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1.
Pest Manag Sci ; 80(6): 2796-2803, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38327120

RESUMEN

BACKGROUND: Practical resistance of Helicoverpa zea to Cry proteins has become widespread in the US, making Vip3Aa the only effective Bacillus thuringiensis (Bt) protein for controlling this pest. Understanding the genetic basis of Vip3Aa resistance in H. zea is essential in sustaining the long-term efficacy of Vip3Aa. The objectives of this study were to characterize the inheritance of Vip3Aa resistance in four distinct field-derived H. zea strains (M1-RR, AC4-RR, R2-RR and R15-RR), and to test for shared genetic basis among these strains and a previously characterized Texas resistant strain (LT#70-RR). RESULTS: Maternal effects and sex linkage were absent, and the effective dominance level (DML) was 0.0 across Vip3Aa39 concentrations ranging from 1.0 to 31.6 µg cm-2, in all H. zea resistant strains. Mendelian monogenic model tests indicated that Vip3Aa resistance in each of the four strains was controlled by a single gene. However, interstrain complementation tests indicated that three distinct genetic loci are involved in Vip3Aa resistance in the five resistant H. zea strains: one shared by M1-RR and LT#70-RR; another shared by R2-RR and R15-RR; and a distinct one for AC4-RR. CONCLUSION: Results of this study indicate that Vip3Aa resistance in all H. zea strains was controlled by a single, recessive and autosomal gene. However, there were three distinct genetic loci associated with Vip3Aa resistance in the five resistant H. zea strains. The information generated from this study is valuable for exploring mechanisms of Vip3Aa resistance, monitoring the evolution of Vip3Aa resistance, and devising effective strategies for managing Vip3Aa resistance in H. zea. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Asunto(s)
Proteínas Bacterianas , Resistencia a Medicamentos , Mariposas Nocturnas , Mariposas Nocturnas/efectos de los fármacos , Mariposas Nocturnas/genética , Bacillus thuringiensis/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/farmacología , Resistencia a Medicamentos/genética , Control de Plagas/métodos , Dosificación Letal Mediana , Prueba de Complementación Genética , Genes Recesivos/genética , Animales
2.
Nanomaterials (Basel) ; 13(9)2023 Apr 25.
Artículo en Inglés | MEDLINE | ID: mdl-37177005

RESUMEN

Within the framework of effective mass theory, we investigate the effects of spin-orbit interaction (SOI) and Zeeman splitting on the electronic properties of an electron confined in GaAs single quantum rings. Energies and envelope wavefunctions in the system are determined by solving the Schrödinger equation via the finite element method. First, we consider an inversely quadratic model potential to describe electron confining profiles in a single quantum ring. The study also analyzes the influence of applied electric and magnetic fields. Solutions for eigenstates are then used to evaluate the linear inter-state light absorption coefficient through the corresponding resonant transition energies and electric dipole matrix moment elements, assuming circular polarization for the incident radiation. Results show that both SOI effects and Zeeman splitting reduce the absorption intensity for the considered transitions compared to the case when these interactions are absent. In addition, the magnitude and position of the resonant peaks have non-monotonic behavior with external magnetic fields. Secondly, we investigate the electronic and optical properties of the electron confined in the quantum ring with a topological defect in the structure; the results show that the crossings in the energy curves as a function of the magnetic field are eliminated, and, therefore, an improvement in transition energies occurs. In addition, the dipole matrix moments present a non-oscillatory behavior compared to the case when a topological defect is not considered.

3.
Nanomaterials (Basel) ; 13(3)2023 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-36770510

RESUMEN

A theoretical analysis of optical properties in a ZnS/CdS/ZnS core/shell/shell spherical quantum dot was carried out within the effective mass approximation. The corresponding Schrödinger equation was solved using the finite element method via the 2D axis-symmetric module of COMSOL-Multiphysics software. Calculations included variations of internal dot radius, the application of electric and magnetic fields (both oriented along z-direction), as well as the presence of on-center donor impurity. Reported optical properties are the absorption and relative refractive index change coefficients. These quantities are related to transitions between the ground and first excited states, with linearly polarized incident radiation along the z-axis. It is found that transition energy decreases with the growth of internal radius, thus causing the red-shift of resonant peaks. The same happens when the external magnetic field increases. When the strength of applied electric field is increased, the opposite effect is observed, since there is a blue-shift of resonances. However, dipole matrix moments decrease drastically with the increase of the electric field, leading to a reduction in amplitude of optical responses. At the moment impurity effects are activated, a decrease in the value of the energies is noted, significantly affecting the ground state, which is more evident for small internal radius. This is reflected in an increase in transition energies.

