Evidence for Erythrocyte-Specific Histone Modification and Structural Changes in Chromatin During Goose Erythrocyte Maturation

1974 ◽  
Vol 15 (3) ◽  
pp. 659-677
Author(s):  
K. BRASCH ◽  
G. H. M. ADAMS ◽  
J. M. NEELIN
Keyword(s):  
Structural Changes ◽  
Inverse Correlation ◽  
Phosphate Content ◽  
Progressive Decrease ◽  
Isolated Nuclei ◽  
Goose Erythrocyte ◽  
Immature Cells ◽  
Gradual Transformation ◽  
Specific Agent ◽  
Relative Case

Regenerating blood of geese suffering from phenylhydrazine anaemia was separated into ‘mature’ and ‘immature’ cell populations by centrifugation through a barrier of BSA. Socalled ‘mature cells’ consisted of mainly mature erythrocytes and ‘immature cells’ included two-thirds polychromatic and younger erythroblasts. Histone proteins, dissociated from isolated nuclei of both populations of cells by sequential extraction with citric acid and hydrochloric acid, were compared and the nuclei were examined by electron microscopy. Erythrocyte-specific histone V (f2c) was fully extracted from immature nuclei at pH 2.0, but only partially extracted at the same pH from mature nuclei. An inverse correlation was found between relative case of extraction and alkali-labile phosphate content of purified samples of histone V. The more readily dissociated fraction of histone V from immature nuclei had a higher phosphate content than the less readily dissociated component V from immature and mature nuclei. Chromatin in mature nuclei became tightly congealed after only partial extraction of histone V at pH 2.0, but loosened visibly after subsequent full extraction of histone V at pH 1.8. In contrast, chromatin in immature nuclei never became totally congealed. Histone V may be a tissue-specific agent involved in packing of DNA within chromatin fibrils. During erythropoiesis, progressive decrease of histone V phosphate may lead to its increased binding affinity for chromatin and thus to the gradual transformation of the erythrocyte genome into a permanently repressed state.

scholarly journals Biochemically distinct cohesin complexes mediate positioned loops between CTCF sites and dynamic loops within chromatin domains

2021 ◽  
Author(s):  
Yu Liu ◽  
Job Dekker
Keyword(s):  
Sister Chromatid ◽  
Structural Changes ◽  
Experimental Approach ◽  
Cohesin Complex ◽  
Genomic Context ◽  
Experimental Conditions ◽  
Chromatin Domains ◽  
Isolated Nuclei ◽  
Sister Chromatids ◽  
Chromatid Cohesion

The ring-like cohesin complex mediates sister chromatid cohesion by encircling pairs of sister chromatids. Cohesin also extrudes loops along chromatids. Whether the two activities involve similar mechanisms of DNA engagement is not known. We implemented an experimental approach based on isolated nuclei carrying engineered cleavable RAD21 proteins to precisely control cohesin ring integrity so that its role in chromatin looping could be studied under defined experimental conditions. This approach allowed us to identify cohesin complexes with distinct biochemical, and possibly structural properties, that mediate different sets of chromatin loops. When RAD21 is cleaved and the cohesin ring is opened, cohesin complexes at CTCF sites are released from DNA and loops at these elements are lost. In contrast, cohesin-dependent loops within chromatin domains and that are not anchored at CTCF sites are more resistant to RAD21 cleavage. The results show that the cohesin complex mediates loops in different ways depending on genomic context and suggests that it undergoes structural changes as it dynamically extrudes and encounters CTCF sites.

Effect of ureteral blockade on renal blood flow and urinary concentrating ability

1963 ◽  
Vol 205 (2) ◽  
pp. 286-292 ◽  
Author(s):  
Ewald E. Selkurt
Keyword(s):  
Blood Flow ◽  
Glomerular Filtration ◽  
Renal Blood Flow ◽  
Inverse Correlation ◽  
Progressive Decrease ◽  
Vascular Perfusion ◽  
Saline Loading ◽  
Vasa Recta ◽  
The Face ◽  
Urinary Concentrating Ability

