Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2016
Publication Date: 2/15/2017
Publication URL: http://handle.nal.usda.gov/10113/5678122
Citation: Perkin, L.C., Elpidina, E.N., Oppert, B.S. 2017. RNA interference and dietary inhibitors induce a similar compensation response in Tribolium castaneum larvae. Insect Molecular Biology. 26(1):35-45. doi:10.1111/imb.12269.
Interpretive Summary: The red flour beetle (RFB) is a major stored product pest responsible for great economic loss worldwide. The RFB has a specialized gut, arranged to efficiently breakdown grain and cereal products. We used a molecular technique called RNA interference (RNAi) to reduce the expression of a gene responsible for the most highly expressed digestive enzyme in feeding stages of the beetle. Expression of this gene, as well as all other genes, was measured using another molecular technique, RNA-seq. We found that expression of the major gut enzyme gene was significantly reduced, but the RFB gut compensates for the loss by increasing the expression of genes that encode other gut enzymes. This is similar to the response of larvae fed general enzyme inhibitors. We also found that targeting a particular region of the gene with RNAi caused the most reduced expression and changed the expression of fewer genes overall. This information adds to the body of literature on the complex RFB gut, and it also guides future directions towards new pest control strategies.
Technical Abstract: RNAi uses the host’s cellular machinery to degrade and reduce gene expression and has become a way to functionally test a gene of interest. RNAi technology is being used to develop pest control strategies in the agricultural community because it can be applied to non-model systems. However, there has been a range of success in achieving reduced gene expression. In this manuscript, we attempt to use RNAi to reduce the expression of a major gut cysteine cathepsin L gene in the genetic coleopteran model Tribolium castaneum by two different methods (micro-injection and oral), using dsRNA constructs targeting different regions of the gene (3’, middle, and 5’). We find different magnitudes of change between methods, but in all cases the expression of the gene was increased in response to dsRNA, although not statistically significant (p<0.05). The results are consistent with previous T. castaneum studies that target gut cathepsins with inhibitors. We suggest the expression of the gene and the biology of the system is maintained by feedback mechanisms to preserve homeostasis of digestion. In addition, we discuss the difficulties of successful oral RNAi experiments in T. castaneum.