Any schoolchild knows perfectly well that dinosaurs roamed the Earth millions of years ago. Today, paleontologists find fossilized prehistoric remains in different parts of the world. And Dr. Mary Schweitzer of the University of North Carolina even managed to isolate the remains of soft tissue from the fossils. Maybe it will be possible to get DNA from them?
Are there any chances?
The question is - why do we, in fact, need "dinosaur" DNA? First of all - to study it and understand how the evolution of the lizards took place, which to some extent are the predecessors of mankind. By the way, dinosaurs (at least such a species as theropods) are considered to be the ancestors of birds and they find about 300 common features in both …
And some people believe that dinosaurs will be able to clone, and “parks of the Jurassic period” will appear on Earth, in which everyone will be able to admire the ancient inhabitants of our planet …
To begin with, how much is it possible to extract the coveted DNA from the remains of the lizards? The bones of dinosaurs, which have lain in the earth for about 65 million years, are composed of the mineral hydroxyapatite, which is now actively used in laboratories to purify biomolecules. In theory, DNA molecules can "stick" to this material.
But many experts believe that DNA molecules have a fairly short lifespan, a maximum of five to six million years. When samples of different ages, from several hundred to 8000 years, were placed in hot acid, it turned out that the older they are, the fewer molecules can be isolated … Modeling showed that the chances of finding DNA in the remains of the Cretaceous period are extremely small. Nevertheless, its preservation, as it turned out, did not directly depend on the age of the samples.
In addition, since there is evidence that molecules that are biochemically similar to DNA can form in human bone tissue cells, theoretically they can also form in dinosaur bones.
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Authenticity criteria
But how can you prove that this is dinosaur DNA, and not someone else's? What if the molecule got into the samples already in the laboratory, along with some kind of contaminant?
Scientists offer several criteria for this.
1. The DNA sequence isolated from the bones should be as expected. For example, it should be similar to the genetic material of birds, but at the same time differ from the DNA of birds, and from the DNA of crocodiles, and in general from any known modern DNA.
2. Genuine dinosaur DNA must be highly fragmented and difficult to analyze by modern means. If the molecule consists of long "chains", which are relatively easy to "decode" during sequencing, then, in all likelihood, this is "third-party" DNA.
3. Since DNA molecules are considered to be rather fragile, more stable compounds, for example, collagen and lipids, of which cell membranes are composed, must be present in the studied genetic material. Moreover, in such molecules, a connection with birds or crocodiles should be traced.
4. The connection of proteins and DNA found in samples with dinosaurs should be confirmed not only by genetic sequencing, but also by other scientific methods. So, you need to check the reaction of proteins to specific antibodies. In one of the experiments, it was possible to use alternative methods to localize a DNA-like substance inside the cells of the bone tissue of the remains of Tyrannosaurus Rex, a representative of the species of lizards living in western North America.
5. It is required at all stages to examine not only samples, but also all other chemical compounds used in the laboratory. If similar sequences are found in them, then, most likely, we are talking simply about pollution.
Is cloning real?
But let's say dinosaur DNA is successfully isolated. What about cloning?
In theory, the process of cloning lizards is quite possible. One of the laboratory methods is the insertion of fragments of specific DNA into bacterial plasmids. In the process of cell division, replication occurs and identical copies of DNA are created.
In another technique, a set of donated DNA is placed into viable eggs, from which their own nuclei have been removed in advance. After that, the eggs are implanted into the uterus, and offspring are born, whose DNA is identical to the donor's. This is how the notorious Dolly sheep was born. However, the cloning process is incredibly difficult, and it is extremely difficult to get full and viable clones …
However, recovering bare DNA from fossil remains is not so impossible. Even just the process of its laboratory study can tell us a lot about how the animal world of the Earth was formed and how the evolutionary processes went.