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PubMedDate not supplied

Effects of Apis mellifera propolis on the activities of streptococcal glucosyltransferases in solution and adsorbed onto saliva-coated hydroxyapatite.

Propolis, a resinous hive product collected by Apis mellifera bees, has been used for thousands of years in folk medicine. Ethanolic extracts of propolis (EEP) have been shown to inhibit the activity of a mixture of crude glucosyltransferase (Gtf) enzymes in solution. These enzymes synthesize glucans from sucrose, which are important for the formation of pathogenic dental plaque. In the present study, the effects of propolis from two different regions of Brazil on the activity of separate, purified Gtf enzymes in solution and on the surface of saliva-coated hydroxyapatite (sHA) beads were evaluated. The EEP from Minas Gerais (MG; Southeastern Brazil) and Rio Grande do Sul (RS; Southern Brazil) were tested for their ability to inhibit the enzymes GtfB (synthesis of insoluble glucan), GtfC (insoluble/soluble glucan) and GtfD (soluble glucan). The effects of propolis on Gtf from Streptococcus sanguis (soluble glucan synthesis) was also explored. The EEP from both regions effectively inhibited the activity of all Gtfs in solution (75-95%) and on the surface of sHA beads (45-95%) at concentrations between 0.75 and 3.0 mg of propolis/ml. However, the two samples of propolis showed different levels of inhibition on each of the enzymes tested. In general, EEP RS demonstrated a significantly higher inhibitory activity on GtfB and C activities (both solution and surface assays) than EEP MG at concentrations between 0.047 and 0.187 mg/ml (p<0.05). EEP MG, on the other hand, exhibited a greater inhibitory effect on the activities of surface GtfD (at 0.375, 0.75 and 1.5 mg/ml) and S. sanguis Gtf (at 1.5 and 3.0 mg/ml; p<0.05). These data indicate that EEP is a potent inhibitor of Gtf enzymes in solution and adsorbed on an experimental pellicle; however, its effect on Gtf activity is variable depending on the geographical origin of the propolis samples. There is a need to identify the active compounds of propolis.

Bacterial Proteins↗
PubMed1977

Detoxified hymenoptera venoms: preliminary studies of in vitro cytotoxicity and antigenicity of Apis mellifera 'venomoid'.

The preparation of detoxified venom (venomoid) of Apis mellifera is described. The venomoid obtained by formaldehyde detoxification retained significant antigenicity. Radioallergosorbent test (RAST) inhibition studies indicated a loss of the affinity of the venomoid for the venom-specific human IgE antibody. In rabbits the venomoid was capable of producing precipitating antibodies which cross-reacted with the original venom. Cytotoxic activity of venomoid as measured by nonimmunological histamine release and hemolytic activity with human cells was not detectable in vitro. Further studies seem warranted for the establishment of a venomoid as a diagnostic and/or therapeutic agent in the management of the hypersensitivity reactions to venom.

Animals↗
PubMed1998

Mechanism of action of honey bee (Apis mellifera L.) venom on different types of muscles.

1. The effect of crude honeybee (Apis mellifera) venom on the skeletal, smooth as well as cardiac muscles were studied in this investigation. 2. Perfusion of gastrocnemius-sciatic nerve preparation of frogs with 1 microgram/ml venom solution has weakened the mechanical contraction of the muscle without recovery. Blocking of nicotinic receptors with 3 micrograms/ml flaxedil before bee venom application sustained normal contraction of gastrocnemius muscle. 3. The electrical activity of duodenum rabbits was recorded before and after the application of 1 microgram/ml venom solution. The venom has depressed the amplitude of the muscle contraction after 15 min pretreatment with atropine nearly abolished the depressor effect of the venom on smooth muscle. 4. In concentrations from 0.5-2 micrograms/ml, bee venom caused decrease of heart rate of isolated perfused toad heart. This bradycardia was accompanied by elongation in the P-R interval. A gradual and progressive increase in the R-wave amplitude reflected a positive inotropism of the venom. Application of 5 micrograms/ml verapamil, a calcium channels blocking agent, abolished the noticed effect of the venom. 5. Marked electrocardiographic changes were produced within minutes of the venom application on the isolated perfused hearts, like marked injury current (elevation or depression of the S-T segment), atrioventricular conduction disturbances and sinus arrhythmias. Atropine and nicotine could decrease the toxic effect of the venom on the myocardium. 6. Results of the present work lead to the suggestion that bee venom is mediated through the peripheral cholinergic neurotransmitter system. General neurotoxicity of an inhibitory nature involving the autonomic as well as neuromuscular system are established as a result of the venom, meanwhile a direct effect on the myocardium membrane stabilization has been suggested.

