/Nexus - 0601 - New Times Magazine/pages/0031/image.png)
Page Content (OCR)
tection from pathogens. Thus, the indiscriminate killing of bacte-
ria does have health effects on humans (and, indeed, animals) by
upsetting the ecology of the human/bacteria system. In fact, the
patient information sheet that comes with any prescription for
tetracycline is convincing evidence that tetracycline is not harm-
less to use.
Plants, too, depend on micro-organisms. They do not function
normally without a web of interactions, and indirect effects from
substances like tetracycline may prove to be important.
this phenomenon occurred with seeds containing the Terminator
gene, plants containing the silenced toxin gene could grow and
reproduce, perhaps for several generations. Thus, Terminator and
other engineered genes could be carried into the future, to be
expressed—perhaps still unexpectedly—at some later time.
Depending on Terminator to prevent GMOs or their traits from
spreading unintentionally is unrealistic. 'Escapes' are even more
likely to occur in some of the other patent applications, where the
genetic components of Terminator will reshuffle during sexual
reproduction, and a portion of the seeds will lack the toxin alto-
gether and thus be viable.
- Will Terminator Technology prevent genetically
modified organisms from escaping?
Clearly, farmers would not want plants genetically modified
with Terminator to spread into surrounding areas or to grow from
seed as unexpected 'volunteers' in another season. They also
would not want the Terminator plants to exchange genes with
other varieties or related species. Interestingly, Terminator has
been proposed as a method to prevent just such escapes of GMOs
and their genes. However, Terminator is not likely to function
well for such purposes.
First, it is unlikely that any tetracycline treatment will be 100
per cent effective. For various reasons, some seeds may not
respond or take up enough tetracycline to activate recombinase.
In such cases, the plants growing from the unaffected seeds would
look just like all the others, but they would grow up to make
pollen carrying a non-functional toxin gene.
The pollen would also carry the genetically engineered protein
(e.g., for herbicide tolerance) supposedly being protected by
Terminator. If this pollen fertilised a normal plant, the seed
would not die because no toxin would be made, but the seed
would now have the herbicide-tolerance gene and could pass that
on. Thus a trait from the GMO would have escaped through the
pollen.
Of course, self-fertilised seeds of the Terminator line would
also survive in the second generation if the tetracycline treatment
failed, and could be carried off by birds or grow as 'volunteers' the
next season.
Another possibility is that even successfully activated
Terminator genes may fail to make toxin because of a phenome-
non called 'gene silencing’. In experiments with other GMOs, it
was discovered—quite unexpectedly—that, in some cases, previ-
ously active (introduced) genes can suddenly stop working. If
- Will Terminator genes mutate and change
characteristics in some dangerous way?
If plants were to carry silenced toxin genes, as described above,
those genes might suddenly be activated again, causing seeds to
die unpredictably in subsequent generations. By the time the phe-
nomenon occurred, however, it might be difficult to ascribe the
cause to Terminator.
Another possibility is that the Terminator may be activated at a
different time or place in the plant. Fortunately, such events will
be self-limiting because the plants will die.
However, for farmers, the instability and unpredictability of
GMOs has already been an economic problem. Genes have an
ecology—a complex way of interacting with themselves and the
environment—that can interfere with the simple linear logic of
genetic engineering.
A recent article in The Ecologist discussed this problem in
detail (Ho et al., 1998).
Final Thoughts on Terminator Technology
These are a few of the potential snags that I see in the use of
Terminator Technology. My analysis was based on the details of
only one of the applications described in the Terminator patent. I
am confident that some of the particular problems I have dis-
cussed will be addressed by the seed industry before they imple-
ment the technology.
However, I am also sure that there will be other problems no
one yet foresees or imagines. There will be surprises. But what-
ever the potential biological problems presented by Terminator, in
my view they are small in comparison to Terminator's economic,
social and political ramifications (see RAFI, 1998). co
References Terminator Technology. These can be accessed About the Author:
= Ho, Mae-Wan, Genetic Engineering: Dream at RAFI's website at