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1.
Jean-Baptiste Ramond Pamela J. Welz Marla I. Tuffin Stephanie G. Burton Don A. Cowan 《Microbial ecology》2013,66(3):563-570
Agri effluents such as winery or olive mill wastewaters are characterized by high phenolic concentrations. These compounds are highly toxic and generally refractory to biodegradation. Biological sand filters (BSFs) represent inexpensive, environmentally friendly, and sustainable wastewater treatment systems which rely vastly on microbial catabolic processes. Using denaturing gradient gel electrophoresis and terminal-restriction fragment length polymorphism, this study aimed to assess the impact of increasing concentrations of synthetic phenolic-rich wastewater, ranging from 96 mg L?1 gallic acid and 138 mg L?1 vanillin (i.e., a total chemical oxygen demand (COD) of 234 mg L?1) to 2,400 mg L?1 gallic acid and 3,442 mg L?1 vanillin (5,842 mg COD L?1), on bacterial communities and the specific functional diazotrophic community from BSF mesocosms. This amendment procedure instigated efficient BSF phenolic removal, significant modifications of the bacterial communities, and notably led to the selection of a phenolic-resistant and less diverse diazotrophic community. This suggests that bioavailable N is crucial in the functioning of biological treatment processes involving microbial communities, and thus that functional alterations in the bacterial communities in BSFs ensure provision of sufficient bioavailable nitrogen for the degradation of wastewater with a high C/N ratio. 相似文献
2.
Because of the ability to cleave RNA substrates in trans, the hairpin ribozyme has great potential for therapeutic application. Activity of a three-stranded version of the minimal truncated form is enhanced by the presence of the polyamine spermine. Since spermine is the most abundant polyamine in eucariots, improved prospects for the hairpin ribozyme as therapeutic agent were predicted. We have found that not all hairpin ribozyme variants accept spermine equally well as counter-ion. Particularly the two-stranded versions commonly used for therapeutic studies show rather decreased activity when spermine is present. We have investigated a number of hairpin ribozyme derivatives regarding their ability to carry out spermine supported catalysis. Among the studied structures a two-stranded reverse-joined hairpin ribozyme displayed the highest cleavage rates in a synergistic mixture of magnesium ions and spermine. The specific features of this ribozyme along with its potential for in vivo application are discussed. 相似文献
3.
Haussmann BI Hess DE Omanya GO Folkertsma RT Reddy BV Kayentao M Welz HG Geiger HH 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,109(5):1005-1016
Molecular markers for resistance of sorghum to the hemi-parasitic weed Striga hermonthica were mapped in two recombinant inbred populations (RIP-1, -2) of F3:5 lines developed from the crosses IS9830 × E36-1 (1) and N13 × E36-1 (2). The resistant parental lines were IS9830 and N13; the former is characterized by a low stimulation of striga seed germination, the latter by mechanical resistance. The genetic maps of RIP-1 and RIP-2 spanned 1,498 cM and 1,599 cM, respectively, with 137 and 157 markers distributed over 11 linkage groups. To evaluate striga resistance, we divided each RIP into set 1 (116 lines tested in 1997) and set 2 (110 lines evaluated in 1998). Field trials were conducted in five environments per year in Mali and Kenya. Heritability estimates for area under the striga number progress curve (ASNPC) in sets 1 and 2 were respectively 0.66 and 0.74 in RIP-1 and 0.81 and 0.82 in RIP-2. Across sites, composite interval mapping detected 11 QTL (quantitative trait loci) and nine QTL in sets 1 and 2 of RIP-1, explaining 77% and 80% of the genetic variance for ASNPC, respectively. The most significant RIP-1 QTL corresponded to the major-gene locus lgs (low stimulation of striga seed germination) in linkage group I. In RIP-2, 11 QTL and nine QTL explained 79% and 82% of the genetic variance for ASNPC in sets 1 and 2, respectively. Five QTL were common to both sets of each RIP, with the resistance alleles deriving from IS9830 or N13. Since their effects were validated across environments, years and independent RIP samples, these QTL are excellent candidates for marker-assisted selection. 相似文献
4.
