scholarly journals ARHGEF3.2 modulates Wnt‐PCP signaling in dorsal marginal zone of Xenopus embryos during early development

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Jaeho Yoon ◽  
Jee‐In Heo ◽  
Sung Chan Kim ◽  
Jae‐Bong Park ◽  
Jae‐Yong Lee ◽  
...  
Keyword(s):  
Early Development ◽  
Marginal Zone ◽  
Xenopus Embryos ◽  
Pcp Signaling

The origins of primitive blood in Xenopus: implications for axial patterning

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 423-434 ◽  
Author(s):  
M.C. Lane ◽  
W.C. Smith
Keyword(s):  
Xenopus Laevis ◽  
Marginal Zone ◽  
Cell Stage ◽  
Axial Patterning ◽  
Xenopus Embryos ◽  
Spemann's Organizer ◽  
Dorsal Mesoderm

The marginal zone in Xenopus laevis is proposed to be patterned with dorsal mesoderm situated near the upper blastoporal lip and ventral mesoderm near the lower blastoporal lip. We determined the origins of the ventralmost mesoderm, primitive blood, and show it arises from all vegetal blastomeres at the 32-cell stage, including blastomere C1, a progenitor of Spemann's organizer. This demonstrates that cells located at the upper blastoporal lip become ventral mesoderm, not solely dorsal mesoderm as previously believed. Reassessment of extant fate maps shows dorsal mesoderm and dorsal endoderm descend from the animal region of the marginal zone, whereas ventral mesoderm descends from the vegetal region of the marginal zone, and ventral endoderm descends from cells located vegetal of the bottle cells. Thus, the orientation of the dorsal-ventral axis of the mesoderm and endoderm is rotated 90(degrees) from its current portrayal in fate maps. This reassessment leads us to propose revisions in the nomenclature of the marginal zone and the orientation of the axes in pre-gastrula Xenopus embryos.

Sizzled: a secreted Xwnt8 antagonist expressed in the ventral marginal zone of Xenopus embryos

Development ◽  
1997 ◽  
Vol 124 (23) ◽  
pp. 4739-4748 ◽  
Author(s):  
A.N. Salic ◽  
K.L. Kroll ◽  
L.M. Evans ◽  
M.W. Kirschner
Keyword(s):  
Marginal Zone ◽  
Signal Sequence ◽  
Expression Cloning ◽  
Midblastula Transition ◽  
Xenopus Embryos ◽  
Rich Domain ◽  
Molecular Pattern ◽  
Dependent Inhibition ◽  
Frizzled Receptors ◽  
Dose Dependent Inhibition

An expression cloning screen was used to isolate a novel gene homologous to the extracellular cysteine-rich domain of frizzled receptors. The gene (which we called sizzled for secreted frizzled) was shown to encode a soluble secreted protein, containing a functional signal sequence but no transmembrane domains. Sizzled (szl) is capable of inhibiting Xwnt8 as assayed by (1) dose-dependent inhibition of siamois induction by Xwnt8 in animal caps, (2) rescue of embryos ventralized by Xwnt8 DNA and (3) inhibition of XmyoD expression in the marginal zone. Szl can dorsalize Xenopus embryos if expressed after the midblastula transition, strengthening the idea that zygotic expression of wnts and in particular of Xwnt8 plays a role in antagonizing dorsal signals. It also suggests that inhibiting ventralizing wnts parallels the opposition of BMPs by noggin and chordin. szl expression is restricted to a narrow domain in the ventral marginal zone of gastrulating embryos. szl thus encodes a secreted antagonist of wnt signaling likely involved in inhibiting Xwnt8 and XmyoD ventrally and whose restricted expression represents a new element in the molecular pattern of the ventral marginal zone.

