Search Results (6)

Due to its high efficiency and safety, oocyte vitrification finds broad application in many fields of life sciences, such as clinical assisted reproduction and conservation of animal genetic resources. However, vitrification may cause cellular damage and reduce the quality of oocytes and their cumulus cells (CCs), which could be closely related to disorders in lipid metabolism. At present, the impact of vitrification upon the lipid profile of oocytes and CCs has not been systematically elucidated. In this study, we used porcine germinal vesicle cumulus–oocyte complexes (COCs) as a model to analyze their lipid characteristics after vitrification and in vitro maturation (IVM), utilizing untargeted lipid metabolomics. Our results showed that an overall count of 37 down-regulated and 8 up-regulated differential lipids was identified in the vitrified oocytes. Pathway analysis confirmed the enrichment in glycerophospholipid metabolism and fat digestion and absorption, etc. Combined with transcriptomic analysis, three enriched pathways were revealed, including the AMPK signaling pathway, metabolic pathways, and fatty acid elongation. On the other hand, a total of four down-regulated and eight up-regulated differential lipids were detected in the vitrified CCs. Pathway enrichment implicated autophagy, glycerophospholipid metabolism, etc. A joint analysis of metabolomic and transcriptomic data revealed four enrichment pathways, including cholesterol metabolism, fat digestion and absorption, regulation of lipolysis in adipocytes, and metabolic pathways. Notably, the supplementation of lysophosphatidylcholine during IVM attenuated oxidative stress, enhanced mitochondrial activity, and enhanced the viability and embryonic development of cryopreserved porcine oocytes. The results indicate that vitrification alters lipids in oocytes and CCs, and the supplementation of lipids plays a role in improving the quality of vitrified oocytes. Full article

Declining human fertility worldwide is an attractive research target for the search for “high fertility” genes and pathways to counteract this problem. To study these genes and pathways for high fertility, the superfertile Dummerstorf mouse lines FL1 and FL2 are two unique model organisms representing an improved fertility phenotype. A direct reason for this remarkable characteristic of increased litter size, which reaches >20 pups/litter in both FLs, is the raised ovulation rate by approximately 100%, representing an impressive record in this field. Dummerstorf high-fertility lines incarnate extraordinary and singular models of high-fertility for other species, mostly farm animals, with the aim of improving production and reducing costs. Our main goal is to describe the genetic and molecular pathways to reach their phenotypical excellence, and to reproduce them using the control population. The large litter size and ovulation rate in Dummerstorf lines are mostly due to an increase in the quality of their oocytes, which receive a different intake of fat and are composed of different types and concentrations of fatty acids. As the follicular microenvironment plays a fundamental role during the oocytes development, in the present manuscript, we tried to improve the in vitro maturation technique by mimicking the fatty acid profile of FLs oocytes during the IVM of control oocytes. Currently, the optimization of the IVM system is fundamental mostly for prepubertal girls and oncological patients whose main source of gametes to restore fertility may be their maturation in vitro. Our data suggest that the specific fatty acid composition of FLs COCs can contribute to their high-fertility phenotype. Indeed, COCs from the control line matured in IVM-medium supplemented with C14:0 (high in FL2 COCs) or with C20:0, C21:0, C22:0, and C23:0 (high in FL1 COCs), but also control oocytes without cumulus, whose concentration in long-chain FAs are “naturally” higher, showing a slightly higher maturation rate. These findings represent an important starting point for the optimization of the IVM system using FA supplementation. Full article

Vanillic acid (VA) has shown antioxidant and anti-inflammatory activities in different cell types, but its biological effects in the context of early embryo development have not yet been clarified. In the current study, the impact of VA supplementation during in vitro maturation (IVM) and/or post-fertilization (in vitro culture; IVC) on redox homeostasis, mitochondrial function, AKT signaling, developmental competence, and the quality of bovine pre-implantation embryos was investigated. The results showed that dual exposure to VA during IVM and late embryo culture (IVC3) significantly improved the blastocyst development rate, reduced oxidative stress, and promoted fatty acid oxidation as well as mitochondrial activity. Additionally, the total numbers of cells and trophectoderm cells per blastocyst were higher in the VA-treated group compared to control (p < 0.05). The RT-qPCR results showed down-regulation of the mRNA of the apoptosis-specific markers and up-regulation of AKT2 and the redox homeostasis-related gene TXN in the treated group. Additionally, the immunofluorescence analysis showed high levels of pAKT-Ser473 and the fatty acid metabolism marker CPT1A in embryos developed following VA treatment. In conclusion, the study reports, for the first time, the embryotrophic effects of VA, and the potential linkage to AKT signaling pathway that could be used as an efficacious protocol in assisted reproductive technologies (ART) to improve human fertility. Full article

