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991.
van Schie CC Ament K Schmidt A Lange T Haring MA Schuurink RC 《The Plant journal : for cell and molecular biology》2007,52(4):752-762
Geranyl diphosphate synthase (GPS) is generally considered to be responsible for the biosynthesis of monoterpene precursors only. However, reduction of LeGPS expression in tomato (Lycopersicon esculentum) by virus-induced gene silencing resulted in severely dwarfed plants. Further analysis of these dwarfed plants revealed a decreased gibberellin content, whereas carotenoid and chlorophyll levels were unaltered. Accordingly, the phenotype could be rescued by application of gibberellic acid. The dwarfed phenotype was also obtained in Arabidopsis thaliana plants transformed with RNAi constructs of AtGPS. These results link geranyl diphosphate (GPP) to the gibberellin biosynthesis pathway. They also demand a re-evaluation of the role of GPS in precursor synthesis for other di-, tri-, tetra- and/or polyterpenes and their derivatives. 相似文献
992.
Cécile Vanpé Lucie Debeffe Maxime Galan A. J. Mark Hewison Jean‐Michel Gaillard Emmanuelle Gilot‐Fromont Nicolas Morellet Hélène Verheyden Jean‐François Cosson Bruno Cargnelutti Joël Merlet Erwan Quéméré 《Oikos》2016,125(12):1790-1801
Dispersal is a key life‐history trait governing the response of individuals, populations and species to changing environmental conditions. In the context of global change, it is therefore essential to better understand the respective role of condition‐, phenotype‐ and genetic‐dependent drivers of dispersal behaviour. Although the importance of immune function and pathogen infestation in determining patterns of dispersal is increasingly recognised, no study to our knowledge has yet investigated the influence of immune gene variability on dispersal behaviour. Here, we filled this knowledge gap by assessing whether individual heterozygosity at five immune gene loci (one from the Major histocompatibility complex and four from encoding Toll‐like receptors) influences roe deer natal dispersal. We found that dispersal propensity was affected by immune gene diversity, suggesting potential pathogen‐mediated selection through over‐dominance. However, the direction of this effect differed between high and low quality individuals, suggesting that dispersal propensity is driven by two different mechanisms. In support of the condition‐dependent dispersal hypothesis, dispersal propensity increased with increasing body mass and, among high quality individuals only (standardized body mass > 18 kg), with increasing immune gene diversity. However, among poor quality individuals, we observed the opposite pattern such that dispersal propensity was higher for individuals with lower immune gene diversity. We suggest that these poor quality individuals expressed an emergency dispersal tactic in an attempt to escape a heavily infested environment associated with poor fitness prospects. Our results have potentially important consequences in terms of population genetics and demography, as well as host–pathogen evolution. 相似文献
993.
Patrick Cordier Michel Mendès France Philippe Bolon Jean Pailhous 《Acta biotheoretica》1994,42(2-3):187-201
Our work is aimed at studying the optimization of a complex motor behaviour from a global perspective. First, free climbing as a sport will be briefly introduced while emphasizing in particular its psychomotor aspect called route finding. The basic question raised here is how does the optimization of a sensorimotoricity-environment system take place. The material under study is the free climber's trajectory, viewed as the signature of climbing behaviour (i.e., the spatial dimension). The concepts of learning, optimization, constraint, and degrees of freedom of a system will be discussed using the synergistic approach to the study of movement (Bernstein, 1967; Kelso, 1977). Measures of a trajectory's length and convex hull can be used to define an index whose equation resembles that of an entropy. This index is a measure of the trajectory's overall complexity. Some important concepts related to the thermodynamics of curves will also be discussed. The optimization process will be studied by examining the changes in entropy over time for a set of trajectories generated during the learning of a route (ten successive repetitions of the same climb). It will be shown that the entropy of the trajectories decreases as learning progresses, that each level of expertise has its own characteristic entropy curve, and that for the subjects tested, the mean entropy of skilled climbers is lower than that of average climbers. Basing our analysis on the concepts of degrees of freedom and constraint equations, an attempt is made to relate trajectory entropy to system entropy. Based on the postulate that trajectory entropy is equal to the difference in entropy between the unconstrained and constrained system, a model of motor optimization is proposed. This model is illustrated by an entropy graph reflecting a dynamic release process. In the light of our results, two opposing views will be examined: movement construction vs. movement emergence. 相似文献
994.
