排序方式: 共有114条查询结果,搜索用时 0 毫秒
1.
Kotakonda Arunasri Mohammed Adil Katari Venu Charan Chatterjee Suvro Seerapu Himabindu Reddy Sisinthy Shivaji 《PloS one》2013,8(3)
This study demonstrates the effects of simulated microgravity on E. coli K 12 MG1655 grown on LB medium supplemented with glycerol. Global gene expression analysis indicated that the expressions of hundred genes were significantly altered in simulated microgravity conditions compared to that of normal gravity conditions. Under these conditions genes coding for adaptation to stress are up regulated (sufE and ssrA) and simultaneously genes coding for membrane transporters (ompC, exbB, actP, mgtA, cysW and nikB) and carbohydrate catabolic processes (ldcC, ptsA, rhaD and rhaS) are down regulated. The enhanced growth in simulated gravity conditions may be because of the adequate supply of energy/reducing equivalents and up regulation of genes involved in DNA replication (srmB) and repression of the genes encoding for nucleoside metabolism (dfp, pyrD and spoT). In addition, E. coli cultured in LB medium supplemented with glycerol (so as to protect the cells from freezing temperatures) do not exhibit multiple stress responses that are normally observed when cells are exposed to microgravity in LB medium without glycerol. 相似文献
2.
J?rg Lesting Thiemo Daldrup Venu Narayanan Christian Himpe Thomas Seidenbecher Hans-Christian Pape 《PloS one》2013,8(10)
Theta oscillations are considered crucial mechanisms in neuronal communication across brain areas, required for consolidation and retrieval of fear memories. One form of inhibitory learning allowing adaptive control of fear memory is extinction, a deficit of which leads to maladaptive fear expression potentially leading to anxiety disorders. Behavioral responses after extinction training are thought to reflect a balance of recall from extinction memory and initial fear memory traces. Therefore, we hypothesized that the initial fear memory circuits impact behavioral fear after extinction, and more specifically, that the dynamics of theta synchrony in these pathways signal the individual fear response. Simultaneous multi-channel local field and unit recordings were obtained from the infralimbic prefrontal cortex, the hippocampal CA1 and the lateral amygdala in mice. Data revealed that the pattern of theta coherence and directionality within and across regions correlated with individual behavioral responses. Upon conditioned freezing, units were phase-locked to synchronized theta oscillations in these pathways, characterizing states of fear memory retrieval. When the conditioned stimulus evoked no fear during extinction recall, theta interactions were directional with prefrontal cortical spike firing leading hippocampal and amygdalar theta oscillations. These results indicate that the directional dynamics of theta-entrained activity across these areas guide changes in appraisal of threatening stimuli during fear memory and extinction retrieval. Given that exposure therapy involves procedures and pathways similar to those during extinction of conditioned fear, one therapeutical extension might be useful that imposes artificial theta activity to prefrontal cortical-amygdalo-hippocampal pathways that mimics the directionality signaling successful extinction recall. 相似文献
3.
4.
5.
6.
Orientational order and dynamics of hydration water in a single crystal of bovine pancreatic trypsin inhibitor. 下载免费PDF全文
The orientational order and dynamics of the water molecules in form II crystals of bovine pancreatic trypsin inhibitor (BPTI) are studied by (2)H NMR in the temperature range 6-50 degrees C. From the orientation dependence of the single crystal quadrupole splitting and linewidth, the principal components of the motionally averaged quadrupole interaction tensor and the irreducible linewidth components for the orthorhombic crystal are determined. With the aid of water orientations derived from neutron and x-ray diffraction, it is shown that the NMR data can be accounted for by a small number of highly ordered crystal waters, some of which have residence times in the microsecond range. Most of these specific hydration sites must be located at intermolecular contacts. The surface hydration layer that is also present in dilute solution is likely to be only weakly ordered and would then not contribute significantly to the splitting and linewidth from the protein crystal. To probe water dynamics on shorter time scales, the (2)H longitudinal relaxation dispersion is measured for a polycrystalline BPTI sample. The observed dispersion is dominated by rapidly exchanging deuterons in protein side chains, undergoing restricted rotational motions on a time scale of 10 ns. 相似文献
7.
8.
Miller G Pillarisetty VG Shah AB Lahrs S Xing Z DeMatteo RP 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(6):2875-2885
GM-CSF is critical for dendritic cell (DC) survival and differentiation in vitro. To study its effect on DC development and function in vivo, we used a gene transfer vector to transiently overexpress GM-CSF in mice. We found that up to 24% of splenocytes became CD11c+ and the number of DC increased up to 260-fold to 3 x 10(8) cells. DC numbers remained substantially elevated even 75 days after treatment. The DC population was either CD8alpha+CD4- or CD8alpha-CD4- but not CD8alpha+CD4+ or CD8alpha-CD4+. This differs substantially from subsets recruited in normal or Flt3 ligand-treated mice or using GM-CSF protein injections. GM-CSF-recruited DC secreted extremely high levels of TNF-alpha compared with minimal amounts in DC from normal or Flt3 ligand-treated mice. Recruited DC also produced elevated levels of IL-6 but almost no IFN-gamma. GM-CSF DC had robust immune function compared with controls. They had an increased rate of Ag capture and caused greater allogeneic and Ag-specific T cell stimulation. Furthermore, GM-CSF-recruited DC increased NK cell lytic activity after coculture. The enhanced T cell and NK cell immunostimulation by GM-CSF DC was in part dependent on their secretion of TNF-alpha. Our findings show that GM-CSF can have an important role in DC development and recruitment in vivo and has potential application to immunotherapy in recruiting massive numbers of DC with enhanced ability to activate effector cells. 相似文献
9.
Non-invasive longitudinal detection and evaluation of gene expression in living animals can provide investigators with an understanding of the ontogeny of a gene's biological function(s). Currently, mouse model systems are used to optimize magnetic resonance imaging (MRI), positron emission tomography (PET), single-photon emission computed tomography (SPECT), and optical imaging modalities to detect gene expression and protein function. These molecular imaging strategies are being developed to assess tumor growth and the tumor microenvironment. In addition, pre-labeling of progenitor cells can provide invaluable information about the developmental lineage of stem cells both in organogenesis and tumorigenesis. The feasibility of this approach has been extensively tested by targeting of endogenous tumor cell receptors with labeled ligand (or ligand analog) reporters and targeting enzymes with labeled substrate (or substrate analog). We will primarily discuss MRI, PET, and SPECT imaging of cell surface receptors and the feasibility of non-invasive imaging of gene expression using the tumor microenvironment (e.g., hypoxia) as a conditional regulator of gene expression. 相似文献
10.
Rocco J. LaFaro Suryanarayana Pothula Keshar Paul Kubal Mario Emil Inchiosa Venu M. Pothula Stanley C. Yuan David A. Maerz Lucresia Montes Stephen M. Oleszkiewicz Albert Yusupov Richard Perline Mario Anthony Inchiosa Jr. 《PloS one》2015,10(12)