Team:Toulouse/Project/Spreading

From 2014.igem.org

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The goal of this module is to prevent horizontal transfer between bacteria. Indeed, it is necessary to avoid any exchange of genetic material between wild type organisms and optimized organisms : it could be dangerous because of mutations, and considering ethics, it seems to be essential to avoid the spreading of synthetic genes.<br/>
The goal of this module is to prevent horizontal transfer between bacteria. Indeed, it is necessary to avoid any exchange of genetic material between wild type organisms and optimized organisms : it could be dangerous because of mutations, and considering ethics, it seems to be essential to avoid the spreading of synthetic genes.<br/>
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Considering this issue, we thought about a system to avoid such transfers : a toxin-antitoxin module. It involves the addition of two genes to the bacterium : a gene encoding for a toxin (for example tse2) and a gene encoding for the antitoxin (tsi1), placing them in an opposite way on the genome. The large space between them will permit to avoid simultaneous transfers : if the optimised bacterium transfers the gene encoding for the toxin, the probability that the gene encoding for the antitoxin may be transferred simultaneously is really low since they are located far away from each other.<br/>
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Considering this issue, we thought about a system to avoid such transfers : a toxin-antitoxin module. It involves the addition of two genes to the bacterium : a gene encoding for a toxin (for example <i>tse2</i>) and a gene encoding for the antitoxin (<i>tsi1</i>), placing them in an opposite way on the genome. The large space between them prevents simultaneous transfers : if the optimised bacterium transfers the gene encoding for the toxin, the probability that the gene encoding for the antitoxin may be transferred simultaneously is really low since they are located far away from each other.<br/>
Therefore, if the host bacterium receives the gene encoding for the toxin, it will be unable to survive since it will not have the antitoxin. If it receives the antitoxin only, it will not be useful for the bacterium, and will not affect it.<br/>
Therefore, if the host bacterium receives the gene encoding for the toxin, it will be unable to survive since it will not have the antitoxin. If it receives the antitoxin only, it will not be useful for the bacterium, and will not affect it.<br/>
To sum up, since a simultaneous transfer is dimly probable, the bacterium will either die because of the toxin or live while expressing the antitoxin (useless).  
To sum up, since a simultaneous transfer is dimly probable, the bacterium will either die because of the toxin or live while expressing the antitoxin (useless).  
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<p class="title1">Using integrative plasmids</p>
<p class="title1">Using integrative plasmids</p>
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All our constructions should be carried by integrative plasmids. Consequently, our different genetic modules would be integrated into the bacterium genome. The integration in the genome is more stable as the constructions are less likely to be transferred to other microorganisms. In addition to that, the expression of our genetic modules would not be dependant on a selective pressure based on an antibiotic resistance (as we can not inject antibiotics in the tree), allowing a high level of transcription in planta.  
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All our constructions are carried by integrative plasmids. Consequently, our different genetic modules would be integrated into the bacterium genome. The integration in the genome is more stable as the constructions are less likely to be transferred to other microorganisms. In addition to that, the expression of our genetic modules would not be dependant on a selective pressure based on an antibiotic resistance (as we can not inject antibiotics in the tree), allowing a high level of transcription in planta.  
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Revision as of 15:02, 12 October 2014