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At least 505 records · Page 28Linked to original sources
PubMed1999

Exploratory studies of inhibitory conditioning in honeybees (Apis mellifera).

The best available evidence of inhibitory conditioning in vertebrates comes from experiments in which variants of A+/AB- and A+/B- training were compared in terms of response to B in summation and retardation tests, the results suggesting that inhibition is generated by nonreinforcement as an increasing function of the excitatory value of the setting. We report here 7 experiments with foraging honeybees (Apis mellifera) that failed to show a difference in the effects of the 2 treatments. On the basis of previous experiments as well as supplementary experiments whose results give no reason to doubt the sensitivity of the training techniques and measures used, our consistently negative results may mean either that inhibition in honeybees is generated by nonreinforcement independently of the setting or that there is no inhibitory conditioning at all in honeybees--that the only associative function of nonreinforcement is to reduce excitatory strength.

Animals↗
PubMed2000

Concentrated expression of Ca2+/ calmodulin-dependent protein kinase II and protein kinase C in the mushroom bodies of the brain of the honeybee Apis mellifera L.

We have previously used the differential display method to identify a gene that is expressed preferentially in the mushroom bodies of worker honeybees and to show that it encodes a putative inositol 1,4,5-trisphosphate receptor (IP3R) homologue (Kamikouchi et al. [1998] Biochem. Biophys. Res. Commun. 242:181-186). In the present study, we examined whether the expression of some of the genes for proteins involved in the intracellular Ca2+ signal transduction is also concentrated in the mushroom bodies of the honeybee by isolating cDNA fragments that encode the Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC) homologues of the honeybee. In situ hybridization analysis revealed that the expression of these genes was also concentrated in the mushroom bodies of the honeybee brain: The CaMKII gene was expressed preferentially in the large-type Kenyon cells of the mushroom bodies, whereas that for PKC was expressed in both the large and small types of Kenyon cells. The expression of the genes for IP3R and CaMKII was concentrated in the mushroom bodies of the queen and drone as well as in those of the worker bee. Furthermore, the enzymatic activities of CaMKII and PKC were found to be higher in the mushroom bodies/central bodies than in the optic and antennal lobes of the worker bee brain. These results suggest that the function of the intracellular Ca2+ signal transduction is enhanced in Kenyon cells in comparison to other neuronal cell types in the honeybee brain.

Amino Acid Sequence↗
PubMed1984

Biological effects of a 765-kV, 60-Hz transmission line on honey bees (Apis mellifera L.): hemolymph as a possible stress indicator.

Number of circulating hemocytes and hemolymph protein patterns of adult worker honey bees were analyzed as possible indicators of stress resulting from colony placement under a 765-kV transmission line. Although exposure to 55, 80, and 95 microA total induced hive current (THC) produced colony behavioral disturbance, there were no consistent effects on mean hemocyte counts at 55- or 95-microA THC. Age-dependent declines in circulating hemocyte number were similar in all exposure groups. There were no consistent differences in tube-gel electropherograms. No consistent differences were found in two-density slab-gel electropherograms based on ultrasensitive silver stain. The 67 positively charged and four negatively charged protein fractions from overwintering bees are two- to threefold more than currently reported in the literature.

Animals↗
PubMed1988

Exposure scheme separates effects of electric shock and electric field for honey bees, Apis mellifera L.

Mechanisms to explain disturbance of honey bee colonies under a 765-kV, 60-Hz transmission line [electric (E) field = 7 kV/m] fall into two categories: direct bee perception of enhanced in-hive E fields, and perception of shock from induced currents. The same adverse biological effects previously observed in honey bee colonies exposed under a 765-kV transmission line can be reproduced by exposing worker bees to shock or E field within elongated hive entranceways (= tunnels). Exposure to intense E field caused disturbance only if bees were in contact with a conductive substrate. E-field and shock exposure can be separated and precisely defined within tunnels, eliminating dosimetric vagaries that occur when entire hives are exposed to E field.

Animals↗
PubMed1988

Mechanism of biological effects observed in honey bees (Apis mellifera, L.) hived under extra-high-voltage transmission lines: implications derived from bee exposure to simulated intense electric fields and shocks.

