Microarray analysis reveals strategies of Tribolium castaneum larvae to compensate for cysteine and serine protease inhibitors

Authors: Oppert, Brenda; ELPIDINA, ELENA - Moscow State University; Toutges, Michelle; MAZUMDAR-LEIGHTON, SUE - University Of Delhi

Submitted to: Comparative Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2010
Publication Date: 12/1/2010
Citation: Oppert, B.S., Elpidina, E.N., Toutges, M.J., Mazumdar-Leighton, S. 2010. Microarray analysis reveals strategies of Tribolium castaneum larvae to compensate for cysteine and serine protease inhibitors. Comparative Biochemistry and Physiology. 5(4):280-287. doi: http://dx.doi.org/10.106/j.cbd.2010.08.001.

Interpretive Summary: Previously, our studies determined that flour beetle larvae respond to dietary inhibitors by shifting from one class of proteases to another. This response is problematic if cereal inhibitors are to be incorporated into IPM strategies for storage pest control. To study this at the gene level, whole-genome microarrays were used to evaluate the inhibitor response. The data demonstrated that the response by beetle larvae to dietary inhibitors involves a complicated adjustment of gene expression. However, the study also provided clues as to how to better utilize inhibitors for beetle pest control. Therefore, effective control of beetles may soon be possible with a strategy that can anticipate beetle responses to inhibitors.

Technical Abstract: Microarrays containing Tribolium castaneum whole-genome sequences were developed to study the transcriptome response of T. castaneum larvae to dietary protease inhibitors. In larvae fed diets containing 0.1% of the cysteine protease inhibitor E-64 alone or in combination with 5.0% of the serine protease-specific soybean trypsin inhibitor (STI), 23 and 21 genes were significantly down regulated, respectively, including protease and exopeptidase genes, and also genes involved in protein translation, energy production, cell signaling and communication, and ion transport. Four down regulated transcripts, genes encoding alkaline phosphatase, glutamate transporter, carbonate dehydratase, and perlecan, were common to larvae subjected to either E-64 or E-64 plus STI treatments. In larvae fed diets containing 5.0% STI, only two genes were significantly down regulated. Although not statistically significant, some cathepsin L and B genes were down regulated in response to E-64 or STI. In STI-treated larvae, the down regulation of serine protease genes was compensated by up regulation of alternative serine protease genes, mostly chymotrypsin. An increase in protease homologs in response to inhibitors suggests a role in protecting larvae from the negative effects of inhibitor treatments. In larvae fed combination treatments, most protease genes were down regulated and none were up regulated, supporting the hypothesis that dietary treatments containing inhibitor combinations prevent compensation responses by insects.