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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
Hite |MS-Office, Visual Basic, FTR, Text |Fax (+44)(0)1695 720889
|wrhite@cix.compulink.co.uk, http://www.u-net.com/~wrcs/home
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