4.
Insects ; 14(2)2023 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-36835730

RESUMEN

Helicoverpa zea is a major target pest of Bt crops expressing Cry and/or Vip3Aa proteins in the U.S.A. Widespread practical resistance of H. zea to the Cry1 and Cry2 proteins makes Vip3Aa the only effective Bt protein against this pest. Understanding the frequency of resistance alleles against Vip3Aa in field populations of H. zea is crucial for resistance management and the sustainability of Vip3Aa technology. Using a modified F2 screen method by crossing susceptible laboratory female moth with feral male moth of H. zea, we successfully screened a total of 24,576 neonates from 192 F2 families of H. zea collected from Arkansas, Louisiana, Mississippi, and Tennessee during 2019-2020. We found five F2 families containing ≥3rd instar survivors on the diagnostic concentration of 3.0 µg/cm2 Vip3Aa39. Dose-response bioassays confirmed the high levels of Vip3Aa resistance in these F2 families, with an estimated resistance ratio of >909.1-fold relative to the susceptible strain. The estimated resistance allele frequency against Vip3Aa in H. zea for these four southern states is 0.0155 with a 95% CI of 0.0057-0.0297. These data should provide critical information for understanding the risks of Vip3Aa resistance in H. zea and help design appropriate resistance management strategies for the sustainability of the Vip3Aa technology.

5.
J Econ Entomol ; 116(2): 289-296, 2023 04 24.
Artículo en Inglés | MEDLINE | ID: mdl-36610074

RESUMEN

Evaluating the frequency of resistance alleles is important for resistance management and sustainable use of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis. Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a major crop pest in the United States that has evolved practical resistance to the crystalline (Cry) proteins in Bt corn and cotton. The standard F2 screen for estimating resistance allele frequency does not work well for H. zea because successful single-pair matings are rare. In this study, we developed and implemented a modified F2 screen for H. zea that generates F1 progeny by crossing three laboratory susceptible female moths with one feral male moth instead of single-pair crosses. During 2019-2020, we used this modified method to establish 192 F2 families from 623 matings between susceptible females and feral males from Arkansas, Louisiana, Mississippi, and Tennessee. From each F2 family, we screened 128 neonates against discriminating concentrations of Cry1Ac and Cry2Ab in diet overlay bioassays. Based on these discriminating concentration bioassays, families were considered positive for resistance if at least five larvae survived to second instar, including at least one to third instar. The percentage of positive families was 92.7% for Cry1Ac and 38.5% for Cry2Ab, which yields an estimated resistance allele frequency (with 95% confidence interval) of 0.722 (0.688-0.764) for Cry1Ac and 0.217 (0.179-0.261) for Cry2Ab. The modified F2 screen developed and implemented here may be useful for future resistance monitoring studies of H. zea and other pests.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Femenino , Masculino , Animales , Zea mays , Endotoxinas , Toxinas de Bacillus thuringiensis , Resistencia a los Insecticidas , Proteínas Bacterianas , Proteínas Hemolisinas , Mariposas Nocturnas/genética , Larva , Frecuencia de los Genes , Plantas Modificadas Genéticamente
6.
Pest Manag Sci ; 78(10): 4333-4339, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35750998

RESUMEN

BACKGROUND: Pyramided Bacillus thuringiensis (Bt) crops producing multiple Bt proteins with different modes of action are widely planted in the United States. Helicoverpa zea is a major target pest of pyramided Bt crops and has evolved practical resistance to both Cry1 and Cry2 proteins in some regions of U.S. However, little information is available regarding redundant killing and the dominance of resistance for insects possessing multiple resistance on pyramided Bt crops. In this study, we evaluated redundant killing and the dominance of resistance for H. zea strains resistant to Cry1 or Cry1 + Cry2 on pyramided Bt corn and cotton. RESULTS: We found that the Cry1-resistant H. zea was incompletely dominant on Cry1Ac + Cry1F cotton. Pyramided crops producing Cry2 and/or Vip3Aa proteins showed a complete redundant killing against the Cry1-resistant H. zea. The Cry1 + Cry2-resistant H. zea displayed incompletely recessive to completely dominant resistance on pyramided Bt crops containing Cry1 and/or Cry2 proteins. The redundant killing was complete for the Cry1 + Cry2-resistant H. zea on pyramided Bt crops producing Vip3Aa protein. CONCLUSION: The dominant resistance of Cry1 and Cry2 in H. zea on pyramided Bt crops deviates from the assumption of functionally recessive resistance underlying the high-dose refuge strategy. However, the assumptions of complete redundant killing are achieved for both Cry1- and Cry1 + Cry2-resistant H. zea on pyramided Bt crops. These results suggest that the pyramided strategy could be valuable for increasing the durability of Bt technology for managing H. zea, a pest with inherently low susceptibility against Cry proteins. © 2022 Society of Chemical Industry.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Animales , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/farmacología , Productos Agrícolas/genética , Productos Agrícolas/metabolismo , Endotoxinas/genética , Endotoxinas/metabolismo , Endotoxinas/farmacología , Gossypium/genética , Gossypium/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/farmacología , Resistencia a los Insecticidas/genética , Larva , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Zea mays/genética , Zea mays/metabolismo
7.
Pest Manag Sci ; 78(8): 3260-3265, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35474413

