CRISPR-Cas9 knockout of membrane-bound alkaline phosphatase or cadherin does not confer resistance to Cry toxins in Aedes aegypti.

The Aedes aegypti cadherin-like protein (Aae-Cad) and the membrane-bound alkaline phosphatase (Aae-mALP) are membrane proteins identified as putative receptors for the larvicidal Cry toxins produced by Bacillus thuringiensis subsp. israelensis bacteria. Cry toxins are the most used toxins in the control of different agricultural pest and mosquitos. Despite the relevance of Aae-Cad and Aae-mALP as possible toxin-receptors in mosquitoes, previous efforts to establish a clear functional connection among them and Cry toxins activity have been relatively limited. In this study, we used CRISPR-Cas9 to generate knockout (KO) mutations of Aae-Cad and Aae-mALP. The Aae-mALP KO was successfully generated, in contrast to the Aae-Cad KO which was obtained only in females. The female-linked genotype was due to the proximity of aae-cad gene to the sex-determining loci (M:m). Both A. aegypti KO mutant populations were viable and their insect-development was not affected, although a tendency on lower egg hatching rate was observed. Bioassays were performed to assess the effects of these KO mutations on the susceptibility of A. aegypti to Cry toxins, showing that the Aae-Cad female KO or Aae-mALP KO mutations did not significantly alter the susceptibility of A. aegypti larvae to the mosquitocidal Cry toxins, including Cry11Aa, Cry11Ba, Cry4Ba, and Cry4Aa. These findings suggest that besides the potential participation of Aae-Cad and Aae-mALP as Cry toxin receptors in A. aegypti, additional midgut membrane proteins are involved in the mode of action of these insecticidal toxins.

Addressing medical student burnout through informal peer-assisted learning: a correlational analysis.

BACKGROUND: Despite the recognized advantages of Peer-Assisted Learning (PAL) in academic settings, there is a notable absence of research analyzing its effects on students' Academic Burnout. This study aims to cover this gap by assessing the underlying effectiveness of Informal Peer-Assisted Learning (IPAL) as a cooperative learning method, focusing on its potential to mitigate academic burnout among medical students. METHODS: In 2022, a cross-sectional study was conducted at the School of Medicine, Universidad Central del Caribe, in Puerto Rico. The research team gathered data from 151 participants, 49.19% of 307 total student body. This cohort included 76 female students, 71 male students, and 4 individuals saying other. The School Burnout Inventory questionnaire (SBI-9) was employed to assess Academic Burnout, along with an added query about self-reported IPAL. The SBI-9 underwent validation processes to ascertain its reliability and validity, incorporating the Exploratory Factor Analysis and Confirmatory Factor Analysis. Following this, the investigators conducted an analysis to determine the correlation between academic burnout levels and involvement in IPAL. RESULTS: The validation process of the questionnaire affirmed its alignment with an eight-item inventory, encapsulating two principal factors that elucidate academic burnout. The first factor pertains to exhaustion, while the second encompasses the combined subscales of cynicism and inadequacy. The questionnaire shows high reliability (Cronbach's alpha = 0.829) and good fit indices (Comparative Fit Index = 0.934; Tucker-Lewis Index = 0.902; Standardized Root Mean Squared Residual = 0.0495; Root Mean Squared Error of Approximation = 0.09791; p-value < 0.001). The factors proven in the selected model were used to evaluate the correlation between Academic Burnout and IPAL. Students engaged in IPAL showed significantly lower academic burnout prevalence compared to those who never participated in such practices, with a mean academic burnout score of 44.75% (SD 18.50) for IPAL engaged students versus 54.89% (SD 23.71) for those who never engaged in such practices (p-value < 0.013). Furthermore, within the group engaged in IPAL, students displayed lower levels of cynicism/inadequacy 41.98% (SD 23.41) compared to exhaustion 52.25% (SD 22.42) with a p-value < 0.001. CONCLUSIONS: The results of this study underscore a notable issue of academic burnout among medical students within the surveyed cohort. The investigation reveals a significant correlation between Academic Burnout and IPAL, suggesting that incorporating IPAL strategies may be beneficial in addressing burnout in medical education settings. However, further research is needed to explore potential causal mechanisms.

Performance insights into spray-dryer microencapsulated Bacillus thuringiensis cry pesticidal proteins with gum arabic and maltodextrin for effective pest control.

Bacillus thuringiensis (Bt) produces crystals composed mainly of Cry pesticidal proteins with insecticidal activity against pests but are highly susceptible to degradation by abiotic factors. In this sense, encapsulation techniques are designed to improve their performance and lifetime. However, the effects of polymeric matrix encapsulation such as gum arabic and maltodextrin by spray-dryer in the mechanisms of action of Bt kurstaki and Bt aizawai are unknown. We analyzed crystal solubilization, protoxin activation, and receptor binding after microencapsulation and compared them with commercial non-encapsulated products. Microencapsulation did not alter protein crystal solubilization, providing 130 kDa (Cry1 protoxin) and 70 kDa (Cry2 protoxin). Activation with trypsin, chymotrypsin, and larval midgut juice was analyzed, showing that this step is highly efficient, and the protoxins were cleaved producing similar ~ 55 to 65 kDa activated proteins for both formulations. Binding assays with brush border membrane vesicles of Manduca sexta and Spodoptera frugiperda larvae provided a similar binding for both formulations. LC50 bioassays showed no significant differences between treatments but the microencapsulated treatment provided higher mortality against S. frugiperda when subjected to UV radiation. Microencapsulation did not affect the mechanism of action of Cry pesticidal proteins while enhancing protection against UV radiation. These data will contribute to the development of more efficient Bt biopesticide formulations. KEY POINTS: • Microencapsulation did not affect the mechanisms of action of Cry pesticidal proteins produced by Bt. • Microencapsulation provided protection against UV radiation for Bt-based biopesticides. • The study's findings can contribute to the development of more efficient Bt biopesticide formulations.

