Muscle gene activation in Xenopus requires intercellular communication during gastrula as well as blastula stages

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 137-142 ◽  
Author(s):  
J. B. Gurdon ◽  
K. Kao ◽  
K. Kato ◽  
N. D. Hopwood
Keyword(s):  
Protein Synthesis ◽  
Developmental Stage ◽  
Cell Transplantation ◽  
Intercellular Communication ◽  
Gene Activation ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Morphological Marker ◽  
Muscle Gene ◽  
Early Gastrula

In Xenopus an early morphological marker of mesodermal induction is the elongation of the mesoderm at the early gastrula stage (Symes and Smith, 1987). We show here that the elongation of equatorial (marginal) tissue is dependent on protein synthesis in a mid blastula, but has become independent of it by the late blastula stage. In animal caps induced to become mesoderm, the time when protein synthesis is required for subsequent elongation immediately follows the time of induction, and is not related to developmental stage. For elongation, intercellular communication during the blastula stage is of primary importance. Current experiments involving cell transplantation indicate a need for further celhcell interactions during gastrulation, and therefore after the vegetal-animal induction during blastula stages. These secondary cell interactions are believed to take place among cells that have already received a vegetal induction, and may facilitate some of the later intracellular events known to accompany muscle gene activation.

Uptake of dissolved amino acids by embryos and larvae of Dendraster excentricus (Eschscholtz) (Echinodermata: Echinoidea)

1983 ◽  
Vol 61 (2) ◽  
pp. 349-354 ◽  
Author(s):  
Marueen E. de Burgh ◽  
Robert D. Burke
Keyword(s):  
Amino Acids ◽  
Liquid Scintillation ◽  
Linear Increase ◽  
Scintillation Counting ◽  
Acid Transport ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Dendraster Excentricus ◽  
Development State ◽  
Early Gastrula

The uptake of 14C- and 3H-labelled mixed amino acids by embryos and larvae of Dendraster excentricus (Eschscholtz) was investigated using liquid scintillation counting and autoradiography. Peaks in transport were observed immediately after fertilization, at the mesenchyme blastula stage, and at the early gastrula stage. The subsequent linear increase in amino acid transport correlated with increase in surface area of the growing pluteus. Autoradiographs showed that in all stages epidermis accumulated 3H label more than internal tissues. It was concluded that uptake rate of dissolved amino acids is dependent upon the size and development state of the embryo and independent of the requirement of the larva to feed.

Expression of a novel FGF in the Xenopus embryo. A new candidate inducing factor for mesoderm formation and anteroposterior specification

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 711-720 ◽  
Author(s):  
H.V. Isaacs ◽  
D. Tannahill ◽  
J.M. Slack
Keyword(s):  
Specific Activity ◽  
Biological Properties ◽  
The Body ◽  
Mesoderm Induction ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Mesoderm Formation ◽  
Low Levels

We have cloned and sequenced a new member of the fibroblast growth factor family from Xenopus laevis embryo cDNA. It is most closely related to both mammalian kFGF (FGF-4) and FGF-6 but as it is not clear whether it is a true homologue of either of these genes we provisionally refer to it as XeFGF (Xenopus embryonic FGF). Two sequences were obtained, differing by 11% in derived amino acid sequence, which probably represent pseudotetraploid variants. Both the sequence and the behaviour of in vitro translated protein indicates that, unlike bFGF (FGF-2), XeFGF is a secreted molecule. Recombinant XeFGF protein has mesoderm-inducing activity with a specific activity similar to bFGF. XeFGF mRNA is expressed maternally and zygotically with a peak during the gastrula stage. Both probe protection and in situ hybridization showed that the zygotic expression is concentrated in the posterior of the body axis and later in the tailbud. Later domains of expression were found near the midbrain/hindbrain boundary and at low levels in the myotomes. Because of its biological properties and expression pattern, XeFGF is a good candidate for an inducing factor with possible roles both in mesoderm induction at the blastula stage and in the formation of the anteroposterior axis at the gastrula stage.

