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PubMedDate not supplied

Terminal steps in JH biosynthesis in the honey bee (Apis mellifera L. ): developmental changes in sensitivity to JH precursor and allatotropin.

Juvenile hormone (JH) is considered the prime endogenous signal for the induction of queen development in honey bees (Apis mellifera L.). At the beginning of the last (5th) larval stadium, worker corpora allata synthesize less JH than queen corpora allata as a consequence of a limited production of JH precursors and a caste- and stage-specific block of the terminal step in JH biosynthesis. As previously shown, the Manduca sexta allatotropin stimulates JH biosynthesis in honey bee corpora allata in a dose-dependent and reversible manner, but can not overcome the stage-specific block in the terminal step of JH biosynthesis that is typical for worker early 5th instars. In experiments with M. sexta allatotropin and with the JH precursor farnesoic acid, we found characteristic stage-specific differences in their effects on JH biosynthesis. From the end of the spinning stage on, corpora allata could be stimulated by farnesoic acid to a much higher extent than in earlier developmental stages, suggesting a sudden increase in epoxidase activity. Manduca sexta allatotropin, however, stimulated corpora allata activity until the end of the spinning stage, at which time the corpora allata become suddenly insensitive. These data suggest that in worker larvae, important changes in the regulation of the terminal enzymatic steps in JH biosynthesis occur at the transition from the spinning stage to the prepupal stage. However, the analysis of in vitro activities of the involved enzymes, O-methyltransferase and methyl farnesoate epoxidase, remained inconclusive.

Animals↗
PubMed1992

Effect of diacylglycerols on the activity of cobra venom, bee venom, and pig pancreatic phospholipases A2.

The effects of a series of diacylglycerols (DAGs) with varying acyl chain lengths and degree of unsaturation on the activity of cobra venom, bee venom, and pig pancreatic phospholipases A2 (PL-A2S) were studied using two lipid substrates: dipalmitoylphosphatidylcholine (DPPC) or bovine liver phosphatidylcholine (BL-PC). The activities of the phospholipases critically depended on the chain length and degree of unsaturation of the added DAGs and on the chemical composition of the substrate. The effects of DAGs on cobra or bee venom PL-A2S were similar, but significantly different from the pig pancreatic PL-A2. The data, taken together with our previous NMR studies on physicochemical effects of these DAGs on lipid bilayer structure [De Boeck, H., & Zidovetzki, R. (1989) Biochemistry 28, 7439; (1992) Biochemistry 31, 623], allowed detailed correlation of the type of a bilayer perturbation induced by DAG with the activation or inhibition of the phospholipase on the same system. In general, the activation of the phospholipases correlated with the DAG-induced defects of the lipid bilayer structure. The results, however, argue against general designation of DAGs as "activators" or "inhibitors" of PL-A2S. Thus, for example, diolein activated phospholipases with the BL-PC lipid substrate, but inhibited them with the DPPC substrate. Dihexanoylglycerol and dioctanoylglycerol inhibited pig pancreatic PL-A2 with both lipid substrates and inhibited cobra or been venom PL-A2 with the DPPC substrate, but activated the latter two enzymes with the BL-PC substrate. Longer-chain DAGs (C greater than 12), which induce lateral phase separation of the bilayers into the regions of different fluidities, activated all PL-A2S with both lipid substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1997

Synergism between mellitin and phospholipase A2 from bee venom: apparent activation by intervesicle exchange of phospholipids.

