Bovine Preimplantation Embryos Research Articles

PPAR-gamma influences developmental competence and trophectoderm lineage specification in bovine embryos.

Peroxisome proliferator-activated receptor gamma (PPARG) is a critical regulator of placental function, but earlier roles in preimplantation embryo development and embryonic origins of placental formation have not been established. Results herein demonstrate that PPARG responds to pharmacologic stimulation in the bovine preimplantation embryo and influences blastocyst development, cell lineage specification, and transcripts important for placental function. Peroxisome proliferator-activated receptor gamma (PPARG) is a key regulator of metabolism with conserved roles that are indispensable for placental function, suggesting previously unidentified and important roles in preimplantation embryo development. Herein, we report the functional characterization of bovine PPARG to reveal expression beginning on D6 of development with nuclear and ubiquitous patterns. Day 6 PPARG+ embryos have fewer total cells and a lower proportion of trophectoderm cells compared to PPARG- embryos (P < 0.05). Coculture with a PPARG agonist, rosiglitazone (Ros), or antagonist GW9662 (GW), decreases blastocyst development (P < 0.01). Day 7.5 (D7.5) developmentally delayed embryos exposed to Ros express lower transcript abundance of key genes important for placental development and cell lineage formation (CDX2, RXRB, SP1, TFAP2C, SIRT1, and PTEN). In contrast, Ros does not alter transcript abundance in D7.5 blastocysts, but GW treatment lowers RXRA, RXRB, SP1, and NFKB1 expression. Knockout of embryonic PPARG does not alter blastocyst formation and hatching ability but decreases total cell number in D7.5 blastocysts. The decreased embryo development response and affected pathways following targeted pharmacological perturbation vs embryonic knockout of PPARG suggest roles of both maternal and embryonic origins. These data reveal regulatory contributions of PPARG in preimplantation embryo development, cell lineage formation, and regulation of transcripts associated with placental function.

81 Maternal extracellular vesicles from in vitro and in vivo system have different impact in pre-implantation bovine embryos development

81 Maternal extracellular vesicles from in vitro and in vivo system have different impact in pre-implantation bovine embryos development

84 Characterization and effect of endometriosomes on the development and quality of pre-implantation bovine embryos

84 Characterization and effect of endometriosomes on the development and quality of pre-implantation bovine embryos

Presence of KREMEN receptors for DKK1 in the preimplantation bovine embryo.

The WNT inhibitory protein DKK1 has been shown to regulate development of the preimplantation embryo to the blastocyst stage. In cattle, DKK1 increases the number of trophectoderm cells that are the precursor of the placenta. DKK1 can affect cells by blocking WNT signaling through its receptors KREMEN1 and KREMEN2. Here it was shown that the mRNA for KREMEN1 and KREMEN2 decline as the embryo advances in development. Nonetheless, immunoreactive KREMEN1 was identified in blastocysts using Western blotting. DKK1 also decreased amount of immunoreactive CTNNB1 in blastocysts, as would be expected if DKK1 was signaling through a KREMEN-mediated pathway. Thus, it is likely that KREMEN1 functions as a receptor for DKK1 in the preimplantation bovine embryo.

Adaptative response to changes in pyruvate metabolism on the epigenetic landscapes and transcriptomics of bovine embryos

The epigenetic reprogramming that occurs during the earliest stages of embryonic development has been described as crucial for the initial events of cell specification and differentiation. Recently, the metabolic status of the embryo has gained attention as one of the main factors coordinating epigenetic events. In this work, we investigate the link between pyruvate metabolism and epigenetic regulation by culturing bovine embryos from day 5 in the presence of dichloroacetate (DCA), a pyruvate analog that increases the pyruvate to acetyl-CoA conversion, and iodoacetate (IA), which inhibits the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), leading to glycolysis inhibition. After 8 h of incubation, both DCA and IA-derived embryos presented higher mitochondrial membrane potential. Nevertheless, in both cases, lower levels of acetyl-CoA, ATP-citrate lyase and mitochondrial membrane potential were found in blastocysts, suggesting an adaptative metabolic response, especially in the DCA group. The metabolic alteration found in blastocysts led to changes in the global pattern of H3K9 and H3K27 acetylation and H3K27 trimethylation. Transcriptome analysis revealed that such alterations resulted in molecular differences mainly associated to metabolic processes, establishment of epigenetic marks, control of gene expression and cell cycle. The latter was further confirmed by the alteration of total cell number and cell differentiation in both groups when compared to the control. These results corroborate previous evidence of the relationship between the energy metabolism and the epigenetic reprogramming in preimplantation bovine embryos, reinforcing that the culture system is decisive for precise epigenetic reprogramming, with consequences for the molecular control and differentiation of cells.

