Tag Archives: salamander

Humans could have salamander-like ability to regrow cartilage

Despite not being able to regrow a limb like a salamander, humans have some capacity to restore cartilage in their joints, a study showed. This opens the door to new treatments for joint injuries and diseases like osteoarthritis.

Credit Wikimedia Commons.

The findings, published in Science Advances, run counter to a widely held belief. Because the cartilage cushioning the joints lacks its own blood supply, the body can’t repair damage from an injury or the wear-and-tear of aging.

And that, in part, is why so many people eventually develop osteoarthritis, where broken-down cartilage causes pain and stiffness in the joints. But that lack of blood supply does not mean there’s no regenerative capacity in the cartilage, according to the study.

“Cartilage in human joints can repair itself through a process similar to that used by creatures such as salamanders and zebrafish to regenerate limbs,” according to Duke Health, which helped lead the research.

Salamanders and other animals with regenerative abilities have a type of molecule called microRNA, which helps regulate joint tissue repair. Humans have microRNA too, but the mechanism for cartilage repair is stronger in some parts of the body, the study found. For example, the microRNA molecules are more active in our ankles, and less active in our knees and hips.

“We were excited to learn that the regulators of regeneration in the salamander limb appear to also be the controllers of joint tissue repair in the human limb,” said Duke professor and researcher Ming-Feng Hsueh. “We call it our ‘inner salamander’ capacity.”

The “age” of cartilage, meaning whether proteins have changed the structure or undergone amino acid conversions, depends on its location in the body, the study found. Cartilage is “young” in the ankles, “middle-aged” in the knees, and “old” in the hips. This correlation lines up with how animals regenerate fastest at the furthest tips of their bodies, like tails or the ends of legs.

For years, scientists have known humans do have some regenerative capabilities — when children’s fingertips are amputated, the tip can regenerate when treated correctly. But it was widely believed that these capabilities were limited and that humans were “unable to counteract cumulative damage” to their joints.

The findings could have huge implications for athletes or people with joint injuries. MicroRNA could be injected into joints or developed into medicines that prevent or reverse arthritis, the study said. In the more distant future, it could even “establish a basis for human limb regeneration.”

The next step is to figure out what regulators humans lack that salamanders have — and then see if it’s possible to “add the missing components back,” said Duke professor Virginia Byers Kraus, one of the lead authors of the study. Once those missing components are identified, they could be combined with microRNA to create a “molecular cocktail” aimed at regenerating entire limbs.

“We believe that an understanding of this ‘salamander-like’ regenerative capacity in humans, and the critically missing components of this regulatory circuit, could provide the foundation for new approaches to repair joint tissues and possibly whole human limbs,” Kraus said.

Salamander.

Researchers find salamander-eating plants in Canadian provincial park

In a probable first for North America, researchers at the University of Guelph (U of G), Canada, have discovered meat-eating pitcher plants that dine on young salamanders, not just insects.

Salamander.

Recently metamorphosed spotted salamanders trapped inside the leaves of northern pitcher plants.
Image credits Patrick D. Moldowan et al., (2019),

The bogs in Ontario’s Algonquin Park are rife with deadly plants — if you’re a baby salamander. A new study led by U of G biologist Alex Smith reports on the “unexpected and fascinating case of plants eating vertebrates in our backyard, in Algonquin Park.” The findings, the team explains, may be unique to North America so far.

How the tables have turned

Pitcher plants are well-known for eating animals — but they tend to limit themselves to insects and spiders. This smaller prey is lured into the plants’ bell-shaped leaves, where they are digested in a mixture of rainwater and enzymes. However, until now, nobody had seen these plants capture anything larger. The team found evidence of northern pitcher plants (Sarracenia purpurea purpurea L.) capturing young spotted salamanders (Ambystoma maculatum Shaw) in Canada’s oldest provincial park, Algonquin Park.

The findings are even more surprising, considering that Algonquin is a very popular destination and has been a subject of scientific observations for hundreds of years. Noting how long the park has held this secret — despite generations of visiting naturalists, its proximity to major cities and a highway running through its southern end — Smith said, “Algonquin Park is so important to so many people in Canada. Yet within the Highway 60 corridor, we’ve just had a first.”

The study was borne from a discovery made by then-undergraduate student Teskey Baldwin in 2017 during a U of G field ecology course in the provincial park: he found a salamander inside a pitcher plant. Baldwin is a co-author of the current study. When they returned to monitor pitcher plants in a single pond in the park in the fall of 2018, the team found that roughly 20% of the plants had juvenile salamanders in their pitchers, each about as long as a human finger. Several plants they looked at had more than one captured salamander.

