Showing papers by "Braunschweig University of Technology published in 2005"
TL;DR: It is hypothesized that the endophytes, in contrast to known pathogens, generally have far greater phenotypic plasticity and thus more options than pathogens: infection, local but also extensive colonisation, latency, virulence, pathogenity and (or) saprophytism.
1,323 citations
TL;DR: A novel method for the adaptation of target gene codon usage to most sequenced prokaryotes and selected eukaryotic gene expression hosts was developed to improve heterologous protein production using JCat (Java Codon Adaptation Tool).
Abstract: A novel method for the adaptation of target gene codon usage to most sequenced prokaryotes and selected eukaryotic gene expression hosts was developed to improve heterologous protein production. In contrast to existing tools, JCat (Java Codon Adaptation Tool) does not require the manual definition of highly expressed genes and is, therefore, a very rapid and easy method. Further options of JCat for codon adaptation include the avoidance of unwanted cleavage sites for restriction enzymes and Rho-independent transcription terminators. The output of JCat is both graphically and as Codon Adaptation Index (CAI) values given for the pasted sequence and the newly adapted sequence. Additionally, a list of genes in FASTA-format can be uploaded to calculate CAI values. In one example, all genes of the genome of Caenorhabditis elegans were adapted to Escherichia coli codon usage and further optimized to avoid commonly used restriction sites. In a second example, the Pseudomonas aeruginosa exbD gene codon usage was adapted to E.coli codon usage with parallel avoidance of the same restriction sites. For both, the degree of introduced changes was documented and evaluated. JCat is integrated into the PRODORIC database that hosts all required information on the various organisms to fulfill the requested calculations. JCat is freely accessible at http://www.prodoric.de/JCat.
970 citations
TL;DR: In this article, a collection of numerical algorithms for the solution of various problems arising in fractional models is presented, which will give the engineer the necessary tools required to work with fractional model in an efficient way.
592 citations
TL;DR: In this paper, the mathematical setting of stationary systems modelled by elliptic partial differential equations with stochastic coefficients (random fields) is investigated and stability with respect to stability.
590 citations
TL;DR: Spectra and high-resolution images obtained by the Huygens Probe Descent Imager/Spectral Radiometer instrument in Titan's atmosphere reveal the traces of once flowing liquid, and like Earth, the brighter highland regions show complex systems draining into flat, dark lowlands.
Abstract: The irreversible conversion of methane into higher hydrocarbons in Titan's stratosphere implies a surface or subsurface methane reservoir. Recent measurements from the cameras aboard the Cassini orbiter fail to see a global reservoir, but the methane and smog in Titan's atmosphere impedes the search for hydrocarbons on the surface. Here we report spectra and high-resolution images obtained by the Huygens Probe Descent Imager/Spectral Radiometer instrument in Titan's atmosphere. Although these images do not show liquid hydrocarbon pools on the surface, they do reveal the traces of once flowing liquid. Surprisingly like Earth, the brighter highland regions show complex systems draining into flat, dark lowlands. Images taken after landing are of a dry riverbed. The infrared reflectance spectrum measured for the surface is unlike any other in the Solar System; there is a red slope in the optical range that is consistent with an organic material such as tholins, and absorption from water ice is seen. However, a blue slope in the near-infrared suggests another, unknown constituent. The number density of haze particles increases by a factor of just a few from an altitude of 150 km to the surface, with no clear space below the tropopause. The methane relative humidity near the surface is 50 per cent.
551 citations
TL;DR: This study extended research on respites by examining the extent to which experiences during the weekend contribute to health and job performance after the weekend and reveals practical implications for individual and organizational optimization of recovery processes.
