See also: Transgénèse (homonymy)
The transgenèse is a technique consisting in introducing one or more Gène S into cells (for example vegetable or animal) driving with the transmission of the introduced Gène, or Transgène, with the successive generations.
The transformed organization is called Organisme genetically modified (GMO), or organization Transgénique.
The genetic transformations of unicellular organizations or Virus are relatively simple to approach. They call upon techniques definitely more complex for the animals and plants.
Production of individuals transgenic
The transgenèse comprises several stages:-
identification and localization of the “Gene of interest”, person in charge of the characteristic considered to be interesting to transfer (for example resistance to the bee moth is carried by gene LT in the Maïs LT).
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the insulation of this gene.
- the construction of transgene. It implies to isolate the sequence coding the Protéine from interest to add, then to add upstream gene a Promoteur (in order to allow the transcription) and downstream from terminating of transcription.
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the realization of a “genetic construction” (comprising gene of interest and the sequences of regulation necessary to its expression in the organization receiver) and its insertion in a Plasmide, inner loop of DNA of origin Bacterium not serving as “case” of transfer of gene of interest. The sequences of regulation comprise obligatorily a promoter adapted to the organization receiver. A sequence is a sequence of Nucléotide S particular. The choice of the promoter makes it possible to direct the form of gene, to limit it to part of the organization (sheets or roots, glands mammaires…) or at a stage of its development.
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the transformation of the target organization, with a penetration of DNA in the cell, and the integration of genetic information. The introduction of the plasmide modified into the genome of the cell, is done by a biological vector (a Agrobacterium or a “disarmed” virus) or by a mechanical process (projection of tungsten microballs carrying the plasmide). It is also possible to introduce genic construction directly, by microinjection in the cell.
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selection of the transformed cells, with the assistance for example, of discriminating elements included in transgene. Thus, by introducing a gene of resistance to an antibiotic into the plasmide and by putting the bacteria transformed into contact with the Antibiotic concerned, will survive only the bacteria having received transgene.
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multiplication of the transformed cells.
Differences between the traditional transgenèse and methods of improvement
Benefit:
- Advantages of purity and speed: The transgenèse makes it possible to introduce a single character interesting, and this, in only one stage. The traditional techniques give individuals having inherited of more than one character, and this, after several generations of crossings.
- very diverse Possibilities of crossings: The traditional methods make it possible to exchange genes only inside one species or all at least between relatively close species. The transgenèse, on the other hand, allows the introduction into an organization receiver of a gene coming from any organization donor, even of an artificial gene.
Disadvantages:
- It is necessary to identify and of cloner the sequence of interesting genes, then to synthesize In vitro these genes before carrying out the transgenèse.
- the transgenèse allows the introduction only one character coded by one gene or a small number of genes, being given the difficulty of the preparation of transgenes and their introduction into the targeted cells.
See too
- Paul Berg
- Topicality of food safety and agricultural biotechnology - Information balanced concerning the debate on cultures GM
Simple: Genetic engineering
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