Custom DNA, xenobiology and nature

Xenobiology seeks alternative chemical structures that can ensure organic functions instead of or in parallel with the universal structures of life on Earth. So far, these are DNA, RNA and proteins. The cells that house these modified or artificial molecules are always natural bacteria, such as Escherichia coli (E coli).

Transformed DNA, amplified DNA

Make experiences proof of concept has been carried out, in particular in the United States, Japan and France (Genopole). In 2010, Philippe Marlière forced bacteria E coli to integrate a synthetic molecule into their DNA: 5-cholo uracil (toxic) instead of thymine (one of the four bases of natural DNA). At selection pressure in a controlled culture medium, the bacteria have become dependent on this new molecule in five months. They had adapted the ersatzen to survive and had integrated it into their DNA as a replacement for thymine. Those E coli therefore has a DNA transformed into AXN: xenonucleic acid. The future challenge will be that attack the other DNA bases » [2].

In 2014, Floyd E. Romesberg integrated into E coli and DNA ” rising of a pair of synthetic bases named X and Y. As in the previous case, it is a natural / artificial hybrid organism. In fact, only the genetic material is artificial. This does not prevent one of the proponents of xenophobia from saying that ” it is a Copernican revolution: Before we studied living organisms, biology in the future will generate new genes and new species! » [3]. So there would be one alphabet ‘To six DNA bases and no longer the four natural ones that would modify the genetic code [4].

In 2021, we will also begin to understand how a base named Z (instead of A) can exist naturally in a virus that attacks bacteria. This virus has an enzyme of ancient origin which makes it possible to synthesize this Z-base. By copying this, synthetic biologists plan to enzymatically implant new bases in the genetic material. [5].

Xenobiology, an example of the new biological empirics

This new empirical defense of xenobiology consists of trying, experimenting to see what happens. It’s evolving especially with synthetic biology, which wants to build systems ” live “. It is supported by the idea that it is not necessary to understand everything in order to build, which calls into question the responsibilities of researchers. [6].

Proponents of xenobiology recognize that nature has explored only a tiny fraction of possibilities, but for them, natural selection would have retained only imperfect structures and living beings, even if the choice of the most suitable locally would have enabled evolution. For example, the genetic code is not optimal, due to preparedness at some point in evolution. It needs to be perfected to optimize it, just as bacteria or the human species need to be optimized.

Xenobiology scientists do not mind real living things: they willrelaunch the development of bacterial, plant or animal species in a controlled way … » [7] and the purpose of their work is truly industrial production of new molecules.

Nature / extended DNA coexistence and its mastery

Thus, for those who promote it, xenobiology would be a means of strict separation between the natural domain and the biosynthetic domain. Two worlds without interference, as artificial biodiversity would depend on a controlled cultural environment and “unable to contaminate, genetically contaminated natural habitats. From an environmental protection point of view, this is a path that can lead us to the ultimate protection» [8]. However, these beliefs seem fragile and somewhat contradictory, as it is also said that xenobiology must be rendered harmless, that is, that it produced “must not have the natural as prey» [9]. The recipe for this is not given.

Mastery is the key word in xenobiology, but is it possible? We do not know what the current, brand new GMOs do in nature; how could we know what xenobiology products will do there in the future? One thing is for sure: Nature and its long journey of 3.5 billion years are not prepared to accept such artifacts. The changes that it moves on to, even though their origins can be brutal, are slow, progressive, collective.

The mastery of the evolution of xeno-biological systems is also posed. Populations of bacteria with AXN grown in a controlled environment have been shown to be stable. What would happen if these bacteria were confronted with nature even though they were not intended there? Are we sure that the transformed or amplified DNAs will not be combined with the natural DNA, as their relationships will have changed? This fear was mentioned in an article published in June 2021 in the journalScience Advisory Board [10] : “Bioengineers have a moral obligation to develop a deeper understanding of how synthetic biosystems will continue to evolve if implemented in our bodies or in the wider environment … to ensure that there are no unexpected errors or negatives consequences associated with the technologies“.

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