The piggyBac+TET-on transposon induction system has a high efficiency in integrating exogenous genes in multiple cell types, can precisely integrate to reduce genomic damage, has a flexible gene expression regulation, and a strong genetic stability. When used in conjunction with somatic cell nuclear transfer experiments, it can precisely and effectively reveal the intrinsic mechanisms of early biological development. This study successfully reprogrammed black-boned sheep fibroblasts (SFs) into induced pluripotent stem cells (iPSCs) using the piggyBac+TET-on transposon system and investigated their impact on early embryonic development. Seven exogenous reprogramming factors (bovine OCT4, SOX2, KLF4, cMyc, porcine NANOG, Lin-28, and SV40 Large T) were delivered into SFs, successfully inducing iPSCs. A growth performance analysis revealed that iPSC clones exhibited a raised or flat morphology with clear edges, positive alkaline phosphatase staining, and normal karyotypes. The transcriptome analysis indicated a significant enrichment of iPSCs in oxidative phosphorylation and cell proliferation pathways, with an up-regulated expression of the ATP5B, SDHB, Bcl-2, CDK1, and Cyclin D1 genes and a down-regulated expression of BAX (p < 0.05). Somatic cell nuclear transfer experiments demonstrated that the cleavage rate (85% ± 2.12) and blastocyst rate (52% ± 2.11) of the iPSCs were significantly higher than those of the SFs (p < 0.05). The detection of trilineage marker genes confirmed that the expression levels of endoderm (DCN, NANOS3, FOXA2, FOXD3, SOX17), mesoderm (KDR, CD34, NFH), and ectoderm (NEUROD) markers in iPSCs were significantly higher than in SFs (p < 0.01). The findings demonstrate that black-boned sheep iPSCs possess pluripotency and the potential to differentiate into all three germ layers, revealing the mechanisms by which reprogrammed iPSCs influence early embryonic development and providing a critical foundation for research on sheep pluripotent stem cells.

The intensification of global climate warming exacerbates the issue of heat stress in dairy cows, making the SLICK mutation in the prolactin receptor (PRLR) gene a critical target for enhancing heat tolerance in these animals. This study aims to investigate the effects of CRISPR/Cas9-mediated editing of the PRLR gene on the biological characteristics of bovine fibroblasts and early embryonic development following somatic cell nuclear transfer (SCNT). Using the CRISPR/Cas9 system, we targeted and edited a 20 bp–150 bp region within exon nine of the PRLR gene. After conducting off-target predictions and activity screenings, we identified optimal guide RNA (sgRNA) sequences and established stable transgenic cell lines. Transcriptome sequencing was performed on edited cells to identify key genes and validate their expression profiles. Edited cells were utilized as donor cells for SCNT, during which we assessed oocyte levels of reactive oxygen species (ROS), glutathione (GSH), and mitochondrial function to analyze embryonic developmental performance. We constructed a cellular stress resistance network aimed at mitigating damage transmission while maintaining embryonic developmental homeostasis. This research provides technical support and theoretical reference for genetic editing breeding programs aimed at improving heat tolerance in dairy cattle.

This study designed three sgRNAs (sgRNA139, sgRNA128, and sgRNA109) targeting the prolactin gene receptor (PRLR) in fetal cattle, utilized Cas9 to cleave endogenous DNA, and screened stable cell lines for somatic cell nuclear transfer experiments to investigate the impact of different editing sites on embryonic development. The results showed that sgRNA139 had the highest cleavage efficiency (Fcut = 0.65, Indels = 42.19%), while sgRNA109 had the lowest (Fcut = 0.45, Indels = 35.31%). No significant differences were observed in cell growth status after electroporation (p > 0.05), and the transfection efficiency exceeded 90% after five days of culture. In the evaluation of key embryonic development indicators, sgRNA109 significantly reduced the cleavage rate and blastocyst rate (p < 0.01), whereas sgRNA139 showed no significant effect on the cleavage rate (p > 0.05), but its blastocyst rate was slightly lower than that of the control group (p > 0.05). This study demonstrates that highly specific sgRNAs and stable edited cell lines used as donor cells can significantly regulate the later stages of embryonic development. This study not only provides new experimental evidence for the functional study of the PRLR but also lays an important theoretical foundation for the innovation of molecular breeding technologies in dairy cattle.

This study focuses on optimizing the liquid preservation protocol for Mongolian sheep semen at 17 °C. We systematically compared the protective effects of eight extender formulations on sperm quality and analyzed dynamic metabolic changes under optimal storage conditions via LC-MS/MS metabolomics, aiming to provide experimental evidence for improving semen preservation techniques and to establish a foundation for the selection of preservation media in future germplasm conservation efforts. By comparing eight diluents, a semen preservation formulation for Mongolian sheep was optimized. The eighth diluent, including fructose, lactose, and Tris, effectively sustained sperm motility during liquid storage at 17 °C. To clarify the underlying metabolic mechanism, LC-MS/MS metabolomics identified 2669 metabolites in spermatozoa at storage times of 0, 48, 96, and 144 h. Based on the metabolomics analysis of differential metabolites, three antioxidants including vitamin E (acting as the basic antioxidant protection), lycopene (for targeted inhibition of lipid peroxidation) and resveratrol (suggested to have endogenous protective effects) were used for exogenous addition experiments. Subsequently, the optimal concentrations for addition were screened: resveratrol (25 μM), lycopene (5 μM), and vitamin E (1.5 μM). Verification experiments revealed that each of the three antioxidants could independently sustain sperm viability above 50% for up to 7 days. Moreover, the combined supplementation exhibited a synergistic effect, increasing sperm viability to 55.05%. This study not only elucidates the underlying mechanism of sperm preservation at the metabolic level, but also provides a validated formulation basis and theoretical support for the development of efficient sheep semen preservatives.