The Molecular Characterization and Gene Expressions of Trehalase in Bumblebee, Bombus lantschouensis (Hymenoptera: Apidae)

Abstract

Trehalose provides the main energy source for the physiological activities of insects, especially in adverse conditions. Trehalase is the only enzyme that hydrolyzes trehalose, therefore it is important to clarify the distribution and expression of trehalase under adverse conditions such as high temperatures and starvation. Here, we have cloned the trehalase genes and investigated their expression in different tissues, at multiple development stages, and with the treatments of high temperature and starvation in Bombus lantschouensis, which is considered to be one of the most commercially viable native species in China. The results suggest that the membrane-bound (BlTre-2) cDNA has an open reading frame of 1986 nucleotides, which encodes a protein of 662 amino acids, and two putative transmembrane domains. qRT-PCR analysis indicated that BlTre-2 was expressed in 10 tissues and at nine development stages, with the highest expression in general in 30-day-old workers, and in ovarian tissue in particular. The expression of BlTre-1 for 15-day-old workers which were exposed to a pre-treatment of 45°C increased over the first 5 h and subsequently decreased over time. In contrast the expression of BlTre-2 consistently decreased over time. The highest expression levels of BlTre-1 and BlTre-2 were observed the newly emerged adult workers when starved for 16-20 h. These results indicate that BlTre-2 may be part of the carbohydrate metabolism of the bumblebee, and that BlTre-1 is a key gene regulating energy metabolism and providing trehalose when exposed to a high temperature. Both BlTre-1 and BlTre-2 may balance trehalose and provide energy when B. lantschouensis is starved.