The spatio-temporal framework of melanogenic induction in pigmented retinal cells of Xenopus laevis

Development ◽  
1980 ◽  
Vol 60 (1) ◽  
pp. 173-188
Author(s):  
Olga A. Hoperskaya ◽  
Olga N. Golubeva
Keyword(s):  
Xenopus Laevis ◽  
Normal Development ◽  
Rana Temporaria ◽  
Terminal Differentiation ◽  
Gastrula Stage ◽  
Cell Type ◽  
Retinal Cells ◽  
Spatio Temporal ◽  
Species Specific

Using methods involving transplantation of neuroectoderm and eye rudiments between aap/ap mutants and + / + embryos of Xenopus laevis, new aspects of melanogenic induction have been ascertained. The possibility of separate induction of a melanocyte cell type and of the product of terminal differentiation in it — melanosomes, has been demonstrated. Melanogenic induction starts at the late gastrula stage. It has an irreversible character which has been shown using the technique of double transplantation. Melanogenic factor (MgF) is produced only by the region of endomesoderm which is adjacent to eye rudiments in the course of normal development. Competence for melanogenic induction lasts till stage NF 30. Melanogenic induction appears to be species-specific; at least after transplantation of eye vesicles from ap/apXenopus laevis to Rana temporaria the melanoprotein synthesis cannot be switched on. L-Tyrosine, under the conditions of the experiments, is not a factor in the induction of melanogenesis.

Mitotic activity of germ cells during normal development of Xenopus laevis tadpoles

Development ◽  
1975 ◽  
Vol 34 (3) ◽  
pp. 687-694
Author(s):  
Ken-Ichi Ijiri ◽  
Nobuo Egami
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
Mitotic Activity ◽  
Germ Cells ◽  
Regional Difference ◽  
Normal Development ◽  
Uniform Value ◽  
Interesting Conclusion ◽  
Spatio Temporal ◽  
Gland Development

Data on the spatio-temporal pattern of germ cell proliferation in Xenopus laevis tadpoles were obtained, tracing the germ cells from the cloacal position forward. This spatial pattern in germ cell distribution and its change during normal development clearly coincided with histological observations of germ gland development. By application of regression lines to the analysis of this complex pattern, an interesting conclusion about the mitotic activity of germ cells was suggested. While the mitotic activity of germ cells before sexual differentiation shows a regional difference along the germ-cell-containing ridge (GCCR), the doubling time of sexually differentiated gonia seems to show a uniform value over the whole GCCR

Fission yeast tmsl protein abrogates normal development in Xenopus laevis embryos

1995 ◽  
Vol 204 (3) ◽  
pp. 198-202 ◽  
Author(s):  
Peter Wagner ◽  
Michael Hoever ◽  
Katrin Appel ◽  
Walter Kn�chel ◽  
Mathias Montenarh
Keyword(s):  
Xenopus Laevis ◽  
Fission Yeast ◽  
Normal Development ◽  
Xenopus Laevis Embryos

Translocation of a store of maternal cytoplasmic c-myc protein into nuclei during early development

1989 ◽  
Vol 9 (12) ◽  
pp. 5395-5403
Author(s):  
M Gusse ◽  
J Ghysdael ◽  
G Evan ◽  
T Soussi ◽  
M Méchali
Keyword(s):  
Embryonic Development ◽  
Xenopus Laevis ◽  
Protein Content ◽  
Mature Oocyte ◽  
Gastrula Stage ◽  
Cleavage Stage ◽  
Midblastula Transition ◽  
Phosphorylation State ◽  
Growing Cell ◽  
Delayed Translation