Growth Developmental Defects of Mitochondrial Iron Transporter 1 and 2 Mutants in Arabidopsis in Iron Sufficient Conditions.

Iron is the most abundant micronutrient in plant mitochondria, and it has a crucial role in biochemical reactions involving electron transfer. It has been described in Oryza sativa that Mitochondrial Iron Transporter (MIT) is an essential gene and that knockdown mutant rice plants have a decreased amount of iron in their mitochondria, strongly suggesting that OsMIT is involved in mitochondrial iron uptake. In Arabidopsis thaliana, two genes encode MIT homologues. In this study, we analyzed different AtMIT1 and AtMIT2 mutant alleles, and no phenotypic defects were observed in individual mutant plants grown in normal conditions, confirming that neither AtMIT1 nor AtMIT2 are individually essential. When we generated crosses between the Atmit1 and Atmit2 alleles, we were able to isolate homozygous double mutant plants. Interestingly, homozygous double mutant plants were obtained only when mutant alleles of Atmit2 with the T-DNA insertion in the intron region were used for crossings, and in these cases, a correctly spliced AtMIT2 mRNA was generated, although at a low level. Atmit1 Atmit2 double homozygous mutant plants, knockout for AtMIT1 and knockdown for AtMIT2, were grown and characterized in iron-sufficient conditions. Pleiotropic developmental defects were observed, including abnormal seeds, an increased number of cotyledons, a slow growth rate, pinoid stems, defects in flower structures, and reduced seed set. A RNA-Seq study was performed, and we could identify more than 760 genes differentially expressed in Atmit1 Atmit2. Our results show that Atmit1 Atmit2 double homozygous mutant plants misregulate genes involved in iron transport, coumarin metabolism, hormone metabolism, root development, and stress-related response. The phenotypes observed, such as pinoid stems and fused cotyledons, in Atmit1 Atmit2 double homozygous mutant plants may suggest defects in auxin homeostasis. Unexpectedly, we observed a possible phenomenon of T-DNA suppression in the next generation of Atmit1 Atmit2 double homozygous mutant plants, correlating with increased splicing of the AtMIT2 intron containing the T-DNA and the suppression of the phenotypes observed in the first generation of the double mutant plants. In these plants with a suppressed phenotype, no differences were observed in the oxygen consumption rate of isolated mitochondria; however, the molecular analysis of gene expression markers, AOX1a, UPOX, and MSM1, for mitochondrial and oxidative stress showed that these plants express a degree of mitochondrial perturbation. Finally, we could establish by a targeted proteomic analysis that a protein level of 30% of MIT2, in the absence of MIT1, is enough for normal plant growth under iron-sufficient conditions.

A major conformational change of N-terminal helices of Bacillus thuringiensis Cry1Ab insecticidal protein is necessary for membrane insertion and toxicity.

Pore forming toxins rely on oligomerization for membrane insertion to kill their targets. Bacillus thuringiensis produces insecticidal Cry-proteins composed of three domains that form pores that kill the insect larvae. Domain I is involved in oligomerization and membrane insertion, whereas Domains II and III participate in receptor binding and specificity. However, the structural changes involved in membrane insertion of these proteins remain unsolved. The most widely accepted model for membrane insertion, the 'umbrella model', proposed that the α-4/α-5 hairpin of Domain I swings away and is inserted into the membrane. To determine the topology of Cry1Ab in the membrane, disulfide bonds linking α-helices of Domain I were introduced to restrict their movement. Disulfide bonds between helices α-2/α-3 or α-3/α-4 lost oligomerization and toxicity, indicating that movement of these helices is needed for insecticidal activity. By contrast, disulfide bonds linking helices α-5/α-6 did not affect toxicity, which contradicts the 'umbrella model'. Additionally, Föster resonance energy transfer closest approach analyses measuring distances of different points in the toxin to the membrane plane and collisional quenching assays analysing the protection of specific fluorescent-labeled residues to the soluble potassium iodide quencher in the membrane inserted state were performed. Overall, the data show that Domain I from Cry1Ab may undergo a major conformational change during its membrane insertion, where the N-terminal region (helices α-1 to α-4) participates in oligomerization and toxicity, probably forming an extended helix. These data break a paradigm, showing a new 'folding white-cane model', which better explains the structural changes of Cry toxins during insertion into the membrane.

Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis.

Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some of these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism of action of these toxins that have helped to improve their performance and to cope with the resistance evolved by different insects against some of these proteins. However, crucial information that is still missing is the structure of pores formed by some of these PFTs, such as the three-domain crystal (Cry) proteins, which are the most commercially used Bt toxins in the biological control of insect pests. In recent years, progress has been made on the identification of the structural changes that certain Bt insecticidal PFT proteins undergo upon membrane insertion. In this review, we describe the models that have been proposed for the membrane insertion of Cry toxins. We also review the recently published structures of the vegetative insecticidal proteins (Vips; e.g. Vip3) and the insecticidal toxin complex (Tc) in the membrane-inserted state. Although different Bt PFTs show different primary sequences, there are some similarities in the three-dimensional structures of Vips and Cry proteins. In addition, all PFTs described here must undergo major structural rearrangements to pass from a soluble form to a membrane-inserted state. It is proposed that, despite their structural differences, all PFTs undergo major structural rearrangements producing an extended α-helix, which plays a fundamental role in perforating their target membrane, resulting in the formation of the membrane pore required for their insecticidal activity.

Supervivencia extendida con pembrolizumab en un paciente con cáncer de pulmón no microcítico estadio IV: Reporte de caso / Extendedsurvival with pembrolizumab in a patient with stage IV non-small cell lung cancer:A case report

Introducción:La inmunoterapia con pembrolizumab ha mejorado el pronóstico del cáncer de pulmón metastásico. En el presente caso se presenta la supervivencia extendidad y evolución de un paciente específico.Caso clínico:Hombre de 66 años, fumador. Diagnosticado de masa pulmonar en lóbulo infe-rior izquierdo de dimensiones 9 x 8 cm, con metástasis supra e infratentoriales intraaxiliares. Taller diagnóstico: Establecida como neoplasia de pulmón en estadio IVc, se comprobó el estado de PDL1 que positivo en un 80 % de la muestra de masa pulmonar. Debuta con me-tástasis cerebrales.Evolución: Se inció inmunoterapia con Pembrolizumab, el cual se mantubo hasta la presencia de un efecto secundario atribuido al pembrolizumab, cumpliendo 30meses de supervivencia hasta el cierre de esta observación no se reportó la muerte del paciente.Conclusiones:En el presente reporte, la determinación del biomarcador histológico PDL1 po-sitivo en cáncer de pulmón ayudo a prescribir un tratamiento con inmunoterpia dirigida, lo que demostró aumentar la supervivencia más allá que el tratamiento convencional con quimiote-rapia

Introduction: Immunotherapy with pembrolizumab has improved the prognosis of metastatic lung cancer. A specific patient's extended survival and evolution is presented in the present case.Clinical case: 66-year-old man, smoker. Diagnosed with a lung mass in the left lower lobe measuring 9 x 8 cm, with supra and infratentorial intra-axial metastases.Diagnostic workshop: To establisha stage IVc lung neoplasm, 80% of the lung mass sample was confirmed to be positive for PDL1.Evolution: Immunotherapy was started with Pembrolizumab, which was maintained until the presence of a side effect attributed to pembrolizumab, completing 30 months of survival until the closure of this observation, the patient's death was not reported.Conclusions: In the present report, the determination of the positive histological biomarker PDL1 in lung cancer helped prescribe treatment with targeted immunotherapy, which was shown to increase survival beyond conventional treatment with chemotherapy

[Public health measures during the COVID-19 pandemic in institutions for the protection of children and adolescents in two departments in ColombiaMedidas de saúde pública em instituições de proteção de crianças e adolescentes em dois departamentos da Colômbia durante a pandemia de COVID-19]. / Medidas de salud pública en instituciones de protección a la infancia y la adolescencia en dos departamentos de Colombia durante la pandemia de COVID-19.

Objective: Analyze facilitating processes, obstacles, and effects of the implementation of non-pharmacological public health measures for the prevention of COVID-19 in child and adolescent protection centers in two departments (Antioquia and La Guajira) in Colombia during the period 2020-2021. Methods: Mixed methods study with a convergent parallel design in 13 residential child/adolescent protection facilities in Colombia (11 in Antioquia and two in La Guajira). A questionnaire was given to 145 children and adolescents, and 23 interviews were held with persons responsible for the implementation of measures in the national family welfare system. Results: The implemented non-pharmacological public health measures did not differ by department; the most complex to implement were physical distancing and restriction of family visits. Conclusions: In centers for the protection of children and adolescents in Antioquia and La Guajira, non-pharmacological public health measures helped mitigate the spread of the virus in environments considered at-risk.

Objetivo: Analisar os processos que facilitam e dificultam a implementação de medidas não farmacológicas de saúde pública para a prevenção da COVID-19 em centros de proteção de crianças e adolescentes em dois departamentos (Antioquia e La Guajira) da Colômbia, e os efeitos de tal implementação, durante o período 2020-2021. Métodos: Estudo de métodos mistos com delineamento paralelo convergente em 13 internatos para a proteção de crianças e adolescentes na Colômbia (11 em Antioquia e 2 em La Guajira). Foi aplicado um questionário a 145 crianças e adolescentes, e foram realizadas 23 entrevistas com os responsáveis pela implementação das medidas do sistema nacional de bem-estar familiar. Resultados: As medidas não farmacológicas de saúde pública implementadas não diferiram por departamento. As mais complexas de serem aplicadas foram o distanciamento físico e a restrição de visitas familiares. Conclusões: Nos centros de proteção de crianças e adolescentes de Antioquia e La Guajira, medidas não farmacológicas de saúde pública contribuíram para mitigar a propagação do vírus em ambientes considerados de risco.

