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81.
In the nucleus of eukaryotic cells, histone proteins organize the linear genome into a functional and hierarchical architecture. In this paper, we use the crystal structures of the nucleosome core particle, B-DNA and the globular domain of H5 linker histone to build the first all-atom model of compact chromatin fibers. In this 3D jigsaw puzzle, DNA bending is achieved by solving an inverse kinematics problem. Our model is based on recent electron microscopy measurements of reconstituted fiber dimensions. Strikingly, we find that the chromatin fiber containing linker histones is a polymorphic structure. We show that different fiber conformations are obtained by tuning the linker histone orientation at the nucleosomes entry/exit according to the nucleosomal repeat length. We propose that the observed in vivo quantization of nucleosomal repeat length could reflect nature's ability to use the DNA molecule's helical geometry in order to give chromatin versatile topological and mechanical properties. 相似文献
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Various approaches have been developed to define conservation units for plant and animal species. In this study we combined
nuclear microsatellites (from a previous published study) and chloroplast microsatellites (assessed in the present study),
leaf and seed morphology traits and abiotic variables (climate and soil) to define evolutionary significant units (ESU) of
Santalum austrocaledonicum, a tree species growing in New Caledonia. Results for chloroplast microsatellites showed that the total population heterozygosity
was␣high, (H
cp = 0.84) but varied between islands. Differentiation was strong in the total population (F
stcp = 0.66) but also within the main island Grande Terre (F
stcp = 0.73) and within Iles Loyauté (F
stcp = 0.52), highlighting a limited gene flow between populations. These results confirmed those obtained with nuclear microsatellites.
The cluster analysis on molecular markers discriminated two main groups constituted by the populations of Grande Terre and
the populations of Iles Loyauté. A principal component analysis of leaf and seed morphology traits singled out the populations
of Iles Loyauté and the western populations of Grande Terre. Quantitative genetic analyses showed that the variation between
populations was under genetic control (broad sense heritability close to 80%). A high correlation between rainfall and morphological
traits suggested an impact of climate on this variation. The integration of these results allows to define two ESUs, one corresponding
to Grande Terre and Ile des Pins and the other the Iles Loyauté archipelago. This study stresses the need to restore some
populations of Grande Terre that are currently threatened by their small size. 相似文献
84.
Toillon RA Lagadec C Page A Chopin V Sautière PE Ricort JM Lemoine J Zhang M Hondermarck H Le Bourhis X 《Molecular & cellular proteomics : MCP》2007,6(7):1239-1247
Normal breast epithelial cells are known to exert an apoptotic effect on breast cancer cells, resulting in a potential paracrine inhibition of breast tumor development. In this study we purified and characterized the apoptosis-inducing factors secreted by normal breast epithelial cells. Conditioned medium was concentrated by ultrafiltration and separated on reverse phase Sep-Pak C18 and HPLC. The proapoptotic activity of eluted fractions was tested on MCF-7 breast cancer cells, and nano-LC-nano-ESI-MS/MS allowed the identification of insulin-like growth factor-binding protein-3 (IGFBP-3) and maspin as the proapoptotic factors produced by normal breast epithelial cells. Western blot analysis of conditioned media confirmed the specific secretion of IGFBP-3 and maspin by normal cells but not by breast cancer cells. Immunodepletion of IGFBP-3 and maspin completely abolished the normal cell-induced apoptosis of cancer cells, and recombinant proteins reproduced the effect of normal cell-conditioned medium on apoptosis of breast cancer cells. Together our results indicated that normal breast epithelial cells can induce apoptosis of breast cancer cells through IGFBP-3 and maspin. These findings provide a molecular hypothesis for the long observed inhibitory effect of normal surrounding cells on breast cancer development. 相似文献
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86.
Nicole C. Thunes Rachel A. Conrad Haitham H. Mohammed Yongtao Zhu Paul Barbier Jason P. Evenhuis David Perez-Pascual Jean-Marc Ghigo Ryan S. Lipscomb John R. Schneider Nan Li Devon H. Erbes Clayton Birkett Benjamin R. LaFrentz Timothy J. Welch Mark J. McBride 《Applied and environmental microbiology》2022,88(3)
87.
Ritabrata Dutta Karim Zouaoui Boudjeltia Christos Kotsalos Alexandre Rousseau Daniel Ribeiro de Sousa Jean-Marc Desmet Alain Van Meerhaeghe Antonietta Mira Bastien Chopard 《PLoS computational biology》2022,18(3)
Cardio/cerebrovascular diseases (CVD) have become one of the major health issue in our societies. But recent studies show that the present pathology tests to detect CVD are ineffectual as they do not consider different stages of platelet activation or the molecular dynamics involved in platelet interactions and are incapable to consider inter-individual variability. Here we propose a stochastic platelet deposition model and an inferential scheme to estimate the biologically meaningful model parameters using approximate Bayesian computation with a summary statistic that maximally discriminates between different types of patients. Inferred parameters from data collected on healthy volunteers and different patient types help us to identify specific biological parameters and hence biological reasoning behind the dysfunction for each type of patients. This work opens up an unprecedented opportunity of personalized pathology test for CVD detection and medical treatment. 相似文献
88.
FRET multiphoton spectral imaging microscopy of 7-ketocholesterol and Nile Red in U937 monocytic cells loaded with 7-ketocholesterol 总被引:1,自引:0,他引:1
Kahn E Vejux A Dumas D Montange T Frouin F Robert V Riedinger JM Stoltz JF Gambert P Todd-Pokropek A Lizard G 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》2004,26(6):304-313
OBJECTIVE: To show the effect of 7-ketocholesterol (7KC) on cellular lipid content by means of flow cytometry and the interaction of 7KC with Nile Red (NR) via ultraviolet fluorescence resonance energy transfer (FRET) excitation of NR on U937 monocytic cells by means of 2-photon excitation confocal laser scanning microscopy (CLSM). STUDY DESIGN: Untreated and 7KC-treated U937 cells were stained with NR and analyzed by flow cytometry and CLSM. 3D sequences of images were obtained by spectral analysis in a 2-photon excitation CLSM and analyzed by the factor analysis of medical image sequences (FAMIS) algorithm, which provides factor curves and images. Factor images are the result of the FAMIS image processing method, which handles emission spectra. In FRET analysis, preparations are screened at selected UV wavelengths to avoid emission of NR in the absence of 7KC. RESULTS: During 7KC-induced cell death,flow cytometry and CLSM revealed a modification of the cellular lipid content. Factor images show FRET occurrence and subsequent colocalization of 7KC and NR. CONCLUSION: This investigation established the utility of 2-photon excitation CLSM to assess colocalization of 7KC with NR by FRET and to identify and distinguish polar and neutral lipids stained by NR that accumulate from the effect of 7KC. 相似文献
89.
90.