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Understanding a Core Pilin of the Type IVa Pili of Acidithiobacillus thiooxidans, PilV
( Araceli Hernández-sánchez ),( Edgar D. Páez-pérez ),( Elvia Alfaro-saldaña ),( Vanesa Olivares-illana ),( J. Viridiana García-meza ) 한국미생물생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.3
Pilins are protein subunits of pili. The pilins of type IV pili (T4P) in pathogenic bacteria are well characterized, but anything is known about the T4P proteins in acidophilic chemolithoautotrophic microorganisms such as the genus Acidithiobacillus. The interest in T4P of A. thiooxidans is because of their possible role in cell recruitment and bacterial aggregation on the surface of minerals during biooxidation of sulfide minerals. In this study we present a successful ad hoc methodology for the heterologous expression and purification of extracellular proteins such as the minor pilin PilV of the T4P of A. thiooxidans, a pilin exposed to extreme conditions of acidity and high oxidation-reduction potentials, and that interact with metal sulfides in an environment rich in dissolved minerals. Once obtained, the model structure of A. thiooxidans PilV revealed the core basic architecture of T4P pilins. Because of the acidophilic condition, we carried out in silico characterization of the protonation status of acidic and basic residues of PilV in order to calculate the ionization state at specific pH values and evaluated their pH stability. Further biophysical characterization was done using UV-visible and fluorescence spectroscopy and the results showed that PilV remains soluble and stable even after exposure to significant changes of pH. PilV has a unique amino acid composition that exhibits acid stability, with significant biotechnology implications such as biooxidation of sulfide minerals. The biophysics profiles of PilV open new paradigms about resilient proteins and stimulate the study of other pilins from extremophiles.
Splenic myeloid metaplasia in warm autoimmune hemolytic anemia (wAIHA): a retrospective study
Víctor Manuel Anguiano-Álvarez,Alonso Hernández-Company,Nashla Hamdan-Pérez,Daniel Montante-M,Diego A. Zúñiga-Tamayo,Sergio Rodríguez-Rodríguez,Alan Pomerantz,Elena J. Tuna-Aguilar 대한혈액학회 2018 Blood Research Vol.53 No.1
BackgroundSplenic myeloid metaplasia (SMM) is a kind of extramedullary hematopoiesis, whereasits clinical significance in wAIHA remains unclear. The aim of this study is evaluating thefrequency and clinical characteristics of SMM, compared with splenic-congestion (SC). MethodsWe included patients with wAIHA treated in a Mexican tertiary hospital between January1992 and December 2015. All patients received steroids as first-line treatment and splenectomyas second-line treatment. ResultsAmong the thirty-six splenectomized patients, 15 (41.6%) and 21 (58.4%) were diagnosedas SMM and SC, respectively. No differences were found in clinical characteristicsbetween two groups. SMM patients showed lower platelet count (147×109/L vs. 240×109/L, P=0.02) and higher presence of anti-dsDNA antibodies (40% vs. 4.7%,P=0.01) than SC patients. Although the complete response (CR) rate with first-line treatmentwas lower in SMM patients (13.3% vs. 47.6%; P=0.04), post-splenectomy mediandisease-free-survival (DFS) was longer (16.2 mo vs. 5.1 mo; P=0.19). Univariate/multivariateanalysis showed that achieving CR during first-line treatment (OR 0.3, 95% CI:0.03‒0.94, P=0.03) and higher platelet count (OR 0.99, 95% CI: 0.98‒0.99, P=0.03)were protective factors for SMM; and anti-dsDNA titer higher than 9.6 IU/dL was a riskfactor for SMM (OR 2.76, 95% CI: 1.48‒5.14, P<0.001). ConclusionThe wAIHA patients with SMM have different biological profiles with those without SMM. This study is the first trial evaluating the significance of histopathological spleen findingsand their association with rheumatologic profile.
