More than royal food - Major royal jelly protein genes in sexuals and workers of the honeybee Apis mellifera

Assessing lethal and sublethal effects of pesticides on honey bees in a multifactorial context

The registration of novel pesticides that are subsequently banned because of their unexpected negative effects on non-target species can have a huge environmental impact. Therefore, the pre-emptive evaluation of the potential effects of new compounds is essential. To this aim both lethal and sublethal effects should be assessed in a realistic scenario including the other stressors that can interact with pesticides. However, laboratory studies addressing such interactive effects are rare, while standardized laboratory-based protocols focus on lethal effects and not on sub-lethal effects. We propose to assess both lethal and sublethal effects in a multifactorial context including the other stressors affecting the non-target species. We tested this approach by studying the impact on honey bees of the insecticide sulfoxaflor in combination with a common parasite, a sub-optimal temperature and food deprivation. We studied the survival and the transcriptome of honey bees, to assess both the lethal and the potential sublethal effects of the insecticide, respectively. With this method we show that a field realistic concentration of sulfoxaflor in food does not affect the survival of honey bees; however, the significant impact on some key genes indicates that sublethal effects are possible in a realistically complex scenario. Moreover, our results demonstrate the feasibility and reliability of a novel approach to hazard assessment considering the interactive effects of pesticides. We anticipate our approach to be a starting point for a paradigm shift in toxicology: from an unifactorial, mortality-centered assessment to a multifactorial, comprehensive approach. This is something of the utmost importance to preserve pollination, thus contributing to the sustainability of our food production system.

Behavioral and genetic correlates of heterogeneity in learning performance in individual honeybees, Apis mellifera

Learning an olfactory discrimination task leads to heterogeneous results in honeybees with some bees performing very well and others at low rates. Here we investigated this behavioral heterogeneity and asked whether it was associated with particular gene expression patterns in the bee's brain. Bees were individually conditioned using a sequential conditioning protocol involving several phases of olfactory learning and retention tests. A cumulative score was used to differentiate the tested bees into high and low performers. The rate of CS+ odor learning was found to correlate most strongly with a cumulative performance score extracted from all learning and retention tests. Microarray analysis of gene expression in the mushroom body area of the brains of these bees identified a number of differentially expressed genes between high and low performers. These genes are associated with diverse biological functions, such as neurotransmission, memory formation, cargo trafficking and development.

Expression of honey bee (Apis mellifera) sterol homeostasis genes in food jelly producing glands of workers

Adult workers of Western honey bees (Apis mellifera L.) acquire sterols from their pollen diet. These food sterols are transported by the hemolymph to peripheral tissues such as the mandibular and the hypopharyngeal glands in the worker bees' heads that secrete food jelly which is fed to developing larvae. As sterols are obligatory components of biological membranes and essential precursors for molting hormone synthesis in insects, they are indispensable to normal larval development. Thus, the study of sterol delivery to larvae is important for a full understanding of honey bee larval nutrition and development. Whereas hypopharyngeal glands only require sterols for their membrane integrity, mandibular glands add sterols, primarily 24-methylenecholesterol, to its secretion. For this, sterols must be transported through the glandular epithelial cells. We have analyzed for the first time in A. mellifera the expression of genes which are involved in intracellular movement of sterols. Mandibular and hypopharyngeal glands were dissected from newly emerged bees, 6-day-old nurse bees that feed larvae and 26-day-old forager bees. The expression of seven genes involved in intracellular sterol metabolism was measured with quantitative real-time PCR. Relative transcript abundance of sterol metabolism genes was significantly influenced by the age of workers and specific genes but not by gland type. Newly emerged bees had significantly more transcripts for six out of seven genes than older bees indicating that the bulk of the proteins needed for sterol metabolism are produced directly after emergence.

Sublethal acetamiprid exposure induces immunity, suppresses pathways linked to juvenile hormone synthesis in queens and affects cycle-related signaling in emerging bees

Acetamiprid is the only neonicotinoid registered in the European Union because the risks of neonicotinoids to honey bees and other pollinators are strictly regulated. Herein, we orally exposed honey bee colonies to sublethal concentrations of acetamiprid (20 μg/L) under isolated conditions. After one month of continuous exposure, the emerging bees and queens were collected and analyzed via high-throughput label-free quantitative proteomics using a data-independent acquisition strategy. Six and 34 significantly differentially expressed proteins (DEPs) were identified in the emerging bees and queens, respectively. Mrjp3 was the only DEP found in both sample types/castes, and its opposite regulation illustrated a differential response. The DEPs in the emerging bees (H/ACA RNP, Rap1GAP, Mrjp3, and JHE) suggested that sublethal exposure to acetamiprid affected cell cycle-related signaling, which may affect the life history of workers in the colony. The DEPs with increased levels in queens, such as Mrjps 1-4 and 6-7, hymenoptaecin, and apidaecin 22, indicated an activated immune response. Additionally, the level of farnesyl pyrophosphate synthase (FPPS), which is essential for the mevalonate pathway and juvenile hormone biosynthesis, was significantly decreased in queens. The impaired utilization of juvenile hormone in queens supported the identification of additional DEPs. Furthermore, the proteome changes suggested the existence of increased neonicotinoid detoxification by UDP-glucuronosyltransferase and increased amino acid metabolism. The results suggest that the continuous exposure of bee colonies to acetamiprid at low doses (nanograms per gram in feed) may pose a threat to the colonies. The different exposure routes and durations for the emerging bees and queens in our experiment must be considered, i.e., the emerging bees were exposed as larvae via feeding royal jelly and beebread provided by workers (nurse bees), whereas the queens were fed royal jelly throughout the experiment. The biological consequences of the proteomic changes resulting from sublethal/chronic exposure require future determination.

Transcriptome analysis of Apis mellifera antennae reveals molecular divergence underlying the division of labour in worker bees

The olfactory system plays a fundamental role in mediating insect behaviour. Worker bees exhibit an age-dependent division of labour, performing discrete sets of behaviours throughout their lifespan. The behavioural states of bees rely on their sense of the environment and chemical communication via their olfactory system, the antennae. However, the olfactory adaptation mechanism of worker bees during their behavioural development remains unclear. In this study, we conducted a comprehensive and quantitative analysis of antennal gene expression in the Apis mellifera of newly emerged workers, nurses, foragers and defenders using RNA-seq. We found that the antenna tissues of honey bees continued developing after transformation from newly emerged workers to adults. Additionally, we identified differentially expressed genes associated with bee development and division of labour. We validated that major royal jelly protein genes are highly and specifically expressed in nurse honey bee workers. Furthermore, we identified and validated significant alternative splicing events correlated with the development and division of labour. These findings provide a comprehensive transcriptome profile and a new perspective on the molecular mechanisms that may underlie the worker honey bee division of labour.

Comparative Evolutionary Genomics in Insects

Genome sequencing quality, in terms of both read length and accuracy, is constantly improving. By combining long-read sequencing technologies with various scaffolding techniques, chromosome-level genome assemblies are now achievable at an affordable price for non-model organisms. Insects represent an exciting taxon for studying the genomic underpinnings of evolutionary innovations, due to ancient origins, immense species-richness, and broad phenotypic diversity. Here we summarize some of the most important methods for carrying out a comparative genomics study on insects. We describe available tools and offer concrete tips on all stages of such an endeavor from DNA extraction through genome sequencing, annotation, and several evolutionary analyses. Along the way we describe important insect-specific aspects, such as DNA extraction difficulties or gene families that are particularly difficult to annotate, and offer solutions. We describe results from several examples of comparative genomics analyses on insects to illustrate the fascinating questions that can now be addressed in this new age of genomics research.

