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Metabolic Processes (metabolic + process)
Selected AbstractsExpression profiles of fhs (FTHFS) genes support the hypothesis that spirochaetes dominate reductive acetogenesis in the hindgut of lower termitesENVIRONMENTAL MICROBIOLOGY, Issue 7 2006Michael Pester Summary Reductive acetogenesis is an important metabolic process in the hindgut of wood-feeding termites. We analysed diversity and expression profiles of the bacterial fhs gene, a marker gene encoding a key enzyme of reductive acetogenesis, formyl tetrahydrofolate synthetase (FTHFS), to identify the active homoacetogenic populations in representatives of three different termite families. Clone libraries of polymerase chain reaction-amplified fhs genes from hindgut contents of Reticulitermes santonensis (Rhinotermitidae) and Cryptotermes secundus (Kalotermitidae) were compared with previously published fhs gene sequences obtained from Zootermopsis nevadensis (Termopsidae). Most of the clones clustered among the ,Termite Treponemes', which comprise also the fhs genes of the two strains of the homoacetogenic spirochaete Treponema primitia. The high abundance of treponemal fhs genes in all clone libraries was in agreement with the results of DNA-based terminal-restriction fragment length polymorphism (T-RFLP) analysis. Moreover, in mRNA-based T-RFLP profiles of the three termites, only expression of fhs genes of ,Termite Treponemes' was detected, albeit at different levels. In C. secundus, only one of the dominating phylotypes was transcribed, while in R. santonensis, the apparently less abundant fhs genes were the most actively expressed. Our results strongly support the hypothesis that spirochaetes are responsible for reductive acetogenesis in the hindgut of lower, wood-feeding termites. [source] Biochemistry and molecular biology of lithotrophic sulfur oxidation by taxonomically and ecologically diverse bacteria and archaeaFEMS MICROBIOLOGY REVIEWS, Issue 6 2009Wriddhiman Ghosh Abstract Lithotrophic sulfur oxidation is an ancient metabolic process. Ecologically and taxonomically diverged prokaryotes have differential abilities to utilize different reduced sulfur compounds as lithotrophic substrates. Different phototrophic or chemotrophic species use different enzymes, pathways and mechanisms of electron transport and energy conservation for the oxidation of any given substrate. While the mechanisms of sulfur oxidation in obligately chemolithotrophic bacteria, predominantly belonging to Beta - (e.g. Thiobacillus) and Gammaproteobacteria (e.g. Thiomicrospira), are not well established, the Sox system is the central pathway in the facultative bacteria from Alphaproteobacteria (e.g. Paracoccus). Interestingly, photolithotrophs such as Rhodovulum belonging to Alphaproteobacteria also use the Sox system, whereas those from Chromatiaceae and Chlorobi use a truncated Sox complex alongside reverse-acting sulfate-reducing systems. Certain chemotrophic magnetotactic Alphaproteobacteria allegedly utilize such a combined mechanism. Sulfur-chemolithotrophic metabolism in Archaea, largely restricted to Sulfolobales, is distinct from those in Bacteria. Phylogenetic and biomolecular fossil data suggest that the ubiquity of sox genes could be due to horizontal transfer, and coupled sulfate reduction/sulfide oxidation pathways, originating in planktonic ancestors of Chromatiaceae or Chlorobi, could be ancestral to all sulfur-lithotrophic processes. However, the possibility that chemolithotrophy, originating in deep sea, is the actual ancestral form of sulfur oxidation cannot be ruled out. [source] Isolation and identification of 1,-hydroxy-3-epi-vitamin D3, a potent suppressor of parathyroid hormone secretionJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2005Alex J. Brown Abstract Since our original demonstration of the metabolism of 1,,25(OH)2D3 into 1,,25(OH)2 -3-epi-D3 in human keratinocytes, there have been several reports indicating that epimerization of the 3 hydroxyl group of vitamin D compounds is a common metabolic process. Recent studies reported the metabolism of 25OHD3 and 24(R),25(OH)2D3 into their respective C-3 epimers, indicating that the presence of 1, hydroxyl group is not necessary for the 3-epimerization of vitamin D compounds. To determine whether the presence of a 25 hydroxyl group is required for 3-epimerization of vitamin D compounds, we investigated the metabolism of 1,OHD3, a non-25 hydroxylated vitamin D compound, in rat osteosarcoma cells (ROS 17/2.8). We noted metabolism of 1,OHD3 into a less polar metabolite which was unequivocally identified as 1,OH-3-epi-D3 using the techniques of HPLC, GC/MS, and 1H-NMR analysis. We also identified 1,OH-3-epi-D3 as a circulating metabolite in rats treated with pharmacological concentrations of 1,OHD3. Thus, these results indicated that the presence of a 25 hydroxyl group is not required for 3-epimerization of vitamin D compounds. Furthermore, the results from the same studies also provided evidence to indicate that 1,OH-3-epi-D3, like 1,OHD3, is hydroxylated at C-25. We then evaluated the biological activities of 1,OH-3-epi-D3. Treatment of normal rats every other day for 7 days with 2.5 nmol/kg of 1,OH-3-epi-D3 did not raise serum calcium, while the same dose of 1,OHD3 increased serum calcium by 3.39,±,0.52 mg/dl. Interestingly, in the same rats which received 1,OH-3-epi-D3 we also noted a reduction in circulating PTH levels by 65,±,7%. This ability of 1,OH-3-epi-D3 to suppress PTH levels in normal rats without altering serum calcium was further tested in rats with reduced renal function. The results indicated that the ED50 of 1,OH-3-epi-D3 for suppression of PTH was only slightly higher than that of 1,,25(OH)2D3, but that the threshold dose of the development of hypercalcemia (total serum Ca >,10.5 mg/dl) was nearly 80 times higher. These findings indicate that 1,OH-3-epi-D3 is a highly selective vitamin D analog with tremendous potential for treatment of secondary hyperparathyroidism in chronic renal failure patients. © 2005 Wiley-Liss, Inc. [source] Relative longevity and field metabolic rate in birdsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2008A. P. MØLLER Abstract Metabolism is a defining feature