Regional specification within the mesoderm of early embryos of Xenopus laevis

Development ◽  
1987 ◽  
Vol 100 (2) ◽  
pp. 279-295 ◽  
Author(s):  
L. Dale ◽  
J.M. Slack
Keyword(s):  
Xenopus Laevis ◽  
Marginal Zone ◽  
Mesoderm Induction ◽  
Intermediate Type ◽  
Cell Stage ◽  
Early Embryos ◽  
Significant Difference ◽  
Cell Embryo ◽  
Single Blastomeres

We have further analysed the roles of mesoderm induction and dorsalization in the formation of a regionally specified mesoderm in early embryos of Xenopus laevis. First, we have examined the regional specificity of mesoderm induction by isolating single blastomeres from the vegetalmost tier of the 32-cell embryo and combining each with a lineage-labelled (FDA) animal blastomere tier. Whereas dorsovegetal (D1) blastomeres induce ‘dorsal-type’ mesoderm (notochord and muscle), laterovegetal and ventrovegetal blastomeres (D2–4) induce either ‘intermediate-type’ (muscle, mesothelium, mesenchyme and blood) or ‘ventral-type’ (mesothelium, mesenchyme and blood) mesoderm. No significant difference in inductive specificity between blastomeres D2, 3 and 4 could be detected. We also show that laterovegetal and ventrovegetal blastomeres from early cleavage stages can have a dorsal inductive potency partially activated by operative procedures, resulting in the induction of intermediate-type mesoderm. Second, we have determined the state of specification of ventral blastomeres by isolating and culturing them in vitro between the 4-cell stage and the early gastrula stage. The majority of isolates from the ventral half of the embryo gave extreme ventral types of differentiation at all stages tested. Although a minority of cases formed intermediate-type and dorsal-type mesoderms we believe these to result from either errors in our assessment of the prospective DV axis or from an enhancement, provoked by microsurgery, of some dorsal inductive specificity. The results of induction and isolation experiments suggest that only two states of specification exist in the mesoderm of the pregastrula embryo, a dorsal type and a ventral type. Finally we have made a comprehensive series of combinations between different regions of the marginal zone using FDA to distinguish the components. We show that, in combination with dorsal-type mesoderm, ventral-type mesoderm becomes dorsalized to the level of intermediate-type mesoderm. Dorsal-type mesoderm is not ventralized in these combinations. Dorsalizing activity is confined to a restricted sector of the dorsal marginal zone, it is wider than the prospective notochord and seems to be graded from a high point at the dorsal midline. The results of these experiments strengthen the case for the three-signal model proposed previously, i.e. dorsal and ventral mesoderm inductions followed by dorsalization, as the simplest explanation capable of accounting for regional specification within the mesoderm of early Xenopus embryos.

Mesoderm induction by fibroblast growth factor in early Xenopus development

1990 ◽  
Vol 327 (1239) ◽  
pp. 75-84 ◽  
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Marginal Zone ◽  
Mesoderm Induction ◽  
Fibroblast Growth ◽  
Heparin Binding ◽  
Cell Stage ◽  
Animal Pole

In early amphibian development the mesoderm is formed around the equator of the blastula in response to inductive signals from the endoderm. At the time of its formation the mesoderm consists of a large ‘ventral type’ zone and a small ‘organizer’ zone. A screen of candidate substances showed that a small group of heparin binding growth factors (HBGFs) were active as mesoderm inducing agents in vitro . The fibroblast growth factors (aFGF and bFGF) and embryonal carcinoma derived growth factor (ECDGF) all show similar potency and can produce ventral inductions at concentrations above about 100 pM. Single blastula ectoderm cells can be induced and will differentiate in a defined medium to form mesodermal tissues and all inner blastula cells are competent to respond to the factors. Inducing activity can be extracted from Xenopus blastulae and can be purified by heparin affinity chromatography. Antibody neutralization and Western blotting experiments identify this activity as bFGF. The amounts present are small but would be sufficient to evoke ventral inductions in vivo. It is not yet known whether the bFGF is localized to the endoderm, although it is known that inducing activity secreted by endodermal cells can be neutralized by heparin. The competence of ectoderm to respond to FGF rises from about the 128-cell-stage and falls again by the onset of gastrulation. This change is paralleled by a rise and fall of binding of 125I-labelled aFGF. Chemical cross-linking reveals that this binding is attributable to a receptor of molecular mass about 130 kilodaltons (kDa). The receptor is present both in the marginal zone, which responds to the signal in vivo, and in the animal pole region, which is not induced in vivo but which will respond to HBGFs in vitro . In intact embryos we believe that the ventral type mesoderm forms the somites, kidney and other intermediate structures as well as the blood islands of the ventral midline. These intermediate structures are induced as a function of distance from the organizer in a process called ‘dorsalization’. Lithium salts have a dorsalizing effect on whole embryos and also on explants from the ventral marginal zone, causing them to form large blocks of muscle. Lithium will also cause large muscle blocks to form when applied to ectoderm explants together with FGF. It is difficult to extend these results directly to mammalian embryos, but we have shown that the products of the murine int-2 gene and of the human k-fgf genes are active as mesoderm inducing factors.

