The three-dimensional structure of the cell wall glycoprotein of Chlorogonium elongatum

1984 ◽  
Vol 68 (1) ◽  
pp. 271-284
Author(s):  
P.J. Shaw ◽  
G.J. Hills
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Primary Cell Wall ◽  
Globular Domain ◽  
Higher Plant ◽  
Intersubunit Interactions

The green alga Chlorogonium elongatum, a member of the Volvocales, possesses a crystalline cell wall composed of hydroxyproline-rich glycoprotein similar to the primary cell wall glycoproteins of higher plants. Electron microscopy and computer image processing have been used to determine the crystal structure of the Chlorogonium cell wall in three dimensions to a resolution of 2.0 nm. The structure is composed of heterologous dimers. Each subunit of the dimer comprises a long, thin spacer domain and a large globular domain, which is the site of the intra- and inter-dimer interactions. There are also sites of intersubunit interactions at the opposite ends of the rod domains. We suggest that the rods are composed predominantly of glycosylated polyproline helix, as has been suggested for higher plant cell wall glycoproteins and has been shown for the cell wall glycoprotein of Chlamydomonas reinhardtii, which is closely related to Chlorogonium.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Direct visualization of cross-links in the primary plant cell wall

1990 ◽  
Vol 96 (2) ◽  
pp. 323-334 ◽  
Author(s):  
M. C. MCCANN ◽  
B. WELLS ◽  
K. ROBERTS
Keyword(s):  
Cell Wall ◽  
Plant Cell Wall ◽  
Three Dimensional ◽  
Preliminary Evidence ◽  
Cellulose Microfibrils ◽  
Primary Cell Wall ◽  
Positive Role ◽  
Extraction Step ◽  
Cross Links ◽  
Wall Construction

We have investigated the structure of the onion primary cell wall at high resolution, using shadowed replicas of rapidly frozen deep-etched specimens. We have sequentially extracted polymers from the wall and have visualized both these and the remaining structures at each extraction step. By viewing the structures in as near their native state as possible, an accurate three-dimensional picture of wall construction has been assembled, facilitated by viewing stereo pairs of micrographs. Our observations show that the physical links between cellulose microfibrils that we observe in the intact wall are generally shorter (20–40 nm) than the isolated molecules we extract (30->700nm), suggesting that lateral interactions must occur between linking polymers and cellulose in muro. These cross-links are hemicellulosic and we believe them to be xyloglucans: their removal allows increased lateral association of microfibrils. Na2CO3-extractable pectic fractions form a separate coextensive network, the removal of which does not affect basic cellulose/ hemicellulose architecture. Preliminary evidence for a lamellate model of wall construction has been obtained. In addition, we propose a positive role for hemicellulose in maintaining the ordered spacing of cellulose micronbrils, perhaps regulating wall porosity and strength. The basic wall parameters that we derive impose constraints on possible cell wall models.

scholarly journals Interaction of higher plant ribosomal 5S RNAs with Xenopus laevis transcriptional factor IIIA.

1994 ◽  
Vol 41 (1) ◽  
pp. 17-24 ◽  
Author(s):  
M Z Barciszewska
Keyword(s):  
Xenopus Laevis ◽  
Wheat Germ ◽  
Three Dimensional ◽  
Transcriptional Factor ◽  
Dimensional Structure ◽  
Higher Plant ◽  
Three Dimensional Structure ◽  
Common Motif ◽  
Lupin Seeds

In this paper transcriptional factor IIIA (TFIIIA) has been used as a probe for identity of three-dimensional-structure of eukaryotic 5S rRNAs. I was interested in finding a common motif in plant and Xenopus 5S rRNAs for TFIIIA recognition. I found that the two eukaryotic 5S rRNAs (from wheat germ and lupin seeds) are recognized by X. laevis TFIIIA and the data clearly suggest that these 5S rRNAs have very similar if not identical three-dimensional structures. Also effects of various conditions on stability of these complexes have been studied.

scholarly journals Based on systems science methodology—— Research on the talent training system of hall three-dimensional structure

2020 ◽  
Vol 198 ◽  
pp. 01050
Author(s):  
Yong-Chen ◽  
Zhong Hua-Cheng ◽  
Qi-Xu
Keyword(s):  
Three Dimensional ◽  
Training System ◽  
Three Dimensions ◽  
Structure Theory ◽  
Dimensional Structure ◽  
Systems Science ◽  
Three Dimension ◽  
Time Dimension ◽  
Dimension Analysis ◽  
Science Methodology

Draw lessons from the basic idea of system science methodology, based on the hall three dimensions structure theory construction of research personnel training problems, from the time dimension, logic knowledge and three dimension analysis of all aspects of talent cultivation system, clear the talent training theory support, and solve the problem of a series of contradictions in the process of talent training, further enriched and developed the theoretical system of talents cultivation.

scholarly journals Cryo-Electron Tomography Reveals the Comparative Three-Dimensional Architecture of Prochlorococcus, a Globally Important Marine Cyanobacterium

