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排序方式: 共有892条查询结果,搜索用时 15 毫秒
881.
882.
Juergen Kreyling Torsten Bittner Anja Jaeschke Anke Jentsch Manuel Jonas Steinbauer Daniel Thiel Carl Beierkuhnlein 《Restoration Ecology》2011,19(4):433-440
Assisted colonization as an adaptation strategy to conserve or restore biodiversity in the face of climate change deservedly evokes controversy. Assisted colonization is perceived by some as a last option for conserving endangered species and by others as a risky and unwise management effort due to current gaps of knowledge. Based on the pros and cons of the recent debate, we show that the current discussion mainly focuses on the assisted colonization of rare and endangered species beyond their natural range of distribution. We suggest that a more useful approach for the conservation of endangered species could occur by focusing on the relevant foundation or keystone species, which ensure ecosystem integrity for a multitude of dependent species by governing the habitat structure and micro‐climate of the site. Examples of foundation species include dominant tree species in forests or dominant corals in coral reefs. For a given conservation or restoration need (e.g. conservation of rare species), we recommend the assisted colonization of pre‐adapted ecotypes of the relevant foundation species from climates similar to future expectations for the target site. This approach could lead to climate‐safe habitats for endangered species with minimal adverse effects on recipient ecosystems. 相似文献
883.
Juergen Theuer Ralf Dechend Dominik N Muller Joon-Keun Park Anette Fiebeler Peter Barta Detlev Ganten Hermann Haller Rainer Dietz Friedrich C Luft 《BMC cardiovascular disorders》2002,2(1):3
Background
We are investigating a double transgenic rat (dTGR) model, in which rats transgenic for the human angiotensinogen and renin genes are crossed. These rats develop moderately severe hypertension but die of end-organ cardiac and renal damage by week 7. The heart shows necrosis and fibrosis, whereas the kidneys resemble the hemolytic-uremic syndrome vasculopathy. Surface adhesion molecules (ICAM-1 and VCAM-1) are expressed early on the endothelium, while the corresponding ligands are found on circulating leukocytes. Leukocyte infiltration in the vascular wall accompanies PAI-1, MCP-1, iNOS and Tissue Factor expression. Furthermore we show evidence that Ang II causes the upregulation of NF-kB in our model. 相似文献884.
Mathilde Borg Dahl Juergen Kreyling Sebastian Petters Haitao Wang Martin Steen Mortensen Lorrie Maccario Søren J. Sørensen Tim Urich Robert Weigel 《Environmental microbiology》2023,25(6):1118-1135
In temperate regions, climate warming alters temperature and precipitation regimes. During winter, a decline in insulating snow cover changes the soil environment, where especially frost exposure can have severe implications for soil microorganisms and subsequently for soil nutrient dynamics. Here, we investigated winter climate change responses in European beech forests soil microbiome. Nine study sites with each three treatments (snow exclusion, insolation, and ambient) were investigated. Long-term adaptation to average climate was explored by comparing across sites. Triplicated treatment plots were used to evaluate short-term (one single winter) responses. Community profiles of bacteria, archaea and fungi were created using amplicon sequencing. Correlations between the microbiome, vegetation and soil physicochemical properties were found. We identify core members of the forest-microbiome and link them to key processes, for example, mycorrhizal symbiont and specialized beech wood degraders (fungi) and nitrogen cycling (bacteria, archaea). For bacteria, the shift of the microbiome composition due to short-term soil temperature manipulations in winter was similar to the community differences observed between long-term relatively cold to warm conditions. The results suggest a strong link between the changes in the microbiomes and changes in environmental processes, for example, nitrogen dynamics, driven by variations in winter climate. 相似文献
885.
886.
