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991.
Guillemente Huet Colette Richet Dominique Demeyer Hervé Bisiau Benoit Soudan Daniel Tetaert Pierre Degand 《生物化学与生物物理学报:疾病的分子基础》1992,1138(3):213-221
The variant surface glycoprotein of African trypanosomes is released after overnight incubation of parasites at 4°C in pH 5.5 phosphate glucose buffer and may be purified by Concanavalin A Sepharose affinity chromatography [1]. The addition of proteinase inhibitors during the parasite incubation is necessary to prevent the proteolysis of the variant surface glycoproteins by the trypanosomal released proteinases. Using this procedure without the addition of proteinase inhibitors, the proteolytic activities, released from the bloodstream forms Trypanosoma brucei brucei variant AnTat 1.1, were separated by Concanavalin-A Sepharose affinity chromatography. The unretained material (F1) shows hydrolytic activity against the two synthetic substrates Z-Phe-Arg-AMC and Z-Arg-Arg-AMC, which is stimulated by dithiothreitol, but not inhibited by E-64, and characterized by and alkaline pH optimum and an estimated molecular mass of 80–100 kDa. The Michaelis constant for the substrates Z-Arg-Arg-AMC and Z-Phe-Arg-AMC was, respectively, 2.8 and 6.7 μM. The retained material eluted by addition of 1% methyl-α-D-mannopyranoside (F2) shows hydrolytic activity against the synthetic substrate Z-Phe-Arg-AMC, which is stimulated by dithiothreitol, inhibited by E-64, active between pH 6.0 and 8.0, and could be separated into two peaks of activity by HPLC, one peak of high molecular mass (> 70 kDa) and the other peak of lower molecular mass (30–70 kDa). By electrophoresis in gels containing gelatin as substrate, this fraction contains several proteins with gelatinolytic activity, whereas the unretained fraction F1 did not have any gelatinolytic activity. 相似文献
992.
S. K. Gupta M. Altares R. Benoit R. J. Riopelle R. J. Dunn P. M. Richardson 《Developmental neurobiology》1992,23(5):481-490
CNTF (ciliary neurotrophic factor), purified from rabbit sciatic nerves by a relatively simple procedure, is bioactive in tissue culture at low picomolar concentration and appears as a doublet on polyacrylamide gel electrophoresis (PAGE). In these nerves, CNTF accounts for more than one-half of the survival-promoting activity on ciliary neurons. The concentration of CNTF in rabbit sciatic nerves is estimated to be 5 nmol/kg, more than 1000 times higher than would seem to be required to support neurons if the neurotrophic factor were homogeneously distributed. With recombinant DNA technology, rat CNTF has been synthesized in Escherichia coli, purified without denaturating agents, and found to be bioactive at a slightly lower concentration than CNTF extracted from rabbit sciatic nerves. After radioiodination, CNTF retains biological activity but is not specifically internalized and retrogradely transported in motor and sensory axons. In peripheral nerves, ciliary neurotrophic factor differs biologically from nerve growth factor (NGF) by its much higher tissue concentration and apparent lack of internalization by peripheral nerve axons. © 1992 John Wiley & Sons, Inc. 相似文献
993.
The ornithine aminotransferase (OAT) locus: analysis of RFLPs in gyrate atrophy. 总被引:6,自引:2,他引:4 下载免费PDF全文
V Ramesh L A Benoit P Crawford P T Harvey T B Shows V E Shih J F Gusella 《American journal of human genetics》1988,42(2):365-372
A cDNA probe (HOAT1) for ornithine aminotransferase (OAT) has recently been used to map (1) the structural gene for this enzyme to chromosome 10 and (2) several related DNA sequences to the X chromosome. We have defined six RFLPs for OAT, to explore its possible role in gyrate atrophy (GA) of the choroid and retina, an autosomal recessive genetic disorder associated with a deficiency of OAT activity. The RFLPs, which are detected by noncoding single-copy probes from the OAT gene and by subclones of the HOAT1 cDNA, all map on human chromosome 10, producing an overall level of heterozygosity for the OAT locus of 83%. Using the RFLPs, we have determined that the OAT locus segregates concordantly with GA in one available pedigree. Furthermore, the RFLPs display significant disequilibrium with GA, providing genetic evidence implicating a defect in the OAT structural gene as the cause of this disorder. The RFLPs for OAT are potentially applicable to prenatal diagnosis and carrier detection in families with a previous history of GA. They will also allow identification of specific haplotypes associated with GA chromosomes, as a guide for more detailed molecular-genetic investigations of the mutations underlying the disorder. 相似文献
994.
