Search results for "Mali"
showing 10 items of 3900 documents
TGF-β superfamily signaling is essential for tooth and hair morphogenesis and differentiation
2007
Members of the transforming growth factor beta (TGF-beta) superfamily of signaling molecules are involved in the regulation of many developmental processes that involve the interaction between mesenchymal and epithelial tissues. Smad7 is a potent inhibitor of many members of the TGF-beta family, notably TGF-beta and activin. In this study, we show that embryonic overexpression of Smad7 in stratified epithelia using a keratin 5 promoter, results in severe morphogenetic defects in skin and teeth and leads to embryonic and perinatal lethality. To further analyze the functions of Smad7 in epithelial tissues of adult mice, we used an expression system that allowed a controlled overexpression of …
Derivation of clinical-grade human embryonic stem cells.
2006
Embryonic stem cells proliferate in vitro while maintaining an undifferentiated state, and are capable of differentiating into most cell types under appropriate conditions. These properties imply great potential in the treatment of various diseases and disabilities. In fact, the first clinical trials with hESC for treating spinal cord injuries will begin next year. However, therapeutic application of human embryonic stem cell derivatives is compromised by the exposure of existing lines to animal and human components, with the subsequent risk of contamination with retroviruses and other pathogens, which can be transmitted to patients. The scientific community is striving to avoid the use of …
Double In Utero Electroporation to Target Temporally and Spatially Separated Cell Populations.
2020
In utero electroporation is an in vivo DNA transfer technique extensively used to study the molecular and cellular mechanisms underlying mammalian corticogenesis. This procedure takes advantage of the brain ventricles to allow the introduction of DNA of interest and uses a pair of electrodes to direct the entrance of the genetic material into the cells lining the ventricle, the neural stem cells. This method allows researchers to label the desired cells and/or manipulate the expression of genes of interest in those cells. It has multiple applications, including assays targeting neuronal migration, lineage tracing, and axonal pathfinding. An important feature of this method is its temporal a…
Histopathology and Classification of Renal Cell Tumors (Adenomas, Oncocytomas and Carcinomas)
1986
The term renal cell tumors (adenomas and carcinomas) subsumes the tumors deriving from the uriniferous tubule epithelium of the kidney. Precise analysis shows that the renal cell tumors display different cell types which build up the individual tumor alone or in combination with each other. Three categories of basic elements are distinguished in the characterization of renal cell tumors: Cytological elements = tumor cell types: Clear, chromophobe, chromophilic (basophilic, eosinophilic), oncocytic, spindle-shaped/pleomorphic. Histological elements = growth patterns: Compact, acinar (nest-like), tubulopapillary (tubular, papillary), cystic. Cytological grading of malignancy: G I, G II, G III…
Comm Sorts Robo to Control Axon Guidance at the Drosophila Midline
2002
AbstractAxon growth across the Drosophila midline requires Comm to downregulate Robo, the receptor for the midline repellent Slit. We show here that comm is required in neurons, not in midline cells as previously thought, and that it is expressed specifically and transiently in commissural neurons. Comm acts as a sorting receptor for Robo, diverting it from the synthetic to the late endocytic pathway. A conserved cytoplasmic LPSY motif is required for endosomal sorting of Comm in vitro and for Comm to downregulate Robo and promote midline crossing in vivo. Axon traffic at the CNS midline is thus controlled by the intracellular trafficking of the Robo guidance receptor, which in turn depends…
Compartmentalization of Central Neurons inDrosophila: A New Strategy of Mosaic Analysis Reveals Localization of Presynaptic Sites to Specific Segment…
2002
Synaptogenesis in the CNS has received far less attention than the development of neuromuscular synapses, although only central synapses allow the study of neuronal postsynaptic mechanisms and display a greater variety of structural and functional features. This neglect is attributable mainly to the enormous complexity of the CNS, which makes the visualization of individual synapses on defined neuronal processes very difficult. We overcome this obstacle and demonstrate by confocal microscopy the specific arrangement of output synapses on individual neurites. These studies are performed via genetic mosaic strategies in the CNS of the fruitfly Drosophila melanogaster. First, we use targeted e…
Charting the Drosophila neuropile: a strategy for the standardised characterisation of genetically amenable neurites
2003
Insect neurons are individually identifiable and have been used successfully to study principles of the formation and function of neuronal circuits. In the fruitfly Drosophila, studies on identifiable neurons can be combined with efficient genetic approaches. However, to capitalise on this potential for studies of circuit formation in the CNS of Drosophila embryos or larvae, we need to identify pre- and postsynaptic elements of such circuits and describe the neuropilar territories they occupy. Here, we present a strategy for neurite mapping, using a set of evenly distributed landmarks labelled by commercially available anti-Fasciclin2 antibodies which remain comparatively constant between s…
Spatio-temporal pattern of cells expressing the clock genes period and timeless and the lineages of period expressing neurons in the embryonic CNS of…
2010
The initial steps towards the generation of cell diversity in the central nervous system of the fruitfly Drosophila melanogaster take place during early phases of embryonic development when a stereotypic population of neural progenitor cells (neuroblasts and midline precursors) is formed in a precise spatial and temporal pattern, and subsequently expresses a particular sequence of genes. The clarification of the positional, temporal and molecular features of the individual progenitor cells in the nerve cord and brain as well as of their specific types of neuronal and/or glial progeny cells forms an essential basis to understand the mechanisms controlling their development. The present study…
Tenectin, a novel extracellular matrix protein expressed during Drosophila melanogaster embryonic development
2006
1567-133X (Print) Journal Article Research Support, Non-U.S. Gov't; During Drosophila embryonic development, various morphogenetic processes require the remodeling of the extracellular matrix. In a previous study, we have identified and characterized a cDNA encoding a novel putative extracellular matrix protein named tenebrin, in the beetle Tenebrio molitor. Here, we examine the expression of the Drosophila ortholog, referred to as Tenectin (Tnc), during embryonic development. Tnc is expressed in the majority of tissues of neuroectodermic origin such as hindgut, foregut, tracheal system, anal plate, and CNS. In the CNS, the Tnc transcript is restricted to a few cells, whereas the protein is…
Analysis of Drosophila salivary gland, epidermis and CNS development suggests an additional function of brinker in anterior-posterior cell fate speci…
2000
Salivary glands are simple structured organs which can serve as a model system in the study of organogenesis. Following a large EMS mutagenesis we have identified a number of genes required for normal salivary gland development. Mutations in the locus small salivary glands-1 (ssg-1) lead to a drastic reduction in the size of the salivary glands. The gene ssg-1 was cloned and subsequent sequence and genetic analysis showed identity to the recently published gene brinker. The salivary gland placode in brinker mutants appears reduced along both the anterior-posterior and dorso-ventral axis. Analysis of the brinker cuticle phenotype revealed a similar loss of anterior-posterior as well as later…