The worker honeybee fat body proteome is extensively remodeled preceding a major life-history transition

Life-history stage determines the diet of ectoparasitic mites on their honey bee hosts

Ectoparasitic mites of the genera Varroa and Tropilaelaps have evolved to exclusively exploit honey bees as food sources during alternating dispersal and reproductive life history stages. Here we show that the primary food source utilized by Varroa destructor depends on the host life history stage. While feeding on adult bees, dispersing V. destructor feed on the abdominal membranes to access to the fat body as reported previously. However, when V. destructor feed on honey bee pupae during their reproductive stage, they primarily consume hemolymph, indicated by wound analysis, preferential transfer of biostains, and a proteomic comparison between parasite and host tissues. Biostaining and proteomic results were paralleled by corresponding findings in Tropilaelaps mercedesae, a mite that only feeds on brood and has a strongly reduced dispersal stage. Metabolomic profiling of V. destructor corroborates differences between the diet of the dispersing adults and reproductive foundresses. The proteome and metabolome differences between reproductive and dispersing V. destructor suggest that the hemolymph diet coincides with amino acid metabolism and protein synthesis in the foundresses while the metabolism of non-reproductive adults is tuned to lipid metabolism. Thus, we demonstrate within-host dietary specialization of ectoparasitic mites that coincides with life history of hosts and parasites.

Effects of Virgin Coconut Oil-Enriched Diet on Immune and Antioxidant Enzymatic Activity, Fat and Vitellogenin Contents in Newly Emerged and Forager Bees (Apis mellifera L.) Reared in Cages

Searching for artificial diets positively affecting the survival, immune and antioxidant systems of honey bees is one of main challenges occurring in beekeeping. Among nutrients, lipids play a significant role in insect nutrition as structural components in cell membranes, energy sources and reserves, and are involved in many physiological processes. In this context, the aim of this work was to investigate the effect of 0.5% and 1% coconut oil-enriched diet administration on newly emerged and forager bees survival rate, feed intake, immune system, antioxidant system and both fat and vitellogenin content. In newly emerged bees, supplementation with 1% coconut oil determined a decrease in feed consumption, an increase in survival rate from the 3rd to 14th day of feeding, a short-term decrease in phenoloxidase activity, an increase in body fat and no differences in vitellogenin content. Conversely, supplementation with 0.5% coconut oil determined an increase in survival rate from the 3rd to 15th day of feeding and an increase in fat content in the long term (i.e., 20 days). Regarding the forager bee diet, enrichment with 0.5% and 1% coconut oil only determined an increase in fat content. Therefore, supplementation with coconut oil in honey bee diets at low percentages (0.5 and 1%) determines fat gain. Further investigations to evaluate the use of such supplement foods to prevent the fat loss of weak families during winter are desirable.

New insight into molecular mechanisms underlying division of labor in honeybees

Honeybees are highly organized eusocial insects displaying a distinct division of labor. Juvenile hormone (JH) has long been hypothesized to be the major driver of behavioral transitions. However, more and more experiments in recent years have suggested that the role of this hormone is not as fundamental as hypothesized. Vitellogenin, a common egg yolk precursor protein, seems to be the major regulator of division of labor in honeybees, in connection with nutrition and the neurohormone and transmitter octopamine. Here, we review the role of vitellogenin in controlling honeybee division of labor and its modulation by JH, nutrition, and the catecholamine octopamine.

Antimicrobial Activity of Apidermin 2 from the Honeybee Apis mellifera

Apidermins (APDs) are known as structural cuticular proteins in insects, but their additional roles are poorly understood. In this study, we characterized the honeybee, Apis mellifera, APD 2 (AmAPD 2), which displays activity suggesting antimicrobial properties. In A. mellifera worker bees, the AmAPD 2 gene is transcribed in the epidermis, hypopharyngeal glands, and fat body, and induced upon microbial ingestion. Particularly in the epidermis of A. mellifera worker bees, the AmAPD 2 gene showed high expression and responded strongly to microbial challenge. Using a recombinant AmAPD 2 peptide, which was produced in baculovirus-infected insect cells, we showed that AmAPD 2 is heat-stable and binds to live bacteria and fungi as well as carbohydrates of microbial cell wall molecules. This binding action ultimately induced structural damage to microbial cell walls, which resulted in microbicidal activity. These findings demonstrate the antimicrobial role of AmAPD 2 in honeybees.

