Proteomics Improves the New Understanding of Honeybee Biology

The role of the veterinary diagnostic toxicologist in apiary health

Susceptibility of individuals and groups to toxicants depends on complex interactions involving the host, environment, and other exposures. Apiary diagnostic investigation and honey bee health are truly population medicine: the colony is the patient. Here we provide basic information on the application of toxicology to the testing of domestic honey bees, and, in light of recent research, expand on some of the challenges of interpreting analytical chemistry findings as they pertain to hive health. The hive is an efficiently organized system of wax cells used to store brood, honey, and bee bread, and is protected by the bee-procured antimicrobial compound propolis. Toxicants can affect individual workers outside or inside the hive, with disease processes that range from acute to chronic and subclinical to lethal. Toxicants can impact brood and contaminate honey, bee bread, and structural wax. We provide an overview of important natural and synthetic toxicants to which honey bees are exposed; behavioral, husbandry, and external environmental factors influencing exposure; short- and long-term impacts of toxicant exposure on individual bee and colony health; and the convergent impacts of stress, nutrition, infectious disease, and toxicant exposures on colony health. Current and potential future toxicology testing options are included. Common contaminants in apiary products consumed or used by humans (honey, wax, pollen), their sources, and the potential need for product testing are also noted.

Therapeutic Potential of Bee and Scorpion Venom Phospholipase A2 (PLA2): A Narrative Review

Venomous arthropods such as scorpions and bees form one of the important groups with an essential role in medical entomology. Their venom possesses a mixture of diverse compounds, such as peptides, some of which have toxic effects, and enzymatic peptide Phospholipase A2 (PLA2) with a pharmacological potential in the treatment of a wide range of diseases. Bee and scorpion venom PLA2 group III has been used in immunotherapy, the treatment of neurodegenerative and inflammatory diseases. They were assessed for antinociceptive, wound healing, anti-cancer, anti-viral, anti-bacterial, anti-parasitic, and anti-angiogenesis effects. PLA2 has been identified in different species of scorpions and bees. The anti-leishmania, anti-bacterial, anti-viral, and anti-malarial activities of scorpion PLA2 still need further investigation. Many pieces of research have been stopped in the laboratory stage, and several studies need vast investigation in the clinical phase to show the pharmacological potential of PLA2. In this review, the medical significance of PLA2 from the venom of two arthropods, namely bees and scorpions, is discussed.

Multifunctionality and intrinsic disorder of royal jelly proteome

Royal Jelly (RJ) is a gelatinous white-yellowish fluid, possessing a sour taste and a slight phenolic smell that is secreted by the hypopharyngeal and mandibular salivary glands of the nurse honeybees, and is used in nutrition of larvae and adult queens. Similar to other substances associated with the activities of honeybees, RJ not only contains nutritive components, such as carbohydrates, proteins, peptides, lipids, vitamins, and mineral salts, but also represents a natural ingredient with cosmetic and health-promoting properties. RJ is characterized by remarkable multifunctionality, possessing numerous biological activities. Although this multifunctionality of RJ can be considered as a consequence of its complex nature, many proteins and peptides in RJ are polyfunctional entities themselves. In this article, we show that RJ proteins contain different levels of intrinsic disorder, have sites of post-translational modifications, can be found in multiple isoforms, and many of them possess disorder-based binding sites, suggesting that the conformational ensembles of the RJ proteins might undergo change as a result of their interaction with specific binding partners. All these observations suggest that the multifunctionality of proteins and peptides from RJ is determined by their structural heterogeneity and polymorphism, and serve as an illustration of the protein structure-function continuum concept.

