Cloning dinosaurs. Cloning dinosaurs why you can't clone a dinosaur

Julie Feinstein from the American Museum of Natural History retrieves a frozen tissue sample from an endangered animal

Is it really necessary to resurrect dinosaurs from flesh and blood if computer technology will make them completely “alive” so soon?

The stuffed sheep Dolly is preserved in the museum today

"Solve all your problems with a simple freeze" - the slogan of Applied Cryogenics from the animated series Futurama

Fantasts and futurologists have repeatedly predicted that in the future, extinct creatures will be “restored” again through cloning using the remaining - say, in a frozen state - DNA fragments. To what extent this is even possible is not entirely clear. However, a large-scale project has already been launched in the United States to preserve frozen tissue samples of rare and endangered animals.

In principle, such cloning has already taken place - Spanish scientists "revived" the Pyrenean goat, the last representative of which died in 2000. However, the cloned animal did not last even 7 minutes, dying from a lung infection. However, many experts considered this a major success, which inspired the emergence of new collections of frozen specimens, including the project of the American Museum of Natural History (AMNH). And who knows if such repositories will not really serve as an invaluable "Noah's ark" that can save many species from complete extinction.

The AMNH repository has space for about 1 million samples, although it is still far from that number. Butterflies, frog legs, a fragment of whale skin and crocodile skin - such samples are preserved in containers cooled with liquid nitrogen. And according to the recently concluded with the US National Park Service, the collection will be replenished with new exhibits. For example, already in August, scientists are preparing to take blood samples from the island fox, which is on the verge of extinction. In theory, such frozen cells could someday be used to clone and completely "resurrect" an extinct species. But so far, no scientific group has been able to do this.

For example, the Spaniards who cloned the Pyrenean goat almost literally followed the method of the British Ian Wilmut (Ian Wilmut) - the same one who literally shocked the whole world in 1997 by introducing the cloned sheep Dolly. This showed the fundamental possibility of cloning mammals - moreover, the sheep lived for more than 6 years and died in 2003. However, both Dolly and the Spanish goat were cloned with nuclear transfer: scientists took the egg of one animal and removed the nucleus from it, and instead introduced the nucleus from cells of the animal they wanted to clone. Then such a "hybrid" cell was placed in the body of a surrogate mother.

Such a method requires the ideal cell condition of the animal that scientists intend to clone. For a sheep and a goat, this might still work, but what about the many extinct or endangered species that have neither horns nor legs? Even in cryogenic storage, over the years, DNA slowly degrades, and even samples that have been preserved in “natural” conditions contain only an insignificant part of their genome at all.

However, modern computer technology makes it possible to scrupulously restore the complete genome of an extinct species by combining data from several samples. In this way, work is underway on the genetic mapping of ancient mammoths and even Neanderthals. Quite significant fragments of the genome of other extinct species have already been obtained - for example, a cave bear or moa, a giant bird that reigned in New Zealand before the Maori aborigines appeared here.

And German researchers managed to do a good job with the Neanderthal genome - however, only its mitochondria (special organelles, "energy stations" of our cells that have their own genetic material). And if moa birds died out about a thousand years ago, then Neanderthals have not existed for about 40 thousand years - and the work of scientists from Germany is all the more valuable. However, all these approaches will never work with samples older than 100 thousand years: during this period, DNA degrades completely.

What - we will never see the "dinosaur park" in the enclosures of which live cloned tyrannosaurs or giant diplodocus? How to know. For example, not so long ago, a “reverse evolution” method was proposed to restore the genome, which consists in working with the genotype of “living relatives” of an extinct species.

Californian scientist Benedict Paten and colleagues are working on such an approach. Their solution is to sequence the genomes of many individual members of related species, and then compare them in order to determine the “source code” using special algorithms. For example, by “calculating” the genomes of humans and chimpanzees, the authors managed to “come” to four of our common ancestors, which they reported in a publication last fall.

However, this method, of course, is not ideal and has its limitations. Dinosaur Revival is delayed again. And even if we manage to get data on the genomes of all living organisms on the planet, some of the extinct species simply did not leave any descendants. They have disappeared, and it is unlikely that information about their DNA can somehow be obtained.

But let's say we managed to get a complete transcript of the genome of some extinct species. This is only part of the task, because we still need to get a living organism. And this is an almost divine thing: to move from information encoded in DNA to a real being.

