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1.
2.
Identification and expression of water stress- and abscisic acid-regulated genes in a drought-tolerant sunflower genotype 总被引:17,自引:0,他引:17
3.
Karine Cahier Damien Piel Rubén Barcia-Cruz David Goudenège K. Mathias Wegner Marc Monot Jesús L. Romalde Frédérique Le Roux 《Environmental microbiology》2023,25(8):1424-1438
Phages depend on their bacterial hosts to replicate. The habitat, density and genetic diversity of host populations are therefore key factors in phage ecology, but our ability to explore their biology depends on the isolation of a diverse and representative collection of phages from different sources. Here, we compared two populations of marine bacterial hosts and their phages collected during a time series sampling program in an oyster farm. The population of Vibrio crassostreae, a species associated specifically to oysters, was genetically structured into clades of near clonal strains, leading to the isolation of closely related phages forming large modules in phage–bacterial infection networks. For Vibrio chagasii, which blooms in the water column, a lower number of closely related hosts and a higher diversity of isolated phages resulted in small modules in the phage–bacterial infection network. Over time, phage load was correlated with V. chagasii abundance, indicating a role of host blooms in driving phage abundance. Genetic experiments further demonstrated that these phage blooms can generate epigenetic and genetic variability that can counteract host defence systems. These results highlight the importance of considering both the environmental dynamics and the genetic structure of the host when interpreting phage–bacteria networks. 相似文献
4.
Arques Didier G.; Michel Christian J.; Orieux Karine 《Bioinformatics (Oxford, England)》1992,8(1):5-14
The software AGE (Analysis of Gene Evolution) has been developedboth to study a genetic reality, i. e. the identification ofstatistical properties in genes (e.g. periodicities), and tosimulate this observed genetic reality, by models of molecularevolution. AGE has two types of models: (i) models of sequencecreation from oligonucleotides: concatenation model in seriesof an oligonucleotide, independent (or Markov) mixing modelof oligonucleotides according to given probabilities (or a Markovmatrix); (ii) models of sequence evolution from created sequences:insertion/deletion process of (mono, di, tri)nucleot-ides, basemutation process. The study of a reality and the developmentof simulation models are based on several new algorithms: approximatedsimulation and exact calculus to compute various autocorrelationfunctions, Fourier transformation of autocorrelation curves,recognition of a curve form, etc. AGE is implemented on IBMor compatible microcomputers and can be used by biologists withoutany computer knowledge to identify statistical properties intheir newly determined DNA sequence and to explain them by modelsof molecular evolution. 相似文献
5.
Thierry Pillot Anne Barbier Athanase Visvikis Karine Lozac'h Maryvonne Rosseneu Joel Vandekerckhove Gérard Siest 《Protein expression and purification》1996,7(4):407-414
We have cloned, from total human liver RNA, the cDNA encoding apolipoprotein E3 (apoE3). Site-directed mutagenesis was used to obtain the cDNA encoding the apoE4 isoform, a major variant of this apolipoprotein in man. These two cDNAs were subcloned into the procaryotic expression vector pAHRS. A polyhistidine tag was added at the NH2-termini of the recombinant proteins (apoE3 and apoE4) to enable rapid purification. The resulting plasmids (pAHRS-apoE3 and pAHRS-apoE4) were introduced into theEscherichia colistrain BL21(DE3). Recombinant strains were grown at 37°C in a Luria and Bertani medium and the addition of isopropyl β-thiogalactoside resulted in the expression of large amounts of apoE protein (40.5 kDa), representing at least 15% of cellular proteins. The recombinant apoE isoforms were purified, under denaturating conditions, in one step by affinity chromatography on a Ni-chelated agarose column, yielding to about 20 mg of 96% pure protein per liter of culture. Compared to plasma apoE3 purified from human very low density lipoproteins, the two renatured recombinant apoE isoforms have the same secondary structure content, as revealed by circular dichroism measurement. Moreover, the recombinant apoE3 isoform shares similar properties for the association with lipids, compared to the human protein, indicating that the addition of the amino-terminal polyhistidine peptide does not influence the structure and the lipid binding properties of this recombinant apoE isoform. No differences in the secondary structure of recombinant apoE4 were detected, whereas this isoform presents specific reactivity with lipids. This simple and rapid procedure for the expression and the purification of functional recombinant apoE should therefore enable structural and physiological studies requiring large amounts of these apolipoproteins. 相似文献
6.