Mediating a host cell signaling pathway linked to overwinter mortality offers a promising therapeutic approach for improving bee health

INTRODUCTION

Honey bees provides valuable pollination services for world food crops and wild flowering plants which are habitats of many animal species and remove carbon dioxide from the atmosphere, a powerful tool in the fight against climate change. Nevertheless, the honey bee population has been declining and the majority of colony losses occur during the winter.

OBJECTIVES

The goal of this study was to understand the mechanisms underlying overwinter colony losses and develop novel therapeutic strategies for improving bee health.

METHODS

First, pathogen prevalence in overwintering bees were screened between 2015 and 2018. Second, RNA sequencing (RNA-Seq) for transcriptional profiling of overwintering honey bees was conducted and qRT-PCR was performed to confirm the results of the differential expression of selected genes. Lastly, laboratory bioassays were conducted to measure the effects of cold challenges on bee survivorship and stress responses and to assess the effect of a novel medication for alleviating cold stress in honey bees.

RESULTS

We identified that sirtuin signaling pathway is the most significantly enriched pathway among the down-regulated differentially expressed genes (DEGs) in overwintering diseased bees. Moreover, we showed that the expression of SIRT1 gene, a major sirtuin that regulates energy and immune metabolism, was significantly downregulated in bees merely exposed to cold challenges, linking cold stress with altered gene expression of SIRT1. Furthermore, we demonstrated that activation of SIRT1 gene expression by SRT1720, an activator of SIRT1 expression, could improve the physiology and extend the lifespan of cold-stressed bees.

CONCLUSION

Our study suggests that increased energy consumption of overwintering bees for maintaining hive temperature reduces the allocation of energy toward immune functions, thus making the overwintering bees more susceptible to disease infections and leading to high winter colony losses. The novel information gained from this study provides a promising avenue for the development of therapeutic strategies for mitigating colony losses, both overwinter and annually.

Ferroptosis precedes apoptosis to facilitate specific death signalling by fatty acids

Cell death is physiologically induced by specific mediators. However, our power to trigger the process in selected cells is quite limited. The protandric shrimp Hippolyte inermis offers a possible answer. Here, we analyse a de novo transcriptome of shrimp post-larvae fed on diatoms. The sex ratio of diatom-fed shrimps versus shrimps fed on control diets was dramatically altered, demonstrating the disruption of the androgenic gland, and their transcriptome revealed key modifications in gene expression. A wide transcriptomic analysis, validated by real-time qPCR, revealed that ferroptosis represents the primary factor to re-shape the body of this invertebrate, followed by further apoptotic events, and our findings open biotechnological perspectives for controlling the destiny of selected tissues. Ferroptosis was detected here for the first time in a crustacean. In addition, this is the first demonstration of a noticeable effect prompted by an ingested food, deeply impacting the gene networks of a young metazoan, definitely determining its future physiology and sexual differentiation.

Revolutionizing the Use of Honeybee Products in Healthcare: A Focused Review on Using Bee Pollen as a Potential Adjunct Material for Biomaterial Functionalization

The field of biomedical engineering highly demands technological improvements to allow the successful engraftment of biomaterials requested for healing damaged host tissues, tissue regeneration, and drug delivery. Polymeric materials, particularly natural polymers, are one of the primary suitable materials employed and functionalized to enhance their biocompatibility and thus confer advantageous features after graft implantation. Incorporating bioactive substances from nature is a good technique for expanding or increasing the functionality of biomaterial scaffolds, which may additionally encourage tissue healing. Our ecosystem provides natural resources, like honeybee products, comprising a rich blend of phytochemicals with interesting bioactive properties, which, when functionally coupled with biomedical biomaterials, result in the biomaterial exhibiting anti-inflammatory, antimicrobial, and antioxidant effects. Bee pollen is a sustainable product recently discovered as a new functionalizing agent for biomaterials. This review aims to articulate the general idea of using honeybee products for biomaterial engineering, mainly focusing on describing recent literature on experimental studies on biomaterials functionalized with bee pollen. We have also described the underlying mechanism of the bioactive attributes of bee pollen and shared our perspective on how future biomedical research will benefit from the fabrication of such functionalized biomaterials.

Identification of royal jelly as a potential new drug to protect the ovarian reserve and uterus against cyclophosphamide in rats

OBJECTIVE

The aim of this study was to investigate the effect of royal jelly (RJ), a powerful natural antioxidant, on cyclophosphamide-induced ovarian damage.

METHODS

Thirty-two Wistar albino rats were divided into four groups. Oral treatment was administered to all rats for 16 days after a single intraperitoneal injection. The control group received intraperitoneal and oral saline; the RJ group received intraperitoneal saline and 100 mg/kg/day oral RJ; the cyclophosphamide group received intraperitoneal 100 mg/kg cyclophosphamide and oral saline; and the treatment group received intraperitoneal 100 mg/kg cyclophosphamide and 100 mg/kg/day oral RJ. The groups were compared in terms of ovarian reserve tests and histopathological changes in the ovary and uterus.

RESULTS

All follicle counts were higher in the treatment group than in the cyclophosphamide group. The increase in the number of preantral follicles (p=0.001) and the decrease in the number of atretic follicles (p=0.004) were statistically significant. RJ treatment significantly improved follicular degeneration and cortical fibrosis in the ovary and epithelial and gland degeneration in the uterus due to cyclophosphamide toxicity.

CONCLUSION

According to these results, RJ reduces cyclophosphamide-related ovarian and endometrial damage in rats. For this reason, it should be further investigated to determine its effects on reproductive function.

Quantitative comparison of manuka and clover honey proteomes with royal jelly

Royal jelly and honey are two substances produced successively by the worker bee caste. Modern proteomics approaches have been used to explore the protein component of each substance independently, but to date none have quantitatively compared the protein profile of honey and royal jelly directly. Sequential window acquisition of all theoretical fragment-ion spectra mass spectrometry (SWATH-MS) was used to compare protein quantities of bee origin in mānuka and clover honey to royal jelly. Two analysis techniques identified 76 proteins in total. Peptide intensity was directly compared for a subset of 31 proteins that were identified with high confidence, and the relative changes in protein abundance were compared between each honey type and royal jelly. Major Royal Jelly Proteins (MRJPs) had similar profiles in both honeys, except MRJP6, which was significantly more abundant in clover honey. Proteins involved in nectar metabolism were more abundant in honey than in royal jelly as expected. However, the trend revealed a potential catalytic role for MRJP6 in clover honey and a nectar- or honey-specific role for uncharacterised protein LOC408608. The abundance of MRJP6 in mānuka honey was equivalent to royal jelly suggesting a potential effect of nectar type on expression of this protein. Data are available via ProteomeXchange with identifier PXD038889.

