Search results for "Embryon"
showing 10 items of 988 documents
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…
The commonly used marker ELAV is transiently expressed in neuroblasts and glial cells in theDrosophilaembryonic CNS
2007
Glial cells in the Drosophila embryonic nervous system can be monitored with the marker Reversed-polarity (Repo), whereas neurons lack Repo and express the RNA-binding protein ELAV (Embryonic Lethal, Abnormal Vision). Since the first description of the ELAV protein distribution in 1991 (Robinow and White), it is believed that ELAV is an exclusive neuronal and postmitotic marker. Looking at ELAV expression, we unexpectedly observed that, in addition to neurons, ELAV is transiently expressed in embryonic glial cells. Furthermore, it is transiently present in the proliferating longitudinal glioblast, and it is transcribed in embryonic neuroblasts. Likewise, elav-Gal4 lines, which are generally…
Composition of a Neuromere and Its Segmental Diversification under the Control ofHoxGenes in the Embryonic CNS ofDrosophila
2014
Studies performed at the level of single, identified cells in the fruitfly Drosophila have decisively contributed to our understanding of the mechanisms underlying the development and function of the nervous system. This review highlights some of the work based on single-cell analyses in the embryonic/larval CNS that sheds light on the principles underlying formation and organization of an entire segmental unit and its divergence along the anterior/posterior body axis.
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…
The muscleblind gene participates in the organization of Z-bands and epidermal attachments of Drosophila muscles and is regulated by Dmef2.
1998
We report the embryonic phenotype of muscleblind (mbl), a recently described Drosophila gene involved in terminal differentiation of adult ommatidia. mbl is a nuclear protein expressed late in the embryo in pharyngeal, visceral, and somatic muscles, the ventral nerve cord, and the larval photoreceptor system. All three mbl alleles studied exhibit a lethal phenotype and die as stage 17 embryos or first instar larvae. These larvae are partially paralyzed, show a characteristically contracted abdomen, and lack striation of muscles. Our analysis of the somatic musculature shows that the pattern of muscles is established correctly, and they form morphologically normal synapses. Ultrastructural a…
The fate of the CNS midline progenitors in Drosophila as revealed by a new method for single cell labelling
1994
ABSTRACT We present a new method for marking single cells and tracing their development through embryogenesis. Cells are labelled with a lipophilic fluorescent tracer (DiI) in their normal positions without impaling their membranes. The dye does not diffuse between cells but is transferred to the progeny, disclosing their morphology in all detail. Behaviour of labelled cells can be observed in vivo (cell divisions, morphogenetic movements and differentiation). Following photoconversion of the dye, fully differentiated clones can be analyzed in permanent preparations. We apply this method for cell lineage analysis of the embryonic Drosophila CNS. Here we describe the fate of the CNS midline …
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…