1,358 research outputs found
) in agricultural landscapes
No full textAlthough habitat fragmentation and agricultural intensification are known as threads to pollinator diversity, little is known about consequences for population size and genetic diversity. Here, we combined detailed field observations, molecular approaches and GIS-based quantification of landscape structure (measured by proportions of seminatural habitats and proportions of mass flowering crops) to get new insights into driving forces of population dynamics of the bumblebee species Bombus pascuorum. Comparing 13 agriculturally dominated landscape sectors, we found the proportion of mass flowering crops to positively influence bumblebee abundance whereas the proportion of seminatural habitats was of minor importance. We used microsatellites to quantify landscape-related colony densities, inbreeding and population substructure. Detected colony densities did not correlate with landscape parameters or with local worker abundance, measured by field observations. These results indicate that increased worker abundances within landscapes are rather due to greater colony sizes than due to an increased number of nests. We found significant population substructure, measured by F-ST and seven landscape sectors to bear significantly increased inbreeding values (F-IS). F-IS was strongly varying between sectors but did not correlate with landscape structure. Moreover, F-IS had a significantly negative effect on colony size, demonstrating the importance of genetic diversity on population fitness at a landscape scale. We suggest that inbreeding levels might be related to the temporal variation of food resources and population sizes in agricultural landscapes
Bern, Burgerbibliothek, Cod. A 95.5 : Robin Comtet: Panégyrique de Blanche de Navarre (fragment)
No full textFragment of a panegyric on Queen Blanche of Navarre (1331–1398), consisting of almost 400 verses. The author Robin Comtet - who mentions himself toward the end of the piece - is not otherwise known. The poem seems to have been preserved only in this copy and has not yet been published.Online Since: 2018-06-1
Cervico-thoracic kyphosis in a girl with Pierre Robin sequence
No full textCongenital cervico-thoracic kyphosis has been encountered in a girl with Pierre Robin sequence. The constellation of the spine malformation complex such as incomplete development of the vertebral bodies associated with defective ossification of the cervico-thoracic pedicles causing effectively the development of complete spinal cord injury at the kyphotic level of C7/T1 were present. Congenital kyphosis secondary to vertebral body hypoplasia has not been reported in connection with Pierre Robin sequence
Dynamics and folding of single two-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy
No full textWe report single-molecule measurements on the folding and unfolding conformational equilibrium distributions and dynamics of a disulfide crosslinked version of the two-stranded coiled coil from GCN4. The peptide has a fluorescent donor and acceptor at the N termini of its two chains and a Cys disulfide near its C terminus. Thus, folding brings the two N termini of the two chains close together, resulting in an enhancement of fluorescent resonant energy transfer. End-to-end distance distributions have thus been characterized under conditions where the peptide is nearly fully folded (0 M urea), unfolded (7.4 M urea), and in dynamic exchange between folded and unfolded states (3.0 M urea). The distributions have been compared for the peptide freely diffusing in solution and deposited onto aminopropyl silanized glass. As the urea concentration is increased, the mean end-to-end distance shifts to longer distances both in free solution and on the modified surface. The widths of these distributions indicate that the molecules are undergoing millisecond conformational fluctuations. Under all three conditions, these fluctuations gave nonexponential correlations on 1- to 100-ms time scale. A component of the correlation decay that was sensitive to the concentration of urea corresponded to that measured by bulk relaxation kinetics. Thetrajectories provided effective intramolecular diffusion coefficients as a function of the end-to-end distances for the folded and unfolded states. Single-molecule folding studies provide information concerning the distributions of conformational states in the folded, unfolded, and dynamically interconverting states.Author manuscript. Published in final edited form as: Proc Natl Acad Sci U S A. 2000 November 21; 97(24): 13021-13026.The final published version of this article is located at: http://www.pnas.org/cgi/reprint/97/24/13021NIH GM54616; to William F. DeGradoNIH GM12592; to Robin M. HochstrasserNIH GM48130; to William F. Degrado and Robin M. HochstrasserThis work was supported by GM54616 (to W.F.D.), GM12592 (to R.M.H.) and GM48130 (to W.F.D. and R.M.H.) with instrumentation developed under RR01348. D.S.T. was supported by National Institutes of Health Grant NRSA F32-GM18589.Also available in PubMed Central. PMCID:PMC2717
