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41.
To study selected cardiovascular, thermoregulatory, and hormonal responses to the consumption of glycerol solutions during exercise, nine subjects cycled for 90 min at 50% peak O2 uptake in a 30 degree C, 45% relative humidity environment. Beverages tested included a 10% glycerol solution (G), a 6% carbohydrate-electrolyte beverage (CE), the 6% carbohydrate-electrolyte beverage plus 4% glycerol (CEG), and a water placebo (WP) ingested at regular intervals during the first 60 min of exercise. The beverages were administered in counterbalanced order with subjects serving as their own controls. Ingestion of the glycerol solutions resulted in an increase in plasma osmolality and attenuation of the decrease in plasma volume associated with the WP treatment (P less than 0.05). Plasma renin activity was highest with WP (P less than 0.05), and G was associated with increased antidiuretic hormone levels (P less than 0.05). Ratings of perceived thirst were lowest for CEG and G, and the frequency of gastrointestinal distress was greatest for G (P less than 0.05). However, no differences among beverage treatments were observed for heart rate, esophageal temperature, sweat rate, ratings of perceived exertion, or changes in cortisol and aldosterone levels. These data indicate that there are no substantial metabolic, hormonal, cardiovascular, or thermoregulatory advantages to the consumption of solutions containing 4 or 10% glycerol during exercise. 相似文献
42.
Sébastien J. Puechmaille Benjamin Allegrini Emma S.M. Boston Marie-Jo Dubourg-Savage Allowen Evin Alexandre Knochel Yann Le Bris Vincent Lecoq Michèle Lemaire Delphine Rist Emma C. Teeling 《Mammalian Biology》2012,77(3):224-228
In recent years, new cryptic mammalian species have been discovered in Europe, many of which belong to the order Chiroptera. Within this order, some species such as Myotis nattereri contain several cryptic lineages/species, especially in the Mediterranean region. Here we present genetic, phylogenetic and morphological analysis on the Myotis nattereri species complex, focusing on France which is thought to be a contact zone for the different lineages/species. We sequenced the full Cytochrome b gene from individuals from 23 localities and investigated diagnostic morphological characteristics. Our results reveal new phylogenetic relationships within the Myotis nattereri species complex and among closely related species. We discuss morphological characters which are synapomorphic to each lineage and can be used to differentiate them. Our results also demonstrate the presence of a new lineage within the Myotis nattereri species complex. This lineage, endemic to Corsica, possibly represents a new cryptic species for which we present preliminary ecological data. We further identify the presence of three lineages/species in France and detail their distribution with potential contact zones. 相似文献
43.
Between the end of blooming and the withering of petals of cut carnations ( Dianthus caryophyllus L. cv. Ember), the total superoxide dismutase activity decreased. The three forms of superoxide dismutase (Cu, Zn-SOD, Fe-SOD and Mn-SOD. EC1. 15. 1. 1) identified on polyacrylamide gel exhibited several isozymes, the activities of which decreased sooner or later during aging. The important activity of the Mn-SOD decreased at the beginning of withering to become undetectable, while the weak activity of Fe-SODs declined only at the end of withering. It is suggested that the localization of SODs in the cell may explain these differences. Hypothesis are proposed to understand the decreased activity of SODs during aging. 相似文献
44.