A functional test for maternally inherited cadherin in Xenopus shows its importance in cell adhesion at the blastula stage

Development ◽  
1994 ◽  
Vol 120 (1) ◽  
pp. 49-57 ◽  
Author(s):  
J. Heasman ◽  
D. Ginsberg ◽  
B. Geiger ◽  
K. Goldstone ◽  
T. Pratt ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Protein Level ◽  
Mrna Level ◽  
Functional Test ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Xenopus Development ◽  
Dose Dependent ◽  
Embryonic Ectoderm ◽  
E Cadherin

We report here on the consequences of reducing the expression of EP-cadherin at the earliest stages of Xenopus development. Injection of oligodeoxynucleotides antisense to maternal EP-cadherin mRNA into full-grown oocytes reduced the mRNA level in oocytes, and the protein level in blastulae. Adhesion between blastomeres was significantly reduced, as seen in whole embryos, and in assays of the ability of blastomeres to reaggregate in culture. This effect was especially conspicuous in the inner cells of the blastula and included the disruption of the blastocoel. The severity of the EP-cadherin mRNA depletion and of the disaggregation phenotype was dose dependent. This phenotype was rescued by the injection into EP-cadherin mRNA-depleted oocytes of the mRNA coding for a related cadherin, E-cadherin, that is normally expressed at the gastrula stage in the embryonic ectoderm.

Expression of N-CAM precedes neural induction in Pleurodeles waltl (urodele, amphibian)

Development ◽  
1989 ◽  
Vol 106 (4) ◽  
pp. 675-683 ◽  
Author(s):  
J.P. Saint-Jeannet ◽  
F. Foulquier ◽  
C. Goridis ◽  
A.M. Duprat
Keyword(s):  
Monoclonal Antibody ◽  
Nervous System ◽  
Xenopus Laevis ◽  
Neural Induction ◽  
Gastrula Stage ◽  
Pleurodeles Waltl ◽  
Early Gastrula

The appearance and localization of N-CAM during neural induction were studied in Pleurodeles waltl embryos and compared with recent contradictory results reported in Xenopus laevis. A monoclonal antibody raised against mouse N-CAM was used. In the nervous system of Pleurodeles, it recognized two glycoproteins of 180 and 140×10(3) M(r) which are the Pleurodeles equivalent of N-CAM-180 and -140. Using this probe for immunohistochemistry and immunocytochemistry, we showed that N-CAM was already expressed in presumptive ectoderm at the early gastrula stage. In late gastrula embryos, a slight increase in staining was observed in the neurectoderm, whereas the labelling persisted in the noninduced ectoderm. When induced ectodermal cells were isolated at the late gastrula stage and cultured in vitro up to 14 days, a faint polarized labelling of cells was observed initially. During differentiation, the staining increased and became progressively restricted to differentiating neurons.

The effect of egg rotation on the differentiation of primordial germ cells in Xenopus laevis

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 79-99
Author(s):  
J. H. Cleine ◽  
K. E. Dixon
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Intermediate Zone ◽  
Gastrula Stage ◽  
Tail Bud ◽  
Axis Orientation ◽  
Early Gastrula ◽  
Number Of Cells

Eggs of X. laevis were rotated (sperm entrance point downwards) either through 90° (1×90 embryos) or 180° in two 90° steps (2×90 embryos) at approximately 25–30 min postfertilization after cooling to 13°C. The embryos were kept in their off-axis orientation and cooled until the early gastrula stage. Rotation resulted in relocation of egg constituents with slight changes in the distribution of outer cortical and subcortical components and major changes in inner constituents where the heavy yolk and cytoplasm appeared to reorient as a single coherent unit to maintain their relative positions with respect to gravity. Development of rotated embryos was such that regions of the egg which normally give rise to posterior structures instead developed into anterior structures and vice versa. Germ plasm was displaced in the vegetal-dorsal-animal direction (the direction of rotation) and was segregated into dorsal micromeres and intermediate zone cells in 2×90 embryos and dorsal macromeres and intermediate zone cells in 1×90 embryos. In consequence, at the gastrula stage, cells containing germ plasm were situated closer to the dorsal lip of the blastopore after rotation — in 2×90 gastrulas around and generally above the dorsal lip. Hence, in rotated embryos, the cells containing germ plasm were invaginated earlier during gastrulation and therefore were carried further anteriorly in the endoderm to a mean position anterior to the midpoint of the endoderm. The number of cells containing germ plasm in rotated embryos was not significantly different from that in controls at all stages up to and including tail bud (stage 25). However at stages 46, 48 and 49 the number of primordial germ cells was reduced in 1×90 embryos in one experiment of three and in 2×90 embryos in all experiments. We tested the hypothesis that the decreased number of primordial germ cells in the genital ridges was due to the inability of cells to migrate to the genital ridges from their ectopic location in the endoderm. When anterior endoderm was grafted into posterior endodermal regions the number of primordial germ cells increased slightly or not at all suggesting that the anterior displacement of the cells containing germ plasm was not the only factor responsible for the decreased number of primordial germ cells in rotated embryos. Other possible explanations are discussed.