This work explores mechanisms for disturbance of honey bee colonies under a 765 kV, 60-Hz transmission line [electric (E) field = 7 kV/m] observed in previous studies. Proposed mechanisms fell into two categories: direct bee perception of enhanced in-hive E fields and perception of shock from induced currents. The adverse biological effects could be reproduced in simulations where only the worker bees were exposed to shock or to E field in elongated hive entranceways (= tunnels). We now report the results of full-scale experiments using the tunnel exposure scheme, which assesses the contribution of shock and intense E field to colony disturbance. Exposure of worker bees (1,400 h) to 60-Hz E fields including 100 kV/m under moisture-free conditions within a nonconductive tunnel causes no deleterious affect on colony behavior. Exposure of bees in conductive (e.g., wet) tunnels produces bee disturbance, increased mortality, abnormal propolization, and possible impairment of colony growth. We propose that this substrate dependence of bee disturbance is the result of perception of shock from coupled body currents and enhanced current densities postulated to exist in the legs and thorax of bees on conductors. Similarly, disturbance occurs when bees are exposed to step-potential-induced currents. At 275-350 nA single bees are disturbed; at 600 nA bees begin abnormal propolization behavior; and stinging occurs at 900 nA. We conclude that biological effects seen in bee colonies under a transmission line are primarily the result of electric shock from induced hive currents. This evaluation is based on the limited effects of E-field exposure in tunnels, the observed disturbance thresholds caused by shocks in tunnels, and the ability of hives exposed under a transmission line to source currents 100-1,000 times the shock thresholds.

Animals↗
PubMed2003

Patterns of PERIOD and pigment-dispersing hormone immunoreactivity in the brain of the European honeybee (Apis mellifera): age- and time-related plasticity.

We explored the neural basis of age- and task-related plasticity in circadian patterns of activity in the honeybee. To identify putative circadian pacemakers in the bee brain, we used antibodies against Drosophila melanogaster and Antheraea pernyi PERIOD and an antiserum to crustacean pigment-dispersing hormone (PDH) known to cross-react with insect pigment-dispersing factors (PDFs). In contrast to previous results from Drosophila, PDH and PER immunoreactivity (-ir) were not colocalized in bee neurons. The most intense PER-ir was cytoplasmic, in two groups of large neurons in the protocerebrum. The number of protocerebral PER-ir neurons and PER-ir intensity within individual cells were highest in brains collected during subjective night and higher in old bees than in young bees. These results are consistent with previous analyses of brain per mRNA in honeybees. Nuclear PER-ir was found throughout the brain, including the optic and antennal lobes. A single group of PDH-ir neurons (approximately 20/optic lobe) was consistently and intensely labeled at the medial margin of the medulla, independent of age or time of day. The processes of these neurons extended to specific neuropils in the protocerebrum and the optic lobes but not to the deutocerebrum. The patterns displayed by PER- and PDH-ir do not completely match any patterns previously described. This suggests that, although clock proteins are conserved across insect groups, there is no universal pattern of coexpression that allows ready identification of pacemaker neurons within the insect brain.

Aging↗
PubMed1995

Anatomy of the antennal motoneurons in the brain of the honeybee (Apis mellifera).

This paper describes the morphology and location of the cerebral motoneurons that control the movement of the antennae in the honeybee. The position of each antenna is controlled by two muscle systems; the basal segment (scape) is moved by four muscles within the head capsule, and two muscles within the scape control the distal segments (flagellum) of the antenna. The motor system of the scape is controlled by nine motoneurons, and that of the flagellum by six motoneurons. All of these motoneurons share the dorsal lobe as a common projection area where their dendritic fields overlap extensively. These motoneurons do not have contralateral projections. The cell bodies of the antennal motoneurons are located in the soma layer lateral to the dorsal lobe. The somata for each muscle system are arranged in three clusters; two clusters are located in a region of the cortex dorsal to the dorsal lobe and one cluster is located in the cortex ventral to the dorsal lobe. In the cortex dorsal to the dorsal lobe, one cluster of each muscle system shares the same region. Altogether five groups of cell bodies can be distinguished. Double labeling of the motoneurons and presumptive mechanosensory primary antennal afferents with fluorescent dyes has shown that there is an extensive overlap of axonal projections of antennal mechanosensory afferents with dendritic fields of antennal motoneurons.

Afferent Pathways↗
PubMed2001

Mispatterning in the ommatidia of Apis mellifera pupae treated with a juvenile hormone analogue.

