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131.
Isolation and characterization of cellulose-degrading bacteria from the deep subsurface of the Homestake gold mine,Lead, South Dakota,USA 总被引:3,自引:0,他引:3
Gurdeep Rastogi Geetha L. Muppidi Raghu N. Gurram Akash Adhikari Kenneth M. Bischoff Stephen R. Hughes William A. Apel Sookie S. Bang David J. Dixon Rajesh K. Sani 《Journal of industrial microbiology & biotechnology》2009,36(4):585-598
The present study investigated the cultivable mesophilic (37°C) and thermophilic (60°C) cellulose-degrading bacterial diversity
in a weathered soil-like sample collected from the deep subsurface (1.5 km depth) of the Homestake gold mine in Lead, South
Dakota, USA. Chemical characterization of the sample by X-ray fluorescence spectroscopy revealed a high amount of toxic heavy
metals such as Cu, Cr, Pb, Ni, and Zn. Molecular community structures were determined by phylogenetic analysis of 16S rRNA
gene sequences retrieved from enrichment cultures growing in presence of microcrystalline cellulose as the sole source of
carbon. All phylotypes retrieved from enrichment cultures were affiliated to Firmicutes. Cellulose-degrading mesophilic and thermophilic pure cultures belonging to the genera Brevibacillus, Paenibacillus, Bacillus, and Geobacillus were isolated from enrichment cultures, and selected cultures were studied for enzyme activities. For a mesophilic isolate
(DUSELG12), the optimum pH and temperature for carboxymethyl cellulase (CMCase) were 5.5 and 55°C, while for a thermophilic
isolate (DUSELR7) they were 5.0 and 75°C, respectively. Furthermore, DUSELG12 retained about 40% CMCase activity after incubation
at 60°C for 8 h. Most remarkably, thermophilic isolate, DUSELR7 retained 26% CMCase activity at 60°C up to a period of 300 h.
Overall, the present work revealed the presence of different cellulose-degrading bacterial lineages in the unique deep subsurface
environment of the mine. The results also have strong implications for biological conversion of cellulosic agricultural and
forestry wastes to commodity chemicals including sugars. 相似文献
132.
Regulation of tetrapyrrole biosynthesis in higher plants has been attributed to negative feedback control. Two effectors of feedback inhibition have been identified, heme and the FLU protein. Inhibition by heme implicates the Fe-branch via regulation of the initial step of tetrapyrrole synthesis. In the present work a FLU-containing chloroplast membrane complex was identified, that besides FLU comprises the four enzymes catalyzing the final steps of chlorophyll synthesis. The results support the notion that FLU links chlorophyll synthesis and the target of feedback control, glutamyl-tRNA reductase, thereby allowing also the Mg-branch to control the initial step of tetrapyrrole synthesis. 相似文献
133.
Delekta PC Apel IJ Gu S Siu K Hattori Y McAllister-Lucas LM Lucas PC 《The Journal of biological chemistry》2010,285(53):41432-41442
Thrombin is a potent modulator of endothelial function and, through stimulation of NF-κB, induces endothelial expression of intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). These cell surface adhesion molecules recruit inflammatory cells to the vessel wall and thereby participate in the development of atherosclerosis, which is increasingly recognized as an inflammatory condition. The principal receptor for thrombin on endothelial cells is protease-activated receptor-1 (PAR-1), a member of the G protein-coupled receptor superfamily. Although it is known that PAR-1 signaling to NF-κB depends on initial PKC activation, the subsequent steps leading to stimulation of the canonical NF-κB machinery have remained unclear. Here, we demonstrate that a complex of proteins containing CARMA3, Bcl10, and MALT1 links PAR-1 activation to stimulation of the IκB kinase complex. IκB kinase in turn phosphorylates IκB, leading to its degradation and the release of active NF-κB. Further, we find that although this CARMA3·Bcl10·MALT1 signalosome shares features with a CARMA1-containing signalosome found in lymphocytes, there are significant differences in how the signalosomes communicate with their cognate receptors. Specifically, whereas the CARMA1-containing lymphocyte complex relies on 3-phosphoinositide-dependent protein kinase 1 for assembly and activation, the CARMA3-containing endothelial signalosome functions completely independent of 3-phosphoinositide-dependent protein kinase 1 and instead relies on β-arrestin 2 for assembly. Finally, we show that thrombin-dependent adhesion of monocytes to endothelial cells requires an intact endothelial CARMA3·Bcl10·MALT1 signalosome, underscoring the importance of the signalosome in mediating one of the most significant pro-atherogenic effects of thrombin. 相似文献
134.