Absence of a molecular circadian clock in the preimplantation embryo is a conserved characteristic in the mammal.

It is not known when a functional circadian clock is established in the developing embryo. Lack of expression of key genes involved in the clock mechanism is indicative that a functional circadian clock mechanism is absent in the mammalian preimplantation embryo through the blastocyst stage of development. An embryonic circadian clock could conceivably organize cellular and developmental events temporally and in synchrony with other circadian rhythms in the mother. The hypothesis that a functional molecular clock exists in the preimplantation bovine, pig, human, and mouse embryo was tested by using publicly available RNAseq datasets to examine developmental changes in expression of the core genes responsible for the circadian clock - CLOCK, ARNTL, PER1, PER2, CRY1, and CRY2. In general, the transcript abundance of each gene decreased as development advanced to the blastocyst stage. The most notable exception was for CRY2, where transcript abundance was low and constant from the two-cell or four-cell to the blastocyst stage. Developmental patterns were generally the same for all species although there were some species-specific patterns such as an absence of PER1 expression in the pig, an increase in ARNTL expression at the four-cell stage in human, and an increase in expression of Clock and Per1 from the zygote to two-cell stage in the mouse. Analysis of intronic reads (indicative of embryonic transcription) for bovine embryos indicated an absence of embryonic transcription. Immunoreactive CRY1 was not detected in the bovine blastocyst. Results indicate that the preimplantation mammalian embryo lacks a functional intrinsic clock although specific components of the clock mechanism could conceivably play a role in other functions in the embryo.

Pre-Implantation Bovine Embryo Evaluation—From Optics to Omics and Beyond

Approximately 80% of the ~1.5 million bovine embryos transferred in 2021 were in vitro produced. However, only ~27% of the transferred IVP embryos will result in live births. The ~73% pregnancy failures are partly due to transferring poor-quality embryos, a result of erroneous stereomicroscopy-based morphological evaluation, the current method of choice for pre-transfer embryo evaluation. Numerous microscopic (e.g., differential interference contrast, electron, fluorescent, time-lapse, and artificial-intelligence-based microscopy) and non-microscopic (e.g., genomics, transcriptomics, epigenomics, proteomics, metabolomics, and nuclear magnetic resonance) methodologies have been tested to find an embryo evaluation technique that is superior to morphologic evaluation. Many of these research tools can accurately determine embryo quality/viability; however, most are invasive, expensive, laborious, technically sophisticated, and/or time-consuming, making them futile in the context of in-field embryo evaluation. However accurate they may be, using complex methods, such as RNA sequencing, SNP chips, mass spectrometry, and multiphoton microscopy, at thousands of embryo production/collection facilities is impractical. Therefore, future research is warranted to innovate field-friendly, simple benchtop tests using findings already available, particularly from omics-based research methodologies. Time-lapse monitoring and artificial-intelligence-based automated image analysis also have the potential for accurate embryo evaluation; however, further research is warranted to innovate economically feasible options for in-field applications.

P-155 MicroRNA-155 (miR-155) expression profile and developmental characteristics of bovine early embryos are altered when cultured in group versus individually

