Rahman Mohammad Bozlur, Held-Hoelker Eva, Saeed-Zidane Mohammed, Rings Franca, Salilew-Wondim Dessie, Tesfaye Dawit, Gad Ahmed, Gebremedhn Samuel, Tholen Ernst, Schellander Karl, Große-Brinkhaus Christine, Hoelker Michael
Institute of Animal Sciences, Animal Breeding, University of Bonn, Endenicher Allee 15, Bonn, 53115, Germany.
Department of Animal Science, Biotechnology and Reproduction of farm animals, University of Goettingen, Burckhardtweg 2, Göttingen, 37077, Germany.
BMC Genomics. 2025 Jul 17;26(1):673. doi: 10.1186/s12864-025-11848-8.
Although differences between in vivo and in vitro derived bovine blastocysts in terms of global gene expression profiles have been reported, comparative transcriptome analyses specifically addressing the sustained impact of the oocyte source or the in vitro culture environments during maturation and post-maturation period are remain limited. Therefore, the present study aimed to investigate the specific impacts of oocyte origin and the culture environment during and after maturation on the gene expression signature at blastocyst stage. To achieve this, we utilized our recently developed technique that enables intrafollicular transfer of immature and matured slaughterhouse-derived oocytes into dominant or preovulatory follicles.
The presents study identified a total of 1052 differentially expressed genes between in vitro and in vivo derived blastocysts, many of which are involved in key pathways related to protein synthesis, protein degradation and cell-cycle regulation. The majority of these genes (n = 913), particularly those associated with "ubiquitin mediated proteolysis", "proteasome activity" as well as "cell cycle" related pathways, were differentially expressed due to the in vitro environment following oocyte maturation. Moreover, a distinct set of genes (n = 109) including DHCR7, DHCR24, HMGCR, HMGCS1 and SCD5, which are crucial for cholesterol biosynthesis and lipid metabolism, were altered in response to the in vitro environment during oocyte maturation. Notably, the origin of the immature oocyte also appeared to predetermine the later expression outline of a set of genes (n = 28), including DLD and PLAC8, which are implicated in implantation success and calf delivery.
The present study provides a comprehensive overview of transcriptomic alterations and pathway disruptions resulting from the in vitro environment following oocyte maturation, offering insight into potential mechanisms underlying embryonic genome activation, DNA duplication and appropriate cell cleavage. The differential expression of genes involved in cholesterol biosynthesis and lipid metabolism due to the in vitro maturation environment may contribute to the reduced cryotolerance observed in the resulting blastocysts. Furthermore, dysregulation of specific genes as a consequence of oocyte source has implications for post-implantation developmental competence. Collectively, these findings advance our understanding of the molecular determinants affecting embryonic developmental potential. The expression signature of these pathways could therefore be used to assess the impact of various treatments and culture environments on embryonic development. In addition, the insights gained from this study could inform future strategies to improve the quality of embryos in in vitro production systems through the targeted modulation, either enhancement or inhibition, of specific genes or pathways.
尽管已有报道称体内和体外来源的牛囊胚在整体基因表达谱方面存在差异，但针对卵母细胞来源或体外培养环境在成熟和成熟后期的持续影响进行的比较转录组分析仍然有限。因此，本研究旨在探讨卵母细胞来源以及成熟期间和成熟后的培养环境对囊胚阶段基因表达特征的具体影响。为实现这一目标，我们利用了我们最近开发的技术，该技术能够将未成熟和成熟的屠宰场来源的卵母细胞卵泡内转移到优势卵泡或排卵前卵泡中。
本研究共鉴定出体外和体内来源的囊胚之间有1052个差异表达基因，其中许多基因参与了与蛋白质合成、蛋白质降解和细胞周期调控相关的关键途径。这些基因中的大多数（n = 913），特别是那些与“泛素介导的蛋白水解”、“蛋白酶体活性”以及“细胞周期”相关途径有关的基因，由于卵母细胞成熟后的体外环境而差异表达。此外，一组独特的基因（n = 109），包括对胆固醇生物合成和脂质代谢至关重要的DHCR7、DHCR24、HMGCR、HMGCS1和SCD5，在卵母细胞成熟期间因体外环境而发生改变。值得注意的是，未成熟卵母细胞的来源似乎也预先决定了一组基因（n = 28）的后期表达概况，这些基因包括与着床成功和犊牛分娩有关的DLD和PLAC8。
本研究全面概述了卵母细胞成熟后体外环境导致的转录组改变和途径破坏，深入了解了胚胎基因组激活、DNA复制和适当细胞分裂的潜在机制。由于体外成熟环境导致的参与胆固醇生物合成和脂质代谢的基因差异表达，可能导致所产生囊胚的冷冻耐受性降低。此外，卵母细胞来源导致的特定基因失调对着床后发育能力有影响。总体而言，这些发现推进了我们对影响胚胎发育潜力的分子决定因素的理解。因此，这些途径的表达特征可用于评估各种处理和培养环境对胚胎发育的影响。此外，本研究获得的见解可为未来通过针对性调节特定基因或途径（增强或抑制）来提高体外生产系统中胚胎质量的策略提供参考。
