Feb. 15, 2009 Medical scientists in Minnesota are focusing their expertise on a pest that destroys soybeans. The goal of the Minnesota Partnership team is to develop an insecticide that is safe for humans but will kill the soybean aphid, a bug that's been ravaging Minnesota crops. Their findings appear in the journal Public Library of Science -- PLoS One.
"We've shown in the laboratory that we're 99 percent effective in inhibiting a key enzyme in two aphids, one that damages soybeans," says Stephen Brimijoin, Ph.D., a Mayo Clinic researcher on the team. "This means we should be able to stop the insect without harming other animals or humans because the target we're hitting is selective to the aphid."
Dr. Brimijoin collected soybean aphids from demonstration plots at the University of Minnesota Extension facility in Rochester and isolated the key enzyme in the aphids, while Yuan-Ping Pang, Ph.D., Mayo Clinic co-investigator, characterized the molecular structures of the target area.
"We're reporting the development of a small molecule that blocks nearly all acetylcholinesterase (AChE) activity in the greenbug and the soybean aphid, but without inhibiting AChE in humans," says Dr. Pang. "Now we need to see how well that translates to the field." Overseeing that phase will be David Ragsdale, Ph.D., an entomologist at the University of Minnesota and another co-investigator. The researchers estimate that phase of the project will begin in a few weeks.
"Our organization is excited about this project and closely awaiting the outcome," says Gene Stoel, research chair, Minnesota Soybean Research and Promotion Council. "This is a great example of how Minnesota's medical and agriculture sectors can work together for everyone."
Currently, no insecticide can counter the soybean aphid, according to Dr. Brimijoin. Various aphid species adapt to organophosphate insecticides and those chemicals can often prove toxic to birds and humans. Instead of targeting serine, as has been the case for decades, the small molecule developed by Dr. Pang focuses on a novel cystine target called Cys289, to which aphids and other insects cannot develop a resistance. Only 6 micromoles in size, the molecule caused "irreversible inhibition" in the greenbug. It had the same impact on the soybean aphid, though that data was too recent to include in the article.
The Minnesota Partnership for Biotechnology and Medical Genomics has been funding research aimed at disease for five years. The soybean aphid research shows the broader benefits of modern genomic and molecular science in Minnesota's top medical research institutions. It also demonstrates an expansion from treating or curing patients to preventing diseases through proactively improving environmental health.
Other support for the soybean aphid research came from the U.S. Army, the University of Minnesota/Mayo/IBM Collaboration Seed Grant Program and Mayo Clinic. Co-authors of the PLoS One article are Sanjay Singh, Yang Gao, T. Leon Lassiter, and Rajesh Mishra, Ph.D., all of Mayo Clinic; and Kun Yan Zhu, Ph.D., of Kansas State University.
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