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Cellular Content (cellular + content)
Selected Abstracts,- d -Mannopyranosyl-(1,2)-,- d -glucopyranosyl-(1,2)-glycerate in the thermophilic bacterium Petrotoga miotherma , structure, cellular content and functionFEBS JOURNAL, Issue 12 2007Carla D. Jorge The intracellular accumulation of low molecular mass organic compounds in response to stressful conditions was investigated in the thermophilic bacterium Petrotoga miotherma, a member of the order Thermotogales. This led to the discovery of a new solute, whose structure was established as ,- d -mannopyranosyl-(1,2)-,- d -glucopyranosyl-(1,2)-glycerate (MGG) by MMR spectroscopy and MS. Under optimum growth conditions (3% NaCl; 55 °C), MGG was the major solute [up to 0.6 µmol·(mg protein),1]; ,-glutamate and proline were also present but in minor amounts [below 0.08 µmol·(mg protein),1]. The level of MGG increased notably with the salinity of the growth medium up to the optimum NaCl concentration. At higher NaCl concentrations, however, the level of MGG decreased, whereas the levels of proline and ,-glutamate increased about five-fold and 10-fold, respectively. MGG plays a role during low-level osmotic adaptation of Petrotoga miotherma, whereas ,-glutamate and, to a lesser extent, proline are used for osmoprotection under salt stress. MGG is not part of the cell strategy for coping with heat or oxidative stress. Nevertheless, MGG was an efficient protector of pig heart malate dehydrogenase against heat inactivation and freeze-drying, although mannosylglycerate was better. This is the first report on the occurrence of MGG in living systems. [source] Possible involvement of an FKBP family member protein from a psychrotrophic bacterium Shewanella sp.FEBS JOURNAL, Issue 7 2004SIB1 in cold-adaptation A psychrotrophic bacterium Shewanella sp. strain SIB1 was grown at 4 and 20 °C, and total soluble proteins extracted from the cells were analyzed by two-dimensional polyacrylamide gel electrophoresis. Comparison of these patterns showed that the cellular content of a protein with a molecular mass of 28 kDa and an isoelectric point of four greatly increased at 4 °C compared to that at 20 °C. Determination of the N-terminal amino acid sequence, followed by the cloning and sequencing of the gene encoding this protein, revealed that this protein is a member of the FKBP family of proteins with an amino acid sequence identity of 56% to Escherichia coli FKBP22. This protein was overproduced in E. coli in a His-tagged form, purified, and analyzed for peptidyl-prolyl cis-trans isomerase activity. When this activity was determined by the protease coupling assay using N -succinyl-Ala-Leu-Pro-Phe- p -nitroanilide as a substrate at various temperatures, the protein exhibited the highest activity at 10 °C with a kcat/Km value of 0.87 µm,1·s,1. When the peptidyl-prolyl cis-trans isomerase activity was determined by the RNase T1 refolding assay at 10 and 20 °C, the protein exhibited higher activity at 10 °C with a kcat/Km value of 0.50 µm,1·s,1. These kcat/Km values are lower but comparable to those of E. coli FKBP22. We propose that a FKBP family protein is involved in cold-adaptation of psychrotrophic bacteria. [source] Cultured Granule Cells and Astrocytes from Cerebellum Differ in Metabolizing SphingosineJOURNAL OF NEUROCHEMISTRY, Issue 2 2000Laura Riboni Sphingosine metabolism was studied in primary cultures of differentiated cerebellar granule cells and astrocytes. After a 2-h pulse with [C3 - 3H]sphingosine at different doses (0.1-200 nmol/mg of cell protein), both cell types efficiently incorporated the long chain base ; the percentage of cellular [3H]sphingosine over total label incorporation was extremely low at sphingosine doses of <10 nmol/mg of cell protein and increased at higher doses. Most of the [3H]sphingosine taken up underwent metabolic processing by N -acylation, 1-phosphorylation, and degradation (assessed as 3H2O released in the medium). The metabolic processing of exogenous sphingosine was extremely efficient in both cells, granule cells and astrocytes being able to metabolize, respectively, an amount of sphingosine up to 80- and 300-fold the cellular content of this long chain base in 2 h. At the different doses, the prevailing