Carbohydrate metabolism in the liver of rats in food deprivation and experimental diabetes

In experiments with starving rats (Rattus rattus L.) and rats with alloxan-induced diabetes, the activity of enzymes and the contents of metabolites of the main metabolic pathways have been studied. It has been shown that adaptation of carbohydrate metabolism to these stress conditions has common trends: intensification of gluconeogenetic processes and glyoxylate cycle induction are observed against the background of decrease in the activities of glycolytic enzymes and the pentose phosphate pathway. A hypothetical mechanism of adaptation of rat liver cell metabolism to a deficiency of glucose as the main energy substrate is proposed.     

Separating the wheat from the chaff: unbiased filtering of background tandem mass spectra improves protein identification

Only a small fraction of spectra acquired in LC-MS/MS runs matches peptides from target proteins upon database searches. The remaining, operationally termed background, spectra originate from a variety of poorly controlled sources and affect the throughput and confidence of database searches. Here, we report an algorithm and its software implementation that rapidly removes background spectra, regardless of their precise origin. The method estimates the dissimilarity distance between screened MS/MS spectra and unannotated spectra from a partially redundant background library compiled from several control and blank runs. Filtering MS/MS queries enhanced the protein identification capacity when searches lacked spectrum to sequence matching specificity. In sequence-similarity searches it reduced by, on average, 30-fold the number of orphan hits, which were not explicitly related to background protein contaminants and required manual validation. Removing high quality background MS/MS spectra, while preserving in the data set the genuine spectra from target proteins, decreased the false positive rate of stringent database searches and improved the identification of low-abundance proteins.     

The DNLS equation and parametric decay instability

A model that describes the interaction of nonlinear Alfvén packets propagating in opposite directions parallel to the ambient magnetic field is constructed. This model incorporates both (i) the parametric interaction of harmonics propagating in the same direction, which can be responsible for the transportation of the wave energy to the short-wavelength region of the spectrum, and (ii) the parametric interaction of Alfvén waves propagating in opposite directions, which can be responsible for the excitation of backward-propagating waves by the parametric decaylike instability of the forward-propagating fluctuations.     

Monoallelic gene expression in mammals

Three systems of monoallelic gene expression in mammals are known, namely, X-chromosome inactivation, imprinting, and allelic exclusion. In all three systems, monoallelic expression is regulated epigenetically and is frequently directed by long non-coding RNAs (ncRNAs). This review briefs all three systems of monoallelic gene expression in mammals focusing on chromatin modifications, spatial chromosome organization in the nucleus, and the functioning of ncRNAs.     

Structural-functional study of glycine-and-proline-containing peptides (Glyprolines) as potential neuroprotectors

A synthetic scheme for preparation of (Gly-Pro) _n , (Pro-Gly) _n (n = 2, 3), and (Pro-Gly-Pro) _n (n = 1, 2) peptides was elaborated. The effect of the synthesized peptides and the Gly-Pro and Pro-Gly dipeptides on survival of cultured cells of PC12 rat pheochromocytoma was studied under the conditions of oxidative stress induced by brief incubation of the cells with hydrogen peroxide. Peptides of the general formula (Gly-Pro) _n and the Pro-Gly-Pro peptide at a concentration of 0.2–100 μM were shown to decrease the number of damaged cells. The Gly-Pro peptide was the most active and decreased the number of damaged cells by 49% on average at a concentration of 100 μM.     

Top-Down Lipidomics Reveals Ether Lipid Deficiency in Blood Plasma of Hypertensive Patients

Background

Dyslipoproteinemia, obesity and insulin resistance are integrative constituents of the metabolic syndrome and are major risk factors for hypertension. The objective of this study was to determine whether hypertension specifically affects the plasma lipidome independently and differently from the effects induced by obesity and insulin resistance.

Methodology/Principal Findings

We screened the plasma lipidome of 19 men with hypertension and 51 normotensive male controls by top-down shotgun profiling on a LTQ Orbitrap hybrid mass spectrometer. The analysis encompassed 95 lipid species of 10 major lipid classes. Obesity resulted in generally higher lipid load in blood plasma, while the content of tri- and diacylglycerols increased dramatically. Insulin resistance, defined by HOMA-IR >3.5 and controlled for BMI, had little effect on the plasma lipidome. Importantly, we observed that in blood plasma of hypertensive individuals the overall content of ether lipids decreased. Ether phosphatidylcholines and ether phosphatidylethanolamines, that comprise arachidonic (20∶4) and docosapentaenoic (22∶5) fatty acid moieties, were specifically diminished. The content of free cholesterol also decreased, although conventional clinical lipid homeostasis indices remained unaffected.

Conclusions/Significance

Top-down shotgun lipidomics demonstrated that hypertension is accompanied by specific reduction of the content of ether lipids and free cholesterol that occurred independently of lipidomic alterations induced by obesity and insulin resistance. These results may form the basis for novel preventive and dietary strategies alleviating the severity of hypertension.     

Structure of the O-Specific polysaccharide from Shewanella japonica KMM 3601 containing 5,7-Diacetamido-3,5,7,9-tetradeoxy-D-glycero-D-talo-non-2-ulosonic acid

Structure of the O-specific polysaccharide chain of the lipopolysaccharide (LPS) of Shewanella japonica KMM 3601 was elucidated. The initial and O-deacylated LPS as well as a trisaccharide representing the O-deacetylated repeating unit of the O-specific polysaccharide were studied by sugar analysis along with ¹H and ¹³C NMR spectroscopy. The polysaccharide was found to contain a rare higher sugar, 5,7-diacetamido-3,5,7,9-tetradeoxy-d-glycero-d-talo-non-2-ulosonic acid (a derivative of 4-epilegionaminic acid, 4eLeg). The following structure of the trisaccharide repeating unit was established: →4)-α-4eLegp5Ac7Ac-(2→4)-β-d-GlcpA3Ac-(1→3)-β-d-GalpNAc-(1→.     

Investigation of a sulfate transfer during autohydrolysis of a fucoidan from the brown alga Fucus evanescens by tandem ESIMS

A fucoidan from the brown alga Fucus evanescens was effectively depolymerized by autohydrolysis. Negative-ion electrospray ionization mass spectrometry (ESIMS) revealed that the mixture contained sulfated mono- and oligosaccharides with polymerization degree (DP) up to 6, having from 1 to 4 sulfate groups per molecule. The prevalence of oligosaccharides with even DP was observed. It could be explained by the tendency of the 3-linked α-l-fucopyranose residues to hydrolyze faster than 4-linked ones. The intermolecular sulfate transfer during autohydrolysis was detected by ESIMS, when equimolar quantities of d-Rib and d-Glc were added as acceptors. The products were singly-sulfated and hexose was about four times more effective as an acceptor, than pentose. It was impossible to record MS/MS spectra of the sulfate transfer products, since intensities of their ions were too low.