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Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Cambridge scientists create the world's first living organism with completely redesigned DNA | science

Cambridge scientists create the world's first living organism with completely redesigned DNA | science



Scientists have created the first living organism in the world to have a fully synthetic and radically altered DNA code

Laboratory microbe, a strain of bacteria normally found in soil and in the human intestine, is similar to its microorganisms. natural cousins ​​but survive on a smaller set of genetic instructions

The existence of an error proves that life can exist with a limited genetic code and paves the way for organisms whose biological mechanisms are designed to produce medicines and useful materials, or to add new functions.

In a two-year effort, researchers at the Molecular Biology Laboratory at Cambridge University read and revised the DNA of the bacterium Escherichia coli E coli Escherichia coli E coli ), before the formation of cells with synthetic version of altered genome

Artificial genome has 4m base pairs, units of genetic code expressed by letters G, A, T and C. Printed in full on A4 sheets, it runs at 970 pages, making the genome the far away that scientists ever built .

"It was quite clear whether it was possible to make the genome so big and whether it was possible to change so much," said Jason Chin, a synthetic biology expert who led the project.

DNA coiled inside a cell stores the instructions it needs to function. For example, when a cell needs more protein for growth, it reads DNA that encodes the correct protein. DNA letters are read in triplets called codons, such as TCG and TCA

Almost all of their lives, from jellyfish to humans, they use 64 codons. But many of them do the same job. A total of 61 codons make 20 natural amino acids that can be strung as beads on a cord to create any protein in nature. Three other codons are basically stems: they notify the cell when the protein is done, as it is at the end of this sentence, as it is at the end of this sentence.





<img class = "gu-image" itemprop = "contentUrl" alt = "New synthetic organism, Escherichia coli Syn61, on the plates, synthetic organism,
Escherichia coli
Syn61 on plates. Photo: Background
By doing so, Cambridge decided to rework the genome of E coli by removing some of its excess codons. The scientists worked on the computer and went through the bug DNA. Whenever they encountered TCG, the codon that makes the amino acid called serine was rewritten as AGC, which does the same job. In a similar manner, they replaced the other two codons

More than 18,000 adjustments later by scientists removed each occurrence of these three codons from the genome of the error. The revised genetic code was then chemically synthesized and piece by piece added to E coli where it replaced the natural genome of the organism. The result reported in Nature is a microbe with a completely synthetic and radically altered DNA code. Known as the Syn61, the error is slightly longer than usual, and grows slower, but still survives

"It's amazing," Chin said. When the mistake was made, shortly before Christmas, the research team had a lab photo with a plate of microbes as the central figure in birth recreation.

Such design life forms could be useful. Because their DNA is different, invasive viruses will try to spread to them, making them effective against viruses. This could bring benefits. E E. coli already uses the biopharmaceutical industry to produce insulin for diabetes and other drug substances for cancer, multiple sclerosis, heart attacks and eye diseases, but the whole production can go wrong when the bacteria are cultured. contaminated with viruses or other microbes. But that's not all: in future work, the released genetic code could be replaced so that the cells spew out on design enzymes, proteins, and drugs


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In 2010, American scientists announced the creation of the first organism in the world with a synthetic genome. This error, Mycoplasma mycoides has a smaller genome than E coli – about 1 m base pairs – and has not been radically redesigned. Clyde Hutchison, an American research group who commented on the latest work, said: "This genome replacement scale is greater than any complete genome replacement that has been published so far."

Levels, not only successful building of the largest synthetic genome yet, but that most coding has changed to a genome so far, ”said Tom Ellis, synthetic biology researcher at Imperial College London.

long. Ellis and others build a synthetic genome for baker's yeast, while Harvard scientists make bacterial genomes with multiple coding changes. Not surprisingly, the elaborate E coli does not grow as natural strains. "If something is surprising, it grows after many changes," he said.


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