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61.
Nathalie Griffon Catherine Pilon François Sautel Jean-Charles Schwartz Pierre Sokoloff 《Journal of neurochemistry》1997,68(1):1-9
Abstract: As cerebral neurons express the dopamine D1 receptor positively coupled with adenylyl cyclase, together with the D3 receptor, we have investigated in a heterologous cell expression system the relationships of cyclic AMP with D3 receptor signaling pathways. In NG108-15 cells transfected with the human D3 receptor cDNA, dopamine, quinpirole, and other dopamine receptor agonists inhibited cyclic AMP accumulation induced by forskolin. Quinpirole also increased mitogenesis, assessed by measuring [3 H]thymidine incorporation. This effect was blocked partially by genistein, a tyrosine kinase inhibitor. Forskolin enhanced by 50–75% the quinpirole-induced [3 H]thymidine incorporation. This effect was maximal with 100 n M forskolin, occurred after 6–16 h, was reproduced by cyclic AMP-permeable analogues, and was blocked by a protein kinase A inhibitor. Forskolin increased D3 receptor expression up to 135%, but only after 16 h and at concentrations of >1 µ M . Thus, in this cell line, the D3 receptor uses two distinct signaling pathways: it efficiently inhibits adenylyl cyclase and induces mitogenesis, an effect possibly involving tyrosine phosphorylation. Activation of the cyclic AMP cascade potentiates the D3 receptor-mediated mitogenic response, through phosphorylation by a cyclic AMP-dependent kinase of a yet unidentified component. Hence, transduction of the D3 receptor can involve both opposite and synergistic interactions with cyclic AMP. 相似文献
62.
Nathalie Doerflinger Catherine Linder Karim Ouahchi Gabor Gyapay Jean Weissenbach Denis Le Paslier Philippe Rigault Samir Belal Christiane Ben Hamida Faycal Hentati Mongi Ben Hamida Massimo Pandolfo Stephano DiDonato Ronald Sokol Herbert Kayden Pierre Landrieu Alexandra Durr Alexis Brice Fran?oise Goutières Alfried Kohlschütter Pascal Sabouraud Ali Benomar Mohamed Yahyaoui Jean-Louis Mandel Michel Koenig 《American journal of human genetics》1995,56(5):1116-1124
Ataxia with vitamin E deficiency (AVED) is an autosomal recessive disease characterized clinically by neurological symptoms with often striking resemblance to those of Friedreich ataxia. This disorder has been reported previously as familial isolated vitamin E deficiency. We have mapped recently the AVED locus to a 5-cM confidence interval on chromosome 8q by homozygosity mapping in six Mediterranean families. We have now analyzed six new and two previously described families and demonstrate genetic homogeneity despite important clinical variability and wide geographic origins. Analysis of nine new tightly linked microsatellite markers, including four characterized in this study, revealed a predominant but not unique mutation in northern African populations, where this condition is more frequent. Haplotype analysis but also classical recombinations allowed us to refine the AVED position to a 1-cM interval. A YAC contig over this interval was constructed from marker STSs and YAC fingerprint data, in order to facilitate the search of the AVED gene. 相似文献
63.
Proteolytic activity of proteasome on myofibrillar structures 总被引:5,自引:0,他引:5
Richard G. Taylor Caroline Tassy Mariele Briand Nathalie Robert Yves Briand Ahmed Ouali 《Molecular biology reports》1995,21(1):71-73
The physiologic function of proteasome remains unclear. Evidence suggests a role in degradation of ubiquitin-protein conjugates, MHC antigen presentation, and some specificity of substrate within certain cell types. To explore further the properties of proteasome we have examined its effect on a well defined structure, the myofibril. We find that despite its large size (20S) proteasome is able to degrade myofibrils and intact, permeabilized muscle fibrils. The proteins degraded showed some specificity because actin, myosin and desmin were degraded faster than -actinin, troponin T and tropomyosin. Changes in ultrastructure were slow and included a general loss of structure with Z and I bands effected before the M band and costameres. 相似文献
64.
Ulrich Flögel Thoralf Niendorf Nathalie Serkowa Annette Brand Joachim Henke Dieter Leibfritz 《Neurochemical research》1995,20(7):793-802
Diffusion-weighted in vivo1H-NMR spectroscopy of F98 glioma cells embedded in basement membrane gel threads showed that the initial cell swelling to about 180% of the original volume induced under hypotonic stress was followed by a regulatory volume decrease to nearly 100% of the control volume in Dulbecco's modified Eagle's medium (DMEM) but only to 130% in Krebs-Henseleit buffer (KHB, containing only glucose as a substrate) after 7 h. The initial cell shrinkage to approx. 70% induced by the hypertonic stress was compensated by a regulatory volume increase which after 7 h reached almost 100% of the control value in KHB and 75% in DMEM.1H-,13C-and31P-NMR spectroscopy of perchloric acid extracts showed that these volume regulatory processes were accompanied by pronounced changes in the content of organic osmolytes. Adaptation of intra- to extracellular osmolarity was preferentially mediated by a decrease in the cytosolic taurine level under hypotonic stress and by an intracellular accumulation of amino acids under hypertonic stress. If these solutes were not available in sufficient quantities (as in KHB), the osmolarity of the cytosol was increasingly modified by biosynthesis of products and intermediates of essential metabolic pathways, such as alanine, glutamate and glycerophosphocholine in addition to ethanolamine. The cellular nucleoside triphosphate level measured by in vivo31P-NMR spectroscopy indicated that the energy state of the cells was more easily sustained under hypotonic than hypertonic conditions.To whom to address reprint requests. 相似文献
65.
