69 GLOBAL H3k9ac AND H3k27me3 EXPRESSION IN BLASTOMERES FROM 8- TO 16-CELL STAGE BOVINE EMBRYOS

2014 ◽  
Vol 26 (1) ◽  
pp. 148
Author(s):  
C. S. Oliveira ◽  
N. Z. Saraiva ◽  
L. Z. Oliveira ◽  
R. V. Serapião ◽  
M. R. de Lima ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Histone Modifications ◽  
Pearson Correlation ◽  
Developmental Competence ◽  
Bovine Embryos ◽  
Cell Stage ◽  
Embryonic Genome Activation ◽  
Embryonic Genome ◽  
Group A ◽  
Genome Activation

Embryonic genome activation is a crucial step in early embryo development, and is accompanied by a dramatic change in the epigenetic profile of blastomeres. Histone modifications related to euchromatin and heterochromatin can be important parameters to infer developmental competence, as they are affected by manipulation and environmental stress conditions. The aim of this study was to characterise permissive (H3k9ac) and repressive (H3k27me3) histone modifications during the embryonic genome activation cell cycle in bovine embryos, regarding correlation between those marks and variance among blastomeres. For that, bovine embryos were produced by IVF and cultured in SOF medium supplemented with 5 mg mL–1 of BSA and 2.5% FCS in 5% O2 in an air atmosphere for 5 days (70 h after IVF). The 8 to 16 cell embryos were fixed in 4% paraformaldehyde and submitted to H3k9ac and H3k27me3 immunofluorescence assay (mouse anti-H3K9ac monoclonal antibody, 1 : 200; Sigma; rabbit anti-H3k27me3 monoclonal antibody, 1 : 200; Upstate, Charlottesville, VA, USA). Nuclei were counterstained with Hoechst 33342. Images of each embryo were captured (AxioCam, Carl Zeiss, São Paulo, Brazil) and measured for nuclear fluorescence intensity in each blastomere using Adobe Photoshop CS3 (Adobe Systems, San Jose, CA, USA). Mean levels were compared using the Mann-Whitney test and variances were compared using F-test (SAS 9.1, SAS Institute Inc., Cary, NC, USA; P = 0.05). We evaluated 2 replicates and 12 embryos during the transition from the 8 to 16 cell stages, totaling 169 blastomeres. Global H3k27me3 levels varied accordingly to H3k9ac levels, as indicated by a high Pearson correlation coefficient (r = 0.913). Levels of each blastomere were normalized to the lowest level obtained within each embryo. Some embryos displayed a high variation between blastomeres, and, for further analysis, we divided the embryos into groups: group A for embryos that presented similar H3k9ac levels between blastomeres (8 embryos, 66%), and group B for embryos that exhibited higher heterogeneity between blastomeres (at least 2 blastomeres presenting a 2-fold increase compared to the lowest blastomere; 4 embryos, 33%). Mean H3k9ac and H3k27me3 normalized levels were lower for group A [H3k9ac: 1.35 ± 0.29 (A), 1.94 ± 1.02* (B); H3k27me3: 1.33 ± 0.24 (A), 1.99 ± 0.77 (B)], and group A displayed lower variance values (H3k9ac: 0.07 (A), 1.05* (B); H3k27me3: 0.06 (A), 0.60 (B)]. Within each embryo, blastomeres were sorted in ascending order for H3k9ac level (1 to 16), and compared between groups A and B. We detected that mean levels differed (P < 0.05) between groups from blastomere 9 to 16 for H3k9ac and 10 to 16 for H3k27me3. Therefore, in 8- to 16-cell stage embryos, the H3k27me3 repressive mark is highly correlated with the H3k9ac permissive mark. Also, our results describe the presence of 2 distinguishable populations of bovine embryos at this stage, considering their epigenetic status. One population presented similar levels of repressive and permissive marks among blastomeres, whereas the second one displayed a remarkable variation among their blastomeres. This observation should be further studied, as it might reflect distinct cleavage pattern embryos and blastomere competence. The authors acknowledge FAPESP, FAPERJ and CNPq for financial support.

scholarly journals Human embryonic genome activation initiates at the one-cell stage

2021 ◽  
Author(s):  
Maki Asami ◽  
Brian Y.H. Lam ◽  
Marcella K. Ma ◽  
Kara Rainbow ◽  
Stefanie Braun ◽  
...  
Keyword(s):  
Cell Stage ◽  
Embryonic Genome Activation ◽  
Embryonic Genome ◽  
The One ◽  
Genome Activation

