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Frontiers in Cell and Developmental... 2024What is the utilization rate of embryos that exert inadequate zygote cleavage into three daughter cells?
RESEARCH QUESTION
What is the utilization rate of embryos that exert inadequate zygote cleavage into three daughter cells?
DESIGN
This study used a retrospective dataset from a single IVF Unit. A total of 3,060 embryos from 1,811 fresh IVF cycles were analyzed. The cleavage pattern, morphokinetics, and outcome were recorded. Only 2pn embryos, fertilized by ejaculated sperm, and cultured in a time-lapse system for at least 5 days were included. We generated three study groups according to the embryo's cleavage pattern: (I) Control, normal cleavage ( = 551); (II) fast cleavage, zygote to three cells within 5 h ( = 1,587); and (III) instant direct tripolar cleavage (IDC) from zygote to three cells ( = 922).
RESULTS
The rate of usable fast cleavage blastocysts was 108/1,587 (6.81%) and usable control blastocysts was 180/551 (32.67%). The time of PN fading and from fading to first cleavage differed significantly between the three groups. Although the pregnancy rate of control and fast cleavage blastocysts were comparable (40.35% and 42.55%, respectively), the amount of instant direct cleavage embryos that reached blastocyst stage was neglectable (only four embryos out of 922 analyzed IDC embryos) and unsuitable for statistical comparison of pregnancy rates.
CONCLUSION
Our results indicate the need to culture instant direct cleavage embryos for 5 days, up to the blastocyst stage, and avoid transfer of embryos that are fated to arrest even when their morphological grade on day 3 is acceptable, whereas fast cleavage embryos could be transferred on day 3 when there is no alternative.
PubMed: 38887513
DOI: 10.3389/fcell.2024.1398684 -
DNA and Cell Biology Jun 2024parasites, the causative agents of malaria, rely on sophisticated cellular mechanisms to survive and proliferate within their hosts. complex life cycle requires... (Review)
Review
parasites, the causative agents of malaria, rely on sophisticated cellular mechanisms to survive and proliferate within their hosts. complex life cycle requires posttranslational modifications (PTMs) to control cellular activities. Neddylation is a type of PTM in which NEDD8 is covalently attached to target proteins and plays an important role in cell cycle control and metabolism. Covalent attachment to its substrates requires the Nedd8-activating enzyme, E1; the NEDD8-conjugating enzyme, E2; and the ligase, E3. In , protein neddylation is essential for parasite development during the stage I-II transition from zygote to ookinete differentiation and malaria transmission. Here, we discuss the current understanding of protein neddylation in which is involved in malaria transmission.
PubMed: 38885136
DOI: 10.1089/dna.2024.0120 -
Development (Cambridge, England) Jun 2024Plants are dependent on divisions of stem cells to establish cell lineages required for growth. During embryogenesis, early division products are considered to be stem...
Plants are dependent on divisions of stem cells to establish cell lineages required for growth. During embryogenesis, early division products are considered to be stem cells, whereas during post-embryonic development, stem cells are present in meristems at the root and shoot apex. PLETHORA/AINTEGUMENTA-LIKE (PLT/AIL) transcription factors are regulators of post-embryonic meristem function and are required to maintain stem cell pools. Despite the parallels between embryonic and post-embryonic stem cells, the role of PLTs during early embryogenesis has not been thoroughly investigated. Here, we demonstrate that the PLT regulome in the zygote, and apical and basal cells is in strong congruence with that of post-embryonic meristematic cells. We reveal that out of all six PLTs, only PLT2 and PLT4/BABY BOOM (BBM) are expressed in the zygote, and that these two factors are essential for progression of embryogenesis beyond the zygote stage and first divisions. Finally, we show that other PLTs can rescue plt2 bbm defects when expressed from the PLT2 and BBM promoters, establishing upstream regulation as a key factor in early embryogenesis. Our data indicate that generic PLT factors facilitate early embryo development in Arabidopsis by induction of meristematic potential.
