Initial anteroposterior pattern of the zebrafish central nervous system is determined by differential competence of the epiblast

Development ◽  
1998 ◽  
Vol 125 (10) ◽  
pp. 1957-1966 ◽  
Author(s):  
S. Koshida ◽  
M. Shinya ◽  
T. Mizuno ◽  
A. Kuroiwa ◽  
H. Takeda
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Ectopic Expression ◽  
Neural Tissue ◽  
Ventral Side ◽  
Expression Domain ◽  
Anteroposterior Patterning ◽  
Endogenous Expression ◽  
Neural Marker ◽  
Fgf Signalling

Analyses using amphibian embryos proposed that induction and anteroposterior patterning of the central nervous system is initiated by signals that are produced by the organizer and organizer-derived axial mesoderm. However, we show here that the initial anteroposterior pattern of the zebrafish central nervous system depends on the differential competence of the epiblast and is not imposed by organizer-derived signals. This anteroposterior information is present throughout the epiblast in ectodermal cells that normally give rise both to neural and non-neural derivatives. Because of this information, organizer tissues transplanted to the ventral side of the embryo induce neural tissue but the anteroposterior identity of the induced neural tissue is dependent upon the position of the induced tissue within the epiblast. Thus, otx2, an anterior neural marker, was only ever induced in anterior regions of the embryo, irrespective of the position of the grafts. Similarly, hoxa-1, a posterior neural marker was induced only in the posterior regions. Furthermore, the boundary of each ectopic expression domain on the ventral side was always at an equivalent latitude to that of the endogenous expression of the dorsal side of the embryo. The anteroposterior specification of the epiblast is independent of the dorsoventral specification of the embryo because neural tissues induced in the ventralized embryos also showed anteroposterior polarity. Cell transplantation and RNA injection experiments showed that non-axial marginal mesoderm and FGF signalling is required for anteroposterior specification of the epiblast. However, the requirement for FGF signalling is indirect in that cells with compromised ability to respond to FGF can still respond to anteroposterior positional information.

Patterning the ascidian nervous system: structure, expression and transgenic analysis of the CiHox3 gene

Development ◽  
1999 ◽  
Vol 126 (21) ◽  
pp. 4737-4748 ◽  
Author(s):  
A. Locascio ◽  
F. Aniello ◽  
A. Amoroso ◽  
M. Manzanares ◽  
R. Krumlauf ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Hox Genes ◽  
Regional Identity ◽  
Regulatory Elements ◽  
System Structure ◽  
Anteroposterior Patterning ◽  
Hox Gene ◽  
The Central Nervous System ◽  
Group 3

Hox genes play a fundamental role in the establishment of chordate body plan, especially in the anteroposterior patterning of the nervous system. Particularly interesting are the anterior groups of Hox genes (Hox1-Hox4) since their expression is coupled to the control of regional identity in the anterior regions of the nervous system, where the highest structural diversity is observed. Ascidians, among chordates, are considered a good model to investigate evolution of Hox gene, organisation, regulation and function. We report here the cloning and the expression pattern of CiHox3, a Ciona intestinalis anterior Hox gene homologous to the paralogy group 3 genes. In situ hybridization at the larva stage revealed that CiHox3 expression was restricted to the visceral ganglion of the central nervous system. The presence of a sharp posterior boundary and the absence of transcript in mesodermal tissues are distinctive features of CiHox3 expression when compared to the paralogy group 3 in other chordates. We have investigated the regulatory elements underlying CiHox3 neural-specific expression and, using transgenic analysis, we were able to isolate an 80 bp enhancer responsible of CiHox3 activation in the central nervous system (CNS). A comparative study between mouse and Ciona Hox3 promoters demonstrated that divergent mechanisms are involved in the regulation of these genes in vertebrates and ascidians.

