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  • Springer  (37)
  • Springer Nature  (8)
  • Cell Press  (3)
  • American Association for the Advancement of Science (AAAS)
  • 1985-1989  (49)
  • 1987  (49)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 44 (1987), S. 177-185 
    ISSN: 1570-7458
    Keywords: spotted alfalfa aphid ; Therioaphis trifolii ; aphid-resistant plants ; lucerne = alfalfa ; Medicago sativa ; variation ; bioassay ; antibiosis non-preference ; inter-plant movement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'étude de la multiplication initiale des effectifs de T. trifolii, élevés au laboratoire sur pousses de différents pieds de luzerne, a servi de test d'antibiose pour les cultures en plein champ. La distribution de l'antibiose, dans des échantillons importants de plantes appartenant à des cultivars sélectionnés pour leur résistance aux pucerons, a présenté une forme en J, c'est-à-dire que la majorité des plantes était très résistante, quelques unes apparemment sensibles, et un certain nombre intermédiaires entre ces deux extrêmes. Pour un niveau donné d'antibiose, la reproduction, la mortalité et ainsi la distribution initiale en âges dans les populations de pucerons ont été généralement identiques. La multiplication végétative de plantes présentant un gradient de résistance à l'intérieur d'un cultivar et l'utilisation d'un plan de distribution des boutures ont permis l'étude de ce qui semble être l'effet de l'hétérogénéité spatiale sur la résistance des cultures aux attaques de pucerons. La simulation d'une invasion de la culture par les pucerons en plaçant des adulte sur toutes les boutures d'un rang ne pouvait donner une explication de la croissance de la population que si les pucerons se déplacaient le long du rang pour découvrir et exploiter les pieds les plus sensibles. Une distribution par taches, comme on peut l'envisager dans un champ, ne devrait pas gêner les pucerons, car bien que les mouvements d'évasion soient stimulés par les niveaux de résistance élevés (de non-préférence), on peut en déduire que les pucerons se déplaceront sur des plantes très résistantes, eventuellement pour atteindre des plantes moins résistantes placées derriere.
    Notes: Abstract Initial population growth of spotted alfalfa aphid reared on shoots cut from individual lucerne plants, was tested and used as a realistic bioassay of antibiosis. Within cultivars selected for aphid-resistance there was a J-shaped distribution of antibiosis between plants of the crop, the majority being highly resistant, a few apparently susceptible and a proportion partly-resistant. For a given level of antibiosis, reproduction, mortality and thus initial age distribution of aphid populations were generally similar. Vegetative cloning of plants from the range of resistance available in a cultivar has allowed studies of the likely effect of spatial variation of resistance in crops on aphid infestations, using experimental arrays of cut shoots. Simulation of aphid invasion of crops by the placement of adults on all shoots of an array gave results explicable only if the aphids moved through the array to find and breed on the more susceptible plants. A patchy arrangement of these, as might be expected in a field crop, would not hinder the aphids, for although movement off a plant is stimulated by higher resistance (non-preference) levels, it was inferred that aphids will move onto higher resistance plants, eventually to reach lower resistance plants beyond.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Polar biology 7 (1987), S. 153-162 
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Six major higher plant communities are defined for sub-Antarctic Heard Island: tussock grassland, meadow, herbfield, pool complex, cushion-carpet, fellfield. The communities were mapped at a scale of 1:50000, using colour aerial photographs and field observations. The floristic composition of twelve vegetation transects and of thirty sample quadrats along these is used to describe the communities and identify dominant or indicator species. The vegetation is compared with that of other sub-Antarctic islands.
