Report Outlines Benefits and Drawbacks of Genetically-Engineered Crops; Looks Toward Future

The National Research Council (NRC), a part of the National Academies, recently published a report that provides a detailed assessment of the impact of genetically-engineered (GE) crops on farmers. Genetically-engineered crops were first introduced to farm fields in 1996. Today, GE crops account for over 80 percent of the soybean, corn, and cotton grown in the United States. The majority of these GE crops are resistant to glyphosate (the active ingredient in RoundUp weedkiller) and make Bacillus thuringiensis, or Bt, a bacterium that is poisonous to the insects that eat it.
The NRC tied GE crops to a number of benefits, including:

  • lower production costs,
  • fewer pest problems,
  • reduced use of pesticides, and
  • greater crop yields.

A number of environmental benefits were also associated with GE crops. The greatest benefit was seen in terms of water quality. Due to the use of fewer pesticides and insecticides, hazardous chemical run-off is less of a problem at farms that grow genetically-engineered crops.

One worry of using these glyphosate-resistant GE crops is that problems with weeds could arise in the future as the weeds themselves become resistant to glyphosate. This resistance has already arisen in nine weed species since the introduction of GE crops. The report authors suggest that farmers utilizing GE crops should not make the crops themselves their only weed/insect management program. Instead, to maintain the crops’ effectiveness against weeds, it is suggested that farmers use an integrated weed management system that involves pesticides other than glyphosate. As to fending off insect pests, the NRC recommends that farmers continue to utilize EPA-mandated “refuges” in which conventional crops are grown alongside their GE crop fields. The thought behind these refuges is that the insects will opt to feed on the conventional plants and not the GE crops, thus reducing the chance of the insects becoming resistant to the inserted Bt gene.

In the report, the National Resource Council provides a number of suggestions for future studies and research. One such suggestion is to further study the impact that genetically-engineered crops have on both conventional and organic farmers. In addition, the NRC suggests that government support be made available to researchers interested in studying genetically-engineered crops that provide a public benefit, such as reduced environmental impact.

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Delivering Vaccines Through Reengineered Food Poisoning Microbes

Researchers based at the Monash Institute of Pharmaceutical Sciences located at Monash University in Melbourne, Australia have discovered a way to deliver a vaccine orally with the help of a genetically engineered harmless version of the dangerous bacteria Listeria monocytogenes.

L. monocytogenes lives in soil and water. Foods such as fruits or vegetables may become contaminated with Listeria from the soil. Food from animal sources, such as meat or dairy products, may become contaminated from infected animals (which often show no symptoms of infection). If present, the Listeria bacterium is normally killed during the pasteurization process or cooking. However, improper food handling following processing can result in L. monocytogenes contamination.

Contamination by L. monocytogenes results in the food-borne illness called listeriosis. Symptoms of listeriosis include fever, muscle aches, and gastrointestinal conditions such as nausea or diarrhea. Listeriosis can also spread into the nervous system, leading to headaches, confusion, stiff neck, loss of balance, or convulsions. Those most susceptible to Listeria infections include pregnant women, infants, the elderly, and those with compromised immune systems.

Listeria is effective because it is able to survive the harsh, acidic conditions of the stomach and, using a protein called invasin, is able to penetrate epithelial host cells in the gastrointestinal tract. Colin Pouton and his colleagues at Monash University exploited this characteristic in developing their oral vaccine using a modified L. monocytogenes as the carrier. Oral vaccines are typically not effective because they are destroyed by stomach acid; since this is not a problem for the Listeria bacterium, this quality makes Listeria an excellent way to transport a vaccine.

In their research, the scientists created a new strain of L. monocytogenes that rendered the bacteria harmless and could instead by packed full of medicine or a vaccine. The thought was that the modified Listeria bacterium could be used to infect the recipient with a beneficial vaccine. The scientists also made the new strain of L. monocytogenes suicidal, meaning that the bacteria burst and die after entering the host cells.

In a trial run using intestinal cells grown in the lab, the scientists showed that the modified Listeria strain was able to successfully infiltrate the cells, deliver the intended protein, and then die, causing no harm to the intestinal cells themselves. Though encouraged by these early findings, more research will be necessary before this oral vaccination can be used in human subjects.

The results of the scientists research were published in the journal Molecular Pharmaceutics. Scientists who contributed to this research include Cheng-Yi Kuo, Shubhra Sinha, Jalal A. Jazayeri, and Colin W. Pouton.

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Scientists Develop Iron-Rich Rice Plant

Iron deficiency can be a problem for those who do not eat a well-balanced diet, and it can be an especially insidious problem for populations in developing countries. Women and children are particularly vulnerable to iron deficiency. Symptoms of iron deficiency include pronounced fatigue and an inability to metabolize certain harmful substances. Iron deficiency can lead to anemia, which is a condition in which the body does not produce enough healthy red bloods necessary to transport oxygen to the body’s tissues. In many developing countries, one of the major food sources (and sometimes only food source) is rice. Rice, in its unaltered form, is actually a good source of iron. However, most rice provided to populations in developing countries is peeled rice; that is, the seed coat has been removed. The seed coat is often removed to give the rice a longer shelf life; rice that retains its seed coat is likely to spoil faster in sub-tropical and tropical climates typically found in developing countries.

Because iron supplements or other food sources are not readily available or overly expensive, scientists are working on developing an iron-rich variety of rice. Researchers at the Swiss Federal Institute of Technology Zurich (also referred to as ETH Zurich) have had success in doing just that.

Lead researchers Christof Sautter and Wilhelm Gruissem worked with colleagues to genetically modify a rice plant to increase its iron content. In their experiment, the scientists inserted two plant genes into an existing variety of rice. The two inserted plant genes work together to both mobilize and store iron. In addition, the inserted genes aid in the rice plant’s ability to absorb a greater quantity of iron from the soil and also store more iron in the rice kernel. Most importantly, the modified rice plant was shown to have a six-fold increase in iron content compared to a typical (unmodified) rice plant.

More research and experiments, including tests to see whether the modified rice plants will grow under typical agricultural conditions, are necessary before the modified rice plants will be available commercially. Regulations require that genetically-modified seeds and plants must undergo a rigorous period of greenhouse and field testing to ensure that it is safe for human consumption and will not have negative impacts on an ecosystem. In addition, the scientists are interested in increasing the modified rice plant’s iron content to at least twelve-fold; that is, twice the level they currently have achieved. Upon the modified rice plants eventual assumed approval, the scientists would like to provide it to small-scale and self-sufficient farmers at no cost, given the crop’s humanitarian implications.

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