Genetically Manipulated Food News

10 July 1997

Table of Contents

Human blood plasma from GM animals
New GM Tomato
Insect Resistant BT Cotton

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Scientists close to making human blood from animals

Scottish firm helped clone sheep

July 6, 1997 Web posted at: 4:16 pm EDT (2016 GMT)

LONDON (AP) -- Scientists who helped engineer the first cloned sheep are close to generating human blood plasma from animals, a newspaper reported Sunday.

PPL Therapeutics, the Scottish firm that helped Edinburgh's Roslin Institute clone a sheep, is developing the means to replace the plasma genes of sheep and cows with the human equivalent, according to The Observer, a respected weekly paper.

The animals' milk will then contain the key elements of human blood plasma, including albumen, clotting factors and antibodies, the newspaper reported.

PPL told the paper it plans to rear herds of the animals and manufacture plasma from the proteins extracted from their milk.

PPL hopes the process will be ready "in months," The Observer quoted Dr. Ron James, the firm's managing director, as saying.

Only 5 percent of Britain's population regularly gives blood. Genetically modified animals could produce 10,000 times more plasma a year than a human donor.

James told the newspaper that the results would be of "great medical benefit to man."

Britain's National Blood Service was more cautious.

"Using animal-grown human plasma is fine in theory," said a spokeswoman, who was not further identified by The Observer, "but until the clinical trials are complete you can never be sure that you have the full plasma equivalent, or whether the animals will pass on diseases to man."

The announcement by scientists at the Roslin Institute in February that they had created a cloned sheep using cells from another sheep's udder triggered an ethical storm and led several governments -- including the Clinton administration -- to introduce legislation that would limit the uses of cloning.


Subject: GM tomatoes, and wishful thinking

Here is an interesting article.

Our position is that these genetically engineered foods should receive long-term testing before they are put on the market.

The current situation is that due to pressure from the biotech industry, who would like to quickly make money off their products, genetically engineered foods are fast tracked to the market without extensive testing for their long term effects on consumers.


Reuters Tuesday July 8 7:42 PM EDT

Genetically Altered Tomato Could Combat Cancer

By Maggie Fox

LONDON (Reuter) - European scientists said Tuesday they had bred a vitamin-rich tomato they hope can eventually help prevent heart disease and cancer.

They also hoped the genetically engineered tomato would be more acceptable to Europeans frightened by the idea of transgenic food.

The tomato has increased levels of carotenoids, nutrients important to health. It has about four times the normal levels of beta-carotene, which the body uses to make vitamin A, and twice the levels of lycopene, the compound that helps make tomatoes red and a close cousin of beta-carotene.

"The reason for that is there are a number of reports that lycopene reduces the risks of some cancers," said Peter Bramley, a professor of biochemistry at the Royal Holloway Hospital in Egham near London.

"Therefore, the idea is if we can increase the amount of lycopene in the diet through tomatoes this can reduce the incidence of these cancers," Bramley, who coordinated the European Union-funded study, told Reuters.

Bramley's team report their results to the European Commission this week. They are among 130 European laboratories funded by a 50 million Ecu ($56 million) project known as the Project of Technological Priority (PTP).

Bramley's group used the same technology used is to breed Calgene Inc's Flavr Savr tomato -- using a bacteria to deliver a new gene into the plant.

"What we have done is to take the gene that encodes the enzyme to produce lycopene and we have introduced that into the tomato so it only works in the ripening fruit," he said.

Other teams in Spain and Germany are working with peppers, Bramley said.

Bramley said he had eaten his transgenic tomatoes. "They don't taste any different," he said. "They are quite normal. They may look a little redder or a little more orange." But he said he was acutely aware of the fears people had about genetically engineered food.

Street demonstrations broke out in several European cities earlier this year over news that Monsanto's Round up Ready soybean, genetically engineered to resist herbicides, would be imported without labelling.

But Bramley noted that the genes inserted into the tomatoes and peppers were genes for substances already eaten by people, so the safety implications were different.

He said work was being done in other labs to create rice rich in beta-carotene and lycopene for growing in countries where naturally vitamin-rich vegetables are scarce.