Medidas de salud pública en instituciones de protección a la infancia y la adolescencia en dos departamentos de Colombia durante la pandemia de COVID-19

[RESUMEN]. Objetivo. Analizar los procesos facilitadores y obstaculizadores y los efectos de la implementación de las medidas de salud pública no farmacológicas para la prevención de la COVID-19 en los centros de protección de la infancia y la adolescencia de dos departamentos (Antioquia y la Guajira) de Colombia durante el período 2020-2021. Métodos. Estudio de métodos mixtos con un diseño paralelo convergente en 13 internados de protección de la infancia y adolescencia de Colombia (11 en Antioquia y 2 en La Guajira). Se aplicó un cuestionario a 145 niñas, niños y adolescentes y 23 entrevistas a mediadores de la implementación de las medidas del sistema nacional de bienestar familiar. Resultados. Las medidas de salud pública no farmacológicas implementadas no difieren por departamento; las más complejas para aplicar fueron el distanciamiento físico y la restricción de las visitas familiares. Conclusiones. En los centros de protección de la infancia y la adolescencia de Antioquia y la Guajira, las medidas de salud pública no farmacológicas contribuyeron a mitigar la propagación del virus en entornos considerados de riesgo.

[ABSTRACT]. Objective. Analyze facilitating processes, obstacles, and effects of the implementation of non-pharmacologi- cal public health measures for the prevention of COVID-19 in child and adolescent protection centers in two departments (Antioquia and La Guajira) in Colombia during the period 2020–2021. Methods. Mixed methods study with a convergent parallel design in 13 residential child/adolescent protection facilities in Colombia (11 in Antioquia and two in La Guajira). A questionnaire was given to 145 children and adolescents, and 23 interviews were held with persons responsible for the implementation of measures in the national family welfare system. Results. The implemented non-pharmacological public health measures did not differ by department; the most complex to implement were physical distancing and restriction of family visits. Conclusions. In centers for the protection of children and adolescents in Antioquia and La Guajira, non-phar- macological public health measures helped mitigate the spread of the virus in environments considered at-risk.

[RESUMO]. Objetivo. Analisar os processos que facilitam e dificultam a implementação de medidas não farmacológi- cas de saúde pública para a prevenção da COVID-19 em centros de proteção de crianças e adolescentes em dois departamentos (Antioquia e La Guajira) da Colômbia, e os efeitos de tal implementação, durante o período 2020-2021. Métodos. Estudo de métodos mistos com delineamento paralelo convergente em 13 internatos para a proteção de crianças e adolescentes na Colômbia (11 em Antioquia e 2 em La Guajira). Foi aplicado um questionário a 145 crianças e adolescentes, e foram realizadas 23 entrevistas com os responsáveis pela implementação das medidas do sistema nacional de bem-estar familiar. Resultados. As medidas não farmacológicas de saúde pública implementadas não diferiram por departa- mento. As mais complexas de serem aplicadas foram o distanciamento físico e a restrição de visitas familiares. Conclusões. Nos centros de proteção de crianças e adolescentes de Antioquia e La Guajira, medidas não farmacológicas de saúde pública contribuíram para mitigar a propagação do vírus em ambientes considera- dos de risco.

Medidas de salud pública en instituciones de protección a la infancia y la adolescencia en dos departamentos de Colombia durante la pandemia de COVID-19 / Public health measures during the COVID-19 pandemic in institutions for the protection of children and adolescents in two departments in Colombia / Medidas de saúde pública em instituições de proteção de crianças e adolescentes em dois departamentos da Colômbia durante a pandemia de COVID-19

RESUMEN Objetivo. Analizar los procesos facilitadores y obstaculizadores y los efectos de la implementación de las medidas de salud pública no farmacológicas para la prevención de la COVID-19 en los centros de protección de la infancia y la adolescencia de dos departamentos (Antioquia y la Guajira) de Colombia durante el período 2020-2021. Métodos. Estudio de métodos mixtos con un diseño paralelo convergente en 13 internados de protección de la infancia y adolescencia de Colombia (11 en Antioquia y 2 en La Guajira). Se aplicó un cuestionario a 145 niñas, niños y adolescentes y 23 entrevistas a mediadores de la implementación de las medidas del sistema nacional de bienestar familiar. Resultados. Las medidas de salud pública no farmacológicas implementadas no difieren por departamento; las más complejas para aplicar fueron el distanciamiento físico y la restricción de las visitas familiares. Conclusiones. En los centros de protección de la infancia y la adolescencia de Antioquia y la Guajira, las medidas de salud pública no farmacológicas contribuyeron a mitigar la propagación del virus en entornos considerados de riesgo.

