Search results for "structures"
showing 10 items of 4815 documents
Impact of Ultrabithorax alternative splicing on Drosophila embryonic nervous system development.
2015
Hox genes control divergent segment identities along the anteroposterior body axis of bilateral animals by regulating a large number of processes in a cell context-specific manner. How Hox proteins achieve this functional diversity is a long-standing question in developmental biology. In this study we investigate the role of alternative splicing in functional specificity of the Drosophila Hox gene Ultrabithorax (Ubx). We focus specifically on the embryonic central nervous system (CNS) and provide a description of temporal expression patterns of three major Ubx isoforms during development of this tissue. These analyses imply distinct functions for individual isoforms in different stages of n…
The Process-inducing Activity of Transmembrane Agrin Requires Follistatin-like Domains
2009
Clustering or overexpression of the transmembrane form of the extracellular matrix proteoglycan agrin in neurons results in the formation of numerous highly motile filopodia-like processes extending from axons and dendrites. Here we show that similar processes can be induced by overexpression of transmembrane-agrin in several non-neuronal cell lines. Mapping of the process-inducing activity in neurons and non-neuronal cells demonstrates that the cytoplasmic part of transmembrane agrin is dispensable and that the extracellular region is necessary for process formation. Site-directed mutagenesis reveals an essential role for the loop between beta-sheets 3 and 4 within the Kazal subdomain of t…
Neuroblast pattern and identity in the Drosophila tail region and role of doublesex in the survival of sex-specific precursors.
2013
The central nervous system is composed of segmental units (neuromeres), the size and complexity of which evolved in correspondence to their functional requirements. In Drosophila, neuromeres develop from populations of neural stem cells (neuroblasts) that delaminate from the early embryonic neuroectoderm in a stereotyped spatial and temporal pattern. Pattern units closely resemble the ground state and are rather invariant in thoracic (T1-T3) and anterior abdominal (A1-A7) segments of the embryonic ventral nerve cord. Here, we provide a comprehensive neuroblast map of the terminal abdominal neuromeres A8-A10, which exhibit a progressively derived character. Compared with thoracic and anterio…
Induction of identified mesodermal cells by CNS midline progenitors in Drosophila.
1997
ABSTRACT The Drosophila ventral midline cells generate a discrete set of CNS lineages, required for proper patterning of the ventral ectoderm. Here we provide the first evidence that the CNS midline cells also exert inductive effects on the mesoderm. Mesodermal progenitors adjacent to the midline progenitor cells give rise to ventral somatic mucles and a pair of unique cells that come to lie dorsomedially on top of the ventral nerve cord, the so-called DM cells. Cell ablation as well as cell transplantation experiments indicate that formation of the DM cells is induced by midline progenitors in the early embryo. These results are corroborated by genetic analyses. Mutant single minded embryo…
A common precursor for glia and neurons in the embryonic CNS of Drosophila gives rise to segment-specific lineage variants
1993
ABSTRACT The nervous system consists of two classes of cells, neurons and glia, which differ in morphology and function. They derive from precursors located in the neurogenic region of the ectoderm. In this study, we present the complete embryonic lineage of a neuroectodermal precursor in Drosophila that gives rise to neurons as well as glia in the abdominal CNS. This lineage is conserved among different Drosophila species. We show that neuronal and glial cell types in this clone derive from one segregating precursor, previously described as NB1-1. Thus, in addition to neuroblasts and glioblasts, there exists a third class of CNS precursors in Drosophila, which we call neuroglioblasts. We f…
Programmed cell death in the embryonic central nervous system of Drosophila melanogaster.
2006
Although programmed cell death (PCD) plays a crucial role throughout Drosophila CNS development, its pattern and incidence remain largely uninvestigated. We provide here a detailed analysis of the occurrence of PCD in the embryonic ventral nerve cord (VNC). We traced the spatio-temporal pattern of PCD and compared the appearance of, and total cell numbers in,thoracic and abdominal neuromeres of wild-type and PCD-deficient H99mutant embryos. Furthermore, we have examined the clonal origin and fate of superfluous cells in H99 mutants by DiI labeling almost all neuroblasts, with special attention to segment-specific differences within the individually identified neuroblast lineages. Our data r…
Abdominal-B and caudal inhibit the formation of specific neuroblasts in the Drosophila tail region
2013
The central nervous system of Drosophila melanogaster consists of fused segmental units (neuromeres), each generated by a characteristic number of neural stem cells (neuroblasts). In the embryo, thoracic and anterior abdominal neuromeres are almost equally sized and formed by repetitive sets of neuroblasts, whereas the terminal abdominal neuromeres are generated by significantly smaller populations of progenitor cells. Here we investigated the role of the Hox gene Abdominal-B in shaping the terminal neuromeres. We show that the regulatory isoform of Abdominal-B (Abd-B.r) not only confers abdominal fate to specific neuroblasts (e.g. NB6-4) and regulates programmed cell death of several proge…
Successive specification ofDrosophilaneuroblasts NB 6-4 and NB 7-3 depends on interaction of the segment polarity geneswingless,gooseberryandnaked cu…
2001
The Drosophila central nervous system derives from neural precursor cells, the neuroblasts (NBs), which are born from the neuroectoderm by the process of delamination. Each NB has a unique identity, which is revealed by the production of a characteristic cell lineage and a specific set of molecular markers it expresses. These NBs delaminate at different but reproducible time points during neurogenesis (S1-S5) and it has been shown for early delaminating NBs (S1/S2) that their identities depend on positional information conferred by segment polarity genes and dorsoventral patterning genes. We have studied mechanisms leading to the fate specification of a set of late delaminating neuroblasts,…
Commitment of CNS Progenitors Along the Dorsoventral Axis of Drosophila Neuroectoderm
1995
In the Drosophila embryo, the central nervous system (CNS) develops from a population of neural stem cells (neuroblasts) and midline progenitor cells. Here, the fate and extent of determination of CNS progenitors along the dorsoventral axis was assayed. Dorsal neuroectodermal cells transplanted into the ventral neuroectoderm or into the midline produced CNS lineages consistent with their new position. However, ventral neuroectodermal cells and midline cells transplanted to dorsal sites of the neuroectoderm migrated ventrally and produced CNS lineages consistent with their origin. Thus, inductive signals at the ventral midline and adjacent neuroectoderm may confer ventral identities to CNS p…
Mice lacking Plexin-B3 display normal CNS morphology and behaviour
2009
Semaphorins and their receptors, plexins, have emerged as important regulators of a multitude of biological processes. Plexin-B3 has been shown to be selectively expressed in postnatal oligodendrocytes. In contrast to the well-characterized Plexin-A family and the Plexin-B family members Plexin-B1 and -B2, no data are available on the functional role of Plexin-B3 in the central nervous system in vivo. Here we have elucidated the functional significance of Plexin-B3 by generating and analyzing constitutive knock-out mice. Plexin-B3-deficient mice were found to be viable and fertile. A systematic histological analysis revealed no morphological defects in the brain or spinal cord of mutant ani…