Faculty Opinions recommendation of The zebrafish T-box genes no tail and spadetail are required for development of trunk and tail mesoderm and medial floor plate.

2002 ◽  
Author(s):  
David Kimelman
Keyword(s):  
Floor Plate ◽  
T Box ◽  
No Tail

The zebrafish T-box genesno tailandspadetailare required for development of trunk and tail mesoderm and medial floor plate

Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3311-3323 ◽  
Author(s):  
Sharon L. Amacher ◽  
Bruce W. Draper ◽  
Brian R. Summers ◽  
Charles B. Kimmel
Keyword(s):  
Embryonic Development ◽  
Neural Tube ◽  
Transcriptional Regulators ◽  
Floor Plate ◽  
Wild Type ◽  
T Box ◽  
No Tail ◽  
Ventral Neural Tube ◽  
Plate Formation ◽  
In Cells

T-box genes encode transcriptional regulators that control many aspects of embryonic development. Here, we demonstrate that the mesodermally expressed zebrafish spadetail (spt)/VegT and no tail (ntl)/Brachyury T-box genes are semi-redundantly and cell-autonomously required for formation of all trunk and tail mesoderm. Despite the lack of posterior mesoderm in spt–;ntl– embryos, dorsal-ventral neural tube patterning is relatively normal, with the notable exception that posterior medial floor plate is completely absent. This contrasts sharply with observations in single mutants, as mutations singly in ntl or spt enhance posterior medial floor plate development. We find that ntl function is required to repress medial floor plate and promote notochord fate in cells of the wild-type notochord domain and that spt and ntl together are required non cell-autonomously for medial floor plate formation, suggesting that an inducing signal present in wild-type mesoderm is lacking in spt–;ntl– embryos.

Intronic enhancers control expression of zebrafish sonic hedgehog in floor plate and notochord

Development ◽  
1999 ◽  
Vol 126 (10) ◽  
pp. 2103-2116 ◽  
Author(s):  
F. Muller ◽  
B. Chang ◽  
S. Albert ◽  
N. Fischer ◽  
L. Tora ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Sonic Hedgehog ◽  
Screening Strategy ◽  
Floor Plate ◽  
T Box ◽  
Important Region ◽  
Signalling Molecule ◽  
Intron 1 ◽  
Wide Range ◽  
Enhancer Sequences

The signalling molecule Sonic hedgehog (Shh) controls a wide range of differentiation processes during vertebrate development. Numerous studies have suggested that the absolute levels as well as correct spatial and temporal expression of shh are critical for its function. To investigate the regulation of shh expression, we have studied the mechanism controlling its spatial expression in the zebrafish. We employed an enhancer screening strategy in zebrafish embryos based on co-injection of putative enhancer sequences with a reporter construct and analysis of mosaic expression in accumulated expression maps. Enhancers were identified in intron 1 and 2 that mediate floor plate and notochord expression. These enhancers also drive notochord and floor plate expression in the mouse embryo strongly suggesting that the mechanisms controlling shh expression in the midline are conserved between zebrafish and mouse. Functional analysis in the zebrafish embryo revealed that the intronic enhancers have a complex organisation. Two activator regions, ar-A and ar-C, were identified in intron 1 and 2, respectively, which mediate mostly notochord and floor plate expression. In contrast, another activating region, ar-B, in intron 1 drives expression in the floor plate. Deletion fine mapping of ar-C delineated three regions of 40 bp to be essential for activity. These regions do not contain binding sites for HNF3beta, the winged helix transcription factor previously implicated in the regulation of shh expression, indicating the presence of novel regulatory mechanisms. A T-box transcription factor-binding site was found in a functionally important region that forms specific complexes with protein extracts from wild-type but not from notochord-deficient mutant embryos.

scholarly journals Activator-to-Repressor Conversion of T-Box Transcription Factors by the Ripply Family of Groucho/TLE-Associated Mediators

2008 ◽  
Vol 28 (10) ◽  
pp. 3236-3244 ◽  
Author(s):  
Akinori Kawamura ◽  
Sumito Koshida ◽  
Shinji Takada
Keyword(s):  
Transcription Factors ◽  
Transcriptional Activation ◽  
Cultured Cells ◽  
Biological Significance ◽  
Zebrafish Embryos ◽  
Mutant Form ◽  
Dna Binding Domain ◽  
T Box ◽  
No Tail ◽  
Posterior Trunk

ABSTRACT The T-box family of transcription factors, defined by a conserved DNA binding domain called the T-box, regulate various aspects of embryogenesis by activating and/or repressing downstream genes. In spite of the biological significance of the T-box proteins, how they regulate transcription remains to be elucidated. Here we show that the Groucho/TLE-associated protein Ripply converts T-box proteins from activators to repressors. In cultured cells, zebrafish Ripply1, an essential component in somite segmentation, and its structural relatives, Ripply2 and -3, suppress the transcriptional activation mediated by the T-box protein Tbx24, which is coexpressed with ripply1 during segmentation. Ripply1 associates with Tbx24 and converts it to a repressor. Ripply1 also antagonizes the transcriptional activation of another T-box protein, No tail (Ntl), the zebrafish ortholog of Brachyury. Furthermore, injection of a high dosage of ripply1 mRNA into zebrafish eggs causes defective development of the posterior trunk, similar to the phenotype observed in homozygous mutants of ntl. A mutant form of Ripply1 defective in association with Tbx24 also lacks activity in zebrafish embryos. These results indicate that the intrinsic transcriptional property of T-box proteins is controlled by Ripply family proteins, which act as specific adaptors that recruit the global corepressor Groucho/TLE to T-box proteins.

