VOICES OF THE SOUTH AND NORTH
Alexandria Conference on Biotechnology and Sustainable Development
Jennifer A. Thomson

This meeting took place in the conference center that is part of the new Library of Alexandria, Egypt, the old one having burnt down in the time of Julius Caesar. It is a magnificent complex and when completed will be spectacular, with marvelous views over the harbor towards the site of the old lighthouse.

Ismael Serageldin, former chair of the Consultative Group on International Agricultural Research (CGIAR) and Vice President of the World Bank, presided over the meeting. This was most fitting as his present appointment is Director General of the Library of Alexandria. He also set the scene for the conference in his opening address, which was an extremely wide-ranging, wonderfully illustrated overview of the need for sustainable development and the potential role of biotechnology.

Serageldin's opening was followed by Gordon Conway, President of the Rockefeller Foundation, who likened globalization to the two faces of the Greek god, Janus. The dark face represented the poor getting poorer and the rich, richer, while the light face represented everyone winning. Similarly, biotechnology has a light and a dark side. On the light side he gave an example of the effect that Bt cotton is having on the lives of resource-poor farmers in South Africa where yields increased from 261 to 417 kg/ha during 1999 and 2000. On the dark side is the fact that from 1975 to 1997 only 11 out of 1233 pharmaceuticals were developed for tropical diseases and, of these, six were for veterinary diseases. He emphasized the need for private/public partnerships to bring the benefits of biotechnology to the South, including the need to unlock intellectual property for agricultural benefits. He also highlighted the need for more of our best scientists to work in well-equipped laboratories and field facilities in developing countries in order to interact with, learn from, and address the needs of poor people.

Another speaker in the opening session was Dr. Magdy Madkour, Director of the Agriculture Genetic Engineering Research Institute in Cairo (AGERI). He presented an impressive overview of the research being carried out in his Institute in EPA-approved facilities, explained the biosafety regulations and guidelines governing biotechnology in Egypt, and stated that the country had approved 57 applications including contained tests and field trials of genetically modified crops. Indeed, some of the most impressive posters presented at the meeting came from the AGERI.

Marc van Montagu, Director of the Flanders Interuniversity Institute for Biotechnology Department of Plant Genetics, gave an extensive overview of the state of the art in plant biotechnology. He highlighted the wealth of data generated by genomics and the challenging opportunities opened up by proteomics and metabolomics. Expressed sequence tags (ESTs) are known from approximately 120 plant species, which could lead the way toward "chemical genetics" in which selective inhibitors can be used to change a phenotype before the plant can adapt. He emphasized the importance of improving science education worldwide and explaining to society the importance of science in decision-making.

In another talk, Ismael Serageldin compared high and low income countries where the differences in income could be as much as 42-fold but the difference in research expenditure could exceed 200-fold. He talked about the values of science, including truth, honor, creativity, and imagination, constructive subversiveness (throwing down and destroying existing paradigms if necessary), tolerance of engagement (of unfamiliarity of ideas, often raised by young people), and arbitration of disputes by institutions. He also raised the thorny issue of patents and pointed out that if these were to be stopped approximately 2/3 to 4/5 of the input to the total knowledge base could be lost.

There was a very interesting panel discussion that included Pat Mooney, Executive Director of the Rural Advancement Foundation International (RAFI), Donald Johnston, Secretary General of the OECD, Rudy Rabbinge, Professor of Land and Water Resources at the University of Wageningen, and Marc van Montagu. There was also a number of representatives of the "South" (a political, not a geographic South) including myself and representatives from Egypt, Brazil, and Kuwait, among others. Although the environmental impacts of genetically modified crops still need careful monitoring and research, the consequences of not developing and planting such crops in the South was felt to outweigh the problems that might be associated with them. People from the South indicated that meetings such as this provided invaluable opportunities for learning about each others' strengths and weaknesses. It also facilitated South-South collaboration, in addition to North-South ones. The importance of private/public cooperation was also stressed. It was pointed out that the North often proclaims the benefits that the South could derive from biotechnology—indeed they often use these reasons to justify the importance of biotechnology. However, they are, for a variety of reasons, failing to substantially invest in the type of biotechnology that will benefit inhabitants of the South.

Thomas Hoban, Professor in the College of Agriculture and Life Sciences at North Carolina State University, helps organizations understand social trends and anticipate the future. He pointed out that society is only starting to come to grips with the nature, scope, and pace of scientific changes associated with biotechnology. On the one hand, public policies are being adopted that would either ban areas of scientific development or establish such stringent regulations that innovation will be stifled. On the other hand, some within the business community argue that the market should be able to sort out the winners from the losers. What is needed is a major commitment toward an open dialogue about the issues associated with biotechnology. This in turn requires a much greater commitment to communication among all segments of society with an interest in our collective future.

