The Disposition of Proteinpoly-Saccharide in the Epiphysial Plate Cartilage of the Young Rabbit

1970 ◽  
Vol 6 (3) ◽  
pp. 843-864
Author(s):  
J. W. SMITH
Keyword(s):  
Uranyl Acetate ◽  
Bismuth Nitrate ◽  
Young Rabbit ◽  
Proliferative Zone ◽  
Attachment Sites ◽  
Central Regions ◽  
The Matrix ◽  
And Function ◽  
Initial Mineral ◽  
Positively Charged

Although acidic bismuth nitrate stains the polysaccharide in the unfixed bovine epiphysial plate, it fails to do so in that of the rabbit. After fixation in glutaraldehyde, however, Araldite sections stained with bismuth nitrate exhibit 3-nm spots which are interpreted as polysaccharide chains in coiled conformation. In the matrix of the proliferative zone, and in the large Golgi vesicles of the associated chondrocytes, the polysaccharide spots are arranged in closely packed groups. Lead citrate and uranyl acetate staining shows the non-fibrillar material in these situations as a continuous network of particles. The centre of each particle is translucent, and double staining with phosphotungstic acid and bismuth indicates that these central regions contain the groups of polysaccharide spots. It is suggested that in the unfixed tissue bismuth binding is prevented by screening of the polysaccharide sulphates by positively charged non-collagenous protein, and that fixation, by precipitating this protein as a network around groups of proteinpolysaccharide molecules, frees the sulphate groups to react with bismuth. Proteinpolysaccharide molecules appear to be tangentially attached to each period of the small collagen fibrils of the matrix. Fixation precipitation of the associated protein tends to aggregate these molecules into groups which are often somewhat eccentric to their original attachment sites, and consequently the fibrillar attachment of proteinpolysaccharide usually appears to be rather irregular. In the zone of early calcification single mineral crystals are associated with dense bodies of unknown nature and function. Many are also associated with short linear rows of polysaccharide spots. This and the similarity in the lengths of the two structures suggest that initial mineral crystals may grow along a proteinpolysaccharide molecule from one end to the other. Absence of polysaccharide spots in relation to crystal clusters suggest that these clusters are formed as a result of the seeding effect of the initial single crystals.

The Distribution of the Protein-Polysaccharide Complex in the Nucleus Pulposus Matrix in Young Rabbits

1968 ◽  
Vol 3 (1) ◽  
pp. 33-40
Author(s):  
J. W. SMITH ◽  
A. SERAFINI-FRACASSINI
Keyword(s):  
Nucleus Pulposus ◽  
Osmium Tetroxide ◽  
Lead Nitrate ◽  
Vitreous Body ◽  
Collagen Fibrils ◽  
Bismuth Nitrate ◽  
Young Rabbit ◽  
Native Collagen ◽  
The Matrix ◽  
Concentrated Solution

The distribution and relationship of the collagen and the proteinpolysaccharide complex in the extracellular matrix of the nucleus pulposus of the young rabbit were studied by electron microscopy. The polysaccharide was demonstrated by treatment of the tissue with either 0.5% bismuth nitrate at pH 2 or a mixture of equal volumes of 1% lead nitrate and 2% osmium tetroxide at pH 5. The protein part of the complex was observed in tissue fixed in osmium tetroxide at pH 7.2 and stained with 1% phosphotungstic acid. The collagen of the tissue was apparent in all preparations. The water-extracted proteinpolysaccharide was studied after coagulation of a concentrated solution in 0.5% bismuth nitrate, whereas the isolated fibrous fraction was examined by negative staining of sprayed material. Collagen is present in the intact tissues as native collagen fibrils of about 300 Å diameter, and as sheets, 4OO-Å thick, of parallel, separate, filaments of 50-60 Å diameter. Usually several such sheets lie close, and approximately parallel, to one another. After extraction of the proteinpolysaccharide from the tissue with water, all the collagenous components tend to aggregate into large native collagen fibrils. Some of the proteinpolysaccharide complex of the intact tissue is free in the matrix. The polysaccharide moiety is visualized as 270 Å particles, serially attached to a protein core in the form of beaded filaments about 40Å in diameter. The rest of the complex is attached to the sheets of collagen filaments in regular periodic zones which are 270 Å wide and centred 670 Å apart. None of the complex appears to be associated with the larger collagen fibrils. The staining reactions of the polysaccharides in several connective tissues are discussed and the relationships of the proteinpolysaccharide complexes to collagen in cartilage, the vitreous body and the nucleus pulposus are compared.

