Improving Detection and Analysis of Genetically Modified Organisms

For thousands of years, humans practiced the selective breeding of plants and animals in hopes of improving hardiness, yield, disease resistance and quality. It could take decades to see the results, which were often hit-and-miss. What used to be a slow and inexact process has been revolutionized by recent discoveries about the structure and workings of DNA. Altering the genetic information of an organism through genetic engineering can achieve genetic modification (GM) within one generation.

Molecular biology makes it possible to identify specific, desirable genes and to decode, manipulate, copy and transfer them into other organisms. Compared to traditional breeding methods, GM dramatically accelerates the process of genetic variation and allows much greater precision in selecting and achieving the desired characteristics. It also makes it possible to transfer genes from one species to another. GM pineapples, lentils and tomatoes are a few examples of the "transgenic" foods currently on the market.

Novel concerns and consequences

Using GM to enhance crop characteristics gives humankind the potential to significantly improve the quantity and quality of the world's food supply, and is cited by many as a way to help address the problems of world hunger and malnutrition. However, the increased use of genetically modified organisms (GMOs) in food products is raising concerns about the possible long-term effects on human health and the environment. Two major commodity crops, GMO maize and soya, grown on a large scale throughout the world, particularly in North America, have attracted the most attention.

The key is information. Although tests are being conducted to determine the long-term effects of GM foods, many nations want to give their consumers a choice. As a result, several countries have passed regulations that require the labeling of all GM foods (also called novel or transgenic foods). Australia and New Zealand jointly adopted a labeling policy in July 2000, and mandatory labeling went into effect in Japan in April 2001. Since January 2000, the European Union has required the labeling of food containing more than 1% of GMOs.

Food manufacturers and retailers are responsible for complying with these regulations. But it can be very difficult to accurately detect and quantify small amounts of GMOs, particularly in processed foods. Researchers have been working to develop and refine analytical methods that will enable food producers and suppliers to meet the new labeling requirements.

Amplifying and analyzing DNA

When analyzing for GMOs, the material to be sampled commonly contains both modified and unmodified foods. However, heavily processed foods contain a small amount of usable DNA, so the first step is the identification and amplification of segments that contain genetic information specific to the GM and naturally occurring organisms. This is done by means of the polymerase chain reaction (PCR), which allows rapid, sensitive and specific detection of these genetic markers.

PCR works like a copy machine for DNA and specific segments of DNA called primers can be selected to distinguish between natural foods and GMOs. The primers begin the bio-chemical reaction and identify the portion of DNA to be copied. This allows the DNA-copying enzyme (polymerase) to 'zoom in' on specific regions of DNA and amplify this region exponentially. The product created as a result of the PCR reaction must then be analyzed to confirm the length of each DNA fragment (sizing) and the amount contained in the sample (quantification).

Traditionally, this analysis has been done with gel electrophoresis, a process that requires skilled users who apply samples by hand onto gel slices. When voltage is applied to the gel, molecules separate into bands, a process that can take several hours. After visualization of these bands (staining), the results are read by visual inspection or by further processing with gel scanners and appropriate software. This process has some serious disadvantages: it is labor intensive, time consuming, and subject to human error.

Accelerating the process

The Agilent 2100 bioanalyzer eliminates many of these problems by utilizing lab-on-a-chip technology co-developed by Caliper Technologies Corporation and Agilent Technologies. Using this microfluidic capillary electrophoresis approach, the 2100 bioanalyzer automates sample injection, separation, detection, and analysis, is easy to use, and is capable of analyzing twelve samples in a run time of only 30 minutes. It provides better sensitivity, resolution and reproducibility than gel electrophoresis and gives exact quantification and sizing information about the sample. Results are presented in a simulated gel image, an electropherogram, and tabular format for easy display, manipulation and electronic sharing.

These advantages have made the 2100 bioanalyzer the analysis method of choice for Genolife, a biotechnology laboratory in Europe that specializes in molecular biology as it applies to agro-food, pharmaceutical and cosmetic products. Genolife has been doing GMO testing since 1997. Its customers include seed producers, farmers, the food and feed industry, and food distributors, many of whom require fast analysis of samples with five to ten genetic targets per sample. Genolife uses the Agilent 2100 bioanalyzer to analyze and identify each of these targets. Because the 2100 bioanalyzer can screen many samples at once and identify many genetic targets, it provides the speed and accuracy that Genolife needs, and combined with PCR, makes it possible to provide screening, identification and quantification of more than a hundred targets in only two to three hours and to provide results to its customers in only 24 hours.

These faster and more efficient processes for DNA analysis can increase the amount of information available to all of us, from the scientists who are enhancing crop characteristics to the consumers who want to make informed decisions about which products they buy.

For more information

The Agilent 2100 bioanalyzer system includes an operating computer with system software, the 2100 bioanalyzer equipped with an electrode cartridge for molecular assays plus startup accessories and an optional printer. An add-on pressure cartridge is available for cell-based assays.

Agilent's Life Sciences and Chemical Analysis Group provides a wide range of innovative solutions for chemical and biochemical researchers. To learn more about the Agilent 2100 bioanalyzer system, as well as other products and resources, please return to the main page of the Life Sciences/Chemical Analysis section of our Web site.