Worker bees (Apis mellifera) deprived of pollen in the first week of adulthood exhibit signs of premature aging

Pollinator populations, including bees, are in rapid decline in many parts of the world, raising concerns over the future of ecosystems and food production. Among the factors involved in these declines, poor nutrition deserves attention. The diet consumed by adult worker honeybees (Apis mellifera) is crucial for their behavioral maturation, i.e., the progressive division of labor they perform, such as nurse bees initially and later in life as foragers. Poor pollen nutrition is known to reduce the workers' lifespan, but the underlying physiological and genetic mechanisms are not fully understood. Here we investigate how the lack of pollen in the diet of workers during their first week of adult life can affect age-related phenotypes. During the first seven days of adult life, newly emerged workers were fed either a pollen-deprived (PD) diet mimicking that of an older bee, or a control pollen-rich (PR) diet, as typically consumed by young bees. The PD-fed bees showed alterations in their fat body transcriptome, such as a switch from a protein-lipid based metabolism to a carbohydrate-based metabolism, and a reduced expression of genes involved with immune response. The absence of pollen in the diet also led to an accumulation of oxidative stress markers in fat body tissue and alterations in the cuticular hydrocarbon profiles, which became similar to those of chronologically older bees. Together, our data indicate that the absence of pollen during first week of adulthood triggers the premature onset of an aging-related worker phenotype.

The trophocytes and oenocytes of worker and queen honey bees (Apis mellifera) exhibit distinct age-associated transcriptome profiles

Despite the identical genomic context, trophocytes and oenocytes in worker bees exhibit aging-related phenotypes, in contrast to the longevity phenotypes in queen bees. To explore this phenomenon at the molecular level, we evaluated the age-associated transcriptomes of trophocytes and oenocytes in worker bees and queen bees using high-throughput RNA-sequencing technology (RNA-seq). The results showed that (i) while gene expression profiles were different between worker and queen bees, they remained similar between young and old counterparts; (ii) worker bees express a high proportion of low-abundance genes, whereas queen bee transcriptomes display a high proportion of moderate-expression genes; (iii) genes were upregulated to a greater extent in queen bees vs. worker bees; and (iv) distinct aging-related and longevity-related candidate genes were found in worker and queen bees. These results provide new insights into the cellular aging and longevity of trophocytes and oenocytes in honey bees. Identification of aging-associated biomarker genes also constitutes a basis for translational research of aging in higher organisms.

Evaluating Effects of a Critical Micronutrient (24-Methylenecholesterol) on Honey Bee Physiology

Although poor nutrition is cited as one of the crucial factors in global pollinator decline, the requirements and role of several important nutrients (especially micronutrients) in honey bees are not well understood. Micronutrients, viz. phytosterols, play a physiologically vital role in insects as precursors of important molting hormones and building blocks of cellular membranes. There is a gap in comprehensive understanding of the impacts of dietary sterols on honey bee physiology. In the present study, we investigated the role of 24-methylenecholesterol-a key phytosterol-in honey bee nutritional physiology. Artificial diets with varying concentrations of 24-methylenecholesterol (0%, 0.1%. 0.25%, 0.5%, 0.75%, and 1% dry diet weight) were formulated and fed to honey bees in a laboratory cage experiment. Survival, diet consumption, head protein content, and abdominal lipid contents were significantly higher in dietary sterol-supplemented bees. Our findings provide additional insights regarding the role of this important sterol in honey bee nutritional physiology. The insights gleaned from this study could also advance the understanding of sterol metabolism and regulation in other bee species that are dependent on pollen for sterols, and assist in formulation of a more complete artificial diet for honey bees (Apis mellifera Linnaeus, 1758) (Hymenoptera: Apidae).

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.

Appetite is correlated with octopamine and hemolymph sugar levels in forager honeybees

Insects have rapidly changing energy demands, so they primarily rely on hemolymph and other carbohydrates to carry out life activities. However, how gustatory responsiveness and hemolymph sugar levels coordinate with one another to maintain energetic homeostasis in insects remains largely unknown for the highly social honeybee that goes through large physiological and behavioral changes. The potential role of biogenic amines and neuropeptides in the connection between the regulation of appetite and fluctuating sugar levels in the hemolymph, due to starvation, as the bee ages, was investigated. The largest appetite increase due to the starvation treatment was within the forager age class and this corresponded with an increase in octopamine levels in the brain along with a decline in hemolymph sugar levels. Adipokinetic hormone (AKH) was found in very small quantities in the brain and there were no significant changes in response to starvation treatment. Our findings suggest that the particularly dynamic levels of hemolymph sugar levels may serve as a monitor of the forager honeybee energetic state. Therefore, there may be a pathway in forager bees via octopamine responsible for their precise precipitous regulation of appetite, but to determine cause and effect relationships further investigation is needed.

