Sharp boundaries of Dpp signalling trigger local cell death required for Drosophila leg morphogenesis

Article available at http://dx.doi.org/10.1038/ncb1518Morphogens are secreted signalling molecules that govern many developmental processes1. In the Drosophila wing disc, the transforming growth factor (TGF) homologue Decapentaplegic (Dpp) forms a smooth gradient and specifies cell fate by conferring a defined value of morphogen activity. Thus, neighbouring cells have similar amounts of Dpp protein, and if a sharp discontinuity in Dpp activity is generated between these cells, Jun kinase (JNK)-dependent apoptosis is triggered to restore graded positional information2, 3. To date, it has been assumed that this apoptotic process is only activated when normal signalling is distorted. However, we now show that a similar process occurs during normal development: rupture in Dpp activity occurs during normal segmentation of the distal legs of Drosophila. This sharp boundary of Dpp signalling, independently of the absolute level of Dpp activity, induces a JNK—reaper-dependent apoptosis required for the morphogenesis of a particular structure of the leg, the joint. Our results show that Dpp could induce a developmental programme not only in a concentration dependent manner, but also by the creation of a sharp boundary of Dpp activity. Furthermore, the same process could be used either to restore a normal pattern in response to artificial disturbance or to direct a morphogenetic process.This work has been supported by grants from the Dirección General de Investigación Científica y Técnica (BMC 2002-00300), the Comunidad Autónoma de Madrid (08.1/0031/2001.1 and GR/SAL/0147/2004) and an Institutional Grant from the Fundación Ramón Areces. C.M. is a recipient of a Formación del Personal Universitario (F.P.U.) fellowship from the Ministerio de Educación y Ciencia.Peer reviewe

The Gene Regulatory Cascade Linking Proneural Specification with Differentiation in Drosophila Sensory Neurons

Temporal expression profiling of sensory precursor cells reveals how the atonal proneural transcription factor regulates a specialized neuronal differentiation pathway

Prevalence of self-reported constipation in adults from the general population

OBJECTIVE To estimate the prevalence of self-reported constipation and associated factors in the general population of a Brazilian city. METHOD Secondary analysis of an epidemiological study, population-based, cross-sectional study, about bowel habits of Brazilian population. A total of 2,162 individuals were interviewed using two instruments: sociodemographic data and the adapted and validated Brazilian version of the "Bowel Function in the Community" tool. RESULTS There was a prevalence of 25.2% for the self-reported constipation, 37.2% among women and 10.2% among men. Stroke and old age were associated with constipation in the three statistical models used. CONCLUSION The prevalence found showed to be similar to the findings in the literature, although some associated factors obtained here have never been investigated

Robust Target Gene Discovery through Transcriptome Perturbations and Genome-Wide Enhancer Predictions in Drosophila Uncovers a Regulatory Basis for Sensory Specification

CisTarget X is a novel computational method that accurately predicts Atonal governed regulatory networks in the retina of the fruit fly

Illness perceptions mediate the relationship between bowel symptom severity and health-related quality of life in IBS patients

PURPOSE: Irritable bowel syndrome (IBS) is a functional bowel disorder with a large negative impact on HRQOL. The present study examines whether severity of bowel symptoms is directly related to HRQOL, and/or indirectly, mediated by the patients’ illness perceptions. METHODS: Patients were recruited from an IBS support group (N = 123), and data were collected online. HRQOL was measured with the Quality of Life Measure for Persons with IBS and illness perceptions with the brief Illness Perception Questionnaire. Mediation models were tested using the bootstrapping procedure developed by Hayes. RESULTS: Irritable bowel syndrome symptom severity is directly related to total HRQOL and its subscales; after entering the mediator variables (i.e. the patients’ illness perceptions) into the model, this direct association remained only significant for total HRQOL. The relationship between bowel symptom severity and total HRQOL was partially mediated by illness perceptions, and its relationship with each of the HRQOL subscales was fully mediated by the patients’ illness perceptions. Perceived consequences were a mediator of the relationship between bowel symptom severity, total HRQOL as well as its subscales, with the exception of Sexuality. CONCLUSIONS: Bowel symptom severity not only has a direct relationship with HRQOL, but also an indirect relationship via the patients’ cognitive and emotional representations of their illness. In order to better understand this relationship, future research should not only include illness perceptions but also assess cognitive and behavioural coping responses. Clinicians wanting to improve patients’ HRQOL should not only focus on the patients’ symptoms, but also on their illness beliefs and coping responses

Various Size-sorting Processes for Millimeter-sized Particles in the Sun's Protoplanetary Disk? Evidence from Chondrules in Ordinary Chondrites

Chondrules are approximately millimeter-sized beads of crystallized silicate melt. They formed mainly in the first similar to 3 Ma of the Sun's protoplanetary disk and are the main constituents of chondritic asteroids. Here we report on the size-frequency distributions (2D and 3D) of chondrules in the brecciated ordinary chondrite (OC) Northwest Africa (NWA) 5205. We investigated three large (centimeter-to decimeter-sized) chondritic lithic clasts of a particular textural type (cluster chondrite) with eye-catching different chondrule sizes. One clast shows the largest mean chondrule size (similar to 1.5 mm) ever measured in a chondrite. As in the other OCs, we find a positive correlation between the minimum and mean chondrule size, which we consider as an argument for chondrule size sorting. Chondrule size-frequency distributions in the clasts are distinctly more symmetric than the about lognormal distributions in other OCs. Furthermore, we find a co-enrichment of chondrule types with a priori small mean sizes (type I, porphyritic) in clasts with overall small mean chondrule sizes. We consider this as the fingerprint of an additional/second size-sorting process, which acted later on these chondrule populations. This process possibly subdivided a typical LL-type chondrule population into several subpopulations with different mean chondrule sizes. We speculate that this second sorting occurred in a unidirectional gas stream or headwind, e.g., by settling of chondrules through an asteroidal atmosphere or interaction with an expanding impact plume. Possibly, fine-grained matrix was almost completely removed by this, and the size-sorted chondrule subpopulations accreted in a hot state separately in different regions of the asteroid