排序方式: 共有47条查询结果,搜索用时 187 毫秒
1.
Ajith?R?Vancha Suman?Govindaraju Kishore?VL?Parsa Madhuri?Jasti Maribel?González-García Rafael?P?BallesteroEmail author 《BMC biotechnology》2004,4(1):23
Background
Several cell lines and primary cultures benefit from the use of positively charged extracellular matrix proteins or polymers that enhance their ability to attach to culture plates. Polyethyleneimine is a positively charged polymer that has gained recent attention as a transfection reagent. A less known use of this cationic polymer as an attachment factor was explored with several cell lines. 相似文献2.
3.
Thibaud Souter Raphael Cornette Julio Pedraza John Hutchinson Michel Baylac 《Comptes Rendus Palevol》2010,9(6-7):411-422
Geometric morphometrics involves defining landmark points to generate a discrete representation of an object. This crucial step is strongly influenced by the biological question guiding the analysis, and even more when using curve and surface semi-landmarks methods, because these require to generate a template of reference. We exemplify these constraints using two datasets from projects with very different backgrounds. The Theropod Dataset is a functional morphometric analysis of different extinct and extant theropod pelves. The Shrew Dataset is a populational morphometric analysis of the white-toothed shrew with very small variations in skull shape. We propose a novel procedure to generate a regular template configuration, using polygonal modelling tools. This method allows us to control the template geometry and adapt its complexity to the morphological variation in the sample. More studies are necessary to assess the morphometric and statistical importance of template design in curve and surface analyses. 相似文献
4.
CA Kalva-Filho EZ Campos VL Andrade ASR Silva AM Zagatto MCS Lima M Papoti 《Biology of sport / Institute of Sport》2015,32(4):333-337
The aims of the present study were to investigate the relationship of aerobic and anaerobic parameters with 400 m performance, and establish which variable better explains long distance performance in swimming. Twenty-two swimmers (19.1±1.5 years, height 173.9±10.0 cm, body mass 71.2±10.2 kg; 76.6±5.3% of 400 m world record) underwent a lactate minimum test to determine lactate minimum speed (LMS) (i.e., aerobic capacity index). Moreover, the swimmers performed a 400 m maximal effort to determine mean speed (S400m), peak oxygen uptake () and total anaerobic contribution (CANA). The CANA was assumed as the sum of alactic and lactic contributions. Physiological parameters of 400 m were determined using the backward extrapolation technique ( and alactic contributions of CANA) and blood lactate concentration analysis (lactic anaerobic contributions of CANA). The Pearson correlation test and backward multiple regression analysis were used to verify the possible correlations between the physiological indices (predictor factors) and S400m (independent variable) (p < 0.05). Values are presented as mean ± standard deviation. Significant correlations were observed between S400m (1.4±0.1 m·s-1) and LMS (1.3±0.1 m·s-1; r = 0.80), (4.5±3.9 L·min-1; r = 0.72) and CANA (4.7±1.5 L·O2; r= 0.44). The best model constructed using multiple regression analysis demonstrated that LMS and explained 85% of the 400 m performance variance. When backward multiple regression analysis was performed, CANA lost significance. Thus, the results demonstrated that both aerobic parameters (capacity and power) can be used to predict 400 m swimming performance. 相似文献
5.
Konrad Zych Yang Li Joeri K van der Velde Ronny VL Joosen Wilco Ligterink Ritsert C Jansen Danny Arends 《BMC bioinformatics》2015,16(1)
Background
Genetic markers and maps are instrumental in quantitative trait locus (QTL) mapping in segregating populations. The resolution of QTL localization depends on the number of informative recombinations in the population and how well they are tagged by markers. Larger populations and denser marker maps are better for detecting and locating QTLs. Marker maps that are initially too sparse can be saturated or derived de novo from high-throughput omics data, (e.g. gene expression, protein or metabolite abundance). If these molecular phenotypes are affected by genetic variation due to a major QTL they will show a clear multimodal distribution. Using this information, phenotypes can be converted into genetic markers.Results
The Pheno2Geno tool uses mixture modeling to select phenotypes and transform them into genetic markers suitable for construction and/or saturation of a genetic map. Pheno2Geno excludes candidate genetic markers that show evidence for multiple possibly epistatically interacting QTL and/or interaction with the environment, in order to provide a set of robust markers for follow-up QTL mapping.We demonstrate the use of Pheno2Geno on gene expression data of 370,000 probes in 148 A. thaliana recombinant inbred lines. Pheno2Geno is able to saturate the existing genetic map, decreasing the average distance between markers from 7.1 cM to 0.89 cM, close to the theoretical limit of 0.68 cM (with 148 individuals we expect a recombination every 100/148=0.68 cM); this pinpointed almost all of the informative recombinations in the population.Conclusion
The Pheno2Geno package makes use of genome-wide molecular profiling and provides a tool for high-throughput de novo map construction and saturation of existing genetic maps. Processing of the showcase dataset takes less than 30 minutes on an average desktop PC. Pheno2Geno improves QTL mapping results at no additional laboratory cost and with minimum computational effort. Its results are formatted for direct use in R/qtl, the leading R package for QTL studies. Pheno2Geno is freely available on CRAN under “GNU GPL v3”. The Pheno2Geno package as well as the tutorial can also be found at: http://pheno2geno.nl.Electronic supplementary material
The online version of this article (doi:10.1186/s12859-015-0475-6) contains supplementary material, which is available to authorized users. 相似文献6.
7.
Johnston SL Grune T Bell LM Murray SJ Souter DM Erwin SS Yearsley JM Gordon IJ Illius AW Kyriazakis I Speakman JR 《Proceedings. Biological sciences / The Royal Society》2006,273(1592):1369-1374
An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot "have it all"--combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the "trade-off" and "having it all" theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from -21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans. 相似文献
8.
The hair cells of the auditory and balance systems of the inner ear have precise structures and orientations related to function. Hair cells differentiate from a homogenous cell population with the initiation of afferent synaptogenesis and appearance of the apical hair bundle being the first definitive structural sign of hair cell development. The cytoskeletal network then develops and the intercellular membrane junctions become more complex. As auditory function is established in mammalian cochlear hair cells, the lateral membrane acquires certain specializations. Accompanying this there is a change from afferent to efferent innervation of outer hair cells. 相似文献
9.
B. M. Degnan Duncan Souter Sandie M. Degnan Suzanne C. Long 《Development genes and evolution》1997,206(6):370-376
Increased K+ concentration in seawater induces metamorphosis in the ascidian Herdmania
momus. Larvae cultivated at 24°C exhibit highest rates of metamorphosis when treated with 40 mM KCl-elevated seawater at 21°C. At 24°C, H. momus larvae develop competence to respond to KCl-seawater and initiate metamorphosis approximately 3 h after hatching. Larval trunks
and tails separated from the anterior papillae region, but maintained in a common tunic at a distance of greater than 60 μm,
do not undergo metamorphosis when treated with KCl-seawater; normal muscle degradation does not occur in separated tails while
ampullae develop from papillae-containing anterior fragments. Normal programmed degradation of myofibrils occurs when posterior
fragments are fused to papillae-containing anterior fragments. These data indicate that H. momus settlement and metamorphosis only occurs when larvae have attained competence, and suggest that an anterior signalling centre
is stimulated to release a factor that induces metamorphosis.
Received: 15 May 1996 / Accepted: 19 September 1996 相似文献
10.