To further understand the function of morphogenetic hormones in honeybee eye differentiation, the alterations in ommatidial patterning induced by pyriproxyfen, a juvenile hormone (JH) analogue, were studied by scanning and transmission electron microscopy. Prepupae of prospective honeybee workers were treated with pyriproxyfen and the effects on ommatidial differentiation were described at the end of the pupal development. The results show that the entire ommatidia, i.e., the dioptric as well as the receptor systems, were affected by the JH analogue. The wave of ommatidial differentiation, which progresses from the posterior to the anterior region of the pupal eyes, was arrested. In treated pupae, the rhabdomeres only differentiated at the apical axis of the retinula, the secondary and tertiary pigment cells did not develop their cytoplasm protrusions, and the cone cell quartet did not pattern correctly. Simultaneously, an intense vacuolization was observed in cells forming ommatidia. In a previous study we showed that pyriproxyfen exerts an inhibition on pupal ecdysteroid secretion. In this sense, the arrested ommatidial differentiation in pyriproxyfen-treated pupae could be due to a secondary effect resulting from an alteration in pupal ecdysteroid titers.

Animals↗
PubMed2002

Hydroxyurea-induced partial mushroom body ablation in the honeybee Apis mellifera: volumetric analysis and quantitative protein determination.

Hydroxyurea (HU) treatment of first instar honeybee larvae was previously shown to cause mushroom body (MB) ablations. Predominantly, either one or both median MB subunits were ablated. This prompted us to analyze the effects of asymmetrical or symmetrical HU-induced MB ablation on both the morphology of the brain and on the level of three proteins (synapsin, PKA RII, and PKC), which are considered to play a role in synaptic plasticity, learning, and memory. In brains with one median MB subunit missing the volume of the overall MB calyx neuropil in the lesioned side was diminished by 35%. This strong reduction occurred although the remaining lateral MB calyx of the lesioned brain side was found to be significantly larger than that of the intact side. Accordingly, in brains with both median MB subunits missing the size of the remaining lateral calyces increased. The various types of MB ablation differentially affected the amounts of synapsin, PKA RII, and PKC expressed in the central brain. In animals with bilateral and thus symmetrical MB ablation (both median calyces ablated) the protein amount was found to be similar to that in control animals. However, unilateral MB ablation causes an increase in the amounts of the tested proteins in the intact brain side, while the levels in the ablated side were the same as in control animals. These findings not only show that HU-induced ablation of MB subunits is accompanied by volume changes and by changes in protein expression, but also suggest that these processes are highly regulated between the brain sides. The latter is of general importance in understanding the potential contribution of the MB subunits to learning and memory and their interaction between the brain sides.

Animals↗
PubMedDate not supplied

Qualitative and quantitative determination of yohimbine in authentic yohimbe bark and in commercial aphrodisiacs by HPLC-UV-API/ MS methods.

The development and validation of a rapid qualitative and quantitative method based on an HPLC-UV-MS technique with atmospheric pressure chemical ionisation and electrospray ionisation for the analysis of yohimbine in a number of commercial aphrodisiac products is reported. HPLC with multiple-stage mass spectrometry experiments allowed the identification of the target compound and increased the selectivity of complex analyses such as those involved with multi-botanical preparations. The precision and the robustness of the method were improved by the use of two internal standards: codeine for UV detection and deuterium-labelled yohimbine for MS detection. Twenty commercial aphrodisiac preparations were analysed and the amount of yohimbine measured and expressed as the maximal dose per day suggested on product labels ranged from 1.32 to 23.16 mg.

Aphrodisiacs↗
PubMed1999

Trophallaxis in the honeybee, Apis mellifera : the interaction between viscosity and sucrose concentration of the transferred solution.

Trophallaxis by honeybee foragers was studied under the experimental conditions of an arena. The behaviour of pairs of bees, one (donor) fed with 50-&mgr;l sucrose solutions and another unfed recipient, was analysed as a function of the sucrose concentration, the concentration at constant viscosity (kept constant by adding tylose, an inert polysaccharide), and of the viscosity of a 30% sucrose solution. By increasing the concentration of solutions, the rate at which the solution was transferred to recipient bees (transfer rate of solution, in &mgr;l/s) increased up to a maximum value for 30% sucrose solution, and decreased beyond this concentration (concentration experiment). At constant viscosity, no modulation was observed for the lower sugar concentration range (10-30%), while the transfer rate of solution clearly increased beyond 30% (concentration experiment at constant viscosity). For the 30% sucrose solution, the transfer rate decreased with increasing viscosity (viscosity experiment). If only the sucrose compound is comparatively analysed, the transfer rate of sucrose (in mg/s) increased similarly in the first two experiments. These results give behavioural evidence suggesting that donor bees are capable of modulating the trophallactic food transfer as related to the sucrose concentrations carried into their crops within a considerable wide range, but viscosity prevents it. It also suggests that trophallactic transfer rate does not depend on abdominal volume, for even when all donor bees attained similar loads (50 &mgr;l), transfer rate of solution increased along with the offered sucrose concentration. Results are discussed in relation to the information exchange performed in the foraging context displayed by foragers. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

Trophallaxis in the honeybee Apis mellifera (L.): the interaction between flow of solution and sucrose concentration of the exploited food sources.