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  • 3
    ISSN: 1432-2048
    Keywords: Chenopodium ; Photoperception ; Phytochrome ; Shade avoidance ; Stem extension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of far-red light given against a background of white light on the stem-extension kinetics of three-week-old, light-grown Chenopodium album seedlings were investigated. Under white light alone, the stems (cotyledon-to-apex) extended almost exactly logarithmically with time. Under these conditions the increase in log [stem length in mm] per hour was approx. 3.7·10-3, equivalent to about 1% per h during both skoto-and photoperiods. Supplementary far-red given throughout each photoperiod massively stimulated extension. The calculated logarithmic extension rate, however, slowly returned to that of the controls, following an initial large increase. This is predicted by a model in which far-red light linearly increases the extension rate of individual internodes which arise at an exponentially increasing rate. The behaviour of the model is also consistent with critical experiments in which far-red was given as a pre-treatment or transiently, as well as with other published data. Far-red stimulation of logarithmic extension rate in successive photoperiods was closely and linearly correlated with calculated phytochrome photoequilibrium. Daily short periods of supplementary far-red were especially potent in accelerating extension; the plants seemed least responsive at the end of the photoperiod.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 97 (1987), S. 169-182 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Two major swarms of early Proterozoic (ca. 2.1 Ga) basic dykes occur within the Archaean craton of southern West Greenland. One swarm comprises ophitic and sub-ophitic tholeiitic dolerites, while the other (the BN dyke swarm) constitutes mainly norites in which pyroxenes and olivine are enclosed by plagioclase oikocrysts. The close geochemical similarity between a quenched norite and the coarser-grained varieties indicates that the composition of the latter type has not been significantly modified by crystal accumulation. The BN dykes are geochemically distinctive, most having high MgO (ca. 16%), Cr and Ni contents in conjunction with relatively high SiO2, light rare-earth (REE) and large ion lithophile (LIL) element concentrations. The texture, mineral chemistry and petrochemistry of the quenched noritic dyke all bear strong resemblances to those features in modern boninitic lavas. The BN dykes also correspond to proposed parental liquids of the Bushveld Complex and other major layered basic igneous intrusions. The two dyke swarms are petrogenetically distinct. The tholeiitic dolerites were derived from a relatively undepleted, primordial mantle while the noritic dykes originated from a metasomatized harzburgitic source. The wide-spread distribution of similar Proterozoic intrusions suggests crustal underplating by harzburgitic mantle on a world-wide scale at this time.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 97 (1987), S. 292-296 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Several petrologic experiments have demonstrated that in igneous and metamorphic reactions amphibole minerals can break down by a subsolidus dehydration reaction, but evidence for the reaction in natural rocks has been lacking. Evidence for the breakdown of an edenite-pargasite amphibole by a subsolidus dehydration reaction has now been found in an andesite flow from Garner Mountain, southern Cascase Range. The andesite contains one modal percent of ‘crystal clots’ formed of crystallites of opx, cpx, plag, K-spar, opaque and quartz. The crystal clots retain the original amphibole morphology and intra-clot pyroxenes are aligned with crystallographic c parallel to c in the amphibole precursor; these conditions would not be duplicated by a melting reaction. Microprobe analyses of the bulk clot and the intra-clot minerals suggest the solid-state reaction: 100 amph+10 SiO2=〉55 cpx+33 plag+22 opx+ 1 opq+1 kspar Pyroxene thermometry of the andesite groundmass pyroxenes and the intra-clot pyroxenes demonstrates that the amphibole dehydration reaction occurred in the xenocrystic amphiboles as a result of heating by the near-solidus andesite magma.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 87 (1987), S. 91-96 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In human duodenal mucosa Paneth cells originate away from the base of crypts and migrate towards the base during maturation The earliest cells in the Paneth cell lineage could be identified by labelling of lysozyme in the Golgi apparatus. Specific labelling for lysozyme was present in the rough endoplasmic reticulum, Golgi apparatus, condensing vacuoles, granules and many lysosomes of mature Paneth cells. The maturation of the Paneth cell is accompanied by an increase in the content of lysozyme in the secretory granules and with senescence lysozyme diffuses into the cytoplasm.