The c-myc proto-oncogene is expressed as a maternal protein during oogenesis in Xenopus laevis, namely, in nondividing cells. A delayed translation of c-myc mRNA accumulated in early oocytes results in the accumulation of the protein during late oogenesis. The oocyte c-myc protein is unusually stable and is located in the cytoplasm, contrasting with its features in somatic cells. A mature oocyte contains a maternal c-myc protein stockpile of 4 x 10(5) to 6 x 10(5) times the level in a somatic growing cell. This level of c-myc protein is preserved only during the cleavage stage of the embryo. Fertilization triggers its rapid migration into the nuclei of the cleaving embryo and a change in the phosphorylation state of the protein. The c-myc protein content per nucleus decreases exponentially during the cleavage stage until a stoichiometric titration by the embryonic nuclei is reached during a 0.5-h period at the midblastula stage. Most of the maternal c-myc store is degraded by the gastrula stage. These observations implicate the participation of c-myc in the events linked to early embryonic development and the midblastula transition.

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 development of the tectum in Xenopus laevis: an autoradiographic study

Development ◽  
1972 ◽  
Vol 28 (1) ◽  
pp. 87-115
Author(s):  
K. Straznicky ◽  
R. M. Gaze
Keyword(s):  
Xenopus Laevis ◽  
Dna Synthesis ◽  
Optic Tectum ◽  
Tritiated Thymidine ◽  
Dorsal Surface ◽  
Autoradiographic Study ◽  
Cell Type ◽  
Pole Cells ◽  
Serial Addition ◽  
The Times

The development of the optic tectum in Xenopus laevis has been studied by the use of autoradiography with tritiated thymidine. The first part of the adult tectum to form is the rostroventral pole; cells in this position undergo their final DNA synthesis between stages 35 and 45 or shortly thereafter. Next, the cells comprising the ventrolateral border of the tectum form. These cells undergo their final DNA synthesis at or shortly after stage 45. Finally the cells comprising the dorsal surface of the adult tectum form, mainly between stages 50–55. This part of the tectum originates from the serial addition of strips of cells medially, which displace the pre-existing tissue laterally and rostrally. The formation of the tectum is virtually complete by stage 58. The tectum in Xenopus thus forms in topographical order from rostroventral to caudo-medial. The distribution of labelled cells, several stages after the time of injection of isotope, indicates that, at any one time, a segment of tectum is forming which runs normal to the tectal surface and includes all layers from the ventricular layer out to the surface. In Xenopus, therefore, the times of origin of tectal cells appear to be related not to cell type or tectal layer but to the topographical position of the cells across the surface of the tectum.

scholarly journals Identification of a regeneration-organizing cell in the Xenopus tail

Science ◽  
2019 ◽  
Vol 364 (6441) ◽  
pp. 653-658 ◽  
Author(s):  
C. Aztekin ◽  
T. W. Hiscock ◽  
J. C. Marioni ◽  
J. B. Gurdon ◽  
B. D. Simons ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Transcriptional Profiling ◽  
Cellular Mechanism ◽  
Cell Type ◽  
Genetic Ablation ◽  
Tail Development ◽  
Naturally Occurring ◽  
Early Embryos ◽  
Single Cell Rna Sequencing ◽  
Wound Epidermis

Unlike mammals, Xenopus laevis tadpoles have a high regenerative potential. To characterize this regenerative response, we performed single-cell RNA sequencing after tail amputation. By comparing naturally occurring regeneration-competent and -incompetent tadpoles, we identified a previously unrecognized cell type, which we term the regeneration-organizing cell (ROC). ROCs are present in the epidermis during normal tail development and specifically relocalize to the amputation plane of regeneration-competent tadpoles, forming the wound epidermis. Genetic ablation or manual removal of ROCs blocks regeneration, whereas transplantation of ROC-containing grafts induces ectopic outgrowths in early embryos. Transcriptional profiling revealed that ROCs secrete ligands associated with key regenerative pathways, signaling to progenitors to reconstitute lost tissue. These findings reveal the cellular mechanism through which ROCs form the wound epidermis and ensure successful regeneration.

