scholarly journals Mechanisms of transcriptional regulation of ecdysone response

2019 ◽  
Vol 23 (2) ◽  
pp. 212-218 ◽  
Author(s):  
M. Yu. Mazina ◽  
N. E. Vorobyeva
Keyword(s):  
Salivary Glands ◽  
Structural Changes ◽  
Gene Activation ◽  
Regulatory Elements ◽  
Cell Type Specificity ◽  
Excellent Description ◽  
The Many ◽  
General Aspects ◽  
Available Information

The mechanisms of ecdysone-dependent expression have been studied for many decades. Initially, the activation of individual genes under the influence of ecdysone was studied on the model of polythene chromosomes from salivary glands of Drosophila melanogaster. These works helped to investigate the many aspects of the Drosophila development. They also revealed plenty of valuable information regarding the fundamental mechanisms controlling the genes’ work. Many years ago, a model describing the process of gene activation by ecdysone, named after the author – Ashburner model – was proposed. This model is still considered an excellent description of the ecdysone cascade, which is implemented in the salivary glands during the formation of the Drosophila pupa. However, these days there is an opinion that the response of cells to the hormone ecdysone can develop with significant differences, depending on the type of cells. The same genes can be activated or repressed under the influence of ecdysone in different tissues. Likely, certain DNA-binding transcription factors that are involved in the ecdysonedependent response together with the EcR/Usp heterodimer are responsible for cell-type specificity. A number of transcriptional regulators involved in the ecdysone response have been described. Among them are several complexes responsible for chromatin remodeling and modification. It has been shown by various methods that ecdysone-dependent activation/repression of gene transcription develops with significant structural changes of chromatin on regulatory elements. The description of the molecular mechanism of this process, in particular, the role of individual proteins in it, as well as structural interactions between various regulatory elements is a matter of the future. This review is aimed to discuss the available information regarding the main regulators that interact with the ecdysone receptor. We provide a brief description of the regulator’s participation in the ecdysone response and links to the corresponding study. We also discuss general aspects of the mechanism of ecdysone-dependent regulation and highlight the most promising points for further research.

scholarly journals A scalable platform for the development of cell-type-specific viral drivers

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Sinisa Hrvatin ◽  
Christopher P Tzeng ◽  
M Aurel Nagy ◽  
Hume Stroud ◽  
Charalampia Koutsioumpa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heterologous Gene Expression ◽  
High Specificity ◽  
Cell Types ◽  
Regulatory Elements ◽  
Cell Type ◽  
Cell Type Specificity ◽  
Cell Type Specific ◽  
The Many ◽  
Dna Regulatory Elements

Enhancers are the primary DNA regulatory elements that confer cell type specificity of gene expression. Recent studies characterizing individual enhancers have revealed their potential to direct heterologous gene expression in a highly cell-type-specific manner. However, it has not yet been possible to systematically identify and test the function of enhancers for each of the many cell types in an organism. We have developed PESCA, a scalable and generalizable method that leverages ATAC- and single-cell RNA-sequencing protocols, to characterize cell-type-specific enhancers that should enable genetic access and perturbation of gene function across mammalian cell types. Focusing on the highly heterogeneous mammalian cerebral cortex, we apply PESCA to find enhancers and generate viral reagents capable of accessing and manipulating a subset of somatostatin-expressing cortical interneurons with high specificity. This study demonstrates the utility of this platform for developing new cell-type-specific viral reagents, with significant implications for both basic and translational research.

Elemental Interfaces and Displacive Phase Transformations

2008 ◽  
Vol 59 ◽  
pp. 63-68
Author(s):  
Václav Paidar
Keyword(s):  
Phase Transformations ◽  
Structural Changes ◽  
Atomic Plane ◽  
Many Body ◽  
Single Plane ◽  
Atomistic Models ◽  
Shear Type ◽  
Hcp Structure ◽  
The Many

Two basic processes, namely shear and shuffling of atomic planes can be considered as elementary mechanisms of displacive phase transformations. The atomistic models suitable to investigate the role of interfaces in the structural changes are tested. The many-body potentials are used for the description of interatomic forces. General displacements of atomic planes are examined, i.e. γ-surface type calculations extensively used for stacking fault and lattice dislocation analysis are applied to single plane shuffling and alternate shuffling of every other atomic plane producing in combination with homogeneous deformation the hcp structure. Similar approach considering shear type planar displacements leads to the Zener path between the bcc and fcc lattices. The effect of additional deformation required to obtain the close-packed atomic arrangements is analysed.

scholarly journals A model of active transcription hubs that unifies the roles of active promoters and enhancers