Requirement of Sox2-mediated signaling for differentiation of early Xenopus neuroectoderm

Development ◽  
2000 ◽  
Vol 127 (4) ◽  
pp. 791-800 ◽  
Author(s):  
M. Kishi ◽  
K. Mizuseki ◽  
N. Sasai ◽  
H. Yamazaki ◽  
K. Shiota ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Glucocorticoid Receptor ◽  
Ligand Binding ◽  
Cell Fate ◽  
Neural Differentiation ◽  
Dominant Negative ◽  
Gastrula Stage ◽  
Blastula Stage ◽  
Sensory Epithelia ◽  
Neural Tissues

From early stages of development, Sox2-class transcription factors (Sox1, Sox2 and Sox3) are expressed in neural tissues and sensory epithelia. In this report, we show that Sox2 function is required for neural differentiation of early Xenopus ectoderm. Microinjection of dominant-negative forms of Sox2 (dnSox2) mRNA inhibits neural differentiation of animal caps caused by attenuation of BMP signals. Expression of dnSox2 in developing embryos suppresses expression of N-CAM and regional neural markers. We have analyzed temporal requirement of Sox2-mediated signaling by using an inducible dnSox2 construct fused to the ligand-binding domain of the glucocorticoid receptor. Attenuation of Sox2 function both from the late blastula stage and from the late gastrula stage onwards causes an inhibition of neural differentiation in animal caps and in whole embryos. Additionally, dnSox2-injected cells that fail to differentiate into neural tissues are not able to adopt epidermal cell fate. These data suggest that Sox2-class genes are essential for early neuroectoderm cells to consolidate their neural identity during secondary steps of neural differentiation.

Muscle gene activation by induction and the nonrequirement for cell division

Development ◽  
1986 ◽  
Vol 97 (Supplement) ◽  
pp. 75-84
Author(s):  
J. B. Gurdon ◽  
S. Fairman
Keyword(s):  
Gene Activation ◽  
Cell Types ◽  
Northern Analysis ◽  
Muscle Actin ◽  
S1 Nuclease ◽  
Cardiac Actin ◽  
Gene Transcripts ◽  
Cloned Cdna ◽  
Muscle Gene ◽  
Neurula Stage

In amphibia, as in many other animals with free-swimming larvae, muscle is one of the first differentiated cell types to be formed in early development. In Xenopus, the first contractions of axial body muscle take place about 30 h after fertilization, but genes required to form muscle are activated long before this, during gastrulation. Muscle actin proteins are first seen to be synthesized at the early neurula stage (Sturgess et al. 1980). More recently Mohun et al. (1984), using cloned cDNA probes, have found that cardiac actin, the type of muscle actin characteristic of adult heart, is a major component of the larval axial muscle. Xenopus cardiac actin gene transcripts are detected by S1 nuclease and Northern analysis at the early neurula stage (Mohun et al. 1984), and the use of SP6 probes on poly(A)+ RNA enables cardiac actin transcripts to be seen as early as the midgastrula stage (Cascio & Gurdon, 1986).

scholarly journals A Novel Complex Regulates cardiac actin Gene Expression through Interaction of Emb, a Class VI POU Domain Protein, MEF2D, and the Histone Transacetylase p300

2004 ◽  
Vol 24 (7) ◽  
pp. 2944-2957 ◽  
Author(s):  
S. Molinari ◽  
F. Relaix ◽  
M. Lemonnier ◽  
B. Kirschbaum ◽  
B. Schäfer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Gene Activation ◽  
Distal Enhancer ◽  
Cardiac Actin ◽  
Pou Domain ◽  
Cell Extracts ◽  
E Box ◽  
Novel Complex ◽  
Domain Protein ◽  
Muscle Gene

