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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of 4-methylumbelliferyl 1,2-cis-glycosides
    Amsterdam : Elsevier
    Carbohydrate Research 65 (1978), S. 23-33 
    Details
    ISSN: 0008-6215
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0008-6215(00)84209-3
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  • 2
    Electronic Resource
    Electronic Resource
    Diploid males in the bumble beeBombus terrestris (1994)
    Springer
    Entomologia experimentalis et applicata 71 (1994), S. 263-269 
    Details
    ISSN: 1570-7458
    Keywords: Bombus terrestris ; bumble bee breeding ; diploid males ; sex determination ; sex alleles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The frequency of colonies that produce diploid males after brother-sister (50%) and nephew-niece (37.5%) matings proves that inB. terrestris the sex is determined by a single multi-allelic sex locus. The diploid males which develop normally into adults make up 50% of the diploid brood. In the laboratory the growth rate of colonies with diploid males is influenced only slightly. Of 41 colony founding queens caught out of a natural population, all produced a colony without any diploid males. Therefore, the number of sex alleles in this population is estimated to be at least 24. This means that in commercial rearing systems for bumble bees, involving several generations, the occurrence of diploid males can largely be prevented by a good scheme for crossings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426410
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  • 3
    Electronic Resource
    Electronic Resource
    Ovarian development and egg laying in workers of Bombus terrestris (1989)
    Springer
    Entomologia experimentalis et applicata 51 (1989), S. 199-213 
    Details
    ISSN: 1570-7458
    Keywords: Bombus terrestris ; oogenesis ; worker oviposition ; classification of ovarian development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Nous avons cherché à répondre aux trois questions suivantes concernant la régulation de l'ovogenèse et la ponte des reines et des ouvrières: a) quels facteurs influencent l'ovogenèse et la ponte consécutive, au niveau individuel? b) Quel est l'impact des facteurs sociaux et de la présence de la reine sur l'activité ovarienne et la ponte des ouvrières, au niveau de la colonie? c) Est-ce que l'ovogenèse des ouvrières est liée à la ponte des reines, particulièrement lorsqu'elle passe d'une ponte en majorité à œufs diploïdes femelles, à une ponte à œufs haploïdes mâles? Quand les ouvrières naissant dans une colonie normale, leurs ovaires se développent jusqu'à 10 jours. A ce moment, environ 40% des abeilles contiennent des œufs mûrs, tandis que les ovocytes des autres sont à un état intermédiaire. Ni la durée du développement de l'œuf à l'adulte, ni la taille du corps n'interviennent pour déterminer quelle ouvrière produira des œufs ou pas. Chez les abeilles adultes, la fréquence d'alimentation des larves et l'activité de la glande hypopharyngienne n'ont aucune relation avec l'activité ovarienne. Les ovaires des abeilles qui n'ont pas de contact avec le pollen ne se développent pas, et le corps gras de ces abeilles est relativement petit. La prospection dans la nature est liée à une faible activité ovarienne; cependant des abeilles qui ont été prospectrices peuvent devenir ultérieurement des ouvrières pondeuses surtout si elles appartiennent à la première ou à la seconde couvée. Les interactions sociales entre ouvrières ou entre reine et ouvrières stimulent l'activité, entraînant une activation des ovaires. Cependant, la reine a un léger effet inhibiteur, tel que l'activité ovarienne des ouvrières de 5–8 jours est plus faible que dans les groupes sans reine. Cependant, les vieilles abeilles des groupes avec reine ont une activité ovarienne presque aussi élevée que celles des groupes sans reine. Dans les groupes sans reine certaines ouvrières pondent à partir du septième jour, tandis que dans les colonies avec reine, cette dernière inhibe la ponte des ouvrières jusqu'à 30 jours. Par conséquent, la reine a deux effets différents sur la reproduction des ouvrières: un effet physiologique et un effet comportemental. Le niveau ovarien des ouvrières est sans effet sur le passage de la reine à la ponte d'œufs haploïdes, de même que ce passage n'aura pas d'influence sur l'activité ovarienne ultérieure des ouvrières. Il n'y a de même aucune relation entre le moment de ce passage à la ponte haploïde et l'apparition de pontes chez les ouvrières.
