µmol Effect of summer feeding on catalase and

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µmol Effect of summer feeding on catalase and ascorbate peroxidase activity in honey bee (Apis mellifera L. ) L. S. Yazlovytska, Е. O. Chunkivsky, R. A. Volkov Department of Molecular Genetics and Biothechnology, University of Chernivtsi, Ukraine Introduction In the middle of summer (July) honey bees often do not obtain sufficient amount of food in nature and require additional feeding. However, the physiological and biochemical consequences of the feeding still remain poorly understood. Especially, little is known about the possible effects on the activity of antioxidative enzymes, e. g. , catalase (CAT) and ascorbate peroxidase (APX), which are responsible for the scavenging of hydrogen peroxide and, therefore, are involved in the cell protection against different kinds of abiotic stress. The aim of our study was to evaluate the effect of summer feeding on the activity of CAT and APX in forager bees. Materials and methods The experimental colonies received additional feeding with 60% sucrose solution for 3 days. The activity of CAT and APX was measured (I) before, (II) at the 4 th and (III) at 11 th day of the experiment (Fig. 1). The enzyme activity was determined in tissues of the gut, head and thorax from forager bees. The body parts od the ten working bees were combined and used to prepare one extract. Activities of CAT and APX were measured by the methods of Aebi and Amako, respectively. The protein content was assayed according to the method proposed by Bradford. Statistical analysis was performed using the Kruskal–Wallis one-way analysis of variance by ranks. The significance was declared at P<0, 05. The stages to the selection of bees І – before of the experience ІІ – at the 4 th day of the experiment ІІІ – at the 11 th day of the experiment supernatant head torax (x 10) The activity of CAT and APX were measured The protein content was assayed gut Figure 1. Scheme of experimentation І – before of the experience µmol/min/mg prot ІІ – at the 4 th day of the experiment ІІІ – at the 11 th day of the experiment А В C - control colonies - experimental colonies Figure 2. The activity of CAT was determined in tissues of the head(A), thorax(B), and gut(C) from forager bees (Mediana; Segment: range of values) І – before of the experience µmol/min/mg prot ІІ – at the 4 th day of the experiment ІІІ – at the 11 th day of the experiment А В C - control colonies - experimental colonies Figure 3. The activity of APX was determined in tissues of the head(A), thorax(B), and gut(C) from forager bees (Mediana; Segment: range of values) Result and Conclusion It was found that the activity of CAT was about two orders of magnitude higher than the activity of APX. This indicates that in bees – like in other insects – CAT represents the main enzyme scavenging hydrogen peroxide where as APX plays an additional and probably specific role in cell protection. It was also found that the activity of CAT did not change significantly during our experiment in comparison of the experimental and control groups (Fig. 2). In contrast, the APX activity significantly increased in the experimental group on the 4 th day of additional feeding, whereas in the control group it remained unchanged in all body parts examined. Herein, the highest increase of APX activity was observed in the tissues of the gut, and the lowest – in the tissues of the thorax (Fig. 3). The lowest increase of the enzyme activity in the thoracal tissue may be explained by adverse weather conditions during our experiment that resulted in reduction of flying activity of the forager bees. The APX activity returned to its original level within a week after termination of summer feeding. Thus, APX may play an important role in limitation of oxidative damage in bees, which received additional feeding.

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