Formation Of Rods Research Articles

RDS Functional Domains and Dysfunction in Disease.

The photoreceptor specific tetraspanin protein retina degeneration slow (RDS) is a critical component of the machinery necessary for the formation of rod and cone outer segments. Over 80 individual pathogenic mutations in RDS have been identified in human patients that lead to a wide variety of retinal degenerative diseases including retinitis pigmentosa, cone-rod dystrophy, and various forms of macular dystrophy. RDS-associated disease is characterized by a high degree of variability in phenotype and penetrance, making analysis of the underlying molecular mechanisms of interest difficult. Here we summarize our modern understanding of RDS functional domains and oligomerization and how disruption of these domains and complexes could contribute to the variety of disease pathologies seen in human patients with RDS mutations.

Exsolution of Fe and SrO Nanorods and Nanoparticles from Lanthanum Strontium Ferrite La0.6Sr0.4FeO3-δ Materials by Hydrogen Reduction.

Formation of uniform Fe and SrO rods as well as nanoparticles following controlled reduction of La0.6Sr0.4FeO3−δ (LSF) and Ni-LSF samples in dry and moist hydrogen is studied by aberration-corrected electron microscopy. Metallic Fe and SrO precipitate from the perovskite lattice as rods of several tenths of nm and thicknesses up to 20 nm. Based on a model of Fe whisker growth following reduction of pure iron oxides, Fe rod exsolution from LSF proceeds via rate-limiting lattice oxygen removal. This favors the formation of single iron metal nuclei at the perovskite surface, subsequently growing as isolated rods. The latter is only possible upon efficient removal of reduction-induced water and, subsequently, reduction of Fe +III/+IV to Fe(0). If water remains in the system, no reduction or rod formation occurs. In contrast, formation of SrO rods following reduction in dry hydrogen is a catalytic process aided by Ni particles. It bears significant resemblance to surface diffusion-controlled carbon whisker growth on Ni, leading to similar extrusion rods and filaments. In addition to SrO rod growth, the exsolution of Fe nanoparticles and, subsequently, Ni–Fe alloy particles is observed. The latter have also been observed under static hydrogen reduction. Under strict control of the experimental parameters, the presented data therefore open an attractive chemically driven pathway to metal nanoarchitectures beyond the formation of “simple” nanoparticles.

Nucleation and growth of electrodeposited Mn oxide rods for supercapacitor electrodes

The nucleation and growth of electrodeposited Mn oxide rods has been investigated by preparing deposits on Au coated Si at varying deposition times between 0.5 s and 10 min. The deposits were investigated using high resolution scanning and transmission electron microscopy. A model for the nucleation and growth of Mn oxide rods has been proposed. Nucleation begins as thin sheets along Au grain boundaries and triple points. As these nucleation sites are consumed, nucleation spreads across the grains. Nucleation of sheets in close proximity causes agglomeration and the formation of rounded particles. Some of these rounded particles then accelerate in growth, initially in all directions and then primarily in the direction normal to the sample surface. Accelerated growth normal to the sample surface leads to the formation of rods. As rods grow, the growth of other particles accelerates and they become rods themselves. Eventually the entire sample surface is covered with rods 15–20 μm long and about 2 μm wide. The sheet-like morphology of the deposits is retained at all stages of deposition. Electron diffraction analysis of 3 s and 6 s deposits shows that the sheets are initially amorphous and then begin to crystallize into a cubic spinel Mn3O4 crystal structure. High resolution imaging of the 6 s sample shows small crystalline regions (∼5 nm in size) within an amorphous matrix.

