Below is an important development reported by Mae Wan Ho
(Natural Law Party Wessex)
Date: 04 December 1998 15:55
Please circulate this message to whoever may be interested.
Horizontal gene transfer - new evidence
A group of researchers in Indiana University of the United
States, headed by
Dr. Jeffrey Palmer, have just reported in the current issue of
the
Proceedings of the National Academy of Sciences USA that a
genetic parasite
belonging to yeast has suddenly jumped into many unrelated
species of higher
plants recently.
This parasite is a piece of DNA called a group I intron that can
splice
itself in and out of a particular gene in the genome of
mitochondria.
Mitochondria are little power houses of the cell that oxdize food
in order
to turn it into a form of energy that can be used for all living
processes.
Until 1995, this parasite was thought to be confined to yeast and
only one
genus of higher plants out of the 25 surveyed had the parasite.
But in a new
survey of species from 335 genera, 48 were found to have the
parasite.
Moreover, all the higher plants that have gained the group I
intron has the
same one, as the DNA base sequence is more than 92% identical.
When this intron jumps into a genome, it also adds to its tail
end an extra
stretch of DNA that does not belong to the host. By comparing
this extra
tail, the researchers are able to conclude that almost all of the
horizontal
gene transfer events were independent and must have occurred very
recently.
"This massive wave of lateral transfers is of entirely
recent occurrence,
perhaps triggered by some key shift in the intron's invasiveness
within
angiosperms [i.e., higher plants]"
So, what triggered this recent explosive invasion of the higher
plants by
the particular genetic parasite? It could have got into the plant
cells by
being carried in viruses, insects or bacteria. In order to get
into the
genome, however, it has to overcome species barriers. For
example, the
genome has to have a specific site of about 20 base pairs that is
recognized
by the parasite. Furthermore, in order for the splicing gene
carried by the
parasite to become expressed, it has to have a signal that is
recognized by
the host.
The researchers themselves raise concerns about releasing
transgenic crops
into the environment, if horizontal gene transfer is so
widespread.
Only two months ago, it was reported in the Journal Nature that
genes
transferred into transgenic plants can be up to 30 times more
likely to
escape than the plant's own genes.
· Is it possible that the recent massive horizontal gene
transfer from yeast
to higher plants was triggered by commercial genetic engineering
biotechnology itself?
· Genetic engineering makes use of artificial genetic parasites
as gene
carriers, to transfer genes horizontally between unrelated
species. These
artificial parasites are made from parts of the most aggressive
naturally
occurring parasites like the group 1 intron discussed here.
· The same kinds of explosive horizontal gene transfer have
already been
documented among viruses and bacteria which are responsible for
the recent
resurgence of drug and antibiotic resistant infectious diseases
(reviewed by
Ho et al, Microbial Ecology in Health and Disease vol 10, 33-39m
1998).
· We should take this new evidence very, very seriously. There
should be an
immediate moratorium on further releases of transgenic plants, in
particular
those carrying antibiotic resistance genes like the Novartis
maize.