scholarly journals Totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marino Maemura ◽  
Hiroaki Taketsuru ◽  
Yuki Nakajima ◽  
Ruiqi Shao ◽  
Ayaka Kakihara ◽  
...  
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Mouse Embryos ◽  
Primitive Endoderm ◽  
Cell Stage ◽  
Supportive Environment ◽  
Mouse Zygotes ◽  
Single Blastomeres ◽  
Multicellular Organisms

AbstractIn multicellular organisms, oocytes and sperm undergo fusion during fertilization and the resulting zygote gives rise to a new individual. The ability of zygotes to produce a fully formed individual from a single cell when placed in a supportive environment is known as totipotency. Given that totipotent cells are the source of all multicellular organisms, a better understanding of totipotency may have a wide-ranging impact on biology. The precise delineation of totipotent cells in mammals has remained elusive, however, although zygotes and single blastomeres of embryos at the two-cell stage have been thought to be the only totipotent cells in mice. We now show that a single blastomere of two- or four-cell mouse embryos can give rise to a fertile adult when placed in a uterus, even though blastomere isolation disturbs the transcriptome of derived embryos. Single blastomeres isolated from embryos at the eight-cell or morula stages and cultured in vitro manifested pronounced defects in the formation of epiblast and primitive endoderm by the inner cell mass and in the development of blastocysts, respectively. Our results thus indicate that totipotency of mouse zygotes extends to single blastomeres of embryos at the four-cell stage.

Misexpression of chick Vg1 in the marginal zone induces primitive streak formation

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 5127-5138 ◽  
Author(s):  
S.B. Shah ◽  
I. Skromne ◽  
C.R. Hume ◽  
D.S. Kessler ◽  
K.J. Lee ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Ectopic Expression ◽  
Primitive Streak ◽  
Axis Formation ◽  
Mesoderm Induction ◽  
Cell Fates ◽  
Signalling Molecules ◽  
Posterior Area ◽  
Area Pellucida

In the chick embryo, the primitive streak is the first axial structure to develop. The initiation of primitive streak formation in the posterior area pellucida is influenced by the adjacent posterior marginal zone (PMZ). We show here that chick Vg1 (cVg1), a member of the TGFbeta family of signalling molecules whose homolog in Xenopus is implicated in mesoderm induction, is expressed in the PMZ of prestreak embryos. Ectopic expression of cVg1 protein in the marginal zone chick blastoderms directs the formation of a secondary primitive streak, which subsequently develops into an ectopic embryo. We have used cell marking techniques to show that cells that contribute to the ectopic primitive streak change fate, acquiring two distinct properties of primitive streak cells, defined by gene expression and cell movements. Furthermore, naive epiblast explants exposed to cVg1 protein in vitro acquire axial mesodermal properties. Together, these results show that cVg1 can mediate ectopic axis formation in the chick by inducing new cell fates and they permit the analysis of distinct events that occur during primitive streak formation.

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.

scholarly journals Xenopus embryonic cell adhesion to fibronectin: position-specific activation of RGD/synergy site-dependent migratory behavior at gastrulation.

1996 ◽  
Vol 134 (1) ◽  
pp. 227-240 ◽  
Author(s):  
J W Ramos ◽  
D W DeSimone
Keyword(s):  
Cell Adhesion ◽  
Matrix Protein ◽  
Marginal Zone ◽  
Cell Attachment ◽  
Extracellular Matrix Protein ◽  
Mesoderm Induction ◽  
Type Iii ◽  
Basic Body ◽  
And Migration