Abstract: This study extended research on respites by examining the extent to which experiences during the weekend contribute to health and job performance after the weekend. Longitudinal data including 3 measurement occasions from 87 emergency service workers indicated that nonwork hassles, absence of positive work reflection, and low social activity during the weekend predicted burnout and poor general well-being after the weekend. Weekend experiences also predicted different aspects of job performance after the weekend. The results reveal practical implications for individual and organizational optimization of recovery processes. Suggestions for future research on specific recovery processes and their effects on individual health and performance are discussed.
410 citations
TL;DR: Although parents from more disadvantaged areas had a lower overall level of participation in the project once recruited, parents with children having higher levels of behavior problems indeed were more likely to participate in the intervention.
Abstract: Despite the potential of parent training as a prevention and behavioral family intervention strategy, there are a number of important issues related to implementation (e.g., recruitment and retention of families). This paper presents recruitment and retention data from families enrolling in a randomized controlled universal prevention trial for child behavior problems conducted in Germany. The recruitment rate averaged 31% (general project participation), with families of lower socioeconomic status (SES) participating at a lower rate. Project-declining families most often reported intrusion of privacy as their primary concern. In contrast, once parents were enrolled in the project, participation among those randomized to the parent training group averaged 77% (program/intervention participation); non-participation was mostly due to logistical issues. Parents accepting the offer of parent training were more likely to report child behavior problems than did declining parents. Although parents from more disadvantaged areas had a lower overall level of participation in the project once recruited, parents with children having higher levels of behavior problems indeed were more likely to participate in the intervention. Different recruitment methods may be required to engage high-risk families from socioeconomically disadvantaged areas to further improve community-level impact on child mental health.
404 citations
TL;DR: It is shown that under suitable growth conditions hexagonal V-shaped pits decorating the defects exhibit narrow sidewall quantum wells with an effective band gap significantly larger than that of the regular c-plane quantum wells.
Abstract: Despite the high density of threading dislocations generally found in (AlGaIn)N heterostructures, the light emission efficiency of such structures is exceptionally high. It has become common to attribute the high efficiency to compositional fluctuations or even phase separation in the active GaInN quantum well region. The resulting localization of charge carriers is thought to keep them from recombining nonradiatively at the defects. Here, we show that random disorder is not the key but that under suitable growth conditions hexagonal V-shaped pits decorating the defects exhibit narrow sidewall quantum wells with an effective band gap significantly larger than that of the regular c-plane quantum wells. Thereby nature provides a unique, hitherto unrecognized mechanism generating a potential landscape which effectively screens the defects themselves by providing an energy barrier around every defect.
396 citations
TL;DR: A new online framework for the accurate and integrative prediction of transcription factor binding sites (TFBSs) in prokaryotes was developed and a free and easy to use collection of interconnected tools in the field of molecular microbiology, infection and systems biology is provided.
Abstract: Summary: A new online framework for the accurate and integrative prediction of transcription factor binding sites (TFBSs) in prokaryotes was developed. The system consists of three interconnected modules: (1) The PRODORIC database as a comprehensive data source and extensive collection of TFBSs with corresponding position weight matrices. (2) The pattern matching tool Virtual Footprint for the prediction of genome based regulons and for the analysis of individual promoter regions. (3) The interactive genome browser GBPro for the visualization of TFBS search results in their genomic context and links to gene and regulator-specific information in PRODORIC. The aim of this service is to provide researchers a free and easy to use collection of interconnected tools in the field of molecular microbiology, infection and systems biology.
Availability: http://www.prodoric.de/vfp
Contact: [email protected]
375 citations
28 Jan 2005
TL;DR: In this article, the authors present three perspectives on performance: an individual differences perspective, a situational perspective, and a performance regulation perspective with a focus on the performance process, and describe how current changes in the nature of work such as the focus on continuous learning and proactivity, increase in team work, improved technology and trends toward globalization have an impact on performance concept and future performance research.
