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141.
Orna Liarzi Rina Barak Vered Bronner Monica Dines Yael Sagi Alla Shainskaya Michael Eisenbach 《Molecular microbiology》2010,76(4):932-943
The ability of CheY, the response regulator of bacterial chemotaxis, to generate clockwise rotation is regulated by two covalent modifications – phosphorylation and acetylation. While the function and signal propagation of the former are widely understood, the mechanism and role of the latter are still obscure. To obtain information on the function of this acetylation, we non‐enzymatically acetylated CheY to a level similar to that found in vivo, and examined its binding to its kinase CheA, its phosphatase CheZ and the switch protein FliM – its target at the flagellar switch complex. Acetylation repressed the binding to all three proteins. These results suggest that both phosphorylation and acetylation determine CheY's ability to bind to its target proteins, thus providing two levels of regulation, fast and slow respectively. The fast level is modulated by environmental signals (e.g. chemotactic and thermotactic stimuli). The slow one is regulated by the metabolic state of the cell and it determines, at each metabolic state, the fraction of CheY molecules that can participate in signalling. 相似文献
142.
Plant and Soil - Unravelling the factors shaping microbial community structure across plant holobiont is required to promote plant health and crop productivity. We compared microbial communities in... 相似文献
143.
Ido Laish Hila Katz Yael Sulayev Meytal Liberman Timna Naftali Fabiana Benjaminov Assaf Stein Yona Kitay-Cohen Tal Biron-Shental Fred Konikoff Aliza Amiel 《Gene》2013
Objective
Primary sclerosing cholangitis (PSC) is a chronic cholestatic disorder that involves inflammatory and fibrotic changes in the bile ducts. Up to 80% of patients have concomitant inflammatory bowel disease (IBD) with colitis. PSC patients are predisposed to develop hepatobiliary, colonic and other extrahepatic malignancies, probably related to inflammatory processes that might promote carcinogenesis. Telomerase is an enzyme complex that lengthens telomeres and has enhanced expression in numerous malignancies. In this study, we evaluated the TERC gene copy number, the proportion of cells in senescence and the amount of fragmentation in the senescent state.Methods
Fluorescence in situ hybridization (FISH) for the TERC gene was applied to lymphocytes retrieved from PSC (N = 19), colitis (N = 20) and healthy control patients (N = 20) to determine the TERC copy number. On the same FISH slides, cells stained with DAPI were also analyzed for senescence-associated heterochromatin foci (SAHF) status, including the number of cells with fragments and the number of SAHF fragments in each cell.Results
A higher TERC gene copy number was observed in cells from PSC patients compared to colitis and control group patients. It was also higher in the colitis than in the control group. Significantly more cells in the senescent state and more fragmentation in each cell were observed in the PSC group compared to colitis and control groups.Conclusion
The TERC gene copy number and the number of cells in the senescent state were increased in PSC patients compared to the colitis and control groups. These findings are probably related to the genetic instability parameters that reflect the higher tendency of this patient group to develop malignancies. 相似文献144.
Degu A Hatew B Nunes-Nesi A Shlizerman L Zur N Katz E Fernie AR Blumwald E Sadka A 《Planta》2011,234(3):501-513
Citrate, a major determinant of citrus fruit quality, accumulates early in fruit development and declines towards maturation.
The isomerization of citrate to isocitrate, catalyzed by aconitase is a key step in acid metabolism. Inhibition of mitochondrial
aconitase activity early in fruit development contributes to acid accumulation, whereas increased cytosolic activity of aconitase
causes citrate decline. It was previously hypothesized that the block in mitochondrial aconitase activity, inducing acid accumulation,
is caused by citramalate. Here, we investigated the effect of citramalate and of another aconitase inhibitor, oxalomalate,
on aconitase activity and regulation in callus originated from juice sacs. These compounds significantly increased citrate
content and reduced the enzyme’s activity, while slightly inducing its protein level. Citramalate inhibited the mitochondrial,
but not cytosolic form of the enzyme. Its external application to mandarin fruits resulted in inhibition of aconitase activity,
with a transient increase in fruit acidity detected a few weeks later. The endogenous level of citramalate was analyzed in
five citrus varieties: its pattern of accumulation challenged the notion of its action as an endogenous inhibitor of mitochondrial
aconitase. Metabolite profiling of oxalomalate-treated cells showed significant increases in a few amino acids and organic
acids. The activities of alanine transaminase, aspartate transaminase and aspartate kinase, as well as these of two γ-aminobutyrate
(GABA)-shunt enzymes, succinic semialdehyde reductase (SSAR) and succinic semialdehyde dehydrogenase (SSAD) were significantly
induced in oxalomalate-treated cells. It is suggested that the increase in citrate, caused by aconitase inhibition, induces
amino acid synthesis and the GABA shunt, in accordance with the suggested fate of citrate during the acid decline stage in
citrus fruit. 相似文献
145.
