Molecular Mechanism and Structural Aspects of Transporter Associated with Antigen Processing Inhibition by the Cytomegalovirus Protein US6

Abstract BCR-mediated antigen processing occurs at immunologically relevant antigen concentrations and hinges on the trafficking of antigen-BCR (Ag-BCR) complexes to class II–containing multivesicular bodies (MVBs) termed MIICs. However, the molecular mechanism underlying the trafficking of Ag-BCR complexes to and within MIICs is not well understood. In contrast, the trafficking of the epidermal growth factor receptor (EGFR) to and within MVBs occurs via a well-characterized ubiquitin-dependent mechanism, which is blocked by acute inhibition of proteasome activity. Using a highly characterized antigen-specific model system, it was determined that the immunoglobulin heavy chain subunit of the IgM BCR of normal (ie, nontransformed) B cells is ubiquitinated. Moreover, acute inhibition of proteasome activity delays the formation of ubiquitinated ligand–BCR complexes, alters the intracellular trafficking of internalized Ag-BCR complexes, and selectively blocks the BCR-mediated processing and presentation of cognate antigen, without inhibiting the endocytosis, processing, and presentation of non–cognate antigen internalized by fluidphase endocytosis. These results demonstrate that the trafficking of Ag-BCR complexes to and within MVB-like antigen processing compartments occurs via a molecular mechanism with similarities to that used by the EGFR, and establishes the EGFR as a paradigm for the further analysis of Ag-BCR trafficking to and within MIICs.

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Transcriptomic analyses revealed the effect of Funneliformis mosseae on differentially expressed genes in Fusarium oxysporum

10.1101/2020.05.28.120873 ◽

2020 ◽

Author(s):

Xue-Qi Zhang ◽

Li Bai ◽

Na Guo ◽

Bai-Yan Cai

Keyword(s):

Molecular Mechanism ◽

Abc Transporter ◽

Root Rot ◽

Antigen Processing ◽

Rna Degradation ◽

Atp Binding ◽

Glycoside Hydrolase Family ◽

Continuous Cropping ◽

Experimental Basis ◽

Soybean Root

AbstractSoybean root rot is a typical soil-borne disease that severely affects the yield of soybean, and F. mosseae, the dominant strain of AMF in continuous cropping of soybean. The aim of this study was to providing an experimental basis for the study of the molecular mechanism underlying the alleviation of the obstacles associated with the continuous cropping of soybean by AMF. In this study, F. mosseae was inoculated in soil planted with soybean infected with F. oxysporum. The results showed that the incidence of soybean root rot was significantly reduced after inoculation with F. mosseae. The significantly upregulated genes encoded the ABC transporter, ATP-binding/permease protein and the ABC transporter, ATP-binding protein. The significantly downregulated genes encoded chitin-binding domain proteins; key enzymes involved in metabolic pathways such as glycolysis, including class II fructose-bisphosphate aldolase and NAD-dependent glyceraldehyde-3-phosphate dehydrogenase, glycoside hydrolase family 61 protein, which hydrolyse cellulose and hemicellulose; actin and other major components of the cytoskeleton. The DEGs were enriched in antigen processing and presentation, carbon fixation in photosynthetic organisms, glycolysis/gluconeogenesis, the MAPK signalling pathway, protein processing in the endoplasmic reticulum and RNA degradation. Inoculation with F. mosseae could promote the growth and development of soybean and improve disease resistance. This study provides an experimental basis for further research on the molecular mechanism underlying the alleviation of challenges associated with the continuous cropping of soybean by AMF.

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Structural aspects of osmoregulation in porphyra

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100082923 ◽

1978 ◽

Vol 36 (2) ◽

pp. 412-413

Author(s):

C. Wiencke ◽

A. Lauchli

Keyword(s):

Culture Medium ◽

Point Of View ◽

Chemical Fixation ◽

Cellular Organization ◽

Osmotic Adaptation ◽

Osmotic Balance ◽

Activity Of Enzymes ◽

Osmotic Agents ◽

Vacuolar System ◽

Structural Aspects

Osmoregulatory mechanisms in algae were investigated mainly from a physiological point of view (KAUSS 1977, HELLEBUST 1976). In Porphyra two osmotic agents, i. e. floridoside/isofloridoside (KAUSS 1968) and certain ions, such as K+ and Na+(EPPLEY et al. 1960) are considered for osmotic balance. Accumulations of ions (particularly Na+) in the cytoplasm during osmotic adaptation is improbable, because the activity of enzymes is generally inhibited by high ionic concentrations (FLOWERS et al. 1977).The cellular organization of Porphyra was studied with special emphasis on the development of the vacuolar system under different hyperosmotic conditions. Porphyra was cultivated at various strengths of the culture medium ASP 12 (PROVASOLI 1961) ranging from normal to 6 times concentrated (6x) culture medium. Por electron microscopy freeze fracturing was used (specimens fixed in 2% glutaraldehyde and incubated in 30% glycerol, preparation in a BALZERS BA 360 M apparatus), because chemical fixation gave poor results.

