Part two of Three.
Content-Type: text/plain; charset="us-ascii"
Date: Tue, 3 Nov 1998 00:06:04 +0100
From: Richard Wolfson <firstname.lastname@example.org>
> ======#====== New Scientist October 31, 1998
SECTION: Features: Living in a GM world,
HEADLINE: Strange Fruit
BYLINE: Phil Cohen
HIGHLIGHT: The food industry has everything to gain FROM coming clean ABOUT
products with bolted-on DNA BODY: CONSIDER the cautionary tale of the
celery. In the mid-1980s, celery growers in the US introduced what they
thought was a wonderful new strain. Highly resistant to insects, it
promised to boost yields dramatically. There was just one small problem.
People who handled the celery sticks began complaining of severe skin
Dermatologists discovered that the celery was shedding psoralens, natural
chemicals which become irritants and mutagens when exposed to sunlight.
Or take the once notorious American Lenape - or rather, don't. All seemed
well with this hardy new variety of potato launched in the US and Canada in
the 1960s. Then came the bitter truth. Biochemists discovered the source of
the tuber's unusual burning flavour: dangerous levels of toxins called
"Many nightmares predicted for genetically engineered crops have already
happened," reflects Tony Conner of the New Zealand Institute for Crop and
Food Research near Christchurch.
It's just that "not many people noticed or cared" because they were the
fruits of conventional breeding, not genetic manipulation.
In fact, many biotech insiders and government food regulators, especially
in the US, believe that the public has got it all wrong. By the time a
"gene food" reaches people's plates it is not merely as safe as a
conventional food -in some respects it is actually safer, because of the
intensive testing that regulators demand for high-tech food crops. By the
end of this year millions of Americans will have eaten these foods, says
Arnold Foudin of the US Department of Agriculture in Beltsville, Maryland.
"And yet you won't be seeing anyone dying in the street."
Frankenfoods However, you won't be seeing opponents of gene foods downing
their placards, either. In Europe especially, campaigners have been working
flat out in recent months to prevent genetically engineered crops being
grown on the same scale as in North America. Their tactic has been to play
the moral/emotional card for all it's worth and brand all genetically
engineered crops "Frankenfoods" regardless of the specifics of each genetic
modification. So far, it has worked amazingly well. All hell broke loose in
Britain in August when a food scientist appeared on TV claiming - wrongly
as it turned out - that a potato he'd engineered was toxic to rats.
Inevitably, the questions that really matter have vanished amid the
confusion and theatre. How do specific genes and the proteins they encode
behave in the body ? Do the types of genes and proteins being introduced
into high-tech crops raise any new threats to food safety that could go
undetected by researchers in companies or government labs ? The answers
reveal that the biotech industry is on solid ground when it claims its
products are no riskier than conventional foods. But it strays into some
distinctly swampy territory when it claims, as it continues to with some
force in the US, that genetically engineered foods need not be routinely
labelled. First, there is the issue of food safety. In traditional
breeding, scientists often introduce unknown genes into a plant species en
masse by hybridising them with a related species with a desirable trait.
Genetic engineering, by contrast, involves splicing no more than a few well
characterised genes into a plant. That seems less drastic but can still
produce unforeseen effects. In either case, the influx of new DNA might end
up in critical parts of the genome, altering the behaviour of the plant's
normal complement of genes, slashing the production of nutrients or pumping
up the level of natural toxins. In many species, plant biochemistry is not
just complex and sensitive, it's actually geared up for producing toxins to
ward off predators - hence the bitter Lenape and toxic celery.
"That's why it's standard to thoroughly analyse these new transgenic
plants," says Roy Fuchs of Monsanto in St Louis, Missouri. "We need to see
that they are substantially equivalent to commercial plants." To that end,
Fuchs and his team run each promising transgenic crop through a battery of
biochemical checks. They monitor levels of nutrients, proteins and
potential poisons, and, in some cases, feed the crop to livestock to check
that the animals gain weight at the normal rate and remain generally
But what about more insidious effects ? Some people worry that genetic
engineering brings new DNA into the food supply, from microbes, for
example. Couldn't this new DNA end up invading our genomes or the genomes
of our gut bacteria ? Few scientists take this threat seriously. Not even
Walter Doerfler, a researcher at the University of Cologne in Germany,
whose work has been seized on by opponents of gene foods.
