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  • 1
    Digitale Medien
    Digitale Medien
    Above-room-temperature optically pumped 4.12 μm midinfrared vertical-cavity surface-emitting lasers (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 1129-1131 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Optically pumped lead salt vertical-cavity surface-emitting lasers (VCSELs) with a nine period PbSe/PbSrSe quantum well active region operating above room temperature in pulsed mode are reported. The gain peak and cavity mode of the VCSEL structure are in resonance at 300 K. A power output of 40 mW is obtained at room temperature and it does not show saturation. The room-temperature threshold pump density is 200 kW/cm2. The lasing wavelength of λ=4.12 μm remains nearly constant over a temperature range of 280–310 K. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1449540
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  • 2
    Digitale Medien
    Digitale Medien
    Comparison of sulphur uptake by oilseed rape and the soil sulphur status of two adjacent fields with different soil series (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 10 (1994), S. 0 
    Details
    ISSN: 1475-2743
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract. At Woburn Experimental Farm (SE central England) sulphur (S) deficiency symptoms occurred in a winter oilseed rape crop grown in Lansome field on soil of the Cottenham series, but not on the Blithe series soil in the adjacent Mill Dam Close field. At maturity, the two crops produced a similar amount of dry matter but seed yield and harvest index were significantly less in Lansome. Total S uptake of the crop in Lansome was less than half of that in Mill Dam Close, which was similar to the amount normally found in a S sufficient crop. Both soils are of light texture (loamy sand and sandy clay loam for the Cottenham and Blithe series, respectively), and there was little difference in the extractable S concentration in the topsoils between the two fields. However, more extractable S was found in the subsoil of Blithe series, because it contains more free Fe and Al oxides and has a lower pH. These results show that any evaluation of the soil S supply needs to take into account the pool of available S in the subsoil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1475-2743.1994.tb00457.x
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  • 3
    Digitale Medien
    Digitale Medien
    Inheritance and mapping of a restorer gene for the rapeseed cytoplasmic male sterile line 681A (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 124 (2005), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: A novel cytoplasmic male sterility-fertility restoration system has been developed in rapeseed (Brassica napus). The cytoplasmic male sterile line 681A was derived from a spontaneous male sterile mutant in a newly released double-low rapeseed cultivar ‘Xiangyou 13′. The restorer line 714R was identified in the interspecific progeny from a B. napus×B. juncea-cross. Genetic analysis showed that fertility restoration for 681A cytoplasmic male sterility was controlled by a single dominant nuclear gene which might originate from B. juncea. The RAPD marker S1039-520 was found to be linked to the restorer gene in F2 progeny of 681A × 714R with a recombination frequency of 5.45%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1439-0523.2004.01048.x
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  • 4
    Digitale Medien
    Digitale Medien
    Zinc hyperaccumulation and cellular distribution in Arabidopsis halleri (2000)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Although Arabidopsis halleri (=Cardaminopsis halleri) is known as a Zn hyperaccumulator, there have been no detailed studies on Zn accumulation, tolerance and cellular distribution in this species. In a hydroponic experiment, A. halleri grew healthily with Zn concentrations varying from 1 to 1000 μM, without showing phytotoxicity or reduction in root or shoot dry weights. The concentration of Zn in the shoots increased from 300 μg g−1 dry weight in the 1 μM Zn treatment to 32 000 μg g−1 in the 1000 μM Zn treatment. Approximately 60% of the total Zn in the shoots were water-soluble, and there was no evidence of Zn and P co-precipitation. Both citric and malic acid concentrations in the shoots were not significantly affected by the Zn treatments, whereas in the roots there was a positive response in both organic acids to increasing Zn in solution. Cellular distribution of Zn, Ca and K in frozen hydrated leaf tissues was examined using energy-dispersive X-ray microanalysis. Zinc was sequestered in the base of trichomes, whereas the middle and upper parts of trichomes were highly enriched with Ca. Mesophyll cells appeared to have more Zn than the epidermis, probably because the latter were very small in size. Similarities and differences between A. halleri and the other well-known Zn hyperaccumulator, Thlaspi caerulescens, are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00569.x
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  • 5
    Digitale Medien
    Digitale Medien