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Molecular Structure of the Outermost Cell Wall Component of Spirillum Serpens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079218 ◽

1977 ◽

Vol 35 ◽

pp. 342-343

Author(s):

Wah Chiu ◽

David Grano

Keyword(s):

Molecular Structure ◽

Cell Wall ◽

Outer Membrane ◽

Gel Electrophoresis ◽

Electron Microscopic Examination ◽

Electron Microscopic ◽

Cell Wall Component ◽

Protein Components ◽

Exposure Technique ◽

Structural Aspects

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.

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7-beam lattice images of (110) oriented Ge

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108593 ◽

1978 ◽

Vol 36 (1) ◽

pp. 290-291

Author(s):

J.R. Parsons ◽

C.W. Hoelke

Keyword(s):

Image Features ◽

Objective Lens ◽

Lattice Plane ◽

Lattice Image ◽

Crystalline Defects ◽

Transmission Electron ◽

Lattice Images ◽

Electron Microscopes ◽

Structural Aspects ◽

Beam Lattice

The direct imaging of a crystal lattice has intrigued electron microscopists for many years. What is of interest, of course, is the way in which defects perturb their atomic regularity. There are problems, however, when one wishes to relate aperiodic image features to structural aspects of crystalline defects. If the defect is inclined to the foil plane and if, as is the case with present 100 kV transmission electron microscopes, the objective lens is not perfect, then terminating fringes and fringe bending seen in the image cannot be related in a simple way to lattice plane geometry in the specimen (1).The purpose of the present work was to devise an experimental test which could be used to confirm, or not, the existence of a one-to-one correspondence between lattice image and specimen structure over the desired range of specimen spacings. Through a study of computed images the following test emerged.

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Structural aspects of tracheary element differentiation in suspension cultures of Zinnia elegans

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100155815 ◽

1989 ◽

Vol 47 ◽

pp. 768-769

Author(s):

C. H. Haigler ◽

A. W. Roberts

Keyword(s):

Tracheary Element ◽

Vesicle Fusion ◽

Zinnia Elegans ◽

Cellulose Synthesis ◽

Tracheary Elements ◽

Animal Cells ◽

Mesophyll Cells ◽

Fixation Techniques ◽

Localized Patterns ◽

Structural Aspects

Tracheary elements, the water-conducting cells in plants, are characterized by their reinforced walls that became thickened in localized patterns during differentiation (Fig. 1). The synthesis of this localized wall involves abundant secretion of Golgi vesicles that export preformed matrix polysaccharides and putative proteins involved in cellulose synthesis. Since the cells are not growing, some kind of endocytotic process must also occur. Many researchers have commented on where exocytosis occurs in relation to the thickenings (for example, see), but they based their interpretations on chemical fixation techniques that are not likely to provide reliable information about rapid processes such as vesicle fusion. We have used rapid freezing to more accurately assess patterns of vesicle fusion in tracheary elements. We have also determined the localization of calcium, which is known to regulate vesicle fusion in plant and animal cells.Mesophyll cells were obtained from immature first leaves of Zinnia elegans var. Envy (Park Seed Co., Greenwood, S.C.) and cultured as described previously with the following exceptions: (a) concentration of benzylaminopurine in the culture medium was reduced to 0.2 mg/l and myoinositol was eliminated; and (b) 1.75ml cultures were incubated in 22 x 90mm shell vials with 112rpm rotary shaking. Cells that were actively involved in differentiation were harvested and frozen in solidifying Freon as described previously. Fractures occurred preferentially at the cell/planchet interface, which allowed us to find some excellently-preserved cells in the replicas. Other differentiating cells were incubated for 20-30 min in 10(μM CTC (Sigma), an antibiotic that fluoresces in the presence of membrane-sequestered calcium. They were observed in an Olympus BH-2 microscope equipped for epi-fluorescence (violet filter package and additional Zeiss KP560 barrier filter to block chlorophyll autofluorescence).

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Biophysical and Structural Aspects of Bioenergetics

10.1039/9781847552532 ◽

2007 ◽

Cited By ~ 1

Keyword(s):

Structural Aspects

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Structural Aspects of Phonological Development

Language Speech and Hearing Services in Schools ◽

10.1044/0161-1461.1901.05 ◽

1988 ◽

Vol 19 (1) ◽

pp. 5-16 ◽

Cited By ~ 5

Author(s):

Karen E. Pollock ◽

Richard G. Schwartz

Keyword(s):

Clinical Management ◽

Structural Complexity ◽

Strong Preference ◽

Phonological Development ◽

Structural Position ◽

Phonological Disorders ◽

Syllabic Structure ◽

The Relationship ◽

Structural Aspects ◽

Target Words

The relationship between syllabic structure and segmental development was examined longitudinally in a child with a severe phonological disorder. Six speech samples were collected over a 4-year period (3:5 to 7:3). Analyses revealed gradual increases in the complexity and diversity of the syllable structures produced, and positional preferences for sounds within these forms. With a strong preference for [d] and [n] at the beginning of syllables, other consonants appeared first at the end of syllables. Implications for clinical management of phonological disorders include the need to consider both structural position and structural complexity in assessing segmental skills and in choosing target words for intervention.

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