Abstract Study question Culturing bovine preimplantation embryos in group versus individually has an impact on the expression profile of miR-155 and developmental characteristics. Summary answer MiR-155 was significantly greater in its expression when embryos were cultured in groups versus singly. Developmental characteristics of blastocysts were similar regardless of culture condition. What is known already MiRNAs are short non-coding RNAs that play important roles in many biological pathways including embryogenesis and are potent effectors of post-transcriptional gene silencing. It has been estimated that approximately 60% of all proteins-coding genes are regulated by miRNAs. MiR-155 is involved in early events of embryogenesis; however, it has not been characterized in bovine embryos and this knowledge has not yet been clinically translated. Existing literature indicates that group culture yields superior embryo development as embryos can benefit from autocrine signaling and paracrine communication but embryos in groups may be exposed to negative effects of dying or delayed embryos. Study design, size, duration The study consisted of two groups: zygotes cultured to blastocysts in group and those cultured individually. Each sample consists of 3 blastocysts. Droplet digital PCR (dd-PCR) was used to examine the expression of miR-155. Gene Set Enrichment Analysis (GSEA) of miRNAs was carried out to identify functional Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways that are enriched for the targets of one or more miRNAs. Participants/materials, setting, methods Oocytes were aspirated from antral follicles of bovine ovaries and matured in vitro. Twenty-four hours post retrieval, matured oocytes were inseminated with sperm from similar bull. Presumptive zygotes were cultured either in groups or individually until blastocyst stage, Blastocyst were collected and purified for RNA. Analysis for KEGG and GO Biological Process, Cellular Component and Molecular Functions were carried out on the identified target genes. Results were plotted according to level of enrichment for miR-155. Main results and the role of chance Five hundred and seventy-five oocytes were retrieved from 120 bovine ovaries. Cleavage rate and blastocyst formation after IVF were compared between those blastocysts cultured in groups versus individually. There was no significant difference among the two groups with regards to cleavage rate (69% vs. 54%) and blastocyst formation (42% vs.35%). ddPCR assessment showed significantly greater MiR-155 expression in those blastocysts cultured in groups (p = 0.002). The highest level of miR-151 expressed was 20 copies/sample. Every sample, regardless of the culture conditions, had detectable miR-155 level. The interaction of predicted miR-155 target clusters based on the GO Biological Processes shows that miR-155 plays a role in DNA binding, transcription factor binding, regulates transcription and affects cell adhesion. KEGG analysis revealed an association between miR-155 to steroidogenesis and controls apoptosis pathways. Limitations, reasons for caution The number of copies expressed for this miRNA was relatively low, which could suggest that miR-155 may not have a functional role at the blastocyst stage as the effectiveness of a miRNA depends on the relative number of binding site and target molecules. Blastocysts were pooled based on morphological assessment. Wider implications of the findings MiRNAs offer a novel mean to assess embryonic fitness. Further validation and more complex study designs are required to implement the profiling of embryonic miRNAs as a diagnostic test for embryo selection. Group culture increased miR-155 expression, possibly reflecting differences in cellular behavior between group cultured embryos and individually ones. Trial registration number Not applicable

Perspective: Can early embryonic losses be reduced in lactating dairy cows?

Perspective: Can early embryonic losses be reduced in lactating dairy cows?

Disruption of CSF2RA in the bovine preimplantation embryo reduces development and affects embryonic gene expression in utero.

The hypothesis that CSF2 plays a role in the preimplantation development of the bovine embryo was tested by evaluating consequences of inactivation of CSF2RA (the functional receptor in the embryo) for development of embryos in utero. CRISPR/Cas9 was used to alter sequences on exon 5 and intron 5 of CSF2RA, Control embryos were injected with Cas9 mRNA only. Embryos > 16 cells at day 5 after insemination were transferred to synchronized recipient females in groups of 7 to 24. Embryos were flushed from the uterus two days later. The proportion of recovered embryos that developed to the blastocyst stage was lower for knockout embryos (39%) than for control embryos (63%). RNA sequencing of individual morulae and blastocysts indicated a total of 27 (morula) or 15 (blastocyst) differentially-expressed genes (false discovery rate <0.05). Gene set enrichment analysis indicated that the knockout affected genes playing roles in several functions including cell signaling and glycosylation. It was concluded that signaling through CSF2RA is not obligatory for development of the bovine preimplantation embryo to the blastocyst stage but that CSF2 signaling does enhance the likelihood that the embryo can become a blastocyst and result in specific changes in gene expression.

“Usage a CRISPR/Cas9-based for obtaining knockouts of economically significant cattle genes”

An experimental work dealing with the gene modification using the Cas9 RNA-based editing system was performed. Point site-specific breakpoints in gDNA were introduced at the zygote stage by microinjection of spCas9 mRNA protein and guide RNAs into the zygote cytoplasm. Oocytes that extruded the first and second polar bodies were used for the injection. 2 series of microinjections of gene editing designs for early bovine embryos were made. The degeneration ranged from 10% to 56% in different groups. A total of 100 injections were performed. Cleavage was started by 78% of the surviving oocytes; 5 embryos reached the blastocyst stage, which was 16% of the number of dividing embryos. All the resulting embryos were analyzed to evaluate the efficiency of editing. gDNA was isolated from all embryos that had reached the blastocyst stage. Using Sanger sequencing of genes of interest in pre-implantation bovine embryos and biopsies from them, it was shown that in 5 out of 17 embryos resulting from microinjections of guide RNA against the BLG gene and SpCas9 mRNA, and in 2 out of 9 embryos after microinjections of guide RNA against CD209 gene and SpCas9 mRNA, the required genome modifications were found. This is indicative of the high efficiency of this delivery method of the editing system.

