Nature

How extinct animals could be brought back from death?

Published

3 weeks ago

11/04/2024

pouyan

Scientists are getting closer to being able to bring back long-extinct species of animals such as mammoths and Tasmanian wolves.

How extinct animals could be brought back from death?

Millions of years ago, the Tasmanian wolf, also known as the Tasmanian tiger, was scattered throughout Australia. These dog-like creatures, about the size of an American coyote and with stripes on their bodies, disappeared from the mainland about two thousand years ago. Tasmanian wolves remained in Tasmania until the 1920s when they were slaughtered by European colonists who saw them as a threat to their livestock. “It was a human-caused extinction,” says Andrew Pask, a geneticist at the University of Melbourne. “European immigrants came to Australia and brutally destroyed this animal.”

According to the BBC, Pasak is leading a group of scientists who, in collaboration with Colossal Biosciences, which works in the field of de-extinction, are planning to recreate these wolf-like creatures and bring them back to life.

Thanks to recent advances in genetics, and the advent of Crispr-Cas9 gene-editing technology, the Tasmanian wolf is not the only extinct species we may see again. But how does de-extinction science work and what kind of ethical questions does it raise?

In the case of the Tasmanian wolf, the first step is to sequence the DNA of the extinct animal. DNA is the genetic pattern that exists in the cells of the body. Pasak did this in 2017. “The great thing about the Tasmanian wolf is that because it was such an important marsupial, all the big museums wanted a specimen in their collection, so there are hundreds of specimens around the world, some of them very well preserved,” he says. Is.”

Well-preserved specimens of the Tasmanian wolf have made it possible to sequence the animal’s DNA.

“Our sample was a cub taken from its mother’s pouch,” Pasek said. They shot the mother and immediately placed the cub in alcohol, which preserves the DNA. “This was a miraculous sample for us to use to build the genome.”

Although the condition of the DNA obtained from the said sample is very good, it is not perfect. Over time, exposure to UV rays and bacteria causes DNA to break down into smaller pieces. The older the sample, the smaller the fragments left until eventually there isn’t enough left (so there’s no chance of bringing the dinosaurs back).

The incompleteness of the DNA presents scientists with the challenge of how to put the pieces of DNA together to arrive at the genome of the Tasmanian wolf. Fortunately, a tiny mouse-sized marsupial called the micro mouse can provide a map. “The closest living relative we found to the Tasmanian wolf was the mouse,” Pasek says.

95% of the DNA sequences of Tasmanian wolves and mice are the same, and these sequences have been conserved over time, meaning they have not changed much. “We sequenced the micro mouse genome and compared it to the genetic code of our extinct species, then matched them up and found different loci,” says Pasek.

However, knowing the DNA sequence of an animal is not enough to restore it. The next step is to change the mice’s genes to match those of the Tasmanian wolf. This can be done using Crispr-Cas9. CRISPR is a Nobel Prize-winning genome editing method. “We start with live mouse cells and start editing all those changes, so basically we’re turning a mouse cell into a Tasmanian wolf cell that has the chromosomes of its own species,” Pasek says.

Previously, gene editing was not advanced enough to simultaneously convert different DNA sequences into those of the Tasmanian wolf. Considering the millions of edits required, it was assumed that researchers would have to prioritize the most important DNA sequences and obtain an animal genome that was not completely identical to the genome of an extinct species. Pasak believes that there will be no need for this anymore, he says: “These technologies exist. No one had ever done this on such a large scale before because the DNA editing technology wasn’t precise or fast enough. But now we have advanced enough that we have access to the technology and there is significant investment to work on it.”

Once the researchers have the Tasmanian wolf cell, they must turn it into an embryo capable of growth and then transfer it into the womb of a close living relative. However, this is not as simple as it may seem. “There’s a lot to do,” Pasek says. We have already made marsupial stem cells and it took about five years. “Now we’re putting those stem cells into embryos to see if we can make them grow into a whole living animal.”

A tiny mouse has helped scientists fill in the gaps in the DNA of the extinct Tasmanian wolf.

It is not only the Tasmanian wolf that can be reintroduced in the manner described. Preserved fragments of woolly mammoth DNA found in the frozen tundra of the Arctic mean these large mammals could make a comeback. Most woolly mammoths became extinct about ten thousand years ago.

Scientists at Colossal Bioscience, a company founded by Harvard researchers, are using CRISPR to add pieces of mammoth DNA to the genome of the Asian elephant, the mammoth’s closest living relative. The resulting hybrid, known as a “mammophant,” would be adapted to the cold Siberian tundra and could help fill the ecological void left by the loss of mammoths.