Last year, Doerfler's team found that when DNA from a bacterial virus was
eaten by a mouse, some snippets of viral genes invaded the animal's
bloodstream and cells - and, on rare occasions, even linked itself to mouse
DNA ("New Scientist", 4 January 1997, p 14; "Proceedings of the National
Academy of Sciences"94 p 961)). "This generated a lot of hysteria in the
genetically engineered food arena," remembers Doerfler. But he believes
that mammals have defences against this genetic onslaught. In his
experiments, the vast majority of the viral chromosomes were shattered into
pieces too small to contain intact genes. And despite scouring tissues
throughout the mouse, Doerfler has never found any evidence of active
ingested genes - even ones designed to work in human cells.
Shredded genes Nor are microbes in the human gut likely to pick up genes
from food. Most DNA from food will be destroyed well before it reaches the
bacteria, with any surviving remnants being shredded again inside the
bacteria by so-called restriction enzymes. Even if intact genes were to
successfully invade a bacterium or human cell, they're unlikely to spring
into action because their activity will be controlled by DNA switches
designed to work only in plants. The one exception may turn out to be the
antibiotic resistance genes that biotechnologists routinely use as
"markers" for handling DNA in bacteria and identifying its presence in
plant cells. Despite all the scare stories about these marker genes, those
in crops now approved for commercial growth have been genetically
scrambled, so there is little chance for their resurrection, or they are of
no clinical importance. So it's unlikely that these particular genes could
boost the spread of antibiotic resistance in human pathogens.
Even so, critics worry that there is nothing to prevent scientists from
using different markers in future, and while scientists agree that the
chance of one of these genes jumping from food into a new cell is tiny, few
will say it is impossible. Technology could soon make it impossible,
however. Some years ago, David Ow and his colleagues at the Plant Gene
Expression Center in Albany, California - a lab belonging to the US
Department of Agriculture - discovered a way of removing marker genes and
other extraneous DNA from engineered plant cells. Their approach involved
using a pair of molecular scissors called CRE, an enzyme from a bacterial
virus, to snip out the antibiotic resistance DNA. Since then, Ow's group
has shown the same editing trick also works in an important food crop,
Until now, industry researchers have shown little interest in the work
because they insisted that their genes posed no threat. But attitudes seem
to be changing. "There is no clinical concern here whatsoever," says Jeff
Stein of Novartis in Greensboro, North Carolina. "But we do worry about
public perception." While not disclosing too many technical details, Stein
says that all future Novartis crop products will be "100 per cent" free of
antibiotic resistance genes. Other companies are also investigating ways of
cutting out antibiotic resistance genes and surplus DNA.
More recently, Ow's team showed that the editing process can run in
reverse, enabling researchers to insert foreign genes into plant
chromosomes at exact locations ("Plant Journal," vol 7, p 649) - something
that has so far been impossible. The method involves the insertion of DNA
"docking sites" into unimportant areas of a chromosome. In future,
researchers will be able to use such sites to slot new genes into plants
without disturbing their normal complement of genes. Genetic engineering
will finally become the precision tool that the biotech industry claims it
Not that this would deal with every worry. In some cases, the transgenic
protein encoded by this precision-engineered DNA might itself turn out to
be toxic, although detecting this wouldn't be a problem. Unlike
conventional breeders, biotechnologists can use the genes that interest
them to produce transgenic proteins in bacteria to test on animals.
A more subtle effect of proteins is harder to deal with.
When molecular biologists shuttle new genes into plants, they might
inadvertently introduce proteins capable of triggering respiratory or
inflammatory problems in the one to two per cent of people who suffer from
food allergies. Scientists at Iowa- based Pioneer Hi-bred, one of the
world's largest seed companies, learnt this the hard way. In the early
1990s, its researchers engineered a more nutritious strain of soya bean by
adding a gene taken from brazil nuts. The gene encoded a protein rich in
methionine, a nutrient that is in short supply in ordinary soya beans. At
the company's request, allergy specialist Steve Taylor of the University of
Nebraska in Lincoln studied antibodies and immune responses from patients
allergic to brazil nuts. Pioneer Hi-bred dropped the soya bean project when
Taylor discovered that the hybrid was likely to trigger a major attack in
people with brazil nut allergies.
To some, it seemed like a narrowly averted disaster. After all, research
based on animal experiments published only a few years earlier suggested
that the same protein was not an allergen. "Allergy science is in its
infancy," says Jane Rissler, a plant pathologist with the Union of
Concerned Scientists in Washington DC. "That's a good reason to collect a
lot more data before doing these widespread transgenic releases." Taylor
himself extracts a different lesson. "It shows you can't be cavalier about
allergies," he says. "But it also shows the system is working."
The system he refers to is a series of tests that scientists now use to
flush out allergens before they are put into crops.