C.J. González-Pérez1,I. Vargas-Arispuro,E. Aispuro-Hernández,C.L. Aguilar-Gil,Y.E. Aguirre-Guzmán,A. Castillo,A. Hernández-Mendoza,J.F. Ayala-Zavala,M.A. Martínez-Téllez1 한국미생물·생명공학회 2019 한국미생물·생명공학회지 Vol.47 No.2
The consumption of fresh vegetables has been related to recurrent outbreaks of foodborne diseases (FBD) worldwide. Therefore, the development of effective alternative technologies is necessary to improve the safety of these products. This study aimed to isolate and identify epiphytic lactic acid bacteria (LAB) from fresh fruits and leafy vegetables and characterize their antagonistic capacity due to their ability to produce bacteriocins or antibacterial compounds. For this, 92 LAB isolates from fruits and leafy vegetables were screened for antagonistic activity. Two strains with the highest and broadest antagonistic activities were selected for further characterization; one from cantaloupe melon (strain CM175) and one from cilantro leaves (strain C15). The cell-free supernatants (CFS) of CM175 and C15 were found to exhibit antagonistic activity against FBD-causing pathogens. The CM175 and C15 strains were identified as Pediococcus pentosaceus and Lactobacillus graminis, respectively. Notably, the P. pentosaceus CM175 CFS stopped the growth of Salmonella Typhimurium, Salmonella Saintpaul, Staphylococcus aureus, and Listeria monocytogenes, and delayed Escherichia coli O157:H7 growth. Moreover, L. graminis C15 CFS delayed the growth of all indicator pathogens, but did not completely stop it. Organic acids and bacteriocin-like molecules were determined to be possibly exerting the observed antagonistic activity of the identified LAB strains. Thus, application of the antagonistic compounds produced by Pediococcus pentosaceus and Lactobacillus graminis could be a novel and ecological strategy in developing antimicrobial biopreservatives for the food industry and mitigating FBD by reducing the biological contamination in fruit and vegetable orchards, mainly via their potential in controlling both gram-negative and gram-positive pathogenic bacteria.
Thermal shock resistance of mullite/Sr-celsian/zirconia composites
Rodríguez-Salazar P.,Almanza-Robles J. M.,Cortés-Hernández D. A.,Escobedo-Bocardo J. C. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.6
The thermal shock resistance of novel mullite /Sr-celsian /zirconia composites was studied. The eff ect of the Sr-celsian (15, 20, 25 wt.%) and ZrO 2 (5, 15, 25 wt.%) amounts on the thermal shock resistance, was evaluated. The composites were obtained at 1450 °C. Thermal shock resistance was performed by heating samples up to a selected temperature (∆ T = 200–1000 °C) and then suddenly immersed in water. After testing, the bending strength was evaluated and the results were statistically analyzed using Minitab with a confi dence level of 0.05. Pareto charts showed that Sr-celsian and zirconia content have the highest infl uence on fl exural strength after thermal shock. The highest thermal shock resistance was obtained for the composites with the highest amount of zirconia and Sr-celsian. Most of the composites showed a decrease in strength of around 75%. The strength of the composites with 20 or 25 wt.% of celsian and 25 wt.% zirconia increased at ∆ T of 1000 °C. The Pareto chart for these composites showed that zirconia has the highest eff ect on strength. A change in expansion is shown between 800 and 900 °C, indicating the transformation of monoclinic to tetragonal zirconia. This transformation generates microc- racks that defl ect cracks generated during thermal stress. Also, residual stresses are generated during cooling which plays a role in absorbing the energy of a generated crack. The strontium celsian forms an interlocked microstructure that improves strength. These composites are promising materials for applications in which sudden and extreme temperature changes occur.
Chun, E. J.,Cvetič,, G.,Dev, P. S. B.,Drewes, M.,Fong, C. S.,Garbrecht, B.,Hambye, T.,Harz, J.,Herná,ndez, P.,Kim, C. S.,Molinaro, E.,Nardi, E.,Racker, J.,Rius, N.,Zamora-Saa, J. World Scientific Publishing Company 2018 International journal of modern physics. A, Partic Vol.33 No.6
<P>The focus of this paper lies on the possible experimental tests of leptogenesis scenarios. We consider both leptogenesis generated from oscillations, as well as leptogenesis from out-of-equilibrium decays. As the Akhmedov-Rubakov-Smirnov (ARS) mechanism allows for heavy neutrinos in the GeV range, this opens up a plethora of possible experimental tests, e.g. at neutrino oscillation experiments, neutrinoless double beta decay, and direct searches for neutral heavy leptons at future facilities. In contrast, testing leptogenesis from out-of-equilibrium decays is a quite difficult task. We comment on the necessary conditions for having successful leptogenesis at the TeV-scale. We further discuss possible realizations and their model specific testability in extended seesaw models, models with extended gauge sectors, and supersymmetric leptogenesis. Not being able to test high-scale leptogenesis directly, we present a way to falsify such scenarios by focusing on their washout processes. This is discussed specifically for the left-right symmetric model and the observation of a heavy <TEX>$ W_{R}$</TEX>, as well as model independently when measuring <TEX>$ \Updelta L = 2$</TEX> washout processes at the LHC or neutrinoless double beta decay.</P>
