Phospholipids composition in tissues of the root voles Microtus oeconomus inhabiting territories with elevated radioactive background

Phospholipid composition was studied in tissues of root voles Microtus oeconomus Pall. from natural populations inhabiting territories with increased levels of natural radioactivity. Lipid component of biological membranes of animal tissues was shown to have high sensitivity to action of chronic low-intensity irradiation at small doses. Under effect of various damaging factors on the organism, similar changes of membrane state indexes were noted, these changes being due to functioning of the physical-chemical system of cell metabolism regulation by oxidative reactions in membrane lipids. An important role of intrapopulational processes contributing essentially to formation of biological consequences of the low-intensity irradiation of animals in natural habitat was revealed.     

Mechanism of metabolic adaptation

The paper presents results of investigations on some mechanisms of metabolic adaptation in mammals. There are four sections in the tissue metabolic system of acid-base homeostasis: polyamines as factors of metabolic adaptation; significance of carbon dioxide for metabolic response formation in hypobiosis; polyamines metabolism in hypobiosis. Peculiarities of intermediate metabolism have been analyzed in animal tissues under the changes in H+, CO2 and HCO3- concentrations. Basing on a new interpretation of the experimental data and detected regularity in the metabolism, conclusion on the existence of a new acid-base homeostasis system in the tissues has been made. The results of polyamines metabolism investigations in the mammals under the stress have been described. The experimental data make us to believe that changes in polyamines synthesis and ODC activity in particular, is a part of stereotype nonspecific response to any stress impacts and one of the factors of cell metabolic adaptation. Some new data on mechanisms of formation and control of metabolic status of animals in the natural and artificial hibernation have been presented. The key idea is that in the state of hypobiosis the carbon dioxide (HCO3-) appears as a regulatory factor of metabolic adaptation, which is able to realize its action directly via affecting numerous biochemical events. The participation of polyamines in adaptive metabolic response to hybernation factors is suggested. Some peculiarities of ornithine decarboxilase and transglutaminase activity during the different stages of genuine and artificial hypobiosis have been demonstrated.     

The general physiological mechanisms of glutamate influence on the central nervous system

The L-Glutamate, is dicarboxilic amino acid which plays the important role in maintenance of normal functioning of the central nervous system (CNS) in invertebrate and vertebrate animals. It carrying out functions of amphibolic intermediate in biosynthesis and degradation of amino acids and some nitrogenous substances. Besides, L-Glutamate acid possesses a significant role in the regulation of the bioenergetics processes that proceeding in nervous system, due to direct or indirect participations in the reactions of glycolysis, gluconeogenesis, synthesis of ketone bodies and formation of glycogen. Also, L-Glutamate accepts direct participation in realization of a citrate cycle reactions, a respiratory circuit; in conversion of ammonia and it excretion from an organism. However the most important function of the L-Glutamate--its participation in the processes of nervous regulation as excitatory neuromediator in the CNS of invertebrate and vertebrate animals.     

The microbial degradation of cyclohexanecarboxylic acid by a beta-oxidation pathway with simultaneous induction to the utilization of benzoate

The metabolism of cyclohexanecarboxylic acid by a bacterium, designated PRL W19, follows a pathway involving beta-oxidation of coenzyme A intermediates analogous to the classical oxidation of fatty acids. The organism appears to have the property for the constitutive metabolism of caproic acid, and cell extracts contain high levels of the enzymes required for the functioning of the fatty acid cycle. However, the metabolism of cyclohexanecarboxylic acid requires induction by growth or incubation with an appropriate substrate. Extracts of induced cells contain several enzyme activities which are synthesized in response to the induction process. These enzymes include cyclohexanecarboxyl-CoA synthetase, cyclohexanecarboxyl-CoA dehydrogenase, 1-cyclohexenecarboxyl-CoA hydratase, and trans-2-hydroxycyclohexanecarboxyl-CoA dehydrogenase. A characteristics feature of this organism is that it becomes induced for the metabolism of benzoate and catechol during growth on cyclohexanecarboxylic acid, but benzoate does not appear to be an obligatory intermediate in the metabolism of cyclohexanecarboxylic acid.     