However, the mentioned technology has limitations and there are obstacles that need to be overcome. “Many of the traits we have as living animals require multiple copies of genes,” says Michael Archer, a paleontologist at the University of New South Wales in Sydney. It’s not easy to tell how many are needed by looking at the reconstructed genome. “You wish that one version would be enough to create the features you want, but these projects always have a big unknown component.”

What is Crisper?

Crispr (Crispr-Cas9) was created in 2012 by Nobel Prize-winning scientists Emmanuel Charpentier and Jennifer Doudna. The technology uses a set of genetic scissors that are part of the defense mechanism that bacteria use.

When bacteria face a viral threat, they copy a piece of the invader’s DNA and insert it into their genome to create genetic scissors that recognize only that exact sequence.

CRISPR’s invention has revolutionized the speed and cost of gene editing, allowing scientists to precisely remove sections of DNA and make cuts to insert new genes.

However, genome reconstruction is not the only method scientists can use to revive extinct animals.

The auroch, a type of prehistoric cow, is the subject of ancient cave paintings around the world. This animal once roamed the plains of Europe and was as tall as an elephant. Niagao became extinct in the 1600s.

Although Niagaos are long extinct, their genes can still be found in various breeds of cattle, and their descendants can be found in Spain, Portugal, Italy, and the Balkans. Geneticists are backcrossing these species together to produce offspring that are closer to Niagao traits.

Another idea is to clone the dead animal by taking the nucleus of a healthy cell and then transferring it to the egg of a close living relative in the hope of forming an embryo. Of course, a whole cell is needed for this, and the cells disintegrate immediately after death. An animal like the Tasmanian wolf, which became extinct almost a hundred years ago, cannot be brought back with the help of this method. But this method can be an option for species that have recently become extinct.

In 2003, researchers successfully cloned the Pyrenean ibex, a type of goat that became extinct when the last member of the species was killed by a falling tree. Unfortunately, the newborn died shortly after birth due to lung failure.

Archer is using cloning technology to bring back a native Queensland frog. This frog ( Rheobatrachus silus ), which became extinct in 1983, had a strange method of reproduction where it swallowed its fertilized eggs and used its stomach as a kind of womb.

In 2013, Archer completed the first step (transferring a nucleus from a frozen frog cell to an empty egg of a closely related amphibian). Incredibly, the cells began to divide and an embryo was formed. “We did it hundreds of times and it didn’t work, and then suddenly one of them succeeded and under the microscope, we saw a hybrid embryo that started to divide,” says Archer. It was very exciting.”

However, after initial excitement, the project hit a snag when none of the embryos turned into baby frogs. “The frog embryos developed into a mass of cells, which is the initial and normal stage of embryo development, but then they stopped,” says Archer. “Normally, the outer layer of cells folds inward to form the bilayer structure that results in a tadpole, but our cell masses did not enter this stage.”

The same thing happened when the team was trying to create a dream using two species of frogs. So, there was one aspect of their experimental work that disrupted embryo development; Not that there’s a problem with extinct frog DNA. “We’re trying to understand this barrier in living frogs first before we work on DNA from an extinct animal,” says Archer.

Niagao was a type of prehistoric cattle that roamed the plains of Europe before disappearing in the 1600s.

Ethical considerations for returning extinct animals

Even if we can bring back extinct animals, there are ethical considerations. The reintroduction of Tasmanian mammoths and wolves may disrupt existing ecosystems. When these animals became extinct, other animals evolved and adapted to fill their place. Will existing organisms be harmed as a result of reintroducing extinct species?

Because of climate change, the environments where extinct organisms once lived may have changed drastically. Some of the plants that woolly mammoths used to feed on are also long gone. Can mammoths still survive on their own in the wild, and if not, who will be responsible for taking care of them? Will they end up in the zoo?

“I don’t think we should bring all the animals back,” Pasek said. I think they have to meet certain criteria. In the case of Tasmanian wolves, the extinction happened recently, so their habitat is still there in Tasmania, as well as the food they used to eat, so there is a place for them to stay and they can thrive in that environment again. This animal also played an important role in the ecosystem. The Tasmanian wolf was the apex predator at the top of the food chain. “There are no other top marsupial predators, so with the extinction of the Tasmanian wolf there was a huge gap.”

Some researchers argue that efforts to bring back long-extinct species could detract from conservation efforts to save existing animals and even increase the risk of biodiversity loss.

But de-extinction technologies can also be used to save species that are on the verge of extinction, especially those like the white rhinoceros that have a small gene pool.