Current Status of the Bioactive Properties of Royal Jelly: A Comprehensive Review with a Focus on Its Anticancer, Anti-Inflammatory, and Antioxidant Effects

Royal jelly (RJ) has been one of the most widely used natural products in alternative medicine for centuries. Being produced by both hypopharyngeal and mandibular glands, RJ exhibits an extraordinary complexity in terms of its composition, including proteins, lipids, carbohydrates, polyphenols, vitamins, and hormones. Due to its heterogeneous structure, RJ displays various functional roles for honeybees, including being involved in nutrition, learning, memory, and social behavior. Furthermore, a wide range of studies reported its therapeutic properties, including anticancer, anti-inflammatory, and antioxidant activities, to name a few. In this direction, there is a wide range of health-related problems for which the medical area specialists and researchers are continuously trying to find a cure, such as cancer, atherosclerosis, or infertility. For the mentioned diseases and more, it has been proven that RJ is a key player in finding a valuable treatment. In this review, the great impact of RJ as an alternative medicine agent is highlighted, with a focus on its anticancer, anti-inflammatory, and antioxidant activities. Moreover, we link it to its apitherapeutic potential by discussing its composition. Herein, we discuss a wide range of novel studies and present the latest research work.

Major royal jelly proteins influence the neurobiological regulation of the division of labor among honey bee workers

Age-based division of labor among workers is a fundamental life-history trait of many social insects, including the Western honey bee, Apis mellifera L. Extensive studies of the causation of the most pronounced transition from performing tasks in the nest to outside foraging indicate hormonal regulation of complex physiological changes. However, the proximate neurobiological mechanisms that cause the behavioral repertoire to change are still not understood and require novel approaches to be fully characterized. Thus, we established the first comprehensive monoclonal antibody microarray in honey bees with 16,320 antibodies to directly identify proteins in the brain that regulate the transition to foraging. Major royal jelly protein (MRJP) 1 and MRJP3 were identified as potential protein effectors and further investigated. A series of experimental manipulations of the workers' behavioral transition led to changes in MRJP1 and MRJP3 quantities in accordance with their presumed functional role. Injection of MRJPs into the brain resulted in increased task-reversal from foraging to nursing and decreased task-progression from nursing to foraging, while the latter was increased by injection with MRJP antibodies. Finally, down-regulation of MRJP1 and MRJP3 expression via RNAi injection into the brain increased the transition from in-hive nursing to outside foraging, confirming a causal role of these two proteins in the proximate regulation of behavior and life-history of honey bee workers. Interaction partners of MRJP1 and MRJP3 in the honey bee brain included other regulators of honey bee behavior and life history. Thus, our transformative methodological advancement of proteome analysis in honey bees reveals novel regulators of honey bee behavior, extends our understanding of the functional pleiotropy of MRJPs, and supports a general nutrition-based model of the regulation of the age-based division of labor in honey bees.

Increased Stress Levels in Caged Honeybee (Apis mellifera) (Hymenoptera: Apidae) Workers

Honeybees, Apis mellifera, usually live in large colonies consisting of thousands of individuals. Within the colony, workers interact with their social environment frequently. The large workforce, division of labour, and other features may promote the ecological success of honeybees. For decades, artificial mini colonies in cages within the laboratory have become the gold standard, especially in experiments related to toxicology, effects of pesticides and pathogens. Experiments using caged bees and full-sized colonies yielded contradictory results. Here, the effect of cage experiments on the stress level of individual bees is analysed. Two different stress response were targeted, the heat shock response and the mobilization of energetic resources. While no differences were found for varying group sizes of bees, very strong effects emerged by comparing caged workers with bees from natural colonies. Caged workers showed increased levels of hsp expression and reduced haemolymph titres for trehalose, the energy storage sugar. These results reveal that the lack of the social environment (e.g., lack of queen, lack of sufficient group size) induce stress in caged bees, which might act synergistically when bees are challenged by additional stressors (e.g., pesticides, pathogens) resulting in higher mortality than observed under field conditions.

Royal Jelly Components Encapsulation in a Controlled Release System—Skin Functionality and Biochemical Activity for Skin Applications

Royal jelly is a yellowish-white substance with a gel texture that is secreted from the hypopharyngeal and mandibular glands of young worker bees. It consists mainly of water (50–56%), proteins (18%), carbohydrates (15%), lipids (3–6%), minerals (1.5%), and vitamins, and has many beneficial properties such as antimicrobial, anti-inflammatory, anticancer, antioxidant, antidiabetic, immunomodulatory, and anti-aging. Royal jelly has been used since ancient times in traditional medicine, cosmetics and as a functional food due to its high nutritional value. The main bioactive substances are royalactin, and 10-hydroxy-2-decenoic acid (10-HDA). Other important bioactive molecules with antioxidant and photoprotective skin activity are polyphenols. However, they present difficulties in extraction and in use as they are unstable physicochemically, and a higher temperature causes color change and component degradation. In the present study, a new encapsulation and delivery system consisting of liposomes and cyclodextrins incorporating royal jelly has been developed. The new delivery system aims to the elimination of the stability disadvantages of royal jelly’s sensitive component 10-HDA, but also to the controlled release of its ingredients and, more particularly, 10-HDA, for an enhanced bioactivity in cosmeceutical applications.

Expression of MRJP3 and HSP70 mRNA Levels in Apis mellifera L. Workers after Dietary Supplementation with Proteins, Prebiotics, and Probiotics

Royal jelly is an essential substance for the development of bees from larval to adult stages. Studies have identified a group of key proteins in royal jelly, denominated major royal jelly proteins (MRJPs). The group currently consists of nine proteins (MRJP1–MRJP9), with MRJP1 being the most abundant and MRJP3 being used as a microsatellite marker for the selection of queens with a greater production of royal jelly. The diet of bees is mostly composed of proteins, and supplementing this intake to encourage a higher production of their primary product is important for producers. It is estimated that, by adding probiotic and prebiotic organisms to their diets, the benefits to bees will be even greater, both for their immune systems and primary responses to stress. Circumstances that are adverse compared to those of the natural habitat of bees eventually substantially interfere with bee behavior. Stress situations are modulated by proteins termed heat shock proteins (HSPs). Among these, HSP70 has been shown to exhibit abundance changes whenever bees experience unusual situations of stress. Thus, we sought to supplement A. mellifera bee colony diets with proteins and prebiotic and probiotic components, and to evaluate the expression levels of MRJP3 and HSP70 mRNAs using qRT-PCR. The results revealed that differences in the expression of MRJP3 can be attributed to the different types of feed offered. Significant differences were evident when comparing the expression levels of MRJP3 and HSP70, suggesting that protein supplementation with pre/probiotics promotes positive results in royal jelly synthesis carried out by honey bee nurses.

Updated species checklist of fishes from Lake Dongting in Hunan Province, South China: Species diversity and conservation

A lack of an updated checklist of freshwater fish species from Lake Dongting is a great hindrance to further biodiversity analysis. A seasonal survey of fishes in the lake was conducted from October 2017 to January 2019. Based on the data obtained during the field survey and coupled with known literature and the latest taxonomic development of relevant taxa, the species checklist of fishes from Lake Dongting was updated. A total of 130 species from 12 orders, 30 families and 76 genera has been documented, containing 126 native species and four alien species. Its fish fauna is dominated by the Xenocyprididae that has the highest number of included species (30), followed by the Gobionidae (25) and Acheilognathidae (11). This checklist comprises 20 species undergoing nomenclatural changes and 11 new records, eight of which are native and three exotic. It excludes 20 species, which have been reported in error in historical works, due to synonyms, erroneous records, taxonomic changes and unconfirmed records. Unsampled in this survey were 34 species that are ecologically specialised: migratory, rheophilic, predatory, shellfish-dependent or pelagic-egg-spawning. While some of these species eluded capture likely due to the paucity of population, others may have been extirpated in Lake Dongting perhaps owing to human perturbations, such as river damming across affluents or the Chang-Jiang mainstem, sand dredging, overfishing or water pollution. The updated checklist lays a sound foundation for biodiversity conservation of fishes in Lake Dongting.

