Isolation of copper oxide (CuO) nanoparticles resistant Pseudomonas strains from soil and investigation on possible mechanism for resistance

The present study deals with isolation and characterization of copper oxide nanoparticles resistant Pseudomonas strains that were isolated from the soil collected from mining and refining sites of Sarcheshmeh copper mine in the Kerman Province of Iran. The three isolates were selected based on high level of copper oxide nanoparticles (CuO NPs) resistance. The isolates were authentically identified as Pseudomonas fluorescens CuO-1, Pseudomonas fluorescens CuO-2 and Pseudomonas sp. CuO-3 by morphological, biochemical and 16S rDNA gene sequencing analysis. The growth pattern of these isolates with all the studied CuO NPs concentrations was similar to that of control (without CuO NPs) indicating that CuO NPs would not affect the growth of isolated strains. A reduction in the amount of exopolysaccharides was observed after CuO NPs—P. fluorescens CuO-1 culture supernatant interaction. The Fourier transform infrared spectroscopy (FT-IR) peaks for the exopolysaccharides extracted from the bacterial culture supernatant and the interacted CuO NPs were almost similar. The exopolysaccharide capping of the CuO NPs was confirmed by FT-IR and X-ray diffraction analysis. The study of bacterial exopolysaccharides capped CuO NPs with E. coli PTCC 1338 and S. aureus PTCC 1113 showed less toxicity compared to uncoated CuO NPs. Our study suggests that the capping of nanoparticles by bacterially produced exopolysaccharides serve as the probable mechanism of tolerance.     

Murine Efficacy and Pharmacokinetic Evaluation of the Flaviviral NS5 Capping Enzyme 2-Thioxothiazolidin-4-One Inhibitor BG-323

Arthropod-borne flavivirus infection continues to cause significant morbidity and mortality worldwide. Identification of drug targets and novel antiflaviviral compounds to treat these diseases has become a global health imperative. A previous screen of 235,456 commercially available small molecules identified the 2-thioxothiazolidin-4-one family of compounds as inhibitors of the flaviviral NS5 capping enzyme, a promising target for antiviral drug development. Rational drug design methodologies enabled identification of lead compound BG-323 from this series. We have shown previously that BG-323 potently inhibits NS5 capping enzyme activity, displays antiviral effects in dengue virus replicon assays and inhibits growth of West Nile and yellow fever viruses with low cytotoxicity in vitro. In this study we further characterized BG-323’s antiviral activity in vitro and in vivo. We found that BG-323 was able to reduce replication of WNV (NY99) and Powassan viruses in culture, and we were unable to force resistance into WNV (Kunjin) in long-term culture experiments. We then evaluated the antiviral activity of BG-323 in a murine model. Mice were challenged with WNV NY99 and administered BG-323 or mock by IP inoculation immediately post challenge and twice daily thereafter. Mice were bled and viremia was quantified on day three. No significant differences in viremia were observed between BG-323-treated and control groups and clinical scores indicated both BG-323-treated and control mice developed signs of illness on approximately the same day post challenge. To determine whether differences in in vitro and in vivo efficacy were due to unfavorable pharmacokinetic properties of BG-323, we conducted a pharmacokinetic evaluation of this small molecule. Insights from pharmacokinetic studies indicate that BG-323 is cell permeable, has a low efflux ratio and does not significantly inhibit two common cytochrome P450 (CYP P450) isoforms thus suggesting this molecule may be less likely to cause adverse drug interactions. However, the T_1/2 of BG-323 was suboptimal and the percent of drug bound to plasma binding proteins was high. Future studies with BG-323 will be aimed at increasing the T_1/2 and determining strategies for mitigating the effects of high plasma protein binding, which likely contribute to low in vivo efficacy.     

Immune responses of great sturgeon Huso huso to Aeromonas hydrophila bacterin

The immunocompetent cell population, lysozyme activity, chemiluminescence response and antibody titre were assessed in great sturgeon Huso huso after intraperitoneal immunization with formalin-inactivated whole cells of Aeromonas hydrophila . Generally an increase was seen in indices of immunocomptent cell counts of immunized fish compared to the control group. The neutrophil count was higher in immunized fish from day 29. Lysozyme activity in liver and spleen samples of immunized fish was initially significantly higher than unimmunized fish, but was not different in serum and kidney. Antibody titre and respiratory burst in immunized fish were mainly significantly higher than unimmunized fish.     

The Vital Role of Blood Flow-Induced Proliferation and Migration in Capillary Network Formation in a Multiscale Model of Angiogenesis

Sprouting angiogenesis and capillary network formation are tissue scale phenomena. There are also sub-scale phenomena involved in angiogenesis including at the cellular and intracellular (molecular) scales. In this work, a multiscale model of angiogenesis spanning intracellular, cellular, and tissue scales is developed in detail. The key events that are considered at the tissue scale are formation of closed flow path (that is called loop in this article) and blood flow initiation in the loop. At the cellular scale, growth, migration, and anastomosis of endothelial cells (ECs) are important. At the intracellular scale, cell phenotype determination as well as alteration due to blood flow is included, having pivotal roles in the model. The main feature of the model is to obtain the physical behavior of a closed loop at the tissue scale, relying on the events at the cellular and intracellular scales, and not by imposing physical behavior upon it. Results show that, when blood flow is considered in the loop, the anastomosed sprouts stabilize and elongate. By contrast, when the loop is modeled without consideration of blood flow, the loop collapses. The results obtained in this work show that proper determination of EC phenotype is the key for its survival.     

