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Old 08-10-2003, 04:22 PM
Peter Ashby
 
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Default A Danger to the World's Food: Genetic Engineering and the EconomicInterests of the Life Science

In article ,
"pearl" wrote:

'The release of transgenic crops into the environment has raised
concerns over the spread of transgenic DNA, not only by cross-
pollination to related species, but especially by horizontal gene
transfer to unrelated species (reviewed by Ho et al (1) and
Traavik (2)). On account of the _persistence_ of DNA in all
environments, and the ability of practically all cells to take up
'naked' or free DNA, the success of horizontal gene transfer may
depend largely on the nature of the DNA itself. New revelations
concerning the CaMV recombination hotspot (3) have prompted
us to consider the safety implications of the CaMV promoter.
That is all the more urgent as CaMV promoter is in practically
all transgenic crops already released commercially or undergoing
field trials.


It is clear that the CaMV 35S promoter is well-endowed with
motifs involved in recombination. An additional factor which
may increase the instability of the plasmid is the junction between
CaMV 35S promoter and foreign DNA. All these considerations
make it highly likely that the CaMV 35S promoter will take part
in horizontal gene transfer and recombination, and also cause
largescale genomic rearrangements in the process.

Horizontal transfer of the CaMV promoter not only contributes
to the known instability of transgenic lines (30), but has the
potential to reactivate dormant viruses or creating new viruses in
all species to which it is transferred, particularly in view of the
modularity and interchangeability of promoter elements (8). In
this regard, the close relationship of CaMV to hepadnaviruses
such as the human hepatitis B is especially relevant. In addition,
because the CaMV promoter is promiscuous in function (see
above), it has the possibility of promoting inappropriate over-
expression of genes in all species to which it happens to be
transferred. One consequence of such inappropriate over-
expression of genes may be cancer. ....'
http://www.i-sis.org.uk/camvrecdis.php



Good grief have these people no basic biology? Firstly they seem to
confer magical malicious properties on a promoter sequence. So it might
recombine? so might many thousands of other sites all over the
integrated genome, including endogenous retroviruses. There is nothing
there to suggest A) that this promoter would recombine preferentially
compared with endogenous viral promoters in the plant genome. or B) that
this magically malicious promoter would be able to do anything once
recombined. As an analogy, is an isolated light switch lying on a bench,
not connected to anything dangerous? No, so why should a promoter
sequence be? Both are switches, not effectors.


And finally, if lateral gene transfer was as likely as this piece of ill
thought out polemic hints then differential forms of life would never
hav evolved. As soon as one population evolved away from another lateral
transfer would drag them back to the median again. This is
scaremongering masquerading as science, pure and simple. You may want to
look further at the source to find why too. Not exactly unbiased.

Peter

--
Peter Ashby
School of Life Sciences, University of Dundee, Scotland
To assume that I speak for the University of Dundee is to be deluded.
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