Embryo Transition Research Articles

Widespread regulation of the maternal transcriptome by Nanos in Drosophila.

The translational repressor Nanos (Nos) regulates a single target, maternal hunchback (hb) mRNA, to govern abdominal segmentation in the early Drosophila embryo. Nos is recruited to sites in the 3' UTR of hb mRNA in collaboration with the sequence-specific RNA-binding protein Pumilio (Pum); on its own, Nos has no binding specificity. Nos is expressed at other stages of development, but very few mRNA targets that might mediate its action at these stages have been described. Nor has it been clear whether Nos is targeted to other mRNAs in concert with Pum or via other mechanisms. In this report, we identify mRNAs targeted by Nos via 2 approaches. First, we identify mRNAs depleted upon expression of a chimera bearing Nos fused to the nonsense mediated decay (NMD) factor Upf1. We find that, in addition to hb, Upf1-Nos depletes approximately 2,600 mRNAs from the maternal transcriptome in early embryos. Virtually all of these appear to be targeted in a canonical, hb-like manner in concert with Pum. In a second, more conventional approach, we identify mRNAs that are stabilized during the maternal zygotic transition (MZT) in embryos from nos- females. Most (86%) of the 1,185 mRNAs regulated by Nos are also targeted by Upf1-Nos, validating use of the chimera. Previous work has shown that 60% of the maternal transcriptome is degraded in early embryos. We find that maternal mRNAs targeted by Upf1-Nos are hypoadenylated and inefficiently translated at the ovary-embryo transition; they are subsequently degraded in the early embryo, accounting for 59% of all destabilized maternal mRNAs. We suggest that the late ovarian burst of Nos represses a large fraction of the maternal transcriptome, priming it for later degradation by other factors in the embryo.

Effect of water temperature on the beginning of active feeding of tugun and nelma larvae

Temperature conditions of transition to active feeding of tugun Coregonus tugun (Pallas, 1814) and nelma Stenodus leucichthys nelma (Pallas, 1773) larvae to substantiate elements of artificial reproduction biotechniques were studied experimentally. We added live food (Artemia nauplii) and placed larvae a day after the transition to the first stage of the larval period in aquaria with different constant temperatures. The proportion of larvae that started feeding consistently increased in the temperature range 0.2–10 °C reaching 100% at daily exposure of experiments. The 50% level of transition to active feeding was observed at 6 °C. The ability of larvae with preliminary feeding experience to consume food at a temperature 1–5 °C lower than that of larvae that had not fed before was found. The individual duration of larvae transition to active feeding varied significantly from 1 to 8–9 days in a series of experiments at a stable low temperature (0.2 °C). Delayed initiation of exogenous feeding due to the limiting effect of low temperatures is physiologically equivalent to larval starvation. This may negatively affect the subsequent development of larvae. Species specificity was not significantly revealed in all series of experiments. We recommend keeping the water temperature at least 10°C from the time of embryo transition to larval development when rearing juveniles under intensive technologies to reduce the diversity of planting material in terms of size parameters. In this case, the duration of the time interval necessary for the beginning of active feeding of all larvae will be maximally reduced.

P-232 EIF4E1B Contributes to Early Translation Burst for Embryogenesis Whose Deficiency Causes Embryo Development Arrest at Four-Cell Stage during Oocyte to Embryo Transition in Women

