33 research outputs found
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 63Â 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
Label-Free Characterization of Peptide–Lipid Interactions Using Immobilized Lipodisks
Irrelevant tactile stimulation biases visual exploration in external coordinates
Ossandón JP, König P, Heed T. Irrelevant tactile stimulation biases visual exploration in external coordinates. Scientific Reports. 2015;5(1): 10664
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Axonal Transport Reductions in Acute Experimental Allergic Encephalomyelitis: Qualitative Analysis of the Optic Nerve
In order to determine if changes in axonal transport were different in adult animals with acute experimental allergic encephalomyelitis (EAE), in comparison to juvenile animals with chronic EAE, the effects of this acute demyelin-ating disorder on axonal transport were examined in the Optic nerves of adult strain-13 guinea pigs. Utilizing autoradiographic analysis of silver grain counts, both the fast and slow components of orthograde transport were studied at intervals of thirty minutes, three hours, one day and three days after tritiated leucine injection into the vitreous cavity. In order to determine the contribution of fiber loss in acute EAE, optic nerve fiber density was analyzed from electron micrographs of normal and demyelinated nerves. Animals with acute EAE had a decrease in radioactivity at the lamina retinalis and lamina choroidalis after thirty minutes and three hours, and at the lamina scleralis and foci of demyelination after one and three days. A 16% loss of fibers did not account for as much as a 74% reduction in radioactivity with acute EAE. The global reductions in axonal transport observed in acute EAE animals my contribute to their progressive deterioration and eventual demise by lack of delivery of tubule-vesicular mterials for synaptic transmission, axolenmmal proteins for electrogenesis and neurofilamentary components of the cytoskeleton. Moreover, they are unlike the increase of fast axonal transport associated with recovery of physiologic function characteristic of animals with the chronic form of the disease