scholarly journals Epigenetic reprogramming during early development in mammals

Reproduction ◽  
2004 ◽  
Vol 127 (6) ◽  
pp. 643-651 ◽  
Author(s):  
Fátima Santos ◽  
Wendy Dean
Keyword(s):  
Dna Methylation ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Epigenetic Reprogramming ◽  
Epigenetic Alterations ◽  
Chromatin Organisation ◽  
Genomic Imprints ◽  
Genomic Regions ◽  
Derivatives Of

Epigenetic modifications serve as an extension of the information content by which the underlying genetic code may be interpreted. These modifications mark genomic regions and act as heritable and stable instructions for the specification of chromatin organisation and structure that dictate transcriptional states. In mammals, DNA methylation and the modification of histones account for the major epigenetic alterations. Two cycles of DNA methylation reprogramming have been characterised. During germ cell development, epigenetic reprogramming of DNA methylation resets parent-of-origin based genomic imprints and restores totipotency to gametes. On fertilisation, the second cycle is triggered resulting in an asymmetric difference between parental genomes. Further epigenetic asymmetry is evident in the establishment of the first two lineages at the blastocyst stage. This differentiative event sets the epigenetic characteristics of the lineages as derivatives of the inner cell mass (somatic) and trophectoderm (extra-embryonic). It is the erasure and subsequent re-tracing of the epigenetic checkpoints that pose the most serious obstacles to somatic nuclear transfer. Elaboration of the mechanisms of these interactions will be invaluable in our fundamental understanding of biological processes and in achieving substantial therapeutic advances.

scholarly journals DNA methylation pattern in human zygotes and developing embryos

Reproduction ◽  
2004 ◽  
Vol 128 (6) ◽  
pp. 703-708 ◽  
Author(s):  
Helena Fulka ◽  
Milan Mrazek ◽  
Olga Tepla ◽  
Josef Fulka
Keyword(s):  
Dna Methylation ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Methylation Pattern ◽  
Blastocyst Stage ◽  
The Other ◽  
Cell Stage ◽  
Global Methylation ◽  
Early Embryos ◽  
Human Zygotes

We report on observations of the global methylation/demethylation pattern of both pronuclei in human zygotes and in early embryos up to the blastocyst stage. Our results demonstrate that in about half of the zygotes examined the paternal chromatin was less methylated than the maternal chromatin. In the other half, both pronuclei exhibited the same intensity of labeling. The nuclei in developing embryos were intensively labeled for up to the four-cell stage; thereafter, a decline of labeling intensity was detected. Remethylation in some nuclei starts in late morulae. Surprisingly, and unlike the mouse, at the blastocyst stage the inner cell mass showed a weaker intensity of labeling than the trophectodermal cells.

scholarly journals Position- and Hippo signaling-dependent plasticity during lineage segregation in the early mouse embryo

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Eszter Posfai ◽  
Sophie Petropoulos ◽  
Flavia Regina Oliveira de Barros ◽  
John Paul Schell ◽  
Igor Jurisica ◽  
...  
Keyword(s):  
Gene Expression ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Global Gene Expression ◽  
Blastocyst Stage ◽  
Egfp Expression ◽  
Hippo Signaling ◽  
Ability To Regenerate ◽  
Early Mouse ◽  
Cell Commitment

The segregation of the trophectoderm (TE) from the inner cell mass (ICM) in the mouse blastocyst is determined by position-dependent Hippo signaling. However, the window of responsiveness to Hippo signaling, the exact timing of lineage commitment and the overall relationship between cell commitment and global gene expression changes are still unclear. Single-cell RNA sequencing during lineage segregation revealed that the TE transcriptional profile stabilizes earlier than the ICM and prior to blastocyst formation. Using quantitative Cdx2-eGFP expression as a readout of Hippo signaling activity, we assessed the experimental potential of individual blastomeres based on their level of Cdx2-eGFP expression and correlated potential with gene expression dynamics. We find that TE specification and commitment coincide and occur at the time of transcriptional stabilization, whereas ICM cells still retain the ability to regenerate TE up to the early blastocyst stage. Plasticity of both lineages is coincident with their window of sensitivity to Hippo signaling.