Dorsal-ventral patterning and differentiation of noggin-induced neural tissue in the absence of mesoderm

Development ◽  
1995 ◽  
Vol 121 (6) ◽  
pp. 1927-1935 ◽  
Author(s):  
A.K. Knecht ◽  
P.J. Good ◽  
I.B. Dawid ◽  
R.M. Harland
Keyword(s):  
Nervous System ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Neural Tissue ◽  
Expression Domain ◽  
Xenopus Development ◽  
Dorsal Mesoderm

In Xenopus development, dorsal mesoderm is thought to play a key role in both induction and patterning of the nervous system. Previously, we identified a secreted factor, noggin, which is expressed in dorsal mesoderm and which can mimic that tissue's neural-inducing activity, without inducing mesoderm. Here the neural tissue induced in ectodermal explants by noggin is further characterized using four neural-specific genes: two putative RNA-binding proteins, nrp-1 and etr-1; the synaptobrevin sybII; and the lipocalin cpl-1. First we determine the expression domain of each gene during embryogenesis. Then we analyze expression of these genes in noggin-treated explants. All markers, including the differentiated marker sybII, are expressed in noggin-induced neural tissue. Furthermore, cpl-1, a marker of dorsal brain, and etr-1, a marker absent in much of the dorsal forebrain, are expressed in non-overlapping territories within these explants. We conclude that the despite the absence of mesoderm, noggin-induced neural tissue shows considerable differentiation and organization, which may represent dorsal-ventral patterning of the forebrain.

Ectopic engrailed 1 expression in the dorsal midline causes cell death, abnormal differentiation of circumventricular organs and errors in axonal pathfinding

Development ◽  
2000 ◽  
Vol 127 (18) ◽  
pp. 4061-4071 ◽  
Author(s):  
A. Louvi ◽  
M. Wassef
Keyword(s):  
Cell Death ◽  
Choroid Plexus ◽  
Subcommissural Organ ◽  
Ectopic Expression ◽  
Axonal Pathfinding ◽  
Posterior Commissure ◽  
Expression Domain ◽  
In Ovo ◽  
Dorsal Midline ◽  
Endogenous Expression

A series of gain- or loss-of-function experiments performed in different vertebrate species have demonstrated that the Engrailed genes play multiple roles during brain development. In particular, they have been implicated in the determination of the mid/hindbrain domain, in cell proliferation and survival, in neurite formation, tissue polarization and axonal pathfinding. We have analyzed the consequences of a local gain of En function within or adjacent to the endogenous expression domain in mouse and chick embryos. In WEXPZ.En1 transgenic mice (Danielian, P. S. and McMahon, A. P. (1996) Nature 383, 332–334) several genes are induced as a consequence of ectopic expression of En1 in the diencephalic roof (but in a pattern inconsistent with a local di- to mes-encephalon fate change). The development of several structures with secretory function, generated from the dorsal neuroepithelium, is severely compromised. The choroid plexus, subcommissural organ and pineal gland either fail to form or are atrophic. These defects are preceded by an increase in cell death at the dorsal midline. Comparison with the phenotype of Wnt1(sw/sw) (swaying) mutants suggests that subcommissural organ failure is the main cause of prenatal hydrocephalus observed in both strains. The formation of the posterior commissure is also delayed, and errors in axonal pathfinding are frequent. In chick, ectopic expression of En by in ovo electroporation, affects growth and differentiation of the choroid plexus.

Spatial aspects of neural induction in Xenopus laevis

Development ◽  
1989 ◽  
Vol 107 (4) ◽  
pp. 785-791 ◽  
Author(s):  
E.A. Jones ◽  
H.R. Woodland
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Peripheral Nerves ◽  
Neural Differentiation ◽  
Neural Induction ◽  
Neural Tissue ◽  
Thoracic Region ◽  
Lateral Extent ◽  
Tail Tip ◽  
Developing Nervous System

A monoclonal antibody, 2G9, has been identified and characterised as a marker of neural differentiation in Xenopus. The epitope is present throughout the adult central nervous system and in peripheral nerves. Staining is first detected in embryos at stage 21 in the thoracic region. By stage 29 it stains the whole central nervous system, except the tail tip. The epitope is present in a 65K Mr protein, and includes sialic acid. The antibody also reacts with neural tissue in mice and axolotls and newts. 2G9 was used to show that both notochord and somites are capable of neural induction, and the stimulus is present as late as stage 22. Attempts to demonstrate the induction of nervous system by developing nervous system (homoiogenetic induction) were unsuccessful. The view that the lateral extent of the nervous system might be determined by that of the inductive stimulus is discussed. Neural induction was detected as early as stage 10 and occurs in embryos without gastrulation and without cell division from stage 7 1/2.

