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  • 11
    Electronic Resource
    Electronic Resource
    Annual changes in the nutritive state of North Sea dab (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 49 (1996), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The nutritive state of dab Limanda limanda was investigated over a 2-year period at a fixed sampling site northwest of Helgoland (German Bight, North Sea), with respect to feeding habits and the accumulation of biochemical storage products. Ophiuroids formed the main weight of food organisms (50%) while polychaetes (10%), molluscs and crustaceans (〈5% each) were less frequent. Feeding activity in males varied between summer and winter, while females fed more constantly. The condition factor and the hepatosomatic index showed characteristic seasonal cycles in both sexes. The glycogen content in the liver reached 40–60 mg g−1 FW in summer and fell to about 10–20 mg g−1 FW in late winter. Total lipids of the liver showed a distinct seasonal cycle with 400 mg g−1 FW in summer and a minimum of 50–100 mg g−1 FW in spring. The lipid content of the muscle ranged from 5 to 6 mg g−1 FW and did not vary significantly between seasons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1996.tb00015.x
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  • 12
    Electronic Resource
    Electronic Resource
    Activity of methanotrophic bacteria in Green Bay sediments (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 16 (1995), S. 0 
    Details
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Sediment pore water samples obtained from a 19 m station in Green Bay in Lake Michigan were examined for levels of ambient dissolved methane and copper, and for the potential for in situ methane oxidation by methanotrophs found within surface sediments. The in situ methane concentration in the upper oxic sediment layer ranged from 20–150 μmol · 1−1 at this station. The activity of methanotrophs and the kinetics of methane oxidation in these sediments were demonstrated by the uptake of radiolabeled methane. Ks values varied between 4.1–9.6 nmol · cm3 of sediment slurry. High Vmax values (12.7–35.2 nmol · cm−3 · h−1) suggest a large population of methanotrophs in the sediments. An average methane flux to the oxic sediments of 0.24 mol · m−2 · year−1 was calculated from the pore water methane gradients. Pore water concentrations of copper in the upper sediment layer ranged from 10–120 nmol · 1−1. Based upon the copper concentration, other measured parameters, and equilibrium conditions defined by WATEQF4, an estimate for dissolved free Cu2+ concentration of 5–38 nmol · 1−1 pore water was obtained. Several factors control the rate of methane oxidation, including oxygen, methane, and the bioavailability of free Cu2+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6941.1995.tb00262.x
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  • 13
    Electronic Resource
    Electronic Resource
    New processes and actual trends in biotechnology (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 16 (1995), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: A survey of immobilization techniques with special emphasis on alginate entrapment and micro hollow spheres is presented. The advantages and disadvantages of immobilization are discussed. Industrial applications of immobilization are demonstrated, especially biosensors and production of acrylamide. The fundamentals of bioprocesses with reduced water content and application as well as process examples are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1995.tb00173.x
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  • 14
    Electronic Resource
    Electronic Resource
    Sigma factor and sporulation genes in Clostridium (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 17 (1995), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The genus Clostridium, represented by Gram-positive, anaerobic, spore-forming bacteria, is well known for its clinical importance and considerable biotechnological potential. Recently, evidence for a functional role of the transcription factors σA, σE, σG, and σK in this genus was provided by cloning and sequencing these genes from C. acetobutylicum. In C. kluyveri, a partially sequenced open reading frame was found to encode the N terminus of the putative σ factor L with significant similarity to members of the σ54 family. The identification of sequences with high similarity to the BacillusσF (C. acetobutylicum), σH (several clostridial species), and σD (C. thermocellum)-controlled consensus promoters renders the existence of these transcription factors in clostridia very likely. These data are in agreement with information obtained by RNA transcript mapping (σA, σH), heterologous DNA hybridization (σD, σH), and immuno characterization of purified proteins (σA) from various clostridial species. Thus, the picture emerges that a fundamental similarity exists at the genetic level between the regulation of various cellular responses, in particular sporulation, in the genera Bacillus and Clostridium. The different induction patterns of sporulation in Bacillus spp. (nutrient starvation) and many clostridial species (cessation of growth or exposure to oxygen in the presence of excess nutrients) are most interestingly not reflected in the general regulatory features of this developmental process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1995.tb00216.x
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  • 15
    Electronic Resource
    Electronic Resource
    Computational simulation and experimental findings of three-dimensional fatigue crack growth in a single-edge notched specimen under torsion loading (2005)