Abstract Study question What are the effects and corresponding mechanisms of the early burst of translation inhibited during the oocyte-to-embryo transition (OET), which is essential for human embryogenesis? Summary answer EIF4E1B contributes to the early burst of translation for embryogenesis whose deficiency causes embryo development arrest at four-cell stage during OET in women. What is known already The first records of human zygotic genes are observed in late one-cell zygotes, and translation in mammals happens before the activation of zygotic genes. Recently, we identified an oocyte specific role of eIF4E1b in selecting and regulating the translation initiation of individual mRNAs that are involved in cell differentiation, cell cycle regulation, and cell fate determination during OET. The genetic ablation of Eif4e1b in mice resulted in a developmental arrest in the 2-cell phase of embryogenesis. How is the early burst of translation regulated in human embryogenesis remains unknown. Study design, size, duration A total of 236 female Chinese participants who underwent assisted reproductive technology (ART) and experienced at least one cycle of OET defects were recruited from our university-affiliated center from January 2017 to May 2023. 60 frozen human 3 pronuclei (3PN) embryos have been used for this work. The use of human embryos donated for research was allowed by the the Ethics Committee of the Reproductive and Genetic Hospital of CITIC–Xiangya (reference LL-SC-2018-009). Participants/materials, setting, methods All recruited individuals underwent whole-exome sequencing. In vitro transcription and micro-injection were employed to validate the embryo development pattern under different translation inhibition as well as potential effects of the EIF4E1B variant in mouse oocytes. Immunoprecipitation was conducted to investigate the causes of OET failure and identify the ability of eIF4E1B bind with PABPC1L. Additionally, a knock-in (KI) mouse model carrying homozygous Eif4e1bA192T was generated to evaluate female fertility and a more comprehensive mechanism. Main results and the role of chance Translation inhibitor cycloheximide (CHX) and knockdown of different translation initiation factors eIF4Es were administered to human 3 pronuclei (3PN) embryos, starting from the 1C stage. The absence of eIF4E1B was identified as a specific phenotype, leading to developmental arrest at the 1-4C stage, which is consistent with the effects of Translation inhibitor CHX. Additionally, a novel homozygous mutation (c.565G>A; p. Ala189Thr) in EIF4E1B was found within a consanguineous family. This mutation was associated with recurrent four-cell arrests, suggesting a translational regulation role for eIF4E1B from the 1C to 4C stage during OET. The mutated eIF4E1B disrupted the expression and condensate distribution of eIF4E1B. We also confirmed the interaction between eIF4E1B and PABPC1L, with the c.565G>A variant in EIF4E1B impairing their binding ability. Furthermore, KI mice carrying homozygous Eif4e1bA192T partially recapitulated the phenotype resulting from EIF4E1B deficiency. Limitations, reasons for caution More cases are required to demonstrate the association between EIF4E1B variants and phenotypes. Wider implications of the findings By delving deeper into the intricate interactions between basic physiology and clinical characteristics, this research elucidates the crucial role of maternal EIF4E1B in ensuring the early burst of translation for embryogenesis and provide a diagnostic genetic marker for women with OET defects. Trial registration number Not applicable

Use of image processing techniques can indicate bovine embryo stress and response to temperature changes in real-time

Temperature is a known factor affecting pre-implantation embryo development and should be controlled to prevent a decrease in developmental competence. However, practical considerations of the conventional embryo transfer procedure require the embryos to endure fluctuations in temperature as the embryos are flushed from the in vivo uterine environment, to the in vitro collection dish and into the embryo laboratory. This transition typically involves the embryo culture environ­ment decreasing from 38 °C (body temperature) to approximate­ly 20 °C (room temperature), possibly inducing damage to the embryo and reducing the likelihood of the embryo to result in live birth. The objective of this study was to use graphic imag­ing and machine learning techniques to measure real-time bo­vine embryo morphokinetic activity as the embryo transitions from 38 °C to environmental room temperature.

