Title: DIFFERENTIAL GENE EXPRESSION IN PERILLUS BIOCULATUS NYMPHS FED A SUBOPTIMAL ARTIFICIAL DIET Authors
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2006
Publication Date: June 1, 2006
Citation: Yocum, G.D., Coudron, T.A., Brandt, S.L. 2006. Differential gene expression in Perillus bioculatus nymphs fed a suboptimal artificial diet. Journal of Insect Physiology. 52(6):586-592. Interpretive Summary: One of the limiting factors for the broader adoption of biocontrol as a pest management approach is the cost of the beneficial insects, which can far exceed that of chemical control. An optimized artificial diet can greatly reduce the cost of producing beneficial insects. The current strategy for diet development is to measure some physiological or biochemical parameter in order to quantify the effect of changes in the diet formulation on the insect’s performance. Often the selection of changes is based on biochemical information obtained from other insects reared on other diets. This endeavor is time-consuming, taking years to decades to perfect a diet, and many attempts end in failure. What is needed to accelerate diet development is a method to directly measure multiple diet deficiencies through a feedback mechanism using the diet and insect under study. Nutrigenomics, the examination of how nutrition affects gene expression patterns within the insect under study, offers not only a means to quantify an insect’s response to a diet reformulation but also provides information on diet limitations. Using a nutrigenomics approach we have developed four dietary-regulated molecular markers from third instar nymph of Perillus bioculatus that indicate diet quality by their level of expression. The significant impact of this investigation is as follows: 1) We demonstrated that diets can be evaluated at an early developmental stage – as opposed to the current practice of using adults – thereby greatly decreasing the screening time for new diet formulations. 2) We established key components of proper experimental design essential for future nutrigenomic experiments.
Technical Abstract: Fragments of two artificial diet up-regulated and two prey up-regulated transcripts were isolated from the predatory Pentatomid Perillus bioculatus using suppression subtractive hybridization. A BlastX search found similarities for two diet-upregulated clones, i.e., the tyrosine-3-monooxygenase gene and the gene for the chitin binding protein, Gasp. The probe generated from the tyrosine-3-monooxygenase clone hybridized to two transcripts 2.3 and 1.2 kb in size. The two transcripts were differentially regulated: the 2.3 kb transcript was upregulated in the first and late third instar diet-fed nymphs, whereas the 1.2 kb transcript was upregulated in the second and early third instar diet-fed nymphs. The Gasp gene was upregulated in late third instar nymphs. A positive correlation was found between levels of expression of the isolated genes and the number of generations the insects had been reared on the artificial diet.