Toxicity and SOS response to ELF magnetic field and nalidixic acid in E. coli cells

Extremely low frequency (ELF) magnetic fields have previously been shown to affect conformation of chromatin and cell proliferation. Possible genotoxic and carcinogenic effects of ELF have also been discussed and tested. In this study, we analyzed the effect of ELF on chromatin conformation in E. coli GE499 cells by the anomalous viscosity time dependence (AVTD) technique. Possible genotoxic ELF effects at the specific combination of static and ELF magnetic fields, that has been proven to have effects on chromatin conformation, were investigated by clonogenic assay, cell growth kinetics, and analysis of SOS-response using inducible recA-lacZ fusion and the β-galactosidase assay. Genotoxic agent nalidixic acid (NAL) was used as positive control and in combination with ELF. Nalidixic acid at 3-30μg/ml decreased the AVTD peaks and induced cytotoxic effect. In contrast to NAL, ELF increased AVTD, stimulated cell growth, and increased cloning efficiency. These effects depended on frequency within the frequency range of 7-11Hz. While NAL induced SOS response, ELF exposure did not induce the recA-lacZ fusion. Exposure to ELF did not modify the genotoxic effects of NAL either. All together, the data show that ELF, under specific conditions of exposure, acted as nontoxic but cell growth stimulating agent.     

Microbiological and production characteristics of the high-temperature Kongdian petroleum reservoir revealed during field trial of biotechnology for the enhancement of oil recovery

Microbiological technology for the enhancement of oil recovery based on the activation of the stratal microflora was tested in the high-temperature horizons of the Kongdian bed (60°C) of the Dagang oil-field (China). This biotechnology consists in the pumping of a water-air mixture and nitrogen and phosphorus mineral salts into the oil stratum through injection wells in order to stimulate the activity of the stratal microflora which produce oil-releasing metabolites. Monitoring of the physicochemical, microbiological, and production characteristics of the trial site has revealed large changes in the ecosystem as a result of the application of biotechnology. The cell numbers of thermophilic hydrocarbon-oxidizing, fermentative, sulfate-reducing, and methanogenic microorganisms increased 10–10000-fold. The rates of methanogenesis and sulfate reduction increased in the near-bottom zone of the injection wells and of some production wells. The microbial oil transformation was accompanied by the accumulation of bicarbonate ions, volatile fatty acids, and biosurfactants in the formation waters, as well as of CH₄ and CO₂ both in the gas phase and in the oil. Microbial metabolites promoted the additional recovery of oil. As a result of the application of biotechnology, the water content in the production liquid from the trial site decreased, and the oil content increased. This allowed the recovery of more than 14000 tons of additional oil over 3.5 years.     

Virtual slit scanning microscopy

We present a novel slit scanning confocal microscope with a CCD camera image sensor and a virtual slit aperture for descanning that can be adjusted during post-processing. A very efficient data structure and mathematical criteria for aligning the virtual aperture guarantee the ease of use. We further introduce a method to reduce the anisotropic lateral resolution of slit scanning microscopes. System performance is evaluated against a spinning disk confocal microscope on identical specimens. The virtual slit scanning microscope works as the spinning disk type and outperforms on thick specimens.     

A benefit-finding intervention for family caregivers of persons with Alzheimer disease: study protocol of a randomized controlled trial

Background

Patients with ST-elevation myocardial infarction (STEMI) not treated with primary or rescue percutaneous coronary intervention (PCI) are at risk for recurrent ischemia, especially when viability in the infarct-area is present. Therefore, an invasive strategy with PCI of the infarct-related coronary artery in patients with viability would reduce the occurrence of a composite end point of death, reinfarction, or unstable angina (UA).

Methods

Patients admitted with an (sub)acute myocardial infarction, who were not treated by primary or rescue PCI, and who were stable during the first 48 hours after the acute event, were screened for the study. Eventually, we randomly assigned 216 patients with viability (demonstrated with low-dose dobutamine echocardiography) to an invasive or a conservative strategy. In the invasive strategy stenting of the infarct-related coronary artery was intended with abciximab as adjunct treatment. Seventy-five (75) patients without viability served as registry group. The primary endpoint was the composite of death from any cause, recurrent myocardial infarction (MI) and unstable angina at one year. As secondary endpoint the need for (repeat) revascularization procedures and anginal status were recorded.

Results

The primary combined endpoint of death, recurrent MI and unstable angina was 7.5% (8/106) in the invasive group and 17.3% (19/110) in the conservative group (Hazard ratio 0.42; 95% confidence interval [CI] 0.18-0.96; p = 0.032). During follow up revascularization-procedures were performed in 6.6% (7/106) in the invasive group and 31.8% (35/110) in the conservative group (Hazard ratio 0.18; 95% CI 0.13-0.43; p < 0.0001). A low rate of recurrent ischemia was found in the non-viable group (5.4%) in comparison to the viable-conservative group (14.5%). (Hazard-ratio 0.35; 95% CI 0.17-1.00; p = 0.051).