RNA double cleavage by a hairpin-derived twin ribozyme 总被引:4,自引:4,他引:0
The hairpin ribozyme is a small catalytic RNA that catalyses reversible sequence-specific RNA hydrolysis in trans. It consists of two domains, which interact with each other by docking in an antiparallel fashion. There is a region between the two domains acting as a flexible hinge for interdomain interactions to occur. Hairpin ribozymes with reverse-joined domains have been constructed by dissecting the domains at the hinge and rejoining them in reverse order. We have used both the conventional and reverse-joined hairpin ribozymes for the design of a hairpin-derived twin ribozyme. We show that this twin ribozyme cleaves a suitable RNA substrate at two specific sites while maintaining the target specificity of the individual monoribozymes. For characterisation of the studied ribozymes we have evaluated a quantitative assay of sequence-specific ribozyme activity using fluorescently labelled RNA substrates in conjunction with an automated DNA sequencer. This assay was found to be applicable with hairpin and hairpin-derived ribozymes. The results demonstrate the potential of hairpin ribozymes for multi-target strategies of RNA cleavage and suggest the possibility for employing hairpin-derived twin ribozymes as powerful tools for RNA manipulation in vitro and in vivo. 相似文献
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7.
J Krücken A Harder P Jeschke L Holden-Dye V O'Connor C Welz G von Samson-Himmelstjerna 《Trends in parasitology》2012,28(9):385-394
The broad-spectrum anthelmintic cyclooctadepsipeptide PF1022A is a fungal metabolite from Rosellinia sp. PF1022, which is a Mycelia sterilia found on the leaves of Camellia japonica. A broad range of structurally related cyclooctadepsipeptides has been characterized and tested for anthelmintic activities. These metabolites have been used as starting points to generate semisynthetic derivatives with varying nematocidal capacity. Predominant among these compounds is emodepside, which exhibits a broad nematocidal potential against gastrointestinal and extraintestinal parasites. Here we review the chemical biology and mode of action of cyclooctadepsides with particular attention to PF1022A and emodepside. We illustrate how they target nematode neuromuscular function, opening up new avenues for antiparasitic treatments with potential capability for important selective toxicity. 相似文献
8.
H. G. Welz X. C. Xia P. Bassetti A. E. Melchinger T. Lübberstedt 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,99(3-4):649-655
Quantitative trait loci (QTLs) for resistance to the fungal pathogen Setosphaeria turcica, the cause of northern corn leaf blight (NCLB), were mapped in a population of 220 F3 families derived from a cross between two moderately resistant European inbred lines, D32 (dent) and D145 (flint). The population
was genotyped with 87 RFLP and 7 SSR markers. Trials were conducted in the field in Switzerland, and in the greenhouse with
selected F3 families in Germany. The F3 population segregated widely for resistance with transgression of the parents. By composite interval mapping, a total of
13 QTLs were detected with two disease ratings (0 and 3 weeks after flowering). Together these QTLs explained 48% and 62%
of the phenotypic variation. Gene action at most QTLs was partially dominant. Eight out of the 13 QTL alleles for resistance
were contributed by the more-resistant parent, D145. On chromosomes 3, 5 and 8, QTLs were located in the same chromosomal
regions as QTLs in tropical and U.S. Corn Belt germplasm. Some QTLs affected NCLB, head smut and common rust at the same time,
with alleles at these loci acting isodirectionally.
Received: 25 January 1999 / Accepted: 20 Februar 1999 相似文献
9.
H. G. Welz A. W. Schechert H. H. Geiger 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):1036-1045
Cultivars with quantitative resistance are widely used to control Setosphaeria turcica (Luttrell) Leonard & Suggs, the causal organism of northern corn leaf blight (NCLB). Here the effectiveness of quantitative
trait loci (QTLs) for NCLB resistance was investigated over the course of host plant development in inoculated field trials.
A population of 194–256 F2:3 lines derived from a cross between a susceptible Italian (Lo951) and a highly resistant African inbred line (CML202) was
tested in three environments in Kenya. The traits assessed were the incubation period (IP), the percentage disease severity
(DS 1 to 5, taken biweekly), and the area under the disease progress curve (AUDPC). Considering all resistance traits and
environments, a total of 19 putative QTLs were detected by composite interval mapping using a linkage map with 110 RFLP markers.
In the combined analysis across environments, nine QTLs were significant (LOD >3.0) for DS 3, recorded around flowering time,
explaining 71% of the genotypic variance. Four of these nine QTLs displayed significant (P<0.05) QTL×environment (QTL×E) interaction. Most QTLs were already significant in the juvenile stage (IP) and became less
effective after flowering. Across environments, three QTLs conditioned adult-plant resistance, in the sense that they were
only significant after flowering. Six QTL alleles on chromosomes 2, 4, 5, 8, and 9 of CML202 should be useful for marker-assisted
backcrossing.
Received: 24 August 1998 / Accepted: 29 September 1998 相似文献
10.
Heiko Rühl Lars Schr?der Jens Müller Shorena Sukhitashvili Julia Welz Walther C. Kuhn Johannes Oldenburg Christian Rudlowski Bernd P?tzsch 《PloS one》2014,9(8)