Sibylle Bauer Dereje W Mekonnen Michael Hartmann Ipek Yildiz Robert Janowski Birgit Lange Birgit Geist Jürgen Zeier Anton R Schffner 《The Plant cell》2021,33(3):714
Glucosylation modulates the biological activity of small molecules and frequently leads to their inactivation. The Arabidopsis thaliana glucosyltransferase UGT76B1 is involved in conjugating the stress hormone salicylic acid (SA) as well as isoleucic acid (ILA). Here, we show that UGT76B1 also glucosylates N-hydroxypipecolic acid (NHP), which is synthesized by FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1) and activates systemic acquired resistance (SAR). Upon pathogen attack, Arabidopsis leaves generate two distinct NHP hexose conjugates, NHP-O-β-glucoside and NHP glucose ester, whereupon only NHP-O-β-glucoside formation requires a functional SA pathway. The ugt76b1 mutants specifically fail to generate the NHP-O-β-glucoside, and recombinant UGT76B1 synthesizes NHP-O-β-glucoside in vitro in competition with SA and ILA. The loss of UGT76B1 elevates the endogenous levels of NHP, SA, and ILA and establishes a constitutive SAR-like immune status. Introgression of the fmo1 mutant lacking NHP biosynthesis into the ugt76b1 background abolishes this SAR-like resistance. Moreover, overexpression of UGT76B1 in Arabidopsis shifts the NHP and SA pools toward O-β-glucoside formation and abrogates pathogen-induced SAR. Our results further indicate that NHP-triggered immunity is SA-dependent and relies on UGT76B1 as a common metabolic hub. Thereby, UGT76B1-mediated glucosylation controls the levels of active NHP, SA, and ILA in concert to balance the plant immune status. 相似文献
887.
In vivo coherent anti-Stokes Raman scattering microscopy reveals vitamin A distribution in the liver
Marko Rodewald Hyeonsoo Bae Sophie Huschke Tobias Meyer-Zedler Michael Schmitt Adrian Tibor Press Stephanie Schubert Michael Bauer Juergen Popp 《Journal of biophotonics》2021,14(6):e202100040
Here we present a microscope setup for coherent anti-Stokes Raman scattering (CARS) imaging, devised to specifically address the challenges of in vivo experiments. We exemplify its capabilities by demonstrating how CARS microscopy can be used to identify vitamin A (VA) accumulations in the liver of a living mouse, marking the positions of hepatic stellate cells (HSCs). HSCs are the main source of extracellular matrix protein after hepatic injury and are therefore the main target of novel nanomedical strategies in the development of a treatment for liver fibrosis. Their role in the VA metabolism makes them an ideal target for a CARS-based approach as they store most of the body's VA, a class of compounds sharing a retinyl group as a structural motive, a moiety that is well known for its exceptionally high Raman cross section of the C═C stretching vibration of the conjugated backbone. 相似文献
888.
Martin Lemmerer Juergen Mairhofer Alexander Lepak Karin Longus Rainer Hahn Bernd Nidetzky 《Biotechnology and bioengineering》2019,116(6):1259-1268
Sugar nucleotide-dependent (Leloir) glycosyltransferases from plants are important catalysts for the glycosylation of small molecules and natural products. Limitations on their applicability for biocatalytic synthesis arise because of low protein expression (≤10 mg/L culture) in standard microbial hosts. Here, we showed two representative glycosyltransferases: sucrose synthase from soybean and UGT71A15 from apple. A synthetic biology-based strategy of decoupling the enzyme expression from the Escherichia coli BL21(DE3) cell growth was effective in enhancing their individual (approximately fivefold) or combined (approximately twofold) production as correctly folded, biologically active proteins. The approach entails a synthetic host cell, which is able to shut down the production of host messenger RNA by inhibition of the E. coli RNA polymerase. Overexpression of the enzyme(s) of interest is induced by the orthogonal T7 RNA polymerase. Shutting down of the host RNA polymerase is achieved by l -arabinose-inducible expression of the T7 phage-derived Gp2 protein from a genome-integrated site. The glycosyltransferase genes are encoded on conventional pET-based expression plasmids that allow T7 RNA polymerase-driven inducible expression by isopropyl-β- d -galactoside. Laboratory batch and scaled-up (20 L) fed-batch bioreactor cultivations demonstrated improvements in an overall yield of active enzyme by up to 12-fold as a result of production under growth-decoupled conditions. In batch culture, sucrose synthase and UGT71A15 were obtained, respectively, at 115 and 2.30 U/g cell dry weight, corresponding to ∼5 and ∼1% of total intracellular protein. Fed-batch production gave sucrose synthase in a yield of 2,300 U/L of culture (830 mg protein/L). Analyzing the isolated glycosyltransferase, we showed that the improvement in the enzyme production was due to the enhancement of both yield (5.3-fold) and quality (2.3-fold) of the soluble sucrose synthase. Enzyme preparation from the decoupled production comprised an increased portion (61% compared with 26%) of the active sucrose synthase homotetramer. In summary, therefore, we showed that the expression in growth-arrested E. coli is promising for recombinant production of plant Leloir glycosyltransferases. 相似文献
889.