Fitness effects of amino acid replacements in the beta-galactosidase of Escherichia coli 总被引:7,自引:1,他引:6
Two genetic procedures were used to obtain amino acid replacements in the
lacZ-encoded beta-galactosidase in Escherichia coli. Amino acid
replacements could be obtained without regard to their effects on lactase
activity by selecting spontaneous mutations that relieved the strong
polarity of six nonsense mutations. When streaked on MacConkey- lactose
indicator plates, approximately 75% of these mutants gave strong red
lactose-fermenting colonies, and 25% gave white nonfermenting colonies.
Mutants from 11 other nonsense codons were isolated directly using
MacConkey-lactose indicator plates, on which positive color indication
requires only 0.5% of the wildtype lactase activity. Among the total of 17
codons, 25 variant beta-galactosidases were identified using
electrophoresis and thermal denaturation studies. The fitness effects of
these variant beta-galactosidases were determined using competition
experiments conducted with lactose as the sole nutrient limiting the growth
rate in chemostat cultures. Three of the replacements were deleterious, one
was selectively advantageous, and the selective effects of the remaining 21
were undetectable under conditions in which the smallest detectable
selection coefficient was approximately 0.4%/generation.
相似文献
995.
As one of the 17 megadiverse countries of the world and with four biodiversity hotspots
represented in its borders, India is home to an impressive diversity of life forms.
However, much work remains to document and catalogue the species of India and their
geographic distributions, especially for diverse invertebrate groups. In the present
study, a comprehensive and critical list of Indian ant species is provided with up-to-date
state-wise distribution. A total of 828 valid species and subspecies names belonging to
100 genera are listed from India. Potential erroneous data, misidentifications and dubious
distributional records that may exist in the literature are also identified. The present
exhaustive listing of Indian ants will provide a holistic view about diversity and
distribution and will also help to identify major undersampled areas where future sampling
and taxonomic efforts should be directed. 相似文献
996.
Alexandre Seyer Samia Boudah Simon Broudin Christophe Junot Benoit Colsch 《Metabolomics : Official journal of the Metabolomic Society》2016,12(5):91
Introduction
Due to its proximity with the brain, cerebrospinal fluid (CSF) could be a medium of choice for the discovery of biomarkers of neurological and psychiatric diseases using untargeted analytical approaches.Objectives
This study explored the CSF lipidome in order to generate a robust mass spectral database using an untargeted lipidomic approach.Methods
Cerebrospinal fluid samples from 45 individuals were analyzed by liquid chromatography coupled to high-resolution mass spectrometry method (LC-HRMS). A dedicated data processing workflow was implemented using XCMS software and adapted filters to select reliable features. In addition, an automatic annotation using an in silico lipid database and several MS/MS experiments were performed to identify CSF lipid species.Results
Using this complete workflow, 771 analytically relevant monoisotopic lipid species corresponding to 550 unique lipids which represent five major lipid families (i.e., free fatty acids, sphingolipids, glycerophospholipids, glycerolipids, and sterol lipids) were detected and annotated. In addition, MS/MS experiments enabled to improve the annotation of 304 lipid species. Thanks to LC-HRMS, it was possible to discriminate between isobaric and also isomeric lipid species; and interestingly, our study showed that isobaric ions represent about 50 % of the total annotated lipid species in the human CSF.Conclusion
This work provides an extensive LC/HRMS database of the human CSF lipidome which constitutes a relevant foundation for future studies aimed at finding biomarkers of neurological disorders.997.