Animals↗
PubMed1977

Occurrence of intercellular bridges between follicle epithelial cells in the ovary of Apis mellifica queens.

Hitherto unknown intercellular bridges or fusomes between the follicle epithelial cells investing the oocytes of Apis mellifica queens have been observed both with light and electron microscopy. Usually each follicle cell has 2-3 intercellular bridges. In surfacial paraffin sections, the intercellular bridges can be seen to connect a series of follicle cells which may be branching. The intercellular bridges lie close to the egg cortex and this position is relatively constant. The width of the fusomal ring canal varies in different developmental stages. In stages 3 and 4 of oogenesis, which are the main vitellogenic stages, the intercellular bridges measure 0-5 micron, while in stages 1 and 2 they have a diameter ranging from 1-5 to 3-5 micron. In these stages the intercellular bridges are provided with numerous transverse microfilaments which disappear later. The fusomal lips are thickened and consist of electron-dense material and an additional layer of less electron-dense material both inside and outside. Ribosomes flow across the bridge. The intercellular bridges may serve to synchronize the differentiation and functional activity of the follicle epithelium during the course of oogenesis.

Animals↗
PubMed1995

Motor pattern of the stinging response in the honeybee Apis mellifera

In the stinging response of the worker honeybee (Apis mellifera), rhythmic movements of the lancets on the stylet are produced by alternating contractions of a set of stinging muscles (a protractor, M198, and a retractor, M199) on each side during co-contraction of the frucula muscles (M197s) on both sides. In this study, stinging movements were elicited by tactile stimulation to the sternum in isolated abdomens, in intact animals and in preparations in which the connectives between the sixth and terminal abdominal ganglia were cut. There was a close relationship among the following three temporal variables of stinging motoneurone pattern: the interval between successive bursts of a stinging muscle, the duration of a burst and the time lag between the bursts of homologous stinging muscles on both sides. All of these variables increased linearly as the sting was inserted deeper into a soft object and the tension on the lancets increased. When sensory nerves from the proprioceptors (campaniform sensilla on the tapering sting shaft and hair plates at the basal cuticular plate) were cut on both sides, the relative timing of bursts of homologous stinging muscles on both sides and antagonistic stinging muscles on each side became more variable. When a proprioceptive input was removed from one side during penetration of the sting, the frequency of the bursts of stinging muscles was higher and the duration of bursts was shorter on the cut side than on the intact side; nevertheless, a sting muscle was still activated out of phase with its antagonistic muscle on the ipsilateral side and its homologous muscle on the contralateral side. These results suggest that the motor pattern driving the rhythmic movements of stinging muscles is produced by a central pattern generator consisting of a pair of oscillators located in the terminal abdominal ganglion and that the precise timing of the motor pattern in a hemiganglion is controlled mainly by proprioceptive inputs on its own side.