In the closing session it was agreed that many of the issues raised in Alexandria should be revisited and updated at the BioVision World Life Sciences Forum to be held in Lyon, France in April 2003.

The time course of Cry1Ab protein production in lines 60 and 73 (another line that produced Bt protein only after induction) was examined by ELISA assay. The protein was first detected 12 - 24 hours after induction and reached a maximum by 48 hours. Western blots of line 60 showed that the protein remained present at high levels for at least four weeks so that a single application of the inducer could give relatively long-term insect control.

Line 60, 67, and 73 are promising materials for use in studies of resistance management via chemically-induced expression of Bt genes. This approach could limit Bt protein production to particular time periods or situations where insect pressure would result in serious crop loss. It could thus foster a more effective insecticide resistance management program within an overall Integrated Pest Management (IPM) concept than constitutive expression of Bt genes. Inducible expression of Bt proteins may be particularly appropriate in situations (e.g., tomato and sweet corn production) where some level of an insect population can be tolerated on the vegetative part of the plant prior to the need to protect the marketable part of the plant. Although application of a chemical to the transgenic crops would be required, BTH has been released by Syngenta as a broad-spectrum plant protection compound ("Actigard™") that is not harmful to humans or to insects. It is therefore already in use for some crops.

While chemically-inducible control of insecticidal transgenes has attractive features, much additional work is required before it can be recommended as an alternative to constitutive expression. We will investigate use of chemically-inducible broccoli plants for resistance management in greenhouse cage tests. The behavior of the PR-1a promoter in field plantings should also be assessed, particularly under exposure to pathogens or other stresses. The long-term time course of Bt protein production must be determined. It is important to avoid possible exposure of insects to plants producing low levels of Bt proteins, since this could encourage selection of resistant insects. BTH (or a similar compound) would have to be approved for application to the target crops. Economic analyses of constitutive and inducible systems are key steps in further assessing the applied value of this technology.

Sources

1. Cao J, Shelton AM, and Earle ED. 2001. Gene expression and insect resistance in transgenic broccoli containing a Bacillus thuringiensis cry1Ab gene with the chemically inducible PR-1a promoter. Molecular Breeding 8: 207-216.

2. Shelton AM, Tang JD, Roush RT, Metz TD, and Earle ED. 2000. Field tests on managing resistance to Bt-engineered plants. Nature Biotechnology 18: 339-342.

3. Tang, JD, Collins HL, Metz TD, Earle ED, Zhao J, Roush RT, and Shelton AM. 2001. Greenhouse tests on resistance management of Bt transgenic plants using refuge strategies. Journal of Economic Entomology 94(1): 240-247.

4. Williams S, Friedrich L, Dincher S, Carozzi N, Kessmann H, Ward E, and Ryals J. 1992. Chemical regulation of Bacillus thuringiensis delta-endotoxin expression in transgenic plants. Bio/technology 10: 540-543.

BIOTECHNOLOGY INSIGHT
How Biotech Crops Protect Water Quality
David I. Gustafson

Protecting rivers, lakes, and streams is one of the greatest environmental challenges facing agriculture today. While soil sediment remains the single biggest concern for rivers and streams, crop protection chemicals also need careful management. Monitoring studies have shown that some pesticide residues are present at detectable levels on agricultural land and occasionally are detectable at concentrations above standards established by the Environmental Protection Agency (EPA). While these standards are highly conservative, and there is no evidence of harm to the public, perceived value exists in the adoption of new practices and technologies that meet agricultural production needs while reducing the use of mobile and persistent crop chemicals. Adoption of biotech crops is one such new practice. Computer models predict that insect-protected and herbicide-tolerant crops may significantly lower pesticide concentrations in both ground and surface waters (Fig. 1). Monitoring data from vulnerable watersheds support the model predictions.

Computer models predict improved water quality

A modeling study¹ predicts that water quality in vulnerable watersheds in the Midwest would be significantly improved if growers planted herbicide-tolerant corn varieties. Researchers used standard computer models employed by the EPA to predict concentrations of the herbicides alachlor, atrazine, glufosinate (Liberty^®), and glyphosate (Roundup^®) in water. They compared several application scenarios, including ones in which Liberty and Roundup post-emergence herbicides were used with LibertyLink^® and Roundup Ready^® corn, respectively.

