Intestinal stem cell proliferation and epithelial homeostasis in the adult Drosophila midgut

Adult tissue homeostasis requires a tight balance between the removal of old or damaged cells and the production of new ones. Such processes are usually driven by dedicated stem cells that reside within specific tissue locations or niches. The intestinal epithelium has a remarkable regenerative capacity, which has made it a prime paradigm for the study of stem cell-driven tissue self-renewal. The discovery of the presence of stem cells in the adult midgut of the fruit fly Drosophila melanogaster has significantly impacted our understanding of the role of stem cells in intestinal homeostasis. Here we will review the current knowledge of the main mechanisms involved in the regulation of tissue homeostasis in the adult Drosophila midgut, with a focus on the role of stem cells in this process. We will also discuss processes involving acute or chronic disruption of normal intestinal homeostasis such as damage-induced regeneration and ageing

Wnt signalling in intestinal stem cells: lessons from mice and flies

Adult stem cells play critical roles in the basal maintenance of tissue integrity, also known as homeostasis, and in tissue regeneration following damage. The highly conserved Wnt signalling pathway is a key regulator of stem cell fate. In the gastrointestinal tract, Wnt signalling activation drives homeostasis and damage-induced repair. Additionally, deregulated Wnt signalling is a common hallmark of age-associated tissue dysfunction and cancer. Studies using mouse and fruit fly models have greatly improved our understanding of the functional contribution of the Wnt signalling pathway in adult intestinal biology. Here, we summarize the latest knowledge acquired from mouse and Drosophila research regarding canonical Wnt signalling and its key functions during stem cell driven intestinal homeostasis, regeneration, ageing and cancer

Difficulties in HIV/AIDS prevention in rural Malawi

Background : Recent research on the HIV epidemic in sub-Saharan Africa has highlighted the relevance of married individuals' extramarital sexual behavior for the spread of the disease. At the same time, there is social disapproval of sexual infidelity. Objective : This article examines the extent to which Malawian married men's likelihood of having extramarital sex is influenced by their expectations about the prevalence of extramarital relationships in their social network. It also explores whether this effect depends on the network density, and whether it is also observed when the extramarital behavior of a particularly influential actor is controlled for. Methods : Data from the last two waves, 2004 and 2006, of the longitudinal survey provided by the Malawi Diffusion and Ideational Change Project are analyzed both cross-sectionally and through a panel analysis with fixed effects. The longitudinal approach enables the researcher to deal with the potential non-random distribution of social interactions among respondents, which bias the estimation in the cross-sectional analysis. Results : Married men's expectations about the prevalence of extramarital sexual relationships in the network were shown to have a substantial influence on their extramarital behavior, and the impact was found to be bigger in dense networks. In addition, there was some evidence that the perceived dominant behavior in the peer group is relevant, independent of the extramarital behavior of the respondents' best friends

Drosophila as a model system to study nonautonomous mechanisms affecting tumour growth and cell death

The study of cancer has represented a central focus in medical research for over a century. The great complexity and constant evolution of the pathology require the use of multiple research model systems and interdisciplinary approaches. This is necessary in order to achieve a comprehensive understanding into the mechanisms driving disease initiation and progression, to aid the development of appropriate therapies. In recent decades, the fruit fly Drosophila melanogaster and its associated powerful genetic tools have become a very attractive model system to study tumour-intrinsic and non-tumour-derived processes that mediate tumour development in vivo. In this review, we will summarize recent work on Drosophila as a model system to study cancer biology. We will focus on the interactions between tumours and their microenvironment, including extrinsic mechanisms affecting tumour growth and how tumours impact systemic host physiology

Basic and translational models of cooperative oncogenesis

No abstract available

c-Src drives intestinal regeneration and transformation

The non‐receptor tyrosine kinase c‐Src, hereafter referred to as Src, is overexpressed or activated in multiple human malignancies. There has been much speculation about the functional role of Src in colorectal cancer (CRC), with Src amplification and potential activating mutations in up to 20% of the human tumours, although this has never been addressed due to multiple redundant family members. Here, we have used the adult <i>Drosophila</i> and mouse intestinal epithelium as paradigms to define a role for Src during tissue homeostasis, damage‐induced regeneration and hyperplasia. Through genetic gain and loss of function experiments, we demonstrate that Src is necessary and sufficient to drive intestinal stem cell (ISC) proliferation during tissue self‐renewal, regeneration and tumourigenesis. Surprisingly, Src plays a non‐redundant role in the mouse intestine, which cannot be substituted by the other family kinases Fyn and Yes. Mechanistically, we show that Src drives ISC proliferation through upregulation of EGFR and activation of Ras/MAPK and Stat3 signalling. Therefore, we demonstrate a novel essential role for Src in intestinal stem/progenitor cell proliferation and tumourigenesis initiation <i>in vivo.</i&gt

Efecto antiinflamatorio del extracto etanólico de las hojas de Hibiscus rosa-sinensis (cucarda) en ratones albinos

El estudio realizado buscó determinar el efecto antinflamatorio del extracto etanólico de las hojas de Hibiscus rosa-sinensis (cucarda) en ratones albinos, se emplearon 30 ratones albinos divididos en cinco grupos quienes recibieron suero fisiológico 2mL/Kg, el segundo grupo recibió el fármaco Dexametasona 4 mg/kg , el tercer, cuarto y quinto grupo recibieron el extracto de cucarda en concentraciones de 50, 100 y 200 mg/Kg respectivamente, se encontró un porcentaje de rendimiento del extracto de las hojas de cucarda fue de 8.5%, así también el estudio fitoquímico identificó la presencia de flavonoides, taninos, saponinas y alcaloides. También se encontró que el extracto de cucarda a dosis de 200 mg/kg presentó la mayor eficacia antiinflamatoria, manteniendo los parámetros de fórmula leucocitaria dentro de los valores normales, así como HDL y PCR. Concluyendo que el extracto etanólico de las hojas de Hibiscus rosa-sinensis posee actividad antiinflamatoria en ratones albinosTesi

