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In this study, we analyzed Apis mellifera royal jelly proteome alterations induced by supplementation with different concentrations of dietary organic zinc (0, 25, 50, and 75 ppm). Proteins extracted from royal jelly were separated by electrophoresis and isoelectric focusing, and zinc-containing protein spots were identified by tandem mass spectrometry. Organic zinc-containing diets modified total royal jelly protein content and altered the expression of five major royal jelly proteins (MRJP1, MRJP2, MRJP3, MRJP5, and MRJP8). While the diet with the lowest tested zinc content (Zn25) increased total royal jelly protein content and expression of MRJP1, diets with higher zinc contents (Zn50 and Zn75) decreased MRJP expression. Our results demonstrate that important proteins and metabolic processes are modified in royal jelly produced by honey bees supplemented with different concentrations of organic zinc source, affecting nutrition and maintenance of colonies. [ABSTRACT FROM AUTHOR]

We investigated the effects of organic and inorganic zinc (Zn) supplementation on the morphology of mandibular glands in Apis mellifera L.. We randomly assigned 28 beehives to seven treatment groups (four beehives in each group) as follows: control (no Zn) and Zn organic or inorganic supplementation (25, 50, and 75 ppm organic or inorganic Zn, respectively). The inorganic source was Zn sulfate monohydrate (37% Zn) and the organic source was Zn-methionine (16% Zn), which were diluted in sugar syrup 1:1 (50% water and 50% sugar) and provided to the honey bees for 36 days. The morphology of the mandibular glands collected from 6-day-old nurse honey bees from each group was analysed after sectioning and visualizing the sections under a microscope. The results were compared using analysis of variance followed by Tukey's test. The area of the mandibular glands increased significantly in the treatments containing the organic Zn source and was higher in the 75 ppm treatment. The results from the inorganic Zn sources of 25 and 50 ppm were similar to those of the control; however, the 75 ppm treatment showed the worst glands development. Therefore, organic Zn supplementation in the feeding of honey bees, in the concentrations used in this study, positively modulated development of the mandibular glands. [ABSTRACT FROM AUTHOR]

In this study the effects of inorganic iron (Fe) supplementation on the morphology of mandibular glands in Apis mellifera were investigated. We randomly assigned 12 beehives to four treatment groups (with three hives in each group), as follows: Fe0 (no Fe supplementation), and Fe25, Fe50, and Fe100 (supplemented with 25, 50, and 100 ppm Fe, respectively). Ferrous sulfate heptahydrate (containing 33.10% Fe), diluted in sugar syrup (1:1 water and sugar), was used as the iron source, and the treatment was done for 3 months. The morphology of glands collected from six-day-old nurse bees from each group was analyzed after sectioning them and visualizing the sections under a microscope. The results were compared by ANOVA followed by the Tukey test (P < 0.05). The area and height of the secretory cells of mandibular glands were observed to be significantly reduced. We conclude that the supplementation of inorganic Fein the feed of bees, at concentrations used in this study negatively modulates their development. [ABSTRACT FROM AUTHOR]

This study assessed the effects of different protein levels on the development of the mandibular gland (MG) in six-day-old worker bees (Apis mellifera) during the dearth period. Twenty colonies were randomly assigned to one of four experimental diets containing 0%, 23%, 25%, or 27% crude protein (CP), with five replicates each. The experimental diets were composed of feed meal and honey sirup. Each colony was provided with 30 g of formulated feed every 3 days over a 36-day period. At the end of the experimental period, ten six-day-old worker bees were collected from each treatment for the morphological analysis of their MGs. The area of the MG was significantly larger in the bees fed protein-enriched feeds than in the controls. The height of the secretory cells in the MG was also significantly greater in all colonies fed protein-enriched feed than in the control group. However, the group that received the feed with 23% CP had significantly taller secretory cells than the other groups. Based on regression analysis, the ideal level of protein in the diet for the development of the MG was 22.2% CP. Thus, the use of protein-enriched feed promotes greater increases in the area and height of secretory MG cells in six-day-old honey bee workers. [ABSTRACT FROM AUTHOR]