Single-cell omics identifies inflammatory signaling as a trans-differentiation trigger in mouse embryos

Trans-differentiation represents a direct lineage conversion; however, insufficient characterization of this process hinders its potential applications. Here, to explore a potential universal principal for trans-differentiation, we performed single-cell transcriptomic analysis of endothelial-to-hematopoietic transition (EHT), endothelial-to-mesenchymal transition, and epithelial-to-mesenchymal transition in mouse embryos. We applied three scoring indexes of entropies, cell-type signature transcription factor expression, and critical transition signals to show common features underpinning the fate plasticity of transition states. Cross-model comparison identified inflammatory-featured transition states and a common trigger role of interleukin-33 in promoting fate conversions. Multimodal profiling (integrative transcriptomic and chromatin accessibility analysis) demonstrated the inflammatory regulation of hematopoietic specification. Furthermore, multimodal omics and fate-mapping analyses showed that endothelium-specific Spi1, as an inflammatory effector, governs appropriate chromatin accessibility and transcriptional programs to safeguard EHT. Overall, our study employs single-cell omics to identify critical transition states/signals and the common trigger role of inflammatory signaling in developmental-stress-induced fate conversions.

Glycolytic state of aortic endothelium favors hematopoietic transition during the emergence of definitive hematopoiesis.

The first definitive hematopoietic progenitors emerge through the process of endothelial-to-hematopoietic transition in vertebrate embryos. With molecular regulators for this process worked out, the role of metabolic pathways used remains unclear. Here, we performed nano-LC-MS/MS-based proteomic analysis and predicted a metabolic switch from a glycolytic to oxidative state upon hematopoietic transition. Mitochondrial activity, glucose uptake, and glycolytic flux analysis supported this hypothesis. Systemic inhibition of lactate dehydrogenase A (LDHA) increased oxygen consumption rate in the hemato-endothelial system and inhibited the emergence of intra-aortic hematopoietic clusters. These findings were corroborated using Tie2-Cre-mediated deletion of Ldha that showed similar effects on hematopoietic emergence. Conversely, stabilization of HIF-1α via inhibition of oxygen-sensing pathway led to decreased oxidative flux and promoted hematopoietic emergence in mid-gestation embryos. Thus, cell-intrinsic regulation of metabolic state overrides oxygenated microenvironment in the aorta to promote a glycolytic metabolic state that is crucial for hematopoietic emergence in mammalian embryos.

Topology-based segmentation of 3D confocal images of emerging hematopoietic stem cells in the zebrafish embryo

Abstract We develop a novel method for image segmentation of 3D confocal microscopy images of emerging hematopoietic stem cells. The method is based on the theory of persistent homology and uses an optimal threshold to select the most persistent cycles in the persistence diagram. This enables the segmentation of the image’s most contrasted and representative shapes. Coupling this segmentation method with a meshing algorithm, we define a pipeline for 3D reconstruction of confocal volumes. Compared to related methods, this approach improves shape segmentation, is more ergonomic to automatize, and has fewer parameters. We apply it to the segmentation of membranes, at subcellular resolution, of cells involved in the endothelial-to-hematopoietic transition (EHT) in the zebrafish embryos.

62 Comparison of N6-methyladenosine modification of mRNA during the bovine and murine oocyte to embryo transition

62 Comparison of N6-methyladenosine modification of mRNA during the bovine and murine oocyte to embryo transition

Analysis of chromosomal structural variations in patients with recurrent spontaneous abortion using optical genome mapping.