Physicochemical properties of sprayed V2O5 thin films: Effect of substrate temperature

Polycrystalline vanadium pentoxide (V2O5) thin films have been successfully deposited onto preheated glass substrates via chemical spray pyrolysis deposition method at various substrate temperatures from 350 to 500°C. The thermal decomposition behavior of vanadium trichloride (VCl3) powder has been studied using thermogravimetric–differential thermal analysis (TG–DTA). The effect of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. XRD analysis showed that the films are polycrystalline with an orthorhombic crystal structure. SEM study showed the formation of rod like morphology of varying length from 0.8 to 1μm and diameter from 230 to 300nm. AFM study showed that the grain size varies from 134 to 304nm. The optical results revealed that band gap energy decreases from 2.53 to 2.35eV for direct allowed transition. The dielectric properties revealed that the dielectric constant (ϵ′) and dielectric loss tangent (tan δ) decreases whereas AC conductivity increases with increase in frequency of applied electric field. DC resistivity measurement results showed the semiconducting behavior of the V2O5 thin films.

Association of a Novel ACTA1 Mutation With a Dominant Progressive Scapuloperoneal Myopathy in an Extended Family.

New genomic strategies can now be applied to identify a diagnosis in patients and families with previously undiagnosed rare genetic conditions. The large family evaluated in the present study was described in 1966 and now expands the phenotype of a known neuromuscular gene. To determine the genetic cause of a slowly progressive, autosomal dominant, scapuloperoneal neuromuscular disorder by using linkage and exome sequencing. Fourteen affected individuals in a 6-generation family with a progressive scapuloperoneal disorder were evaluated. Participants were examined at pediatric, neuromuscular, and research clinics from March 1, 2005, to May 31, 2014. Exome and linkage were performed in genetics laboratories of research institutions. Examination and evaluation by magnetic resonance imaging, ultrasonography, electrodiagnostic studies, and muscle biopsies (n = 3). Genetic analysis included linkage analysis (n = 17) with exome sequencing (n = 7). Clinical findings included progressive muscle weakness in an initially scapuloperoneal and distal distribution, including wrist extensor weakness, finger and foot drop, scapular winging, mild facial weakness, Achilles tendon contractures, and diminished or absent deep tendon reflexes. Both age at onset and progression of the disease showed clinical variability within the family. Muscle biopsy specimens demonstrated type I fiber atrophy and trabeculated fibers without nemaline rods. Analysis of exome sequences within the linkage region (4.8 megabases) revealed missense mutation c.591C>A p.Glu197Asp in a highly conserved residue in exon 4 of ACTA1. The mutation cosegregated with disease in all tested individuals and was not present in unaffected individuals. This family defines a new scapuloperoneal phenotype associated with an ACTA1 mutation. A highly conserved protein, ACTA1 is implicated in multiple muscle diseases, including nemaline myopathy, actin aggregate myopathy, fiber-type disproportion, and rod-core myopathy. To our knowledge, mutations in Glu197 have not been reported previously. This residue is highly conserved and located in an exposed position in the protein; the mutation affects the intermolecular and intramolecular electrostatic interactions as shown by structural modeling. The mutation in this residue does not appear to lead to rod formation or actin accumulation in vitro or in vivo, suggesting a different molecular mechanism from that of other ACTA1 diseases.

Cofilin rod formation in neurons impairs neuronal structure and function.

Cofilin-1 is a major actin depolymerizer in the central nervous system. It is a member of the ADF/cofilin family that regulates the dynamics of actin filaments. The activity of cofilin-1 is regulated by the modulation of phosphorylation at its Ser3 residue, and its proper function is crucial for the structure and proper function of neurons. Cofilin rods, pathological structures composed of cofilin and actin, form under stress conditions. A high cofilin/F-actin ratio, cofilin dephosphorylation and/or cofilin oxidation are three major mechanisms of cofilin rod formation. Cofilin rods can be divided into cytoplasmic rods and nuclear rods. Cytoplasmic rods have been proved to disrupt dendritic transportation, cause synaptic loss and impair synaptic function, which maybe associated with neurodegenerative diseases such as Alzheimer's disease. On the other hand, the role of nuclear rods remains largely unknown. Further studies are needed to investigate the relationship and the underlying mechanisms of cofilin rod formation during the progression of various neurological diseases.