    PO Box 1354, 9600 Garsington Road, Oxford OX4 2XG, UK. : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 28 (2005), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, the rather complex three-dimensional (3D) fatigue crack growth behaviour in a single-edge notched (SEN) specimen with an inclined plane of the initial crack under torsion loading is investigated with the aid of ADAPCRACK3D programme and by application of a recently developed 3D fracture criterion. It will be shown that the computationally simulated results for fatigue crack growth in the FE model of the specimen are in good agreement with experimental findings for the development of spatially twisted and warped crack faces in the real laboratory test specimen. Consequently, also for this case with a rather complex 3D crack growth behaviour, the functionality of the ADAPCRACK3D programme and the validity of the proposed 3D fracture criterion can be stated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.2005.00864.x
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  • 16
    Electronic Resource
    Electronic Resource
    HLA-DP antibodies in patients awaiting renal transplantation (1995)
    Springer
    Transplant international 8 (1995), S. 180-184 
    Details
    ISSN: 1432-2277
    Keywords: HLA-DP antibodies ; kidney transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sera from 505 patients awaiting renal transplantation with known panel-reactive cytotoxic antibody (PRA) status were tested for HLA-DP antibodies of the IgG class by means of the monoclonal antibody immobilization of leukocyte antigens (MAILA) technique. The overall incidence of HLA-DP antibodies was 7.3%. A positive HLA-DP antibody status correlated only weakly (r=0.23) with a positive cytotoxic antibody status. After retrospective analysis, patients with HLA-DP antibodies prior to retransplantation revealed a significantly (P〈0.025) higher graft function rate than HLA-DP-negative patients. One patient was found to possess IgG HLA-DP autoantibodies prior to transplantation; thus far, his graft has been functioning for more than 2 years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336534
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  • 17
    Electronic Resource
    Electronic Resource
    Granite-hosted gold mineralization in the Midlands greenstone belt: a new type of low-grade gold deposit in Zimbabwe (1998)
    Springer
    Mineralium deposita 33 (1998), S. 437-460 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract In 1992, the Ford gold deposit was rediscovered during field work in the Kwekwe district near the Indarama mine, approximately 200 km southwest of Harare, Zimbabwe. Based on diamond drilling and open pit operations, estimated ore reserves are at least 3 Mt with an average gold content of 2.5 g/t. The gold deposit is located within a porphyritic granite dike with a thickness of 20–50 m, striking 800 m NNW-SSE. It dips 60–70° to the NE and intrudes a volcano-sedimentary sequence of tholeiitic basalts, acid volcanics, and banded iron formations of the Bulawayan Group (2900–2700 Ma). The intrusion of the dike occurred at 2541 ± 17 Ma (Pb/Pb step leaching technique) within a second order structure and is related to displacement along transcrustal deformation zones such as the Sherwood- and Taba-Mali deformation zones. Gold mineralization is confined to the s-shaped part of the dike intrusion. At the present stage of mining, the deposit is characterized by the absence of major veins, the occurrence of disseminated pyrite throughout the orebody, and a distinct alteration pattern comparable to that of porphyry copper deposits. The central zone of the dike shows a typical K-feldspar-albite-sericite-pyrite (±biotite?) alteration, followed by a narrow external propylitic zone. Native gold with an average Ag content of 5 wt.% and a grain size of 5–100 μm is rare and occurs within pyrite and secondary K-feldspar. Sulphide mineral separates of pyrite and minor arsenopyrite probably contain invisible gold (up to 120 ppm) amenable to cyanidation. Anomalously high gold values of ∼7 ppm have been found in the transition between the K-feldspar-albite-sericite-pyrite alteration and the propylitic zone, indicating that the mineralizing fluids have experienced major physico-chemical changes in the transition zone. The regional tectonic position of the orebody suggests that the emplacement of the granite and the gold mineralization are structurally controlled. The Pb isotope composition of several leachates of pyrite indicate isotope disequilibrium with magmatic minerals and point to a contamination of the mineralizing fluid by Pb from older (sedimentary?) sources. Stable isotope geochemistry of sulphides and carbonates as well as the metallogeny of the deposit compare to shear-zone hosted gold mineralization in the Kwekwe district, for which a deep crustal origin has been discussed. Although this study documents contrasting evidence for a porphyry-gold versus a shear-zone type of mineralization, it is suggested that gold-bearing fluids were syntectonically introduced into a ductile shear zone within the granite dike either during cooling of the intrusion or later in Archaean or early Proterozoic times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050162
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  • 18
    Electronic Resource
    Electronic Resource
    A laboratory study on digestive processes in the Antarctic krill, Euphausia superba, with special regard to chitinolytic enzymes (1999)
    Springer
    Polar biology 21 (1999), S. 295-304 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding experiments of 9, 14 and 20 days duration were carried out on the Antarctic krill, Euphausia superba. Two groups were fed with the chitinous diatom Cyclotella cryptica and the non-chitinous green algae Dunaliella bioculata, respectively. A control group remained unfed. The time courses of the activities of endo- and exochitinase in the stomach and the midgut gland were compared with those of the digestive enzymes protease, cellulase (1,4-β-d-glucanase) and laminarinase (1,3-β-d-glucanase). Specific activities of all enzymes were higher in the stomach than in the midgut gland. Characteristic time courses of activity were evident after 4 days. In starved animals, enzyme activities decreased to a minimum after 4 days and recovered within 14 days to initial values. In the stomach, the activities of endo- and exochitinase increased when krill were fed on Cyclotella. For animals fed with Dunaliella, activities stayed constant or decreased slightly. The results confirm chitinases as digestive enzymes and, therefore, the capability of krill to utilize various food sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050365