Abstract: SUMMARY This chapter gives an overview of research on individual performance. Individual performance is highly important for an organization as a whole and for the individuals working in it. Performance comprises both a behavioral and an outcome aspect. It is a multi-dimensional and dynamic concept. This chapter presents three perspectives on performance: an individual differences perspective with a focus on individual characteristics as sources for variation in performance; a situational perspective with a focus on situational aspects as facilitators and impediments for performance; and a performance regulation perspective with a focus on the performance process. The chapter describes how current changes in the nature of work such as the focus on continuous learning and proactivity, increase in team work, improved technology, and trends toward globalization have an impact on the performance concept and future performance research.
364 citations
TL;DR: It is shown that the A. nidulans phytochrome FphA binds a biliverdin chromophore, acts as a red-light sensor, and represses sexual development under red- light conditions, the first phy tochrome experimentally characterized outside the plant and bacterial kingdoms and the second type of fungal protein identified that functions in photoperception.
TL;DR: The aim of the present study was the development and characterisation of surface-modified SLN for adsorptive protein loading by variation of both the lipid matrix and the emulsifier concentration in the continuous phase.
TL;DR: The phylogenetic novelty of the hydrolases suggests that some of them may have potential for new applications in biocatalysis and the sequences and contexts of neighbouring genes suggested suggested tentative phylogenetic assignments of the rumen organisms producing the retrieved enzymes.
Abstract: A metagenome expression library of bulk DNA extracted from the rumen content of a dairy cow was established in a phage lambda vector and activity-based screening employed to explore the functional diversity of the microbial flora. Twenty-two clones specifying distinct hydrolytic activities (12 esterases, nine endo-beta-1,4-glucanases and one cyclodextrinase) were identified in the library and characterized. Sequence analysis of the retrieved enzymes revealed that eight (36%) were entirely new and formed deep-branched phylogenetic lineages with no close relatives among known ester- and glycosyl-hydrolases. Bioinformatic analyses of the hydrolase gene sequences, and the sequences and contexts of neighbouring genes, suggested tentative phylogenetic assignments of the rumen organisms producing the retrieved enzymes. The phylogenetic novelty of the hydrolases suggests that some of them may have potential for new applications in biocatalysis.
TL;DR: It is shown that CED-1, C-6 and C-7 are required for actin reorganization around the apoptotic cell corpse, and that C-10(Rac) GTPase acts genetically downstream of these proteins to mediate corpse removal, functionally linking the two engulfment pathways and identifying the CED, -6 and -7 signalling module as upstream regulators of Rac activation.
Abstract: The removal of apoptotic cells is essential for the physiological well being of the organism. In Caenorhabditis elegans, two conserved, partially redundant genetic pathways regulate this process. In the first pathway, the proteins CED-2, CED-5 and CED-12 (mammalian homologues CrkII, Dock180 and ELMO, respectively) function to activate CED-10 (Rac1). In the second group, the candidate receptor CED-1 (CD91/LRP/SREC) probably recognizes an unknown ligand on the apoptotic cell and signals via its cytoplasmic tail to the adaptor protein CED-6 (hCED-6/GULP), whereas CED-7 (ABCA1) is thought to play a role in membrane dynamics. Molecular understanding of how the second pathway promotes engulfment of the apoptotic cell is lacking. Here, we show that CED-1, CED-6 and CED-7 are required for actin reorganization around the apoptotic cell corpse, and that CED-1 and CED-6 colocalize with each other and with actin around the dead cell. Furthermore, we find that the CED-10(Rac) GTPase acts genetically downstream of these proteins to mediate corpse removal, functionally linking the two engulfment pathways and identifying the CED-1, -6 and -7 signalling module as upstream regulators of Rac activation.
TL;DR: A general model for quantum channels with memory is presented and it is shown that it is sufficiently general to encompass all causal automata: any quantum process in which outputs up to some time do not depend on inputs at times can be decomposed into a concatenated memory channel.
