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At least 595 records · Page 33Linked to original sources
PubMed2005

Honey bees as a model for understanding mechanisms of life history transitions.

As honey bee workers switch from in-hive tasks to foraging, they undergo transition from constant exposure to the controlled homogenous physical and sensory environment of the hive to prolonged diurnal exposures to a far more heterogeneous environment outside the hive. The switch from hive work to foraging offers an opportunity for the integrative study of the physiological and genetic mechanisms that produce the behavioral plasticity required for major life history transitions. Although such transitions have been studied in a number of animals, currently there is no model system where the evolution, development, physiology, molecular biology, neurobiology and behavior of such a transition can all be studied in the same organism in its natural habitat. With a large literature covering its evolution, behavior and physiology (plus the recent sequencing of the honey bee genome), the honey bee is uniquely suited to integrative studies of the mechanisms of behavior. In this review we discuss the physiological and genetic mechanisms of this behavioral transition, which include large scale changes in hormonal activity, metabolism, flight ability, circadian rhythms, sensory perception and processing, neural architecture, learning ability, memory and gene expression.

Animals↗
PubMed2006

Interval timing by an invertebrate, the bumble bee Bombus impatiens.

Sensitivity to temporal information and the ability to adjust behavior to the temporal structure of the environment should be phylogenetically widespread. Some timing abilities, such as sensitivity to circadian cycles, appear in a wide range of invertebrate and vertebrate taxa [1,2]. Interval timing--sensitivity to the duration of time intervals--has, however, only been shown to occur in vertebrates [3,4]. Insect pollinators make a variety of decisions that would appear to require the ability to estimate elapsed durations. We exposed bumble bees to conditions in which proboscis extension was reinforced after a fixed duration had elapsed or after either of two fixed durations had elapsed. Two groups of bees were trained with a short duration (either 6 s or 12 s) and a long duration (36 s) in separate experimental phases (independent timing groups), whereas two other groups were trained with a short duration (either 6 s or 12 s) and long duration (36 s) always intermixed unpredictably (multiple timing groups). On long intervals, independent timing groups waited longer than mixed timing groups to generate the first response and responded maximally near the end of the interval. Multiple timing groups waited the same amount of time on average before generating the first response on both long and short intervals. On individual trials, multiple timing groups appeared to time either the long duration only or both the short and long durations: most trials were characterized by a single burst of responding that began between the short and long duration values or by two bursts of responding with the first burst bracketing the short value and the second burst beginning in anticipation of the long value. These results show that bumble bees learn to time interval durations and can flexibly time multiple durations simultaneously. The results indicate no phylogenetic divide between vertebrates and invertebrates in interval timing ability.

Animals↗
PubMed2005

Occurrence of mycotoxin producing fungi in bee pollen.

The natural mycobiota occurring in bee pollen is studied in the present report with special attention to analyze the incidence of fungal species that are potential producers of mycotoxins. A total of 90 ready-to-eat bee pollen samples were analyzed. Eighty-seven samples were collected in stores placed in different Spanish areas and three were from Buenos Aires (Argentina). The statistical results (ANOVA) showed that yeasts and Penicillium spp. were the predominant fungi. With regard to the potential mycotoxin producing species, Penicillium verrucosum, Aspergillus niger aggregate, Aspergillus carbonarius, Aspergillus ochraceus, Aspergillus flavus, Aspergillus parasiticus and Alternaria spp. were found. The last genus was isolated very frequently. The potential ability for producing ochratoxin A (OTA) and aflatoxins B(1), B(2), G(1) and G(2) was studied by culturing in vitro the isolates followed by analysis of these mycotoxins in culture extracts by HPLC with fluorescent detection. It was found that 100%, 53.3%, 33.3% and 25% of the isolates of A. carbonarius, A. ochraceus, P. verrucosum and A. niger aggregate, respectively, produced OTA. Moreover, 28.6% of the isolates from the A. flavus plus A. parasiticus group were able to produce aflatoxin B(1). Aflatoxin B(2) was detected in only 10% of the cultures. Aflatoxins G(1) and G(2) were not detected in cultures under the assayed conditions. This is the first report carried out on the natural mycobiota occurring in bee pollen in general and on the toxigenic capability of these isolates in particular.