During Xenopus laevis gastrulation, the basic body plan of the embryo is generated by movement of the marginal zone cells of the blastula into the blastocoel cavity. This morphogenetic process involves cell adhesion to the extracellular matrix protein fibronectin (FN). Regions of FN required for the attachment and migration of involuting marginal zone (IMZ) cells were analyzed in vitro using FN fusion protein substrates. IMZ cell attachment to FN is mediated by the Arg-Gly-Asp (RGD) sequence located in the type III-10 repeat and by the Pro-Pro-Arg-Arg-Ala-Arg (PPRRAR) sequence in the type III-13 repeat of the Hep II domain. IMZ cells spread and migrate persistently on fusion proteins containing both the RGD and synergy site sequence Pro-Pro-Ser-Arg-Asn (PPSRN) located in the type III-9 repeat. Cell recognition of the synergy site is positionally regulated in the early embryo. During gastrulation, IMZ cells will spread and migrate on FN whereas presumptive pre-involuting mesoderm, vegetal pole endoderm, and animal cap ectoderm will not. However, animal cap ectoderm cells acquire the ability to spread and migrate on the RGD/synergy region when treated with the mesoderm inducing factor activin-A. These data suggest that mesoderm induction activates the position-specific recognition of the synergy site of FN in vivo. Moreover, we demonstrate the functional importance of this site using a monoclonal antibody that blocks synergy region-dependent cell spreading and migration on FN. Normal IMZ movement is perturbed when this antibody is injected into the blastocoel cavity indicating that IMZ cell interaction with the synergy region is required for normal gastrulation.

The effects of brain-derived neurotrophic factor and metformin on in vitro developmental competence of bovine oocytes

Zygote ◽  
2009 ◽  
Vol 17 (3) ◽  
pp. 187-193 ◽  
Author(s):  
So Gun Hong ◽  
Goo Jang ◽  
Hyun Ju Oh ◽  
Ok Jae Koo ◽  
Jung Eun Park ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Embryo Development ◽  
Neurotrophic Factor ◽  
Brain Derived Neurotrophic Factor ◽  
Early Embryo ◽  
Developmental Competence ◽  
Blastocyst Development ◽  
Cell Stage ◽  
Significant Difference

SummaryBrain-derived neurotrophic factor (BDNF) signalling via tyrosine kinase B receptors may play an important role in ovarian development and function. It has been reported that metformin elevates the activity of Tyrosine kinase receptors and may amplify BDNF signalling. The objective of this study was to investigate the effect of BDNF during in vitro maturation (IVM) and/or in vitro culture (IVC) (Experiment 1), and to evaluate the collaborative effect of BDNF and metformin treatment on the developmental competence of bovine in vitro fertilized (IVF) embryos (Experiment 2). In Experiment 1, BDNF, which was added to our previously established IVM systems, significantly increased the proportions of MII oocytes at both 10 ng/ml (86.7%) and 100 ng/ml (85.4%) compared with the control (64.0%). However, there was no statistically significant difference in blastocyst development between the control or BDNF-supplemented groups. In Experiment 2, in order to investigate the effect of BDNF (10 ng/ml) and/or metformin (10−5 M) per se, TCM-199 without serum and hormones was used as the control IVM medium. The BDNF (48.3%) and BDNF plus metformin (56.5%) significantly enhanced the proportions of MII oocytes compared with the control (34.4%). Although, BDNF or metformin alone had no effect in embryo development, BDNF plus metformin significantly improved early embryo development to the 8–16-cell stage compared with the control (16.5 vs. 5.5%). In conclusion, the combination of BDNF and metformin may have a collaborative effect during the IVM period. These results could further contribute to the establishment of a more efficient bovine in vitro embryo production system.

The role of fibroblast growth factor in early Xenopus development

Development ◽  
1989 ◽  
Vol 107 (Supplement) ◽  
pp. 141-148 ◽  
Author(s):  
J. M. W. Slack ◽  
B. G. Darlington ◽  
L. L. Gillespie ◽  
S. F. Godsave ◽  
H. V. Isaacs ◽  
...  
Keyword(s):  
Marginal Zone ◽  
Specific Activity ◽  
Progressive Increase ◽  
Defined Medium ◽  
Relative Molecular Mass ◽  
Heparin Binding ◽  
Cell Stage ◽  
Animal Pole