Complete blockade of the ureter in dogs subjected to saline loading (0.85–10.0% NaCl) resulted in an increase in total renal blood during the period of blockade which appeared to be related to the antecedent diuresis and increment in ureteral pressure. This was accompanied by a progressive decrease in extraction of para-aminohippurate (PAH) and a greater decrease in creatinine extraction. The change in Epah showed a close inverse correlation to the change in renal blood flow (RBF). This afforded a possible explanation for the increment in RBF, for the increased perfusion of vascular circuits of the A-V communicating type would account for such a correlation. Evidence was supplied which suggested that such pathways involved the medullary vascular circuits. This was based on the observation that the concentrating ability of the kidney was impaired by the period of occlusion. The most likely mechanism for this would be maintained (or increased) vascular perfusion of the vasa recta system, in the face of markedly curtailed glomerular filtration, conditions resulting from ureteral blockade.

scholarly journals Evidence for a Relationship between Body Mass and Energy Metabolism in the Human Brain

2010 ◽  
Vol 30 (7) ◽  
pp. 1403-1410 ◽  
Author(s):  
André Schmoller ◽  
Torben Hass ◽  
Olga Strugovshchikova ◽  
Uwe H Melchert ◽  
Harald G Scholand-Engler ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Mass ◽  
Inverse Correlation ◽  
High Energy ◽  
Weight Regulation ◽  
Phosphate Content ◽  
Body Weight Regulation ◽  
High Energy Phosphate ◽  
Atp Metabolism ◽  
The Brain

Cerebral energy metabolism has been suggested to have an important function in body weight regulation. We therefore examined whether there is a relationship between body mass and adenosine triphosphate (ATP) metabolism in the human brain. On the basis of our earlier findings indicating a neuroprotective preferential energy supply of the brain, as compared with peripheral muscle on experimentally induced hypoglycemia, we examined whether this physiological response is preserved also in low-weight and obese participants. We included 45 healthy male subjects with a body mass index (BMI) ranging from 17 to 44 kg/m2. Each participant underwent a hypoglycemic glucose-clamp intervention, and the ATP metabolism, that is, the content of high-energy phosphates phosphocreatine (PCr) and ATP, was measured repeatedly by 31phosphor magnetic resonance spectroscopy (31P-MRS) in the cerebral cortex and skeletal muscle. Results show an inverse correlation between BMI and high-energy phosphate content in the brain ( P<0.01), whereas there was no such relationship found between skeletal muscle and BMI. The hypoglycemic clamp intervention did not affect the ATP metabolism in both tissues. Our data show an inverse correlation between BMI and cerebral high-energy phosphate content in healthy humans, suggesting a close relationship between energetic supply of the brain and body weight regulation.

scholarly journals The AIIB and China-ASEAN Relations: Shaping a New North-South Paradigm

2018 ◽  
Vol 04 (01) ◽  
pp. 95-121 ◽  
Author(s):  
Olga Daksueva ◽  
Serafettin Yilmaz
Keyword(s):  
Structural Changes ◽  
Asian Countries ◽  
Dyadic Relationship ◽  
Investment Bank ◽  
The Past ◽  
Political Implications ◽  
Northern Country ◽  
China’S Foreign Policy ◽  
Gradual Transformation ◽  
Intense Debate

The Asian Infrastructure Investment Bank (AIIB), one of the largest investment institutions in the world, was established in 2015. The launch of the China-initiated AIIB generated intense debate among scholars and politicians over the functions and potential economic and political implications of the institution. This paper aims to examine the AIIB from a normative perspective, investigating its role as a cursor for structural changes in China’s foreign policy conceptualization. It goes on to hypothesize that, over the past few years, there has been a gradual transformation in China’s relations with Southeast Asian countries, which indicates a shift from a traditional “South-South” model to a “North-South” model. It observes that as Beijing continues to promote its own brand of frameworks and institutions, the emerging North-South paradigm will likely be further emphasized, transforming China’s position vis-a-vis other nations and groupings. Nevertheless, China as an emerging Northern country will continue to experiment on and develop this new North-South interaction in a way that is distinct from the orthodox North-South dyadic relationship.