Dephrin, a transmembrane ephrin with a unique structure, prevents interneuronal axons from exiting the Drosophila embryonic CNS

Development ◽  
2002 ◽  
Vol 129 (18) ◽  
pp. 4205-4218 ◽  
Author(s):  
Torsten Bossing ◽  
Andrea H. Brand
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Ectopic Expression ◽  
Axonal Pathfinding ◽  
N Terminus ◽  
Outer Border ◽  
Embryonic Cns ◽  
First Time ◽  
Neuronal Compartments

Ephrin/Eph signalling is crucial for axonal pathfinding in vertebrates and invertebrates. We identified the Drosophila ephrin orthologue, Dephrin, and describe for the first time the role of ephrin/Eph signalling in the embryonic central nervous system (CNS). Dephrin is a transmembrane ephrin with a unique N terminus and an ephrinB-like cytoplasmic tail. Dephrin binds and interacts with DEph, the Drosophila Eph-like receptor, and Dephrin and DEph are confined to different neuronal compartments. Loss of Dephrin or DEph causes the abberant exit of interneuronal axons from the CNS, whereas ectopic expression of Dephrin halts axonal growth. We propose that the longitudinal tracts in the Drosophila CNS are moulded by a repulsive outer border of Dephrin expression.

Ectopic expression of either the Drosophila gooseberry-distal or proximal gene causes alterations of cell fate in the epidermis and central nervous system

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1151-1161 ◽  
Author(s):  
Y. Zhang ◽  
A. Ungar ◽  
C. Fresquez ◽  
R. Holmgren
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cell Fate ◽  
Ectopic Expression ◽  
Cell Fate Specification ◽  
Single Function ◽  
Independent Functions ◽  
Segment Polarity ◽  
The Central Nervous System ◽  
The Common

Previous studies have shown that the segment polarity locus gooseberry, which contains two closely related transcripts gooseberry-proximal and gooseberry-distal, is required for proper development in both the epidermis and the central nervous system of Drosophila. In this study, the roles of the gooseberry proteins in the process of cell fate specification have been examined by generating two fly lines in which either gooseberry-distal or gooseberry-proximal expression is under the control of an hsp70 promoter. We have found that ectopic expression of either gooseberry protein causes cell fate transformations that are reciprocal to those of a gooseberry deletion mutant. Our results suggest that the gooseberry-distal protein is required for the specification of naked cuticle in the epidermis and specific neuroblasts in the central nervous system. These roles may reflect independent functions in neuroblasts and epidermal cells or a single function in the common ectodermal precursor cells. The gooseberry-proximal protein is also found in the same neuroblasts as gooseberry-distal and in the descendants of these cells.

Induction of the mesendoderm in the zebrafish germ ring by yolk cell-derived TGF-beta family signals and discrimination of mesoderm and endoderm by FGF

Development ◽  
1999 ◽  
Vol 126 (14) ◽  
pp. 3067-3078 ◽  
Author(s):  
A. Rodaway ◽  
H. Takeda ◽  
S. Koshida ◽  
J. Broadbent ◽  
B. Price ◽  
...  
Keyword(s):  
Ectopic Expression ◽  
Dominant Negative ◽  
Fibroblast Growth ◽  
Tgf Beta ◽  
Fgf Receptor ◽  
Activin Receptor ◽  
Yolk Cell ◽  
Endogenous Expression ◽  
Vertebrate Embryo ◽  
Fgf Signalling

