Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

scholarly journals Chromatin and Epigenetic Rearrangements in Embryonic Stem Cell Fate Transitions

2021 ◽  
Vol 9 ◽  
Author(s):  
Li Sun ◽  
Xiuling Fu ◽  
Gang Ma ◽  
Andrew P. Hutchins
Keyword(s):  
Embryonic Development ◽  
Cell Fate ◽  
Embryonic Stem ◽  
Model Systems ◽  
Somatic Genome ◽  
Mouse Cells ◽  
Pass Through ◽  
Organismal Development ◽  
Human And Mouse

A major event in embryonic development is the rearrangement of epigenetic information as the somatic genome is reprogrammed for a new round of organismal development. Epigenetic data are held in chemical modifications on DNA and histones, and there are dramatic and dynamic changes in these marks during embryogenesis. However, the mechanisms behind this intricate process and how it is regulating and responding to embryonic development remain unclear. As embryos develop from totipotency to pluripotency, they pass through several distinct stages that can be captured permanently or transiently in vitro. Pluripotent naïve cells resemble the early epiblast, primed cells resemble the late epiblast, and blastomere-like cells have been isolated, although fully totipotent cells remain elusive. Experiments using these in vitro model systems have led to insights into chromatin changes in embryonic development, which has informed exploration of pre-implantation embryos. Intriguingly, human and mouse cells rely on different signaling and epigenetic pathways, and it remains a mystery why this variation exists. In this review, we will summarize the chromatin rearrangements in early embryonic development, drawing from genomic data from in vitro cell lines, and human and mouse embryos.

Ordered Intracellular Reca-Dna Assemblies

2000 ◽  
Vol 6 (S2) ◽  
pp. 860-861
Author(s):  
S. G. Wolf ◽  
S. Levin-Zaidman ◽  
D. Frenkiel-Krispin ◽  
E. Shimoni ◽  
I. Sabanay ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Electron Micrographs ◽  
Reca Protein ◽  
Sos Response ◽  
Structural Features ◽  
Wild Type ◽  
E Coli ◽  
Dna Damaging Agents

The inducible SOS response increases the ability of bacteria to cope with DNA damage through various DNA repair processes in which the RecA protein plays a central role. We find that induction of the SOS system in wild-type E. coli bacteria results in fast and massive intracellular coaggregation of RecA and DNA into lateral assemblies, which comprise substantial portions of both the cellular RecA and the DNA complement. The structural features of the coaggregates and their relation to in-vitro RecA-DNA are consistent with the possibility that the intracellular assemblies represent a functional entity in which RecA-mediated DNA repair and protection activities occur.Bacterial chromatin is demarcated in electron micrographs of metabolically active cells as amorphous ribosome-free spaces that are irregularly spread over the cytoplasm (Fig. A). Wild-type E. coli cells exposed to DNA-damaging agents that induce the SOS response reveal a strikingly different morphology (Fig. B).

Nanostructured biofunctionalized polyurethanes for applications in regenerative medicine

2012 ◽  
Vol 1417 ◽  
Author(s):  
Sebastian Kruss ◽  
Tobias Wolfram
Keyword(s):  
Electron Microscopy ◽  
Surface Engineering ◽  
Au Nanoparticles ◽  
Structural Features ◽  
Cellular Adhesion ◽  
Cellular Interactions ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Adsorption Processes

ABSTRACTPolyurethane (PU) materials are used in a wide variety of implantable devices and technologies, e.g. stents, breast augmentation, nose surgery and bladder reconstruction. Despite the excellent chemical control for manufacturing bulk materials and the good biocompatibility, a major challenge remains interfacing of PU with biological environments. A chemically controlled surface engineering approach could improve desired protein adsorption processes and cellular interactions within different tissues, preventing uncontrolled events of the implant especially in early stages shortly after surgical procedures.To gain better control over the PU surfaces we polymerized different bulk PU materials and developed a transfer-nanolithography technique to deposit inorganic Au-nanoparticles with defined structural features on the PU surface. Different nanoparticle patterns were transferred and analyzed by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). Topographical features of PU substrates were investigated by atomic force microscopy (AFM). Transferred Au-nanoparticles showed high stability on PU substrates even under extreme sonication conditions. In a final step, those nanoparticles were functionalized with peptides to facilitate cellular adhesion under physiologically relevant conditions. As proof of concept, rat embryonic fibroblast cells were cultured on a peptide functionalized PU interface and investigated by SEM.In conclusion, we developed a versatile method to prepare nanostructured and biofunctionalized PUs. These PUs showed good stability characteristics and in vitro biocompatibility in cell culture assays.