Mellitin, a cationic amphiphilic peptide, has an apparent activating effect on interfacial catalysis by phospholipase A2 (PLA2) of bee venom on zwitterionic vesicles of 1-palmitoyl-2-oleoylglycero-sn-3-phosphocholine (POPC) and on anionic vesicles of 1,2-dimyristoylglycero-sn-3-phosphomethanol (DMPM), as well as on covesicles of POPC/DMPM (3:7). On the other hand, mellitin-induced increase in the rate of pig pancreatic PLA2 is seen only on anionic vesicles. Interfacial kinetic protocols and spectroscopic methods show that the activation is due to enhanced substrate replenishment resulting from intervesicle exchange of zwitterionic or anionic phospholipids through vesicle-vesicle contacts established by mellitin. It is shown that as the hydrolysis on POPC vesicles progresses, due to a high propensity of bee PLA2 for binding to the product containing zwitterionic vesicles, most of the enzyme in the reaction mixture is trapped on few vesicles that are initially hydrolyzed, and thus reaction ceases. Under these conditions, mellitin promotes substrate replenishment by direct exchange of the products of hydrolysis from the enzyme-containing vesicles with the substrate present in excess vesicles which have not been hydrolyzed. Pig PLA2 has poor affinity for POPC vesicles, and the affinity is only modestly higher in the presence of low mole fractions of the products of hydrolysis; therefore, the enzyme is not trapped on those vesicles. Biophysical studies confirm that the phospholipid exchange occurs through stable intervesicle contacts formed by low mole fractions of mellitin, without transbilayer movement of phospholipids or fusion of vesicles. At high mole fraction (> 1.5%) mellitin induces leakage in POPC vesicles and does not form additional contacts. In POPC/DMPM vesicles, the contacts are formed even at high mole fractions of mellitin. Changes in intrinsic tryptophan fluorescence of mellitin indicate that bound mellitin exists in at least two different functional forms depending on the lipid composition and on the lipid:peptide ratio. A model is proposed to accommodate amphiphilic mellitin as a transmembrane channel or an intervesicle contact.

Acrylamide↗
PubMed2004

Simultaneous immunoaffinity column cleanup and HPLC analysis of aflatoxins and ochratoxin A in Spanish bee pollen.

Bee pollen is a major substrate for mycotoxins growth when no prompt and adequate drying is performed by the beekeeper after collection by bees. Regulatory limits for aflatoxins and ochratoxin A are currently in force in the European Union for a rising list of foodstuffs, but not for this. An immunoaffinity column cleanup process has been applied prior to the analysis of aflatoxins B(1), B(2), G(1), and G(2) and ochratoxin A (OTA). Optimization of the HPLC conditions has involved both a gradient elution and a wavelength program for the separation and fluorimetric quantitation of all five mycotoxins at their maximum excitation and emission values of wavelength in a single run. The higher limit of detection (mug/kg) was 0.49 for OTA and 0.20 for aflatoxin B(1). Repeatability (RSDr) at the lower limit tested ranged from 9.85% for OTA to 6.23% for aflatoxin G(2), and recoveries also at the lower spiked level were 73% for OTA and 81% for aflatoxin B(1). None of the 20 samples assayed showed quantifiable values for the five mycotoxins.

Aflatoxins↗
PubMed1999

Release of GPI-anchored Zn2+-glycerophosphocholine cholinephosphodiesterase as an amphiphilic form from bovine brain membranes by bee venom phospholipase A2.

Enzymatic release of Zn(2+)-glycerophosphocholine (GPC)cholinephosphodiesterase, as an amphiphilic form, from bovine brain membranes was examined. Of various membrane hydrolases, bee PLA2 was the most effective in the release of the GPC cholinephosphodiesterase (amphiphilic form, 63-70%) from membrane. Compared to pancreatic PLA2, bee PLA2 was more efficient in the release of GPC cholinephosphodiesterase. In pH-dependent release of GP1-anchored phosphodiesterase, there was a similar pH-release profile between PLA2-mediated release and spontaneous one, implying the involvement of membrane disruption in the PLA2 action. The PLA2-mediated release showed a limited time-dependence (until 45 min) and a limited dose dependence (up to 3 units/ml), characteristic of a receptor-type binding. An ionic binding of PLA2 to membrane may be alluded from the interfering effect of anionic phospholipids on the PLA2 action. In support of an interaction between PLA2 and membrane glycoproteins, the PLA2 action was found to be blocked by lectins, wheat germ agglutinin or concanavalin A. In combination with detergent, the PLA2-mediated release was found to be enhanced synergistically by saponin, a cholesterol-complexing agent. Meanwhile, an additive interaction between PLA2 and lysolecithin suggests that PLA2 action is independent of lysolecithin. It is suggested that the binding of PLA2 to specific sites of membranes, probably rich in GPI-anchored glycoproteins, may be related to the facilitated release of GPI-anchored proteins as amphiphilic form.