Note: Sucrose transport and metabolism in Clostridium beijerinckii NCIMB 8052

Sucrose is the major carbon source in molasses, the traditional substrate employed in the industrial acetone-butanol-ethanol (ABE) fermentation by solventogenic clostridia. The utilization of sucrose by Clostridium beijerinckii NCIMB 8052 was investigated. Extracts prepared from cultures grown on sucrose (but not xylose or fructose) as the sole carbon source possessed sucrose phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) activity. Extract fractionation and reconstitution experiments revealed that the entire sucrose Enzyme II complex resides within the membrane in this organism. Sucrose-6-phosphate hydrolase and fructokinase activities were also detected in sucrose grown cultures. The fructokinase activity, which is required specifically during growth on sucrose, was shown to be inducible under these conditions. A pathway for sucrose metabolism in this organism is proposed.     

The Role of Solution Conditions in the Bacteriophage PP7 Capsid Charge Regulation

We investigate and quantify the effects of pH and salt concentration on the charge regulation of the bacteriophage PP7 capsid. These effects are found to be extremely important and substantial, introducing qualitative changes in the charge state of the capsid such as a transition from net-positive to net-negative charge depending on the solution pH. The overall charge of the virus capsid arises as a consequence of a complicated balance with the chemical dissociation equilibrium of the amino acids and the electrostatic interaction between them, and the translational entropy of the mobile solution ions, i.e., counterion release. We show that to properly describe and predict the charging equilibrium of viral capsids in general, one needs to include molecular details as exemplified by the acid-base equilibrium of the detailed distribution of amino acids in the proteinaceous capsid shell.     

The Role of Solution Conditions in the Bacteriophage PP7 Capsid Charge Regulation

We investigate and quantify the effects of pH and salt concentration on the charge regulation of the bacteriophage PP7 capsid. These effects are found to be extremely important and substantial, introducing qualitative changes in the charge state of the capsid such as a transition from net-positive to net-negative charge depending on the solution pH. The overall charge of the virus capsid arises as a consequence of a complicated balance with the chemical dissociation equilibrium of the amino acids and the electrostatic interaction between them, and the translational entropy of the mobile solution ions, i.e., counterion release. We show that to properly describe and predict the charging equilibrium of viral capsids in general, one needs to include molecular details as exemplified by the acid-base equilibrium of the detailed distribution of amino acids in the proteinaceous capsid shell.     

Physiological role of carbonic anhydrase isozymes and their distribution in ruminant gastrointestinal tract

New data on physical-chemical characteristics, biochemical properties and functional specificity of carbonic anhydrase isozymes of human and animals are reviewed. The recent literature information about the tissue composition and regional distribution of isozymes of carbonic anhydrase in the ruminant gastrointestinal tract is generalized. The participation of carbonic anhydrase isozymes in the regulation of acid-base balance in the organism of ruminants is considered.     

Nutritional interrelationships of electrolytes and amino acids

Evidence for interactions between amino acid and electrolyte metabolism is reviewed. Variations in dietary sodium, potassium, and chloride concentrations affect acid-base balance and also influence the severity of the lysine-arginine antagonism. High dietary levels of Na and K salts of metabolizable organic acids alleviate, whereas excessive dietary chloride exacerbates, the antagonism. Potassium deficiency causes depletion of intracellular potassium and increased intracellular accumulation of basic amino acids. These variations in electrolytes, which alter acid-base balance, also influence the metabolism of glutamic acid and the excretion of nitrogen. It is hypothesized that basic amino acids as well as glutamic acid and glutamine may have an important role in metabolic regulation of acid-base balance.     

A metabolic study to decipher amino acid catabolism-directed biofuel synthesis in Acetoanaerobium sticklandii DSM 519

