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81.
82.
Serradeil-Le Gal C Raufaste D Derick S Blankenstein J Allen J Pouzet B Pascal M Wagnon J Ventura MA 《American journal of physiology. Regulatory, integrative and comparative physiology》2007,293(2):R938-R949
[(3)H]SSR-149415 is the first tritiated nonpeptide vasopressin V(1b) receptor (V(1b)R) antagonist ligand. It was used for studying rodent (mouse, rat, hamster) and human V(1b)R from native or recombinant origin. Moreover, a close comparison between the human and the mouse V(1b)R was performed using SSR-149415/[(3)H]SSR-149415 in binding and functional studies in vitro. [(3)H]SSR-149415 binding was time-dependent, reversible, and saturable. Scatchard plot analysis gave a single class of high-affinity binding sites with apparent equilibrium dissociation constant (K(d)) approximately 1 nM and maximum binding density (B(max)) values from 7,000 to 300,000 sites/cell according to the cell line. In competition experiments, [(3)H]SSR-149415 binding was stereospecific and dose-dependently displaced by reference peptide and nonpeptide arginine vasopressin (AVP)/OT ligands following a V(1b) rank order of affinity: SSR-149415 = AVP > dCha > dPen > dPal > dDavp > SSR-126768A > SR-49059 > SSR-149424 > OT > SR-121463B. Species differences between human, rat, mouse, and hamster V(1b)R were observed. Autoradiography studies with [(3)H]SSR-149415 on rat and human pituitary showed intense specific labeling confined to corticotroph cells and absence of labeling in the other tissues examined. SSR-149415 potently and stereospecifically antagonized the AVP-induced inositol phosphate production and intracellular Ca(2+) increase (EC(50) from 1.83 to 3.05 nM) in recombinant cell lines expressing either the mouse or the human V(1b)R. AVP (10(-7) M) exposure of AtT20 cells expressing mouse or human EGFP-tagged V(1b)R induced their rapid internalization. Preincubation with 10(-6) M SSR-149415 counteracted the internalization process. Moreover, recycling of internalized receptors was observed upon 10(-6) M SSR-149415 treatment. Thus SSR-149415/[(3)H]SSR-149415 are unique tools for studying animal and human V(1b)R. 相似文献
83.
Beuerle T Theuring C Klewer N Schulz S Hartmann T 《Insect biochemistry and molecular biology》2007,37(1):80-89
Arctiids which as larvae sequester pyrrolizidine alkaloids (PAs) from their food plants are known to synthesize insect-specific PAs by esterifying necine bases derived from plant PAs with necic acids of insect origin. There are two classes of insect PAs, the creatonotines and the callimorphines. The creatonotines contain as necic acids either 2-hydroxy-3-methylbutyric acid (creatonotine A) or 2-hydroxy-3-methylpentanoic acid (creatonotine B). The three known callimorphines contain 2-hydroxy-2-methylbutanoic acid whose hydroxyl group can be either free (deacetylcallimorphine) or acetylated (callimorphine) or propionylated (homocallimorphine). Insect PAs are assumed to play an important role in the recycling of plant derived necine bases and the processing by trans-esterification of PA monoesters that cannot be directly transmitted to the insect's pupal and adult life-stages. The absolute configuration of the insect-specific necic acids was elucidated in the context of the suggested role of the insect PAs as insect-made mimics of plant monoester PAs of the lycopsamine type. For this purpose all needed stereoisomers were synthesized and a gas chromatography-mass spectrometry (GC-MS) method was established that allows the enantioselective separation and assignment of the stereochemistry of all insect specific necic acids as their methyl esters. The method could also be applied to the GC-MS analysis of the intact alkaloids which were hydrolyzed during injection and converted into their methyl esters. Analysis of the creatonotines and callimorphines isolated from the polyphagous arctiids Estigmene acrea and Grammia geneura that were fed with pure PAs and defined PA mixtures revealed the following absolute configuration: the callimorphines and creatonotine A were present in 2'R configuration, whereas creatonotine B was found as mixture of (2'R, 3'S)- and (2'S, 3'S)-stereoisomers. The ratio of 2'S to 2'R was extremely variable ranging from 98% S to 94% R. The cause of the lack of stereospecificity is discussed particularly in respect of a possible epimerization of the hydroxyl group at C-2' in analogy to the known epimerization at C-3' of plant acquired PAs of the lycopsamine type. 相似文献
84.
