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At least 1,009 records · Page 56Linked to original sources
PubMed1976

Role of intracellular calcium and sodium in light adaptation in the retina of the honey bee drone (Apis mellifera, L).

In the honey bee drone, the decrease in sensitivity to light of a retinula cell exposed to background illumination was found to be accurately reflected by the difference in amplitude between the initial transient depolarization and the lowest steady depolarization evoked by the background light. It is shown that both the decrease in sensitivity to light and the accompanying drop in potential from the transient to the plateau can be prevented by injecting EGTA intracellularly. A decrease in duration and amplitude of responses to short test flashes such as observed immediately after illumination was found to occur too when Ca or Na, but not K, Li, or Mg injected into dark-adapted retinula cells. Injection of EGTA into a retinula cell maintained a steady state of light adaptation, was found to cause an increase in amplitude and duration of the response to a short test flash, thus producing the effects of dark adaptation. It is suggested that, in the retina of the honey bee drone, an increase in intracellular calcium concentration plays a central role in light adaptation and that an increase in intracellular sodium concentration, resulting from the influx of sodium ions during the responses to light, could lead to this increase in intracellular free calcium.

Adaptation, Ocular↗
PubMed1982

Kinetics of oxygen consumption after a single flash of light in photoreceptors of the drone (Apis mellifera).

The time course of the rate of oxygen consumption (QO2) after a single flash of light has been measured in 300-micrometers slices of drone retina at 22 degrees C. To measure delta QO2(t), the change in QO2 from its level in darkness, the transients of the partial pressure of O2 (PO2) were recorded with O2 microelectrodes simultaneously in two sites in the slice and delta QO2 was calculated by a computer using Fourier transforms. After a 40-ms flash of intense light, delta QO2, reached a peak of 40 microliters O2/g.min and then declined exponentially to the baseline with a time constant tau 1 = 4.96 +/- 0.49 s (SD, n = 10). The rising phase was characterized by a time constant tau 2 = 1.90 +/- 0.35 s (SD, n = 10). The peak amplitude of delta QO2 increased linearly with the log of the light intensity. Replacement of Na+ by choline, known to decrease greatly the light-induced transmembrane current, caused a 63% decrease of delta QO2. With these changes, however, the kinetics of delta QO2 (t) were unchanged. This suggest that the recovery phase is rate-limited by a single reaction with apparent first-order kinetics. Evidence is provided that suggests that this reaction may be the working of the sodium pump. Exposure of the retina to high concentrations of ouabain or strophanthidin (inhibitors of the sodium pump) reduced the peak amplitude of delta QO2 by approximately 80% and increased tau 1. The increase of tau 1 was an exponential function of the time of exposure to the cardioactive steroids. Hence, it seems likely that the greatest part of delta QO2 is used for the working of the pump, whose activity is the mechanism underlying the rate constant of the descending limb of delta QO2 (t).

Animals↗
PubMed1983

Microspectrophotometry of single rhabdoms in the retina of the honeybee drone (Apis mellifera male).

The relative absorption spectra of the bistable photopigment of single rhabdoms from the dorsal region of the retina of the honeybee drone were obtained using slices of retina fixed in glutaraldehyde; less accurate measurements on unfixed tissue gave difference spectra that were similar to those for fixed retinae. The method used was based on measurements of absorbance changes during saturating adaptations of the visual pigment to different monochromatic lights. It is similar to previous methods based on measurements of difference spectra amplitudes, but is simpler to use and more accurate. The predominant pigment has states that absorb maximally at 446 (rhodopsin) and 505 nm (metarhodopsin). In addition, there is a small amount of another pigment whose two states absorb maximally at approximately 340 (UV) and 460 nm.

Animals↗
PubMed1999

Size analysis of a pressurized metered dose inhaler-delivered suspension formulation by the API Aerosizer time-of-flight aerodynamic particle size analyzer.

Aerosizer time-of-flight (TOF) aerodynamic particle size analyzers (TSI-Amherst, Amherst, MA) are widely used for the rapid assessment of aerosols from a wide variety of drug delivery devices, including pressurized metered dose inhalers (pMDIs). This technique offers significant advantages in terms of rapid measurement times in comparison with the more time-consuming compendial methods such as the cascade impactor or multistage liquid impinger. Particle size analysis takes place by determining the TOF of individual particles following acceleration to supersonic velocity. No drug assay is performed; thus, the resulting size distribution also includes particles that do not contain any medication such as the excipients and surfactant that are present in most pMDI-based formulations. Illustrative data are presented for one particular formulation (Pulmicort: 200 micrograms of budesonide per dose; Astra Draco; Lund, Sweden) and demonstrate that bias from this source can significantly shift the reported particle distribution to finer sizes compared with impactor-based analysis in which direct assay for drug has taken place. In this case, the mass median aerodynamic diameter (MMAD) determined by an Aerosizer-LD was close to 2.4 microns, but was found to be approximately 4 microns using the cascade impactor-based procedure. Such a shift results in an overestimation of the fine particle fraction of the emitted dose, which may lead to misleading conclusions about the therapeutic benefit of a particular drug delivery system when making use of this formulation. TOF aerosol measurement techniques appear to be vulnerable to this type of bias for any suspension formulation in which the drug content is not homogeneously distributed within all particle sizes.