Translation elongation in eukaryotes is mediated by the concerted actions of elongation factor 1A (eEF1A), which delivers aminoacylated tRNA to the ribosome; elongation factor 1B (eEF1B) complex, which catalyzes the exchange of GDP to GTP on eEF1A; and eEF2, which facilitates ribosomal translocation. Here we present evidence in support of a novel mode of translation regulation by hindered tRNA delivery during mitosis. A conserved consensus phosphorylation site for the mitotic cyclin-dependent kinase 1 on the catalytic delta subunit of eEF1B (termed eEF1D) is required for its posttranslational modification during mitosis, resulting in lower affinity to its substrate eEF1A. This modification is correlated with reduced availability of eEF1A·tRNA complexes, as well as reduced delivery of tRNA to and association of eEF1A with elongating ribosomes. This mode of regulation by hindered tRNA delivery, although first discovered in mitosis, may represent a more globally applicable mechanism employed under other physiological conditions that involve down-regulation of protein synthesis at the elongation level. 相似文献
146.
147.
Louis J. Vuga Jadranka Milosevic Kusum Pandit Ahmi Ben-Yehudah Yanxia Chu Thomas Richards Joshua Sciurba Michael Myerburg Yingze Zhang Anil V. Parwani Kevin F. Gibson Naftali Kaminski 《PloS one》2013,8(12)
Idiopathic pulmonary fibrosis (IPF) is a progressive and life threatening disease with median survival of 2.5–3 years. The IPF lung is characterized by abnormal lung remodeling, epithelial cell hyperplasia, myofibroblast foci formation, and extracellular matrix deposition. Analysis of gene expression microarray data revealed that cartilage oligomeric matrix protein (COMP), a non-collagenous extracellular matrix protein is among the most significantly up-regulated genes (Fold change 13, p-value <0.05) in IPF lungs. This finding was confirmed at the mRNA level by nCounter® expression analysis in additional 115 IPF lungs and 154 control lungs as well as at the protein level by western blot analysis. Immunohistochemical analysis revealed that COMP was expressed in dense fibrotic regions of IPF lungs and co-localized with vimentin and around pSMAD3 expressing cells. Stimulation of normal human lung fibroblasts with TGF-β1 induced an increase in COMP mRNA and protein expression. Silencing COMP in normal human lung fibroblasts significantly inhibited cell proliferation and negatively impacted the effects of TGF-β1 on COL1A1 and PAI1. COMP protein concentration measured by ELISA assay was significantly increased in serum of IPF patients compared to controls. Analysis of serum COMP concentrations in 23 patients who had prospective blood draws revealed that COMP levels increased in a time dependent fashion and correlated with declines in force vital capacity (FVC). Taken together, our results should encourage more research into the potential use of COMP as a biomarker for disease activity and TGF-β1 activity in patients with IPF. Hence, studies that explore modalities that affect COMP expression, alleviate extracellular matrix rigidity and lung restriction in IPF and interfere with the amplification of TGF-β1 signaling should be persuaded. 相似文献
148.
Orna Reisman-Berman 《Ecography》2007,30(4):459-470
Shifts between facilitation and interference and their importance in shaping plant population and community dynamics have received wide recognition. Nevertheless, the causes and spatio-temporal scales of these shifts are poorly understood, yet strongly debated. This study tested the hypothesis that age-related changes in canopy structure shift the effect of a nurse shrub on their protégé from facilitation to interference, using as a model system the interaction between the dwarf shrub Sarcopoterium spinosum and conspecific new recruits, in the shrubland of the transition area between the Mediterranean and the semi-arid climatic zones of Israel. Foliation level (i.e. the percentage of canopy surface area covered with leaves), a measure of shrub canopy structure, increased with age. Shading level was significantly and positively related to foliation level. Densities of new recruits in the shrubland showed a unimodal response to canopy structure and cover: the highest densities were associated with canopies presenting low and medium foliation levels (providing 71 and 82% shade, respectively), while high foliation levels (93% shade) and open spaces among canopies were characterized by very low densities. A related field experiment using shading nets revealed that seedling survival rates followed a similar unimodal pattern, with the highest survival (ca 60%) detected in moderate shade (70%), twice as much as in full sun, and the lowest survival (ca 10%) observed in extreme shade (90%). These results support the study hypothesis on age-dependent interactions. Thus, in a semi-arid shrubland ecosystem, the transition of the "nurse shrub" from "young" to "old" stage can shift facilitation to interference. Hence, the age structure of established shrub populations determines a) the availability of suitable sites for seedling recruitment and b) the balance between facilitation versus interference effects on seedling establishment. 相似文献
149.
150.
The HLA class II Allele DRB1*1501 is over-represented in patients with idiopathic pulmonary fibrosis
Xue J Gochuico BR Alawad AS Feghali-Bostwick CA Noth I Nathan SD Rosen GD Rosas IO Dacic S Ocak I Fuhrman CR Cuenco KT Smith MA Jacobs SS Zeevi A Morel PA Pilewski JM Valentine VG Gibson KF Kaminski N Sciurba FC Zhang Y Duncan SR 《PloS one》2011,6(2):e14715