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21.
Sergiu Netotea Iris Bertani Laura Steindler Ádám Kerényi Vittorio Venturi Sándor Pongor 《Biology direct》2009,4(1):6-16
Background
Quorum sensing (QS) is a form of gene regulation based on cell-density that depends on inter-cellular communication. While there are a variety of models for bacterial colony morphology, there is little work linking QS genes to movement in an open system. 相似文献22.
Antimicrobial peptides are small molecular weight proteins with a large antibacterial spectrum. They can reach high local concentrations in tissues with active inflammation, being largely produced by immunocompetent cells. However, their effect on eukaryotic cells is still unclear. We have, therefore, studied three structurally different antimicrobial peptides (cecropin P1, PR‐39 and NK‐lysin) for their cytotoxic effects on blood mononuclear cells. None of the antimicrobial peptides tested exhibited significant cytotoxic effect on resting lymphocytes isolated either from peripheral blood or from the spleen with the exception of high concentrations (ten times higher than IC100 for Escherichia coli) of NK‐lysin. Activated lymphocytes were, however, more sensitive to the cytotoxic effect of the antimicrobial peptides. Both activated T‐cells and B‐cells were dose dependent sensitive to NK‐lysin while only activated B‐cells but not activated T‐cells were sensitive to PR‐39. Cecropin did not exhibit any cytotoxic effect on activated lymphocytes either. By using several cell lines (3B6, K562, U932 and EL‐4) we were able to show that NK‐lysin has a broad necrotic effect while PR‐39 has a cell specific apoptotic effect dependent on the specifically cellular uptake. In conclusion we show here that antimicrobial peptides are not cytotoxic for the resting eukaryotic cells but can be cytotoxic on activated immune cells through distinct mechanisms of cell death. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
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Sergiu Fendrihan Andrea Legat Marion Pfaffenhuemer Claudia Gruber Gerhard Weidler Friedrich Gerbl Helga Stan-Lotter 《Reviews in Environmental Science and Biotechnology》2006,5(2-3):203-218
Halophilic archaebacteria (haloarchaea) thrive in environments with salt concentrations approaching saturation, such as natural brines, the Dead Sea, alkaline salt lakes and marine solar salterns; they have also been isolated from rock salt of great geological age (195–250 million years). An overview of their taxonomy, including novel isolates from rock salt, is presented here; in addition, some of their unique characteristics and physiological adaptations to environments of low water activity are reviewed. The issue of extreme long-term microbial survival is considered and its implications for the search for extraterrestrial life. The development of detection methods for subterranean haloarchaea, which might also be applicable to samples from future missions to space, is presented. 相似文献
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Christine Gersch Sergiu P. Palii Witcha Imaram Kyung Mee Kim S. Ananth Karumanchi Alexander Angerhofer 《Nucleosides, nucleotides & nucleic acids》2013,32(2):118-149
Hyperuricemia is associated with hypertension, metabolic syndrome, preeclampsia, cardio-vascular disease and renal disease, all conditions associated with oxidative stress. We hypothesized that uric acid, a known antioxidant, might become prooxidative following its reaction with oxidants; and, thereby contribute to the pathogenesis of these diseases. Uric acid and 1,3-15N2-uric acid were reacted with peroxynitrite in different buffers and in the presence of alcohols, antioxidants and in human plasma. The reaction products were identified using liquid chromatography-mass spectrometry (LC-MS) analyses. The reactions generate reactive intermediates that yielded triuret as their final product. We also found that the antioxidant, ascorbate, could partially prevent this reaction. Whereas triuret was preferentially generated by the reactions in aqueous buffers, when uric acid or 1,3-15N2-uric acid was reacted with peroxynitrite in the presence of alcohols, it yielded alkylated alcohols as the final product. By extension, this reaction can alkylate other biomolecules containing OH groups and others containing labile hydrogens. Triuret was also found to be elevated in the urine of subjects with preeclampsia, a pregnancy-specific hypertensive syndrome that is associated with oxidative stress, whereas very little triuret is produced in normal healthy volunteers. We conclude that under conditions of oxidative stress, uric acid can form reactive intermediates, including potential alkylating species, by reacting with peroxynitrite. These reactive intermediates could possibly explain how uric acid contributes to the pathogenesis of diseases such as the metabolic syndrome and hypertension. 相似文献
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Andreea Dudu Sergiu Emil Georgescu Patrick Berrebi Marieta Costache 《Genetics and molecular biology》2012,35(4):886-891
Sturgeons are fish species with a complex biology. They are also characterized by complex aspects including polyploidization and easiness of hybridization. As with most of the Ponto-Caspian sturgeons, the populations of Acipenser ruthenus from the Danube have declined drastically during the last decades. This is the first report on mitochondrial point heteroplasmy in the cytochrome b gene of this species. The 1141 bp sequence of the cytb gene in wild sterlet sturgeon individuals from the Lower Danube was determined, and site heteroplasmy evidenced in three of the 30 specimens collected. Two nucleotide sequences were identified in these heteroplasmic individuals. The majority of the heteroplasmic sites are synonymous and do not modify the sequence of amino acids in cytochrome B protein. To date, several cases of point heteroplasmy have been reported in animals, mostly due to paternal leakage of mtDNA. The presence of specific point heteroplasmic sites might be interesting for a possible correlation with genetically distinct groups in the Danube River. 相似文献