Structural similarity of ribosomes from E. coli and A. salina

1978 ◽  
Vol 36 (2) ◽  
pp. 242-243
Author(s):  
M. Boublik ◽  
R.M. Wydro ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Ribosomal Proteins ◽  
Direct Evidence ◽  
Structural Similarity ◽  
Carbon Support ◽  
Artemia Salina ◽  
Uranyl Acetate ◽  
Biological Assays ◽  
E Coli ◽  
And Function ◽  
Fine Carbon

Ribosomes are ribonucleoprotein particles necessary for processing the genetic information of mRNA into proteins. Analogy in composition and function of ribosomes from diverse species, established by biochemical and biological assays, implies their structural similarity. Direct evidence obtained by electron microscopy seems to be of increasing relevance in understanding the structure of ribosomes and the mechanism of their role in protein synthesis.The extent of the structural homology between prokaryotic and eukaryotic ribosomes has been studied on ribosomes of Escherichia coli (E.c.) and Artemia salina (A.s.). Despite the established differences in size and in the amount and proportion of ribosomal proteins and RNAs both types of ribosomes show an overall similarity. The monosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) appear in the electron micrographs as round particles with a diameter of approximately 225Å for the 70S E.c. (Fig. 1) and 260Å for the 80S A.s. monosome (Fig. 2).

Structural Role of rRNAs on the Ribosomal Subunits from E. Coli by Scanning Transmission Electron Microscopy

1981 ◽  
Vol 39 ◽  
pp. 424-425
Author(s):  
M. Boublik ◽  
N. Robakis ◽  
J.S. Wall
Keyword(s):  
Three Dimensional ◽  
Uranyl Acetate ◽  
Dimensional Structure ◽  
Electron Microscopic ◽  
Ribosomal Subunits ◽  
E Coli ◽  
Freeze Dried ◽  
16S Rna ◽  
Scanning Transmission ◽  
And Function

The three-dimensional structure and function of biological supramolecular complexes are, in general, determined and stabilized by conformation and interactions of their macromolecular components. In the case of ribosomes, it has been suggested that one of the functions of ribosomal RNAs is to act as a scaffold maintaining the shape of the ribosomal subunits. In order to investigate this question, we have conducted a comparative TEM and STEM study of the structure of the small 30S subunit of E. coli and its 16S RNA.The conventional electron microscopic imaging of nucleic acids is performed by spreading them in the presence of protein or detergent; the particles are contrasted by electron dense solution (uranyl acetate) or by shadowing with metal (tungsten). By using the STEM on freeze-dried specimens we have avoided the shearing forces of the spreading, and minimized both the collapse of rRNA due to air drying and the loss of resolution due to staining or shadowing. Figure 1, is a conventional (TEM) electron micrograph of 30S E. coli subunits contrasted with uranyl acetate.

scholarly journals Proteomic profiling of the mitochondrial ribosome identifies Atp25 as a composite mitochondrial precursor protein

2016 ◽  
Vol 27 (20) ◽  
pp. 3031-3039 ◽  
Author(s):  
Michael W. Woellhaf ◽  
Frederik Sommer ◽  
Michael Schroda ◽  
Johannes M. Herrmann
Keyword(s):  
Precursor Protein ◽  
Ribosomal Biogenesis ◽  
Proteomic Profiling ◽  
Mitochondrial Translation ◽  
Bacterial Ribosome ◽  
Mitochondrial Ribosome ◽  
Translation Apparatus ◽  
The Matrix ◽  
Processing Peptidase ◽  
And Function