Cellular energy metabolism maintains young status in old queen honey bees (Apis mellifera)

Trophocytes and oenocytes of queen honey bees are used in studies of cellular longevity, but their cellular energy metabolism with age is poorly understood. In this study, the molecules involved in cellular energy metabolism were evaluated in the trophocytes and oenocytes of young and old queen bees. The findings indicated that there were no significant differences between young and old queen bees in β-oxidation, glycolysis, and protein synthesis. These results indicate that the cellular energy metabolism of trophocytes and oenocytes in old queen bees is similar to young queen bees and suggests that maintaining cellular energy metabolism in a young status may be associated with the longevity of queen bees. Fat and glycogen accumulation increased with age indicating that old queen bees are older than young queen bees.

Reproductive parasitism by worker honey bees suppressed by queens through regulation of worker mandibular secretions

Social cohesion in social insect colonies can be achieved through the use of chemical signals whose production is caste-specific and regulated by social contexts. In honey bees, queen mandibular gland pheromones (QMP) maintain reproductive dominance by inhibiting ovary activation and production of queen-like mandibular gland signals in workers. We investigated whether honey bee queens can control reproductively active workers of the intraspecific social parasite Apis mellifera capensis, parasitising A. m. scutellata host colonies. Our results show that the queen’s QMP suppresses ovarian activation and inhibits the production of QMP pheromone signals by the parasitic workers, achieved through differential expression of enzymes involved in the biosynthesis of these pheromones at two points in the biosynthetic pathway. This is the first report showing that honey bee queens can regulate reproduction in intraspecific social parasites and deepens our understanding of the molecular mechanisms involved in the regulation of worker reproduction in social insects.

Proteomics Improves the New Understanding of Honeybee Biology

The honeybee is one of the most valuable insect pollinators, playing a key role in pollinating wild vegetation and agricultural crops, with significant contribution to the world's food production. Although honeybees have long been studied as model for social evolution, honeybee biology at the molecular level remained poorly understood until the year 2006. With the availability of the honeybee genome sequence and technological advancements in protein separation, mass spectrometry, and bioinformatics, aspects of honeybee biology such as developmental biology, physiology, behavior, neurobiology, and immunology have been explored to new depths at molecular and biochemical levels. This Review comprehensively summarizes the recent progress in honeybee biology using proteomics to study developmental physiology, task transition, and physiological changes in some of the organs, tissues, and cells based on achievements from the authors' laboratory in this field. The research advances of honeybee proteomics provide new insights for understanding of honeybee biology and future research directions.

Mitochondrial capacity, oxidative damage and hypoxia gene expression are associated with age-related division of labor in honey bee (Apis mellifera L.) workers

During adult life, honey bee workers undergo a succession of behavioral states. Nurse bees perform tasks inside the nest, and when they are about 2-3 weeks old they initiate foraging. This switch is associated with alterations in diet, and with the levels of juvenile hormone and vitellogenin circulating in hemolymph. It is not clear whether this behavioral maturation involves major changes at the cellular level, such as mitochondrial activity and the redox environment in the head, thorax and abdomen. Using high-resolution respirometry, biochemical assays and RT-qPCR, we evaluated the association of these parameters with this behavioral change. We found that tissues from the head and abdomen of nurses have a higher oxidative phosphorylation capacity than those of foragers, while for the thorax we found the opposite situation. As higher mitochondrial activity tends to generate more H₂O₂, and H₂O₂ is known to stabilize HIF-1α, this would be expected to stimulate hypoxia signaling. The positive correlation that we observed between mitochondrial activity and hif-1α gene expression in abdomen and head tissue of nurses would be in line with this hypothesis. Higher expression of antioxidant enzyme genes was observed in foragers, which could explain their low levels of protein carbonylation. No alterations were seen in nitric oxide (NO) levels, suggesting that NO signaling is unlikely to be involved in behavioral maturation. We conclude that the behavioral change seen in honey bee workers is reflected in differential mitochondrial activities and redox parameters, and we consider that this can provide insights into the underlying aging process.