Acetoanaerobium sticklandii DSM 519 is a hyper-ammonia-producing anaerobe. It has the ability to produce organic solvents and acids from protein catabolism through Stickland reactions and specialized pathways. Nevertheless, its protein catabolism-directed biofuel production has not yet been understood. The present study aimed to decipher such growth-associated metabolic potential of this organism at different growth phases using metabolic profiling. A seed culture of this organism was grown separately in metabolic assay media supplemented with gelatin and or a mixture of amino acids. The extracellular metabolites produced by this organism were qualitatively analyzed by gas chromatography–mass spectrometry platform. The residual amino acids after protein degradation and amino acids assimilation were identified and quantitatively measured by high-performance liquid chromatography (HPLC). Organic solvents and acids produced by this organism were detected and the quantity of them determined with HPLC. Metabolic profiling data confirmed the presence of amino acid catabolic products including tyramine, cadaverine, methylamine, and putrescine in fermented broth. It also found products including short-chain fatty acids and organic solvents of the Stickland reactions. It reported that amino acids were more appropriate for its growth yield compared to gelatin. Results of quantitative analysis of amino acids indicated that many amino acids either from gelatin or amino acid mixture were catabolised at a log-growth phase. Glycine and proline were poorly consumed in all growth phases. This study revealed that apart from Stickland reactions, a specialized system was established in A. sticklandii for protein catabolism-directed biofuel production. Acetone–butanol–ethanol (ABE), acetic acid, and butyric acid were the most important biofuel components produced by this organism. The production of these components was achieved much more on gelatin than amino acids. Thus, A. sticklandii is suggested herein as a potential organism to produce butyric acid along with ABE from protein-based wastes (gelatin) in bio-energy sectors.

     

Age characteristics of cadmium content in the organism of poisoned rats with experimental metabolic acidosis

The paper demonstrates age peculiarities of cadmium content in the liver, kidneys and spleen of 3-month and 18-month rats poisoned by cadmium sulfate. It was registered that the content of cadmium is 266.7 times higher in 3-month old rats, and 141.8 times in 18 months rats in comparison with intact ones. A biological model of introducing 3-month and 18-month rats into the state of metabolic acidosis before and after poisoning with cadmium sulfate was developed. The result of the research showed that changes in acid-base equilibrium of poisoned rats towards metabolic acidosis may influence a decrease of cadmium content in their organisms. Thus, when modeling of metabolic acidosis before the poisoning with cadmium, the content of cadmium decreases in 3-month rats' liver by 21%, in kidneys by 53%; in metabolic acidosis modeling after cadmium poisoning its content decreases, accordingly, by 44% and by 56.5% in comparison with the just poisoned ones. In metabolic experimental acidosis modeling the content of cadmium in 3-month poisoned rats' spleen decreased by 36.5% before and after poisoning. Such changes were also registered in 18-month old rats but to lower extent. Thus, the results of the researches showed more effective correction of cadmium intoxication decrease in the organism of 3-month rats when using the model of acid-base equilibrium change in the organisms of poisoned animals.     

Effect of ecdysterone on the metabolism of purine and pyrimidine nucleotides in chicken tissues]

Hormonal amounts (10(-7) M) of ecdysterone phytoecdysteroid have been studied for their effect on the metabolic processes in the chicken tissues. Changes in the blood serum parameters which characterize the state of the integral systems of mineral, lipid, protein and nucleotide metabolism as well as the dynamics of metabolism of nucleic acids and their precursors--purine and pyrimidine nucleotides in the tissues with actively functioning protein-synthesizing system prove that the biological effect of ecdysterone after its introduction to the bird organism manifests both in the non-genome early phase of the action (0-1 h) and in the late genome phase (24-72 h), i.e. in analogy to the time of response to the introduction of classical steroid hormones. It is supposed that polyfunctional early effect of ecdysterone is mediated by its action on one of universal transmembrane signal systems of the cells--adenylate cyclase or polyphosphoinosite one, while the presence of the expressed changes in metabolism of nucleic acids in the late phase unambiguously indicate to its action in the bird organism as that of a typical steroid hormone.     

Intracellular pH regulation and metabolic interactions in hepatic tissues.

Intracellular pH (pHi) regulation in the vertebrate liver relies heavily on ionic transport mechanisms. Liver, in common with many tissues, has plasma membrane Na(+)-H+ and Cl(-)-HCO3- electroneutral exchangers which work in opposition to tightly control pHi. Mammalian livers also possess electrogenic Na(+)-HCO3- exchangers, capable of base uptake, which, when coupled to pHi-mediated changes in membrane potential, probably confer an additional measure of pHi control, compared to fish livers, where the transporter appears to be functionally absent. It is suggested that this may be a fundamental difference between aquatic and aerial breathing. pHi regulation has barely been examined in invertebrate hepatic tissues, but already some interesting differences are apparent. Notably, an electrogenic 2Na(+)-1H+ acid-extrusion system is present in apical membranes of crustacean hepatopancreas. Despite these ionic control systems, complex acid-base disturbances (e.g., "metabolic" acidosis) have been known for some time to influence hepatic metabolism in vertebrates, but few studies have carefully examined the independent effects of the acid-base variables involved. Thus mechanistic explanations for the effects of acid-base disturbances are scarce. Ureogenesis in mammals has been well studied, and several pH-related mechanisms are evident. In contrast, the pH-insensitivity of ureogenesis in fish liver may represent a second difference between aquatic and terrestrial species. In summary, by virtue of its metabolic diversity, liver represents a potentially important organ in acid-base balance, and an interesting study tissue for interrelationships between metabolism and acid-base balance.     