Juergen Geist Håkan Söderberg Andreas Karlberg Ralph Kuehn 《Conservation Genetics》2010,11(4):1339-1350
Freshwater pearl mussels (Margaritifera margaritifera) are among the most critically threatened bivalve molluscs worldwide. An understanding of spatial patterns of genetic diversity
is crucial for the development of integrative conservation strategies. We used microsatellites to study the genetic diversity
and differentiation of 14 populations of M. margaritifera in central Sweden, an area which was described as a major secondary contact zone in postglacial colonisation for other species.
Genetic diversity of Swedish pearl mussel populations was much greater than in central and southern Europe but similar to
the genetic diversity observed in the northeastern portion of their European range. Genetic differentiation among populations
was pronounced but to a large extent independent from present-day drainage systems. The complex patterns of genetic diversity
and differentiation in pearl mussel seem to be strongly influenced by the species’ high degree of specialisation and extraordinary
life history strategy which involves facultative hermaphrodism and an obligatory encystment stage on a host fish. Genetic
drift effects and anthropogenic disturbances resulting in reduction of population size and loss of connectivity are less pronounced
in northern pearl mussel populations compared to those in central and southern Europe. 相似文献
890.
David C. Aldridge Isobel S. Ollard Yulia V. Bespalaya Ivan N. Bolotov Karel Douda Juergen Geist Wendell R. Haag Michael W. Klunzinger Manuel Lopes-Lima Musa C. Mlambo Nicoletta Riccardi Ronaldo Sousa David L. Strayer Santiago H. Torres Caryn C. Vaughn Tadeusz Zając Alexandra Zieritz 《Global Change Biology》2023,29(3):575-589
We identified 14 emerging and poorly understood threats and opportunities for addressing the global conservation of freshwater mussels over the next decade. A panel of 17 researchers and stakeholders from six continents submitted a total of 56 topics that were ranked and prioritized using a consensus-building Delphi technique. Our 14 priority topics fell into five broad themes (autecology, population dynamics, global stressors, global diversity, and ecosystem services) and included understanding diets throughout mussel life history; identifying the drivers of population declines; defining metrics for quantifying mussel health; assessing the role of predators, parasites, and disease; informed guidance on the risks and opportunities for captive breeding and translocations; the loss of mussel–fish co-evolutionary relationships; assessing the effects of increasing surface water changes; understanding the effects of sand and aggregate mining; understanding the effects of drug pollution and other emerging contaminants such as nanomaterials; appreciating the threats and opportunities arising from river restoration; conserving understudied hotspots by building local capacity through the principles of decolonization; identifying appropriate taxonomic units for conservation; improved quantification of the ecosystem services provided by mussels; and understanding how many mussels are enough to provide these services. Solutions for addressing the topics ranged from ecological studies to technological advances and socio-political engagement. Prioritization of our topics can help to drive a proactive approach to the conservation of this declining group which provides a multitude of important ecosystem services. 相似文献