Trehalose metabolism in the blue crab Callinectes sapidus: isolation of multiple structural cDNA isoforms of trehalose-6-phosphate synthase and their expression in muscles.

Adult blue crab Callinectes sapidus exhibit behavioral and ecological dimorphisms: females migrating from the low salinity water to the high salinity area vs. males remaining in the same areas. The flesh basal muscle of the swimming paddle shows a dimorphic color pattern in that levator (Lev) and depressor (Dep) of females tend to be much darker than those of males, while both genders have the same light colored remoter (Rem) and promoter (Pro). The full-length cDNA sequence of four structural isoforms of trehalose-6-phosphate synthase (TPS) is isolated from chela muscles of an adult female, C. sapidus. Two isoforms of the C. sapidus TPS encode functional domains of TPS and trehalose-6-phosphorylase (TPP) in tandem as a fused gene product of Escherichia coli Ost A and Ost B. The other two isoforms contain only a single TPS domain. In both males and females, the darker (Lev+Dep) muscles exhibit greater amounts of trehalose, TPS and trehalase activities than the light colored (Rem+Pro). The fact that adult females show higher levels of trehalase activity in the basal muscles and of glucose in Lev+Dep than those of adult males suggests that there may be a metabolic dimorphism. Moreover, the involvement of trehalose in energy metabolism that was examined under the condition of strenuous swimming activity mimicked in adult females demonstrates the intrinsic trehalose metabolism in Lev+Dep, which subsequently results in hemolymphatic hyperglycemia and hyperlactemia. Our data support that trehalose serves as an additional carbohydrate source of hemolymphatic hyperglycemia in this species. Behavioral and ecological dimorphisms of C. sapidus adults may be supported by a functional dimorphism in energy metabolism.