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991.
Nehemías Leija-Martínez Sergio Casas-Flores Rubén D. Cadena-Nava Joan A. Roca José A. Mendez-Caba?as Eduardo Gomez Jaime Ruiz-Garcia 《Nucleic acids research》2014,42(22):13963-13968
RNA molecules play different roles in coding, decoding and gene expression regulation. Such roles are often associated to the RNA secondary or tertiary structures. The folding dynamics lead to multiple secondary structures of long RNA molecules, since an RNA molecule might fold into multiple distinct native states. Despite an ensemble of different structures, it has been theoretically proposed that the separation between the 5′ and 3′ ends of long single-stranded RNA molecules (ssRNA) remains constant, independent of their base content and length. Here, we present the first experimental measurements of the end-to-end separation in long ssRNA molecules. To determine this separation, we use single molecule Fluorescence Resonance Energy Transfer of fluorescently end-labeled ssRNA molecules ranging from 500 to 5500 nucleotides in length, obtained from two viruses and a fungus. We found that the end-to-end separation is indeed short, within 5–9 nm. It is remarkable that the separation of the ends of all RNA molecules studied remains small and similar, despite the origin, length and differences in their secondary structure. This implies that the ssRNA molecules are ‘effectively circularized’ something that might be a general feature of RNAs, and could result in fine-tuning for translation and gene expression regulation. 相似文献
992.
Nicole E. Soltis Sara Gomez Gary G. Leisk Patrick Sherwood Evan L. Preisser Pierluigi Bonello Colin M. Orians 《Annals of botany》2014,113(4):721-730
Background and Aims
Exotic herbivores that lack a coevolutionary history with their host plants can benefit from poorly adapted host defences, potentially leading to rapid population growth of the herbivore and severe damage to its plant hosts. The hemlock woolly adelgid (Adelges tsugae) is an exotic hemipteran that feeds on the long-lived conifer eastern hemlock (Tsuga canadensis), causing rapid mortality of infested trees. While the mechanism of this mortality is unknown, evidence indicates that A. tsugae feeding causes a hypersensitive response and alters wood anatomy. This study investigated the effect of A. tsugae feeding on biomechanical properties at different spatial scales: needles, twigs and branches.Methods
Uninfested and A. tsugae-infested samples were collected from a common garden experiment as well as from naturally infested urban and rural field sites. Tension and flexure mechanical tests were used to quantify biomechanical properties of the different tissues. In tissues that showed a significant effect of herbivory, the potential contributions of lignin and tissue density on the results were quantified.Key Results Adelges tsugae
infestation decreased the abscission strength, but not flexibility, of needles. A. tsugae feeding also decreased mechanical strength and flexibility in currently attacked twigs, but this effect disappeared in older, previously attacked branches. Lignin and twig tissue density contributed to differences in mechanical strength but were not affected by insect treatment.Conclusions
Decreased strength and flexibility in twigs, along with decreased needle strength, suggest that infested trees experience resource stress. Altered growth patterns and cell wall chemistry probably contribute to these mechanical effects. Consistent site effects emphasize the role of environmental variation in mechanical traits. The mechanical changes measured here may increase susceptibility to abiotic physical stressors in hemlocks colonized by A. tsugae. Thus, the interaction between herbivore and physical stresses is probably accelerating the decline of eastern hemlock, as HWA continues to expand its range. 相似文献993.
Ines Sanchez-Roman Alexia Gomez Alba Naudí Mariona Jove Jose Gómez Mónica Lopez-Torres Reinald Pamplona Gustavo Barja 《Journal of bioenergetics and biomembranes》2014,46(3):159-172
A low rate of mitochondrial ROS production (mitROSp) and a low degree of fatty acid unsaturation are characteristic traits of long-lived animals and can be obtained in a single species by methionine restriction (MetR) or atenolol (AT) treatments. However, simultaneous application of both treatments has never been performed. In the present investigation it is shown that MetR lowers mitROSp and complex I content. Both the MetR and the AT treatments lower protein oxidative modification and oxidative damage to mtDNA and the fatty acid unsaturation degree in rat heart mitochondria. The decrease in fatty acid unsaturation seems to be due, at least in part, to decreases in desaturase and elongase activities or peroxisomal β-oxidation. Furthermore, the phosphorylation of extracellular signal-regulated kinase (ERK) was stimulated by MetR and AT. The decrease in membrane fatty acid unsaturation and protein oxidation, and the changes in fatty acids and p-ERK showed additive effects of both treatments. In addition, the increase in mitROSp induced by AT observed in the present investigation was totally avoided with the combined MetR + AT treatment. It is concluded that the simultaneous treatment with MetR plus atenolol is more beneficial than either single treatment alone to lower oxidative stress in rat heart mitochondria, analogously to what has been reported in long-lived animal species. 相似文献
994.