In early amphibian development, the mesoderm is formed around the equator of the blastula in response to an inductive signal from the endoderm. A screen of candidate substances showed that a small group of heparin-binding growth factors (HBGFs) were active as mesoderm-inducing agents in vitro. The factors aFGF, bFGF, kFGF and ECDGF all show similar potency and can produce inductions at concentrations above about 100 pM. The product of the murine int-2 gene is also active, but with a lower specific activity. Above the induction threshold there is a progressive increase of muscle formation with dose. Single blastula ectoderm cells can be induced and will differentiate in a defined medium to form mesodermal tissues. All inner blastula cells are competent to respond to the factors but outer cells, bearing oocyte-derived membrane, are not. Inducing activity can be extracted from Xenopus blastulae and binds to heparin like the previously described HBGFs. Antibody neutralization and Western blotting experiments identify this activity as bFGF. The amounts present are small but would be sufficient to evoke inductions in vivo. It is not yet known whether the bFGF is localized to the endoderm, although it is known that inducing activity secreted by endodermal cells can be neutralized by heparin. The competence of ectoderm to respond to HBGFs rises from about the 128-cell stage and falls again by the onset of gastrulation. This change is paralleled by a rise and fall of binding of 125I-aFGF. Chemical cross-linking reveals that this binding is attributable to a receptor of relative molecular mass about 130 × 103. The receptor is present both in the marginal zone, which responds to the signal in vivo, and in the animal pole region, which is not induced in vivo but which will respond to HBGFs in vitro. In the embryo, the induction in the vicinity of the dorsal meridian is much more potent than that around the remainder of the marginal zone circumference. Dorsal inductions contain notochord and will dorsalize ventral mesoderm with which they are later placed in contact. This effect might be due to a local high bFGF concentration or, more likely, to the secretion in the dorsal region of an additional, synergistic factor. It is known that TGF-β-1 and -2 can greatly increase the effect of low doses of bFGF, although it has not yet been demonstrated that they are present in the embryo. Lithium salts have a dorsalizing effect on whole embryos or on explants from the ventral marginal zone, and also show potent synergism when applied together with HBGFs.

scholarly journals 81 EFFECT OF SUCROSE CONCENTRATION IN WARMING MEDIUM ON THE DEVELOPMENT POTENTIAL OF VITRIFIED BOVINE OOCYTES

2005 ◽  
Vol 17 (2) ◽  
pp. 190
Author(s):  
W.C. Chang ◽  
J. Xu ◽  
S. Jiang ◽  
X.C. Tian ◽  
X. Yang ◽  
...  
Keyword(s):  
Sucrose Concentration ◽  
Control Group ◽  
Bovine Oocyte ◽  
Cell Stage ◽  
Significant Difference ◽  
Humidified Air ◽  
Bovine Oocytes ◽  
Experimental Group ◽  
One Way Anova

The aim of this experiment was to determine the effect of the sucrose concentration (0 to 0.33 M) in the dilution medium on the viability, fertilizability, and development of vitrified bovine oocytes. Bovine oocyte-cumulus complexes were collected from slaughterhouse ovaries and in vitro-matured as reported previously. After 24-h maturation in TCM199-based medium under 5% CO2 humidified air at 39°C, these were exposed to hyaluronidase and carefully pipetted to remove all except the 3–5 innermost layers of cumulus. Oocytes were put into the pre-equilibration medium for 3 min and then into vitrification solution containing HEPES-buffered TCM199 supplemented with 20% FBS, ethylene glycol, and dimethylsulphoxide for 25–30 s; they were then vitrified by modified solid surface vitrification (Dinnyes et al. 2000 Biol. Reprod. 63, 513–518).The oocytes were warmed at 39°C by placing them in holding medium with 0, 0.08, 0.17, 0.25, or 0.33 M sucrose. Non-vitrified oocytes were used as controls. Oocytes were inseminated 30 min after warming, and the presumptive zygotes were cultured in CR1-aa medium supplemented with 6 mg/mL BSA at 39°C in a humidified atmosphere of 5% CO2, 5% O2, and 90% N2 for eight days. Data were analyzed by one-way ANOVA. As shown in Table 1, there was no significant difference in survival rate (P > 0.05) of the vitrified oocytes that were placed in dilution solution containing 0.17, 0.25, or 0.33 M sucrose and the non-treated controls. On Day 2 (fertilized on Day 0), cleavage to the 8-cell stage was similar for the 0.17, 0.25, and 0.33 M dilution groups, but the rates for all three were significantly lower (P < 0.05) than for the control group. The blastocyst rate on Day 8 was significantly higher for the 0.25 M group than for any other experimental group but still significantly lower than for the control. In conclusion, this study suggests that with this vitrification/warming procedure the optimum concentration of sucrose in the dilution solution is 0.25 M. Table 1. Oocyte survival after vitrification/warming and subsequent embryo development The authors would like to thank Ms Colleen Shaffer for the preparation of bovine oocytes.

