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Researchers claim to have found “exquisitely preserved” fossilized dinosaur DNA after 125 million years

That the fantasy of ‘Jurassic Park’ comes true at the moment is quite unlikely, starting from the conservation and extraction of usable genetic material from amber, although according to some scientists “the possibility of creating dinosaurs already exists.” The fact is that the complicated thing is to find valid (or entire) DNA samples to complete the creation of a being, and in line with this now some researchers affirm having found entire nuclei of genetic material in dinosaur remains.

Yes, they are remains fossilized, which may not be enough for as many films as those that could have occurred to us at one point. The finding has attracted attention, and perhaps that is why it does not have the support of all the experts in the field.

John Hammond would like this

The conservation of molecules It depends on the structure itself and the environment that has surrounded it, as with tissues. An example is mummification, which allows them to be preserved much more, as we saw with the idea of ​​making a mummy “speak” a while ago.

Although the thesis of Crichton’s novel or Spielberg’s film is to recover the genetic material by pulling the blood that the insects trapped in it could suck from a saurian, in reality DNA recovery attempts are usually approached in other ways . In this case, the team of researchers from the Institute of Geology and Paleontology at Linyi University (among other centers also in China) explains in their work (published in Nature) that they focused on dinosaur cartilage, due to previous findings in which it was suggested that this tissue is favorable when it comes to preserving cell nuclei.

As a reminder or very quick information, a eukaryotic cell (the most advanced and complex, those that humans have and most multicellular species, as well as some unicellular species) is a compartment full of elements, a bit like organs. (organelles), and in turn has a space to store the genetic material lined with a membrane: the core. Depending on which cell it is, the nucleus may be larger or smaller and depending on the “age” of the cell the genetic material will be more or less compacted, but in the end we are talking about between 0.5 and 25 µm in size. nucleus.

Tincion Hoescht Cell NucleusTincion Hoescht Cell Nucleus

Cell nuclei in HeLa cells, the leftmost one in the cell division phase (chromosomes) and the other two with semi-condensed DNA (chromatin).

The evolutionary reason for our genetic material to be more protected within the cell and, in turn, to be compacted on many occasions, is to favor its preservation and not be damaged, since being free it would be quite susceptible to being affected by some mode. Hence not so easy to find an intact core or enough DNA to “Dolly” a dinosaur.

In this case, the researchers analyzed the cartilage of a Caudipteryx, a dinosaur whose name means “feathered tail” that lived in the early Cretaceous (about 125 million years ago). After demineralizing the sample, they observed it under a microscope using one of the most common stains in light microscopy: hematoxylin and iosin. Two dyes that stain some structures with a pink-blue gradient, so that the nucleus is very dark and marked.

HyeHye

Example of tissue staining with hematoxylin and eosin. In this case, it is human lung tissue, the cavitation of it, the cell nuclei in dark blue and the red blood cells in some capillaries showing very well. Image: Wikipedia

As they explain, in a chondrocyte (cartilage cell) of the dinosaur fossil they saw nuclei with chromatin strips, that is, DNA with some degree of condensation. The degree of conservation of the nuclei is quite surprising, which is why they give force to the hypothesis that cartilage is a candidate tissue to be one of the best preserving genetic material.

In addition to staining, researchers have used electron microscopy techniques and other analyzes to determine the degree of preservation of these nuclei. In addition, they compared the results with the cartilage tissue staining of a chicken, seeing that there were similarities in the patternwhich would be further proof of how surprisingly well the millions of years old nuclei would have stained.

Regarding the reasons for conservation, the team of scientists points out that in addition to the peculiarities of the tissue (the presence of calcium, etc.) it is also possible that it has influenced the geology of the terrain, with layers of volcanic ash. It is the so-called Jehol biota, a name that refers to the set of organisms that inhabited a region of northern China very rich in fossils up to 131 million years ago.

Of course, since it would be a very notorious and relevant finding, there are voices positioned against it with the argument that it could be a case of contamination (also prehistoric). As reported on Gizmodo, researchers such as Evan Saitta (from the Center for Integrative Research at the Field Museum of Natural History in Chicago) or Nic Rawlence (director of the paleogenetics laboratory at the University of Otago in New Zealand) suggest that the staining could correspond to microbes installed in the remains of the dinosaur.

In addition, it should be noted that in this case it is a fossil (in stone), so the structure of the genetic material must have undergone some mineralization. Thus, it is not clear that although cartilage can better preserve DNA, it can be sequenced, as was achieved with mammoth DNA (preserved rather by freezing).

The researchers want to continue to investigate cartilage to try to add strength to the theory that cartilage may be something of a holy grail of conservation of genetic material, although there is also much more research to add to this first finding of Caudipteryx DNA. . The investigation of ancient DNA, along with other analyzes in parallel, has proven to be very useful in filling in gaps in history, so it would be very interesting if such old samples could indeed be found.