of all living organisms, with the metabolic process resulting in the production of free radicals that can cause permanent damage to DNA and other molecules. Surprisingly, birds, bats and other organisms with high metabolic rates have some of the slowest rates of senescence begging the question whether species with high metabolic rates also have evolved mechanisms to cope with damage induced by metabolism. To test whether species with the highest metabolic rates also lived the longest I determined the relationship between relative longevity (maximum lifespan), after adjusting for annual adult survival rate, body mass and sampling effort, and mass-specific field metabolic rate (FMR) in 35 species of birds. There was a strongly positive relationship between relative longevity and FMR, consistent with the hypothesis. This conclusion was robust to statistical control for effects of potentially confounding variables such as age at first reproduction, latitude and migration distance, and similarity in phenotype among species because of common phylogenetic descent. Therefore, species of birds with high metabolic rates senesce more slowly than species with low metabolic rates. [source] Mass spectrometric analysis of 7-sulfoxymethyl-12-methylbenz[a]anthracene and related electrophilic polycyclic aromatic hydrocarbon metabolitesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 11 2004Andreas F. Lehner Abstract The Meso-region theory of polycyclic aromatic hydrocarbon (PAH) carcinogenesis predicts that the development of pronounced carcinogenicity depends on the introduction of a good leaving group on alkyl side-chains attached to the exceptionally reactive meso-anthracenic or L-region positions of PAHs. Thus, the first step in carcinogenesis by methylated PAHs such as 7,12-dimethylbenz[a]anthracene (DMBA) would be the hydroxylation of the L-region methyl groups, particularly the 7-methyl group. The second would be the formation of a metabolite, e.g. a sulfate ester, which is expected to be a good leaving group capable of generating a highly reactive benzylic carbocation. 7-Hydroxymethyl-12-methylbenz[a]anthracene (7-HMBA) is a metabolite of DMBA, and sulfation of 7-HMBA to a 7-sulfoxymethyl metabolite (7-SMBA) is a known Phase II metabolic process designed to facilitate excretion, but actually enabling more destructive side-reactions. These side-reactions occur with generation of an electrophilic 7-methylene carbonium ion, and/or by in vivo halide exchange to provide neutral side-products more capable of entering cells, especially those of DMBA target tissues. Electrospray ionization mass spectrometry (MS) enabled us to visualize 7-SMBA as an intact m/z 351 conjugate anion by negative mode, and as a released m/z 255 carbonium ion by positive mode. Upon prolonged refrigeration, 7-SMBA accumulated an m/z 383 photooxide, which appeared capable of re-evolving the starting material as visualized by tandem quadrupole MS, or MS/MS. The 7-SMBA carbonium ion provided interpretable fragments when studied by fragment ion MS/MS, including those representing the loss of up to several protons. Subtle differences in this property were encountered upon perturbing 7-SMBA, either by warming it at 37 °C for 2 h or by substituting the initial sulfoxy group with an iodo group. Side-reactions accounting for such proton losses are proposed, and are of interest whether they occur in the mass spectrometer, in solution or both; these proposals include acidity at the 12-methyl position and cyclization between the 12-methyl group and the adjacent C-1 position. It is also suggested that such side-reactions may comprise one route to relieving steric strain arising between the 12-methyl group and the angular benzo ring of 7-SMBA. Copyright © 2004 John Wiley & Sons, Ltd. [source] DOC leaching from a coniferous forest floor: modeling a manipulation experiment,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2005Edward Tipping Abstract The DyDOC model simulates the C dynamics of forest soils, including the production and transport of dissolved organic matter (DOM), on the basis of soil hydrology, metabolic processes, and sorption reactions. The model recognizes three main pools of soil C: litter, substrate (an intermediate transformation product), and humic substances. The model was used to simulate the behavior of C in the O horizon of soil under a Norway spruce stand at Asa, Sweden, that had been subjected to experimental manipulations (addition and removal) of above-ground litter inputs and to removal of the Oi and Oe layers. Initially, the model was calibrated using results for the control plots and was able to reproduce the observed total soil C pool and 14C content, DOC flux and DO14C content, and the pool of litter C, together with the assumed content of C in humic substances (20% of the total soil C), and the assumed distribution of DOC between hydrophilic and hydrophobic fractions. The constant describing DOC exchange between micro- and macropores was estimated from short-term variations in DOC concentration. When the calibrated model was used to predict the effects of litter and soil manipulations, it underestimated the additional DOC export (up to 33%) caused by litter addition, and underestimated the 22% reduction in DOC export caused by litter withdrawal. Therefore, an additional metabolic process, the direct conversion of litter to DOC, was added to the model. The addition of this process permitted reasonably accurate simulation of the results of the manipulation experiments, without affecting the goodness-of-fit in the model calibration. The results suggest that, under normal conditions, DOC exported from the Asa forest floor is a mixture of compounds derived from soil C pools with a range of residence times. Approximately equal amounts come from the litter pool (turnover time 4.6 yr), the substrate pool (26 yr), and the humic-substances pool (36 yr). [source] Expression of contactin associated protein-like 2 in a subset of hepatic progenitor cell compartment identified by gene expression profiling in hepatitis B virus-positive cirrhosisLIVER INTERNATIONAL, Issue 1 2010Huafeng Wang Abstract Background: Hepatic progenitor cells (HPC), a cell compartment capable of differentiating into hepatocytic