Golden hamsters (Mesocricetus auratus) have been extensively used in biomedical research. With the advent of genome-editing technology, it is now possible to generate gene-knockout hamsters, providing unique research models that cannot be achieved with mice or rats. Therefore, the development of cryopreservation techniques for hamster embryos is in high demand. In this study, we present a simplified vitrification protocol for hamster embryo preservation. In vivo-derived 8-cell or morula embryos (Day 3) were vitrified using Cryotop in modified HECM-3 medium containing ethylene glycol, DMSO, and sucrose. After warming, the embryos were transferred into the uteri of Day 3-pregnant females with a different coat color. The results showed that 21–26% of the transferred embryos developed to the term. The experiments were conducted in a conventional laboratory setting, avoiding direct light exposure. Given the reproducibility of our vitrification protocol, it has broad applicability in laboratories that use hamsters.

Ethanolamine plasmalogens (EPls) and choline plasmalogens (CPls), unique glycerophospholipids may play important roles in milk production and reproduction in postpartum dairy cows. While CPls are more abundant in bovine blood, EPls are predominant in the brain. Brain EPls are the only recognized ligands of G protein-coupled receptor 61 (GPR61), a receptor that co-localizes with GnRH receptors on gonadotrophs. We hypothesized that chemosynthetic CPls stimulate gonadotropin secretion from bovine gonadotrophs, similar to the reported effects of chemosynthetic EPls. Anterior pituitary cells from healthy, post-pubertal heifers, were cultured for 3.5 days and then treated with increasing concentrations (0, 0.7, 7, 70, or 700 pM) of EPl with vinyl-ether-bonded stearic acid and ester-bonded oleic acid (C18:0-C18:1EPl) as a positive control, or CPls with vinyl-ether-bonded stearic acid and ester-bonded oleic acid (C18:0-C18:1CPl), arachidonic acid (C18:0-C20:4CPl), or docosahexaenoic acid (C18:0-C22:6CPl). After 2 h, the medium samples were harvested for FSH and LH assays. C18:0-C18:1EPl (7–700 pM) stimulated basal FSH and LH secretion (P < 0.01). None of the tested CPl concentrations stimulated LH secretion. Only 700 pM of C18:0-C18:1CPl, but not lower concentrations, stimulated FSH secretion (P < 0.05), an effect that was inhibited by a SMAD pathway inhibitor. However, both C18:0-C18:1CPl and C18:0-C20:4CPl synergized with GnRH to stimulate FSH secretion. In silico molecular-docking simulations using the deep-learning algorithm ColabFold revealed that CPls bind to the three-dimensional structural model of GPR61. In conclusion, C18:0-C20:4CPl stimulated FSH secretion exclusively in the presence of GnRH, whereas C18:0-C18:1CPl weakly stimulated FSH secretion and showed potential interaction with the GnRH signaling pathways.

During mouse preimplantation development, zygotic genome activation (ZGA), which synthesizes new transcripts in the embryo, occurs during the 1-cell to 2-cell stage. Embryos at the 1- and 2-cell stages are totipotent, and as embryonic development progresses, their differentiation potential decreases, and the embryos become pluripotent. However, the roles of genes expressed during ZGA in mouse embryonic differentiation remain incompletely understood. Here, we show that periodic tryptophan protein 1 (Pwp1), a WD-repeat protein, is expressed from the ZGA and controls embryonic differentiation at later stages. Developmental potential was reduced when siRNAs or antisense oligonucleotides targeting Pwp1 were introduced into 1-cell stage mouse embryos. Further, Pwp1 knockdown resulted in irregular localization of YAP1 at the morula stage, upregulation of the inner cell mass marker Nanog, and downregulation of the trophectoderm marker Cdx2 at the blastocyst stage. Transcriptome analysis showed that Pwp1 knockdown upregulated ZGA gene expression at the morula stage. Because Pwp1 contributes to H4K20me3 histone modification, these results suggest that Pwp1 is required for mouse preimplantation development to control differentiation-associated genes via H4K20me3 modification. Elucidating the role of Pwp1 in embryonic differentiation is expected to contribute toward the advancement of assisted reproductive technologies.