61 REVERSIBLE INHIBITION OF BOVINE MINOR EMBRYONIC GENOME ACTIVATION IMPAIRS PRE-IMPLANTATION DEVELOPMENT

2017 ◽  
Vol 29 (1) ◽  
pp. 138
Author(s):  
R. P. Nociti ◽  
R. V. Sampaio ◽  
V. F. M. H. de Lima ◽  
R. M. Schultz ◽  
P. J. Ross
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Reversible Inhibitor ◽  
Blastocyst Formation ◽  
Cell Stage ◽  
Developmental Potential ◽  
Embryonic Genome Activation ◽  
Transcriptional Inhibition ◽  
Embryonic Genome ◽  
Genome Activation

Bovine pre-implantation embryos can develop in the absence of gene expression up to the 8/16-cell stage, the time when the major embryonic genome activation (EGA) occurs. Some embryonic genes, however, are transcribed before EGA (minor EGA). This study used a reversible inhibitor of RNA Polymerase II (5,6 dichlorobenzimidazole 1-β-D-ribofuranoside; DRB) to assess the importance of minor EGA for development to the blastocyst stage. Oocytes were matured and inseminated in vitro, and the fertilized eggs were cultured in supplemented KSOMaa and allocated to different treatments 16 h post-insemination (hpi). Development was recorded at 44 and 72 hpi, and the incidence of blastocyst formation on Day 7 (IVF = Day 0) was recorded. Data were analysed by ANOVA followed by Duncan test. First, we tested different DRB concentrations [50 μM (D50), 75 μM (D75), 100 μM (D100), and dimethyl sulfoxide vehicle control (CTRL)] to block development to blastocyst when continuously present. Only embryos in CTRL produced blastocysts (45.0 ± 5.8%; 4 replicates with a total of 391 oocytes examined). No difference in development was observed at 44 h (57.9 ± 16.5, 53.3 ± 10.5, 60.5 ± 19.0, and 52.3 ± 5.8% for D50, D75, D100, and CTRL, respectively) and 72 h (78.9 ± 8.8, 66.1 ± 11.7, 71.5 ± 16.5, and 70.8 ± 5.6% for D50, D75, D100, and CTRL, respectively). Next, in 7 replicates (751 oocytes) we determined the effect of blocking transcription (50 μM DRB) spanning 2 embryo stages (periods of 28 h), initiated at 16 hpi (1&2C), 30 hpi (2&4C), and 44 hpi (4&8C). Controls included DRB treatment from 16 to 72 hpi (1–8C) and CTRL. There was no difference in development at 44 and 72 h. The incidence of blastocyst formation, however, was significantly decreased in all treatment groups compared with CTRL (27.7 ± 4.7; 15.1 ± 3.5; 23.3 ± 3.1; 20.5 ± 1.9; and 42.1 ± 3.2% for 1&2C, 2&4C, 4&8C, 1–8C, and CTRL, respectively). Finally, in 12 replicates (1499 oocytes), the effect of blocking transcription for 14-h periods, spanning mostly a unique cleavage stage, was evaluated. The DRB treatment (50 μM) started at 16 hpi (1C), 30 hpi (2C), 44 hpi (4C), and 58 hpi (8C). Furthermore, 1–16C and CTRL treatments were included. No difference in development at 44 and 72 h were observed. Development to the blastocyst was significantly lower from CTRL (46.0 ± 3.2%) in 2C, 4C, 8C, and 1–16C (28.9 ± 3.9, 26.1 ± 4.2, 30.1 ± 4.8, and 18.9 ± 3.2%, respectively) but not in 1C (34.7 ± 4.4%). In summary, continuous transcriptional inhibition using DRB resulted in a developmental block at the time of major EGA, similar to α-amanitin treatment (an irreversible RNA Polymerase II inhibitor). Transcriptional inhibition during single cleavage stages was sufficient to decrease the developmental potential of the embryo. We conclude that minor EGA has an important role for bovine development. This work was funded by NIH-NICHD R01HD070044 to P. J. Ross. R. P. Nociti was sponsored by CNPQ; R. V. Sampaio was sponsored by FAPESP.

