Characterization of organic matter in spodosol amazonian by fluorescence spectroscopy.

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High resolution imaging reveals heterogeneity in chromatin states between cells that is not inherited through cell division

BACKGROUND: Genomes of eukaryotes exist as chromatin, and it is known that different chromatin states can influence gene regulation. Chromatin is not a static structure, but is known to be dynamic and vary between cells. In order to monitor the organisation of chromatin in live cells we have engineered fluorescent fusion proteins which recognize specific operator sequences to tag pairs of syntenic gene loci. The separation of these loci was then tracked in three dimensions over time using fluorescence microscopy. RESULTS: We established a work flow for measuring the distance between two fluorescently tagged, syntenic gene loci with a mean measurement error of 63 nm. In general, physical separation was observed to increase with increasing genomic separations. However, the extent to which chromatin is compressed varies for different genomic regions. No correlation was observed between compaction and the distribution of chromatin markers from genomic datasets or with contacts identified using capture based approaches. Variation in spatial separation was also observed within cells over time and between cells. Differences in the conformation of individual loci can persist for minutes in individual cells. Separation of reporter loci was found to be similar in related and unrelated daughter cell pairs. CONCLUSIONS: The directly observed physical separation of reporter loci in live cells is highly dynamic both over time and from cell to cell. However, consistent differences in separation are observed over some chromosomal regions that do not correlate with factors known to influence chromatin states. We conclude that as yet unidentified parameters influence chromatin configuration. We also find that while heterogeneity in chromatin states can be maintained for minutes between cells, it is not inherited through cell division. This may contribute to cell-to-cell transcriptional heterogeneity. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12860-016-0111-y) contains supplementary material, which is available to authorized users

Characterization of organic matter in spodosol amazonian by fluorescence spectroscopy.

Made available in DSpace on 2017-11-01T23:24:04Z (GMT). No. of bitstreams: 1 PROCI17Characterizationoforganicmatter....pdf: 410306 bytes, checksum: f322a4c020812fc6c19f9e91b1efdcfe (MD5) Previous issue date: 2017-10-30bitstream/item/165808/1/PROCI-17-Characterization-of-organic-matter....pd

Reconstructing 3D genomes from chromosomal contact maps

International audienceA computational challenge raised by chromosome conformation capture (3C) experiments is to reconstruct spatial distances and three-dimensional genome structures from observed contacts between genomic loci. We propose a two-step algorithm, ShRec3D, and assess its accuracy using both in silico data and human genome-wide 3C (Hi-C) data. This algorithm avoids convergence issues, accommodates sparse and noisy contact maps, and is orders of magnitude faster than existing methods

Correlations of three-dimensional motion of chromosomal loci in yeast revealed by the double-helix point spread function microscope

Single-particle tracking has been applied to study chromatin motion in live cells, revealing a wealth of dynamical behavior of the genomic material once believed to be relatively static throughout most of the cell cycle. Here we used the dual-color three-dimensional (3D) double-helix point spread function microscope to study the correlations of movement between two fluorescently labeled gene loci on either the same or different budding yeast chromosomes. We performed fast (10 Hz) 3D tracking of the two copies of the GAL locus in diploid cells in both activating and repressive conditions. As controls, we tracked pairs of loci along the same chromosome at various separations, as well as transcriptionally orthogonal genes on different chromosomes. We found that under repressive conditions, the GAL loci exhibited significantly higher velocity cross-correlations than they did under activating conditions. This relative increase has potentially important biological implications, as it might suggest coupling via shared silencing factors or association with decoupled machinery upon activation. We also found that on the time scale studied (∼0.1–30 s), the loci moved with significantly higher subdiffusive mean square displacement exponents than previously reported, which has implications for the application of polymer theory to chromatin motion in eukaryotes