Axis and germ line deficiencies caused by u.v. irradiation of Xenopus oocytes cultured in vitro

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 735-743 ◽  
Author(s):  
S. Holwill ◽  
J. Heasman ◽  
C.R. Crawley ◽  
C.C. Wylie
Keyword(s):  
Xenopus Oocytes ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Spatial Arrangement ◽  
Sensitive Period ◽  
Axis Formation ◽  
Cytoplasmic Localization ◽  
Dorsal Axis ◽  
Vegetal Pole

An intriguing aspect of developmental biology is the extent to which early development is controlled by the spatial arrangement of molecules in the oocyte. Ultraviolet (u.v.) irradiation of the vegetal pole of the fertilized egg of Xenopus laevis affects both the development of the embryonic dorsal axis and also the formation of primordial germ cells (PGCs). However, the importance of cytoplasmic localization in the oocyte has been difficult to assess because, until recently, it has proved impossible to mature and fertilize cultured oocytes routinely. In this report, we describe a method for routinely maturing and fertilizing cultured oocytes of Xenopus. We find that the u.v.-sensitive period for PGC and dorsal axis formation extends back into stage-VI oocytes, thus demonstrating a true oocyte contribution to these processes. This method also allows greater time for experimental intervention and should facilitate the eventual isolation of the molecules concerned.

Further analysis of the effect of ultra-violet irradiation on the formation of the germ line in Xenopus laevis

Development ◽  
1983 ◽  
Vol 76 (1) ◽  
pp. 67-81
Author(s):  
V. Thomas ◽  
J. Heasman ◽  
C. Ford ◽  
D. Nagajski ◽  
C. C. Wylie
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Ultra Violet ◽  
The Other ◽  
Yolk Mass ◽  
Cell Numbers ◽  
Dorsal Axis ◽  
Vegetal Pole ◽  
Dorsal Mesentery

Ultra-violet (u.v.) irradiation of the vegetal pole of newly fertilized eggs has three documented effects: reduction of primordial germ cells (PGCs), cytological damage to the vegetal hemisphere and disruption of the normal mechanism by which the vegetal yolk mass induces the formation of the dorsal axis of the embryo. In this study, we find that 90° rotation of the egg for various periods after irradiation rescues the dorsal axial structures but does not restore the number of PGCs found in the dorsal mesentery of the gut; neither is there any correlation between reduced numbers of PGCs and disruption of cleavage at the vegetal pole. We therefore conclude that the effect on the germ line is separate from the other two phenomena. Secondly, 90° rotation of non-irradiated eggs was found to significantly reduce germ cell numbers migrating in the dorsal mesentery of the gut.

scholarly journals HYBRID DYSGENESIS IN DROSOPHILA MELANOGASTER: THE BIOLOGY OF FEMALE AND MALE STERILITY

Genetics ◽  
1979 ◽  
Vol 92 (1) ◽  
pp. 161-174
Author(s):  
William R Engels ◽  
Christine R Preston
Keyword(s):  
Male Sterility ◽  
Germ Cells ◽  
Germ Line ◽  
Hybrid Sterility ◽  
Primordial Germ Cells ◽  
Wild Strain ◽  
Hybrid Dysgenesis ◽  
Sensitive Period ◽  
Male Recombination ◽  
Larval Stages

ABSTRACT High levels of female and male sterility were observed among the hybrids from one of the two reciprocal crosses between a wild strain of D. melanogaster known as π2 and laboratory strains. The sterility, which is part of a common syndrome called hybrid dysgenesis, was found to be associated with the rudimentary condition of one or both of the ovaries or testes. All other tissues, including those of the reproductive system were normal, as were longevity and mating behavior. The morphological details of the sterility closely mimic the agametic condition occurring when germ cells are destroyed by irradiation or by the maternal-effect mutation, grandchildless. We suggest that sterility in hybrid dysgenesis is also caused by failure in the early development of germ cells. There is a thermo-sensitive period beginning at approximately the time of initiation of mitosis among primordial germ cells a few hours before the egg hatches and ending during the early larval stages. Our results suggest that hybrid dysgenesis, which also includes male recombination, mutation and other traits, may be limited to the germ line, and that each of the primordial germ cells develops, or fails to develop, independently of the others. This hypothesis is consistent with the observed frequencies of unilateral and bilateral sterility, with the shape of the thermo-sensitivity curves and with the fact that males are less often sterile than females. The features of this intraspecific hybrid sterility are found to resemble those seen in some interspecific Drosophila hybrids, especially those from the cross D. melanogasfer × D. simulans.

