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  • Springer  (25)
  • International Union of Crystallography  (1)
  • 1990-1994  (17)
  • 1985-1989  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Flavonoids as plant signals to rhizosphere microbes (1992)
    Springer
    Mycorrhiza 1 (1992), S. 55-58 
    Details
    ISSN: 1432-1890
    Keywords: Glomus ; Nodulation ; Rhizobium ; Spore germination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Certain flavonoids released from plants regulate activities of soil microbes at micromolar and nanomolar concentrations. Processes affected by these compounds include induction of nodulation gene transcription in rhizobial bacteria, promotion of chemotaxis in rhizobia, increase in growth rate of several bacterial species, and enhancement of Glomus spore germination and hyphal growth. Data on the amount and identity of flavonoids released from several crop plant species form a new basis for molecular genetic and ecological studies of the rhizosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206136
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  • 2
    Electronic Resource
    Electronic Resource
    Patch size of forest openings and arthropod populations (1991)
    Springer
    Oecologia 86 (1991), S. 325-334 
    Details
    ISSN: 1432-1939
    Keywords: Arthropods ; Disturbance ; Patch dynamics ; Southern Appalachian Mountains ; Succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Five sizes of canopy openings (0.016 ha to 10 ha) were established in the Southern Appalachian Mountains in early 1982 to examine the initial patterns of plant and arthropod establishment across a size range of forest disturbances. Vegetation standing crop after the first growing season was considerably higher in large than small openings in apparent response to greater resource release (e.g., sunlight) in larger openings. Woody stump and root sprouts were the dominant mode of revegetation in each patch size. Forest dominants such as Quercus rubra, Q. prinus and Carya spp. were less important as sprouters in openings than several minor forest components (e.g., Robinia pseudo-acacia, Acer rubrum, Halesia carolina and Cornus florida). Arthropod abundance and community composition varied across the size range of forest openings. Arthropods from the surrounding forest readily utilized the smallest canopy openings (0.016 ha). All feeding guilds were well represented in these small openings and herbivore biomass and load (mg of herbivores/g of foliage) were much higher than in larger patches. In contrast, arthropod abundance and species richness were significantly lower in mid-size than smaller patches. The relatively sparse cover and high sunlight in mid-size openings may have promoted surface heat buildups or soil surface/litter moisture deficits which restricted arthropod entry from the surrounding forest. Arthropod abundance and species richness were higher in large than mid-size patches. The greater vegetation cover in larger openings may have minimized the deleterious effects on arthropod populations. However, the absence of population increases among these arthropod species maintained herbivore loads at very low levels in large patches. Our results suggest that arthropod abundance and diversity in sprout-dominated forest openings are highly dependent on the extent of environmental differences between patch and surrounding forest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317597
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  • 3
    Electronic Resource
    Electronic Resource
    Organochlorine chemicals in human breast milk in Hong Kong (1989)
    Springer
    Archives of environmental contamination and toxicology 18 (1989), S. 490-494 
    Details
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract The results of a small-scale survey of organochlorine contaminants in human breast milk are presented and compared to previous data from 1976 for Hong Kong, and to reported data from elsewhere. Concentrations of p,p′ DDT, dieldrin and hexachlorobenzene (HCB) in recent breast milk samples were slightly but significantly lower than those in samples taken a decade previously in Hong Kong. However, levels of γ-HCH (hexachlorocyclohexane) were higher in the more recent samples. The concentrations of DDT, DDE and β-HCH in Hong Kong breast milk remain among the highest reported in the literature. Probable routes of uptake of such contaminants include the ingestion of seafood, as these same compounds have previously been found at high concentrations in mussels from Hong Kong waters. Data for organochlorine levels in breast milk from other parts of Asia are not available, but trends in global pesticide usage suggest that significant contamination elsewhere in the continent is likely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01055014
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  • 4
    Electronic Resource
    Electronic Resource
    Host-feeding and egg maturation byPachycrepoideus vindemiae (1993)
    Springer
    Entomologia experimentalis et applicata 69 (1993), S. 75-82 
    Details
    ISSN: 1570-7458
    Keywords: host feeding ; preference ; Pachycrepoideus vindemiae ; parasitoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) is a facultative hyperparasitoid ofDrosophila parasitoids in Europe. FemaleP. vindemiae host-feed from the same hosts into which they lay eggs and this enables them to mature additional eggs.P. vindemiae females were allowed to host-feed from puparia containingDrosophila melanogaster Meigen (Diptera: Drosophilidae) pupae or pupae ofAsobara tabida Nees (Hymenoptera: Braconidae). Wasps which had host-fed carried significantly more eggs; the species of host which was fed from had no significant effect on the number of mature eggs in the ovaries. Host-feeding caused no significant reduction in the size of the emerging offspring.P. vindemiae were allowed to forage over patches containing different frequencies of the two host species. No significant oviposition preference was found but there were marked host-feeding preferences which were affected by the age of the host pupae. It is suggested that these preferences were due to the physical nature of the hosts which were fed from.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380676
