scholarly journals On the chromatin of the immature oocyte: from morphology to function and regulatory mechanisms mediated by follicular cells

2015 ◽  
Author(s):  
Valentina Lodde ◽  
Silvia C. Modina ◽  
Alberto M. Luciano
Keyword(s):  
Cell Biology ◽  
Molecular Mechanisms ◽  
Functional Aspects ◽  
Complex Process ◽  
Chromatin Configuration ◽  
Oocyte Differentiation ◽  
The Relationship ◽  
Insight Into ◽  
Tremendous Impact

In her comment entitled ‘Nuclear histochemistry: its history in fifty volumes’ (Eur J Histochem 2006; 50:79-81) Maria Gabriella Manfredi Romanini referred to “nuclear histochemistry” as a “real molecular biology in situ, applied to research on dynamic processes in the nucleus, which makes the microscopic and histochemical approach absolutely irreplaceable for the progress of our understanding of cell biology”. These words perfectly exemplify the research path that is elucidating the process of remodeling of chromatin configuration within the nucleus of the mammalian oocyte. This process, which occurs towards the end of the oocyte differentiation phase before meiotic resumption, has received much attention in the last decade since it has a tremendous impact on the capability of the oocyte to generate an embryo after fertilization. The study of the oocyte chromatin by means of classical morphological and histochemical approaches has given a fundamental contribution to our understanding of oocyte biology and has paved the way to functional and mechanistic studies. Several research groups worldwide, including ours, are indeed dedicating a large amount of studies to find the relationship between morphological and functional aspects of the oocyte chromatin remodeling process, to reveal the molecular mechanisms involved, as well as to clarify the contribution of the follicular compartment. Here, we summarize some studies intended to give insight into the mechanism( s) regulating this complex process, including recent findings indicating that ovarian granulosa cells and their coupling with the oocyte through gap junctions are implicated in such a process.

Regulation of TRPV5 and TRPV6 by associated proteins

2006 ◽  
Vol 290 (6) ◽  
pp. F1295-F1302 ◽  
Author(s):  
Stan F. J. van de Graaf ◽  
Joost G. J. Hoenderop ◽  
René J. M. Bindels
Keyword(s):  
Molecular Mechanisms ◽  
Hormonal Control ◽  
Trp Channel ◽  
Intestinal Lumen ◽  
Blood Compartment ◽  
Associated Proteins ◽  
The Relationship ◽  
Insight Into ◽  
Prime Target

The epithelial Ca2+ channels TRPV5 and TRPV6 are the most Ca2+-selective members of the TRP channel superfamily. These channels are the prime target for hormonal control of the active Ca2+ flux from the urine space or intestinal lumen to the blood compartment. Insight into their regulation is, therefore, pivotal in our understanding of the (patho)physiology of Ca2+ homeostasis. The recent elucidation of TRPV5/6-associated proteins has provided new insight into the molecular mechanisms underlying the regulation of these channels. In this review, we describe the various means of TRPV5/6 regulation, the role of channel-associated proteins herein, and the relationship between both processes.

scholarly journals Nucleosome–nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity

2017 ◽  
Vol 28 (11) ◽  
pp. 1580-1589 ◽  
Author(s):  
Yuta Shimamoto ◽  
Sachiko Tamura ◽  
Hiroshi Masumoto ◽  
Kazuhiro Maeshima
Keyword(s):  
Molecular Mechanisms ◽  
Mechanical Response ◽  
Nuclear Architecture ◽  
Living Cells ◽  
Genome Integrity ◽  
Biological Processes ◽  
Cell Nuclei ◽  
Histone Tails ◽  
Insight Into

Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers.

Impaired development of zygotes with uneven pronuclear size

Zygote ◽  
1998 ◽  
Vol 6 (2) ◽  
pp. 137-141 ◽  
Author(s):  
Sasha Sadowy ◽  
Giles Tomkin ◽  
Santiago Munné ◽  
Toni Ferrara-Congedo ◽  
Jacques Cohen
Keyword(s):  
Preimplantation Development ◽  
Chromosomal Anomalies ◽  
Hybridisation Analysis ◽  
Pronuclear Morphology ◽  
Selection For ◽  
The Relationship ◽  
Further Development ◽  
Zygote Stage ◽  
Insight Into