Mecanismos de transferencias monetarias condicionadas a los sectores en situación de pobreza en el Ecuador entre los años 2007-2012

Esta tesis analiza los efectos del Bono de Desarrollo Humano (BDH), política de protección social no contributiva cuyos inicios datan en 1998, que empezó como una transferencia económica sin condicionalidades, para después a constituirse en la política de protección social de mayor continuidad en el Ecuador en los últimos veinte años, y en el Programa de Transferencias Condicionadas (PTC) de mayor cobertura en América Latina. El examen académico en torno al BDH se ha llevado a cabo -sobre todo- en las investigaciones de tesis de estudiantes de todos los niveles superiores, más que en el debate nacional de los analistas expertos que desde las universidades estudian y cuestionan métodos y resultados. Iniciativas similares, como el mexicano PDHO y el brasileño PBM sí se han beneficiado de este aporte académico que ha cuestionado de manera constante: (i) su efecto marginal sobre la persistente desigualdad en la región y su efecto limitado en la reducción de la pobreza, (ii) la conveniencia de mantener o no las condicionalidades y (iii) las relaciones clientelares entre el Gobierno y los beneficiarios. La investigación inicia con la revisión del debate académico sobre la protección social en América Latina. Esta revisión permite identificar dos enfoques: el primero, el de la economía política, que centra sus esfuerzos en encontrar la explicación, tanto de los orígenes y de las circunstancias en las que se crearon cuanto de los cambios de los sistemas de protección social en la región; el segundo se ocupa de los efectos o repercusiones económicas, políticas y sociales de los PTC. La tesis dialoga con estos dos enfoques. En primera instancia utiliza la economía política para contextualizar el caso ecuatoriano. En un segundo momento presenta y discute los resultados de una investigación cualitativa con el método de la entrevista en profundidad de los efectos del BDH en la vida de sus beneficiarios. El aporte de esta tesis radica en señalar un camino teórico y metodológico para investigar las políticas de transferencias económicas con condicionalidades y sus efectos, a la vez que incorpora el estudio del caso ecuatoriano a la literatura existente desde un enfoque cualitativo. Entre las varias conclusiones a que llega esta tesis se halla que la implementación de este tipo de metodología redistributiva de ingresos con focalización en la población perteneciente a los quintiles más bajos de ingresos es, sin duda, una necesidad de los países cuya configuración social es originariamente de gran desigualdad. Asimismo, es innegable que el diseño del programa del BDH tiene un decidido sesgo de género que podría perjudicar a las mujeres

A neuronal relay mediates a nutrient responsive gut/fat body axis regulating energy homeostasis in adult Drosophila

The control of systemic metabolic homeostasis involves complex inter-tissue programs that coordinate energy production, storage, and consumption, to maintain organismal fitness upon environmental challenges. The mechanisms driving such programs are largely unknown. Here, we show that enteroendocrine cells in the adult Drosophila intestine respond to nutrients by secreting the hormone Bursicon α, which signals via its neuronal receptor DLgr2. Bursicon α/DLgr2 regulate energy metabolism through a neuronal relay leading to the restriction of glucagon-like, adipokinetic hormone (AKH) production by the corpora cardiaca and subsequent modulation of AKH receptor signaling within the adipose tissue. Impaired Bursicon α/DLgr2 signaling leads to exacerbated glucose oxidation and depletion of energy stores with consequent reduced organismal resistance to nutrient restrictive conditions. Altogether, our work reveals an intestinal/neuronal/adipose tissue inter-organ communication network that is essential to restrict the use of energy and that may provide insights into the physiopathology of endocrine-regulated metabolic homeostasis

ACCEM observation strategy.

International audienceACCEM is an NGO that works in favour of refugees and immigrants in Spain. Since 1996, ACCEM has developed a strategy of observation that articulates national observation and local observatories. The objective of the local observatories is to improve the services which are offered to the migrants, thanks to a better knowledge of their needs and to the use of tools of territorial intelligence, CATALYSE and the trees of knowledge. Since 1996, the Gorion national observatory has gathered in Madrid the individual data of migrants from the regional centres and from the different programmes that were carried out by ACCEM. It provides a wider knowledge of the migrants and of their different demand profiles. Thus, it allows better programming the actions. It is also possible to answer the administration, economic actors and local centres demands of information about the actions and programmes. In the same way, two local observatories were developed in GIJÓN and SIGÜENZA in partnership with the local services and the public associations. The objective was to answer in a global way the needs of the migrants whilst establishing and reinforcing the synergies between the services in the respect of the local specificities. They notably improved the knowledge of the migrant population in its diversity within the community. They allowed us putting in practice the adapted individual answers but also improving the well-being of the territorial communities. They developed new "satellites" observatories that are respectively in OVIEDO and in GUADALAJARA. Since 2004, ACCEM has projected to develop a larger network of local observatories on the basis of these experiences. The objective is to harmonize a common language, to widen the vision of the needs and to improve the articulation between the three levels: local, regional and national. In a first time, the CATALYSE tools were harmonized in each observatory by all the partners who are involved in the latter. From now on, they are harmonized in all the observatories and they are used by two new ones, in SEVILLA and in LEÓN. Now, the project e-gorrion aims at putting online the tools to make them more accessible and to develop some answers in real time