Background and aims: Certain chromosomal structural variations (SVs) in biological parents can lead to recurrent spontaneous abortions (RSAs). Unequal crossing over during meiosis can result in the unbalanced rearrangement of gamete chromosomes such as duplication or deletion. Unfortunately, routine techniques such as karyotyping, fluorescence in situ hybridization (FISH), chromosomal microarray analysis (CMA), and copy number variation sequencing (CNV-seq) cannot detect all types of SVs. In this study, we show that optical genome mapping (OGM) quickly and accurately detects SVs for RSA patients with a high resolution and provides more information about the breakpoint regions at gene level. Methods: Seven couples who had suffered RSA with unbalanced chromosomal rearrangements of aborted embryos were recruited, and ultra-high molecular weight (UHMW) DNA was isolated from their peripheral blood. The consensus genome map was created by de novo assembly on the Bionano Solve data analysis software. SVs and breakpoints were identified via alignments of the reference genome GRCh38/hg38. The exact breakpoint sequences were verified using either Oxford Nanopore sequencing or Sanger sequencing. Results: Various SVs in the recruited couples were successfully detected by OGM. Also, additional complex chromosomal rearrangement (CCRs) and four cryptic balanced reciprocal translocations (BRTs) were revealed, further refining the underlying genetic causes of RSA. Two of the disrupted genes identified in this study, FOXK2 [46,XY,t(7; 17)(q31.3; q25)] and PLXDC2 [46,XX,t(10; 16)(p12.31; q23.1)], had been previously shown to be associated with male fertility and embryo transit. Conclusion: OGM accurately detects chromosomal SVs, especially cryptic BRTs and CCRs. It is a useful complement to routine human genetic diagnostics, such as karyotyping, and detects cryptic BRTs and CCRs more accurately than routine genetic diagnostics.

Chromatin remodeling of prostaglandin signaling in smooth muscle enables mouse embryo passage through the female reproductive tract.

Early mammalian development occurs during embryo transit of the female reproductive tract. Transport is orchestrated by secreted oviduct fluid, unidirectional beating of epithelial cilia, and smooth muscle contractions. Using gene-edited mice, we document that conditional disruption of a component of the SWI/SNF chromatin remodeling complex in smooth muscle cells prevents transport through the oviduct without perturbing embryogenesis. Analysis with RNA sequencing (RNA-seq), transposase-accessible chromatin with sequencing (ATAC-seq), chromatin immunocleavage sequencing (ChIC-seq), and pharmacologic rescue experiments implicated prostaglandin signaling pathways. In comparison with controls, gene-edited mice had compromised chromatin accessibility at enhancer/promoters of Ptgs2, Pla2g16, Pla2r1, and Ptger3 (EP3) as well as decreased enhancer-promoter interactive looping critical for Ptgs2 (aka Cox-2) expression in a SWI/SNF complex-dependent manner. Treatment of wild-type mice with prostaglandin inhibitors phenocopied the genetically induced defect.

Localization of the Drosophila pioneer factor GAF to subnuclear foci is driven by DNA binding and required to silence satellite repeat expression

The eukaryotic genome is organized to enable the precise regulation of gene expression. This organization is established as the embryo transitions from a fertilized gamete to a totipotent zygote. To understand the factors and processes that drive genomic organization, we focused on the pioneer factor GAGA factor (GAF) that is required for early development in Drosophila. GAF transcriptionally activates the zygotic genome and is localized to subnuclear foci. This non-uniform distribution is driven by binding to highly abundant GA repeats. At GA repeats, GAF is necessary to form heterochromatin and silence transcription. Thus, GAF is required to establish both active and silent regions. We propose that foci formation enables GAF to have opposing transcriptional roles within a single nucleus. Our data support a model in which the subnuclear concentration of transcription factors acts to organize the nucleus into functionally distinct domains essential for the robust regulation of gene expression.

Developmentally programmed histone H3 expression regulates cellular plasticity at the parental-to-early embryo transition.

During metazoan development, the marked change in developmental potential from the parental germline to the embryo raises an important question regarding how the next life cycle is reset. As the basic unit of chromatin, histones are essential for regulating chromatin structure and function and, accordingly, transcription. However, the genome-wide dynamics of the canonical, replication-coupled (RC) histones during gametogenesis and embryogenesis remain unknown. In this study, we use CRISPR-Cas9-mediated gene editing in Caenorhabditis elegans to investigate the expression pattern and role of individual RC histone H3 genes and compare them to the histone variant, H3.3. We report a tightly regulated epigenome landscape change from the germline to embryos that are regulated through differential expression of distinct histone gene clusters. Together, this study reveals that a change from a H3.3- to H3-enriched epigenome during embryogenesis restricts developmental plasticity and uncovers distinct roles for individual H3 genes in regulating germline chromatin.