The correlation between human zygote morphology and chromosomal anomalies after cleavage has not been well characterised. Commonly observed morphological qualities at the zygote stage have provided little insight into further development, and therefore selection for cryopreservation or transfer appears to be less specific than that at later stages of preimplantation development. The purpose of this work was to evaluate the relationship between aberrant pronuclear morphology and chromosomal anomalies after cleavage. Monospermic zygotes exhibiting two pronuclei where diameters differed by at least 4 μm were found to arrest at a significantly higher rate than zygotes with pronuclear diameters differing by less than 4 µm. In addition, a higher incidence of day 2 multinucleation was observed. Embryos deriving from zygotes with dysmorphic pronuclei that were not replaced or cryopreserved by day 3 of development were separated and fixed for fluorescence in situ hybridisation analysis of chromosomes X, Y, 13, 18 and 21. A significantly higher incidence of mosaicism was found in this group compared with others that had developed from zygotes with normal pronuclear morphology. Although the mechanism leading to this form of divergent pronuclear morphology is unclear, results suggest a correlation with oocyte cyto-plasmic immaturity.

scholarly journals Zanvil Alexander Cohn 1926-1993.

1994 ◽  
Vol 179 (1) ◽  
pp. 1-30 ◽  
Author(s):  
R M Steinman ◽  
C L Moberg
Keyword(s):  
Cell Biology ◽  
Cell System ◽  
Mononuclear Phagocyte ◽  
Cytotoxic Lymphocytes ◽  
Culture Model ◽  
Disease Site ◽  
Tissue Culture Model ◽  
Antigen Presenting ◽  
The Relationship

Zanvil Alexander Cohn, an editor of this Journal since 1973, died suddenly on June 28, 1993. Cohn is best known as the father of the current era of macrophage biology. Many of his scientific accomplishments are recounted here, beginning with seminal studies on the granules of phagocytes that were performed with his close colleague and former editor of this Journal, James Hirsch. Cohn and Hirsch identified the granules as lysosomes that discharged their contents of digestive enzymes into vacuoles containing phagocytosed microbes. These findings were part of the formative era of cell biology and initiated the modern study of endocytosis and cell-mediated resistance to infection. Cohn further explored the endocytic apparatus in pioneering studies of the mouse peritoneal macrophage in culture. He described vesicular inputs from the cell surface and Golgi apparatus and documented the thoroughness of substrate digestion within lysosomal vacuoles that would only permit the egress of monosaccharides and amino acids. These discoveries created a vigorous environment for graduate students, postdoctoral fellows, and junior and visiting faculty. Some of the major findings that emerged from Cohn's collaborations included the radioiodination of the plasma membrane for studies of composition and turnover; membrane recycling during endocytosis; the origin of the mononuclear phagocyte system in situ; the discovery of the dendritic cell system of antigen-presenting cells; the macrophage as a secretory cell, including the release of proteases and large amounts of prostaglandins and leukotrienes; several defined parameters of macrophage activation, especially the ability of T cell-derived lymphokines to enhance killing of tumor cells and intracellular protozoa; the granule discharge mechanism whereby cytotoxic lymphocytes release the pore-forming protein perforin; the signaling of macrophages via myristoylated substrates of protein kinase C; and a tissue culture model in which monocytes emigrate across tight endothelial junctions. In 1983, Cohn turned to a long-standing goal of exploring host resistance directly in humans. He studied leprosy, focusing on the disease site, the parasitized macrophages of the skin. He injected recombinant lymphokines into the skin and found that these molecules elicited several cell-mediated responses. Seeing this potential to enhance host defense in patients, Cohn was extending his clinical studies to AIDS and tuberculosis. Zanvil Cohn was a consummate physician-scientist who nurtured the relationship between cell biology and infectious disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Defects in cytochrome oxidase assembly in humans: lessons from yeastThis paper is one of a selection of papers published in this Special Issue, entitled CSBMCB — Membrane Proteins in Health and Disease.

2006 ◽  
Vol 84 (6) ◽  
pp. 859-869 ◽  
Author(s):  
Jennifer M. Zee ◽  
D. Moira Glerum
Keyword(s):  
Molecular Mechanisms ◽  
Inner Mitochondrial Membrane ◽  
Yeast Saccharomyces Cerevisiae ◽  
Assembly Pathway ◽  
Complex Process ◽  
Health And Disease ◽  
Molecular Bases ◽  
Near Future ◽  
Insight Into ◽  
Selection Of