The human blastocyst: cell number, death and allocation during late preimplantation development in vitro

Development ◽  
1989 ◽  
Vol 107 (3) ◽  
pp. 597-604 ◽  
Author(s):  
K. Hardy ◽  
A.H. Handyside ◽  
R.M. Winston
Keyword(s):  
Cell Death ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Human Embryos ◽  
Cell Numbers ◽  
Human Blastocyst ◽  
Development In Vitro

The development of 181 surplus human embryos, including both normally and abnormally fertilized, was observed from day 2 to day 5, 6 or 7 in vitro. 63/149 (42%) normally fertilized embryos reached the blastocyst stage on day 5 or 6. Total, trophectoderm (TE) and inner cell mass (ICM) cell numbers were analyzed by differential labelling of the nuclei with polynucleotide-specific fluorochromes. The TE nuclei were labelled with one fluorochrome during immunosurgical lysis, before fixing the embryo and labelling both sets of nuclei with a second fluorochrome (Handyside and Hunter, 1984, 1986). Newly expanded normally fertilized blastocysts on day 5 had a total of 58.3 +/− 8.1 cells, which increased to 84.4 +/− 5.7 and 125.5 +/− 19 on days 6 and 7, respectively. The numbers of TE cells were similar on days 5 and 6 (37.9 +/− 6.0 and 40.3 +/− 5.0, respectively) and then doubled on day 7 (80.6 +/− 15.2). In contrast, ICM cell numbers doubled between days 5 and 6 (20.4 +/− 4.0 and 41.9 +/− 5.0, respectively) and remained virtually unchanged on day 7 (45.6 +/− 10.2). There was widespread cell death in both the TE and ICM as evidenced by fragmenting nuclei, which increased substantially by day 7. These results are compared with the numbers of cells in morphologically abnormal blastocysts and blastocysts derived from abnormally fertilized embryos. The nuclei of arrested embryos were also examined. The number of TE and ICM cells allocated in normally fertilized blastocysts appears to be similar to the numbers allocated in the mouse. Unlike the mouse, however, the proportion of ICM cells remains higher, despite cell death in both lineages.

Developmental expression and cellular localization of glucose transporter molecules during mouse preimplantation development

Development ◽  
1992 ◽  
Vol 115 (1) ◽  
pp. 305-312
Author(s):  
M. Aghayan ◽  
L.V. Rao ◽  
R.M. Smith ◽  
L. Jarett ◽  
M.J. Charron ◽  
...  
Keyword(s):  
Western Blot ◽  
Cellular Localization ◽  
Glucose Transporter ◽  
Developmental Stages ◽  
Molecular Level ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Preimplantation Development ◽  
Developmental Expression

Two general mechanisms mediate glucose transport, one is a sodium-coupled glucose transporter found in the apical border of intestinal and kidney epithelia, while the other is a sodium-independent transport system. Of the latter, several facilitated transporters have been identified, including GLUT1 (erythrocyte/brain), GLUT2 (liver) and GLUT4 (adipose/muscle) isoforms. In this study, we used Western-blot analysis and high resolution immunoelectron microscopy (IEM) to investigate the stage-related expression and cellular localization of GLUT1, 2 and 4. The Western blot results demonstrate that GLUT1 is detectable in the oocyte and throughout preimplantation development. GLUT2 isoforms were not detectable until the blastocyst stage, while the GLUT4 isoform was undetectable in the oocyte through blastocyst stages. The present findings confirm previous studies at the molecular level which demonstrated that mRNAs encoding the same GLUT isoforms are detectable at corresponding developmental stages. GLUT1 and GLUT2 display different cellular distributions at the blastocyst stage as shown by IEM studies. GLUT1 has a widespread distribution in both trophectoderm and inner cell mass cells, while GLUT2 is located on trophectoderm membranes facing the blastocyst cavity. This observation suggests a different functional significance for these isoforms during mouse preimplantation development.