Whereas the structure and function of cytosolic ribosomes are well characterized, we only have a limited understanding of the mitochondrial translation apparatus. Using SILAC-based proteomic profiling, we identified 13 proteins that cofractionated with the mitochondrial ribosome, most of which play a role in translation or ribosomal biogenesis. One of these proteins is a homologue of the bacterial ribosome-silencing factor (Rsf). This protein is generated from the composite precursor protein Atp25 upon internal cleavage by the matrix processing peptidase MPP, and in this respect, it differs from all other characterized mitochondrial proteins of baker’s yeast. We observed that cytosolic expression of Rsf, but not of noncleaved Atp25 protein, is toxic. Our results suggest that eukaryotic cells face the challenge of avoiding negative interference from the biogenesis of their two distinct translation machineries.

scholarly journals Proteolytic Events of Wound-Healing — Coordinated Interactions Among Matrix Metalloproteinases (MMPs), Integrins, and Extracellular Matrix Molecules

2001 ◽  
Vol 12 (5) ◽  
pp. 373-398 ◽  
Author(s):  
Bjorn Steffensen ◽  
Lari Häkkinen ◽  
Hannu Larjava
Keyword(s):  
Extracellular Matrix ◽  
Wound Healing ◽  
Matrix Metalloproteinases ◽  
Wound Repair ◽  
Enzyme Activation ◽  
Processing Enzymes ◽  
The Matrix ◽  
Signaling Receptors ◽  
State Of Rest ◽  
And Function

During wound-healing, cells are required to migrate rapidly into the wound site via a proteolytically generated pathway in the provisional matrix, to produce new extracellular matrix, and, subsequently, to remodel the newly formed tissue matrix during the maturation phase. Two classes of molecules cooperate closely to achieve this goal, namely, the matrix adhesion and signaling receptors, the integrins, and matrix-degrading and -processing enzymes, the matrix metalloproteinases (MMPs). There is now substantial experimental evidence that blocking key molecules of either group will prevent or seriously delay wound-healing. It has been known for some time now that cell adhesion by means of the integrins regulates the expression of MMPs. In addition, certain MMPs can bind to integrins or other receptors on the cell surface involved in enzyme activation, thereby providing a mechanism for localized matrix degradation. By proteolytically modifying the existing matrix molecules, the MMPs can then induce changes in cell behavior and function from a state of rest to migration. During wound repair, the expression of integrins and MMPs is simultaneously up-regulated. This review will focus on those aspects of the extensive knowledge of fibroblast and keratinocyte MMPs and integrins in biological processes that relate to wound-healing.

DNA-RNA complexes that might represent transient attachment sites of nuclear DNA to the matrix

1990 ◽  
Vol 95 (4) ◽  
pp. 667-674
Author(s):  
C. Patriotis ◽  
M. Andreeva ◽  
M. Pascaleva ◽  
V. Ivanov ◽  
L. Djondjurov
Keyword(s):  
Dna Sequences ◽  
Nuclear Dna ◽  
Rna Polymerase Iii ◽  
Erythroid Differentiation ◽  
Rnase H ◽  
Dna And Rna ◽  
Attachment Sites ◽  
The Matrix ◽  
Exo Iii ◽  
Rna Complexes

In this study we describe DNA-RNA complexes in matrix DNA of Friend cells. The presence of such unusual structures is confirmed by the following evidence. When a preparation of matrix DNA is electrophoresed in agarose an RNA component always migrates together with DNA. There should be a close interaction between DNA and RNA in such a preparation because the presence of the RNA component causes resistance of DNA to DNase I and Exo III. An intimate, hybrid-type association of part of the RNA component with DNA is indicated also by the fact that about 20% of this RNA is sensitive to RNase H. By specific inhibition of the RNA synthesis with alpha-amanitin and actinomycin D it was shown that the bulk of associated RNA is transcribed by RNA polymerase III. Hybridization experiments showed similarity between the DNA sequences isolated from the complexes and those from the base of dehistonized DNA loops obtained by high-salt extraction of nuclei. This observation suggests that the complexes might represent attachment sites of nuclear DNA to the matrix: possibly, the attachment is mediated via the RNA component. Experiments with induction of erythroid differentiation indicated that a profound reorganization of the nucleus, accompanying terminal differentiation, leads to a striking reduction in the number of complexes and thus in the number of attachment sites. This suggests that the complexes should function as transient attachment sites.