The biogenesis of the inner mitochondrial membrane enzyme cytochrome c oxidase (COX) is a complex process that requires the actions of ancillary proteins, collectively called assembly factors. Studies with the yeast Saccharomyces cerevisiae have provided considerable insight into the COX assembly pathway and have proven to be a fruitful model for understanding the molecular bases for inherited COX deficiencies in humans. In this review, we focus on critical steps in the COX assembly pathway. These processes are conserved from yeast to humans and are known to be involved in the etiology of human COX deficiencies. The contributions from our studies in yeast suggest that this organism remains an excellent model system for delineating the molecular mechanisms underlying COX assembly defects in humans. Current progress suggests that a complete picture of COX assembly will be achieved in the near future.

scholarly journals A Novel Taxon of RNA Viruses Endemic to Planarian Flatworms

2019 ◽  
Author(s):  
Jeffrey Burrows ◽  
Delphine Depierreux ◽  
Max L. Nibert ◽  
Bret J. Pearson
Keyword(s):  
Stem Cell ◽  
Rna Interference ◽  
Persistent Infection ◽  
Cell Biology ◽  
Molecular Mechanisms ◽  
Adult Stem Cell ◽  
Dsrna Virus ◽  
Rnai Pathway ◽  
Cell Type

AbstractThe phylum Platyhelminthes is composed of both parasitic and non-parasitic flatworms. While the parasitic species have drawn attention for their wide effects on human and livestock heath, free-living flatworms, such as freshwater planarians, have become molecular models of regeneration and stem cell biology in the laboratory. However, one aspect of planarian biology that remains understudied is the relationship between host and any endemic viruses. Here we used searches of multiple transcriptomes from Schmidtea mediterranea asexual strain CIW4 and detected a novel, double-stranded RNA (dsRNA) virus, named S. mediterranea tricladivirus (SmedTV), which represents a distinct taxon (proposed new genus) within a larger taxon of monosegmented dsRNA viruses of diverse hosts. Experimental evidence for SmedTV in S. mediterranea CIW4 was obtained through whole-mount in situ hybridization (WISH). SmedTV “expression” (detected by both sense and anti-sense probes) was discrete yet variable from worm to worm and cell type to cell type, suggesting a persistent infection. Single-cell RNA sequencing (scRNAseq) further supported that SmedTV expression was low in stem cells, but substantially higher in multiple, though not all, differentiated tissues, with notable neural enrichment.Interestingly, knockdown of SmedTV by RNA-interference resulted in a “cure” of SmedTV after 10 RNAi doses, and expression remained undetectable by WISH even after 90 days. Due to being able to evade host defenses and the endogenous RNAi pathway, we believe SmedTV represents a novel animal model to study host-virus evolution.Statement of significancePlanarians are freshwater flatworms and emerging models to study the molecular mechanisms of adult stem cell and regenerative biology. However, they also live in aquatic environments with high amounts of viruses, bacteria, fungi, and protist pathogens. How the planarian immune system copes with all of these is largely unknown and only 2 types of virus have been described. Here we find a novel dsRNA virus, endemic to multiple types of flatworms. We show that it is a persistent infection, and likely transmits from stem cell to differentiated cell in the planarian, while avoiding endogenous RNA-interference machinery and mechanisms used to suppress viruses. We present this as a new model to study host-virus defense and evolution.

scholarly journals Experimental study of shale drillability with different bedding inclinations under varying wellbore pressure conditions

2021 ◽  
Vol 11 (4) ◽  
pp. 1751-1759
Author(s):  
Shuai Chen ◽  
Xiangchao Shi ◽  
Heng Bao ◽  
Leiyu Gao ◽  
Jie Wu
Keyword(s):  
Mechanical Properties ◽  
Shale Gas ◽  
Physical And Mechanical Properties ◽  
In Situ Conditions ◽  
Wellbore Pressure ◽  
Development Engineering ◽  
The Impact ◽  
The Relationship ◽  
Insight Into

AbstractIn the practice of shale gas development engineering, it is important to understand the physical and mechanical properties of shale. The bedding inclinations of shale are known to significantly influence its physical and mechanical properties. This study mainly examined the influence of bedding inclinations on drillability under different wellbore pressures. The bedding inclinations used in this study varied from 0° to 90°, with a gradient of 15°. The wellbore pressure values used varied from 0 to 25 MPa, with a gradient of 5 MPa. The results show that the drillability index of shale increases exponentially with increasing wellbore pressure at different bedding inclinations. The proposed exponential empirical model can describe the relationship between the drillability index and wellbore pressure. When the wellbore pressure is less than 15 MPa, bedding inclinations significantly influence the drillability index, and the drillability index of shale shows a “W”-type variation trend as the bedding inclinations increase in the range of 0° to 90°. The influence of bedding inclinations on drillability decreases gradually with increasing wellbore pressure. When the wellbore pressure increases to 25 MPa, the impact of bedding inclinations on drillability is virtually undetectable. The results of this study can provide reasonably insight into the effect of bedding inclinations on shale deformation under the drill bit, and useful prediction for the drillability index under in situ conditions.