PROTEINS OF THE INTEGUMENTARY SYSTEM OF THE HONEYBEE, Apis mellifera

The integument of insects and other arthropods is composed of an inner basal lamina coated by the epidermis, which secretes the bulk of the outer integument layer, the cuticle. The genome sequencing of several insect species has allowed predicting classes of proteins integrating the cuticle. However, only a small proportion of them, as well as other proteins in the integumentary system, have been validated. Using two-dimensional gel electrophoresis coupled with mass spectrometry, we identified 45 different proteins in a total of 112 selected gel spots derived from thoracic integument samples of developing honeybee workers, including 14 cuticular proteins (AmelCPR 3, AmelCPR 12, AmelCPR 16, AmelCPR 27, apidermin 2, apidermin 3, endocuticle structural glycoprotein SgAbd-8-like, LOC100577363, LOC408365, LOC413679, LOC725454, LOC100576916, LOC725838, and peritrophin 3-C analogous). Gene ontology functional analysis revealed that the higher proportions of the identified proteins have molecular functions related to catalytic and structural molecule activities, are involved in metabolic biological processes, and pertain to the protein class of structural or cytoskeletal proteins and hydrolases. It is noteworthy that 26.7% of the identified proteins, including five cuticular proteins, were revealed as protein species resulting from allelic isoforms or derived from posttranslational modifications. Also, 66.7% of the identified cuticular proteins were expressed in more than one developmental phase, thus indicating that they are part of the larval, pupal, and adult cuticle. Our data provide experimental support for predicted honeybee gene products and new information on proteins expressed in the developing integument.

Cellular degradation activity is maintained during aging in long-living queen bees

Queen honeybees (Apis mellifera) have a much longer lifespan than worker bees. Whether cellular degradation activity is involved in the longevity of queen bees is unknown. In the present study, cellular degradation activity was evaluated in the trophocytes and oenocytes of young and old queen bees. The results indicated that (i) 20S proteasome activity and the size of autophagic vacuoles decreased with aging, and (ii) there were no significant differences between young and old queen bees with regard to 20S proteasome expression or efficiency, polyubiquitin aggregate expression, microtubule-associated protein 1 light chain 3-II (LC3-II) expression, 70 kDa heat shock cognate protein (Hsc70) expression, the density of autophagic vacuoles, p62/SQSTM1 expression, the activity or density of lysosomes, or molecular target of rapamycin expression. These results indicate that cellular degradation activity maintains a youthful status in the trophocytes and oenocytes of queen bees during aging and that cellular degradation activity is involved in maintaining the longevity of queen bees.

DNA base modifications in honey bee and fruit fly genomes suggest an active demethylation machinery with species- and tissue-specific turnover rates

Well-known epigenetic DNA modifications in mammals include the addition of a methyl group and a hydroxyl group to cytosine, resulting in 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) respectively. In contrast, the abundance and the functional implications of these modifications in invertebrate model organisms such as the honey bee (Apis mellifera) and the fruit fly (Drosophila melanogaster) are not well understood. Here we show that both adult honey bees and fruit flies contain 5mC and also 5hmC. Using a highly sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) technique, we quantified 5mC and 5hmC in different tissues of adult honey bee worker castes and in adult fruit flies. A comparison of our data with reports from human and mouse shed light on notable differences in 5mC and 5hmC levels between tissues and species.

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Reporting cytosine modifications in uncharacterized tissues, phenotypes and species.

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Quantification of 5mC and 5hmC suggests species-specific roles and turnover.​

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Low levels of 5hmC relative to 5mC and cytosine in honey bees compared to mammals.

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Honey bee abdominal tissues are richer in5hmC than the brain.

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We found a higher 5hmC to 5mC ratio in fruit flies as compared to the honey bee.

Genomic Analyses Reveal Demographic History and Temperate Adaptation of the Newly Discovered Honey Bee Subspecies Apis mellifera sinisxinyuan n. ssp

Studying the genetic signatures of climate-driven selection can produce insights into local adaptation and the potential impacts of climate change on populations. The honey bee (Apis mellifera) is an interesting species to study local adaptation because it originated in tropical/subtropical climatic regions and subsequently spread into temperate regions. However, little is known about the genetic basis of its adaptation to temperate climates. Here, we resequenced the whole genomes of ten individual bees from a newly discovered population in temperate China and downloaded resequenced data from 35 individuals from other populations. We found that the new population is an undescribed subspecies in the M-lineage of A. mellifera (Apis mellifera sinisxinyuan). Analyses of population history show that long-term global temperature has strongly influenced the demographic history of A. m. sinisxinyuan and its divergence from other subspecies. Further analyses comparing temperate and tropical populations identified several candidate genes related to fat body and the Hippo signaling pathway that are potentially involved in adaptation to temperate climates. Our results provide insights into the demographic history of the newly discovered A. m. sinisxinyuan, as well as the genetic basis of adaptation of A. mellifera to temperate climates at the genomic level. These findings will facilitate the selective breeding of A. mellifera to improve the survival of overwintering colonies.

