Alfonso Martínez-Arias

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BACKGROUND The adhesion of two epithelial sheets is a fundamental process that occurs throughout embryogenesis and during wound repair. Sealing of the dorsal epidermis along the midline of the Drosophila embryo provides a genetically tractable model to analyse the closure of such holes. Several studies indicate that the actin cytoskeleton plays a critical(More)
One of the principal functions of any epithelium in the embryonic or adult organism is to act as a self-sealing barrier layer. From the earliest stages of development, embryonic epithelia are required to close naturally occurring holes and to fuse wherever two free edges are brought together, and at the simplest level that is precisely what the epidermis(More)
Throughout development, a series of epithelial movements and fusions occur that collectively shape the embryo. They are dependent on coordinated reorganizations and contractions of the actin cytoskeleton within defined populations of epithelial cells. One paradigm morphogenetic movement, dorsal closure in the Drosophila embryo, involves closure of a dorsal(More)
BACKGROUND The Drosophila Notch protein is a receptor that controls cell fate during embryonic development, particularly in lateral inhibition, a process that acts on groups of cells that share a particular developmental potential to restrict the number of cells that will adopt that cell fate. The process of lateral inhibition is implemented by the nuclear(More)
The Drosophila adult posterior midgut has been identified as a powerful system in which to study mechanisms that control intestinal maintenance, in normal conditions as well as during injury or infection. Early work on this system has established a model of tissue turnover based on the asymmetric division of intestinal stem cells. From the quantitative(More)
Wnt genes encode secreted signalling molecules involved in a number of basic developmental processes. In Drosophila, wingless and DWnt-4 are two physically clustered Wnt genes, which are transcribed in overlapping patterns during embryogenesis and, in several instances, are controlled by the same regulatory molecules. To address the question of the(More)
A population of mouse embryonic stem (ES) cells is characterized by a distribution of Nanog, a gene whose expression is associated with the degree of pluripotency. Cells exhibiting high levels of Nanog maintain a state of pluripotency, while those with low levels are more likely to undergo differentiation. Using a cell line with a fluorescence tag for Nanog(More)
Understanding the mechanisms that underlie pattern formation is one of the major challenges of developmental biology. The complexity and beauty of the patterns on butterfly wings, fish scales, or bird feathers are not only remarkable products of developmental processes but puzzles that tease our intellects. If we are to understand these beautiful products(More)
BACKGROUND Armadillo, the Drosophila orthologue of vertebrate ss-catenin, plays a dual role as the key effector of Wingless/Wnt1 signalling, and as a bridge between E-Cadherin and the actin cytoskeleton. In the absence of ligand, Armadillo is phosphorylated and targeted to the proteasome. Upon binding of Wg to its receptors, the "degradation complex" is(More)
Force generation and the material properties of cells and tissues are central to morphogenesis but remain difficult to measure in vivo. Insight is often limited to the ratios of mechanical properties obtained through disruptive manipulation, and the appropriate models relating stress and strain are unknown. The Drosophila amnioserosa epithelium(More)