RNA-interference pesticides will need special safety testing

Contact: Tim Beardsley tbeardsley@aibs.org 703-674-2500 x326 American Institute of Biological Sciences

A new technology for creating pesticides and pest-resistant crops could have effects on beneficial species that current toxicity testing will miss

Standard toxicity testing is inadequate to assess the safety of a new technology with potential for creating pesticides and genetically modifying crops, according to a Forum article published in the August issue of BioScience. The authors of the article, Jonathan G. Lundgren and Jian J. Duan of the USDA Agricultural Research Service, argue that pesticides and insect-resistant crops based on RNA interference, now in exploratory development, may have to be tested under elaborate procedures that assess effects on animals’ whole life cycles, rather than by methods that look for short-term toxicity.

RNA interference is a natural process that affects the level of activity of genes in animals and plants. Agricultural scientists have, however, successfully devised artificial “interfering RNAs” that target genes in insect pests, slowing their growth or killing them. The hope is that interfering RNAs might be applied to crops, or that crops might be genetically engineered to make interfering RNAs harmful to their pests, thus increasing crop yields.

The safety concern, as with other types of genetic modification and with pesticides generally, is that the artificial interfering RNAs will also harm desirable insects or other animals. And the way interfering RNA works means that simply testing for lethality might not detect important damaging effects. For example, an interfering RNA might have the unintended effect of suppressing the action of a gene needed for reproduction in a beneficial species. Standard laboratory testing would detect no harm, but there could be ecological disruption in fields because of the effects on reproduction.

Lundgren and Duan suggest that researchers investigating the potential of interference RNA pesticides create types that are designed to be unlikely to affect non-target species. They also suggest a research program to evaluate how the chemicals move in real-life situations. If such steps are taken, Lundgren and Duan are optimistic that the “flexibility, adaptability, and demonstrated effectiveness” of RNA interference technology mean it will have “an important place in the future of pest management.”



BioScience, published monthly, is the journal of the American Institute of Biological Sciences (AIBS; http://www.aibs.org). BioScience is a forum for integrating the life sciences that publishes commentary and peer-reviewed articles. The journal has been published since 1964. AIBS is a meta-level organization for professional scientific societies and organizations that are involved with biology. It represents nearly 160 member societies and organizations. The article by Lundgren and Duan can be accessed ahead of print as an uncorrected proof at http://www.aibs.org/bioscience-press-releases/ until early August.

The complete list of peer-reviewed articles in the August 2013 issue of BioScience is as follows. These are now published ahead of print.

Improving Ocean Management through the Use of Ecological Principles and Integrated Ecosystem Assessments. Melissa M. Foley, Matthew H. Armsby, Erin E. Prahler, Margaret R. Caldwell, Ashley L. Erickson, John N. Kittinger, Larry B. Crowder, and Phillip S. Levin

How Far Are Stem-Cell-derived Erythrocytes from the Clinical Arena? Xiaolei Li, Zhiqiang Wu, Xiaobing Fu, and Weidong Han

Invasive Plants in Wildlife Refuges: Coordinated Research with Undergraduate Ecology Courses. Martha F. Hoopes, David M. Marsh, Karen H. Beard, Nisse Goldberg, Alberto Aparicio, Annie Arbuthnot, Benjamin Hixon, Danelle Laflower, Lucas Lee, Amanda Little, Emily Mooney, April Pallette, Alison Ravenscraft, Steven Scheele, Kyle Stowe, Colin Sykes, Robert Watson, and Blia Yang

RNAi-based Insecticidal Crops: Potential Effects on Nontarget Species. Jonathan G. Lundgren and Jian J. Duan

Expert Opinion on Climate Change and Threats to Biodiversity. Debra Javeline, Jessica J. Hellmann, Rodrigo Castro Cornejo, and Gregory Shufeldt

Discovering Ecologically Relevant Knowledge from Published Studies through Geosemantic Searching. Jason W. Karl, Jeffrey E. Herrick, Robert S. Unnasch, Jeffrey K. Gillan, Erle C. Ellis, Wayne G. Lutters, and Laura J. Martin

Persistent pollutant may promote obesity: Tributyltin shown to affect gene activity at extremely low concentrations

2008 study posted for filing

Contact: Jennifer Williams
202-628-1500 x209
American Institute of Biological Sciences

Persistent pollutant may promote obesity

Compound shown to affect gene activity at extremely low concentrations

Tributyltin, a ubiquitous pollutant that has a potent effect on gene activity, could be promoting obesity, according to an article in the December issue of BioScience. The chemical is used in antifouling paints for boats, as a wood and textile preservative, and as a pesticide on high-value food crops, among many other applications.

Tributyltin affects sensitive receptors in the cells of animals, from water fleas to humans, at very low concentrations—a thousand times lower than pollutants that are known to interfere with sexual development of wildlife species. Tributyltin and its relatives are highly toxic to mollusks, causing female snails to develop male sexual characteristics, and it bioaccumulates in fish and shellfish.

The harmful effects of the chemical on the liver and the nervous and immune systems in mammals are well known, but its powerful effects on the cellular components known as retinoid X receptors (RXRs) in a range of species are a recent discovery. When activated, RXRs can migrate into the nuclei of cells and switch on genes that cause the growth of fat storage cells and regulate whole body metabolism; compounds that affect a related receptor often associated with RXRs are now used to treat diabetes. RXRs are normally activated by signaling molecules found throughout the body.

The BioScience article, by Taisen Iguchi and Yoshinao Katsu, of the Graduate University for Advanced Studies in Japan, describes how RXRs and related receptors are also strongly activated by tributyltin and similar chemicals. Tributyltin impairs reproduction in water fleas through its effects on a receptor similar to the RXR. In addition, tributyltin causes the growth of excess fatty tissue in newborn mice exposed to it in utero. The effects of tributytin on RXR-like nuclear receptors might therefore be widespread throughout the animal kingdom.

The rise in obesity in humans over the past 40 years parallels the increased use of industrial chemicals over the same period. Iguchi and Katsu maintain that it is “plausible and provocative” to associate the obesity epidemic to chemical triggers present in the modern environment. Several other ubiquitous pollutants with strong biological effects, including environmental estrogens such as bisphenol A and nonylphenol, have been shown to stimulate the growth of fat storage cells in mice. The role that tributyltin and similar persistent pollutants may play in the obesity epidemic is now under scrutiny.




After noon EST on 1 December and for the remainder of the month, the full text of the article will be available for free download through the copy of this Press Release available at http://www.aibs.org/bioscience-press-releases/.

BioScience, published 11 times per year, is the journal of the American Institute of Biological Sciences (AIBS). BioScience publishes commentary and peer-reviewed articles covering a wide range of biological fields, with a focus on “Organisms from Molecules to the Environment.” The journal has been published since 1964. AIBS is an umbrella organization for professional scientific societies and organizations that are involved with biology. It represents some 200 member societies and organizations with a combined membership of about 250,000.