排序方式: 共有79条查询结果,搜索用时 15 毫秒
31.
Christine Römermann Oliver Tackenberg Anne-Kathrin Jackel Peter Poschlod 《Biodiversity and Conservation》2008,17(3):591-604
Due to ubiquitous eutrophication and fragmentation, many plant species are actually threatened in Europe. Most ecosystems
face an overall nutrient input leading to changes in species composition. Fragmentation is effectively influencing species
survival. We investigate if two different measures of species performance of 91 calcareous grassland species–rate of decline
and rarity—are related to comparable traits and hence processes. On the one hand we expected that species rate of decline
is mainly determined by the processes of eutrophication and fragmentation. On the other hand we hypothesized that the importance
of site characteristics may overwhelm the effect of eutrophication and fragmentation for species rarity. Hence, we compared
persistence traits responding to eutrophication, dispersal traits being related to fragmentation and ecological site factors
for decreasing and increasing species and for rare and common species. The results suggest that increasing species had better
means of long-distance dispersal and were more competitive than decreasing species. In contrast, there were hardly any differences
in traits between rare and common species, but site characteristics were related to species rarity. Rare species were in the
main those with ecological preferences for warm, dry, light and nutrient poor conditions. This study may represent a basis
for the assessment of plant species threat. Applying the deduced knowledge about the life history of decreasing versus increasing
species to habitat-scale approaches it is possible to predict which species may become threatened in the future simply from
the combination of their trait values.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
32.
Humaira Rasheed Cushla McKinney Lisa K. Stamp Nicola Dalbeth Ruth K. Topless Richard Day Diluk Kannangara Kenneth Williams Malcolm Smith Matthijs Janssen Tim L. Jansen Leo A. Joosten Timothy R. Radstake Philip L. Riches Anne-Kathrin Tausche Frederic Lioté Leo Lu Eli A. Stahl Hyon K. Choi Alexander So Tony R. Merriman 《PloS one》2016,11(1)
Deposition of crystallized monosodium urate (MSU) in joints as a result of hyperuricemia is a central risk factor for gout. However other factors must exist that control the progression from hyperuricaemia to gout. A previous genetic association study has implicated the toll-like receptor 4 (TLR4) which activates the NLRP3 inflammasome via the nuclear factor-κB signaling pathway upon stimulation by MSU crystals. The T-allele of single nucleotide polymorphism rs2149356 in TLR4 is a risk factor associated with gout in a Chinese study. Our aim was to replicate this observation in participants of European and New Zealand Polynesian (Māori and Pacific) ancestry. A total of 2250 clinically-ascertained prevalent gout cases and 13925 controls were used. Non-clinically-ascertained incident gout cases and controls from the Health Professional Follow-up (HPFS) and Nurses Health Studies (NHS) were also used. Genotypes were derived from genome-wide genotype data or directly obtained using Taqman. Logistic regression analysis was done including age, sex, diuretic exposure and ancestry as covariates as appropriate. The T-allele increased the risk of gout in the clinically-ascertained European samples (OR = 1.12, P = 0.012) and decreased the risk of gout in Polynesians (OR = 0.80, P = 0.011). There was no evidence for association in the HPFS or NHS sample sets. In conclusion TLR4 SNP rs2143956 associates with gout risk in prevalent clinically-ascertained gout in Europeans, in a direction consistent with previously published results in Han Chinese. However, with an opposite direction of association in Polynesians and no evidence for association in a non-clinically-ascertained incident gout cohort this variant should be analysed in other international gout genetic data sets to determine if there is genuine evidence for association. 相似文献
33.
34.
Klebl Anne-Kathrin Bräutigam Martin Klein Michael Kapp Markus Knippers Rolf Müller Dieter G. 《Hydrobiologia》1996,(1):105-110
The filamentous marine brown algae Ectocarpus siliculosus and Feldmannia simplex are infected by host specific DNA-viruses. Under Percoll isolation, Ectocarpus siliculosus-virus (EsV)-particles maintained their infective potential.The EsV has a circular genome of dsDNA with a size of 320 kb. A restriction map has been established. The gene of a major coat protein (gp1) was detected in a genomic library and partly sequenced. Using gpl- sequences for polymerase chain reaction (PCR) amplification analysis, EsV specific sequences could be detected in various symptom-free, clonal cultures of Ectocarpus. The PCR was also used to follow the passage of the virus genome during the meiosis of hosts. A monospecific antibody against recombinant gpl was used for immunostaining and infection experiments.The Feldmannia simplex-virus (FlexV-1) has a circular genome with a size of 220 kb and a 43% G+C content. FsV-DNA contains methylated bases. 5-methylcytosine (5 mC) makes up 12% of the total cytosines. 相似文献
35.
