To efficiently produce high-quality bovine calves by transferring embryos obtained from in vitro fertilization (IVF), it is important to evaluate their ability to conceive and their ability to develop into normal litters. In this study, we aimed to clarify the effects of timing and morphology of blastomere cleavage on the gene expression status of bovine IVF embryos. Bovine IVF embryos were classified in four categories, which were divided according to the time of the first blastomere cleavage and the presence or absence of direct cleavage. In addition, the gene expression profiles of these embryos were examined. The timing and morphology of the blastomere cleavage was involved in pre-implantation development and gene expression status of bovine IVF embryos. Our results indicate the possibility of multiple evaluations for bovine IVF embryos and the selection of the most suitable embryos for embryo transfer.

The cauda epididymis protects and stores mature sperm in mammals. Recently, comprehensive transcriptomic and proteomic analyses have been conducted to understand its molecular functions; however, fundamental information on its metabolites has not been reported. In this study, we optimized a system for the comprehensive metabolic analysis of the cauda epididymis in mature and juvenile mice. This system identified 116 and 92 metabolites in mature and juvenile mice, respectively. Comparative analysis revealed that 44 and 13 metabolites were upregulated and downregulated, respectively, in the cauda epididymis of mature and juvenile mice. Based on the identified metabolites, 34 metabolic and unique pathways (mature: four pathways and juvenile: one pathway) were determined. In conclusion, the levels of certain metabolites in the cauda epididymis differed between mature and juvenile mice. These results contribute to understanding of the unique functions of the cauda epididymis based on dynamic changes in metabolites.

Apoptosis is an essential physiological process involved in embryonic development, immune responses, and tissue homeostasis. Despite many studies on pro-apoptotic genes, few reports have directly compared the lethality-inducing potential between them under comparable conditions. In this study, we evaluated the lethality-inducing potential of three representative pro-apoptotic genes, Bax, Casp3, and Casp9, in mouse early embryos under defined conditions using the doxycycline (Dox)-inducible tetracycline-regulated gene expression system in combination with the PiggyBac transposon system. All genes were transcriptionally induced by Dox, and Bax showed the strongest lethal effect, followed by Casp9, while Casp3 did not show any effects. Notably, Bax expression severely impaired blastocyst formation and led to the intense accumulation of the DNA damage marker γH2AX, along with a pronounced increase in the apoptotic cells. These findings suggest that introducing upstream apoptotic regulators leads to the more efficient and widespread activation of the apoptotic cascade. Overall, this study is expected to contribute to a deeper understanding of apoptotic mechanisms and future advancements in regenerative medicine, reproductive engineering, and cancer research.

During spermatogenesis, chromatin remodeling regulated by histone modification is essential for spermatogenic cell development, and multiple epigenetic regulators are involved in this process. Recent studies reported that ATAD2 was a newly discovered cancer/testis factor that functioned in chromatin remodeling in somatic cells by binding acetylated histone. However, the physiological role of ATAD2 in spermatogenesis is largely unknown. In this study, we characterized the expression pattern of ATAD2 in mouse testes and found that the highly expressed ATAD2 in the gonads was lowly expressed in meiotic spermatocytes with distinct localization in nucleus, but highly expressed in round spermatids. By generating Atad2 knockout (KO) mice using CRISPR/Cas9 technology, we revealed that ATAD2 deletion leads to failure of DSB repair and chromosome synapsis in spermatocytes and impairs spermiogenesis in spermatids. Atad2 KO mice were subfertile, as characterized by reduced sperm count, impaired motility, and abnormal morphology. RNA-Seq analysis showed that hundreds of genes were dysregulated in Atad2-KO round spermatids. As revealed by GSEA analysis, the gene set related to spermatid development was downregulated, while gene sets related to chromatin binding and positive and negative DNA-templated transcription were upregulated. In conclusion, our results indicate that ATAD2 contributes to meiotic progression and participates in spermiogenesis by regulating RNA transcription in spermatids.