Electron-Microscopic Observations of Polyoma Virus-Transformed Mouse Cells Treated with Specific Immune Serum

1970 ◽  
Vol 7 (3) ◽  
pp. 711-718
Author(s):  
G. NEGRONI ◽  
RITA TILLY
Keyword(s):  
Electron Microscopy ◽  
Immune Serum ◽  
Polyoma Virus ◽  
Malignant Cells ◽  
Serum Complement ◽  
Cell Organelles ◽  
Electron Microscopic ◽  
Mouse Cells ◽  
Pig Serum

Transformed, non-malignant cells from a polyoma virus-induced mouse fibrosarcoma were treated with immune serum raised in isologous mice, and fresh guinea-pig serum (complement). Electron microscopy showed that reduction in cell viability in vitro was associated with damage to cell membranes. The extravasated cell organelles showed only minimal changes.

scholarly journals EVALUATION OF THE GLYCOGENOLYTIC EFFECT OF α-AMYLASE USING RADIOAUTOGRAPHY AND ELECTRON MICROSCOPY

1966 ◽  
Vol 14 (12) ◽  
pp. 898-906 ◽  
Author(s):  
A. COIMBRA
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Glycogen Synthesis ◽  
Paraffin Sections ◽  
Tissue Slices ◽  
Enzyme Preparations ◽  
Glycogenolytic Effect ◽  
Made In

The effectiveness of crystalline α-amylase and saliva in hydrolyzing newly formed glycogen in liver and muscle was examined. Glycogen synthesis was induced by the administration of H3-glucose to fasting rats or by the incubation of tissue slices in a medium containing H3-glucose. Paraffin sections of Rossman-fixed tissues or small pieces of liver fixed in glutaraldehyde and subsequently postosmicated and embedded in Epon were then enzymatically digested. Grain counts were made in radioautographs of treated and untreated materials, and the amount of radioactivity removed by the digestion was used to assess the efficiency of the enzymes in hydrolyzing glycogen. Crystalline α-amylase hydrolyzed almost completely newly formed glycogen in liver and muscle. Saliva removed the glycogen that was synthesized in vivo, but it was less effective in hydrolyzing glycogen synthesized in vitro. Electron micrographs of digested liver cells confirmed the radioautographic findings on the effectiveness of the enzyme preparations.

scholarly journals Herpes simplex viruses type 1 and 2 photoinactivated in the presence of methylene blue transform human and mouse cells in vitro

2017 ◽  
Vol 61 (03) ◽  
pp. 308-315 ◽  
Author(s):  
M. MICHÚTOVÁ ◽  
V. MRÁZOVÁ ◽  
M. KÚDELOVÁ ◽  
M. SMOLINSKÁ ◽  
M. ŠUPOLIKOVÁ ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Herpes Simplex ◽  
Herpes Simplex Viruses ◽  
Mouse Cells ◽  
Human And Mouse

scholarly journals Motor domain phosphorylation and regulation of the Drosophila kinesin 13, KLP10A

2009 ◽  
Vol 186 (4) ◽  
pp. 481-490 ◽  
Author(s):  
Vito Mennella ◽  
Dong-Yan Tan ◽  
Daniel W. Buster ◽  
Ana B. Asenjo ◽  
Uttama Rath ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Molecular Dynamics ◽  
Drosophila Melanogaster ◽  
Structural Features ◽  
Motor Domain ◽  
Α Helix ◽  
Dynamics Simulations

Microtubule (MT)-destabilizing kinesin 13s perform fundamental roles throughout the cell cycle. In this study, we show that the Drosophila melanogaster kinesin 13, KLP10A, is phosphorylated in vivo at a conserved serine (S573) positioned within the α-helix 5 of the motor domain. In vitro, a phosphomimic KLP10A S573E mutant displays a reduced capacity to depolymerize MTs but normal affinity for the MT lattice. In cells, replacement of endogenous KLP10A with KLP10A S573E dampens MT plus end dynamics throughout the cell cycle, whereas a nonphosphorylatable S573A mutant apparently enhances activity during mitosis. Electron microscopy suggests that KLP10A S573 phosphorylation alters its association with the MT lattice, whereas molecular dynamics simulations reveal how KLP10A phosphorylation can alter the kinesin–MT interface without changing important structural features within the motor’s core. Finally, we identify casein kinase 1α as a possible candidate for KLP10A phosphorylation. We propose a model in which phosphorylation of the KLP10A motor domain provides a regulatory switch controlling the time and place of MT depolymerization.

scholarly journals The POU Transcription Factor Oct-1 Represses Virus-Induced Interferon A Gene Expression

