Selection markers Morphological changes

Upon transfection, there are cells that incorporate the plasmid (transfected) and others that do not (wild-type). A selection system allows the separation of these two cell populations. In this regard, the detection of morphologic changes or, more commonly, the use of some toxic metabolite for which the vector confers resistance (biochemical markers) have become the methods of choice to select positive transfectants. 

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