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Specific interaction of peptides with nucleic acids 总被引:5,自引:0,他引:5
215.
Fagerburg MV Schauer GD Thickman KR Bianco PR Khan SA Leuba SH Anand SP 《Nucleic acids research》2012,40(17):8416-8424
The essential DNA helicase, PcrA, regulates recombination by displacing the recombinase RecA from the DNA. The nucleotide-bound state of RecA determines the stability of its nucleoprotein filaments. Using single-molecule fluorescence approaches, we demonstrate that RecA displacement by a translocating PcrA requires the ATPase activity of the recombinase. We also show that in a 'head-on collision' between a polymerizing RecA filament and a translocating PcrA, the RecA K72R ATPase mutant, but not wild-type RecA, arrests helicase translocation. Our findings demonstrate that translocation of PcrA is not sufficient to displace RecA from the DNA and assigns an essential role for the ATPase activity of RecA in helicase-mediated disruption of its filaments. 相似文献
216.
Bradly T. Stone Jian-You Lin Abuzar Mahmood Alden J. Sanford Donald B. Katz 《PLoS biology》2022,20(7)
Gustatory cortex (GC), a structure deeply involved in the making of consumption decisions, presumably performs this function by integrating information about taste, experiences, and internal states related to the animal’s health, such as illness. Here, we investigated this assertion, examining whether illness is represented in GC activity, and how this representation impacts taste responses and behavior. We recorded GC single-neuron activity and local field potentials (LFPs) from healthy rats and rats made ill (via LiCl injection). We show (consistent with the extant literature) that the onset of illness-related behaviors arises contemporaneously with alterations in 7 to 12 Hz LFP power at approximately 12 min following injection. This process was accompanied by reductions in single-neuron taste response magnitudes and discriminability, and with enhancements in palatability-relatedness—a result reflecting the collapse of responses toward a simple “good-bad” code visible in the entire sample, but focused on a specific subset of GC neurons. Overall, our data show that a state (illness) that profoundly reduces consumption changes basic properties of the sensory cortical response to tastes, in a manner that can easily explain illness’ impact on consumption.Sickness is an internal state that impacts consumption, and so could be expected to influence the neural processing of tastes. This study shows that onset of illness changes basic properties of gustatory cortical network processing and taste responses, such that activity comes more purely to reflect the "goodness" or "badness" of tastes. 相似文献
217.
Expression of the human chondrocyte phenotype in vitro 总被引:9,自引:0,他引:9
Amy Lynn Aulthouse Michael Beck Edward Griffey Julie Sanford Karen Arden Mirta A. Machado William A. Horton 《In vitro cellular & developmental biology. Plant》1989,25(7):659-668
Summary We report a culture scheme in which human epiphyseal chondrocytes lose their differentiated phenotype in monolayer and subsequently
reexpress the phenotype in an agarose gel. The scheme is based on a method using rabbit chondrocytes. Culture in monolayer
allowed small quantities of cells to be amplified and provided a starting point to study expression of the differentiated
human chondrocyte phenotype. The cells cultured in monolayer produced type I procollagen, fibronectin, and small noncartilaginous
proteoglycans. Subsequent culture in agarose was associated with the acquisition of typical chondrocyte ultrastructural features
and the synthesis of type II collagen and cartilage-specific proteoglycans. The switch from the nonchondrocyte to the differented
chondrocyte phenotype occurred under these conditions between 1 and 2 wk of agarose culture and was not necessarily homogeneous
throughout a culture. This culture technique will facilitate direct investigation of human disorders of cartilage that have
been addressed in the past by alternative approaches.
This research is supported in part by research grants from the National Institutes of Health, (HD 20691) Bethesda, MD, and
Shriners of North America (15953). 相似文献
218.
Sanford D. Eigenbrode Jennifer E. Andreas Michael G. Cripps Hongjian Ding Russell C. Biggam Mark Schwarzländer 《Biological invasions》2008,10(8):1373-1379
The ‘evolution of increased competitive ability’ (EICA) hypothesis is an extension of optimal defense theory and predicts
that reduced pressure from insect herbivores in the introduced range results in evolution of reduced defenses in invading
plant populations, allowing greater allocation of resources to competitive traits such as growth rate and reproduction. The
EICA hypothesis considered levels of defensive chemistry to be fixed within a particular genotype. In this paper, we propose
that if herbivory is reduced in the introduced range, but chemical defenses are inducible in response to herbivory, evolution of reduced defenses and any associated increase competitive ability should not occur.
Rather, mean induced and constitutive levels of induced defenses should be similar in introduced and native ranges, but the
variance about mean induced levels should be greater in the introduced range. This is predicted because induced levels will
occur less frequently in the introduced range where herbivory is reduced, thereby insulating these levels from the stabilizing
selection expected in the native range where induced levels occur more frequently. We conducted a preliminary study to examine
this by comparing constitutive and induced concentrations of total pyrrolizidine alkaloids (PAs) from native (European) and
introduced (western North America) populations of Cynoglossum officinale L. The mean constitutive and induced concentrations of PAs did not differ between continents, but the variability of the induced
concentrations was significantly greater for plants from the introduced range. Although our study with C. officinale is provisional due to a small sample size, it supports our predictions for evolution of inducible defenses in introduced
ranges where herbivore pressure is reduced. Most chemical defenses in plants have been found to be inducible, so similar patterns
may occur widely. If so, this weakens the generality of EICA’s predictions concerning chemical defenses. The effects of inducible
defenses should be considered in cross-continent comparisons of other invasive plant species. 相似文献
219.
Cammarato A Ahrens CH Alayari NN Qeli E Rucker J Reedy MC Zmasek CM Gucek M Cole RN Van Eyk JE Bodmer R O'Rourke B Bernstein SI Foster DB 《PloS one》2011,6(4):e18497
Drosophila melanogaster is emerging as a powerful model system for the study of cardiac disease. Establishing peptide and protein maps of the Drosophila heart is central to implementation of protein network studies that will allow us to assess the hallmarks of Drosophila heart pathogenesis and gauge the degree of conservation with human disease mechanisms on a systems level. Using a gel-LC-MS/MS approach, we identified 1228 protein clusters from 145 dissected adult fly hearts. Contractile, cytostructural and mitochondrial proteins were most abundant consistent with electron micrographs of the Drosophila cardiac tube. Functional/Ontological enrichment analysis further showed that proteins involved in glycolysis, Ca(2+)-binding, redox, and G-protein signaling, among other processes, are also over-represented. Comparison with a mouse heart proteome revealed conservation at the level of molecular function, biological processes and cellular components. The subsisting peptidome encompassed 5169 distinct heart-associated peptides, of which 1293 (25%) had not been identified in a recent Drosophila peptide compendium. PeptideClassifier analysis was further used to map peptides to specific gene-models. 1872 peptides provide valuable information about protein isoform groups whereas a further 3112 uniquely identify specific protein isoforms and may be used as a heart-associated peptide resource for quantitative proteomic approaches based on multiple-reaction monitoring. In summary, identification of excitation-contraction protein landmarks, orthologues of proteins associated with cardiovascular defects, and conservation of protein ontologies, provides testimony to the heart-like character of the Drosophila cardiac tube and to the utility of proteomics as a complement to the power of genetics in this growing model of human heart disease. 相似文献
220.