Novel Insight Into the Development and Function of Hypopharyngeal Glands in Honey Bees

Hypopharyngeal glands (HGs) are the most important organ of hymenopterans which play critical roles for the insect physiology. In honey bees, HGs are paired structures located bilaterally in the head, in front of the brain between compound eyes. Each gland is composed of thousands of secretory units connecting to secretory duct in worker bees. To better understand the recent progress made in understanding the structure and function of these glands, we here review the ontogeny of HGs, and the factors affecting the morphology, physiology, and molecular basis of the functionality of the glands. We also review the morphogenesis of HGs in the pupal and adult stages, and the secretory role of the glands across the ages for the first time. Furthermore, recent transcriptome, proteome, and phosphoproteome analyses have elucidated the potential mechanisms driving the HGs development and functionality. This adds a comprehensive novel knowledge of the development and physiology of HGs in honey bees over time, which may be helpful for future research investigations.

New Insights into the Biological and Pharmaceutical Properties of Royal Jelly

Royal jelly (RJ) is a yellowish-white and acidic secretion of hypopharyngeal and mandibular glands of nurse bees used to feed young worker larvae during the first three days and the entire life of queen bees. RJ is one of the most appreciated and valued natural product which has been mainly used in traditional medicines, health foods, and cosmetics for a long time in different parts of the world. It is also the most studied bee product, aimed at unravelling its bioactivities, such as antimicrobial, antioxidant, anti-aging, immunomodulatory, and general tonic action against laboratory animals, microbial organisms, farm animals, and clinical trials. It is commonly used to supplement various diseases, including cancer, diabetes, cardiovascular, and Alzheimer's disease. Here, we highlight the recent research advances on the main bioactive compounds of RJ, such as proteins, peptides, fatty acids, and phenolics, for a comprehensive understanding of the biochemistry, biological, and pharmaceutical responses to human health promotion and life benefits. This is potentially important to gain novel insight into the biological and pharmaceutical properties of RJ.

Systematic identification of circular RNAs and corresponding regulatory networks unveil their potential roles in the midguts of eastern honeybee workers

Currently, knowledge of circular RNAs (circRNAs) in insects including honeybee is extremely limited. Here, differential expression profiles and regulatory networks of circRNAs in the midguts of Apis cerana cerana workers were comprehensively investigated using transcriptome sequencing and bioinformatics. In total, 9589 circRNAs (201-800 nt in length) were identified from 8-day-old and 11-day-old workers' midguts (Ac1 and Ac2); among them, 5916 (61.70%) A. cerana cerana circRNAs showed conservation with our previously indentified circRNAs in Apis mellifera ligucstica workers' midguts (Xiong et al., Acta Entomologica Sinica 61:1363-1375, 2018). Five circRNAs were confirmed by RT-PCR and Sanger sequencing. Interestingly, novel_circ_003723, novel_circ_002714, novel_circ_002451, and novel_circ_001980 were highly expressed in both Ac1 and Ac2. In addition, the source genes of circRNAs were involved in 34 GO terms including organelle and cellular process and 141 pathways such as endocytosis and Wnt signaling pathway. Moreover, 55 DEcircRNAs including 34 upregulated and 21 downregulated circRNAs were identified in Ac2 compared with Ac1. circRNA-miRNA regulatory networks indicated that 1060 circRNAs can target 74 miRNAs; additionally, the DEcircRNA-miRNA-mRNA networks suggested that 13 downregulated circRNAs can bind to eight miRNAs and 29 miRNA-targeted mRNAs, while 16 upregulated circRNAs can link to 9 miRNAs and 29 miRNA-targeted mRNAs. These results indicated that DEcircRNAs as ceRNAs may play a comprehensive role in the growth, development, and metabolism of the worker's midgut via regulating source genes and interacting with miRNAs. Notably, eight DEcircRNAs targeting miR-6001-y were likely to be key participants in the midgut development. Our findings not only offer a valuable resource for further studies on A. cerana cerana circRNA and novel insights into understanding the molecular mechanisms underlying the midgut development of eastern honeybee but also provide putative circRNA candidates for functional research in the near future and novel biomarkers for identification of eastern honeybee species including A. cerana cerana and honeybee diseases such as chalkbrood and microsporidiosis.