Indel evolution of mammalian introns and the utility of non-coding nuclear markers in eutherian phylogenetics 总被引:6,自引:0,他引:6
Matthee CA Eick G Willows-Munro S Montgelard C Pardini AT Robinson TJ 《Molecular phylogenetics and evolution》2007,42(3):827-837
Nuclear DNA intron sequences are increasingly used to investigate evolutionary relationships among closely related organisms. The phylogenetic usefulness of intron sequences at higher taxonomic levels has, however, not been firmly established and very few studies have used these markers to address evolutionary questions above the family level. In addition, the mechanisms driving intron evolution are not well understood. We compared DNA sequence data derived from three presumably independently segregating introns (THY, PRKC I and MGF) across 158 mammalian species. All currently recognized extant eutherian mammalian orders were included with the exception of Cingulata, Dermoptera and Scandentia. The total aligned length of the data was 6366 base pairs (bp); after the exclusion of autapomorphic insertions, 1511 bp were analyzed. In many instances the Bayesian and parsimony analyses were complementary and gave significant posterior probability and bootstrap support (>80) for the monophyly of Afrotheria, Euarchontoglires, Laurasiatheria and Boreoeutheria. Apart from finding congruent support when using these methods, the intron data also provided several indels longer than 3 bp that support, among others, the monophyly of Afrotheria, Paenungulata, Ferae and Boreoeutheria. A quantitative analysis of insertions and deletions suggested that there was a 75% bias towards deletions. The average insertion size in the mammalian data set was 16.49 bp +/- 57.70 while the average deletion was much smaller (4.47 bp +/- 14.17). The tendency towards large insertions and small deletions is highlighted by the observation that out of a total of 17 indels larger than 100 bp, 15 were insertions. The majority of indels (>60% of all events) were 1 or 2 bp changes. Although the average overall indel substitution rate of 0.00559 per site is comparable to that previously reported for rodents and primates, individual analyses among different evolutionary lineages provide evidence for differences in the formation rate of indels among the different mammalian groups. 相似文献
85.
Petri net modelling of biological networks 总被引:5,自引:0,他引:5
Chaouiya C 《Briefings in bioinformatics》2007,8(4):210-219
Mathematical modelling is increasingly used to get insights into the functioning of complex biological networks. In this context, Petri nets (PNs) have recently emerged as a promising tool among the various methods employed for the modelling and analysis of molecular networks. PNs come with a series of extensions, which allow different abstraction levels, from purely qualitative to more complex quantitative models. Noteworthily, each of these models preserves the underlying graph, which depicts the interactions between the biological components. This article intends to present the basics of the approach and to foster the potential role PNs could play in the development of the computational systems biology. 相似文献
86.
Navet R Mathy G Douette P Dobson RL Leprince P De Pauw E Sluse-Goffart C Sluse FE 《Journal of proteome research》2007,6(1):25-33
Cold acclimation induces an adaptative increase in respiration in brown adipose tissue (BAT). A comparative analysis by two-dimensional differential in-gel electrophoresis of mitochondrial protein patterns found in rat control and cold-acclimated BAT was performed. A total of 58 proteins exhibiting significant differences in their abundance was unambiguously identified. Proteins implicated in the major catabolic pathways were up-regulated as were ATP synthase and mitofilin. Moreover, these results support the fact that adipocytes can balance their ATP synthesis and their heat production linked to UCP1-sustained uncoupling. 相似文献
87.
Nemecek Thomas Antón Assumpció Basset-Mens Claudine Gentil-Sergent Céline Renaud-Gentié Christel Melero Carlos Naviaux Pierre Peña Nancy Roux Philippe Fantke Peter 《The International Journal of Life Cycle Assessment》2022,27(4):527-542
The International Journal of Life Cycle Assessment - Current field emission modelling and toxicity characterisation of pesticides suffer from several shortcomings like mismatches between LCI... 相似文献
88.
Stéphanie Dupoiron Claudine Zischek Laetitia Ligat Julien Carbonne Alice Boulanger Thomas Dugé de Bernonville Martine Lautier Pauline Rival Matthieu Arlat Elisabeth Jamet Emmanuelle Lauber Cécile Albenne 《The Journal of biological chemistry》2015,290(10):6022-6036
N-Glycans are widely distributed in living organisms but represent only a small fraction of the carbohydrates found in plants. This probably explains why they have not previously been considered as substrates exploited by phytopathogenic bacteria during plant infection. Xanthomonas campestris pv. campestris, the causal agent of black rot disease of Brassica plants, possesses a specific system for GlcNAc utilization expressed during host plant infection. This system encompasses a cluster of eight genes (nixE to nixL) encoding glycoside hydrolases (GHs). In this paper, we have characterized the enzymatic activities of these GHs and demonstrated their involvement in sequential degradation of a plant N-glycan using a N-glycopeptide containing two GlcNAcs, three mannoses, one fucose, and one xylose (N2M3FX) as a substrate. The removal of the α-1,3-mannose by the α-mannosidase NixK (GH92) is a prerequisite for the subsequent action of the β-xylosidase NixI (GH3), which is involved in the cleavage of the β-1,2-xylose, followed by the α-mannosidase NixJ (GH125), which removes the α-1,6-mannose. These data, combined to the subcellular localization of the enzymes, allowed us to propose a model of N-glycopeptide processing by X. campestris pv. campestris. This study constitutes the first evidence suggesting N-glycan degradation by a plant pathogen, a feature shared with human pathogenic bacteria. Plant N-glycans should therefore be included in the repertoire of molecules putatively metabolized by phytopathogenic bacteria during their life cycle. 相似文献
89.