Extent and complexity of RNA processing in honey bee queen and worker caste development

The distinct honeybee (Apis mellifera) worker and queen castes have become a model for the study of genomic mechanisms of phenotypic plasticity. Here we performed a nanopore-based direct RNA sequencing with exceptionally long reads to compare the mRNA transcripts between queen and workers at three points during their larval development. We found thousands of significantly differentially expressed transcript isoforms (DEIs) between queen and worker larvae. These DEIs were formatted by a flexible splicing system. We showed that poly(A) tails participated in this caste differentiation by negatively regulating the expression of DEIs. Hundreds of isoforms uniquely expressed in either queens or workers during their larval development, and isoforms were expressed at different points in queen and worker larval development demonstrating a dynamic relationship between isoform expression and developmental mechanisms. These findings show the full complexity of RNA processing and transcript expression in honey bee phenotypic plasticity.

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Honeybee caste differentiation has a complexity of RNA processing

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Isoforms differentially express between queens and workers during larval development

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Isoforms are formatted by a flexible alternative splicing system

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Poly(A) tails are negatively correlated with isoform expression

Ameliorative effect of bee products on in vitro maturation of sheep oocytes

The present study was undertaken to investigate the possible stimulating effects of Nigella sativa (N. sativa) honey, natural Saudi Sider honey, and honeybee pollen to the in vitro maturation (IVM) medium of sheep oocytes on their subsequent development. Hence, immature oocytes were exposed to various concentrations of natural Nigella sativa (N. sativa), and Saudi Sider honey (5, 10, and 20%), as well as honeybee pollen (1, 10, 50 μg/ml) during an in vitro maturation period (24 hours). After the exposure time, the maturation rate, glutathione (GSH) concentration, and candidate gene expression (GDF-9, MPF, CMOS, IGF-1, and BAX) were evaluated. Our results showed that the maturation rate was higher in the groups challenged with the lowest level of the bee products (5% and 1 μg/ml) when compared with that in the control group; where the mean number of oocytes in the metaphase II stage reached 0.360 for the honeybee pollen-treated group, 0.293 for the N. sativa-treated group, and 0.203 for the natural Saudi Sider honey-treated group. The glutathione level was significantly increased in the group exposed to N. sativa honey when compared with the other groups. Concerning the gene expression results, the Saudi Sider honey treatment showed the best results for all the genes except the CMOS gene, which was significantly higher than the GI and GII groups and lower than the GIV group and the BAX gene which did not show a significant difference when compared with the other groups. In conclusion, the addition of natural honey and honeybee pollen at a low concentration to an IVM medium improved the in vitro maturation rate, increased the glutathione level, and gene expression of the in vitro matured ovine oocytes.

Antibacterial and antioxidant activity of royal jelly collected from geographical regions with different climates in the north of Iran

Royal jelly is one of the most important bee products. The biological activities of royal jelly can be influenced by various factors such as geographic origin, climatic conditions, vegetation. This study was carried out to evaluate the antibacterial and antioxidant activity of royal jelly samples collected from beehives from different geographical regions including mountain, coastal and plain regions in northern Iran. Antibacterial activity of royal jelly samples against ten bacteria was determined using agar well diffusion method. The MIC and MBC of royal jelly samples were determined by the broth microdilution method. Folin-Ciocâlteu reagent and reaction with DPPH were used to determine the total phenolic content and antioxidant potential of royal jelly samples, respectively. The MIC of samples ranged from 0.78 to 12.5% and MBC - from 3.12 to 50%. Samples collected from mountain regions showed the highest antibacterial activity with MIC for Gram-positive bacteria from 0.78 to 1.56% and for Gram-negative bacteria: from 1.56 to 3.12%. The total phenolic content and DPPH radical scavenging activity in royal jelly samples of the mountain region was significantly higher than those from the two regions with other climates. The results of this study indicated that the climate of the geographic region of sampling location had an effect on the antibacterial and antioxidant activity of royal jelly which may be due to differences in plant vegetation and the origin of the flowers of bees.

A potential probiotic Leuconostoc mesenteroides TBE-8 for honey bee

An isolated bacterium TBE-8, was identified as Leuconostoc mesenteroides according to the sequences of 16S rDNA and the 16S-23S rDNA intergenic spacer region. The probiotic properties of the L. mesenteroides TBE-8 strain were characterized and revealed that TBE-8 could utilize various carbohydrates, exhibited high tolerance to sucrose's osmotic pressure and acidic conditions, and could mitigate the impact of the bee pathogen Paenibacillus larvae. In addition, we found that the TBE-8 broth increased the expression of the nutrition-related genes major royal jelly protein 1 and vitellogenin in bees by approximately 1400- and 20-fold, respectively. The expression of genes encoding two antibacterial peptides, hymenoptaecin and apidaecin, in the bee abdomen was significantly increased by 17- and 7-fold in bees fed with the TBE-8 fermented broth. Furthermore, we fed four-frame bee colonies with 50% sucrose syrup containing TBE-8 and can detect the presence of approximately 2 × 106 16S rDNA copies of TBE-8 in the guts of all bees in 24 h, and the retention of TBE-8 in the bee gut for at least 5 days. These findings indicate that the L. mesenteroides TBE-8 has high potential as a bee probiotic and could enhance the health of bee colonies.

Effects of Insecticides and Microbiological Contaminants on Apis mellifera Health

Over the past two decades, there has been an alarming decline in the number of honey bee colonies. This phenomenon is called Colony Collapse Disorder (CCD). Bee products play a significant role in human life and have a huge impact on agriculture, therefore bees are an economically important species. Honey has found its healing application in various sectors of human life, as well as other bee products such as royal jelly, propolis, and bee pollen. There are many putative factors of CCD, such as air pollution, GMO, viruses, or predators (such as wasps and hornets). It is, however, believed that pesticides and microorganisms play a huge role in the mass extinction of bee colonies. Insecticides are chemicals that are dangerous to both humans and the environment. They can cause enormous damage to bees' nervous system and permanently weaken their immune system, making them vulnerable to other factors. Some of the insecticides that negatively affect bees are, for example, neonicotinoids, coumaphos, and chlorpyrifos. Microorganisms can cause various diseases in bees, weakening the health of the colony and often resulting in its extinction. Infection with microorganisms may result in the need to dispose of the entire hive to prevent the spread of pathogens to other hives. Many aspects of the impact of pesticides and microorganisms on bees are still unclear. The need to deepen knowledge in this matter is crucial, bearing in mind how important these animals are for human life.

Beehive Products as Antibacterial Agents: A Review

Honeybees are one of the most marvelous and economically beneficial insects. As pollinators, they play a vital role in every aspect of the ecosystem. Beehive products have been used for thousands of years in many cultures for the treatment of various diseases. Their healing properties have been documented in many religious texts like the Noble Quran and the Holy Bible. Honey, bee venom, propolis, pollen and royal jelly all demonstrated a richness in their bioactive compounds which make them effective against a variety of bacterial strains. Furthermore, many studies showed that honey and bee venom work as powerful antibacterial agents against a wide range of bacteria including life-threatening bacteria. Several reports documented the biological activities of honeybee products but none of them emphasized on the antibacterial activity of all beehive products. Therefore, this review aims to highlight the antibacterial activity of honey, bee venom, propolis, pollen and royal jelly, that are produced by honeybees.

