Identification and analysis of up-regulated proteins in Lissorhoptrus oryzophilus adults for rapid cold hardening.

Rapid cold hardening (RCH) is a central physiological adaptation in which brief chilling significantly enhances the cold tolerance ability of insects. However, the mechanism of rapid cold stress response remains unknown for rice water weevils. To elucidate the mechanism, a comparative proteomic analysis was applied with two-dimensional gel electrophoresis (2-DE) between RCH and control treatment samples. A total of 21 protein spots were found to be up-regulated in rice water weevil adults for the RCH condition. As an initial work, 16 of these proteins were identified using MALDI TOF/TOF MS. In addition, the expression patterns of 9 proteins (including 2 HSPs that were not identified in the 2-DE experiment) were confirmed by qPCR analysis. Using the geneMANIA app in cytoscape, we constructed a protein-protein interaction network analysis of these up-regulated proteins. Gene ontology (GO) function annotation shows that a "response to heat process," including 6 HSPs, was related to the identified proteins. These up-regulated, RCH responsive proteins could possibly serve as potential biomarkers to study the molecular mechanisms of the L. oryzophilus response to cold stress.