Bronchodilator Agents↗
PubMed2006

The SBML ODE Solver Library: a native API for symbolic and fast numerical analysis of reaction networks.

The SBML ODE Solver Library (SOSlib) is a programming library for symbolic and numerical analysis of chemical reaction network models encoded in the Systems Biology Markup Language (SBML). It is written in ISO C and distributed under the open source LGPL license. The package employs libSBML structures for formula representation and associated functions to construct a system of ordinary differential equations, their Jacobian matrix and other derivatives. SUNDIALS' CVODES is incorporated for numerical integration and sensitivity analysis. Preliminary benchmarking results give a rough overview on the behavior of different tools and are discussed in the Supplementary Material. The native application program interface provides fine-grained interfaces to all internal data structures, symbolic operations and numerical routines, enabling the construction of very efficient analytic applications and hybrid or multi-scale solvers with interfaces to SBML and non SBML data sources. Optional modules based on XMGrace and Graphviz allow quick inspection of structure and dynamics.

Algorithms↗
PubMed1998

Separation, characterization and sexual heterogeneity of multiple putative odorant-binding proteins in the honeybee Apis mellifera L. (Hymenoptera: Apidea).

According to precise molar mass determined by mass spectrometry and N-terminal sequence, some 25 odorant-binding-like proteins were characterized from the antennae and legs of worker and drone honeybees. Antennal specific proteins, composed of six different molecules, were classified into three subclasses according to N-terminal sequence homology. The major sexual difference was shown to lie in the relative abundance of these antennal specific proteins and in the occurrence of a drone-specific isoform. At least 19 other related proteins were found to occur in antennae and legs, forming another class showing homology with insect OBP. Genotype comparison of two honeybee races revealed a variability limited to this second class. Provided that these odorant-binding-like proteins are indeed able to bind odorants or pheromones, the question of whether their peculiar multiplicity contributes to the remarkable capacity of the honeybee to discriminate among a wide range of odor molecules is raised.

Amino Acid Sequence↗
PubMed2004

Different thresholds for detection and discrimination of odors in the honey bee (Apis mellifera).

Naturally occurring odors used by animals for mate recognition, food identification and other purposes must be detected at concentrations that vary across several orders of magnitude. Olfactory systems must therefore have the capacity to represent odors over a large range of concentrations regardless of dramatic changes in the salience, or perceived intensity, of a stimulus. The stability of the representation of an odor relative to other odors across concentration has not been extensively evaluated. We tested the ability of honey bees to discriminate pure odorants across a range of concentrations at and above their detection threshold. Our study showed that pure odorant compounds became progressively easier for honey bees to discriminate with increasing concentration. Discrimination is, therefore, a function of odorant concentration. We hypothesize that the recruitment of sensory cell populations across a range of concentrations may be important for odor coding, perhaps by changing its perceptual qualities or by increasing its salience against background stimuli, and that this mechanism is a general property of olfactory systems.

Animals↗
PubMed1991

Putative origin and function of the intergenic region between COI and COII of Apis mellifera L. mitochondrial DNA.

The mitochondrial genome of honeybees is characterized by the presence of a long intergenic sequence located between the COI and COII genes. In addition, the length of this sequence varies between and within subspecies. Four length categories (200, 250, 450 and 650 bp) have been found in 63 sampled colonies. Analysis of the sequence of the largest type reveals the existence of two units: P (54 bp, 100% A + T) and Q (196 bp, 93.4% A + T). The lengths encountered in the sample are explained by the following combinations: Q, PQ, PQQ and PQQQ. According to similarities in primary and secondary structures, the sequence Q has been divided into three parts: Q1 (similar to the 3' end of the COI gene), Q2 (similar to the neighboring tRNA(leu) gene) and Q3 (highly similar to the P sequence). These relationships led us to hypothesize that these sequences, which do not have any counterpart in Drosophila yakuba mitochondrial DNA (mtDNA), arose by tandem duplication. The usual location of length variation in mtDNA control regions prompted us to examine the hypothesis that this COI-COII intergenic region might contain an origin of replication. High A + T content, stability profile, hairpin and cloverleaf putative secondary structures are all in favor of this hypothesis.

Amino Acid Sequence↗
PubMed1995

Linkage map of the honey bee, Apis mellifera, based on RAPD markers.

