Estudio del efecto de quitinasas recombinantes como potenciadoras de la actividad insecticida de un aislamiento de Beauveria bassiana para el control de Diatraea saccharalis

Las quitinasas son enzimas hidrolíticas provenientes de diferentes fuentes biológicas. En virus y hongos entomopatógenos, las quitinasas han sido reportadas como importantes factores de virulencia que cortan la estructura de la quitina presente en las dos principales barreras de protección de los insectos: la cutícula y la matriz peritrófica del intestino medio. Con el fin de estudiar el efecto de quitinasas recombinantes en la actividad insecticida de Beauveria bassiana sobre larvas de Diatraea saccharalis, en este trabajo se clonaron y expresaron en E. coli los marcos abiertos de lectura que codifican para las quitinasas Chit37 y Chit2A provenientes de los aislamientos colombianos Bv062 de B. bassiana y VG008 del granulovirus de Spodoptera frugiperda, respectivamente. La quitinasa fúngica recombinante (rChit37) purificada a partir de la fracción soluble del cultivo de células BL21-DE3, presentó actividad quitinolítica dual de tipo quitobiosidasa y endoquitinasa (EC 3.2.2.14) bajo condiciones óptimas de 45°C y pH 5.0. La rChit37 purificada potenció la actividad insecticida de B. bassiana sobre larvas de segundo instar de D. saccharalis; cuando se adicionó a una concentración de 300 µg/mL en una suspensión de 1x106 conidios/mL, se evidenció una reducción de 46% y 68% en los tiempos letales (TL50 y TL90) y un incremento de la eficacia en 61%. La proteína viral recombinante (rChit2A) presentó un dominio de unión a quitina en su secuencia, sin embargo, no se observó dominio catalítico, lo que se corroboró con la ausencia de actividad enzimática. Los hallazgos de este trabajo proveen una prueba concepto inicial para el estudio de quitinasas recombinantes en el desarrollo de futuras estrategias de potenciación de hongos entomopatógenos con potencial en el control biológico.Chitinases are hydrolytic enzymes from different biological sources. In viruses and entomopathogenic fungi, chitinases have been reported as important virulence factors that cleave the chitin structure present in the two main protective barriers of insects: the cuticle and the peritrophic matrix of the midgut. In the present work, the open reading frames encoding chitinases Chit37 and Chit2A in the Colombian isolates Bv062 and VG008 of B. bassiana and the granulovirus of Spodoptera frugiperda, respectively, were cloned and expressed in E. coli to study the effect of recombinant chitinases on the insecticidal activity of Beauveria bassiana on larvae of Diatraea saccharalis. The recombinant fungal chitinase (rChit37) purified from the soluble fraction of the BL21-DE3 cell culture, displayed dual chitinolytic activity of the quitobiosidase and endochitinase types (EC 3.2.2.14) under optimal conditions of 45°C and pH 5.0. The purified rChit37 enhanced the insecticidal activity of B. bassiana on second instar larvae of D. saccharalis; a reduction of 46% and 68% in lethal times (TL50 and TL90) and an increase in efficacy by 61% was observed when added at a 300 μg/mL concentration in a suspension of 1x106 conidia/mL. The recombinant viral protein (rChit2A) showed a chitin binding domain in its sequence, however, no catalytic domain was observed, which was in agreement with the lack of enzymatic activity. The findings of this work provide an initial proof of concept for the study of recombinant chitinases in the development of future strategies of entomopathogenic fungal enhancement for biological control.Corporación Colombiana de investigación agropecuaria AGROSAVIAMaestrí

Plasmonic trapping with realistic dipole nanoantennas: Analysis of the detection limit

We use numerical simulations based on the surface integral technique to study the detection limit of plasmonic trapping with realistic dipole antennas. The induced plasmon resonance shift due to the coupling between an antenna and a nanoparticle is studied for different antennas geometries, different positions, sizes, and materials for the trapped nanoparticle. The shift of the antenna resonance is found to be linear with the near-field intensity enhancement caused by the antenna and further dependents on the volume and refractive index of the trapped nanoparticle. Detection limit of 5 nm for plasmonic particles and 6.5 nm for high index dielectrics is reported