    Solubility of zinc and interactions between zinc and phosphorus in the hyperaccumulator Thlaspi caerulescens (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: The relationship between Zn and P in the Zn hyperaccumulator Thlaspi caerulescens J. & C. Presl was investigated using hydroponic culture. Total concentrations of Zn in the shoots increased from 0·2 to 27 g kg–1 dry mass when solution Zn increased from 1 to 1000 mmol m–3. Water-soluble Zn accounted for 〉 80% of the total Zn in the shoots containing 〉 5 g Zn kg–1 dry mass. Total P was maintained at about 3 g kg–1 dry mass in the shoots containing 〈 20 g Zn kg–1 dry mass, but significantly decreased with higher Zn concentrations. Linear regression between insoluble P and insoluble Zn in the shoots produced a small slope, suggesting that co-precipitation of Zn and P was not an important detoxification mechanism in the shoots. In contrast, there was a strong correlation between insoluble P and insoluble Zn in the roots, with a linear slope of 0·3 — close to the P:Zn ratio in Zn3(PO4)2. Foliar sprays of phosphate did not affect shoot dry mass significantly, but decreased root length and root dry mass significantly at Zn concentrations in solution from 10 to 3000 mmol m–3. Foliar P was translocated to roots to enhance co-precipitation of Zn and P, although this did not enhance Zn tolerance. The results suggest that T.caerulescens possesses mechanisms which allow it to accumulate and sequester huge amounts of Zn in the shoots without causing P deficiency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00270.x
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  • 6
    Digitale Medien
    Digitale Medien
    Long-Term Expression of a Transferred Gene in Epstein–Barr Virus Transformed Human B Cells (2001)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 54 (2001), S. 0 
    Details
    ISSN: 1365-3083
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Delivering a gene into the Epstein–Barr virus (EBV)-transformed B cells is useful in studying effects of the gene on B-cell functions. However, although people have been able to efficiently transfer genes into and get them expressed in B-lympho blastoidcells for a time probably long enough to kill the cells using vectors harbouring oriP, the expression time of the delivered gene is not long enough in order to study the gene function in B cells. To solve this problem, we constructed an adeno-associated virus (AAV) plasmid pAGX(+) based on plasmids pSub201 and pRc/CMV. We developed and packaged recombinant AAV (rAAV) expression vectors containing an antisense or a sense DNA fragment of 6A8 cDNA encoding a human α-mannosidase, or an antisense fragment of 5D4 cDNA encoding a human cell membrane protein, or EYFP DNA. EBV-transformed B cell SKW6 and 3D5 were transduced with those rAAV or the mock. Transduction with the rAAV-EYFP showed an infection frequency of 64 ± 3.5% and 58 ± 6.2% for SKW6 and 3D5 cell, respectively. Genomic polymerase chain reaction (PCR) for neoR gene indicated an integration of the transferred gene into the host DNA. After being cultured and propagated for over 12 months, the cells were detected for the expression of the transferred gene. The RT–PCR, enzymatic assay and Con A binding test demonstrated an inhibition of 6A8 α-mannosidase in both SKW6 and 3D5 cells transduced with the antisense 6A8 DNA. Immunofluorescence staining with monoclonal antibodies (MoAb) 5D4 showed a reduction of the 5D4 protein expression on both the cells transduced with the antisense 5D4 DNA. The DNA fragmentation assay showed a resistance of the cells with 6A8 α-mannosidase inhibition to apoptosis induction by anti-Fas antibody. The data indicate that the AAV vector pAGX(+) can efficiently introduce genes into EBV-transformed B cells and the delivered gene can be expressed in the cells for more than 12 months which may be long enough for the study of gene functions in B cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3083.2001.00924.x
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  • 7
    Digitale Medien
    Digitale Medien
    Sulphur accumulation and redistribution in wheat (Triticum aestivum): a study using stable sulphur isotope ratios as a tracer system (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Wheat plants were grown hydroponically and fed with two sulphate sources differing in stable isotope composition, one having a δ34S of 13·7‰ and the other 4·1‰. Plant sulphur (S) isotope ratios were determined using an on-line continuous flow-isotope ratio mass spectrometer. This method greatly simplified the procedure for the measurement of S isotope ratios, and was found to be precise for samples containing 〉 1 mg S g–1 dry weight. The δ34S values of plant shoots, which had been grown on a single sulphate source, were very close to the source values, suggesting little isotope fractionation during sulphate uptake and transport from roots to shoots. By changing the sulphate sources at different growth stages, it was possible to estimate S accumulation and redistribution within different plant parts. At maturity, wheat grain derived 14, 30, 6 and 50% of its S from the accumulation during the following successive growth stages: between emergence and early stem extension, between stem extension and flag leaf emergence, between flag leaf emergence and anthesis, and after anthesis, respectively. It was estimated that 39, 32 and 52% of the S present in the flag leaves, older leaves and stems, respectively, at anthesis, was exported during the postanthesis period. These results demonstrate considerable cycling of S within wheat plants, and highlight the importance of S uptake after anthesis to the accumulation of S in grain under the experimental conditions employed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00445.x
