Abstract
This work verifies that amitraz and oxalic acid treatment affect honeybee cuticle proteolytic enzymes (CPE). Three bee groups were monitored: oxalic acid treatment, amitraz treatment, control. Electrophoresis of hydrophilic and hydrophobic CPE was performed. Protease and protease inhibitor activities (in vitro) and antifungal/antibacterial efficiencies (in vivo), were analyzed. Amitraz and oxalic acid treatment reduced hydrophobic, but did not affect hydrophilic, protein concentrations and reduced both hydrophilic and hydrophobic body surface asparagine and serine protease activities in relation to most substrates and independently of pH. The activities of natural cuticle inhibitors of acidic, neutral, and alkaline proteases were suppressed as a result of the treatments, corresponding with reduced antifungal and antibacterial activity. Electrophoretic patterns of low-, medium-, and high-molecular-weight proteases and protease inhibitors were also affected by the treatments.
Highlights
Proteolytic enzymes are active in extra- and intracellular proteolysis and take part in such processes as zymogene activation, the release of hormones and active proteins from their precursors, transport through the cell membranes, witin-cell complex protein processing and receptor activation [1±5]
Asparagine and serine proteases, but no thiolic proteases or metal-proteases, were detected on the apian cuticles because proteolytic activity was identified in the case of pepstatin-A and phenylmethylsulfonyl fluoride (PMSF) but was not observed in relation to iodoacetamide or o-phenanthroline
Amitraz and oxalic acid treatments increased the number of acidic and alkaline protease and neutral hydrophobic protease bands, and reduced the number of bands associated with neutral hydrophilic proteases in electrophorograms (Table 2)
Summary
Proteolytic enzymes (proteases and protease inhibitors) are active in extra- and intracellular proteolysis and take part in such processes as zymogene activation, the release of hormones and active proteins from their precursors, transport through the cell membranes, witin-cell complex protein processing and receptor activation [1±5]. A significant component of the resistance is the layer of active cuticle surface proteins that protect the honeybee against pathogen invasion [9,10]. This proteolytic system may be important for a better understanding of CCD etiology. Polish apiarists report during their meeting that amitraz and oxalic acid may promote the development of other diseases, especially diseases caused by fungi (mycosis). This could be connected with the suppression of the body surface proteolytic system. Bees were examined just before, and two weeks after, the treatments
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