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  • 7
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We observed significant piezoelectric activity in cast films of poly(1-bicyclobutanecarbonitrile).
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  • 8
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The η ω mass spectrum resulting from diffractive photoproduction, by photons of 25–50 GeV, shows a peak at a mass of 1.61±0.04 GeV and width of 0.23±0.08 GeV. Comparison with the corresponding η ρ0 mass spectrum suggests that a resonance interpretation is favoured.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 43 (1987), S. 31-38 
    ISSN: 1570-7458
    Keywords: development rate ; survival ; reproduction ; intrinsic rate of increase ; effect of temperature ; effect of photoperiod ; physiological time ; temperature limits ; Hyperomyzus lactucae ; Aphididae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La durée du développement, le taux de survie et la fécondité en fonction de l'âge ont été suivis chez les virginipares aptères et ailés du puceron: Hyperomyzus lactucae L., élevé sur Sonchus oleraceus L., et soumis à différentes conditions de température et de lumière. A l'intérieur de la gamme de températures moyennes de 12,5 à 24°C, la vitesse de développement et le rythme de reproduction augmentent, tandis que la longévité et la fécondité totale diminuent. La relation entre la température et la durée du développement est presque linéaire, avec un seuil théorique de développement évalué à environ 2°C. Le taux intrinsèque d'accroissement est lié positivement à la température calculée sur une base quotidienne, mais la relation est inversée quand la température est mesurée sur une échelle physiologique. Pour des conditions d'élevage identiques, les ailés ont eu, dans l'ensemble, une durée de développement plus longue, un taux de reproduction et une fécondité totale plus faibles que les aptères. La comparaison des performances des pucerons sous thermopériodes ou températures constantes, ou entre les générations en conditions identiques, a montré (1) que les conditions subies par l'embryon dans la mère conditionnent la survie et le développement; (2) que les limites des températures tolérables changent en fonction du type et de l'amplitude des fluctuations de température. A 22°C, des modifications de la photopériode, dans la gamme; 12D:12L à 8D:16L, ont eu peu d'effet sur les performances des pucerons.
    Notes: Abstract The development time, survivorship and age-specific fecundity of apterous and alate virginoparae of the sowthistle aphid, Hyperomyzus lactucae (L.) (Homoptera: Aphididae), reared on Sonchus oleraceus L., were measured under various temperature and light regimes. Within the temperature range of daily means of 12.5–24°C, speed of development and reproductive rate increased, while life span and total fecundity decreased, with an increase in temperature. The relationship between temperature and rate of development was nearly linear, with a notional development threshold estimated at about 2°C. The intrinsic rate of increase (rm) was positively correlated with temperature when calculated on a daily basis, but was inversely related to temperature when measured on a physiological time scale. Alatae generally had a longer development time, and achieved a lower reproductive rate and life-time fecundity, than apterae reared under identical conditions. Comparison of aphid performance under constant and alternating temperature regimes, and between successive generations under the same regime, showed that (1) the conditions experienced by the aphid as an embryo within its mother are important in determining survival and development and (2) tolerable temperature limits vary with the pattern and amplitude of the fluctuations of temperature. At 22°C, changes of photoperiod within the range of 12D:12L to 8D:16L had little effect on aphid performance.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of ethology 5 (1987), S. 125-129 
    ISSN: 1439-5444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When removed into the laboratory, the intertidal snailPolinices incei, retains a tidal rhythm in activity for several days when maintained under conditions of constant light. There is, in addition, a gradual decline in activity following collection and a batch to batch effect of some note. When a 12∶12 light regime is maintained there is apparent also a c. 24 h rhythm in activity which may supercede the tidal one under some circumstances. The simplest explanation of the results is that there exist both tidal and diel rhythms. These results are compared with those observed by others for a variety of marine organisms, the adaptiveness of the behaviour pattern is discussed, and the implications of the work for further behavioural studies is explored.
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