A new generation of pesticides designed to deal with the current failure of genetically modified organisms, is supposed to hit the agricultural market in the near future. The basis of action for the new generation is called RNA interference.
However, two USDA scientists have called for extended toxicity testing mirroring the concerns expressed by Professor Jack Heinemann, an Australian scientist. The scientists express their concerns that current methods of safety testing do not examine the effects on the entire organism or the potential for RNA strands to interact with genes as a whole creating the expression of new diseases.
The principle behind RNA interference pesticides is that artificially designed interfering RNA will be designed to target genes in insect pests, inhibiting their development or killing them; however, the unintended effect on genes of other animals and humans are currently unknown.
Professor Heinemann, an outspoken Australian Scientist has previously warned about the ability of double stranded RNA to enter the blood stream and organs via the food supply. A 2011 paper published in Cell Research specifically confirmed that plant double stranded RNA can “bind to the nucleotide sequence located in exon 4 of mammalian LDLRAP1, leading to the inhibition of LDLRAP1 expression in vivo.”
DNA and RNA are not a stagnant phenomena, and the prevailing available research points to a considerable public health risk when experimenting with fragments of DNA and RNA inserted into GMOs that end up in our food supply, with unknown health consequences. The human genome shares several peculiarities with the DNA of just about every other plant and animal. The human genetic blueprint contains numerous entities known as transposons, or “jumping genes,” which have the ability to move from place to place on the chromosomes within a cell.
Approximately 50% of human DNA comprises both active transposon elements and the decaying remains of former transposons that were active thousands to millions of years ago before becoming damaged and immobile. Every time a plant, animal or human cell prepares to divide, the chromosome regions richest in transposon-derived sequences, even elements long deceased, are among the last to duplicate.
New research led by Carnegie’s Allan Spradling detailed the spread of one particular jumping gene in the Drosophilia genome, called the P element, to illustrate their point; namely that these elements have the ability to move around and insert themselves into different spots in the genome.
P elements insert into DNA very selectively. Nearly 40% of new jumps occur within just 300 genes and always near the beginning of the gene. But the genes seemed to have nothing in common. When these sites were compared to data about the Drosophila genome, particularly recent studies of Drosophila genome duplication, the answer became clear. What many P insertion sites share in common is an ability to function as starting sites or “origins” for DNA duplication. This association between P elements and the machinery of genome duplication suggested that they can coordinate their movement with DNA replication. Spradling and his team propose that P elements — and likely other transposons as well — use a replication connection to spread more rapidly through genomes. These elements would only transpose after replicating, and then preferentially insert themselves into portions of DNA that have not yet become activated.
The consequences of horizontal gene transfer in association with genetically modified organisms cannot be underestimated despite the considerable denial of GM developers and FDA regulators. The cautious approach by two USDA scientists seems to mirror that sentiment.
Jonathan G. Lundgren and Jian J. Duan. RNAi-based Insecticidal Crops: Potential Effects on Nontarget Species. BioScience, 2013
Sándor Spisák, Norbert Solymosi, Péter Ittzés, András Bodor, Dániel Kondor, Gábor Vattay, Barbara K. Barták, Ferenc Sipos, Orsolya Galamb, Zsolt Tulassay, Zoltán Szállási, Simon Rasmussen, Thomas Sicheritz-Ponten, Søren Brunak, Béla Molnár, István Csabai. Complete Genes May Pass from Food to Human Blood. PLOS ONE. July 30, 2013
Heinemann, J. A., B. Kurenbach, and D. Quist. 2011. Molecular profiling — a tool for addressing emerging gaps in the comparative risk assessment of GMOs. Env. Int. 37:1285-1293.
Zhang, L., D. Hou, X. Chen, D. Li, L. Zhu, Y. Zhang, J. Li, Z. Bian, X. Liang, X. Cai, Y. Yin, C. H. Wang, T. Zhang, D. Zhu, D. Zhang, J. Xu, Q. Chen, Y. Ba, J.-J. Liu, Q. Wang, J. Chen, J. Wang, M. Wang, Q. Zhang, J. Zhang, K. Zen, and C.-Y. Zhang. 2012. Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of cross-kingdom regulation by microRNA. Cell Res 22:107-126.
Evaluation of risks from creation of novel RNA molecules in genetically engineered wheat plants and recommendations for risk assessment An expert opinion of Professor Jack A. Heinemann, PhD, 28 August 2012 , for the Centre for Integrated Research in Biosafety
A. C. Spradling, H. J. Bellen, R. A. Hoskins. Drosophila P elements preferentially transpose to replication origins. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1112960108