and biliary lineages, may give rise to the formation of intermediate hepatobiliary cells (IHBC) or ductular reactions (DR). Aims: The aim of this study was to analyse the gene expression profiles of DR in cirrhosis and further investigate novel proteins expressed by HPC and their intermediate progeny. Methods: DR in hepatitis B virus (HBV)-positive cirrhotic liver tissues adjacent to hepatocellular carcinoma and interlobular bile ducts (ILBDs) in normal liver tissues were isolated by laser capture microdissection and then subjected to microarray analysis. Differential gene expression patterns were verified by quantitative reverse transcriptase-polymerase chain reaction and immunohistochemistry on serial sections. HPC and their intermediate progeny were recognized by immunostaining with hepatocytic and biliary markers [HepPar1, cytokeratin (CK)7, CK19, neural cell adhesion molecule (NCAM), epithelial cell adhesion molecule (EpCAM)]. Results: A total of 88 genes showed upregulation in DR compared with ILBDs. Gene ontology analyses revealed that these upregulated genes were mostly associated with cell adhesion, immune response and the metabolic process. Contactin associated protein-like 2 (CNTNAP2) was first confirmed to be a novel protein expressed in a subpopulation of DR that was positive for CK7, NCAM or EpCAM. In addition, immunoreactivity for CNTNAP2 was also noted in a subset of isolated CK7-positive HPC as well as some ductular IHBC positive for CK19 and HepPar1 in DR. Conclusion: CNTNAP2 is specifically associated with the emergence of ductular populations and may be identified as a novel protein for defining a subset of HPC and their intermediate progeny in cirrhosis. [source] How to design perforated polymeric films for modified atmosphere packs (MAP)PACKAGING TECHNOLOGY AND SCIENCE, Issue 6 2001Luciano ZanderighiArticle first published online: 12 APR 200 Abstract Increasing proportions of fresh produce are being sold in modified atmosphere packs (MAP) with the aim of preserving product quality longer and reducing freight costs. A rigorous theoretical analysis was made of the transport phenomena across packaging film (composite, perforated, etc.) in order to find out whether polymeric film will permit a stationary modified atmosphere (MA) inside the pack, and if so when, and to investigate the effect of the size and shape of the holes in the perforated film. The continuity equations of the pack, for all diffusing species, were written and solved for stationary conditions, with the boundary conditions that species not involved in metabolic processes do not diffuse across polymeric film. After a detailed analysis of the transport phenomena across both continuous and perforated film, and of the metabolic rate processes, it transpires that no stationary conditions compatible with any MA can be found for continuous film, owing to the permeation characteristics of the film and the rate of the metabolic processes. With perforated film it is possible to find, at least for certain metabolic process rates, a stationary state where a constant MA is maintained inside the pack. A proposal is given, provided the rate of the metabolic process is known, for the design of a pack in terms of polymeric materials and of the pinhole size. Two case studies, strawberry and cabbage, are presented and discussed, along with the optimization of the polymeric film and the size and length of the pinholes of the packs. Another point raised deals with the advantages of using perforated film and/or of making holes or openings along the edges where the polymeric film is welded. Copyright © 2001 John Wiley & Sons, Ltd. [source] Glucose Depletion Enhances Sensitivity to Shear Stress-induced Mechanical Damage in Red Blood Cells by Rotary Blood PumpsARTIFICIAL ORGANS, Issue 9 2009Daisuke Sakota Abstract The metabolic process in red blood cells (RBCs) is anaerobic. The life-dependent adenosine triphosphate (ATP) for survival of cells is produced through glycolytic process. The aim of the study was to evaluate the effects of the glucose level on the mean corpuscular volume, mean corpuscular hemoglobin concentration, and hemolysis rate during hemolysis study by rotary blood pumps. The shear stress generated by rotary blood pumps may enhance glucose utilization by RBCs with depletion of glucose affecting ATP production and, consequently, cell size, shape, and morphology. The shear stress increases metabolism of RBCs consuming more energy ATP which is produced anaerobically from glycolytic process. Hence, in the closed circuit testing of rotary blood pumps, depletion of glucose might occur after prolonged pumping, which in turn affects metabolic process of RBCs by changing their size, shape, and morphology. It is thus suggested to monitor and control the glucose level of the fluid that suspends RBCs depending on the study duration. [source] Lysine Acetylation: The Tale of a Modification from Transcription Regulation to MetabolismCHEMBIOCHEM, Issue 11 2010Mohammed Arif Dr. Reversible lysine acetylation is an important modification involved in the regulation of gene expression. Acetyl-CoA and NAD+ are major determinants of this modification, NAD+ levels being regulated by the cellular redox status. Recent reports have shown that lysine acetylation also regulates metabolic processes, thus linking the central metabolic process to gene expression. [source] Magnetic resonance spectroscopy (MRS) and its application in Alzheimer's diseaseCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2007Pravat K. Mandal Abstract Magnetic resonance spectroscopy (MRS) is a noninvasive tool to measure the chemical composition of tissues (in vivo) and characterize functional metabolic processes in different parts of the human organs. It provides vital biological information at the molecular level. Combined with magnetic resonance imaging (MRI), an integrated MRI/MRS examination provides anatomical structure, pathological function, and biochemical information about a living system. MRS provides a link between the biochemical alterations and the pathophysiology of disease. This article provides a comprehensive description of the MRS technique and its application in Alzheimer's disease (AD) research. This review is a primer for students and researchers seeking a firm theoretical understanding of MRS physics as well as its application in clinical AD research. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part A 30A: 40,64, 2007. [source] Depression and the metabolic syndrome: gender-dependent associationsDEPRESSION AND ANXIETY, Issue 8 2008Sharon Toker Ph.D. Abstract This study was designed to test the extent to which depressive symptoms are associated with the presence of the metabolic syndrome (MS) and each of its components, and whether these relationships are gender dependent. Participants were apparently healthy employed men (N=2,355) and women (N=1,525) who underwent a routine health check between the years 2003 and 2005. We used logistic regression analysis, predicting the MS by depressive symptoms, as assessed by the Patient Health Questionnaire, and the following control variables: age, education, smoking status, physical exercise, anxiety, and burnout. As hypothesized, we found that depression among women, but not men, was associated with a 1.94-fold risk of having the MS, and with an elevated risk of having two of its five components: elevated waist circumference (odds ratio, OR=2.23) and elevated glucose levels (OR=2.44). In addition, a positive trend was observed toward an association with the other three components: low high-density lipoprotein, hypertension, and elevated triglycerides. Among men depression was associated with elevated waist circumference only (OR=1.77). These findings suggest that especially among women, the association between depression and cardiovascular diseases might be linked to metabolic processes. If replicated in longitudinal studies, these findings may have important health-care policy implications with regard to depression management interventions. Depression and Anxiety 0:1,9, 2007. © 2007 Wiley-Liss, Inc. [source] Active immunization against (Pro3)GIP improves metabolic status in high-fat-fed miceDIABETES OBESITY & METABOLISM, Issue 9 2010I. A. Montgomery Aim: Ablation of gastric inhibitory polypeptide (GIP) receptor signalling can prevent many of the metabolic abnormalities associated with dietary-induced obesity-diabetes. The present study was designed to assess the ability of active immunization against (Pro3)GIP to counter metabolic dysfunction associated with diet-induced obesity in high-fat-fed mice. Methods: Normal male Swiss NIH mice were injected (s.c.) once every 14 days for 98 days with complexed (Pro3)GIP peptide, with transfer to a high-fat diet on day 21. Results: Active immunization against (Pro3)GIP resulted in circulating GIP antibody production and significantly (p < 0.05 p < 0.01) reduced circulating blood glucose concentrations compared to high-fat control mice from day 84 onwards. Glucose levels were not significantly different from lean controls. The glycaemic response to i.p. glucose was correspondingly improved (p < 0.01) in (Pro3)GIP-immunized mice. Furthermore, circulating and glucose-stimulated plasma insulin levels were significantly (p < 0.01 to p < 0.001) depressed compared to high-fat control mice. Liver triglyceride, pancreatic insulin and circulating LDL-cholesterol levels were also significantly reduced in (Pro3)GIP-immunized mice. These changes were independent of any effects on food intake or body weight. The glucose-lowering effect of native GIP was annulled in (Pro3)GIP-immunized mice consistent with the induction of biologically effective GIP-specific neutralizing antibodies. Conclusion: These results suggest that immunoneutralization of GIP represents an effective means of countering the disruption of metabolic processes induced by high-fat feeding. [source] Post-ingestive effects of nectar alkaloids depend on dominance status of bumblebeesECOLOGICAL ENTOMOLOGY, Issue 4 2009JESSAMYN S. MANSON Abstract 1.,Secondary metabolites have acute or chronic post-ingestive effects on animals, ranging from death to growth inhibition to reduced nutrient assimilation. 2.,Although characterised as toxic, the nectar of Gelsemium sempervirens is not lethal to pollinators, even when the concentration of the nectar alkaloid gelsemine is very high. However, little is known about the sublethal costs of nectar alkaloids. 3.,Using a microcolony assay and paired worker bumblebees, the present study measured the effects of artificial nectar containing gelsemine on oocyte development. Oocytes are a sensitive indicator of protein utilisation and general metabolic processes. We also calculated carbohydrate concentrations in the haemolymph to examine energetic costs of gelsemine consumption. 4.,High concentrations of gelsemine significantly reduced mean oocyte width in subordinate bees, while dominant bees showed only a trend towards oocyte inhibition. Gelsemine consumption did not reduce carbohydrate concentrations in haemolymph. 5.,The cost of ingesting gelsemine may be due to direct toxicity of alkaloids or may be an expense associated with detoxifying gelsemine. Detoxification of alkaloids can require reallocation of resources away from essential metabolic functions like reproduction. The risks associated with nectar alkaloid consumption are tied to both the social and nutritional status of the bee. [source] Pseudomonas fluorescens orchestrates a fine metabolic-balancing act to counter aluminium toxicityENVIRONMENTAL MICROBIOLOGY, Issue 6 2010Joseph Lemire Summary Aluminium (Al), an environmental toxin, is known to disrupt cellular functions by perturbing iron (Fe) homeostasis. However, Fe is essential for such metabolic processes as the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the two pivotal networks that mediate ATP production during aerobiosis. To counter the Fe conundrum induced by Al toxicity, Pseudomonas fluorescens utilizes isocitrate lyase and isocitrate dehydrogenase-NADP dependent to metabolize citrate when confronted with an ineffective aconitase provoked by Al stress. By invoking fumarase C, a hydratase devoid of Fe, this microbe is able to generate essential metabolites. To compensate for the severely diminished enzymes like Complex I, Complex II and Complex IV, the upregulation of a H2O-generating NADH oxidase enables the metabolism of citrate, the sole carbon source via a modified TCA cycle. The overexpression