Molecular and cellular programs underlying the development of bovine pre-implantation embryos.

Early embryonic mortality is a major cause of infertility in cattle, yet the underlying molecular causes remain a mystery. Over the past half century, assisted reproductive technologies such as in vitro fertilisation and somatic cell nuclear transfer have been used to improve cattle reproductive efficiency; however, reduced embryo developmental potential is seen compared to their in vivo counterparts. Recent years have seen exciting progress across bovine embryo research, including genomic profiling of embryogenesis, new methods for improving embryo competence, and experimenting on building bovine embryos from stem cell cultures. These advances are beginning to define bovine embryo molecular and cellular programs and could potentially lead to improved embryo health. Here, I highlight the current status of molecular determinants and cellular programs of bovine embryo development and new opportunities to improve the bovine embryo health.

65 Identification of chromatin state related to H3K27 acetylation in pre-implantation bovine embryos by cleavage under targets and tagmentation analysis

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

Embryonic microRNAs are essential for bovine preimplantation embryo development

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression after transcription. miRNAs are present in transcriptionally quiescent full-grown oocytes and preimplantation embryos that display a low level of transcription prior to embryonic genome activation. The role of miRNAs, if any, in preimplantation development is not known. The temporal pattern of expression of miRNAs during bovine preimplantation development was determined by small RNA-sequencing using eggs and preimplantation embryos (1-cell, 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst). Embryos cultured in the presence of α-amanitin, which permitted the distinguishing of maternal miRNAs from embryonic miRNAs, indicated that embryonic miRNA expression was first detected at the two-cell stage but dramatically increased during the morula and blastocyst stages. Targeting DGCR8 by a small-interfering RNA/morpholino approach revealed a role for miRNAs in the morula-to-blastocyst transition. Knockdown of DGCR8 not only inhibited expression of embryonically expressed miRNAs but also inhibited the morula-to-blastocyst transition. In addition, RNA-sequencing identified an increased relative abundance of messenger RNAs potentially targeted by embryonic miRNAs in DGCR8-knockdown embryos when compared with controls. Results from these experiments implicate an essential role for miRNAs in bovine preimplantation embryo development.

P-262 Magnetic Resonance spectroscopy of individual mammalian embryos and human microtissues

Abstract Study question Can magnetic resonance unravel the metabolic fingerprint of samples at the embryo scale? Summary answer We successfully utilized Magnetic Resonance Spectroscopy (MRS) on single mammalian embryos and microtissues and observed a diverse range of lipids in less than 1 hour. What is known already Non-invasive selection of the best embryo to transfer is one of the most significant challenges for ART professionals. The chemical sensitivity, resolving power, and, more importantly, the non-invasive nature of MRS makes it an excellent candidate to investigate the building blocks of complex organisms. Although MRS is a well-established technique for the biochemical profiling of large organisms, handling small samples like embryos and 3D cell cultures and spheroids alongside sensitivity issues has prevented its adoption for clinical and research applications. Our group has overcome these limitations with microchip-based sensors to leverage non-invasive MRS technology down to the embryo scale. Study design, size, duration A NASH in vitro model of liver microtissues was used first to detect lipid-based metabolic biomarkers over multiple time points in complex 3D cell cultures such as microtissues. We could discriminate between healthy and diseased human micro-livers based on their lipid content. Once the MRS data acquisition and analysis were set up using stimulated or control samples, we moved to the single early or late arrested bovine embryo analysis. The whole experiment lasted one month. Participants/materials, setting, methods Early or late arrested bovine embryos were obtained through IVF, cryopreserved and measured shortly after thawing. The microtissues were provided by InSphero AG (Schlieren, CH) and individually measured fresh in a time frame of 14 days based on 117 measurements. The micro-MRS device was loaded with culture medium and a single sample, then loaded into the MRS magnet. Measurements were performed for a total time of 50 min per embryo or 15 min per microtissue. Main results and the role of chance Micro-MRS efficiently identified four different biomarkers that were significantly differently expressed (p &amp;lt; 0.05) according to the biological state of microlivers simulating non-alcoholic fatty liver disease (NAFL). Three of these markers represent relative concentrations of lipid signatures from fully saturated, mono and poly-unsaturated fatty acids. In addition, we analyzed in vitro produced pre-implantation bovine embryos naturally arrested at different developmental stages. This choice arose from the necessity to analyze them at different and fixed developmental stages to investigate our technology discrimination potential. The spectra obtained from the embryos present up to 6 peak regions assignable to fatty acids as observed in microtissues. Furthermore, the amplitude of the peaks varies substantially within the same group, i.e., within the morulae and within the two 2-cell stage arrested embryos. Using both microtissues and mammalian embryos, we demonstrated that micro-MRS could be used to investigate variations in the lipid content of tiny samples non-invasively. Generally, the majority of the analytical assays used in lipid metabolism investigations rely on invasive/destructive methods such as histology and biopsies, which would hinder the continuation of embryonic development. A non-invasive in vivo assay like the one presented here would provide the means to reveal the role of embryonic lipids throughout development. Limitations, reasons for caution A vital step towards establishing MRS as a clinical and research tool is the reliable detection of a wide range of signals from cellular components. Our method is ready for R&amp;D studies, while its clinical application requires further safety studies and protocol optimization. Wider implications of the findings A non-invasive quick assay would provide the means to reveal the role of embryonic lipids throughout development. Micro-MRS can further develop into a safe embryo assay for selection before embryo transfer. This would apply to both human and animal ART, whose success rate is relatively low. Trial registration number not applicable

