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ISIS Report 02/03/11
Scientists Discover New Route for GM-gene 'Escape'
Genetically modified genes can jump species
via wounds, yes horizontal gene transfer happens, and at high frequencies; it
is the greatest, most underestimated hazard from GMOs released into the
environment Dr. Mae-Wan Ho
Please circulate widely and forward to your
elected representatives
Gene “escape” a misnomer for horizontal
gene transfer
Scientists at Bristol University in the UK announced the discovery of [1] “a previously unknown route” whereby “GM genes may escape
into the natural environment.” “Escape” is a misnomer. There is no need for
the GM (genetically modified) genes to “escape”, when genetically modified
organisms (GMOs) have been released in great abundance and with gay abandon
into the environment over the past 17 years. At issue is how fast and how widely
the GM genes can spread, and what dire consequences could arise.
The “escape”
referred to is horizontal gene transfer – the spread of GM genes by infection
and multiplication (literally like a virus) regardless of species barriers;
hence the rate of spread is much more rapid, and the extent virtually
unlimited. New combinations of genetic material are created at unprecedented
speed; affecting species the most that reproduce the fastest, i.e., bacteria
and viruses that cause diseases. Horizontal gene transfer and recombination is indeed
a main route for generating new strains of bacteria and viruses that cause
diseases. Genetic modification and release of GMOs into the environment is nothing
if not greatly facilitated horizontal gene transfer and recombination. It has
created highways for gene trafficking in place of narrow by-ways and occasional
footpaths that previously existed.
Some of us have
long considered horizontal gene transfer to be the most serious hidden
and underestimated hazard of genetic engineering, and have alerted regulators
accordingly, time and again, since GMOs were first released (see for example [3,
4] (Gene
Technology and Gene Ecology of Infectious Diseases, ISIS scientific
publication; Genetic
Engineering Dream or Nightmare, ISIS publication). The recent “emergency”
warning sent by a senior US Department of Agriculture scientist to US Secretary of Agriculture on a suspected pathogen “new to science” associated with GM
crops may prove to be a case in point [5] (Emergency!
Pathogen New to Science Found in Roundup Ready GM Crops? SiS 50).
Plant wounds hotspots for gene trafficking
The researchers at Bristol University showed that plant wounds, that could be created by insect bites, abrasion and other
mechanical damage, are hotspots for gene trafficking due to the wound hormones
produced by the plant. Under such circumstances, the soil bacterium Agrobacterium
tumefaciens, which causes crown gall disease in plants, could enlarge its
host range to infect fungi, and insert foreign genes into the fungi’s genome
[2]. This has large implications on the safety of GMOs already widely released
into the environment.
A. tumefaciens is probably unique among natural plant pathogens in carrying out
trans-Kingdom horizontal gene transfer during an infection, and it is this
ability that has been widely exploited for creating GM crops, grown on an
estimated 134 million hectares worldwide in 2009, and “jumped’ another 10
percent in 2010, according to industry-funded International Service for the
Acquisition of Agri-biotech Applications (ISAAA) [6].
Research
commissioned by the UK Department of the Environment, Food and Rural Affairs
(DEFRA) in the 1990s had already revealed that it is very difficult, if not
impossible to get rid of the Agrobacterium vector used in creating the
transgenic plant [7], and the bacterium is likely to remain dormant even after
the transgenic plants are transplanted into the soil. Hence, it is expected to
facilitate horizontal gene transfer, in the first instance, to wild-type Agrobacterium
in the soil, and further afield.
Disease-causing
strains of A. tumefaciens have an extrachromosomal Ti (tumour-inducing)
plasmid that enables the horizontal transfer of a segment of the Ti plasmid,
the T-DNA, into the plant cell genome when the bacterium’s virulence (disease
causing) system is activated by hormones produced by the wounded plant. This
feature is exploited in creating genetically modified organisms (GMOs), by
disarming the bacterium, and incorporating the virulence genes in a ‘binary’
vector that has to be used in conjunction with the disarmed Agrobacterium
strain.
In the 1990s, it was shown that
the range of organisms transformed by Agrobacterium could be extended if
the wound hormone acetosyringone was used to induce the virulence system.
The researchers at
Bristol University reasoned that as A. tumefaciens is a soil-dwelling
pathogen that often infects plants through wounds, it is conceivable that the
bacterium could encounter numerous species of microorganisms, including pathogenic
fungi that the same method to gain entry into the plant. The wound sites are
likely to be exuding wound hormones such as acetosyringone, so the bacteria are
primed for T-DNA transfer.
