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Re: Glickman and Biotech



In article <E11IC5.KrA@plamondon.COM> on  Mon, 18 Nov 1996 00:21:41 GMT 
robert@plamondon.COM (Robert Plamondon) wrote:

> ... You go looking for a string match in
> the genes of some organism or other.  It doesn't matter which.
> You paste the right string in the right part of the code.  If the
> organism "runs" properly after being compiled, you know you got it
> right.  A certain amount of testing is in order, but it's not as if
> you have to retest the entire operating system every time you write
> a device driver.  You run regressions on the parts that interact
> with the area you changed.

Regrettably that is not how it is done: in the case of RR Canola the 
insertion of the foreign bacterial genes conferring the Roundup 
resistance is randomly inserted:

    >>2. Development Method 

    Brassica napus variety "Westar" was transformed using a disarmed
    non-pathogenic Agrobacterium tumefaciens vector, i.e., the T-DNA
    region of an A. tumefaciens plasmid from which virulence and
    disease causing genes were removed, and replaced with the
    Roundup-Ready genes. The T-DNA portion of A. tumefaciens plasmids
    are generally known to insert randomly into the plant's genome
    and the insertion is usually stable, as was shown to be the case
    in GT73.<<

and what genes were inserted? Two bacterial ones and one plant derived. 
(The last sentence of the first para is frightening. Just reading it 
myself again I find the term tryptophan rings alarm bells too...)

    >>Two genes have been introduced into the variety "Westar", which
    in combination provide field level tolerance to glyphosate the
    active ingredient in Roundup herbicide. The exact nature of these
    genes is considered confidential business information by
    Monsanto.

    The first gene expresses a bacterial derived version of a plant
    enzyme involved in the shikimate biochemical pathway for the
    production of the aromatic amino acids phenylalanine, tyrosine
    and tryptophan. The plant version of this enzyme, ubiquitous in
    nature, is sensitive to glyphosate - the herbicide disrupts this
    essential pathway, leading to growth suppression or death of the
    plant. However, the bacterial derived version of this enzyme is
    highly insensitive to glyphosate and fulfils the aromatic amino
    acid needs of the plant.

    The second gene, also bacterial derived from a strain of a
    species ubiquitous in nature, expresses an enzyme that degrades
    glyphosate, thereby deactivating the herbicidal effect. The
    coding sequence of this gene has been altered to enhance the
    efficiency of glyphosate degradation, compared to the original
    version. 

    A plant-derived coding sequence expressing a chloroplast transit
    peptide was co-introduced with each of the Roundup-Ready genes.
    This peptide facilitates the import of the newly translated
    Roundup-Ready enzymes into the chloroplasts, the site of both the
    shikimate pathway and glyphosate mode-of-action.<< 


William |WRC Solutions: Computer Consultants|Tel (+44)(0)1695  50470
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