The role of RNA-polymerase II transcription in embryonic nucleologenesis by bovine embryos

Biologia ◽  
2010 ◽  
Vol 65 (3) ◽  
Author(s):  
Mária Kovalská ◽  
Ida Petrovičová ◽  
František Strejček ◽  
Marian Adamkov ◽  
Erika Halašová ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
De Novo ◽  
Control Group ◽  
Bovine Embryos ◽  
Embryonic Genome Activation ◽  
Embryonic Genome ◽  
Autoradiographic Labeling ◽  
Genome Activation

AbstractThe early stages of embryonic development are maternally driven. As development proceeds, maternally inherited informational molecules decay, and embryogenesis becomes dependent on de novo synthesized RNAs of embryonic genome. The aim of the present study is to investigate the role of de novo transcription in the development of embryos during embryonic genome activation. Autoradiography for detection of transcriptional activity and transmission electron microscopy were applied in in vitro produced bovine embryos cultured to the late 8-cell stage with or without (control group) α-amanitin, specific inhibitor of RNA-polymerases II and III transcription. The α-amanitin (AA) groups presented three sets of embryos cultivated with AA in different time intervals (6, 9 and 12 h). In control group, nucleoplasm and nucleolar structures displayed strong autoradiographic labeling and showed initial development of fibrillo-granular nucleoli. In α-amanitin groups, lack of autoradiographic labeling and disintegrated nucleolus precursor bodies (NPBs) stage were observed. Inhibition of RNA polymerase II (RNA pol II) already in the early phases of embryonic genome activation has detrimental effect on nucleolar formation and embryo survival, what was shown for the first time.

90 TRANSCRIPTION OF USP9Y AND ZFY IN DEVELOPING AND ARRESTED BOVINE EMBRYOS IN VITRO

2013 ◽  
Vol 25 (1) ◽  
pp. 193
Author(s):  
J. Caudle ◽  
C. K. Hamilton ◽  
F. A. Ashkar ◽  
W. A. King
Keyword(s):  
Embryo Development ◽  
Blastocyst Stage ◽  
Early Embryo ◽  
Bovine Embryos ◽  
Cell Stage ◽  
Male Embryo ◽  
Male Development ◽  
Embryonic Genome ◽  
Genome Activation

Sexual dimorphisms such as differences in growth rate and metabolism have been observed in the early embryo, suggesting that sex chromosome-linked gene expression may play an active role in early embryo development. Furthermore, in vitro sex ratios are often skewed toward males, indicating that Y-linked genes may benefit development. While little attention has been paid to the Y chromosome, expression of some Y-linked genes such as SRY and ZFY has been identified in the early embryo, and only a few studies have systematically examined early stages. Identification of transcripts of Y-linked genes in the early embryo may provide insights into male development and provide markers of embryonic genome activation in male embryos. The objectives of this study were i) to examine the timing of transcription of 2 Y chromosome-linked genes involved with sperm production and male development, ubiquitin-specific peptidase 9 (USP9Y) and zinc finger protein (ZFY), in in vitro-produced bovine embryos from the 2-cell stage to the blastocyst stage and ii) to determine if USP9Y and ZFY transcripts are present in in vitro-produced embryos arrested at the 2- to 8-cell stages. To examine the chronology of transcription of these genes, pools of 30 embryos for each developmental stage, 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst, were produced by bovine standard in vitro embryo production (Ashkar et al. 2010 Hum. Reprod. 252, 334–344) using semen from a single bull. Pools of 30 were used to balance sex ratios and to account for naturally arresting embryos. Embryos for each developmental stage were harvested and snap frozen. Total RNA was extracted from each pool, reverse transcribed to cDNA and by using PCR, and transcripts of USP9Y and ZFY were detected as positive or negative. In addition pools of 30 embryos arrested at the 2- to 8-cell stage harvested 7 days after IVF were processed and analysed in the same way to determine if transcripts from the Y chromosomes are present in developmentally arrested embryos. Transcripts of USP9Y and ZFY were detected in the pooled embryos from the 8-cell stage through to the blastocyst stage, but none were detected in the 2-cell or 4-cell pools. Transcripts of ZFY were detected in the arrested 2- to 8-cell embryo pool, but transcripts of USP9Y were not detected. Given that these Y genes begin expression at the 8-cell stage, coincident with embryonic genome activation, it was concluded that these genes may be important for early male embryo development. Furthermore, the results suggest that arrested embryos that have stopped cleaving before the major activation of the embryonic genome are still capable of transcribing at least some of these genes. The absence of USP9Y transcripts in the arrested embryos suggests that it may be important for early male embryo development. Funding was provided by NSERC, the CRC program, and the OVC scholarship program.