Diane Julien-David Saïd Ennahar Michel Miesch Philippe Geoffroy Francis Raul Dalal Aoude-Werner Jean-Marc Lessinger Eric Marchioni 《Steroids》2009,74(10-11):832-836
Phytosteryl esters (PE) are used as ingredients in functional food to decrease plasma concentration of low density lipoprotein-cholesterol (LDL-C). Effective impairment of cholesterol absorption by PE suggests that these esters are hydrolyzed by the pancreatic cholesterol esterase (CEase, EC 3.1.1.13) and the liberated sterol may interfere with cholesterol reducing its intestinal absorption. PE-enriched foods are marketed for cooking purposes, and temperature is one of the most important factors leading to the formation of oxidation products. Very little is known about the outcome of PE oxides during the digestive process. A new analytical method based on mass spectrometric detection directly after enzymatic reaction was developed to determine in vitro the activity of CEase on PE and their oxides present in functional food. Using this method, we identified a new inhibitor of CEase: sitosteryl 9,10-dihydroxystearate, which behaves as a non-competitive inhibitor of the hydrolysis of cholesteryl oleate and sitosteryl oleate. 相似文献
995.
Damien Sanlaville Capucine Delnatte Jean-Franois Mougenot Joris-Robert Vermeesch Claude Houdayer Marie-Christine de
Blois David Genevieve Olivier Goulet Jean-Pierre Fryns Francis Jaubert Michel Vekemans Stanislas Lyonnet Serge Romana Charis Eng Dominique Stoppa-Lyonnet 《American journal of human genetics》2006,79(3):596-597
996.
Julio Sáez-Vásquez Monique Raynal Luis Meza-Basso Michel Delseny 《Plant molecular biology》1993,23(6):1211-1221
In order to identify genes involved in cold acclimation, we have constructed a cDNA library from Brassica napus (cv. Samouraï) cold-acclimated etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible plant gene, was isolated. Northern blot hybridizations using total RNA from acclimated and unacclimated seedlings confirmed that BnC24 represents a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (ABA). In addition, further screening of the cold-acclimated cDNA library using pBnC24 cDNA as a probe, allowed the isolation of a second type of homologous cDNA. Sequence analysis showed that the two BnC24 genes encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino acid sequences of these clones do not show any homology with other previously described cold-induced plants genes. However they have strong homology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes. 相似文献
997.
Franck Desmoulin Michel Galinier Charlotte Trouillet Matthieu Berry Clément Delmas Annie Turkieh Pierre Massabuau Heinrich Taegtmeyer Fatima Smih Philippe Rouet 《PloS one》2013,8(4)
Objective
Mortality in heart failure (AHF) remains high, especially during the first days of hospitalization. New prognostic biomarkers may help to optimize treatment. The aim of the study was to determine metabolites that have a high prognostic value.Methods
We conducted a prospective study on a training cohort of AHF patients (n = 126) admitted in the cardiac intensive care unit and assessed survival at 30 days. Venous plasmas collected at admission were used for 1H NMR – based metabonomics analysis. Differences between plasma metabolite profiles allow determination of discriminating metabolites. A cohort of AHF patients was subsequently constituted (n = 74) to validate the findings.Results
Lactate and cholesterol were the major discriminating metabolites predicting 30-day mortality. Mortality was increased in patients with high lactate and low total cholesterol concentrations at admission. Accuracies of lactate, cholesterol concentration and lactate to cholesterol (Lact/Chol) ratio to predict 30-day mortality were evaluated using ROC analysis. The Lact/Chol ratio provided the best accuracy with an AUC of 0.82 (P < 0.0001). The acute physiology and chronic health evaluation (APACHE) II scoring system provided an AUC of 0.76 for predicting 30-day mortality. APACHE II score, Cardiogenic shock (CS) state and Lact/Chol ratio ≥ 0.4 (cutoff value with 82% sensitivity and 64% specificity) were significant independent predictors of 30-day mortality with hazard ratios (HR) of 1.11, 4.77 and 3.59, respectively. In CS patients, the HR of 30-day mortality risk for plasma Lact/Chol ratio ≥ 0.4 was 3.26 compared to a Lact/Chol ratio of < 0.4 (P = 0.018). The predictive power of the Lact/Chol ratio for 30-day mortality outcome was confirmed with the independent validation cohort.Conclusion
This study identifies the plasma Lact/Chol ratio as a useful objective and simple parameter to evaluate short term prognostic and could be integrated into quantitative guidance for decision making in heart failure care. 相似文献998.