metabolic route of sphingosine was different. At lower doses and in a wide dose range, the major metabolic fate of sphingosine was N -acylation. With increasing doses, there was first increased sphingosine degradation and then increased levels of sphingosine-1-phosphate. The data demonstrate that, in neurons and astrocytes, the metabolic machinery devoted to sphingosine processing is different, astrocytes possessing an overall higher capacity to synthesize the bioactive compounds ceramide and sphingosine-1-phosphate. [source] Homeostasis of neuroactive amino acids in cultured cerebellar and neocortical neurons is influenced by environmental cuesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1-2 2005Helle Waagepetersen Abstract Neuronal function is highly influenced by the extracellular environment. To study the effect of the milieu on neurons from cerebellum and neocortex, cells from these brain areas were cultured under different conditions. Two sets of cultures, one neocortical and one cerebellar neurons, were maintained in media containing [U- 13C]glucose for 8 days at initial concentrations of 12 and 28 mM glucose, respectively. Other sets of cultures (8 days in vitro) maintained in a medium containing initially 12 mM glucose were incubated subsequently for 4 hr either by addition of [U- 13C]glucose to the culture medium (final concentration 3 mM) or by changing to fresh medium containing [U- 13C]glucose (3 mM) but without glutamine and fetal calf serum. 13C Nuclear magnetic resonance (NMR) spectra revealed extensive ,-aminobutyric acid (GABA) synthesis in both cultured neocortical and cerebellar neurons after maintenance in medium containing [U- 13C]glucose for 8 days, whereas no aspartate labeling was observed in these spectra. Mass spectrometry analysis, however, revealed high labeling intensity of aspartate, which was equal in the two types of neurons. Addition of [U- 13C]glucose (4 hr) on Day 8 in culture led to a similar extent of labeling of GABA in neocortical and in cerebellar cultures, but the cellular content of GABA was considerably higher in the neocortical neurons. The cellular content of alanine was similar regardless of culture type. Comparing the amount of labeling, however, cerebellar neurons exhibited a higher capacity for alanine synthesis. This is compatible with the fact that cerebellar neurons could ameliorate a low alanine content after culturing in low glucose (12 mM) by a 4-hr incubation in medium containing 3 mM glucose. A low glucose concentration during the culture period and a subsequent medium change were associated with decreases in glutathione and taurine contents. Moreover, glutamate and GABA contents were reduced in cerebellar cultures under either of these conditions. In neocortical neurons, the GABA content was decreased by simultaneous exposure to low glucose and change of medium. These conditions also led to an increase in the aspartate content in both types of cultures, although most pronounced in the neocortical neurons. Further experiments are needed to elucidate these phenomena that underline the impact of extracellular environment on amino acid homeostasis. © 2004 Wiley-Liss, Inc. [source] UNCOUPLING OF SILICON COMPARED WITH CARBON AND NITROGEN METABOLISMS AND THE ROLE OF THE CELL CYCLE IN CONTINUOUS CULTURES OF THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) UNDER LIGHT, NITROGEN, AND PHOSPHORUS CONTROL1JOURNAL OF PHYCOLOGY, Issue 5 2002Pascal Claquin The elemental composition and the cell cycle stages of the marine diatom Thalassiosira pseudonana Hasle and Heimdal were studied in continuous cultures over a range of different light- (E), nitrogen- (N), and phosphorus- (P) limited growth rates. In all growth conditions investigated, the decrease in the growth rate was linked with a higher relative contribution of the G2+M phase. The other phases of the cell cycle, G1 and S, showed different patterns, depending on the type of limitation. All experiments showed a highly significant increase in the amount of biogenic silica per cell and per cell surface with decreasing growth rates. At low growth rates, the G2+M elongation allowed an increase of the silicification of the cells. This pattern could be explained by the major uptake of silicon during the G2+M phase and by