Toxicology of cupric salts on honeybees. IV--Gluconate and sulfate action on hemolymph trehalose activity in vivo and in vitro.
A biphasic increase of hemolymph glucose levels was observed following injection to bees of cupric gluconate or sulfate, both potent agents for the control of Varroa jacobsoni, a parasitic mite of hives. The simultaneous injection to bees of 0.3 microM BAYg5421 (an inhibitor of alpha-glucosidases) quenched the response, suggesting a direct effect of 2 nmol/bee cupric ions on trehaloses' activity. One nanomol of injected cupric gluconate increased the trehalose (Tre) activity by 233% in crude hemolymph extracts at 1 mM trehalose concentration, and exhibited biphasic dose-related effects with a maximum 15% increase at 0.5 mM cupric ion and a stabilized 20% inhibition from 4 mM, regardless of the anionic moiety. Upon partial purification of the enzyme complex, two fractions (FI = 75% and FII = 25% of total activity) were isolated that exhibited, respectively, less and more marked positive cooperatively than crude extract. Form I showed almost no susceptibility to either cupric derivatives, which indicated form II as the most likely target, with 68% and 72% increases with 0.25 mM cupric sulfate and 0.5 mM cupric gluconate, in presence of 16 mM trehalose.
Nectoux
M
M
INRA Phytopharmacy Department, University of Avignon, France.
Bounias
M
M
Popeskovic
D
D
D020909:Acarbose; D000818:Animals; D001516:Bees / Q000187:drug effects / Q000502:physiology*; D003300:Copper / Q000633:toxicity*; D019327:Copper Sulfate; D005260:Female; D005942:Gluconates / Q000633:toxicity*; D006458:Hemolymph / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007700:Kinetics; D012044:Regression Analysis; D014199:Trehalose / Q000378:metabolism*; D014312:Trisaccharides / Q000494:pharmacology
D005942:Gluconates; D007004:Hypoglycemic Agents; D014312:Trisaccharides; D003300:Copper; D014199:Trehalose; D019327:Copper Sulfate; D020909:Acarbose