Journal Article↗
PubMed1999

Mechanisms of thermal stability during flight in the honeybee apis mellifera

Thermoregulation of the thorax allows honeybees (Apis mellifera) to maintain the flight muscle temperatures necessary to meet the power requirements for flight and to remain active outside the hive across a wide range of air temperatures (Ta). To determine the heat-exchange pathways through which flying honeybees achieve thermal stability, we measured body temperatures and rates of carbon dioxide production and water vapor loss between Ta values of 21 and 45 degrees C for honeybees flying in a respirometry chamber. Body temperatures were not significantly affected by continuous flight duration in the respirometer, indicating that flying bees were at thermal equilibrium. Thorax temperatures (Tth) during flight were relatively stable, with a slope of Tth on Ta of 0.39. Metabolic heat production, calculated from rates of carbon dioxide production, decreased linearly by 43 % as Ta rose from 21 to 45 degrees C. Evaporative heat loss increased nonlinearly by over sevenfold, with evaporation rising rapidly at Ta values above 33 degrees C. At Ta values above 43 degrees C, head temperature dropped below Ta by approximately 1-2 degrees C, indicating that substantial evaporation from the head was occurring at very high Ta values. The water flux of flying honeybees was positive at Ta values below 31 degrees C, but increasingly negative at higher Ta values. At all Ta values, flying honeybees experienced a net radiative heat loss. Since the honeybees were in thermal equilibrium, convective heat loss was calculated as the amount of heat necessary to balance metabolic heat gain against evaporative and radiative heat loss. Convective heat loss decreased strongly as Ta rose because of the decrease in the elevation of body temperature above Ta rather than the variation in the convection coefficient. In conclusion, variation in metabolic heat production is the dominant mechanism of maintaining thermal stability during flight between Ta values of 21 and 33 degrees C, but variations in metabolic heat production and evaporative heat loss are equally important to the prevention of overheating during flight at Ta values between 33 and 45 degrees C.

Journal Article↗
PubMed2002

Discrimination of closed shapes by two species of bee, Apis mellifera and Megachile rotundata.

In the present study, the performance of two bee species, the honeybee Apis mellifera and the leaf-cutter bee Megachile rotundata, in discriminating among various closed (convex) shapes was examined systematically for the first time. Bees were trained to each of five different shapes, a disc, a square, a diamond and two different triangles, all of the same area, using fresh bees in each experiment. In subsequent tests, the trained bees were given a choice between the learned shape and each of the other four shapes. Two sets of experiments were conducted with both species. In the first, solid black shapes were presented against a white background, thus providing a high luminance contrast. In the second, the shapes carried a random black-and-white pattern and were presented 5 cm in front of a similar pattern, thus producing motion contrast, rather than luminance contrast, against the background. The results obtained with the solid shapes reveal that both bee species accomplish the discrimination, although the performance of the honeybee is significantly better than that of the leaf-cutter bee. Furthermore, the effectiveness of the various shapes differs between the two species. However, in neither species is the discrimination performance correlated with the amount of overlap of the black areas contained in the various pairs of shapes, suggesting that, in our experiments, shape discrimination is not based on a template-matching process. We propose that it is based on the use of local parameters situated at the outline of the shape, such as the position of angles or acute points and, in particular, the position and orientation of edges. This conclusion is supported by the finding that bees of both species accomplish the discrimination even with the patterned shapes. These shapes are visible only because of the discontinuity of the speed of image motion perceived at the edge between the shape and the background.

Animals↗
PubMed2000

Antennal malformations in light ocelli drones of Apis mellifera (Hymenoptera, Apidae).

Malformed antennae of Apis mellifera light ocelli drones were drawn, dissected and mounted permanently on slides containing Canada balsam, in order to count the olfactory discs present in each segment, in comparison with the number of those structures in normal antennae of their brothers. Some drones presented morphological abnormalities in a single segment of the right or left antenna, but others had two or more malformed segments in a same antenna. Drones with malformations in both antennae were also observed. The 4th and 5th flagellum segments were the most frequently affected. In a low number of cases the frequency of olfactory discs in malformed segments did not differ from that one recorded for normal segments. However, in most cases studied, the antennal malformations brought about a significant reduction in the number of olfactory discs from malformed segments.

Animals↗
PubMed2000

Morphometrics and adaptatives aspects in africanized honeybees (Apis mellifera).