If the transgenic protein comes from a known allergenic food, it is
subjected to immunological tests. If the protein comes from other sources,
researchers study its molecular structure (amino acid sequence), looking
for similarities with allergy-triggering proteins in the databases. The
protein's chemical hardiness is also scrutinised. In test-tube simulations
of the heat, acid and enzymes found in the stomach, most proteins are torn
to shreds in seconds. Allergens tend to survive several minutes before
they, too, are destroyed.
Mystery ingredients Even if true allergens do escape detection and make it
into transgenic crops, immunologist Yueh-hsui Chien of Stanford University
questions whether this represents a new risk to the consumer. "If you
regularly eat tomatoes, and then you eat a transgenic one, you know you are
eating a few new proteins," she says. "The first time you eat a lobster,
you eat several thousand new proteins."
But that's a false comparison, argues Rebecca Goldburg, senior scientist at
the Environmental Defense Fund, an advocacy group in New York. She points
out that someone knows they are eating a lobster. But the new ingredient in
the tomato is invisible because transgenic crops are, for the most part,
unlabelled and mixed in with the rest of the harvest. "The industry is
depriving us of one of our most important natural defence mechanisms," she
says. "Reading ingredients."
In the US, companies argue that the chance of allergic responses to the
current generation of modified crops is too remote to warrant segregation
and labelling. And so far, the US Food and Drug Administration has
supported this view by introducing rules that require farmers and
manufacturers to segregate and label transgenic foods only if there is good
reason to suspect they might behave differently in the body than more
conventional foods. Officials in Europe made a similar ruling in September,
but in Britain and many other countries in the European Union, some
manufacturers and retailers have decided to label products voluntarily.
Full disclosure may soon be a major fashion. In the industry, the most
excited talk is about using molecular biology to lower undesirable
chemicals or boost nutrients in food. At Nagoya University in Japan, for
example, researchers have managed to slash levels of the major allergenic
protein in rice by 70 to 80 per cent by inserting a so-called antisense
gene to block the protein's production in the plant.
If biotechnology dramatically increases the quality or safety of food,
companies on both sides of the Atlantic may soon be falling over each other
to market new and improved gene crops - and to provide the public with more
information about what they are eating.
Then we can decide for ourselves which of the risks - low tech or high tech
- we are willing to take when we eat our next meal.
For more science news see
> ======#====== New Scientist October 31, 1998
Living in a GM world, live and let Live
BYLINE: Martin Brookes and Andy Coghlan HIGHLIGHT: Engineered crops will be
the best thing that's happened to wildlife for years, say their advocates.
Others fear it could all go horribly wrong BODY: BIG science plus
agriculture spells bad news for wildlife. This has been the mantra of
environmentalists ever since Rachel Carson documented the impact of
chemical pesticides on American wildlife in her 1960s classic, "Silent
Spring". And that is the mantra that Dan Verakis, spokesman for biotech
giant Monsanto and defender-in-chief of genetically engineered crops, is
keen to turn on its head. "People are saying this technology is the last
nail in the coffin of our wildlife," he says. "But we believe it could help
wildlife recover." Genetic engineering could slash the volume of herbicides
and pesticides that farmers need to dump on the land each year; it could
"reverse the Silent Spring scenario".
Advocates of the new high-tech crops clearly see this as their strong card,
the one that can simultaneously wrong-foot anti- biotech greens and all
those who are sceptical simply because they can see no benefits in the
technology for anyone other than farmers and shareholders. There's just one
small problem. Biotech's biggest money-spinners to date are crops that seem
designed to keep farmers hooked on chemicals.
Of the 27.8 million hectares of land planted with genetically engineered
crops this year in the US, 71 per cent is covered with plants resistant to
herbicides, largely soya bean and maize engineered to carry an enzyme that
neutralises glyphosate, Monsanto's famous Roundup herbicide. Thanks to this
enzyme, the biotech industry gets to sell transgenic seed and a chemical,
and farmers can wage war on weeds like never before.
In theory, they can spray as much as they want whenever they want and not
endanger their crop. Of course, the industry claims these crops are greener
than they seem. Farmers planting soya beans resistant to glyphosate have
only to apply the herbicide once or twice instead of six or seven times,
says Val Giddings of the Biotechnology Industry Organisation. "The notion
held in Europe that farmers want to spray herbicides willy-nilly is
nonsense because they want to cut costs."
And so they do, but the total volume of chemicals alone doesn't tell the
whole story, especially not with herbicide- resistant crops. Whether these
are a good thing for wildlife depends not just on how much herbicide
farmers spray, but when and where they spray it, and, above all, what their
attitude is to weeds. The fact that many take an aesthetic pride in running
a farm with "clean fields" means that reversing the Silent Spring scenario
might be easier said than done.
