Signals That Instruct Somite and Myotome Formation Persist in Xenopus laevis Early Tailbud Stage Embryos

2002 ◽  
Vol 172 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Lisa A. Dali ◽  
Jean Gustin ◽  
Kathleen Perry ◽  
Carmen R. Domingo
Keyword(s):  
Xenopus Laevis ◽  
Tailbud Stage

EP-cadherin in muscles and epithelia of Xenopus laevis embryos

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1335-1344 ◽  
Author(s):  
G. Levi ◽  
D. Ginsberg ◽  
J.M. Girault ◽  
I. Sabanay ◽  
J.P. Thiery ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Developmental Stages ◽  
Close Association ◽  
Apical Surface ◽  
Major Site ◽  
Tailbud Stage ◽  
Migratory Cells ◽  
Endodermal Cells ◽  
Xenopus Laevis Embryos ◽  
E Cadherin

EP-cadherin is a novel Xenopus Ca+2-dependent adhesion molecule, which shares comparable homology with mouse E- and P-cadherins (Ginsberg, De Simone and Geiger; 1991, Development 111, 315–325). We report here the patterns of expression of this molecule in Xenopus laevis embryos at different developmental stages ranging from cleavage to postmetamorphic. EP-cadherin is already expressed in the oocyte and egg and can then be detected in close association with the membrane of all blastomeres up to late blastula stages. Starting at late gastrula stages, the level of EP-cadherin expression increases sharply in non-neural ectodermal cells, in the somites and in the notochord; it persists in endodermal cells and decreases rapidly in all migratory cells. During neurulation the level of EP-cadherin expression declines gradually in the nervous system and is undetectable here throughout later development except in the optic nerve and in the neural part of the olfactory organ. This pattern continues during later development so that in the tailbud stage and up to metamorphosis the most prominent staining is detected in the epidermis and skeletal muscle. After metamorphosis, the molecule gradually disappears from the muscle tissue and the major site of expression remains the skin. EP-cadherin is invariably present in close association with the cell membrane. In the muscle it is associated with the sarcolemma at regions of myoblast-myoblast or myotube-myotube contact. In epidermal cells, EP-cadherin is usually coexpressed with E-cadherin. Yet, while E-cadherin staining is always restricted to the basolateral aspects of the cells, EP-cadherin is often distributed throughout the plasmalemma including the apical surface.

Replacement of posterior by anterior endoderm reduces sterility in embryos from inverted eggs of Xenopus laevis

Development ◽  
1986 ◽  
Vol 94 (1) ◽  
pp. 83-93
Author(s):  
J. H. Cleine
Keyword(s):  
Cell Differentiation ◽  
Xenopus Laevis ◽  
Germ Cell ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Inverted Position ◽  
Control Series ◽  
Germ Cell Differentiation ◽  
Tailbud Stage

The genital ridges of Xenopus laevis tadpoles reared from eggs kept in an inverted position contain less than 40 % of the number of primordial germ cells (PGCs) of controls (Cleine & Dixon, 1985). It has been suggested that this reduction is caused by the germ cells' ectopic position in the anterior endoderm of larvae from inverted eggs, from where they may be unable to migrate into the genital ridges (Cleine & Dixon, 1985). This hypothesis is tested here by interchanging anterior and posterior endodermal grafts between pairs of inverted embryos at the early tailbud stage. Replacement of anterior by posterior endoderm has no effect but replacement of posterior by anterior endoderm increases the number of PGCs in the genital ridges and significantly reduces the proportion of sterile embryos. In a control series, in which the same type of grafting was done with normal embryos, replacement of posterior by anterior endoderm reduced the number of germ cells to almost zero, but replacement of anterior by posterior endoderm nearly doubled it. These findings are explained in terms of the distribution of the germ cells in the endoderm at the time of grafting. The results firstly show that the position of the germ cells is crucial to successful migration and secondly they support the notion that germ plasm has a determinative role during early germ cell differentiation.

scholarly journals A monoclonal antibody specific for an epidermal cell antigen of Xenopus laevis: electron microscopic observations using a gold-labeling method.

1988 ◽  
Vol 36 (5) ◽  
pp. 515-521 ◽  
Author(s):  
M Asada-Kubota
Keyword(s):  
Monoclonal Antibody ◽  
Epithelial Cells ◽  
Xenopus Laevis ◽  
Apical Cell ◽  
Superficial Layer ◽  
Electron Microscopic ◽  
Larval Stages ◽  
Tailbud Stage ◽  
Stage Stage ◽  
Epidermal Development

A monoclonal antibody (EPI-1), raised against the supernatant of a homogenate of Xenopus laevis larvae at the tailbud stage (stage 36/37), interacts specifically with a 250 KD epidermal antigen of Xenopus. An immunocytochemical gold-labeling technique was used to investigate changes in antigen distribution during epidermal development of Xenopus laevis. Specific immunolabeling was initially detected over the endoplasmic reticulum in the outer epithelial cells of the late gastrula stage (stage 12.5). After the early neurula stage (stage 13), immunolabeling appeared over moderately electron-dense bodies (these bodies disappear after stage 29), and also over the apical cell surface and adjacent cytoplasm of all the outer epithelial cells. During metamorphosis, labeling decreased and disappeared after stage 62, as the superficial layer had peeled off. These data suggest that the antigen is useful as a marker of general differentiation in studies of epidermal development during the embryonic and larval stages of Xenopus laevis.