2005 ◽  
Vol 25 (19) ◽  
pp. 8717-8731 ◽  
Author(s):  
Thibault Mesplède ◽  
Marie-Laure Island ◽  
Nicolas Christeff ◽  
Fahrettin Petek ◽  
Janine Doly ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Infection ◽  
Regulatory Element ◽  
Adaptive Immune ◽  
Mouse Cells ◽  
Immune System Regulation ◽  
Human And Mouse ◽  
Control Of Expression

ABSTRACT Alpha interferon (IFN-α) and IFN-β are able to interfere with viral infection. They exert a vast array of biologic functions, including growth arrest, cell differentiation, and immune system regulation. This regulation extends from innate immunity to cellular and humoral adaptive immune responses. A strict control of expression is needed to prevent detrimental effects of unregulated IFN. Multiple IFN-A subtypes are coordinately induced in human and mouse cells infected by virus and exhibit differences in expression of their individual mRNAs. We demonstrated that the weakly expressed IFN-A11 gene is negatively regulated after viral infection, due to a distal negative regulatory element, binding homeoprotein pituitary homeobox 1 (Pitx1). Here we show that the POU protein Oct-1 binds in vitro and in vivo to the IFN-A11 promoter and represses IFN-A expression upon interferon regulatory factor overexpression. Furthermore, we show that Oct-1-deficient MEFs exhibit increased in vivo IFN-A gene expression and increased antiviral activity. Finally, the IFN-A expression pattern is modified in Oct-1-deficient MEFs. The broad representation of effective and potent octamer-like sequences within IFN-A promoters suggests an important role for Oct-1 in IFN-A regulation.

scholarly journals Equine lung decellularization: a potential approach for in vitro modeling the role of the extracellular matrix in asthma

2018 ◽  
Vol 9 ◽  
pp. 204173141881016 ◽  
Author(s):  
Renata Kelly da Palma ◽  
Paula Fratini ◽  
Gustavo Sá Schiavo Matias ◽  
Andressa Daronco Cereta ◽  
Leticia Lopes Guimarães ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Extracellular Matrix ◽  
Sodium Dodecyl ◽  
Treatment Strategies ◽  
Lung Compliance ◽  
Collagen I ◽  
The Future ◽  
Scanning Electron

Contrary to conventional research animals, horses naturally develop asthma, a disease in which the extracellular matrix of the lung plays a significant role. Hence, the horse lung extracellular matrix appears to be an ideal candidate model for in vitro studying the mechanisms and potential treatments for asthma. However, so far, such model to study cell–extracellular matrix interactions in asthma has not been developed. The aim of this study was to establish a protocol for equine lung decellularization that maintains the architecture of the extracellular matrix and could be used in the future as an in vitro model for therapeutic treatment in asthma. For this the equine lungs were decellularized by sodium dodecyl sulfate detergent perfusion at constant gravitational pressure of 30 cmH2O. Lung scaffolds were assessed by immunohistochemistry (collagen I, III, IV, laminin, and fibronectin), scanning electron microscopy, and DNA quantification. Their mechanical property was assessed by measuring lung compliance using the super-syringe technique. The optimized protocol of lung equine decellularization was effective to remove cells (19.8 ng/mg) and to preserve collagen I, III, IV, laminin, and fibronectin. Moreover, scanning electron microscopy analysis demonstrated maintained microscopic lung structures. The decellularized lungs presented lower compliance compared to native lung. In conclusion we described a reproducible decellularization protocol that can produce an acellular equine lung feasible for the future development of novel treatment strategies in asthma.

scholarly journals Efficient lentiviral transduction of different human and mouse cells

2018 ◽  
Author(s):  
Gang Zhang ◽  
Taihua Wang
Keyword(s):  
Cell Lines ◽  
Human Cell ◽  
Efficient Method ◽  
Genetic Research ◽  
Human Cell Lines ◽  
Primary Cells ◽  
Lentiviral Transduction ◽  
Mouse Cells ◽  
Human And Mouse

AbstractBackgroundLentiviral vectors (LVs) allowing efficient establishment of stable transgene overexpression mammalian and human cell lines are invaluable tools for genetic research. Currently, although LV transductions are broadly adopted, they are often limited due to their low titers for efficient transduction.ResultsHere, we described a set of optimized, efficient techniques, which could produce sufficiently high LV titers, and, provide efficient transduction of cells. According to these optimizations, most of the mammalian and human cells, both primary cells and cell lines, could be transduced successfully with high levels of transgene stable expression, including both constitutive and induced expressions.ConclusionsOur data demonstrated the highly usefulness of our optimized methods. Therefore, this study provided an efficient method for most of LV transduction experiments in vitro.

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