Cytosine modifications in the honey bee (Apis mellifera) worker genome

Epigenetic changes enable genomes to respond to changes in the environment, such as altered nutrition, activity, or social setting. Epigenetic modifications, thereby, provide a source of phenotypic plasticity in many species. The honey bee (Apis mellifera) uses nutritionally sensitive epigenetic control mechanisms in the development of the royal caste (queens) and the workers. The workers are functionally sterile females that can take on a range of distinct physiological and/or behavioral phenotypes in response to environmental changes. Honey bees have a wide repertoire of epigenetic mechanisms which, as in mammals, include cytosine methylation, hydroxymethylated cytosines, together with the enzymatic machinery responsible for these cytosine modifications. Current data suggests that honey bees provide an excellent system for studying the “social repertoire” of the epigenome. In this review, we elucidate what is known so far about the honey bee epigenome and its mechanisms. Our discussion includes what may distinguish honey bees from other model animals, how the epigenome can influence worker behavioral task separation, and how future studies can answer central questions about the role of the epigenome in social behavior.

Soluble proteins of chemical communication: an overview across arthropods

Detection of chemical signals both in insects and in vertebrates is mediated by soluble proteins, highly concentrated in olfactory organs, which bind semiochemicals and activate, with still largely unknown mechanisms, specific chemoreceptors. The same proteins are often found in structures where pheromones are synthesized and released, where they likely perform a second role in solubilizing and delivering chemical messengers in the environment. A single class of soluble polypeptides, called Odorant-Binding Proteins (OBPs) is known in vertebrates, while two have been identified in insects, OBPs and CSPs (Chemosensory Proteins). Despite their common name, OBPs of vertebrates bear no structural similarity with those of insects. We observed that in arthropods OBPs are strictly limited to insects, while a few members of the CSP family have been found in crustacean and other arthropods, where however, based on their very limited numbers, a function in chemical communication seems unlikely. The question we address in this review is whether another class of soluble proteins may have been adopted by other arthropods to perform the role of OBPs and CSPs in insects. We propose that lipid-transporter proteins of the Niemann-Pick type C2 family could represent likely candidates and report the results of an analysis of their sequences in representative species of different arthropods.

Energy-regulated molecules maintain young status in the trophocytes and fat cells of old queen honeybees

Queen honeybees (Apis mellifera) have much longer lifespans than worker bees. Energy-regulated molecules in the trophocytes and fat cells of workers during aging have been determined, but are unknown in queen bees. In the present study, energy-regulated molecules were evaluated in the trophocytes and fat cells of young and old queen bees. Adenosine monophosphate-activated protein kinase α2 (AMPK-α2), phosphorylated AMPK-α2 (pAMPK-α2), and cAMP-specific phosphodiesterases activity increased with aging. The pAMPK-α2/AMPK-α2 ratio and AMPK activity; adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) concentrations; the ADP/ATP ratio and the AMP/ATP ratio; the cyclic adenosine monophosphate concentration; forkhead box protein O expression; Silent information regulator T1 (SirT1) expression and activity; and peroxisome proliferator-activated receptor-α (PPAR-α) expression were not significantly different between young and old queen bees. These results show that energy-regulated molecules maintain a youthful status in the trophocytes and fat cells of queen bees during aging. These cells seem to have longevity-promoting mechanisms and may clarify the secret of longevity in queen bees.