Quality of the “aluminum-carbon” interface when forming current leads to anodes of magnesium electrolyzers

The results of an investigation into the metal-nonmetal interface during the formation of electrocontact rods by means of the effect of a high-strength pulsed magnetic field on the melt are presented. It is shown that the proposed magnetic-pulsed technology makes it possible to considerably lower the transient electric resistance between electrocontact rods and the anode block of the electrolyzer due to an increase in contact density.

Growth mechanism of icosahedral and other five-fold symmetric diamond crystals

Five-fold symmetric diamond crystals (FSDCs) were synthesized by hot filament chemical vapour deposition (HFCVD) methods. Their surface morphologies and defects were characterised by scanning electron microscopy (SEM). From the perspective of nucleation-growth, a growth mechanism for icosahedral and other five-fold symmetric diamond crystals was discussed. Computer modelling was also carried out. The results show that the dodecahedrane (C20H20) molecule is proposed as a nucleus for the growth of icosahedral diamond crystals (IDCs), wherein the 20 {111} surface planes develop orthogonal to the direction of the original 20… C…H bonds by sequential H abstraction and CH3 addition reactions. IDC can be pictured as an assembly of isosceles tetrahedra, with each tetrahedron contributing a {111} plane to the surface of the IDC and the remainder of the tetrahedral surfaces forming twin planes with neighbouring tetrahedra. The small mismatch (1.44°) between the {111} surface dihedral angle of a perfect icosahedron and that of a twinned icosahedron reveals itself via twin planes in the IDC grain. The modelling suggests how the relief of strain induced by this distortion could lead to the formation of defects such as concave pentagonal cavities at vertices and grooves along the grain edges that accord well with those observed experimentally. Similar arguments based on growth from the hexacyclo pentadecane (C15H20) nucleus can also account for the observed formation of star and rod shaped FSDCs, and some of their more obvious morphological defects.

QUALITY OF THE «ALUMINUM–CARBON» INTERFACE WHEN FORMING CURRENT LEADS TO ANODES OF MAGNESIUM ELECTROLYZERS

The results of investigation into the metal–nonmetal interface during the formation of electrocontact rods by means of the effect of the high-strength pulsed magnetic field on the melt are presented. It is shown that the proposed magnetic-pulsed technology makes it possible to considerably lower the transient electric resistance between electrocontact rods and anode block of the electrolyzer due to an increase in contact density.

Sperm exposure to carbon-based nanomaterials causes abnormalities in early development of purple sea urchin (Paracentrotus lividus)

We examined egg fertilisation in purple sea urchin (Paracentrotus lividus) after sperm exposure to carbon-based nanomaterials, carbon black (CB) and graphene oxide (GO), from 0.0001mg/L to 1.0mg/L. Gastrula stage embryos were investigated for acetylcholinesterase and propionylcholinesterase activities, and their morphological characteristics. Plutei were analysed for morphological abnormalities, with emphasis on skeletal rod formation. Egg fertilisation was significantly affected by CB, at all concentrations tested. Loss of cell adhesion at the gastrula surface was observed in eggs fertilised with sperm treated with CB. However, concentration-dependant morphological anomalies were observed in the gastrulae and plutei formed after sperm exposure to either CB or GO. The activities of both cholinesterases decreased in the gastrulae, although not in a concentration-dependent manner. These effects appear to arise from physical interactions between these carbon-based nanomaterials and the sperm, whereby nanomaterials attached to the sperm surface interfere with fertilisation, which leads to disturbances in the signalling pathways of early embryonic development. Reduced cholinesterase activity in gastrulae from eggs fertilised with nanomaterial-treated sperm confirms involvement of the cholinergic system in early sea urchin development, including skeletogenesis.