Actions of DKK1 on the preimplantation bovine embryo to affect pregnancy establishment, placental function, and postnatal phenotype†.

One mechanism by which the maternal environment regulates the early embryo is by secretion of cell-signaling molecules. One of these is dickkopf WNT signaling pathway inhibitor 1. Objectives were to (A) resolve discrepancies in the literature regarding effects of dickkopf WNT signaling pathway inhibitor 1 in the bovine embryo on development of trophectoderm and competence to establish pregnancy after embryo transfer and (B) determine whether there are long-term consequences of dickkopf WNT signaling pathway inhibitor 1 on placental function and postnatal phenotype. Embryos produced in vitro were cultured with vehicle or 100ng/mL recombinant human dickkopf WNT signaling pathway inhibitor 1 from Days 5 to 7.5 of development (i.e., the morula and blastocyst stages of development). dickkopf WNT signaling pathway inhibitor 1 increased the number of cells positive for the trophectoderm marker CDX2 at Day 7.5 of development while having no effect on number of cells positive for the inner cell mass marker SOX2. There was no effect of dickkopf WNT signaling pathway inhibitor 1 on pregnancy or calving rate after transfer of blastocysts produced with Y-sorted semen to either lactating dairy cows or suckling beef cows. Treatment with dickkopf WNT signaling pathway inhibitor 1 at the morula-to-blastocyst stages programmed placental function, as measured by an effect of dickkopf WNT signaling pathway inhibitor 1 on plasma concentrations of pregnancy associated glycoproteins and placental lactogen at Day 160 of gestation (although not on other days examined). dickkopf WNT signaling pathway inhibitor 1 treatment also resulted in calves that were heavier at birth as compared to calves derived from control embryos. After birth, dickkopf WNT signaling pathway inhibitor 1 calves grew slower than controls. Results confirm that dickkopf WNT signaling pathway inhibitor 1 alters the developmental program of the bovine embryo to affect both prenatal and postnatal phenotypes.

Actions of WNT family member 5A to regulate characteristics of development of the bovine preimplantation embryo†.

