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71.
Microbial genomes harbor genomic islands (GIs), genes presumably acquired via horizontal gene transfer (HGT). We compared GIs of hyperthermophilic, thermophilic, mesophilic, and pathogenic/nonpathogenic species and of small and large genomes. The COG database was used to characterize gene-encoded functions. Putative donors were determined to quantify gene flux between superkingdoms. In hyperthermophiles, more than 10% of the genes were on average acquired across the superkingdom border. For thermophiles and particularly mesophiles, we identified a nearly unidirectional export from bacteria to archaea. Additionally, we analyzed GI composition for Escherichia, and pairs of Listeria, Rhizobiales, Methanosarcinaceae, and Thermus thermophilus/Deinococcus radiodurans. For Escherichia and Listeria, the composition of GIs in pathogenic and nonpathogenic species did not differ significantly with respect to encoded COG classes. The analysis of related genomes showed that the composition of GIs cannot be explained with trends of gene content known to depend on genome size. 相似文献
72.
Brian Flatley Peter Malone Rainer Cramer 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(5):940-949
Matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry (MS) is a highly versatile and sensitive analytical technique, which is known for its soft ionisation of biomolecules such as peptides and proteins. Generally, MALDI MS analysis requires little sample preparation, and in some cases like MS profiling it can be automated through the use of robotic liquid-handling systems. For more than a decade now, MALDI MS has been extensively utilised in the search for biomarkers that could aid clinicians in diagnosis, prognosis, and treatment decision making. This review examines the various MALDI-based MS techniques like MS imaging, MS profiling and proteomics in-depth analysis where MALDI MS follows fractionation and separation methods such as gel electrophoresis, and how these have contributed to prostate cancer biomarker research. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge. 相似文献
73.
Extracellular invertase is an essential component of cytokinin-mediated delay of senescence 总被引:24,自引:0,他引:24 下载免费PDF全文
Balibrea Lara ME Gonzalez Garcia MC Fatima T Ehness R Lee TK Proels R Tanner W Roitsch T 《The Plant cell》2004,16(5):1276-1287
Leaf senescence is the final stage of leaf development in which the nutrients invested in the leaf are remobilized to other parts of the plant. Whereas senescence is accompanied by a decline in leaf cytokinin content, exogenous application of cytokinins or an increase of the endogenous concentration delays senescence and causes nutrient mobilization. The finding that extracellular invertase and hexose transporters, as the functionally linked enzymes of an apolasmic phloem unloading pathway, are coinduced by cytokinins suggested that delay of senescence is mediated via an effect on source-sink relations. This hypothesis was further substantiated in this study by the finding that delay of senescence in transgenic tobacco (Nicotiana tabacum) plants with autoregulated cytokinin production correlates with an elevated extracellular invertase activity. The finding that the expression of an extracellular invertase under control of the senescence-induced SAG12 promoter results in a delay of senescence demonstrates that effect of cytokinins may be substituted by these metabolic enzymes. The observation that an increase in extracellular invertase is sufficient to delay leaf senescence was further verified by a complementing functional approach. Localized induction of an extracellular invertase under control of a chemically inducible promoter resulted in ectopic delay of senescence, resembling the naturally occurring green islands in autumn leaves. To establish a causal relationship between cytokinins and extracellular invertase for the delay of senescence, transgenic plants were generated that allowed inhibition of extracellular invertase in the presence of cytokinins. For this purpose, an invertase inhibitor was expressed under control of a cytokinin-inducible promoter. It has been shown that senescence is not any more delayed by cytokinin when the expression of the invertase inhibitor is elevated. This finding demonstrates that extracellular invertase is required for the delay of senescence by cytokinins and that it is a key element of the underlying molecular mechanism. 相似文献
74.
Tibor Harrach Klaus Eckert Kai Schulze-Forster Rolf Nuck Detlef Grunow H. Rainer Maurer 《Journal of Protein Chemistry》1995,14(1):41-52
Crude bromelain extracts from pineapple stems (Ananas comosus) were fractionated by two-step FPLC-cation-exchange chromatography. At least eight basic proteolytically active components were detected. The two main components F4 and F5 together with the most active proteinase fraction F9 were characterized by SDS-PAGE, mass spectroscopy, multizonal cathodal electrophoresis, partial amino acid sequence, and monosaccharide composition analysis. F9 amounts to about 2% of the total protein and has a 15 times higher specific activity against the substratel-pyroglutamyl-l-phenylanalyl-l-leucine-p-nitroanilide (PFLNA) than the main component F4. The molecular masses of F4, F5, and F9 were determined to 24,397, 24,472, and 23,427, respectively, by mass spectroscopy. Partial N-terminal amino acid sequence analysis (20 amino acids) revealed that F9 differs from the determined sequence of F4 and F5 by an exchange at position 10 (tyrosineserine) and position 20 (asparagine glycine). F4 and F5 contained fucose, N-acetylglucosamine, xylose, and mannose in ratio of 1.02.01.02.0, but only 50% of the proteins seem to be glycosylated, whereas F9 was found to be unglycosylated. Polyclonal antibodies (IgG) against F9 detected F4 and F5 with tenfold reduced reactivity. ThepH optimum of F4 and F5 was betweenpH4.0 and 4.5 and for F9 close to neutralpH. The kinetic parameters for PFLNA hydrolysis were similar for F4 (K
m 2.30 mM,k
cat 0.87 sec–1 and F5 (K
m 2.42 mM,k
cat 0.68 sec–1), and differed greatly from F9 (K
m 0.40 mM,k
cat 3.94 sec–1).Dedicated to H. Tschesche, Bielefeld, Germany, on behalf of his 60th anniversary. 相似文献
75.