Comparative transcriptomic analysis of the mechanisms underpinning ageing and fecundity in social insects

The exceptional longevity of social insect queens despite their lifelong high fecundity remains poorly understood in ageing biology. To gain insights into the mechanisms that might underlie ageing in social insects, we compared gene expression patterns between young and old castes (both queens and workers) across different lineages of social insects (two termite, two bee and two ant species). After global analyses, we paid particular attention to genes of the insulin/insulin-like growth factor 1 signalling (IIS)/target of rapamycin (TOR)/juvenile hormone (JH) network, which is well known to regulate lifespan and the trade-off between reproduction and somatic maintenance in solitary insects. Our results reveal a major role of the downstream components and target genes of this network (e.g. JH signalling, vitellogenins, major royal jelly proteins and immune genes) in affecting ageing and the caste-specific physiology of social insects, but an apparently lesser role of the upstream IIS/TOR signalling components. Together with a growing appreciation of the importance of such downstream targets, this leads us to propose the TI-J-LiFe (TOR/IIS-JH-Lifespan and Fecundity) network as a conceptual framework for understanding the mechanisms of ageing and fecundity in social insects and beyond. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'

Improving Reproductive Performance and Health of Mammals Using Honeybee Products

Honeybee products have positive effects on the reproductive performance of mammals. Many honeybee product constituents are biologically active, with antioxidant, antimicrobial, antiviral, anti-inflammatory, immunomodulatory, antifungal, wound-healing, and cardio-protective properties. Honeybee products also improve male and female fertility rates by enhancing gamete cryopreservation, in vitro maturation and fertilization, and embryo development. Previously published studies confirmed their efficacy for alleviating reproductive toxicity caused by contaminants and lifestyle habits that impair overall health and well-being. However, high-dose oral administration of honeybee products may adversely affect the reproductive system, and unfavorable effects were alleviated by treatment cessation. For this reason, this review proposes that bioactive components from bee products can be used as a strategy for improving the reproductive performance and health of mammals.

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.

Differences in larval pesticide tolerance and esterase activity across honey bee (Apis mellifera) stocks

Honey bee populations in North America are an amalgamation of diverse progenitor ecotypes experiencing varying levels of artificial selection. Genetic differences between populations can result in variable susceptibility towards environmental stressors, and here we compared pesticide tolerances across breeding stocks using a mixture of seven pesticides frequently found in colonies providing pollination services. We administered the pesticide mixture chronically to in vitro reared larvae at four concentrations of increasing Hazard Quotient (HQ, or cumulative toxicity) and measured mortality during larval development. We found that different stocks had significantly different tolerances to our pesticide mixture as indicated by their median lethal toxicity (HQ₅₀). The intensively selected Pol-Line stock exhibited the greatest pesticide sensitivity while Old World (progenitor) and putatively feral stocks were the most pesticide-tolerant. Furthermore, we found that activity of the detoxification enzyme esterase was positively correlated with pesticide tolerance when measured using two different substrate standards, and confirmed that larvae from the Pol-Line stock had generally lower esterase activity. Consistent with an increased pesticide tolerance, the Old World and putatively feral stocks had higher esterase activities. However, esterases and other detoxification enzymes (CYP450s and GSTs) were found in similar abundances across stocks, suggesting that the differences in enzyme activity we observed might arise from stock-specific single nucleotide polymorphisms or post-translational modifications causing qualitative variation in enzyme activity. These results suggest that selective breeding may inadvertently increase honey bees' sensitivity to pesticides, whereas unselected, putatively feral and Old World stocks have larvae that are more tolerant.

Transcriptome sequencing of Coccinella septempunctata adults (Coleoptera: Coccinellidae) feeding on artificial diet and Aphis craccivora

Background

The insect predator Coccinella septempunctata can effectively control many types of pests, such as aphids, whiteflies, and small lepidopteran larvae. We previously found that C. septempunctata fed an artificial diet showed diminished biological properties(e.g. fecundity, egg hatching rate, survival rate, etc.) compared with those fed natural prey (Aphis craccivora), likely due to different nutritional characteristics of the diet. In this study, we used transcriptome sequencing analysis to identify nutrition- and metabolism-related genes of C. septempunctata that were differentially expressed depending on diet.

Methodology/Principal findings

The Illumina HiSeq2000 was used to sequence 691,942,058 total clean reads from artificial diet-fed and A. craccivora-fed C. septempunctata libraries, and the clean reads were assembled using Trinity de novo software (Tabel 2). Comparison of transcriptome sequences revealed that expression of 38,315 genes was affected by the artificial diet, and 1,182 of these genes showed a significant change in expression levels (FDR ≤ 0.05,|log2FC|≥1, “FC” stands for “fold change”). These differentially expressed genes (DEGs) were likely associated with the decreased egg laying capacity, hatching rate, longevity, and increased sex ratio (♀:♂) of adult C. septempunctata observed in the group fed the artificial diet. Furthermore, in the most DEGs metabolic pathways for C. septempunctata feeding on the artificial diet accumulated amino acid metabolic pathways, lipid metabolic pathways, and starch and glucose metabolism were down-regulated.

Conclusions/Significance

We found some differentially expressed genes and metabolic pathways are related to nutrition, from which a more informative feedback for diet formulation was obtained and the artificial diet could be more efficiently optimized.

Declining genetic diversity of European honeybees along the twentieth century

The European honeybee (Apis mellifera) is a key pollinator and has in the last decades suffered significant population decline. A combination of factors, including decrease in genetic diversity and introduction of Varroa mites, have been suggested to be responsible for these losses, but no definitive cause has yet been appointed. In Europe not only have wild colonies been severely affected, but managed hives have had a massive decline in numbers. To test the hypothesis that honeybees’ genetic diversity has decreased in the recent past, we used reduced representation genome sequencing of 40 historical honeybee specimens collected in Natural History collections across Europe and compared them to genomic data from 40 individuals from extant populations (collected post 2006). Our results are consistent with the existence of five evolutionary lineages as previously described, and show a decrease in genetic diversity between historical and extant individuals of the same lineage, as well as high levels of admixture in historical specimens. Our data confirm that a loss of genetic diversity has occurred during the last century, potentially increasing honeybees’ vulnerability to contemporary ecological and anthropogenic stressors.

Sex-specific molecular specialization and activity rhythm-dependent gene expression in honey bee antennae

We performed an RNA-seq-based comparison of gene expression levels in the antennae of honey bee drones and time-trained foragers (workers) collected at different times of the day and different activity states. Interestingly, olfaction-related genes [i.e. odorant receptor (Or) genes, odorant binding protein (Obp) genes, carboxyl esterase (CEst) genes, etc.] showed stable gene expression differences between drone and worker antennae. Drone antennae showed higher expression of 24 Or genes, of which 21 belong to the clade X which comprises the receptor for the major queen pheromone compound 9-ODA. This high number of drone-biased Or genes suggests that more than previously thought play a role in sex-pheromone communication. In addition, we found higher expression levels for many non-olfaction-related genes including nitric oxide synthase (NOS), and the potassium channel Shaw In contrast, workers showed higher expression of 67 Or genes, which belong to different Or clades that are involved in pheromone communication as well as the perception of cuticular hydrocarbons and floral scents. Further, drone antennae showed higher expression of genes involved in energy metabolism, whereas worker antennae showed higher expression of genes involved in neuronal communication, consistent with earlier reports on peripheral olfactory plasticity. Finally, drones that perform mating flight in the afternoon (innate) and foragers that are trained to forage in the afternoon (adapted) showed similar daily changes in the expression of two major clock genes, period and cryptochrome2 Most of the other genes showing changes with time or onset of daily flight activity were specific to drones and foragers.