Knight, A.L.,Barros-Parada, W.,Bosch, D.,Escudero-Colomar, L.A.,Fuentes-Contreras, E.,Herná,ndez-Sá,nchez, J.,Yung, C.,Kim, Y.,Kovanci, O.B.,Levi, A.,Lo, P.,Molinari, F.,Valls, J.,Gemeno, Cambridge University Press 2015 Bulletin of entomological research Vol.105 No.1
<B>Abstract</B><P>The response of <I>Grapholita molesta</I> (Busck) males to three-component sex pheromone blends containing a 100% ratio of the major sex pheromone component, (<I>Z</I>)-8-dodecenyl acetate and a 10% ratio of (<I>Z</I>)-8-dodecenol, but with varying ratios of (<I>E</I>)-8-dodecenyl acetate (0.4, 5.4, 10.4, 30.4, and 100.1% <I>E</I>-blends) was tested with populations in eight stone and pome fruit orchards in Europe, Asia, and North and South America. Traps baited with the 5.4% <I>E</I>-blend caught significantly more males than traps with any other blend with all populations. Significantly more males were caught in traps baited with the 10.4% <I>E</I>-blend than in traps with the remaining blends, except with the 0.4% <I>E-</I>blend in Turkey. Significant differences in male moth catches occurred between the other blends with the 0.4>30.4% <I>E-</I>blend, and the 30.4>100.1% <I>E-</I>blend. Male moth catches with the 100.1% <I>E</I>-blend only differed from the hexane control in Chile. No apparent differences were noted to these blends in populations collected from pome or stone fruits. Flight tunnel assays to synthetic blends with a subset of populations were similar to the field results, but the breadth of the most attractive <I>E-</I>blends was wider. Flight tunnel assays also demonstrated a high level of male-female cross-attraction among field-collected populations. Female gland extracts from field-collected populations did not show any significant variation in their three-component blends. The only exceptions in these assays were that long-term laboratory populations were less responsive and attractive, and produced different blend ratios of the two minor components than recently collected field populations.</P>
Kim, K. H.,Watson, Dan M.,Manoj, P.,Forrest, W. J.,Furlan, Elise,Najita, Joan,Sargent, Benjamin,Herná,ndez, Jesú,s,Calvet, Nuria,Adame, Lucí,a,Espaillat, Catherine,Megeath, S. T.,Muz American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.226 No.1
<P>We present our investigation of 319 Class II objects in Orion A observed by Spitzer/IRS. We also present the follow-up observations of 120 of these Class II objects in Orion A from the Infrared Telescope Facility/SpeX. We measure continuum spectral indices, equivalent widths, and integrated fluxes that pertain to disk structure and dust composition from IRS spectra of Class II objects in Orion A. We estimate mass accretion rates using hydrogen recombination lines in the SpeX spectra of our targets. Utilizing these properties, we compare the distributions of the disk and dust properties of Orion A disks with those of Taurus disks with respect to position within Orion A (Orion Nebular Cluster [ONC] and L1641) and with the subgroups by the inferred radial structures, such as transitional disks (TDs) versus radially continuous full disks (FDs). Our main findings are as follows. (1) Inner disks evolve faster than the outer disks. (2) The mass accretion rates of TDs and those of radially continuous FDs are statistically significantly displaced from each other. The median mass accretion rate of radially continuous disks in the ONC and L1641 is not very different from that in Taurus. (3) Less grain processing has occurred in the disks in the ONC compared to those in Taurus, based on analysis of the shape index of the 10 mu m silicate feature (F-11.3/F-9.8). (4) The 20-31 mu m continuum spectral index tracks the projected distance from the most luminous Trapezium star, theta(1) Ori C. A possible explanation is UV ablation of the outer parts of disks.</P>
Active tailoring of nanoantenna plasmonic fields using few-cycle laser pulses
Choi, S.,Ciappina, M. F.,Pé,rez-Herná,ndez, J. A.,Landsman, A. S.,Kim, Y.-J.,Kim, S. C.,Kim, D. American Physical Society 2016 Physical Review A Vol.93 No.2
<P>Plasmonic nanoatennas are a versatile tool for coherently manipulating light on a nanoscale by confining electric fields of the driving laser into subwavelength volumes, thereby significantly enhancing electric near fields. It is normally assumed that the time-dependent spectral properties of these near fields are independent of the duration of the driving laser pulse. Here we show that when a few-cycle laser pulse shines on a bow-tie nanoantenna, its spectral properties are dramatically modified, as evidenced by a large shift of the center wavelength of the near field, relative to the driving laser. In addition, for certain geometries, a second color appears in the near field, creating conditions for generation of an isolated attosecond pulse at megahertz repetition rate. Our results open the door to frequency-tunable ultrafast sources at nanometer scale without tuning the frequency of the driving laser.</P>