Because of their lower post-emergence application rates and greater ability to bind to soil, Liberty and Roundup herbicide levels in runoff were predicted to be 1/5th to 1/10th of those of atrazine and alachlor. This key finding indicates that replacement of pre-emergence corn herbicides with post-emergence herbicides applied to biotech crops would dramatically reduce herbicide concentrations in watersheds. Due to the favorable toxicology profiles, Liberty and Roundup herbicides present far less concern to water quality, and they are allowed at much higher levels in water than atrazine or alachlor (Fig. 2).

A second modeling study² similarly predicts lower pesticide concentrations in ground and surface waters as a result of biotech crop adoption. The potential impact on water quality and related ecosystems of three biotech cropping systems was considered: Bt corn, Bt cotton, and herbicide-tolerant corn. The key finding was that all three biotechnology-based cropping systems are predicted to result in significantly lower pesticide concentrations in ground and surface waters, thereby reducing the impact that pesticides can have on water quality and related ecosystems.

Case studies confirm modeling predictions

Bt cotton in the Mississippi Delta
One of the most intensively managed agricultural areas of the United States is the Mississippi River Alluvial Plain in northwestern Mississippi. Concern exists for potential offsite movement of insecticides used on cotton due to the high regional rainfall, low slopes, and slightly permeable soils. The 1996 - 1999 study by Cullum and Smith³ examined fields in the Beasley Lake Watershed planted to Bt cotton and fields in Deep Hollow Watershed planted to non-Bt cotton. Researchers reported a dramatic reduction in the amount of pyrethroid insecticides released into the environment at the Bt cotton sites. They also reported that even though the non-Bt sites resulted in very low detection of pyrethroid insecticides, the Bt cotton sites had even lower concentrations in the runoff.

Roundup Ready soybeans and LibertyLink corn in the Northern Appalachia
In the vulnerable upland soils of the Northern Appalachia, herbicide levels occasionally exceed water standards. Growers use reduced input management practices that lessen, but do not eliminate, the problem. The objective of Shipitalo and Malone's study⁴ was to determine if herbicide levels in runoff could be reduced by replacing pre-emergence, residual herbicides with post-emergence, contact herbicides (Liberty and Roundup herbicides). The researchers found that concentrations of atrazine, and less often alachlor, occasionally exceeded water limits in the vulnerable watersheds studied. Yet Liberty and Roundup herbicide levels remained well below water standards, despite the fact that rainfall occurred two to three days after application. The authors stated that "By growing transgenic corn and soybean and replacing these herbicides [alachlor and atrazine] with post-emergence products glufosinate and glyphosate, the environmental impact of herbicide losses in runoff resulting from production of these crops should be reduced." (Shipitalo & Malone, 2000)

Roundup Ready corn in Illinois
Although not a water quality issue in most areas, pre-emergence herbicides used on corn can be a problematic contaminant issue in some vulnerable watersheds in the Midwest. One of several monitoring studies to examine this is a multi-year, 12-state, 175-site program initiated by the Acetochlor Registration Partnership (ARP) in 1995. During the last three years of the study (1999 - 2001), researchers focused on small watersheds in Illinois with high corn production acreage. Through Monsanto's Downstream Benefits™ program, growers within these watersheds were encouraged to plant Roundup Ready corn using either reduced rates of conventional pre-emergence herbicides or a strictly post-emergence Roundup herbicide program. The benefits of Roundup Ready corn to these Illinois watersheds were significant, as shown in Figure 3.

Of the 131 samples collected in watersheds in which higher amounts of Roundup Ready corn were planted, none had total herbicide concentrations greater than four parts per billion (ppb) and only two samples (two percent) were greater than two ppb for major corn herbicides. Of the 1,185 samples collected in other watersheds, 44 (four percent) had greater than 4 ppb total herbicide concentrations and 145 (12 percent) had greater than 2 ppb total herbicide. The results are particularly impressive because the watersheds chosen were among those that had previously (1995 - 1998) had the highest total herbicide concentrations in water.

Best management practices address water challenges

As predicted by computer models and confirmed by field results, agricultural biotechnology is an additional tool to help growers protect the water supply, particularly in vulnerable watersheds. Other best management practices also can reduce the flow of sediment, nutrients, and chemicals into ground and surface waters. Site selection, application timing and soil erosion prevention methods (e.g., conservation tillage, buffer strips) are all part of overall good land stewardship.

