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Free New Zealand in Food & Environment, 8th
November 2004
'GE Solution' Threatens More Than Just Possums
A project aimed at destroying possums is cause for serious concern
and could put other mammals in New Zealand at risk.
The experiments involve an antigen to the zona pellucida that has
been created and turned into a contraceptive spray that could save
New Zealand millions of dollars a year. But the experiment could
also impact the reproduction capacity of other mammal populations.
"These experiments could be much worse than just being a 'dead
end", says Claire Bleakley from GE Free NZ in food and environment.
â??The possum experiments could become a threat to other mammals
through horizontal gene transfer(HGT), just as possums have been
through transfer of TB."
On 28 January 2001 Genetically modified (GM) carrots and potatoes
were imported into NZ. These vegetables contain a transgene made
from a zona pellucida (ZP) antigen and a LT-B protein to enhance
the absorption of the antigen.
All mammal eggs have a ZP jelly specific and essential to each species,
this planned form of possum control- if allowed to become common
place- could threaten other species as a result of horizontal gene
transfer.
When sprayed into the eyes and nose the antigen crosses into the
blood stream and circulates around the body. As it is a foreign
protein an auto-immune response produces antibodies to ZP. These
antibodies then go on to attack the undeveloped egg in the follicles
of the ovary.
ZP could cause long term sterility to other female populations of
animals both marsupial, bird, bovine, ovine and human though Horizontal
Gene Transfer (HGT).
Research has found that human ZP (hZP) is 85% similar to possum
and pig ZP (pZP). Researcher, Koyama (1996) injected pZP into hamsters
causing permanent infertility followed by degenerative changes in
the ovaries. In monkeys there was also ovarian impairment with pre-cancerous
cells.
The zona pellucida (pZP3) is a jelly that every mammalian female
egg cell has enclosing it. It is a compound of three glycoproteins
that acts in a number of ways; It is an attractant to the sperm,
helping binding to the egg and once the egg is fertilised serves
as a repellent to other sperm. It also acts to protect the egg from
chromosomal damage and to promote fertility.
Could the possum experiments become a risk to other mammals through
HGT?
It is widely acknowledged that possums are major carriers of TB.
They transfer the toxin to the soil through their fecal waste and
dead bodies. Cows dogs and other animals can pick up the disease
if they contact the waste.
There is a possibility that possums could transfer the ZP antigen
through their faeces into the soil in this manner. Research studies
have found that, "Humans and mice fed on potato expressing
the sLT-B protein produced antibodies against LT-B in their serum
and gut secretions" (Mason et al. 1998; Tacket et al. 1998).
â?? ERMA must not allow these experiments into the field.
There are safer ways kill possums and create an industry from themâ?
says Ms Bleakley. "The risk to the New Zealand environment
and economy through poor science with no insight to the precautionary
principle could push our agriculture to the brink of a disaster".
ENDS
Claire Bleakley (06) 308 9842
References:
Skinner,SM,:Mills,T.:Kirchick, H.J; Dunbar, B.S.; (1984) Immunisation
with zona pellucida proteins results in abnormal ovarian follicular
differentiation and inhibition of gonadotrophin-induced steroid
secretion. Dept Cell Biol; Baylor Coll. Med., Houston, TX, USA.
Rankin Tracy; Talbot, Prue; Lee, Eric; Dean, Jurrien.(1999) Abnormal
zonae pellucidae in mice lacking ZP1 result in early embryonic loss.
Laboratory of Cellular and Development Biology, NIDDK, National
Institutes of Health, Bethesda, MD, USA.
Cai,L; Li, D; Sun, X; Wang, M. (2000). Mechanism of prmature ovarian
failure in murine autoimmune oophoritis immunised by porcine zona
pellucida.Institute of Obstetrics and Gynecology, Shanghai Medical
University, Shanghai, People Rebublic of China.
Abington Reproductive Medicine.(2000) Association of antizona pellucida
antibodies in human premature ovarian failure and infertility. www.abington-repromed.com
Koyama, K.,Hasegawa, A.,& Isojima, S.(1994) Porcine zona pellucida
antigen 4(ZP-4) as a candidate for vaccine. Department of Obstetrics
and Gynecology, Hyogo Medical College, Hyogo, Japan.Eds.
Talwar, G.P.; Rao, Kanury V.S.; Chauhan V.S. Recomb. Synth. Vaccines.
Application Executive Summary: GMC00020
Landcare Research propose to research the biological control of
the possum by evaluating the immunogenicity and effects on fertility
of transgenic plant material expressing foreign proteins by;
· feeding possums with transgenic carrots expressing either
(i) sLT-B or (ii) possum zona pellucida protein 3 (ZP3).
· feeding possums with transgenic potatoes expressing a 27
amino acid peptide from possum zona pellucida protein 3, joined
to sLT-B by an 7 amino acid linker at the N terminal end (ZP3 pep-LT-B).
· measuring serum and mucosal immune responses of possums
to ZP3, ZP3-peptide, and LT-B.
for promising constructs, measuring the effects of immunisation
on the fertility of possums by superovulation and artificial insemination,
and/or natural outdoor breeding trials.
Spray doom to possums NZ HERALD 21.10.2004 By SIMON COLLINS.
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