Release date: 2014-05-12
Sina Technology News Beijing time on May 9th news, according to the "Nature" magazine website, billions of years, all life on the earth is written in simple A, T, C and G. They constitute the structure of DNA and exist in all living things. Now, this list of letters may have to be extended. The researchers said they created a living artificial cell containing two types of "foreign" DNA components.
Many scientists see this achievement as a major breakthrough and an important step toward the synthesis of special cells that will produce drugs or other useful molecular substances. Even it opens up the possibility that one day we will not have to build a cell body with the help of the existing four DNA components.
Floyd Romesberg is from the Scripps Research Institute in La Yola, California, and is the leader who has been working for 15 years. He said: "What we are getting now is a living cell that stores genetic information." Their research paper was published in the journal Nature today.
DNA is a double helix. Each of its chains has a sugar molecular chain as its backbone and is connected to some secondary structure, such as chemical base pairs. There are four different bases in total: adenine (A), guanine (G), cytosine (C), and thymine (T). These different letters represent different ways of encoding the amino acids that make up the protein. The base connects the two DNA strands together, where A is always connected to T on the opposite strand, and C corresponds to G.
Letters in test tubes
Scientists have been thinking about the question since the 1960s: Can other informational storage be used to store information? But it was not until 1989 that Steven Benner of the Swiss Federal Institute of Technology and his research team successfully implanted the modified cytosine (C) and thymine (T) into DNA for the first time. In the reaction tests carried out in test tubes, the DNA strands, which were called "interesting letters" by Professor Benner, successfully replicated themselves and produced RNA and proteins.
According to Bernard, the bases obtained by the Romsberg study group have changed even more, and the difference between the four natural base components of nature is more significant. In an article published in 2008 and in subsequent experiments, the team reported pairing efforts in 60 candidate bases and tried more than 3,600 combinations. In the process they identified a base pair, called "d5SICS" and "dNaM", which seemed to be promising to succeed. The key point is that these molecules themselves must match the catalytic enzyme mechanism, which is tasked with helping with DNA replication and interpretation.
Denis Malyshev is a former graduate of the Romsberg Laboratory and the first author of this latest research paper. He said: "We didn't even think about it at the time that we would eventually create a cell body that implanted this base pair." Through a test tube experiment, the research team succeeded in implementing the modified base pairs they developed. Copy and produce RNA. This requires the bases they make to be recognized by the enzyme, which previously only recognized A, T, C and G.
The first challenge in creating an artificial living organism is to allow cells to accept foreign bases so that they can maintain DNA molecules during multiple cell divisions, during which DNA is replicated. The team engineered E. coli to express a gene from diatoms, a single-celled algae. The result of this expression process is the availability of a protein that allows the molecule to pass through the outer membrane of E. coli.
The team produced a small piece of DNA called a plasmid containing a foreign base pair and injected it into E. coli. As the diatom's protein supplies nutrients to foreign nucleotides, this plasmid successfully replicates itself and replicates itself in the new division of E. coli in the next week. in. When the nutrient supply from the protein is finally depleted, E. coli replaces the previously injected foreign ingredients with natural components.
External control
Maleshev will control the ability of foreign DNA to be absorbed as a safe means once these artificial cells leak out of the laboratory. But other researchers, including Bena, are working to transform cells so that they can directly produce certain foreign bases, thus directly eliminating the culture process.
Romsberg's team is currently trying to get foreign DNA to encode proteins instead of decoding the 20 amino acids that together make up all the proteins in nature. Amino acids are encoded by codons consisting of three DNA bases, so the extra addition of two foreign DNA "letters" will greatly enhance the ability of cells to encode new amino acids. Romsberg said: "If a book can only be written in 4 letters, it is difficult to tell some interesting stories. If you allow more letters, you can invent new words and find them. With the new method of using these words, you may be able to tell more interesting stories."
What are the potential application prospects of this technology? First, we can implant toxic amino acids into the protein, ensuring that it only attacks the soldiers to kill the cancer cells. In addition, this technology can also be applied to fluorescent amino acids to help scientists track biological reactions under the microscope. Romsberg's team has now found a company called "Synthorx" in San Diego, Calif., to try to commercialize the work.
Ross Thyer is a synthetic biologist from the University of Texas at Austin and co-author of related papers. He said: "It is a leap to expand our capabilities." There is now the possibility of giving foreign DNA the ability to encode new amino acids.
Bena said: "Many people in the academic world think that the results of Romsberg are impossible to achieve." This is because the chemical reactions involving DNA, such as the replication process, must be extremely careful to avoid mutations.
The modified E. coli contains millions of DNA base pairs, of which only one pair is foreign. But Benner believes that there is no reason to believe that it is impossible to make cells that are completely constructed from foreign genes in the future. He said: "I don't think there is a limit here. If you go back to the past and repeat the 4 billion years of evolutionary history, you will get a completely different genetic system."
But to create a complete synthetic life will be a huge challenge. Romsberg said: "Many times people will say that you will create a living body that is completely synthesized by unnatural DNA." He said: "But that doesn't happen because there are too many to reorganize DNA. The factor is that it is integrated into every aspect of cell life."
Wood Chipper Shredder,Drum Wood Chipper,Wood Cutting Chipper Machine,Firewood Chipper Making Machine
Shandong Longze Mechanical Equipment Co.,Ltd , https://www.pelletmachinefactory.com