Modified genetic alphabet: Chemical evolution generates bacterial strain with artificial nucleotide in its genome
(PhysOrg.com) -- Evolution is based on heredity, changes to the genetic material (mutation), and the natural selection of those organisms that are best suited to the given environmental conditions. An international team led by Rupert Mutzel at the Freie Universität of Berlin has now successfully emulated one particular evolutionary process in the laboratory. As the researchers report in the journal Angewandte Chemie, they were able to generate a bacterial strain whose genetic material contains an artificial building block in place of a natural one. Their success results from a special automated cultivation technique.
DNA, the carrier of the genetic information of all cells, is based on a code consisting of four “letters”, the bases adenine, cytosine, guanine, and thymine. Thanks to their new artificial evolution process, the scientists have now been able to grow bacteria in which the thymine of DNA has been replaced with an analogue, the base 5-chlorouracil. This synthetic component is poisonous to other organisms.
The researchers started with a genetically modified strain of the bacterium Escherichia coli that is no longer capable of producing thymine. These microorganisms were cultivated over many generations in the presence of increasing amounts of chlorouracil in a specially built apparatus. Whenever the size of the population sank below a certain level, the bacteria were given a brief dose of a chlorouracil-free, thymine-containing medium to give them a chance to recover. The concentration of chlorouracil was automatically increased whenever genetic variants of the bacteria that better tolerated this substance were produced.
In this way, the cells were always exposed to a quantity of chlorouracil that was just barely tolerable. After about 1000 generations, the microorganisms had adapted to the altered environmental conditions, that is, the presence of chlorouracil instead of thymine. They were able to build up their DNA with chlorouracil in place of thymine. Analysis of the genome showed that the process of adaptation resulted in many changes to the genetic material of the bacteria.
“Our results demonstrate the success of our evolutionary cultivation strategy,” says Mutzel. “In this way it should be possible to develop microorganisms that can convert chemical intermediates to pharmaceuticals or break down environmental pollutants.” Microorganisms that have DNA with synthetic building blocks may also be useful in hindering the spread of purposely or accidentally released modified cells in the environment. Such microorganisms would also be incapable of exchanging genes with their natural relatives.
More information: Rupert Mutzel, Chemical Evolution of a Bacterium's Genome, Angewandte Chemie International Edition 2011, 50, No. 31, 7109–7114, Permalink to the article: http://dx.doi.org/ … ie.201100535
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Jul 19, 2011
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Jul 19, 2011
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If yes, then what happens when the modified bacteria spread to the environment. They would have no natural predators to eat them.
Jul 19, 2011
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Jul 19, 2011
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Jul 19, 2011
Rank: 5 / 5 (4)
That would be one rough synthesis. It would be easy to add Cl to the structure without removing anything, but that methyl group isn't coming off by itself; pulling a CH3 off of a larger molecule is one of the hardest things one can attempt in organic synthesis. The double bond at the point of substitution makes the elimination of the methyl group even less likely, as the leaving group will be CH3 instead of CH4 (VERY unfavourable). Those nitrogens in the ring structure are "ortho-para-directing," while the point of desired substitution is 'meta' to both of them; even if you could get the methyl group off, the Cl would end up being added to the wrong spot.
Basically, it would need to evolve its own specific enzyme for the process. Many generations would have to survive in a chlorouracil-free environment for that to happen. Not impossible, but I wouldn't hold my breath.
Jul 20, 2011
Rank: 1 / 5 (2)
There is no such intellect yet on this Planet to predict it.
Dont play with it, this coli bacteria has been turned in lab rat for the scientists, more they use it, more other people will use it.....like the drosophila fly.
There are so much other bacteria.....
Jul 20, 2011
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Jul 20, 2011
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Smart guy wont be so certain about that.....