RESUMEN

BACKGROUND: Seed mixture strategy can guarantee the compliance of planting non-Bt crops to host the susceptible insects for resistance management. However, pollen movement between Bt and non-Bt corn in the mixed plantings could reduce the efficacy of this strategy for ear-feeding insects. Few studies have evaluated the effects of cross-pollination among non-Bt and pyramided Bt corn in seed mixtures on the resistance development of insects possessing multiple resistances. Here, we provided the first study to investigate whether cross-pollination in mixed plantings of pyramided Bt corn producing Cry1A.105 and Cry2Ab2 would increase the dominance of resistance of dual-gene resistant populations of Helicoverpa zea, a target of pyramided Bt corn and cotton in the USA. RESULTS: We compared the survival and development of susceptible, dual-gene resistant (resistance to both Cry1 and Cry2 proteins) and heterozygous genotypes of H. zea in the laboratory on non-Bt and pyramided Bt corn ears collected from mixed plantings and structured plantings in the field. We found higher fitness for F1 heterozygous insects than for the susceptible insects of H. zea on both pyramided Bt corn and non-Bt corn in the mixed plantings. CONCLUSION: These results suggest that cross-pollination in mixed plantings will significantly increase the dominance of resistance by supporting survival of heterozygous insects for dual-gene resistant populations of H. zea, and therefore accelerate evolution of resistance to pyramided Bt crops. © 2022 Society of Chemical Industry.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Animales , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Proteínas Bacterianas/farmacología , Productos Agrícolas/genética , Endotoxinas/farmacología , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/farmacología , Resistencia a los Insecticidas/genética , Larva/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Polinización , Semillas/metabolismo , Zea mays/genética , Zea mays/metabolismo
8.
Pediatr Pulmonol ; 57(5): 1339-1347, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35224889

RESUMEN

BACKGROUND AND OBJECTIVES: Accurate and readily available biomarkers to predict the clinical course of bronchiolitis would enable enhanced decision-making in this setting. We explored the relationship of several biochemical parameters available at the pediatric emergency care setting with the need of advanced respiratory support (ARS): continuous positive airway pressure (CPAP), biphasic positive airway pressure (BiPAP), or invasive mechanical ventilation (MV) in bronchiolitis. METHODS: Single-center, prospective, observational, including infants aged less than 12 months diagnosed with acute bronchiolitis at the Pediatric Emergency Department. Determination of plasmatic values of several laboratory tests was performed at the time of hospital admission. Multivariate logistic analysis identified independent predictors for need of ARS. RESULTS: From October 1, 2018 to May 1, 2020, we recruited 149 infants (58% males; median age of 1 [0.5-2.5] month). Thirty-seven (25%) cases required ARS. After adjusting by age, bacterial superinfection, and comorbidities in the multivariate analysis, only higher levels of glycemia (p = 0.001), C-reactive protein (CRP) (p = 0.028), CRP/albumin ratio (p = 0.032), and NT-proBNP (p = 0.001) remained independently associated with ARS. These biomarkers reached moderate prediction accuracy with area under the curve of receiver operator curve curves ranging from 0.701 to 0.830 (p = 0.001). All they presented relatively high specificity (0.75-0.84) and negative predictive values (0.77-0.89) with low sensitivity and positive predictive values. They also correlated significantly with length of stay hospitalization (p = 0.001). CONCLUSION: Increased plasmatic levels of CRP, CRP/albumin ratio, glycemia, and NT-proBNP at hospital admission are associated with the need for ARS in infants with acute bronchiolitis.