Topics: Meristem; Arabidopsis; Arabidopsis Proteins; Transcription Factors; Gene Expression Regulation, Plant; Gene Expression Regulation, Developmental; Seeds; Zygote
PubMed: 38884589
DOI: 10.1242/dev.202527 -
Harefuah Jun 2024The article, which focuses only on the prevention of the sperm and/or the frozen embryo mix-up, will begin by elaborating on the acute need to prevent the next gamete...
The article, which focuses only on the prevention of the sperm and/or the frozen embryo mix-up, will begin by elaborating on the acute need to prevent the next gamete and zygote mix-up scenario. Afterwards, it will explore the practical methods already existing and the technologies. The main chapter will suggest the possible artificial intelligence technologies in the narrow field of artificial insemination for achieving that goal.
Topics: Humans; Artificial Intelligence; Insemination, Artificial; Male; Female; Cryopreservation; Spermatozoa
PubMed: 38884286
DOI: No ID Found -
Research Square Jun 2024NLRP2 belongs to the subcortical maternal complex (SCMC) of mammalian oocytes and preimplantation embryos. This multiprotein complex, encoded by maternal-effect genes,...
BACKGROUND
NLRP2 belongs to the subcortical maternal complex (SCMC) of mammalian oocytes and preimplantation embryos. This multiprotein complex, encoded by maternal-effect genes, plays a pivotal role in the zygote-to-embryo transition, early embryogenesis, and epigenetic (re)programming. The maternal inactivation of genes encoding SCMC proteins has been linked to infertility and subfertility in mice and humans. However, the underlying molecular mechanisms for the diverse functions of the SCMC, particularly how this cytoplasmic structure influences DNA methylation, which is a nuclear process, are not fully understood.
RESULTS
We undertook joint transcriptome and DNA methylome profiling of pre-ovulatory germinal-vesicle oocytes from -null, heterozygous (Het), and wild-type (WT) female mice. We identified numerous differentially expressed genes (DEGs) in Het and -null when compared to WT oocytes. The genes for several crucial factors involved in oocyte transcriptome modulation and epigenetic reprogramming, such as DNMT1, UHRF1, KDM1B and ZFP57 were overexpressed in Het and -null oocytes. Absence or reduction of , did not alter the distinctive global DNA methylation landscape of oocytes, including the bimodal pattern of the oocyte methylome. Additionally, although the methylation profile of germline differentially methylated regions (gDMRs) of imprinted genes was preserved in oocytes of Het and -null mice, we found altered methylation in oocytes of both genotypes at a small percentage of the oocyte-characteristic hyper- and hypomethylated domains. Through a tiling approach, we identified specific DNA methylation differences between the genotypes, with approximately 1.3% of examined tiles exhibiting differential methylation in Het and -null compared to WT oocytes.
CONCLUSIONS
Surprisingly, considering the well-known correlation between transcription and DNA methylation in developing oocytes, we observed no correlation between gene expression differences and gene-body DNA methylation differences in -null versus WT oocytes or Het versus WT oocytes. We therefore conclude that post-transcriptional changes in the stability of transcripts rather than altered transcription is primarily responsible for transcriptome differences in -null and Het oocytes.
PubMed: 38883732
DOI: 10.21203/rs.3.rs-4457414/v1 -
Journal of Obstetrics and Gynaecology... Jun 2024To study the association between the blastulation rate, the presence of 1 pro nucleus (1PN) zygotes, and the ploidy of the cohort of blastocysts.
PURPOSE
To study the association between the blastulation rate, the presence of 1 pro nucleus (1PN) zygotes, and the ploidy of the cohort of blastocysts.
METHODS
A cross-sectional study using the existing databases of two university fertility centers in Canada. We included 345 cycles from 235 couples who underwent next generation sequencing PGT-A in the study.
RESULTS
A total of 1456 blastocysts were biopsied. In multivariate analysis, only female age and the number of 1PN/2PN embryos showed a negative association with euploid ratio. Surprisingly, when the analysis was limited to cycles with no delayed blastulation, the blastulation rate was also negatively associated with the euploid ratio.
CONCLUSION
This study sheds some light on the stages of early embryo development. Further study on the mechanisms governing embryo development and the different cell cycle checkpoints in embryo development is warranted.