Hunte C Koepke J Lange C Rossmanith T Michel H 《Structure (London, England : 1993)》2000,8(6):669-684
BACKGROUND: The cytochrome bc(1) complex is part of the energy conversion machinery of the respiratory and photosynthetic electron transfer chains. This integral membrane protein complex catalyzes electron transfer from ubiquinol to cytochrome c. It couples the electron transfer to the electrogenic translocation of protons across the membrane via a so-called Q cycle mechanism. RESULTS: The cytochrome bc(1) complex from the yeast Saccharomyces cerevisiae was crystallized together with a bound antibody Fv fragment. The structure was determined at 2.3 A resolution using multiple isomorphous replacement, and refined to a crystallographic R factor of 22.2% (R(free) = 25.4%). The complex is present as a homodimer. Each 'monomer' of the refined model includes 2178 amino acid residues of subunits COR1, QCR2, COB, CYT1, RIP1, QCR6, QCR7, QCR8 and QCR9 of the cytochrome bc(1) complex and of the polypeptides V(H) and V(L) of the Fv fragment, the cofactors heme b(H), heme b(L), heme c(1), the [2Fe-2S] cluster and 346 water molecules. The Fv fragment binds to the extrinsic domain of the [2Fe-2S] Rieske protein and is essential for formation of the crystal lattice. CONCLUSIONS: The approach to crystallize membrane proteins as complexes with specific antibody fragments appears to be of general importance. The structure of the yeast cytochrome bc(1) complex reveals in detail the binding sites of the natural substrate coenzyme Q6 and the inhibitor stigmatellin. Buried water molecules close to the binding sites suggest possible pathways for proton uptake and release. A comparison with other cytochrome bc(1) complexes shows features that are specific to yeast. 相似文献
999.
In the radioreceptor assay for growth hormone (RRA-GH) using [125I]iodo-hGH, hGH and human liver membrane particulate fractions as tracer, hormone standard and receptors, respectively, ovine placental lactogen (oPL) is capable of inhibiting the binding of [125I]iodo-hGH in a parallel manner with hGH and in equipotency. Similarly, in the RRA-GH by employing [125I]iodo-oPL, oPL and human liver membrane particulate fractions as tracer, hormone standard and receptors, respectively, hGH is also equipotent as oPL in inhibiting the binding of [125I]iodo-oPL in a parallel fashion. The addition of monoclonal antibodies against oPL in the assay was effective in inhibiting the binding of [125I] iodo-oPL to human liver, but could not, however, inhibit the binding of [125I]iodo-hGH to human liver. Furthermore, the addition of the monoclonal antibodies in the RRA-GH did not affect the parallelism of the oPL standard but lowered the total binding of oPL. Our studies indicate that the structure of the binding sequence in oPL which binds to the GH receptor of human liver is not identical to the equivalent sequence of hGH and that the monoclonal antibodies compete with GH receptors in human liver for the binding of oPL. 相似文献
1000.