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  • 1
    Electronic Resource
    Electronic Resource
    Behavioural development and abdomen inflation of gynes and newly mated queens of Melipona beecheii (Apidae, Meliponinae) (1999)
    Springer
    Insectes sociaux 46 (1999), S. 361-365 
    Details
    ISSN: 1420-9098
    Keywords: Key words: Pre-mating behaviour, gyne, abdomen enlargement, Melipona beecheii, stingless bee.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: The behaviour of gynes of Melipona beecheii in queen-deprived colonies was studied. The period after emergence until acceptance is characterized by agonistic behaviour of workers towards the gynes. The gynes escaped from this worker aggression by hiding in the periphery of the nest, by performing rapid turn-arounds once grabbed by a worker, and "feigning death". Between acceptance and nuptial flight, gynes spent most of their time in pushing, hiding, and antennal contact with workers, and self-grooming or food solicitation. After the nuptial flight the queen's behavioural repertoire shifted to less pushing and food solicitation, to an increase in standing, tapping and antennal contact.¶Accepted gynes had a significantly more prolonged abdomen inflation than gynes that were eliminated.¶An hypothesis is presented to explain how abdomen enlargement and behavioural development influences the acceptance of gynes and the establishment of a dominance relation with workers under queenless conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000400050157
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  • 2
    Electronic Resource
    Electronic Resource
    Behaviour of drones in Melipona (Apidae, Meliponinae) (1997)
    Springer
    Insectes sociaux 44 (1997), S. 435-447 
    Details
    ISSN: 1420-9098
    Keywords: Key words: Stingless bees, drone behaviour, Melipona, M. beecheii, M. favosa, M. fasciata.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary: The behaviour of drones of different species of Melipona was studied in Costa Rica and on Tobago. Drones of all species behaved very similarly. The intranidal behavioural analysis indicates that drones spent most time on standing, walking, stirring the antennae and self-grooming. The only "typical worker behaviour", occasionally performed by 16 to 18 days old drones of Melipona, was the participation in nectar dehydrating. The age-relatedness and location in the nest where a behaviour is performed is being discussed. Worker aggression against drones was observed only three times. The behaviour of drones when they leave the nest is described. Drones leave the nest mainly between 8 and 11 AM, at an average age of 18.6 days. It was observed that drones do not return after they have once left the hive. A description is given of a nest-associated drone aggregation of Melipona fasciata on a wall. Drones of this species stayed in the aggregation for an average of 7.6 days, spending most time on standing or flying in a "cloud" near the nest entrance. They spent about five hours daily on the average and may leave the aggregation temporary. Drones were able to live up to 74 days in a closed hive, the average being 45 days. Implications of drone behaviour for the mating biology of stingless bees are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000400050063
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  • 3
    Electronic Resource
    Electronic Resource
    The number of bacteria in the rhizosphere during plant development: relating colony-forming units to different reference units (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 285-291 
    Details
    ISSN: 1432-0789
    Keywords: Key words Chrysanthemum ; Rhizosphere ; Rhizobacteria ; Root age ; Reference unit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The number of bacteria was determined during the growth of chrysanthemum plants on young (tip) and old (base) root parts. We assessed if the same conclusions could be drawn on the dynamics of bacterial populations during plant development when different reference units were used to express the bacterial counts. The results indicated that the total number of bacteria on the base decreased significantly during plant development, when expressed per root length, per root fresh weight or per root surface. The number of bacteria on the tip only decreased significantly when expressed per root length. Using the unit of dry weight of adhering soil, contradictory results were obtained for both base and tip; in general, the number of bacteria increased significantly during plant development. Thus, different reference units may lead to different conclusions. Root surface seemed to be the best unit to use, but the use of this unit requires time-consuming measurements. Regression analyses indicated that the reference unit "root surface" was highly correlated with root fresh weight (R 2=93%). Thus, once this relation is determined, the less time-consuming unit can be measured in the experimental work. To analyse the data, the colony-forming units should be expressed per root surface. Besides bacterial numbers during plant development, we assessed whether the bacterial populations collected showed different growth rates on agar plates. The growth rates of bacteria from the tip and base and different development stages of the plants showed differences, indicating differences in the metabolic state of the collected populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050495