Quantitative polymorphism of tandem repeats as a method of epigenetic regulation of the of human cells response to oxidative stress

2020 ◽  
pp. 68-70
Author(s):  
Н.Н. Вейко ◽  
Е.С. Ершова ◽  
М.С. Конькова ◽  
Е.М. Малиновская ◽  
С.В. Костюк
Keyword(s):  
Adaptive Response ◽  
Spatial Organization ◽  
Tandem Repeats ◽  
Spatial Configuration ◽  
Human Cells ◽  
Central Regions ◽  
Schizophrenic Patients ◽  
Response To Stress ◽  
Cell Genome ◽  
And Function

Пространственная организация хроматина важна для нормального функционирования клетки. На архитектуру ядра влияют размеры отдельных фрагментов генома, которые коррелируют с числом копий этих фрагментов. Перемещение локусов 1q12 от поверхности ядра в центральные области является ключевой стадией адаптивного ответа клетки на стресс. Мы предположили, что размер локусов 1q12, который коррелирует с содержанием повтора f-SatIII, может влиять на перемещение этих участков хроматина в ядре. Методом FISH на выделенных лимфоцитах показали, что в контроле локусы 1q12 расположены вблизи поверхности ядра, в ядрах лимфоцитов больных шизофренией (БШ) и облученных контрольных клеток локусы 1q12 расположены в центральных районах ядра. Длительное культивирование облученных лимфоцитов сопровождалось гибелью клеток, и снижением содержания f-SatIII в ДНК. Очевидно, что погибали клетки с большим размером 1q12 (много f-SatIII), обогащая популяцию клетками с низким содержанием f-SatIII. В клетках БШ и в облученных клетках мы обнаружили повышение уровня РНК SATIII. Размеры гетерохроматина 1q12 в клетках человека могут влиять на процессы пролиферации и ответа клетки на стресс. Количественный полиморфизм тандемных повторов генома - один из эпигенетических механизмов регуляции ответа клеток на окислительный стресс. The spatial organization of chromatin is important for the normal functioning of the cell. Genome repeat cluster sizes can affect the chromatin spatial configuration and function. The 1q12 heterochromatin loci movement from the periphery to the center of the nucleus is the cells’ universal response to various types of stress. We hypothesized that a large 1q12 domain could affect chromatin movement, thereby inhibiting adaptive response (AR). Using the FISH method, we shown that in the control, 1q12 loci are located near the surface of the nucleus; in the lymphocyte nuclei of schizophrenic patients and irradiated control cells, 1q12 loci are located in the central regions of the nucleus. During prolonged cultivation, the irradiated cells with a large Large f-SatIII amount die and the population is enriched with the cells with low f-SatIII content. In intact SZ patients’ lymphocytes and in irradiated cells we found an increase in SATIII RNA levels. The size of heterochromatin 1q12 loci in human cells can affect to the proliferation and cells’ adaptive response to stress. Quantitative polymorphism of tandem genome repeats is one of the epigenetic mechanisms of genome expression’s regulation.