Abstract: We present a general model for quantum channels with memory and show that it is sufficiently general to encompass all causal automata: any quantum process in which outputs up to some time $t$ do not depend on inputs at times ${t}^{\ensuremath{'}}gt$ can be decomposed into a concatenated memory channel. We then examine and present different physical setups in which channels with memory may be operated for the transfer of (private) classical and quantum information. These include setups in which either the receiver or a malicious third party have control of the initializing memory. We introduce classical and quantum channel capacities for these settings and give several examples to show that they may or may not coincide. Entropic upper bounds on the various channel capacities are given. For forgetful quantum channels, in which the effect of the initializing memory dies out as time increases, coding theorems are presented to show that these bounds may be saturated. Forgetful quantum channels are shown to be open and dense in the set of quantum memory channels.
TL;DR: The current sheet within the magnetosphere is thinner and more extended, and the external magnetic field is different compared with past spacecraft observations, and small diamagnetic cavities and ion cyclotron waves of types that were not reported before are observed.
Abstract: Cassini's successful orbit insertion has provided the first examination of Saturn's magnetosphere in 23 years, revealing a dynamic plasma and magnetic environment on short and long time scales. There has been no noticeable change in the internal magnetic field, either in its strength or its near-alignment with the rotation axis. However, the external magnetic field is different compared with past spacecraft observations. The current sheet within the magnetosphere is thinner and more extended, and we observed small diamagnetic cavities and ion cyclotron waves of types that were not reported before.
TL;DR: In this article, the authors identified a class II-type O-phosphoseryl-tRNA synthetase (SepRS) and SepCysS, which can also act as the sole route for cysteine biosynthesis.
Abstract: Several methanogenic archaea lack cysteinyl-transfer RNA (tRNA) synthetase (CysRS), the essential enzyme that provides Cys-tRNA(Cys) for translation in most organisms. Partial purification of the corresponding activity from Methanocaldococcus jannaschii indicated that tRNA(Cys) becomes acylated with O-phosphoserine (Sep) but not with cysteine. Further analyses identified a class II-type O-phosphoseryl-tRNA synthetase (SepRS) and Sep-tRNA:Cys-tRNA synthase (SepCysS). SepRS specifically forms Sep-tRNA(Cys), which is then converted to Cys-tRNA(Cys) by SepCysS. Comparative genomic analyses suggest that this pathway, encoded in all organisms lacking CysRS, can also act as the sole route for cysteine biosynthesis. This was proven for Methanococcus maripaludis, where deletion of the SepRS-encoding gene resulted in cysteine auxotrophy. As the conversions of Sep-tRNA to Cys-tRNA or to selenocysteinyl-tRNA are chemically analogous, the catalytic activity of SepCysS provides a means by which both cysteine and selenocysteine may have originally been added to the genetic code.
TL;DR: The present paper provides a summary of the collision-induced dissociation of protonated and deprotonated phase II metabolites of drugs and pesticides, and the fragmentation of the major classes of conjugates is reported.
TL;DR: Early approaches to model this morphologic development are recapitulated in this review to explain current trends in this area of research and present recent advances in the investigation of fungal metabolism.
Abstract: Cultivation processes involving filamentous fungi have been optimised for decades to obtain high product yields. Several bulk chemicals like citric acid and penicillin are produced this way. A simple adaptation of cultivation parameters for new production processes is not possible though. Models explaining the correlation between process-dependent growth behaviour and productivity are therefore necessary to prevent long-lasting empiric test series. Yet, filamentous growth consists of a complex microscopic differentiation process from conidia to hyphae resulting in various macroscopically visible appearances. Early approaches to model this morphologic development are recapitulated in this review to explain current trends in this area of research. Tailoring morphology by adjusting process parameters is one side of the coin, but an ideal morphology has not even been found. This article reviews several reasons for this fact starting with nutrient supply in a fungal culture and presents recent advances in the investigation of fungal metabolism. It illustrates the challenge to unfold the relationship between morphology and productivity.
