scholarly journals Chromatin fiber structural motifs as regulatory hubs of genome function?

2019 ◽  
Vol 63 (1) ◽  
pp. 123-132 ◽  
Author(s):  
Manuela Moraru ◽  
Thomas Schalch
Keyword(s):  
Recent Progress ◽  
Higher Order ◽  
Chromatin Fiber ◽  
Structural Level ◽  
Structural Motifs ◽  
Random Structures ◽  
Fractal Characteristics ◽  
Chromatin Fibers ◽  
Eukaryotic Genomes

Abstract Nucleosomes cover eukaryotic genomes like beads on a string and play a central role in regulating genome function. Isolated strings of nucleosomes have the potential to compact and form higher order chromatin structures, such as the well-characterized 30-nm fiber. However, despite tremendous advances in observing chromatin fibers in situ it has not been possible to confirm that regularly ordered fibers represent a prevalent structural level in the folding of chromosomes. Instead, it appears that folding at a larger scale than the nucleosome involves a variety of random structures with fractal characteristics. Nevertheless, recent progress provides evidence for the existence of structural motifs in chromatin fibers, potentially localized to strategic sites in the genome. Here we review the current understanding of chromatin fiber folding and the emerging roles that oligonucleosomal motifs play in the regulation of genome function.

Transitions between in situ and isolated chromatin

1993 ◽  
Vol 105 (2) ◽  
pp. 551-561 ◽  
Author(s):  
P.J. Giannasca ◽  
R.A. Horowitz ◽  
C.L. Woodcock
Keyword(s):  
Higher Order ◽  
Chromatin Fiber ◽  
Sperm Chromatin ◽  
Order Structure ◽  
Native State ◽  
Chromatin Fibers

We show that the mechanism by which chromatin displaying higher-order structure is usually isolated from nuclei involves a transition to an extended nucleosomal arrangement. After being released from nuclei, chromatin must refold in order to produce the typical chromatin fibers observed in solution. For starfish sperm chromatin with a long nucleosome repeat (222 bp), isolated fibers are significantly wider than those in the nucleus, indicating that the refolding process does not regenerate the native higher-order structure. We also propose that for typical eukaryotic nuclei, the concept that the native state of the (inactive) bulk of the genome is a chromatin fiber with defined architecture be reconsidered.

scholarly journals Nucleosome packing in interphase chromatin.

1979 ◽  
Vol 81 (2) ◽  
pp. 453-457 ◽  
Author(s):  
J B Rattner ◽  
B A Hamkalo
Keyword(s):  
Electron Microscope ◽  
Chromatin Condensation ◽  
Higher Order ◽  
Chromatin Fiber ◽  
Interphase Chromatin ◽  
Metaphase Chromosomes ◽  
Microscope Analysis ◽  
Electron Microscope Analysis ◽  
Chromatin Fibers

Higher-order chromatin fibers (200--300 A in diameter) are reproducibly released from nuclei after lysis in the absence of formalin and/or detergent. Electron microscope analysis of these fibers shows that they are composed of a continuous array of closely apposed nucleosomes which display several distinct packing patterns. Analysis of the organization of nucleosomes within these arrays and their distribution along long stretches of chromatin suggest that the basic 100-A chromatin fiber is not packed into discrete superbeads and is not folded into a uniform solenoid within the native 250-A fiber. Furthermore, because similar higher-order fibers have been visualized in metaphase chromosomes, the existence of this fiber class appears to be independent of the degree of in vivo chromatin condensation.

Comparison of higher-order aberrations after wavefront-guided laser in situ keratomileusis and laser-assisted subepithelial keratectomy

2006 ◽  
Vol 32 (5) ◽  
pp. 779-784 ◽  
Author(s):  
So-Hyang Chung ◽  
In Sik Lee ◽  
Young Ghee Lee ◽  
Hyung Keun Lee ◽  
Eung Kweon Kim ◽  
...  
Keyword(s):  
Higher Order ◽  
Laser In Situ Keratomileusis ◽  
Higher Order Aberrations

scholarly journals Chromatin fibers observed in situ in frozen hydrated sections. Native fiber diameter is not correlated with nucleosome repeat length.

1994 ◽  
Vol 125 (1) ◽  
pp. 11-19 ◽  
Author(s):  
C L Woodcock
Keyword(s):  
Cell Types ◽  
Repeat Length ◽  
Strong Positive Correlation ◽  
Whole Cells ◽  
Chromosome Architecture ◽  
Chromatin Fibers ◽  
The Moment ◽  
Chicken Erythrocytes ◽  
Patiria Miniata