Animals↗
PubMed2002

Complete mitochondrial DNA sequence of the important honey bee pest, Varroa destructor (Acari: Varroidae).

Mites in the genus Varroa are the primary parasites of honey bees on several continents. Genetic analyses based on Varroa mitochondrial DNA have played a central role in establishing Varroa taxonomy and dispersal. Here we present the complete mitochondrial sequence of the important honey bee pest Varroa destructor. This species has a relatively compact mitochondrial genome (15,218 bp). The order of genes encoding proteins is identical to that of most arthropods. Ten of 22 transfer RNAs are in different locations relative to hard ticks, and the 12S ribosomal RNA subunit is inverted and separated from the 16S rRNA by a novel non-coding region, a trait not yet seen in other arthropods. We describe a dispersed set of 45 oligonucleotide primers that can be used to address genetic questions in Varroa. A subset of these primers should be useful for taxonomic and phylogenetic studies in other mites and ticks.

Animals↗
PubMed2003

(S)-(+)-linalool, a mate attractant pheromone component in the bee Colletes cunicularius.

Enantiomerically pure (S)-(+)-linalool was the main constituent in the extracts of the cephalic secretions of virgin females, mated females, freshly emerged males, and patrolling males of the solitary bee Colletes cunicularius. After copulation, the content of (S)-(+)-linalool emitted by the female was strongly reduced. Electrophysiological experiments revealed that both enantiomers of linalool elicited responses from the antennae of the males. Field tests using the pure enantiomers and the racemate of linalool showed that the number of male bees attracted was highest for (S)-(+)-linalool. The search flight activity in the mating flight area increased dramatically when patrolling males were presented with (S)-(+)-linalool vs (R)-(-)-linalool. Taken together, these data indicate a mate attractant pheromone function of (S)-(+)-linalool.

Acyclic Monoterpenes↗
PubMedDate not supplied

Behavioural effects of pesticides in bees--their potential for use in risk assessment.

This paper reviews a wide variety of behavioural effects that have been reported in bees following exposure to pesticides, primarily insecticides. These range from effects on odour discrimination in the individual to the loss of foraging bees due to disruption of their homing behaviour. Some of these effects have the potential to have a significant impact on the development and survival of colonies. However, there is currently little guidance available on the types of behavioural data which should be collected during laboratory, semi-field or field regulatory studies or how they should be included and interpreted in risk assessment. Further work is required to allow risk assessment to include significant behavioural effects and their longer term consequences on colony survival and development. Such an approach will require a larger base set of data to predict the longer-term consequences on colonies of short-term effects on individuals, e.g. through population modelling.

Animals↗
PubMed1977

Krameria, free fatty acids and oil-collecting bees.

Vogel's report of the production of glycerides rather than nectar as rewards gathered by bees described an association involving several genera of insects and numerous plant families. We report here that members of the Krameriaceae produce floral lips more unusual than those described by Vogel. Our data also provide evidence that the oils of Krameria are collected by bees of only one genus, Centris (Anthophoridae), and used, mixed with pollen, as larval food.

Animals↗
PubMed1979

Behavioural access to short-term memory in bees.

