Dietary wheat germ oil influences gene expression in larvae and eggs of the oriental fruit fly

Authors: Coudron, Thomas; Chang, Chiou; Goodman, Cynthia; Stanley, David

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2010
Publication Date: 2/4/2011
Citation: Coudron, T.A., Chang, C.L., Goodman, C.L., Stanley, D.W. 2011. Dietary wheat germ oil influences gene expression in larvae and eggs of the oriental fruit fly. Archives of Insect Biochemistry and Physiology. 76:67-82.

Interpretive Summary: A sterile insect technique is being used to control the oriental fruit fly, which is a pest capable of causing extensive damage to fruit production. The technique requires rearing large numbers of healthy fruit flies prior to sterilization and release. These insects are reared on an artificial diet. However, formulation of a nutritional and environmentally friendly diet has been a consistent challenge. This study illustrated the benefits of a new research tool, proteomics, to improve diet formulation and learn about the affect of sub-optimal diets on the health and performance of fruit flies reared on artificial diets. An analysis of insects reared on two diets differing in lipid content revealed significant differences in gene expression in immature and egg stages of the fruit fly. Further, the association of these genes with fruit fly metabolism revealed a nutritional role of the dietary lipids in the health and performance the fruit fly. Knowing the role of dietary lipids in fruit fly metabolism will assist researchers and insectaries in the production of high quality fruit flies which will improve the control of the pest with sterile insect techniques.

Technical Abstract: Changes in animal nutrition, particularly essential dietary components, alter global gene expression patterns. Our goal is to identify molecular markers that serve as early indicators of the quality of insect culture media. Markers of deficient culture media will increase the efficiency of developing optimal systems for mass rearing beneficial insects and some pest species because decisions on culture media quality can be made without waiting through one or several life cycles. The objective of our current study is to discover molecular markers of essential dietary lipid deficiency in the oriental fruit fly, Bactrocera dorsalis. We reared groups of fruit flies separately on media either devoid of, or supplemented with, wheat germ oil and analyzed gene expression in third instar larvae and F1 eggs. We analyzed egg and larval proteins on 2D-electrophoresis. Gel densitometry revealed significant changes in expression levels of genes encoding 8 proteins in larvae and 23 proteins in eggs. We identified these proteins by mass spectrometry on MALDI TOF/TOF and bioinformatic analyses of the protein sequences. Among these, we identified one gene encoding receptor of activated C Kinase 1 (RACK1) that increased in expression by 6.8-fold in eggs from adults reared on media supplemented with wheat germ oil. RACK1 is an essential component of at least three intracellular signal transduction pathways, making it a good candidate molecular marker of lipid deficiency in fruit flies and possibly many other insect species.