Asunto(s)
Bronquiolitis , Albúminas , Biomarcadores , Bronquiolitis/diagnóstico , Bronquiolitis/terapia , Niño , Presión de las Vías Aéreas Positiva Contínua , Femenino , Humanos , Lactante , Masculino , Estudios Prospectivos
9.
Insect Sci ; 29(2): 487-495, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34258865

RESUMEN

Helicoverpa zea is a major target pest of Bt corn and Bt cotton. Field-evolved resistance of H. zea to Cry1 and Cry2 proteins has been widely reported in the United States. Understanding the frequency of resistance alleles in a target insect is critical for Bt resistance management. Despite multiple cases of practical resistance to Cry proteins having been documented in H. zea, there are no data on the current status of alleles conferring resistance to Cry1Ac and Cry2Ab2 in field populations of this pest. During 2018-2019, a total of 106 F2 families for Cry1Ac and 120 F2 families for Cry2Ab2 were established using mass mating and light trap strategy. We screened 13,568 and 15,360 neonates using a discriminatory dose of Cry1Ac and Cry2Ab2, respectively. The results showed that 93.4% and 35.0% of the F2 families could survive on the discriminatory dose of Cry1Ac and Cry2Ab2, respectively. The estimated resistance allele frequency for Cry1Ac in H. zea ranged from 0.4150 to 0.4975 and for Cry2Ab2 ranged from 0.1097 and 0.1228. These data indicate that the frequency of alleles conferring resistance to Cry1 and Cry2 proteins in H. zea in Texas are high. In addition, our data suggest the resistance to Cry1Ac and Cry2Ab2 in the screened families of H. zea varies from recessive to dominant. The information in this study provides precise estimates of Cry resistance allele frequencies in H. zea and increases our understanding of the risks to the sustainability of Bt crops.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Animales , Bacillus thuringiensis/metabolismo , Toxinas de Bacillus thuringiensis , Proteínas Bacterianas/metabolismo , Endotoxinas/metabolismo , Endotoxinas/farmacología , Proteínas Hemolisinas/genética , Resistencia a los Insecticidas/genética , Mariposas Nocturnas/genética , Mariposas Nocturnas/metabolismo , Plantas Modificadas Genéticamente/metabolismo , Texas , Estados Unidos , Zea mays/genética
10.
Toxins (Basel) ; 13(9)2021 09 02.
Artículo en Inglés | MEDLINE | ID: mdl-34564622

RESUMEN

Evolution of resistance by pests can reduce the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Because of the widespread resistance of Helicoverpa zea to crystalline (Cry) Bt toxins in the United States, the vegetative insecticidal protein Vip3Aa is the only Bt toxin produced by Bt corn and cotton that remains effective against some populations of this polyphagous lepidopteran pest. Here we evaluated H. zea resistance to Vip3Aa using diet bioassays to test 42,218 larvae from three lab strains and 71 strains derived from the field during 2016 to 2020 in Arkansas, Louisiana, Mississippi, Tennessee, and Texas. Relative to the least susceptible of the three lab strains tested (BZ), susceptibility to Vip3Aa of the field-derived strains decreased significantly from 2016 to 2020. Relative to another lab strain (TM), 7 of 16 strains derived from the field in 2019 were significantly resistant to Vip3Aa, with up to 13-fold resistance. Susceptibility to Vip3Aa was significantly lower for strains derived from Vip3Aa plants than non-Vip3Aa plants, providing direct evidence of resistance evolving in response to selection by Vip3Aa plants in the field. Together with previously reported data, the results here convey an early warning of field-evolved resistance to Vip3Aa in H. zea that supports calls for urgent action to preserve the efficacy of this toxin.


Asunto(s)
Toxinas de Bacillus thuringiensis , Proteínas Bacterianas , Control de Insectos , Resistencia a los Insecticidas , Mariposas Nocturnas , Control Biológico de Vectores , Animales , Larva , Mariposas Nocturnas/crecimiento & desarrollo , Plantas Modificadas Genéticamente/química
11.
Minerva Pediatr (Torino) ; 73(1): 15-21, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-28176512