2007 ◽  
Vol 189 (12) ◽  
pp. 4485-4493 ◽  
Author(s):  
Claire S. Ting ◽  
Chyongere Hsieh ◽  
Sesh Sundararaman ◽  
Carmen Mannella ◽  
Michael Marko
Keyword(s):  
Cell Wall ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Membrane System ◽  
Niche Differentiation ◽  
Dimensional Structure ◽  
Comparative Genomic ◽  
Photosynthetic Membrane ◽  
Peptidoglycan Biosynthesis ◽  
Cryo Electron Tomography

ABSTRACT In an age of comparative microbial genomics, knowledge of the near-native architecture of microorganisms is essential for achieving an integrative understanding of physiology and function. We characterized and compared the three-dimensional architecture of the ecologically important cyanobacterium Prochlorococcus in a near-native state using cryo-electron tomography and found that closely related strains have diverged substantially in cellular organization and structure. By visualizing native, hydrated structures within cells, we discovered that the MED4 strain, which possesses one of the smallest genomes (1.66 Mbp) of any known photosynthetic organism, has evolved a comparatively streamlined cellular architecture. This strain possesses a smaller cell volume, an attenuated cell wall, and less extensive intracytoplasmic (photosynthetic) membrane system compared to the more deeply branched MIT9313 strain. Comparative genomic analyses indicate that differences have evolved in key structural genes, including those encoding enzymes involved in cell wall peptidoglycan biosynthesis. Although both strains possess carboxysomes that are polygonal and cluster in the central cytoplasm, the carboxysomes of MED4 are smaller. A streamlined cellular structure could be advantageous to microorganisms thriving in the low-nutrient conditions characteristic of large regions of the open ocean and thus have consequences for ecological niche differentiation. Through cryo-electron tomography we visualized, for the first time, the three-dimensional structure of the extensive network of photosynthetic lamellae within Prochlorococcus and the potential pathways for intracellular and intermembrane movement of molecules. Comparative information on the near-native structure of microorganisms is an important and necessary component of exploring microbial diversity and understanding its consequences for function and ecology.

scholarly journals Three-dimensional structure of the bacterial cell wall peptidoglycan

2006 ◽  
Vol 103 (12) ◽  
pp. 4404-4409 ◽  
Author(s):  
S. O. Meroueh ◽  
K. Z. Bencze ◽  
D. Hesek ◽  
M. Lee ◽  
J. F. Fisher ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Three Dimensional ◽  
Bacterial Cell Wall ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Cell Wall Peptidoglycan

Three-dimensional X-ray diffraction imaging of process-induced dislocation loops in silicon

2011 ◽  
Vol 44 (3) ◽  
pp. 526-531 ◽  
Author(s):  
David Allen ◽  
Jochen Wittge ◽  
Jennifer Stopford ◽  
Andreas Danilewsky ◽  
Patrick McNally
Keyword(s):  
Semiconductor Industry ◽  
Three Dimensional ◽  
Crystal Defects ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Imaging ◽  
Relationship Of

In the semiconductor industry, wafer handling introduces micro-cracks at the wafer edge and the causal relationship of these cracks to wafer breakage is a difficult task. By way of understanding the wafer breakage process, a series of nano-indents were introduced both into 20 × 20 mm (100) wafer pieces and into whole wafers as a means of introducing controlled strain. Visualization of the three-dimensional structure of crystal defects has been demonstrated. The silicon samples were then treated by various thermal anneal processes to initiate the formation of dislocation loops around the indents. This article reports the three-dimensional X-ray diffraction imaging and visualization of the structure of these dislocations. A series of X-ray section topographs of both the indents and the dislocation loops were taken at the ANKA Synchrotron, Karlsruhe, Germany. The topographs were recorded on a CCD system combined with a high-resolution scintillator crystal and were measured by repeated cycles of exposure and sample translation along a direction perpendicular to the beam. The resulting images were then rendered into three dimensions utilizing open-source three-dimensional medical tomography algorithms that show the dislocation loops formed. Furthermore this technique allows for the production of a video (avi) file showing the rotation of the rendered topographs around any defined axis. The software also has the capability of splitting the image along a segmentation line and viewing the internal structure of the strain fields.

METHODS FOR INDICATION OF NONCULTURATED VIABLE MICROORGANISMS WHEN CONTROL OF CRITICAL POINTS OF LIVESTOCK, POULTRY AND FOOD PRODUCTION TECHNOLOGY

2021 ◽  
Vol 1 (4) ◽  
pp. 441-447
Author(s):  
Ekaterina M. Lenchenko ◽  
◽  
Damir I. Udavliev ◽  
Inna B. Pavlova ◽  
◽  
...  
Keyword(s):  
Cell Wall ◽  
Luminescence Spectrum ◽  
Three Dimensional ◽  
Yeast Cells ◽  
Dimensional Structure ◽  
Heterogeneous Structure ◽  
Bacterial Cells ◽  
Microscopic Fungi ◽  
Gram Positive Bacteria ◽  
Red Luminescence