TL;DR: A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is demonstrated, which demonstrated that the appropriate use of SIDA helped to account for matrix effects.
Abstract: The aim of this study was to quantify, in a single analysis, 31 volatile fermentation-derived products that contribute to the aroma of red and white wine. We developed a multi-component method based on headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME-GC-MS). The 31 volatile compounds analysed include ethyl esters, acetates, acids and alcohols. Although these compounds have a range of functional groups, chemical properties, volatilities, affinities for the SPME fibre, and are found in wine at various concentrations, the accuracy of the analysis was achieved with the use of polydeuterated internal standards for stable isotope dilution analyses (SIDA). Nine of the labelled standards were commercially available, while 22 were synthesised. The method was validated by a series of duplicate spiked standard additions to model, white and red wine matrices over the concentration range relevant for each compound in wine. This demonstrated that the appropriate use of SIDA helped to account for matrix effects, for instance potential sources of variation such as the relative response to the MS detector, ionic strength, ethanol content and pH of different wine matrices. The resultant calibration functions had correlation coefficients (R2) ranging from 0.995 to 1.000. Each compound could be quantified at levels below its aroma threshold in wine. Relative standard deviations were all <5%. The method was optimised for the best compromise (over the 31 compounds) of wine dilution factor, level of sodium chloride addition, SPME fibre, SPME temperature, SPME time, GC column and MS conditions. Confirmation of identity was achieved by retention time and peak shape, and measurement of at least three ions for each analyte and internal standard with the MS operating in selected ion monitoring mode to facilitate more precise quantitation with a high sampling rate. The method is a valuable research tool with many relevant applications. A novel method for the combined chiral separation and SIDA quantification of 2- and 3-methylbutanoic acid is also demonstrated.
10 Oct 2005
TL;DR: A mean opinion score metric borrowed from the subjective analysis of audio and video content is introduced to classify the player's perceived game quality to investigate the effect of latency and jitter on multiplayer games.
Abstract: In this paper we analyse different factors affecting players' perception and performance in multiplayer games. We introduce a mean opinion score metric borrowed from the subjective analysis of audio and video content to classify the player's perceived game quality. With a survey we investigated the player's view on network latency for a variety of games. Furthermore, we examine four different games under different network conditions and collect data on game score and subjective perception from every player. During the evaluation, we investigate the effect of latency and jitter on multiplayer games. We use regression analysis methods to identify coherences between delay, jitter, skill, game score, and the subjective impression of the player. Finally, we compare the results from the survey and the experiments.
TL;DR: It is demonstrated that nutrient amendment to hydrocarbon-contaminated superficial sediments enhanced the indigenous microbial biodegradation activity and that highly specialized marine hydrocarbonoclastic bacteria, representing a minor fraction in the natural microbial community, play an important role in the biodegrading of petroleum hydrocarbons accidentally entering the coastal environment.
Abstract: Summary
Hydrocarbon-contaminated superficial sediments collected from the Harbor of Milazzo (Tirrenean Sea, northern Sicily), a zone strongly affected by anthropogenic activities, were examined for in situ biodegradative capacities. A culture-independent molecular phylogenetic approach was used to study the influence of hydrocarbon and nutrient addition on the activity and diversity of the indigenous microbiota during a microcosm evaluation. The autochthonous microbial community in non-polluted sediments was represented by eubacterial phylotypes grouped within Proteobacteria, CFB and Firmicutes. The archaeal domain was represented by members of Marine Group I of Crenarchaeota. The majority of recovered sequences was affiliated with heterotrophic genera Clostridium and Vibrio, typical members of eutrophic coastal environments. Amendments of hydrocarbons and mineral nutrients to microcosms dramatically changed the initial diversity of the microbial community. Only bacterial phylotypes affiliated with Proteobacteria and CFB division were detected. The decrease in diversity observed in several microcosms could be explained by the strong selection for microorganisms belonging to group of marine hydrocarbonoclastic γ-Proteobacteria, namely Alcanivorax, Cycloclasticus, Marinobacter, Marinobacterium/Neptunomonas and Thalassolituus. This study demonstrated that nutrient amendment to hydrocarbon-contaminated superficial sediments enhanced the indigenous microbial biodegradation activity and that highly specialized marine hydrocarbonoclastic bacteria, representing a minor fraction in the natural microbial community, play an important role in the biodegradation of petroleum hydrocarbons accidentally entering the coastal environment.
