Multiple virus infections in the honey bee and genome divergence of honey bee viruses

Using uniplex RT-PCR we screened honey bee colonies for the presence of several bee viruses, including black queen cell virus (BQCV), deformed wing virus (DWV), Kashmir bee virus (KBV), and sacbrood virus (SBV), and described the detection of mixed virus infections in bees from these colonies. We report for the first time that individual bees can harbor four viruses simultaneously. We also developed a multiplex RT-PCR assay for the simultaneous detection of multiple bee viruses. The feasibility and specificity of the multiplex RT-PCR assay suggests that this assay is an effective tool for simultaneous examination of mixed virus infections in bee colonies and would be useful for the diagnosis and surveillance of honey bee viral diseases in the field and laboratory. Phylogenetic analysis of putative helicase and RNA-dependent RNA polymerase (RdRp) encoded by viruses reveal that DWV and SBV fall into a same clade, whereas KBV and BQCV belong to a distinct lineage with other picorna-like viruses that infect plants, insects and vertebrates. Results from field surveys of these viruses indicate that mixed infections of BQCV, DWV, KBV, and SBV in the honey bee probably arise due to broad geographic distribution of viruses.     

蜜蜂全基因组出笼前后

在2006年10月26日,期待已久的蜜蜂的基因组序列在英国杂志《自然》上发表了。这一事件对于全世界蜜蜂生物学家来说,标志着蜜蜂研究“后基因组时代”的开始。这一重大项目由倍乐医学院完成,耗资800万美元,历时2年。而实际上对于基因组的注释又经过近2年的时间,由代表15个国家、来自64个实验室的170名科学家完成。这一等待是值得的基因组序列最终发表后,生物学家通过互联网能做他们自己的“数据采掘”,用这一可得的公共资源验证自己的假说。事实上,在蜜蜂基因组文章在《自然》上发表的当周,其姊妹刊上发表的约50篇相关论文中,有一半以上是基于生物信息学的研究,这些刊物包括《科学》、《基因组研究》、《美国国家科学院院报》及《昆虫分子生物学》。蜜蜂与人类享有一些共性劳动分工,复杂的通信系统包括语言,发达的保卫和防御系统,精妙的建筑以及为了共同利益自我牺牲的特点。由于有这些共性,蜜蜂基因组的发表将使科学家不仅能够深入研究蜜蜂生物学,而且能深入了解我们人类自身的生物学。     

Asymmetric neural coding revealed by in vivo calcium imaging in the honey bee brain

Left–right asymmetries are common properties of nervous systems. Although lateralized sensory processing has been well studied, information is lacking about how asymmetries are represented at the level of neural coding. Using in vivo functional imaging, we identified a population-level left–right asymmetry in the honey bee''s primary olfactory centre, the antennal lobe (AL). When both antennae were stimulated via a frontal odour source, the inter-odour distances between neural response patterns were higher in the right than in the left AL. Behavioural data correlated with the brain imaging results: bees with only their right antenna were better in discriminating a target odour in a cross-adaptation paradigm. We hypothesize that the differences in neural odour representations in the two brain sides serve to increase coding capacity by parallel processing.     

Computational and transcriptional evidence for microRNAs in the honey bee genome

Background  

Non-coding microRNAs (miRNAs) are key regulators of gene expression in eukaryotes. Insect miRNAs help regulate the levels of proteins involved with development, metabolism, and other life history traits. The recently sequenced honey bee genome provides an opportunity to detect novel miRNAs in both this species and others, and to begin to infer the roles of miRNAs in honey bee development.     

Chemosensory proteins in the honey bee: Insights from the annotated genome, comparative analyses and expressional profiling

Small chemosensory proteins (CSPs) belong to a conserved, but poorly understood protein family that has been implicated in transporting chemical stimuli within insect sensilla. However, their expression patterns suggest that these molecules are also critical for other functions including early development. Here we used both bioinformatics and experimental approaches to characterize the CSP gene family in a social insect, the Western honey bee Apis mellifera, and then compared its members to CSPs in other arthropods. The number of CSPs in the honey bee genome (six) is similar to that found in the sequenced dipteran species (four-seven), but is much lower than the number of CSPs in the moth or in the beetle (around 20 each). These differences seem to be the result of lineage specific expansions. Our analysis of CSPs in a number of arthropods reveals a conserved gene family found in both Mandibulates and Chelicerates. Expressional profiling in diverse tissues and throughout development reveals broader than expected patterns of expression with none of the CSPs restricted to the antennae and one found only in the queen ovaries and in embryos. We conclude that CSPs are multifunctional context-dependent proteins involved in diverse cellular processes ranging from embryonic development to chemosensory signal transduction. Some CSPs may function in cuticle synthesis, consistent with their evolutionary origins in the arthropods.     

