岡部碩道 via Wikimedia Commons // Public Domain
岡部碩道 via Wikimedia Commons // Public Domain

Scientists Find Genetic Root of Limb Regrowth

岡部碩道 via Wikimedia Commons // Public Domain
岡部碩道 via Wikimedia Commons // Public Domain

If you’ve ever been jealous of a lizard’s ability to regrow its tail, take heart: Scientists are one step closer to understanding how it works and say that one day we might be able to do the same thing. (With arms and legs, that is. Not tails. Be realistic.) They published their findings in the journal PLOS One.

Few things are cooler (and more useful) than the ability to regenerate lost limbs. So it’s not too surprising that scientists are really, really interested in how it all works. Researchers at the MDI Biological Laboratory in Maine were especially curious about the inner workings of a process called blastema formation, in which new limb tissue begins to grow at the site of a wound. They decided to look at three species with appendage-regenerating superpowers: the zebrafish (Danio rerio), the bichir fish (Polypterus senegalus) and Ambystoma mexicanum, better known as the Mexican salamander or axolotl. Despite this common trait, these species are evolutionarily distant from one another, having diverged about 420 million years ago.

In order to study limb regrowth, the scientists had to start with limb loss. They brought groups of axolotls, bichirs, and zebrafish into the lab and surgically amputated at least one appendage on each animal—legs for the axolotls and fins for the fish. Then they let the animals rest, collecting tissue samples from the wound sites every few days. They ran the tissue samples through a series of genetic tests, examining several types of each animal’s RNA in search of regrowth-related code.

Not only did they find that code, but they found the same code in all three species—a surprising and exciting twist. "It was a fantastic feeling," co-author Benjamin L. King said in a press statement. "We didn't expect the patterns of genetic expression to be vastly different in the three species, but it was amazing to see that they were consistently the same."

Understanding blastema formation could help explain the complicated science of wound and other tissue healing, and may someday lead to treatments for people who have suffered injuries or burns.

Co-author Voot P. Yin also notes that the regrowth mechanism they found may exist in many other species as well—including humans.

"Limb regeneration in humans may sound like science fiction, but it's within the realm of possibility," Yin said. "The fact that we've identified a genetic signature for limb regeneration in three different species with three different types of appendages suggests that nature has created a common genetic instruction manual governing regeneration that may be shared by all forms of animal life, including humans."

So don’t give up on your lizard dreams just yet.

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How Bats Protect Rare Books at This Portuguese Library
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Visit the Joanina Library at the University of Coimbra in Portugal at night and you might think the building has a bat problem. It's true that common pipistrelle bats live there, occupying the space behind the bookshelves by day and swooping beneath the arched ceilings and in and out of windows once the sun goes down, but they're not a problem. As Smithsonian reports, the bats play a vital role in preserving the institution's manuscripts, so librarians are in no hurry to get rid of them.

The bats that live in the library don't damage the books and, because they're nocturnal, they usually don't bother the human guests. The much bigger danger to the collection is the insect population. Many bug species are known to gnaw on paper, which could be disastrous for the library's rare items that date from before the 19th century. The bats act as a natural form of pest control: At night, they feast on the insects that would otherwise feast on library books.

The Joanina Library is famous for being one of the most architecturally stunning libraries on earth. It was constructed before 1725, but when exactly the bats arrived is unknown. Librarians can say for sure they've been flapping around the halls since at least the 1800s.

Though bats have no reason to go after the materials, there is one threat they pose to the interior: falling feces. Librarians protect against this by covering their 18th-century tables with fabric made from animal skin at night and cleaning the floors of guano every morning.

[h/t Smithsonian]

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Honey Bees Can Understand the Concept of Zero
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The concept of zero—less than one, nothing, nada—is deceptively complex. The first placeholder zero dates back to around 300 BCE, and the notion didn’t make its way to Western Europe until the 12th century. It takes children until preschool to wrap their brains around the concept. But scientists in Australia recently discovered a new animal capable of understanding zero: the honey bee. According to Vox, a new study finds that the insects can be taught the concept of nothing.

A few other animals can understand zero, according to current research. Dolphins, parrots, and monkeys can all understand the difference between something and nothing, but honey bees are the first insects proven to be able to do it.

The new study, published in the journal Science, finds that honey bees can rank quantities based on “greater than” and “less than,” and can understand that nothing is less than one.

Left: A photo of a bee choosing between images with black dots on them. Right: an illustration of a bee choosing the image with fewer dots
© Scarlett Howard & Aurore Avarguès-Weber

The researchers trained bees to identify images in the lab that showed the fewest number of elements (in this case, dots). If they chose the image with the fewest circles from a set, they received sweetened water, whereas if they chose another image, they received bitter quinine.

Once the insects got that concept down, the researchers introduced another challenge: The bees had to choose between a blank image and one with dots on it. More than 60 percent of the time, the insects were successfully able to extrapolate that if they needed to choose the fewest dots between an image with a few dots and an image with no dots at all, no dots was the correct answer. They could grasp the concept that nothing can still be a numerical quantity.

It’s not entirely surprising that bees are capable of such feats of intelligence. We already know that they can count, teach each other skills, communicate via the “waggle dance,” and think abstractly. This is just more evidence that bees are strikingly intelligent creatures, despite the fact that their insect brains look nothing like our own.

Considering how far apart bees and primates are on the evolutionary tree, and how different their brains are from ours—they have fewer than 1 million neurons, while we have about 86 billion—this finding raises a lot of new questions about the neural basis of understanding numbers, and will no doubt lead to further research on how the brain processes concepts like zero.

[h/t Vox]

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