RESUMO
The metabolic and epigenetic landscapes of the pre-implantation embryo change and evolve rapidly as the embryo travels through the reproductive tract. The maternal and paternal genomes combine, rapid cell division is initiated, potency is re-established and eventually differentiation begins, all in the absence of a vascular supply delivering oxygen, nutrients and a functional waste removal system. In recent years, it has become clear that environmental challenges to the developing embryo, including maternal diet, stress and inflammation, alter its long-term trajectory, although the exact signaling molecules, which are recognised by the embryo, and the mechanisms by which these signals are translated into long-term outcomes, remain elusive. Recently, it has become apparent that energy or fuel-sensing metabolic pathways interact with important epigenetic regulators of chromatin structure, to regulate gene expression. While this has not yet been explored in the pre-implantation embryo, the interaction between these two key cellular systems, - metaboloepigenetics - is a plausible mechanism by which gene-environment interactions occur, and by which the embryos trajectory is established. This review explores the metabolic and epigenetic plasticity of the early embryo, and how the two systems intertwine to propagate the next generation.(AU)
Assuntos
Animais , Epigenômica/métodos , Expressão Gênica/fisiologia , Desenvolvimento Embrionário , MetabolismoRESUMO
An understanding of oocyte and embryo metabolism is critical to understanding and developing in vitro culture systems. In the last 60-70 years there has been a constant evolution in the way metabolism studies have been conducted. This includes a change from studying the metabolism of the oocyte alone vs. as a whole cumulus oocyte complex. The study of in vivo environments has lead to the creation of defined sequential culture systems, resulting in overcoming developmental blocks and improved embryo development. And techniques for studying metabolism have evolved from the use of radiolabelled isotopes to increasingly specific fluorescence probesand metabolomics, allowing for large, integrative profiles. Metabolism is a potential diagnostic for selecting the most likely embryos to implant. We envisage the future of metabolism will involve the ability to measure more-in-less (more substrates, less volumes) and allow for a holistic approach to understanding the relationship between metabolism and developmental competence, as it is unconceivable that a single metabolic output will be able to assess health and/or quality.(AU)
Assuntos
Animais , Oócitos/metabolismo , Desenvolvimento EmbrionárioRESUMO
An understanding of oocyte and embryo metabolism is critical to understanding and developing in vitro culture systems. In the last 60-70 years there has been a constant evolution in the way metabolism studies have been conducted. This includes a change from studying the metabolism of the oocyte alone vs. as a whole cumulus oocyte complex. The study of in vivo environments has lead to the creation of defined sequential culture systems, resulting in overcoming developmental blocks and improved embryo development. And techniques for studying metabolism have evolved from the use of radiolabelled isotopes to increasingly specific fluorescence probesand metabolomics, allowing for large, integrative profiles. Metabolism is a potential diagnostic for selecting the most likely embryos to implant. We envisage the future of metabolism will involve the ability to measure more-in-less (more substrates, less volumes) and allow for a holistic approach to understanding the relationship between metabolism and developmental competence, as it is unconceivable that a single metabolic output will be able to assess health and/or quality.
Assuntos
Animais , Desenvolvimento Embrionário , Oócitos/metabolismoRESUMO
The metabolic and epigenetic landscapes of the pre-implantation embryo change and evolve rapidly as the embryo travels through the reproductive tract. The maternal and paternal genomes combine, rapid cell division is initiated, potency is re-established and eventually differentiation begins, all in the absence of a vascular supply delivering oxygen, nutrients and a functional waste removal system. In recent years, it has become clear that environmental challenges to the developing embryo, including maternal diet, stress and inflammation, alter its long-term trajectory, although the exact signaling molecules, which are recognised by the embryo, and the mechanisms by which these signals are translated into long-term outcomes, remain elusive. Recently, it has become apparent that energy or fuel-sensing metabolic pathways interact with important epigenetic regulators of chromatin structure, to regulate gene expression. While this has not yet been explored in the pre-implantation embryo, the interaction between these two key cellular systems, - metaboloepigenetics - is a plausible mechanism by which gene-environment interactions occur, and by which the embryos trajectory is established. This review explores the metabolic and epigenetic plasticity of the early embryo, and how the two systems intertwine to propagate the next generation.
Assuntos
Animais , Desenvolvimento Embrionário , Epigenômica/métodos , Expressão Gênica/fisiologia , MetabolismoRESUMO
The knowledge concerning redox and reactive oxygen species (ROS)-mediated regulation of early embryo development is scarce and remains controversial. The aim of this work was to determine ROS production and redox state during early in vitro embryo development in sperm-mediated and parthenogenetic activation of bovine oocytes. Sperm-mediated oocyte activation was carried out in IVF-modified synthetic oviductal fluid (mSOF) with frozen-thawed semen. Parthenogenetic activation was performed in TALP plus ionomycin and then in IVF-mSOF with 6-dimethylaminopurine plus cytochalasin B. Embryos were cultured in IVF-mSOF. ROS and redox state were determined at each 2-h interval (7-24âh from activation) by 2',7'-dichlorodihydrofluorescein diacetate and RedoxSensor Red CC-1 fluorochromes respectively. ROS levels and redox state differed between activated and non-activated oocytes (P<0.05 by ANOVA). In sperm-activated oocytes, an increase was observed between 15 and 19âh (P<0.05). Conversely, in parthenogenetically activated oocytes, we observed a decrease at 9âh (P<0.05). In sperm-activated oocytes, ROS fluctuated throughout the 24âh, presenting peaks around 7, 19, and 24âh (P<0.05), while in parthenogenetic activation, peaks were detected at 7, 11, and 17âh (P<0.05). In the present work, we found clear distinctive metabolic patterns between normal and parthenogenetic zygotes. Oxidative activity and ROS production are an integral part of bovine zygote behavior, and defining a temporal pattern of change may be linked with developmental competence.