Domestic black-headed minks are one of the most endangered animals in North America. Today, the ancestors of all living domestic minks are only 7 individuals. However, researchers at the Santiago Zoo in Chile recently took frozen cells from a black-headed weasel that died 30 years ago and used them to create a colony called Elizabeth. Elizabeth’s DNA is diverse, so it can increase the genetic diversity of the population. “De-extinction technology isn’t just about reintroducing Tasmanian wolves, it’s also helping to prevent other animals from going extinct,” Pask says. We have a lot of fires in Australia and as the world warms we will see more extreme weather events in the coming decades. Australia has collected and frozen tissue samples from marsupials from areas most at risk. “So, if there’s a fire, you can bring those species back into that area as the vegetation regrows.”

“I think it would be unethical not to do it,” Archer says of the ethical considerations associated with reviving extinct animals. The immoral thing that was done in the first place was the destruction of these animals by humans, and this is the intelligent man’s way of undoing the mistake he made.

Nature

The secret of the cleanest air on earth has been discovered

Published

2 weeks ago

15/04/2024

pouyan

The secret of the cleanest air on earth has been discovered. The Arctic Ocean is known for having the cleanest air on Earth, but the exact reasons for this have remained a mystery until now.

The secret of the cleanest air on earth has been discovered

The Arctic Ocean has some of the cleanest air on Earth, but there’s more to it than a lack of human activity. It is true that there are fewer people there and there are no industrial chemicals or burning of fossil fuels, but there are natural sources of fine particles such as salt from evaporating seawater or dust collected by the wind.

According to SA, regardless of their origin, fine solid particles or liquid droplets suspended in the air are known as aerosols. We define clean air as having low levels of particulate matter, without distinguishing between natural or industrial sources.

Recent research has discovered that clouds and rain play an important role in cleaning the atmosphere.

Understanding the role of clouds and rain

Aerosol levels in the Arctic Ocean are influenced by a wide range of factors, including the amount of salt spread and seasonal changes in the growth of tiny plant-like organisms called phytoplankton, which are the source of airborne sulfate particles.

Fewer sulfates are produced in winter when the air in the Arctic Ocean is fresher. But that’s not all. The Arctic Ocean is also the cloudiest place on Earth and experiences short-lived, scattered rain unlike anywhere else on Earth. Therefore, researchers sought to find out the role of clouds and rain in cleaning the air.

The biggest obstacle to understanding these processes has always been the lack of high-quality observations of clouds, precipitation, and aerosols in this region of the world.

Fortunately, a new generation of satellites allows us to study cloud images in unprecedented detail. We developed a computer program to detect different cloud patterns over a large area of the Arctic Ocean.

We specifically looked for distinct honeycomb patterns in the cloud field, the researchers say. These honeycomb clouds are of great interest because they play a major role in regulating the weather.

When a honeycomb cell becomes cloud-filled, or so-called “closed,” it becomes whiter and brighter, reflecting more sunlight into space. So these clouds help to keep the earth cool.

On the other hand, empty or so-called “open” honeycomb cells allow more sunlight to reach the Earth’s surface.

These complexities continue to be a source of error in Earth climate modeling because they are not properly incorporated into the model. It is important to get the balance of open and closed cells right, otherwise the results may be erroneous.

Whether the cells of the honeycomb are open or closed is also related to the amount of precipitation they can produce.

These cells are big enough to be seen from space and have a diameter of about 40 to 60 km. Therefore, we can study them using satellite images.

The aim of our research is to obtain higher-resolution information about clouds, rain, and sunlight, particularly with the launch of the Cloud and Precipitation Experiment in Tasmania, the researchers say.

Clearing aerosols from the sky

We compared the honeycomb cloud patterns with aerosol measurements at the Kennaook/Cape Grim Observatory, as well as with Bureau of Meteorology precipitation observations from a nearby rain gauge, the researchers say.

Our results showed that the days with the cleanest air were associated with the presence of an “open honeycomb cloud,” they say. We think this is because these clouds produce scattered but intense showers that seem to wash the aerosol particles out of the air.

This conclusion is somewhat counterintuitive, but it appears that open cells contain more moisture and produce more rain than closed cells.

“We found that open honeycomb clouds produce six times as much rain as closed clouds,” the researchers say. Therefore, what is detected by the satellite as less cloudy air actually produces the most effective rain to wash away the aerosols. While the open or closed honeycomb pattern is less effective. This was one of the surprising aspects of our findings.

“We found that empty honeycomb clouds are much more common in the winter months when the air is cleaner,” the researchers added. We also wanted to know what makes cloud fields look the way they do. Our analysis shows that large-scale climate systems control the pattern of the cloud field. As rogue storms move through the Arctic Ocean, they also produce these open and closed cells.

Fresh air and better weather models

Researchers say our research adds a new piece to the puzzle of why the Southern Ocean has the cleanest air in the world.

Precipitation is the key, especially rain that falls from these clear, open honeycomb clouds. We found for the first time that they are actually responsible for clearing the air currents in the Arctic Ocean.

