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271.
Reactive oxygen species (ROS) production by an NADPH oxidase (NOX) encoded by AtrbohC/RHD2 is required for root hair growth in Arabidopsis thaliana. ROP (RHO of plants) GTPases are also required for normal root hair growth and have been proposed to regulate ROS production in plants. Therefore, the role of ROP GTPase in NOX-dependent ROS formation by root hairs was investigated. Plants overexpressing wild-type ROP2 (ROP2 OX), constitutively active (CA-rop2), or dominant negative (DN-rop2) rop2 mutant proteins were used. Superoxide formation by root hairs was detected by superoxide dismutase-sensitive nitroblue tetrazolium reduction, and ROS production in the root hair differentiation zone was detected by dihydrofluorescein diacetate oxidation. Both probes showed that ROS production was increased in ROP2 OX and CA-rop2 plants, and decreased in DN-rop2 plants, relative to wild-type plants. When CA-rop2 was expressed in the NOX loss-of-function rhd2-1 mutant, ROS formation and root hair growth were impaired, suggesting that RHD2 is required for this ROP2-dependent ROS formation. 相似文献
272.
Pleurocidin is an antimicrobial peptide that was isolated from the mucus membranes of winter flounder (Pseudopleuronectes americanus) and contributes to the initial stages of defense against bacterial infection. From NMR structural studies with the uniformly (15)N-labeled peptide, a structure of pleurocidin was determined to be in a random coil conformation in aqueous solution whereas it assumes an alpha-helical structure in TFE and in dodecylphosphocholine (DPC) micelles. From (15)N relaxation studies, the helix is a rigid structure in the membrane-mimicking environment. Strong NOESY cross-peaks from the pleurocidin to the aliphatic chain on DPC confirm that pleurocidin is contained within the DPC micelle and not associated with the surface of the micelle. From diffusion studies it was determined that each micelle contains at least two pleurocidin molecules. 相似文献
273.
Van VQ Darwiche J Raymond M Lesage S Bouguermouh S Rubio M Sarfati M 《Journal of immunology (Baltimore, Md. : 1950)》2008,181(8):5204-5208
Peripheral CD103(+)Foxp3(+) regulatory T cells (Tregs) can develop both from conventional naive T cells upon cognate Ag delivery under tolerogenic conditions and from thymic-derived, expanded/differentiated natural Tregs. We here show that CD47 expression, a marker of self on hematopoietic cells, selectively regulated CD103(+)Foxp3(+) Treg homeostasis at the steady state. First, the proportion of effector/memory-like (CD44(high)CD62L(low)) CD103(+)Foxp3(+) Tregs rapidly augmented with age in CD47-deficient mice (CD47(-/-)) as compared with age-matched control littermates. Yet, the percentage of quiescent (CD44(low)CD62L(high)) CD103(-)Foxp3(+) Tregs remained stable. Second, the increased proliferation rate (BrdU incorporation) observed within the CD47(-/-)Foxp3(+) Treg subpopulation was restricted to those Tregs expressing CD103. Third, CD47(-/-) Tregs maintained a normal suppressive function in vitro and in vivo and their increased proportion in old mice led to a decline of Ag-specific T cell responses. Thus, sustained CD47 expression throughout life is critical to avoid an excessive expansion of CD103(+) Tregs that may overwhelmingly inhibit Ag-specific T cell responses. 相似文献
274.
Azita Monazzam Pasha Razifar Martin Simonsson Fredrik Qvarnstr?m Raymond Josephsson Carl Blomqvist Bengt L?ngstr?m Mats Bergstr?m 《Cancer cell international》2006,6(1):6
Background
In order to explore a pre-clinical method to evaluate if [18F]FDG is valid for monitoring early response, we investigated the uptake of FDG in Multicellular tumour spheroids (MTS) without and with treatment with five routinely used chemotherapy agents in breast cancer. 相似文献275.
Temple CL Tse R Bettger-Hahn M MacDermid J Gan BS Ross DC 《Plastic and reconstructive surgery》2006,117(7):2119-27; discussion 2128-30
276.
William A Cafruny Richard G Duman Grace HW Wong Suleman Said Pam Ward-Demo Raymond RR Rowland Eric A Nelson 《Virology journal》2006,3(1):1-17
Background
Porcine reproductive and respiratory syndrome virus (PRRSV) is the etiologic agent of PRRS, causing widespread chronic infections which are largely uncontrolled by currently available vaccines or other antiviral measures. Cultured monkey kidney (MARC-145) cells provide an important tool for the study of PRRSV replication. For the present study, flow cytometric and fluorescence antibody (FA) analyses of PRRSV infection of cultured MARC-145 cells were carried out in experiments designed to clarify viral dynamics and the mechanism of viral spread. The roles of viral permissiveness and the cytoskeleton in PRRSV infection and transmission were examined in conjunction with antiviral and cytotoxic drugs.Results
Flow cytometric and FA analyses of PRRSV antigen expression revealed distinct primary and secondary phases of MARC-145 cell infection. PRRSV antigen was randomly expressed in a few percent of cells during the primary phase of infection (up to about 20–22 h p.i.), but the logarithmic infection phase (days 2–3 p.i.), was characterized by secondary spread to clusters of infected cells. The formation of secondary clusters of PRRSV-infected cells preceded the development of CPE in MARC-145 cells, and both primary and secondary PRRSV infection were inhibited by colchicine and cytochalasin D, demonstrating a critical role of the cytoskeleton in viral permissiveness as well as cell-to-cell transmission from a subpopulation of cells permissive for free virus to secondary targets. Cellular expression of actin also appeared to correlate with PRRSV resistance, suggesting a second role of the actin cytoskeleton as a potential barrier to cell-to-cell transmission. PRRSV infection and cell-to-cell transmission were efficiently suppressed by interferon-γ (IFN-γ), as well as the more-potent experimental antiviral agent AK-2.Conclusion
The results demonstrate two distinct mechanisms of PRRSV infection: primary infection of a relatively small subpopulation of innately PRRSV-permissive cells, and secondary cell-to-cell transmission to contiguous cells which appear non-permissive to free virus. The results also indicate that an intact cytoskeleton is critical for PRRSV infection, and that viral permissiveness is a highly efficient drug target to control PRRSV infection. The data from this experimental system have important implications for the mechanisms of PRRSV persistence and pathology, as well as for a better understanding of arterivirus regulation. 相似文献277.
