Development and application of a differential method for reliable metabolome analysis in Escherichia coli

Quantitative metabolomics of microbial cultures requires well-designed sampling and quenching procedures. We successfully developed and applied a differential method to obtain a reliable set of metabolome data for Escherichia coli K12 MG1655 grown in steady-state, aerobic, glucose-limited chemostat cultures. From a rigorous analysis of the commonly applied quenching procedure based on cold aqueous methanol, it was concluded that it was not applicable because of release of a major part of the metabolites from the cells. No positive effect of buffering or increasing the ionic strength of the quenching solution was observed. Application of a differential method in principle requires metabolite measurements in total broth and filtrate for each measurement. Different methods for sampling of culture filtrate were examined, and it was found that direct filtration without cooling of the sample was the most appropriate. Analysis of culture filtrates revealed that most of the central metabolites and amino acids were present in significant amounts outside the cells. Because the turnover time of the pools of extracellular metabolites is much larger than that of the intracellular pools, the differential method should also be applicable to short-term pulse response experiments without requiring measurement of metabolites in the supernatant during the dynamic period.     

Fuel-dependent,shape-selective,distinct blue and green photoluminescence from α-Bi2O3 and β-Bi2O3 synthesised using microwave combustion

In the current study, α-Bi₂O₃ and β-Bi₂O₃ were synthesised using a one-step, novel, solid–solid combustion technique. The reaction rate was increased with the use of microwaves (molecular heating) compared to direct or indirect heating. A strong relationship was observed between the fuel, polymorphic structure, shape and optical properties of the synthesised Bi₂O₃. Photoluminescence studies reveal that two major visible emissions are observed for all samples. The two emissions are distinct with a broad peak in blue and a narrow peak in green. The intensity of the green characteristic emission depends strongly on the heating method used for synthesis and is more intense for microwave-synthesised samples.     

Reproductive tissues-specific meta-QTLs and candidate genes for development of heat-tolerant rice cultivars

Plant Molecular Biology - By integrating genetics and genomics data, reproductive tissues-specific and heat stress responsive 35 meta-QTLs and 45 candidate genes were identified, which could be...     

Singlet oxygen damages the function of Photosystem II in isolated thylakoids and in the green alga Chlorella sorokiniana

Photosynthesis Research - Singlet oxygen (1O2) is an important damaging agent, which is produced during illumination by the interaction of the triplet excited state pigment molecules with molecular...     

Baseline morbidity in 2,990 adult African volunteers recruited to characterize laboratory reference intervals for future HIV vaccine clinical trials

Background

An understanding of the health of potential volunteers in Africa is essential for the safe and efficient conduct of clinical trials, particularly for trials of preventive technologies such as vaccines that enroll healthy individuals. Clinical safety laboratory values used for screening, enrolment and follow-up of African clinical trial volunteers have largely been based on values derived from industrialized countries in Europe and North America. This report describes baseline morbidity during recruitment for a multi-center, African laboratory reference intervals study.

Methods

Asymptomatic persons, aged 18–60 years, were invited to participate in a cross-sectional study at seven sites (Kigali, Rwanda; Masaka and Entebbe, Uganda; Kangemi, Kenyatta National Hospital and Kilifi, Kenya; and Lusaka, Zambia). Gender equivalency was by design. Individuals who were acutely ill, pregnant, menstruating, or had significant clinical findings were not enrolled. Each volunteer provided blood for hematology, immunology, and biochemistry parameters and urine for urinalysis. Enrolled volunteers were excluded if found to be positive for HIV, syphilis or Hepatitis B and C. Laboratory assays were conducted under Good Clinical Laboratory Practices (GCLP).

Results and Conclusions

Of the 2990 volunteers who were screened, 2387 (80%) were enrolled, and 2107 (71%) were included in the analysis (52% men, 48% women). Major reasons for screening out volunteers included abnormal findings on physical examination (228/603, 38%), significant medical history (76, 13%) and inability to complete the informed consent process (73, 13%). Once enrolled, principle reasons for exclusion from analysis included detection of Hepatitis B surface antigen (106/280, 38%) and antibodies against Hepatitis C (95, 34%). This is the first large scale, multi-site study conducted to the standards of GCLP to describe African laboratory reference intervals applicable to potential volunteers in clinical trials. Approximately one-third of all potential volunteers screened were not eligible for analysis; the majority were excluded for medical reasons.     

Temperature Gradient Measurements by Using Thermoelectric Effect in CNTs-Silicone Adhesive Composite

This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT) and silicone adhesive. The composite contains CNT and silicon adhesive 1∶1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results.     

Nitric oxide in blood. The nitrosative-oxidative disequilibrium hypothesis on the pathogenesis of cardiovascular disease

There is growing evidence that altered production and/or spatio-temporal distribution of reactive oxidant species and reactive nitrosative species in blood creates oxidative and/or nitrosative stresses in the failing myocardium and endothelium. This contributes to the abnormal cardiac and vascular phenotypes that characterize cardiovascular disease. These derangements at the system level can now be interpreted at the integrated cellular and molecular levels in terms of effects on signaling elements in the heart and vasculature. The end results of nitric oxide/redox disequilibrium have implications for cardiac and vascular homeostasis and may result in the development of atherosclerosis, myocardial tissue remodelling and hypertrophy. Reactive oxygen species/reactive nitrogen species generation is also attributed to the transit from hypertrophic to apoptotic phenotypes, a possible mechanism of myocardial failure. In this review, we highlight the possible roles of altered production and/or spatio-temporal distribution of reactive oxidant species and reactive nitrosative species in blood on the pathogenesis of the failing cardiovascular system.     

Temporal variation in drug interaction between lithium and morphine-induced analgesia

The administration-time-dependent aspects of the drug interaction between lithium and morphine-induced analgesia were studied using the mouse hot-plate test at six different times of day, each scheduled at 4 h intervals. Lithium treatment alone, in doses of 1 to 10 mmol/kg administered intraperitoneally (i.p.) did not significantly alter test latencies compared to the corresponding clock-time in saline-injected controls. Basal pain sensitivity and morphine-induced antinociceptive activity displayed significant circadian rhythms as assessed by the hot-plate response latencies, with higher values occurring during the nocturnal activity than during the daytime rest span. Acute administration of lithium, in a dose of 3 mmol/kg, 30 min prior to morphine dosing did not influence morphine-induced analgesia compared to all the clock-time test-matched morphine groups, except the 9 HALO (Hours After Lights On) one. There was a prominent potentiation of the morphine-induced antinociception at this biological time during combined drug treatment. The latter finding demonstrates that administration-time-dependent differences in drug-drug interactions need to be considered in both experimental designs and clinical settings.