scholarly journals Optochemical Dissection of T-box Gene-Dependent Medial Floor Plate Development

2015 ◽  
Vol 10 (6) ◽  
pp. 1466-1475 ◽  
Author(s):  
Alexander Y. Payumo ◽  
Whitney J. Walker ◽  
Lindsey E. McQuade ◽  
Sayumi Yamazoe ◽  
James K. Chen
Keyword(s):  
Floor Plate ◽  
T Box

scholarly journals The one-eyed pinhead gene functions in mesoderm and endoderm formation in zebrafish and interacts with no tail

Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 327-342 ◽  
Author(s):  
A.F. Schier ◽  
S.C. Neuhauss ◽  
K.A. Helde ◽  
W.S. Talbot ◽  
W. Driever
Keyword(s):  
Lithium Treatment ◽  
Floor Plate ◽  
Wild Type ◽  
Cell Fates ◽  
No Tail ◽  
Mesoderm Formation ◽  
Prechordal Plate ◽  
The One ◽  
Brain Patterning ◽  
Anterior Posterior

The zebrafish locus one-eyed pinhead (oep) is essential for the formation of anterior axial mesoderm, endoderm and ventral neuroectoderm. At the beginning of gastrulation anterior axial mesoderm cells form the prechordal plate and express goosecoid (gsc) in wild-type embryos. In oep mutants the prechordal plate does not form and gsc expression is not maintained. Exposure to lithium, a dorsalizing agent, leads to the ectopic induction and maintenance of gsc expression in wild-type embryos. Lithium treatment of oep mutants still leads to ectopic gsc induction but not maintenance, suggesting that oep acts downstream of inducers of dorsal mesoderm. In genetic mosaics, wild-type cells are capable of forming anterior axial mesoderm in oep embryos, suggesting that oep is required in prospective anterior axial mesoderm cells before gastrulation. The oep gene is also essential for endoderm formation and the early development of ventral neuroectoderm, including the floor plate. The loss of endoderm is already manifest during gastrulation by the absence of axial-expressing cells in the hypoblast of oep mutants. These findings suggest that oep is also required in lateral and ventral regions of the gastrula margin. The sonic hedgehog (shh).gene is expressed in the notochord of oep animals. Therefore, the impaired floor plate development in oep mutants is not caused by the absence of the floor plate inducer shh. This suggests that oep is required downstream or in parallel to shh signaling. The ventral region of the forebrain is also absent in oep mutants, leading to severe cyclopia. In contrast, anterior-posterior brain patterning appears largely unaffected, suggesting that underlying prechordal plate is not required for anterior-posterior pattern formation but might be involved in dorsoventral brain patterning. To test if oep has a wider, partially redundant role, we constructed double mutants with two other zebrafish loci essential for patterning during gastrulation. Double mutants with floating head, the zebrafish Xnot homologue, display enhanced floor plate and adaxial muscle phenotypes. Double mutants with no tail (ntl), the zebrafish homologue of the mouse Brachyury locus, display severe defects in midline and mesoderm formation including absence of most of the somitic mesoderm. These results reveal a redundant function of oep and ntl in mesoderm formation. Our data suggest that both oep and ntl act in the blastoderm margin to specify mesendodermal cell fates.

Defining subregions of Hensen's node essential for caudalward movement, midline development and cell survival

Development ◽  
1999 ◽  
Vol 126 (21) ◽  
pp. 4771-4783 ◽  
Author(s):  
J.B. Charrier ◽  
M.A. Teillet ◽  
F. Lapointe ◽  
N.M. Le Douarin
Keyword(s):  
Primitive Streak ◽  
Floor Plate ◽  
Paraxial Mesoderm ◽  
Avian Embryo ◽  
Tail Bud ◽  
Anterior Portion ◽  
T Box ◽  
Endodermal Cells ◽  
Further Development ◽  
Midline Development

