Methionine restriction restores a younger metabolic phenotype in adult mice with alterations in fibroblast growth factor 21

Methionine restriction (MR) decreases body weight and adiposity and improves glucose homeostasis in rodents. Similar to caloric restriction, MR extends lifespan, but is accompanied by increased food intake and energy expenditure. Most studies have examined MR in young animals; therefore, the aim of this study was to investigate the ability of MR to reverse age‐induced obesity and insulin resistance in adult animals. Male C57BL/6J mice aged 2 and 12 months old were fed MR (0.172% methionine) or control diet (0.86% methionine) for 8 weeks or 48 h. Food intake and whole‐body physiology were assessed and serum/tissues analyzed biochemically. Methionine restriction in 12‐month‐old mice completely reversed age‐induced alterations in body weight, adiposity, physical activity, and glucose tolerance to the levels measured in healthy 2‐month‐old control‐fed mice. This was despite a significant increase in food intake in 12‐month‐old MR‐fed mice. Methionine restriction decreased hepatic lipogenic gene expression and caused a remodeling of lipid metabolism in white adipose tissue, alongside increased insulin‐induced phosphorylation of the insulin receptor (IR) and Akt in peripheral tissues. Mice restricted of methionine exhibited increased circulating and hepatic gene expression levels of FGF21, phosphorylation of eIF2a, and expression of ATF4, with a concomitant decrease in IRE1α phosphorylation. Short‐term 48‐h MR treatment increased hepatic FGF21 expression/secretion and insulin signaling and improved whole‐body glucose homeostasis without affecting body weight. Our findings suggest that MR feeding can reverse the negative effects of aging on body mass, adiposity, and insulin resistance through an FGF21 mechanism. These findings implicate MR dietary intervention as a viable therapy for age‐induced metabolic syndrome in adult humans.     

Recent developments and applications of electron transfer dissociation mass spectrometry in proteomics

Electron transfer dissociation (ETD) has been developed recently as an efficient ion fragmentation technique in mass spectrometry (MS), being presently considered a step forward in proteomics with real perspectives for improvement, upgrade and application. Available also on affordable ion trap mass spectrometers, ETD induces specific N–Cα bond cleavages of the peptide backbone with the preservation of the post-translational modifications and generation of product ions that are diagnostic for the modification site(s). In addition, in the last few years ETD contributed significantly to the development of top-down approaches which enable tandem MS of intact protein ions. The present review, covering the last 5 years highlights concisely the major achievements and the current applications of ETD fragmentation technique in proteomics. An ample part of the review is dedicated to ETD contribution in the elucidation of the most common posttranslational modifications, such as phosphorylation and glycosylation. Further, a brief section is devoted to top-down by ETD method applied to intact proteins. As the last few years have witnessed a major expansion of the microfluidics systems, a few considerations on ETD in combination with chip-based nanoelectrospray (nanoESI) as a platform for high throughput top-down proteomics are also presented.     

The interaction graph structure of mass-action reaction networks

Behaviour of chemical networks that are described by systems of ordinary differential equations can be analysed via the associated graph structures. This paper deals with observations based on the interaction graph which is defined by the signs of the Jacobian matrix entries. Some of the important graph structures linked to network dynamics are signed circuits and the nucleus (or Hamiltonian hooping). We use mass-action chemical reaction networks as an example to showcase interesting observations about the aforementioned interaction graph structures. We show that positive circuits and specific nucleus structures (associated to multistationarity) are always present in a great generic class of mass-action chemical and biological networks. The theory of negative circuits remains poorly understood, but there is some evidence that they are indicators of stable periodicity. Here we introduce the concept of non-isolated circuits which indicate the presence of a negative circuit.     

Role of nitric oxide in tolerance to lipopolysaccharide in mice.

