<i>ATP5PO </i>levels regulate enteric nervous system development in zebrafish, linking Hirschsprung disease to Down Syndrome

Hirschsprung disease (HSCR) is a complex genetic disorder characterized by the absence of enteric nervous system (ENS) in the distal region of the intestine. Down Syndrome (DS) patients have a &gt;50-fold higher risk of developing HSCR than the general population, suggesting that overexpression of human chromosome 21 (Hsa21) genes contribute to HSCR etiology. However, identification of responsible genes remains challenging. Here, we describe a genetic screening of potential candidate genes located on Hsa21, using the zebrafish. Candidate genes were located in the DS-HSCR susceptibility region, expressed in the human intestine, were known potential biomarkers for DS prenatal diagnosis, and were present in the zebrafish genome. With this approach, four genes were selected: RCAN1, ITSN1, ATP5PO and SUMO3. However, only overexpression of ATP5PO, coding for a component of the mitochondrial ATPase, led to significant reduction of ENS cells. Paradoxically, in vitro studies showed that overexpression of ATP5PO led to a reduction of ATP5PO protein levels. Impaired neuronal differentiation and reduced mitochondrial ATP production, were also detected in vitro, after overexpression of ATP5PO in a neuroblastoma cell line. Finally, epistasis was observed between ATP5PO and ret, the most important HSCR gene. Taken together, our results identify ATP5PO as the gene responsible for the increased risk of HSCR in DS patients in particular if RET variants are also present, and show that a balanced expression of ATP5PO is required for normal ENS development.</p

Construction d'un dilatomètre de haute précision. La dilatation du cuivre

A precision direct reading dilatometer for the temperature range from — 190 °C to 700 °C has been constructed. The characteristics of the apparatus are described and its possibilities are illustrated by results obtained on copper.On a construit un dilatomètre très simple qui permet la détermination précise de la dilatation thermique des solides. Une bonne idée de sa qualité est obtenue en comparant les résultats pour la dilatation du cuivre avec ceux de la littérature

Error, communication and learning in ant societies

When large food sources are discovered, many species recruit using different mechanisms. Numerous recruits do not reach the food source and explore the foraging area. These ants make new discoveries. The interplay between communication and exploration generates collective and efficient structures. This organisation is discussed in relation to the mechanisms of recruitment, quality and degree of aggregation of food-sources and territorial marking. This first organization, characteristic of large colonies, is compared to another foraging organisation: small societies of deterministic and specialised foragers rarely communicating together.info:eu-repo/semantics/publishe

Grain-boundary embrittlement in highly irradiated 15-15Ti austenitic steel

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Autocatalysis as a source of synchronised rhythmical activity in social insects

SCOPUS: ar.jinfo:eu-repo/semantics/publishe