Maynard C Berthiaume F Lemarchand K Harel J Payment P Bayardelle P Masson L Brousseau R 《Applied and environmental microbiology》2005,71(12):8548-8557
A small-oligonucleotide microarray prototype was designed with probes specific for the universal 16S rRNA and cpn60 genes of several pathogens that are usually encountered in wastewaters. In addition to these two targets, wecE-specific oligonucleotide probes were included in the microarray to enhance its discriminating power within the Enterobacteriaceae family. Universal PCR primers were used to amplify variable regions of 16S rRNA, cpn60, and wecE genes directly in Escherichia coli and Salmonella enterica serovar Typhimurium genomic DNA mixtures (binary); E. coli, S. enterica serovar Typhimurium, and Yersinia enterocolitica genomic DNA mixtures (ternary); or wastewater total DNA. Amplified products were fluorescently labeled and hybridized on the prototype chip. The detection sensitivity for S. enterica serovar Typhimurium was estimated to be on the order of 0.1% (10(4) S. enterica genomes) of the total DNA for the combination of PCR followed by microarray hybridization. The sensitivity of the prototype could be increased by hybridizing amplicons generated by PCR targeting genes specific for a bacterial subgroup, such as wecE genes, instead of universal taxonomic amplicons. However, there was evidence of PCR bias affecting the detection limits of a given pathogen as increasing amounts of a different pathogen were spiked into the test samples. These results demonstrate the feasibility of using DNA microarrays in the detection of waterborne pathogens within mixed populations but also raise the problem of PCR bias in such experiments. 相似文献
7.
Thermal depolymerization of alginate in the solid state 总被引:2,自引:0,他引:2
A new method of introduction carboxyl groups to chitosan sulfate by the acylation reaction between hydroxyethyl chitosan sulfates and butane dioic anhydride in homogeneous solution was used to obtain carboxybutyrylated hydroxyethyl chitosan sulfates. The structures of the derivatives were characterized by element analysis, FT-IR, 13C-NMR, and gel permeation chromatography. The content and position of the carboxyl groups could be controlled favorably. Their anticoagulant activity was determined for human plasma with respect to activated partial thromboplastin time (APTT), thrombin time (TT), and prothombin time (PT). The introducing of carboxyl groups to amino groups greatly prolonged the APTT and TT. The best result occurred when the degree of substitution of the carboxyl groups was about 0.4/unit that prolonged APTT and TT with about 5 and 1.5 times compared to that of the uncarboxylated hydroxyethyl chitosan sulfates; another conclusion is that introducing of carboxyl groups into N,O-position gave better results than that just into N-positions. Low S% chitosan sulfate and 6-O-desulfated chitosan sulfate showed little anticoagulant activity but their N,O-carboxybutyrylated derivatives (0.6/unit ds) showed increased APTT or TT, while their N-carboxybutyrylated derivatives (0.6/unit ds) gave no improvement. Generally, the introducing of carboxyl groups could not increase PT in spite of the position introduced. 相似文献
8.
