Larval dietary wheat germ oil influences age-specific protein expression in adults of the oriental fruit fly

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

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2012
Publication Date: 2/8/2012
Citation: Chang, C.L., Coudron, T.A., Goodman, C.L., Stanley, D.W. 2012. Larval dietary wheat germ oil influences age-specific protein expression in adults of the oriental fruit fly. Journal of Insect Physiology. 58:690-698.

Interpretive Summary: The oriental fruit fly is a wide-spread pest of fruit and vegetable agriculture throughout the Pacific islands and tropical Asia. One of the approaches in managing this important pest is use of a sterile insect technique. This pest management strategy depends on the knowledge, facilities and funding to support mass-production of sterile adults. The sterile adults must be of high quality to ensure their ability to compete successfully for mates after their release in nature. One of the problems with mass rearing is the relative difficulty in controlling costs by switching dietary components as material costs rise and fall. We approached this problem by developing biochemical markers that can be used to quickly assess the ability of dietary components to produce high quality adult flies. This work reduces the cost of mass rearing Oriental fruit flies and directly benefits fruit and vegetable producers throughout the geographic range of flies. This work will be used by other researchers to discover biochemical markers for insect mass rearing programs globally.

Technical Abstract: Changes in essential dietary components alter global gene expression patterns in animals. We reported on a proteomics study designed to identify molecular markers of deficiencies in culture media developed for the oriental fruit fly, Bactrocera dorsalis. In that study, we found significant changes in expression of 70 proteins in adults of larvae reared on media lacking wheat germ oil (WGO). Of these, a gene encoding an insect chitin-binding protein was expressed at about 120-fold high levels in adult males reared on media supplemented with WGO compared to males reared in the absence of WGO. We inferred it may be feasible to develop the gene as a molecular marker of dietary lipid deficiency. The work was focused, however, on analysis of 11 day old adults. We have no information on expression of the chitin-biting protein, nor on any other proteins at other adult stages. In this paper, we address the idea that the whole animal proteome changes dynamically with age. We reared separate groups of fruit fly larvae on media with and without WGO supplementation and analyzed protein expression in adult males and females age 0, 4, 8, and 12 days old using 2D electrophoresis. Gel densitometry revealed significant increases(by = 2-fold) and decreases (by= 50%) in expression levels of 29 proteins in females and 10 in males. We identified these proteins by mass spectrometry on MALDI TOF/TOF and bioinformatic analyses of the protein sequences. Two proteins, peroxiredoxin (26-fold increase) and vitellogenin 1 (15-fold increase) increased in expression in day 8 females. The key finding is that we recorded these increases mostly in day 8 females. We infer that the fruit fly proteome changes with adult age. The natural changes in proteome with adult age is a crucial aspect of developing these and other proteins into molecular markers of lipid deficiency in fruit flies and possibly other insect species.