Smith explains that the ponds in this particular bog don’t house fish, making the salamanders a key predator and prey species in the local food webs. The observations also coincided with “pulses” of young salamanders moving onto land after changing from their (aquatic) larval stage. Smith believes that the animals were either lured by insects inside the plants’ pitchers, or they may have entered them in a bid to escape predators.

Some of the trapped salamanders likely died within three days, while others may have lived up to 19 days, the team explains. After expiring, they were broken down by digestive enzymes and other organisms in the water held inside the leaf. Smith said other factors may kill salamanders in pitcher plants, including heat, starvation, or pathogens.

Doesn’t sound like a particularly pleasant fate for the salamanders — so why do the plants put them through all that? Smith says that soil in the bog is relatively nutrient-poor, especially in regards to nitrogen (which is the hard-cap on how much plants can develop in natural environments). Other flesh-eating plants also grow in nutrient-poor environments, he notes, citing sundews and the Venus flytrap.

The only other species of meat-eating pitcher plant (native to Asia) consumes mostly insects and spiders, and occasionally small birds and mice. Smith said the Algonquin Park discovery opens new questions for biologists: are the salamanders a key prey species of the plants? Are the pitcher plants the main predators of these amphibians? And do the two species compete for insects — in which case, might the salamanders outcompete the plants?

“I hope and imagine that one day the bog’s interpretive pamphlet for the general public will say, ‘Stay on the boardwalk and watch your children. Here be plants that eat vertebrates,”‘ Smith quips.

The paper “Salamanders as rich prey for carnivorous plants in a nutrient‐poor northern bog ecosystem” has been published in the journal Ecology.

A unisexual female salamander. Credit: Robert Denton.

When you don’t need sex, like these salamanders, you get lazy. And that’s a problem in the face of climate change

A unisexual female salamander. Credit: Robert Denton.

A unisexual female salamander. Credit: Robert Denton.

Mole salamanders are stout-bodied salamanders endemic to North America which are fascinating for a variety of reason. For one, their short stubby arms and little faces with protruding cartoonish eyes makes them some of the cutest amphibians you’ll see. They’re also facultatively paedomorphic, meaning that they may retain larval characteristics as adults and continue to live in the water or metamorphosis and lead a terrestrial life. In other words, these Peter Pans can choose whether or not to become adults. And it gets weirder.

Sex: more than meets the eye

One mole salamander variety is comprised of all females which reproduce asexually by cloning. This strategy seems successful given the unisexual mole salamanders have been around for six million years but one recent study suggests these adorable critters might be at a disadvantage compared to their sex-driven cousins in the face of climate change. Simply put, not having sex makes them lazier, the study seems to conclude.

In Europe, an invasive pathogenic fungus (Batrachochytrium salamandrivorans; Bsal) is wreaking havoc for the salamander and newt biodiversity. In 2016, the U.S. federal government embargoed 201 species to keep amphibians potentially infected with the skin-eating diseases from starting an outbreak at the other end of the pond as well. Despite these best efforts, the fungus might end up infecting North American species. Moreover, climate change and habitat fragmentations make amphibian populations in the U.S. even more vulnerable.

Bearing these threats in mind, biologist Rob Denton and colleagues from Ohio State University are studying the various reproduction strategies of mole salamanders to see what are the advantages and disadvantages for each.

“Salamander-specific chytrid (Bsal) fungus is a huge concern here in the United States, because we have such a wonderful hotbed of salamander diversity compared to the rest of the world,” Dentold told The Smithsonian. “Preventing that outbreak from happening here is really important and part of that is understanding the differences on a species level between these animals—how they interact with each other and how they interact with their landscape.”

The unisexual salamanders, known as Ambystoma, do have a “little bit” of sex, to be fair. When the weather is ripe, meaning wet (they love the rain), these females will come in contact with pockets of sperm deposited by males from either of the five known mole salamander species. “Usually that sperm is just used to tell their body, ‘hey, it’s time to make eggs,’” Denton says. “Sometimes that sperm genome actually sneaks into that next generation,” he added. No one knows yet how this happens.

To test whether this cloning evolutionary strategy is more advantageous than the procreating variety, the researchers placed 17 small-mouth salamanders and 21 unisexual individuals on a treadmill. Every three minutes, the salamanders were given a break from their workouts after a researcher would flip them on their backs. The time it took for each salamander to rebound on their feet was recorded. The longer it took, the more tired the salamander was, the researchers reckoned. This experiment revealed that the sexual salamanders could travel four times the distance asexual salamanders could.