The results of morphometric and densitometric parameters biofilms are presented, effective methods of detecting uncultivated viable microorganisms isolated from a representative sample of objects of veterinary and sanitary supervision are tested and selected. Optical, luminescent and scanning electron microscopy revealed the formation of a three-dimensional structure biofilms in the form a dense network consisting of gram-negative and gram-positive bacteria, yeast cells, hyphal and pseudohyphalic forms, surrounded by an intercellular polymer matrix. The presence hyphae of microscopic fungi causes an increase in the number of cells adhered to the substrate, microcolonies were formed from bacteria and yeast cells of microscopic fungi. The pathogenesis of the syndrome of overgrowth of microorganisms is provided by the presence of various dissociative variants, the dispersion of uncultivated bacterial cells, which gain advantages in the hyperagregation of the architectonics of heterogeneous biofilms. Multilayer membranes, vesicles, cells with a defective cell wall, spheroplasts, protoplasts, L-shapes, needle-like and giant structures, and revertant cells were identified. The dynamics of changes in the viable structures microorganisms was characterized by alternating periods of decrease and increase in the intensity of biofilm formation. When detecting the viability of microorganisms in the composition biofilms, viable and non-viable cells were differentiated – a green luminescence spectrum and a red luminescence spectrum, respectively. The dissociation of the population caused an increase in the concentration of R-dissociant cells with a higher growth rate, cell lysis was detected after 48–72 h of cultivation, a change in the ratio phenotypic forms was observed – the M-dissociant was predominant. The study of the heterogeneous structure of the population, without disturbing the natural architectonics of biofilms, revealed direct correlations (r = 0,89) between morphometric (≥90 % of the field of view) and densitometric parameters (OD). The efficiency of a nutrient medium containing pancreatic hydrolyzate, mannitol, L-asparagine and glycerol was established for the repair of the cell wall, the reversal of L-forms of microorganisms.

Diffraction by crystals

2002 ◽  
Author(s):  
David Blow
Keyword(s):  
Fourier Transform ◽  
Three Dimensional ◽  
Incident Beam ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Angle Of Incidence ◽  
X Ray ◽  
Max Von Laue ◽  
The Fourier Transform

In Chapter 4 many two-dimensional examples were shown, in which a diffraction pattern represents the Fourier transform of the scattering object. When a diffracting object is three-dimensional, a new effect arises. In diffraction by a repetitive object, rays are scattered in many directions. Each unit of the lattice scatters, but a diffracted beam arises only if the scattered rays from each unit are all in phase. Otherwise the scattering from one unit is cancelled out by another. In two dimensions, there is always a direction where the scattered rays are in phase for any order of diffraction (just as shown for a one-dimensional scatterer in Fig. 4.1). In three dimensions, it is only possible for all the points of a lattice to scatter in phase if the crystal is correctly oriented in the incident beam. The amplitudes and phases of all the scattered beams from a three-dimensional crystal still provide the Fourier transform of the three-dimensional structure. But when a crystal is at a particular angular orientation to the X-ray beam, the scattering of a monochromatic beam provides only a tiny sample of the total Fourier transform of its structure. In the next section, we are going to find what is needed to allow a diffracted beam to be generated. We shall follow a treatment invented by Lawrence Bragg in 1913. Max von Laue, who discovered X-ray diffraction in 1912, used a different scheme of analysis; and Paul Ewald introduced a new way of looking at it in 1921. These three methods are referred to as the Laue equations, Bragg’s law and the Ewald construction, and they give identical results. All three are described in many crystallographic text books. Bragg’s method is straightforward, understandable, and suffices for present needs. I had heard J.J. Thomson lecture about…X-rays as very short pulses of radiation. I worked out that such pulses…should be reflected at any angle of incidence by the sheets of atoms in the crystal as if these sheets were mirrors.…It remained to explain why certain of the atomic mirrors in the zinc blende [ZnS] crystal reflected more powerfully than others.

scholarly journals Application of the Measure of Peer Justice Climate to a Multiethnic Sample

SAGE Open ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 215824401989882
Author(s):  
Blaine Marcano ◽  
Gloria Castaño-Collado
Keyword(s):  
Undergraduate Students ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Dimensional Structure ◽  
Outcome Variable ◽  
Confirmatory Factor Analyses ◽  
Team Members ◽  
Justice Perceptions ◽  
Competing Models ◽  
Justice Climate

The measure created by H. Li offers a useful tool for investigating justice perceptions among team members or peer justice climate; however, more research is required to confirm its structure in lieu of competing models. This study provides evidence for the three-dimensional structure of peer justice climate within a multiethnic context and explores its relation to outcome variable performance. Participants were 304 undergraduate students from universities in the multiethnic, Republic of Trinidad and Tobago. Competing structures of peer justice climate were compared using exploratory and confirmatory factor analyses. Results indicated that peer justice climate is best conceptualized as having three dimensions (distributive, procedural, interactional) with an overarching justice factor connecting them. Suggestions are made for improving the measure. Procedural peer justice climate was found to have a significant positive relation with team performance.

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