Aflatoxins↗
PubMed2003

Oral colon-specific drug delivery for bee venom peptide: development of a coated calcium alginate gel beads-entrapped liposome.

Colon-specific drug delivery systems (CDDSs) can be used to improve the bioavailability of protein and peptide drugs through the oral route. A novel formulation for oral administration using coated calcium alginate gel beads-entrapped liposome and bee venom peptide as a model drug has been investigated for colon-specific drug delivery in vitro. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely in the physiological environment of the stomach and small intestine. The release rate of bee venom from the coated calcium alginate gel beads-entrapped liposome was dependent on the concentration of calcium and sodium alginate, the amount of bee venom in the liposome, as well as the coating. Furthermore, a human gamma-scintigraphy technique was used in vivo to determine drug delivery more precisely. The colonic arrival time of the tablets was found to be 4-5 h. The results clearly demonstrated that the coated calcium alginate gel beads-entrapped liposome is a potential system for colon-specific drug delivery.

Administration, Oral↗
PubMed2006

Volatile compounds emitted by live European honey bee (Apis mellifera L.) queens.

We used solid-phase microextraction (SPME, 65 microm PDMS-DVB fiber) to sample the volatile compounds emitted by live honey bee queens in several reproductive states (unmated queens, recently mated queens, and established mated queens), and compared them to the volatiles emitted by workers. We detected nine compounds that were present in at least 75% of the individuals in at least one type of bee, and which were not present in the sampling environment alone. Four of these compounds were present in queens but not in workers. One of these four compounds, identified as E-beta-ocimene, was expressed fully only in established mated queens and may be a signal of diploid egg-laying activity. The three remaining queen-specific compounds (including one identified as 2-phenylethanol) were associated with unmated queens and may mediate interactions between unmated queens and workers during queen elimination. The five common compounds that we detected in both queens and workers were hydrocarbons and may function as nestmate recognition cues. We consider these discoveries as a first step in determining the potentially important functions of volatile signals and cues within honey bee nests.

Acyclic Monoterpenes↗
PubMed2006

Acute ethanol ingestion produces dose-dependent effects on motor behavior in the honey bee (Apis mellifera).

Ethanol consumption produces characteristic behavioral states in animals that include sedation, disorientation, and disruption of motor function. Using individual honey bees, we assessed the effects of ethanol ingestion on motor function via continuous observations of their behavior. Consumption of 1 M sucrose solutions containing a range of ethanol doses led to hemolymph ethanol levels of approximately 40-100 mM. Using ethanol doses in this range, we observed time and dose-dependent effects of ethanol on the percent of time our subjects spent walking, stopped, or upside down, and on the duration and frequency of bouts of behavior. The effects on grooming and flying behavior were more complex. Behavioral recovery from ethanol treatment was both time and ethanol dose dependent, occurring between 12 and 24 h post-ingestion for low doses and at 24-48 h for higher doses. Furthermore, the amount of ethanol measured in honey bee hemolymph appeared to correlate with recovery. We predict that the honey bee will prove to be an excellent model system for studying the influence of ethanol on the neural mechanisms underlying behavior.

Animals↗
PubMed2005

Ascosphaera aggregata contamination on alfalfa leafcutting bees in a loose cell incubation system.

The alfalfa leafcutting bee, a solitary bee used to pollinate alfalfa seed crops, is seriously affected by chalkbrood, a larval disease caused by the fungus Ascosphaera aggregata. One attempt to control the disease includes removing nests from the nesting boards (the "loose cell" system). We report here that adults emerging from the loose cells are heavily contaminated with A. aggregata spores. The contamination levels are not as high as previously reported for bees emerging directly from the boards, but they are still a likely focus for disease spread and may need to be targeted in chalkbrood control strategies.

Animals↗
PubMed2005

The regenerative cells during the metamorphosis in the midgut of bees.

