Typical Ring Research Articles

Structure of a Shigella effector reveals a new class of ubiquitin ligases

Bacterial pathogens have evolved effector proteins with ubiquitin E3 ligase activities through structural mimicking. Here we report the crystal structure of the Shigella flexneri type III effector IpaH3, a member of the leucine-rich repeat (LRR)-containing bacterial E3 family. The LRR domain is structurally similar to Yersinia pestis YopM and potentially binds to substrates. The structure of the C-terminal E3 domain differs from the typical RING- and HECT-type E3s. IpaH3 synthesizes a Lys48-linked ubiquitin chain, and the reaction requires noncovalent binding between ubiquitin and a specific E2, UbcH5. Free ubiquitin serves as an acceptor for IpaH3-catalyzed ubiquitin transfer. Cys363 within a conserved CXD motif acts as a nucleophile to catalyze ubiquitin transfer through a transthiolation reaction. The D365N mutant is devoid of E3 activities but turns into a potent ubiquitin-E2 thioesterase. Our analysis establishes a structurally and mechanistically distinct class of ubiquitin ligases found exclusively in pathogenic or symbiotic bacteria.

Corneal Copper Deposition Secondary to Oral Contraceptives

To document two cases of corneal pigmented rings and hypercupremia associated with estrogen-based oral contraceptive use. Other causes of corneal pigment rings including Kayser-Fleischer rings and the previously documented association of estrogens and hypercupremia are discussed. Two healthy female patients presenting to a general optometric practice for routine examinations were found to have bilateral bluish-green corneal deposits at the level of endothelium/Descemet's membrane. The deposits were predominately in the inferior midperiphery in both patients, but formed a complete ring 3 years after initial presentation in one. Both patients were found to have abnormally elevated serum copper and elevated ceruloplasmin levels, and both were taking estrogen-based oral contraceptives. Serum copper levels returned to normal levels soon after cessation of the oral contraceptives, and subsequently re-elevated when a different oral contraceptive agent was tried. Although the pigment rings appeared different from typical Kayser-Fleischer rings, both patients were referred to gastroenterologists to rule out Wilson's disease. This is believed to be the first report of corneal pigment deposition and hypercupremia associated with oral contraceptive use. Recognition of these potential side effects by eye care practitioners and prescribing physicians may spare patients the expense and morbidity risk of unnecessary medical testing. Further research is needed to determine the exact nature of the deposits (presumed to be a copper compound), and whether it may be accumulating to dangerous levels in other body tissues as in Wilson's disease.

In Vitro Multimerization and Membrane Insertion of Bacterial Outer Membrane Secretin PulD

Synthesis of the Klebsiella oxytoca outer membrane secretin PulD, or its membrane-associated core domain, in a liposome-supplemented Escherichia coli in vitro transcription–translation system resulted in the formation of multimers that appeared as typical dodecameric secretin rings when examined by negative-stain electron microscopy. Cryo-electron microscopy of unstained liposomes and differential extraction by urea indicated that the secretin particles were inserted into the liposome membranes. When made in the presence of the detergent Brij-35, PulD and the core domain were synthesized as monomers. Both proteins caused almost immediate growth cessation when synthesized in E. coli without a signal peptide. The small amounts of PulD synthesized before cell death appeared as multimers with characteristics similar to those of the normal outer membrane secretin dodecamers. It was concluded that multimerization and membrane insertion are intrinsic properties of secretin PulD that are independent of a specific membrane environment or membrane-associated factors. The closely related Erwinia chrysanthemi secretin OutD behaved similarly to PulD in all assays, but the more distantly related Neisseria meningitidis secretin PilQ did not form multimers either when made in vitro in the presence of liposomes or when made in E. coli without its signal peptide. This is the first report of the apparently spontaneous in vitro assembly and membrane insertion of a large outer membrane protein complex. Spontaneous multimerization and insertion appear to be restricted to outer membrane proteins closely related to PulD.