Pattern regulation in isolated halves and blastomeres of early Xenopus laevis

Development ◽  
1983 ◽  
Vol 74 (1) ◽  
pp. 221-234
Author(s):  
H. Kageura ◽  
K. Yamana
Keyword(s):  
Xenopus Laevis ◽  
Calf Serum ◽  
The Other ◽  
Foetal Calf Serum ◽  
Cell Stage ◽  
Macroscopic Appearance ◽  
Xenopus Embryos ◽  
Early Embryos ◽  
Tailbud Stage ◽  
Pattern Regulation

Xenopus embryos at the 2-cell stage were cut into right and left halves, those at the 4-cell stage into dorsal and ventral halves or individual blastomeres, and those at the 8-cell stage into lateral, animal and vegetal halves. Defect embryos, that is, 8-cell embryos from which a particular pair of blastomeres had been removed, were also prepared. These halves, blastomeres and defect embryos were cultured in 50% Leibovitz (L-15) medium supplemented with 10% foetal calf serum and then in 10% Steinberg solution. Their development was determined from their macroscopic appearance when controls reached stage 26 (early tailbud stage) or later. The only halves that could develop into normal larvae or frogs were lateral ones of 2- and 8-cell embryos. An interesting finding was that these halves of 2-cell embryos developed into only half-embryos when cultured in the above Leibovitz medium beyond the beginning of gastrulation. On the other hand, most or all the dorsal and ventral halves at the 4-cell stage and the animal and vegetal quartets at the 8-cell stage did not form normally proportioned embryos. Defect embryos lacking any two blastomeres of the animal half gave rise to nearly normal embryos, whereas those lacking two dorsal or two ventral blastomeres of the vegetal half did not. From the present results and those of studies now in progress, it is concluded that development of blastomeres and halves from these early embryos, except lateral halves from 2- and 8-cell embryos, is not regulative as expected earlier, and that a certain combination of blastomeres is essential for complete pattern regulation.

Analysis of hsp 30, hsp 70 and ubiquitin gene expression in Xenopus laevis tadpoles

Development ◽  
1988 ◽  
Vol 103 (1) ◽  
pp. 59-67
Author(s):  
P.H. Krone ◽  
J.J. Heikkila
Keyword(s):  
Heat Shock ◽  
Xenopus Laevis ◽  
Temporal Pattern ◽  
Size Range ◽  
Continuous Exposure ◽  
Hsp 70 ◽  
Blastula Stage ◽  
Tailbud Stage ◽  
Actin Mrna ◽  
Continuous Heat

Heat-induced accumulation of hsp 30 mRNA (1.1 kb) during early development of Xenopus laevis was first detectable at the tailbud stage (stage 30–34). This contrasts with heat-induced accumulation of hsp 70 mRNA (2.7 kb) and ubiquitin mRNA (size range = 1.7–3.1 kb), which was first detectable at the mid- to late-blastula stage. Continuous exposure of tadpoles to a 33 degrees C heat shock resulted in a coordinate, transient accumulation of hsp 30, hsp 70 and ubiquitin mRNA. A coordinate, temporal pattern was also observed for the decay of hsp 30, hsp 70 and ubiquitin mRNA in tadpoles recovering at 22 degrees C following a 1 h heat shock at 33 degrees C. Thus, while hsp 30 genes are regulated differently during development compared with hsp 70 and ubiquitin genes, these genes all exhibit a coordinate heat-inducible pattern of expression at the tadpole stage. Levels of alpha-cardiac actin mRNA remained unchanged during continuous heat shock and recovery experiments.