The midgut epithelium of bees is formed by the digestive cells, responsible for enzyme secretion and nutrient absorption and for small regenerative cells that are placed in nests scattered among the digestive cells. During metamorphosis, the larval midgut epithelium degenerates and a new adult midgut epithelium is built during larval differentiation of regenerative cells. The present work focuses on the midgut epithelial modifications during the post-embryonic development of the stingless bee Melipona quadrifasciata anthidioides worker and the occurrence of regenerative cell proliferation during midgut metamorphosis in order to test the hypothesis that adult midgut epithelium of worker bees results from regenerative cell proliferation during the pupal stage. Regenerative cell proliferation was detected during larval lifespan. Larval aging is followed by an increase in the number and the size of the nests of regenerative cells. Larval epithelium degeneration begins 2 days after the start of defecation process and in this period the nests of regenerative cells are in contact by means of cytoplasmic extension which have many septate desmosomes and gap junctions. The BrdU immunoreactive regenerative cells were found in the prepupae 12 h after BrdU injection, suggesting that regenerative cell population increase during this larval period. Regenerative cell proliferation results in the increase of the regenerative cell population and not in the formation of new digestive cells because the proliferation of regenerative cells would not be enough to reestablish the nests of regenerative cells and at the same time form new adult digestive cells. In this sense the hypothesis that digestive adult cells originate from regenerative cell proliferation during midgut metamorphosis in M. quadrifasciata anthidioides was rejected.

Animals↗
PubMed2005

Analysis of peptides in the brain and corpora cardiaca-corpora allata of the honey bee, Apis mellifera using MALDI-TOF mass spectrometry.

The neuropeptide profiles and diversity of the brain and retrocerebral organs (corpora cardiaca-corpora allata; CC-CA) of adult workers of the honey bee Apis mellifera carnica (dark European strain) were investigated using a combination of HPLC and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) with post-source decay (PSD) and collision-induced dissociation (CID) fragmentation. Using evidence from genomic sources, including BLAST searches of the honey bee genome, comparisons with other species and de novo sequencing by PSD and CID fragmentation, a total of 13 mass ions could be assigned to peptides predicted from the A. mellifera genomic database. Peptides positively identified were A. mellifera tachykinin-related peptides 3 and 4 (APMGFQGMRa; APMGFYGTRa) and leucomyosuppressin (pEDVDHVFLRFa). Peptides tentatively identified were A. mellifera tachykinin-related peptides 2 and 5 (ALMGFQGVRa; ARMGFHGMRa), A. mellifera allatostatins 2, 3 and 4 (GRDYSFGLa; RQYSFGLa; GRQPYSFGLa), A1-SIFamide (AYRKPPFNGSIFa), Q1-leucomyosuppressin (QDVDHVFLRFa) and A. mellifera pyrokinins PK 1, PK 2 and Q1-PK 2 (TSQDITSGMWFGPRLa; pEITQFTPRLa; QITQFTPRLa). Allatostatins, tachykinin-related peptides and A1-SIFamide were not detected in CC-CA extract, which appears to contain predominantly leucomyosuppressin, Q1-leucomyosuppressin, PK 1, PK 2, Q1-PK 2 and some unidentified masses. No ion signal was detected that would correspond to the hypertrehalosaemic peptide (=Manse-AKH), which has been isolated from the Italian race of the honey bee (A. mellifera ligustica), but not from A. mellifera carnica.

Amino Acid Sequence↗
PubMed2004

Molecular phylogenetics of the allodapine bee genus Braunsapis: A-T bias and heterogeneous substitution parameters.