Variation of nitrogenase activity, photosynthesis and pigmentation of the cyanobacterium Fischerella ambigua strain FS18 under different irradiance and pH values

Summary Our objective was to evaluate the physiological response of Fischerella ambigua FS18 to the combined influence of pH (5, 7 and 9) and light intensity (3 and 300 μmol photon m⁻² s⁻¹). Growth rates were similar at pH 9 and pH 7. There was no growth at pH 5. Increasing light intensity did not have any considerable influence on growth rates. Chlorophyll concentration was higher at pH 7 at all light intensities. Chlorophyll concentration decreased with increasing light intensity from 3 to 300 μmol photon m⁻² s⁻¹. Synthesis of the phycobiliproteins (PBP), phycocyanin (PC) and allophycocyanin (APC) had the highest rate in pH 7. Increasing irradiance decreased the concentrations of all PBPs. The light-saturated photosynthetic rate was clearly higher at high light intensity. With respect to nitrogenase activity, the highest rate was at pH 9 and 300 μmol photon m⁻² s⁻¹. Irradiance did not affect significantly this activity at pH 7. This cyanobacterium seems to be alkalophilic with maximum nitrogenase activity and photosynthesis at pH 9. It can also adapt its photosynthetic apparatus to the variable factors that are found in rice fields.     

A case of amniotic membrane transplantation in non-healing Nocardia asteroides keratitis

A patient with severe non-healing microscopically proven Nocardia keratitis was treated with maximal topical amikacin followed by amniotic membrane transplantation (AMT) 2 months later (single-layer epithelial side-down). Epithelial healing was achieved, but neovascularization continued. This case report indicates that AMT combined with topical antibiotic provides pain relief and allows epithelial healing in severe Nocardia keratitis.     

Evaluation of antioxidant properties and total phenolic contents of some strains of microalgae

Antioxidant activities of both cells and extracellular substances were evaluated in 12 soil-isolated strains of microalgae according to FRAP and DPPH-HPLC assays. Their total phenolic contents were also determined by Folin–Ciocalteu method. Extractions were performed with hexane, ethyl acetate, and water. The results of FRAP assay showed that algal cells contained considerable amounts of antioxidants from 0.56 ± 0.06 to 31.06 ± 4.00 μmol Trolox g⁻¹ for Microchaete tenera hexane extract and Chlorella vulgaris water extract, respectively. In water fractions of extracellular substances, the antioxidants were from 1.30 ± 0.15 μmol Trolox g⁻¹ for Fischerella musicola to 73.20 ± 0.16 μmol Trolox g⁻¹ for Fischerella ambigua. Also, DPPH-HPLC assay represented high antioxidant potential of water fractions. The measured radical-scavenging activities of the studied microalgae were at least 0.15 ± 0.02 in Nostoc ellipsosporum cell mass to a maximum of 109.02 ± 8.25 in C. vulgaris extracellular substance. The amount of total phenolic contents varied in different strains of microalgae and ranged from zero in hexane extract to 19.15 ± 0.04 mg GAE g⁻¹ in C. vulgaris extracellular water fraction. Significant correlation coefficients between two measured parameters indicated that phenolic compounds were a major contributor to the microalgal antioxidant capacities.     

Plant growth-promoting activities of fluorescent pseudomonads,isolated from the Iranian soils

Fluorescent pseudomonads are among the most influencing plant growth-promoting rhizobacteria in plants rhizosphere. In this research work the plant growth-promoting activities of 40 different strains of Pseudomonas fluorescens and Pseudomonas putida, previously isolated from the rhizosphere of wheat (Triticum aestivum L.) and canola (Brassica napus L.) and maintained in the microbial collection of Soil and Water Research Institute, Tehran, Iran, were evaluated. The ability of bacteria to produce auxin and siderophores and utilizing P sources with little solubility was determined. Four strains of Wp1 (P. putida), Cfp10 (Pseudomonas sp.), Wp150 (P. putida), and Wp159 (P. putida) were able to grow in the DF medium with ACC. Thirty percent of bacterial isolates from canola rhizosphere and 33% of bacterial isolates from wheat rhizosphere were able to produce HCN. The results indicate that most of the bacteria, tested in the experiment, have plant growth-promoting activities. This is the first time that such PGPR species are isolated from the Iranian soils. With respect to their great biological capacities they can be used for wheat and canola inoculation in different parts of the world, which is of very important agricultural implications.