    Notes: Abstract Answers were sought to three questions to the regulation of oogenesis and ovipositions by the bumblebee queen and by her workers: a) Which factors have an effect on oogenesis and subsequent ovipositions at the individual level? b) What impact do social factors and the presence of the queen have on ovary activation and egg laying by workers at colony level? c) Is oogenesis in workers related to egg laying by the queen, particularly to her switch from laying diploid, female biased eggs to haploid, male producing eggs? When workers emerge, in queenright colonies, their ovaries start to develop and become increasingly up to the age of about 10 days. By that time about 40% of the bees contain ripe eggs, whereas in the other bees the oocytes remain in an intermediate stage. Neither developmental time from egg to adult nor body size has an influence in determining which workers will develop mature eggs and which will not. In adult bees the frequency of feeding larvae or the activity of the hypopharyngeal gland are not related to ovarian activity. The ovaries of bees that have no access to pollen do not develop, and the fat bodies of these bees are relatively small. Foraging in the field is correlated with low ovarian activity. However, bees that once were foragers can become laying workers later on in life, especially if they belong to the first and second brood. Social interactions between workers or between a worker and a queen stimulate activity, leading to activation of the ovaries. The queen, however, also has a slight inhibitory effect, so that in workers aged 5–8 days ovarian activity is lower than in queenless groups. In older bees from queenright groups ovarian activity levels are almost the same as in groups of queenless workers. In queenless groups some of the workers lay eggs from the age of 7 days onwards, whereas in colonies and queenright groups the queen prevents all worker ovipositions for about 31 days. The queen, therefore, has two different effects on the reproductive characteristics of the worker, a physiological one and a behavioural one. Ovarian development levels in the worker population do not affect the switch of the queen to the laying of haploid eggs, nor does this switch has any influence on the degree of ovarian activity of the worker population later on. There is also no relation between the moment of the switch and the occurrence of worker ovipositions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347883
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  • 4
    Electronic Resource
    Electronic Resource
    Early sex determination in larvae ofBombus terrestris (1990)
    Springer
    Insectes sociaux 37 (1990), S. 232-235 
    Details
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Une méthode est décrite pour déterminer de façon aisée et précise le sexe de tous les stades larvaires du bourdon. La méthode est également applicable à d'autres espèces d'abeilles.
    Notes: Summary A method is described for an easy and accurate sex determination forall larval stages of the bumble bee. The method is also applicable to other species of bees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02224050
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  • 5
    Electronic Resource
    Electronic Resource
    Sexual biology of haploid and diploid males in the bumble beeBombus terrestris (1995)
    Springer
    Insectes sociaux 42 (1995), S. 255-266 
    Details
    ISSN: 1420-9098
    Keywords: Bombus terrestris ; diploid males ; size ; spermatozoa ; mating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InB. terrestris diploid males develop normally into adults (Duchateau et al., 1994). The diploid males are similar in appearance to the haploid males, except that they are smaller. The size of the testis of diploid males, relative to the length of the radial cell, is smaller than that of haploid males. There is overlap in the frequency distribution with respect to body size and testis size. The spermatozoa of diploid males are larger than those of the haploids and the vasa deferentia contain fair less spermatozoa than those of haploid males of the same age. Countings and measurements of the spermatozoa, therefore, can give the best indication about the ploidy of the males. Diploid males are successful in mating. They mate at a younger age than haploid males and they die sooner. The number of vial offspring of diploid males, however, is very low. No queen that mated with a diploid male produced a colony, but a few queens did produce some progeny. These might have been triploid males and workers. InB. terrestris higher ploidy results in smaller individuals, whereas in several other species of the Hymenoptera it has been found to result in larger individuals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240420
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  • 6
    Electronic Resource
    Electronic Resource
    Feeding frequency and caste differentiation in Bombus terrestris larvae (1999)
    Springer
    Insectes sociaux 46 (1999), S. 306-314 
    Details
    ISSN: 1420-9098
    Keywords: Key words:Bombus terrestris, bumble bee, feeding frequency, caste differentiation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: The frequency with which bumble bee larvae are fed during their development was studied using video-recordings. The behaviour of the workers while feeding worker, male and queen larvae of Bombus terrestris was recorded. At the beginning of development, female larvae of both castes were fed at a similar frequency. However, during their last phase queen larvae were fed much more often than worker larvae. Despite the differences in frequency, both queen and worker larval feeding followed a similar pattern. Male larvae were fed more often than worker larvae, but less often than queen larvae. They also differed from the female larvae in the way their feeding frequency increased during development. This suggests that the process of feeding male larvae occurs in a different way.¶The time intervals between feedings were very variable for all larvae: from a few seconds up to 3 h. Although there was a general tendency for the intervals to decrease in duration with larval development, the irregularity was always present.¶The differences in feeding frequency found at the individual level for larvae of the same age and the irregularity of the feeding process can be explained by the variation in the amount of food per feeding.¶Finally, our data suggest that larvae play an active role in the regulation of the feeding process. This subject is discussed and compared to the situation in honey bees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000400050150