The regulation of phosphoenolpyruvate carboxylase in CAM plants

Phosphoenolpyruvate carboxylase catalyses the primary assimilation of CO(2) in Crassulacean acid metabolism plants. It is activated by phosphorylation, and this plays a major role in setting the day-night pattern of metabolism in these plants. The key factor that controls the phosphorylation state of phosphoenolpyruvate carboxylase is the activity of phosphoenolpyruvate carboxylase kinase. Recent work on Crassulacean acid metabolism plants has established this enzyme as a novel protein kinase and has provided new insights into the regulation of protein phosphorylation. Phosphoenolpyruvate carboxylase kinase is controlled by synthesis and degradation in response to a circadian oscillator. The circadian control of phosphoenolpyruvate carboxylase kinase can be overridden by changes in metabolite levels. The primary effect of the circadian oscillator in this system may be at the level of the tonoplast, and changes in kinase expression may be secondary to circadian changes in the concentration of a metabolite, perhaps cytosolic malate.     

Locust flight activity as a model for hormonal regulation of lipid mobilization and transport

Flight activity of insects provides a fascinating yet relatively simple model system for studying the regulation of processes involved in energy metabolism. This is particularly highlighted during long-distance flight, for which the locust constitutes a long-standing favored model insect, which as one of the most infamous agricultural pests additionally has considerable economical importance. Remarkably many aspects and processes pivotal to our understanding of (neuro)hormonal regulation of lipid mobilization and transport during insect flight activity have been discovered in the locust; among which are the peptide adipokinetic hormones (AKHs), synthesized and stored by the neurosecretory cells of the corpus cardiacum, that regulate and integrate lipid (diacylglycerol) mobilization and transport, the functioning of the reversible conversions of lipoproteins (lipophorins) in the hemolymph during flight activity, revealing novel concepts for the transport of lipids in the circulatory system, and the structure and functioning of the exchangeable apolipopotein, apolipophorin III, which exhibits a dual capacity to exist in both lipid-bound and lipid-free states that is essential to these lipophorin conversions. Besides, the lipophorin receptor (LpR) was identified and characterized in the locust.In an integrative approach, this short review aims at highlighting the locust as an unrivalled model for studying (neuro)hormonal regulation of lipid mobilization and transport during insect flight activity, that additionally has offered a broad and profound research model for integrative physiology and biochemistry, and particularly focuses on recent developments in the concept of AKH-induced changes in the lipophorin system during locust flight, that deviates fundamentally from the lipoprotein-based transport of lipids in the circulation of mammals. Current studies in this field employing the locust as a model continue to attribute to its role as a favored model organism, but also reveal some disadvantages compared to model insects with a completely sequenced genome.     

Physiologic functions of vitamin D3 and its metabolism in the body in normal states and in some pathologies

In the review there are some results of investigations of the laboratory summarized on the mechanisms of vitamin D3 metabolism and its functioning in organism; investigation of infringement of mineral, lipid and protein metabolic processes with vitamin D3 deficiency and with different pathologies and the ways of their regulation as well as the data about some new high-effective forms of vitamin D3 for their implementation in medicine and agriculture.     

Brain glutamate metabolism during metabolic alkalosis and acidosis.