Xenopus axis formation: induction of goosecoid by injected Xwnt-8 and activin mRNAs

Development ◽  
1993 ◽  
Vol 118 (2) ◽  
pp. 499-507 ◽  
Author(s):  
H. Steinbeisser ◽  
E.M. De Robertis ◽  
M. Ku ◽  
D.S. Kessler ◽  
D.A. Melton
Keyword(s):  
Uv Irradiation ◽  
High Frequency ◽  
Marginal Zone ◽  
Homeobox Gene ◽  
Dorsal Side ◽  
Axis Formation ◽  
Gene Products ◽  
Turn On ◽  
Xenopus Embryos ◽  
Spemann's Organizer

In this study, we compare the effects of three mRNAs-goosecoid, activin and Xwnt-8- that are able to induce partial or complete secondary axes when injected into Xenopus embryos. Xwnt-8 injection produces complete secondary axes including head structures whereas activin and goosecoid injection produce partial secondary axes at high frequency that lack head structures anterior to the auditory vesicle and often lack notochord. Xwnt-8 can activate goosecoid only in the deep marginal zone, i.e., in the region in which this organizer-specific homeobox gene is normally expressed on the dorsal side. Activin B mRNA, however, can turn on goosecoid in all regions of the embryo. We also tested the capacity of these gene products to restore axis formation in embryos in which the cortical rotation was blocked by UV irradiation. Whereas Xwnt-8 gives complete rescue of anterior structures, both goosecoid and activin give partial rescue. Rescued axes including hindbrain structures up to level of the auditory vesicle can be obtained at high frequency even in the absence of notochord structures. The possible functions of Wnt-like and activin-like signals and of the goosecoid homeobox gene, and their order of action in the formation of Spemann's organizer are discussed.

scholarly journals Using 32-Cell Stage Xenopus Embryos to Probe PCP Signaling

2011 ◽  
pp. 91-104 ◽  
Author(s):  
Hyun-Shik Lee ◽  
Sergei Y. Sokol ◽  
Sally A. Moody ◽  
Ira O. Daar
Keyword(s):  
Cell Stage ◽  
Xenopus Embryos ◽  
Pcp Signaling

Early development of Xenopus embryos is affected by simulated gravity

1994 ◽  
Vol 14 (8) ◽  
pp. 249-255 ◽  
Author(s):  
Hiroki Yokota ◽  
Anton W. Neff ◽  
George M. Malacinski
Keyword(s):  
Early Development ◽  
Xenopus Embryos

Localization and induction in early development of Xenopus

1984 ◽  
Vol 307 (1132) ◽  
pp. 319-330 ◽  
Keyword(s):  
Early Development ◽  
Marginal Zone ◽  
Experimental Results ◽  
Cytoplasmic Region ◽  
Zone Cell

Our experimental results, as well as those of others, lead us to suggest the following steps in the dorsalization and axialization of the Xenopus egg and embryo: (1) the spermaster determines the direction of rotation of the cortex relative to the deeper cytoplasm (endoplasm ); (2) the rotation of the cortex activates latent dorsalizingaxializing agents in the vegetal hemisphere. The extent of rotation determines the am ount of activation. The direction of rotation determines the location of the activated agents. (3) The activated agents determine the level of mesoderm-inducing activity of the vegetal cells cleaved from that cytoplasmic region. (4) The level of inducing activity determines at least the time at which marginal zone cells will begin gastrulation movements. (5) The time of its initiation of gastrulation may determine how anterior and dorsal a particular marginal zone cell can become.

scholarly journals A novel role for the extraembryonic area opaca in positioning the primitive streak of the early chick embryo

2021 ◽  
Author(s):  
Hyung Chul Lee ◽  
Claudio D Stern
Keyword(s):  
Chick Embryo ◽  
Early Development ◽  
Marginal Zone ◽  
Outer Region ◽  
Primitive Streak ◽  
Support Functions ◽  
Anterior Half ◽  
Embryonic Polarity ◽  
Classical Studies ◽  
Area Pellucida