EVALUATION OF PLUM POX VIRUS INFECTION ON DIFFERENT STONE FRUIT TREE VARIETIES

Fiftynine peach, 19 apricot and 19 plum varieties, grown in a screenhouse after inoculation by chip budding with the M strain of Plum pox virus (PPV), were surveyed from 2003 through 2007 for symptom expression on the leaves, flowers and fruits. A large number of accessions of the three species showed discoloration and mottling of the leaves in spring, and many peach varieties with pink flowers displayed strong colour breaking of the petals. Some peach and apricot and a single plum cultivar produced deformed fruit with typical rings and mottling. Eleven out of 97 inoculated cultivars, showed no apparent symptoms and gave negative responses in ELISA and Real time PCR assays. These plants were re-inoculated with the same PPV isolate and will be the object of further observations.

Characterisation of zinc-binding domains of peroxisomal RING finger proteins using size exclusion chromatography/inductively coupled plasma-mass spectrometry

We determined the zinc binding stoichiometry of peroxisomal RING finger proteins by measuring sulfur/metal ratios using inductively coupled plasma-mass spectrometry coupled to size exclusion chromatography, a strategy that provides a fast and quantitative overview on the binding of metals in proteins. As a quality control, liquid chromatography-electrospray ionisation-time of flight-mass spectrometry was used to measure the molar masses of the intact proteins. The RING fingers of Pex2p, Pex10p, and Pex12p showed a stoichiometry of 2.0, 2.1, and 1.2 mol zinc/mol protein, respectively. Thus, Pex2p and Pex10p possess a typical RING domain with two coordinated zinc atoms, whereas that of Pex12p coordinates only a single zinc atom.

Negative permeability around 630 nm in nanofabricated vertical meander metamaterials

AbstractWe demonstrate a new design of a 3‐dimensional meander structure that exhibits negative permeability with a broad bandwidth between 550 nm and 665 nm. The structural design allows for full coupling of the magnetic field component at all angles of incidence. We compare our structure with other metamaterial structures with respect to the series capacitance contributions of the different metamaterials. The investigation of optical metamaterials is carried out combining transmission line analysis with numerical simulations of Maxwell's equations. The analysis is demonstrated for typical split ring structures and the novel 3D meander metamaterial structures. Comparing the resulting scattering parameter spectra as well as the retrieved effective material parameters, we find that transmission line description remains valid for metamaterials at optical frequencies. We find in addition that the longitudinal capacitance is the decisive parameter to achieve negative permeability with a broad bandwidth at optical frequencies. For experimental verification we manufactured split‐ring resonator structures and meander metamaterial structures with linewidths down to 30 nm, element sizes down to 100 nm, and periods between 200 nm and 350 nm. For meander metamaterial structures a permeability value of –1 was achieved within a bandwidth of 50 nm centered at 630 nm. The largest absolute value of –4.5 was achieved at 650 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerical Simulation and Experimental Research on Rolling Process of Conical Ring with Inner Steps

The Conical Ring with Inner Steps (CRIS) is a typical profile ring, which is hard to be formed by ring rolling. Less-profile-filling and shrinking-drawing are the two main defects formed in the rolling process. Through the study of the rolling formability of CRIS with different ratio of height to diameter with the combination of FEM simulation method and experimental method, the main factors that affect the CRIS rolling formability are determined. The CRIS forging is designed. And the FEM simulation and experimental results show that the design method is reasonable.

Useful approach to access germanicanes from betulin

A new semisynthetic access to germanicane-type triterpenes was achieved from betulin, a natural triterpene of the lupane family. The Wagner–Meerwein rearrangement of acetylated betulinic acid allowed the formation of the typical ring E of germanicanes and a lactone function. Several germanicane derivatives can be obtained via the lactone ring-opening such as 19β-machaerocerol and 19β-machaeroceric acid. The cytotoxicity of some compounds was evaluated against two cancerous cell lines.

Ring current instabilities excited by the energetic oxygen ions

The ring current instabilities driven by the energetic oxygen ions are investigated during the magnetic storm. The electrons and protons are considered to have Maxwellian distributions, while energetic oxygen ions are having loss-cone distribution. Dispersion relation for the quasielectrostatic modes with frequencies ω>ωcp (proton cyclotron frequency) and propagating obliquely to the magnetic field is obtained. Dispersion relation is studied numerically for the storm time ring current parameters and it is found that these instabilities are most prominent during intense storms when the oxygen ions become the dominant constituents of the ring current plasma. For some typical storm-time ring current parameters, these modes can produce quasielectrostatic noise in the range of 17–220Hz, thus providing a possible explanation of the electrostatic noise observed at the inner boundary of the ring current during magnetic storms. Further, these modes can attain saturation electric fields of the order of 100–500μV∕m, and therefore, are expected to scatter O+ ions into the loss-cone giving rise to their precipitation into the atmosphere, thus contributing to the ring current decay.