Modification of the head proteome of nurse honeybees (Apis mellifera) exposed to field-relevant doses of pesticides

Understanding the effect of pesticides on the survival of honeybee colonies is important because these pollinators are reportedly declining globally. In the present study, we examined the changes in the head proteome of nurse honeybees exposed to individual and combined pesticides (the fungicide pyraclostrobin and the insecticide fipronil) at field-relevant doses (850 and 2.5 ppb, respectively). The head proteomes of bees exposed to pesticides were compared with those of bees that were not exposed, and proteins with differences in expression were identified by mass spectrometry. The exposure of nurse bees to pesticides reduced the expression of four of the major royal jelly proteins (MRJP1, MRJP2, MRJP4, and MRJP5) and also several proteins associated with carbohydrate metabolism and energy synthesis, the antioxidant system, detoxification, biosynthesis, amino acid metabolism, transcription and translation, protein folding and binding, olfaction, and learning and memory. Overall, when pyraclostrobin and fipronil were combined, the changes in protein expression were exacerbated. Our results demonstrate that vital proteins and metabolic processes are impaired in nurse honeybees exposed to pesticides in doses close to those experienced by these insects in the field, increasing their susceptibility to stressors and affecting the nutrition and maintenance of both managed and natural colonies.

Towards Precision Nutrition: A Novel Concept Linking Phytochemicals, Immune Response and Honey Bee Health

The high annual losses of managed honey bees (Apis mellifera) has attracted intensive attention, and scientists have dedicated much effort trying to identify the stresses affecting bees. There are, however, no simple answers; rather, research suggests multifactorial effects. Several works have been reported highlighting the relationship between bees' immunosuppression and the effects of malnutrition, parasites, pathogens, agrochemical and beekeeping pesticides exposure, forage dearth and cold stress. Here we analyze a possible connection between immunity-related signaling pathways that could be involved in the response to the stress resulted from Varroa-virus association and cold stress during winter. The analysis was made understanding the honey bee as a superorganism, where individuals are integrated and interacting within the colony, going from social to individual immune responses. We propose the term "Precision Nutrition" as a way to think and study bees' nutrition in the search for key molecules which would be able to strengthen colonies' responses to any or all of those stresses combined.

The rise and fall of major royal jelly proteins during a honeybee (Apis mellifera) workers' life

The genome of the western honeybee (Apis mellifera) harbors nine transcribed major royal jelly protein genes (mrjp1-9) which originate from a single-copy precursor via gene duplication. The first MRJP was identified in royal jelly, a secretion of the bees' hypopharyngeal glands that is used by young worker bees, called nurses, to feed developing larvae. Thus, MRJPs are frequently assumed to mainly have functions for developing bee larvae and to be expressed in the food glands of nurse bees. In-depth knowledge on caste- and age-specific role and abundance of MRJPs is missing. We here show, using combined quantitative real-time PCR with quantitative mass spectrometry, that expression and protein amount of mrjp1-5 and mrjp7 show an age-dependent pattern in worker's hypopharyngeal glands as well as in brains, albeit lower relative abundance in brains than in glands. Expression increases after hatching until the nurse bee period and is followed by a decrease in older workers that forage for plant products. Mrjp6 expression deviates considerably from the expression profiles of the other mrjps, does not significantly vary in the brain, and shows its highest expression in the hypopharyngeal glands during the forager period. Furthermore, it is the only mrjp of which transcript abundance does not correlate with protein amount. Mrjp8 and mrjp9 show, compared to the other mrjps, a very low expression in both tissues. Albeit mrjp8 mRNA was detected via qPCR, the protein was not quantified in any of the tissues. Due to the occurrence of MRJP8 and MRJP9 in other body parts of the bees, for example, the venom gland, they might not have a hypopharyngeal gland- or brain-specific function but rather functions in other tissues. Thus, mrjp1-7 but not mrjp8 and mrjp9 might be involved in the regulation of phenotypic plasticity and age polyethism in worker honeybees.

An Evolutionary Perspective of Dopachrome Tautomerase Enzymes in Metazoans

Melanin plays a pivotal role in the cellular processes of several metazoans. The final step of the enzymically-regulated melanin biogenesis is the conversion of dopachrome into dihydroxyindoles, a reaction catalyzed by a class of enzymes called dopachrome tautomerases. We traced dopachrome tautomerase (DCT) and dopachrome converting enzyme (DCE) genes throughout metazoans and we could show that only one class is present in most of the phyla. While DCTs are typically found in deuterostomes, DCEs are present in several protostome phyla, including arthropods and mollusks. The respective DCEs belong to the yellow gene family, previously reported to be taxonomically restricted to insects, bacteria and fungi. Mining genomic and transcriptomic data of metazoans, we updated the distribution of DCE/yellow genes, demonstrating their presence and active expression in most of the lophotrochozoan phyla as well as in copepods (Crustacea). We have traced one intronless DCE/yellow gene through most of the analyzed lophotrochozoan genomes and we could show that it was subjected to genomic diversification in some species, while it is conserved in other species. DCE/yellow was expressed in most phyla, although it showed tissue specific expression patterns. In the parasitic copepod Mytilicola intestinalis DCE/yellow even belonged to the 100 most expressed genes. Both tissue specificity and high expression suggests that diverse functions of this gene family also evolved in other phyla apart from insects.

Dyeing but not dying: Colourful dyes as a non-lethal method of food labelling for in vitro-reared honey bee (Apis mellifera) larvae

Several environmental factors (e.g. food source, pesticides, toxins, parasites and pathogens) influence development and maturation of honey bees (Apis mellifera). Therefore, controlled experimental conditions are mandatory when studying the impact of environmental factors: particularly food quality and nutrient consumption. In vitro larval rearing is a standard approach for monitoring food intake of larvae and the labelling of food is necessary to quantify intake in controlled feeding experiments. Here, we tested the suitability of two food dyes, Allura Red and Brilliant Blue, in an experimental set up using in vitro reared honey bee larvae and freshly hatched adult workers. Absorbance of both dyes was measured, in food and dye-fed larvae, to determine the optimal dye concentrations for accurate detection and quantification. By quantifying relative dye concentrations in dye mixtures, relative concentrations of mixed dyes can be estimated independent of the total food consumed by the larvae. Survival assays were conducted to test the impact of both dyes on larval and worker bee survival. Worker bees showed no increase in adult mortality, when fed with dyed honey. Larval survival was not significantly different until the late pupal stage. The physiological impact of dye feeding was tested by measuring larval immune response. No changes in innate immune gene expression were detectable for larvae fed with dyed and non-dyed food. In conclusion, we established a non-invasive food labelling protocol for food intake quantification in in vitro reared honey bee larvae, using non-toxic, inexpensive, and easy to apply food dyes.