Sources 1. Wauchope RD et al. In press. Predicted impact of transgenic, herbicide-tolerant corn on drinking water quality in vulnerable watersheds of the Midwestern United States. Pest Management Science.

2. Estes TL et al. 2001. Predicted impact of transgenic crops on water quality and related ecosystems in vulnerable watersheds in the United States. Paper presented at the Soil and Water Mini-Symposium, British Crop Protection Council (BCPC) Conference, Weeds, November 2001. Brighton, UK.

3. Cullum RF and Smith S, Jr. 2001. Bt cotton in Mississippi Delta management systems evaluation area: Insecticides in runoff, 1996 - 1999. Oxford, MS: U.S. Department of Agriculture, Agricultural Research Service.

4. Shipitalo MJ and Malone RW. 2000. Runoff losses of pre- and post-emergence herbicides from watersheds in a corn-soybean rotation. Coshocton, OH: USDA-ARS, North Appalachian Experimental Watershed.

Life cycle of the malaria parasite in humans and mosquitoes. (Used with permission:Nature. http://www.nature.com)

The mechanism by which malaria parasites cross the epithelium in the midgut and the salivary glands of the mosquito is unknown but is hypothesized to involve a cell surface receptor. Previous work using phage display technology had identified a 12 amino-acid peptide, called SM1, which bound to both the salivary gland and midgut epithelial cells and inhibited the passage of the parasite across both epithelia. Thus one potential strategy to block Plasmodium development in the mosquito is overexpression of SM1 in the mosquito gut.

Expression of SM1 was placed under the control of the carboxypeptidase (CP) gene promoter and signal sequence. The CP promoter was chosen because it is induced by a blood meal and the CP signal sequence directs secretion of the protein into the lumen of the midgut. The CP-SM1 transgene and the gene for green fluorescent protein under the control of an eye-specific promoter were introduced into the germ line of the mosquito Anopheles stephensi, a primary vector of human malaria in India. Transgenic progeny were identified by detection of green fluorescence in larvae or the eyes of adult mosquitoes.

Four transgenic mosquito lines were developed that expressed the SM1 protein in midgut epithelium. In each line, the transgene integrated into a different part of the mosquito genome. As expected, expression of SM1 RNA and SM1 protein was induced 3 - 6 h and 6 - 24 h, respectively, after a blood meal. This was the ideal scenario for interrupting the lifecycle of the parasite, since ookinetes invade the midgut epithelium 24 hours after a blood meal.

To evaluate the efficacy of SM1 overexpression, transgenic and control mosquitoes were fed on mice infected with Plasmodium berghei, a useful experimental parasite in the laboratory. In transgenic mosquitoes, oocyst formation was inhibited approximately 80% and the number of sporozoites in the salivary glands was reduced compared to non-transgenic mosquitoes. As a final test, the ability of the transgenic mosquitoes to transmit the parasite to uninfected mice was examined. In two of three experiments, no transmission of P. berghei was detected, whereas in the third experiment, transmission was reduced greater than two-fold.

This report demonstrates an important proof-of-principle, that a transgenic mosquito expressing a specific protein can effectively interrupt the replication cycle of a parasite. This opens up the possibility of developing transgenic mosquitoes to control mosquito-borne diseases that affect not only humans but also livestock. For example, mosquitoes are the vectors for transmission of the West Nile virus or equine encephalitis virus to horses. Much work remains, however, before transgenic mosquitoes can be safely released into the environment. Nevertheless, this transgenic approach represents a new tool in the fight to control mosquito-borne diseases.

Source
Ito J, et al. 2002. Transgenic anopheline mosquitoes impaired in transmission of a malaria parasite. Nature 417: 452-455.

For 17 years, Harvard's oncomouse has run the maze of Canada's patenting process. On May 21, the transgenic mouse neared the end of its trip when the Supreme Court of Canada heard oral arguments on whether the critter is patentable under Canadian law.

The oncomouse journey began in 1985 when the President and Fellows of Harvard College filed a patent application with the Canadian Intellectual Property Office (CIPO), which included claims to nonhuman transgenic mammals with cells that contain an activated oncogene. By 1993, the CIPO examiner had decided to allow claims to the process for producing the transgenic mammals, but had rejected claims to the mammals themselves. The CIPO did not consider animals to fit into the patentable categories of "manufacture" or "composition of matter," as Harvard had been arguing.

In August, 1995, after review by the CIPO Commissioner of Patents and an oral hearing before the Patent Appeal Board, the CIPO confirmed the rejection of transgenic mammal claims. Harvard appealed the decision in the Federal Court of Canada, Trial Division.