scholarly journals Comets

2005 ◽  
Vol 13 ◽  
pp. 762-762 ◽  
Author(s):  
Michael F. A’Hearn
Keyword(s):  
Solar System ◽  
Size Distribution ◽  
Wave Data ◽  
Near Ir ◽  
Recent Developments ◽  
Real Size ◽  
In Situ Observations ◽  
The Relationship ◽  
Insight Into

Earth-based observations of comets far surpass the ability of in situ observations to understand the range of cometary properties and thus provide unique insight into the relationship between comets and the formation of the solar system. Recent developments in composition have emphasized near-IR and mm-wave data, although optical and ultraviolet data still play crucial roles. Observers now realize the importance of chemistry in the coma. Surveys of nuclear sizes are beginning to provide a real size distribution and we have recent examples of breakup that provide important information on structure.

scholarly journals The crosstalk between autophagy and apoptosis was mediated by phosphorylation of Bcl-2 and beclin1 in benzene-induced hematotoxicity

2019 ◽  
Vol 10 (10) ◽  
Author(s):  
Yujiao Chen ◽  
Wei Zhang ◽  
Xiaoli Guo ◽  
Jing Ren ◽  
Ai Gao
Keyword(s):  
Risk Assessment ◽  
Molecular Mechanisms ◽  
Ros Generation ◽  
Hematological Cancer ◽  
Exposed Workers ◽  
Different Types ◽  
First Time ◽  
The Relationship ◽  
Insight Into

Abstract Increasing evidence suggested that benzene exposure resulted in different types of hematological cancer. Both autophagy and apoptosis were reported to play vital roles in benzene toxicity, but the relationship between autophagy and apoptosis remain unclear in benzene-induced hematotoxicity. In this study, the toxic effect of benzene on autophagy and apoptosis in benzene-exposed workers and in vitro were verified. Results showed that benzene metabolite (1, 4-benzoquinone, 1, 4-BQ) dose-dependently induced autophagy and apoptosis via enhancing phosphorylation of Bcl-2 and beclin1. Finally, we also found that the elevated ROS was in line with enhancing the phosphorylation of Bcl-2 and beclin1 which contributed to 1, 4-BQ-induced autophagy and apoptosis. Taken together, this study for the first time found that the effect of 1, 4-BQ on the crosstalk between autophagy and apoptosis were modulated by the ROS generation via enhancing phosphorylation of Bcl-2(Ser70) and phosphorylation of beclin1(Thr119), which offered a novel insight into underlying molecular mechanisms of benzene-induced hematotoxicity, and specifically how the crosstalk between autophagy and apoptosis was involved in benzene toxicity. This work provided novel evidence for the toxic effects and risk assessment of benzene.

scholarly journals A Regulatory Network for miR156-SPL Module in Arabidopsis thaliana

2019 ◽  
Vol 20 (24) ◽  
pp. 6166 ◽  
Author(s):  
Chenfei Zheng ◽  
Meixia Ye ◽  
Mengmeng Sang ◽  
Rongling Wu
Keyword(s):  
Molecular Mechanisms ◽  
High Throughput Sequencing ◽  
Phase Changes ◽  
Plant Age ◽  
Age Related ◽  
Complex Process ◽  
Spl Genes ◽  
Regulation Network ◽  
Rich Data ◽  
Insight Into

Vegetative phase changes in plants describes the transition between juvenile and adult phases of vegetative growth before flowering. It is one of the most fundamental mechanisms for plants to sense developmental signals, presenting a complex process involving many still-unknown determinants. Several studies in annual and perennial plants have identified the conservative roles of miR156 and its targets, SBP/SPL genes, in guiding the switch of plant growth from juvenile to adult phases. Here, we review recent progress in understanding the regulation of miR156 expression and how miR156-SPLs mediated plant age affect other processes in Arabidopsis. Powerful high-throughput sequencing techniques have provided rich data to systematically study the regulatory mechanisms of miR156 regulation network. From this data, we draw an expanded miR156-regulated network that links plant developmental transition and other fundamental biological processes, gaining novel and broad insight into the molecular mechanisms of plant-age-related processes in Arabidopsis.

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