Experiments confirmed their suspicion in
full
They carried out their investigation using the
wilt-causing fungus Verticillium albo-atrum, a strong candidate for
encounters with Agrobacterium in the plant, as it has a similar wide
host range in plants, infecting both root and crown. Previous lab experiments
have shown that V. albo-atrum cannot be transformed by Agrobacterium in
the absence of acetosyringone. So, if it is presented with Agrobacterium
on plant tissue, and transformation does occur, it must be the plant that
supplies the wound hormone.
Peeled and sliced potato tubers
and carrots, leave- and stem-sections from tobacco plants were used as the
plant tissues for testing. After sterilization, they were inoculated with both A.
tumefaciens and V. albo-atrum and left at room temperature in a
covered agar dish for a minimum of 8 days and a maximum of 42 days.
Successful
transformants of V. albo-atrum were obtained from every kind of plant
tissue. 2 out of 17 potato slices, 1 out of 15 carrot slices; 14 out of 42
dishes each with 3-5 leaf pieces, and 10 out of 31 stem sections (without agar
plate, so as to be as close to the natural condition as possible). These
transformants were confirmed with molecular genetic analyses.
Implications on risk assessments of GMOs
still understated
The researchers concluded [2]: “This work
therefore raises interesting questions about whether the host range of A.
tumefaciens in nature is greater than just plants. It is possible that
evidence of such events could be looked for retrospectively in the increasing
number of genome sequences becoming available....
“In addition, the result may well
have implications for the risk assessment of GM plants generated via Agrobacterium-mediated
transformation, as Agrobacterium can survive within plant tissue through
transformation and tissue culture and can therefore be found within regenerated
transgenic plants...”
This is an understatement of a
serious risk that has been known almost since the first release of Agrobacterium-transformed
GMOs into the environment.
The risks are far greater than admitted
We have repeatedly drawn attention to the
possibility of facilitated horizontal gene transfer from GMOs created with Agrobacterium
vector, which is even stronger than originally envisaged due to other discoveries
made since then. I reproduce what we wrote in 2008 [8] (Horizontal Gene
Transfer from GMOs Does Happen, SiS 38), which repeats
an earlier account [9] (Living
with the Fluid Genome , ISIS publication) (see Box).
Agrobacterium vector a vehicle for
facilitated horizontal gene transfer [8, 9]
“We
have ..provided evidence strongly suggesting that the most common method of
creating transgenic plants may also serve as a ready route for horizontal gene
transfer [9, 10].
“Agrobacterium
tumefaciens,
the soil bacterium that causes crown gall disease, has been developed as a
major gene transfer vector for making transgenic plants. Foreign genes are
typically spliced into the T-DNA - part of a plasmid of A. tumefaciens
called Ti (tumour-inducing) – which ends up integrated into the genome of the
plant cell that subsequently develops into a tumour.
“But
further investigations revealed that the process whereby Agrobacterium
injects T-DNA into plant cells strongly resembles conjugation, the
mating process between bacterial cells.
Conjugation,
mediated by certain bacterial plasmids requires a sequence called the origin of
transfer (oriT) on the DNA that’s transferred. All the other functions
can be supplied from unlinked sources, referred to as ‘trans-acting functions’
(or tra). Thus, ‘disabled’ plasmids, with no trans-acting functions, can
nevertheless be transferred by ‘helper’ plasmids that carry genes coding for
the trans-acting functions. And that’s the basis of a complicated vector system
devised, involving Agrobacterium T-DNA, which has been used for creating
numerous transgenic plants.
“It
soon transpired that the left and right borders of the T-DNA are similar to oriT,
and can be replaced by it. Furthermore, the disarmed T-DNA, lacking the
trans-acting functions (virulence genes that contribute to disease), can
be helped by similar genes belonging to many other pathogenic bacteria. It
seems that the trans-kingdom gene transfer of Agrobacterium and the
conjugative systems of bacteria are both involved in transporting
macromolecules, not just DNA but also protein.
“That
means transgenic plants created by the T-DNA vector system have a ready route
for horizontal gene escape, via Agrobacterium, helped by the ordinary
conjugative mechanisms of many other bacteria that cause diseases, which are
present in the environment.
“In
fact, the possibility that Agrobacterium can serve as a vehicle for
horizontal gene escape was first raised in 1997 in a study sponsored by the UK
Government [7, 12], which found it extremely difficult to get rid of the Agrobacterium
in the vector system after transformation. Treatment with an armoury of
antibiotics and repeated subculture of the transgenic plants over 13 months
failed to get rid of the bacterium. Furthermore, 12.5 percent of the Agrobacterium
remaining still contained the binary vector (T-DNA and helper plasmid), and were
hence fully capable of transforming other plants.