Robert A Miron MJ Champagne C Gingras MC Branton PE Lavoie JN 《The Journal of cell biology》2002,158(3):519-528
In transformed cells, induction of apoptosis by adenovirus type 2 (Ad2) early region 4 ORF 4 (E4orf4) correlates with accumulation of E4orf4 in the cell membrane-cytoskeleton fraction. However, E4orf4 is largely expressed in nuclear regions before the onset of apoptosis. To determine the relative contribution of nuclear E4orf4 versus membrane-associated E4orf4 to cell death signaling, we engineered green fluorescent fusion proteins to target E4orf4 to specific cell compartments. The targeting of Ad2 E4orf4 to cell membranes through a CAAX-box or a myristylation consensus signal sufficed to mimic the fast Src-dependent apoptotic program induced by wild-type E4orf4. In marked contrast, the nuclear targeting of E4orf4 abolished the early induction of extranuclear apoptosis. However, nuclear E4orf4 still induced a delayed cell death response independent of Src-like activity and of E4orf4 tyrosine phosphorylation. The zVAD.fmk-inhibitable caspases were dispensable for execution of both cell death programs. Nevertheless, both pathways led to caspase activation in some cell types through the mitochondrial pathway. Finally, our data support a critical role for calpains upstream in the death effector pathway triggered by the Src-mediated cytoplasmic death signal. We conclude that Ad2 E4orf4 induces two distinct cell death responses, whose relative contributions to cell killing may be determined by the genetic background. 相似文献
45.
Ceni C Muller-Steffner H Lund F Pochon N Schweitzer A De Waard M Schuber F Villaz M Moutin MJ 《The Journal of biological chemistry》2003,278(42):40670-40678
Cyclic ADP-ribose, a metabolite of NAD+, is known to modulate intracellular calcium levels and signaling in various cell types, including neural cells. The enzymes responsible for producing cyclic ADP-ribose in the cytoplasm of mammalian cells remain unknown; however, two mammalian enzymes that are capable of producing cyclic ADP-ribose extracellularly have been identified, CD38 and CD157. The present study investigated whether an ADP-ribosyl cyclase/NAD+-glycohydrolase independent of CD38 is present in brain tissue. To address this question, NAD+ metabolizing activities were accurately examined in developing and adult Cd38-/- mouse brain protein extracts and cells. Low ADP-ribosyl cyclase and NAD+-glycohydrolase activities (in the range of pmol of product formed/mg of protein/min) were detected in Cd38-/- brain at all developmental stages studied. Both activities were found to be associated with cell membranes. The activities were significantly higher in Triton X-100-treated neural cells compared with intact cells, suggesting an intracellular location of the novel cyclase. The cyclase and glycohydrolase activities were optimal at pH 6.0 and were inhibited by zinc, properties which are distinct from those of CD157. Both activities were enhanced by guanosine 5'-O-(3-thiotriphosphate), a result suggesting that the novel enzyme may be regulated by a G protein-dependent mechanism. Altogether our results indicate the presence of an intracellular membrane-bound ADP-ribosyl cyclase/NAD+-glycohydrolase distinct from CD38 and from CD157 in mouse brain. This novel enzyme, which is more active in the developing brain than in the adult tissue, may play an important role in cyclic ADP-ribose-mediated calcium signaling during brain development as well as in adult tissue. 相似文献
46.
The pituitary hormone prolactin (prl) is implicated in a number of biological functions, especially lactation, which is mediated through specific lactogenic receptors (PrlR). Human growth hormone (hGH) is also a pituitary hormone responsible for linear growth. While the growth hormone receptor (hGHR) binds only hGH, hPrlR can interact with both hGH and hPrl. Using structural information from the human growth hormone (hGH)/receptor (hGHR) complex, we modeled by homology a complex between rabbit prolactin hormone (rbPrl) and its receptor (rbPrlR). While the somatogenic hormone/somatogenic receptor (hGH/hGHR) and somatogenic hormone/lactogenic receptor (hGH/hPrlR) interactions are now known and well studied, here we propose a model for the interaction of the lactogenic hormone with its receptor (rbPrl/rbPrlR), and compare these three kinds of ligand/receptor interaction. We identified residues contributing to the active site and tested the potential dimerization of the receptor. Biochemical studies and information deduced from the modeled complex do not exclude a homodimeric form but point to a functional heterodimeric complex. Proteins 27: 459–468, 1997. © 1997 Wiley-Liss, Inc. 相似文献
47.