Forager bees arriving at the hive after visiting a nectar source, unload the collected liquid food to recipient hivemates through mouth-to-mouth contact (trophallaxis). We analysed whether the main characteristics that define nectar in energetic terms, that is, rate of production (flow of solution), sucrose concentration and rate of sucrose production (sucrose flow) influence trophallactic behaviour. Individual bees trained to feed at a regulated-flow feeder offering sucrose solution were captured once the foraging visit was complete and placed in an acrylic arena with a recipient bee that had not been fed. The rate at which liquid was transferred during the subsequent trophallactic contact (transfer rate) was analysed as a function of the different solution flows and sucrose concentrations offered at the feeder. A relationship was found between transfer rate during trophallaxis and the flow of solution previously presented at the feeder. This relationship was independent of sucrose concentration when above a certain threshold value (ca. 22% weight on weight). We also analysed whether the rate of sucrose deliverance of the food source (sucrose flow) influenced the rate at which the solution was transferred. No clear relationship was found between the rate of sucrose deliverance during trophallactic events (sucrose transfer rate) and the sucrose flow presented at the feeder. The possibility that trophallaxis could be a communication channel through which quantitative information on food source profitability is transmitted among hivemates is discussed. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1997

Programmed cell death in the honey-bee (Apis mellifera L.) larvae midgut.

The histochemical and cytochemical localization of acid phosphatase has been used in an attempt to map the sites of cellular lysis and death. Reaction product was found both in the brush border of the midgut epithelium and in the basal membrane. Vacuolar acid phosphatase activity was found in the regenerative epithelial cells. Extra-cisternal reaction product was associated with the endoplasmic reticulum which was dilated in lysed areas of the cytoplasm. Free acid and alkaline phosphatase activity was found in the basal area of the midgut epithelial cells and the former also occurred in the haemocoel. In the tracheoblastic cells only vacuolar acid phosphatase activity was seen. Chromatin aggregates were distributed throughout the nucleus and the nuclear envelope showed some infolding. Certain mature epithelial cells proved positive for anti-histone associated DNA fragmentation indicative of programmed cell death.

Acid Phosphatase↗
PubMed1998

Histopathological and histochemical changes in honeybee larvae (Apis mellifera L.) after infection with Bacillus larvae, the causative agent of American foulbrood disease.

Morphological, histochemical and cytochemical changes were examined in honeybee larvae after infection with the bacterium Bacillus larvae. The results indicate cell necrosis in the midgut epithelium accompanied by increasing cell vacuolization and nuclear pyknosis following per os inoculation with B. larvae. Many autolysosomes were positive for acid phosphatase. Non-vacuolar acid phosphatase activity was also found in lysed cell compartments. No such activity was found in regenerative epithelial cells. Degradation of haemocytes, salivary glands and other tissues was also observed. Histochemical analyses after per cutaneous inoculation with B. larvae of three- and five-day-old honeybee larvae show intense non-vacuolar acid phosphatase activity followed by disintegration of infected salivary glands, epithelial cell cytoplasm and haemocytes.

Acid Phosphatase↗
PubMed2000

Modes of cell death in the hypopharyngeal gland of the honey bee (Apis mellifera l).

Different modes of cell death have been revealed in the regressing hypopharyngeal glands of worker honey bees. The hypopharyngeal gland, which is well developed in young nursing bees to produce protein for larval food, was seen to regress naturally in foraging adult worker bees. A range of techniques including histology, cytochemistry, in situ TUNEL, Annexin V and Comet assays indicated that cells within the gland demonstrate progressive symptoms of apoptosis, necrosis and a vacuolar form of programmed cell death. The latter mode of cell death did not display chromatin margination, but was accompanied by an enhanced level of autophagic and hydrolytic activity in which a cytosolic source of acid phosphatase became manifest in the extra-cisternal spaces. Normal and annexin-positive cells were found to occur in the younger nursing bees, whilst necrosis and an aberrant vacuolar type of apoptosis predominated in the older foraging bees. The relevance of these results to the classification of programmed cell death is discussed.

Acid Phosphatase↗