the independence of this process on the requirements of the other elements. This was illustrated by the elemental ratios Si/C and Si/N that increased from 2- to 6-fold, depending of the type of limitation, whereas the C/N ratio decreased by 10% (E limitation) or increased by 50% (P limitation). The variations of the ratios clearly demonstrate the uncoupling of the Si metabolism compared with the C and N metabolisms. This uncoupling enabled us to explain that in any of the growth condition investigated, the silicification of the cells increased at low growth rates, whereas carbon and nitrogen cellular content are differently regulated, depending of the growth conditions. [source] Restoration of Protein Synthesis in Heart and Skeletal Muscle After Withdrawal of AlcoholALCOHOLISM, Issue 4 2004Thomas C. Vary Abstract: Background: The rate of protein synthesis is diminished after chronic alcohol consumption through changes in both mRNA translation initiation and elongation. It remains unknown how long adverse effects of alcohol on protein synthesis persist after withdrawal from ethanol. Methods: We examined the effect of removal of alcohol from the diet of rats for 72 hr after chronic alcohol exposure (16 weeks) on rates of protein synthesis and potential mechanisms for controlling mRNA translation in heart, skeletal muscle, and liver. Rates of protein synthesis were measured after intravenous infusion of [3H]-l-phenylalanine. The formation of active eukaryotic initiation factor (eIF)4E·eIF4G complex, the cellular content of eukaryotic elongation factor (eEF)1A and eEF2, and the phosphorylation state of eEF2 and S6K1 were measured in each tissue. Results: Withdrawal of alcohol from the diet restored protein synthesis in heart and skeletal muscle to values obtained in pair-fed control rats not exposed to alcohol. However, the organ weight and protein content per muscle was not affected by withdrawal of alcohol from the diet. In both heart and skeletal muscle, the restoration of protein synthesis correlated with reversal of defects in the formation of active eIF4E·eIF4G complex and eEF1A content. Myocardial eEF2 content was also restored to control values after withdrawal of alcohol from the diet. In the gastrocnemius, there was a decrease in the cellular content of eEF2. The lower eIF2 content may have been counterbalanced by an increased activity of eEF2 through a reduction in the phosphorylation state of eEF2 allowing protein synthesis to proceed unimpeded. Conclusions: These studies indicate that changes in protein metabolism observed during chronic alcohol intake are reversible and do not, at this stage, represent an irreversible change in cardiac or skeletal muscle. [source] Birthweight of full-term infants is associated with cord blood CD34+ cell concentrationACTA PAEDIATRICA, Issue 10 2004P Aroviita Aim: CD34+ cell counts are used to define the haematopoietic stem cell potential of a given cord blood transplant. The aim was to test the hypothesis that high concentration of cord blood haematopoietic progenitor and stem cells could be a reflection of intrauterine growth, of which birthweight is an indicator. Methods: Simple and multiple regression analyses were applied to test cord blood bank data on 1368 infants for associations of selected obstetric factors and cellular contents of cord blood. Results: When groups were formed based on the extreme values (5th versus 95th percentiles) of a given variable, e.g. birthweight, the term infants having the highest birthweights were found to have statistically significantly higher median cord blood CD34+ cell concentrations. Also, infants in the top 50th percentile of relative birthweight had higher median CD34+ cell concentration than infants in the low 50th percentile. In multiple regression analysis, the correlation between birthweight and CD34+ cell concentration was statistically clearly significant. Notably, while an expected correlation between gestational age and nucleated cell concentration was found, there was no association between infant gestational age and CD34+ cell concentration. Conclusion: Haematopoietic progenitor and stem cells may reflect intrauterine growth and have a more central role in foetal development than has been reported earlier. [source] | |||||||||||||