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81.
van Oijen AM 《Biopolymers》2007,85(2):144-153
The replication, recombination, and repair of DNA are processes essential for the maintenance of genomic information and require the activity of numerous enzymes that catalyze the polymerization or digestion of DNA. This review will discuss how differences in elastic properties between single- and double-stranded DNA can be used as a probe to study the dynamics of these enzymes at the single-molecule level. 相似文献
82.
Caenorhabditis elegans is a major laboratory model system yet a newcomer to the field of population genetics, and relatively little is known of its biology in the wild. Recent studies of natural populations at a single time point revealed strong spatial population structure and suggested that these populations may be very dynamic. We have therefore studied several natural C. elegans populations over time and genotyped them at polymorphic microsatellite loci. While some populations appear to be genetically stable over the course of observation, others seem to go extinct, with full replacement of multilocus genotypes upon regrowth. The frequency of heterozygotes indicates that outcrossing occurs at a mean frequency of 1.7% and is variable between populations. However, in genetically stable populations, linkage disequilibrium between different chromosomes can be maintained over several years at a level much higher than expected from the heterozygote frequency. C. elegans seems to follow metapopulation dynamics, and the maintenance of linkage disequilibrium despite a low yet significant level of outcrossing suggests that selection may act against the progeny of outcrossings. 相似文献
83.
Tordjman J Leroyer S Chauvet G Quette J Chauvet C Tomkiewicz C Chapron C Barouki R Forest C Aggerbeck M Antoine B 《The Journal of biological chemistry》2007,282(32):23591-23602
84.
Sourisseau M Schilte C Casartelli N Trouillet C Guivel-Benhassine F Rudnicka D Sol-Foulon N Le Roux K Prevost MC Fsihi H Frenkiel MP Blanchet F Afonso PV Ceccaldi PE Ozden S Gessain A Schuffenecker I Verhasselt B Zamborlini A Saïb A Rey FA Arenzana-Seisdedos F Desprès P Michault A Albert ML Schwartz O 《PLoS pathogens》2007,3(6):e89
An unprecedented epidemic of chikungunya virus (CHIKV) infection recently started in countries of the Indian Ocean area, causing an acute and painful syndrome with strong fever, asthenia, skin rash, polyarthritis, and lethal cases of encephalitis. The basis for chikungunya disease and the tropism of CHIKV remain unknown. Here, we describe the replication characteristics of recent clinical CHIKV strains. Human epithelial and endothelial cells, primary fibroblasts and, to a lesser extent, monocyte-derived macrophages, were susceptible to infection and allowed viral production. In contrast, CHIKV did not replicate in lymphoid and monocytoid cell lines, primary lymphocytes and monocytes, or monocyte-derived dendritic cells. CHIKV replication was cytopathic and associated with an induction of apoptosis in infected cells. Chloroquine, bafilomycin-A1, and short hairpin RNAs against dynamin-2 inhibited viral production, indicating that viral entry occurs through pH-dependent endocytosis. CHIKV was highly sensitive to the antiviral activity of type I and II interferons. These results provide a general insight into the interaction between CHIKV and its mammalian host. 相似文献
85.
Assessing whether trait variations among individuals are consistent over time and among environmental conditions is crucial to understand evolutionary responses to new selective pressures such as climate change. According to the universal thermal dependence hypothesis, thermal sensitivity of metabolic rate should not vary strongly and consistently among organisms, implying limited evolutionary response for metabolic traits under climate change. However, this hypothesis has been rarely tested at an individual level, leaving a gap in our understanding of climate change impacts on metabolic responses and their potential evolution. Using the amphipod Gammarus fossarum, we investigated the variability and repeatability of individual metabolic thermal reaction norms over time. We found large variations in both the thermal sensitivity (i.e. slope) and expression level (i.e. intercept) of individual metabolic reaction norms. Moreover, differences among individuals were consistent over time, and therefore repeatable. Inter‐individual variations in body mass resulted in a high repeatability of metabolic expression level but had no significant effect on the repeatability of thermal sensitivity. Overall, our results highlight that inter‐individual variability and repeatability of thermal reaction norms can be substantial. We conclude that these consistent differences among individuals should not be overlooked when apprehending the ecological and evolutionary effects of climate change. 相似文献
86.
Tomas Urbina Jean-Rmi Lavillegrand Marc Garnier Arsene Mekinian Jerome Pacanowski Nathalie Mario Guillaume Dumas Geoffroy Hariri Antoine Pilon Lucie Darrivre Muriel Fartoukh Bertrand Guidet Eric Maury Judith Leblanc Yannick Chantran Olivier Fain Karine Lacombe Guillaume Voiriot Hafid Ait-Oufella 《Innate immunity》2022,28(1):3
Little is known about the immuno-inflammatory response to Tocilizumab and its association with outcome in critically-ill SARS-CoV2 pneumonia. In this multicenter retrospective cohort of SARS-CoV-2 patients admitted to three intensive care units between March and April 2020, we matched on gender and SAPS II 21 Tocilizumab-treated patients to 42 non-treated patients. Need for mechanical ventilation was 76% versus 79%. IL-6, C-reactive protein, and fibrinogen had been collected within the first days of admission (T1), 3 d (T2) and 7 d (T3) later. Tocilizumab-treated patients had persistently higher IL-6 plasma levels and persistently lower C-Reactive protein and fibrinogen levels. Among Tocilizumab-treated patients, baseline levels of inflammatory biomarkers were not different according to outcome. Conversely, C-reactive protein and fibrinogen decrease was delayed in non-survivors. C-Reactive protein decreased at T1 in survivors (45 [30–98] vs 170 [69–204] mg/l, P < 0.001) but only at T2 in non-survivors (37 [13–74] vs 277 [235–288], P = 0.03). Fibrinogen decreased at T2 in survivors (4.11 [3.58–4.69] vs 614 [5.61–7.85] g/l, P = 0.005) but not in non-survivors (4.79 [4.12–7.58] vs 7.24 [6.22–9.24] g/l, P = 0.125). Tocilizumab treatment was thus associated with a persistent both increase in plasma IL-6, and decrease in C-reactive protein and fibrinogen. Among Tocilizumab-treated patients, the decrease in inflammatory biomarkers was delayed in non-survivors. 相似文献
87.