Transcriptome Analysis of Newly Emerged Honeybees Exposure to Sublethal Carbendazim During Larval Stage

There are increasing concerns regarding the impact of agrochemical pesticides on non-target organisms. Pesticides could cause honeybee abnormal development in response to neurotoxins such as neonicotinoid. However, knowledge of carbendazim, a widespread fungicide in beekeeping practice, influencing on honeybee (Apis mellifera L.) brain development is lacking. Large-scale transcriptome approaches were applied to determine the changes in global gene expression in the brains of newly emerged honeybees after carbendazim exposure during the larval stage. To further understand the effects of carbendazim on the brain development of honeybees, the functions of differentially expressed genes were compared between the treatment and control groups. We found that neuroregulatory genes were down-regulated after carbendazim exposure, which suggest the neurotoxic effects of this fungicide on honeybee nervous system. Carbendazim exposure also altered the expression of genes implicated in metabolism, transport, sensor, and hormone. Notably, larvae in the carbendazim-treated group observed longer time to shift into the dormant pupal state than the control group. Moreover, a low juvenile hormone and high ecdysone titers were found in the treatment group compared to control group. The data is the first report of neurotoxic effects on honeybee caused by carbendazim, and the sublethal carbendazim may disturb honeybee development and is a potential chemical threating the honeybee colonies.

The terpenes of leaves, pollen, and nectar of thyme (Thymus vulgaris) inhibit growth of bee disease-associated microbes

Honey bees are highly prone to infectious diseases, causing colony losses in the worst case. However, they combat diseases through a combination of their innate immune system and social defence behaviours like foraging for health-enhancing plant products (e.g. nectar, pollen and resin). Plant secondary metabolites are not only highly active against bacteria and fungi, they might even enhance selective foraging and feeding decisions in the colony. Here, we tested six major plant terpenes and their corresponding acetates, characterizing six natural Thymus vulgaris chemotypes, for their antimicrobial activity on bacteria associated with European foulbrood. Comparison of the inhibitory activity revealed the highest activity for carvacrol and thymol whereas the acetates mostly did not inhibit bacterial growth. All terpenes and acetates are present in the nectar and pollen of thyme, with pollen containing concentrations higher by several orders of magnitude. The physiological response was tested on forager and freshly emerged bees by means of antennal electroantennography. Both responded much stronger to geraniol and trans-sabinene hydrate compared to carvacrol and thymol. In conclusion, bee-forageable thyme product terpenes (mainly from pollen) yield effective antibiotic activity by reducing the growth of bee disease-associated bacteria and can be detected with different response levels by the honey bees' antennae. This is a further step forward in understanding the complex pathogen-pollinator-plant network.

Transcriptional Control of Honey Bee (Apis mellifera) Major Royal Jelly Proteins by 20-Hydroxyecdysone

One of the first tasks of worker honey bees (Apis mellifera) during their lifetime is to feed the larval offspring. In brief, young workers (nurse bees) secrete a special food jelly that contains a large amount of unique major royal jelly proteins (MRJPs). The regulation of mrjp gene expression is not well understood, but the large upregulation in well-fed nurse bees suggests a tight repression until, or a massive induction upon, hatching of the adult worker bees. The lipoprotein vitellogenin, the synthesis of which is regulated by the two systemic hormones 20-hydroxyecdysone and juvenile hormone, is thought to be a precursor for the production of MRJPs. Thus, the regulation of mrjp expression by the said systemic hormones is likely. This study focusses on the role of 20-hydroxyecdysone by elucidating its effect on mrjp gene expression dynamics. Specifically, we tested whether 20-hydroxyecdysone displayed differential effects on various mrjps. We found that the expression of the mrjps (mrjp1–3) that were finally secreted in large amounts into the food jelly, in particular, were down regulated by 20-hydroxyecdysone treatment, with mrjp3 showing the highest repression value.

Stress and early experience underlie dominance status and division of labour in a clonal insect

Cooperation and division of labour are fundamental in the 'major transitions' in evolution. While the factors regulating cell differentiation in multi-cellular organisms are quite well understood, we are just beginning to unveil the mechanisms underlying individual specialization in cooperative groups of animals. Clonal ants allow the study of which factors influence task allocation without confounding variation in genotype and morphology. Here, we subjected larvae and freshly hatched workers of the clonal ant Platythyrea punctata to different rearing conditions and investigated how these manipulations affected division of labour among pairs of oppositely treated, same-aged clonemates. High rearing temperature, physical stress, injury and malnutrition increased the propensity of individuals to become subordinate foragers rather than dominant reproductives. This is reflected in changed gene regulation: early stages of division of labour were associated with different expression of genes involved in nutrient signalling pathways, metabolism and the phenotypic response to environmental stimuli. Many of these genes appear to be capable of responding to a broad range of stressors. They might link environmental stimuli to behavioural and phenotypic changes and could therefore be more broadly involved in caste differentiation in social insects. Our experiments also shed light on the causes of behavioural variation among genetically identical individuals.

Nematicidal activity of 'major royal jelly protein'-containing glycoproteins from Acacia honey

Parasitic nematodes infect more than two billion people worldwide particularly in developing countries. We previously reported nematicidal activity of natural honey using model nematode Caenorhabditis elegans. In this study, characterization of nematicidal effects of natural honey and its glycoproteins has been carried out. Chromatographically separated honey glycoproteins showed potent anti-C. elegans activity (LD₅₀ = 100 ng proteins/μL). Honey glycoproteins with molecular masses of ∼260 kD and ∼160 kD comprised of 'major royal jelly protein-1'-containing complexes. In these complexes, MRJP1 was present in different glycosylation forms. Quantitative PCR based gene expression assays described molecular functions of C. elegans affected by honey and honey glycoproteins. Expression of 14 gene transcripts associated with key cellular and molecular functions including energy metabolism, cytoskeleton, cell division, transcription and translation was analyzed. Acacia honey exerted a concentration-dependent alteration of gene transcripts involved in the citric acid cycle (mdh-1 and idhg-1) and cytoskeleton (act-1, act-2, and arp6). Likewise, MRJP1-containing glycoproteins caused down-regulation of arp-6 and idhg-1; and up-regulation of act-1 and mdh-1 gene transcripts. Consistent down-regulation of isocitrate dehydrogenase encoding idhg-1 gene which is among the rate-controlling enzymes of the citric acid cycle was considered as main biochemical factor involved in the nematicidal activity of honey and MRJP-containing glycoproteins. Acacia honey suppressed the expression of gene transcripts encoding actin-2, while honey glycoproteins did not. Hence, honey partly exerted anti-C. elegans activity by decreasing the transcription of actin-2 gene transcripts, demonstrated by a defect in the movement and egg laying. Moreover, arp-6 gene transcripts encoding actin-related protein 6 was significantly and constantly down-regulated by honey and honey proteins.

The queen's gut refines with age: longevity phenotypes in a social insect model

BACKGROUND

In social insects, identical genotypes can show extreme lifespan variation providing a unique perspective on age-associated microbial succession. In honey bees, short- and long-lived host phenotypes are polarized by a suite of age-associated factors including hormones, nutrition, immune senescence, and oxidative stress. Similar to other model organisms, the aging gut microbiota of short-lived (worker) honey bees accrue Proteobacteria and are depleted of Lactobacillus and Bifidobacterium, consistent with a suite of host senescence markers. In contrast, long-lived (queen) honey bees maintain youthful cellular function with much lower expression of oxidative stress genes, suggesting a very different host environment for age-associated microbial succession.