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  • 19
    Electronic Resource
    Electronic Resource
    Differences among plant species in cuticular permeabilities and solute mobilities are not caused by differential size selectivities (1998)
    Springer
    Planta 206 (1998), S. 322-328 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Cuticular membrane ; Foliar uptake ; Growth substance  ; Membrane permeability ; Size selectivity (cuticle) ; Solute mobility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Solute mobilities in cuticular membranes of six species (Hedera helix, Malus domestica, Populus alba, Pyrus communis, Stephanotis floribunda, Strophantus gratus) were measured using plant hormones, growth regulators and other organic model compounds varying in molar volumes from 99 to 349 mL · mol−1 The dependence of mobilities (k*) on molar volume (V x ) was exponential and could be described with equations of the type log k*=log k*0−′ V x . The y-intercepts (log k*0) represent mobilities of a hypothetical solute of zero molar volume. The parameter β′ is a measure of size selectivity of cuticular membranes and no differences among the six species were observed. At 25 °C the average β′ was 0.0095 mol · mL−1. Solute mobility decreased by about a factor of 8.9 when molar volume increased by 100 mL · mol−1 and the mobility of a compound with V x  = 100 mL · mol−1 was about 700-fold higher than the mobility of a compound with V x  = 400 mL · mol−1. Size selectivity decreased with increasing temperatures and for Strophantusβ′-values of 1.6 × 10−2 to 8.0 × 10-4 mol · mL−1 were obtained for 10 and 30 °C, respectively. The-intercepts (log k*0) differed among plant species by 3 orders of magnitude and since size selectivity was the same for all species, solute mobilities for solutes having zero molar volumes were the sole cause for differences among species in solute mobilities and permeabilities. We argue that these differences in k*0 are related to tortuosity of the diffusion path. These results were used to derive an equation which predicts rates of cuticular penetration on the basis of k*0, the average size selectivity of 9.5 × 10−3 mol · mL−1 and the driving forces of penetration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050407
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  • 20
    Electronic Resource
    Electronic Resource
    Ovarian development and spawning in relation to the moult cycle in Northern krill, Meganyctiphanes norvegica (Crustacea: Euphausiacea), along a climatic gradient (1999)
    Springer
    Marine biology 133 (1999), S. 267-281 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Adaptive processes linked to reproduction were studied comparatively for three populations of Northern krill, Meganyctiphanes norvegica (M. Sars, 1857), sampled during winter and summer cruises in the Clyde Sea (W Scotland), the Kattegat (E Denmark), and the Ligurian Sea (NW Mediterranean). The aim was to investigate the functional relationship between egg production and moulting under contrasted climatic and environmental conditions. A staging system for female sexual development established for live krill was complemented by a histological study of the ovary at various developmental steps. During the reproductive season, all adult female krill were engaged in cyclical egg production. During experiments, female krill released one batch of mature oocytes in one or two spawning events. The ovary of postspawn female krill still contained developing oocytes for another egg batch. In the non-reproductive period, all female krill had a resting ovary. Ovarian structure and pattern of egg production were identical in the three populations, but seasonal timing of egg production was different. The model proposed for the Ligurian population of the annual cycle of ovarian development can be extended to the other two populations, taking into account the seasonal characteristics of each site. Random field samples were staged simultaneously for moult cycle and for sexual development. Moult stages and the seasonal variation of the intermoult period were studied for the Kattegat population using multi-year data and compared to data obtained during summer/winter cruises in the Clyde and the Ligurian Sea. At the three sites, intermoult period was shorter and temperature-dependent during the reproductive period, concurrent with the season of greatest food availability. During most of the year and the period of sexual rest, moulting activity was reduced. The relationship between spawning and the moult cycle was studied comparatively for the three populations. Eggs were released during the premoult phase of a “spawning moult cycle”, in one or two spawnings associated with apolysis and Moult Stage D1, respectively. Yolk accumulation for the next egg batch was completed during an alternating “vitellogenic moult cycle”. A model for the timing of cyclical egg production in relation to moulting, as proposed for the Kattegat, can be extended to the other populations, taking into account intermoult period variation with temperature. Temperature appeared to be the principal environmental factor controlling growth (through moulting) and egg production during the reproductive season, in connection with favourable trophic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050466
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