Breckpot K Heirman C De Greef C van der Bruggen P Thielemans K 《Journal of immunology (Baltimore, Md. : 1950)》2004,172(4):2232-2237
Antigens encoded by MAGE genes are of particular interest for cancer immunotherapy because they are tumor specific and shared by tumors of different histological types. Several clinical trials are in progress with MAGE peptides, proteins, recombinant poxviruses, and dendritic cells (DC) pulsed with peptides or proteins. The use of gene-modified DC would offer the major advantage of a long-lasting expression of the transgene and a large array of antigenic peptides that fit into the different HLA molecules of the patient. In this study, we tested the ability of gene-modified DC to prime rare Ag-specific T cells, and we identified a new antigenic peptide of clinical interest. CD8(+) T lymphocytes from an individual without cancer were stimulated with monocyte-derived DC, which were infected with a second-generation lentiviral vector encoding MAGE-3. A CTL clone was isolated that recognized peptide EGDCAPEEK presented by HLA-Cw7 molecules, which are expressed by >40% of Caucasians. Interestingly, this new tumor-specific antigenic peptide corresponds to position 212-220 of MAGE-2, -3, -6, and -12. HLA-Cw7 tumor cell lines expressing one of these MAGE genes were lysed by the CTL, indicating that the peptide is efficiently processed in tumor cells and can therefore be used as target for antitumoral vaccination. The risk of tumor escape due to appearance of Ag-loss variants should be reduced by the fact that the peptide is encoded by several MAGE genes. 相似文献
9.
Delattre M Leidel S Wani K Baumer K Bamat J Schnabel H Feichtinger R Schnabel R Gönczy P 《Nature cell biology》2004,6(7):656-664
Centrosomes, the major microtubule-organizing centres (MTOCs) of animal cells, are comprised of a pair of centrioles surrounded by pericentriolar material (PCM). Early in the cell cycle, there is a single centrosome, which duplicates during S-phase to direct bipolar spindle assembly during mitosis. Although crucial for proper cell division, the mechanisms that govern centrosome duplication are not fully understood. Here, we identify the Caenorhabditis elegans gene sas-5 as essential for daughter-centriole formation. SAS-5 is a coiled-coil protein that localizes primarily to centrioles. Fluorescence recovery after photobleaching (FRAP) experiments with green fluorescent protein (GFP) fused to SAS-5 (GFP-SAS-5) demonstrated that the protein shuttles between centrioles and the cytoplasm throughout the cell cycle. Analysis of mutant alleles revealed that the presence of SAS-5 at centrioles is crucial for daughter-centriole formation and that ZYG-1, a kinase that is also essential for this process, controls the distribution of SAS-5 to centrioles. Furthermore, partial RNA-interference (RNAi)-mediated inactivation experiments suggest that both sas-5 and zyg-1 are dose-dependent regulators of centrosome duplication. 相似文献
10.
Silaghi A Piercecchi-Marti MD Grino M Leonetti G Alessi MC Clement K Dadoun F Dutour A 《Obesity (Silver Spring, Md.)》2008,16(11):2424-2430
Epicardial fat is a relatively neglected component of the heart and could be an important risk factor of cardiac disease. The objective of our study was to assess the relationship between epicardial adipose tissue (EAT) extent, fat distribution, and coronaropathy in a group of adult victims of accidental or suspicious sudden death. In 56 cadavers, we performed 34 measurements of EAT from five computerized photographs of the heart (anterior and posterior faces, and three ventricle transversal slices) and analyzed their relationship with anthropometric markers of adiposity (BMI, waist and leg circumference, thickness of abdominal and thigh subcutaneous adipose tissue (SAT)), with the presence and staging of coronary artery disease (CAD), and with markers of myocardial hypertrophy. Simple linear regressions showed that EAT measurements are highly intercorrelated (r from 0.4 to 0.6, P < 0.001), and correlate with age, waist circumference, and heart weight, and to a lesser extent, with BMI, abdominal SAT thickness, and leg SAT thickness. Multiple regression showed that age, waist circumference, and heart weight significantly and independently correlate with EAT (P < 0.0001). No other anthropometric measurement was found independently correlated with EAT. The EAT/myocardium ratios correlated positively with age and waist circumference. Anterior and posterior areas of EAT were found significantly increased in patients with CAD and correlated positively with CAD staging (P = 0.0034, r = 0.38). Anterior EAT surface was found positively associated with CAD (P = 0.01), independently of age and other adiposity measurements. Prospective studies are needed to assess the risk of occurrence/progression of CAD that relate to EAT excess. 相似文献