Aloe ring spot, a new disease of aloe caused by Haematonectria haematococca (Berk. & Broome) Samuels & Nirenberg (anamorph: Fusarium sp.)

A ring spot disease of Aloe vera was found on leaves of potted seedlings of Aloe vera in Hachijojima and Chichijima Islands, Tokyo. From tissue of ring spot lesions, a fungus producing Fusarium-type conidia was consistently isolated. After 1 month, reddish perithecia of nectriaceous fungus had formed on the colonies of this isolate on PDA. These nectriaceous and Fusarium fungi were identified as Haematonectria haematococca and Fusarium sp., respectively. From a single ascospore isolation, the former was confirmed to be the teleomorph of the Fusarium sp. Typical ring spot lesions were reproduced by artificial inoculations using single ascospore and single conidium isolates. Inoculations of five species of genus Aloe revealed that they were highly susceptible except for A. arborescens. This is the first report of a disease on Aloe caused by H. haematococca (anamorph: Fusarium sp.) in Japan, and it was named aloe ring spot.

Angioma cavernoso del trígono ventricular: Caso clínico

The authors report on an intraventricular cavernous angioma located at the right trigone in a 25-year-old male patient presented with a predominantly intralesional haemorrhage. Neuroimaging led to an accurate preoperative diagnosis although the typical low intensity perilesional ring of gliosis and hemosiderin was not present. The lesion was microsurgically removed using an stereotactically guided posterior temporal transsulcal approach.

Technology Insight: can neuroimaging provide insights into the role of ischemia in Baló's concentric sclerosis?

Baló's concentric sclerosis (BCS) has long been considered to be a variant of multiple sclerosis. Although BCS was initially described over 100 years ago, relatively few antemortem cases have been identified, and the exact pathogenesis remains unknown. Inflammatory protective ischemic preconditioning has recently been suggested as a mechanism by which the typical concentric rings of the BCS lesion are formed. Advanced neuroimaging can provide important in vivo markers of disease progression that can assist in the diagnosis and management of patients with BCS. In this Review, we discuss evidence from longitudinal neuroimaging studies that supports the role of ischemic preconditioning in BCS.

Pulmonary tumor thrombotic microangiopathy resulting from metastatic signet ring cell carcinoma of the stomach

Pulmonary tumor thrombotic microangiopathy is an unusual malignancy-related respiratory complication characterized by multiple microthrombi and intimal myofibroblast proliferation. Its clinical manifestation is subacute respiratory failure with pulmonary hypertension. Herein is reported a case of pulmonary tumor thrombotic microangiopathy associated with gastric signet ring cell carcinoma. A 51-year-old woman with gastric cancer died of subacute respiratory failure. Autopsy showed gastric signet ring cell carcinoma with diffuse metastasis of pulmonary lymphatics and pleurae; every organ examined lacked a space-occupying tumor mass. Histologically, proliferated intimal myofibroblasts obliterated most of the pulmonary vascular lumen, and a few stenosed vascular lumina contained cancer cells. In addition, pulmonary vasculature associated with intimal proliferation contained microthrombi. Most cancer cells in the stomach and pulmonary lymphatics were typical signet ring cells, whereas those in vascular lesions were cells of poorly differentiated adenocarcinoma without mucous production. Consistent with a previous report, the latter expressed vascular endothelial growth factor (VEGF) and tissue factor (TF). The proliferated intimal myofibroblasts also expressed type 2A serotonin receptor (5-HT(2A)). These findings suggest that local expression of VEGF, TF, and 5-HT(2A) may be linked to the pathogenesis of this unusual pulmonary complication.