Microtubules and their protofilaments in the flagellum of an insect spermatozoon

1990 ◽  
Vol 95 (2) ◽  
pp. 207-217
Author(s):  
B.A. Afzelius ◽  
P.L. Bellon ◽  
S. Lanzavecchia
Keyword(s):  
Protein Denaturation ◽  
Uranyl Acetate ◽  
Photographic Method ◽  
Microtubule Associated Proteins ◽  
Attachment Sites ◽  
Stick Insects ◽  
Computer Aided Analysis ◽  
Computer Aided ◽  
Associated Proteins ◽  
Dynein Arms

Spermatozoa of stick insects have nine accessory tubules, which surround the nine outer microtubular doublets and the two inner microtubular singlets. When fixed in a fixative that was designed to minimize protein denaturation (glutaraldehyde and tannic acid, no osmium post-fixation but block staining with uranyl acetate in water) the accessory tubules were seen to contain 17 protofilaments of the same type as those in the 9 + 2 microtubular doublets and singlets. The protofilaments in accessory tubules and other microtubules were roughly triangular. When studied by Markham's photographic method a somewhat different tilt of the two longer sides was seen; this makes it possible to distinguish a polarity in the microtubules, i.e. to differentiate between a microtubule that is viewed from its (-)end to its (+)end from one that is viewed in the opposite direction. The dynein arms of the doublets can be used as an independent type of marker for the polarity. In a computer-aided analysis of the fine structure of the tail axoneme, the A-subtubules of the outer doublets were seen to be not quite equidistant; rather, there were somewhat widened electron-dense interspaces in the ring of protofilaments in four places. The locations of these widened interspaces coincide with the attachment sites for the spoke, the inner dynein arm, the outer dynein arm, and the intertubular material. It is tentatively concluded that proteins of these structures, and perhaps also other microtubule-associated proteins, may be anchored deep within the wall of a microtubule rather than just superficially along it.

scholarly journals Indirect flight muscles in Drosophila melanogaster as a tractable model to study muscle development and disease

2020 ◽  
Vol 64 (1-2-3) ◽  
pp. 167-173
Author(s):  
Saroj Jawkar ◽  
Upendra Nongthomba
Keyword(s):  
Drosophila Melanogaster ◽  
Muscle Development ◽  
Myoblast Fusion ◽  
Successful Development ◽  
Adult Muscle ◽  
Attachment Sites ◽  
Flight Muscles ◽  
And Function

Myogenesis is a complex multifactorial process leading to the formation of the adult muscle. An amalgamation of autonomous processes including myoblast fusion and myofibrillogenesis, as well as non-autonomous processes, such as innervations from neurons and precise connections with attachment sites, are responsible for successful development and function of muscles. In this review, we describe the development of the indirect flight muscles (IFMs) in Drosophila melanogaster, and highlight the use of the IFMs as a model for studying muscle development and disease, based on recent studies on the development and function of IFMs.

scholarly journals Structure of the H1 C-terminal domain and function in chromatin condensationThis paper is one of a selection of papers published in a Special Issue entitled 31st Annual International Asilomar Chromatin and Chromosomes Conference, and has undergone the Journal’s usual peer review process.

2011 ◽  
Vol 89 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Tamara L. Caterino ◽  
Jeffrey J. Hayes
Keyword(s):  
Review Process ◽  
Peer Review Process ◽  
Special Issue ◽  
Direct Role ◽  
Linker Histones ◽  
Terminal Domain ◽  
Chromatin Folding ◽  
And Function ◽  
Positively Charged ◽  
Selection Of

Linker histones are multifunctional proteins that are involved in a myriad of processes ranging from stabilizing the folding and condensation of chromatin to playing a direct role in regulating gene expression. However, how this class of enigmatic proteins binds in chromatin and accomplishes these functions remains unclear. Here we review data regarding the H1 structure and function in chromatin, with special emphasis on the C-terminal domain (CTD), which typically encompasses approximately half of the mass of the linker histone and includes a large excess of positively charged residues. Owing to its amino acid composition, the CTD was previously proposed to function in chromatin as an unstructured polycation. However, structural studies have shown that the CTD adopts detectable secondary structure when interacting with DNA and macromolecular crowding agents. We describe classic and recent experiments defining the function of this domain in chromatin folding and emerging data indicating that the function of this protein may be linked to intrinsic disorder.

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