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  • 8
    Digitale Medien
    Digitale Medien
    Uptake and transport of zinc in the hyperaccumulator Thlaspi caerulescens and the non-hyperaccumulator Thlaspi ochroleucum (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Growth and zinc uptake of the hyperaccumulator species Thlaspi caerulescens J. & C. Presl and the non-hyperaccumulator species Thlaspi ochroleucum Boiss. & Heldr. were compared in solution culture experiments. T. caerulescens was able to tolerate 500 mmol m−3 (32.5 g m−3) Zn in solution without growth reduction, and up to 1000 mmol m−3 (65 g m−3) Zn without showing visible toxic symptoms but with a 25% decrease in dry matter (DM) yield. Up to 28 g kg−1 of Zn in shoot DM was obtained in healthy plants of T. caerulescens. In contrast, T. ochroleucum suffered severe phytotoxicity at 500 mmol m−3 Zn. Marked differences were shown in Zn uptake, distribution and redistribution between the two species. T. caerulescens had much higher concentrations of Zn in the shoots, whereas T. ochroleucum accumulated higher concentrations of Zn in the roots. When an external supply of 500 mmol m−3 Zn was withheld, 89% of the Zn accumulated previously in the roots of T. caerulescens was transported to the shoots over a 33 d period, whereas in T. ochroleucum only 32% was transported. T. caerulescens was shown to have a greater internal requirement for Zn than other plants. Increasing the supply of Zn from 1 to 10 mmol m−3 gave a 19% increase in the total DM of this species. liven the shoots from the 1 mmol m−3 Zn treatment which showed Zn deficiency contained 10 times greater Zn concentrations than the widely reported critical value for Zn deficiency to occur in many other plant species. The results obtained suggest that strongly expressed constitutive sequestration mechanisms exist in the hyperaccumulator T. caerulescens, which detoxify the large amount of Zn present in shoot tissues and decrease its physiological availability in the cytosol. Both T. caerulescens and T. ochroleucum had constitutively high concentrations of malate in shoots, which were little affected by different Zn treatments. Although malate may play a role in Zn chelation because of the high concentrations present, it cannot explain the species specificity of Zn tolerance and hyperaccumulation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-134.x
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  • 9
    Digitale Medien
    Digitale Medien
    Functional projection distances of spinal interneurons mediating reciprocal inhibition during swimming in Xenopus tadpoles (2001)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 13 (2001), S. 0 
    Details
    ISSN: 1460-9568
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The basis for longitudinal coordination among spinal neurons during locomotion is still poorly understood. We have now examined the functional projection distances for the longitudinal axons of reciprocal inhibitory ‘commissural interneurons’ in the spinal cord of young Xenopus tadpoles. In quiescent animals, glycinergic inhibitory postsynaptic potentials (IPSPs) were evoked in ventral spinal neurons by stimulating small rostral and caudal groups of commissural interneuron somata at different distances on the opposite side of the hindbrain and spinal cord. Unitary IPSPs, produced by single synaptic contacts, could be distinguished from background noise. Local cord stimulation at different distances revealed maximum functional projection distances up to ∼ 0.5 mm for both descending and ascending axons, but with the probability of recording connections falling steeply over this distance. These maximum longitudinal projection distances are smaller than predicted by axonal anatomy (∼ 1.2 mm). We then measured functional projection distances during swimming by examining the synaptic output of a surgically isolated group of rostral commissural interneurons, mapping the occurrence of the mid-cycle, reciprocal IPSPs they produced in more caudal neurons. IPSPs occurred with high probability up to 0.9 mm away, nearly twice the projection distance found in quiescent tadpoles. These results show that synaptic contacts from commissural interneurons could influence longitudinal coupling during swimming at distances of up to 0.9 mm (∼ 4–5 myotome segments or ∼ 25% of the spinal cord). They provide direct evidence for functional projection distances of a characterized class of interneurons belonging to a spinal locomotor pattern generator.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1460-9568.2001.01419.x
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  • 10
    Digitale Medien
    Digitale Medien
    Impact and implications of price policy and land degradation on agricultural growth in developing countries
    Amsterdam : Elsevier
    Agricultural Economics 5 (1991), S. 311-324 
    Details
    ISSN: 0169-5150
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://linkinghub.elsevier.com/retrieve/pii/0169-5150(91)90025-G
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