The introduction of the African bees (Apis mellifera scutelata) in Brazil and their expansion in the American Continent created the opportunity to study the process of species adaptation in a new environment. In that process, within intra-specific variability, normalising selection can favour individuals that present a better adaptative morphology and they will constitute the most frequent type found in the population. To test that hypothesis morphometric analyses in samples of colonies of africanized bees and in samples of the populations were performed. The development of the colonies was also evaluated in terms of the amount of their brood, honey and pollen. Analysis of the data indicates that more developed colonies are formed by individuals closer to the population average with concerning morphological traits.

Journal Article↗
PubMed2000

Effective fall treatment of Varroa jacobsoni (Acari: Varroidae) with a new formulation of formic acid in colonies of Apis mellifera (Hymenoptera: Apidae) in the northeastern United States.

New formulations of formic acid and thymol, both individually and in combination with various essential oils, were compared with Apistan to determine their efficacy as fall treatments for control of Varroa jacobsoni (Oudemans), a parasitic mite of the honey bee, Apis mellifera L. Percent mite mortality in colonies treated with 300 ml of 65% formic acid averaged 94.2 +/- 1.41% (least square means +/- SE, n = 24), equivalent to those receiving four, 10% strips of Apistan (92.6 +/- 1.79%, n = 6). Treatment with thymol (n = 24) resulted in an average mite mortality of 75.4 +/- 5.79%, significantly less than that attained with Apistan or formic acid. The addition of essential oils did not affect treatment efficacy of either formic acid or thymol. The ratio of the coefficients of variation for percentage mortality for the formic acid (CVFA) and Apistan (CVA) groups was CVFA/CVA = 0.66. This indicates that the formic acid treatment was as consistent as the Apistan treatment. Thymol treatments did not provide as consistent results as Apistan or formic acid. Coefficient variation ratios for percentage mortality for the thymol group (CVT) with the Apistan and formic acid groups were CVT/CVA = 4.47 and CVT/CVFA = 6.76, respectively. In a second experiment, colonies received a 4-wk fall treatment of either 300 ml of 65% formic acid (n = 24) or four, 10% strips of Apistan (n = 6). The next spring, mite levels in the formic acid group (554.3 +/- 150.20 mites) were similar to those in the Apistan treatment group (571.3 +/- 145.05 mites) (P = 0.93). Additionally, the quantities of bees, brood, pollen, and nectar/honey in the two treatment groups were not significantly different (P > or = 0.50 each variable). These results suggest that formic acid is an effective alternative to Apistan as a fall treatment for varroa mites in temperate climates.

Animals↗
PubMed2001

Bombus impatiens (Hymenoptera: Apidae): an alternative to Apis mellifera (Hymenoptera: Apidae) for lowbush blueberry pollination.

The pollination effectiveness of the commercially reared bumble bee Bombus impatiens Cresson, was compared in field studies to the honey bee, Apis mellifera L., for lowbush blueberry, Vaccinium angustifolium Ait. A preliminary study indicated that B. impatiens had potential as an alternative pollinator. In a 3-yr study, percentage fruit set, percentage harvested berries, berry weight, and seeds per berry were compared in blueberry fields stocked at 7.5 A. mellifera hives per hectare to 5, 7.5, or 10 B. impatiens colonies per hectare. Percentage of harvested berries (yield) was significantly higher in fields stocked with B. impatiens at 10 colonies per hectare. No other parameters measuring pollinator effectiveness were significantly different at 5, 7.5, or 10 colonies per hectare. Flower handling time was significantly faster for B. impatiens and it more frequently collected blueberry pollen. All parameters of pollinator effectiveness were similar for B. impatiens, A. mellifera, and native wild bees in a follow-up study. Overall, B. impatiens was a suitable alternative to A. mellifera.

Animals↗
PubMed2001

Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis mellifera.

