Latest news with #salamander
France 24
10-07-2025
- Science
- France 24
Mexican fishermen join fight to save extraordinary amphibian
The achoque, also known as the Lake Patzcuaro salamander, is a lesser known relative of the axolotl, the small friendly- faced amphibian battling extinction in Mexico City. Overfishing, pollution and reduced water levels in Lake Patzcuaro, its only natural habitat, mean that the achoque is listed as critically endangered by the International Union for Conservation of Nature. In an attempt to prevent it disappearing, biologists from Michoacana University decided to pay the local Indigenous community of San Jeronimo Purenchecuaro to help the achoque to reproduce. Correa, who knows the lake in the western state of Michoacan like the back of his hand, has a new job as an amphibian egg collector. Now in his 60s, he remembers when the waters teemed with fish and there was no need to worry for the salamander. "There used to be a lot of achoques," he told AFP. "Now the new generation doesn't know about it." From lab to lake After the eggs are collected, biologist Rodolfo Perez takes them to his laboratory at Michoacana University to hatch, in the hope of giving the achoques a better chance of surviving. After the hatchlings have grown enough, they are moved to the community's achoque protection reserve, where the fishermen care for them until they are ready to be released into the lake, said Israel Correa, a relative of Froylan Correa. The achoque belongs to the Ambystoma group, keenly studied by scientists for an extraordinary ability to regenerate mutilated limbs and parts of organs such as the brain and heart. If one loses a tail, it quickly grows another. That has made the salamanders a subject of fascination for scientists hoping to learn lessons that could apply to humans. Since pre-Hispanic times, the achoque has been a source of food as well as a remedy used by Indigenous people for respiratory illnesses. Its skin color allows it to blend into its natural habitat. According to a local legend, the achoque was first an evil god who hid in the lake mud to escape the punishment of other deities. Perez is trying to hatch as many eggs as possible with the help of the locals to prevent its extinction. "It's been a lot of work," he said, adding that the biggest challenge is finding money to compensate the fishermen, since the achoques require constant care. Collaboration between scientists and the local community has helped to stabilize the achoque population, according to the researchers. There are an estimated 80 to 100 individuals who live in a small part of the lake, said Luis Escalera, another biologist at Michoacana University. The number, however, is "much lower than it was 40 years ago," he said. For the fishermen fighting to save them, it is a labor of love. "We can't miss a day without coming because otherwise they'll die," Israel Correa said at the achoque protection reserve on the shores of Lake Patzcuaro.
WIRED
17-06-2025
- Science
- WIRED
Scientists Discover the Key to Axolotls' Ability to Regenerate Limbs
Jun 17, 2025 5:00 AM A new study reveals the key lies not in the production of a regrowth molecule, but in that molecule's controlled destruction. The discovery could inspire future regenerative medicine. Axolotls in Professor James Monaghan's laboratory. Photograph: Alyssa Stone/Northeastern University The axolotl seems like something out of science fiction. This perpetually youthful-looking Mexican salamander possesses a superpower that defies biology as we know it: the ability to regenerate entire limbs, parts of its heart, and even its spinal cord. But how does an amputated limb know whether to regenerate an entire arm from the shoulder down or just a hand from the wrist? This mystery of 'positional identity' has fascinated scientists for decades. A team at Northeastern University, led by James Monaghan, has unraveled a key piece of this biological puzzle. In a study published in Nature Communications, the researchers reveal an elegant molecular mechanism that acts like a GPS coordinate system for regenerating cells. Surprisingly, the secret lies not in producing more of a chemical signal, but in how quickly it is destroyed. Monaghan's lab houses about 500 axolotls cared for by a team ranging from undergraduate students to postdocs. 'Raising axolotls involves managing a complex aquatic system and being patient, as they reach sexual maturity within a year. It's slower than with other model organisms, but also more exciting. In many experiments, the team is exploring completely new terrain,' Monaghan says. For more than two decades, Monaghan's lab has been studying the axolotl to understand how it regenerates complex organs such as its limbs, spinal cord, heart, and tail. His lab's research focuses on uncovering why nerves are essential to this process and what unique cellular properties allow axolotls to regenerate tissues that other animals cannot. These findings could transform our understanding of bodily regeneration and have important applications in regenerative medicine. James Monaghan at work in the lab. Photograph: Alyssa Stone/Northeastern University 'For years we've known that retinoic acid, a derivative of vitamin A, is a crucial molecule that screams to cells 'build a shoulder!'' explains Monaghan. 