Extreme AT bias in Hymenopteran mitochondrial genes have created difficulties for molecular phylogenetic analyses, especially for older divergences where multiple substitutions can erode signal. Heterogeneity in the evolutionary rates of different codon positions and different genes also appears to have been a major problem in resolving ancient divergences in allodapine bees. Here we examine the phylogeny of relatively recent divergences in the allodapine bee genus Braunsapis. We examined heterogeneity in nucleotide substitution parameters for one nuclear gene and codon positions in two mitochondrial genes, exploring various phylogenetic analyses for recovering relationships among species from Africa, Madagascar, southern Asia, and Australia. We explored maximum parsimony, maximum likelihood, Log determinant and Bayesian analyses. Broad topological features of best fit trees tended to be similar for equivalent data sets (e.g., total, or with 3rd mt positions excluded), regardless of the analytic method used (e.g., maximum likelihood or Bayesian). Analyses that used the total data set without modelling partitions separately gave unlikely results, indicating that the Malagasy species was most closely related to Australian species. However, analyses that excluded 3rd mitochondrial positions, or modelled partitions separately, suggested that the Malagasy species falls within the African clade. The unlikely topologies apparently result from long branch attraction, and this problem is ameliorated where modelling allows more realistic estimates of base composition and evolutionary rates for 3rd mitochondrial positions. However, we found that even when codon positions are modelled separately, estimated evolutionary rates for 3rd mitochondrial positions are likely to underestimate true rates. Long branch attraction and multiple substitutions are likely to be much more difficult to circumvent in analyses that explore older, generic-level, divergences in allodapine bees where overwriting is expected to be much more extreme. Our results indicate an African origin for Braunsapis, followed by a single, very early, dispersal event into Asia and then by a later dispersal event into Australia. The Malagasy species is derived from within the African clade.

Animals↗
PubMed2004

Phylogeny of the orchid bees (Hymenoptera: Apinae: Euglossini): DNA and morphology yield equivalent patterns.

Orchid bees (Euglossini) are spectacular long-tongued Neotropical bees important in the pollination of Neotropical long-corolla flowers, particularly some orchids. Besides remarkably long tongues, males in particular exhibit other flower-related adaptations, including setal brushes on the foretarsi used for rasping the petals of orchids while collecting aromatic compounds. These compounds are stored in large swollen tibiae and are thought to play an important role in courtship behavior. Euglossini are also unusual in lacking sociality; they are the only tribe among the corbiculate bees that are not eusocial, and two of the genera are cleptoparasitic. Each genus exhibits distinct behavioral traits including nest architecture and host-parasite interactions, yet their evolution is unknown. Despite previous phylogenetic studies of on morphological characters, the relationships among the five euglossine genera remain under debate. We investigate euglossine generic relationships using DNA sequence data from four genes and new morphological characters. The morphological and molecular data yield congruent evolutionary patterns, and combining the data gives a fully resolved and well supported phylogeny of Euglossini.

Animals↗
PubMed2003

The hive bee to forager transition in honeybee colonies: the double repressor hypothesis.

In summer, the honeybee (Apis mellifera) worker population consists of two temporal castes, a hive bee group performing a multitude of tasks including nursing inside the nest, and a forager group specialized on collecting nectar, pollen, water and propolis. Elucidation of the regulatory mechanisms responsible for the hive bee to forager transition holds a prominent position within present day sociobiology. Here we suggest a new explanation dubbed the "double repressor hypothesis" aimed to account for the substantial amount of empirical data in this field. This is the first time where both the regular transition and starvation-induced precocious transition are explained within the same regulatory framework. We suggest that the transition is under regulatory control by an internal and an external repressor of the allatoregulatory central nervous system, where these two repressors modulate a positive regulatory feedback loop involving juvenile hormone (JH) and the lipoprotein vitellogenin. The concepts of age-neutrality, fixed and variable response thresholds and reinforcement are integral parts of our explanation, and in addition they are given explicit physiological content. The hypothesis is represented by a differential equations model at the level of the individual bee, and by a discrete individual-based colony model. The two models generate predictions in accordance with empirical data concerning the cumulative probability of becoming a forager, mean age at onset of foraging, reversal of foragers, time window of reversal, relationship between JH titre and onset of foraging, relative representations of genotypic groups, and effects of forager depletion and confinement.

Aging↗
PubMed1995

IgE+ cells in the peripheral blood of atopic, nonatopic, and bee venom-hypersensitive individuals exhibit the phenotype of highly differentiated B cells.

