Knockdown of double-stranded RNases (dsRNases) enhances oral RNA interference (RNAi) in the corn leafhopper, Dalbulus maidis.

The leafhopper Dalbulus maidis is a harmful pest that causes severe damage to corn crops. Conventional chemical pesticides have negative environmental impacts, emphasizing the need for alternative solutions. RNA interference (RNAi) is a more specific and environmentally friendly method for controlling pests and reducing the negative impacts of current pest management practices. Previous studies have shown that orally administered double-stranded RNA (dsRNA) is less effective than injection protocols in silencing genes. This study focuses on identifying and understanding the role of double-stranded ribonucleases (dsRNases) in limiting the efficiency of oral RNAi in D. maidis. Three dsRNases were identified and characterized, with Dmai-dsRNase-2 being highly expressed in the midgut and salivary glands. An ex vivo degradation assay revealed significant nuclease activity, resulting in high instability of dsRNA when exposed to tissue homogenates. Silencing Dmai-dsRNase-2 improved the insects' response to the dsRNA targeting the gene of interest, providing evidence of dsRNases involvement in oral RNAi efficiency. Therefore, administering both dsRNase-specific and target gene-specific-dsRNAs simultaneously is a promising approach to increase the efficiency of oral RNAi and should be considered in future control strategies.

Dynamics of maternal gene expression in Rhodnius prolixus.

The study of developmental processes in Rhodnius prolixus has recently advanced with the sequencing of the genome. In this work, we analyze the maternal gene expression driving oogenesis and early embryogenesis in R. prolixus. We examined the transcriptional profile of mRNAs to establish the genes expressed across the ovary, unfertilized eggs and different embryonic stages of R. prolixus until the formation of the germ band anlage (0, 12, 24, and 48 h post egg laying). We identified 81 putative maternal and ovary-related genes and validated their expression by qRT-PCR. We validate the function of the ortholog gene Bicaudal-D (Rp-BicD) by in situ hybridization and parental RNAi. Consistent with a role in oogenesis and early development of R. prolixus, we show that lack of Rp-BicD does not significantly affect oogenesis but impairs the formation of the blastoderm. Based on our findings, we propose three times of action for maternal genes during oogenesis and embryogenesis in R. prolixus.

Development of efficient RNAi methods in the corn leafhopper Dalbulus maidis, a promising application for pest control.

BACKGROUND: The corn leafhopper Dalbulus maidis is the main vector of important stunting pathogens that affect maize production. Currently, there are no effective methods available to manage this pest without adverse impact on the environment. In this context, genomic-based technologies such as RNA interference (RNAi) provide a more environmentally friendly pest control strategy. Therefore, we aimed to assess the application of RNAi in D. maidis and determine the function of a candidate gene related to insect reproduction and propagation. RESULTS: We have characterized the core RNAi genes and evaluated the functionality of the RNAi machinery. We assessed the potential of RNAi technology in D. maidis via injection or ingestion of double-stranded RNA (dsRNA) to adult females. We chose Bicaudal C (BicC) as a target gene due to its important role during insect oogenesis. Administration of dsRNABicC caused significant reductions in the transcript levels (fold changes up to 170 times) and ovipositions. Phenotypic analysis of the ovaries revealed alterations in oocyte development, providing additional confirmation for our results and supporting the idea that Dmai-BicC is a key player of D. maidis oogenesis. CONCLUSION: This is, to our knowledge, the first report of efficient RNAi in D. maidis. We believe our findings provide a starting point for future control strategies against one of the most important maize pests in the Americas. © 2022 Society of Chemical Industry.

Bicaudal C is required for the function of the follicular epithelium during oogenesis in Rhodnius prolixus.

The morphology and physiology of the oogenesis have been well studied in the vector of Chagas disease Rhodnius prolixus. However, the molecular interactions that regulate the process of egg formation, key for the reproductive cycle of the vector, is still largely unknown. In order to understand the molecular and cellular basis of the oogenesis, we examined the function of the gene Bicaudal C (BicC) during oogenesis and early development of R. prolixus. We show that R. prolixus BicC (Rp-BicC) gene is expressed in the germarium, with cytoplasmic distribution, as well as in the follicular epithelium of the developing oocytes. RNAi silencing of Rp-BicC resulted in sterile females that lay few, small, non-viable eggs. The ovaries are reduced in size and show a disarray of the follicular epithelium. This indicates that Rp-BicC has a central role in the regulation of oogenesis. Although the follicular cells are able to form the chorion, the uptake of vitelline by the oocytes is compromised. We show evidence that the polarity of the follicular epithelium and the endocytic pathway, which are crucial for the proper yolk deposition, are affected. This study provides insights into the molecular mechanisms underlying oocyte development and show that Rp-BicC is important for de developmental of the egg and, therefore, a key player in the reproduction of this insect.

