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PubMed2026

Failures to maintain CpG-methylation of CoRSIVs in bovine sperm are associated with low sire conception.

In brief: Correlated regions of systemic interindividual epigenetic variation (CoRSIVs) are genomic regions with CpG-methylation patterns that differ between individuals, yet are consistent between tissues, within the same individual. Analyzing two groups of Holstein bull methylomes-nine with a high sire-conception rate (SCR) and nine with a low SCR-we found that a common type of CoRSIVs was significantly associated with reduced SCR and is thus suggested as a biomarker for SCR because it was highly methylated in sperm, but failed to retain hypermethylation in the gametes of males with low SCR. Abstract: Correlated regions of systemic interindividual epigenetic variation (CoRSIVs) are genomic regions with CpG-methylation patterns that differ between individuals, yet are consistent between tissues, within the same individual; therefore, their methylation can be profiled in bodily fluids that are easily obtained, such as blood and semen. Bearing in mind the simple epigenetic profiling of CoRSIVs, we tested whether this type of differentially methylated region (DMR) is associated with bovine fertility. Sequence Read Archive (SRA) meth BLAST was used to estimate CoRSIVs methylation status in 18 healthy, representative, and age-matched Holstein bulls, among which nine had high (H) sire-conception rate (SCR), and the other nine had low (L) SCR (group averages of SCR: 3.3 ± 0.6 and -3.8 ± 1.8, respectively). This method was also applied to morula and trophoblast SRA methylomes. Analysis with meth BLAST was effective for most (80%) CoRSIVs and showed that CoRSIVs are reprogrammed during blastocyst formation, although this method was incapable of specifically determining the methylation level in CoRSIVs with retrotransposons. In sperm, the effect of global methylation was evident in a common (25%) type of CoRSIVs that is highly (94.5% ± 4.3%) methylated in sperm. Specifically, a failure to retain hypermethylation in the sperm plus strand was significantly (p < 0.00025) indicative of low SCR. Comparing global DNA methylation using the latter type of CoRSIVs between sperm and blood can be used as a better biomarker for fertility than using other differentially methylated regions with more complex epigenetics.

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PubMed2026

Transcriptomic insights into thermal stress reveal physiological trade-off between thermal stress adaptation and reproductive investment in Spodoptera litura.

Spodoptera litura, a highly polyphagous lepidopteran pest, poses a major threat to agricultural productivity due to its remarkable adaptability to diverse environmental conditions. Although heat stress is known to trigger transcriptional reprogramming in insects, the molecular mechanisms underlying thermal stress responses in S. litura remain poorly understood. In the present study, fourth-instar larvae were exposed to acute heat stress (44 °C) and compared with control conditions (27 ± 1 °C) to investigate heat-induced transcriptional alterations affecting physiology and reproduction. High-quality RNA-Seq data achieved more than 80% mapping efficiency, with a total of 15,782 transcripts were identified. Transcriptome analysis of S. litura larvae showed 323 differentially expressed genes (DEGs), of which 262 genes were significantly upregulated and 61 were downregulated in heat-stressed larvae compared to the control group. The DEGs were associated with stress response, reproduction, signalling, proteostasis, detoxification, oxidative stress, metabolism, development, and chromatin regulation. Heat shock proteins genes, including HSP70, HSP90, and HSP27, together with co-chaperones such as TRET-1, STIP1, and Starvin, were strongly upregulated, indicating enhanced cellular protection against protein damage and oxidative stress under heat stress. Conversely, key reproductive and cell cycle-related genes, including BARR, CAPD2, FEO, CDK2 and MORULA, were significantly downregulated, suggesting reproductive impairment and developmental arrest. RT-qPCR validation corroborated the RNA-Seq findings, demonstrating a heat-induced physiological trade-off that prioritizes survival over reproduction. Consistent with these molecular responses, heat-stressed insects exhibited marked reproductive impairment, including significant reductions in gonadosomatic index, eupyrene sperm bundle count, mating frequency, mating success, female calling behaviour, copulation duration, fecundity, and egg fertility. Collectively, these findings provide comprehensive insights into the molecular basis of thermal adaptation in S. litura and demonstrate that acute heat stress compromises reproductive fitness while activating conserved stress-response pathways that promote short-term survival.

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PubMed2026

Generation of eight-cell embryo-like cells from human pluripotent stem cells.

Mammalian embryonic development is a highly orchestrated process initiated by the fusion of the oocyte with sperm to generate the zygote. In humans, the zygote remains transcriptionally quiescent until the major wave of zygotic genome activation (ZGA) occurs around the eight-cell (8C) stage (day 3 after fertilization). These cells and the derived morula cells are totipotent: they have the capacity to form a whole individual. Our understanding of human totipotency is very limited because of ethical concerns using embryos and the scarcity of material available for research. Recently, we established a controllable transgene-free methodology to generate totipotent eight-cell embryo-like cells (8CLCs) from human pluripotent stem cells (PSCs) in vitro. These 8CLCs are produced using a novel medium, formulated by us, containing specific chemical compounds and cytokines. Here, we provide a detailed protocol for inducing, isolating and characterizing 8CLCs generated with this medium. The induction process can be done either in a stepwise manner (primed-naive-8CLC) that requires only 5 d starting from naive PSCs or directly from primed PSCs, which takes ~7 d. The resulting 8CLCs exhibit transcriptional and epigenetic features resembling those of human 8C embryo cells. On the basis of our experience, we expect that an individual with ~1 year of experience working with human PSC culture would be able to carry out this protocol. Our approach provides a valuable model for studying human early embryogenesis, particularly the molecular events surrounding ZGA.

Journal Article↗

PubMed2025

A long noncoding RNA with enhancer-like function in pig zygotic genome activation.

The zygotic genome activation (ZGA) is crucial for the development of pre-implantation embryos. Long noncoding RNAs (lncRNAs) play significant roles in many biological processes, but the study on their role in the early embryonic development of pigs is limited. In this study, we identify lncFKBPL as an enhancer-type lncRNA essential for pig embryo development. lncFKBPL is expressed from the 4-cell stage to the morula stage in pig embryos, and interference with lncFKBPL leads to a developmental arrest at the 8-cell stage. Mechanistic investigations uncover that lncFKBPL is able to bind to MED8, thereby mediating enhancer activity and regulating FKBPL expression. Additionally, FKBPL interacts with the molecular chaperone protein HSP90AA1, stabilizing CDK9 and boosting its protein-level expression. Elevated CDK9 levels enhance Pol II phosphorylation, facilitating ZGA. Our findings illuminate the role of lncFKBPL as an enhancer lncRNA in pig ZGA regulation and early embryo development, providing a foundation for further exploration in this area.

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