Toxicology of cupric salts on honeybees IV — gluconate and sulfate action on hemolymph trehalose activity in vivo and in vitro
✍ Scribed by Nectoux, M. ;Bounias, M. ;Popeskovic, D.
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 682 KB
- Volume
- 10
- Category
- Article
- ISSN
- 0887-2082
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✦ Synopsis
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 Vawoa jacobsoni, a parasitic mite of hives. The simultaneous injection to bees of 0.3 pM BAYg5421 (an inhibitor of a-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 cooperativity than crude extract. Form I showed almost no susceptibility to either cupric derivatives, which indicated form I1 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.