'But the puzzle was how the cells in the regenerating limb-stump controlled their levels so precisely to know exactly where they were on the axis from shoulder to hand.' To unpick this mystery, the team focused on a cluster of stem cells that form at the wound site after a limb is lost in animals like the axolotl that are capable of regeneration. Known as the blastema, it's this base of stem cells that then orchestrates regeneration. The prevailing theory was that differences in retinoic acid production might explain why a shoulder (proximal) amputation leads to an entire limb being regenerated, while a wrist (distal) amputation only regenerates the hand. 'Our big surprise was to discover that the key was not in how much retinoic acid was produced, but in how it was degraded,' says Monaghan. The team discovered that cells in the distal part of the limb, the wrist, are awash in an enzyme called CYP26B1, whose sole function is to destroy retinoic acid. In contrast, cells in the shoulder have hardly any of this enzyme, allowing retinoic acid to accumulate to high levels. This difference creates a chemical gradient along the limb: lots of retinoic acid in the shoulder, little in the wrist. It is this gradient that informs cells of their exact location. In humans, this pathway of cellular plasticity is absent or closed. 'Therefore, the great challenge is to understand how to induce this blastemal state in our cells, a key transient structure in regeneration. If achieved, it would be possible for our cells to respond again to positional and regenerative signals, as they do in the axolotl,' explains the researcher. Tricking the Cells Into Over-Regenerating To confirm their discovery, the researchers conducted an experiment. They amputated axolotl legs at the wrist and administered a drug called talarozole, which inhibits the CYP26B1 enzyme. By 'turning off the brakes,' retinoic acid accumulated to extremely high levels in a place where it normally shouldn't. As a result the wrist cells, 'confused' by the high concentration of retinoic acid, interpreted position as being the shoulder. Instead of regenerating a hand, they proceeded to regenerate a complete, duplicated limb. 'It was the ultimate test,' Monaghan says. Different limb regenerations of axolotls treated with talarozole. Photograph: Alyssa Stone/Northeastern University The team went a step further to identify which genes were activated by these high levels of retinoic acid. They discovered a master gene that was specifically activated in shoulder areas: Shox . An abbreviation of 'short stature homeobox gene,' Shox is so called because mutations to it in humans cause short stature. 'We identified Shox as a critical instruction manual in this process,' Monaghan explains. 'It's the gene that tells developing cells to 'build the arm and forearm bones.'' To confirm this, the team used Crispr gene-editing technology to knock out the Shox gene in axolotl embryos. The resulting animals had peculiar limbs: normal-sized hands and fingers, but significantly shorter and underdeveloped arms and forearms. This demonstrated that Shox is essential for shaping proximal, but not distal, structures, revealing that regeneration uses distinct genetic programs for each limb segment. This study not only solves a long-standing mystery of regenerative biology, but also provides a molecular road map. By understanding how the axolotl reads and executes its genetic instructions for regeneration, scientists can begin to think about how, someday, we might learn to write our own genetic instructions. An axolotl. Photograph: Alyssa Stone/Northeastern University 'The axolotl has cellular properties that we want to understand at the deepest level,' says Monaghan. 'While regeneration of a complete human limb is still in the realm of science fiction, each time we discover a piece of this genetic blueprint, such as the role of CYP26B1 and Shox , we move one step closer to understanding how to orchestrate complex tissue repair in humans.' To bring this science closer to clinical applications, one crucial step is to succeed in inducing blastema formations of stem cells at sites of amputation in humans. 'This is the 'holy grail' of regenerative biology. Understanding the minimal components that make it up—the molecular signals, the cellular environment, the physiological conditions—would allow us to transform a scar into a regenerative tissue,' explains Monaghan. In his current research, there are still gaps to be filled: how the CYP26B1 gradient is regulated, how retinoic acid connects to the Shox gene, and what downstream factors determine the formation of specific structures, such as the humerus or radius bones. From Healing to Regeneration Monaghan explains that axolotls do not possess a 'magic gene' for regeneration, but share the same fundamental genes as humans. 