To begin with, it will be necessary to synthesize the DNA itself and somehow correctly divide its strands into the necessary chromosomes and fold them - also in the same unique way that they were folded and ordered in a once living being. Already at this stage today the problem is unsolvable. But let's say, and we succeeded, say, using a biologist robot who made hundreds of thousands of attempts and found the only correct option (we wrote about such robots in the article “The Beginning of a New Era”). You will need an eviscerated egg, in which you can place the chromosomes in the nucleus before implanting it in a surrogate mother. And everything we know about the nature and nature of genetic diseases allows us to add: the slightest mistake will lead to complete collapse. In a word, all this looks too complicated and is unlikely to allow cloning even a mammoth in the foreseeable future. It might be easier to invent a time machine.

Although the famous American geneticist George Church (George Church) offers a completely original approach. It is not necessary, he believes, to clone an entire ancient animal. In the same mammoth, we are interested in a hairy elephant, so it’s easier to take an ordinary elephant and turn off the genes that determine its lack of hair, and instead introduce into it those that were responsible for the hair of a mammoth. Step by step, other characteristic elements of a mammoth can be added to the elephant - say, changing the shape of the tusks and so on - until we are more or less closer to the "original source". The method is also more than controversial - after all, in fact, by doing this we do not restore extinct species, but create new ones.

And is it all necessary? Many scientists are inclined to believe that the complex problems associated with the "revival" of the once extinct species are not worth it. Imagine that we restore the same moa birds - their impact on the ecosystem of modern New Zealand will most likely be deeply destructive. And to spend colossal efforts and funds just to get a few birds for the zoo seems to be the height of extravagance. It is difficult to talk about the ethical issues of cloning, say, Neanderthals. As some experts wisely point out, than to restore the lost, it is better to take up the preservation of what is still available. And we cannot but agree with them.

A film by the famous director S. Spielberg about an island where cloned giant lizards roam the amusement park has probably been seen by every one of our readers. At one time, after watching the movie, many wondered: is a dinosaur clone a myth or reality?

The most interesting thing is that this question is of interest not only to idle onlookers. The problem of cloning came to grips with genetic scientists funded by very wealthy people.

Dinosaur DNA is gone

Billionaire from Australia Clive Palmer, famous for creating a copy of the infamous ship "Titanic", "fired up" with the idea to create his own park with giant lizards. To do this, you just need to get a clone of these prehistoric creatures, but is such a task possible for a person, even with a tightly stuffed wallet (sorry, suitcase) of money? Unfortunately, no, scientists answered.

For a long time, Australian researchers have been working on the problem of preserving DNA in the bones of ancient birds and the probability of obtaining it. The tests were carried out on the bones of ancient birds called moas.

Once these giants inhabited New Zealand, but five hundred years ago they were practically destroyed by the local population. Geneticists studied bones that were up to 8,000 years old or more. It turned out that DNA molecules decayed in the bones quite quickly. After one and a half million years, the genetic material cannot be used for reading, and after seven million years it completely decays. And even ancient insects encased in amber do not possess any DNA.

The most famous dinosaurs

tyrannosaurus rex(aka Tyrannosaurus Rex). This is an unsurpassed predator, a real killing machine. Old Rex is familiar to anyone who has watched Jurassic Park. It is believed that with its enormous dimensions, the lizard was able to reach speeds of up to 60 km / h.	Diplodocus. This peaceful herbivorous lizard had an impressive size - its body length reached 40 meters! Diplodocus spent most of its life in the water, and they got out on land to eat or lay eggs.	Triceratops. A characteristic feature of this massive dinosaur are three horns and an openwork "collar" around the neck. The appearance of Triceratops had some similarities with the modern rhinoceros. This dinosaur weighed about 12 tons, it belonged to herbivores.
Pterodactyl. Jurassic aviation representative. What can be said about this lizard? He had a rather large beak with teeth, and the wingspan of the "bird" reached 12 meters. The pterodactyl could snatch fish out of the water right on the fly, thanks to dexterous paws with “fingers”.	Allosaurus. Another terrible predator attacking its prey in a jump. The jaw of the Allosaurus consisted of about 70 teeth, from 10 to 15 cm long. The long and muscular tail helped the predator to maintain balance when walking and running.	Plesiosaur. It is an aquatic lizard with an incredibly long neck. Some believe that the famous monster of Loch Ness may be a descendant of a plesiosaur. The main diet of this pangolin was fish. Plesiosaurus had large flippers, which allowed it to maneuver in the aquatic environment.

Chicken ancestors could bite painfully

Nobody even doubts that scientific research in the field of paleontology will continue, but the conclusion has already been made. He tells us that it is impossible to create an amusement park with giant lizards. But you shouldn't get upset! Extinct giants can be revived in another way.