The genetic control of the social parasitism in the Cape honey bee, A. m. capensis ESCH
No full textDiese Arbeit befasst sich mit der genetischen Kontrolle des sozialen Parasitismus der Kapbiene, A. m. capensis. Im ersten Teil dieser Arbeit ergab eine Mikrosatelliten-basierte Analyse Hinweise, dass Thelytokie in der Kapbiene von einem genetischen Locus kontrolliert wird. Im zweiten Teil dieser Arbeit werden Next-Generation-Sequencing Daten der mapping population generiert. Die anschließenden SNP-Analysen führten zur Identifizierung des Thelytokie-kontrollierenden Locus. Zudem wird ein balanciert nachteiliges Allelsystem abgeleitet, das erklärt weshalb Thelytokie nur bei Kapbienen vorkommt. Im dritten Teil dieser Arbeit wird die Entwicklung von A. m. capensis sozialen Parasiten mit sozialen Arbeiterinnen, unter Verwendung von RNAseq-Daten aufeinanderfolgender Zeitpunkte, verglichen. Gene, die in die Entwicklung von sozialen Parasiten involviert sind, wurden identifizieren.This thesis examines the genetic control of the social parasitism of the Cape bee, A. m. capensis. In the first part of this thesis, a microsatellite-based analysis of a wild A. m. capensis mapping population provided support that thelytoky in the Cape bee is controlled by a single genetic locus. In the second part of this thesis, next generation sequencing data of the mapping population are generated. The subsequent SNP analyses led to the identification of the thelytoky controlling locus. Additionally, a balanced detrimental allele system was inferred, which explains why thelytoky only occurs in A. m. capensis. In the third part of this thesis, the development of A. m. capensis social parasites and social workers are compared using RNAseq data of subsequent time points. Genes that are involved in the development of A. m. capensis social parasites are identified.vorgelegt von Denise Aume
THE QUALITY OF HONEY FOR BEES AND MAN
No full textHoney is used both as food ingredient and in a variety of treatments for diverse ailments. For this reason, consumer expectation of its quality and purity is particularly high. The aim of the BEE SHOP Honey Department was the evaluation of honey quality and authenticity, through the development of new instrument for the verification of the botanical origin and the presence of impurities. Honey quality can be important also for the colony itself and therefore the Honey Department focused on the physiological properties of honey which can be beneficial for honeybees and for the prevention of bee diseases. Testing the origin of honeybees is also important to enforce the EC directive for organic beekeeping, since the use of regional bee strains is an important quality criterion for organic honey. To identify the origin of the honeybee the BEE SHOP Honey Department has developed a DNA based diagnostic tool. Through the analysis of honey and nectar samples by HPLC-MS-MS methods, suitable markers were detected for Robinia, Tilia, Citrus, Eucalyptus and chestnut unifloral honeys, and the following phytochemicals have been proposed for the determination of honey floral origins: myricetin, tricetin and luteolin for Eucalyptushoney, kynurenic acid related compounds for chestnut honey, terpenoids for Linden honey, hesperetin for Citrus honey, kaempferol rhamnosides for Acacia (Robinia) honey. Two novel protocols were introduced for the evaluation of honey quality: DRIFTS (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) and HR-NMR (High Resolution Nuclear Magnetic Resonance). These techniques, coupled with appropriate multivariate statistical analysis, demonstrated to be suitable for the verification of botanical origin and the detection of honey adulteration by sugar syrups. The HR-NMR method seems to be suitable also for a quantitative determination of the adulteration levels. A new sensitive enzyme-linked immunoassay (ELISA) for the quantitative determination of apalbumin1a major compound of the royal jelly (RJ) proteins in honey has been developed. This protein can be used as a marker for honey quality because its concentration varies with the botanical origin. The highest content was determined in chestnut honey, in comparison with acacia and rape honey, while the lowest amount was detected in honey obtained supplying bee colony with saccharose syrup. The antimicrobial potential of honey based on proteins of honeybee origin was tested by microtiter based assays. The inhibition of P. larvae growth was observed in the protein fraction of cherry and rape honeys and honeydew. Moreover, a protein fraction corresponding to apalbumin2a has been identified in honey. This protein, purified from RJ, had specific antibiotic properties against P. larvae. The anti quorum-sensing (QS) activities of honeys with different floral origin have been evaluated, using bacterial strains in which quorum-sensing activated the pigment violacein. 