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  • 7
    Electronic Resource
    Electronic Resource
    Cauda equina syndrome in ankylosing spondylitis (1981)
    Springer
    Acta neurochirurgica 55 (1981), S. 303-315 
    Details
    ISSN: 0942-0940
    Keywords: Ankylosing spondylitis ; Bechterew's disease ; rhizomelic arthritis ; cauda equina syndrome ; CT Scan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This article describes a case of cauda equina syndrome associated with ankylosing spondylitis, and reviews 28 additional cases in the literature. The neurological symptoms appear late in the evolution of spondylitis, when it is at an inactive stage. The diagnosis is easily confirmed by myelography, with water-soluble contrast and performed in a supine position, and by computerized tomography (CT) scan of the lumbar spine. The typical features are a dilated lumbar sac with multiple dorsal diverticula. The pathogenesis of this entity remains the subject of speculation. Arachnoiditis with subsequent adhesions is the most likely explanation. No treatment has proved helpful so far. Surgery is not indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01808446
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  • 8
    Electronic Resource
    Electronic Resource
    Agonistic behaviours in colonies of the bumblebeeBombus terrestris (1989)
    Springer
    Journal of ethology 7 (1989), S. 141-151 
    Details
    ISSN: 1439-5444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first aim of this study was to investigate whether specific changes in the frequencies of behavioural characteristics are correlated with the cause or reflect the onset of the laying of haploid eggs by the queen, and whether these changes cause the onset of egg laying and aggressive behaviour by workers. The second aim was to obtain a better understanding of the occurrence of the behaviours in relation to the physiology and function of the queen and the workers. No behavioural characteristics of workers which could predict the occurrence of the queen's switch to haploid egg laying was found nor did any such behaviour indicate that the switch had already occurred. The onset of worker oviposition was not found to be the consequence of the level or the type of agonistic actions between the workers and the queen. With the onset of worker oviposition the agonistic behaviours called trembling and buzzing, which are directed at the queen, disappear. At the same time the frequency of a non-directed behaviour, called humming, increases. This behaviour is seen particularly in the small housebees with developed ovaries. Before worker oviposition begins, the frequencies with which individual workers perform agonistic behaviour are not correlated with the conditions of their ovaries nor correlated with other characteristics of the workers. However, these frequencies are related to the sequence in which workers emerge. The correlations with age are due to the fact that workers of the first brood have higher activity levels than those of the later broods. The first egg layers are to be found among the first workers. In the period of worker oviposition, humming and the aggressive behaviours of darting and attack are performed by workers with developed ovaries. These behaviours are directed particularly towards workers who also have active ovaries. If the queen has disappeared 1 worker usually becomes dominant. This worker is characterized by the relatively high frequency with which she engages in darting and attacks. In addition, this worker is characterized by a specific behaviour, called pumping, which is directed at workers that have mature eggs in their ovaries. Behavioural domination, however, is no guarantee that the bee concerned will eventually become the most productive one. Although at an apparently pre-determined moment in the ontogeny of the colony the queen loses control over worker oviposition and related behaviours, she remains dominant in various other behavioural hierarchies. It is therefore concluded that the queen never loses dominance completely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02350036
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  • 9
    Electronic Resource
    Electronic Resource
    Pb2PdX6 (X = Cl, Br) - Verbindungen mit gestreckten [PdX6]-OktaedernProfessor Hanskarl Müller-Buschbaum zum 65. Geburtstage gewidmet (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 1231-1235 
    Details
    ISSN: 0044-2313
    Keywords: Dilead(II)-hexahalogenopalladate(II) ; crystal structure ; strongly elongated PdX6 octahedra ; DTA, IR/RAMAN, 207Pb MAS NMR ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Pb2PdX6 (X = Cl, Br) - Compounds with Elongated [PdX6] OctahedraIn contradiction to published data new compounds in the systems PbX2 - PdX2 (X = Cl, Br) with the formula Pb2PdCl6 (I) and Pb2PdBr6 (II) were found. These were synthesized by thermal treatment of the corresponding mixtures of PbX2 and PdX2 (X = Cl, Br). X-ray single crystal structure analysis shows isotypism of I and II, monoclinic, P21/c (No. 14), Z = 2, I: a = 9.037(2) Å, b = 6.224(1) Å, c = 8.162(1) Å, β = 90.31(7)β, II: a = 9.512(7) Å, b = 6.584(8) Å, c = 8.383(3) Å, β = 90.07(5)º. Strongly elongated PdX6 octahedra are found in the crystal structure. Additional characterisation of the compounds was done by DTA, IR/RAMAN spectra and 207Pb MAS NMR investigations. Remarcable low field shifts were found for 207Pb.
    Notes: Entgegen Literaturangaben wurden in den Systemen PbX2 - PdX2 (X = Cl, Br) die neuen Verbindungen Pb2PdCl6(I) und Pb2PdBr6(II) aufgefunden. Sie wurden durch thermische Behandlung der binären Halogenide PbX2 und PdX2 im molaren Verhältnis 2:1 dargestellt (Einkristalle). Die Kristallstrukturen wurden mit Einkristallröntgenuntersuchungen ermittelt. I und II sind isotyp, monoklin, P21/c (Nr. 14), Z = 2, I: a = 9,037(2) Å, b = 6,224(1) Å, c = 8,162(1) Å, β = 90,31(7)º, II: a = 9,512(7) Å, b = 6,584(8) Å, c = 8,383(3) Å, β = 90,07(5)º. In Pb2PdX6 werden stark gestreckte PdX6-Oktaeder beobachtet. Die Verbindungen wurden außerdem mittels DTA, IR/RAMAN-Spektren und 207Pb-MAS-NMR-Untersuchungen charakterisiert. Für 207Pb wurde eine bemerkenswerte Tieffeldverschiebung beobachtet.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220721
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