But first the good news. Even staunch critics of the speed with which
biotechnology is revolutionising the world's agriculture acknowledge that
transgenic crops engineered to be resistant to specific fungi and insects
could make many old- style chemical sprays redundant. In Arkansas alone
last year, farmers planted 1 million acres with engineered cotton resistant
to the cotton bollworm, and hardly any of the usual organophosphate
pesticides were applied. "It amounts to a saving in pesticide application
of 1 litre per acre, enough to fill about 14 large railroad tank cars,"
"People in the US are more pleased than Europeans when you tell them you
don't need chemicals to control insects and nematodes," says Roger Beachy,
a plant biologist at the Scripps Institute in La Jolla. "The public in
Europe don't seem to be aware of the benefits to the environment, and
therefore to them personally," he says.
How long those benefits will last is not so clear. Introduce a new method
of pest or weed control and "you always get a temporary dip in the cost to
the farmer", says Margaret Mellon, director of agriculture and
biotechnology for the Union of Concerned Scientists, a pressure group in
Washington DC. "In the past, those dips have never persisted because
resistance has emerged." Sure enough, biotech companies already have to
take seriously the problem of pests acquiring resistance to Bt toxin (see
"Resistance is useless"). Others, meanwhile, fear that inserting certain
pesticide genes into plants could jeopardise the balance between pests and
beneficial insects in agricultural ecosystems.
Friendly fire The aim of such manipulations is to provide the crops with a
toxin that can ward off or kill specific pests such as bollworms and
aphids, while sparing friendlier insects such as ladybirds.
But this year a British team found that a potato engineered to resist an
aphid pest also harmed ladybirds, at least in lab conditions.
Nick Birch of the Scottish Crop Research Institute in Dundee and his
colleagues inserted a gene from the snowdrop into potatoes, enabling the
tubers to make a lectin capable of stopping aphids from snacking on them
quite so much. When aphids reared on these potatoes were fed to ladybirds,
however, the females lived only half as long and produced more than twice
the number of unhatched eggs compared with ladybirds fed normal aphids.
Still, most ecologists see this as an argument for testing each pesticide
gene fully before using it, not for banning them en masse. There are some
pesticide genes that shouldn't be inserted into crops until their wider
biological effects have been determined, says Brian Johnson, an ecologist
with the conservation group English Nature who advises the British
government about the release of transgenic organisms. But overall, the
environmental benefits of pest-resistant crops could be immense, he says.
Herbicide-resistant crops, however, are another matter. English Nature is
urging the British government to impose a moratorium on their use until
their effects on biodiversity have been explored. Johnson accepts that the
crops are not all bad. In the US, for instance, they have led many farmers
to switch to Roundup from atrazine, a herbicide chemical that is far more
likely to leach into water systems and harm animals and humans.
One of Roundup's virtues is that it binds to soil as it breaks down.
Another is that it can reduce the need for ploughing, which may contribute
It is also a very effective herbicide. Perhaps too effective. English
Nature fears that armed with Roundup and transgenic crops, farmers will end
up wiping out more wild plants than ever before. They may spray less,
Johnson says, but because chemicals like Roundup kill a broader spectrum of
weeds than many other herbicides, their impact would be greater. The result
could be weed wipeout. In the US, that might not matter so much because
less of the nation's biodiversity is locked up in farmland. But, as Johnson
says, "Europe doesn't have the luxury of vast wilderness areas like the
US". Much more of its wildlife depends on agricultural practices for its
In Britain, says Johnson, farmers often permit a modest growth of weeds in
and around their fields. These weeds support a variety of insects which
provide a lifeline for threatened birds such as linnets and skylarks. In
fact, research is just beginning to reveal in detail which plants do and do
not harm the yields of different crops, promising a new era of laissez-
faire crop management. What will happen to all this if British farmers
switch to engineered crops and broad-spectrum herbicides ?
Not a great deal, according to Alan Dewar at the Institute for Arable Crops
Research at Broom's Barn in Suffolk. Dewar says that with conventional
herbicides most farmers cleanse their land of weeds anyway. In fact, to
avoid damaging their non- resistant crops, most farmers spray their land
before the growing season even begins. At least with the transgenic crops,
farmers have the option of letting the weeds grow with the crop for part of
the season. In experiments carried out this summer for Monsanto, Dewar and
his colleague Mike May found that yields of transgenic sugar beet treated
with Roundup remained higher than with conventional herbicides even when
Roundup was applied late, letting the weeds survive for much longer than
usual in the growing season.
"It was obvious to see that the weedy plots were heaving with life," says
Dewar. Aphids that normally attacked the beet, for example, colonised the
weeds instead. Conservation-minded farmers could use Roundup to allow weeds
to grow a bit longer, says Dewar. "But it requires a bit of nerve because
it looks a bit of a mess."