29 honey samples inhibited QS even at the lowest concentration. The anti-QS activity was concentration-dependent and relied on the floral origin. Among all honeys, chestnut and linden samples were the strongest quorum-sensing inhibitors (QSI)
Pheromone-mediated reproductive dominance hierarchies among pseudo-clonal honeybee workers (Apis mellifera capensis)
No full textHoney bee colonies are characterised by well-developed reproductive division of labour between the queen and workers. Here, we test whether this reproductive division of labour is evident in both the socially parasitic workers that invade a colony as well as in their offspring generation. We infected six Apis mellifera scutellata host colonies with pseudo-clonal socially parasitic Cape honeybee workers (Apis mellifera capensis). We show that the first generation of socially parasitic workers can monopolize reproduction within host colonies. Of the initially invading parasites, 94.4% became reproductive pseudoqueens with activated ovaries and produced queen-like pheromones. Their offspring, however, had much lower levels of ovary activation (3.1%), yet 89% showed fatty acid synthesis typical of the queen substance (9-oxo-2(E)-decenoic acid) biochemical pathway. However, in these second-generation workers, the last oxidation step from the precursor (9-hydroxy-2(E)-decenoic acid) to the queen substance was interrupted and appears to be required for reproductive dominance in honeybee workers. Our data show that despite the absence of genetic diversity, residual queen mandibular pheromone (QMP) variation is sufficient to establish reproductive dominance hierarchies among parasitic workers. Consequently, QMP produced by a group of workers can maintain reproductive division of labour in queenless honeybee colonies
The wild honeybees of Sudan - a test case for conservation, apiculture and invasive species
No full textWegen des vielfachen Imports von europäischen Honigbienen Apis mellifera und der zufälligen Einführung der Zwerghonigbiene Apis florea in den Sudan, untersuchte ich die möglichen Auswirkungen dieser beiden Arten auf die einheimischen Honigbienen des Sudans. Maternale Introgression in lokale Genpools wurde durch Genotypisierung der mitochondrialen (mt) DNA von wilden Bienenvölkern aus dem ganzen Land erfasst. Die nativen Bienen im Sudan tragen sechs verschiedene mt-Haplotypen (A1 , A4, A8 , A13, O1, O1’). Nur in den Regionen, in denen Imkerei betrieben wird, finden sich auch Bienenvölker mit dem europäischen Haplotyp C2. Obwohl es keine Hinweise auf maternale Introgression durch Schwärmen von Bienenvölkern gibt, findet in Regionen mit kommerzieller Imkerei Introgression in lokale Genpools durch die Paarung von Königinnen mit Drohnen europäischer Herkunft statt. Beide eingeführte Arten haben bisher nicht zu einem Verdrängungswettbewerb mit den nativen Bienen aus dem Sudan geführt. Allerdings hat Apis florea höhere Volksdichten als die einheimischen wilden Kolonien von A. mellifera. Dies deutet darauf hin, dass die Zwerghonigbiene im Sudan ein hohes invasives Potential besitzt.von Mogbel Ahmed Abdalla El-Niweir
INBREEDING EFFECTS IN FLIGHT MUSCLE MITOCHONDRIA OF Apis mellifera L.
No full textln f-light muscle mitochondria of drones and rvorkcrs lApis mellifera L.) cnzymc activities shorved srgnrficant changes after inbrecding. fhe genonre sccms to llrve only moderatc etlect on this mitochondrial inbreeding depression. It is shou.n that mainll'cytoplasmic factors are aft-ecting thc changcs in enzymc activitl'observed after inbrecding
Reproductive biology of the Cape honeybee : a critique of Beekman et al.
No full textA critique of “Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually”: Laying workers of the Cape honeybee parthenogenetically produce female offspring whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in A. m. capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator and we therefore suggest that these “homozygous” larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeders.http://www.ncbi.nlm.nih.gov/pubmed/22581844ab201
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