WNT signaling is important for regulation of embryonic development. The most abundant WNT gene expressed in the bovine endometrium during the preimplantation period is WNT5A. One objective was to determine whether WNT5A regulates competence of the bovine preimplantation embryo to become a blastocyst and alters the number of cells in the inner cell mass and trophectoderm. A second objective was to delineate features of the cell-signaling mechanisms involved in WNT5A actions. WNT5A caused a concentration-dependent increase in the proportion of embryos developing to the blastocyst stage and in the number of inner cell mass cells in the resultant blastocysts. A concentration of 200ng/mL was most effective, and a higher concentration of 400ng/mL was not stimulatory. Bovine serum albumin in culture reduced the magnitude of effects of WNT5A on development to the blastocyst stage. WNT5A affected expression of 173 genes at the morula stage; all were upregulated by WNT5A. Many of the upregulated genes were associated with cell signaling. Actions of WNT5A on development to the blastocyst stage were suppressed by a Rho-associated coiled-coil kinase (ROCK) signaling inhibitor, suggesting that WNT5A acts through Ras homology gene family member A (RhoA)/ROCK signaling. Other experiments indicated that actions of WNT5A are independent of the canonical β-catenin signaling pathway and RAC1/c-Jun N-terminal kinase (JNK) signaling. This is the first report outlining the actions of WNT5A to alter the development of the mammalian embryo. These findings provide insights into how embryokines regulate maternal-embryonic communication.

Micronucleus formation during early cleavage division is a potential hallmark of preimplantation embryonic loss in cattle

In assisted reproductive technology (ART)-derived embryos of non-rodent mammals, including humans and cattle, chromosome segregation errors are highly likely to occur during early cleavage division, resulting in aneuploidy, including mosaicism. However, the relationship between chromosomal segregation errors during early cleavage and subsequent embryonic development has not been detailed in these mammals. In the present study, we developed non-invasive live-cell imaging of chromosome segregation dynamics using a histone H2B-mCherry mRNA probe in bovine preimplantation embryos. Chromosome segregation errors in early cleavage affected blastocyst formation. Especially, embryos that underwent abnormal chromosome segregation (ACS) with multiple or large micronucleus formation rarely developed into blastocysts. Embryos with the severe ACS had prolonged cell cycle duration. After transfer of blastocysts with live-cell imaging of chromosome segregation to ten cows, six became pregnant and four of them gave full-term offspring. Interestingly, two of them were derived from blastocysts with ACS. Hence, chromosomal segregation errors with micronucleus formation during early cleavage can be a fatal hallmark of preimplantation embryogenesis in cattle. This technique has shown potential for understanding the relationship between chromosome segregation error and subsequent embryo development, and for selecting viable ART-derived embryos for medical and livestock production.

Silencing XIST on the future active X: Searching human and bovine preimplantation embryos for the repressor.

X inactivation is the means of equalizing the dosage of X chromosomal genes in male and female eutherian mammals, so that only one X is active in each cell. The XIST locus (in cis) on each additional X chromosome initiates the transcriptional silence of that chromosome, making it an inactive X. How the active X in both males and females is protected from inactivation by its own XIST locus is not well understood in any mammal. Previous studies of autosomal duplications suggest that gene(s) on the short arm of human chromosome 19 repress XIST on the active X. Here, we examine the time of transcription of some candidate genes in preimplantation embryos using single-cell RNA sequencing data from human embryos and qRT-PCR from bovine embryos. The candidate genes assayed are those transcribed from 19p13.3-13.2, which are widely expressed and can remodel chromatin. Our results confirm that XIST is expressed at low levels from the future active X in embryos of both sexes; they also show that the XIST locus is repressed in both sexes when pluripotency factors are being upregulated, during the 4-8 cell and morula stages in human and bovine embryos - well before the early blastocyst (E5) when XIST on the inactive X in females starts to be upregulated. Our data suggest a role for DNMT1, UHRF1, SAFB and SAFB2 in XIST repression; they also exclude XACT and other 19p candidate genes and provide the transcriptional timing for some genes not previously assayed in human or bovine preimplantation embryos.

Mining RNAseq data reveals dynamic metaboloepigenetic profiles in human, mouse and bovine pre-implantation embryos

SummaryMetaboloepigenetic regulation has been reported in stem cells, germ cells, and tumor cells. Embryonic metaboloepigenetics, however, have just begun to be described. Here we analyzed RNAseq data to characterize the metaboloepigenetic profiles of human, mouse, and bovine pre-implantation embryos. In embryos, metaboloepigenetic reprogramming was species-specific, varied with the developmental stage and was disrupted with in vitro culture. Metabolic pathways and gene expressions were strongly correlated with early embryo DNA methylation and were changed with in vitro culture. Although the idea that the in vitro environment may influence development is not new, there has been little progress on improving pregnancy rates after decades using in vitro fertilization. Hence, the present data will contribute to understanding how the in vitro manipulation affects the metaboloepigenetic status of early embryos, which can be used to establish culture strategies aimed at improving the in vitro environment and, consequently, pregnancy rates and offspring health.