'The key difference lies in the accessibility of those genes. While an injury in humans activates genes that induce scarring, in salamanders there is cell de-differentiation : the cells return to an embryonic-like state, where they can respond to signals such as retinoic acid. This ability to return to a 'developmental state' is the basis of their regeneration,' explains the researcher. So, if humans have the same genes, why can't we regenerate? 'The difference is that the salamander can reaccess that [developmental] program after injury.' Humans cannot—they only access this development pathway during initial growth before birth. 'We've had selective pressure to shut down and heal,' Monaghan says. 'My dream, and the community's dream, is to understand how to make the transition from scar to blastema.' James Monaghan. Photograph: Alyssa Stone/Northeastern University Monaghan says that, in theory, it would not be necessary to modify human DNA to induce regeneration, but to intervene at the right time and place in the body with regulatory molecules. For example, the molecular pathways that signal a cell to be located in the elbow on the pinky side—and not the thumb—could be reactivated in a regenerative environment using technologies such as Crispr. 'This understanding could be applied in stem cell therapies. Currently, laboratory-grown stem cells do not know 'where they are' when they are transplanted. If they can be programmed with precise positional signals, they could integrate properly into damaged tissues and contribute to structural regeneration, such as forming a complete humerus,' says the researcher. After years of work, understanding the role of retinoic acid—studied since 1981—is a source of deep satisfaction for Monaghan. The scientist imagines a future where a patch placed on a wound can reactivate developmental programs in human cells, emulating the regenerative mechanism of the salamander. Although not immediate, he believes that cell engineering to induce regeneration is a goal already within the reach of science. He reflects on how the axolotl has had a second scientific life. 'It was a dominant model a hundred years ago, then fell into disuse for decades, and has now reemerged thanks to modern tools such as gene editing and cell analysis. The team can study any gene and cell during the regenerative process. In addition, the axolotl has become a cultural icon of tenderness and rarity.' This story originally appeared on WIRED en Español and has been translated from Spanish.
Washington Post
10-06-2025
- Science
- Washington Post
These glowing axolotls may hold the secret to human limb regeneration
With a silly smile and frilly gills, the axolotl has wriggled its way into the hearts of millions, becoming a popular aquarium pet and pop-culture icon in video games, children's books and toy stores. But this adorable species of salamander is also helping researchers investigate a serious medical mystery: Could the human body be coaxed to regrow a severed arm or leg? Scientists are turning to the axolotl because it is an expert at regeneration. After losing a limb, an adult axolotl can grow it back fresh and new. In a study published in the journal Nature Communications on Tuesday, scientists used axolotls genetically engineered to glow in the dark to understand the molecular underpinnings of this amazing trait. 'This species is special,' said James Monaghan, a Northeastern University biologist who led the research. They've 'really become the champion of some extreme abilities that animals have.' Although critically endangered in the wild in Mexico, axolotls have been kept and studied in labs since the 19th century. They are known for being, naturally, forever young. Unlike other amphibians such as frogs, axolotls never go through full metamorphosis, instead retaining into adulthood certain juvenile characteristics such as external gills and webbed feet that make them look so weirdly cute to their human admirers. The species is also a comeback king, able to regrow not only lost limbs but also tissue in the heart, lungs and even the brain. One marvel is that to enable a body part to grow back, the cells responsible for that growth need to somehow register where they are on the body. If an amputation is at the upper arm, for example, they have to re-create upper arm, then the lower arm and finally, the hand. But if it's at the lower arm, the cells have to know to grow back just the lower arm and hand. 'Salamanders have been famous for their ability to regenerate arms for centuries,' Monaghan said. 'One of the outstanding questions that has really plagued the field is how a salamander knows what to grow back.' For their study, Monaghan and his colleagues investigated a tiny molecule called retinoic acid that seems to be responsible for this careful choreography. A derivative of vitamin A, it is known for its regenerative ability and is related to retinol found in skin-care products. 