Evolutionary origin of the cell nucleus and its functional architecture

2010 ◽  
Vol 48 ◽  
pp. 1-24 ◽  
Author(s):  
Jan Postberg ◽  
Hans J. Lipps ◽  
Thomas Cremer
Keyword(s):  
Cell Nucleus ◽  
Interdisciplinary Research ◽  
Nuclear Organization ◽  
Nuclear Architecture ◽  
Evolutionary Origin ◽  
Cell Type ◽  
Research Strategies ◽  
Evolutionarily Conserved ◽  
Species Specific ◽  
The Impact

Understanding the evolutionary origin of the nucleus and its compartmentalized architecture provides a huge but, as expected, greatly rewarding challenge in the post-genomic era. We start this chapter with a survey of current hypotheses on the evolutionary origin of the cell nucleus. Thereafter, we provide an overview of evolutionarily conserved features of chromatin organization and arrangements, as well as topographical aspects of DNA replication and transcription, followed by a brief introduction of current models of nuclear architecture. In addition to features which may possibly apply to all eukaryotes, the evolutionary plasticity of higher-order nuclear organization is reflected by cell-type- and species-specific features, by the ability of nuclear architecture to adapt to specific environmental demands, as well as by the impact of aberrant nuclear organization on senescence and human disease. We conclude this chapter with a reflection on the necessity of interdisciplinary research strategies to map epigenomes in space and time.

scholarly journals Regulation of melanocyte development by ligand-dependent BMP signaling underlies oncogenic BMP signaling in melanoma

2019 ◽  
Author(s):  
Alec K. Gramann ◽  
Arvind M. Venkatesan ◽  
Melissa Guerin ◽  
Craig J. Ceol
Keyword(s):  
Neural Crest ◽  
Pigment Cell ◽  
Terminal Differentiation ◽  
Melanoma Cells ◽  
Cell Development ◽  
Bmp Signaling ◽  
Pigment Cells ◽  
Cell Type ◽  
Neural Crest Development ◽  
Direct Regulation

AbstractPreventing terminal differentiation is important in the development and progression of many cancers including melanoma. Recent identification of the BMP ligand GDF6 as a novel melanoma oncogene showed GDF6-activated BMP signaling suppresses differentiation of melanoma cells. Previous studies have identified roles for GDF6 orthologs during early embryonic and neural crest development, but have not identified direct regulation of melanocyte development by GDF6. Here, we investigate the BMP ligand gdf6a, a zebrafish ortholog of human GDF6, during the development of melanocytes from the neural crest. We establish that the loss of gdf6a or inhibition of BMP signaling during neural crest development disrupts normal pigment cell development, leading to an increase in the number of melanocytes and a corresponding decrease in iridophores, another neural crest-derived pigment cell type in zebrafish. This shift occurs as pigment cells arise from the neural crest and depends on mitfa, an ortholog of MITF, a key regulator of melanocyte development that is also targeted by oncogenic BMP signaling. Together, these results indicate that the oncogenic role ligand-dependent BMP signaling plays in suppressing differentiation in melanoma is a reiteration of its physiological roles during melanocyte development.

scholarly journals Uptake of fluorescent-labeled BSA into root cells: endocytosis?

2014 ◽  
Vol 66 (3-4) ◽  
pp. 319-324 ◽  
Author(s):  
A. Kaźmierczak ◽  
J. Maszewski
Keyword(s):  
Zea Mays ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Cytochalasin B ◽  
Fluorescein Isothiocyanate ◽  
Cell Type ◽  
Root Cells ◽  
Root Zones ◽  
Species Specific

Incorporation of rhodamine- and fluorescein-isothiocyanate labeled bovine serum albumin (BSA-TRITC, BSA-FITC) was examined in different root zones of the 3-day-old seedlings in <em>Melandrium noctiflorum</em>, <em>Allium cepa</em> and <em>Zea mays</em>. The uptake of fluorescent-labeled BSA was found: (1) species-specific, (2) cell-type dependent, and (3) cytochalasin B-sensitive. The characteristic punctute distribution of vesicles within the cytoplasm suggests the internalization of labeled proteins by endocytosis.

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