88.
Anja T. Rovio Josef Abel Arja L. Ahola Aida M. Andres Jaume Bertranpetit Antoine Blancher Ronald E. Bontrop Leona G. Chemnick Howard J. Cooke James M. Cummins Heidi A. Davis David J. Elliott Ellen Fritsche Timothy B. Hargreave Susan M. G. Hoffman Anne M. Jequier Shu-Huei Kao Heui-Soo Kim David R. Marchington Denise Mehmet Nel Otting Joanna Poulton Oliver A. Ryder Hans-Christian Schuppe Osamu Takenaka Yau-Huei Wei Lars Wichmann Howard T. Jacobs 《Mammalian genome》2004,15(6):492-502
The human nuclear gene for the catalytic subunit of mitochondrial DNA polymerase (POLG) contains within its coding region a CAG microsatellite encoding a polyglutamine repeat. Previous studies demonstrated an association between length variation at this repeat and male infertility, suggesting a mechanism whereby the prevalent (CAG)10 allele, which occurs at a frequency of >80% in different populations, could be maintained by selection. Sequence analysis of the POLG CAG microsatellite region of more than 1000 human chromosomes reveals that virtually all allelic variation at the locus is accounted for by length variation of the CAG repeat. Analysis of POLG from African great apes shows that a prevalent length allele is present in each species, although its exact length is species-specific. In common chimpanzee (Pan troglodytes) a number of different sequence variants contribute to the prevalent length allele, strongly supporting the idea that the length of the POLG microsatellite region, rather than its exact nucleotide or amino acid sequence, is what is maintained. Analysis of POLG in other primates indicates that the repeat has expanded from a shorter, glutamine-rich sequence, present in the common ancestor of Old and New World monkeys. 相似文献
89.
An approach to automatic prediction of the amino acid type from NMR chemical shift values of its nuclei is presented here, in the frame of a model to calculate the probability of an amino acid type given the set of chemical shifts. The method relies on systematic use of all chemical shift values contained in the BioMagResBank (BMRB). Two programs were designed, one (BMRB stats) for extracting statistical chemical shift parameters from the BMRB and another one (RESCUE2) for computing the probabilities of each amino acid type, given a set of chemical shifts. The Bayesian prediction scheme presented here is compared to other methods already proposed: PROTYP RESCUE and PLATON and is found to be more sensitive and more specific. Using this scheme, we tested various sets of nuclei. The two nuclei carrying the most information are C(beta) and H(beta), in agreement with observations made in Grzesiek and Bax, 1993. Based on four nuclei: H(beta), C(beta), C(alpha) and C', it is possible to increase correct predictions to a rate of more than 75%. Taking into account the correlations between the nuclei chemical shifts has only a slight impact on the percentage of correct predictions: indeed, the largest correlation coefficients display similar features on all amino acids. 相似文献
90.
Géraldine?Verquin Ga?lle?Fontaine Marc?Bria Elena?Zhilinskaya Edmond?Abi-Aad Antoine?Abouka?s Brigitte?Baldeyrou Christian?Bailly Jean-Luc?BernierEmail author 《Journal of biological inorganic chemistry》2004,9(3):345-353
Oxovanadium(IV) complexes of hydroxysalen derivatives have been prepared and tested as DNA reactive agents. The nuclease activity has been investigated under oxidative or reducing conditions, on the basis of the various oxidation states of vanadium: VIII, VIV and VV. In the absence of an activating agent, none of the compounds tested was able to induce cleavage of DNA, whereas in the presence of mercaptopropionic acid (MPA) or Oxone the four complexes induced DNA modifications. Under both conditions, the para-hydroxy complex was found to be the most active compound. Reaction of these salen complexes with DNA occurs essentially at guanine residues and is more efficient in the presence of Oxone than under reducing conditions. The extent of Oxone-mediated DNA oxidation by the four vanadyl complexes was clearly superior to VOSO4
and was observed without piperidine treatment. EPR studies provided information on the reactive metal-oxo species involved under each conditions and a mechanism of reaction with DNA is discussed.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00775-004-0529-0Abbreviations BPE buffer
bis-phosphate EDTA buffer
- DMPO
5,5-dimethylpyrroline
N-oxide
- DMS
dimethyl sulfate
- HFS
hyperfine structure
- Lin
linear
- MPA
3-mercaptopropionic acid
- Nck
nicked
- salen
(salicylidene)ethylenediamine
- Sc
supercoiled
- TBE buffer
tris-borate EDTA buffer
- Tris
tris(hydroxymethyl)aminomethane 相似文献