ABSTRACT
In Drosophila, neural stem cells or neuroblasts (NBs) acquire different identities according to their site of origin in the embryonic neuroectoderm. Their identity determines the number of times they will divide and the types of daughter cells they will generate. All NBs divide asymmetrically, with type I NBs undergoing self-renewal and generating another cell that will divide only once more. By contrast, a small set of NBs in the larval brain, type II NBs, divides differently, undergoing self-renewal and generating an intermediate neural progenitor (INP) that continues to divide asymmetrically several more times, generating larger lineages. In this study, we have analysed the origin of type II NBs and how they are specified. Our results indicate that these cells originate in three distinct clusters in the dorsal protocerebrum during stage 12 of embryonic development. Moreover, it appears that their specification requires the combined action of EGFR signalling and the activity of the related genes buttonhead and Drosophila Sp1 In addition, we also show that the INPs generated in the embryo enter quiescence at the end of embryogenesis, resuming proliferation during the larval stage.
Subject(s)
Cell Lineage/physiology , Drosophila Proteins/metabolism , Drosophila/embryology , Neural Stem Cells , Neurogenesis/physiology , Animals , Cell Differentiation/genetics , Drosophila/cytology , Drosophila/metabolism , Gene Expression Regulation, Developmental , Larva/cytology , Larva/metabolism , Larva/physiology , Nerve Tissue Proteins/metabolism , Signal Transduction , Transcription Factors/metabolismABSTRACT
The insect wing is a key evolutionary innovation that was essential for insect diversification. Yet despite its importance, there is still debate about its evolutionary origins. Two main hypotheses have been proposed: the paranotal hypothesis, which suggests that wings evolved as an extension of the dorsal thorax, and the gill-exite hypothesis, which proposes that wings were derived from a modification of a pre-existing branch at the dorsal base (subcoxa) of the leg. Here, we address this question by studying how wing fates are initially specified during Drosophila embryogenesis, by characterizing a cis-regulatory module (CRM) from the snail (sna) gene, sna-DP (for dorsal primordia). sna-DP specifically marks the early primordia for both the wing and haltere, collectively referred to as the DP. We found that the inputs that activate sna-DP are distinct from those that activate Distalless, a marker for leg fates. Further, in genetic backgrounds in which the leg primordia are absent, the DP are still partially specified. However, lineage-tracing experiments demonstrate that cells from the early leg primordia contribute to both ventral and dorsal appendage fates. Together, these results suggest that the wings of Drosophila have a dual developmental origin: two groups of cells, one ventral and one more dorsal, give rise to the mature wing. We suggest that the dual developmental origins of the wing may be a molecular remnant of the evolutionary history of this appendage, in which cells of the subcoxa of the leg coalesced with dorsal outgrowths to evolve a dorsal appendage with motor control.
Subject(s)
Drosophila melanogaster/embryology , Wings, Animal/embryology , Animals , Cell Lineage , Gene Expression Regulation, Developmental , Snail Family Transcription Factors/genetics , Snail Family Transcription Factors/metabolismABSTRACT
Las limitaciones de la colonoscopia virtual radican en la complejidad del cumplimiento de las instrucciones de preparación previa, con modelos diferentes para diabéticos y no diabéticos, y diferente producto laxante empleado, sintomatología y duración. Este estudio diseña una intervención enfermera que minimiza los rechazos de pacientes que, por mala limpieza del colon, no pueden realizar la colonoscopia virtual. Método. Se distribuyen de forma aleatoria los pacientes que cumplen los criterios de inclusión en dos grupos: Grupo control: se siguen según el protocolo previo del servicio. Grupo intervención: acudieron a una consulta de enfermería previa a la colonoscopia virtual, donde se les realiza una encuesta sobre su salud y se determina y explica detalladamente el mejor protocolo de preparación del colon para cada paciente, así como el proceso de colonoscopia virtual. Objetivo. Comprobar la efectividad de una consulta de enfermería para la preparación de colonoscopias virtuales en términos de aumento de la tasa de colonoscopias virtuales interpretables o de calidad. Resultados. Se redujo significativamente la puntuación en ansiedad de los pacientes tras la consulta (6.5 +/-2.5 antes frente a 5.5+/-2.4 después; p < 0.001). El grupo intervención redujo en casi un 4 % el número de pruebas complementarias precisadas por el grupo control. La recitación de pacientes fue un 6 % inferior en el grupo intervención que en el grupo control. Conclusiones. Se podría producir un ahorro de 15 990 euros anuales, puesto que se redujo la recitación de pacientes y la realización de pruebas diagnósticas complementarias al nivel del grupo intervención (AU)
The limitations of virtual colonoscopy lie on the complexity of patients previous preparation process. There are different models for diabetic and non-diabetic patients, and these models also differ depending on the laxative product used, the symptomatology and its duration. This study designs a nursing intervention to minimize refusal of patients who, due to bad colon cleansing, cannot be subject to a virtual colonoscopy. Method. Patients who met the inclusion criteria were randomized into two groups. Control group: patients were treated according to the previous protocol of service. Experimental group: patients attended a nurse consultation appointment prior to the virtual colonoscopy, where nurses implemented a questionnaire about the patients health and determined the best protocol for bowel preparation according to each patient, explaining the process in detail. The virtual colonoscopy procedure was also clarified during the nursing appointed consultation. Objective. To determine the effectiveness of nursing work in the preparation of virtual colonoscopy in terms of increasing the rate of interpretable or high-quality virtual colonoscopies. Results. The anxiety score for patients was significantly reduced after the nursing consultation (6.5 +/-2.5 before vs. 5.5 +/- 2.4 after; p < 0.001). The experimental group showed a reduction of almost 4 % in number of complementary tests necessary for the control group. The reappointment of patients in the experimental group was 6 % lower than in the control group. Conclusions. The experimental group showed that savings of 15.990 a year could be achieved by reducing both: reappointment of patients and need for complementary diagnostic tests (AU)