Conclusion

We demonstrated that after acute MI (treated with thrombolysis or without reperfusion therapy) patients with viability in the infarct-area benefit from a strategy of early in-hospital stenting of the infarct-related coronary artery. This treatment results in a long-term uneventful clinical course. The study confirmed the low risk of recurrent ischemia in patients without viability.

Trial registration

ClinicalTrials.gov: NCT00149591.     

鼠李糖脂的表面化学和生物合成及其在垃圾堆肥中的应用展望

鼠李糖脂是生物表面活性剂中一类非常重要而应用广泛的微生物发酵产物,在环境污染修复中需求量越来越多。针对近十年来国内外对鼠李糖脂生物表面活性剂的研究,较系统地总结了其化学结构、性质、生物合成机理及产量调节方法,及大规模生产鼠李糖脂的基础研究工作,并对其在城市生活垃圾堆肥中的应用做了展望。     

The properties of hydrocarbon-oxidizing bacteria isolated from the oilfields of Tatarstan, western Siberia, and Vietnam

Eleven strains of hydrocarbon-oxidizing bacteria, isolated from oilfields and representing the genera Rhodococcus, Gordonia, Dietzia, and Pseudomonas, were characterized as mesophiles and neutrophiles. Rhodococci were halotolerant microorganisms growing in a media containing up to 15% NaCl. All the strains oxidized n-alkanes of crude oil. An influence of the cultivation temperatures (28 or 45°C) and organic supplements on the degradation of C₁₂-C₃₀ n-alkanes in oxidized oil by two bacterial strains of the genus Pseudomonas was shown. The introduction of acetate, propionate, butyrate, ethanol, and sucrose led mainly to decreased oxidation of petroleum paraffins. At certain cultivation temperatures, the addition of volatile fatty acid salts increased the content of certain n-alkanes in oxidized oil as compared to crude oil.     

Antagonistic Interactions between Stress Factors during the Growth of Microorganisms under Conditions Simulating the Parameters of Their Natural Ecotopes

Two stress factors, hypoxia (microaerobic conditions) and a high salt concentration, if applied simultaneously to aerobic microorganisms, display an antagonistic mode of interaction. As a result, the NaCl level that is usually optimal for moderate halophiles (5–6 %) becomes optimal for the growth of weak halophiles (Rhodococcus erythropolis and Shewanella sp. CN32); the halotolerant yeast Yarrowia lypolytica acquires halophilic properties (with a growth optimum at a NaCl concentration of 10%), and the growth rate of the extremely halophilic Halobacterium salinarum increases at supraoptimal salt concentrations (25–34%). This phenomenon is apparently due to multiple changes in metabolic reactions. In particular, high salt concentrations suppress respiration and the formation of enzymes (superoxide dismutase and catalase) that protect the cell from toxic oxygen species. Therefore, establishment of microaerobic conditions compensates for the loss of these protective mechanisms and enables cell growth at higher salt concentrations than under aerobic conditions. Of some importance can also be the increase in the intracellular concentrations of osmoprotectants caused by the suppression of their intracellular oxidation. The implications of this phenomenon for the ecophysiology of microorganisms (including oil-oxidizing species) and for the classification of weak and moderate halophiles are discussed.     

Nonglucosylated oligosaccharides are transferred to protein in MI8-5 Chinese hamster ovary cells

A CHO mutant MI8-5 was found to synthesize Man9-GlcNAc2-P-P-dolichol rather than Glc3Man9GlcNAc2-P-P-dolichol as the oligosaccharide-lipid intermediate in N-glycosylation of proteins. MI8-5 cells were incubated with labeled mevalonate, and the prenol was found to be dolichol. The mannose-labeled oligosaccharide released from oligosaccharide-lipid of MI8-5 cells was analyzed by HPLC and alpha-mannosidase treatment, and the data were consistent with a structure of Man9GlcNAc2. In addition, MI8-5 cells did not incorporate radioactivity into oligosaccharide- lipid during an incubation with tritiated galactose, again consistent with MI8-5 cells synthesizing an unglucosylated oligosaccharide-lipid. MI8-5 cells had parental levels of glucosylphosphoryldolichol synthase activity. However, in two different assays, MI8-5 cells lacked dolichol- P-Glc:Man9GlcNAc2-P-P-dolichol glucosyltransferase activity. MI8-5 cells were found to synthesize glucosylated oligosaccharide after they were transfected with Saccharomyces cerevisiae ALG 6, the gene for dolichol-P-Glc:Man9GlcNAc2-P-P-dolichol glucosyltransferase. MI8-5 cells were found to incorporate mannose into protein 2-fold slower than parental cells and to approximately a 2-fold lesser extent.