'Anyone that watches TV for 30 minutes watches a skin commercial with retinol,' Monaghan said. His team worked with axolotls that had been genetically engineered so that their tissue glows in the presence of the acid, allowing real-time tracking of its presence. Then, in the name of vitally important science, the researchers did something that might strike some axolotl fans as shocking: they severed axolotl arms. Monaghan said his team anesthetized the axolotls before the procedure and closely monitored their health. 'Importantly, they don't show signs of pain or distress after limb amputation the way mammals might, and they regenerate fully within weeks,' he said. When given a drug that blocks an enzyme responsible for breaking down retinoic acid, the axolotls regrew their missing limbs incorrectly, with an upper arm sprouting out where a forearm should be. A control group of animals that did not receive the drug regenerated normally. The work suggests that retinoic acid acts like a GPS device, helping cells to determine their location: the higher the concentration of the acid, the closer to the center of the body. The chemical appears to activate a gene or genes within the cells to regulate limb growth. 'While we are still far from regenerating human limbs, this study is a step in that direction,' said Prayag Murawala, an assistant professor at MDI Biological Laboratory in Maine. His lab helped Monaghan produce the genetically engineered animals used in the study, but was otherwise not involved in the research. 'Better understanding of gene regulatory circuit is essential if we have to re-create this in humans,' Murawala said. When it comes to human limb regeneration, Monaghan noted that every cell already contains in its DNA the blueprints to rebuild body parts. 'We all have the same genes,' he said. 'We've all made these limbs when we were embryos.' The question now is figuring out the right chemical signals to unlock those early developmental instructions in humans after birth, as axolotls are able to do. 'It's one of the oldest questions in biology, but it's also the most futuristic-looking,' he said. When Monaghan began his research two decades ago, 'most people didn't know what an axolotl was.' But for the past decade the animal has been an obsession for kids, boosted in popularity after debuting in the video game 'Minecraft' in 2021. 'It's a little surreal,' he said. 'You just see axolotls at the airport, axolotls at the mall. My kids are coming home with axolotl toys all the time, because people know what I do.'
Forbes
23-05-2025
- General
- Forbes
How Vermont Rallied To Save Tiny Salamanders From Becoming Roadkills
A blue-spotted salamander. Two underpasses costing $330,000 in the Lake Champlain Valley are a model effort in how a Vermont community rallied behind thousands of tiny salamanders scurrying over the road yearly to safeguard the wildlife migrations. 'If you tell somebody an eight-inch long, purple and yellow salamander will come out of the ground in the thousands every spring and they've never seen it before, most people will tell you that you're crazy. And yet, that's exactly what's happening every year,' said Jens Hilke, conservation planner at Vermont Fish & Wildlife Department. A salamander in the town of Monkton pauses while crossing the road this spring in Vermont. Most amphibians in Vermont need to live in both dry lands like forests and wetlands separated by terrain for two seasonal migrations. 'Every spring, stunning numbers of frogs and salamanders migrate from their terrestrial overwintering habitats to their aquatic breeding habitats,' explained VTF&W herpetologist Luke Groff. Spotted salamander. These predictable migrations to seasonal habitats enable ecopassages to be highly effective for intercepting and guiding the creatures through safer passageways. 'There's a migratory path that has to happen seasonally. That's highly synchronous, resulting in many, many animals making that migration simultaneously. And yet those animals outside of that time of the year are extremely difficult to find. They're underground, they're not visible. They're under rocks and logs. They're dormant for many, many months hiding out in the cold winters, especially here in Vermont,' said Brittany Moser, assistant professor at the University of Vermont's Rubenstein School of Environment and Natural Resources. Noticing action was needed to protect the salamanders from being decimated under tire wheels along a main road, Vermont locals in Monkton decided to safeguard the wildlife there. Eastern red-backed salamander that is found in Vermont. The community around Monkton is home to just over 2,000 people and many forest area amphibians. It sits in picturesque Addison County, nestled in the Lake Champlain Valley between the Adirondacks and Green