Team:Toulouse/ethics

From 2014.igem.org

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<p class="title1">SubtiTree</p>
<p class="title1">SubtiTree</p>
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<p class="texte"<B>Survival in the environment</B>
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<p class="texte">SubtiTree will live in sap tree, that is why we use one endophyte Bacillus subtilis strain. In order to contain our bacteria in this area during a short period of time, we modified some of its survival characteristics. 
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First, the control of synthetic bacterium location concerned us,that is why we border it inside the plane tree. Sap tree is known to contain a certain quantity of proline which could allow bacterial growth whereas the soil is composed by only trace of this amino acids. Thus we decide to delete the proline production pathway to make an auxotrophic bacterium for this amino acid.
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<p class="texte" style="text-align:center"><B> Gene transfer</B>
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<p class="texte">Secondly, SubtiTree is an annual bacterium to avoid any kind of mutations. It is known that endophyte bacteria must sporulate to survive to winter. Thus, we chose a B.subtilis strain without late genes of sporulation. So SubtiTree is a non-sporulation bacterium, which means that in stress conditions (cold temperature, food lack …) or outside the sap, the bacterium will not resist and die.</p>
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<p class="texte">These two characteristics of SubtiTree show that it’s an annual bacterium, which can only grow in sap tree. Combined they prevent any long term colonization of an ecological niche by SubtiTree against wild bacteria. These prevent any long term effect.</p>
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<p class="texte"> We try to respond to bacterial spread problem, at the same time we wonder about horizontal gene transfer. The transmission of some genes from our synthetic bacterium to wild bacteria could be block with two modifications. 
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First, as used in genetic engineering, plasmids are a tremendous way to transfer some genic information. In this way, it’s not the best way to restrict the collecting transgenic DNA. That is why we insert our genes in the bacterium chromosome.
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<p class="texte" style="text-align:center"><B>Survival in the environment</B>
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<p class="texte">Secondly, some bacteria are able to accept chromosomal DNA, like Bacillus subtilis. Thus, the previous strategy is enough not efficient to prevent transfer. We could include the toxin/anti-toxin system. The toxin gene is near to our synthetic gene, contrary to the anti-toxin gene. So if there is a transfer of our synthetic gene, the toxin gene will be included in the transfer. Receiver bacteria will die by the production of the toxic protein. </p>
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<p class="texte" style="text-align:center"><B>Survival in the environment</B>
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<p class="texte">Our synthetic genes are not the only problem in the design of SubtiTree. One of the side effects of our cloning method is the persistence of antibiotic resistance genes. This is incompatible with the introduction of SubtiTree in the environment. It is possible to delete this resistance in chromosome. To conclude, the spreading limitation as shown before makes the use of SubtiTree acceptable in the wild.
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<p class="texte" style="text-align:center"><B>Survival in the environment</B>
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<p class="texte">Of course, men are responsible for their mistakes such as the introduction of Ceratocytis platani and should fix it by any way. But is it too stupid to think that nature will respond to this threat? Since ages nature was able to keep its balance, if one specie dies another takes the place. So if all plane-trees die by this disease, there will be another species which will be able to take up this ecological niche. This project just shows the wish of humanity to interfere in the nature. </p>
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Revision as of 11:44, 12 October 2014