RESUMEN

BACKGROUND: There is no evidence of the need for oxygen supplementation during upper digestive endoscopies under ketamine sedation in children, and the latest recommendations specifically state that it is not mandatory for the procedure. The aim of our study is to assess the incidence of respiratory adverse events during upper digestive endoscopies in children under Ketamine sedation when performed without oxygen supplementation, in accordance with the latest recommendations. METHODS: Eighty-eight children undergoing ketamine sedation for programmed upper digestive endoscopy at our Pediatric Intensive Care Unit were included. Patients needing other sedative agents different from ketamine were excluded. No patients received previous oxygen therapy. Suction equipment, oxygen, a bag-valve-mask, and age-appropriate equipment for advanced airway management were immediately available. The primary outcome measure was the incidence of desaturation episodes (i.e. FiO2 below 90% requiring an intervention). RESULTS: Fifty-five patients (62.5%) presented a desaturation episode during the procedure. Most desaturation episodes occurred during the endoscope introduction (78.2%), and 5 episodes were previous to the endoscope introduction (minute 0). Around sixty percent of patients (58.9%) required oxygen therapy and four patients required bag-mask ventilation. Once oxygen therapy was initiated, 34 patients (70.5%) required it during the complete procedure or part of it. CONCLUSIONS: Desaturation episodes occur frequently early on in the procedure. Our data suggest that the role of oxygen supplementation prior to, and during upper digestive endoscopies under ketamine sedation in children should be thoroughly assessed for future recommendations.


Asunto(s)
Sedación Consciente/efectos adversos , Sedación Profunda/efectos adversos , Endoscopía del Sistema Digestivo , Hipnóticos y Sedantes/efectos adversos , Ketamina/efectos adversos , Trastornos Respiratorios/etiología , Adolescente , Niño , Preescolar , Femenino , Humanos , Hipnóticos y Sedantes/uso terapéutico , Incidencia , Lactante , Ketamina/uso terapéutico , Masculino , Estudios Prospectivos , Trastornos Respiratorios/epidemiología , Trastornos Respiratorios/terapia
12.
Pest Manag Sci ; 77(3): 1530-1535, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33201547

RESUMEN

BACKGROUND: Helicoverpa zea is a destructive pest and target of maize and cotton expressing Cry and Vip3Aa proteins in North America. The efficacy of Cry proteins against H. zea in the USA has been largely compromised by resistance. A rapid shift towards planting Bt cotton and maize producing Vip3Aa will accelerate evolution of resistance to Vip3Aa in H. zea. Research on the genetic basis of Vip3Aa resistance in H. zea is urgently needed, and can provide fundamental information for managing resistance in this pest. Here, we characterize the inheritance of Vip3Aa resistance in H. zea. RESULTS: Susceptibility of a Vip3Aa-susceptible strain (SS), a resistant strain (RR), and progeny from different crosses against Vip3Aa39 was determined. RR was established from an F2 screening of a population from Texas sampled in 2019. RR had a resistance ratio of 45194.1-fold against Vip3Aa39 relative to SS. Maternal effects and sex linkage were absent in RR. The dominance D value, calculated based on median lethal concentration (LC50 ) values, was -1.0 and the effective dominance (DML ), calculated based on a given Vip3Aa39 concentration, was ≤0.0 at concentrations of 0.1-31.6 µg cm-2 . The test using a monogenic mode of inheritance showed that resistance to Vip3Aa in H. zea was largely due to a single gene. CONCLUSION: Results of this study indicate that Vip3Aa resistance in H. zea is monogenic, autosomal, and recessive. This information is valuable for studying the mechanism of Vip3Aa resistance, monitoring of resistance development, and designing appropriate strategies for preventive management of Vip3Aa resistance. © 2020 Society of Chemical Industry.


Asunto(s)
Bacillus thuringiensis , Mariposas Nocturnas , Animales , Bacillus thuringiensis/genética , Proteínas Bacterianas/genética , Endotoxinas , Proteínas Hemolisinas/genética , Resistencia a los Insecticidas/genética , Larva/genética , Mariposas Nocturnas/genética , Plantas Modificadas Genéticamente , Texas , Zea mays/genética
13.
Sensors (Basel) ; 20(17)2020 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-32854446

RESUMEN

Physical rehabilitation therapies for children present a challenge, and its success-the improvement of the patient's condition-depends on many factors, such as the patient's attitude and motivation, the correct execution of the exercises prescribed by the specialist or his progressive recovery during the therapy. With the aim to increase the benefits of these therapies, social humanoid robots with a friendly aspect represent a promising tool not only to boost the interaction with the pediatric patient, but also to assist physicians in their work. To achieve both goals, it is essential to monitor in detail the patient's condition, trying to generate user profile models which enhance the feedback with both the system and the specialist. This paper describes how the project NAOTherapist-a robotic architecture for rehabilitation with social robots-has been upgraded in order to include a monitoring system able to generate user profile models through the interaction with the patient, performing user-adapted therapies. Furthermore, the system has been improved by integrating a machine learning algorithm which recognizes the pose adopted by the patient and by adding a clinical reports generation system based on the QUEST metric.