The Federal Court of Canada dismissed the appeal on April 21, 1998. The judge decided that a transgenic mammal is not truly reproducible because too much is left to chance, including the chromosomal location of the transgene, and the degree of transgene expression. Consequently, the judge concluded that the transgenic mammal was not sufficiently reproducible to be a "composition of matter" or an "article of manufacture" under the Canadian Patent Act. Harvard then appealed its case to the Canadian Federal Court of Appeal.

On August 3, 2000, the appellate court determined that the oncomouse is a composition of matter and sent the case back to the CIPO with the direction to grant a patent on the transgenic animal claims. Now it was the government's turn to appeal. In the name of the Commissioner of Patents, the Attorney General of Canada filed an application to seek appeal to the Supreme Court of Canada. On June 14, 2001, the Supreme Court of Canada granted the application for appeal (Case No. 28155).

During May's oral hearing before the Supreme Court, the federal government warned that a decision to allow the issuance of claims to the oncomouse would open the door to the patenting of genetically-modified humans. On a less bizarre note, another government lawyer argued that the Court must consider the Patent Act in the context in which it was drafted in 1869, a time long before the advent of genetic engineering. Chief Justice Beverley McLachlin dismissed this argument, pointing out that the Patent Act was designed to deal with the development of future, unanticipated inventions. At least one member of the Court seemed skeptical about patenting the oncomouse. Mr. Justice Ian Binnie wondered why Harvard should be entitled to a patent on the transgenic animal when the Harvard researchers had only modified one out of 40,000 genes. Harvard's lawyer argued that the transgenic modification was not just a minor add-on. The nine justices are expected to issue a ruling by the end of this year, a decision that will affect about 600 patent applications on genetically-modified animals and plants.

Other Law News Bits - Monsanto v. Schmeiser: A Battle of Biblical Proportion?

Last year, the Federal Court of Canada (Saskatoon, Saskatchewan) ordered a farmer to pay Monsanto Company thousands of dollars because the company's genetically-engineered canola plants were found growing on the farmer's field. The case reaped worldwide attention in part because the farmer apparently was not taking advantage of the genetically-modified feature of the canola plants, and because the farmer's liability was based on a determination of patent infringement in a country that does not grant patents on plants.

In Monsanto v. Schmeiser, Monsanto sued Percy Schmeiser for infringing Canadian Letters Patent No. 1,313,830, which includes claims to a chimeric plant gene encoding 5-enolpyruvylshikimate-3-phosphate synthetase, an enzyme that confers resistance to glyphosate herbicide (sold as "Roundup"). The patent also includes claims to plant cells that contain the chimeric plant gene. Monsanto Canada licenses Canadian commercial seed growers to grow Roundup Ready canola, which expresses the patented gene.

The seed of a lawsuit was planted in the summer of 1997 when Monsanto received an anonymous tip that Roundup Ready canola was growing in Schmeiser's fields, even though the farmer did not have a license from Monsanto. The company sent Robinson Investigations, a private agency in Saskatoon, to perform random audits of canola crops growing in Saskatchewan. This led to the identification of Roundup Ready canola and the filing of the lawsuit.

During the trial, Schmeiser argued that the canola plants appeared on his farm as the result of cross-field breeding by wind or insects, among other potential scenarios. Judge W. Andrew MacKay, however, was persuaded by Monsanto's evidence that none of these potential sources of "contamination" could account for the concentration or extent of Roundup Ready canola present in the defendant's field. Besides, the judge emphasized that the source of Roundup resistant canola was "really not significant" for the resolution of the issue of infringement. Rather, the question was whether the defendant had made, used, or sold the patented invention.

The judge concluded that, in 1998, the defendant infringed Monsanto's patent by planting canola fields with seed saved from the previous year's crop, which was known or ought to have been known by the defendant to be Roundup tolerant and which contained the genes and cells claimed under Monsanto's patent. The defendant further infringed by selling seed harvested in 1998. After the court ordered Schmeiser to pay Monsanto, the defendant filed an appeal with the Federal Court of Appeal.

In May, the appellate court held two days of hearings to consider Schmeiser's appeal. Two of the three justices on the panel asked how a person could infringe Monsanto's patent if he did not know that Roundup Ready canola was growing in his field. As the lower court noted, however, intent does not enter into the basic question of patent infringement: a person either does or does not infringe a patent claim.

