ORIGINE DELLA VITA E CHIMICA PREBIOTICA-ORIGIN OF LIFE AND PREBIOTIC CHEMISTRY : THE GENE TRASMISSION

That is: what should we expect in the near future

DNA (deoxyribonucleic acid) is the genome, the molecule that contains genetic information.

It is written in DNA if an organism will be a human being, a tree or a microorganism. In the DNA of all organisms, tens of thousands of segments called genes have been identified. They are genes, or groups of genes, that determine the color of the skin, the number of fingers on one hand, and so on. Each gene is made up of a few hundred base triplets. Every living organism always transmits its genetic heritage to descendants and this transmission is called vertical. Often in the descendants the hereditary heritage undergoes mutations, that is, a base is replaced by another base changing the meaning of the triplet that now codifies for another amino acid. If this substitution is neutral or gives the new organism an advantage over the other organisms, it remains and is passed on to the offspring. On the other hand, if the mutation is disadvantageous, it is likely that the organism dies and that evolutionary line dies out. The study of the arrangement of bases in genes and the arrangement of amino acids in proteins is called sequencing. The comparative analysis then compares the DNA or proteins of the various organisms and from this comparison we can trace the common ancestor. With the help of Paleontology, it can often be traced back to the period in which this separation occurred. So we know, that humans and chimpanzees have 99% of their DNA in common and that their progenitor must have lived about 5-6 million years ago, that mammals and reptiles had a common progenitor around 150 million years old does. Ultimately, gene and protein sequencing only confirms Darwin's theory of evolution at the molecular level. Since genes are transmitted from an organism to their descendants by establishing a kinship bond, Darwin's genealogical tree which concerned higher organisms has been extended back in time, even to micro organisms.

It all seemed quite clear when, in the 80s of the last century, lateral transmission, also known as horizontal transmission, was discovered in the bacterial world and among single-cell eukaryotes: genes are not only transmitted from an organism to their descendants but also between cells that do not have no kinship ties.

At a bacterial level, therefore, it is not always clear whether a given gene belongs to the evolutionary line of such an organism, or if it has been transmitted by other bacteria belonging to different evolutionary lines.

When it comes down to the bacterial level, the construction of a phylogenetic tree becomes very complicated. However, the genealogical tree still remained valid for higher organisms and the horizontal transmission could affect these organisms was strongly excluded.

At the beginning of the 90s of the last century a friend of mine was called by an acquaintance who tells him that during the cleaning of the garden he noticed the presence of a snake that he immediately killed and not knowing where to throw it buried him.

After a few weeks, after cleaning the garden, he transplanted some cauliflower seedlings. Reached the maturation period in a plant, the cauliflower, to his surprise, was not the same as the others. Jokes of nature? But the owner of the garden, after taking photos, dug under the seedling. To his surprise, he found the snake's skin, that was where he buried it.

The photos were sent to two science publication magazines. One magazine did not store, the other sent them back with the reason "we don't deal with these things". Now, it is true that at that time such an event found no scientific explanation and could be catalogued as a simple oddity of nature. But, without wanting to make controversy, anyone involved in science should also always be aware that taking the conclusions of science as definitive means raising facts and theories to dogma.

Around 2010, after almost twenty years, it was discovered that horizontal gene transfer also involves higher organisms. Those responsible for this transfer are viruses and bacteria that infect plant and animal cells and transfer segments of their genes to them. In addition, bacterial pathogens that enter plant and animal cells can pick up foreign genetic material, transport it to their cells and then serve as vectors for horizontal gene transfer. Until a few years ago, it was believed that viruses and bacteria were the only carriers for horizontal gene transfer between plants and animals. In short, there could be no direct transmission for plant cells, which generally have a protective cell wall. In recent years, it has been discovered that insects, with their hard and sharp parts, can also transfer foreign genetic material to both plants and animals.

Today it is believed that there are no barriers that prevent the entry of foreign genetic material into the cells of any species on earth.

And then we can perhaps explain what happened to the cauliflower seedling. While the roots slowly sank into the ground to anchor the plant on the ground, the root apex, already considered by Darwin to be the brain of the plants, must have touched the skin of the snake. The scales of the skin are made up of external cells with no nucleus but rich in keratin, a very hard protein material, and internal cells that retain the nucleus, where the genetic material resides. The very hard protein material must have injured the root apex and allowed the underlying cells to transmit the genes of a new morphogenesis to the root that replaced or added to the original morphogenesis.

Now, one wonders: what will happen in the future when gene addition or replacement, in higher organisms, becomes a laboratory technique.

Meanwhile, we are talking about the morphology of a flower. Whether the shape of the flower is round, elongated or spiral is about aesthetics, but the metabolic system as a whole has not been affected. When this technique is available, we can give flowers and fruits extravagant shapes.

Perhaps some bizarre biologist will be able to perform some bizarre experiment by giving a monkey the shape of a snake or a dog. But in such a case the form is not independent of the metabolic system of the whole organism, such a creature would probably not live long, the metabolic system would not allow it.

We will see what the future holds for us, in any case it is always advisable to be vigilant. Meanwhile, remaining within the sphere of flowers, there are several that are classified as oddities of nature.

Da: Meteoweb.eu