The team then left the lab to assess fitness in the wild. Mole salamanders spend all of their early life in shallow poles from which they emerge only after they’ve metamorphosized from their humble tadpole beginnings. Once they become adults, the sexual salamanders will do some soul searching but, ultimately, will return back to their original breeding pools where they were born to lay eggs. It follows that in any given pond you’ll find a similar genetic makeup.

However, some small-mouth salamanders will break the pattern and land in other pools. So Denton and colleagues set up traps in ponds formed by melted snow and using samples collected from captive individuals they mapped the diversity of the pond. This told them how far an individual between ponds and how it compared to the unisexuals.

The results suggest that in the wild small-mouth salamanders travel twice and a half as far as their counterparts, as reported in the journal Functional Ecology

Not having sex has its perks. For instance, the unisexual salamanders go out less and hence the risk of catching an infectious disease, like Bsal, drops. On the flipside, it’s genetic diversity that could help these salamanders if an outbreak occurs. This is how Tasmanian devils were able to rebound in the face of evil facial tumor disease (DFTD), an 100% kill rate disease which wiped out 80 percent of the population. Then there’s climate change which affects habitats and available resources. If their habitat dries up, unisexual mole salamanders might not make it but their sexual counterparts might, simply because they’re less lazy it seems. So there’s more to sex than meets the eye.

“Maybe the best explanation for why sexual salamanders travel so far is because they have to: On a large landscape with few places to breed, the animals that can cross that distance are the ones that survive and reproduce,” Denton said.

“Perhaps the more interesting question is why the all-female salamanders don’t go very far, and we think that has to do with the physiological costs of not having sex. Essentially, not mixing up your genomic material often enough likely causes some problems for genes that you need to make energy.”

Scientists find Salamander in Amber in the Caribbean

Finding insects, plants or even dinosaur feathers trapped in amber s rare and exciting. But finding a fossil salamander in amber… that’s something else – it’s actually unique. But the salamander’s unfortunate fate sparked immediate interest from researchers: not only is it a unique finding, but it’s from a never-before seen species of salamander, and it comes from the Caribbean – a place where there are no salamanders today.

GEORGE POINAR, JR., COURTESY OF OREGON STATE UNIVERSITY

The little creature suffered a most unfortunate fate. It was only a baby when it got into a skirmish of some kind and its back limb got torn off. Then, through a series of unknown events, it somehow got trapped in resin, where it remained stuck for the next 20-30 years. But one salamander’s misfortune is another paleontologist’s fortune.

“There are very few salamander fossils of any type, and no one has ever found a salamander preserved in amber,” said George Poinar, Jr., a professor emeritus in the OSU College of Science, in a press release. “And finding it in Dominican amber was especially unexpected, because today no salamanders, even living ones, have ever been found in that region.”

Salamander fossils of all types are rare. The amphibians with a lizard-like appearance are found in the Holarctic and Neotropical regions, though some researchers believe that they previously lived in other areas as well – and this is a fine piece of evidence.

The new species has been called Palaeoplethodon hispaniolae by the authors of the paper, and it adds more hint not only about the biology of the Caribbean area, but also about its geology and climate; salamanders require very specific conditions to be able to thrive, and finding a salamander basically ensures that those conditions were fulfilled at one point in time.

The family in which Palaeoplethodon belonged is fairly common in North America, especially in the Appalachian mountains, but this ancient species has some significant differences from the salamanders we see today. For starters, it didn’t have the distinctive “salamander legs”, and instead sported a kind of webbing that might have made it a worse climber.

But the species also raises some important questions: why is it that all salamanders went extinct in the Americas? Was there some predator that simply killed them all, some climatic event? Or did they simply drift with the tectonic movement of the Americas? We’re still far away from answering those questions, but this little guy might provide some valuable hints.

Car-sized Salamander roamed Portugal 230 million years ago

Paleontologists have found the remains of a “super salamander” – a previously unknown car-sized species of early amphibian. The predatory salamander likely feasted on fish and even small dinosaurs.

“This new amphibian looks like something out of a bad monster movie. It was as long as a small car and had hundreds of sharp teeth in its big flat head, which kind of looks like a toilet seat when the jaws snap shut,” said Dr Steve Brusatte, of the University of Edinburgh’s School of GeoSciences, who led the study.