ABSTRACT Expression of the mouse cardiac actin gene depends on a distal enhancer (−7 kbp) which has been shown, in transgenic mice, to direct expression to embryonic skeletal muscle. The presence of this distal sequence is also associated with reproducible expression of cardiac actin transgenes. In differentiated skeletal muscle cells, activity of the enhancer is driven by an E box, binding MyoD family members, and by a 3′ AT-rich sequence which is in the location of a DNase I-hypersensitive site. This sequence does not bind MEF2 proteins, or other known muscle transcription factors, directly. Oct1 and Emb, a class VI POU domain protein, bind to consensus sites on the DNA, and it is the binding of Emb which is important for activity. Emb binds as a major complex with MEF2D and the histone transacetylase p300. The form of Emb present in this complex and as a major form in muscle cell extracts is longer (80 kDa) than that previously described. These results demonstrate the importance of this novel complex in the transcriptional regulation of the cardiac actin gene and suggest a potential role in chromatin remodeling associated with muscle gene activation.

scholarly journals EDS1 Contributes to Nonhost Resistance of Arabidopsis thaliana Against Erwinia amylovora

2012 ◽  
Vol 25 (3) ◽  
pp. 421-430 ◽  
Author(s):  
Manon Moreau ◽  
Alexandre Degrave ◽  
Régine Vedel ◽  
Frédérique Bitton ◽  
Oriane Patrit ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Protein Synthesis ◽  
Erwinia Amylovora ◽  
Gene Activation ◽  
Negative Regulator ◽  
Nonhost Resistance ◽  
Callose Deposition ◽  
In The Wild ◽  
Increased Sensitivity ◽  
Main Components

Erwinia amylovora causes fire blight in rosaceous plants. In nonhost Arabidopsis thaliana, E. amylovora triggers necrotic symptoms associated with transient bacterial multiplication, suggesting either that A. thaliana lacks a susceptibility factor or that it actively restricts E. amylovora growth. Inhibiting plant protein synthesis at the time of infection led to an increase in necrosis and bacterial multiplication and reduced callose deposition, indicating that A. thaliana requires active protein synthesis to restrict E. amylovora growth. Analysis of the callose synthase–deficient pmr4-1 mutant indicated that lack of callose deposition alone did not lead to increased sensitivity to E. amylovora. Transcriptome analysis revealed that approximately 20% of the genes induced following E. amylovora infection are related to defense and signaling. Analysis of mutants affected in NDR1 and EDS1, two main components of the defense-gene activation observed, revealed that E. amylovora multiplied ten times more in the eds1-2 mutant than in the wild type but not in the ndr1-1 mutant. Analysis of mutants affected in three WRKY transcription factors showing EDS1-dependent activation identified WRKY46 and WRKY54 as positive regulators and WRKY70 as a negative regulator of defense against E. amylovora. Altogether, we show that EDS1 is a positive regulator of nonhost resistance against E. amylovora in A. thaliana and hypothesize that it controls the production of several effective defenses against E. amylovora through the action of WRKY46 and WRKY54, while WRKY70 acts as a negative regulator.

scholarly journals Purification and characterization of the stage-specific embryonic enhancer-binding protein SSAP-1.

1993 ◽  
Vol 13 (3) ◽  
pp. 1746-1758 ◽  
Author(s):  
D J DeAngelo ◽  
J DeFalco ◽  
G Childs
Keyword(s):  
Gene Expression ◽  
Molecular Weight ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Gene Activation ◽  
Upstream Sequence ◽  
Blastula Stage ◽  
Sequence Element ◽  
Enhancer Element ◽  
Beta Gene

We have demonstrated that a highly conserved segment of DNA between positions -288 and -317 (upstream sequence element IV [USE IV]) is largely responsible for the transcriptional activation of the sea urchin H1-beta histone gene during the blastula stage of embryogenesis. This sequence is capable of acting as an embryonic enhancer element, activating target genes in a stage-specific manner. Nuclear extracts prepared from developmentally-staged organisms before and after the gene is activated all contain a factor which specifically binds to the enhancer. We have purified a 43-kDa polypeptide which binds to and footprints the USE IV enhancer element. We refer to this protein as stage-specific activator protein 1 (SSAP-1). Early in development before the enhancer is active, SSAP appears as a 43-kDa monomer, but it undergoes a change in its molecular weight beginning at about 12 h postfertilization (early blastula) which precisely parallels the increase in H1-beta gene expression. Modified SSAP has an apparent molecular mass of approximately 90 to 100 kDa and contains at least one 43-kDa SSAP polypeptide. Thus, it is the disappearance of the 43-kDa species and the appearance of the 90- to 100-kDa species which coincide with the H1-beta gene activation. The correlation between the change in molecular weight of SSAP and the stage-specific activation of H1-beta gene expression strongly suggests that this higher-molecular-weight form of SSAP is directly responsible for the blastula stage-specific transcriptional activation of the late H1 gene.

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