A series on the historical, philosophical, and scientific foundations of the GM crop debate.
Heralded as both the cause and the solution of the world’s food production problems, genetically modified organisms, or GMOs, have become a hotly debated topic since they were first approved for use and human consumption in North America in the mid-1990s. The poles of the debate include staunch advocates of GM crops and environmental dissenters: large agribusinesses, such as Monsanto, who argue for the safety and utility of GMOs, and organizations such as Greenpeace International who maintain that the threat posed by GMOs is unprecedented and must be avoided at all costs. Ad campaigns, activist rallies, and glossy brochures abound in defense of each position.
In the midst of this debate it is easy to get lost in a mass of scary hypotheses, burdensome statistics, and confusing scientific terms. Yet, basic issues are left painfully undiscussed: what does it mean for a crop to be ‘genetically modified’ (is genetic modification a problem? If so, why?); what is the historical place of GMOs in agriculture (aren’t all crops ‘genetically modified’?); what is the role of private corporations in their production and distribution (are GMOs produced by evil multi-national corporations bent on world domination?); and what are the intellectual property structures that influence the creation of GMOs (you can patent a plant?).
This series of blog posts is aimed at clarifying these issues by discussing what it actually means when a crop is ‘genetically modified,’ what the arguments are about the potential impact on the environment and human health, and what the relationship is between international patent structures and the food on your fork.
Part 1: What is a GMO?
Genetically modified organism – GMO – is a vague category at best. First of all, what organisms are we actually talking about? And what sort of genetic modification are we worried about? First off, while GMOs could refer to any living organism that has been genetically modified in some capacity, the acronym is usually used to refer to crops – plants used in agricultural systems. Second, the critically minded among us may point out that all crops are genetically modified. Genetic modification is the nature of agriculture; humanity has been modifying the living world to suit their food production needs for millennia, beginning by simply selecting seeds from the plants that look the best for planting the next season. But, when people talk about GMOs they are usually referring to a particular type of genetic modification, recombinant DNA (rDNA) technology.
Understanding the process by which GMOs are genetically modified is of paramount importance to understanding the debate regarding GMOs, and is the true beginning of the GMO story.
The development of recombinant DNA technology
In the 1970s, biology found itself in uncharted territory. Previously one of the least profitable scientific disciplines, in 1973 biology came to include a profitable new tool, recombinant DNA technology. The ability to splice sections of DNA encoding particular genes, insert those genetic segments into a different host organism in a controlled and predictable manner, and have that host organism express the trait of interest, held both huge industrial potential and risk.
Finding a pair of scissors
The tools that would eventually become recombinant DNA technology were coming fast in the early 1970s. Hamilton Smith, a microbiologist at Johns Hopkins University, had already discovered and published papers regarding the nature of Class II restriction endonucleases – enzymes that cut DNA strands predictably at the same location. This was paramount to the development of recombinant DNA technology because it provided scientists with the necessary ‘scissors’ to cut double stranded DNA in a consistent and predictable manner. Using these enzymes, specific genes of interest could be removed from a whole genome. Some Class II restriction endonucleases proved especially beneficial to biotech advances because they produced cohesive or ‘sticky’ ends, which allowed for easy recombination of DNA cleaved with the same enzyme. As all DNA, regardless of its origin, is essentially the same, the discovery of Class II restriction endonucleases opened up great opportunity for the recombination of DNA from a several different origins, even from different species. It was soon after the discovery of class II restriction endonucleases that scientists were able to successfully incorporate a spliced gene into a host genome.
Figuring out how to cut and paste
The first scientists to replicate or amplify a recombinant genome met at a 1972 plasmid convention in Hawaii. There, Stanley Cohen, a professor of medicine at Stanford University, and Herbert Boyer, a biochemist from the University of California at San Francisco, met in a deli and sketched out on a napkin what would become the basis of biotechnology. Boyer had earlier identified the restriction endonuclease EcoRI after isolating it from the bacterium E. coli. As for Cohen, he had been focusing on cloning antibiotic-carrying plasmids in E. coli after coming up with a method to get plasmids into the bacterium. At the time of their meeting, Cohen hypothesized plasmids could be used as cloning vectors – that is, a means by which desired DNA sequences could be incorporated into a host genome and replicated.
With their complementary interests, Boyer and Cohen agreed to collaborate and set to incorporating spliced DNA into plasmids that could then be cloned in vitro. It proved to be one of the most fruitful partnerships in the history of biology. Within four months of their meeting, Cohen and Boyer successfully spliced foreign DNA into a plasmid and replicated the plasmid in an E. coli bacterium. Boyer and Cohen published their findings in Proceedings of the National Academy of Sciences (vol. 70, no. 11) in a paper entitled “Construction of Biologically Functional Bacterial Plasmids In Vitro.”
Cohen and Boyer followed up the 1973 paper as co-authors of “Replication and Transcription of Eukaryotic DNA in Escherichia coli” a paper published in the May 1974 edition of Proceedings. This time, a team of scientists illustrated the ability of transformed bacteria to replicate eukaryotic DNA from an animal source. In this experiment, DNA from Xenopus laevis, commonly referred to as African clawed frog, was digested using EcoRI, placed within a plasmid, and replicated within E. coli. This experiment proved to be particularly groundbreaking as it illustrated the strength of recombinant DNA technology, which had previously only been theorized: In 1974, scientists had replicated spliced eukaryotic DNA using a bacterial host.
The potential of such an advancement seemed limitless. Yet this fostered both fear and hope, demanding a response from the scientific community and government regulators. Both groups would respond, and their reactions laid the foundation for many of the issues surrounding GMOs today.