An artist’s impression of the giant carnivorous amphibian Metoposaurus algarvensis, discovered by researchers from the University of Edinburgh Photograph: University of Edinburgh/PA

 

Scientists now know quite a lot about these creatures – they lived together in large numbers, grew up to more than 2 meters, and lived in low-lying lakes and rivers during the Late Triassic Period, the first major stage of the Mesozoic. Researchers can say for sure that it is a new species, judging by its jaw structure and parts of the skull where the spinal cord meets the brain.

“We have a mass graveyard of these things that looks like hundreds of individuals all jumbled together,” Steve Brusatte, who led the study, told The Washington Post in a phone interview. “These things lived and died together. We have skeletons of many different individuals, adults and children … We know what it ate, how it moved and what it was like when it was alive.”

Image credits: Steve Brusatte.

The species is now called Metoposaurus algarvensis, named after the Algarve province in southern Portugal where it was discovered. The area where they found it likely contains many more still undiscovered fossils, but to date, only a fraction of them were actually excavated.

“There is a real jumble of bones in there, but it’s been challenging to remove them because they come from a bone bed that is about half a metre thick and goes into the hillside,” said Steve Brusatte, who led the study. The team have spent two field trips excavating bones from the site and hope to return to collect more of the remains.

For all its spectacular size, Metoposaurus algarvensis had puny legs, which indicates that it mostly hunted in the water, as it wasn’t specially adapted to land. It was likely quite vulnerable on land. This is the first member of the Metoposaurus group found in the Iberian peninsula (Portugal and Spain). But despite their strange looks, they were likely quite common in the area.

“It looks like an alien — it looks like it’s from another world,” Brusatte said. “But these animals weren’t rare at all.” Indeed, big amphibians dominated planet Earth until volcanic activity associated with Pangea’s break-up paved the way for the T. Rex and its dino compatriots.

Journal Reference: Stephen L. Brusatte, Richard J. Butler, Octávio Mateus & J. Sébastien Steyer. A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls. DOI:10.1080/02724634.2014.912988

Salamaders show that being different means staying alive

Remember when we were kids and everyone picked on the ones who looked peculiar in a way or another starting from their hair color and ending with their height? Well, whether you were a “victim” or a “predator” find out that there is a reason why some individuals of a species look at least a bit different. It simply makes predators look away.

As the researchers from the University of Tennessee discovered, birds are most likely to attack those salamanders that look like the majority. The scientists wanted to see how Blue Jays would react facing the prevalence of a dorsal stripe among a group of salamanders.

The discovery is quite intriguing as usually throughout a species’ evolution those traits that make an individual stronger, more able to find food or escape predators are the ones to “survive” while the other ones disappear. As an example those giraffes who had a longer neck were more likely to breed so that in the end the entire species possesses this trait.

However, in this case it seems that being different might keep predators away, thus allowing the individual to survive and breed. The regular back pattern of the salamanders makes them similar to the environment they live in, which makes them hard to see. The striped salamanders released by the researchers in the first day outnumbered the unstriped by nine to one or the other way around. On test days the numbers were evened out but the Blue Jays proved to prefer to attack those models that had seen most before that day. The birds were used to concentrate in order to spot a salamander on the forest floor, this constant effort making them not even notice the ones who were not striped.

So, it seems that the experiment proves a new theory: predators seem to avoid those individuals who look peculiar. Too bad it does not work for bullies too!

source:BioMed Central

Thriving Hybrid Salamanders

 

hybrid

So a new study conducted by UC Davis research revealed interesting things from interbred salamanders, results that go against what was the dominant idea about interbread species.

The salamander experts studied the survival rates and genetic makeup of three types of salamanders: native California tiger salamanders (Ambystoma californiense), which are protected under the U.S. Endangered Species Act; barred tiger salamanders that were introduced in California from Texas in the 1950s (Ambystoma tigrinum mavortium); and the hybrid offspring born when the two species mated. They found that hybrids did better when released into their habitat than the natural species. The belief was that hybrids are not as fit as their parents and they are weaker.

But hybrids favour natural selection and this may be an answer for the salamander endagered population. Some think that they are just threats to the native salamanders (awesome salamander here). But this is a thing to look to in the future since it is harder and harder for numerous species with the dissapearance of their habitat.

It is bad that people consider hybrids to be less valuable than the so called pure species. We find it very easy to forget where we came from and how the human species evolved from microscopic ancestors and later from larger creatures thanks to endless interbreeds. People should understand that hybrids exist and they are part of natural selection and they should be regarded as beings, equal to and just as valuable as “pure breeds”.