Rainer W. Scora Berthold O. Bergh J. Anthony Hopfinger 《Biochemical Systematics and Ecology》1975,3(4):215-218
The normal-alkane range in leaf cuticular waxes from 22 Persea species and cultivars and from the closely related genus Beilschmiedia was C23 H48 to C35, H72; alkanes with an odd number of carbon atoms predominated, C33 H68 usually constituting about half of the total wax. The alkane profiles gave good agreement with established taxonomy. Beilschmiedia showed an alkane distribution quite different from that of the Persea taxa. Amongst Persea species, the geographical and phylogenetic distinctiveness of P. indica and P. donnell-smithii were reflected in the distinctiveness of their alkanes. Within the subgenus Persea. the morphologically most distinct entity. P. schiedeana, also had a distinct alkane profile. Cultivars of hybrid origin indicated in their alkane proportions pronounced gene interaction. 相似文献
76.
Plant-based production of biopharmaceuticals 总被引:15,自引:0,他引:15
Fischer R Stoger E Schillberg S Christou P Twyman RM 《Current opinion in plant biology》2004,7(2):152-158
Plants are now gaining widespread acceptance as a general platform for the large-scale production of recombinant proteins. The first plant-derived recombinant pharmaceutical proteins are reaching the final stages of clinical evaluation, and many more are in the development pipeline. Over the past two years, there have been some notable technological advances in this flourishing area of applied biotechnology, as shown by the continuing commercial development of novel plant-based expression platforms. There has also been significant success in tackling some of the limitations of plant bioreactors, such as low yields and inconsistent product quality, that have limited the approval of plant-derived pharmaceuticals. 相似文献
77.
Stefan Kunz Marianne Spirig Claudia Ginsburg Andrea Buchstaller Philipp Berger Rainer Lanz Christoph Rader Lorenz Vogt Beat Kunz Peter Sonderegger 《The Journal of cell biology》1998,143(6):1673-1690
Neural cell adhesion molecules composed of immunoglobulin and fibronectin type III-like domains have been implicated in cell adhesion, neurite outgrowth, and fasciculation. Axonin-1 and Ng cell adhesion molecule (NgCAM), two molecules with predominantly axonal expression exhibit homophilic interactions across the extracellular space (axonin- 1/axonin-1 and NgCAM/NgCAM) and a heterophilic interaction (axonin-1–NgCAM) that occurs exclusively in the plane of the same membrane (cis-interaction). Using domain deletion mutants we localized the NgCAM homophilic binding in the Ig domains 1-4 whereas heterophilic binding to axonin-1 was localized in the Ig domains 2-4 and the third FnIII domain. The NgCAM–NgCAM interaction could be established simultaneously with the axonin-1–NgCAM interaction. In contrast, the axonin-1–NgCAM interaction excluded axonin-1/axonin-1 binding. These results and the examination of the coclustering of axonin-1 and NgCAM at cell contacts, suggest that intercellular contact is mediated by a symmetric axonin-12/NgCAM2 tetramer, in which homophilic NgCAM binding across the extracellular space occurs simultaneously with a cis-heterophilic interaction of axonin-1 and NgCAM. The enhanced neurite fasciculation after overexpression of NgCAM by adenoviral vectors indicates that NgCAM is the limiting component for the formation of the axonin-12/NgCAM2 complexes and, thus, neurite fasciculation in DRG neurons. 相似文献
78.