“Agrobacterium not only transfers
genes into plant cells; there is possibility for retrotransfer of DNA from
the plant cell to Agrobacterium [13]. High rates of gene transfer
are associated with the plant root system and the germinating seed, where
conjugation is most likely [14]. There, Agrobacterium could multiply and
transfer transgenic DNA to other bacteria, as well as to the next crop to be
planted. These possibilities have yet to be investigated empirically.
“Finally,
Agrobacterium attaches to and genetically transforms several human cell
lines [15, 16] (Common
plant vector injects genes into human cells ISIS News 11/12). In stably
transformed HeLa cells (a human cell line derived originally from a cancer
patient), the integration of T-DNA occurred at the right border, exactly
as would happen when it is transferred into a plant cell genome. This suggests
that Agrobacterium transforms human cells by a mechanism similar to that
which it uses for transforming plants cells.
“The
possibility that Agrobacterium is a vehicle for horizontal transfer of
transgenic DNA remains unresolved to this day.”
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Agrobacterium transfers genes into human
cells
It is also worth reiterating our comment on
the scientific paper [15] documenting that Agrobacterium can transfer genes into human cells [16].
“The paper shows that
human cancer cells along with neurons and kidney cells were transformed with
the Agrobacterium T-DNA. Such observations should raise alarm for those
who use Agrobacterium in the laboratory.
“The
integrated T-DNA will almost certainly act as a mutagen as it integrates into
human chromosomes. Cancer can be triggered by activation of oncogenes (ie,
cancer genes) or inactivation of cancer-suppressing genes. Furthermore, the
sequences carried within the T-DNA in the transforming bacterium can be
expressed in the transformed cells (the viral promoter CaMV has been found to
be active in HeLa cells [17]) ….
“It is
clear that little has been done to prevent environmental escape of the
transforming bacteria or to quantify such releases. In conclusion, a study of
cancer incidence among those exposed to Agrobacterium tumefaciens in the
laboratory and in the field is needed. It would be worthwhile to screen workers
for T-DNA sequences.”
To conclude
The discovery by the Bristol University researchers barely scratches the surface of the hidden hazards of GMOs from
horizontal gene transfer. It is high time for a global ban to be imposed on
further environmental releases of GMOs, and all those responsible for releasing
them should be brought to book.
References
1.
“Hazards of GMOS: Agrobacterium mediated
transformation”http://www.bristol.ac.uk/news/2010/7279.html
2.
Knight CJ, Bailey AM, Foster GD. Investigating
Agrobacterium-mediated transformation of Verticillium albo-atrum on plant
surfaces. PLOS ONE 2010, 5(10): e13684. Doi:10.1371/journal.pone.0013684
3.
Ho MW. Gene technology and gene ecology of
infectious diseases. Microbial Ecology in Health and Disease 1998, 10, 33-59.
4.
Ho MW. Genetic Engineering Dream of Nightmare? The Brave New
World of Bad Science and Big Business, Third World Network, Gateway Books,
MacMillan, Continuum, Penang, Malaysia, Bath, UK, Dublin, Ireland, New York,
USA, 1998, 1999, 2007 (reprint with extended Introduction). http://www.i-sis.org.uk/genet.php
5.
Ho MW. Emergency! Pathogen new to science found in Roundup Ready
GM crops? Science in Society 50
(to appear).
6.
Global Status of Commercialized Biotech/GM Crops, 2009, ISAAA, http://www.isaaa.org/
7.
Mc Nicol MJ, Lyon GD, Chen MY, Barrett C and Cobb E. Scottish
Crop Research Institute. Contract No RG 0202.The Possibility of Agrobacterium
as a Vehicle for Gene Escape. MAFF. R&D and Surveillance
Report: 395.
8.
Ho MW and Cummins J. Horizontal gene transfer from GMOs does
happen. Science in Society
38, 22-24, 2008
9.
Ho MW. Living with the Fluid Genome, ISIS/TWN,
London/Penanag, 2003. http://www.i-sis.org.uk/fluidGenome.php
10.
Ferguson G and
Heinemann J. Recent history of trans-kingdom conjugation . In Horizontal
Gene Transfer 2nd ed., Syvanen M and Kado CI. (eds.) Academic
Press, San Diego, 2002.
11.
Ho
MW. Horizontal gene transfer, book review. Heredity 2003, 90, 6-7.
12. Barrett
C, Cobb E, MacNicol R and Lyon G. A risk assessment study of plant genetic
transformation using Agrobacterium and implication for analysis of
transgenic plants.Plant Cell Tissue and Organ Culture 1997,
19,135-144.
