical about the possibility of liquid water on Kepler 452b because of its size. The planet’s diameter is 60% larger than Earth’s, so the chances of it having a rocky surface, and therefore containing water, are somewhere between 50 and 62%. If it’s rocky, the planet would have gravity twice as strong as Earth’s, and its mass would be five times as large. In addition, Kepler 452b could have more volcanic activity than Earth. There’s also a chance that the planet could be a large ball of gas, similar to Neptune. But figuring out the composition of Kepler 452b could prove difficult.
</p>
<div class="ad"></div>
<p>
 Dennis Overbye, writing for The New York Times:
</p>
<blockquote>
<p>
 To determine whether Kepler 452b deserves a place on the honor roll of possible home worlds, astronomers have to measure its mass, which requires being close enough to observe the wobbling of the star as it is tugged around by the planet’s gravity. For now that is impossible, as Kepler 452 is 1,400 light-years away.
</p>
</blockquote>
<p>
 Kepler 452b is 1.5 billion years older than Earth. Still, it’s considered the most Earth-like planet we’ve ever found. Even if the planet doesn’t host extraterrestrial life, Kepler 452b could provide us with a glimpse of what Earth will be like a billion years from now.
</p>
<div class="newsletter"></div>
<p>
 Image Credit: NASA/JPL-Caltech/T. Pyle
</p>

<p>NASA has discovered an exoplanet that closely resembles Earth and has the potential to host life.</p>

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