The injection of repeated doses of lipopolysaccharide (LPS) results in attenuation of the febrile response, which is called endotoxin tolerance. We tested the hypothesis that nitric oxide (NO) arising from inducible NO synthase (iNOS) plays a role in endotoxin tolerance, using not only pharmacological trials but also genetically engineered mice. Body core temperature was measured by biotelemetry in mice treated with NG-monomethyl-L-arginine (L-NMMA, 40 mg/kg; a nonselective NO synthase inhibitor) or aminoguanidine (AG, 10 mg/kg; a selective iNOS inhibitor) and in mice deficient in the iNOS gene (iNOS KO) mice. Tolerance to LPS was induced by means of three consecutive LPS (100 microg/kg) intraperitoneal injections at 24-h intervals. In wild-type mice, we observed a significant reduction of the febrile response to repeated administration of LPS. Injection of L-NMMA and AG markedly enhanced the febrile response to LPS in tolerant animals. Conversely, iNOS-KO mice repeatedly injected with LPS did not become tolerant to the pyrogenic effect of LPS. These data are consistent with the notion that NO modulates LPS tolerance in mice and that iNOS isoform is involved in NO synthesis during LPS tolerance.     

Calorie restriction effects on silencing and recombination at the yeast rDNA

Aging research has developed rapidly over the past decade, identifying individual genes and molecular mechanisms of the aging process through the use of model organisms and high throughput technologies. Calorie restriction (CR) is the most widely researched environmental manipulation that extends lifespan. Activation of the NAD⁺‐dependent protein deacetylase Sir2 (S ilent I nformation R egulator 2) has been proposed to mediate the beneficial effects of CR in the budding yeast Saccharomyces cerevisiae, as well as other organisms. Here, we show that in contrast to previous reports, Sir2 is not stimulated by CR to strengthen silencing of multiple reporter genes in the rDNA of S. cerevisiae. CR does modestly reduce the frequency of rDNA recombination, although in a SIR2‐independent manner. CR‐mediated repression of rDNA recombination also does not correlate with the silencing of Pol II‐transcribed noncoding RNAs derived from the rDNA intergenic spacer, suggesting that additional silencing‐independent pathways function in lifespan regulation.     

Interdependency of the oxidizability of lipoproteins and peroxidase activity with base excess, HCO3, pH and magnesium in human venous and capillary blood

As continuous production of free radicals and reactive oxygen species is a normal metabolic process, increased metabolism during exercise/workload should increase free radical generation and oxidative stress. Oxidative stress intensity should then depend on the intensity of metabolic stress effects. Intensity of stress is usually reflected in norepinephrine (NE) levels, which correlate linearly and significantly with changes in blood gases, blood buffer systems, blood electrolytes, blood glucose and lactate [Porta, S., Leitner, G., Heidinger, D., Lang, T., Weiss, U., Smolle, K.H., Hasiba, K., 1997. Magnesium w?hrend der Alpinausbildung bringt um 30% bessere Energieverwertung. Magnesium-Bulletin 19(2), 59-61]. Those parameters were used in an open study design to screen 64 subjects for metabolic stress effects along with their antioxidative capacity using both venous and capillary blood. To compare venous and capillary blood, we took venous blood samples from 12 healthy volunteers and capillary blood from 52 other healthy subjects. To show whether free radical changes indeed go along with metabolic stress effects, we tried to quantify relations between metabolic stress effects and oxidative stress by linear correlations. In conclusion, both venous and capillary blood are suitable for determining at least those parameters of the oxidative state that we used. All significant correlations of peroxidase activity and oxidation lag time (OLT) with pH, bicarbonate (HCO3), base excess (BE) and magnesium (Mg) indicate that free radical production increases with metabolism. Those relationships could help to evaluate the oxidative state more precisely.     

RNA STRAND: The RNA Secondary Structure and Statistical Analysis Database

Background  

The ability to access, search and analyse secondary structures of a large set of known RNA molecules is very important for deriving improved RNA energy models, for evaluating computational predictions of RNA secondary structures and for a better understanding of RNA folding. Currently there is no database that can easily provide these capabilities for almost all RNA molecules with known secondary structures.     

