Search results for "Lytic cycle"
showing 10 items of 75 documents
A kinetic model for the oxidation of benzenethiol catalyzed by the [MoVIO2(O2CC(S)(C6H5)2)2]2− complex intercalated in a Zn(II)–Al(III) layered doubl…
2009
Abstract The heterogeneous oxidation of benzenethiol catalyzed by the dianionic bis(2-sulfanyl-2,2-diphenylethanoxycarbonyl) dioxomolybdate (VI) complex intercalated into a Zn(II)–Al(III) layered double hydroxide (LDH) host have been investigated under aerobic conditions. The kinetics of the system has been analysed in detail. In ethanol, the benzenethiol is cleanly oxidized to diphenyl disulfide in the acidic media provided by the protonic resin Amberlite IR-120(H). The reaction is second-order in benzenethiol, and the apparent rate coefficient has been found to be proportional to the catalyst weight and inversely proportional to the initial concentration of the substrate. A catalytic cycl…
High temperature and bacteriophages can indirectly select for bacterial pathogenicity in environmental reservoirs
2010
The coincidental evolution hypothesis predicts that traits connected to bacterial pathogenicity could be indirectly selected outside the host as a correlated response to abiotic environmental conditions or different biotic species interactions. To investigate this, an opportunistic bacterial pathogen, Serratia marcescens, was cultured in the absence and presence of the lytic bacteriophage PPV (Podoviridae) at 25°C and 37°C for four weeks (N = 5). At the end, we measured changes in bacterial phage-resistance and potential virulence traits, and determined the pathogenicity of all bacterial selection lines in the Parasemia plantaginis insect model in vivo. Selection at 37°C increased bacterial…
Slow Infection due to Lowering the Amount of Intact versus Empty Particles Is a Characteristic Feature of Coxsackievirus B5 Dictated by the Structura…
2019
Enterovirus B species typically cause a rapid cytolytic infection leading to efficient release of progeny viruses. However, they are also capable of persistent infections in tissues, which are suggested to contribute to severe chronic states such as myocardial inflammation and type 1 diabetes. In order to understand the factors contributing to differential infection strategies, we constructed a chimera by combining the capsid proteins from fast-cytolysis-causing echovirus 1 (EV1) with nonstructural proteins from coxsackievirus B5 (CVB5), which shows persistent infection in RD cells. The results showed that the chimera behaved similarly to parental EV1, leading to efficient cytolysis in both…
A green way to gamma-lactams through a copper catalyzed ARGET-ATRC in ethanol and in the presence of ascorbic acid
2011
Abstract A ‘green’ ARGET-ATRC, for the CuCl[PMDETA] catalysed cyclo -isomerization of N -allyl-α-polychloroamides to γ-lactams is described. The process works efficiently (yields 78–96%), uses a bio-solvent, as ethanol, and exploits the reducing feature of ascorbic acid to limit, at a low level (2–4%), the amount of catalyst. To preserve the efficacy of the catalytic cycle, addition of Na 2 CO 3 is essential, which quenches the HCl released during the CuCl[PMDETA] regeneration step. Profitable features of the process are: mild reaction temperatures (25–37 °C), relatively short reaction times (usually 5 h) and low solvent volumes (2 mmol of substrate/mL of ethanol). The method, upon stoichio…
Understanding light-driven H 2 evolution through the electronic tuning of aminopyridine cobalt complexes
2017
A new family of cobalt complexes with the general formula [CoII(OTf)2(Y,XPyMetacn)] (1R,Y,XPyMetacn ¼ 1-[(4-X-3,5-Y-2-pyridyl)methyl]-4,7-dimethyl-1,4,7-triazacyclononane, (X ¼ CN (1CN), CO2Et (1CO2Et), Cl (1Cl), H(1H), NMe2 (1NMe2)) where (Y ¼ H, and X ¼ OMe when Y ¼ Me (1DMM)) is reported. We found that the electronic tuning of the Y,XPyMetacn ligand not only has an impact on the electronic and structural properties of the metal center, but also allows for a systematic water-reduction-catalytic control. In particular, the increase of the electron-withdrawing character of the pyridine moiety promotes a 20-fold enhancement of the catalytic outcome. By UV-Vis spectroscopy, luminescence quenc…
Studies on Holothuriapolii (echinodermata) coelomocyte lysate II. Isolation of coelomocyte hemolysins
1988
The lytic activity of the Holothuria polii coelomocyte lysate resides in two electrophoretically distinct hemolysins identified as He1 and He2. He1 represents the calcium dependent, heat-labile component whereas He2 is calcium independent and heat-stable. The two hemolysins share serological identity. Both hemolysins appear as single protein molecules of 80KDa molecular weight by SDS-PAGE and transblotting analysis under non-reducing conditions. However under reducing conditions, they are doublets of 76 and 80KDa molecular weight. The hypothesis that the two hemolysins could be isoforms is discussed.