The dietary proportion of essential amino acids and Sir2 influence lifespan in the honeybee

Dietary essential amino acids have an important influence on the lifespan and fitness of animals. The expression of the NAD(+)-dependent histone deacetylase, Sir2, can be influenced by diet, but its role in the extension of lifespan has recently been challenged. Here, we used the honeybee to test how the dietary balance of carbohydrates and essential amino acids and/or Sir2 affected lifespan. Using liquid diets varying in their ratio of essential amino acids to carbohydrate (EAA:C), we found that adult worker bees fed diets high in essential amino acids (≥1:10) had shorter lifespans than bees fed diets containing low levels of dietary amino acids. Bees fed a 1:500 EAA:C diet lived longer and, in contrast to bees fed any of the other diets, expressed Sir2 at levels tenfold higher or more than bees fed a 1:5 EAA:C diet. When bees were fed the 1:500 diet, small interfering RNA (siRNA)-mediated knock-down of Sir2 expression shortened lifespan but did not reduce survival to the same extent as the 1:5 diet, indicating that Sir2 contributes to mechanisms that determine lifespan in response to differences in macronutrient intake but is not the sole determinant. These data show that the ratio of dietary amino acids to carbohydrate influences Sir2 expression and clearly demonstrate that Sir2 is one of the factors that can determine honeybee lifespan. We propose that effects of dietary amino acids and Sir2 on lifespan may depend on the simultaneous activation of multiple nutrient sensors that respond to relative levels of essential amino acids and carbohydrates.

Oxidative stress and anti-oxidant enzyme activities in the trophocytes and fat cells of queen honeybees (Apis mellifera)

Trophocytes and fat cells of queen honeybees have been used for delayed cellular senescence studies, but their oxidative stress and anti-oxidant enzyme activities with advancing age are unknown. In this study, we assayed reactive oxygen species (ROS) and anti-oxidant enzymes in the trophocytes and fat cells of young and old queens. Young queens had lower ROS levels, lower superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, and higher thioredoxin reductase (TR) activity compared to old queens. These results show that oxidative stress and anti-oxidant enzyme activities in trophocytes and fat cells increase with advancing age in queens and suggest that an increase in oxidative stress and a consequent increase in stress defense mechanisms are associated with the longevity of queen honeybees.

Genomic analysis of the interactions between social environment and social communication systems in honey bees (Apis mellifera)

Social context is often a primary regulator of social behavior, but genes that affect or are affected by social context have rarely been investigated. In social insects, caste specific pheromones are key modulators of social behavior, e.g., in honey bees the queen mandibular gland (MG) pheromone mediates reproductive dominance, its absence prompting ovary activation and queen pheromone production in workers. Here, we investigate the effect of social environment on genome-wide expression patterns in the MG, to determine how social context modulates expression of genes that, in turn alter social environment. We used microarrays to examine the MGs of virgin and mated queens, and queenright (QR) and queenless (QL) workers with or without activated ovaries. Approximately 2554 transcripts were significantly differentially expressed among these groups, with caste and social context being the main regulators of gene expression patterns, while physiological state (ovary activation) only minimally affecting gene expression. Thus, social context strongly regulates expression of genes, which, in turn, shape social environment. Among these, 25 genes that are putatively involved in caste selective production of the fatty-acid derived MG pheromone were differentially expressed in queens and workers. These genes whose functions correspond with enzymatic or transport processes emphasize the occurrence of disparate pheromone biosynthetic pathways for queens and workers, adding another dimension regarding the regulation of these important pheromones. Gene ontology analysis also revealed genes of different functional categories whose expression was impacted by caste or by the social environment, suggesting that the MG has broader functions than pheromone biosynthesis.

Comparative proteomics and expression analysis of five genes in Epicauta chinensis larvae from the first to fifth instar

Blister beetle is an important insect model for both medicinal and pure research. Previous research has mainly focused on its biology and biochemistry, but very little data is yet available in the molecular biology. This study uses differential proteomics technology to analyze the soluble proteins extracted from each of the 5 instars larvae of Epicauta chinensis. 42 of the differentially-expressed proteins were identified successfully by MALDI-TOF/TOF-MS. Some of these proteins' function and their expression profiles are analyzed. Our analysis revealed dynamics regulation of the following proteins: Axin-like protein pry-1 (APR-1), dihydrolipoyl dehydrogenase (DLD), vitellogenin (Vg) and lysozyme C (Lmz-S). APR-1 negatively regulates the Wnt signaling pathway. Its overexpression could result in embryo, leg, eye and ovary ectopica or malformation. DLD catalyzes the pyruvate into acetyl-CoA, the latter is the starting material of juvenile hormone (JH) and ipsdienol biosynthesis through the MVA pathway in insects. While Vg synthesis can be regulated by JH and stimulated by food factors. So DLD may affect the synthesis of JH, ipsdienol and Vg indirectly. The activity of lysozyme is an indicator of the immunity. Nutrition/food should be taken into account for its potential role during the development of larva in the future. Among the five genes and their corresponding proteins' expression, only hsc70 gene showed a good correspondence with the protein level. This reflects the fluctuating relationship between mRNA and protein levels.