To address which mitochondria-related nuclear differentially expressed genes (DEGs) and related pathways are altered during human oocyte maturation, single-cell analysis was performed in three oocyte states: in vivo matured (M-IVO), in vitro matured (M-IVT), and failed to mature in vitro (IM-IVT). There were 691 DEGs and 16 mitochondria-related DEGs in the comparison of M-IVT vs. IM-IVT oocytes, and 2281 DEGs and 160 mitochondria-related DEGs in the comparison of M-IVT vs. M-IVO oocytes, respectively. The GO and KEGG analyses showed that most of them were involved in pathways such as oxidative phosphorylation, pyruvate metabolism, peroxisome, and amino acid metabolism, i.e., valine, leucine, isoleucine, glycine, serine, and threonine metabolism or degradation. During the progress of oocyte maturation, the metabolic pathway, which derives the main source of ATP, shifted from glucose metabolism to pyruvate and fatty acid oxidation in order to maintain a low level of damaging reactive oxygen species (ROS) production. Although the immature oocytes could be cultured to a mature stage by an in vitro technique (IVM), there were still some differences in mitochondria-related regulations, which showed that the mitochondria were regulated by nuclear genes to compensate for their developmental needs. Meanwhile, the results indicated that the current IVM culture medium should be optimized to compensate for the special need for further development according to this disclosure, as it was a latent strategy to improve the effectiveness of the IVM procedure. Full article

Glucose or fatty acids (FAs) metabolisms may alter the ovarian follicle environment and thus determine oocyte and the nascent embryo quality. The aim of the experiment was to investigate the effect of selective inhibition of glucose (iodoacetate + DHEA) or FA (etomoxir) metabolism on in vitro maturation (IVM) of bovine COCs (cumulus–oocyte complexes) to investigate oocyte’s development, quality, and energy metabolism. After in vitro fertilization, embryos were cultured to the blastocyst stage. Lipid droplets, metabolome, and lipidome were analyzed in oocytes and cumulus cells. mRNA expression of the selected genes was measured in the cumulus cells. ATP and glutathione relative levels were measured in oocytes. Changes in FA content in the maturation medium were evaluated by mass spectrometry. Our results indicate that only glucose metabolism is substantial to the oocyte during IVM since only glucose inhibition decreased embryo culture efficiency. The most noteworthy differences in the reaction to the applied inhibition systems were observed in cumulus cells. The upregulation of ketone body metabolism in the cumulus cells of the glucose inhibition group suggest possibly failed attempts of cells to switch into lipid consumption. On the contrary, etomoxir treatment of the oocytes did not affect embryo development, probably due to undisturbed metabolism in cumulus cells. Therefore, we suggest that the energy pathways analyzed in this experiment are not interchangeable alternatives in bovine COCs. Full article

Elevated non-esterified fatty acid (NEFA), predominantly palmitic acid (PA), concentrations in blood and follicular fluid are a common feature in maternal metabolic disorders such as obesity. This has a direct negative impact on oocyte developmental competence and the resulting blastocyst quality. We use NEFA-exposure during bovine oocyte in vitro maturation (IVM) as a model to mimic oocyte maturation under maternal metabolic stress conditions. However, the impact of supportive embryo culture conditions on these metabolically compromised zygotes are not known yet. We investigated if the addition of anti-apoptotic, antioxidative and mitogenic factors (namely, Insulin-Transferrin-Selenium (ITS) or serum) to embryo culture media would rescue development and important embryo quality parameters (cell proliferation, apoptosis, cellular metabolism and gene expression patterns) of bovine embryos derived from high PA- or high NEFA-exposed oocytes when compared to controls (exposed to basal NEFA concentrations). ITS supplementation during in vitro culture of PA-exposed oocytes supported the development of lower quality embryos during earlier development. However, surviving blastocysts were of inferior quality. In contrast, addition of serum to the culture medium did not improve developmental competence of PA-exposed oocytes. Furthermore, surviving embryos displayed higher apoptotic cell indices and an aberrant cellular metabolism. We conclude that some supportive embryo culture supplements like ITS and serum may increase IVF success rates of metabolically compromised oocytes but this may increase the risk of reduced embryo quality and may thus have other long-term consequences. Full article