Nonplanar ring resonator modes: generalized Gaussian beams

Several findings on the modes of a nonplanar ring resonator have been carried out by utilizing the matrix method of generalized Gaussian beams. The widely used nonplanar ring resonator--a four-equal-sided nonplanar ring cavity with two curvature mirrors and two planar mirrors--has been chosen as an example. The overall stability maps of this typical nonplanar ring cavity with L/R ranging from 0 to infinity are calculated and described, while the total cavity length is L and the radius of the curvature mirrors is R. The stability map has also been found to have asymmetry with total image rotation rho ranging from 0 degrees to 360 degrees and 0<L/R<2. It has also been found that there still exist several stable regions in the extended region with L/R>2. The Gaussian modes of the nonplanar ring cavity have been found to have different characteristics with different design parameters such as rho and L/R. The azimuth angles of the major and minor axes of the spot size have been found to be variable with different design parameters such as rho and L/R and variable under different location of the nonplanar cavity. These interesting findings are totally different from the behavior of conventional planar stable resonators and are important to the cavity designs of nonplanar ring resonators.

Dynamic analysis of a microelectromechanical systems resonant gyroscope excited using combination parametric resonance

This paper investigates the application of parametric excitation to a resonant microelectromechanical systems (MEMS) gyroscope. The modal equations of motion of an electrostatically actuated ring are derived and shown to be coupled via the electrostatic stiffness. Such electrostatic coupling between in-plane modes of vibration permits parametric instabilities that may be exploited in a novel excitation scheme. A multiple time scale perturbation method is used to analyse the response of the ring gyroscope to the combination parametric excitations with the principal objective of separating the drive and response frequencies of the ring gyroscope. As pairs of flexural modes of the perfect ring are degenerate, the combination excitation between distinct modes demand the ring to be analysed as a four degree of freedom system. Slight mis-tuning between the otherwise degenerate modes is incorporated in the perturbation analysis. The results of the perturbation analysis are subsequently used to determine the stability boundaries for a typical ring gyroscope when excited using a sum combination resonance between the flexural modes of order 2 and 5. In this case, the ratio of the drive and response frequencies is approximately 10:1. Drive and sense configurations that enable effective parametric excitation of a desired mode are investigated. Simulation of the oscillator scheme is achieved using MATLAB Simulink and this validates the perturbation analysis. Agreement between the models within 10 per cent is demonstrated.

Cover Picture: Formation of Self‐Organized Dynamic Structure Patterns of Barium Carbonate Crystals in Polymer‐Controlled Crystallization (Angew. Chem. Int. Ed. 27/2006)

The Belousov–Zhabotinsky reaction with its typical concentric ring pattern is described for a precipitation for the first time by T. Wang, A.‐W. Xu, and H. Cölfen in their Communication on page 4451 ff. The formation and self‐organization of BaCO3 nanoparticles can be directed with a new phosphonated block copolymer: short to ultralong nanofibers and, ultimately, ring patterns are obtained. This system could help to explain natural pattern formation. The cover picture shows observed and simulated Belousov–Zhabotinsky ring patterns, as well as the molecular structure of the block copolymer.

Heat content change in the surface isothermal layer of a warm core ring in the sea east of Japan

Heat content change in the surface isothermal layer of a typical warm core ring in the sea east of Japan is described based on approximately 90 CTD profiles obtained by one profiling float. Erosion of the seasonal thermocline and development of a surface isothermal layer from the mid-summer to the early winter of 1999 are clearly seen. While heat content change between two consecutive profiles with a 35-hour time interval is much noisier, its 10-day running mean is consistent with net surface heat flux, indicating that surface heat flux dominates the temporal heat content change in the surface isothermal layer in the warm core ring.

Multifunctional photochromic spiropyran dendrimers and their relaxation behaviors of photochromism

First and second generation dendrimers that exhibit unique photochromic behavior were synthesized through multi-step reactions. Their photochromic behavior under illumination of monochromatic ultraviolet light ( λ = 365 nm) was investigated. The colorless dendritic dye solution and its film exhibit typical ring opening and E/Z geometrical transformation from spiropyran to merocyanine. The stability of photochromism in the two dendrimers was much better than that observed in the dye-attached polymer or dye-doped polymer system. Particularly, blend material system of photochromic dendrimer and photocrosslinkable dendrimer showed much better stability of the photochromism.