Transcriptional markers of sub-optimal nutrition in developing Apis mellifera nurse workers

BACKGROUND

Honey bees (Apis mellifera) contribute substantially to the worldwide economy and ecosystem health as pollinators. Pollen is essential to the bee's diet, providing protein, lipids, and micronutrients. The dramatic shifts in physiology, anatomy, and behavior that accompany normal worker development are highly plastic and recent work demonstrates that development, particularly the transition from nurse to foraging roles, is greatly impacted by diet. However, the role that diet plays in the developmental transition of newly eclosed bees to nurse workers is poorly understood. To further understand honey bee nutrition and the role of diet in nurse development, we used a high-throughput screen of the transcriptome of 3 day and 8 day old worker bees fed either honey and stored pollen (rich diet) or honey alone (poor diet) within the hive. We employed a three factor (age, diet, age x diet) analysis of the transcriptome to determine whether diet affected nurse worker physiology and whether poor diet altered the developmental processes normally associated with aging.

RESULTS

Substantial changes in gene expression occurred due to starvation. Diet-induced changes in gene transcription occurring in younger bees were largely a subset of those occurring in older bees, but certain signatures of starvation were only evident 8 day old workers. Of the 18,542 annotated transcripts in the A. mellifera genome, 150 transcripts exhibited differential expression due to poor diet at 3d of age compared with 17,226 transcripts that differed due to poor diet at 8d of age, and poor diet caused more frequent down-regulation of gene expression in younger bees compared to older bees. In addition, the age-related physiological changes that accompanied early adult development differed due to the diet these young adult bees were fed. More frequent down-regulation of gene expression was observed in developing bees fed a poor diet compared to those fed an adequate diet. Functional analyses also suggest that the physiological and developmental processes occurring in well-fed bees are vastly different than those occurring in pollen deprived bees. Our data support the hypothesis that poor diet causes normal age-related development to go awry.

CONCLUSION

Poor nutrition has major consequences for the expression of genes underlying the physiology and age-related development of nurse worker bees. More work is certainly needed to fully understand the consequences of starvation and the complex biology of nutrition and development in this system, but the genes identified in the present study provide a starting point for understanding the consequences of poor diet and for mitigating the economic costs of colony starvation.

Honey bee protein atlas at organ-level resolution

Genome sequencing has provided us with gene lists but cannot tell us where and how their encoded products work together to support life. Complex organisms rely on differential expression of subsets of genes/proteins in organs and tissues, and, in concert, evolved to their present state as they function together to improve an organism's overall reproductive fitness. Proteomics studies of individual organs help us understand their basic functions, but this reductionist approach misses the larger context of the whole organism. This problem could be circumvented if all the organs in an organism were comprehensively studied by the same methodology and analyzed together. Using honey bees (Apis mellifera L.) as a model system, we report here an initial whole proteome of a complex organism, measuring 29 different organ/tissue types among the three honey bee castes: queen, drone, and worker. The data reveal that, e.g., workers have a heightened capacity to deal with environmental toxins and queens have a far more robust pheromone detection system than their nestmates. The data also suggest that workers altruistically sacrifice not only their own reproductive capacity but also their immune potential in favor of their queen. Finally, organ-level resolution of protein expression offers a systematic insight into how organs may have developed.

Insect omics research coming of age1This review is part of a virtual symposium on recent advances in understanding a variety of complex regulatory processes in insect physiology and endocrinology, including development, metabolism, cold hardiness, food intake and digestion, and diuresis, through the use of omics technologies in the postgenomic era

As more and more insect genomes are fully sequenced and annotated, omics technologies, including transcriptomic, proteomic, peptidomics, and metobolomic profiling, as well as bioinformatics, can be used to exploit this huge amount of sequence information for the study of different biological aspects of insect model organisms. Omics experiments are an elegant way to deliver candidate genes, the function of which can be further explored by genetic tools for functional inactivation or overexpression of the genes of interest. Such tools include mainly RNA interference and are currently being developed in diverse insect species. In this manuscript, we have reviewed how omics technologies were integrated and applied in insect biology.