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  • 2000-2004  (6)
  • 1930-1934
  • 2002  (1)
  • 2000  (5)
  • 1
    Digitale Medien
    Digitale Medien
    Interactions between atmospheric CO2 concentration and phosphorus nutrition on the formation of proteoid roots in white lupin (Lupinus albus L.) (2002)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Atmospheric [CO2] affects photosynthesis and therefore should affect the supply of carbon to roots. To evaluate interactions between carbon supply and nutrient acquisition, the [CO2] effects on root growth, proteoid root formation and phosphorus (P) uptake capacity were studied in white lupin (Lupinus albus L.) grown hydroponically at 200, 410 and 750 µmol mol−1 CO2, under sufficient (0·25 mm P) and deficient (0·69 µm P) phosphorus. Plant size increased with increasing [CO2] only at high P. Both P deficiency and increasing [CO2] increased the production of proteoid clusters; the increase in response to increased [CO2] was proportionally greater from low to ambient [CO2] than from ambient to high. The activity of phosphoenol pyruvate carboxylase in the proteoid root, the exudation of organic acids from the roots, and the specific uptake of P increased with P deficiency, but were unaffected by [CO2]. Increasing [CO2] from Pleistocene levels to those predicted for the next century increased plant size and allocation to proteoid roots, but did not change the specific P uptake capacity per unit root mass. Hence, rising [CO2] should promote nutrient uptake by allowing lupins to mine greater volumes of soil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00883.x
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  • 2
    Digitale Medien
    Digitale Medien
    Gonococcal lipooligosaccharide is a ligand for the asialoglycoprotein receptor on human sperm (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 36 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: In the present study, we show that Neisseria gonorrhoeae lipooligosaccharide (LOS) can bind to the asialoglycoprotein receptor (ASGP-R) on human sperm. This work demonstrates the presence of ASGP-R on human sperm. Binding of purified ASGP-R ligand decreased in the presence of gonococci. Binding of purified iodinated gonococcal LOS identified a protein of molecular weight corresponding to that of human ASGP-R. The presence of excess unlabelled LOS blocked binding of iodinated gonococcal LOS. Binding of wild-type gonococcal LOS to sperm was higher than that of mutant LOS lacking the galactose ligand for ASGP-R. These data suggest that the ASGP-R on human sperm cells recognizes and binds wild-type gonococcal LOS. This interaction may contribute to the transmission of gonorrhea from infected males to their sexual partners.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.01938.x
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  • 3
    Digitale Medien
    Digitale Medien
    Minimal Presentations and Efficiency of Semigroups (2000)
    Springer
    Semigroup forum 60 (2000), S. 231-242 
    Details
    ISSN: 1432-2137
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: S is said to be efficient if it can be defined by a presentation (A | R) with |R| -|A|=rank(H 2(S)). In this paper we demonstrate certain infinite classes of both efficient and inefficient semigroups. Thus, finite abelian groups, dihedral groups D 2 n with n even, and finite rectangular bands are efficient semigroups. By way of contrast we show that finite zero semigroups and free semilattices are never efficient. These results are compared with some well-known results on the efficiency of groups.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002339910016
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  • 4
    Digitale Medien
    Digitale Medien
    Particle-mediated gene transfer to rat neurons in primary culture (2000)
    Springer
    Pflügers Archiv 439 (2000), S. 730-738 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Dorsal root ganglion neurons Gene gun Green fluorescent protein Hippocampal neurons Particle-mediated gene transfer Primary tissue culture Transfection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. Gene transfer into neuronal cells provides an important approach to study their function. Particle-mediated gene delivery was used to transfect rat dorsal root ganglion (DRG) and hippocampal neurons in primary culture with the genes for the enhanced blue and green fluorescent proteins (EBFP and EGFP) under control of the cytomegalovirus promoter. Quantitative analysis of marker protein fluorescence detected expression at 3 h that continued to increase for 48 h. For DRG neurons the optimal expression efficiency of 8±2% was obtained 24 h following transfection. In contrast, approximately 2±1% of hippocampal neurons in culture expressed EGFP at 3 h which subsequently declined. Co-transfection of DRG cultures with two plasmids produced reliable expression of both genes. Transfected DRG neurons exhibited normal electrophysiological properties, and resting and stimulated intracellular Ca2+ concentrations were unchanged. After transfection, 44% of hippocampal neurons remained in functional synaptic networks as indicated by glutamatergic Ca2+ spiking activity. Particle-mediated gene delivery provided a straightforward, reproducible and efficient method for transfection of neurons in primary culture. Transfected cells were easily identified by EGFP fluorescence, enabling subsequent physiological analysis. Biolistic particle bombardment was well tolerated by peripheral neurons, although caution was required when this method was applied to CNS cultures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004249900240
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  • 5
    Digitale Medien
    Digitale Medien
    A first estimate of organic carbon storage in Holocene lake sediments in Alberta, Canada (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 395-400 
    Details
    ISSN: 1573-0417
    Schlagwort(e): carbon storage ; lake sediment ; Holocene ; Canada ; climate change ; organic matter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie
    Notizen: Abstract This paper reports a first estimate of the Holocene lake sediment carbon pool in Alberta, Canada. The organic matter content of lake sediment does not appear to depend strongly on lake size or other limnological parameters, allowing a simple first estimate in which we assume all Alberta lake sediment to have the same organic matter content. Alberta lake sediments sequester about 15 g C m-2 yr-1, for a provincial total of 0.23 Tg C yr-1, or 2.3 Pg C over the Holocene. Alberta lakes may represent as much as 1/1700 of total global, annual permanent carbon sequestration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008103605817
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  • 6
    Digitale Medien
    Digitale Medien
    Microbial Biomass and Community Structure in a Sequence of Soils with Increasing Fertility and Changing Land Use (2000)
    Springer
    Microbial ecology 40 (2000), S. 223-237 
    Details
    ISSN: 1432-184X
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The microbial biomass and community structure of eight Chinese red soils with different fertility and land use history was investigated. Two community based microbiological measurements, namely, community level physiological profiling (CLPP) using Biolog sole C source utilization tests and phospholipid fatty acid (PLFA) profiles, were used to investigate the microbial ecology of these soils and to determine how land use alters microbial community structure. Microbial biomass-C and total PLFAs were closely correlated to organic carbon and total nitrogen, indicating that these soil microbial measures are potentially good indices of soil fertility in these highly weathered soils. Metabolic quotients and C source utilization were not correlated with organic carbon or microbial biomass. Multivariate analysis of sole carbon source utilization patterns and PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. PLFAs showed these differences more than CLPP methods. Consequently, PLFA analysis was a better method for assessing broad-spectrum community differences and at the same time attempting to correlate changes with soil fertility. Soils from tea orchards were particularly distinctive in their CLPP. A modified CLPP method, using absorbance readings at 405 nm and different culture media at pH values of 4.7 and 7.0, showed that the discrimination obtained can be influenced by the culture conditions. This method was used to show that the distinctive microbial community structure in tea orchard soils was not, however, due to differences in pH alone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002480000053
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