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Effect of the α‐glucosidase inhibitor, bromoconduritol, on carbohydrate metabolism in the silverleaf whitefly, Bemisia argentifolii
Author(s) -
Salvucci Michael E.
Publication year - 2000
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/1520-6327(200011)45:3<117::aid-arch3>3.0.co;2-t
Subject(s) - biology , sucrose , carbohydrate , biochemistry , excretion , metabolism , whitefly , hexokinase , glucosidases , enzyme , botany , glycolysis
The involvement of α‐glucosidase in the partitioning of ingested sucrose between excretion and incorporation was investigated in the silverleaf whitefly ( Bemisia argentifolii ). Approximately half of the α‐glucosidase activity in adult whiteflies was soluble and the remainder was associated with membranes. In contrast, almost all of the trehalulose synthase was membrane‐associated. Isoelectric focusing revealed that soluble and membrane‐associated α‐glucosidases were each composed of several isozymes in the pH 5 to 6.5 range, but the distribution of activity among the various isozymes was different. Bromoconduritol, an inhibitor of glucosidases, inhibited trehalulose synthase and α‐glucosidase activities in whitefly extracts. Inhibition was greatest when bromoconduritol was incubated with extracts prior to the addition of sucrose, consistent with the irreversible nature of this inhibitor. Addition of bromoconduritol to artificial diets decreased the extractable trehalulose synthase and α‐glucosidase activities by about 30 and 50%, respectively. Ingestion of bromoconduritol reduced the amount of carbohydrate excreted by about 80% without changing the distribution of the major honeydew sugars or causing an increase in the proportion of sucrose that was excreted. Ingestion of bromoconduritol did not affect respiration, the content and distribution of soluble carbohydrates in whitefly bodies, or the conversion of labeled sucrose into glucose, trehalose and isobemisiose. The results indicate that partitioning of ingested carbon between excretion and metabolism in whiteflies is highly regulated, probably involving multiple forms of α‐glucosidase that facilitate a separation of the processes involved in the metabolic utilization of sucrose from those involved in excretion of excess carbohydrate. Arch. Insect Biochem. Physiol. 45:117–128, 2000. Published 2001 Wiley‐Liss, Inc.