Bacteriophage GIL01 gp7 interacts with host LexA repressor to enhance DNA binding and inhibit RecA-mediated auto-cleavage
2015
The SOS response in Eubacteria is a global response to DNA damage and its activation is increasingly associated with the movement of mobile genetic elements. The temperate phage GIL01 is induced into lytic growth using the host's SOS response to genomic stress. LexA, the SOS transcription factor, represses bacteriophage transcription by binding to a set of SOS boxes in the lysogenic promoter P1. However, LexA is unable to efficiently repress GIL01 transcription unless the small phage-encoded protein gp7 is also present. We found that gp7 forms a stable complex with LexA that enhances LexA binding to phage and cellular SOS sites and interferes with RecA-mediated auto-cleavage of LexA, the ke…
Phage-borne factors and host LexA regulate the lytic switch in phage GIL01.
2011
ABSTRACT The Bacillus thuringiensis temperate phage GIL01 does not integrate into the host chromosome but exists stably as an independent linear replicon within the cell. Similar to that of the lambdoid prophages, the lytic cycle of GIL01 is induced as part of the cellular SOS response to DNA damage. However, no CI-like maintenance repressor has been detected in the phage genome, suggesting that GIL01 uses a novel mechanism to maintain lysogeny. To gain insights into the GIL01 regulatory circuit, we isolated and characterized a set of 17 clear plaque ( cp ) mutants that are unable to lysogenize. Two phage-encoded proteins, gp1 and gp7, are required for stable lysogen formation. Analysis of …
Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides
2006
Abstract We have studied a reaction between the reduced form of titanocene dichloride (Cp 2 TiCl 2 ) and a group of organic halides: benzyl derivatives (4-X C 6 H 4 CH 2 Cl, X = H, NO 2 , CH 3 ; 4-X C 6 H 4 CH 2 Br, X = H, NO 2 , PhC(O); 4-X C 6 H 4 CH 2 SCN, X = H, NO 2 ) as well as three aryl halides (4-NO 2 C 6 H 4 Hal, Hal = Cl, Br; 4-CH 3 O-C 6 H 4 Cl). It has been shown that the electrochemical reduction of Cp 2 TiCl 2 in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Base…
Phage-driven loss of virulence in a fish pathogenic bacterium
2012
Parasites provide a selective pressure during the evolution of their hosts, and mediate a range of effects on ecological communities. Due to their short generation time, host-parasite interactions may also drive the virulence of opportunistic bacteria. This is especially relevant in systems where high densities of hosts and parasites on different trophic levels (e.g. vertebrate hosts, their bacterial pathogens, and virus parasitizing bacteria) co-exist. In farmed salmonid fingerlings, Flavobacterium columnare is an emerging pathogen, and phage that infect F. columnare have been isolated. However, the impact of these phage on their host bacterium is not well understood. To study this, four s…