Impact of wild-type and genetically modified Pseudomonas fluorescens on soil enzyme activities and microbial population structure in the rhizosphere of pea

The definitive version is available at www.blackwell-synergy.com. Copyright Blackwell Publishing DOI : 10.1046/j.1365-294x.1998.00367.xThe aim of this work was to determine the impact of wild type along with functionally and non-functionally modified Pseudomonas fluorescens strains in the rhizosphere. The wild type F113 strain carried a gene encoding the production of the antibiotic 2,4 diacetylphloroglucinol (DAPG) useful in plant disease control, and was marked with a lacZY gene cassette. The first modified strain was a functional modification of strain F113 with repressed production of DAPG, creating the DAPG negative strain F113 G22. The second paired comparison was a non-functional modification of wild type (unmarked) strain SBW25, constructed to carry marker genes only, creating strain SBW25 EeZY-6KX. Significant perturbations were found in the indigenous bacterial population structure, with the F113, (DAPG+) strain causing a shift towards slower growing colonies (K strategists) compared with the non-antibiotic producing derivative (F113 G22) and the SBW25 strains. The DAPG+ strain also significantly reduced, in comparison with the other inocula, the total Pseudomonas populations but did not affect the total microbial populations. The survival of F113 and F113 G22 were an order of magnitude lower than the SBW 25 strains. The DAPG+ strain caused a significant decrease in the shoot to root ratio in comparison to the control and other inoculants, indicating plant stress. F113 increased soil alkaline phosphatase, phosphodiesterase and aryl sulphatase activities compared to the other inocula, which themselves reduced the same enzyme activities compared to the control. In contrast to this, the -glucosidase, -galactosidase and N-acetyl glucosaminidase activities decreased with the inoculation of the DAPG+ strain. These results indicate that soil enzymes are sensitive to the impact of GMM inoculation.Peer reviewe

Development of Materials for Fused Deposition Modeling

No abstract availabl

Instant Messenger Friends? Social Relationship Behavior Differences Between Two Countries

Canadian and U.S. respondents’ social behavior resulting from communication tools is examined.  Results suggest that Canadians are less likely to use social communication tools to develop new relationships

Mycobacterium marinum phthiocerol dimycocerosates enhance macrophage phagosomal permeabilization and membrane damage

Phthiocerol dimycocerosates (PDIMs) are a class of mycobacterial lipids that promote virulence in Mycobacterium tuberculosis and Mycobacterium marinum. It has recently been shown that PDIMs work in concert with the M. tuberculosis Type VII secretion system ESX-1 to permeabilize the phagosomal membranes of infected macrophages. As the zebrafish-M. marinum model of infection has revealed the critical role of PDIM at the host-pathogen interface, we set to determine if PDIMs contributed to phagosomal permeabilization in M. marinum. Using an ΔmmpL7 mutant defective in PDIM transport, we find the PDIM-ESX-1 interaction to be conserved in an M. marinum macrophage infection model. However, we find PDIM and ESX-1 mutants differ in their degree of defect, with the PDIM mutant retaining more membrane damaging activity. Using an in vitro hemolysis assay—a common surrogate for cytolytic activity, we find that PDIM and ESX-1 differ in their contributions: the ESX-1 mutant loses hemolytic activity while PDIM retains it. Our observations confirm the involvement of PDIMs in phagosomal permeabilization in M. marinum infection and suggest that PDIM enhances the membrane disrupting activity of pathogenic mycobacteria and indicates that the role they play in damaging phagosomal and red blood cell membranes may differ

Competence Checking for the Global E-Service Society Using Games

We study the problem of checking the competence of communicative agents operating in a global society in order to receive and offer electronic services. Such a society will be composed of local sub-societies that will often be semi-open, viz., entrance of agents in a semi-open society is conditional to specific admission criteria. Assuming that a candidate agent provides an abstract description of their communicative skills, we present a test that a controller agent could perform in order to decide if a candidate agent should be admitted. We formulate this test by revisiting an existing knowledge representation framework based on games specified as extended logic programs. The resulting framework finds useful application in complex and inter-operable web-services construed as semi-open societies in support of the global vision known as the Semantic Web

SU(3) breaking in hyperon transition vector form factors

We present a calculation of the SU(3)-breaking corrections to the hyperon transition vector form factors to $\mathcal{O}(p^4)$ in heavy baryon chiral perturbation theory with finite-range regularisation. Both octet and decuplet degrees of freedom are included. We formulate a chiral expansion at the kinematic point $Q^2=-(M_{B_1}-M_{B_2})^2$, which can be conveniently accessed in lattice QCD. The two unknown low-energy constants at this point are constrained by lattice QCD simulation results for the $\Sigma^-\rightarrow n$ and $\Xi^0\rightarrow \Sigma^+$ transition form factors. Hence we determine lattice-informed values of $f_1$ at the physical point. This work constitutes progress towards the precise determination of $|V_{us}|$ from hyperon semileptonic decays