Expression of manganese lipoxygenase in Pichia pastoris and site-directed mutagenesis of putative metal ligands

Manganese lipoxygenase is secreted by the fungus Gaeumannomyces graminis. We expressed the enzyme in Pichia pastoris, which secreted approximately 30 mg Mn-lipoxygenase/L culture medium in fermentor. The recombinant lipoxygenase was N- and O-glycosylated (80-100 kDa), contained approximately 1 mol Mn/mol protein, and had similar kinetic properties (K(m) approximately 7.1 microM alpha-linolenic acid and V(max) 18 nmol/min/microg) as the native Mn-lipoxygenase. Mn-lipoxygenase could be quantitatively converted, presumably by secreted Pichia proteases, to a smaller protein (approximately 67 kDa) with retention of lipoxygenase activity (K(m) approximately 6.4 microM alpha-linolenic acid and V(max) approximately 12 nmol/min/microg). Putative manganese ligands were investigated by site-directed mutagenesis. The iron ligands of soybean lipoxygenase-1 are two His residues in the sequence HWLNTH, one His residue and a distant Asn residue in the sequence HAAVNFGQ, and the C-terminal Ile residue. The homologous sequences of Mn-lipoxygenase are H274VLFH278 and H462HVMN466QGS, respectively, and the C-terminal amino acid is Val-602. The His274Gln, His278Glu, His462Glu, and the Val-602 deletion mutants of Mn-lipoxygenase were inactive, and had lost >95% of the manganese content. His-463, Asn-466, and Gln-467 did not appear to be critical for Mn-lipoxygenase activity, as His463Gln, Asn466Gln, Asn466Leu, and Gln467Asn mutants metabolized alpha-linolenic acid to 11- and 13-hydroperoxylinolenic acids. We conclude that His-274, His-278, His-462, and Val-602 likely coordinate manganese.     

Group members' assessment of their conductor in small analytic group

In this pilot study the authors present the group members' assessment of their conductor in group analysis--the treatment conducted in accordance with concept >group-as-a-whole< of S. H. Foulkes. There will be presented the results obtained by scale for evaluation of characteristics of the group therapist. In the scale, developed by the authors of the study, there were 30 items and by factorial analysis it gave three interpretable factors: authenticity, empathy and distrust. By self-evaluation the members of three small groups, i.e. 20 patients, ranked characteristics of their conductor. The patients, assessing the degree of their accordance with 30 items of the evaluation scale, expressed whether and how much they experienced their conductor as an authentic, empathic and trustworthy person. While in the beginning of the group analytic process the conductor's role was important, his importance decreased as the group-as-a-whole developed. Group experience became more important than the conductor. In other words, the group itself became the therapist, what is one more the proof of the Foulkes' concept of >the group-as-a-whole<.     

Thermodynamically based DNA strand design

We describe a new algorithm for design of strand sets, for use in DNA computations or universal microarrays. Our algorithm can design sets that satisfy any of several thermodynamic and combinatorial constraints, which aim to maximize desired hybridizations between strands and their complements, while minimizing undesired cross-hybridizations. To heuristically search for good strand sets, our algorithm uses a conflict-driven stochastic local search approach, which is known to be effective in solving comparable search problems. The PairFold program of Andronescu et al. [M. Andronescu, Z. C. Zhang and A. Condon (2005) J. Mol. Biol., 345, 987–1001; M. Andronescu, R. Aguirre-Hernandez, A. Condon, and H. Hoos (2003) Nucleic Acids Res., 31, 3416–3422.] is used to calculate the minimum free energy of hybridization between two mismatched strands. We describe new thermodynamic measures of the quality of strand sets. With respect to these measures of quality, our algorithm consistently finds, within reasonable time, sets that are significantly better than previously published sets in the literature.