The nuclear-to-cytoplasmic ratio drives cellularization in the close animal relative Sphaeroforma arctica

The ratio of nuclear content to cytoplasmic volume (N/C ratio) is a key regulator driving the maternal-to-zygotic transition in most animal embryos. Altering this ratio often impacts zygotic genome activation and deregulates the timing and outcome of embryogenesis.1,2,3 Despite being ubiquitous across animals, little is known about when the N/C ratio evolved to control multicellular development. Such capacity either originated with the emergence of animal multicellularity or was co-opted from the mechanisms present in unicellular organisms.4 An effective strategy to tackle this question is to investigate the close relatives of animals exhibiting life cycles with transient multicellular stages.5 Among these are ichthyosporeans, a lineage of protists undergoing coenocytic development followed by cellularization and cell release.6,7,8 During cellularization, a transient multicellular stage resembling animal epithelia is generated, offering a unique opportunity to examine whether the N/C ratio regulates multicellular development. Here, we use time-lapse microscopy to characterize how the N/C ratio affects the life cycle of the best-studied ichthyosporean model, Sphaeroforma arctica. We uncover that the last stages of cellularization coincide with a significant increase in the N/C ratio. Increasing the N/C ratio by reducing the coenocytic volume accelerates cellularization, whereas decreasing the N/C ratio by lowering the nuclear content halts it. Moreover, centrifugation and pharmacological inhibitor experiments suggest that the N/C ratio is locally sensed at the cortex and relies on phosphatase activity. Altogether, our results show that the N/C ratio drives cellularization in S.arctica, suggesting that its capacity to control multicellular development predates animal emergence.

Dynamic changes of 3'UTR length during oocyte-to-zygote transition of in vitro pig embryos.

Alternative polyadenylation (APA) generates different 3'-untranslated regions (3'UTRs) to regulate gene expression and localization, and affects a variety of biological processes. Here, we characterized the 3'UTR dynamics during the oocyte-to-zygote transition by analysing our previously reported porcine single-cell RNA-seq (scRNA-seq) datasets (in vitro matured metaphase II (MII) oocytes, in vitro fertilized zygotes (IVF1) and parthenogenetically activated 1-cell embryos (PA1)). After IVF1 versus MII comparison, dynamic analyses of APA from RNA-seq (DaPars) method identified 139 mRNAs with significantly different 3'UTRs (padj .≤ .05), mainly enriched in cell cycle, regulation of cyclin-dependent protein kinase activity, histone modification, mRNA surveillance, and regulation of actin cytoskeleton. For PA1 versus MII comparison, 105 mRNAs with significantly different 3'UTRs (padj .≤ .05) were identified to be mainly enriched in intracellular transport, mitotic spindle organization, cell cycle, pyruvate metabolism and glycolysis/gluconeogenesis. Furthermore, there were 7 mRNAs with more significant 3'UTR differences (|△PDUI| ≥ 0.45 and |log2 [PDUI ratio]| ≥ 0.59) respectively in IVF1 versus MII (Lrp2bp, Mtfr2, Nhlrc2, Psip1, Smu1, Ssr1 and Wtap) and PA1 versus MII (Asf1b, Dimt1, Nap1l1, Ncoa4, Nudt21, Pnn and Rpl15) comparisons. Integrative genomics viewer analysis further identified that 3'UTRs of Psip1, Smu1, Ssr1 and Wtap had more than 140 nt average length changes, whereas those of Dimt1, Nap1l1 and Rpl15 were shortened with more than 460 nt. Regulatory elements (PAS, CPE, microRNA binding sites and m6 A sites) in 3'UTRs of different lengths were predicted. Our findings provide useful information to further investigate the molecular mechanism of 3'UTR in regulating the oocyte-to-zygote transition of pig embryos.

Selective Translation of Maternal mRNA by eIF4E1B Controls Oocyte to Embryo Transition.