Juan Arturo Gomez Barroso Carlos Fernando Aguilar 《European biophysics journal : EBJ》2014,43(8-9):361-366
Ribosomal P proteins form a “stalk” complex in the large subunit of the ribosomes. In Trypanosoma cruzi, the etiological agent of Chagas disease, the complex is formed by five P protein members: TcP0, TcP1α, TcP1β, TcP2α and TcP2β. The TcP0 protein has 34 kDa, and TcP1 and TcP2 proteins have 10 kDa. The structure of T. cruzi P0 and the stalk complex TcP0–TcP1α–TcP1β–TcP2α–TcP2β have not been solved to date. In this work, we constructed a three-dimensional molecular model for TcP0 using homology modeling as implemented in the MODELLER 9v12 software. The model was constructed using different templates: the X-ray structures of the protein P0 from Pirococcus horikoshii, a segment from the Danio renio Ca+2/K+ channel and the C-terminal peptide (C13) from T. cruzi ribosomal P2 protein; the Cryo-EM structure of Triticum aestivum P0 protein and the NMR structure of Homo sapiens P1 ribosomal protein. TcP0 has a 200-residue-long N-terminal, which is an α/β globular stable domain, and a flexible C-terminal, 120-residue-long domain. The molecular surface electrostatic potential and hydrophobic surface were calculated. The surface properties are important for the C-terminal's antigenic properties. They are also responsible for P0-specific binding to RNA26S and the binding to the P1–P2 proteins. We explored and identified protein interactions that may be involved in conformational stability. The structure proposed in this work represents a first structural report for the TcP0 protein. 相似文献
995.
996.
997.
998.
Eduardo Vilar Gomez Ana Torres Gonzalez Luis Calzadilla Bertot Ali Yasells Garcia Yoan Sanchez Rodriguez Yadina Martinez Perez 《PloS one》2014,9(4)
Background
Arterial blood pressure (BP) is a reliable marker of circulatory dysfunction in cirrhotic patients. There are no prospective studies evaluating the association between different levels of arterial BP and ascites development in compensated cirrhotic patients. Therefore, we evaluated the relationship between arterial BP and ascites development in compensated cirrhotic patients.Materials and Methods
A total of 402 patients with compensated HCV-related cirrhosis were prospectively followed during 6 years to identify ascites development. At baseline, patients underwent systolic, diastolic and mean arterial pressure (MAP) measurements. Any history of arterial hypertension was also recorded. The occurrence of events such as bleeding, hepatocellular carcinoma, death and liver transplantation prior to ascites development were considered as competing risk events.Results
Over a median of 156 weeks, ascites occurred in 54 patients (13%). At baseline, MAP was significantly lower in patients with ascites development (75.9 mm/Hg [95%CI, 70.3–84.3]) than those without ascites (93.6 mm/Hg [95% CI: 86.6–102.3]). After adjusting for covariates, the 6-year cumulative incidence of ascites was 40% (95%CI, 34%–48%) for patients with MAP<83.32 mm/Hg. In contrast, cumulative incidences of ascites were almost similar among patients with MAP values between 83.32 mm/Hg and 93.32 mm/Hg (7% [95% CI: 4%–12%]), between 93.32 mm/Hg and 100.31 mm/Hg (5% [95% CI: 4%–11%]) or higher than 100.31 mm/Hg (3% [95% CI: 1%–6%]). The MAP was an independent predictor of ascites development.Conclusions
The MAP is closely related to the development of ascites in compensated HCV-related cirrhosis. The risk of ascites development increases in 4.4 fold for subjects with MAP values <83.32 mm/Hg. 相似文献999.
This paper presents methods for the determination of players'' positions and contact time points by tracking the players and the ball in beach volleyball videos. Two player tracking methods are compared, a classical particle filter and a rigid grid integral histogram tracker. Due to mutual occlusion of the players and the camera perspective, results are best for the front players, with 74,6% and 82,6% of correctly tracked frames for the particle method and the integral histogram method, respectively. Results suggest an improved robustness against player confusion between different particle sets when tracking with a rigid grid approach. Faster processing and less player confusions make this method superior to the classical particle filter. Two different ball tracking methods are used that detect ball candidates from movement difference images using a background subtraction algorithm. Ball trajectories are estimated and interpolated from parabolic flight equations. The tracking accuracy of the ball is 54,2% for the trajectory growth method and 42,1% for the Hough line detection method. Tracking results of over 90% from the literature could not be confirmed. Ball contact frames were estimated from parabolic trajectory intersection, resulting in 48,9% of correctly estimated ball contact points. 相似文献
1000.
Olga Lucía Fernández Yira Diaz-Toro Clemencia Ovalle Liliana Valderrama Sandra Muvdi Isabel Rodríguez María Adelaida Gomez Nancy Gore Saravia 《PLoS neglected tropical diseases》2014,8(5)