Signatures of selection in the Iberian honey bee (Apis mellifera iberiensis) revealed by a genome scan analysis of single nucleotide polymorphisms

Understanding the genetic mechanisms of adaptive population divergence is one of the most fundamental endeavours in evolutionary biology and is becoming increasingly important as it will allow predictions about how organisms will respond to global environmental crisis. This is particularly important for the honey bee, a species of unquestionable ecological and economical importance that has been exposed to increasing human‐mediated selection pressures. Here, we conducted a single nucleotide polymorphism (SNP)‐based genome scan in honey bees collected across an environmental gradient in Iberia and used four F_ST‐based outlier tests to identify genomic regions exhibiting signatures of selection. Additionally, we analysed associations between genetic and environmental data for the identification of factors that might be correlated or act as selective pressures. With these approaches, 4.4% (17 of 383) of outlier loci were cross‐validated by four F_ST‐based methods, and 8.9% (34 of 383) were cross‐validated by at least three methods. Of the 34 outliers, 15 were found to be strongly associated with one or more environmental variables. Further support for selection, provided by functional genomic information, was particularly compelling for SNP outliers mapped to different genes putatively involved in the same function such as vision, xenobiotic detoxification and innate immune response. This study enabled a more rigorous consideration of selection as the underlying cause of diversity patterns in Iberian honey bees, representing an important first step towards the identification of polymorphisms implicated in local adaptation and possibly in response to recent human‐mediated environmental changes.     

Nestmate recognition cues in the honey bee: differential importance of cuticular alkanes and alkenes

In social insects, recognition of nestmates from aliens is based on olfactory cues, and many studies have demonstrated that such cues are contained within the lipid layer covering the insect cuticle. These lipids are usually a complex mixture of tens of compounds in which aliphatic hydrocarbons are generally the major components. The experiments described here tested whether artificial changes in the cuticular profile through supplementation of naturally occurring alkanes and alkenes in honeybees affect the behaviour of nestmate guards. Compounds were applied to live foragers in microgram quantities and the bees returned to their hive entrance where the behaviour of the guard bees was observed. In this fashion we compared the effect of single alkenes with that of single alkanes; the effect of mixtures of alkenes versus that of mixtures of alkanes and the whole alkane fraction separated from the cuticular lipids versus the alkene fraction. With only one exception (the comparison between n-C(19) and (Z)9-C(19)), in all the experiments bees treated with alkenes were attacked more intensively than bees treated with alkanes. This leads us to conclude that modification of the natural chemical profile with the two different classes of compounds has a different effect on acceptance and suggests that this may correspond to a differential importance in the recognition signature.     

Uncovering the novel characteristics of Asian honey bee,Apis cerana,by whole genome sequencing

Background

The honey bee is an important model system for increasing understanding of molecular and neural mechanisms underlying social behaviors relevant to the agricultural industry and basic science. The western honey bee, Apis mellifera, has served as a model species, and its genome sequence has been published. In contrast, the genome of the Asian honey bee, Apis cerana, has not yet been sequenced. A. cerana has been raised in Asian countries for thousands of years and has brought considerable economic benefits to the apicultural industry. A cerana has divergent biological traits compared to A. mellifera and it has played a key role in maintaining biodiversity in eastern and southern Asia. Here we report the first whole genome sequence of A. cerana.

Results

Using de novo assembly methods, we produced a 238 Mbp draft of the A. cerana genome and generated 10,651 genes. A.cerana-specific genes were analyzed to better understand the novel characteristics of this honey bee species. Seventy-two percent of the A. cerana-specific genes had more than one GO term, and 1,696 enzymes were categorized into 125 pathways. Genes involved in chemoreception and immunity were carefully identified and compared to those from other sequenced insect models. These included 10 gustatory receptors, 119 odorant receptors, 10 ionotropic receptors, and 160 immune-related genes.