Asunto(s)
Rehabilitación , Robótica , Niño , Terapia por Ejercicio , Retroalimentación , Humanos , Aprendizaje Automático , Motivación
14.
Pest Manag Sci ; 76(11): 3676-3684, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32419321

RESUMEN

BACKGROUND: The corn earworm, Helicoverpa zea (Boddie), is a major target pest of pyramided Bt corn and cotton in the United States. Field-evolved practical resistance to Cry1 and Cry2 proteins in H. zea has been documented in multiple locations in the United States. Understanding the genetic basis of Bt resistance is essential in developing insect resistance management (IRM) strategies for the sustainable use of the Bt crop technology. In this study, we characterized the genetic bases of Cry2Ab2 resistance in H. zea using diet-overlay bioassays with two different forms of Cry2Ab2 protein. RESULTS: Laboratory bioassays using a Cry2Ab2-resistant (RR) strain, a susceptible (SS) strain, as well as cross and backcross strains, revealed that resistance to Cry2Ab2 was autosomally inherited and controlled by more than one locus. In diet bioassays, the dominance of Cry2Ab2 resistance in H. zea varied from incompletely recessive to incompletely dominant across all tested Cry2Ab2 concentrations of either Bt corn leaf powder or solubilized protein. On leaf tissue of TwinLink cotton (expressing Cry1Ab and Cry2Ae), Cry2Ab2 resistance in H. zea was completely dominant. CONCLUSION: These results have significant implications for understanding the widespread field-evolved resistance of H. zea against Cry1 and Cry2 proteins in Bt corn and cotton and should be useful in developing effective IRM strategies for H. zea. © 2020 Society of Chemical Industry.


Asunto(s)
Bacillus thuringiensis , Lepidópteros , Mariposas Nocturnas , Animales , Bacillus thuringiensis/genética , Proteínas Bacterianas/genética , Endotoxinas/genética , Endotoxinas/farmacología , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/farmacología , Resistencia a los Insecticidas/genética , Mariposas Nocturnas/genética , Plantas Modificadas Genéticamente/genética , Estados Unidos , Zea mays/genética
15.
Sci Rep ; 10(1): 5867, 2020 04 03.
Artículo en Inglés | MEDLINE | ID: mdl-32246037

RESUMEN

The corn earworm, Helicoverpa zea, is a major target pest of the insecticidal Vip3Aa protein used in pyramided transgenic Bt corn and cotton with Cry1 and Cry2 proteins in the U.S. The widespread resistance to Cry1 and Cry2 proteins in H. zea will challenge the long-term efficacy of Vip3Aa technology. Determining the frequency of resistant alleles to Vip3Aa in field populations of H. zea is critically important for resistance management. Here, we provided the first F2 screen study to estimate the resistance allele frequency for Vip3Aa in H. zea populations in Texas, U.S. In 2019, 128 H. zea neonates per isofamily for a total of 114 F2 families were screened with a diagnostic concentration of 3.0 µg/cm2 of Vip3Aa39 protein in diet-overlay bioassays. The F2 screen detected two families carrying a major Vip3Aa resistance allele. The estimated frequency of major resistance alleles against Vip3Aa39 in H. zea in Texas from this study was 0.0065 with a 95% CI of 0.0014-0.0157. A Vip3Aa-resistant strain (RR) derived from the F2 screen showed a high level of resistance to Vip3Aa39 protein, with a resistance ratio of >588.0-fold relative to a susceptible population (SS) based on diet-overlay bioassays. We provide the first documentation of a major resistance allele conferring high levels of Vip3Aa resistance in a field-derived strain of H. zea in the U.S. Data generated from this study contribute to development of management strategies for the sustainable use of the Vip3Aa technology to control H. zea in the U.S.


