Integrated proteomic and metabolomic analysis of larval brain associated with diapause induction and preparation in the cotton bollworm, Helicoverpa armigera.

Diapause is a developmental arrest that allows an organism to survive unfavorable environmental conditions and is induced by environmental signals at a certain sensitive developmental stage. In Helicoverpa armigera, the larval brain receives the environmental signals for diapause induction and then regulates diapause entry at the pupal stage. Here, combined proteomic and metabolomic differential display analysis was performed on the H. armigera larval brain. Using two-dimensional electrophoresis, it was found that 22 proteins were increased and 27 proteins were decreased in the diapause-destined larval brain, 37 of which were successfully identified by MALDI-TOF/TOF mass spectrometry. RT-PCR and Western blot analyses showed that the expression levels of the differentially expressed proteins were consistent with the 2-DE results. Furthermore, a total of 49 metabolites were identified in the larval brain by GC-MS analysis, including 4 metabolites at high concentrations and 14 metabolites at low concentrations. The results gave us a clue to understand the governing molecular events of the prediapause phase. Those differences that exist in the induction phase of diapause-destined individuals are probably relevant to a special memory mechanism for photoperiodic information storage, and those differences that exist in the preparation phase are likely to regulate accumulation of specific energy reserves in diapause-destined individuals.