77 OVIDUCT - EMBRYO INTERACTIONS: TWO-WAY TRAFFIC OR A ONE-WAY STREET? TRANSCRIPTOMIC RESPONSE OF THE BOVINE OVIDUCT TO THE PRESENCE OF AN EMBRYO

2014 ◽  
Vol 26 (1) ◽  
pp. 152 ◽  
Author(s):  
V. Maillo ◽  
P. O'Gaora ◽  
J. P. Mehta ◽  
C. De Frutos ◽  
N. Forde ◽  
...  
Keyword(s):  
Gene Expression ◽  
Corpus Luteum ◽  
Differential Expression ◽  
Microarray Analysis ◽  
Differentially Expressed ◽  
Cell Stage ◽  
Embryonic Genome Activation ◽  
Embryonic Genome ◽  
Oviduct Epithelium ◽  
Genome Activation

Despite clear evidence of a two-way interaction between the developing conceptus and the uterine endometrium in early pregnancy, the evidence for reciprocal cross-talk during the transit of the embryo through the oviduct is less clear. The aims were (1) to characterise the transcriptome of the bovine oviduct at the initiation of embryonic genome activation (EGA), (2) to examine the effect, if any, of the presence of an embryo on the oviduct transcriptome, and (3) to compare gene expression in the ampulla and isthmus of the oviduct ipsilateral to the corpus luteum. The oestrous cycles of cross-bred beef heifers were synchronized and those recorded in standing oestrus were randomly allocated to control group, nonbred (n = 7), or AI group (n = 11). All heifers were slaughtered on Day 3 after oestrus. The oviducts from each animal were isolated, straightened, and cut in half (ampulla and isthmus). Each portion was flushed with 500 μL of PBS to confirm the presence of an oocyte/embryo and was then opened and scraped longitudinally to obtain epithelial cells. Cells were snap-frozen in liquid nitrogen for microarray analysis. All recovered oocytes and embryos were located in the isthmus of the oviduct ipsilateral to the corpus luteum. The recovery rate was 72.7% (8/11) and 83.3% (5/6) for pregnant and cyclic animals, respectively. The stage of the recovered embryos was as follows: 4-cell stage (n = 1), 8-cell stage (n = 5), and 8–16 cell stage (n = 2), whereas in the cyclic group all recovered structures were unfertilized oocytes. The cells of the isthmus from ipsilateral and contralateral oviducts from 5 cyclic and 5 pregnant animals (8-cell embryos) and the ipsilateral ampulla cells from the pregnant animals were used for microarray analysis (Affymetrix Bovine ST array, Affymetrix, Santa Clara, CA, USA). Array data were analysed using BioConductor packages in R and custom CDF files downloaded from MBNI. Preprocessing of raw data was performed with RMA, and differential expression was assessed by linear modelling implemented in the limma package. Genes displaying P < 0.05 after adjustment for multiple testing were considered differentially expressed. A total of 18 809 probe sets were assessed for differential expression. Comparison of pregnant and cyclic oviduct epithelium revealed no significantly altered genes. However, comparison of the isthmus and ampulla of the ipsilateral oviduct in pregnant animals revealed 4011 (P < 0.05) and 2327 (P < 0.01) differentially expressed genes. Some of the gene ontologies involved in biological processes included fatty acid metabolism, cell adhesion, cell morphogenesis, cellular developmental process, and reproduction. In conclusion, we have characterised the transcriptome of the bovine oviduct epithelium at the initiation of embryonic genome activation on Day 3 post-oestrus in pregnant and cyclic heifers. Although large differences in gene expression were observed between the isthmus and ampulla, data suggest that the presence of an 8-cell embryo had no effect on the transcriptome of the cells of the isthmus, although a local effect at the precise position of the embryo cannot be ruled out.

The stage of embryonic genome activation in bovine embryos following in vitro fertilization

1999 ◽  
Vol 51 (1) ◽  
pp. 188 ◽  
Author(s):  
E-H Park ◽  
R-C Chian ◽  
H-M Chung ◽  
J-G Lim ◽  
J-J Ko ◽  
...  
Keyword(s):  
In Vitro Fertilization ◽  
Bovine Embryos ◽  
Vitro Fertilization ◽  
Embryonic Genome Activation ◽  
Embryonic Genome ◽  
Genome Activation

scholarly journals Preovulatory oocyte aging in mice affects fertilization rate and embryonic genome activation

2017 ◽  
Author(s):  
Hannah Demond ◽  
Debora Dankert ◽  
Ruth Grümmer ◽  
Bernhard Horsthemke
Keyword(s):  
Fold Increase ◽  
Fertilization Rate ◽  
Developmental Competence ◽  
Preimplantation Embryos ◽  
Cell Stage ◽  
Embryonic Genome ◽  
Oocyte Aging ◽  
And Control ◽  
Genome Activation ◽  
Zygotic Genome