How often do we eat chicken meat? But we don’t even think for a minute that this is the meat of a descendant of a prehistoric lizard. It's funny that our chicken and the ancient monster have similar DNA, and the embryonic chicken is equipped with a large scaly tail and saber-toothed jaws. What is the challenge facing geneticists today? They had the opportunity to study the gene information of a bird to obtain a dinosaur.

Relatively recently, American researchers came to the conclusion that the composition of the blood of an ostrich strongly resembles the composition of the blood of giant lizards. And this discovery gives hope for obtaining the DNA of these extinct individuals. In all likelihood, we expect a lot of interesting things. And maybe we will be able to see with our own eyes a real “dinosaur park”.

And about bringing their ideas to life today. And then I read about a rumor that the famous film “Jurassic Park” could be re-shot, so I thought about how much science has now advanced in cloning dinosaurs, well, or at least someone younger, for example, Neanderthals. I went online for the latest articles.
I'll start with the bad news. Despite the beautiful theory, so colorfully shown in the film, it is extremely difficult, or rather impossible, to put it into practice. Firstly, the probability of finding a female mosquito in amber immediately after she bit a dinosaur, and not someone a couple of hundred million later, is negligible. And the safety of pure DNA in amber is also a big question. But the very idea that you need to find or recreate DNA is, of course, correct. But is it possible to do this?

For a long time, the answer of scientists to this question was categorically unambiguous: no, it is not possible to extract DNA from ancient fossils for the following reasons:
- on average, DNA outside of permafrost is destroyed after 100,000 years
- all you can find is very short pieces of DNA that cannot be stitched together
- even if you try to isolate fragments of genetic information, it is very difficult to separate it from someone else's DNA, introduced later or belonging to the bacteria of that era
But dreams are given to us for that, so that we do the impossible. Fortunately for us and for civilization as a whole, scientists do not understand the word "impossible" and do not listen to the arguments of reason, which gives us great discoveries.
In 2010, a huge breakthrough was made in recovering DNA with very high accuracy from the found remains dated to about 50-75 thousand years ago. The first was a girl belonging to the ancient extinct people - the Denisovans, who existed in parallel with the Neanderthals. Scientists have developed a new method for reconstructing single-stranded fragments of the DNA molecule, which made it possible to read the girl's nuclear genome with very high accuracy and, on the basis of it, make many discoveries about the evolution of people of that time.
In 2013, the next big event took place: the milestone of 100 thousand years was overcome. The genome of a horse that lived 560-780 thousand years ago was deciphered from the remains found in the permafrost. But the most interesting thing is the deciphering of the mitochondrial DNA of the bear and the ancestors of the Neanderthals (Heidelberg man) dated 400 thousand years, the remains of which were found in a more pleasant climate. This work showed the fundamental possibility of restoring the genome of remains not from permafrost zones, which significantly expands the geography of potential clones. And again, thanks to a breakthrough in the technique of working with DNA fragments. To solve the problem of foreign DNA contamination, sequences of no more than 45 nucleotides were taken (longer sections could hardly be preserved) with post-mortem mutations (certain nucleotide substitutions that occur after cell death). When they collected enough pieces of the puzzle, they began to look for a template, the closest DNA, from which it is possible to restore the sequence of genes. It's like putting together a puzzle from small pieces when you have the big picture. The genome of the Denisovan man best suited this role.
This method requires 2 important components: a large amount of DNA fragments and a template for the reconstruction of the genome. With each new decoding, we gain new knowledge and ... a new template. So step by step we can delve into our own history.


But so far, all these discoveries are limited to a segment of 800 thousand years. And what to do with dinosaurs that lived 225-65 million years ago. It is believed that not a single molecule or even a cell can survive for such a long period of time. But even here science does not stand still.
Very recent studies in 2014 showed that in porous volcanic soil, fossilization occurs so rapidly that not only the structure of cells is preserved, but chromosomes can also be distinguished. Thus, the size of the genome of a fern living 182 million years ago was estimated, and this is already a suitable period of time.
As for the dinosaurs themselves, in 2013 a group of scientists showed that the structure of osteocytes (bone cells) is preserved in fossilized bones after demineralization. And with the help of mass spectroscopy (a high-precision method for determining molecular weight) and antibodies, they showed that proteins of muscles, bones and, most importantly, specialized proteins - histones, which are associated with DNA molecules, have been preserved there. Thus, it turns out that DNA can also be found in these remains, and, consequently, the genome can be restored.
While some scientists are trying to talk fossils, others are conjuring over the DNA of ... a chicken, trying to awaken archaic genes in it and create a dinosaur from Ryaba's ordinary domestic chicken. Personally, I don't believe in Kurodinosaurus, but this work could help provide a genome template for later deciphering the fossil genome.