Chromatin fibers have been observed and measured in frozen hydrated sections of three types of cell (chicken erythrocytes and sperm of Patiria miniata and Thyone briareus) representing an approximately 20-bp range of nucleosomal repeat lengths. For sperm of the starfish P. miniata, it was possible to obtain images of chromatin fibers from cells that were swimming in seawater up to the moment of cryo-immobilization, thus providing a record of the native morphology of the chromatin of these cells. Glutaraldehyde fixation produced no significant changes in the ultrastructure or diameter of chromatin fibers, and fiber diameters observed in cryosections were similar to those recorded after low temperature embedding in Lowicryl K11M. Chromatin fiber diameters measured from cryosections of the three types of nuclei were similar, a striking contrast to the situation for chromatin isolated from these cell types, where a strong positive correlation between diameter and nucleosomal repeat length has been established. The demonstration of chromatin fibers in unfixed whole cells establishes an unequivocal baseline for the study of native chromatin and chromosome architecture. The significant differences between chromatin fibers in nucleo and after isolation supports a previous observation (P. J. Giannasca, R. A. Horowitz, and C. L. Woodcock. 1993. J. Cell Sci. 105:551-561), and suggests that structural studies on isolated material should be interpreted with caution until the changes that accompany chromatin isolation are understood.

scholarly journals Mitochondria-Targeted Self-Assembly of Peptide-Based Nanomaterials

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhen Luo ◽  
Yujuan Gao ◽  
Zhongyu Duan ◽  
Yu Yi ◽  
Hao Wang
Keyword(s):  
Clinical Trials ◽  
Cancer Therapy ◽  
Self Assembly ◽  
Recent Progress ◽  
Assembly Systems ◽  
Targeted Cancer Therapy ◽  
Cancer Treatments ◽  
Self Assembling ◽  
Stimuli Response

Mitochondria are well known to serve as the powerhouse for cells and also the initiator for some vital signaling pathways. A variety of diseases are discovered to be associated with the abnormalities of mitochondria, including cancers. Thus, targeting mitochondria and their metabolisms are recognized to be promising for cancer therapy. In recent years, great efforts have been devoted to developing mitochondria-targeted pharmaceuticals, including small molecular drugs, peptides, proteins, and genes, with several molecular drugs and peptides enrolled in clinical trials. Along with the advances of nanotechnology, self-assembled peptide-nanomaterials that integrate the biomarker-targeting, stimuli-response, self-assembly, and therapeutic effect, have been attracted increasing interest in the fields of biotechnology and nanomedicine. Particularly, in situ mitochondria-targeted self-assembling peptides that can assemble on the surface or inside mitochondria have opened another dimension for the mitochondria-targeted cancer therapy. Here, we highlight the recent progress of mitochondria-targeted peptide-nanomaterials, especially those in situ self-assembly systems in mitochondria, and their applications in cancer treatments.

Co-creation and higher order customer engagement in hospitality and tourism services

2016 ◽  
Vol 28 (2) ◽  
pp. 222-245 ◽  
Author(s):  
Prakash K. Chathoth ◽  
Gerardo R. Ungson ◽  
Robert J. Harrington ◽  
Eric S.W. Chan
Keyword(s):  
Value Creation ◽  
Higher Order ◽  
Customer Engagement ◽  
Service Dominant Logic ◽  
Content Type ◽  
Dominant Logic ◽  
Ex Post ◽  
Ex Ante ◽  
Experiential Value

Purpose – This paper aims to present a review of the literature associated with co-creation and higher-order customer engagement concepts and poses critical questions related to the current state of research. Additionally, the paper presents a framework for customer engagement and co-creation with relevance to hospitality transactions. Design/methodology/approach – Earlier research on co-production, co-creation, consumer engagement and service-dominant logic are discussed and synthesized. Based on this synthesis, links and contrasts of these varying research streams are presented providing an articulation of key characteristics of each and how these might be applied within a hospitality context. Findings – Modalities in service transactions vary among traditional production, co-production and co-creation based on changes in attitudes, enabling technologies and the logic or ideology supporting the change. Transaction characteristics vary among manufacturing, quasi-manufacturing and services based on several key categories including differences in boundary conditions, enablers, success requirements, sustainability requirements, the dominant logic used and key barriers/vulnerabilities. When creating experiential value for consumers, firms should consider several aspects ex-ante, in-situ and ex-post of the change and during the change process. Research limitations/implications – Firms need to move toward higher-order customer engagement using co-creative modalities to enhance value creation. Current practices in the hotel industry may not in their entirety support this notion. Ex-ante, in-situ and ex-post considerations for creating experiential value need to be used as part of a checklist of questions for firms to pose in order to move toward managing customer experiences using the service-dominant logic as part of the firm’s orientation toward its market. This would give it the required thrust to create superior engagement platforms that use co-creative modalities while addressing the barriers to higher-order customer engagement as identified in the literature. Originality/value – The hospitality and tourism literature on co-creation and higher-order customer engagement is still in its infancy. A synthesis of these early studies provides support for the need for future research on co-creation that more clearly articulates the modality firms could use to move toward co-creation. This paper develops a dynamic framework using characteristics of co-creation that integrate the various stages of value creation (i.e. input, throughput and output).

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