A new monoclonal antibody (3D3) generated with human respiratory mucins and directed against Lewis determinants 总被引:1,自引:1,他引:0
Nathalie Emery; Palfa Shirley B.; Place Graham; Oriol Rafael; Hall Roderick L.; Roussel Philippe; Lhermitte Michel 《Glycobiology》1995,5(6):563-570
We have prepared a monoclonal antibody (MAb), 3D3, raised againstpurified human respiratory mucins. This antibody recognizedmucins and proteolytically derived glycopeptides. The epitoperecognized by the antibody was destroyed by -L-fucosidase, indicatingthat it was present on the carbohydrate moieties. Structuralspecificity was determined by adsorption on a variety of synthetic,insolubilized oligosaccharides. Several lines of evidence indicatethat the 3D3 MAb reacted strongly with the Lewis (Leb) antigen,but also recognized Lea and Ley determinants. This antibodymight be useful to study mucin secretion. human bronchial mucins Lewis b 相似文献
66.
67.
Enzymatic conversion of adenosine to inosine in the wobble position of yeast tRNAAsp: the dependence on the anticodon sequence. 总被引:9,自引:4,他引:5 下载免费PDF全文
We have investigated the specificity of the tRNA modifying enzyme that transforms the adenosine at position 34 (wobble position) into inosine in the anticodon of several tRNAs. For this purpose, we have constructed sixteen recombinants of yeast tRNAAsp harboring an AXY anticodon (where X or Y was one of the four nucleotides A, G, C or U). This was done by enzymatic manipulations in vitro of the yeast tRNAAsp, involving specific hydrolysis with S1-nuclease and RNAase A, phosphorylation with T4-polynucleotide kinase and ligation with T4-RNA ligase: it allowed us to replace the normal anticodon GUC by trinucleotides AXY and to introduce simultaneously a 32P-labelled phosphate group between the uridine at position 33 and the newly inserted adenosine at position 34. Each of these 32P-labelled AXY "anticodon-substituted" yeast tRNAAsp were microinjected into the cytoplasm of Xenopus laevis oocytes and assayed for their capacity to act as substrates for the A34 to I34 transforming enzyme. Our results indicate that: 1/ A34 in yeast tRNAAsp harboring the arginine anticodon ACG or an AXY anticodon with a purine at position 35 but with A, G or C but not U at position 36 were efficiently modified into I34; 2/ all yeast tRNAAsp harboring an AXY anticodon with a pyrimidine at position 35 (except ACG) or uridine at position 36 were not modified at all. This demonstrates a strong dependence on the anticodon sequence for the A34 to I34 transformation in yeast tRNAAsp by the putative cytoplasmic adenosine deaminase of Xenopus laevis oocytes. 相似文献
68.
Monique Bedin Dominique Weil Thérèse Fournier Lise Cedard Jean Frezal 《Human genetics》1981,59(3):256-258
Summary Steroid sulfatase activities are significantly higher in placentas obtained after the birth of girls than after the birth of boys, and also in female fibroblasts compared to male strains. This constitutes biochemical evidence for the non-inactivation of the X-linked sulfatase locus. No hydrolytic activity is found in the fibroblasts of ichthyotic boys. Heterozygosity is demonstrated in the fibroblasts of the four mothers studied, as they have steroid sulfatase activity of less or equivalent to the normal male value. 相似文献
69.
70.
Production of type 5 capsular polysaccharide by Staphylococcus aureus grown in a semi-synthetic medium 总被引:4,自引:0,他引:4
The concentration of the type 5 capsular polysaccharide (CP) antigen of Staphylococcus aureus can be measured directly in cultures or cell suspensions by a two-step inhibition enzyme-linked immunosorbent assay (ELISA), using monoclonal antibodies. CP was synthesized during growth on a variety of carbon substrates and its production was not affected by the nature of the carbon source. High levels of yeast extract inhibited CP formation. CP was synthesized in batch culture at the same rate during exponential growth as in the post-exponential phase. Post-exponential CP production contributed at least half the final amount of CP measured. This phenomenon was observed in different culture media, although the specific yield of polysaccharide varied from one medium to another. Post-exponential CP production was observed in the pH range 6-7, but not at pH 8. Post-exponential production was strictly dependent on oxygen availability and did not occur under anaerobic conditions. 相似文献