Summing up, I want to say that science is stubbornly moving towards the goal of obtaining the genome of not only the ancestors of people, but also dinosaurs, and there it will already be possible to think about cloning :-)

The idea of ​​cloning dinosaurs from fossil remains was especially relevant after the release of the movie Jurassic Park, which tells how a scientist learned how to clone dinosaurs and created a whole amusement park on a desert island where you could see a live ancient animal with your own eyes.

But a few years ago, Australian scientists led by Morten Allentoft and Michael Bunce from Murdoch University (Western Australia) proved that it is impossible to “recreate” a living dinosaur.

The researchers conducted a radiocarbon study of bone tissue taken from the fossilized bones of 158 extinct moa birds. These unique and huge birds lived in New Zealand, but 600 years ago they were completely destroyed by the Maori natives. As a result, scientists have found that the amount of DNA in bone decreases over time - every 521 years, the number of molecules is reduced by half.

The last DNA molecules disappear from bone tissue after about 6.8 million years. At the same time, the last dinosaurs disappeared from the face of the earth at the end of the Cretaceous period, that is, about 65 million years ago - long before the critical threshold for DNA at 6.8 million years, and there were no DNA molecules in the bone tissue of the remains that archaeologists manage to find.

“As a result, we found that the amount of DNA in bone tissue, if kept at a temperature of 13.1 degrees Celsius, decreases by half every 521 years,” said research team leader Mike Bunce.

“We extrapolated these data to other, higher and lower temperatures and found that if you keep bone tissue at a temperature of minus 5 degrees, then the last DNA molecules will disappear in about 6.8 million years,” he added.

Sufficiently long fragments of the genome can only be found in frozen bones no more than a million years old.

By the way, to date, the most ancient DNA samples have been isolated from the remains of animals and plants found in permafrost. The age of the found remains is about 500 thousand years.

It is worth noting that scientists will conduct further research in this area, since differences in the age of the remains are responsible for only 38.6% of the discrepancies in the degree of DNA destruction. The rate of DNA decay is influenced by many factors, including the storage conditions of the remains after excavations, the chemical composition of the soil, and even the season in which the animal died.

That is, there is a chance that in conditions of eternal ice or underground caves, the half-life of the genetic material will be longer than geneticists suggest.

Erenhot, city of dinosaurs. Photo: AiF / Grigory Kubatyan

How about a mammoth?

Reports that scientists have found remains suitable for cloning appear regularly. A few years ago, scientists from the Yakutsk North-Eastern Federal University and the Seoul Center for Stem Cell Research signed an agreement to work together on mammoth cloning. Scientists planned to revive the ancient animal using biological material found in permafrost.

A modern Indian elephant was chosen for the experiment, since its genetic code is as close as possible to the DNA of mammoths. Scientists predicted that the results of the experiment would be known no earlier than in 10-20 years.

This year, reports again appeared from scientists from the North-Eastern Federal University, they reported the discovery of a mammoth that lived in Yakutia 43,000 years ago. The collected genetic material allows us to expect that intact DNA has been preserved, but experts are skeptical - after all, very long DNA chains are required for cloning.

Living clones

The topic of human cloning is developing not so much in a scientific way, but in a social and ethical way, causing disputes on the topic of biological safety, self-identification of the “new person”, the possibility of the appearance of inferior people, also giving rise to religious disputes. At the same time, animal cloning experiments are being carried out and have examples of successful completion.

The world's first clone - a tadpole - was created back in 1952. One of the first successful cloning of a mammal (house mouse) was carried out by Soviet researchers back in 1987.

The most striking milestone in the history of cloning of living beings was the birth of Dolly the sheep - this is the first cloned mammal animal obtained by transplanting the nucleus of a somatic cell into the cytoplasm of an egg cell devoid of its own nucleus. Dolly the sheep was a genetic copy of the cell donor sheep (that is, a genetic clone).

If in natural conditions each organism combines the genetic characteristics of the father and mother, then Dolly had only one genetic "parent" - the prototype sheep. The experiment was set up by Ian Wilmuth and Keith Campbell at the Roslyn Institute in Scotland in 1996 and was a breakthrough in technology.

Later, British and other scientists conducted experiments on the cloning of various mammals, among which were horses, bulls, cats and dogs.