Mountains, just over an hour's drive east of Montpelier. The community and members of the Lewis Creek Association and the Monkton Conservation Commission engaged in fundraising and received grants from the Vermont Agency of Transportation and VTF&W to create an amphibian crossing. They wanted to offer protection for large numbers of salamanders being killed while crawling across Moncton Road during their annual treks in the spring and fall. Vermont is home to many different types of rare and common salamanders that can live for 20 years. Some are only three inches long. Others can grow up to six inches in length. The state has the blue-spotted salamander that grows no more than five inches and consumes beetles, earthworms, mites, mosquito larvae, spiders and slugs. From from three to five inches long, the Eastern red-backed salamander is the color of red bricks except for its grayish, granite-colored belly. Vermont also has four-toed salamanders and lots of frogs. A Spring Peeper. One common frog, also prone to being run over, is a minuscule light brownish Spring Peeper. The from is from one to two inches long and named for the peeping sound it makes while exhaling. Side of the Monkton amphibian crossing shows boards to guide wildlife through the culvert underpass ... More opening. Funding was raised to create two culvert tunnels with a concrete fence/wall on both sides. The wall was built a few feet high to keep amphibians within safe passage areas to guide them to the other side of the road. When they reach the wall, they can walk alongside it since it is too high for many to climb. 'Hopefully they choose the right direction. If they choose the wrong direction, they get turned around. They come back and then they go through the structure into the wetland. Then they spend the summer in the wetland. In the fall, they do it in reverse. In terms of the salamanders, it's about a movement of perhaps 600 feet. And it [the spring migration] happens on the first rainy nights above freezing every year,' Hilke said. The tunnel floors must be dry and moist. Dirt is placed inside to ensure there is no running water. Above the tunnels are metal grates built into the road to allow for moisture and moonlight to help the creatures along their way. The grates were designed to stay in place when passed over by snowplows. Grates allow sunlight and moisture to pass through the culverts. Light is critical to help wildife ... More find their way through the tunnels. Moser underscored that even though the migration area may be viewed as short distance of 600 feet that journey is arduous for two-inch and five-inch creatures. 'When you actually scale it to the size of the organism, it's a pretty epic migration for a critter of that size to make, especially given the terrain and the obstacles like the road,' she noted. The inside of the culverts is a simulated natural environment with logs, rocks, flat objects and other debris where salamanders can rest during their migration. A salamander stops in the middle of the Monkton road and is in danger of being run over. Moser worked with Matthew Marcelino (a herpetologist and quantitative ecologist who recently earned his doctorate degree at University of Vermont) on a key study measuring the effectiveness of the Monkton amphibian crossings. A unique aspect of these crossing is data was collected about amphibian mortality rates before and after underpass construction. Moser noted that many wildlife sustainability projects move quickly once funding is obtained without capturing mortality data before construction to demonstrate effectiveness. The numbers in Vermont tell a story of success. Before the Monkton crossing was built there were 1,000 amphibians killed on the road during two spring nights, Marcelino noted. 'After the construction of the underpasses, we noticed there was an 80% decrease in total amphibian mortality. So that's literally saving 800 of those amphibians, which is a huge number. If you think about if that was mammals or birds, that number alone really shows their efficacy [of the road culverts],' he added. Researchers also probed to determine if the crossings helped amphibians that could climb up over the concrete walls such as spring peeper frogs and gray treefrogs. Amphibian Deaths Prevented due to Monkton Wildlife Crossings Data indicated a 73% drop in the number of climbing amphibians during migration due to the tunnels. Which Marcelina called a 'huge' amount in those creatures saved from being run over on the road. The culverts are also providing safe conduct for other wildlife seen on cameras such as raccoons, bobcats and bears. A black bear (left) and a bobcat (right) are captured on video using the Monkton amphibian crossing ... More late at night and in the early morning hours. Moser said it is important for transportation planners to realize they can incorporate wildlife crossings into existing roadway projects to lower costs of creating standalone safe animal passages and making travel safer for people and wildlife at the same time. 