The Vat‐AIEC protease promotes crossing of the intestinal mucus layer by Crohn's disease‐associated Escherichia coli 下载免费PDF全文
998.
Diversity of genetic backgrounds modulating the durability of a major resistance gene. Analysis of a core collection of pepper landraces resistant to Potato virus Y 下载免费PDF全文
Julie Quenouille Ludovic Saint‐Felix Benoit Moury Alain Palloix 《Molecular Plant Pathology》2016,17(2):296-302
The evolution of resistance‐breaking capacity in pathogen populations has been shown to depend on the plant genetic background surrounding the resistance genes. We evaluated a core collection of pepper (Capsicum annuum) landraces, representing the worldwide genetic diversity, for its ability to modulate the breakdown frequency by Potato virus Y of major resistance alleles at the pvr2 locus encoding the eukaryotic initiation factor 4E (eIF4E). Depending on the pepper landrace, the breakdown frequency of a given resistance allele varied from 0% to 52.5%, attesting to their diversity and the availability of genetic backgrounds favourable to resistance durability in the plant germplasm. The mutations in the virus genome involved in resistance breakdown also differed between plant genotypes, indicating differential selection effects exerted on the virus population by the different genetic backgrounds. The breakdown frequency was positively correlated with the level of virus accumulation, confirming the impact of quantitative resistance loci on resistance durability. Among these loci, pvr6, encoding an isoform of eIF4E, was associated with a major effect on virus accumulation and on the breakdown frequency of the pvr2‐mediated resistance. This exploration of plant genetic diversity delivered new resources for the control of pathogen evolution and the increase in resistance durability. 相似文献
999.
Véronique Desgagné Simon-Pierre Guay Renée Guérin François Corbin Patrick Couture Benoit Lamarche 《Epigenetics》2016,11(6):438-448
A high consumption of trans fatty acids (TFAs) is associated with an increased risk of cardiovascular diseases (CVDs). High-density lipoproteins (HDLs) have many cardioprotective properties and transport functional microRNAs (miRNAs) to recipient cells. We hypothesized that dietary TFAs modify the HDL-carried miRNA profile, therefore modulating its cardioprotective properties. We assessed whether consumption of dietary TFAs modifies HDL-carried miR-223-3p and miR-135a-3p concentration and the inter-relationship between diet-induced changes in HDL-carried miRNA concentration and CVD risk markers. In a double blind, randomized, crossover, controlled study, 9 men were fed each of 3 experimental isoenergetic diets: 1) High in industrial TFA (iTFA; 3.7% energy); 2) High in TFA from ruminants (rTFA; 3.7% energy); 3) Low in TFA (control; 0.8% energy) for 4 weeks each. HDLs were isolated by ultracentrifugation and miRNAs were quantified by RT-qPCR. Variations in HDL-miR-223-3p concentration were negatively correlated with variations in HDL-cholesterol after the iTFA diet (rs = 0.82; P = 0.007), and positively correlated with variations in C-reactive protein concentration after the rTFA diet (rs = 0.75; P = 0.020). Variations in HDL-miR-135a-3p concentration were positively correlated with variations in total triglyceride (TG) concentration following the iTFA diet (rs = ?0.82; P = 0.007), and with variations in low-density lipoprotein (LDL)-TG concentration following the rTFA diet (rs = 0.83; P = 0.005), compared to the control diet. However, the consumption of dietary TFAs has no significant unidirectional impact on HDL-carried miR-223-3p and miR-135a-3p concentrations. Our results suggest that the variability in the HDL-carried miRNAs response to TFA intake, by being associated with variations in CVD risk factors, might reflect physiological changes in HDL functions. 相似文献
1000.
Jacques De Grève Jan Van Meerbeeck Johan F. Vansteenkiste Lore Decoster Anne-Pascale Meert Peter Vuylsteke Christian Focan Jean-Luc Canon Yves Humblet Guy Berchem Benoit Colinet Danny Galdermans Lionel Bosquée Joanna Vermeij Alex Dewaele Caroline Geers Denis Schallier Erik Teugels 《PloS one》2016,11(3)