Glutamate modifies ventilation by altering neural excitability centrally. Metabolic acid-base perturbations may also alter cerebral glutamate metabolism locally and thus affect ventilation. Therefore, the effect of metabolic acid-base perturbations on central nervous system glutamate metabolism was studied in pentobarbital-anesthetized dogs under normal acid-base conditions and during isocapnic metabolic alkalosis and acidosis. Cerebrospinal fluid transfer rates of radiotracer [13N]ammonia and of [13N]glutamine synthesized de novo via the reaction glutamate+NH3-->glutamine in brain glia were measured during normal acid-base conditions and after 90 min of acute isocapnic metabolic alkalosis and acidosis. Cerebrospinal fluid [13N]ammonia and [13N]glutamine transfer rates decreased in metabolic acidosis. Maximal glial glutamine efflux rate jm equals 85.6 +/- 9.5 (SE) mumol.l-1 x min-1 in all animals. No difference in jm was observed in metabolic alkalosis or acidosis. Mean cerebral cortical glutamate concentration was significantly lower in acidosis [7.01 +/- 0.45 (SE) mumol/g brain tissue] and tended to be larger in alkalosis, compared with 7.97 +/- 0.89 mumol/g in normal acid-base conditions. There was a similar change in cerebral cortical gamma-aminobutyric acid concentration. Within the limits of the present method and measurements, the results suggest that acute metabolic acidosis but not alkalosis reduces glial glutamine efflux, corresponding to changes in cerebral cortical glutamate metabolism. These results suggest that glutamatergic mechanisms may contribute to central respiratory control in metabolic acidosis.     

The 1986 Borden award lecture. The role of the kidney in amino acid metabolism and nutrition

Measurement of the arteriovenous differences for free amino acids across rat kidney reveals that glycine and citrulline are removed and serine and arginine are added to the circulation. In addition, glutamine is taken up in large quantities by kidneys of animals that need to excrete large quantities of acid (e.g., diabetic animals, NH4Cl-fed animals, and animals fed a high protein diet). Glutamine is the major precursor of urinary ammonia and thus renal glutamine metabolism plays a key role in acid-base homeostasis. This process occurs primarily in the cells of the convoluted proximal tubule. Glutamine carbon is converted to glucose in acidotic rats and is totally oxidized in dogs. Regulation of glutamine metabolism occurs at two levels: acute regulation and chronic regulation. Acute regulation is, in part, mediated through a fall in intracellular [H+]. This activates alpha-ketoglutarate dehydrogenase and, ultimately, glutaminase. Chronic regulation involves induction of key enzymes, including, in the rat, glutaminase, glutamate dehydrogenase, and phosphoenolpyruvate carboxykinase. During the acidosis of prolonged starvation, the kidneys' requirement for glutamine must be met from muscle proteolysis and thus becomes a drain on lean body mass. Serine synthesis occurs by two separate pathways: from glycine by the combined actions of the glycine cleavage enzyme and serine hydroxymethyltransferase and from gluconeogenic precursors using the phosphorylated-intermediate pathway. Both pathways are located in the cells of the proximal tubule. Conversion of glycine to serine is ammoniagenic and the activity of the glycine cleavage enzyme is increased in acidosis. The function of serine synthesis by the phosphorylated-intermediate pathway is not apparent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Triterpene glycosides and the structural-functional properties of membranes

Triterpene glycosides have been found in many plant species and some marine animals. Many of these compounds are physiologically active and possess a broad range of medico-biological action. The physiological activity of triterpene glycosides is based on their ability to interact with the components of biological systems, primarily with sterols comprising the structure of biomembranes. The interaction of glycosides with sterols causes disturbance of selective permeability in plasmic membranes. Triterpene glycosides affect the liposome ionic permeability and flat bilayer lipid membranes. The rate of glycoside effect depends on quantitative and qualitative sterol level in the membrane. These compounds are used by organisms in the struggle for life and in maintaining the biological equilibrium in the antagonistic interactions of biological systems and ensure plant immunity against fungal diseases. Triterpene glycosides as substances of exogenous origin exhibit physiological activity towards warm-blooded animals. They affect the metabolism, the functional state of the organs and the organism as a whole.     

Symbolic Extensions Applied to Multiscale Structure of Genomes

A genome of a living organism consists of a long string of symbols over a finite alphabet carrying critical information for the organism. This includes its ability to control post natal growth, homeostasis, adaptation to changes in the surrounding environment, or to biochemically respond at the cellular level to various specific regulatory signals. In this sense, a genome represents a symbolic encoding of a highly organized system of information whose functioning may be revealed as a natural multilayer structure in terms of complexity and prominence. In this paper we use the mathematical theory of symbolic extensions as a framework to shed light onto how this multilayer organization is reflected in the symbolic coding of the genome. The distribution of data in an element of a standard symbolic extension of a dynamical system has a specific form: the symbolic sequence is divided into several subsequences (which we call layers) encoding the dynamics on various “scales”. We propose that a similar structure resides within the genomes, building our analogy on some of the most recent findings in the field of regulation of genomic DNA functioning.