2021 ◽  
Author(s):  
Iris Zhu ◽  
Wei Song ◽  
Ivan Ovcharenko ◽  
David Landsman
Keyword(s):  
Spatial Organization ◽  
Regulatory Elements ◽  
Cell Type Specificity ◽  
Essential Questions ◽  
Active Transcription ◽  
Gene Regulatory ◽  
Hub Model ◽  
Universal Pattern ◽  
Active Genes

Abstract An essential questions of gene regulation is how large number of enhancers and promoters organize into gene regulatory loops. Using transcription-factor binding enrichment as an indicator of enhancer strength, we identified a portion of H3K27ac peaks as potentially strong enhancers and found a universal pattern of promoter and enhancer distribution: At actively transcribed regions of length of ∼200–300 kb, the numbers of active promoters and enhancers are inversely related. Enhancer clusters are associated with isolated active promoters, regardless of the gene's cell-type specificity. As the number of nearby active promoters increases, the number of enhancers decreases. At regions where multiple active genes are closely located, there are few distant enhancers. With Hi-C analysis, we demonstrate that the interactions among the regulatory elements (active promoters and enhancers) occur predominantly in clusters and multiway among linearly close elements and the distance between adjacent elements shows a preference of ∼30 kb. We propose a simple rule of spatial organization of active promoters and enhancers: Gene transcriptions and regulations mainly occur at local active transcription hubs contributed dynamically by multiple elements from linearly close enhancers and/or active promoters. The hub model can be represented with a flower-shaped structure and implies an enhancer-like role of active promoters.

scholarly journals Epigenetic Activation of the Human Growth Hormone Gene Cluster during Placental Cytotrophoblast Differentiation

2007 ◽  
Vol 27 (18) ◽  
pp. 6555-6568 ◽  
Author(s):  
Atsushi P. Kimura ◽  
Daria Sizova ◽  
Stuart Handwerger ◽  
Nancy E. Cooke ◽  
Stephen A. Liebhaber
Keyword(s):  
Growth Hormone ◽  
Structural Changes ◽  
Gene Activation ◽  
Human Growth ◽  
Regulatory Elements ◽  
Growth Hormone Gene ◽  
Human Pituitary ◽  
Chromatin Structural ◽  
Culture Models ◽  
The Individual

ABSTRACT The hGH cluster contains a single human pituitary growth hormone gene (hGH-N) and four placenta-specific paralogs. Activation of the cluster in both tissues depends on 5′ remote regulatory elements. The pituitary-specific locus control elements DNase I-hypersensitive site I (HSI) and HSII, located 14.5 kb 5′ of the cluster (position −14.5), establish a continuous domain of histone acetylation that extends to and activates hGH-N in the pituitary gland. In contrast, histone modifications in placental chromatin are restricted to the more 5′-remote HSV-HSIII region (kb −28 to −32) and to the placentally expressed genes in the cluster, with minimal modification between these two regions. These data predict distinct modes of hGH cluster gene activation in the pituitary and placenta. Here we used cell culture models to track structural changes at the hGH locus through placental-gene activation. The data revealed that this process was initiated in primary cytotrophoblasts by histone H3K4 di- and trimethylation and H4 acetylation restricted to HSV and to the individual placental-gene repeat (PGR) units within the cluster. Later stages of transcriptional induction were accompanied by enhancement and extension of these modifications and by robust H3 acetylation at HSV, at HSIII, and throughout the placental-gene regions. These data suggested that elements restricted to HSIII-HSV regions and each individual PGR might be sufficient for activation of the hCS genes. This model was tested by comparing hCS transgene expression in the placentas of mouse embryos carrying a full hGH cluster to that in placentas in which the HSIII-HSV region was directly linked to the individual hCS-A PGR unit. The findings indicate that the HSIII-HSV region and the PGR units, although targeted for initial chromatin structural modifications, are insufficient to activate gene expression and that this process is dependent on additional, as-yet-unidentified chromatin determinants.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

Conformational characterization of nucleosome structure by Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 194-195
Author(s):  
Gregory J. Czarnota
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Physiological State ◽  
Gene Activation ◽  
Three Dimensional ◽  
Macromolecular Complex ◽  
Ultrastructural Studies ◽  
Ionic Environment ◽  
Nucleosome Structure ◽  
Dimensional Reconstruction

Chromatin structure at the fundamental level of the nucleosome is important in vital cellular processes. Recent biochemical and genetic analyses show that nucleosome structure and structural changes are very active participants in gene expression, facilitating or inhibiting transcription and reflecting the physiological state of the cell. Structural states and transitions for this macromolecular complex, composed of DNA wound about a heterotypic octamer of variously modified histone proteins, have been measured by physico-chemical techniques and by enzyme-accessibility and are recognized to occur with various post-translational modifications, gene activation, transformation and with ionic-environment. In spite of studies which indicate various forms of nucleosome structure, all current x-ray and neutron diffraction studies have consistently resulted in only one structure, suggestive of a static conformation. In contrast, two-dimensional electron microscopy studies and three-dimensional reconstruction techniques have yielded different structures. These fundamental differences between EM and other ultrastructural studies have created a long standing quandary, which I have addressed and resolved using spectroscopic electron microscopy and statistical analyses of nucleosome images in a study of nucleosome structure with ionic environment.