Nuclear transplantation of male primordial germ cells in the mouse

Development ◽  
1989 ◽  
Vol 107 (2) ◽  
pp. 407-411 ◽  
Author(s):  
Y. Tsunoda ◽  
T. Tokunaga ◽  
H. Imai ◽  
T. Uchida
Keyword(s):  
Germ Cells ◽  
Inner Cell Mass ◽  
Primordial Germ Cells ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Nuclear Transplantation ◽  
Embryonic Genome ◽  
Donor Nucleus ◽  
Implantation Sites ◽  
Genome Activation

We examined the developmental ability of enucleated eggs receiving embryonic nuclei and male primordial germ cells (PGCs) in the mouse. Reconstituted eggs developed into the blastocyst stage only when an earlier 2-cell nucleus was transplanted (36%) but very rarely if the donor nucleus was derived from a later 2-cell, 8-cell, or inner cell mass of a blastocyst (0–3%). 54–100%, 11–67%, 6–43% and 6–20% of enucleated eggs receiving male PGCs developed to 2-cell, 4-cell, 8-cell and blastocyst stage, respectively, in culture. The overall success rate when taking into account the total number of attempts at introducing germ cells was actually 0–6%. Live fetuses were not obtained after transfer of reconstituted eggs to recipients, although implantation sites were observed. The developmental ability of reconstituted eggs in relation to embryonic genome activation and genomic imprinting is discussed.

scholarly journals Lipid Stores and Lipid Metabolism Associated Gene Expression in Porcine and Bovine Parthenogenetic Embryos Revealed by Fluorescent Staining and RNA-seq

2020 ◽  
Vol 21 (18) ◽  
pp. 6488
Author(s):  
Arkadiusz Kajdasz ◽  
Ewelina Warzych ◽  
Natalia Derebecka ◽  
Zofia E. Madeja ◽  
Dorota Lechniak ◽  
...  
Keyword(s):  
Gene Expression ◽  
Lipid Metabolism ◽  
Inner Cell Mass ◽  
Mammalian Species ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Rna Seq ◽  
Expression Of Genes ◽  
Bovine Blastocyst

Compared to other mammalian species, porcine oocytes and embryos are characterized by large amounts of lipids stored mainly in the form of droplets in the cytoplasm. The amount and the morphology of lipid droplets (LD) change throughout the preimplantation development, however, relatively little is known about expression of genes involved in lipid metabolism of early embryos. We compared porcine and bovine blastocyst stage embryos as well as dissected inner cell mass (ICM) and trophoblast (TE) cell populations with regard to lipid droplet storage and expression of genes functionally annotated to selected lipid gene ontology terms using RNA-seq. Comparing the number and the volume occupied by LD between bovine and porcine blastocysts, we have found significant differences both at the level of single embryo and a single blastomere. Aside from different lipid content, we found that embryos regulate the lipid metabolism differentially at the gene expression level. Out of 125 genes, we found 73 to be differentially expressed between entire porcine and bovine blastocyst, and 36 and 51 to be divergent between ICM and TE cell lines. We noticed significant involvement of cholesterol and ganglioside metabolism in preimplantation embryos, as well as a possible shift towards glucose, rather than pyruvate dependence in bovine embryos. A number of genes like DGAT1, CD36 or NR1H3 may serve as lipid associated markers indicating distinct regulatory mechanisms, while upregulated PLIN2, APOA1, SOAT1 indicate significant function during blastocyst formation and cell differentiation in both models.

scholarly journals Trophoblast-specific DNA methylation occurs after the segregation of the trophectoderm and inner cell mass in the mouse periimplantation embryo

Epigenetics ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. 173-182 ◽  
Author(s):  
Momo O. Nakanishi ◽  
Koji Hayakawa ◽  
Kazuhiko Nakabayashi ◽  
Kenichiro Hata ◽  
Kunio Shiota ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Inner Cell Mass ◽  
Cell Mass