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  • 5
    Electronic Resource
    Electronic Resource
    Comparison of lasers for photodynamic therapy with a phthalocyanine photosensitizer (1989)
    Springer
    Lasers in medical science 4 (1989), S. 7-12 
    Details
    ISSN: 1435-604X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Three different lasers were compared under the same conditions for their effectiveness at producing photodynamic damage to normal colon following sensitization with aluminium sulphonated phthalocyanine (AlSPc). One laser was an argon ion pumped continuous wave (CW) dye laser and the other two were pulsed at 10 kHz (copper vapour laser pumped dye laser, and 5 Hz (flashlamp pumped dye laser). The CW and 10 kHz laser were equally effective at producing damage. The 5 Hz laser failed to produce a photodynamic effect, although occasionally caused a photomechanical effect when the laser fibre was placed touching the colonic mucosa. Quantitative analysis suggests that the high energy pulses of the flashlamp pumped dye laser saturate AlSPc, so very little of the available energy can be used to produce a photodynamic effect, in contrast to the two other lasers which do not produce saturation conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032503
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  • 6
    Electronic Resource
    Electronic Resource
    Serum pesticide concentrations in farming cooperatives in Honduras (1989)
    Springer
    Bulletin of environmental contamination and toxicology 42 (1989), S. 643-650 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01700382
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  • 7
    Electronic Resource
    Electronic Resource
    Evolution of the weld heat-affected zone microstructure in a Ti-48AI-2Cr-2Nb gamma titanium aluminide (1994)
    Springer
    Journal of materials science 13 (1994), S. 1061-1065 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277040
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  • 8
    Electronic Resource
    Electronic Resource
    Bibliometrics and UK science policy (1988)
    Springer
    Scientometrics 14 (1988), S. 185-200 
    Details
    ISSN: 1588-2861
    Source: Springer Online Journal Archives 1860-2000
    Topics: Information Science and Librarianship , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract We outline the tasks of the UK Advisory Board for the Research Councils in the context of the country's science policy, and describe a programme of science policy studies developed by the Board in response to a growing need to take a strategic view in science policy decisions. The outcomes of the studies which have used bibliometric techniques are briefly described, and the paper suggests how such techniques might be of use to policy-makers in future.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02020074
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  • 9
    Electronic Resource
    Electronic Resource
    Germacrone defends labrador tea from browsing by snowshoe hares (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 1961-1970 
    Details
    ISSN: 1573-1561
    Keywords: Labrador tea ; Ledum groenlandicum ; snowshoe hare ; Lepus americanus ; herbivore ; plant chemical defense ; germacrone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Labrador tea (Ledum groenlandicum), a slow-growing late successional evergreen, is highly unpalatable to snowshoe hares (Lepus americanus). Germacrone, a sesquiterpene that is the major component of the essential oil ofL. groenlandicum, was shown by bioassay to be a potent antifeedant to hares. Its concentrations in leaves and intemodes of the plant are high enough to defendL. groenlandicum from hares. This chemical defense of Labrador tea from herbivory is consistent with the resource availability theory of antiherbivore defense.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01020508
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis, release, and transmission of alfalfa signals to rhizobial symbionts (1994)
    Springer
    Plant and soil 161 (1994), S. 69-80 
    Details
    ISSN: 1573-5036
    Keywords: betaines ; flavonoids ; Medicago sativa ; nodulation ; Rhizobium meliloti
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In addition to the flavonoids exuded by many legumes as signals to their rhizobial symbionts, alfalfa (Medicago sativa L.) releases two betaines, trigonelline and stachydrine, that induce nodulation (nod) genes inRhizobium meliloti. Experiments with14C-phenylalanine in the presence and absence of phenylalanine ammonia-lyase inhibitors show that exudation of flavonoidnod-gene inducers from alfalfa roots is linked closely to their concurrent synthesis. In contrast, flavonoid and betainenod-gene inducers are already present on mature seeds before they are released during germination. Alfalfa seeds and roots release structurally differentnod-gene-inducing signals in the absence of rhizobia. WhenR. meliloti is added to roots, medicarpin, a classical isoflavonoid phytoalexin normally elicited by pathogens, and anod-gene-inducing compound, formononetin-7-O-(6″-O-malonylglycoside), are exuded. Carbon flow through the phenylpropanoid pathway and into the flavonoid pathway via chalcone synthase is controlled by complexcis-acting sequences andtrans-acting factors which are not completely understood. Even less information is available on molecular regulation of the two other biosynthetic pathways that produce trigonelline and stachydrine. Presumably the three separate pathways for producingnod-gene inducers in some way protect the plant against fluctuations in the production or transmission of the two classes of signals. Factors influencing transmission of alfalfanod-gene inducers through soil are poorly defined, but solubility differences between hydrophobic flavonoids and hydrophilic betaines suggest that the diffusional traits of these molecules are not similar. Knowledge derived from studies of how legumes regulate rhizobial symbionts with natural plant products offers a basis for defining new fundamental concepts of rhizosphere ecology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183086
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