Wiedenheft B Stedman K Roberto F Willits D Gleske AK Zoeller L Snyder J Douglas T Young M 《Journal of virology》2004,78(4):1954-1961
The complete genome sequences of two Sulfolobus spindle-shaped viruses (SSVs) from acidic hot springs in Kamchatka (Russia) and Yellowstone National Park (United States) have been determined. These nonlytic temperate viruses were isolated from hyperthermophilic Sulfolobus hosts, and both viruses share the spindle-shaped morphology characteristic of the Fuselloviridae family. These two genomes, in combination with the previously determined SSV1 genome from Japan and the SSV2 genome from Iceland, have allowed us to carry out a phylogenetic comparison of these geographically distributed hyperthermal viruses. Each virus contains a circular double-stranded DNA genome of approximately 15 kbp with approximately 34 open reading frames (ORFs). These Fusellovirus ORFs show little or no similarity to genes in the public databases. In contrast, 18 ORFs are common to all four isolates and may represent the minimal gene set defining this viral group. In general, ORFs on one half of the genome are colinear and highly conserved, while ORFs on the other half are not. One shared ORF among all four genomes is an integrase of the tyrosine recombinase family. All four viral genomes integrate into their host tRNA genes. The specific tRNA gene used for integration varies, and one genome integrates into multiple loci. Several unique ORFs are found in the genome of each isolate. 相似文献
36.
The solubilization of Fe(III) hydroxide by the naturally occurring siderophoreN,N-bis(2,3-dihydroxybenzoyl)-l-lysine has been investigated spectrophotometrically in the presence and the absence of a stoichiometric amount of molybdate in aqueous medium at pH 7. In the absence of molybdate the reaction is 50% complete after 115 min. In contrast, the addition of an equimolar amount of molybdate results in an instantaneous formation of the molybdenum siderophore complex and a significant delay in the formation of the corresponding iron complex: 50% of the iron complex is present after 44 h and equilibrium is only reached after 2 weeks. The results are discussed with regard to metal acquisition by the nitrogen fixing cells ofAzotobacter vinelandii. 相似文献
37.
38.
Robert Huber Thomas G Palmen Nadine Ryk Anne-Kathrin Hillmer Karina Luft Frank Kensy Jochen Büchs 《BMC biotechnology》2010,10(1):22
Background
High-throughput cultivations in microtiter plates are the method of choice to express proteins from recombinant clone libraries. Such processes typically include several steps, whereby some of them are linked by replication steps: transformation, plating, colony picking, preculture, main culture and induction. In this study, the effects of conventional replication methods and replication tools (8-channel pipette, 96-pin replicators: steel replicator with fixed or spring-loaded pins, plastic replicator with fixed pins) on growth kinetics of Escherichia coli SCS1 pQE-30 pSE111 were observed. Growth was monitored with the BioLector, an on-line monitoring technique for microtiter plates. Furthermore, the influence of these effects on product formation of Escherichia coli pRhotHi-2-EcFbFP was investigated. Finally, a high-throughput cultivation process was simulated with Corynebacterium glutamicum pEKEx2-phoD-GFP, beginning at the colony picking step. 相似文献39.
Fairlamb IJ Duhme-Klair AK Lynam JM Moulton BE O'Brien CT Sawle P Hammad J Motterlini R 《Bioorganic & medicinal chemistry letters》2006,16(4):995-998
The CO-releasing properties of iron(0)tricarbonyl complexes bearing a 2-pyrone ligand have been evaluated. In this report, we demonstrate that the intrinsic stability of the (eta4-2-pyrone)Fe(CO)3 complex influences the extent and rate of CO release, which is affected by the presence of a halogen substituent on the 2-pyrone ring. The cell viability index has been highlighted for the active carbon monoxide-releasing molecules (CO-RMs), demonstrating that these complexes and related derivatives are a promising new class of compounds with potential therapeutic applications. 相似文献
40.
Sven Dänicke Hana Valenta Martin Ganter Bianca Brosig Susanne Kersten Anne-Kathrin Diesing Stefan Kahlert Patricia Panther Jeannette Kluess Hermann-Josef Rothkötter 《Mycotoxin Research》2014,30(3):161-170
Pigs might be exposed to lipopolysaccharides (LPS) and deoxynivalenol (DON) at the same time, and both toxins are thought to interactively affect the intestinal barrier, the innate immune system, and the xenobiotics metabolism. Hence, we aimed at examining the single and combined effects of both toxins on nutrient digestibility and DON metabolism. For this purpose, barrows (26?±?4 kg) were fed restrictedly either a control diet (CON) or a diet contaminated with 3.1 mg DON/kg (DON) for 37 days. At day 37 of the experiment, pigs were infused intravenously for 60 min either with 100 μg DON/kg body weight (BW) (CON-DON), 7.5 μg LPS/kg BW (CON-LPS, DON-LPS) or a combination of both substances (CON-DON?+?LPS), or physiological saline (CON-CON, DON-CON). Blood samples were collected frequently until 3.25 h before the pigs were sacrificed for bile, liver, and kidney collection. The apparent digestibility of N-free extractives was significantly increased by 1 % when the DON-contaminated diet was fed. The total DON content in blood was significantly higher in endotoxemic pigs (34.8 ng/mL; CON-DON?+?LPS) when compared to the pigs infused with DON alone (18.8 ng/mL; CON-DON) while bile concentrations were not influenced by LPS. DON residue levels in liver and kidney closely reflected the treatment effects as described for blood. In contrast to DON infusion, the LPS challenge resulted in a significantly lower total DON concentration (13.2 vs. 7.5 ng/mL in groups DON-CON and DON-LPS, respectively) when the pigs were exposed to DON through the diet. The conjugation degree for DON in blood and bile was not influenced by treatments. In conclusion, endotoxemic pigs are characterized by higher DON residue levels in blood, liver, and kidney, probably by a compromised elimination. 相似文献