Crystal structure of Alanine‐Copper(II) complex to understand the mechanism of salt induced prebiotic oligomerization of amino acids

Oligomerization of amino acid monomers is the vital step in the formation of longer peptides and functional proteins. In spite of continuing efforts towards solving the puzzle of origin of life, the mystery of chemical evolution remains unsolved. Out of various pathways proposed for the formation of peptides under prebiotic conditions, salt induced peptides synthesis presents the most plausible scenario. In attempts to study mechanism of prebiotic oligomerization of amino acid on primitive earth the current study was aimed to determine the crystal structure of intermediate copper amino acid complex and its supra‐molecular assembly. The Structure of the copper alanine complex obtained from SIPF was studied by x‐ray crystallography. The self‐assembling properties of complex into supra‐molecular nanostructures were studied using Field‐emission electron microscopy (FE‐SEM). Results showed the occurrence of racemization of amino acids. This is the first structural study for copper alanine complex formed from prebiotic peptide synthesis pathway. The aggregational properties of intermediate complex showed the formation of rod like crystals and nanospheres. The findings from our study showed the possible mechanism of prebiotic oligomerization of amino acids on the primitive earth towards formation of longer peptides and functional proteins.

Preparation, characterization and photoluminescence properties of SiO2 and SiO2:Eu3+ submicron rods

SiO2 and Eu3+-doped SiO2 submicron rods were conveniently fabricated via a sol–gel process at room temperature. In this process, citric acid served as a unique structural modifier through hydrolysis of TEOS at alkaline condition to obtain the silica submicron rods. The morphology of the products was sensitive to the conditions, such as stirring, gelation time and the dropping speed of NH4OH. By sampling the products at different reaction times, we discussed the formation and growing mechanism of SiO2:Eu3+ submicron rods in detail. The weak interactions between ammonium citrate crystals and silica species may be the reasons of the rods formation. The obtained silica submicron rods were 5–6μm in length and 650–750nm in width and there was no obvious change after doping. Under UV light excitation, the undoped silica submicron rods exhibited blue emission, which may be associated with defect centers in the structures of the products. The Eu3+-doped silica submicron rods exhibited red emission, which was due to the 4f→4f transition of Eu3+. The effect of different doping concentrations of Eu3+ ions on the luminescence was investigated. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), Thermo-gravimetry Analysis (TGA), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Energy-dispersive spectroscopy (EDS) and Photoluminescence spectrum.

Nuclear actin aggregation is a hallmark of anti-synthetase syndrome-induced dysimmune myopathy.

To analyze antisynthetase syndrome-associated myositis by modern myopathologic methods and to define its place in the spectrum of idiopathic inflammatory myopathies (IIMs). Skeletal muscle biopsies from antisynthetase syndrome-associated myositis and other IIMs from different institutions worldwide were analyzed by histopathology, quantitative PCR, and electron microscopy. Myonuclear actin filament inclusions were identified as a unique morphologic hallmark of antisynthetase syndrome-associated myositis. Nuclear actin inclusions were never found in dermatomyositis, polymyositis, sporadic inclusion body myositis, autoimmune necrotizing myopathy associated with signal recognition particle or 3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies, or nonspecific myositis associated with other systemic diseases, harboring myositis-associated autoantibodies, and presenting myofiber necrosis. We show that molecules involved in actin filament formation and actin shuttling mechanisms are altered in antisynthetase syndrome, and may thus be involved in pathologic myonuclear actin aggregation. In addition, we have identified a typical topographic distribution of necrotic myofibers predominantly located at the periphery of muscle fascicles accompanied by inflammation and destruction of the perimysial connective tissue. Antisynthetase syndrome-associated myositis is characterized by distinctive myonuclear actin filament inclusions, including rod formations and a typical necrotizing perimysial myositis. This supports the hypothesis that antisynthetase syndrome-associated myositis is unique and should not be grouped among dermatomyositis, polymyositis, sporadic inclusion body myositis, necrotizing autoimmune myositis, or nonspecific myositis. This study provides Class II evidence that for patients with IIMs, the presence of myonuclear actin filament inclusions accurately identifies patients with antisynthetase syndrome-associated myositis (sensitivity 81%, specificity 100%).