Detecting the trapping of small metal nanoparticles in the gap of nanoantennas with optical second harmonic generation

The second harmonic generation from gold nanoparticles trapped into realistic and idealized gold nanoantennas is numerically investigated using a surface integral equations technique. It is observed that the presence of a nanoparticle in the nanoantenna gap dramatically modifies the second harmonic intensity scattered into the far-field. These results clearly demonstrate that second harmonic generation is a promising alternative to the conventional linear optical methods for the detection of trapping events at the nanoscale

Meta-análisis de infección con Leptospira en gatos domésticos

La leptospirosis es una zoonosis causada por bacterias del género Leptospira, cuyos principales hospedadores son ratas, perros y ganado. El rol de los gatos domésticos (Felis catus) en la transmisión es menos claro, considerándose factores de protección por sus hábitos de caza, aunque también pueden desarrollar infecciones y excretar leptospiras.Trabajo publicado en Cagliada, Maria del Pilar Lilia y Galosi, Cecilia Mónica (comps.). I Congreso de Microbiología Veterinaria. Libro de resúmenes. La Plata: Facultad de Ciencias Veterinarias, 2021.Facultad de Ciencias Veterinaria

Mechanisms of Fano Resonances in Coupled Plasmonic Systems

Fano resonances in hybridized systems formed from the interaction of bright modes only are reported. Despite precedent works, we demonstrate theoretically and experimentally that Fano resonances can be obtained by destructive interference between two bright dipolar modes out of phase. A simple oscillator model is provided to predict and fit the far-field scattering. The predictions are verified with numerical calculations using a surface integral equation method for a wide range of geometrical parameters. The validity of the model Is then further demonstrated with experimental dark-field scattering measurements on actual nanostructures in the visible range. A remarkable set of properties like crossings, avoided crossings, Inversion of subradiant and superradiant modes and a plasmonic equivalent of a bound state in the continuum are presented. The nanostructure, that takes advantage of the combination of Fano resonance and nanogap effects, also shows high tunability and strong near-field enhancement. Our study provides a general understanding of Fano resonances as well as a simple tool for engineering their spectral features

Resonant-Body Fin-FETs with sub-nW power consumption

This paper presents, for the first time, experimental evidence on resonant-body Fin-FETs (RB-FinFET) with two independent lateral gates, operated from weak to strong inversion, which enables unique trade-off between power consumption and gain. Resonance frequencies from 25 MHz to 80 MHz with quality factors of the order of 3000 and motional resistances of the order of tens of kOhm are demonstrated with a mixer mode measurement technique, dedicated to ultra-scaled resonators. The power consumption of the active resonators can be reduced in weak inversion of the RB-FinFET well below 1nW, which is a record value compared to any prior active NEM resonator

Surface nanophotonics with Bloch waves on dielectric multilayers

Planar mutilayers sustaining either TE or TM polarized Bloch Surface Waves (BSWs) offer new opportunities for management of light at the nanoscale. We will discuss how BSWs can be exploited in guiding and confining light on nanometric relieves, enhancing fluorescence emission and providing additional features for plasmonic nano-antennas

On the characteristics of the wake of a wind turbine undergoing large motions caused by a floating structure: an insight based on experiments and multi-fidelity simulations from the OC6 Phase III Project

This study reports the results of the second round of analyses of the OC6 project Phase III. While the first round investigated rotor aerodynamic loading, here focus is given to the wake behavior of a floating wind turbine under large motion. Wind tunnel experimental data from the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project are compared with the results of simulations provided by participants with methods and codes of different levels of fidelity. The effect of platform motion both on the near and the far wake is investigated. More specifically, the behavior of tip vortices in the near wake is evaluated through multiple metrics, such as streamwise position, core radius, convection velocity, and circulation. Additionally, the onset of velocity oscillations in the far wake is analyzed because this can have a negative effect on stability and loading of downstream rotors. Results in the near wake for unsteady cases confirm that simulations and experiments tend to diverge from the expected linearized quasi-steady behavior when the rotor reduced frequency increases over 0.5. Additionally, differences across the simulations become significant, suggesting that further efforts are required to tune the currently available methodologies in order to correctly evaluate the aerodynamic response of a floating wind turbine in unsteady conditions. Regarding the far wake, it is seen that, in some conditions, numerical methods over-predict the impact of platform motion on the velocity fluctuations. Moreover, results suggest that, different from original expectations about a faster wake recovery in a floating wind turbine, the effect of platform motion on the far wake seems to be limited or even oriented to the generation of a wake less prone to dissipation.</p

