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91.
John E. Aston William A. Apel Brady D. Lee Brent M. Peyton 《World journal of microbiology & biotechnology》2011,27(1):153-161
The ability of Acidithiobacillus caldus to grow aerobically using pyruvate, acetate, citrate, 2-ketoglutarate, succinate, and malate as either an electron donor
and carbon source (heterotrophic growth), or as a carbon source when potassium tetrathionate was added as an electron donor
(mixotrophic growth), was tested in chemostat cultures. Under both heterotrophic and mixotrophic conditions, organic acids
were added to a sub-lethal concentration (50 μM). Under mixotrophic conditions, potassium tetrathionate was added to an excess
concentration (10 mM). No cell growth was observed under heterotrophic conditions; however, effluent cell concentrations increased
over threefold when pyruvate was coupled with potassium tetrathionate. Under these conditions, the effluent pyruvate concentration
was reduced to below the detection limit (2 μM), and oxygen consumption increased by approximately 100%. Although pyruvate
provided a carbon source in these experiments, ambient carbon dioxide was also available to the cells. To test whether At. caldus could grow mixotrophically using pyruvate as a sole carbon source and potassium tetrathionate as an electron donor, cells
were batch cultured in a medium free of dissolved inorganic carbon, and with no carbon dioxide in the headspace. These experiments
showed that At. caldus was able to convert between 65 ± 8 and 82 ± 15% of the pyruvate carbon to cellular biomass, depending on the initial pyruvate
concentrations. This work is the first to identify a defined organic-carbon source, other than glucose, that At. caldus can assimilate. This has important implications, as mixotrophic and heterotrophic activity has been shown to increase mineral
leaching in acidic systems. 相似文献
92.
Ca2+ and Mg2+ bind tetracycline with distinct stoichiometries and linked deprotonation 总被引:1,自引:0,他引:1
Jin L Amaya-Mazo X Apel ME Sankisa SS Johnson E Zbyszynska MA Han A 《Biophysical chemistry》2007,128(2-3):185-196
Tetracycline depends on divalent metal ions for its biological function, but its multiple ionization states, conformations, and tautomers at varying solution conditions complicate its ion-binding equilibria, and the stoichiometry of the biologically relevant Ca2+ or Mg2+ complexes has not been clear. Isothermal titration calorimetry was used in the present work to study Ca2+ and Mg2+ binding to tetracycline. The two metal ions bind with distinct stoichiometries, one Ca2+ per tetracycline and one Mg2+ per two tetracyclines, and with differing dependence on solution conditions, indicating that these two ions bind TC differently. An endothermic process accompanies ion binding that is proposed to reflect conformational changes in tetracycline. The results identify conditions that limit the distribution of species and may facilitate structural study. 相似文献
93.
Viamajala S Smith WA Sani RK Apel WA Petersen JN Neal AL Roberto FF Newby DT Peyton BM 《Bioresource technology》2007,98(3):612-622
Microbial enrichments from Cr(VI) contaminated and uncontaminated US Department of Energy Hanford Site sediments produced Cr(VI) reducing consortia when grown in the presence of Cr(VI) with acetate, D-xylose or glycerol as a carbon and energy source. Eight of the nine isolates from the consortia were Gram positive and four of these were identified by 16S rRNA sequence homology and membrane fatty acid composition as belonging to the genus Cellulomonas. Two strains, ES6 and WS01, were further examined for their ability to reduce Cr(VI) under growth and non-growth conditions. During fermentative growth on D-xylose, ES6 and WS01 decreased aqueous Cr(VI) concentrations from 0.04 mM Cr(VI) to below the detection limit (0.002 mM Cr(VI)) in less than three days and retained their ability to reduce Cr(VI) even after four months of incubation. Washed ES6 and WS01 cells also reduced Cr(VI) under non-growth conditions for over four months, both with and without the presence of an exogenous electron donor. K-edge XANES spectroscopy confirmed the reduction of Cr(VI) to Cr(III). The ability to reduce Cr(VI) after growth had stopped and in the absence of an external electron donor, suggests that stimulation of these types of organisms may lead to effective long-term, in situ passive reactive barriers for Cr(VI) removal. Our results indicate that Cr(VI) reduction by indigenous Cellulomonas spp. may be a potential method of in situ bioremediation of Cr(VI) contaminated sediment and groundwater. 相似文献
94.
David J Sewell Richard Turner Ray Field William Holmes Rahul Pradhan Christopher Spencer Stephen G Oliver Nigel KH Slater Duygu Dikicioglu 《Biotechnology and bioengineering》2019,116(6):1315-1325
Without a scale-down model for perfusion, high resource demand makes cell line screening or process development challenging, therefore, potentially successful cell lines or perfusion processes are unrealized and their ability untapped. We present here the refunctioning of a high-capacity microscale system that is typically used in fed-batch process development to allow perfusion operation utilizing in situ gravity settling and automated sampling. In this low resource setting, which involved routine perturbations in mixing, pH and dissolved oxygen concentrations, the specific productivity and the maximum cell concentration were higher than 3.0 × 106 mg/cell/day and 7 × 10 7 cells/ml, respectively, across replicate microscale perfusion runs conducted at one vessel volume exchange per day. A comparative analysis was conducted at bench scale with vessels operated in perfusion mode utilizing a cell retention device. Neither specific productivity nor product quality indicated by product aggregation (6%) was significantly different across scales 19 days after inoculation, thus demonstrating this setup to be a suitable and reliable platform for evaluating the performance of cell lines and the effect of process parameters, relevant to perfusion mode of culturing. 相似文献
95.
