排序方式: 共有119条查询结果,搜索用时 31 毫秒
81.
Dumitru R Navarathna DH Semighini CP Elowsky CG Dumitru RV Dignard D Whiteway M Atkin AL Nickerson KW 《Eukaryotic cell》2007,6(3):465-472
Candida albicans cells of opposite mating types are thought to conjugate during infection in mammalian hosts, but paradoxically, the mating-competent opaque state is not stable at mammalian body temperatures. We found that anaerobic conditions stabilize the opaque state at 37 degrees C, block production of farnesol, and permit in vitro mating at 37 degrees C at efficiencies of up to 84%. Aerobically, farnesol prevents mating because it kills the opaque cells necessary for mating, and as a corollary, farnesol production is turned off in opaque cells. These in vitro observations suggest that naturally anaerobic sites, such as the efficiently colonized gastrointestinal (GI) tract, could serve as niches for C. albicans mating. In a direct test of mating in the mouse GI tract, prototrophic cells were obtained from auxotrophic parent cells, confirming that mating will occur in this organ. These cells were true mating products because they were tetraploid, mononuclear, and prototrophic, and they contained the heterologous hisG marker from one of the parental strains. 相似文献
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Adina Raducan Anca Ruxandra Cantemir Mihaela Puiu Dumitru Oancea 《Bioprocess and biosystems engineering》2012,35(9):1523-1530
The effect of water–alcohol (methanol, ethanol, propan-1-ol, propan-2-ol, ethane-1,2-diol and propane-1,2,3-triol) binary mixtures on the kinetics of hydrogen peroxide decomposition in the presence of bovine liver catalase is investigated. In all solvents, the activity of catalase is smaller than in water. The results are discussed on the basis of a simple kinetic model. The kinetic constants for product formation through enzyme–substrate complex decomposition and for inactivation of catalase are estimated. The organic solvents are characterized by several physical properties: dielectric constant (D), hydrophobicity (log P), concentration of hydroxyl groups ([OH]), polarizability (α), Kamlet-Taft parameter (β) and Kosower parameter (Z). The relationships between the initial rate, kinetic constants and medium properties are analyzed by linear and multiple linear regression. 相似文献
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Panait Marieta Elena Chilug Livia Negoita Valentina Busca Antonela Manda Gina Niculae Dana Dumitru Mirela Gruia Maria Iuliana 《International journal of peptide research and therapeutics》2019,25(3):979-987
International Journal of Peptide Research and Therapeutics - Positron emission tomography (PET) with 68Ga-labeled peptides is a promising option in the imaging of tumors expressing peptide-binding... 相似文献
87.
Grindberg RV Ishoey T Brinza D Esquenazi E Coates RC Liu WT Gerwick L Dorrestein PC Pevzner P Lasken R Gerwick WH 《PloS one》2011,6(4):e18565
Filamentous marine cyanobacteria are extraordinarily rich sources of structurally novel, biomedically relevant natural products. To understand their biosynthetic origins as well as produce increased supplies and analog molecules, access to the clustered biosynthetic genes that encode for the assembly enzymes is necessary. Complicating these efforts is the universal presence of heterotrophic bacteria in the cell wall and sheath material of cyanobacteria obtained from the environment and those grown in uni-cyanobacterial culture. Moreover, the high similarity in genetic elements across disparate secondary metabolite biosynthetic pathways renders imprecise current gene cluster targeting strategies and contributes sequence complexity resulting in partial genome coverage. Thus, it was necessary to use a dual-method approach of single-cell genomic sequencing based on multiple displacement amplification (MDA) and metagenomic library screening. Here, we report the identification of the putative apratoxin. A biosynthetic gene cluster, a potent cancer cell cytotoxin with promise for medicinal applications. The roughly 58 kb biosynthetic gene cluster is composed of 12 open reading frames and has a type I modular mixed polyketide synthase/nonribosomal peptide synthetase (PKS/NRPS) organization and features loading and off-loading domain architecture never previously described. Moreover, this work represents the first successful isolation of a complete biosynthetic gene cluster from Lyngbya bouillonii, a tropical marine cyanobacterium renowned for its production of diverse bioactive secondary metabolites. 相似文献
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We report the hierarchical supramolecular organization of metallosupramolecular homochiral complexes 1 ‐Λ‐(S,S,S,S)‐M2+/ 1 ‐?‐(R,R,R,R)‐M2+ and 2 ‐ Λ‐(S,S,S,S)‐M2+/ 2 ‐?‐ (R,R,R,R)‐M2+ of M2+ = Co2+, Fe2+, Zn2+ metal ions with chiral pseudo‐terpyridine‐type ligands: 1‐ (S,S) or 1‐ (R,R) = 2,6‐bis (naphthyl ethylimine)pyridine and 2‐ (S,S) or 2‐ (R,R) = 2,6‐bis (phenyl‐ethylimine)pyridine. Circular dichroism measurements in solution were used to confirm the enantiomeric nature of all twelve complexes. For crystal structures of 1 ‐ Λ‐ (S,S,S,S)‐M2+ or 1 ‐?‐ (R,R,R,R)‐M2+ complexes, absolute configurations {? (or P), Λ (or M)} were confirmed by refinement of the Flack parameter x: ?0.007 ≤ x ≤ 0.11 for the single crystals of 1 ‐Λ‐(S,S,S,S)‐M2+/ 1 ‐?‐ (R,R,R,R)‐M2+, 2 ‐ Λ‐ (S,S,S,S)‐Fe2+, and 2 ‐?‐ (R,R,R,R)‐Co2+. 相似文献
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Dumitru Chesov Christoph Lange Franziska Daduna Valeriu Crudu Rosemarie Preyer Martin Ernst Barbara Kalsdorf 《PloS one》2015,10(3)
Background
To evaluate interleukin (IL)-2 and interferon (IFN)-γ secreting T-cells in parallel for the differentiation of latent infection with Mycobacterium tuberculosis infection (LTBI) from active tuberculosis.Methods
Following ex-vivo stimulation of peripheral blood mononuclear cells (PBMC) with M. tuberculosis-specific antigens early secretory antigenic target (ESAT)-6 and culture filtrate protein (CFP)-10, immune responses were assessed by enzyme-linked immunospot IFN-γ release assay (EliSpot-IGRA) and a novel dual cytokine detecting fluorescence-linked immunospot (FluoroSpot) in 18 patients with pulmonary tuberculosis, 10 persons with previously cured tuberculosis, 25 individuals with LTBI and 16 healthy controls.Results
Correlation of IFN- γ+ spot-forming cells in EliSpot-IGRA and FluoroSpot were R2 = 0.67 for ESAT-6 and R2 = 0.73 for CFP-10. The number of IL-2- IFN- γ+ producing cells was higher in patients with tuberculosis compared with past tuberculosis (CFP-10-induced p = 0.0068) or individuals with LTBI (ESAT-6-induced p = 0.0136). A cutoff value of >16 CFP-10-induced IFN-γ+ secreting cells/200.000 PBMC in the EliSpot-IGRA discriminated with highest sensitivity and specificity (89% and 76%, respectively). However, overlap in cytokine responses precludes distinction between the cohorts on an individual basis.Conclusions
Combined analysis of IFN-γ and IL-2 secretion by antigen specific T-cells does not allow a reliable differentiation between different states of M. tuberculosis infection in clinical practice. 相似文献90.