Avoiding Transgene Silencing

There are a number of steps that can be taken in the construction of plant-derived biopharmaceuticals in transgenic plants that would effectively reduce gene silencing (De Wilde et al., 2000). These are explained in the following sections. 

Biopharmaceuticals in Plants Toward the Next Century of Medicine 

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Plant phytoene synthase (Psy) has been used in a variety of transgenics. As noted above, P yl over-expression under a strong constitutive promoter caused a decrease in carotenoid accumulation, probably due to transcription silencing. Similarly, over-expression of the gene sequence backward (antisense) also silenced activity. In another approach to over-expression of tomato 1 in fruits, a synthetic alternative in which the third position of each codon was changed in order to avoid transcriptional silencing was successful in conditioning an increase in carotenoid accumulation. 

De Wilde, C., Van Hondt, H., De Buck, S., Angenon, G., De Jaeger, G., and Depicker, A. (2000). Plants as bioreactors for protein prodnction avoiding the problem of transgene silencing. Plant Mol. Biol. 43 347-358. 

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