Phosphate content of goose erythrocyte histones

1970 ◽  
Vol 48 (1) ◽  
pp. 33-37 ◽  
Author(s):  
G. H. M. Adams ◽  
G. Vidali ◽  
J. M. Neelin
Keyword(s):  
Amino Acid ◽  
Complex Formation ◽  
Normal Blood ◽  
Phosphate Content ◽  
Specific Component ◽  
Histone Phosphorylation ◽  
Amino Acid Compositions ◽  
Goose Erythrocyte ◽  
Nuclear Phosphoprotein ◽  
Chromatographic Profiles

Although chromatographic profiles and amino acid compositions of erythrocyte histones from normal and regenerating goose blood did not differ, characteristic fractions from regenerating blood contained more alkali-labile phosphate than did their counterparts from normal blood. Furthermore, the phosphate content of the erythrocyte-specific component was appreciably greater than that of any other histone.The problem of distinguishing between contamination and valid histone phosphate is considered; complex formation between nuclear phosphoprotein and specific histone fractions could not be unequivocally eliminated. The pronounced phosphate levels in the erythrocyte-specific histone V are discussed in relation to the prospective roles of histone phosphorylation.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

Evaluation of single-electron movies of glutamine synthetase molecules

1983 ◽  
Vol 41 ◽  
pp. 280-281
Author(s):  
W. Kunath ◽  
E. Zeitler ◽  
M. Kessel
Keyword(s):  
Electron Microscope ◽  
Glutamine Synthetase ◽  
Electron Irradiation ◽  
Structural Damage ◽  
Structural Changes ◽  
Single Electron ◽  
Continuous Series ◽  
Digital Recording ◽  
Recording Device ◽  
Low Exposure

The features of digital recording of a continuous series (movie) of singleelectron TV frames are reported. The technique is used to investigate structural changes in negatively stained glutamine synthetase molecules (GS) during electron irradiation and, as an ultimate goal, to look for the molecules' “undamaged” structure, say, after a 1 e/Å2 dose.The TV frame of fig. la shows an image of 5 glutamine synthetase molecules exposed to 1/150 e/Å2. Every single electron is recorded as a unit signal in a 256 ×256 field. The extremely low exposure of a single TV frame as dictated by the single-electron recording device including the electron microscope requires accumulation of 150 TV frames into one frame (fig. lb) thus achieving a reasonable compromise between the conflicting aspects of exposure time per frame of 3 sec. vs. object drift of less than 1 Å, and exposure per frame of 1 e/Å2 vs. rate of structural damage.

Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk

1977 ◽  
Vol 35 ◽  
pp. 496-497
Author(s):  
K. Kovacs ◽  
E. Horvath ◽  
J. M. Bilbao ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Structural Changes ◽  
Tissue Injury ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Sequence Of Events ◽  
Pituitary Glands ◽  
Electrolytic Lesions ◽  
Ultrathin Sections

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.

Membrane Changes in Polymorphonuclear Leukocytes During Ionophore (A23187) - Induced Lysosomal Release

1977 ◽  
Vol 35 ◽  
pp. 482-483
Author(s):  
P.L. Moore ◽  
P.L. Sannes ◽  
H.L. Bank ◽  
S.S. Spicer
Keyword(s):  
Structural Changes ◽  
Calcium Release ◽  
Clear Understanding ◽  
Ionophore A23187 ◽  
Enzyme Release ◽  
Extracellular Medium ◽  
Pmn Leukocytes ◽  
Intracellular Ion Concentrations ◽  
Membrane Changes ◽  
Pmn Leukocyte

It is thought that calcium and/or magnesium may play important roles in polymorphonuclear (PMN) leukocyte functions such as chemotaxis, adhesion and phagocytosis. Yet, a clear understanding of the biological roles of these ions has awaited the development of techniques which permit a selective alteration of intracellular ion concentrations. Recently, treatment of cells with the ionophore A23187 has been used to alter intracellular divalent cation concentrations. This ionophore is a lipid soluble antibiotic produced by Streptomyces chartreusensis that complexes with both calcium and magnesium (3) and is believed to carry these ions across biological membranes (4). Biochemical investigations of human PMN leukocytes demonstrate that cells treated with A23187 and extracellular calcium release their lysosomal enzymes into the extracellular medium without rupturing and releasing their soluble cytoplasmic enzymes (5,6). The aim of the present study and and a companion report (7) was to investigate the structural changes that occur in leukocytes during ionophore-induced lysosomal enzyme release.

The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

1971 ◽  
Vol 29 ◽  
pp. 272-273
Author(s):  
Werner J. Niklowitz
Keyword(s):  
Electron Microscope ◽  
Structural Changes ◽  
Mossy Fiber ◽  
Toxic Metal ◽  
Staining Technique ◽  
Brain Structures ◽  
Oxidase Inhibitor ◽  
Fiber Layer ◽  
Hippocampal Tissue ◽  
Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

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