Contamination of soils with toxic metals is a major problem on military, industrial, and mining sites worldwide. Of particular interest to the field of bioremediation is the selection of biological ...markers for the end point of remediation. In this microcosm study, we focus on the effect of addition of a mixture of toxic metals (cadmium, cobalt, cesium, and strontium as chlorides) to soil on the population structure and size of the ammonia oxidizers that are members of the beta subgroup of the Proteobacteria (beta-subgroup ammonia oxidizers). In a parallel experiment, the soils were also treated by the addition of five strains of metal-resistant heterotrophic bacteria. Effects on nitrogen cycling were measured by monitoring the NH3 and NH4+ levels in soil samples. The gene encoding the alpha-subunit of ammonia monooxygenase (amoA) was selected as a functional molecular marker for the beta-subgroup ammonia oxidizing bacteria. Community structure comparisons were performed with clone libraries of PCR-amplified fragments of amoA recovered from contaminated and control microcosms for 8 weeks. Analysis was performed by restriction digestion and sequence comparison. The abundance of ammonia oxidizers in these microcosms was also monitored by competitive PCR. All amoA gene fragments recovered grouped with sequences derived from cultured Nitrosospira. These comprised four novel sequence clusters and a single unique clone. Specific changes in the community structure of beta-subgroup ammonia oxidizers were associated with the addition of metals. These changes were not seen in the presence of the inoculated metal-resistant bacteria. Neither treatment significantly altered the total number of beta-subgroup ammonia-oxidizing cells per gram of soil compared to untreated controls. Following an initial decrease in concentration, ammonia began to accumulate in metal-treated soils toward the end of the experiment.
Recent advances in understanding the role and application of bacteria to the remediation of toxic metal and radionuclide contaminated terrestrial environments have come from several avenues. Novel ...species capable of mobilization and immobilization of metal ions have been discovered. Remediation of toxicity has been accelerated by nutrient amendment, the use of chelating agents and novel methods for phosphate amendment. Major advances in the use of natural and genetically engineered species for bioprotection and remediation of organic co-contaminants have been reported. Construction of wetland function continues to be developed for containment and decontamination of wastewaters.
Colitis is associated with alterations in electrolyte and water transport. These changes give rise to some of the symptoms experienced by patients with colitis. Alterations in fluid flux may also ...contribute to increased susceptibility to mucosal injury. Recently, endogenous water channel proteins (aquaporins; AQPs), have been identified in colonic tissue. The expression of AQP4, AQP7 and AQP8 was examined, via reverse transcription/polymerase chain reaction, Western blotting and immunohistochemistry, in a murine model of colitis and in patients with inflammatory bowel disease or infectious colitis. Colitis was induced in C57BL/6 mice by the addition of 2.5% dextran sodium sulphate (DSS) to their drinking water. AQP expression in these mice was assessed following 12 h to 7 days of DSS exposure and during the recovery phase from 1 to 15 days following cessation of DSS exposure. Colonic water transport was measured after 1 and 3 days of DSS and following 7 days of recovery. The expression of AQP4 and AQP8 mRNA was significantly decreased after 12-24 h of DSS exposure and remained depressed throughout the treatment period. Expression of AQP7 was more variable. Protein expression followed a similar pattern to that observed for AQP mRNA. Significant alteration in colonic fluid secretion was correlated with reduced expression of AQP isoforms. Significantly, patients with active ulcerative colonic, Crohn's colitis or infectious colitis had similar dramatic reductions in AQP expression that appeared to be correlated with disease activity. Thus, colonic injury in both mouse and man is associated with a downregulation in AQP expression.
We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| from B0→D*−ℓ+νℓ decays, reconstructed with the full Belle data set of 711 fb−1 integrated luminosity. Two form ...factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)ηEW|Vcb| and the decay form factors, where F(1) is the normalization factor and ηEW is a small electroweak correction. In the CLN parametrization we find F(1)ηEW|Vcb|=(35.06±0.15±0.56)×10−3, ρ2=1.106±0.031±0.007, R1(1)=1.229±0.028±0.009, R2(1)=0.852±0.021±0.006. For the BGL parametrization we obtain F(1)ηEW|Vcb|=(34.93±0.23±0.59)×10−3, which is consistent with the world average when correcting for F(1)ηEW. The branching fraction of B0→D*−ℓ+νℓ is measured to be B(B0→D*−ℓ+νℓ)=(4.90±0.02±0.16)%. We also present a new test of lepton flavor universality violation in semileptonic B decays, B(B0→D*−e+ν)B(B0→D*−μ+ν)=1.01±0.01±0.03. The errors quoted correspond to the statistical and systematic uncertainties, respectively. This is the most precise measurement of F(1)ηEW|Vcb| and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement.
We present experimental and theoretical evidence that varying the local environment and physical structure of dried DNA has a direct impact on its electronic structure. By preparing samples of DNA in ...various solutions, it was possible to alter the type of ions present during the production of the DNA samples. These variations resulted in differences in the local chemical environment of the dried DNA molecules. X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) were used to probe the variations in the electronic structure of DNA samples. DFT calculations of a stack of 10 adenine (A)−thymine (T) nucleobase pairs show that slight structural variations in stacking height have a direct influence on the electronic structure and result in changes to the HOMO−LUMO gap. The effects of these differences in the local environment on the electronic structure are discussed and are related to the results of conductivity measurements of DNA.
Physiological status of microbial mats of the Ebro Delta (Tarragona, Spain) based on the extraction of lipids considered "signature lipid biomarkers" (SLB) from the cell membranes and walls of ...microorganisms has been analyzed. Data from a day-night cycle show significant differences in viable cells countings (PLFA cells counts) ranging from$1.5\times 10^{10}$to 5.0× 1010cells g-1of sediment. Minimum values were observed at 18:00 and 6:00, when physicochemical conditions change drastically. The diversity of the microbial community was assessed by GC/MS analysis of phospholipid fatty acids (PLFA). The ratio of PLFA, representative of Gram-negative bacteria, comprises 47.8% of the total PLFA of the microbial mat community. The remaining PLFA was representative of Gram-positive (10.0%), anaerobic (5.7%), and eukaryotic microorganisms (5.7%), and other common lipids. Two different approaches were used as a comparative study to assess the physiological status of the microbial mats. Two parameters (cyclopropane fatty acids/ω7c monoenoic fatty acids, and measurement of the trans/cis monoenoic PLFA ratio) showed a minimum at midnight, suggesting the highest microbial activity. Higher values were observed at 18:00 and 6:00, coinciding with lower PLFA cell counts.
The manufacture of fine particles of two steroid drugsprogesterone and medroxyprogesterone acetatehas been investigated through the rapid expansion of supercritical solutions (RESS). The motivation ...was the production of particles with improved characteristics for use in the pharmaceutical industry. Solubility data for each drug in supercritical CO2 were measured prior to performing the RESS experiments as these data are essential for accurate experimental design. The solubility data were measured using a dynamic apparatus at pressures between 100 and 240 bar and at 313.1 and 333.1 K. Particles were manufactured by expanding a solution of supercritical CO2 saturated with drug through a micronozzle to pressures of 50 bar or less. A sufficient amount of particles was manufactured to allow particle characterization tests to be completed. Particle size, particle size distribution, and specific surface area were used as assessment measures to compare the product samples obtained in different experimental conditions. The RESS technique produced particles that were significantly smaller than existing samples manufactured using jet-milling.
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