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Depienne C Bouteiller D Méneret A Billot S Groppa S Klebe S Charbonnier-Beaupel F Corvol JC Saraiva JP Brueggemann N Bhatia K Cincotta M Brochard V Flamand-Roze C Carpentier W Meunier S Marie Y Gaussen M Stevanin G Wehrle R Vidailhet M Klein C Dusart I Brice A Roze E 《American journal of human genetics》2012,90(2):301-307
Congenital mirror movements (CMM) are characterized by involuntary movements of one side of the body that mirror intentional movements on the opposite side. CMM reflect dysfunctions and structural abnormalities of the motor network and are mainly inherited in an autosomal-dominant fashion. Recently, heterozygous mutations in DCC, the gene encoding the receptor for netrin 1 and involved in the guidance of developing axons toward the midline, have been identified but CMM are genetically heterogeneous. By combining genome-wide linkage analysis and exome sequencing, we identified heterozygous mutations introducing premature termination codons in RAD51 in two families with CMM. RAD51 mRNA was significantly downregulated in individuals with CMM resulting from the degradation of the mutated mRNA by nonsense-mediated decay. RAD51 was specifically present in the developing mouse cortex and, more particularly, in a subpopulation of corticospinal axons at the pyramidal decussation. The identification of mutations in RAD51, known for its key role in the repair of DNA double-strand breaks through homologous recombination, in individuals with CMM reveals a totally unexpected role of RAD51 in neurodevelopment. These findings open a new field of investigation for researchers attempting to unravel the molecular pathways underlying bimanual motor control in humans. 相似文献
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Victor Ciornea Liudmila Mingalieva Jean-Pierre Costes Ghenadie Novitchi Irina Filippova Ravil T. Galeev Sergiu Shova Violeta K. Voronkova Aurelian Gulea 《Inorganica chimica acta》2008,361(7):1947-1957
Five heterometallic compounds with formulae [Ba(H2O)4Cr2(μ-OH)2(nta)2] · 3H2O (I), [M(bpy)2(H2O)2] [Cr2(OH)2(nta)2] · 7H2O, where M2+ = Zn, (II); Ni, (III); Co, (IV) and [Mn(H2O)3(bpy)Cr2(OH)2(nta)2] · (bpy) · 5H2O (V); bpy = 2,2′-bipyridine, (nta = nitrilotriacetate ion) have been prepared by reaction of I with the corresponding MII-sulfates in the presence of 2,2′-bipyridine. Substances I–V have been characterized by magnetic susceptibility measurements, EPR and X-ray determinations. I represents a 2D coordination polymer formed by coordination of centrosymmetrical dimeric chromium(III) units and Barium cations. The 10-coordinate Ba polyhedron is completed by four water molecules. Compounds II–IV are isostructural and consist of non-centrosymmetric dimeric anions [Cr2(μ-OH)2(nta)2]2−, complex cations [MII(bpy)2(H2O)2]2+ and solvate water molecules. The octahedral coordination of chromium atoms implies four donor atoms of the nta3− ligands and two bridging OH groups. Multiple hydrogen bonds of coordinated and solvate water molecules link anions and cations in a 3D network. A similar [Cr2(μ-OH)2(nta)2]2− unit is found in V. The bridging function is performed by a carboxylate oxygen atom of the nta ligand that leads to the formation of a trinuclear complex [Mn(bpy)(H2O)2Cr2(μ-OH)2(nta)2]. Experimental and calculated frequency and temperature dependences of EPR spectra of these compounds are presented. The fine structure appearing on the EPR spectra of compound V is analyzed in detail at different temperatures. It is established that the main part of the EPR signals is due to the transitions in the spin states of a spin multiplet with S = 2. Analyses of experimental and calculated spectra confirm the absence of interaction between metal ions (MII) and Cr-dimers in complexes III and IV and the presence of weak Mn–Cr interactions in V. The temperature dependence of magnetic susceptibilities for I–V was fitted on the basis of the expression derived from isotropic Hamiltonian including a bi-quadratic exchange term. 相似文献
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Gersch C Palii SP Kim KM Angerhofer A Johnson RJ Henderson GN 《Nucleosides, nucleotides & nucleic acids》2008,27(8):967-978
The 1980 identification of nitric oxide (NO) as an endothelial cell-derived relaxing factor resulted in an unprecedented biomedical research of NO and established NO as one of the most important cardiovascular, nervous and immune system regulatory molecule. A reduction in endothelial cell NO levels leading to "endothelial dysfunction" has been identified as a key pathogenic event preceding the development of hypertension, metabolic syndrome, and cardiovascular disease. The reduction in endothelial NO in cardiovascular disease has been attributed to the action of oxidants that either directly react with NO or uncouple its substrate enzyme. In this report, we demonstrate that uric acid (UA), the most abundant antioxidant in plasma, reacts directly with NO in a rapid irreversible reaction resulting in the formation of 6-aminouracil and depletion of NO. We further show that this reaction occurs preferentially with NO even in the presence of oxidants peroxynitrite and hydrogen peroxide and that the reaction is at least partially blocked by glutathione. This study shows a potential mechanism by which UA may deplete NO and cause endothelial dysfunction, particularly under conditions of oxidative stress in which UA is elevated and intracellular glutathione is depleted. 相似文献