'There's a benefit to knowing about these things and having them on the radar and to be able to work them into existing road updates," she added. A salamander attempts migrate over the road pavement at night without using the Monkton wildlife ... More underpass. Road kills can have a larger impact on salamanders and other amphibian populations because of how they reproduce. In the case of Vermont's salamanders, they are leaving their winter hibernation to reproduce across the way in marshy areas with water. Once hatched in the water, the young ones must migrate across the road to the dry land to live during colder winter months. 'For some of these species, the [roadway] mortality is a huge impact on population viability if we're losing these animals that are of reproductive age. If they're moving, it's because they're moving to reproduce. Now, we're not just losing them. We're losing their entire reproductive contribution for the year, which could be, depending on the species, many tens or hundreds of eggs that they're contributing,' Moser said. 'So these underpasses, they're there all year round and supporting both directions of migration—adults on the way to the breeding pond and then juveniles as they come up onto land.' Like salamanders, turtle populations can be severely impacted by being run over while trying to cross roads. 'Certain turtle species, for example, are very late to sexual maturity. So you can have just a few hits of female turtles and wipe out an entire population with just a few turtles hit on the roads. Our populations of reptiles and amphibians are in danger,' Hilke noted. A cost benefit analysis of wildlife crossings for amphibians, in particular, should consider the endangerment of entire populations due to road mortality. 'That's different than thinking about deer or moose. We're not going to lose a whole population. We might lose an individual animal, but the population of those larger animals will remain intact. With reptiles and amphibians that is not the case,' Hilke said. 'It's basic ecology. The whole system is interrelated. If we begin losing some of our biological diversity, the threat is to all of our biological diversity.' Another point to consider is that larger animals have bigger home ranges for migration and aren't concentrated in small corridors like amphibians. Also roads are often constructed between the dry and wet amphibian habitats. 'They ultimately become bisected by these roads, which leads to [population] fragmentation. That's one of the reasons why it's so important to protect amphibians and build these structures because we are perhaps impacting them more than other species because of the sensitivity of their life cycles. A very high proportion of their population takes that same migratory corridor. With larger animals, not all the deer are passing right in a 100-meter section of road, whereas in some locations that is really happening with amphibians. They're highly concentrated,' Moser said. 'The only good news is their migration tends to be at night when traffic is a little less.' Views of the side wall (left) to guide amphibians to the tunnels and car crossing over one of the ... More culvert crossings in Monkton. One special factor about the Monkton wildlife crossing that makes it 'so great and a model for other states and countries is that it was driven by local communities and organizations,' said Groff. He also commended the project for having a scientific foundation with before/after data as well as being financially supported by donations from people as well as government grants. The Monkton Road amphibian crossings have been presented at an international conference and across the Northeast as a model of an innovative and successful wildlife infrastructure crossing project. Hilke is working with other Vermont towns to create similar wildlife crossings. A first step, he says, is to collect wildlife mortality data at potential infrastructure crossing locations. A key way to obtain funding for such projects is to demonstrate significant roadway death rates for wildlife, especially rare species. In Vermont and other areas along the Eastern coast, Hilke says underpasses can provide more effective wildlife crossings that overpasses especially due to flooding related to climate change. Blue-spotted salamander. 'In our context, we can meet multiple objectives like allowing for floodwater and allowing for aquatic and terrestrial passages by appropriately sizing our gray infrastructure. As we think about climate adaptation, this gray infrastructure is a solution that works for society and works for our ecology,' Hilke said. 'The power of Monkton is in the story and exciting people in Vermont and around the Northeast, and hopefully even around the world, that we can have a transportation system that works effectively for the traveling public and also stewards our wildlife. It's not an either or. We can have both.'