We have analyzed IgE+ cells in peripheral blood of atopic donors, donors hypersensitive to bee venom, and nonatopic control donors with two- and three-color flow cytometry. Although the percentage of IgE+ cells varied among these groups, the overall phenotypic patterns were similar. Most IgE+ cells do not display typical B-cell markers, such as CD19, CD20, and CD21. A significant proportion of these cells stain for CD38, indicating that they are more differentiated. IgE+ cells express Fc gamma RII and CD45RO, an isoform associated with an advanced level of differentiation. The majority of IgE+ cells do not coexpress other surface immunoglobulin isotypes. In the case of bee venom-hypersensitive donors, we have been able to identify a small population of IgE+ cells with a specificity for phospholipase A2, a major immunogenic component of bee venom. The phospholipase A2+ cells display a phenotype similar to that of the IgE+ cells.

Antibodies, Monoclonal↗
PubMed1998

Modified antigenic reactivity of anti-phospholipase A2 IgG antibodies in patients allergic to bee venom: conversion with immunotherapy and relation to subclass expression.

BACKGROUND: We have previously reported that, in addition to modifying IgG levels and subclass distributions, wasp venom immunotherapy (VIT) rapidly changes IgG antibody specificity. OBJECTIVES: We investigated whether such a change can be documented in the IgG response to the major bee venom allergen, phospholipase A2 (PLA2), from patients allergic to bees treated with VIT; whether it is coupled to the shift in IgG subclass distribution (IgG4 predominance) usually observed during VIT; and whether it restores the specificity displayed by IgG antibodies from nonallergic individuals. METHODS: Antibody specificity was evaluated in 17 patients allergic to bee venom in competitive ELISAs by using streptavidin biotin technology. Patients were tested before and during specific immunotherapy (at 15 days and 6 months) and compared with another group of 17 patients treated with venom injections for at least 2 years (VIT patients) and 30 healthy individuals. RESULTS: The capacity of individual sera to prevent PLA2 binding of pooled IgG from allergic patients changed rapidly with mean percentage inhibitions falling from 84% +/- 14% before starting VIT to 27% +/- 13% and 28% +/- 7% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way analysis of variance [ANOVA]). IgG titers were only slightly increased. The capacity of individual sera to prevent the binding of pooled IgG from patients receiving VIT changed rapidly with mean percentage inhibition increasing from 60% +/- 12% before starting VIT to 85% +/- 6% and 82% +/- 6% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way ANOVA). Similar results were found regardless of whether pooled IgG1 or pooled IgG4 were used. CONCLUSION: VIT results in a rapid change in the antigenic reactivity of anti-PLA2 IgG antibody of human allergic sera, restoring, although not completely, the specificity peculiar to lgG from healthy individuals. This suggests that allergic status and immunoprotection correlate with the preferential expression of distinct IgG specificities, which appear equally distributed over the IgG1 and IgG4 antibody subclasses. It is, however, not known whether the shift in IgG specificity is one of the operative mechanisms of VIT.

Adult↗
PubMed1982

Bee-sting diseases: Who is at risk? What is the treatment?

Many of the large number of people who are stung each year by bees experience frightening systemic reactions, but the vast majority of such reactions are not life-threatening. There is no evidence that the very few who die as a result of a bee sting come from the pool of those who once before sustained a systemic reaction. On the contrary, no reaction at all may be a more ominous predictor of a lethal outcome on a subsequent sting. Death comes about through multiple mechanisms, and not through anaphylaxis alone. Like most cases of sudden death, underlying coronary atherosclerosis appears to be the principal mechanism. External factors that affect mortality include environmental temperature and site of sting. In general, however, because the numbers of deaths are so small, death comes unpredictably, and those at risk have not been identified. Immunotherapy, whether with venom or whole-body extract, has not been proven to prevent death from a bee sting.

Adult↗
PubMed2002

Behavioural pharmacology of octopamine, tyramine and dopamine in honey bees.