ABSTRACT Objective. Analyze facilitating processes, obstacles, and effects of the implementation of non-pharmacological public health measures for the prevention of COVID-19 in child and adolescent protection centers in two departments (Antioquia and La Guajira) in Colombia during the period 2020-2021. Methods. Mixed methods study with a convergent parallel design in 13 residential child/adolescent protection facilities in Colombia (11 in Antioquia and two in La Guajira). A questionnaire was given to 145 children and adolescents, and 23 interviews were held with persons responsible for the implementation of measures in the national family welfare system. Results. The implemented non-pharmacological public health measures did not differ by department; the most complex to implement were physical distancing and restriction of family visits. Conclusions. In centers for the protection of children and adolescents in Antioquia and La Guajira, non-pharmacological public health measures helped mitigate the spread of the virus in environments considered at-risk.

RESUMO Objetivo. Analisar os processos que facilitam e dificultam a implementação de medidas não farmacológicas de saúde pública para a prevenção da COVID-19 em centros de proteção de crianças e adolescentes em dois departamentos (Antioquia e La Guajira) da Colômbia, e os efeitos de tal implementação, durante o período 2020-2021. Métodos. Estudo de métodos mistos com delineamento paralelo convergente em 13 internatos para a proteção de crianças e adolescentes na Colômbia (11 em Antioquia e 2 em La Guajira). Foi aplicado um questionário a 145 crianças e adolescentes, e foram realizadas 23 entrevistas com os responsáveis pela implementação das medidas do sistema nacional de bem-estar familiar. Resultados. As medidas não farmacológicas de saúde pública implementadas não diferiram por departamento. As mais complexas de serem aplicadas foram o distanciamento físico e a restrição de visitas familiares. Conclusões. Nos centros de proteção de crianças e adolescentes de Antioquia e La Guajira, medidas não farmacológicas de saúde pública contribuíram para mitigar a propagação do vírus em ambientes considerados de risco.

Whole Genome Sequencing Analysis of Bacillus thuringiensis GR007 Reveals Multiple Pesticidal Protein Genes.

Bacillus thuringiensis (Bt) are soil ubiquitous bacteria. They produce a great variability of insecticidal proteins, where certain of these toxins are used worldwide for pest control. Through their adaptation to diverse ecosystems, certain Bt strains have acquired genetic mobile elements by horizontal transfer, harboring genes that encode for different virulent factors and pesticidal proteins (PP). Genomic characterization of Bt strains provides a valuable source of PP with potential biotechnological applications for pest control. In this work, we have sequenced the complete genome of the bacterium Bt GR007 strain that is toxic to Spodoptera frugiperda and Manduca sexta larvae. Four replicons (one circular chromosome and three megaplasmids) were identified. The two largest megaplasmids (pGR340 and pGR157) contain multiple genes that codify for pesticidal proteins: 10 cry genes (cry1Ab, cry1Bb, cry1Da, cry1Fb, cry1Hb, cry1Id, cry1Ja, cry1Ka, cry1Nb, and cry2Ad), two vip genes (vip3Af and vip3Ag), two binary toxin genes (vpa2Ac and vpb1Ca), five genes that codify for insecticidal toxin components (Tc's), and a truncated cry1Bd-like gene. In addition, genes that codify for several virulent factors were also found in this strain. Proteomic analysis of the parasporal crystals of GR007 revealed that they are composed of eight Cry proteins. Further cloning of these genes for their individual expression in Bt acrystalliferous strain, by means of their own intrinsic promoter showed expression of seven Cry proteins. These proteins display differential toxicity against M. sexta and S. frugiperda larvae, where Cry1Bb showed to be the most active protein against S. frugiperda larvae and Cry1Ka the most active protein against M. sexta larvae.

Bacillus thuringiensis Cry1Ab Domain III ß-16 Is Involved in Binding to Prohibitin, Which Correlates with Toxicity against Helicoverpa armigera (Lepidoptera: Noctuidae).

Helicoverpa armigera is a major insect pest of several crops worldwide. This insect is susceptible to some Bacillus thuringiensis (Bt) Cry insecticidal proteins expressed in transgenic crops or used in biopesticides. Previously, we identified H. armigera prohibitin (HaPHB) as a Cry1Ac-binding protein. Here, we further analyzed the potential role of PHB as a Cry toxin receptor in comparison to cadherin (CAD), well recognized as a Cry1Ac receptor. HaPHB-2 midgut protein and HaCAD toxin-binding region (TBR) fragment from H. armigera were expressed in Escherichia coli cells, and binding assays with different Cry1 toxins were performed. We demonstrated that Cry1Ab, Cry1Ac, and Cry1Fa toxins bound to HaPHB-2 in a manner similar to that seen with HaCAD-TBR. Different Cry1Ab mutant toxins located in domain II (Cry1AbF371A and Cry1AbG439D) or domain III (Cry1AbL511A and Cry1AbN514A), which were previously characterized and found to be affected in receptor binding, were analyzed regarding their binding interaction with HaPHB-2 and toxicity against H. armigera One ß-16 mutant (Cry1AbN514A) showed increased binding to HaPHB-2 that correlated with 6-fold-higher toxicity against H. armigera, whereas the other ß-16 mutant (Cry1AbL511A) was affected in binding to HaPHB-2 and lost toxicity against H. armigera Our data indicate that ß-16 from domain III of Cry1Ab is involved in interactions with HaPHB-2 and in toxicity. This report identifies a region of Cry1Ab involved in binding to HaPHB-2 from a Lepidoptera insect, suggesting that this protein may participate as a novel receptor in the mechanism of action of the Cry1 toxins in H. armigeraIMPORTANCEHelicoverpa armigera is a polyphagous pest that feeds on important crops worldwide. This insect pest is sensitive to different Cry1 toxins from Bacillus thuringiensis In this study, we analyzed the potential role of PHB-2 as a Cry1 toxin receptor in comparison to CAD. We show that different Cry1 toxins bound to HaPHB-2 and HaCAD-TBR similarly and identify ß-16 from domain III of Cry1Ab as a binding region involved in the interaction with HaPHB-2 and in toxicity. This report characterized HaPHB-Cry1 binding interaction, providing novel insights into potential target sites for improving Cry1 toxicity against H. armigera.