Reuniones periódicas de gastroenterología y hepatología con atención primaria. Motivos de consulta / Periodic gastroenterology and hepatology meetings with primary care. Reasons for consultation

Introducción: la presión asistencial, el envejecimiento poblacional y el aumento de enfermedades crónicas incrementan las derivaciones desde atención primaria, pudiendo sobrecargar el sistema sanitario. Se han efectuado diversas intervenciones que intentan mejorar estos aspectos. Objetivos: valorar motivos de consulta más frecuentes de los médicos generales, tanto en consultas compartidas como en sesiones clínicas realizadas conjuntamente con un especialista consultor en atención primaria, en medios urbano y rural, y su repercusión sobre las derivaciones a primeras consultas de gastroenterología. Material y métodos: se efectúa una intervención de tipo fundamentalmente formativo, consistente en reuniones periódicas en dos centros de atención primaria (urbano y rural), con consultas compartidas y sesiones clínicas en relación con pacientes y temas de gastroenterología. El periodo de intervención (dividido en dos subperiodos) se comparó con un periodo control. Resultados: los problemas más comentados corresponden al tracto digestivo inferior, seguido de patología hepática y del tracto digestivo superior. Se encontraron diferencias significativas en la distribución de diagnósticos entre los dos centros en las consultas compartidas. Se detectó un descenso relativo o porcentual de las derivaciones a nivel global en ambos subperiodos, significativo solo en el primero (51,45 %), así como a nivel rural (45,24 %). Conclusión: los motivos de consulta habituales fueron similares en los medios urbano y rural, con cierto predominio del tracto digestivo inferior. La mayoría pueden ser resueltos desde atención primaria, con el apoyo del consultor especialista. Hay repercusión en las derivaciones a las consultas externas de la especialidad, sobre todo a nivel rural (AU)

Introduction: care overload, aging of population, and increased chronic diseases lead to increased referrals from primary care, which may sometimes overload the health system. Thus, different interventions have been carried out attempting to improve these aspects. Objectives: to assess the most frequent causes of consultation of general physicians, both in joint consultations and clinical sessions held jointly with specialist consultant in primary care, in the urban and rural setting, and the influence on referrals to first consultations of gastroenterology. Material and methods: a mainly training type of intervention was carried out, consisting of regular meetings in both urban and rural primary care center, to perform joint consultations and clinical sessions on patients and topics related to the specialty of gastroenterology. The intervention period (divided in two subperiods) was compared with a control period. Results: most reasons for consultation were those corresponding to lower gastrointestinal tract, followed by liver disease and upper gastrointestinal tract. Significant differences were only found in distribution of diagnoses between the two centers in joint consultations. There was a relative (percent) decrease in referrals at the global level in both subperiods, only significant in the first (51.45 %), as well as in rural setting (45.24 %). Conclusion: common consultations motifs were similar in urban and rural settings, with some relevance of lower gastrointestinal tract disease. Most of them can be solved at primary care, with the help of consultant specialist. There is impact on referrals to the outpatient first consultations of gastroenterology, mainly in rural setting (AU)

Periodic gastroenterology and hepatology meetings with primary care. Reasons for consultation.

INTRODUCTION: care overload, aging of population, and increased chronic diseases lead to increased referrals from primary care, which may sometimes overload the health system. Thus, different interventions have been carried out attempting to improve these aspects. OBJECTIVES: to assess the most frequent causes of consultation of general physicians, both in joint consultations and clinical sessions held jointly with specialist consultant in primary care, in the urban and rural setting, and the influence on referrals to first consultations of gastroenterology. MATERIAL AND METHODS: a mainly training type of intervention was carried out, consisting of regular meetings in both urban and rural primary care center, to perform joint consultations and clinical sessions on patients and topics related to the specialty of gastroenterology. The intervention period (divided in two subperiods) was compared with a control period. RESULTS: most reasons for consultation were those corresponding to lower gastrointestinal tract, followed by liver disease and upper gastrointestinal tract. Significant differences were only found in distribution of diagnoses between the two centers in joint consultations. There was a relative (percent) decrease in referrals at the global level in both subperiods, only significant in the first (51.45 %), as well as in rural setting (45.24 %). CONCLUSION: common consultations motifs were similar in urban and rural settings, with some relevance of lower gastrointestinal tract disease. Most of them can be solved at primary care, with the help of consultant specialist. There is impact on referrals to the outpatient first consultations of gastroenterology, mainly in rural setting.

Diagnóstico de laboratorio y evolución serológica de pacientes con tularemia / Laboratory diagnosis and serologic evolution of patients with tularemia

Fundamento: La tularemia era una enfermedad prácticamente inexistente en España hasta finales de 1997, cuando se declaró un brote epidémico en nuestra comunidad. El objetivo de nuestro trabajo ha sido estudiar los datos existentes sobre el diagnóstico microbiológico de 55 pacientes que sufrieron tularemia. Pacientes y métodos: Se obtuvieron 32 muestras para cultivo pertenecientes a 19 pacientes y 151 sueros correspondientes a 55 pacientes. El diagnóstico serológico se realizó mediante seroaglutinación en tubo y microaglutinación. En todos los sueros se realizó una seroaglutinación de Wright (SAW) y un test de Coombs frente a Brucella y seroaglutinaciones frente a Yersinia enterocolitica O:9, Yersinia enterocolitica O:3 y Proteus OX 19. Resultados: Se aisló F. tularensis en dos muestras (6,25 por ciento) de las 32 estudiadas. Se obtuvieron títulos mayores o iguales a 1/160 en el 78,2 por ciento y en el 74,5 por ciento de los sueros iniciales por sero-aglutinación en tubo y microaglutinación, respectivamente. La correlación entre las dos pruebas fue de 0,80 (p < 0,001). Se observó fenómeno de prozona en el 59,9 por ciento de los sueros, y reactividad cruzada frente a Brucella y Proteus OX19 en el 9,3 y el 22,8 por ciento, respectivamente. No se observó reactividad cruzada con Y. enterocolitica O:3 y O:9. Conclusiones: El cultivo de F. tularensis es poco sensible. La correlación obtenida entre la seroaglutinación en tubo y microaglutinación es buena. Ambas técnicas son útiles en el diagnóstico de la tularemia, con algunas ventajas de la microaglutinación sobre la aglutinación. (AU)