At least one of the appellate justices voiced concern that Monsanto could sue a farmer for patent infringement if the farmer had only two percent Roundup Ready resistant canola in 1,000 acres of conventional canola. Monsanto's lawyer responded that the company would not pursue such farmers through the court system, but would seek another solution. Justice Marc Noel, however, did not seem to find any comfort in "the good grace of Monsanto." It is nevertheless true that companies often refrain from suing for patent infringement if the costs outweigh the benefits.

Mr. Schmeiser has modestly depicted the dispute as "the classic David vs. Goliath struggle," and he has pelted Monsanto with 17 issues for appeal. When it comes to fighting a Goliath, however, a true aim counts for more than the number of stones slung.

Finally: The Festo Manifesto

On May 28, a unanimous US Supreme Court handed down one of the most anticipated decisions in the area of patent law, a ruling that affects the ability of a patent owner to successfully sue for infringement and that vacates the Federal Circuit's Festo decision. Before mulling over the Supreme's take on Festo, a short review is in order.

Courts analyze patent infringement in two stages. The first stage requires an interpretation of the meaning of the claim language and the scope of the claims. The second stage requires a determination of whether the defendant's product or process falls within the scope of the interpreted claims. If every limitation recited in a claim is found in an accused product or process, then the defendant has literally infringed the patent claims. On the other hand, if there is no literal infringement a court may still find that the defendant infringed under the doctrine of equivalents (DOE), a principle devised to prevent a person from getting around a patent by making merely insubstantial changes to the patented invention. The DOE allows a court to expand the literal interpretation of a patent claim and to recognize near-literal copying of a patented invention. However, there are limitations on the doctrine's use.

One limitation of the DOE is provided by prosecution history estoppel: a patent applicant cannot recover subject matter that the applicant surrendered during patent prosecution to obtain the patent. For example, suppose that a patent applicant tried to claim all polypeptides having the function of a native Bacillus thuringiensis toxin and that have an amino acid sequence at least 80% identical to the amino acid sequence of "SEQ ID NO:1." The examiner rejects the claim on the basis that the patent specification does not teach how to make toxins that are only 80% identical to the particular sequence. Eventually, the applicant narrows the claim to Bt-like polypeptides having amino acid sequences that are at least 90% identical to SEQ ID NO:1, and the patent issues. Prosecution history estoppel will prevent the patentee from successfully arguing that the DOE will expand the scope of the claim to cover Bt-like polypeptides with 80% amino acid sequence identity. But can the patentee use the DOE to expand the claim to cover polypeptides with identities between 80 to 90%? The Federal Circuit's Festo decision says "no."

In Festo, the Federal Circuit abolished the "flexible bar" theory of prosecution history estoppel in favor of an "absolute bar" rule. Under the flexible bar theory, a patentee can establish infringement outside the literal scope of an amended claim by showing that the patentee had not surrendered this subject matter to obtain the patent. Under the absolute bar approach, the patentee is deemed to have surrendered all subject matter outside the literal scope of the amended claim element. This means that the patentee no longer has the opportunity to show that certain equivalents would not have been barred from the scope of the claim by prior art or other patentability requirements. The operation of the absolute bar is illustrated by Mycogen v. Monsanto (59 USPQ2d 1852 (CA FC 2001)), in which Mycogen had apparently given up a broad claim to synthetic Bt toxin genes for a claim to a gene having a particular nucleotide sequence. Applying the absolute bar, the court would not allow operation of the DOE to expand Mycogen's claim to include Monsanto's gene with a nucleotide sequence that differed from Mycogen's sequence by 19%. This case also shows why the Federal Circuit's Festo decision was not popular with many patent owners.

The Supreme Court also did not care for the Festo decision. Chastising the lower court for ignoring Supreme Court precedent, Justice Kennedy wrote that instituting an absolute bar would be unfair to patent owners who had made decisions during patent prosecution in reliance of the flexible bar. Nevertheless, the Court seems to have met the Federal Circuit part way. Under the Supreme Court's ruling, there is a flexible bar, but the patentee must now overcome a presumption that prosecution history estoppel created an absolute bar. Going back to the hypothetical case, narrowing the claims from "at least 80%" identity to "at least 90%" identity, creates a presumption that the patentee's claim cannot cover polypeptides falling within the 80% to 90% range. The patentee can overcome this presumption by showing that, "at the time of the amendment, one skilled in the art could not reasonably be expected to have drafted a claim that would have literally encompassed the alleged equivalent." Just how a patentee can effectively make this showing will be determined as the Court's Festo rule is played out in the courts.