The major disincentive for letting the weeds grow, however, is that the
best yields were in plots sprayed early enough for Roundup to destroy
everything. In other words, herbicide- resistant crops could be used in an
environmentally friendly way - but only by farmers who are not driven by a
"clean field" mentality and who don't mind dropping their yields below the
maximum achievable. These are not the farmers Monsanto seems to have in
mind in its brochure for Roundup-ready oilseed rape.
One Manitoba farmer endorses the product thus: "The weed control has been
exceptional. It (Roundup) annihilated everything."
Whether the same would happen in Britain and other countries is hard to
say, but one thing at least is clear. The biotech industry is developing
two very different sales pitches for its products - one for farmers and one
for the rest of us.
Resistance is useless By Bob Holmes IT SOUNDS like a farmer's dream: crops
that produce a steady supply of their own insecticide so there's no need to
drench fields periodically with toxic chemicals to kill off the pests.
In the US the dream has been a reality for three years now, as farmers
enthusiastically plant crops genetically engineered to produce Bt, an
insecticidal protein originally found in a soil bacterium, "Bacillus
This year Bt cotton engineered by Monsanto accounted for over 20 per cent
of all the cotton planted in the US, while Bt maize developed by several
companies grew in over 10 per cent of America's cornfields. A third crop,
Monsanto's Bt potato, has also begun to hit fields. In total, the US's Bt
crops cover an area almost as big as Scotland.
Critics fear that in their rush to take advantage of the new technology,
however, farmers and the companies that supply them may be killing the
goose that lays the golden eggs. Insects have a long history of evolving
resistance to chemical insecticides.
But scientists worry that Bt crops may provoke resistance even more quickly.
Sprayed insecticides usually degrade rapidly, and if relatively few pests
show up in a given year, money-conscious farmers may not spray at all. Bt
plants, on the other hand, are equivalent to a continuous deluge of
insecticide that keeps the pests under constant pressure to evolve
resistance. As Bt crops move into Europe and huge new markets such as China
and India in the next few years, the threat of Bt-resistant superbugs seems
likely to grow. And that matters because many see Bt as the last line of
defence against insect pests.
The best response to such a threat, scientists agree, is to stack the cards
against resistance by making sure that enough insects survive that are
still susceptible to the toxin. Farmers can do that by planting some of
each crop without the "Bt" gene, so that insects can mature without any
evolutionary pressure to become resistant. If there are enough insects in
this refuge, any resistant ones that evolve in the Bt field will mate with
susceptible pests. And if the "Bt"-containing plants deliver a toxic dose
hefty enough to kill insects with just one resistant parent, this so-called
"high dose/refuge" strategy should keep resistance at bay for many years.
But that "if" may be a big one. So far none of the three commercial Bt
crops has been grown long enough for resistant insects to show up in
farmers' fields in the US. Researchers are already seeing ominous hints,
however, that for a few pests, Bt plants aren't delivering the knockout
punch. In some Bt corn varieties, for example, toxin levels drop towards
the end of the growing season, which allows some larvae of the European
corn borer to survive even without resistance genes.
Even when the toxic dose is high enough, refuges work only if susceptible
insects survive on them, and farmers aren't used to encouraging pests. As a
result, agricultural companies - and government regulators - tend to
recommend refuges that are barely big enough to do the job.
If enough susceptible insects manage to survive in the refuge, they will do
little good unless they mate with resistant survivors from the Bt fields.
And here, too, some troubling signs are beginning to emerge. At the
University of Minnesota, Donald Alstad and his colleague David Andow have
found that European corn borer adults rarely fly more than 75 metres during
their lifetime. That means the refuges must be tucked in very close to the
Bt corn, which they seldom are. Entomologists know less about the flight
ranges of other pests, but it's clear that some refuge placements are
The US Environmental Protection Agency may correct some of these problems
when it reconsiders its regulations for Bt plants over the next three
years, says Janet Andersen, who directs the agency's biopesticides
division. But even if the US plugs the largest loopholes, there's no
guarantee that other countries will do the same. In Europe, where Bt crops
are starting to get approval for commercial planting, regulators are still
wrestling with the question of how big the refuges would need to be for
European pests and cropping patterns. In poorer countries, where farms are
small and farmers uneducated, any regulation may be hard to achieve.
For more science news see
--Dan in Sunny Puerto Rico--
To Unsubscribe: Email email@example.com with "unsubscribe sanet-mg".
To Subscribe to Digest: Email firstname.lastname@example.org with the command