The future role of the psychiatrist in Europe – a UEMS perspective

2014 ◽  
Vol 11 (01) ◽  
pp. 35-42
Author(s):  
M. Hermans
Keyword(s):  
Mental Health ◽  
Mental Health Professionals ◽  
Health Professionals ◽  
General Interest ◽  
Future Role ◽  
Personal Opinion ◽  
The Future ◽  
The Subject ◽  
The Many

SummaryThe author presents his personal opinion inviting to discussion on the possible future role of psychiatrists. His view is based upon the many contacts with psychiatrists all over Europe, academicians and everyday professionals, as well as the familiarity with the literature. The list of papers referred to is based upon (1) the general interest concerning the subject when representing ideas also worded elsewhere, (2) the accessibility to psychiatrists and mental health professionals in Germany, (3) being costless downloadable for non-subscribers and (4) for some geographic aspects (e.g. Belgium, Spain, Sweden) and the latest scientific issues, addressing some authors directly.

Economic Growth: New Problems and New Risks

2006 ◽  
pp. 20-37 ◽  
Author(s):  
M. Ershov
Keyword(s):  
Economic Growth ◽  
Foreign Exchange ◽  
Driving Force ◽  
Structural Changes ◽  
Rate Of Growth

The economic growth, which is underway in Russia, raises new questions to be addressed. How to improve the quality of growth, increasing the role of new competitive sectors and transforming them into the driving force of growth? How can progressive structural changes be implemented without hampering the rate of growth in general? What are the main external and internal risks, which may undermine positive trends of development? The author looks upon financial, monetary and foreign exchange aspects of the problem and comes up with some suggestions on how to make growth more competitive and sustainable.

John Cranko's Antigone (1959): A Ballet Lost and Found

2015 ◽  
Vol 33 (1) ◽  
pp. 1-15
Author(s):  
Henrietta Bannerman
Keyword(s):  
World War Ii ◽  
Jean Racine ◽  
World War ◽  
Martha Graham ◽  
Detailed Consideration ◽  
Lost And Found ◽  
The Many ◽  
Tragic Drama ◽  
The Relationship

John Cranko's dramatic and theatrically powerful Antigone (1959) disappeared from the ballet repertory in 1966 and this essay calls for a reappraisal and restaging of the work for 21st century audiences. Created in a post-World War II environment, and in the wake of appearances in London by the Martha Graham Company and Jerome Robbins’ Ballets USA, I point to American influences in Cranko's choreography. However, the discussion of the Greek-themed Antigone involves detailed consideration of the relationship between the ballet and the ancient dramas which inspired it, especially as the programme notes accompanying performances emphasised its Sophoclean source but failed to recognise that Cranko mainly based his ballet on an early play by Jean Racine. As Antigone derives from tragic drama, the essay investigates catharsis, one of the many principles that Aristotle delineated in the Poetics. This well-known effect is produced by Greek tragedies but the critics of the era complained about its lack in Cranko's ballet – views which I challenge. There is also an investigation of the role of Antigone, both in the play and in the ballet, and since Cranko created the role for Svetlana Beriosova, I reflect on memories of Beriosova's interpretation supported by more recent viewings of Edmée Wood's 1959 film.

The Many Voices of Lydia Davis

2016 ◽  
Author(s):  
Jonathan Evans
Keyword(s):  
Short Stories ◽  
Marcel Proust ◽  
Gustave Flaubert ◽  
Maurice Blanchot ◽  
Literary Production ◽  
American Writer ◽  
Michel Leiris ◽  
The Many

The Many Voices of Lydia Davis shows how translation, rewriting and intertextuality are central to the work of Lydia Davis, a major American writer, translator and essayist. Winner of the Man Booker International Prize 2013, Davis writes innovative short stories that question the boundaries of the genre. She is also an important translator of French writers such as Maurice Blanchot, Michel Leiris, Marcel Proust and Gustave Flaubert. Translation and writing go hand-in-hand in Davis’s work. Through a series of readings of Davis’s major translations and her own writing, this book investigates how Davis’s translations and stories relate to each other, finding that they are inextricably interlinked. It explores how Davis uses translation - either as a compositional tool or a plot device - and other instances of rewriting in her stories, demonstrating that translation is central for understanding her prose. Understanding how Davis’s work complicates divisions between translating and other forms of writing highlights the role of translation in literary production, questioning the received perception that translation is less creative than other forms of writing.

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