In the honey bee, responsiveness to sucrose correlates with many behavioural parameters such as age of first foraging, foraging role and learning. Sucrose responsiveness can be measured using the proboscis extension response (PER) by applying sucrose solutions of increasing concentrations to the antenna of a bee. We tested whether the biogenic amines octopamine, tyramine and dopamine, and the dopamine receptor agonist 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (6,7-ADTN) can modulate sucrose responsiveness. The compounds were either injected into the thorax or fed in sucrose solution to compare different methods of application. Injection and feeding of tyramine or octopamine significantly increased sucrose responsiveness. Dopamine decreased sucrose responsiveness when injected into the thorax. Feeding of dopamine had no effect. Injection of 6,7-ADTN into the thorax and feeding of 6,7-ADTN reduced sucrose responsiveness significantly. These data demonstrate that sucrose responsiveness in honey bees can be modulated by biogenic amines, which has far reaching consequences for other types of behaviour in this insect.

Adrenergic alpha-Agonists↗
PubMed1999

Operant conditioning of antennal movements in the honey bee.

An operant learning protocol was developed for honeybees that are fixed in small tubes. The bees had to touch one or two small silver plates within the range of one antenna. The contacts of the antenna with the silver plates were registered electronically. Three conditioning protocols were analysed. In the first series the conditioned increase of the contact frequency was tested. The animals could touch one plate and received a reward (a small drop of sucrose) whenever the instantaneous frequency at this plate was more than one or two standard deviations above the spontaneous frequency. After conditioning the bees showed a significant increase of the contact frequency. No significant changes were found in a group of yoked controls. In the second series differential conditioning was tested. The animals could touch two silver plates. The spontaneous behaviour was measured and the animals received the reward upon touching the plate with the lower spontaneous frequency. The rewards were only applied whenever the instantaneous frequency exceeded a defined threshold. After ten conditioning trials the animals showed a significant increase in contact frequency for the conditioned plate compared to spontaneous behaviour. No significant changes were found in a group of yoked controls. In the third series reversal learning was tested. The animals were able to touch two silver plates. They were first conditioned to touch the plate which had the lower spontaneous contact frequency. After these conditioning trials they were tested for 10 min and subsequently conditioned to the alternative plate. The experiments demonstrated significant reversal learning compared to yoked controls. This new operant conditioning paradigm for the bee offers the possibility to analyse at the physiological level the mechanisms underlying different forms of learning in this insect.

Animals↗
PubMed1999

Delayed toxic reaction following massive bee envenomation.

Massive bee envenomation can produce both immediate and delayed toxic reaction. Signs and symptoms of immediate toxic reaction are fatigue, nausea, vomiting, hemolysis, kidney failure, and disseminated intravascular coagulation. The label "delayed toxic reaction" refers to a patient who is asymptomatic after a massive bee envenomation, with normal initial laboratory results, but later demonstrates laboratory evidence of hemolysis, coagulopathy, thrombocytopenia, rhabdomyolysis, liver dysfunction, and disseminated intravascular coagulation. The subject of this case report, a 66-year-old man, was stung more than 125 times in an attack by Africanized bees. He was initially asymptomatic, except for pain, and his laboratory findings were normal. The first signs of his fatal multi-organ-system failure were not apparent until 18 hours after envenomation. This experience has led the Good Samaritan Regional Poison Center in Phoenix, AZ, to recommend a 24-hour hospitalization for pediatric patients, older patients, and patients with underlying medical problems who are asymptomatic or who are experiencing only pain after an envenomation of 50 or more stings. Such patients have an increased risk of tissue injury, which may be delayed and which may be more effectively treated if identified early rather than on 12- to 24-hour follow-up. All other envenomated, asymptomatic patients or envenomated patients experiencing only pain who become symptomatic or who belatedly exhibit laboratory values consistent with hemolysis, thrombocytopenia, rhabdomyolysis, liver dysfunction, kidney failure, and disseminated intravascular coagulation within a 6-hour emergency department observation period should be admitted. Intravenous fluids, blood products, dialysis, and other intensive measures should be initiated if necessary.

Aged↗