Memory formation proceeds in temporal phases which differ in their effectiveness in controlling subsequent behavior and in their susceptibility to amnestic treatment. The initial phase of memory formation, frequently termed short-term memory, is generally considered a necessary precursor to long-term memory. However, the course of short-term memory differs widely between animal species and is dependent on experimental procedure. Information may even bypass the short-term phase en route to the long-term one. Experiments reported here using honey bees in a behavioural learning situation suggest that the greatest significance of short-term memory is its function as a mode of memory storage which may be altered effectively by new and contradictory information. Freely flying honey bees were presented two colour alternatives and rewarded on first one and then the other in a reversal learning paradigm. Subsequent colour preference was dependent on the interval between the two trials. Several new features of short-term memory are described. It is concluded that a single mechanisms of short- to long-term memory transfer cannot account for the observed bimodal interval dependent behaviour. Two mechanisms are proposed.

Animals↗
PubMed1998

Eosinophilic foreign body granuloma after multiple self-administered bee stings.

A bee sting can cause a foreign body granuloma of the skin, due to activated macrophages at the stinging site. A 52-year-old woman presented with a large doughnut-shaped ulcerative tumour on the left side of her face. A bean-sized facial papule had grown to a 4.0 x 3.9 x 1.1 cm mass after multiple bee stings induced by herself over a period of 1 year. Histology showed epidermal ulceration with granulomatous inflammatory cell infiltration of many eosinophils. No micro-organisms or foreign bodies were identified. Intralesional triamcinolone acetonide was not effective, but an excellent outcome was obtained using carbon dioxide laser vaporization of the lesion.

Animals↗
PubMed2000

Sperm-mediated transformation of the honey bee, Apis mellifera.

Our primary objective was to identify techniques to transform the genome of the honey bee (Apis mellifera) with foreign DNA constructs. The strategy we adopted was to linearize foreign DNA and introduce it with sperm during the instrumental insemination of virgin queen honey bees. We analysed extracts from larvae within the same cohort and isolated the predicted fragment by means of PCR amplification of genomic DNA. Larvae that carried the construct also expressed the introduced DNA. We propagated several transgenic lines for up to three generations, which demonstrates its heritability. Once carried by a queen, the construct can be detected in that queen's larvae over several months. However, there was no evidence of integration of the construct, at least as determined by genomic Southern analysis. Nevertheless, this demonstrates the general viability of the technique for introduction of DNA, and it should be augmented by further use of transposable elements that enhance integration.

Animals↗
PubMed2004

Egg viability and worker policing in honey bees.

In many species of social Hymenoptera, unmated workers can lay eggs that will produce males by parthenogenesis. Nevertheless, in queenright honey bee colonies (Apis mellifera), worker reproduction is low. One possible mechanism for this difference is worker policing, the removal of worker-laid eggs by other workers. This behavior can evolve in species in which queens are multiply mated, where workers are more closely related to the sons of their mother than those of their sisters. Another possible mechanism of the low level of worker reproduction is worker-laid eggs being less viable than queen-laid eggs. We show that this difference in quality is the case for honey bees.

Animals↗
PubMed2003

Global perception in small brains: topological pattern recognition in honey bees.

A series of experiments with honey bees demonstrate that their small brains nevertheless possess the ability for topological perception. Bees rapidly learned to discriminate patterns that are topologically different, and they generalized the learned cue to other novel patterns. By contrast, discrimination of topologically equivalent patterns was learned much more slowly and not as well. Thus, although the global nature of topological properties makes their computation difficult, topology may be a fundamental component of the vocabulary by which visual systems represent and characterize objects.

Animals↗
PubMed1994

DNA fingerprinting analysis of parent-offspring conflict in a bee.