A linkage map was constructed for the honey bee based on the segregation of 365 random amplified polymorphic DNA (RAPD) markers in haploid male progeny of a single female bee. The X locus for sex determination and genes for black body color and malate dehydrogenase were mapped to separate linkage groups. RAPD markers were very efficient for mapping, with an average of about 2.8 loci mapped for each 10-nucleotide primer that was used in polymerase chain reactions. The mean interval size between markers on the map was 9.1 cM. The map covered 3110 cM of linked markers on 26 linkage groups. We estimate the total genome size to be approximately 3450 cM. The size of the map indicated a very high recombination rate for the honey bee. The relationship of physical to genetic distance was estimated at 52 kb/cM, suggesting that map-based cloning of genes will be feasible for this species.

Animals↗
PubMed1999

Unusually high recombination rate detected in the sex locus region of the honey bee (Apis mellifera).

Sex determination in Hymenoptera is controlled by haplo-diploidy in which unfertilized eggs develop into fertile haploid males. A single sex determination locus with several complementary alleles was proposed for Hymenoptera [so-called complementary sex determination (CSD)]. Heterozygotes at the sex determination locus are normal, fertile females, whereas diploid zygotes that are homozygous develop into sterile males. This results in a strong heterozygote advantage, and the sex locus exhibits extreme polymorphism maintained by overdominant selection. We characterized the sex-determining region by genetic linkage and physical mapping analyses. Detailed linkage and physical mapping studies showed that the recombination rate is <44 kb/cM in the sex-determining region. Comparing genetic map distance along the linkage group III in three crosses revealed a large marker gap in the sex-determining region, suggesting that the recombination rate is high. We suggest that a "hotspot" for recombination has resulted here because of selection for combining favorable genotypes, and perhaps as a result of selection against deleterious mutations. The mapping data, based on long-range restriction mapping, suggest that the Q DNA-marker is within 20,000 bp of the sex locus, which should accelerate molecular analyses.

Animals↗
PubMed1975

Sex determination in bees. II. Additivity of maleness genes in Apis mellifera.

Twenty-two randomly taken morphological characters were used in order to estimate the Mahalanobis generalized distance between diploid males, diploid workers, haploid males and triploid workers. It was found that adult diploid males are metamales and triploid females are slightly masculinized. These facts indicate that the maleness genesare slightly additive.

Alleles↗
PubMed1980

The evolution of multiple mating behavior by honey bee queens (Apis mellifera L.).

A model is presented showing that natural selection operating at the individual level can adequately explain the evolution of multiple mating behavior by honey bee queens. Group selection need not be invoked. The fitness of a given female genotype is a function of the number of sex alleles in the population, the number of matings by an individual female and the specific parameters that determine the relationship of brood viability to individual fitness. Even though the exact relationship is not known, it is almost certainly not linear. A nonlinear relationship between worker brood viability and fitness and a significant genetic load associated with the sex-determination system in honey bees are the essential components of this model.

Animals↗
PubMed2000

Ovarian stimulation during assisted reproduction treatment: a comparison of recombinant and highly purified urinary human FSH. On behalf of The Feronia and Apis study group.

This randomized, single-blind, multicentre, multinational study compared recombinant human FSH (rhFSH, Gonal-F) with highly purified urinary human FSH (uhFSH, Metrodin HP) in women undergoing ovarian stimulation for IVF/intracytoplasmic sperm injection (ICSI). Following desensitization in a long gonadotrophin-releasing hormone (GnRH) agonist protocol, patients received s.c. Gonal-F or Metrodin HP, at a fixed dose of 150 IU, until there was adequate follicular development. Of 496 women randomized, 232 and 231 in the Gonal-F and Metrodin HP groups respectively received human chorionic gonadotrophin (HCG). The duration of FSH treatment was significantly shorter with Gonal-F than with Metrodin HP (11.6 +/- 1.9 days versus 12. 4 +/- 2.7 days; P < 0.0001) and significantly fewer ampoules were required (mean 22.6 +/- 5.0 versus 24.3 +/- 5.1, P < 0.0002). There were, however, significantly more follicles > or =10 mm in diameter with Gonal-F (15.6 +/- 8.2 versus 13.6 +/- 7.1, P < 0.01) and oocytes retrieved (13.1 +/- 7.7 versus 11.4 +/- 7.6, P < 0.002). Although no statistical difference in pregnancy rate was recorded, patients receiving Gonal-F had a higher pregnancy rate per cycle than patients given Metrodin HP (25.1 versus 20.1%). Moderate to severe ovarian hyperstimulation syndrome occurred in 2.8 and 1.2% of Gonal-F and Metrodin HP patients respectively (not significant). In conclusion, FSH stimulation in combination with a long GnRH agonist protocol is effective in inducing multiple follicular development and embryos with a high implantation potential. However, Gonal-F is clearly more effective than Metrodin HP in inducing multifollicular development.

Adult↗