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121.
Epidemic modeling in complex realities 总被引:1,自引:0,他引:1
122.
Lack of enhanced spinal regeneration in Nogo-deficient mice 总被引:37,自引:0,他引:37
The failure of regeneration of severed axons in the adult mammalian central nervous system is thought to be due partly to the presence of endogenous inhibitors of axon regeneration. The nogo gene encodes three proteins (Nogo-A, -B, and -C) that have been proposed to contribute to this inhibition. To determine whether deletion of nogo enhances regenerative ability, we generated two lines of mutant mice, one lacking Nogo-A and -B but not -C (Nogo-A/B mutant), and one deficient in all three isoforms (Nogo-A/B/C mutant). Although Nogo-A/B-deficient myelin has reduced inhibitory activity in a neurite outgrowth assay in vitro, tracing of corticospinal tract fibers after dorsal hemisection of the spinal cord did not reveal an obvious increase in regeneration or sprouting of these fibers in either mouse line, suggesting that elimination of Nogo alone is not sufficient to induce extensive axon regeneration. 相似文献
123.
Hoggart CJ Chadeau-Hyam M Clark TG Lampariello R Whittaker JC De Iorio M Balding DJ 《Genetics》2007,177(3):1725-1731
Simulation is an invaluable tool for investigating the effects of various population genetics modeling assumptions on resulting patterns of genetic diversity, and for assessing the performance of statistical techniques, for example those designed to detect and measure the genomic effects of selection. It is also used to investigate the effectiveness of various design options for genetic association studies. Backward-in-time simulation methods are computationally efficient and have become widely used since their introduction in the 1980s. The forward-in-time approach has substantial advantages in terms of accuracy and modeling flexibility, but at greater computational cost. We have developed flexible and efficient simulation software and a rescaling technique to aid computational efficiency that together allow the simulation of sequence-level data over large genomic regions in entire diploid populations under various scenarios for demography, mutation, selection, and recombination, the latter including hotspots and gene conversion. Our forward evolution of genomic regions (FREGENE) software is freely available from www.ebi.ac.uk/projects/BARGEN together with an ancillary program to generate phenotype labels, either binary or quantitative. In this article we discuss limitations of coalescent-based simulation, introduce the rescaling technique that makes large-scale forward-in-time simulation feasible, and demonstrate the utility of various features of FREGENE, many not previously available. 相似文献
124.
Kallikrein gene families have been identified previously in genomes of the human, the mouse, and the rat, and individual kallikrein-like genes have been found in many more species. This study presents the in silico identification of kallikrein gene families in the recently sequenced genomes of four additional mammalian species, the chimpanzee, the dog, the pig, and the opossum. Phylogenies were constructed with gene sequences from all seven mammalian families, using Bayesian analysis, which clarified the evolutionary relationships between these genes. Individual gene sequences, as well as concatenated constructs of multiple sequences, were used. Fifteen kallikrein genes were located in the chimpanzee (Pan troglodytes) genome, while only 14 were identified in the canine (Canis familiaris) genome as no orthologue to human KLK3 was found. Thirteen genes were identified from the pig (Sus scrofa) genome, which lacked homologues to KLK2 and KLK3, and 11 genes, orthologous to human KLK5 through KLK15, were found in the opossum (Monodelphis domestica) genome. No kallikrein genes were identified from the available genome sequences of the chicken (Gallus gallus) or African clawed frog (Xenopus tropicalis). Within the family of kallikreins several subfamilies were suggested by phylogenetic analysis. One consisted of KLK4, KLK5, and KLK14; another of KLK9, KLK11, and KLK15; a third of KLK10 and KLK12; a fourth of KLK6 and KLK13; and finally one of KLK8 and the classical kallikreins (KLK1, KLK2, and KLK3). 相似文献
125.
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127.
This paper concerns the 13C NMR signal assignment in the DMSO of a neutral polysaccharide, scleroglucan. The previously proposed chemical structure is confirmed. The 13C NMR spectrum shows that scleroglucan is a regular poly (A, B, C, D) type glucan. The relaxation times of the different series of carbon atoms demonstrate that a single, pendant glucose group is attached to each third monomer along the main chain of what is a β(1 → 3)-glucan. Partial acid hydrolysis gives a spectrum analogous to that of the β(1 → 3)-d-glucan, curdlan, and confirms the structure of the polymer backbone.In aqueous solution, no signal has been obtained due to the existence of a rigid, ordered conformation as demonstrated by optical rotation; in the presence of sodium hydroxide, a conformational transition is produced just as with curdlan. The conclusion is that the behaviour of scleroglucan in solution is similar to that of other β(1 → 3)-d-glucans even though it is more soluble. 相似文献
128.
The anaerobic ammonium oxidation process is a new process for ammonia removal from wastewater. It is also a new microbial
physiology that was previously believed to be impossible. The identification of Candidatus Brocadia anammoxidans and its relatives as the responsible bacteria was only possible with the development of a new experimental
approach. That approach is the focus of this paper. The approach is a modernisation of the Winogradsky/Beyerinck strategy
of selective enrichment and is based on the introduction of the molecular toolbox and modern bioreactor engineering to microbial
ecology. It consists of five steps: (1) postulation of an ecological niche based on thermodynamic considerations and macro-ecological
field data; (2) engineering of this niche into a laboratory bioreactor for enrichment culture; (3) black-box physiological
characterisation of the enrichment culture as a whole; (4) phylogenetic characterisation of the enriched community using molecular
tools; (5) physical separation of the dominant members of the enrichment culture using gradient centrifugation and the identification
of the species of interest in accordance with Koch's postulates; (6) verification of the in situ importance of these species in the actual ecosystems. The power of this approach is illustrated with a case study: the identification
of the planctomycetes responsible for anaerobic ammonium oxidation. We argue that this was impossible using molecular ecology
or conventional ‘cultivation based techniques’ alone. We suggest that the approach might also be used for the microbiological
study of many interesting microbes such as anaerobic methane oxidisers.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
129.
Molecular characterization of the proteinase-encoding gene, prb1, related to mycoparasitism by Trichoderma harzianum 总被引:11,自引:0,他引:11
Roberto A. Geremia Gustavo H. Goldman Dirk Jacobs W. Ardrtes Silvia B. Vila Marc Van Montagu Alfredo Herrera-Estrella 《Molecular microbiology》1993,8(3):603-613
The soil fungus Trichoderma harzianum is a mycoparasitic fungus known for its use as a biocontrol agent of phytopathogenic fungi. Among other factors, Trichoderma produces a series of antibiotics and fungal cell wall-degrading enzymes. These enzymes are believed to play an important role in mycoparasitism. Among the hydrolytic enzymes, we have identified a basic proteinase (Prb1) which is induced by either autoclaved mycelia, fungal cell wall preparation or chitin; however, the induction does not occur in the presence of glucose. The proteinase was purified and biochemically characterized as a serine proteinase of 31 kDa and pl 9.2. Based on the sequence of three internal peptides, synthetic oligonudeotide probes were designed. These probes allowed subsequent isolation of a cDNA and its corresponding genomic clone. The deduced amino acid sequence indicates that the proteinase is synthesized as a pre-proenzyme and allows its classification as a serine proteinase. Northen analysis shows that the induction of this enzyme is due to an increase in the corresponding mRNA level. 相似文献
130.
Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献