Effect of the alpha-glucosidase inhibitor, bromoconduritol, on carbohydrate metabolism in the silverleaf whitefly, Bemisia argentifolii.

The involvement of alpha-glucosidase in the partitioning of ingested sucrose between excretion and incorporation was investigated in the silverleaf whitefly (Bemisia argentifolii). Approximately half of the alpha-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 alpha-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 alpha-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 alpha-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 alpha-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.

[1]  Salvucci,et al.  Effects of temperature and dietary sucrose concentration on respiration in the silverleaf whitefly, Bemisia argentifolii. , 2000, Journal of insect physiology.

[2]  Salvucci.  Sorbitol accumulation in whiteflies: evidence for a role in protecting proteins during heat stress. , 2000, Journal of thermal biology.

[3]  A. Douglas,et al.  Living on a high sugar diet: the fate of sucrose ingested by a phloem-feeding insect, the pea aphid Acyrthosiphon pisum. , 2000, Journal of insect physiology.

[4]  M. Salvucci,et al.  Effect of high temperature on the metabolic processes affecting sorbitol synthesis in the silverleaf whitefly, Bemisia argentifolii. , 1999, Journal of insect physiology.

[5]  A. Dixon,et al.  Dietary sucrose and oligosaccharide synthesis in relation to osmoregulation in the pea aphid, Acyrthoslphon pisum , 1997 .

[6]  D. Hendrix,et al.  Diglucomelezitose, a Novel Pentasaccharide in Silverleaf Whitefly Honeydew , 1997 .

[7]  M. Salvucci,et al.  Effect of sucrose concentration on carbohydrate metabolism in Bemisia argentifolii : biochemical mechanism and physiological role for trehalulose synthesis in the silverleaf whitefly , 1997 .

[8]  Wilkinson,et al.  Honeydew sugars and osmoregulation in the pea aphid Acyrthosiphon pisum , 1997, The Journal of experimental biology.

[9]  J. Baker,et al.  Compartmentalization of digestion , 1996 .

[10]  Karl Crailsheim,et al.  Lipid and sugar absorption , 1996 .

[11]  W. Terra,et al.  An α-glucosidase from perimicrovillar membranes of Dysdercus peruvianus (Hemiptera: Pyrrhocoridae) midgut cells. Purification and properties , 1995 .

[12]  D. Hendrix,et al.  Bemisiose: an unusual trisaccharide in Bemisia honeydew. , 1992, Carbohydrate research.

[13]  P. Calvo,et al.  Effect of bromoconduritol on glucosidase II from rat liver. A new kinetic model for the binding and hydrolysis of the substrate. , 1993, European journal of biochemistry.

[14]  H. Heldt,et al.  Phloem Transport of Amino Acids in Relation to their Cytosolic Levels in Barley Leaves. , 1992, Plant physiology.

[15]  T. Mittler,et al.  Effects of dietary sucrose concentration on aphid honeydew carbohydrate levels and rates of excretion , 1991 .

[16]  D. N. Byrne,et al.  Carbohydrate and amino acid composition of phloem sap and honeydew produced by Bemisia tabaci , 1990 .

[17]  F. S. Walters,et al.  Sucrose-dependent increase in oligosaccharide production and associated glycosidase activities in the potato aphid Macrosiphum euphorbiae (Thomas) , 1988 .

[18]  D. B. Fisher,et al.  Accumulation and Conversion of Sugars by Developing Wheat Grains : VI. Gradients Along the Transport Pathway from the Peduncle to the Endosperm Cavity during Grain Filling. , 1986, Plant physiology.

[19]  P. Cheetham.  The extraction and mechanism of a novel isomaltulose-synthesizing enzyme from Erwinia rhapontici. , 1984, The Biochemical journal.

[20]  D. B. Fisher,et al.  Osmoregulation by the aphid Myzus persicae: A physiological role for honeydew oligosaccharides , 1984 .

[21]  R. Schwarz,et al.  Inhibition of formation of complex oligosaccharides by the glucosidase inhibitor bromoconduritol. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[22]  Y. Fujiki,et al.  Isolation of intracellular membranes by means of sodium carbonate treatment: application to endoplasmic reticulum , 1982, The Journal of cell biology.

[23]  M. M. Bradford.  A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. , 1976, Analytical biochemistry.

[24]  R. E. Huber.  The purification and study of a honey bee abdominal sucrase exhibiting unusual solubility and kinetic properties. , 1975, Archives of Biochemistry and Biophysics.

[25]  G. Legler,et al.  Untersuchungen zum Wirkungsmechanismus glykosidspaltender Enzyme, VII. Funktionelle Gruppen am aktiven Zentrum einer α-Glucosidase aus Saccharomyces cerevisiae , 1973 .