Characterization of putative soluble and membrane-bound trehalases in a hemipteran insect, Nilaparvata lugens

Trehalose is the main blood sugar of insects, and the enzyme trehalase is involved in energy metabolism and controlling trehalose levels in cells. Two forms (soluble and membrane-bound) of trehalase and the corresponding genes (NITre-1 and NITre-2) were identified from the brown planthopper, Nilaparvata lugens. Both NITre-1 and NITre-2 contain trehalase signature motifs, and NITre-2 contains a putative transmembrane domain. Comparison of trehalase activity and gene mRNA level at different developmental stages, or following application of 20-hydroxyecdysone (20E), suggests that NITre-1 and NITre-2 encode a soluble trehalase and a membrane-bound trehalase respectively. Soluble trehalase activity accounted for the majority of total trehalas6 activity in N. lugens. Only soluble trehalase activity and NITre-1 mRNA level could be induced by 20E. Additionally, only soluble trehalase activity was significantly higher in macropterous individuals than in brachypterous morphs. These results indicate that only soluble trehalase is differentially expressed between macropterous and brachypterous individuals and is more responsive to hormone stimulus. (C) 2009 Elsevier Ltd. All rights reserved.