Maternal messenger ribonucleic acids (mRNAs) are driven by a highly orchestrated scheme of recruitment to polysomes and translational activation. However, selecting and regulating individual mRNAs for the translation from a competitive pool of mRNAs are little-known processes. This research shows that the maternal eukaryotic translation initiation factor 4e1b (Eif4e1b) expresses during the oocyte-to-embryo transition (OET), and maternal deletion of Eif4e1b leads to multiple defects concerning oogenesis and embryonic developmental competence during OET. The linear amplification of complementary deoxyribonucleic acid (cDNA) ends, and sequencing (LACE-seq) is used to identify the distinct subset of mRNA and its CG-rich binding sites within the 5' untranslated region (UTR) targeted by eIF4E1B. The proteomics analyses indicate that eIF4E1B-specific bound genes show stronger downregulation at the protein level, which further verify a group of proteins that plays a crucial role in oocyte maturation and embryonic developmental competence is insufficiently synthesized in Eif4e1b-cKO oocytes during OET. Moreover, the biochemical results in vitro are combined to further confirm the maternal-specific translation activation model assembled by eIF4E1B and 3'UTR-associated mRNA binding proteins. The findings demonstrate the indispensability of eIF4E1B for selective translation activation in mammalian oocytes and provide a potential network regulated by eIF4E1B in OET.

On the Biological Role of Histone Acetylation/Deacetylation in the Process of Plant Germination

The transition of embryos in air-dry seeds from a state of dormancy to a state with a highly active metabolism during germination is accompanied by significant changes in both spatial and temporal patterns of gene expression and is controlled by multilevel regulatory networks. The character and degree of acetylation of chromatin proteins depend on the transcriptional activity of chromatin, and are also associated with DNA replication and the cell cycle. Obtaining a complete picture of the involvement of histone modification in seed germination in the future will be useful for increasing crop yields, as a way to assess the quality and viability of seeds before sowing, and will also allow the development of methods for managing the realization of plant genetic potential.

CBP/p300 and HDAC activities regulate H3K27 acetylation dynamics and zygotic genome activation in mouse preimplantation embryos

Epigenome reprogramming after fertilization enables transcriptionally quiescent maternal and paternal chromatin to acquire a permissive state for subsequent zygotic genome activation (ZGA). H3K27 acetylation (H3K27ac) is a well‐established chromatin marker of active enhancers and promoters. However, reprogramming dynamics of H3K27ac during maternal‐to‐zygotic transition (MZT) in mammalian embryos are not well‐studied. By profiling the allelic landscape of H3K27ac during mouse MZT, we show that H3K27ac undergoes three waves of rapid global transitions between oocyte stage and 2‐cell stage. Notably, germinal vesicle oocyte and zygote chromatin are globally hyperacetylated, with noncanonical, broad H3K27ac domains that correlate with broad H3K4 trimethylation (H3K4me3) and open chromatin. H3K27ac marks genomic regions primed for activation including ZGA genes, retrotransposons, and active alleles of imprinted genes. We show that CBP/p300 and HDAC activities play important roles in regulating H3K27ac dynamics and are essential for preimplantation development. Specifically, CBP/p300 acetyltransferase broadly deposits H3K27ac in zygotes to induce the opening of condensed chromatin at putative enhancers and ensure proper ZGA. On the contrary, HDACs revert broad H3K27ac domains to canonical domains and safeguard ZGA by preventing premature expression of developmental genes. In conclusion, coordinated activities of CBP/p300 and HDACs during mouse MZT are essential for ZGA and preimplantation development.

Control of Maternal-to-Zygotic Transition in Human Embryos and Other Animal Species (Especially Mouse): Similarities and Differences.