Enantioselective Olfactory Effects of the Neonicotinoid Dinotefuran on Honey Bees (Apis mellifera L.)

Sublethal exposure to neonicotinoids affects honey bee olfaction, but few studies have investigated the sublethal effects of the enantioselective neonicotinoid dinotefuran on honey bee olfaction. This study assessed the sublethal olfactory toxicity of dinotefuran enantiomers to honey bees. Compared to R-dinotefuran, S-dinotefuran had higher acute oral toxicity, sucrose sensitivity effects, octopamine concentrations, lower learning ability, and memory effects on honey bees. High-throughput circular RNA sequencing of the honey bee brain revealed that R-dinotefuran caused more gene regulatory changes than S-dinotefuran. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that the SERCA, Kca, and Maxik genes may be related to the enantioselective effects of dinotefuran isomers on honey bee olfaction. These results indicated that the current ecotoxicological safety knowledge about chiral dinotefuran effects on honey bees should be amended.

The Emerging Proteomic Research Facilitates in-Depth Understanding of the Biology of Honeybees

Advances in instrumentation and computational analysis in proteomics have opened new doors for honeybee biological research at the molecular and biochemical levels. Proteomics has greatly expanded the understanding of honeybee biology since its introduction in 2005, through which key signaling pathways and proteins that drive honeybee development and behavioral physiology have been identified. This is critical for downstream mechanistic investigation by knocking a gene down/out or overexpressing it and being able to attribute a specific phenotype/biochemical change to that gene. Here, we review how emerging proteome research has contributed to the new understanding of honeybee biology. A systematic and comprehensive analysis of global scientific progress in honeybee proteome research is essential for a better understanding of research topics and trends, and is potentially useful for future research directions.

Potential Natural Food Preservatives and Their Sustainable Production in Yeast: Terpenoids and Polyphenols

Terpenoids and polyphenols are high-valued plant secondary metabolites. Their high antimicrobial activities demonstrate their huge potential as natural preservatives in the food industry. With the rapid development of metabolic engineering, it has become possible to realize large-scale production of non-native terpenoids and polyphenols by using the generally recognized as safe (GRAS) strain, Saccharomyces cerevisiae, as a cell factory. This review will summarize the major terpenoid and polyphenol compounds with high antimicrobial properties, describe their native metabolic pathways as well as antimicrobial mechanisms, and highlight current progress on their heterologous biosynthesis in S. cerevisiae. Current challenges and perspectives for the sustainable production of terpenoid and polyphenol as natural food preservatives via S. cerevisiae will also be discussed.

In-depth Proteome of the Hypopharyngeal Glands of Honeybee Workers Reveals Highly Activated Protein and Energy Metabolism in Priming the Secretion of Royal Jelly

Royal jelly (RJ) is a secretion of the hypopharyngeal glands (HGs) of honeybee workers. High royal jelly producing bees (RJBs), a stock of honeybees selected from Italian bees (ITBs), have developed a stronger ability to produce RJ than ITBs. However, the mechanism underpinning the high RJ-producing performance in RJBs is still poorly understood. We have comprehensively characterized and compared the proteome across the life span of worker bees between the ITBs and RJBs. Our data uncover distinct molecular landscapes that regulate the gland ontogeny and activity corresponding with age-specific tasks. Nurse bees (NBs) have a well-developed acini morphology and cytoskeleton of secretory cells in HGs to prime the gland activities of RJ secretion. In RJB NBs, pathways involved in protein synthesis and energy metabolism are functionally induced to cement the enhanced RJ secretion compared with ITBs. In behavior-manipulated RJB NBs, the strongly expressed proteins implicated in protein synthesis and energy metabolism further demonstrate their critical roles in the regulation of RJ secretion. Our findings provide a novel understanding of the mechanism consolidating the high RJ-output in RJBs.