Fe–Al–P–C–B bulk metallic glass with good mechanical and soft magnetic properties

Fe-based bulk metallic glasses (BMGs) were fabricated in Fe–Al–P–C–B alloy system by copper mold casting. Among them, Fe77Al3P9C9B2 (at.%) alloy shows the best glass-forming ability yielding the formation of an amorphous cylinder rod with a diameter of 3.0mm. This alloy exhibits a high compressive strength of more than 3000MPa and an appreciable plastic strain of up to 5.0%. In addition, the present alloy also shows good soft magnetic properties, i.e., high saturation magnetization of about 1.36T and low coercive force of about 2.1A/m. The integration of high GFA, good mechanical and soft magnetic properties along with low materials cost for the Fe–Al–P–C–B BMG makes it a competitive candidate as structural and functional materials.

Clinical report of Brucella spondylitis in elderly people

Objective To discuss the clinical features and treatment of Brucella spondylitis in elderly people and its efficacy. Methods From January 2002 to May 2013, 45 cases of elderly patients with Brucella spondylitis who were misdiagnosed as spinal tuberculosis before admission were diagnosed synthetically by epidemiological history, clinical manifestations, laboratory tests, medical imaging and pathological data after admission. All patients were treated by standardized drug treatment and hyperbaric oxygen therapy, of which 19 cases were treated by non-surgical treatment (group A) and 26 cases were treated by the operation of primary debridement and posterior pedicle screw fixation (group B). All patients underwent follow-up, pain score, laboratory testing, imaging score and clinical efficacy evaluation after the operation. Results During 12 months follow-up after treatment, 17 cases were cured, 2 cases improved; no adverse drug reaction and abnormal liver and kidney function were found in group A. 26 cases in group B underwent operation, of which 24 cases were cured, 2 cases improved. The implanted bone was healed, the spine was stable and no broken nails, broken rod, recurrence and sinus formation were found in group B. Both of the treatments could gradually decrease pain score that relieved pain effectively over time. The time for pain-relieving and the pain-relieving efficacy were less or better in group B than in group A (both P<0.05). The time for decreasing the serum agglutination test (SAT) titre and C-reactive protein (CRP) level, and for becoming negative of Rose Bengal Plane Test (RBPT) was less in group B than in group A. The vertebral inflammatory infiltration and infection of intervertebral space were gradually absorbed, which required a longer period of treatment in group A, and the efficacies in imaging changes at different time were less in group A than in group B (all P<0.05). The early-stage cure rate was better in group B than in group A, although both treatments had obvious effect (P<0.05). Conclusions The formulation of the diagnostic criteria of Brucella spondylitis in elderly people can improve the diagnostic rate and reduce the misdiagnosis rate. Standardized drug treatment has a better cure rate, and timely surgical intervention can improve clinical effect and has significant advantages particularly in relieving pain, stabilizing the spine, restoring nerve function and promoting early rehabilitation. Key words: Brucellosis; Spine; Inflammation

Molecular Basis for SMC Rod Formation and Its Dissolution upon DNA Binding

SummarySMC condensin complexes are central modulators of chromosome superstructure in all branches of life. Their SMC subunits form a long intramolecular coiled coil, which connects a constitutive “hinge” dimerization domain with an ATP-regulated “head” dimerization module. Here, we address the structural arrangement of the long coiled coils in SMC complexes. We unequivocally show that prokaryotic Smc-ScpAB, eukaryotic condensin, and possibly also cohesin form rod-like structures, with their coiled coils being closely juxtaposed and accurately anchored to the hinge. Upon ATP-induced binding of DNA to the hinge, however, Smc switches to a more open configuration. Our data suggest that a long-distance structural transition is transmitted from the Smc head domains to regulate Smc-ScpAB’s association with DNA. These findings uncover a conserved architectural theme in SMC complexes, provide a mechanistic basis for Smc’s dynamic engagement with chromosomes, and offer a molecular explanation for defects in Cornelia de Lange syndrome.

CetZ tubulin-like proteins control archaeal cell shape.