TL;DR: Under controlled conditions it is possible to use the THz image to distinguish between the two RNA strands, and the requirements to sample preparation imposed by the lack of sharp spectral features in the absorption spectra are discussed.
Abstract: We use terahertz time-domain spectroscopy (THz-TDS) to measure the far-infrared dielectric function of two artificial RNA single strands, composed of polyadenylic acid (poly-A) and polycytidylic acid (poly-C). We find a significant difference in the absorption between the two types of RNA strands, and we show that we can use this difference to record images of spot arrays of the RNA strands. Under controlled conditions it is possible to use the THz image to distinguish between the two RNA strands. We discuss the requirements to sample preparation imposed by the lack of sharp spectral features in the absorption spectra.
TL;DR: The structure of ALAS completes the structural analysis of enzymes in heme biosynthesis and is presented, revealing the molecular basis of XLSA in humans.
Abstract: 5-Aminolevulinate synthase (ALAS) is the first and rate-limiting enzyme of heme biosynthesis in humans, animals, other non-plant eukaryotes, and α-proteobacteria. It catalyzes the synthesis of 5-aminolevulinic acid, the first common precursor of all tetrapyrroles, from glycine and succinyl-coenzyme A (sCoA) in a pyridoxal 5′-phosphate (PLP)-dependent manner. X-linked sideroblastic anemias (XLSAs), a group of severe disorders in humans characterized by inadequate formation of heme in erythroblast mitochondria, are caused by mutations in the gene for erythroid eALAS, one of two human genes for ALAS. We present the first crystal structure of homodimeric ALAS from Rhodobacter capsulatus (ALASRc) binding its cofactor PLP. We, furthermore, present structures of ALASRc in complex with the substrates glycine or sCoA. The sequence identity of ALAS from R. capsulatus and human eALAS is 49%. XLSA-causing mutations may thus be mapped, revealing the molecular basis of XLSA in humans. Mutations are found to obstruct substrate binding, disrupt the dimer interface, or hamper the correct folding. The structure of ALAS completes the structural analysis of enzymes in heme biosynthesis.
TL;DR: The widespread occurrence of quorum‐sensing compounds in marine Alphaproteobacteria, both free‐living strains and those associated to eukaryotic algae, points to a great importance of this signalling mechanism for the adaptation of the organisms to their widely different ecological niches.
Abstract: More than 100 bacterial isolates from various marine habitats were screened for AHL production by using gfp reporter constructs based on the lasR system of Pseudomonas aeruginosa and the luxR system of Vibrio fischeri. Of the 67 Alphaproteobacteria tested, most of which belonged into the so-called Roseobacter clade, 39 induced fluorescence in either one or both sensor strains up to 103-fold compared to controls. Acylated homoserine lactones were identified by GC-MS analysis and shown to have chain lengths of C8, C10, C13–C16, and C18. One or two double bonds were often present, while a keto or hydroxyl group occurred only rarely in the side chain. Most strains produced several different AHLs. C18-en-HSL and C18-dien-HSL were produced by Dinoroseobacter shibae, an aerobic anoxygenic phototrophic bacterium isolated from dinoflagellates, and are among the longest AHLs found to date. Z7-C14-en-HSL, which has previously been detected in Rhodobacter sphaeroides, was produced by Roseovarius tolerans and Jannaschia helgolandensis. This signal molecule was synthesised and shown to induce a similar response to the culture supernatant in the respective sensor strain. The widespread occurrence of quorum-sensing compounds in marine Alphaproteobacteria, both free-living strains and those associated to eukaryotic algae, points to a great importance of this signalling mechanism for the adaptation of the organisms to their widely different ecological niches.