Classical studies have established that the marginal zone, a ring of extraembryonic epiblast immediately surrounding the embryonic epiblast (area pellucida) of the chick embryo is important in setting embryonic polarity by positioning the primitive streak, the site of gastrulation. The more external extraembryonic region (area opaca) was only thought to have nutritive and support functions. Using experimental embryology approaches, this study reveals three separable functions for this outer region: first, juxtaposition of the area opaca directly onto the area pellucida induces a new marginal zone from the latter; this induced domain is entirely posterior in character. Second, ablation and grafting experiments using an isolated anterior half of the blastoderm and pieces of area opaca suggest that the area opaca can influence the polarity of the adjacent marginal zone. Finally, we show that the loss of the ability of such isolated anterior half-embryos to regulate (re-establish polarity spontaneously) at the early primitive streak stage can be rescued by replacing the area opaca by one from a younger stage. These results uncover new roles of chick extraembryonic tissues in early development.

Deep cytoplasmic rearrangements during early development in Xenopus laevis

Development ◽  
1991 ◽  
Vol 111 (4) ◽  
pp. 845-856 ◽  
Author(s):  
M.V. Danilchik ◽  
J.M. Denegre
Keyword(s):  
Cell Cycle ◽  
Plasma Membrane ◽  
Xenopus Laevis ◽  
Early Development ◽  
Marginal Zone ◽  
Dorsal Side ◽  
Fluorescent Dye ◽  
Entry Point ◽  
Sperm Entry ◽  
Yolk Platelet

The egg of the frog Xenopus is cylindrically symmetrical about its animal-vegetal axis before fertilization. Midway through the first cell cycle, the yolky subcortical cytoplasm rotates 30 degrees relative to the cortex and plasma membrane, usually toward the side of the sperm entry point. Dorsal embryonic structures always develop on the side away from which the cytoplasm moves. Details of the deep cytoplasmic movements associated with the cortical rotation were studied in eggs vitally stained during oogenesis with a yolk platelet-specific fluorescent dye. During the first cell cycle, eggs labelled in this way develop a complicated swirl of cytoplasm in the animal hemisphere. This pattern is most prominent on the side away from which the vegetal yolk moves, and thus correlates in position with the prospective dorsal side of the embryo. Although the pattern is initially most evident near the egg's equator or marginal zone, extensive rearrangements associated with cleavage furrowing (cytoplasmic ingression) relocate portions of the swirl to vegetal blastomeres on the prospective dorsal side.

Reptilian cortex and mammalian neocortex early developmental homologies

2003 ◽  
Vol 26 (5) ◽  
pp. 560-561
Author(s):  
Miguel Marín-Padilla
Keyword(s):  
Cerebral Cortex ◽  
Early Development ◽  
Pyramidal Cell ◽  
Structural Organization ◽  
Marginal Zone ◽  
Cell Plate ◽  
Target Article ◽  
Layer I ◽  
Early Developmental

I agree with the view expressed in the target article that the early structural organization of the mammalian neocortex (the primordial neocortical organization) is different from its final one and resembles the more primitive organization of reptilian cortex. During the early development of the neocortex, a distinctly mammalian multilayered pyramidal-cell plate is introduced within a more primitive reptilian-like cortex, establishing simultaneously layer I (marginal zone) above it and layer VII (subplate zone) below it. This multilayered pyramidal-cell plate represents a recent mammalian innovation in the evolution of the cerebral cortex of vertebrates. Hence, the term neocortex is preferable to isocortex.

scholarly journals Sox10 is required for the early development of the prospective neural crest in Xenopus embryos

2003 ◽  
Vol 260 (1) ◽  
pp. 79-96 ◽  
Author(s):  
Stella M Honoré ◽  
Manuel J Aybar ◽  
Roberto Mayor
Keyword(s):  
Neural Crest ◽  
Early Development ◽  
Xenopus Embryos
Sign in / Sign up

Export Citation Format

Share Document