Demonstrating the importance of haplodiploidy in the evolution of eusociality among the Hymenoptera (bees, wasps, and ants) requires estimation of four parameters: relatedness between cooperating individuals, effective mating frequency, sex ratio, and rates of worker reproduction. Multilocus DNA fingerprinting techniques permitted the precise determination of these parameters for the primitively eusocial bee Augochlorella striata (Halictidae). DNA fingerprints revealed an unprecedented resolution of genetic relationships within colonies, detecting factors such as intraspecific nest parasitism and diploid males that confounded estimates of relatedness and sex ratio, respectively. Parameter estimates (i) corroborate recent evidence for queen-worker conflict over the sex ratio and (ii) implicate the role of haplodiploidy in the evolution of worker behavior.

Animals↗
PubMed1996

Common endocrine and genetic mechanisms of behavioral development in male and worker honey bees and the evolution of division of labor.

Temporal polyethism is a highly derived form of behavioral development displayed by social insects. Hormonal and genetic mechanisms regulating temporal polyethism in worker honey bees have been identified, but the evolution of these mechanisms is not well understood. We performed three experiments with male honey bees (drones) to investigate how mechanisms regulating temporal polyethism may have evolved because, relative to workers, drones display an intriguing combination of similarities and differences in behavioral development. We report that behavioral development in drones is regulated by mechanisms common to workers. In experiment 1, drones treated with the juvenile hormone (JH) analog methoprene started flying at significantly younger ages than did control drones, as is the case for workers. In experiment 2, there was an age-related increase in JH associated with the onset of drone flight, as in workers. In experiment 3, drones derived from workers with fast rates of behavioral development themselves started flying at younger ages than drones derived from workers with slower rates of behavioral development. These results suggest that endocrine and genetic mechanisms associated with temporal polyethism did not evolve strictly within the context of worker social behavior.

Aging↗
PubMed2000

Novel human secreted phospholipase A(2) with homology to the group III bee venom enzyme.

Venom and mammalian secreted phospholipases A(2) (sPLA(2)s) have been associated with numerous physiological, pathological, and toxic processes. So far, structurally related group I and II sPLA(2)s have been found in vertebrates such as mammals and snakes, whereas group III sPLA(2)s have mainly been found in venom from invertebrates such as bees and scorpions. Here we report the cloning and expression of a cDNA coding for a human group III (hGIII) sPLA(2). The full-length cDNA codes for a signal peptide of 19 residues followed by a protein of 490 amino acids made up of a central sPLA(2) domain (141 residues) flanked by large N- and C-terminal regions (130 and 219 residues, respectively). The sPLA(2) domain is 31% identical to bee venom sPLA(2) and displays all of the features of group III sPLA(2)s including 10 cysteines. The hGIII sPLA(2) gene consists of at least 7 exons and maps to chromosome 22q. By Northern blot analysis, a 4.4-kilobase hGIII transcript was found in kidney, heart, liver, and skeletal muscle. Transfection of hGIII sPLA(2) cDNA in COS cells led to accumulation of sPLA(2) activity in the culture medium, indicating that the cDNA codes for a secreted enzyme. Using small unilamellar vesicles as substrate, hGIII sPLA(2) was found to be a Ca(2+)-dependent enzyme showing an 11-fold preference for phosphatidylglycerol over phosphatidylcholine and optimal activity at pH 8.

Amino Acid Sequence↗
PubMed2006

Supercooling points and diapause termination in overwintering adults of orchard bees Osmia cornuta and O. rufa (Hymenoptera: Megachilidae).

The orchard bee species Osmia cornuta (Latreille) and O. rufa (Linnaeus) are both European in distribution. Osmia cornuta is distributed in the central and southern half of the continent, while O. rufa is distributed additionally in more northern parts of Europe, including Great Britain. These bees over-winter in cocoons as diapausing adults. The freezing temperatures of overwintering adults of O. cornuta and O. rufa during diapause are similar: -30 degrees C to -24 degrees C and -31 degrees C to -26 degrees C, respectively. However, there are differences in the termination of their diapause. Under natural conditions in the wider area of Belgrade, O. rufa appears in spring about two weeks later than O. cornuta.

Animals↗