David Gendron Anne-Marie Lemay Claudine Tremblay Laetitia JA Lai Anick Langlois émilie Bernatchez Nicolas Flamand Marie-Renée Blanchet Anthony S Don Ynuk Bossé élyse Bissonnette David Marsolais 《Respiratory research》2015,16(1)
Background
In vivo phosphorylation of sphingosine analogs with their ensuing binding and activation of their cell-surface sphingosine-1-phosphate receptors is regarded as the main immunomodulatory mechanism of this new class of drugs. Prophylactic treatment with sphingosine analogs interferes with experimental asthma by impeding the migration of dendritic cells to draining lymph nodes. However, whether these drugs can also alleviate allergic airway inflammation after its onset remains to be determined. Herein, we investigated to which extent and by which mechanisms the sphingosine analog AAL-R interferes with key features of asthma in a murine model during ongoing allergic inflammation induced by Dermatophagoides pteronyssinus.Methods
BALB/c mice were exposed to either D. pteronyssinus or saline, intranasally, once-daily for 10 consecutive days. Mice were treated intratracheally with either AAL-R, its pre-phosphorylated form AFD-R, or the vehicle before every allergen challenge over the last four days, i.e. after the onset of allergic airway inflammation. On day 11, airway responsiveness to methacholine was measured; inflammatory cells and cytokines were quantified in the airways; and the numbers and/or viability of T cells, B cells and dendritic cells were assessed in the lungs and draining lymph nodes.Results
AAL-R decreased airway hyperresponsiveness induced by D. pteronyssinus by nearly 70%. This was associated with a strong reduction of IL-5 and IL-13 levels in the airways and with a decreased eosinophilic response. Notably, the lung CD4+ T cells were almost entirely eliminated by AAL-R, which concurred with enhanced apoptosis/necrosis in that cell population. This inhibition occurred in the absence of dendritic cell number modulation in draining lymph nodes. On the other hand, the pre-phosphorylated form AFD-R, which preferentially acts on cell-surface sphingosine-1-phosphate receptors, was relatively impotent at enhancing cell death, which led to a less efficient control of T cell and eosinophil responses in the lungs.Conclusion
Airway delivery of the non-phosphorylated sphingosine analog, but not its pre-phosphorylated counterpart, is highly efficient at controlling the local T cell response after the onset of allergic airway inflammation. The mechanism appears to involve local induction of lymphocyte apoptosis/necrosis, while mildly affecting dendritic cell and T cell accumulation in draining lymph nodes. 相似文献90.
Imanishi L Vayssières A Franche C Bogusz D Wall L Svistoonoff S 《Molecular plant-microbe interactions : MPMI》2011,24(11):1317-1324
Among infection mechanisms leading to root nodule symbiosis, the intercellular infection pathway is probably the most ancestral but also one of the least characterized. Intercellular infection has been described in Discaria trinervis, an actinorhizal plant belonging to the Rosales order. To decipher the molecular mechanisms underlying intercellular infection with Frankia bacteria, we set up an efficient genetic transformation protocol for D. trinervis based on Agrobacterium rhizogenes. We showed that composite plants with transgenic roots expressing green fluorescent protein can be specifically and efficiently nodulated by Frankia strain BCU110501. Nitrogen fixation rates and feedback inhibition of nodule formation by nitrogen were similar in control and composite plants. In order to challenge the transformation system, the MtEnod11 promoter, a gene from Medicago truncatula widely used as a marker for early infection-related symbiotic events in model legumes, was introduced in D. trinervis. MtEnod11::GUS expression was related to infection zones in root cortex and in the parenchyma of the developing nodule. The ability to study intercellular infection with molecular tools opens new avenues for understanding the evolution of the infection process in nitrogen-fixing root nodule symbioses. 相似文献