13. Kado
C. in Horizontal Gene Transfer 2nd ed., Syvanen M and Kado
CI. (eds.) Academic Press, San Diego, 2002.
14. Sengelov
G, Kristensen KJ, Sorensen AH, Kroer N, and Sorensen SJ. Effect of genomic
location on horizontal transfer of a recombinant gene cassette between Pseudomonas
strains in the rhizosphere and spermosphere of barley seedlings. Current
Microbiology 2001, 42, 160-7.
15. Kunik
T, Tzfira T, Kapulnik Y, Gafni Y, Dingwall C, and Citovsky V. Genetic
transformation of HeLa cells by Agrobacterium. PNAS USA, 2001, 98, 1871-87.
16. Cummins
J. “Common plant vector injects genes into human cells. ISIS News
2002, 11/12, p. 10.
17. Ho
MW, Ryan A and Cummins J. CaMV 35S
promoter fragmentation hotspot confirmed and it is active in animals. Microbial
Ecology in Health and Disease, 2000, 12, 189.
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There are 7 comments on this article so far. Add your comment
| Prof Keshava Nireshwalia Comment left 2nd March 2011 16:04:27
In the light of arguments, there is a strong case for banning GMOs unless a protective strategy against the horizontal transfers and the potential hazards are controlled. Thanks indeed for the enlightenment on the topic. | patrons99 Comment left 3rd March 2011 15:03:33
Great post, Dr Ho! Professor Nireshwalia makes an excellent point. "...there is a strong case for banning GMOs unless a protective strategy against the horizontal transfers and the potential hazards are controlled." Don't the vaccine schedules and global vaccine policy represent another route for GM gene escape? | patrons99 Comment left 3rd March 2011 15:03:41
Don't the vaccine schedules and global vaccine policy represent another route for GM gene escape? How safe is that?
“Vaccine Excipient & Media Summary”
“This section begins with a summary of the excipients included in licensed vaccines in the United States, as of the revision date at the bottom of the page. Excipients are inactive ingredients of a drug product necessary for production of a finished pharmaceutical formulation.”
http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/b/excipient-table-1.pdf
http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/b/excipient-table-2.pdf
This is FRAUD pure and simple. Neurotoxic metals, endocrine disruptors, phase transfer catalysts, ionophores, and non-human DNA are NOT inactive. It’s time that they were called-out on their lies! | mae-wan Ho Comment left 3rd March 2011 15:03:30
Patrons99, you are right about genetically modified vaccines, which we have written a lot about in ISIS. | Todd Millions Comment left 3rd March 2011 21:09:57
Dr-Mae-Wan Ho Thanx for this,exellent as usual.On the vaccine comments-
Given the contamination detection problems of conventional vaccines and serums,Could the brew vats themselves be churning out contaminates by this horizontal mechinism,and if so would they even be picked up by normal testing? | patrons99 Comment left 4th March 2011 14:02:44
How about forced mass vaccination with “franken-viruses”? The reality of vaccine "madness" keeps getting stranger by the day. There really is a lot that we can learn from the H1N1 Pandemic Flu Fraud and Hysteria of 2009. History could easily repeat itself, unless we educate ourselves. Dr A. True Ott, PhD, ND has looked into the subject in detail. At first, I was skeptical, but the more I read about these events, and the hemorrhagic pneumonic plague in the Ukraine, the less skeptical I became. I really do wonder what is more dangerous - the wild-type “germ”, the lab virus, or the jab?
http://atrueott.wordpress.com/
“Flu viruses have eight gene segments and one of the segments is called the PA gene. Interestingly, all eight dangerous hybrids carried the PA gene belonging to the H1N1 parent virus. The eight hybrid viruses caused severe pneumonia, edema and hemorrhaging in infected mice, the experts wrote.”
“Experts believe that a classic way for hybrid viruses to form is when different viruses meet and “marry” inside a single host, swapping genes. Humans and animals, such as pigs, can be efficient “mixing vessels.”
“Novavax will develop new technology to make vaccines using insect cells. VaxInnate will develop technology that combines influenza and bacteria proteins to stimulate strong immune response against the flu.”
| 7Towers Comment left 10th November 2012 14:02:06
I first learned about Agrobacterium tumefaciens while working for a perennial grower. I was amazed as well as alarmed that a bacteria could completely hijack DNA. Reading about how it accomplishes this, along with its easily engineered Ti Plasmid I was appalled at the manipulation and use with reckless abandon.
The extent of my education is high school grad and even I could ascertain the far reaching implications quite easily. Another Agrobacterium specifically radiobacter is able to disarm tumefaciens in the wild , but failed to replicate this ability in the unnatural environments of the lab.
Resistance is a big concern here along with what is very evident. The arrogance is unbelievable. |
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