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  • 4
    Electronic Resource
    Electronic Resource
    Fast survey analysis of biomass by-product samples based on ICP optical emission spectra (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 666-672 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Prehydrolysate samples from the acidic prehydrolysis of Eucalyptus wood residues were submitted to survey analysis by inductively coupled plasma (ICP) optical emission spectrometry (OES) based on the multicomponent and multiline techniques. The survey analysis software is designed to determine 64 elements. The semiquantitative data obtained for the unknown prehydrolysate samples provided fast and valuable information for the determination of important inorganic constituents (Al, B, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Si, Sr, Zn, Co, Pb, Sn) for further utilisation of the prehydrolysate in the production of fertilisers, animal feed and furfural. To validate the survey analysis approach, the prehydrolysate samples were quantitatively analysed by the standard additions method. For the prehydrolysate samples the relative difference between the results obtained by both techniques was generally ± 25% for the majority of the elements, a typical value for the survey approach. Analyte recoveries in the spiked prehydrolysate samples analysed by the survey approach ranged from 95 to 125%. Independent replicates of prehydrolysate samples were measured over a 15-day period showing relative standard deviations of ≤ 4% for all elements, except for Zn (10%) and S (16%).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051410
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  • 5
    Electronic Resource
    Electronic Resource
    Instability of zeolite Y supported cobalt sulfide hydrotreating catalysts in the presence of H2S (1997)
    Springer
    Catalysis letters 47 (1997), S. 155-160 
    Details
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of the sulfidation temperature of dehydrated ion exchanged CoNaY on the catalytic activity and structure was studied by thiophene HDS activity measurements, overall sulfur analysis, temperature programmed sulfidation, Xe adsorption measurements in combination with129Xe NMR, EXAFS and ESR. It was shown that up to a sulfidation temperature of 573 K small highly active Co sulfide clusters were formed in the supercages. Sulfidation above 573 K led to decomposition of these Co sulfide particles by a protolysis reaction resulting in the formation of H2Sand a blue colored Co compound having almost no HDS activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019092602157
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  • 6
    Electronic Resource
    Electronic Resource
    One medicine: The dynamic relationship between animal and human medicine in history and at present (1998)
    Springer
    Agriculture and human values 15 (1998), S. 115-120 
    Details
    ISSN: 1572-8366
    Keywords: Medicine ; Veterinary medicine ; Public health ; Epidemiology ; Comparative medicine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relation and collaboration of human and animal medicine had its ups and downs throughout history. The interaction between these two disciplines has been especially fruitful in the broad areas of patho-physiology and of epidemiology. An exploration of the interaction between the two disciplines, using historical and contemporary examples in comparative medicine, zoonoses, zooprophylaxis, and human-animal bond, reveals that a better understanding of animal and human disease, as well as societal changes such as interest in non-conventional medicine, are leading to a broader concept of one medicine that includes animal and human medicine as well as social and other sciences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007478809782
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  • 7
    Electronic Resource
    Electronic Resource
    Phosphate transport in prokaryotes: molecules, mediators and mechanisms (1997)
    Springer
    Antonie van Leeuwenhoek 72 (1997), S. 299-315 
    Details
    ISSN: 1572-9699
    Keywords: divalent cation ; end-product efflux ; phosphate chelate ; polyphosphate ; proton motive force ; transport protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacteria have evolved sophisticated P〉i transport systems which combine high affinity with coupling to metabolic energy. This review discusses the current evidence concerning the physiological, biochemical, and molecular properties of these P〉i transport systems in prokaryotes. Major developments of the past years will be presented with emphasis on three kinds of issues. First, work on P〉i transport in Escherichia coli and the polyphosphate-accumulating Acinetobacter johnsonii has assigned a novel biochemical mechanism and provided additional descriptive information for the transport of P〉i and divalent cations. It is therefore appropriate to summarize these new facts and emphasize their general relevance for pro- and eukaryotic cells. Second, recent work on the bioenergetics of P〉i transport in A. johnsonii has demonstrated the profound role of the transmembrane P〉i gradient in energy transducing processes such as the accumulation of solutes, and the generation of a proton motive force. These findings and their significance for the survival of the cell during metabolic stress conditions will be discussed. Finally, polyphosphate-accumulating microorganisms play a valuable role in biotechnological applications, such as in wastewater treatment. As such organisms are still underrepresented in current molecular microbiological studies, the investigations in A. johnsonii described here may serve as a useful precedent for those to come.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000530927928