Sabine Neuss Bernd Denecke Lin Gan Qiong Lin Manfred Bovi Christian Apel Michael W?ltje Anandhan Dhanasingh Jochen Salber Ruth Knüchel Martin Zenke 《PloS one》2011,6(9)
Background
Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone tissue engineering because of their ex vivo expansion potential and multipotent differentiation capacity. MSC are readily differentiated towards mature osteoblasts with well-established protocols. However, tissue engineering frequently involves three-dimensional scaffolds which (i) allow for cell adhesion in a spatial environment and (ii) meet application-specific criteria, such as stiffness, degradability and biocompatibility.Methodology/Principal Findings
In the present study, we analysed two synthetic, long-term degradable polymers for their impact on MSC-based bone tissue engineering: PLLA-co-TMC (Resomer® LT706) and poly(ε-caprolactone) (PCL). Both polymers enhance the osteogenic differentiation compared to tissue culture polystyrene (TCPS) as determined by Alizarin red stainings, scanning electron microscopy, PCR and whole genome expression analysis. Resomer® LT706 and PCL differ in their influence on gene expression, with Resomer® LT706 being more potent in supporting osteogenic differentiation of MSC. The major trigger on the osteogenic fate, however, is from osteogenic induction medium.Conclusion
This study demonstrates an enhanced osteogenic differentiation of MSC on Resomer® LT706 and PCL compared to TCPS. MSC cultured on Resomer® LT706 showed higher numbers of genes involved in skeletal development and bone formation. This identifies Resomer® LT706 as particularly attractive scaffold material for bone tissue engineering. 相似文献135.
Šimková K Kim C Gacek K Baruah A Laloi C Apel K 《The Plant journal : for cell and molecular biology》2012,69(4):701-712
Retrograde plastid-to-nucleus signaling tightly controls and coordinates the nuclear and plastid gene expression that is required for plastid biogenesis and chloroplast activity. As chloroplasts act as sensors of environmental changes, plastid-derived signaling also modulates stress responses of plants by transferring stress-related signals and altering nuclear gene expression. Various mutant screens have been undertaken to identify constituents of plastid signaling pathways. Almost all mutations identified in these screens target plastid-specific but not extraplastidic functions. They have been suggested to define either genuine constituents of retrograde signaling pathways or components required for the synthesis of plastid signals. Here we report the characterization of the constitutive activator of AAA-ATPase (caa33) mutant, which reveals another way of how mutations that affect plastid functions may modulate retrograde plastid signaling. caa33 disturbs a plastid-specific function by impeding plastid division, and thereby perturbing plastid homeostasis. This results in preconditioning plants by activating the expression of stress genes, enhancing pathogen resistance and attenuating the capacity of the plant to respond to plastid signals. Our study reveals an intimate link between chloroplast activity and the susceptibility of the plant to stress, and emphasizes the need to consider the possible impact of preconditioning on retrograde plastid-to-nucleus signaling. 相似文献
136.
Van Beek M Oravecz-Wilson KI Delekta PC Gu S Li X Jin X Apel IJ Konkle KS Feng Y Teitelbaum DH Ruland J McAllister-Lucas LM Lucas PC 《Cell reports》2012,1(5):444-452
Excess serum free fatty acids (FFAs) are fundamental to the pathogenesis of insulin resistance. With high-fat feeding, FFAs activate NF-kB in target tissues, initiating negative crosstalk with insulin signaling. However, the mechanisms underlying FFA-dependent NF-kB activation remain unclear. Here, we demonstrate that the saturated FA, palmitate, requires Bcl10 for NF-kB activation in hepatocytes. Uptake of palmitate, metabolism to diacylglycerol, and subsequent activation of protein kinase C (PKC) appear to mechanistically link palmitate with Bcl10, known as a central component of a signaling complex that, along with CARMA3 and MALT1, activates NF-kB downstream of selected cell surface receptors. Consequently, Bcl10-deficient mice are protected from hepatic NF-kB activation and insulin resistance following brief high-fat diet, suggesting that Bcl10 plays a major role in the metabolic consequences of acute overnutrition. Surprisingly, while CARMA3 also participates in the palmitate response, MALT1 is completely dispensable, thereby revealing an apparent nonclassical role for Bcl10 in NF-kB signaling. 相似文献
137.
Aiswarya Baruah Klára imková Dirk K. Hincha Klaus Apel Christophe Laloi 《The Plant journal : for cell and molecular biology》2009,60(1):22-32
Shortly after the release of singlet oxygen (1 O2 ) in chloroplasts, changes in nuclear gene expression occur in the conditional flu mutant of Arabidopsis that reveal a rapid transfer of signals from the plastid to the nucleus. Extensive genetic screens aimed at identifying constituents involved in 1 O2 -mediated plastid-to-nucleus signaling have failed to identify extraplastidic signaling components. This finding suggests that 1 O2 -mediated signals are not translocated to the nucleus via a single linear pathway, but rather through a signaling network that is difficult to block by single mutations. The complexity of this signaling network has been tackled by mutagenizing a transgenic flu line expressing the luciferase reporter gene under the control of the promoter of a 1 O2 -responsive AAA-ATPase gene (At3g28580) and isolating second site mutants that constitutively express the reporter gene at a high level. One of the mutants was shown by map-based cloning and sequencing to contain a single amino acid change in the PLEIOTROPIC RESPONSE LOCUS 1 (PRL1) protein. PRL1 suppresses the expression of AAA-ATPase and other 1 O2 -responsive genes. PRL1 seems to play a major role in modulating responses of plants to environmental changes by interconnecting 1 O2 -mediated retrograde signaling with other signaling pathways. 相似文献
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