The endoderm forms the gut and associated organs, and develops from a layer of cells which emerges during gastrula stages in the vertebrate embryo. In comparison to mesoderm and ectoderm, little is known about the signals which induce the endoderm. The origin of the endoderm is intimately linked with that of mesoderm, both by their position in the embryo, and by the molecules that can induce them. We characterised a gene, zebrafish gata5, which is expressed in the endoderm from blastula stages and show that its transcription is induced by signals originating from the yolk cell. These signals also induce the mesoderm-expressed transcription factor no tail (ntl), whose initial expression coincides with gata5 in the cells closest to the blastoderm margin, then spreads to encompass the germ ring. We have characterised the induction of these genes and show that ectopic expression of activin induces gata5 and ntl in a pattern which mimics the endogenous expression, while expression of a dominant negative activin receptor abolishes ntl and gata5 expression. Injection of RNA encoding a constitutively active activin receptor leads to ectopic expression of gata5 and ntl. gata5 is activated cell-autonomously, whereas ntl is induced in cells distant from those which have received the RNA, showing that although expression of both genes is induced by a TGF-beta signal, expression of ntl then spreads by a relay mechanism. Expression of a fibroblast growth factor (eFGF) or a dominant negatively acting FGF receptor shows that ntl but not gata5 is regulated by FGF signalling, implying that this may be the relay signal leading to the spread of ntl expression. In embryos lacking both squint and cyclops, members of the nodal group of TGF-beta related molecules, gata5 expression in the blastoderm is abolished, making these factors primary candidates for the endogenous TGF-beta signal inducing gata5.

scholarly journals Drosophila Zic family member odd-paired is needed for adult post-ecdysis maturation

Open Biology ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 190245
Author(s):  
Eléanor Simon ◽  
Sergio Fernández de la Puebla ◽  
Isabel Guerrero
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Transcription Factor ◽  
Drosophila Melanogaster ◽  
Family Member ◽  
Ectopic Expression ◽  
Functional Conservation ◽  
The Central Nervous System ◽  
Behavioural Sequence

Specific neuropeptides regulate in arthropods the shedding of the old cuticle (ecdysis) followed by maturation of the new cuticle. In Drosophila melanogaster , the last ecdysis occurs at eclosion from the pupal case, with a post-eclosion behavioural sequence that leads to wing extension, cuticle stretching and tanning. These events are highly stereotyped and are controlled by a subset of crustacean cardioactive peptide (CCAP) neurons through the expression of the neuropeptide Bursicon (Burs). We have studied the role of the transcription factor Odd-paired (Opa) during the post-eclosion period. We report that opa is expressed in the CCAP neurons of the central nervous system during various steps of the ecdysis process and in peripheral CCAP neurons innerving the larval muscles involved in adult ecdysis. We show that its downregulation alters Burs expression in the CCAP neurons. Ectopic expression of Opa, or the vertebrate homologue Zic2 , in the CCAP neurons also affects Burs expression, indicating an evolutionary functional conservation. Finally, our results show that, independently of its role in Burs regulation, Opa prevents death of CCAP neurons during larval development.

scholarly journals COVID-19 and Neurological Manifestations

2020 ◽  
Vol 56 (03) ◽  
pp. 177-182
Author(s):  
Neeraj Balaini ◽  
Manish Modi
Keyword(s):  
Central Nervous System ◽  
Cerebrospinal Fluid ◽  
Nervous System ◽  
Neurological Diseases ◽  
Neural Tissue ◽  
Retrograde Transport ◽  
Shortness Of Breath ◽  
Neurological Manifestations ◽  
Virus Rna ◽  
Viral Illness

AbstractCoronavirus disease 2019 (COVID-19) is a viral illness caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) which has taken the form of a pandemic. It mainly presents as fever, cough, shortness of breath involving respiratory system but neurological manifestations are increasingly being recognized worldwide and even virus RNA was demonstrated to be present in cerebrospinal fluid of a patient. SARS-CoV-2 involves both central nervous system and peripheral nervous system. Virus can enter the neural tissue from hematological route or through retrograde transport from nerve endings. Physicians especially neurologists should be aware regarding neurological manifestations as patient can present with these conditions in emergency. We therefore reviewed the neurological diseases or complications associated with COIVID-19 in available literature.

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