채소류의 토마토 반점 위조 바이러스 발생과 병징 (I)

토마토 반점위조 바이러스(Tomato spotted wilt virus; TSWV)가 2004년 경기도 안양지역에서 토마토, 고추 등을 포함한 14개 채소 작물에서 발생하였다. TSWV검정은 지표식물 검정, IC/RT-PCR, VC/RT-PCR 및 Total RNA를 이용한 RT-PCR방법을 이용하였으며, TSWV가 발생한 작물의 종류는 토마토, 방울 토마토, 고추, 시금치, 치커리, 적치커리, 적겨자, 용설채, 트레비소, 감자, 들깨, 참깨, 호박, 쌈추 이었다. 포장에서의 발생율은 토마토, 고추 등 주요 작물에서 <TEX>$30\%$</TEX>에서 <TEX>$100\%$</TEX> 발생하였으며,병징은 대부분 전형적인 원형반점이었으며, 괴저, 위조 및 심한 모자이크 병징으로 진전되었다. TSWV가 발생한 포장에서 채집한 꽃노랑 총채벌레(Frankliniella occidentalis)를 IC/RT-PCR 검정한 결과 감염율이 <TEX>$90\%$</TEX>이었다. Tomato spotted wilt virus (TSWV) occurred abruptly with a high incidence rate in 14 vegetable crops in Anyang area, Gyunggido in 2004. TSWV was identified by the symptoms on the indicator plants, immunocaptured reverse transcription-polymerase chain reaction (IC/RT-PCR), virion captured (VC)RT-PCR and RT-PCR using total RNA from the infected plants. Vegetable crops infected with TSWV included table tomato, cherry tomato, red pepper, lettuce, chicory, red leaf chicory, red mustard, dragon tongue, treviso, potato, perilla, sesame, pumpkin, and ssamchoo (hybrid of oriental cabbage and cabbage). The incidence of TSWV in fields ranged from 30 to <TEX>$100\%$</TEX>. TSWV usually produced necrosis, wilt and/or severe mosaic with typical single or double ring spots on the leaves. TSWV could be detected in Frankliniella occidentalis collected from the crops in the fields with <TEX>$90\%$</TEX> rate by IC/RT-PCR.

Transport of South Atlantic water through the passages south of Guadeloupe and across 16°N, 2000–2004

CTD, vessel-mounted ADCP and LADCP measurements in the Caribbean passages south of Guadeloupe (three repeats) and along 16°N (five repeats) were carried out between December 2000 and July 2004. The CTD data were used to calculate the contribution of South Atlantic water (SAW) in the upper 1200 m between the isopycnals σ θ = 24.5 and 27.6. Northern and southern source water masses are defined and an isopycnal mixing approach is applied. The SAW fractions are then combined with the ADCP flow field to calculate the transport of SAW into the Caribbean and across 16°N. The SAW inflow into the Caribbean through the passages south of Guadeloupe ranges from 7.6 to 11.6 Sv, which is 50–75% of the total inflow. The mean (9.1±2.2 Sv) is in the range of previous estimates. Ambiguities in the northern and southern source water masses of the salinity maximum water permitted us only to calculate the contribution of SAW from the eastern source in this water mass. We estimated the additional SAW transport by the western source to be of the order of 1.9±0.7 Sv. The calculation of the SAW transport across 16°N was hampered by the presence of several anticyclonic rings from the North Brazil Current (NBC) retroflection region, some of the rings were subsurface intensified. Provided that the rings observed at 16°N are typical rings and that all rings which are annually produced in the NBC retroflection area (6.5–8.5 per year) reach 16°N, the SAW ring transport across 16°N is calculated to 5.3±0.7 Sv. From the 5 repeats at 16°N, only two showed a net northward flow, suggesting that the mean northward SAW transport is dominated by ring advection. The joint SAW transports of the Caribbean inflow (9.1 Sv) and the flow across 16°N (5.3 Sv) sum up to 14.4 Sv. The transport increases to 16.3 Sv if the additional SAW transport from the western source of SMW (1.9±0.7 Sv) is included. These transport estimates and the following implications depend strongly on the assumption that the surface water in the Caribbean inflow is of South Atlantic origin. The transport estimates are, however, in the range of the inverse model calculations for the net cross-hemispheric flow. About 30–40% of this transport is intermediate water from the South Atlantic, presumably supporting studies which found the contributions of intermediate and upper warm water to be of a comparable magnitude. For the upper warm water ( σ θ < 27.1 ), the Caribbean inflow seems to be the major path (7.9±1.6 Sv), the ring induced transport across 16°N is about 30% of that value. The intermediate water transport across 16°N was calculated to be 2.3–3.6 Sv, the inflow into the Caribbean is slightly smaller (1.5–2.4 Sv).