The vegetal determinants required for the Spemann organizer move equatorially during the first cell cycle

Development ◽  
1996 ◽  
Vol 122 (7) ◽  
pp. 2207-2214 ◽  
Author(s):  
M. Sakai
Keyword(s):  
Cell Cycle ◽  
Formation Process ◽  
Lithium Treatment ◽  
Axis Formation ◽  
Cell Stage ◽  
Spemann Organizer ◽  
Dorsal Axis ◽  
Vegetal Pole ◽  
Organizing Center ◽  
Cell Embryo

Embryos with no dorsal axis were obtained when more than 15% of the egg surface was deleted from the vegetal pole of the early 1-cell embryo of Xenopus laevis. The timing of the deletion in the first cell cycle was critical: dorsal-deficient embryos were obtained when the deletion began before time 0.5 (50% of the first cell cycle) whereas normal dorsal axis usually formed when the deletion was done later than time 0.8. The axis deficiency could be restored by lithium treatment and the injection of vegetal but not animal cytoplasm. Bisection of the embryo at the 2-cell stage, which is known to restore the dorsal structures in the UV-ventralized embryos, had no effect on the vegetal-deleted embryos. These results show clearly that, in Xenopus, (1) the dorsal determinants (DDs) localized in the vegetal pole region at the onset of development are necessary for dorsal axis development and (2) the DDs move from the vegetal pole to a subequatorial region where they are incorporated into gastrulating cells to form the future organizing center. A model for the early axis formation process in Xenopus is proposed.

scholarly journals Nuclear Reprogramming in Mouse Primordial Germ Cells: Epigenetic Contribution

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Massimo De Felici
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Germ Cell Tumors ◽  
Cell Lineage ◽  
Epigenetic Modifications ◽  
Epigenetic Reprogramming ◽  
Nuclear Reprogramming

The unique capability of germ cells to give rise to a new organism, allowing the transmission of primary genetic information from generation to generation, depends on their epigenetic reprogramming ability and underlying genomic totipotency. Recent studies have shown that genome-wide epigenetic modifications, referred to as “epigenetic reprogramming”, occur during the development of the gamete precursors termed primordial germ cells (PGCs) in the embryo. This reprogramming is likely to be critical for the germ line development itself and necessary to erase the parental imprinting and setting the base for totipotency intrinsic to this cell lineage. The status of genome acquired during reprogramming and the associated expression of key pluripotency genes render PGCs susceptible to transform into pluripotent stem cells. This may occurin vivounder still undefined condition, and it is likely at the origin of the formation of germ cell tumors. The phenomenon appears to be reproduced under partly definedin vitroculture conditions, when PGCs are transformed into embryonic germ (EG) cells. In the present paper, I will try to summarize the contribution that epigenetic modifications give to nuclear reprogramming in mouse PGCs.

scholarly journals The ontogeny of cKIT+ human primordial germ cells proves to be a resource for human germ line reprogramming, imprint erasure and in vitro differentiation

2012 ◽  
Vol 15 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Sofia Gkountela ◽  
Ziwei Li ◽  
John J. Vincent ◽  
Kelvin X. Zhang ◽  
Angela Chen ◽  
...  
Keyword(s):  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
In Vitro Differentiation

scholarly journals Formative pluripotent stem cells show features of epiblast cells poised for gastrulation

Cell Research ◽  
2021 ◽  
Author(s):  
Xiaoxiao Wang ◽  
Yunlong Xiang ◽  
Yang Yu ◽  
Ran Wang ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Germ Cells ◽  
Pluripotent Stem Cells ◽  
Primordial Germ Cells ◽  
Embryonic Stem ◽  
Large Set ◽  
Mouse Escs ◽  
Epiblast Stem Cells ◽  
Early Gastrula

AbstractThe pluripotency of mammalian early and late epiblast could be recapitulated by naïve embryonic stem cells (ESCs) and primed epiblast stem cells (EpiSCs), respectively. However, these two states of pluripotency may not be sufficient to reflect the full complexity and developmental potency of the epiblast during mammalian early development. Here we report the establishment of self-renewing formative pluripotent stem cells (fPSCs) which manifest features of epiblast cells poised for gastrulation. fPSCs can be established from different mouse ESCs, pre-/early-gastrula epiblasts and induced PSCs. Similar to pre-/early-gastrula epiblasts, fPSCs show the transcriptomic features of formative pluripotency, which are distinct from naïve ESCs and primed EpiSCs. fPSCs show the unique epigenetic states of E6.5 epiblast, including the super-bivalency of a large set of developmental genes. Just like epiblast cells immediately before gastrulation, fPSCs can efficiently differentiate into three germ layers and primordial germ cells (PGCs) in vitro. Thus, fPSCs highlight the feasibility of using PSCs to explore the development of mammalian epiblast.

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