Asunto(s)
Proteínas Bacterianas , Resistencia a los Insecticidas/genética , Insecticidas , Mariposas Nocturnas/genética , Alelos , Animales , Bioensayo , Frecuencia de los Genes/genética , Larva/efectos de los fármacos , Larva/genética , Plantas Modificadas Genéticamente , Zea mays/genética
16.
Amino Acids ; 51(9): 1337-1351, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31428912

RESUMEN

The application of high concentrations of taurine induces long-lasting potentiation of synaptic responses and axon excitability. This phenomenon seems to require the contribution of a transport system with a low affinity for taurine. The prototypic taurine transporter TauT (SLC6A6) was discarded by experimental evidence obtained in TauT-KO mice. The purpose of the present study was to determine whether the proton-coupled amino acid transporter 1 (PAT1; SLC36A1) which is a transport system with low affinity and high capacity for a great variety of amino acids including taurine, contributes to the taurine-induced synaptic potentiation. In rat hippocampal slices, the application of several amino acids (L- and D-alanine, L-glutamine, ß-guanidinopropionic acid, glycine, L-histidine, L- and D-serine, sarcosine, L- and D-threonine) imitated the synaptic potentiation induced by taurine. The magnitude of the potentiation caused by some of these amino acids was even greater than that induced by taurine. By contrast, the application of other amino acids (L-arginine, betaine, L-leucine, L-methionine, L- and D-proline, and L-valine) did not induce potentiation. The behaviour of these different amino acids on synaptic potentiation is not compatible with a role of PAT1 in synaptic potentiation. There was a positive correlation between the accumulation of the different amino acids in the slice and the magnitude of synaptic potentiation induced by them. Some of the amino acids inducing synaptic potentiation, like taurine and L-threonine, also increased electrical resistance of the slice, whereas L-leucine did not modify this parameter. Modifications induced by either taurine or L-threonine in synaptic potentiation, slice resistance and amino acid accumulation were dependent on extracellular chloride concentration. These findings support the idea that the accumulation of amino acids throughout the action of transporters causes cell swelling enhancing the electrical resistance of the slice, which by itself could be sufficient to increase field synaptic potentials.


Asunto(s)
Sistemas de Transporte de Aminoácidos Neutros/metabolismo , Aminoácidos/metabolismo , Hipocampo/fisiología , Simportadores/metabolismo , Potenciales Sinápticos , Aminoácidos/química , Aminoácidos/farmacología , Animales , Impedancia Eléctrica , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Masculino , Ratas , Ratas Sprague-Dawley , Taurina/metabolismo , Taurina/farmacología , Treonina/metabolismo , Treonina/farmacología
17.
Toxins (Basel) ; 11(2)2019 02 09.
Artículo en Inglés | MEDLINE | ID: mdl-30744120

RESUMEN

The corn earworm, Helicoverpa zea (Boddie), is a major pest of Bacillus thuringiensis (Bt) maize and cotton in the U.S.. Reduced efficacy of Bt plants expressing Cry1 and Cry2 against H. zea has been reported in some areas of the U.S.. In this study, we evaluated the occurrence and ear damage of H. zea on transgenic Bt maize expressing Cry proteins or a combination of Vip3A and Cry proteins in the field in Texas in 2018. We found that the occurrence of H. zea larvae and the viable kernel damage area on the ear were not different between non-Bt maize and Bt maize expressing Cry1A.105+Cry2Ab2 and Cry1Ab+Cry1F proteins. A total of 67.5% of the pyramided Bt maize expressing Cry1Ab+Cry1F+Vip3A was damaged by 2nd⁻4th instar larvae of H. zea. Diet bioassays showed that the resistance ratio against Vip3Aa51 for H. zea obtained from Cry1Ab+Cry1F+Vip3A maize was 20.4 compared to a field population collected from Cry1F+Cry1A.105+Cry2Ab2 maize. Leaf tissue bioassays showed that 7-day survivorship on WideStrike3 (Cry1F+Cry1Ac+Vip3A) cotton leaves was significantly higher for the H. zea population collected from Cry1Ab+Cry1F+Vip3A maize than for a Bt-susceptible laboratory population. The results generated from this study suggest that H. zea has evolved practical resistance to Cry1 and Cry2 proteins. Therefore, it is crucial to ensure the sustainable use of the Vip3A technology in Bt maize and cotton.