Rearrangement of N-Terminal α-Helices of Bacillus thuringiensis Cry1Ab Toxin Essential for Oligomer Assembly and Toxicity.

Cry proteins produced by Bacillus thuringiensis are pore-forming toxins that disrupt the membrane integrity of insect midgut cells. The structure of such pore is unknown, but it has been shown that domain I is responsible for oligomerization, membrane insertion and pore formation activity. Specifically, it was proposed that some N-terminal α-helices are lost, leading to conformational changes that trigger oligomerization. We designed a series of mutants to further analyze the molecular rearrangements at the N-terminal region of Cry1Ab toxin that lead to oligomer assembly. For this purpose, we introduced Cys residues at specific positions within α-helices of domain I for their specific labeling with extrinsic fluorophores to perform Föster resonance energy transfer analysis to fluorescent labeled Lys residues located in Domains II-III, or for disulfide bridges formation to restrict mobility of conformational changes. Our data support that helix α-1 of domain I is cleaved out and swings away from the toxin core upon binding with Manduca sexta brush border membrane vesicles. That movement of helix α-2b is also required for the conformational changes involved in oligomerization. These observations are consistent with a model proposing that helices α-2b and α-3 form an extended helix α-3 necessary for oligomer assembly of Cry toxins.

Eficacia y seguridad clínica del itolizumab en fase de inducción en pacientes con psoriasis grave / Efficacy and clinical safety of Itolizumab in the induction phase in patients with severe psoriasis

Introducción: La psoriasis, enfermedad inflamatoria sistémica de la piel, tiene consecuencias adversas serias para el bienestar físico, mental y social de las personas; sus tratamientos son costosos y con marcados efectos adversos. El itolizumab, anticuerpo monoclonal anti CD6 humanizado, actúa como inmunomodulador de las células T y desempeña un importante papel en su patogénesis. Objetivo: Evaluar la eficacia y la seguridad clínica del itolizumab en 80 pacientes con psoriasis vulgar grave. Métodos: Se realizó un programa de uso clínico expandido, promovido por el Centro de Inmunología Molecular. La respuesta clínica se midió por el índice de gravedad y área de afectación de psoriasis, y para la eficacia se conjugaron estos elementos con los de seguridad, mediante un análisis clínico complementario de los datos generados durante la fase de inducción. Se emplearon como medidas de resumen los números absolutos, el porciento, el promedio y estadísticas de asociación: las pruebas de correlación de de Pearson, de Friedman y la prueba de Lambda. Resultados: El análisis del área de afectación de psoriasis arrojó un rápido y sostenido descenso de sus valores; prevalecieron los eventos adversos relacionados con la administración del producto en investigación, de aparición inmediata, ligeros, muy probables y no serios. Conclusiones: El itolizumab es seguro y eficaz en el 96 por ciento de los pacientes psoriásicos graves durante los esquemas de inducción(AU)

Introduction: Psoriasis, systemic inflammatory skin disease, has serious adverse consequences for the physical, mental and social well-being of people; its treatments are expensive and with marked adverse effects. Itolizumab, a humanized anti-CD6 monoclonal antibody, acts as an immunomodulator of T cells and plays an important role in its pathogenesis. Objective: To evaluate the efficacy and clinical safety of itolizumab in 80 patients with severe psoriasis vulgaris. Methods: An expanded clinical use program was carried out, promoted by the Molecular Immunology Center. The clinical response was measured by the severity index and area of psoriasis involvement and for effectiveness these elements were combined with safety, through a complementary clinical analysis of the data generated during the induction phase. Absolute numbers, percent and average and association statistics such as Pearson's correlation tests or Lambda's test were used as summary measures. Results: The area of psoriasis involvement analysis showed a rapid and sustained decrease in its values; adverse events related to the administration of the product under investigation prevailed, light onset, very probable and not serious. Conclusions: Itolizumab is safe and effective in 96 percent of severe psoriatic patients during the induction phase(AU)

Ketamine-Treatment During Late Adolescence Impairs Inhibitory Synaptic Transmission in the Prefrontal Cortex and Working Memory in Adult Rats.

