An international group of scientists created the bacteria, the DNA of which contains the substance that does not exist on Earth. The synthetic monster, which is absolutely safe for our biosphere, was derived from common E. coli bacteria. Biologists say that the technology used in the experiment can help humans model and recreate extraterrestrial organisms.
The group of molecular biologists from Germany, France, Belgium and the USA created the bacteria that contains a non-existent substance. This substance has never been discovered either on planet Earth or in space. This is a man-made compound that became known as 5-chlorouracil.
It is an open secret that the DNA of all terrestrial creatures includes four nitrogenous bases (nucleotides): adenine, guanine, cytosine and thimine. These compounds form the functional part of the molecule known as the genetic code. Certain amino acids - protein bases - correspond to three nitrogenous bases. Thus, the succession of the construction of any protein is recorded in the DNA as the chain, in which the combinations of three nucleotides are alternated.
The scientists decided to create the bacteria, in the DNA of which they would replace one of the nitrogenous bases, namely thimine. The experiment was conducted on E. coli - the bacteria known to everyone. This microorganism has the strains, whose representatives are not capable of synthesizing thimine independently. They have to receive the compound from outside. The researchers decided to deceive the bacteria and implant a synthetic analogue of this nucleotide - the above-mentioned 5-chlorouracil.
High concentrations of this compound are toxic for the bacteria. The biologists had to proceed gradually to give the bacteria an opportunity to get accustomed to the poison. At first, they were growing colonies in the mixture in which both thimine and 5-chlorouracil were present in moderate concentrations. This contributed to accelerated selection: only the strongest organisms could survive. Afterwards, the "survivors" would be transferred to a different environment with a higher content of 5-chlorouracil and a lower content of thimine, etc. As a result, the scientists have grown the cells that did not need thimine at all. Thimine was completely replaced with the analogue of the substance. It took place in a thousand of generations of the bacteria after the beginning of the experiment.
These bacteria can divide normally. The replacement of one nucleotide did not affect the doubling ability of the DNA. All proteins, which the bacteria need, were synthesized normally as well, which means that the change has not affected the normal life of the bacteria.
It turned out, though, that the "extraterrestrials" were unable to transfer pieces of their "incorrect" DNAs to other, normal bacteria. Therefore, even if the creatures escape from the lab, they will not be able to change the genomes of normal microorganisms. They will not be able to live outside the lab either, because 5-chlorouracil can not be found in the natural world.
The researchers found out that the original DNA of E. coli also underwent significant changes. The scientists counted several hundreds of mutations in the DNA. The mutations became necessary for the new organism to become adapted to living in such unconventional environment. All of those mutations are extremely important for the bacteria. If any mutated part of the DNA retrieves the original form, the bacteria dies instantly.
What is the practical value of this experiment? As a matter of fact, it is enormous. According to the scientists, the microorganisms, whose existence depends on the substance that does not exist in nature, can be used for the production of medications, bioethanol and other chemical compounds. What is more, humans will be able to control the activity of those compounds.
In addition, the technology gives an opportunity to build extraterrestrial organisms. One will only have to find out which organic compounds exist on an explored planet. Afterwards, it will be possible to take a common bacteria and implant those compounds in its organic molecule. Observing the modified earthly bacteria, scientists will be able to describe the biological processes that could occur in the organisms of extraterrestrial creatures (if they exist, of course).
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