Asunto(s)
Proteínas Bacterianas/genética , Endotoxinas/genética , Proteínas Hemolisinas/genética , Larva , Mariposas Nocturnas , Enfermedades de las Plantas/parasitología , Plantas Modificadas Genéticamente/parasitología , Zea mays/parasitología , Animales , Bacillus thuringiensis/genética , Toxinas de Bacillus thuringiensis , Texas , Zea mays/genética
18.
Pediatr Crit Care Med ; 20(3): e130-e136, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30664037

RESUMEN

OBJECTIVES: Increasing evidence supports the association of fluid overload with adverse outcomes in different diseases. To our knowledge, few studies have examined the impact of fluid balance on clinical outcome in severe bronchiolitis. Our aim was to determine whether fluid overload was associated with adverse clinical outcomes in critically ill children with severe bronchiolitis. DESIGN: Descriptive, prospective, multicenter study. SETTING: Sixteen Spanish PICUs. PATIENTS: Severe acute bronchiolitis who required admission from October 2014 to May 2015 were included. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Total fluid intake and output were prospectively recorded during PICU assistance. Fluid balance was measured at 24, 48, and 72 hours after PICU admission. A total of 262 patients were enrolled; 54.6% were male. Median age was 1 month (interquartile range, 1-3 mo). Patients had a positive fluid balance during the first 4 days of PICU admission, reaching a neutral balance on day 4. A positive balance at 24 hours in patients admitted to the PICU with severe bronchiolitis was related with longer stay in PICU (p < 0.001), longer hospital stay (p < 0.001), longer duration of mechanical ventilation (p = 0.016), and longer duration of noninvasive ventilation (p = 0.0029). CONCLUSIONS: Critically ill patients with severe acute bronchiolitis who present a positive balance in the first 24 hours of PICU admission have poorer clinical outcomes with longer PICU and hospital length of stay and duration of invasive and noninvasive mechanical ventilation.


Asunto(s)
Bronquiolitis/terapia , Enfermedad Crítica/terapia , Fluidoterapia/efectos adversos , Femenino , Fluidoterapia/métodos , Humanos , Lactante , Unidades de Cuidado Intensivo Pediátrico , Tiempo de Internación , Masculino , Estudios Prospectivos , Respiración Artificial , Factores de Riesgo , Índice de Severidad de la Enfermedad , España , Factores de Tiempo
19.
Materials (Basel) ; 10(3)2017 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-28772681

RESUMEN

The synthesis of AlN and TiB2 by spark plasma sintering (SPS) and the effect of Nb2O5, Y2O3 and ZrO2 additions on the mechanical properties and densification of the produced composites is reported and discussed. After the SPS process, dense AlN and TiB2 composites with Nb2O5, Y2O3 and ZrO2 were successfully prepared. X-ray diffraction analysis showed that in the AlN composites, the addition of Nb2O5 gives rise to Nb4N3 during sintering. The compound Y3Al5O12 (YAG) was observed as precipitate in the sample with Y2O3. X-ray diffraction analysis of the TiB2 composites showed TiB2 as a single phase in these materials. The maximum Vickers and toughness values were 14.19 ± 1.43 GPa and 27.52 ± 1.75 GPa for the AlN and TiB2 composites, respectively.

20.
Biomed Res Int ; 2017: 2565397, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28421191

RESUMEN

Objective. To determine the epidemiology and therapeutic management of patients with severe acute bronchiolitis (AB) admitted to paediatric intensive care units (PICUs) in Spain. Design. Descriptive, prospective, multicentre study. Setting. Sixteen Spanish PICUs. Patients. Patients with severe AB who required admission to any of the participating PICUs over 1 year. Interventions. Both epidemiological variables and medical treatment received were recorded. Results. A total of 262 patients were recruited; 143 were male (54.6%), with median age of 1 month (0-23). Median stay in the PICU was 7 days (1-46). Sixty patients (23%) received no nebuliser treatment, while the rest received a combination of inhalation therapies. One-quarter of patients (24.8%) received corticosteroids and 56.5% antibiotic therapy. High-flow oxygen therapy was used in 14.3% and noninvasive ventilation (NIV) was used in 75.6%. Endotracheal intubation was required in 24.4% of patients. Younger age, antibiotic therapy, and invasive mechanical ventilation (IMV) were risk factors that significantly increased the stay in the PICU. Conclusions. Spanish PICUs continue to routinely use nebulised bronchodilator treatment and corticosteroid therapy. Despite NIV being widely used in this condition, intubation was required in one-quarter of cases. Younger age, antibiotic therapy, and IMV were associated with a longer stay in the PICU.


Asunto(s)
Bronquiolitis/epidemiología , Unidades de Cuidados Intensivos , Tiempo de Internación , Índice de Severidad de la Enfermedad , Administración por Inhalación , Corticoesteroides/administración & dosificación , Antibacterianos/administración & dosificación , Bronquiolitis/tratamiento farmacológico , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Estudios Prospectivos , Factores Sexuales , España
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