Schizophrenia (SZ) is associated with changes in the structure and function of several brain areas. Several findings suggest that these impairments are related to a dysfunction in γ-aminobutyric acid (GABA) neurotransmission in brain areas such as the medial prefrontal cortex (mPFC), the hippocampus (HPC) and the primary auditory cortex (A1); however, it is still unclear how the GABAergic system is disrupted in these brain areas. Here, we examined the effect of ketamine (Ket) administration during late adolescence in rats on inhibition in the mPFC-, ventral HPC (vHPC), and A1. We observe that Ket treatment reduced the expression of the calcium-binding protein parvalbumin (PV) and the GABA-producing enzyme glutamic acid decarboxylase 67 (GAD67) as well as decreased inhibitory synaptic efficacy in the mPFC. In addition, Ket-treated rats performed worse in executive tasks that depend on the integrity and proper functioning of the mPFC. Conversely, we do not find such changes in vHPC or A1. Together, our results provide strong experimental support for the hypothesis that during adolescence, the function of the mPFC is more susceptible than that of HPC or A1 to NMDAR hypofunction, showing apparent structure specificity. Thus, the impairment of inhibitory circuitry in mPFC could be a convergent primary site of SZ-like behavior during the adulthood.

Identification of midgut membrane proteins from different instars of Helicoverpa armigera (Lepidoptera: Noctuidae) that bind to Cry1Ac toxin.

Helicoverpa armigera is a polyphagous pest sensitive to Cry1Ac protein from Bacillus thuringiensis (Bt). The susceptibility of the different larval instars of H. armigera to Cry1Ac protoxin showed a significant 45-fold reduction in late instars compared to early instars. A possible hypothesis is that gut surface proteins that bind to Cry1Ac differ in both instars, although higher Cry toxin degradation in late instars could also explain the observed differences in susceptibility. Here we compared the Cry1Ac-binding proteins from second and fifth instars by pull-down assays and liquid chromatography coupled to mass spectrometry analysis (LC-MS/MS). The data show differential protein interaction patterns of Cry1Ac in the two instars analyzed. Alkaline phosphatase, and other membrane proteins, such as prohibitin and an anion selective channel protein were identified only in the second instar, suggesting that these proteins may be involved in the higher toxicity of Cry1Ac in early instars of H. armigera. Eleven Cry1Ac binindg proteins were identified exclusively in late instar larvae, like different proteases such as trypsin-like protease, azurocidin-like proteinase, and carboxypeptidase. Different aminopeptidase N isofroms were identified in both instar larvae. We compared the Cry1Ac protoxin degradation using midgut juice from late and early instars, showing that the midgut juice from late instars is more efficient to degrade Cry1Ac protoxin than that of early instars, suggesting that increased proteolytic activity on the toxin could also explain the low Cry1Ac toxicity in late instars.

Enhancement of Bacillus thuringiensis Cry1Ab and Cry1Fa Toxicity to Spodoptera frugiperda by Domain III Mutations Indicates There Are Two Limiting Steps in Toxicity as Defined by Receptor Binding and Protein Stability.

Bacillus thuringiensis Cry1Ab and Cry1Fa toxins are environmentally safe insecticides that control important insect pests. Spodoptera frugiperda is an important maize pest that shows low susceptibility to Cry1A toxins, in contrast to Cry1Fa, which is highly active against this pest and is used in transgenic maize for S. frugiperda control. The ß16 region from domain III of Cry1Ab has been shown to be involved in interactions with receptors such as alkaline phosphatase (ALP) or aminopeptidase (APN) in different lepidopteran insects. Alanine-scanning mutagenesis of amino acids of Cry1Ab ß16 (509STLRVN514) revealed that certain ß16 mutations, such as N514A, resulted in increased toxicity of Cry1Ab for S. frugiperda without affecting the toxicity for other lepidopteran larvae, such as Manduca sexta larvae. Exhaustive mutagenesis of N514 was performed, showing that the Cry1Ab N514F, N514H, N514K, N514L, N514Q, and N514S mutations increased the toxicity toward S. frugiperda A corresponding mutation was constructed in Cry1Fa (N507A). Toxicity assays of wild-type and mutant toxins (Cry1Ab, Cry1AbN514A, Cry1AbN514F, Cry1Fa, and Cry1FaN507A) against four S. frugiperda populations from Mexico and one from Brazil revealed that Cry1AbN514A and Cry1FaN507A consistently showed 3- to 18-fold increased toxicity against four of five S. frugiperda populations. In contrast, Cry1AbN514F showed increased toxicity in only two of the S. frugiperda populations analyzed. The mutants Cry1AbN514A and Cry1AbN514F showed greater stability to midgut protease treatment. In addition, binding analysis of the Cry1Ab mutants showed that the increased toxicity correlated with increased binding to brush border membrane vesicles and increased binding affinity for S. frugiperda ALP, APN, and cadherin receptors.IMPORTANCESpodoptera frugiperda is the main maize pest in South and North America and also is an invasive pest in different African countries. However, it is poorly controlled by Bacillus thuringiensis Cry1A toxins expressed in transgenic crops, which effectively control other lepidopteran pests. In contrast, maize expressing Cry1Fa is effective in the control of S. frugiperda, although its effectiveness is being lost due to resistance evolution. Some of the Cry1Ab domain III mutants characterized here show enhanced toxicity for S. frugiperda without loss of toxicity to Manduca sexta Thus, these Cry1Ab mutants could provide useful engineered toxins that, along with other Cry toxins, would be useful for developing transgenic maize expressing stacked proteins for the effective control of S. frugiperda and other lepidopteran pests in the field.