RESULTS

We sequenced the microbiota of 63 honey bee queens exploring two chronological ages and four alimentary tract niches. To control for genetic and environmental variation, we quantified carbonyl accumulation in queen fat body tissue as a proxy for biological aging. We compared our results to the age-specific microbial succession of worker guts. Accounting for queen source variation, two or more bacterial species per niche differed significantly by queen age. Biological aging in queens was correlated with microbiota composition highlighting the relationship of microbiota with oxidative stress. Queens and workers shared many major gut bacterial species, but differ markedly in community structure and age succession. In stark contrast to aging workers, carbonyl accumulation in queens was significantly associated with increased Lactobacillus and Bifidobacterium and depletion of various Proteobacteria.

CONCLUSIONS

We present a model system linking changes in gut microbiota to diet and longevity, two of the most confounding variables in human microbiota research. The pattern of age-associated succession in the queen microbiota is largely the reverse of that demonstrated for workers. The guts of short-lived worker phenotypes are progressively dominated by three major Proteobacteria, but these same species were sparse or significantly depleted in long-lived queen phenotypes. More broadly, age-related changes in the honey bee microbiota reflect the regulatory anatomy of reproductive host metabolism. Our synthesis suggests that the evolution of colony-level reproductive physiology formed the context for host-microbial interactions and age-related succession of honey bee microbiota.

Gene expression changes in honey bees induced by sublethal imidacloprid exposure during the larval stage

Honey bee larvae exposed to sublethal doses of imidacloprid show behavioural abnormalities as adult insects. Previous studies have demonstrated that this phenomenon originates from abnormal neural development in response to imidacloprid exposure. Here, we further investigated the global gene expression changes in the heads of newly emerged adults and observed that 578 genes showed more than 2-fold changes in gene expression after imidacloprid exposure. This information might aid in understanding the effects of pesticides on the health of pollinators. For example, the genes encoding major royal jelly proteins (MRJPs), a group of multifunctional proteins with significant roles in the sustainable development of bee colonies, were strongly downregulated. These downregulation patterns were further confirmed through analyses using quantitative reverse transcription-polymerase chain reaction on the heads of 6-day-old nurse bees. To our knowledge, this study is the first to demonstrate that sublethal doses of imidacloprid affect mrjp expression and likely weaken bee colonies.

Comparative analyses of the major royal jelly protein gene cluster in three Apis species with long amplicon sequencing

The western honeybee, Apis mellifera is a prominent model organism in the field of sociogenomics and a recent upgrade substantially improved annotations of the reference genome. Nevertheless, genome assemblies based on short-sequencing reads suffer from problems in regions comprising e.g. multi-copy genes. We used single-molecule nanopore-based sequencing with extensive read-lengths to reconstruct the organization of the major royal jelly protein (mrjp) region in three species of the genus Apis. Long-amplicon sequencing provides evidence for lineage-specific evolutionary fates of Apis mrjps. Whereas the most basal species, A. florea, seems to encode ten mrjps, different patterns of gene loss and retention were observed for A. mellifera and A. dorsata. Furthermore, we show that a previously reported pseudogene in A. mellifera, mrjp2-like, is an assembly artefact arising from short read sequencing.

Honey, Propolis, and Royal Jelly: A Comprehensive Review of Their Biological Actions and Health Benefits

BACKGROUND

There are several health benefits that honeybee products such as honey, propolis, and royal jelly claim toward various types of diseases in addition to being food.

SCOPE AND APPROACH

In this paper, the effects of honey, propolis, and royal jelly on different metabolic diseases, cancers, and other diseases have been reviewed. The modes of actions of these products have also been illustrated for purposes of better understanding.

KEY FINDINGS AND CONCLUSIONS

An overview of honey, propolis, and royal jelly and their biological potentials was highlighted. The potential health benefits of honey, such as microbial inhibition, wound healing, and its effects on other diseases, are described. Propolis has been reported to have various health benefits related to gastrointestinal disorders, allergies, and gynecological, oral, and dermatological problems. Royal jelly is well known for its protective effects on reproductive health, neurodegenerative disorders, wound healing, and aging. Nevertheless, the exact mechanisms of action of honey, propolis, and royal jelly on the abovementioned diseases and activities have not been not fully elucidated, and further research is warranted to explain their exact contributions.

Therapeutic Properties of Bioactive Compounds from Different Honeybee Products

Honeybees produce honey, royal jelly, propolis, bee venom, bee pollen, and beeswax, which potentially benefit to humans due to the bioactives in them. Clinical standardization of these products is hindered by chemical variability depending on honeybee and botanical sources, but different molecules have been isolated and pharmacologically characterized. Major honey bioactives include phenolics, methylglyoxal, royal jelly proteins (MRJPs), and oligosaccharides. In royal jelly there are antimicrobial jelleins and royalisin peptides, MRJPs, and hydroxy-decenoic acid derivatives, notably 10-hydroxy-2-decenoic acid (10-HDA), with antimicrobial, anti-inflammatory, immunomodulatory, neuromodulatory, metabolic syndrome preventing, and anti-aging activities. Propolis contains caffeic acid phenethyl ester and artepillin C, specific of Brazilian propolis, with antiviral, immunomodulatory, anti-inflammatory and anticancer effects. Bee venom consists of toxic peptides like pain-inducing melittin, SK channel blocking apamin, and allergenic phospholipase A2. Bee pollen is vitaminic, contains antioxidant and anti-inflammatory plant phenolics, as well as antiatherosclerotic, antidiabetic, and hypoglycemic flavonoids, unsaturated fatty acids, and sterols. Beeswax is widely used in cosmetics and makeup. Given the importance of drug discovery from natural sources, this review is aimed at providing an exhaustive screening of the bioactive compounds detected in honeybee products and of their curative or adverse biological effects.

Production of Knockout Mutants by CRISPR/Cas9 in the European Honeybee, Apis mellifera L

The European honeybee (Apis mellifera L.) is used as a model organism in studies of the molecular and neural mechanisms underlying social behaviors and/or advanced brain functions. The entire honeybee genome has been sequenced, which has further advanced molecular biologic studies of the honeybee. Functions of genes of interest, however, remain largely to be elucidated in the honeybee due to the lack of effective reverse genetic methods. Moreover, genetically modified honeybees must be maintained under restricted laboratory conditions due to legal restrictions, further complicating the application of reverse genetics to this species. Here we applied CRISPR/Cas9 to the honeybee to develop an effective reverse genetic method. We targeted major royal jelly protein 1 (mrjp1) for genome editing, because this gene is predominantly expressed in adult workers and its mutation is not expected to affect normal development. By injecting sgRNA and Cas9 mRNA into 57 fertilized embryos collected within 3 h after oviposition, we successfully created six queens, one of which produced genome-edited male offspring. Of the 161 males produced, genotyping demonstrated that the genome was edited in 20 males. All of the processes necessary for producing these genome-edited queens and males were performed in the laboratory. Therefore, we developed essential techniques to create knockout honeybees by CRISPR/Cas9. Our findings also suggested that mrjp1 is dispensable for normal male development, at least till the pupal stage. This new technology could pave the way for future functional analyses of candidate genes involved in honeybee social behaviors.