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  • 8
    Electronic Resource
    Electronic Resource
    The role of transport processes in survival of lactic acid bacteria, Energy transduction and multidrug resistance (1997)
    Springer
    Antonie van Leeuwenhoek 71 (1997), S. 117-128 
    Details
    ISSN: 1572-9699
    Keywords: ABC-transporter ; decarboxylation ; energetics ; lactic acid bacteria ; multidrug resistance ; secondary transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural an d functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1000143525601
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  • 9
    Electronic Resource
    Electronic Resource
    Multidrug resistance in lactic acid bacteria: molecular mechanisms and clinical relevance (1999)
    Springer
    Antonie van Leeuwenhoek 76 (1999), S. 347-352 
    Details
    ISSN: 1572-9699
    Keywords: ABC transporter ; drug binding sites ; drug efflux ; membrane protein ; secondary transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The active extrusion of cytotoxic compounds from the cell by multidrug transporters is one of the major causes of failure of chemotherapeutic treatment of tumor cells and of infections by pathogenic microorganisms. The secondary multidrug transporter LmrP and the ATP-binding cassette (ABC) type multidrug transporter LmrA in Lactococcus lactis are representatives of the two major classes of multidrug transporters found in pro- and eukaryotic organisms. Therefore, knowledge of the molecular properties of LmrP and LmrA will have a wide significance for multidrug transporters in all living cells, and may enable the development of specific inhibitors and of new drugs which circumvent the action of multidrug transporters. Interestingly, LmrP and LmrA are transport proteins with very different protein structures, which use different mechanisms of energy coupling to transport drugs out of the cell. Surprisingly, both proteins have overlapping specificities for drugs, are inhibited by t he same set of modulators, and transport drugs via a similar transport mechanism. The structure-function relationships that dictate drug recognition and transport by LmrP and LmrA will represent an intriguing new area of research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1002033923510
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  • 10
    Electronic Resource
    Electronic Resource
    Carbon and nitrogen allocation in Lolium perenne in response to elevated atmospheric CO2 with emphasis on soil carbon dynamics (1997)
    Springer
    Plant and soil 188 (1997), S. 299-308 
    Details
    ISSN: 1573-5036
    Keywords: elevated CO2 ; carbon partitioning ; nitrogen partitioning ; Lolium perenne ; microbial biomass ; mineralisation ; soil carbon dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of elevated CO2 on the carbon and nitrogen distribution within perennial ryegrass (L. perenne L.) and its influence on belowground processes were investigated. Plants were homogeneously 14C-labelled in two ESPAS growth chambers in a continuous 14C-CO2 atmosphere of 350 and 700 μL L-1 CO2 and at two soil nitrogen regimes, in order to follow the carbon flow through all plant and soil compartments. After 79 days, elevated CO2 increased the total carbon uptake by 41 and 21% at low (LN) and high nitrogen (HN) fertilisation, respectively. Shoot growth remained unaffected, whereas CO2 enrichment stimulated root growth by 46% and the root/soil respiration by 111%, irrespective of the nitrogen concentration. The total 14C-soil content increased by 101 and 28% at LN and HN, respectively. The decomposition of the native soil organic matter was not affected either by CO2 or by the nitrogen treatment. Elevated CO2 did not change the total nitrogen uptake of the plant either at LN or at HN. Both at LN and HN elevated CO2 significantly increased the total amount of nitrogen taken up by the roots and decreased the absolute and relative amounts translocated to the shoots. The amount of soil nitrogen immobilised by micro-organisms and the size of the soil microbial biomass were not affected by elevated CO2, whereas both were significantly increased at the higher soil N content. Most striking was the 88% increase in net carbon input into the soil expressed as: 14C-roots plus total 14C-soil content minus the 12C-carbon released by decomposition of native soil organic matter. The net carbon input into the soil at ambient CO2 corresponded with 841 and 1662 kg ha-1 at LN and HN, respectively. Elevated CO2 increased these amounts with an extra carbon input of 950 and 1056 kg ha-1. Combined with a reduced decomposition rate of plant material grown at elevated CO2 this will probably lead to carbon storage in grassland soils resulting in a negative feed back on the increasing CO2 concentration of the atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004233920896
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