Spodoptera frugiperda (J. E. Smith) Aminopeptidase N1 Is a Functional Receptor of the Bacillus thuringiensis Cry1Ca Toxin.

Bacillus thuringiensis Cry1Ca is toxic to different Spodoptera species. The aims of this work were to identify the Cry1Ca-binding proteins in S. frugiperda, to provide evidence on their participation in toxicity, and to identify the Cry1Ca amino acid residues involved in receptor binding. Pulldown assays using Spodoptera frugiperda brush border membrane vesicles (BBMV) identified aminopeptidase N (APN), APN1, and APN2 isoforms as Cry1Ca-binding proteins. Cry1Ca alanine substitutions in all residues of domain III ß16 were characterized. Two ß16 nontoxic mutants (V505A and S506A) showed a correlative defect on binding to the recombinant S. frugiperda APN1 (SfAPN1). Finally, silencing the expression of APN1 transcript, by double-stranded RNA (dsRNA) feeding, showed that silenced larvae are more tolerant of the Cry1Ca toxin, which induced less than 40% mortality in silenced larvae whereas nonsilenced larvae had 100% mortality. Overall, our results show that Cry1Ca relies on APN1 binding through domain III ß16 to impart toxicity to S. frugiperdaIMPORTANCEBacillus thuringiensis Cry toxins rely on receptor binding to exert toxicity. Cry1Ca is toxic to different populations of S. frugiperda, a major corn pest in America. Nevertheless, the S. frugiperda midgut proteins that are involved in Cry1Ca toxicity have not been identified. Here we identified aminopeptidase N1 (APN1) as a functional receptor of Cry1Ca. Moreover, we showed that Cry1Ca domain III ß16 is involved in APN1 binding. These results give insights on potential target sites for improving Cry1Ca toxicity to S. frugiperda.

Helix α-3 inter-molecular salt bridges and conformational changes are essential for toxicity of Bacillus thuringiensis 3D-Cry toxin family.

Bacillus thuringiensis insecticidal Cry toxins break down larval midgut-cells after forming pores. The 3D-structures of Cry4Ba and Cry5Ba revealed a trimeric-oligomer after cleavage of helices α-1 and α-2a, where helix α-3 is extended and made contacts with adjacent monomers. Molecular dynamic simulations of Cry1Ab-oligomer model based on Cry4Ba-coordinates showed that E101 forms a salt-bridge with R99 from neighbor monomer. An additional salt bridge was identified in the trimeric-Cry5Ba, located at the extended helix α-3 in the region corresponding to the α-2b and α-3 loop. Both salt-bridges were analyzed by site directed mutagenesis. Single-point mutations in the Lepidoptera-specific Cry1Ab and Cry1Fa toxins were affected in toxicity, while reversed double-point mutant partially recovered the phenotype, consistent with a critical role of these salt-bridges. The single-point mutations in the salt-bridge at the extended helix α-3 of the nematicidal Cry5Ba were also non-toxic. The incorporation of this additional salt bridge into the nontoxic Cry1Ab-R99E mutant partially restored oligomerization and toxicity, supporting that the loop between α-2b and α-3 forms part of an extended helix α-3 upon oligomerization of Cry1 toxins. Overall, these results highlight the role in toxicity of salt-bridge formation between helices α-3 of adjacent monomers supporting a conformational change in helix α-3.

Engineering Bacillus thuringiensis Cyt1Aa toxin specificity from dipteran to lepidopteran toxicity.

The Cyt and Cry toxins are different pore-forming proteins produced by Bacillus thuringiensis bacteria, and used in insect-pests control. Cry-toxins have a complex mechanism involving interaction with several proteins in the insect gut such as aminopeptidase N (APN), alkaline phosphatase (ALP) and cadherin (CAD). It was shown that the loop regions of domain II of Cry toxins participate in receptor binding. Cyt-toxins are dipteran specific and interact with membrane lipids. We show that Cry1Ab domain II loop3 is involved in binding to APN, ALP and CAD receptors since point mutation Cry1Ab-G439D affected binding to these proteins. We hypothesized that construction of Cyt1A-hybrid proteins providing a binding site that recognizes gut proteins in lepidopteran larvae could result in improved Cyt1Aa toxin toward lepidopteran larvae. We constructed hybrid Cyt1Aa-loop3 proteins with increased binding interaction to Manduca sexta receptors and increased toxicity against two Lepidopteran pests, M. sexta and Plutella xylostella. The hybrid Cyt1Aa-loop3 proteins were severely affected in mosquitocidal activity and showed partial hemolytic activity but retained their capacity to synergize Cry11Aa toxicity against mosquitos. Our data show that insect specificity of Cyt1Aa toxin can be modified by introduction of loop regions from another non-related toxin with different insect specificity.