Maternal-to-zygotic transition (MZT) of the control of early post-fertilization development is a key-event conditioning the fate of the future embryo, fetus and newborn. Because of the relative paucity of data concerning human embryos, due to ethical concerns and the poor availability of human embryos donated for research, most data have to be derived from animal models, among which those obtained using mouse embryos are most prevalent. However, data obtained by studies performed in non-mammalian specie can also provide useful information. For this reason, this review focuses on similarities and differences of MZT control mechanisms in humans and other species, with particular attention to the mouse. A number of molecular pathways controlling MZT in mice and humans are compared, pointing out those that could be at the origin of further focused experimental studies and the development of new diagnostic tools based on the translational medicine principles. Data concerning possible candidate molecules to be included in these studies are identified.

Optimisation of embryo rescue for cold-resistant seedless grapevine

ABSTRACT Embryo rescue is essential for the breeding of seedless grapes, but current protocols are inefficient and limit practical application. Here, we documented factors influencing embryo rescue efficiency using crosses of a cold-resistant seeded hybrid 00-1-5 (‘Muscat Hamburg’ × Vitis amurensis) as the paternal parent with four stenospermocarpic seedless grape cvs., ‘Flame Seedless’, ‘Qinhong No. 2’, ‘Qinhong No. 10’, and ‘Ruby Seedless’. The results showed that treatment of inflorescences with 30∼50 mg·L−1 IBA 14 days before flowering significantly increased the embryo development, germination, and transition to seedling for progeny of each of the four crosses. ‘Qinhong No. 2’ × 00-1-5 and ‘Qinhong No. 10’ × 00-1-5, with a large number of ovules, were cultured on solid and solid–liquid biphase MM3 media respectively, the embryo development rate on solid medium was significantly better than that on solid–liquid biphase medium. ‘Ruby Seedless’, ‘Qinhong No. 2’ and ‘Qinhong No. 10’ are more suitable for embryo rescue as maternal parent. The optimal medium for transforming deformed seedlings into normal seedlings was 2 × MS medium containing 0.2 mg·L−1 6-BA, 0.1 mg·L−1 IAA, and 1.6 mg·L−1 ZnSO4. In total, 311 embryos were rescued successfully, which were considered as potential cold-resistant seedless hybrids.

Maternal Prkce expression in mature oocytes is critical for the first cleavage facilitating maternal‐to‐zygotic transition in mouse early embryos

ObjectivesEarly embryo development is dependent on the regulation of maternal messages stored in the oocytes during the maternal‐to‐zygote transition. Previous studies reported variability of oocyte competence among different inbred mouse strains. The present study aimed to identify the maternal transcripts responsible for early embryonic development by comparing transcriptomes from oocytes of high‐ or low‐ competence mouse strains.Materials and Methods In vitro fertilization embryos from oocytes of different mouse strains were subject to analysis using microarrays, RNA sequencing, real‐time quantitative PCR (RT‐qPCR) analysis, Western blotting, and immunofluorescence. One candidate gene, Prkce, was analysed using Prkce knockout mice, followed by a cRNA rescue experiment.ResultsThe fertilization and 2‐cell rate were significantly higher for FVB/NJ (85.1% and 82.0%) and DBA/2J (79.6% and 76.7%) inbred mouse strains than those for the MRL/lpr (39.9% and 35.8%) and 129S3 (35.9% and 36.6%) strains. Thirty‐nine differentially expressed genes (DEGs) were noted, of which nine were further verified by RT‐qPCR. Prkce knockout mice showed a reduced 2‐cell rate (Prkce +/+ 80.1% vs. Prkce −/− 32.4%) that could be rescued by Prkce cRNA injection (2‐cell rate reached 76.7%). Global transcriptional analysis revealed 143 DEGs in the knockout mice, which were largely composed of genes functioning in cell cycle regulation.ConclusionsThe transcription level of maternal messages such as Prkce in mature oocytes is associated with different 2‐cell rates in select inbred mouse strains. Prkce transcript levels could serve as a potential biomarker to characterize high‐quality mature oocytes.