of succinyl-CoA synthetase affords an effective route to ATP production by substrate-level phosphorylation in the absence of O2. This fine metabolic balance enables P. fluorescens to survive the dearth of bioavailable Fe triggered by an Al environment, a feature that may have potential applications in bioremediation technologies. [source] LKB1 is essential for the proliferation of T-cell progenitors and mature peripheral T cellsEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2010Peter Tamás Abstract The serine/threonine kinase LKB1 has a conserved role in Drosophila and nematodes to co-ordinate cell metabolism. During T lymphocyte development in the thymus, progenitors need to synchronize increased metabolism with the onset of proliferation and differentiation to ensure that they can meet the energy requirements for development. The present study explores the role of LKB1 in this process and shows that loss of LKB1 prevents thymocyte differentiation and the production of peripheral T lymphocytes. We find that LKB1 is required for several key metabolic processes in T-cell progenitors. For example, LKB1 controls expression of CD98, a key subunit of the L -system aa transporter and is also required for the pre-TCR to induce and sustain the regulated phosphorylation of the ribosomal S6 subunit, a key regulator of protein synthesis. In the absence of LKB1 TCR-,-selected thymocytes failed to proliferate and did not survive. LBK1 was also required for survival and proliferation of peripheral T cells. These data thus reveal a conserved and essential role for LKB1 in the proliferative responses of both thymocytes and mature T cells. [source] Mice with astrocyte-directed inactivation of connexin43 exhibit increased exploratory behaviour, impaired motor capacities, and changes in brain acetylcholine levelsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2003Christian Frisch Abstract Gap junctions mediate communication between many cell types in the brain. Gap junction channels are composed of membrane-spanning connexin (Cx) proteins, allowing the cell-to-cell passage of small ions and metabolites. Cx43 is the main constituent of the brain-spanning astrocytic gap junctional network, controlling activity-related changes in ion and glutamate concentrations as well as metabolic processes. In astrocytes, deletion of Cx43-coding DNA led to attenuated gap junctional coupling and impaired propagation of calcium waves, known to influence neuronal activity. Investigation of the role of Cx43 in behaviour has been impossible so far, due to postnatal lethality of its general deletion. Recently, we have shown that deletion of Cx30, which is also expressed by astrocytes, affects exploration, emotionality, and neurochemistry in the mouse. In the present study, we investigated the effects of the astrocyte-directed inactivation of Cx43 on mouse behaviour and brain neurochemistry. Deletion of Cx43 in astrocytes increased exploratory activity without influencing habituation. In the open field, but not in the elevated plus-maze, an anxiolytic-like effect was observed. Rotarod performance was initially impaired, but reached control level after further training. In the water maze, Cx43 deficient mice showed a steeper learning course, although final performance was similar between groups. Cx43 inactivation in astrocytes increased acetylcholine content in the frontal cortex of water maze-trained animals. Results are discussed in terms of altered communication between astrocytes and neurons, possible compensation processes, and differential effects of Cx30- and astrocyte-specific Cx43 deletion. [source] mTOR as a potential therapeutic target for treatment of keloids and excessive scarsEXPERIMENTAL DERMATOLOGY, Issue 5 2007C. T. Ong Abstract:, Keloid is a dermal fibroproliferative disorder characterized by excessive deposition of extracellular matrix (ECM) components such as collagen, glycoproteins and fibronectin. The mammalian target of rapamycin (mTOR) is a serine/theronine kinase which plays an important role in the regulation of metabolic processes and translation rates. Published reports have shown mTOR as regulator of collagen expression and its inhibition induces a decrease in ECM deposition. Our aim was to investigate the role of mTOR in keloid pathogenesis and investigate the effect of rapamycin on proliferating cell nuclear antigen (PCNA), cyclin D1, collagen, fibronectin and alpha-smooth muscle actin (, -SMA) expression in normal fibroblasts (NF) and keloid fibroblasts (KF). Tissue extracts obtained from keloid scar demonstrated elevated expression of mTOR, p70KDa S6 kinase (p70S6K) and their activated forms, suggesting an activated state in keloid scars. Serum stimulation highlighted the heightened responsiveness of KF to mitogens and the importance of mTOR and p70S6K during early phase of wound healing. Application of rapamycin to monoculture NF and KF, dose- and time-dependently downregulates the expression of cytoplasmic PCNA, cyclin D1, fibronectin, collagen and , -SMA, demonstrating the anti-proliferative effect and therapeutic potential of rapamycin in the treatment of keloid scars. The inhibitory effect of rapamycin was found to be reversible following recovery in the expression of proteins following the removal of rapamycin from the culture media. These results demonstrate the important role of mTOR in the regulation of cell cycle and the expression of ECM proteins: fibronectin, collagen and , -SMA. [source] Glycation of low-density lipoprotein results in the time-dependent accumulation of cholesteryl esters and apolipoprotein B-100 protein in primary human monocyte-derived macrophagesFEBS JOURNAL, Issue 6 2007Bronwyn E. Brown Nonenzymatic covalent binding (glycation) of reactive aldehydes (from glucose or metabolic processes) to low-density lipoproteins has been previously shown to result in lipid accumulation in a murine macrophage cell line. The formation of such lipid-laden cells is a hallmark of atherosclerosis. In this study, we characterize lipid accumulation in primary human monocyte-derived macrophages, which are cells of immediate relevance to human atherosclerosis, on exposure to low-density lipoprotein glycated using methylglyoxal or glycolaldehyde. The time course