Conclusions

This first report of the whole genome sequence of A. cerana provides resources for comparative sociogenomics, especially in the field of social insect communication. These important tools will contribute to a better understanding of the complex behaviors and natural biology of the Asian honey bee and to anticipate its future evolutionary trajectory.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-16-1) contains supplementary material, which is available to authorized users.     

Flight of the honey bee

Summary Using manometric and gas analytical methods oxygen consumption , carbon dioxide production , respiratory quotientRQ, (Fig. 1A-C) and thorax surface temperature difference T _ts (Fig. 3) were determined in single bees. The animals were either sitting in respiratory chambers or were suspended by the scutum, in which case they were resting, walking (turning a small polystyrene ball) or flying in a closed miniature wind tunnel.During resting (sitting in Warburg vessels) at an ambient temperatureT _a=10°C,RQ was 1.01±0.2 (n=905) with variations due to method (Fig. 1D, E).RQ values during walking were determined in single cases. In no case were they significantly different from 1.00. After the first 10 min of flight meanRQ was 1.00±0.04. It was significantly smaller than 1.00 (RQ=0.97) only during the last 5% of long-time flights (mean flight duration 58.8±28.8 min). With the exception of near-exhaustion conditions no signs of fuels other than carbohydrates were found.Metabolic rateP _m was 19.71±21.38 mW g^–1 during resting at 20°CT _a30°C indicating that many resting bees actively thermoregulate at higherT _a. After excluding bees which were actively thermoregulating, by an approximationP _m was 5.65±2.44 mW g^–1 at 20°CT _a30°C. True resting metabolic rate for sitting bees atT _a=10°C was 1.31±0.53 mW g^–1 (Fig. 2A, B).A significant negative correlation was found between relative (specific) oxygen consumption rel and body massM _b at 85 mgM _b150 mg.At 0°CT _ts16.5°C a significant (-0.01) positive correlation was found between and T _ts in single resting bees: T _Ts+0.099, or betweenP _m and T _ts:P _m=1.343 T _ts+0.581 (Fig. 3D) in ml h^–1,P _m in mW,T in °C).During walking (duration 13.15±5.71 min,n=13) at 12.5°CT _a21°C a stable T _ts of 11.41±3.37°C, corresponding to 167 mW g^–1, was reached for 80 to 90% of the walking time (Fig. 4B).During wind tunnel flights of tethered animals the minimal metabolic power measured in exhaustion experiments was 240 mW g^–1. Calculation of factors of increase inP _m is of limited value in poikilotherms, in which true resting conditions are not exactly defined.     

Seasonal trends in honey bee pollen foraging revealed through DNA barcoding of bee-collected pollen

Insectes Sociaux - Recent declines in the abundance and diversity of wild bee species have made it important to understand how introduced species such as honey bees contribute to pollinating native...     

Epidemiology of honey bee parasites

The epidemiology of honey bee parasites has been somewhat neglected, but Lynn Royce and Philippe Rossignol describe their unique characteristics. Indeed, it appears that a parasite of social insects has in essence to adapt to two hosts: first, the individual worker within a colony, the numbers of which grow linearly and second, to the colony itself, the actual reproductive 'organism'. Transmission also has vertical and horizontal components. Analysis of tracheal mite populations in particular suggests that intracolony parasite levels are regulated by the swarming behavior of their hosts. Ironically, current and highly productive methods of honey bee management with movable hives curb swarming and may contribute to increasing the spread and the impact of some parasites. This insight may result in changing management practices to reduce the detrimental effects of bee parasites.     

A filamentous virus of the honey bee

A common and widespread disease of honey bees, Apis mellifera, is caused by an unoccluded, Feulgen-positive, filamentous nuclear virus. Ovoid viral particles seen in diseased bee hemolymph consisted of a folded nucleocapsid within a viral envelope and were 0.40 by 0.10 μm. Virions with unfolded nucleocapsids were about 3060 by 60 nm. The disease was transmissible to bees both per os and by injection, but efforts to infect oriental cockroaches, Blatta orientalis, and the greater wax moth, Galleria mellonella, failed. The disease is apparently the same as that described as a rickettsial disease of European bees.