Beta-carotene and lycopene are anti-oxidants -- they counteract the effects of molecules known as free radicals which can damage cells, leading to cancer, heart disease and other harmful effects.


A commentary on PNAS paper concerning Bt Cotton Adaptation by Insects from

July 1997 ISB NewsReport ( http://www.nbiap.vt.edu )

Boom and Bust of Insect Resistant BT Cotton

The development of insect resistant crop varieties has been the most successful application of agricultural biotechnology research so far. The Bt transgenic crops derive their resistance from the insecticidal gene of the bacterium Bacillus thuringiensis. Cotton, corn, and potato engineered with such genes were grown commercially for the first time in 1996. Transgenic Bt cotton was grown on 1.8 million acres last year, accounting for about 12% of US cotton acreage.

A major worry lurking behind this success is the potential vulnerability of Bt crops to eventual adaptation by insect pests. Large scale deployment of Bt transgenics will certainly impose a selection pressure for pre-existing Bt-resistant insects to increase their numbers. As a result, the effectiveness of this environmentally sound method of pest control would be reduced. Although several resistance management strategies have been proposed to slow the evolution of insect adaptation to Bt genes, they are not based on empirical data, such as the initial frequency of resistance alleles in the population, but rely instead on theoretical estimates that may prove inadequate.

According to Bruce Tabashnik, University of Arizona, excitement over the success of Bt plants "must be tempered with an admission of ignorance" on how to effectively manage pest resistance to ensure long term durability of the approach. Thus a study conducted by a team led by Fred Gould of North Carolina State University may be a turning point in Bt research because it provides the first direct estimate of the field frequency of Bt-resistant insects (1). They report that in tobacco budworms (Heliothis virescens), a major cotton pest, 1 in 350 individuals carried an allele for resistance to the Bt toxin. This estimate is considerably higher than those assumed in earlier theoretical models, and thus forebodes a swift evolution of resistant insect populations. Tabashnik calls this study "a timely finding" which "provides inspiration to plunge ahead" into larger field tests of resistance management tactics (2).

The study was a mammoth effort that began with collecting 2,000 male insects from four cotton-growing states in 1993, before transgenic Bt crops were grown commercially. As the resistance trait is recessive, it is difficult to detect heterozygous insects but estimates of the number of such heterozygotes carrying recessive alleles are critical as those individuals are predominant in any population. The collected males were then individually crossed with females of a strain selected for its extreme high resistance to CryIA(c), the Bt gene used in cotton against tobacco budworm.

The resulting first and second generation progeny from 1025 successful crosses were tested for resistance to Bt toxin using artificial diets in the laboratory. Three males from the sample of 1025 were confirmed to be carrying an allele for resistance to Bt toxin, leading Gould and co-workers to conclude that field frequency of Bt resistance alleles was about 3 in 2,000. William Moar of Auburn University comments, "Gould's research definitely illustrates that resistance management procedures such as refuges, intense field monitoring of transgenic plants for potential escapes, and alternate control strategies are essential to maintain the viability of this valuable resource."

To slow the adaptation of insects to Bt cotton, the EPA has mandated that cotton growers should plant at least 4% of their crop with non-transgenic cotton and this refuge cannot be treated with any insecticides. The idea is that such 'refuges from toxin' will harbor susceptible insects and thus retard the evolution of insect resistance against the Bt gene. Gould et al. predict that with 4% refuge, the Bt cotton could remain efficacious to tobacco budworm for 10 years. This is not bad considering that insects have developed resistance to many pesticides and conventional varieties in less time than that. However, the current Bt cotton has less resistance to other pests such as cotton bollworm and European corn borer, and thus the authors predict a boom cycle of only 3-4 years for this variety. Again Tabashnik puts it elegantly -"Nothing will be gained and much can be lost if we pretend to know more about resistance management than we really do".

References

  1. Gould, F. et al. 1997. Proc. Natl. Acad. Sci., USA 94:3519-3523

  2. Tabashnik, B.E. 1997. Proc.Natl. Acad. Sci., USA 94:3488-3490.

(You can view or download the full text of papers published in PNAS at http://www.pnas.org )

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