Clinical Presentation and Outcomes of Kawasaki Disease in Children from Latin America: A Multicenter Observational Study from the REKAMLATINA Network

Objetivos: Describir la presentación clínica, el manejo y los resultados de la enfermedad de Kawasaki (EK) en Latinoamérica y evaluar los indicadores pronósticos tempranos de aneurisma de la arteria coronaria (AAC). Diseño del estudio: Se realizó un estudio observacional basado en el registro de la EK en 64 centros pediátricos participantes de 19 países latinoamericanos de forma retrospectiva entre el 1 de enero de 2009 y el 31 de diciembre de 2013, y de forma prospectiva desde el 1 de junio de 2014 hasta el 31 de mayo de 2017. Se recopilaron datos demográficos, clínicos y de laboratorio iniciales. Se utilizó una regresión logística que incorporaba factores clínicos y la puntuación z máxima de la arteria coronaria en la presentación inicial (entre 10 días antes y 5 días después de la inmunoglobulina intravenosa [IGIV]) para desarrollar un modelo pronóstico de AAC durante el seguimiento (>5 días después de la IGIV). Resultados: De 1853 pacientes con EK, el ingreso tardío (>10 días tras el inicio de la fiebre) se produjo en el 16%, el 25% tuvo EK incompleta y el 11% fue resistente a la IGIV. Entre los 671 sujetos con puntuación z de la arteria coronaria notificada durante el seguimiento (mediana: 79 días; IQR: 36, 186), el 21% presentaba AAC, incluido un 4% con aneurismas gigantes. Un modelo pronóstico simple que utilizaba sólo una puntuación z de la arteria coronaria máxima ≥2,5 en la presentación inicial fue óptimo para predecir la AAC durante el seguimiento (área bajo la curva: 0,84; IC del 95%: 0,80, 0,88). Conclusiones: De nuestra población latinoamericana, la puntuación z de la arteria coronaria ≥2,5 en la presentación inicial fue el factor pronóstico más importante que precedió a la AAC durante el seguimiento. Estos resultados resaltan la importancia de la ecocardiografía temprana durante la presentación inicial de la EK. © 2023 Los autoresObjectives: To describe the clinical presentation, management, and outcomes of Kawasaki disease (KD) in Latin America and to evaluate early prognostic indicators of coronary artery aneurysm (CAA). Study design: An observational KD registry-based study was conducted in 64 participating pediatric centers across 19 Latin American countries retrospectively between January 1, 2009, and December 31, 2013, and prospectively from June 1, 2014, to May 31, 2017. Demographic and initial clinical and laboratory data were collected. Logistic regression incorporating clinical factors and maximum coronary artery z-score at initial presentation (between 10 days before and 5 days after intravenous immunoglobulin [IVIG]) was used to develop a prognostic model for CAA during follow-up (>5 days after IVIG). Results: Of 1853 patients with KD, delayed admission (>10 days after fever onset) occurred in 16%, 25% had incomplete KD, and 11% were resistant to IVIG. Among 671 subjects with reported coronary artery z-score during follow-up (median: 79 days; IQR: 36, 186), 21% had CAA, including 4% with giant aneurysms. A simple prognostic model utilizing only a maximum coronary artery z-score ≥2.5 at initial presentation was optimal to predict CAA during follow-up (area under the curve: 0.84; 95% CI: 0.80, 0.88). Conclusion: From our Latin American population, coronary artery z-score ≥2.5 at initial presentation was the most important prognostic factor preceding CAA during follow-up. These results highlight the importance of early echocardiography during the initial presentation of KD. © 2023 The Author(s