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941.
942.
Marc Bruckskotten Mario Looso Franz Cemiĉ Anne Konzer Jürgen Hemberger Marcus Krüger Thomas Braun 《BMC bioinformatics》2010,11(1):336
Background
Several tools have been developed to explore and search Gene Ontology (GO) databases allowing efficient GO enrichment analysis and GO tree visualization. Nevertheless, identification of highly specific GO-terms in complex data sets is relatively complicated and the display of GO term assignments and GO enrichment analysis by simple tables or pie charts is not optimal. Valuable information such as the hierarchical position of a single GO term within the GO tree (topological ordering), or enrichment within a complex set of biological experiments is not displayed. Pie charts based on GO tree levels are, themselves, one-dimensional graphs, which cannot properly or efficiently represent the hierarchical specificity for the biological system being studied. 相似文献943.
944.
Iron is required as an element to sustain life in all eukaryotes and most bacteria. Although several bacterial iron acquisition strategies have been well explored, little is known about the intracellular trafficking pathways of iron and its entry into the systems for co-factor biogenesis. In this study, we investigated the iron-dependent process of heme maturation in Bacillus subtilis and present, for the first time, structural evidence for the physical interaction of a frataxin homologue (Fra), which is suggested to act as a regulatory component as well as an iron chaperone in different cellular pathways, and a ferrochelatase (HemH), which catalyses the final step of heme b biogenesis. Specific interaction between Fra and HemH was observed upon co-purification from crude cell lysates and, further, by using the recombinant proteins for analytical size-exclusion chromatography. Hydrogen–deuterium exchange experiments identified the landscape of the Fra/HemH interaction interface and revealed Fra as a specific ferrous iron donor for the ferrochelatase HemH. The functional utilisation of the in vitro-generated heme b co-factor upon Fra-mediated iron transfer was confirmed by using the B. subtilis nitric oxide synthase bsNos as a metabolic target enzyme. Complementary mutational analyses confirmed that Fra acts as an essential component for maturation and subsequent targeting of the heme b co-factor, hence representing a key player in the iron-dependent physiology of B. subtilis. 相似文献
945.
946.
Annarita Falanga Rossella Tarallo Thomas Carberry Massimiliano Galdiero Marcus Weck Stefania Galdiero 《PloS one》2014,9(11)
We have demonstrated that amide-based dendrimers functionalized with the membrane-interacting peptide gH625 derived from the herpes simplex virus type 1 (HSV-1) envelope glycoprotein H enter cells mainly through a non-active translocation mechanism. Herein, we investigate the interaction between the peptide-functionalized dendrimer and liposomes composed of PC/Chol using fluorescence spectroscopy, isothermal titration calorimetry, and surface plasmon resonance to get insights into the mechanism of internalization. The affinity for the membrane bilayer is very high and the interaction between the peptide-dendrimer and liposomes took place without evidence of pore formation. These results suggest that the presented peptidodendrimeric scaffold may be a promising material for efficient drug delivery. 相似文献
947.
948.
An optimal control model for maximum-height human jumping 总被引:11,自引:0,他引:11
Marcus G. Pandy Felix E. Zajac Eunsup Sim William S. Levine 《Journal of biomechanics》1990,23(12):1185-1198
To understand how intermuscular control, inertial interactions among body segments, and musculotendon dynamics coordinate human movement, we have chosen to study maximum-height jumping. Because this activity presents a relatively unambiguous performance criterion, it fits well into the framework of optimal control theory. The human body is modeled as a four-segment, planar, articulated linkage, with adjacent links joined together by frictionless revolutes. Driving the skeletal system are eight musculotendon actuators, each muscle modeled as a three-element, lumped-parameter entity, in series with tendon. Tendon is assumed to be elastic, and its properties are defined by a stress-strain curve. The mechanical behavior of muscle is described by a Hill-type contractile element, including both series and parallel elasticity. Driving the musculotendon model is a first-order representation of excitation-contraction (activation) dynamics. The optimal control problem is to maximize the height reached by the center of mass of the body subject to body-segmental, musculotendon, and activation dynamics, a zero vertical ground reaction force at lift-off, and constraints which limit the magnitude of the incoming neural control signals to lie between zero (no excitation) and one (full excitation). A computational solution to this problem was found on the basis of a Mayne-Polak dynamic optimization algorithm. Qualitative comparisons between the predictions of the model and previously reported experimental findings indicate that the model reproduces the major features of a maximum-height squat jump (i.e. limb-segmental angular displacements, vertical and horizontal ground reaction forces, sequence of muscular activity, overall jump height, and final lift-off time). 相似文献
949.
Karl Sperling Bat -Sheva Kerem Ruth Goitein Veronika Kottusch Howard Cedar Menashe Marcus 《Chromosoma》1985,93(1):38-42
In situ nick translation allows the detection of DNase I sensitive and insensitive regions in fixed mammalian mitotic chromosomes. We have determined the difference in DNase I sensitivity between the active and inactive X chromosomes inMicrotus agrestis (rodent) cells, along both their euchromatic and constitutive heterochromatic regions. In addition, we analysed the DNase I sensitivity of the constitutive heterochromatic regions in mouse chromosomes. InMicrotus agrestis female cells the active X chromosome is sensitive to DNase I along its euchromatic region while the inactive X chromosome is insensitive except for an early replicating region at its distal end. The late replicating constitutive heterochromatic regions, however, in both the active and inactive X chromosome are sensitive to DNase I. In mouse cells on the other hand, the constitutive heterochromatin is insensitive to DNase I both in mitotic chromosomes and interphase nuclei. 相似文献
950.
DNA hypomethylation causes an increase in DNase-I sensitivity and an advance in the time of replication of the entire inactive X chromosome 总被引:1,自引:0,他引:1
Summary We have examined the effect of 5-azacytidine (5-aza-C) induced hypomethylation of DNA on the time of replication and DNase I sensitivity of the X chromosomes of female Gerbillus gerbillus (rodent) lung fibroblast cells. Using in situ nick translation to visualise the potential state of activity of large regions of metaphase chromosomes we show that 5-aza-C causes a dramatic increase in the DNase-I sensitivity of the entire inactive X chromosome of female G. gerbillus cells and this increase in nuclease sensitivity correlates with a large shift in the time of replication of the inactive X chromosome from late S phase to early S phase. These effects of 5-aza-C on the inactive X chromosome are associated with a 15% decrease in DNA methylation. Our results indicate that DNA methylation concomitantly affects both the time of replication and the chromatin conformation of the inactive X chromosome. 相似文献