Occludin dephosphorylation in early development of Xenopus laevis

1997 ◽  
Vol 110 (24) ◽  
pp. 3131-3139 ◽  
Author(s):  
M. Cordenonsi ◽  
E. Mazzon ◽  
L. De Rigo ◽  
S. Baraldo ◽  
F. Meggio ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Xenopus Laevis ◽  
Tight Junction ◽  
De Novo ◽  
Cytoplasmic Domain ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Epithelial Junctions ◽  
Tailbud Stage

Using immunoblot and immunofluorescence analysis with a cross-reacting antiserum, we identified Xenopus laevis occludin as a 57–61 kDa antigen colocalized with cingulin in epithelial junctions of embryos. Occludin was completely extracted from unfertilized eggs and embryos with a solution containing 0.1% Triton X-100 and 1% NP40. Maternal occludin in unfertilized eggs migrated by SDS-PAGE as a 61 kDa protein. In fertilized eggs and in early cleavages up to blastula stage 8 it migrated as a series of polypeptides with 57–60 kDa. In gastrulae, neurulae and tailbud stage embryos, it migrated as a 57 kDa polypeptide. The electrophoretic mobility downshift was specifically reproduced by treatment of extracts with acid phosphatase, indicating that it is due to dephosphorylation. The correlation of occludin dephosphorylation with the de novo assembly of tight junction in native epithelia of Xenopus embryos suggests a possible role of occludin dephosphorylation in the events leading to tight junction assembly. To identify kinases which can phosphorylate occludin, recombinant chicken occludin (cytoplasmic domain) was subjected to in vitro phosphorylation. Occludin was phosphorylated on serine and threonine residues by protein kinase CK2 and p34cdc2/cyclin B complex, but was not significantly phosphorylated by mitogen-activated protein kinase, protein kinase CK1 and p38Syk tyrosine kinase. We noted that occludin sequences contain a motif matching the activation loop of the cytoplasmic domain of insulin receptor kinase.

Expression of microinjected hsp 70/CAT and hsp 30/CAT chimeric genes in developing Xenopus laevis embryos

Development ◽  
1989 ◽  
Vol 106 (2) ◽  
pp. 271-281
Author(s):  
P.H. Krone ◽  
J.J. Heikkila
Keyword(s):  
Xenopus Laevis ◽  
Fusion Gene ◽  
Developmental Regulation ◽  
Hsp 70 ◽  
Inhibitory System ◽  
Developmentally Regulated ◽  
Promoter Sequences ◽  
Chimeric Genes ◽  
Stage Of Development ◽  
Tailbud Stage

The expression of microinjected chimeric genes containing Drosophila hsp 70 and Xenopus hsp 70 and hsp 30 promoters linked to the reporter gene coding for bacterial chloramphenicol acetyltransferase (CAT) was examined during early development of Xenopus laevis. Heat-inducible expression of fusion genes containing either the Drosophila hsp 70 promoter (1100 bp) or the Xenopus hsp 70 promoter (750 bp) was first detectable after the midblastula stage of development. This coincides with the embryonic stage at which the endogenous hsp 70 gene is first heat-inducible. A Xenopus hsp 30/CAT fusion gene containing 350 bp of promoter sequences was also heat-inducible after the midblastula stage unlike the endogenous hsp 30 genes which were not heat-inducible until the early tailbud stage (stage 23–24). Sequences that are present within either the coding or 3′ region of the hsp 30 clone do not cause the microinjected hsp 30 gene to be developmentally regulated in a normal manner. Additionally, microinjected hsp 30 gene sequences have no effect on the developmental regulation of endogenous hsp 30 genes which continue to be activated at the tailbud stage of development. Our data suggest, that an inhibitory system, which may control the expression of the endogenous hsp 30 gene during development, does not regulate the expression of the injected hsp 30 gene.

scholarly journals PCR detection of excision suggests mobility of the medaka fish Tol1 transposable element in the frog Xenopus laevis

2007 ◽  
Vol 89 (4) ◽  
pp. 201-206 ◽  
Author(s):  
AKIRA HIKOSAKA ◽  
AKIHIKO KOGA
Keyword(s):  
Xenopus Laevis ◽  
Transposable Element ◽  
Model Organism ◽  
Full Length ◽  
Medaka Fish ◽  
Helper Plasmid ◽  
Cell Stage ◽  
Wide Range ◽  
Tailbud Stage ◽  
Clawed Frog

SummaryTol1 is a DNA-based transposable element identified in the medaka fish Oryzias latipes and a member of the hAT (hobo/Activator/Tam3) transposable element family. Its mobility has already been demonstrated in the human and mouse, in addition to its original host species. This element is thus expected to be useful in a wide range of vertebrates as a genomic manipulation tool. Herein, we show that the Tol1 element can undergo excision in the African clawed frog Xenopus laevis, a major model organism for vertebrate genetics and developmental biology. An indicator plasmid carrying a Tol1 element was injected into 2- or 4-cell-stage embryos together with either a helper plasmid coding for the full-length Tol1 transposase or a modified helper plasmid yielding a truncated protein, and recovered from tailbud-stage embryos. Deletion of the Tol1 region of the indicator plasmid was observed in the experiment with the full-length transposase, and not in the other case. The deletion was associated with various footprint sequences at breakpoints, as frequently observed with many DNA-based transposable elements. These results indicate that the Tol1 element was excised from the indicator plasmid by catalysis of the transposase, and suggest that the Tol1 element is mobile in this frog species.

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

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