Although synaptic functions of ionotropic glutamate receptors in the olfactory bulb have been studied in vitro, their roles in pattern processing in the intact system remain controversial. We therefore examined the functions of ionotropic glutamate receptors during odor processing in the intact olfactory bulb of zebrafish using pharmacological manipulations. Odor responses of mitral cells and interneurons were recorded by electrophysiology and 2-photon Ca(2+) imaging. The combined blockade of AMPA/kainate and NMDA receptors abolished odor-evoked excitation of mitral cells. The blockade of AMPA/kainate receptors alone, in contrast, increased the mean response of mitral cells and decreased the mean response of interneurons. The blockade of NMDA receptors caused little or no change in the mean responses of mitral cells and interneurons. However, antagonists of both receptor types had diverse effects on the magnitude and time course of individual mitral cell and interneuron responses and, thus, changed spatio-temporal activity patterns across neuronal populations. Oscillatory synchronization was abolished or reduced by AMPA/kainate and NMDA receptor antagonists, respectively. These results indicate that (1) interneuron responses depend mainly on AMPA/kainate receptor input during an odor response, (2) interactions among mitral cells and interneurons regulate the total olfactory bulb output activity, (3) AMPA/kainate receptors participate in the synchronization of odor-dependent neuronal ensembles, and (4) ionotropic glutamate receptor-containing synaptic circuits shape odor-specific patterns of olfactory bulb output activity. These mechanisms are likely to be important for the processing of odor-encoding activity patterns in the olfactory bulb. 相似文献
79.
Developmental changes of nerve growth factor and its mRNA in the rat hippocampus: Comparison with choline acetyltransferase 总被引:4,自引:0,他引:4
Georg Auburger Rolf Heumann Rainer Hellweg Sigrun Korsching Hans Thoenen 《Developmental biology》1987,120(2):322-328
Previous experiments have demonstrated that in the septo-hippocampal system choline acetyltransferase (ChAT) is induced by nerve growth factor (NGF) (Gnahn et al. (1983) Dev. Brain Res. 9, 45-52) and that hippocampal NGF and mRNANGF levels are correlated with the density of cholinergic innervation (Korsching et al. (1985) EMBO J. 4, 1389-1393). In the present investigation we have compared the developmental changes of ChAT, NGF, and mRNANGF levels in this system. During the postnatal development of the hippocampus the time courses of NGF and ChAT were well correlated including the most rapid increase between P12 and P14. This increase in hippocampal NGF was preceded by a corresponding increase in mRNANGF. The developmental changes in hippocampal NGF levels were also closely reflected by corresponding changes in the septum. This, together with previous observations (Korsching et al., 1985) that the adult septum, in spite of relatively high NGF levels, does not contain measurable quantities of mRNANGF, suggests that the NGF levels in the septum are determined by the quantity of NGF transported retrogradely from the field of innervation rather than by local synthesis. During the prenatal period hippocampal NGF levels were relatively high, whereas the mRNANGF was below the level of detection. Since the ingrowth of septal fibers, and with that also the removal of NGF by retrograde transport, begins around birth, the relatively high prenatal NGF levels probably result from an accumulation produced by a small copy number of mRNANGF prior to the removal of NGF by retrograde axonal transport. It is concluded that the correlation of the developmental changes in NGF and mRNANGF with the ChAT activity in the hippocampus further supports the concept of a physiological role of NGF in the central nervous system. 相似文献
80.
Nitrous oxide and methane fluxes of a pristine slope mire in the German National Park Harz Mountains
Nadine Tauchnitz Rainer Brumme Sabine Bernsdorf Ralph Meissner 《Plant and Soil》2008,303(1-2):131-138
Pristine peatlands covered by Histosols (bogs and fens) with high water table and a restricted oxygen (O2) availability are known to have low emissions of nitrous oxide (N2O) but may be a significant source for atmospheric methane (CH4) which are both important greenhouse gases. For the first time N2O and CH4 fluxes of a pristine slope mire in the German Harz Mountains have been monitored. Previously reported peatlands are characterised
by anaerobic conditions due to high water table levels. Slope mires monitored here receive O2 through slope water inflow. Gas fluxes have been monitored deploying closed chamber method on a central non-forested area
and a forested area at the periphery of the slope mire. By means of groundwater piezometers water table levels, ammonium and
nitrate contents as well as hydro-chemical variables like oxygen content and redox potential of the mire pore water have been
concurrently measured with trace gas fluxes at both monitoring sites of the slope mire. The slope mire took up small amounts
of atmospheric methane at a rate of −0.02 ± 0.01 kg C ha−1 year−1 revealing no significant difference between the forested and non-forested site. Higher uptake rates were observed during
low water table level. In contrast to pristine peatlands influx of oxygen containing pore water into slope mire does limit
reduction processes and resultant CH4 emission. N2O fluxes of the forested and non-forested sites of the slope mire did not differ and amounted to 0.25 ± 0.44 kg N ha−1 year−1. Higher emissions were observed at low water table levels and during thawing periods. In spite of favourable conditions N2O fluxes of the slope mire have been comparable to those of pristine peatlands. 相似文献