TL;DR: The principles and advocated practices of agile processes are examined and limitations that may arise from these assumptions are identified and how the limitations can be addressed by incorporating other software-development techniques and practices into agile development environments are outlined.
Abstract: Agile processes focus on the early facilitation and fast production of working code, and are based on software-development process models that support iterative, incremental development of software. Although agile methods have existed for a number of years now, answers to questions concerning the suitability of agile processes to particular software-development environments are still often based on anecdotal accounts of experiences. An appreciation of the (often unstated) assumptions underlying agile processes can lead to a better understanding of the applicability of agile processes to particular situations. Agile processes are less likely to be applicable in situations in which core assumptions do not hold. This article examines the principles and advocated practices of agile processes to identify underlying assumptions. It also identifies limitations that may arise from these assumptions and outlines how the limitations can be addressed by incorporating other software-development techniques and practices into agile development environments.
TL;DR: In this article, a numerical method for the analysis of fluid-structure interaction problems with free surface flows is presented, where a consistent space-time finite element discretization for both continua and a strong coupling algorithm is applied to the highly non-linear problem.
TL;DR: A computational approach to genome analysis is developed that searches for widely separated genes encoding tRNA halves that, on the basis of structural prediction, could form intact tRNA molecules.
Abstract: Analysis of the genome sequence of the small hyperthermophilic archaeal parasite Nanoarchaeum equitans has not revealed genes encoding the glutamate, histidine, tryptophan and initiator methionine transfer RNA species. Here we develop a computational approach to genome analysis that searches for widely separated genes encoding tRNA halves that, on the basis of structural prediction, could form intact tRNA molecules. A search of the N. equitans genome reveals nine genes that encode tRNA halves; together they account for the missing tRNA genes. The tRNA sequences are split after the anticodon-adjacent position 37, the normal location of tRNA introns. The terminal sequences can be accommodated in an intervening sequence that includes a 12-14-nucleotide GC-rich RNA duplex between the end of the 5' tRNA half and the beginning of the 3' tRNA half. Reverse transcriptase polymerase chain reaction and aminoacylation experiments of N. equitans tRNA demonstrated maturation to full-size tRNA and acceptor activity of the tRNA(His) and tRNA(Glu) species predicted in silico. As the joining mechanism possibly involves tRNA trans-splicing, the presence of an intron might have been required for early tRNA synthesis.
TL;DR: The results implicate p75NTR in activity-dependent synaptic plasticity and extend the concept of functional antagonism of the neurotrophin signaling system.
Abstract: Neurotrophins are involved in the modulation of synaptic transmission, including the induction of long-term potentiation (LTP) through the receptor TrkB. Because previous studies have revealed a bidirectional mode of neurotrophin action by virtue of signaling through either the neurotrophin receptor p75NTR or the Trk receptors, we tested the hypothesis that p75NTR is important for longterm depression (LTD) to occur. Although LTP was found to be unaffected in hippocampal slices of two different strains of mice carrying mutations of the p75NTR gene, hippocampal LTD was impaired in both p75NTR-deficient mouse strains. Furthermore, the expression levels of two (RS)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits, GluR2 and GluR3, but not GluR1 or GluR4, were found to be significantly altered in the hippocampus of p75NTR-deficient mice. These results implicate p75NTR in activity-dependent synaptic plasticity and extend the concept of functional antagonism of the neurotrophin signaling system.
TL;DR: The present model successfully explains the pesticide concentrations associated with single entry events caused by runoff, especially at concentration levels above (>or=0.5 microg/l), and is suitable for use in routine exposure assessment of pesticides on a landscape level.