PubMed: 38878821
DOI: 10.1016/j.jogc.2024.102586 -
Human Reproduction (Oxford, England) Jun 2024Which actively translated maternal transcripts are differentially regulated between clinically relevant in vitro and in vivo maturation (IVM) conditions in mouse oocytes...
STUDY QUESTION
Which actively translated maternal transcripts are differentially regulated between clinically relevant in vitro and in vivo maturation (IVM) conditions in mouse oocytes and zygotes?
SUMMARY ANSWER
Our findings uncovered significant differences in the global transcriptome as well as alterations in the translation of specific transcripts encoding components of energy production, cell cycle regulation, and protein synthesis in oocytes and RNA metabolism in zygotes.
WHAT IS KNOWN ALREADY
Properly regulated translation of stored maternal transcripts is a crucial factor for successful development of oocytes and early embryos, particularly due to the transcriptionally silent phase of meiosis.
STUDY DESIGN, SIZE, DURATION
This is a basic science study utilizing an ICR mouse model, best suited for studying in vivo maturation. In the treatment group, fully grown germinal vesicle oocytes from stimulated ovaries were in vitro matured to the metaphase II (MII) stage either as denuded without gonadotropins (IVM DO), or as cumulus-oocyte complexes (IVM COC) in the presence of 0.075 IU/ml recombinant FSH (rFSH) and 0.075 IU/ml recombinant hCG (rhCG). To account for changes in developmental competence, IVM COC from non-stimulated ovaries (IVM COC-) were included. In vivo matured MII oocytes (IVO) from stimulated ovaries were used as a control after ovulation triggering with rhCG. To simulate standard IVM conditions, we supplemented media with amino acids, vitamins, and bovine serum albumin. Accordingly, in vitro pronuclear zygotes (IMZ) were generated by IVF from IVM DO, and were compared to in vivo pronuclear zygotes (IVZ). All experiments were performed in quadruplicates with samples collected for both polyribosome fractionation and total transcriptome analysis. Samples were collected over three consecutive months.
PARTICIPANTS/MATERIALS, SETTING, METHODS
All ICR mice were bred under legal permission for animal experimentation (no. MZE-24154/2021-18134) obtained from the Ministry of Agriculture of the Czech Republic. Actively translated (polyribosome occupied) maternal transcripts were detected in in vitro and in vivo matured mouse oocytes and zygotes by density gradient ultracentrifugation, followed by RNA isolation and high-throughput RNA sequencing. Bioinformatic analysis was performed and subsequent data validation was done by western blotting, radioactive isotope, and mitotracker dye labelling.
MAIN RESULTS AND THE ROLE OF CHANCE
Gene expression analysis of acquired polysome-derived high-throughput RNA sequencing data revealed significant changes (RPKM ≥ 0.2; P ≤ 0.005) in translation between in vitro and in vivo matured oocytes and respectively produced pronuclear zygotes. Surprisingly, the comparison between IVM DO and IVM COC RNA-seq data of both fractionated and total transcriptome showed very few transcripts with more than a 2-fold difference. Data validation by radioactive isotope labelling revealed a decrease in global translation bof20% in IVM DO and COC samples in comparison to IVO samples. Moreover, IVM conditions compromised oocyte energy metabolism, which was demonstrated by both changes in polysome recruitment of each of 13 mt-protein-coding transcripts as well as by validation using mitotracker red staining.
LARGE SCALE DATA
The data discussed in this publication have been deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE241633 (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE241633).
LIMITATIONS, REASONS FOR CAUTION
It is extremely complicated to achieve in vivo consistency in animal model systems such as porcine or bovine. To achieve a high reproducibility of in vivo stimulations, the ICR mouse model was selected. However, careful interpretation of our findings with regard to assisted reproductive techniques has to be made by taking into consideration intra-species differences between the mouse model and humans. Also, the sole effect of the cumulus cells' contribution could not be adequately addressed by comparing IVM COC and IVM DO, because the IVM DO were matured without gonadotropin supplementation.
WIDER IMPLICATIONS OF THE FINDINGS
Our findings confirmed the inferiority of standard IVM technology compared with the in vivo approach. It also pointed at compromised biological processes employed in the critical translational regulation of in vitro matured MII oocytes and pronuclear zygotes. By highlighting the importance of proper translational regulation during in vitro oocyte maturation, this study should prompt further clinical investigations in the context of translation.