Imidacloprid is a systemic nitroguanidine insecticide that belongs to the neonicotinoid family. As an agonist of the acetylcholine receptor, it attacks the insect nervous system and is extremely effective against various sucking and mining pests. Oral acute and chronic toxicity of imidacloprid and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid, desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative) were investigated in Apis mellifera. Acute intoxication by imidacloprid or its metabolites resulted in the rapid appearance of neurotoxicity symptoms, such as hyperresponsiveness, hyperactivity, and trembling and led to hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10-10,000 microg/kg). Acute toxicity (LD50) values of imidacloprid were about 60 ng/bee (600 microg/kg) at 48 h and about 40 ng/bee (400 microg/kg) at 72 and 96 h. Out of the six imidacloprid metabolites tested, only two (5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The 5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50 four to six times higher than that of imidacloprid. Urea also appeared as a compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,000 ng/bee (10,000 microg/kg). However, no significant toxicity was observed with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and desnitroimidacloprid in the range of doses tested. To test chronic toxicity, worker bees were fed sucrose solutions containing 0.1, 1, and 10 microg/L of imidacloprid and its metabolites for 10 d. Fifty percent mortality was reached at approximately 8 d. Hence, considering that sucrose syrup was consumed at the mean rate of 12 microl/d and per bee, after an 8-d period the cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10 microg/kg). Thus, all tested compounds were toxic at doses 30 to 3,000 (olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and >1,000 to 100,000 (remaining metabolites) times lower than those required to produce the same effect in acute intoxication studies. For all products tested, bee mortality was induced only 72 h after the onset of intoxication.

Administration, Oral↗
PubMed1999

Modification of the AFLP protocol applied to honey bee (Apis mellifera L.) DNA.

The established amplified fragment-length polymorphism (AFLP) protocol was simplified and optimized for honey bee DNA (Apis mellifera L.). Compared to the original method, the following simplifications were made: (i) the digestion of DNA and ligation of the adapters are performed in one reaction vs. two, (ii) one restriction enzyme is used vs. two and (iii) amplification is accomplished in one reaction vs. two. PCR products are resolved in agarose-Synergel instead of polyacrylamide and are visualized by ethidium bromide staining rather than by autoradiography of labeled primers. Using the modified procedure for honey bee DNA, high reproducibility of the band patterns of PCR products and low sensitivity to the amplification conditions were seen. Analysis of honey bee DNA revealed considerable genetic variability within and between African and European bee samples. African- and European-specific fragments were found.

Animals↗
PubMed1999

Development of dopamine-immunoreactive neurons associated with the antennal lobes of the honey bee, Apis mellifera.

This report examines the development of the dopaminergic system in the primary antennosensory centres (antennal lobes) of the brain of the honey bee, Apis mellifera, and the effects of dopamine on neurite outgrowth of antennal-lobe neurons in vitro. Antibodies raised against dopamine were used to follow the development of a small population of dopamine-immunoreactive neurons that invade the antennal lobes during metamorphic adult development. Immunopositive somata associated with the antennal lobes were first detected at stage 2 of the nine stages of metamorphic adult development, but processes of these neurons within the antennal-lobe neuropil did not exhibit immunostaining until pupal stage 3. Severe depletion of primary sensory input to the right antennal lobe early in metamorphic adult development or removal of the right antenna from newly emerged bees did not alter the expression of dopamine immunoreactivity in the antennal-lobe neuropil. The presence of dopamine in developing antennal lobes was confirmed by using high performance liquid chromatography with electrochemical detection. Levels of dopamine were significantly higher at pupal stage 4 than at all other stages examined. This surge in dopamine levels coincided with rapid growth and compartmentalisation of the antennal-lobe neuropil. Exogenously applied dopamine (50 microM) enhanced the growth of antennal-lobe neurons in vitro, but only in cells derived from pupae at stage 5 of metamorphic adult development. The early appearance of dopamine-immunoreactive neurons and the effects of dopamine on stage 5 antennal-lobe neurons in vitro support the view that dopamine plays a role in the developing brain of the honey bee.

Analysis of Variance↗
PubMed1999

Reversible downregulation of protein kinase A during olfactory learning using antisense technique impairs long-term memory formation in the honeybee, Apis mellifera.