Tubulin is a major component of the eukaryotic cytoskeleton, controlling cell shape, structure and dynamics, whereas its bacterial homologue FtsZ establishes the cytokinetic ring that constricts during cell division. How such different roles of tubulin and FtsZ evolved is unknown. Studying Archaea may provide clues as these organisms share characteristics with Eukarya and Bacteria. Here we report the structure and function of proteins from a distinct family related to tubulin and FtsZ, named CetZ, which co-exists with FtsZ in many archaea. CetZ X-ray crystal structures showed the FtsZ/tubulin superfamily fold, and one crystal form contained sheets of protofilaments, suggesting a structural role. However, inactivation of CetZ proteins in Haloferax volcanii did not affect cell division. Instead, CetZ1 was required for differentiation of the irregular plate-shaped cells into a rod-shaped cell type that was essential for normal swimming motility. CetZ1 formed dynamic cytoskeletal structures in vivo, relating to its capacity to remodel the cell envelope and direct rod formation. CetZ2 was also implicated in H. volcanii cell shape control. Our findings expand the known roles of the FtsZ/tubulin superfamily to include archaeal cell shape dynamics, suggesting that a cytoskeletal role might predate eukaryotic cell evolution, and they support the premise that a major function of the microbial rod shape is to facilitate swimming.

Synthesis, luminescence properties and EPR investigation of hydrothermally derived uniform ZnO hexagonal rods

One-dimensional (1D) zinc oxide (ZnO) hexagonal rods have been successfully synthesized by surfactant free hydrothermal process at different temperatures. It can be found that the reaction temperature play a crucial role in the formation of ZnO uniform hexagonal rods. The possible formation processes of 1-D ZnO hexagonal rods were investigated. The zinc hydroxide acts as the morphology-formative intermediate for the formation of ZnO nanorods. Upon excitation at 325nm, the sample prepared at 180°C show several emission bands at 400nm (∼3.10eV), 420nm (∼2.95eV), 482nm (∼2.57eV) and 524nm (∼2.36eV) corresponding to different kind of defects. TL studies were carried out by pre-irradiating samples with γ-rays ranging from 1 to 7kGy at room temperature. A well resolved glow peak at ∼354°C was recorded which can be ascribed to deep traps. Furthermore, the defects associated with surface states in ZnO nano-structures are characterized by electron paramagnetic resonance.

Understanding the selective etching of electrodeposited ZnO nanorods.

ZnO nanotubes were prepared by selective dissolution of electrodeposited nanorods. The effect of solution pH, rod morphology, and chloride ion concentration on the dissolution mechanism was studied. The selective etching was rationalized in terms of the surface energy of the different ZnO crystal faces and reactant diffusion. The nanorod diameter and chloride concentration are the most influential parameters on the dissolution mechanism because they control homogeneous dissolution or selective etching of the (110) and (002) surfaces. Bulk solution pH only has an effect on the rate of dissolution. By accurate control of the dissolution process, the nanomorphology can be tailored, and the formation of rods with a thin diameter (10-20 nm), cavity, or ultra-thin-walled tubes (2-5 nm) can be achieved.

Formation mechanism of rutile TiO2 rods on fluorine doped tin oxide glass.

We report the formation mechanism of rutile TiO2 rods grown directly on fluorine doped tin oxide (FTO) glass by hydrothermal process at 130 degrees C. Through SEM images, we could monitor detailed nucleation and crystal growth process of TiO2 nanorods. The TiO2 nanorods started to nucleate and grow along the grain boundaries of SnO2 on FTO glass. As the reaction time increased, fine TiO2 nanorods started to encounter each other on (110) faces and merge, resulting in growth of micrometer scale rods in [001] direction. Through TEM, SAED, and XRD analyses, we propose that the nucleation of TiO2 on SnO2 grain boundaries occurs by Ostwald ripening (OR) while the merging of small TiO2 nanorods for the formation of larger rods occurs through oriented attachment (OA). The merged nanorods grow toward [001] direction to reduce surface energy.