Regulation of soluble and membrane-bound trehalase activity and expression of the enzyme in the larval midgut of the bamboo borer Omphisa fuscidentalis

Possible involvement of proteinaceous and non-proteinaceous trehalase inhibitors in the regulation of hemolymph trehalose concentration in Bombyx mori

“…The alkaloids are absorbed into the hemolymph, indicating that an exogenous trehalase inhibitor may be involved in trehalose regulation in the hemolymph, although there is no data to support this view. In contrast, insects produce trehalase inhibitors, all of which are proteinaceous; these have been reported from the blowfly Phormia regina (Friedman, 1961), the American cockroach Periplaneta americana (Hayakawa et al, 1989), and O. fuscidentalis (Tatun et al, 2008b). In a preliminary study, we found trehalase inhibitor in the hemolymph of B. mori larvae.…”

“…This decrease may be due to soluble trehalase, which increases in activity on Day 5 and peaks on Day 6, together with a sharp decline in trehalose synthase activity before the onset of spinning (Hirano and Yamashita, 1983). Greater levels of ecdysteroids in the hemolymph on these days may up-regulate soluble trehalase gene expression followed by an increase in soluble trehalase activity, as demonstrated in O. fuscidentalis (Tatun et al, 2008b). The increased soluble trehalase activity may overcome inhibitor-P inhibition, causing the sharp decrease in trehalose concentration in conjunction with the cessation of sugar-mimic alkaloid consumption due to the cessation of feeding.…”

“…The regulation of dynamic changes in hemolymph trehalose concentration through larval and pupal periods may involve various factors: inhibitor-M and inhibitor-P; two types of trehalases and their sensitivities to the two inhibitors; expression of two trehalase genes, the soluble trehalase gene treh-1 and the membrane-bound trehalase gene treh-2 (Mitsumasu et al, 2006;Tatun et al, 2008b); and trehalose production by trehalose synthase. Among these factors, the identification of the inhibitor-P gene and regulation of its expression are necessary to better understand the regulatory mechanisms of hemolymph trehalose concentration.…”

“…Insects have either membrane-bound trehalase or both soluble and membrane-bound forms (Thompson, 2003). Both types are present in B. mori (Sumida and Yamashita, 1983;Su et al, 1993;Mitsumasu et al, 2005), the Eri silkworm Samia cynthia ricini (Hirayama et al, 2007), and the bamboo borer Omphisa fuscidentalis (Tatun et al, 2008b). In addition, the enzymatic activities of both trehalases change during growth and development (Yamashita et al, 1974;Tatun et al, 2008b), indicating that trehalase regulation is involved in the translocation of stored sugars from the hemolymph to the body fat and vice versa.…”

Comparison of gut morphology and distribution of trehalase activity in the gut of wood-feeding and fungus-growing termites (Isoptera: Termitidae)

“…crassus and B. prabhae. The high trehalase activity in the midgut must considered in terms of the activity recorded in the lumen of the midgut and in the haemocoel around the midgut (Mitsumasu et al, 2005;Tatun et al, 2008). The latter may serve to supply glucose to the gut cells for their basic energy requirements and to other tissues to be used in reproduction and colony defence (soldier caste).…”