Background
Recent studies suggest that anhedonia, an inability to experience pleasure, can be measured as an enduring trait in non-clinical samples. In order to examine trait anhedonia in a non-clinical sample, we examined the properties of a range of widely used questionnaires capturing anhedonia.Methods
887 young adults were recruited from colleges. All of them were administered a set of checklists, including Chapman Scale for Social Anhedonia (CRSAS) and the Chapman Scale for Physical Anhedonia Scale (CPAS), The Temporal Experience of Pleasure Scale(TEPS), and The Schizotypal Personality Questionnaire (SPQ).Results
Males showed significantly higher level of physical (F = 5.09, p<0.001) and social (F = 4.38, p<0.005) anhedonia than females. As expected, individuals with schizotypal personality features also demonstrated significantly higher scores of physical (t = 3.81, p<0.001) and social (t = 7.33, p<0.001) trait anhedonia than individuals without SPD features, but no difference on self-report anticipatory and consummatory pleasure experience.Conclusions
Concerning the comparison on each item of physical and social anhedonia, the results indicated that individuals with SPD feature exhibited higher than individuals without SPD features on more items of social anhedonia than physical anhedonia scale. These preliminary findings suggested that trait anhedonia can be identified a non-clinical sample. Exploring the demographic and clinical correlates of trait anhedonia in the general population may provide clues to the pathogenesis of psychotic disorder. 相似文献278.
Collier BA Groce JE Morrison ML Newnam JC Campomizzi AJ Farrell SL Mathewson HA Snelgrove RT Carroll RJ Wilkins RN 《Diversity & distributions》2012,18(2):158-167
AIM: Our objective was to identify the distribution of the endangered golden-cheeked warbler (Setophaga chrysoparia) in fragmented oak-juniper woodlands by applying a geoadditive semiparametric occupancy model to better assist decision-makers in identifying suitable habitat across the species breeding range on which conservation or mitigation activities can be focused and thus prioritize management and conservation planning. LOCATION: Texas, USA. METHODS: We used repeated double-observer detection/non-detection surveys of randomly selected (n = 287) patches of potential habitat to evaluate warbler patch-scale presence across the species breeding range. We used a geoadditive semiparametric occupancy model with remotely sensed habitat metrics (patch size and landscape composition) to predict patch-scale occupancy of golden-cheeked warblers in the fragmented oak-juniper woodlands of central Texas, USA. RESULTS: Our spatially explicit model indicated that golden-cheeked warbler patch occupancy declined from south to north within the breeding range concomitant with reductions in the availability of large habitat patches. We found that 59% of woodland patches, primarily in the northern and central portions of the warbler's range, were predicted to have occupancy probabilities ≤0.10 with only 3% of patches predicted to have occupancy probabilities >0.90. Our model exhibited high prediction accuracy (area under curve = 0.91) when validated using independently collected warbler occurrence data. MAIN CONCLUSIONS: We have identified a distinct spatial occurrence gradient for golden-cheeked warblers as well as a relationship between two measurable landscape characteristics. Because habitat-occupancy relationships were key drivers of our model, our results can be used to identify potential areas where conservation actions supporting habitat mitigation can occur and identify areas where conservation of future potential habitat is possible. Additionally, our results can be used to focus resources on maintenance and creation of patches that are more likely to harbour viable local warbler populations. 相似文献
279.
In this study, we present multiple lines of evidence to support a critical role for heparin-bound EGF (epidermal growth factor)-like growth factor (HB-EGF) and tumor necrosis factor-alpha-converting enzyme (TACE) (ADAM17) in the transactivation of EGF receptor (EGFR), ERK phosphorylation, and cellular proliferation induced by the 5-HT(2A) receptor in renal mesangial cells. 5-hydroxy-tryptamine (5-HT) resulted in rapid activation of TACE, HB-EGF shedding, EGFR activation, ERK phosphorylation, and longer term increases in DNA content in mesangial cells. ERK phosphorylation was attenuated by 1) neutralizing EGFR antibodies and the EGFR kinase inhibitor, AG1478, 2) neutralizing HB-EGF, but not amphiregulin, antibodies, heparin, or CM197, and 3) pharmacological inhibitors of matrix-degrading metalloproteinases or TACE small interfering RNA. Exogenously administered HB-EGF stimulated ERK phosphorylation. Additionally, TACE was co-immunoprecipitated with HB-EGF. Small interfering RNA against TACE also blocked 5-HT-induced increases in ERK phosphorylation, HB-EGF shedding, and DNA content. In aggregate, this work supports a pathway map that can be depicted as follows: 5-HT --> 5-HT(2A) receptor --> TACE --> HB-EGF shedding --> EGFR --> ERK --> increased DNA content. To our knowledge, this is the first time that TACE has been implicated in 5-HT-induced EGFR transactivation or in proliferation induced by a G protein-coupled receptor in native cells in culture. 相似文献
280.