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High-resolution Analysis (high-resolution + analysis)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Three-dimensional analysis of intermediate filament networks using SEM tomography

JOURNAL OF MICROSCOPY, Issue 1 2010
S. LÜCK
Summary We identified tomographic reconstruction of a scanning electron microscopy tilt series recording the secondary electron signal as a well-suited method to generate high-contrast three-dimensional data of intermediate filament (IF) networks in pancreatic cancer cells. Although the tilt series does not strictly conform to the projection requirement of tomographic reconstruction, this approach is possible due to specific properties of the detergent-extracted samples. We introduce an algorithm to extract the graph structure of the IF networks from the tomograms based on image analysis tools. This allows a high-resolution analysis of network morphology, which is known to control the mechanical response of the cells to large-scale deformations. Statistical analysis of the extracted network graphs is used to investigate principles of structural network organization which can be linked to the regulation of cell elasticity. [source]

A microarray-based approach for the identification of epigenetic biomarkers for the noninvasive diagnosis of fetal disease

PRENATAL DIAGNOSIS, Issue 11 2009
Tianjiao Chu
Abstract Objectives We describe a novel microarray-based approach for the high-throughput discovery of epigenetic biomarkers for use in the noninvasive detection of fetal genetic disease. Methods We combined a 215 060-probe custom oligonucleotide microarray with a comprehensive library preparation method and novel statistical tools to compare DNA methylation patterns in chorionic villus samples (CVS) with gestational age-matched maternal blood cell (MBC) samples. Our custom microarray was designed to provide high-resolution coverage across human chromosomes 13, 18 and 21. Results We identified 6311 MspI/HpaII sites across all three chromosomes that displayed tissue-specific differential CpG methylation patterns. To maximize the probability of identifying biomarkers that have clinical utility we filtered our data to identify MspI/HpaII sites that are within 150 bp of a highly polymorphic single nucleotide polymorphism (SNP) so that its allelic ratio may be determined for the detection of fetal aneuploidy. Our microarray design and the computational tools used for data analysis are available for download as is the entire data set. Conclusions This high-resolution analysis of DNA methylation patterns in the human placenta during the first trimester of pregnancy identifies numerous potential biomarkers for the diagnosis of fetal aneuploidy on chromosomes 13, 18 and 21. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Deamidation destabilizes and triggers aggregation of a lens protein, ,A3-crystallin

PROTEIN SCIENCE, Issue 9 2008
Takumi Takata
Abstract Protein aggregation is a hallmark of several neurodegenerative diseases and also of cataracts. The major proteins in the lens of the eye are crystallins, which accumulate throughout life and are extensively modified. Deamidation is the major modification in the lens during aging and cataracts. Among the crystallins, the ,A3-subunit has been found to have multiple sites of deamidation associated with the insoluble proteins in vivo. Several sites were predicted to be exposed on the surface of ,A3 and were investigated in this study. Deamidation was mimicked by site-directed mutagenesis at Q42 and N54 on the N-terminal domain, N133 and N155 on the C-terminal domain, and N120 in the peptide connecting the domains. Deamidation altered the tertiary structure without disrupting the secondary structure or the dimer formation of ,A3. Deamidations in the C-terminal domain and in the connecting peptide decreased stability to a greater extent than deamidations in the N-terminal domain. Deamidation at N54 and N155 also disrupted the association with the ,B1-subunit. Sedimentation velocity experiments integrated with high-resolution analysis detected soluble aggregates at 15%,20% in all deamidated proteins, but not in wild-type ,A3. These aggregates had elevated frictional ratios, suggesting that they were elongated. The detection of aggregates in vitro strongly suggests that deamidation may contribute to protein aggregation in the lens. A potential mechanism may include decreased stability and/or altered interactions with other ,-subunits. Understanding the role of deamidation in the long-lived crystallins has important implications in other aggregation diseases. [source]

Unexpected roles for cryptochrome 2 and phototropin revealed by high-resolution analysis of blue light-mediated hypocotyl growth inhibition

THE PLANT JOURNAL, Issue 5 2001
Kevin M. Folta
Summary Blue light (BL) rapidly and strongly inhibits hypocotyl elongation during the photomorphogenic response known as de-etiolation, the transformation of a dark-grown seedling into a pigmented, photoautotrophic organism. In Arabidopsis thaliana, high-resolution studies of hypocotyl growth accomplished by computer-assisted electronic image capture and analysis revealed that inhibition occurs in two genetically independent phases, the first beginning within 30 sec of illumination. The present work demonstrates that phototropin (nph1), the photoreceptor responsible for phototropism, is largely responsible for the initial, rapid inhibition. Signaling from phototropin during the curvature response is dependent upon interaction with NPH3, but the results presented here demonstrate that NPH3 is not necessary for phototropin-dependent growth inhibition. Activation of anion channels, which transiently depolarizes the plasma membrane within seconds of BL, is an early event in the cryptochrome signaling pathway leading to a phase of growth inhibition that replaces the transient phototropin-dependent phase after approximately 30 min of BL. Surprisingly, cry1 and cry2 were found to contribute equally and non-redundantly to anion-channel activation and to growth inhibition between 30 and 120 min of BL. Inspection of the inhibition kinetics displayed by nph1 and nph1cry1 mutants revealed that the cryptochrome phase of inhibition is delayed in seedlings lacking phototropin. This result indicates that BL-activation of phototropin influences cryptochrome signaling leading to growth inhibition. Mutations in the NPQ1 gene, which inhibit BL-induced stomatal opening, do not affect any aspect of the growth inhibition within the first 120 min examined here, and NPQ1 does not affect the activation of anion channels. [source]