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Rescooped by Christian Faltado Cantos from Amazing Science
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Editing the genome with high precision and inserting multiple genes into specific locations

Editing the genome with high precision and inserting multiple genes into specific locations | Multi- gene | Scoop.it

Researchers at MIT, the Broad Institute and Rockefeller University have developed a new technique for precisely altering the genomes of living cells by adding or deleting genes. The researchers say the technology could offer an easy-to-use, less-expensive way to engineer organisms that produce biofuels; to design animal models to study human disease; and  to develop new therapies, among other potential applications.

To create their new genome-editing technique, the researchers modified a set of bacterial proteins that normally defend against viral invaders. Using this system, scientists can alter several genome sites simultaneously and can achieve much greater control over where new genes are inserted, says Feng Zhang, an assistant professor of brain and cognitive sciences at MIT and leader of the research team.  

“Anything that requires engineering of an organism to put in new genes or to modify what’s in the genome will be able to benefit from this,” says Zhang, who is a core member of the Broad Institute and MIT’s McGovern Institute for Brain Research.

 

Complexes known as transcription activator-like effector nucleases (TALENs) can also cut the genome in specific locations, but these complexes can also be expensive and difficult to assemble. The new system is much more user-friendly than TALENs, Zhang says. Making use of naturally occurring bacterial protein-RNA systems that recognize and snip viral DNA, the researchers can create DNA-editing complexes that include a nuclease called Cas9 bound to short RNA sequences. These sequences are designed to target specific locations in the genome; when they encounter a match, Cas9 cuts the DNA. 

This approach can be used either to disrupt the function of a gene or to replace it with a new one. To replace the gene, the researchers must also add a DNA template for the new gene, which would be copied into the genome after the DNA is cut. 

Each of the RNA segments can target a different sequence. “That’s the beauty of this — you can easily program a nuclease to target one or more positions in the genome,” Zhang says. 

The method is also very precise — if there is a single base-pair difference between the RNA targeting sequence and the genome sequence, Cas9 is not activated. This is not the case for zinc fingers or TALEN. The new system also appears to be more efficient than TALEN, and much less expensive. 


Via Dr. Stefan Gruenwald
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Rescooped by Christian Faltado Cantos from Amazing Science
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Genome Engineering of Crops with Designer Nucleases

Genome Engineering of Crops with Designer Nucleases | Multi- gene | Scoop.it

Shaun J. Curtin et al. (2012)

Recent advances in the field of genome engineering indicate that it will soon be routine to make site-directed modifications to the genomes of crop species, including targeted mutations, gene insertions, and gene replacements. This new technology will be used to help elucidate gene function and develop new and valuable traits. Key to enabling site-directed genome modifications are sequence-specific nucleases that generate targeted double-stranded DNA breaks in genes of interest. To date, three different sequence-specific nuclease systems have been used in crop plants: zinc finger nucleases, transcription activator-like effector nucleases (TALENs), and LAGLIDADG homing endonucleases, also termed “meganucleases.” In this review, we report on the current state of genome engineering in crop plants, comparing the different nuclease and gene delivery systems. We also consider some of the limitations that nuclease-mediated crop improvement technologies may encounter.

 

More TALEN news on: http://www.scoop.it/t/tal-effector-science


Via dromius, Dr. Stefan Gruenwald
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