Intraspecific Variability in Proteomic Profiles and Biological Activities of the Honey Bee Hemolymph

Abstract

Pollinator declines have raised major concerns for the maintenance of biodiversity and food security, calling for a better understanding of environmental factors that affect their health. Here we used hemolymph analysis to monitor the health status of Western honey bees Apis mellifera. We evaluated the intraspecific proteomic variations and key biological activities of the hemolymph of bees collected from four Egyptian localities characterized by different food diversities and abundances. Overall, the lowest protein concentrations and the weakest biological activities (cytotoxicity, antimicrobial and antioxidant properties) were recorded in the hemolymph of bees artificially fed sucrose solution and no pollen. By contrast, the highest protein concentrations and biological activities were recorded in bees that had the opportunity to feed on various natural resources. While future studies should expand comparisons to honey bee populations exposed to more different diets and localities, our results suggest hemolymph samples can be used as reliable indicators of bee nutrition.

Keywords: anticancer; antimicrobial; antioxidant; honeybee; proteome.

Figure 1

Protein concentrations in mg/mL for honey bee hemolymph extracted in PBS or DMSO where (A): bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine. Bars and error bars represent the mean values ±SE obtained from triplicate measurements. Different letters above bars indicate significant differences (Tukey’s test, p < 0.05): uppercase letters show comparisons across PBS dissolved samples; lowercase letters show comparisons across DMSO dissolved samples.

Figure 2

Photos of SDS-PAGE gels for honey bee hemolymph extracts dissolved in PBS (A) or DMSO (B) where (A): bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine. M: marker. The molecular weights of the proteins and their amounts are expressed by the color intensity of the protein bands.

Figure 3

Effects of honey bee hemolymph extracts dissolved at different concentrations in PBS or DMSO on human cancer cell proliferation (HepG2 and HeLa), where (A): bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine.

Figure 4

IC₅₀ in microgram/mL of hemolymph extracts of honey bees dissolved in PBS or DMSO against Hepg2 and HeLa cell lines, where (A): bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine. Bars and error bars represent the mean values ± SE obtained from triplicate measurements. Different letters above bars indicate significant differences (Tukey’s test, p < 0.05): uppercase letters show comparisons across PBS dissolved samples; lowercase letters show comparisons across DMSO dissolved samples.

Figure 5

Antimicrobial activity of honey bee hemolymph extracted in PBS or DMSO against E. coli, where (A): bees from Port Said, (B1,B2): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine.

Figure 6

DPPH radical scavenging activity of honey bee hemolymph extracted in PBS or DMSO where (A): Bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine. Bars and error bars represent the mean values ± SEM obtained from triplicate measurements. Different letters above bars indicate significant differences (Tukey’s test, p < 0.05): uppercase letters show comparisons across PBS dissolved samples; lowercase letters show comparisons across DMSO dissolved samples.

Figure 7

Hemolytic activity of honey bee hemolymph extracted in PBS or DMSO at different concentrations against erythrocytes where (A): bees from Port Said, (B): bees from Ismailia governorate, (C): bees from Suez governorate, (D): bees from Saint Catherine.