AbstractDelayed ovulation, or preovulatory aging, can seriously compromise the developmental competence of oocytes. In the present study, we have investigated the effect of preovulatory aging on preimplantation embryos. Delaying ovulation with the gonadotropin releasing hormone (GnRH) antagonist Cetrorelix led to a decline in 2-cell rate from 76 to 46%. From control mice, an average of 17 embryos per mouse was retrieved. This number decreased to a mean of 5 embryos per mouse after preovulatory aging, suggesting that fertilization is impaired by aging. For analysis of zygotic genome activation, 2-cell embryos were incubated with BrUTP, which was incorporated into nascent RNA and detected by immunohistochemistry. A 2.85-fold increase in fluorescence intensity was detected after aging, pointing to a precocious activation of the genome. A possible effect of preovulatory aging on genomic imprint maintenance was investigated at the 8-cell stage. Deep amplicon bisulfite sequencing of Igf2r, Snrpn, H19 and Pou5f1 showed no significant changes between embryos derived from preovulatory-aged oocytes and control embryos, indicating stable imprint maintenance throughout epigenetic reprogramming. We conclude that preovulatory aging of the oocyte affects fertilization and embryonic genomic activation.

68 EPIGENETIC REMODELING OF HISTONE 3 MARKS DURING BOVINE PRE-IMPLANTATION DEVELOPMENT

2014 ◽  
Vol 26 (1) ◽  
pp. 148
Author(s):  
Y. S. Bogliotti ◽  
L. B. Ferré ◽  
D. J. Humpal ◽  
P. J. Ross
Keyword(s):  
Embryo Development ◽  
Oocyte Maturation ◽  
Mixed Model ◽  
Statistical Significance ◽  
Germinal Vesicle ◽  
Cell Stage ◽  
Embryonic Genome Activation ◽  
Histone 3 ◽  
Embryonic Genome ◽  
Genome Activation

During pre-implantation development, substantial epigenetic changes occur that are thought to play key roles in achieving embryonic genome activation and totipotency. Embryonic genome activation occurs at the 8- to 16-cell stage in cattle and, although it is a crucial step of development, the specific mechanisms involved are still poorly understood. The aim of this study was to determine whether 4 histone 3 marks associated with active genes are remodelled during oocyte and early embryo development in cattle. The dynamics of acetylation of lysine 27 (H3K27ac), di-methylation of lysine 79 (H3K79me2), and mono- and tri-methylation of lysine 4 (H3K4me1, H3K4me3) were assessed by immunofluorescence and confocal microscopy. Ovaries were obtained from an abattoir. Immature germinal vesicle stage oocytes were aspirated from small antral follicles and matured for 24 h to the metaphase II stage (MII). Embryos were produced by in vitro fertilization and collected at different stages of development: pronuclear [PN; 18 h post-fertilization (hpf)], 2-cell (30 hpf), 4-cell (44 hpf), 8-cell (56 hpf), 16-cell (72 hpf), morula (120 hpf), and blastocyst (180 hpf). Three to 4 biological replicates were done per antibody and a total of 197 oocytes per embryo were imaged (8 to 16 per stage/antibody). The images were analysed using Fiji (Schindelin et al. 2012 Nat. Methods 9, 676–682). The average nuclear intensity per oocyte per embryo was adjusted by the average of 2 cytoplasmic areas (background). An ANOVA mixed model was used for statistical analysis using SAS (SAS Institute Inc., Cary, NC, USA). The least squares means of the different stages were compared (within each antibody group) using a Tukey-Kramer adjustment and were considered to be significantly different at P < 0.05. The H3K79me2 marks showed a significant increase from germinal vesicle to MII, a change opposite that of H3K27ac, which experienced a significant decrease between these two stages. The H3K4me1/me3 marks showed no significant changes during oocyte maturation. All 3 methylation marks presented a significant reduction in nuclear intensity from MII to PN, indicating that these marks are actively removed right after fertilization. The opposite effect was observed for the acetylation mark, in which the levels increased significantly from MII to PN. The H3K4me1/me3 marks showed a gradual decrease in intensity levels from the 2-cell stage onward, reaching a minimum at the 16-cell per morula stages. The H3K79me2 levels were low from PN to 16-cell stage, at which point its intensity levels began to increase, reaching statistical significance at the blastocyst stage. The H3K27ac marks showed a slow decrease in intensity levels from the PN stage, achieving statistical significance as it dropped to a minimum at the 16-cell stage. These results show that the global levels of the assayed epigenetic marks undergo dynamic changes during oocyte maturation and embryo development, suggesting that their remodelling may be important for early development. The authors thank Alta Genetics for providing the semen.

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