of cellular uptake of low-density lipoprotein-derived lipids and protein has been characterized, together with the subsequent turnover of the modified apolipoprotein B-100 (apoB) protein. Cholesterol and cholesteryl ester accumulation occurs within 24 h of exposure to glycated low-density lipoprotein, and increases in a time-dependent manner. Higher cellular cholesteryl ester levels were detected with glycolaldehyde-modified low-density lipoprotein than with methylglyoxal-modified low-density lipoprotein. Uptake was significantly decreased by fucoidin (an inhibitor of scavenger receptor SR-A) and a mAb to CD36. Human monocyte-derived macrophages endocytosed and degraded significantly more 125I-labeled apoB from glycolaldehyde-modified than from methylglyoxal-modified, or control, low-density lipoprotein. Differences in the endocytic and degradation rates resulted in net intracellular accumulation of modified apoB from glycolaldehyde-modified low-density lipoprotein. Accumulation of lipid therefore parallels increased endocytosis and, to a lesser extent, degradation of apoB in human macrophages exposed to glycolaldehyde-modified low-density lipoprotein. This accumulation of cholesteryl esters and modified protein from glycated low-density lipoprotein may contribute to cellular dysfunction and the increased atherosclerosis observed in people with diabetes, and other pathologies linked to exposure to reactive carbonyls. [source] Histone modifications and chromatin dynamics: a focus on filamentous fungiFEMS MICROBIOLOGY REVIEWS, Issue 3 2008Gerald Brosch Abstract The readout of the genetic information of eukaryotic organisms is significantly regulated by modifications of DNA and chromatin proteins. Chromatin alterations induce genome-wide and local changes in gene expression and affect a variety of processes in response to internal and external signals during growth, differentiation, development, in metabolic processes, diseases, and abiotic and biotic stresses. This review aims at summarizing the roles of histone H1 and the acetylation and methylation of histones in filamentous fungi and links this knowledge to the huge body of data from other systems. Filamentous fungi show a wide range of morphologies and have developed a complex network of genes that enables them to use a great variety of substrates. This fact, together with the possibility of simple and quick genetic manipulation, highlights these organisms as model systems for the investigation of gene regulation. However, little is still known about regulation at the chromatin level in filamentous fungi. Understanding the role of chromatin in transcriptional regulation would be of utmost importance with respect to the impact of filamentous fungi in human diseases and agriculture. The synthesis of compounds (antibiotics, immunosuppressants, toxins, and compounds with adverse effects) is also likely to be regulated at the chromatin level. [source] Energetics of overall metabolic reactions of thermophilic and hyperthermophilic Archaea and BacteriaFEMS MICROBIOLOGY REVIEWS, Issue 2 2001Jan P. Amend Abstract Thermophilic and hyperthermophilic Archaea and Bacteria have been isolated from marine hydrothermal systems, heated sediments, continental solfataras, hot springs, water heaters, and industrial waste. They catalyze a tremendous array of widely varying metabolic processes. As determined in the laboratory, electron donors in thermophilic and hyperthermophilic microbial redox reactions include H2, Fe2+, H2S, S, S2O32,, S4O62,, sulfide minerals, CH4, various mono-, di-, and hydroxy-carboxylic acids, alcohols, amino acids, and complex organic substrates; electron acceptors include O2, Fe3+, CO2, CO, NO3,, NO2,, NO, N2O, SO42,, SO32,, S2O32,, and S. Although many assimilatory and dissimilatory metabolic reactions have been identified for these groups of microorganisms, little attention has been paid to the energetics of these reactions. In this review, standard molal Gibbs free energies (,Gr°) as a function of temperature to 200°C are tabulated for 370 organic and inorganic redox, disproportionation, dissociation, hydrolysis, and solubility reactions directly or indirectly involved in microbial metabolism. To calculate values of ,Gr° for these and countless other reactions, the apparent standard molal Gibbs free energies of formation (,G°) at temperatures to 200°C are given for 307 solids, liquids, gases, and aqueous solutes. It is shown that values of ,Gr° for many microbially mediated reactions are highly temperature dependent, and that adopting values determined at 25°C for systems at elevated temperatures introduces significant and unnecessary errors. The metabolic processes considered here involve compounds that belong to the following chemical systems: H,O, H,O,N, H,O,S, H,O,N,S, H,O,Cinorganic, H,O,C, H,O,N,C, H,O,S,C, H,O,N,S,Camino acids, H,O,S,C,metals/minerals, and H,O,P. For four metabolic reactions of particular interest in thermophily and hyperthermophily (knallgas reaction, anaerobic sulfur and nitrate reduction, and autotrophic methanogenesis), values of the overall Gibbs free energy (,Gr) as a function of temperature are calculated for a wide range of chemical compositions likely to be present in near-surface and deep hydrothermal and geothermal systems. [source] The roots of microbiology and the influence of Ferdinand Cohn on microbiology of the 19th centuryFEMS MICROBIOLOGY REVIEWS, Issue 3 2000Gerhart Drews Abstract The beginning of modern microbiology can be traced back to the 1870s, and it was based on the development of new concepts that originated during the two preceding centuries on the role of microorganisms, new experimental methods, and discoveries in chemistry, physics, and evolutionary cell biology. The crucial progress was the isolation and growth on solid media of clone cultures arising from single cells and the demonstration that these pure cultures have specific, inheritable characteristics and metabolic capacities. The doctrine of the spontaneous generation of microorganisms, which stimulated research for a century, lost its role as an important concept. Microorganisms were discovered to be causative agents of infectious diseases and of specific metabolic processes. Microscopy techniques advanced studies on microorganisms. The discovery of sexuality and development in microorganisms and Darwin's theory of evolution contributed to the founding of microbiology as a science. Ferdinand Cohn (1828,1898), a pioneer in the developmental biology of lower plants, considerably promoted the taxonomy and physiology of bacteria, discovered the heat-resistant endospores of bacilli, and was active in applied microbiology. [source] The capture and gratuitous disposal of resources by plantsFUNCTIONAL ECOLOGY, Issue 1 2001Thomas H. Summary 1,Every plant will die if light, water or nutrients are withheld for long enough. It is natural to think of plants in general as having evolved a strong drive for resource acquisition as a survival mechanism. All else being equal, an individual that sequesters more material from the environment than its neighbour must be at a competitive advantage. 