Fifty-two 3D structures of Ig-like domains covering the immunoglobulin fold family (IgFF) were compared and classified according to the conservation of their secondary structures. Members of the IgFF are distantly related proteins or evolutionarily unrelated proteins with a similar fold, the Ig fold. In this paper, a multiple structural alignment of the conserved common core is described and the correlation between corresponding sequences is discussed. While the members of the IgFF exhibit wide heterogeneity in terms of tissue and species distribution or functional implications, the 3D structures of these domains are far more conserved than their sequences. We define topologically equivalent residues in the Ig-like domains, describe the hydrophobic common cores and discuss the presence of additional strands. The disulfide bridges, not necessary for the stability of the Ig fold, may have an effect on the compactness of the domains. Based upon sequence and structure analysis, we propose the introduction of two new subtypes (C3 and C4) to the previous classifications, in addition to a new global structural classification. The very low mean sequence identity between subgroups of the IgFF suggests the occurrence of both divergent and convergent evolutionary processes, explaining the wide diversity of the superfamily. Finally, this review suggest that hydrophobic residues constituting the common hydrophobic cores are important clues to explain how highly divergent sequences can adopt a similar fold. 相似文献
48.
Rogowski K van Dijk J Magiera MM Bosc C Deloulme JC Bosson A Peris L Gold ND Lacroix B Grau MB Bec N Larroque C Desagher S Holzer M Andrieux A Moutin MJ Janke C 《Cell》2010,143(4):564-578
Polyglutamylation is a posttranslational modification that generates glutamate side chains on tubulins and?other proteins. Although this modification has been shown to be reversible, little is known about the enzymes catalyzing deglutamylation. Here we describe the enzymatic mechanism of protein deglutamylation by members of the cytosolic carboxypeptidase (CCP) family. Three enzymes (CCP1, CCP4, and CCP6) catalyze the shortening of polyglutamate chains and a fourth (CCP5) specifically removes the?branching point glutamates. In addition, CCP1, CCP4, and CCP6 also remove gene-encoded glutamates from the carboxyl termini of proteins. Accordingly, we show that these enzymes convert detyrosinated tubulin into Δ2-tubulin and also modify other substrates, including myosin light chain kinase 1. We further analyze Purkinje cell degeneration (pcd) mice that lack functional CCP1 and show that microtubule hyperglutamylation is directly linked to neurodegeneration. Taken together, our results reveal that controlling the length of the polyglutamate side chains on tubulin is critical for neuronal survival. 相似文献
49.
A new component of bacteriophage Mu replicative transposition machinery: the Escherichia coli ClpX protein 总被引:11,自引:7,他引:11
Amine Mhammedi-Alaoul Martin Pato Marie-Jo Gama Ariane Toussaint 《Molecular microbiology》1994,11(6):1109-1116
We have shown previously that some particular mutations in bacteriophage Mu repressor, the frameshift vir mutations, made the protein very sensitive to the Escherichia coli ATP-dependent Clp protease. This enzyme is formed by the association between a protease subunit (ClpP) and an ATPase subunit. ClpA, the best characterized of these ATPases, is not required for the degradation of the mutant Mu repressors. Recently, a new potential ClpP associated ATPase, ClpX, has been described. We show here that this new subunit is required for Mu vir repressor degradation. Moreover, ClpX (but not ClpP) was found to be required for normal Mu replication. Thus ClpX has activities that do not require its association with ClpP. In the pathway of Mu replicative transposition, the block resides beyond the strand transfer reaction, i.e. after the transposition reaction per se is completed, suggesting that ClpX is required for the transition to the formation of the active replication complex at one Mu end. This is a new clear-cut case of the versatile activity of polypeptides that form multi-component ATP-dependent proteases. 相似文献
50.
E. Ascelijn Reuland Teysir Halaby John P. Hays Denise M. C. de Jongh Henrieke D. R. Snetselaar Marte van Keulen Petra J. M. Elders Paul H. M. Savelkoul Christina M. J. E. Vandenbroucke-Grauls Nashwan al Naiemi 《PloS one》2015,10(1)