Mutation of a LysR-type regulator of antifungal activity results in a growth advantage in stationary phase phenotype in Pseudomonas aureofaciens PA147-2

The growth advantage in stationary phase (GASP) phenotype was shown to be present in two mutants lacking the antifungal phenotype (Af(-) mutants) of Pseudomonas aureofaciens PA147-2. Complementation demonstrated a correlation between GASP and the antifungal defect in one strain but not in the second. Sequence analysis revealed the Af(-) GASP strain had a mutation in a gene (finR) encoding a LysR-type regulator. Antifungal-minus mutants arose in starved cultures, and those aged cultures had increased fitness. Taken together, the results show that there are at least two paths to the GASP phenotype in P. aureofaciens, one of which results in a concomitant loss of the antifungal phenotype.     

Expression of the Antifeeding Gene anfA1 in Serratia entomophila Requires RpoS

The rpoS gene of Serratia entomophila BC4B was cloned and used to create rpoS-mutant strain BC4BRS. Larvae of the New Zealand grass grub Costelytra zealandica infected with BC4BRS became amber colored but continued to feed, albeit to a lesser extent than infected larvae. Subsequently, we found that expression of the antifeeding gene anfA1 in trans was substantially reduced in BC4BRS relative to that in the parental strain BC4B. Our data show that a functional rpoS gene is vital for full expression of anfA1 and for development of the antifeeding component of amber disease.     

Diversity,Antimicrobial Action and Structure-Activity Relationship of Buffalo Cathelicidins

Cathelicidins are an ancient class of antimicrobial peptides (AMPs) with broad spectrum bactericidal activities. In this study, we investigated the diversity and biological activity of cathelicidins of buffalo, a species known for its disease resistance. A series of new homologs of cathelicidin4 (CATHL4), which were structurally diverse in their antimicrobial domain, was identified in buffalo. AMPs of newly identified buffalo CATHL4s (buCATHL4s) displayed potent antimicrobial activity against selected Gram positive (G+) and Gram negative (G-) bacteria. These peptides were prompt to disrupt the membrane integrity of bacteria and induced specific changes such as blebing, budding, and pore like structure formation on bacterial membrane. The peptides assumed different secondary structure conformations in aqueous and membrane-mimicking environments. Simulation studies suggested that the amphipathic design of buCATHL4 was crucial for water permeation following membrane disruption. A great diversity, broad-spectrum antimicrobial action, and ability to induce an inflammatory response indicated the pleiotropic role of cathelicidins in innate immunity of buffalo. This study suggests short buffalo cathelicidin peptides with potent bactericidal properties and low cytotoxicity have potential translational applications for the development of novel antibiotics and antimicrobial peptidomimetics.     

Biosorption of Cadmium by Live and Dead <Emphasis Type="Italic">Spirulina</Emphasis>: IR Spectroscopic,Kinetics, and SEM Studies

Cadmium is an important environmental pollutant and a potent toxicant to bacteria, algae, and fungi. Mechanisms of Cd⁺² toxicity and resistance are variable, depending on the organism. The present work reports the use of live and dead Spirulina sp. for sorption of Cd⁺². This investigation shows that this biomass takes up substantial amount of Cd⁺² ions. IR spectroscopic study, kinetics models, Langmuir & Freundlich adsorption isotherms, scanning electron microscopic analysis of Spirulina sp., and the Spirulina sp. treated with different metal ions have been employed to understand the sorption mechanism. Infrared spectra of live Spirulina treated with Cd⁺² ions for different lengths of time have been taken to understand the time dependency of metal interaction.     

Methylprednisolone and Indomethacin Inhibit Oxidative Stress Mediated Apoptosis in Rat C6 Glioblastoma Cells

Glioblastoma patients receive anti-inflammatory agent for alleviation of vasogenic edema and pain prior to surgery, radiotherapy, and chemotherapy. Oxidative stress is an important mechanism of action of some chemotherapeutic agents in the treatment of glioblastoma. So, we examined the modulatory effects of methylprednisolone (MP, a steroidal anti-inflammatory agent) and indomethacin (IM, a non-steroidal anti-inflammatory agent) on apoptosis in rat C6 glioblastoma cells following oxidative stress with hydrogen peroxide (H₂O₂). Exposure of C6 cells to 1 mM H₂O₂ for 24 h caused significant amounts of morphological and biochemical features of apoptosis. Expressions of Bax and Bcl-2 at mRNA and protein levels were altered resulting in an increase in Bax : Bcl-2 ratio in apoptotic cells, which also exhibited overexpression of 80 kDa calpain and an increase in calpain-cleaved 145 kDa α-spectrin breakdown product. Immunofluorescent and propidium iodide labeling detected caspase-3-p20 fragment in apoptotic cells, indicating activation of caspase-3 as well. Treatment of cells with 1 μM MP or 10 μM IM alone did not induce apoptosis. Pretreatment (1 h) with either 1 μM MP or 10 μM IM significantly inhibited H₂O₂ mediated apoptosis in C6 cells. Thus, pretreatment of glioblastoma with an anti-inflammatory agent, either steroidal or non-steroidal, may compromise the action of a chemotherapeutic agent that mediates therapeutic action via oxidative stress.     

Functional analyses of RNA structures shared between the internal ribosome entry sites of hepatitis C virus and the picornavirus porcine teschovirus 1 Talfan

The internal ribosome entry site (IRES) of porcine teschovirus 1 (PTV-1), a member of the Picornaviridae family, is quite distinct from other well-characterized picornavirus IRES elements, but it displays functional similarities to the IRES from hepatitis C virus (HCV), a member of the Flaviviridae family. In particular, a dominant negative mutant form of eIF4A does not inhibit the activity of the PTV-1 IRES. Furthermore, there is a high level (ca. 50%) of identity between the PTV-1 and HCV IRES sequences. A secondary-structure model of the whole PTV-1 IRES has been derived which includes a pseudoknot. Validation of specific features within the model has been achieved by mutagenesis and functional assays. The differences and similarities between the PTV-1 and HCV IRES elements should assist in defining the critical features of this type of IRES.     

Biodegradation of pyrene by Mycobacterium frederiksbergense in a two-phase partitioning bioreactor system

Biodegradation of pyrene by Mycobacterium frederiksbergense was studied in a two-phase partitioning bioreactor (TPPB) using silicone oil as non-aqueous phase liquid (NAPL). The TPPB achieved complete biodegradation of pyrene; and during the active degradation phase, utilization rates of 270, 230, 139, 82 mg l(-1)d(-1) for initial pyrene loading concentrations (in NAPL) of 1000, 600, 400 and 200 mg l(-1), respectively, were obtained. The degradation rates achieved using M. frederiksbergense in TPPB were much higher than the literature reported values for an ex situ PAH biodegradation system operated using single and pure microbial species. The degradation data was fitted to simple Monod, logistic, logarithmic, three-half-order kinetic models. Among these models, only exponential growth form of the three-half-order kinetic model provided the best fit to the entire degradation profiles with coefficient of determination (R2) value >0.99. From the experimental findings, uptake of pyrene by the microorganism in TPPB was proposed to be a non-interfacial based mechanism.