Defects in the allocation of cells to the inner cell mass and trophectoderm of parthenogenetic mouse blastocysts

1996 ◽  
Vol 8 (8) ◽  
pp. 1193 ◽  
Author(s):  
B Mognetti ◽  
D Sakkas
Keyword(s):  
Inner Cell Mass ◽  
Cell Mass ◽  
Substantial Reduction ◽  
Cell Lineage ◽  
Blastocyst Stage ◽  
Trophectoderm Cells ◽  
Parthenogenetic Development ◽  
Preimplantation Stage ◽  
Parthenogenetic Mouse Embryos ◽  
Parthenogenetic Embryos

Diploid parthenogenetic mouse embryos (which possess two maternally-derived genomes) can develop only as far as the 25-somite stage when transferred in utero and exhibit a substantial reduction in trophoblast tissue. The loss of cultured parthenogenetic embryos during postimplantation indicates that a defect in cell lineage may be evident as early as the blastocyst stage. The possibility that a defect may already be reflected at the preimplantation stage was investigated by examining the allocation of cells to the trophectoderm (trophoblast progenitor cells) and the inner cell mass of haploid and diploid parthenogenetic mouse blastocysts. Utilizing a differential labelling technique for counting cells, diploid parthenogenetic blastocysts were found to have fewer inner cell mass cells and trophectoderm cells than their haploid counterparts and normal blastocysts. In addition, both haploid and diploid parthenogenetic blastocysts had a lower inner cell mass: trophectoderm ratio than normal blastocysts. Thus, the relatively poor development of the trophectoderm lineage at the postimplantation stage is not reflected by a reduction in its allotment of cells at its first appearance. Nevertheless, the findings indicate that parthenogenetic development is already compromised at the blastocyst stage, and provide evidence that the expression of imprinted genes has significance for the development of the embryo at the preimplantation stage.

104 BIRTH OF FIRST BUFFALO (BUBALUS BUBALS) CALF FOLLOWING EMBRYO SPLITTING AND POLYMERASE CHAIN REACTION SEXING AT BLASTOCYST STAGE

2012 ◽  
Vol 24 (1) ◽  
pp. 164 ◽  
Author(s):  
M. Zhang ◽  
H. H. Chen ◽  
J. W. Tang ◽  
X. W. Liang ◽  
M. T. Chen ◽  
...  
Keyword(s):  
Nested Pcr ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Blastocyst Stage ◽  
Buffalo Calf ◽  
Practical Procedure ◽  
Blastocyst Quality ◽  
Grade 3 ◽  
Vitro Development

Embryo-splitting technology provides an effective procedure for increasing the number of transferable embryos per donor, producing genetically identical offspring and facilitating embryo sexing. The ability to identify the sex of embryos before transfer will offer a reliable, economical and practical procedure for buffalo breeding. In this study, we have assessed the feasibility of production of offspring with controlled sex in buffalo by first comparing the effect of blastocyst quality on the viability of demi-embryos and then identifying the sex of a demi-embryo by multiplex-nested PCR before transfer into the recipient. In vitro-matured buffalo oocytes were fertilized by IVF and cultured to the blastocyst stage for 6 to 7 days as described by Lu et al. (2007 Anim. Reprod. Sci. 100, 192–196). These blastocysts were classified in terms of their developmental pattern and morphology on a scale of 1 to 3 grades as described by McEvoy et al. (1990 Theriogenology 33, 1245–1253). Blastocysts were split into 2 equal parts by a micromanipulation system. Viability of the resulting demi-embryos was confirmed by formation of a blastocoel cavity and definite inner cell mass after culture for 24 h. One of the zone-free demi-embryos derived from a grade-1 blastocyst was cultured in TCM 199 supplemented with 10% fetal bovine serum for another 2 h, then was transplanted to a spontaneous oestrous recipient. The other demi-embryo was used for sexing by multiplex-nested PCR (Fu et al. 2007 Theriogenology 68, 1211–1218). The results showed that grade-1 blastocysts yielded more viable demi-embryos than grade-2 and grade-3 blastocysts [P < 0.01; 73/92 (79.67%) vs 32/76 (47.05%) vs 26/94 (26.53%), respectively]. Transplantation of the presumed-Y demi-embryo derived from grade-1 blastocyst into a recipient resulted in the birth of a male buffalo calf. To the best of our knowledge, this is the first buffalo calf produced following embryo splitting and PCR sexing of the embryo at the blastocyst stage. Successful birth of the desired-sex offspring in the present study indicates the feasibility of using embryo splitting in combination with multiplex-nested PCR sexing to produce offspring of controlled sex in swamp buffalo. However, the quality of embryos before splitting was an important factor governing the in vitro development of viable demi-embryos. This study was supported by the Guangxi Science and Technology R&D Program (0626001-3-1, 0815008-2-4).