In this study, we examined the role of cAMP-dependent protein kinase (PKA) in associative olfactory learning of the honeybee, Apis mellifera. In the bee, specific interference with molecules to clarify their role in a certain behavior is difficult, because genetic approaches, such as mutants or transgenic animals, are not feasible at the moment. As a new approach in insects in vivo, we report the use of short antisense oligonucleotides. We show that phosphorothioate-modified oligodeoxynucleotides complementary to the mRNA of a catalytic subunit of PKA directly injected into the bee brain cause a reversible and specific downregulation of both the amount of the catalytic subunit and of PKA activity by 10-15%. The amounts of the regulatory subunit of PKA, as well as PKC, are not affected. The slight "knockdown" of PKA activity during the training procedure, a classical olfactory conditioning of the proboscis extension reflex, neither affects acquisition nor memory retention 3 or 6 hr after training. However, it causes an impairment of long-term memory retention 24 hr after training. Downregulation of PKA 3 hr after training has no detectable effect on memory formation. We conclude that PKA contributes to the induction of a long-term memory 24 hr after training when activated during learning. Second, we demonstrate that the antisense technique is feasible in honeybees in vivo and provides a new and powerful tool for the study of the molecular basis of learning and memory formation in insects.

Animals↗
PubMed2000

[Comparative evaluation of bacteria identification from the Acinetobacter genus using a commercially available API 20NE system, PCR and RFLP techniques].

A study was carried out for identification of 50 Acinetobacter strains isolated from various clinical materials. Using classic methods the following species were identifies: Acinetobacter sp. (68%), Acinetobacter baumanii (24%) and Acinetobacter lwofii (8%). In all strains the recA gene was found of 435-500 pz size which confirms their belonging to that genus. Amplification products were digested with restriction enzymes Mbol and HinfI (RFLP) and their detection was carried out on agarose gel by electrophoresis methods, owing to that the arrangement of gene fragment characteristic of each strain was obtained. After careful analysis restriction patterns were obtained corresponding to the following genome species: Acinetobacter baumanii (60%), Acinetobacter sp. 3 (28%) and Acinetobacter lwoffii (12%). The methods of molecular biology made possible a more precise classification of the studied strains according to species. Certain strains determined as Acinetobacter sp. by the API 20NE system were found to be Acinetobacter baumanii, Acinetobacter sp. 3 or Acinetobacter lwofii when determined by the PCR/RFLP method.

Acinetobacter↗
PubMed2000

Utilization of bee (Apis mellifera) honey for vinegar production at laboratory scale.

Vinegar was obtained from bee (Apis mellifera) honey. The wort was prepared by diluting honey in distilled water to 21% total solids and by adding ammonium sulfate and ammonium phosphate. Saccharomyces cerevisiae was inoculated to the wort (4 g/L). Ethanol production was carried out at room temperature during 84 hours. In this study, 1 Kg of honey yielded about 5 L of wine, containing 8% alcohol (v/v), from a wort with 17.11% total sugars (w/v). The efficiency of the alcoholic fermentation was 81.34%. The acetic fermentation with an inoculum of mixed acetic microorganisms was performed by quick process in a 15 L vertical fermenter. This resulted in a vinegar containing up to 9% of acetic acid (w/v) and about 1% of alcohol (v/v). The acetic fermentation yielded between 91.24 and 97.21%. Approximately 5 L of honey vinegar with 9% acetic acid (w/v) were obtained from 1 Kg of bee honey. All attributes of honey vinegar showed acceptability index over 70%: 95.37% for appearance, 94.81% for color, 79.07% for odor and 75.56% for flavor, indicating it would show good consumer acceptability.

Acetic Acid↗
PubMed1992

[Detection of extended-spectrum beta-lactamases by the rapid ATB E technique. Value of the API V2.1.1 expert system].

Twenty-two extended-spectrum betalactamase-producing strains of enterobacteriaceae recovered in the authors' hospital were tested using the Rapid ATB E coupled with the API V2.1.1. expert system. The expert system detected 90.9% of ESBL-producing strains. Two strains producing a SHV2 and a CTX1, respectively, escaped detection by the expert system despite concomitant resistance to aminoglycosides.

4-Quinolones↗