STUDY FUNDING/COMPETING INTEREST(S)
This work was supported by the Czech Grant Agency (22-27301S), Charles University Grant Agency (372621), Ministry of Education, Youth and Sports (EXCELLENCE CZ.02.1.01/0.0/0.0/15_003/0000460 OP RDE), and Institutional Research Concept RVO67985904. No competing interest is declared.
PubMed: 38876973
DOI: 10.1093/humrep/deae126 -
Biochimica Et Biophysica Acta.... Jun 2024Post-translational modification and fine-tuned protein turnover are of great importance in mammalian early embryo development. Apart from the classic protein degradation...
Post-translational modification and fine-tuned protein turnover are of great importance in mammalian early embryo development. Apart from the classic protein degradation promoting ubiquitination, new forms of ubiquitination-like modification are yet to be fully understood. Here, we demonstrate the function and potential mechanisms of one ubiquitination-like modification, neddylation, in mouse preimplantation embryo development. Treated with specific inhibitors, zygotes showed a dramatically decreased cleavage rate and almost all failed to enter the 4-cell stage. Transcriptional profiling showed genes were differentially expressed in pathways involving cell fate determination and cell differentiation, including several down-regulated zygotic genome activation (ZGA) marker genes. A decreased level of phosphorylated RNA polymerase II was detected, indicating impaired gene transcription inside the embryo cell nucleus. Proteomic data showed that differentially expressed proteins were enriched in histone modifications. We confirmed the lowered in methyltransferase (KMT2D) expression and a decrease in histone H3K4me3. At the same time, acetyltransferase (CBP/p300) reduced, while deacetylase (HDAC6) increased, resulting in an attenuation in histone H3K27ac. Additionally, we observed the up-regulation in YAP1 and RPL13 activities, indicating potential abnormalities in the downstream response of Hippo signaling pathway. In summary, we found that inhibition of neddylation induced epigenetic changes in early embryos and led to abnormalities in related downstream signaling pathways. This study sheds light upon new forms of ubiquitination regulating mammalian embryonic development and may contribute to further investigation of female infertility pathology.
PubMed: 38871031
DOI: 10.1016/j.bbadis.2024.167292 -
Proceedings of the National Academy of... Jun 2024Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule,...
Hertwig's rule states that cells divide along their longest axis, usually driven by forces acting on the mitotic spindle. Here, we show that in contrast to this rule, microtubule-based pulling forces in early embryos align the spindle with the short axis of the cell. We combine theory with experiments to reveal that in order to correct this misalignment, inward forces generated by the constricting cytokinetic ring rotate the entire cell until the spindle is aligned with the cell's long axis. Experiments with slightly compressed mouse zygotes indicate that this cytokinetic ring-driven mechanism of ensuring Hertwig's rule is general for cells capable of rotating inside a confining shell, a scenario that applies to early cell divisions of many systems.
Topics: Animals; Caenorhabditis elegans; Mice; Spindle Apparatus; Microtubules; Cytokinesis; Rotation; Zygote; Embryo, Nonmammalian; Embryonic Development; Models, Biological
PubMed: 38870057
DOI: 10.1073/pnas.2318838121 -
The International Journal of... Jun 2024Enhancers play an essential role in gene regulation by receiving cues from transcription factors and relaying these signals to modulate transcription from target...
Enhancers play an essential role in gene regulation by receiving cues from transcription factors and relaying these signals to modulate transcription from target promoters. Enhancer-promoter communications occur across large linear distances of the genome and with high specificity. The molecular mechanisms that underlie enhancer-mediated control of transcription remain unresolved. In this review, we focus on research in uncovering the molecular mechanisms governing enhancer-promoter communication and discuss the current understanding of developmental gene regulation. The functions of protein acetylation, pausing of RNA polymerase II, transcriptional bursting, and the formation of nuclear hubs in the induction of tissue-specific programs of transcription during zygotic genome activation are considered.
PubMed: 38869221
DOI: 10.1387/ijdb.230218gh