2,But the resource capture imperative seems at odds with the profligacy of some characteristic developmental and metabolic processes in many plants. Here, using leaf senescence as a vantage point, we consider whether a kind of wilful inefficiency of resource use may not be essential for success as a terrestrial autotroph. [source] Modulation of the Lifetime of Water Bound to Lanthanide Metal Ions in Complexes with Ligands Derived from 1,4,7,10-Tetraazacyclododecane Tetraacetate (DOTA)HELVETICA CHIMICA ACTA, Issue 5 2005Shanrong Zhang A series of di- and tetraamide derivatives of DOTA were synthesized, and their lanthanide(III) complexes were examined by multinuclear 1H-, 13C-, and 17O-NMR spectroscopy, and compared with literature data of similar, known complexes (Table). All ligands formed structures similar to the parent [LnIII(DOTA)], complexes, with four N-atoms and four O-atoms from DOTA and one O-atom from the inner-sphere water molecules. Interestingly, the lifetimes ,M of the inner-sphere, metal-bound water molecules vary widely, ranging from nano- to milliseconds, depending on the identity of the pendent amide side chains. In general, positively charged [LnIII(DOTA-tetraamide)]3+ complexes display the longest residence times (high ,M values), while complexes with additional charged functional groups on the extended amides display much smaller ,M values, even when the side groups are not directly coordinated to the central Ln3+ ions. The design of novel [LnIII(DOTA-tetraamide)]3+ complexes with a wide, tunable range of ,M values is of prime importance for the application of fast-responding, paramagnetic chemical-exchange-saturation-transfer (PARACEST) imaging agents used for the study of physiological and metabolic processes. [source] Demyelination secondary to chronic nerve compression injury alters Schmidt,Lanterman incisuresJOURNAL OF ANATOMY, Issue 1 2006Brent L. Berger Abstract The role of Schmidt,Lanterman incisures (SLIs) within the myelin sheath remains the subject of much debate. Previous studies have shown a positive correlation between the number of SLIs per internode and internodal width for both normal and pathological myelin internodes. As chronic nerve compression (CNC) injury induces demyelination, we sought to evaluate if CNC injury altered the occurrence of SLIs using nerve-teasing techniques and light microscopy. Rigorous examination of the teased axons from nerves subjected to CNC injury for 1 month, 2 months or 8 months revealed that there is indeed a positive correlation between the number of SLIs per internode and the internodal width. However, unlike previous studies, the degree of positive correlation between these two parameters was greater in the internodes that had undergone remyelination in response to CNC injury as compared with the internodes from control nerves. These findings support the theory that SLIs are likely to assist in the metabolic processes of the myelin sheath, including growth and maintenance of the myelin sheath. [source] Colorful songbirds metabolize carotenoids at the integumentJOURNAL OF AVIAN BIOLOGY, Issue 6 2004Kevin J. McGraw For decades, carotenoids have attracted attention for their roles as vitamin-A precursors, antioxidants, and immunostimulants, but we still understand very little about the metabolic processes that accompany these compounds. Animals like birds use carotenoids to color their feathers and bare parts to become sexually attractive. They commonly metabolically derive their body colorants from dietary sources of carotenoids, but the sites of pigment metabolism remain unidentified. Here I test the hypothesis that songbirds manufacture their colorful feather and beak carotenoids directly at these tissues. I offer two lines of evidence to support this idea: (1) in a study of 11 colorful species from three passerine families, metabolically derived feather and beak carotenoids were found neither in the liver (a purported site of carotenoid metabolism), nor in the bloodstream (the means by which metabolites would be transported to colorful tissues from anywhere else in the body) at the time when pigments were being deposited into keratinized tissue, and (2) in a more detailed study of pigmentation in the American goldfinch Carduelis tristis, carotenoids sampled from the lipid fractions of maturing feather follicles yielded a mix of dietary and synthetic carotenoids, suggesting that this is the metabolically active site for feather-pigment production. This fresh perspective on carotenoid metabolism in animals should aid our efforts to characterize the responsible enzymes and to better understand the localized biological functions of these pigments. [source] The metabolic component of cellular refractivity and its importance for optical cytometryJOURNAL OF BIOPHOTONICS, Issue 8-9 2009V. TychinskyArticle first published online: 30 JUL 200 Abstract Initially, it has been shown that the phase thickness and refractivity (the latter interpreted as the difference of the refractivity indices of an object and surrounding medium) depend on the functional state of mitochondria. The refractivity of various objects decreased in response to energy depletion. This dependence was then demonstrated for other biological objects such as cyanobacteria, chloroplasts and human cells. This general response brought about the hypothesis of a certain "universal" factor that links the variable (or metabolic) component of refractivity with the object's functional state. However, the origin of this phenomenon remains unknown. Our hypothesis is founded on the dependence of polarization of bound water molecules and the activity of metabolic processes. Here, we show the results of measurements of metabolic component of refractivity different bio-objects (mitochondria, chloroplasts, spores, cancer cells) obtained using the Coherent Phase Microscope "Airyscan". Estimations indicated high (up to n , 1.41,1.45) values for the equivalent refractive index of structured water in cells. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of Fracture on Bone Turnover Markers: A Longitudinal Study Comparing Marker Levels Before and After Injury in 113 Elderly Women,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2007Kaisa K Ivaska PhD Abstract In this longitudinal, prospective, and population-based study (n = 1044), seven BTMs were assessed before and after trauma in 113 elderly women (85 with fractures). Markers were not altered in the immediate postfracture period but were clearly elevated during fracture repair. Recent fracture should thus be taken into account when markers are used in clinical practice. Introduction: Fracture may influence the levels of bone turnover markers (BTM) and have implications for their use in clinical practice. In this longitudinal, prospective, and population-based study, we assessed prefracture levels of BTMs and compared them with postfracture levels of the same individuals immediately after fracture and during fracture repair. This is the first study in which the effect of fracture on bone markers has been evaluated with prefracture samples available. Materials and Methods: Serum and urine were collected at the emergency unit from 85 women (77.9 ± 1.8 yr) who sustained a fracture after low-energy trauma and 28 controls (77.8 ± 2.0 yr) with similar trauma but no fracture. All were participants of the Malmö OPRA study (n = 1044), and pretrauma samples were collected 1.05 ± 0.85 yr before. Bone turnover was assessed by seven different BTMs reflecting different stages of bone metabolism {C-terminal cross-linked telopeptides of type I collagen [S-CTX], S-TRACP5b, N-terminal propeptides of type I collagen [S-PINP], serum osteocalcin (S-OC[1,49] and S-TotalOC), urinary deoxypyridinoline [U-DPD], and urinary osteocalcin [U-OC]}. Results: BTMs sampled within a few hours after fracture were not altered from preinjury levels. Both bone formation and bone resorption markers were, however, significantly increased 4 mo after fracture. The elevation was most pronounced after hip fracture. Bone turnover remained elevated up to 12 mo after fracture. Conclusions: We believe this study extends our knowledge on the skeletal postfracture metabolic processes. In addition, it may provide a basis for future means to monitor pharmacological intervention promoting fracture healing. [source] Effects of environmental variables on fish feeding ecology: implications for the performance of baited fishing gear and stock assessmentJOURNAL OF FISH BIOLOGY, Issue 6 2004A. W. Stoner The effectiveness of baited fishing gear ultimately depends upon behaviour of the target species , activity rhythms, feeding motivation, and sensory and locomotory abilities. While any environmental parameter that mediates feeding or locomotion can have an important influence on the active space presented by the bait and fish catchability, few biologists have considered how such variation in behaviour might affect catch per unit effort (CPUE) and the resultant stock abundance estimates or population parameters. This review reveals that environment-related variation in feeding behaviour can act through four different mechanisms: metabolic processes, sensory limitations, social interactions and direct impacts. Water temperature, light level, current velocity and ambient prey density are likely to have largest effects on fish catchability, potentially affecting variation in CPUE by a factor of ten. Feeding behaviour is also density-dependent, with both positive and negative effects. Over time and geographic space a target species can occupy wide ranges of environmental conditions, and in certain cases, spatial and temporal variation in feeding biology could have a larger impact on CPUE than patterns of abundance. Temperature, light and current can be measured with relative facility and corrections to stock assessment models are feasible. Making corrections for biological variables such as prey density and bait competitors will be more difficult because the measurements are often not practical and relationships to feeding catchability are more complex and poorly understood. There is a critical need for greater understanding of how environmental variables affect feeding-related performance of baited fishing gear. A combination of field observations and laboratory experiments will be necessary to parameterize stock assessment models that are improved to accommodate variation in fish behaviour. Otherwise, survey data could reveal more about variation in behaviour than abundance trends. [source] Computational Biology Approaches to Plant Metabolism and Photosynthesis: Applications for Corals in Times of Climate Change and Environmental StressJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 8 2010M. James C. Crabbe Knowledge of factors that are important in reef resilience helps us to understand how reef ecosystems react following major anthropogenic and environmental disturbances. The symbiotic relationship between the photosynthetic zooxanthellae algal cells and corals is that the zooxanthellae provide the coral with carbon, while the coral provides protection and access to enough light for the zooxanthellae to photosynthesise. This article reviews some recent advances in computational biology relevant to photosynthetic organisms, including Beyesian approaches to kinetics, computational methods for flux balances in metabolic processes, and determination of clades of zooxanthallae. Application of these systems will be important in the conservation of coral reefs in times of climate change and environmental stress. [source] | ||||||||||||||||||||||||||||||||||