155 CHARACTERIZATION OF LIPID DROPLETS IN BOS INDICUS AND BOS TAURUS EMBRYOS

2013 ◽  
Vol 25 (1) ◽  
pp. 226 ◽  
Author(s):  
E. P. López-Damián ◽  
T. Fiordelisio ◽  
M. A. Lammoglia ◽  
M. Alarcón ◽  
M. Asprón ◽  
...  
Keyword(s):  
Lipid Droplets ◽  
Embryo Quality ◽  
Developmental Stages ◽  
Bos Taurus ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Bos Indicus ◽  
Nile Red ◽  
Blastocyst Stage ◽  
Transfer Program

Accurate evaluation of bovine embryos for assessing developmental stage and quality is critical to the success of any embryo transfer program. However, this evaluation process has been reported to be highly subjective in Bos indicus (BI) and can vary as much as 23% compared with that of Bos taurus (BT). These differences in assessment may be related to the quantity of lipid droplets (LD) within the embryo, which has been shown to have a negative effect in cryopreserving embryos. The aim of the present study was to characterize the number and size of LD in different developmental stages of fresh embryos from BI and BT and to compare LD across the three different embryo quality grades (1 = excellent or good, 2 = fair, and 3 = poor). Nonsurgical embryo collection was performed 7 days post-insemination in 10 BI and 10 BT females. Forty-eight embryos were evaluated for stage and grade using stereoscopic microscopy, processed for transmission electron microscopy, and stained with Nile red. Digitalized images were analyzed with ImageJ (National Institutes of Health, Bethesda, MD, USA), contour of lipid droplets were designed, and values of perimeter, area, and fluorescence intensity were assessed. Nonparametric statistical analysis (Mann–Whitney) was utilized. There was no difference in LD number for BT or BI for morulae and blastocyst; however, BI morulae presented larger LD compared with blastocyst stage embryos (286 µm2 v. 223 µm2; P < 0.05). Likewise, BI TF cells had more LD compared with inner cell mass (ICM) cells (48 v. 36; P < 0.05). BT TF cells exhibited larger LD compared with ICM cells (149 µm2 v. 128 µm2; P < 0.05), while BI embryos exhibited a larger area of LD in the ICM compared with the TF (591 µm2 v. 472 µm2; P < 0.05). In all embryos, BI contained more lipid droplets than BT (78 v. 49; P < 0.05). Across all quality grades (good, fair, and poor) there was no difference in the number of LD in BT embryos; however, BI grade-3 embryos presented more LD than grade-1 (36 v. 25). BT embryos LD were larger than BI LD (907 µm2 v. 625 µm2; P < 0.05). Fluorescence images showed higher arbitrary units of fluorescence (auf) for LD in BI. Compared with BT embryos (386 auf v. 280 auf; P < 0.05). These results suggest that BI embryos contain more and smaller LD than BT embryos and the LD described for BI embryo quality grade 1 are larger than those of quality grades 2 and 3, and even though the number of LD in morulae and blastocyst stage embryos are not different LD size is reduced as development occurs. Research funding provided by UNAM-DGAPA-PAPIIT IN200810.

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