193 DIFFERENTIAL EFFECTS OF CULTURE ON APOPTOTIC GENE EXPRESSION IN THE PRE-IMPLANTATION CLONED EMBRYOS OF MINIATURE PIG

2007 ◽  
Vol 19 (1) ◽  
pp. 213
Author(s):  
M. R. Park ◽  
I. S. Hwang ◽  
H. J. Moon ◽  
J. H. Shim ◽  
D. H. Kim ◽  
...  
Keyword(s):  
Gene Expression ◽  
Relative Abundance ◽  
Total Concentration ◽  
Control Group ◽  
Specific Cell ◽  
Miniature Pig ◽  
Cell Stage ◽  
Apoptotic Gene ◽  
Early Embryos

Manipulations of early embryos require that the embryos be placed in vitro. The ability to reproduce in vivo conditions in vitro would greatly facilitate studies on the development of early embryos. A variety of different conditions have been described that result in development of pig embryos from the 1-cell stage to the blastocyst stage in vitro. There is a species-specific cell stage at which the early embryo is very sensitive to in vitro conditions, which generally corresponds to the stage at which the embryo begins producing significant amounts of RNA. The present study was conducted to investigate the relative amounts of apoptotic gene expression in miniature pig NT embryos under culture conditions of different osmolarity. Oocytes were cultured in TCM-199 for 40–44 h at 38.5�C under 5% CO2 in air. Miniature pig ear fibroblast cells were cultured to reach confluency, and the culture was continued for an additional 5–6 days. The NaCl group of embryos was cultured in PZM-3 supplemented with 138 mM NaCl in total concentration (280–320 mOsmol) for the first 2 days, and then cultured in PZM-3 (250–270 mOsmol) for a further 4 days. The control group of embryos was cultured in the PZM-3 for the entire period of in vitro culture. Total RNA samples were prepared from 2 blastocysts using the Roche 1st strand cDNA synthesis kit. Bax and Bcl-xl gene expression of blastocysts was analyzed by real-time RT-PCR. Developemntal rates were analyzed by a GLM procedure of SAS (SAS Institute, Inc., Cary, NC, USA). Relative gene expression was compared by Student&apos;s t-test. Blastocyst formation rate in the NaCl group was not different from that in the control group (25.4% and 23.2%, respectively), but the apoptosis rate was significantly lower (P &lt; 0.05) in the NaCl group (1.6%) than in the control (7.1%). The relative abundance of Bax mRNA expression was significantly higher (P &lt; 0.05) in the control group (n = 32) than in the NaCl group (n = 33). However, the relative abundance of Bcl-xl mRNA was significantly higher (P &lt; 0.05) in NaCl group. The relative abundance of Bax/Bcl-xl was significantly higher in the control group than in the NaCl group (P &lt; 0.05). These results indicate that the hypertonic culture condition at the early embryonic stage of miniature pig NT embryos could reduce the frequency of apoptosis through regulating Bax and Bcl-xl gene expression.

Expression of mRNA encoding leukaemia inhibitory factor (LIF) and its receptor (LIFRβ) in buffalo preimplantation embryos produced in vitro: markers of successful embryo implantation

Zygote ◽  
2012 ◽  
Vol 21 (2) ◽  
pp. 203-213 ◽  
Author(s):  
S. Eswari ◽  
G. Sai Kumar ◽  
G. Taru Sharma
Keyword(s):  
Culture Media ◽  
Total Cell ◽  
Inhibitory Factor ◽  
Preimplantation Embryos ◽  
Leukaemia Inhibitory Factor ◽  
Hatching Rate ◽  
Blastocyst Development ◽  
Cell Stage ◽  
Significant Difference

SummaryThe objective of this study was to evaluate the effect of supplementation of recombinant leukaemia inhibitory factor (LIF) in culture media on blastocyst development, total cell number and blastocyst hatching rates and the reverse transcription-polymerase chain reaction analysis of preimplantation buffalo embryos to determine whether they contain the LIF-encoding mRNA and its beta receptor (LIFRβ) genes in different stages of preimplantation buffalo embryos. Cumulus–oocyte complexes retrieved from slaughterhouse buffalo ovaries were matured in vitro and fertilized using frozen buffalo semen. After 18 h of co-incubation with sperm, the presumptive zygotes were cultured in modified synthetic oviductal fluid without (control) or with rhLIF (100 ng/ml). There was no significant difference in the overall cleavage rate up to morula stage however the development of blastocysts, hatching rate and total cell numbers were significantly higher in the LIF-treated group than control. Transcripts for LIFRβ were detected from immature, in vitro-matured oocytes and in the embryos up to blastocyst stage, while transcripts for the LIF were detected from 8–16-cell stage up to blastocyst, which indicated that embryo-derived LIF can act in an autocrine manner on differentiation process and blastocyst formation. This study indicated that the addition of LIF to the embryo culture medium improved development of blastocysts, functional (hatching) and morphological (number of cells) quality of the blastocysts produced in vitro. The stage-specific expression pattern of LIF and LIFRβ mRNA transcripts in buffalo embryos indicated that LIF might play an important role in the preimplantation development and subsequent implantation of buffalo embryos.

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