Hensen's node, also called the chordoneural hinge in the tail bud, is a group of cells that constitutes the organizer of the avian embryo and that expresses the gene HNF-3(β). During gastrulation and neurulation, it undergoes a rostral-to-caudal movement as the embryo elongates. Labeling of Hensen's node by the quail-chick chimera system has shown that, while moving caudally, Hensen's node leaves in its wake not only the notochord but also the floor plate and a longitudinal strand of dorsal endodermal cells. In this work, we demonstrate that the node can be divided into functionally distinct subregions. Caudalward migration of the node depends on the presence of the most posterior region, which is closely apposed to the anterior portion of the primitive streak as defined by expression of the T-box gene Ch-Tbx6L. We call this region the axial-paraxial hinge because it corresponds to the junction of the presumptive midline axial structures (notochord and floor plate) and the paraxial mesoderm. We propose that the axial-paraxial hinge is the equivalent of the neuroenteric canal of other vertebrates such as Xenopus. Blocking the caudal movement of Hensen's node at the 5- to 6-somite stage by removing the axial-paraxial hinge deprives the embryo of midline structures caudal to the brachial level, but does not prevent formation of the neural tube and mesoderm located posteriorly. However, the whole embryonic region generated posterior to the level of Hensen's node arrest undergoes widespread apoptosis within the next 24 hours. Hensen's node-derived structures (notochord and floor plate) thus appear to produce maintenance factor(s) that ensures the survival and further development of adjacent tissues.

Molecular identification of spadetail: regulation of zebrafish trunk and tail mesoderm formation by T-box genes

Development ◽  
1998 ◽  
Vol 125 (17) ◽  
pp. 3379-3388 ◽  
Author(s):  
K.J. Griffin ◽  
S.L. Amacher ◽  
C.B. Kimmel ◽  
D. Kimelman
Keyword(s):  
Transcription Factor ◽  
Genetic Model ◽  
Zebrafish Embryos ◽  
Fibroblast Growth ◽  
Fgf Signaling ◽  
T Box ◽  
Tail Development ◽  
No Tail ◽  
Mesoderm Formation ◽  
Complementary Actions

Inhibition of fibroblast growth factor (FGF) signaling prevents trunk and tail formation in Xenopus and zebrafish embryos. While the T-box transcription factor Brachyury (called No Tail in zebrafish) is a key mediator of FGF signaling in the notochord and tail, the pathways activated by FGF in non-notochordal trunk mesoderm have been uncertain. Previous studies have shown that the spadetail gene is required for non-notochordal trunk mesoderm formation; spadetail mutant embryos have major trunk mesoderm deficiencies, but relatively normal tail and notochord development. We demonstrate here that spadetail encodes a T-box transcription factor with homologues in Xenopus and chick. Spadetail is likely to be a key mediator of FGF signaling in trunk non-notochordal mesoderm, since spadetail expression is regulated by FGF signaling. Trunk and tail development are therefore dependent upon the complementary actions of two T-box genes, spadetail and no tail. We show that the regulatory hierarchy among spadetail, no tail and a third T-box gene, tbx6, are substantially different during trunk and tail mesoderm formation, and propose a genetic model that accounts for the regional phenotypes of spadetail and no tail mutants.

Induction of muscle pioneers and floor plate is distinguished by the zebrafish no tail mutation

Cell ◽  
1993 ◽  
Vol 75 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Marnie E. Halpern ◽  
Robert K. Ho ◽  
Charline Walker ◽  
Charles B. Kimmel
Keyword(s):  
Floor Plate ◽  
No Tail

Table Substitution Box Method for Increasing Security in Interval Splitting Arithmetic Coding

2017 ◽  
Vol 13 (10) ◽  
pp. 6552-6557
Author(s):  
E.Wiselin Kiruba ◽  
Ramar K.
Keyword(s):  
Compression Ratio ◽  
Arithmetic Coding ◽  
Substitution Box ◽  
Plain Text ◽  
T Box ◽  
Novel Approach ◽  
Permutation Methods ◽  
Message Digest ◽  
Box Method ◽  
Arithmetic Coder

Amalgamation of compression and security is indispensable in the field of multimedia applications. A novel approach to enhance security with compression is discussed in this  research paper. In secure arithmetic coder (SAC), security is provided by input and output permutation methods and compression is done by interval splitting arithmetic coding. Permutation in SAC is susceptible to attacks. Encryption issues associated with SAC is dealt in this research method. The aim of this proposed method is to encrypt the data first by Table Substitution Box (T-box) and then to compress by Interval Splitting Arithmetic Coder (ISAC). This method incorporates dynamic T-box in order to provide better security. T-box is a method, constituting elements based on the random output of Pseudo Random Generator (PRNG), which gets the input from Secure Hash Algorithm-256 (SHA-256) message digest. The current scheme is created, based on the key, which is known to the encoder and decoder. Further, T-boxes are created by using the previous message digest as a key.  Existing interval splitting arithmetic coding of SAC is applied for compression of text data. Interval splitting finds a relative position to split the intervals and this in turn brings out compression. The result divulges that permutation replaced by T-box method provides enhanced security than SAC. Data is not revealed when permutation is replaced by T-box method. Security exploration reveals that the data remains secure to cipher text attacks, known plain text attacks and chosen plain text attacks. This approach results in increased security to Interval ISAC. Additionally the compression ratio  is compared by transferring the outcome of T-box  to traditional  arithmetic coding. The comparison proved that there is a minor reduction in compression ratio in ISAC than arithmetic coding. However the security provided by ISAC overcomes the issues of compression ratio in  arithmetic coding. 

Sign in / Sign up

Export Citation Format

Share Document