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Mesodermal Tissues (mesodermal + tissue)
Selected AbstractsFine structure of neuronal and glial processes in neuropathologyNEUROPATHOLOGY, Issue 1 2006Asao Hirano The cells of the nervous system are characterized by their well-formed cell processes and by cell-to-cell relationships that they form. The neuron reveals essentially cylindrical processes, which form synaptic junctions. On the other hand, the peripheral parts of the glial cells are mainly sheet-like in nature. Thus, the oligodendroglial cell elaborates many sheet-like processes, each of which forms a segment of the myelin sheath. Unique cell junction, transverse bands are present at the interface of oligodendroglial processes and the axon. Finally, the astrocytes also form elaborate sheet-like processes, which separate most of the CNS from the mesodermal tissue as well as surrounding certain neuronal surfaces, including synapses. Punctate adhesions, gap junctions and other adhesive devices are present between astrocytic processes. Defects or anomalies in the neuronal and glial cell processes characterize numerous pathological conditions. [source] Neuro-mesodermal patterns in artificially deformed embryonic explants: A role for mechano-geometry in tissue differentiationDEVELOPMENTAL DYNAMICS, Issue 3 2010E.S. Kornikova Abstract The mutual arrangement of neural and mesodermal rudiments in artificially bent double explants of Xenopus laevis suprablastoporal areas was compared with that of intact explants. While some of the bent explants straightened or became spherical, most retained and actively reinforced the imposed curvature, creating folds on their concave sides and expanding convex surfaces. In the intact explants, the arrangement of neural and mesodermal rudiments exhibited a distinct antero-posterior polarity, with some variability. In the bent explants, this polarity was lost: the neural rudiments were shifted towards concave while the mesodermal tissues moved towards the convex side, embracing the neural rudiments in a horseshoe-shaped manner. We associate these drastic changes in neuro-mesodermal patterning with the active extension and contraction of the convex and concave sides, respectively, triggered by the imposed deformations. We speculate that similar events are responsible for the establishment of neuro-mesodermal patterns during normal development. Developmental Dynamics 239:885,896, 2010. © 2010 Wiley-Liss, Inc. [source] Analysis of regulatory elements of E-cadherin with reporter gene constructs in transgenic mouse embryosDEVELOPMENTAL DYNAMICS, Issue 2 2003Marc P. Stemmler Abstract Proper regulation of E-cadherin,mediated cell adhesion is important during early embryonic development and in organogenesis. In mice, E-cadherin is expressed from the fertilized egg onward and becomes down-regulated during gastrulation in mesoderm and its derivatives, but its expression is maintained in all epithelia. E-cadherin promoter analyses led to the identification of binding sites for two transcriptional repressors, Snail and SIP1, which are able to mediate down-regulation in vitro, but little is known about the regulatory elements that govern E-cadherin transcriptional activity in vivo. Here, we compared the developmentally regulated expression of a series of lacZ -reporter transgenes fused to different sequences of the murine E-cadherin gene between ,6 kb, including the promoter, and +16 kb, covering one third of intron 2. Four different segments with distinct regulatory properties were identified. The promoter fragment from +0.1 to ,1.5 kb remains inactive in most cases but occasionally induces ectopic expression in mesodermal tissues, although it contains binding sites for the repressors Snail and SIP1. This promoter fragment also lacks positive elements needed for the activation of transcription in ectoderm and endoderm. Sequences from ,1.5 to ,6 kb harbor regulatory elements for brain-specific expression and, in addition, insulator or silencer elements, because they are consistently inactive in the mesoderm. Only if sequences from +0.1 to +11 kb are combined with the promoter fragments is E-cadherin,specific transgene expression observed in endoderm and certain epithelia. Sequences between +11 and +16 kb contain cis -active elements that generally enhance transcription. Our analyses show that E-cadherin expression is governed by a complex interplay of multiple regulatory regions dispersed throughout large parts of the locus. Developmental Dynamics 227:238,245, 2003. © 2003 Wiley-Liss, Inc. [source] Transgenic Drosophila reveals a functional in vivo receptor for the Bacillus thuringiensis toxin Cry1Ac1INSECT MOLECULAR BIOLOGY, Issue 6 2002Michael Gill Abstract The bacterium Bacillus thuringiensis synthesizes toxins (,-endotoxins) that are highly specific for insects. Once ingested, the activated form of the toxin binds to a specific receptor(s) located on the midgut epithelial cells, inserts into the membrane causing the formation of leakage pores and eventual death of the susceptible insect larvae. Manduca sexta larvae are highly susceptible to Cry1Ac1, a toxin that is believed to bind M. sexta Aminopeptidase N, a glycoprotein located on the apical membrane. However, the binding data obtained to date only support the interaction of Cry1Ac1 with APN in vitro. To explore the in vivo role of APN, we have utilized the GAL4 enhancer trap technique to drive the expression of M. sexta APN in both midgut and mesodermal tissues of Cry1Ac1 insensitive Drosophila larvae. Transgenic Drosophila fed the toxin were now killed, demonstrating that APN can function as a receptor for Cry1Ac1 in vivo. [source] Comparative analysis of neuroectodermal differentiation capacity of human bone marrow stromal cells using various conversion protocolsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Andreas Hermann Abstract Human adult bone marrow-derived mesodermal stromal cells (hMSCs) are able to differentiate into multiple mesodermal tissues, including bone and cartilage. There is evidence that these cells are able to break germ layer commitment and differentiate into cells expressing neuroectodermal properties. There is still debate about whether this results from cell fusion, aberrant marker gene expression or real neuroectodermal differentiation. Here we extend our work on neuroectodermal conversion of adult hMSCs in vitro by evaluating various epigenetic conversion protocols using quantitative RT-PCR and immunocytochemistry. Undifferentiated hMSCs expressed high levels of fibronectin as well as several neuroectodermal genes commonly used to characterize neural cell types, such as nestin, ,-tubulin III, and GFAP, suggesting that hMSCs retain the ability to differentiate into neuroectodermal cell types. Protocols using a direct differentiation of hMSCs into a neural phenotype failed to induce significant changes in morphology and/or expression of markers of early and mature glial/neuronal cells types. In contrast, a multistep protocol with conversion of hMSCs into a neural stem cell-like population and subsequent terminal differentiation in mature glia and neurons generated relevant morphological changes as well as significant increase of expression levels of marker genes for early and late neural cell types, such as nestin, neurogenin2, MBP, and MAP2ab, accompanied by a loss of their mesenchymal properties. Our data provide an impetus for differentiating hMSCs in vitro into mature neuroectodermal cells. Neuroectodermally converted hMSCs may therefore ultimately help in treating acute and chronic neurodegenerative diseases. Analysis of marker gene expression for characterization of neural cells derived from MSCs has to take into account that several early and late neuroectodermal genes are already expressed in undifferentiated MSCs. © 2006 Wiley-Liss, Inc. [source] | ||||||||||