From the Article



Background - Barriers to HGT

When considering:

a.. the degree to which millions of species co-exist in close
physical contact with each other,
b.. the ability of viruses to move freely between host
organisms, and
c.. the amount of DNA in certain environments,
one realizes the trivial amount of HGT that occurs is actually
remarkable.

While I agree that the "basic" concepts are the same you are
comparing apples and oranges, when you say it is "possible" for these genes
to "migrate" -



to further quote



Utilizing a different model system, Schluter et al. (1995)
attempted to stimulate HGT between biotech potatoes and Erwinia
chrysanthemum, a pathogen tightly associated with potatoes, in order to
calculate rates of HGT under a wide variety of conditions. Under conditions
they describe as "idealized" natural conditions, they calculated a HGT
frequency of 2 X 10 -17, a rate they describe as "so rare as to be
essentially irrelevant in any realistic risk assessment of biotech crops."
These idealized natural conditions included using a bacterial marker gene
linked to a functional origin of replication. It is important to note that
most transformed plants do not contain origins of replication in their
transgenes. Therefore, one might expect the frequency of transformation with
transgenes to be even lower than the 2 X 10 -17 calculated by Schluter et
al. (1995).

Abl5 - your article only further proves the point that the sky
is not falling

Thanks for helping to prove my argument!



Tomatolord





wrote in message
ub.duke.edu...
On Mon, 15 Aug 2005, tomatolord wrote:

How is it possible for the DNA of corn plant to "spread" to the dna of a
weed?

It's basically the same concept as DNA spreading between different kinds
of bacteria, I think -- instead of the DNA being part of a long string of
chromosomal DNA, it floats around inside the cell on a little circle of
DNA (plasmids). This stuff can be passed between cells & even to other
[sufficiently similar] organisms because it can be small enough to get
past the anti-alien-DNA mechanisms.

In many plants, _Agrobacterium_ species bacteria can often be used to
transfer new DNA into a plant via a cut or wound in the plant. Since these
guys form little tumor balls on the roots of many plants, they could
potentially grab DNA from one plant and trasnfer to another.

Let's see... pollen was already mentioned as a possibility. A different
kind of infective plant virus or bacterium could transfer the genes
(especially viruses -- some of them are particularly good at picking up
genes from an organism and donating them elsewhere)... Some people think
that when root cells are sloughed off into the soil, soil microorganisms
could take it up.

Anyway-- basically, intraspecies pollination is really easy, some of the
other mechanisms are less likely. Doesn't mean they couldn't happen.

For a more technical description, see:
http://www2.dupont.com/Biotechnology...narrative.html