96.
Beate B?hm Harald Burkhardt Steffen Uebe Maria Apel Frank Behrens André Reis Ulrike Hüffmeier 《Arthritis research & therapy》2012,14(2):R84-5
Introduction
In recent genome-wide association studies for psoriatic arthritis (PsA) and psoriasis vulgaris, common coding variants in the TRAF3IP2 gene were identified to contribute to susceptibility to both disease entities. The risk allele of p.Asp10Asn (rs33980500) proved to be most significantly associated and to encode a mutant protein with an almost completely disrupted binding property to TRAF6, supporting its impact as a main disease-causing variant and modulator of IL-17 signaling.Methods
To identify further variants, exons 2-4 encoding both known TNF-receptor-associated factor (TRAF) binding domains were sequenced in 871 PsA patients. Seven missense variants and one three-base-pair insertion were identified in 0.06% to 1.02% of alleles. Five of these variants were also present in 931 control individuals at comparable frequency. Constructs containing full-length wild-type or mutant TRAF3IP2 were generated and used to analyze functionally all variants for TRAF6-binding in a mammalian two-hybrid assay.Results
None of the newly found alleles, though, encoded proteins with different binding properties to TRAF6, or to the cytoplasmic tail of the IL-17-receptor α-chain, suggesting that they do not contribute to susceptibility.Conclusions
Thus, the TRAF3IP2-variant p.Asp10Asn is the only susceptibility allele with functional impact on TRAF6 binding, at least in the German population. 相似文献97.
Walter Maetzler Youyong Tian Stephanie Maria Baur Tina Gauger Bartholom?us Odoj Benjamin Schmid Claudia Schulte Christian Deuschle Susanna Heck Anja Apel Arthur Melms Thomas Gasser Daniela Berg 《PloS one》2012,7(10)
Parkinson’s disease (PD) without (non-demented, PDND) and with dementia (PDD), and dementia with Lewy bodies (DLB) are subsumed under the umbrella term Lewy body disorders (LBD). The main component of the underlying pathologic substrate, i.e. Lewy bodies and Lewy neurites, is misfolded alpha-synuclein (Asyn), and - in particular in demented LBD patients - co-occurring misfolded amyloid-beta (Abeta). Lowered blood and cerebrospinal fluid (CSF) levels of transthyretin (TTR) - a clearance protein mainly produced in the liver and, autonomously, in the choroid plexus - are associated with Abeta accumulation in Alzheimer’s disease. In addition, a recent study suggests that TTR is involved in Asyn clearance. We measured TTR protein levels in serum and cerebrospinal fluid of 131 LBD patients (77 PDND, 26 PDD, and 28 DLB) and 72 controls, and compared TTR levels with demographic and clinical data as well as neurodegenerative markers in the CSF. Five single nucleotide polymorphisms of the TTR gene which are considered to influence the ability of the protein to carry its ligands were also analyzed. CSF TTR levels were significantly higher in LBD patients compared to controls. Post-hoc analysis demonstrated that this effect was driven by PDND patients. In addition, CSF TTR levels correlated negatively with CSF Abeta1–42, total tau and phospho-tau levels. Serum TTR levels did not significantly differ among the studied groups. There were no relevant associations between TTR levels and genetic, demographic and clinical data, respectively. These results suggest an involvement of the clearance protein TTR in LBD pathophysiology, and should motivate to elucidate TTR-related mechanisms in LBD in more detail. 相似文献
98.
Cécile Apel Vincent Dumontet Olivier Lozach Laurent Meijer Françoise Guéritte Marc Litaudon 《Phytochemistry letters》2012,5(4):814-818
The chemical investigation of the epiphytic orchid Appendicula reflexa led to the isolation of one new phenanthrene, 3,4,6,7-tetramethoxyphenanthrene-2,8-diol (1) and one new bisphenanthrene ether, named blestrin E (6), together with the known monomeric phenanthrenes, nudol (2), 3,4,6-trimethoxyphenanthrene-2,7-diol (3), coelonin (4) and 6-methoxycoelonin (5). Their structural elucidation was established on the basis of spectroscopic data analysis. The monomeric phenanthrenes 1 and 3 showed moderate cytotoxic activities against KB, MCF7 and K562 cells, and potent inhibiting activity on CDK1/cyclin B (IC50s = 0.07 and 0.2 μM, respectively). 相似文献
99.
100.
Expression of genes belonging to the pho regulon in Streptomyces coelicolor is positively regulated (as shown by comparing the wild-type and a DeltaphoP mutant) by binding of the response regulator PhoP to 11-nt direct repeats (DRus). These sequences have been found in over 100 genes of Streptomyces coelicolor; 20 of them were cloned and the binding of PhoP(DBD) to most of their promoters has been shown by electrophoretic mobility shift assays. Deletion experiments showed that at least two DRus are required for proper binding of PhoP(DBD). Deletion of 1 nt leaving a 10-nt direct repeat reduced drastically binding of PhoP(DBD). Three different types of operators have been identified. Complex operators (class III) contain up to six DRus, some of them with poor conservation of the 11-nt consensus sequence, which however were protected by PhoP(DBD) in footprinting analyses. A cooperative binding of PhoP(DBD) molecules initiated at conserved core DRus appears to be the mechanism involved in binding of several PhoP(DBD) monomers to those complex operators. The information theory-based model that incorporates the positive or negative contribution to the binding of PhoP(DBD) of adjacent sequences has been used to deduce the structure of PHO boxes and the relevance of each DRu. 相似文献