These honeycomb patterns are also found in winter in both the North Atlantic and North Pacific regions. So our work will also help explain how airborne particles, including dust and pollution, are removed in these clouds, and our findings will help improve climate models and enable more accurate predictions.

Rain removes airborne particles from the sky in the same way that a washing machine cleans clothes. Therefore, after passing through the cold front, the air becomes clean and this clean air enters from the southern coast of Australia in winter.

Humans

How humans lose their body hair

Published

1 year ago

09/01/2023

pouyan

In their new research, a group of American scientists has investigated the reasons for body hair loss in mammals such as humans.

Body hair is a defining characteristic of mammals, but several mammals, such as whales, nudibranchs, and humans, have significantly less hair. Why we have significantly less hair than other mammals has long remained a mystery.

To find the genetic basis of hair loss, scientists at the University of Utah (UofU) and the University of Pittsburgh identified coding and non-coding sequences that evolve at different rates in hairless mammals compared to hairy mammals.

Humans body hair is about genetic

They found that humans seem to have the gene for a complete body hair covering. This research identifies several genes and genomic regions critical for hair growth. Also, this research shows that nature has used the same tactic at least nine times in different mammals. Ancestors of rhinos, nudibranchs, dolphins, and other hairless mammals used to swim and submerge to turn off a set of genes needed to lose hair and fur.

“We have taken a creative approach to use biodiversity to learn about our genetics,” said Dr. Nathan Clark, a human geneticist at the University of Utah who has conducted much of this research. This helps us identify regions of our genome that contribute to an important trait.

How humans lose their body hair

Scientists used an evolutionary rate-based method called RERconverge to perform a genome scan of 62 mammal species using 19,149 genes and 343,598 non-coding regions.

The analysis showed that many hairless mammals have mutations in many of the same genes. These genes encode keratin and extra elements that build the hair shaft and facilitate growth.

Also, this research showed that the genome’s regulatory regions seem equally important. Rather than encoding the structures that produce hair, these regions indirectly affect hair production. They control the amount of hair produced and when and where special genes are activated.

Amanda Kowalczyk, one of the researchers of this project, said: There are many genes that we don’t know much about. We believe these genes can play a role in hair growth and maintenance.

As animals are under evolutionary pressure to lose hair, the genes that code for hair become less important, Clark said. This is why they increase the rate of genetic variation allowed by natural selection. Some genetic changes may lead to hair loss, and others may be collateral damage after hair growth stops.

He added: “When a screen identified known hair genes, it showed that this method was efficient.” Also, this research shows that the genes identified on the screen, which are not well defined, can be equally important for having hair. It is a way to determine the global genetic mechanisms that underlie different traits.

Environment

A group of living fossils with 550 million years age have been discovered

Published

1 year ago

31/12/2022

pouyan

Living fossils from 550 million years ago

A group of living fossils that have existed on the planet since about 550 million years ago was spotted by a tourist exploring a prominent rock formation in Arizona.

A group of sperm shrimps called “Triops,” which dated back to prehistoric times and used to live alongside dinosaurs, were seen swimming in a pool of water inside a rock structure called “The Wave.” The video was taken.

Adar Leibovitch, a 29-year-old tourist, was visiting a stone structure when he saw several strange, three-eyed creatures in a pit.

Leibovich shared a video on his Instagram account and wrote: “I was so confused why there are living things in a pit in the middle of the desert.” How is such a thing possible? The eggs of these organisms can be left alone for years. When water hits them, they become active, and their life begins.

Triops , living fossils from 550 million years ago

Triops, named after a Greek term for “three-eyed,” is sometimes called a “frog shrimp” because of its long drooping tail and sometimes a “sperm shrimp” because of the scale on its head.its living fossils.

These creatures have two large compound eyes and a small or simple eye in the middle of the head, which is equipped with photoreceptors and helps to detect light.

Triops are also known as “dinosaur shrimp” because their external appearance has changed slightly compared to fossils from the “Devonian” period.

Leibovich’s video shows four Triops swimming in a shallow pool of water inside a stunning rock structure.

Leibovich captioned the video: “We are so lucky to live in a world where a creature like this Triops is the oldest known creature on the planet.”

The wave is a 190-million-year-old structure made of dunes that have turned into rock over time. Sand dunes are stacked and hardened by the deposition of calcium salts that form vertical and horizontal layers.

Although sightings of thrips are rare, another sighting was reported last year, again in Arizona. A monsoon in October awakened the exotic crustaceans from their decades-long slumber.

Following the rain, hundreds of horseshoe-like creatures hatched from tiny eggs and swam around a lake formed in Wupatki National Monument, about 30 miles outside Flagstaff, Arizona. They reach adulthood within a week, reproduce and lay more eggs to repeat the cycle, staff at the area wrote in a Facebook post.