bims-gamemb 2021-12-12 papers

bims-gamemb

Biomed News

on Gamete and embryo metabolism

Issue of 2021–12–12
nine papers selected by
Cameron A. Schmidt, East Carolina University

The proteome, not the transcriptome, predicts that oocyte superovulation affects embryonic phenotypes in mice.
Human Sperm Remain Motile After a Temporary Energy Restriction but do Not Undergo Capacitation-Related Events.
Oocyte Survival and Development during Follicle Formation and Folliculogenesis in Mice Lacking Aromatase.
Nuclear NAD+-biosynthetic enzyme NMNAT1 facilitates development and early survival of retinal neurons.
Starvation to Glucose Reprograms Development of Neurovascular Unit in Embryonic Retinal Cells.
Key Metabolite Differences Between Korean Pine (Pinus koraiensis) Seeds With Primary Physiological Dormancy and No-Dormancy.
Non-invasive Metabolomic Profiling of Embryo Culture Medium Using Raman Spectroscopy With Deep Learning Model Predicts the Blastocyst Development Potential of Embryos.
Comparison of two culture media on morphokinetics and ploidy status of sibling embryos.
Mitochondria in Early Forebrain Development: From Neurulation to Mid-Corticogenesis.

Sci Rep. 2021 Dec 09. 11(1): 23731

The proteome, not the transcriptome, predicts that oocyte superovulation affects embryonic phenotypes in mice.

Leila Taher, Steffen Israel, Hannes C A Drexler, Wojciech Makalowski, Yutaka Suzuki, Georg Fuellen, Michele Boiani.

Superovulation is the epitome for generating oocytes for molecular embryology in mice, and it is used to model medically assisted reproduction in humans. However, whether a superovulated oocyte is normal, is an open question. This study establishes for the first time that superovulation is associated with proteome changes that affect phenotypic traits in mice, whereas the transcriptome is far less predictive. The proteins that were differentially expressed in superovulated mouse oocytes and embryos compared to their naturally ovulated counterparts were enriched in ontology terms describing abnormal mammalian phenotypes: a thinner zona pellucida, a smaller oocyte diameter, increased frequency of cleavage arrest, and defective blastocyst formation, which could all be verified functionally. Moreover, our findings indicate that embryos with such abnormalities are negatively selected during preimplantation, and ascribe these abnormalities to incomplete ovarian maturation during the time of the conventional superovulation, since they could be corrected upon postponement of the ovulatory stimulus by 24 h. Our data place constraints on the common view that superovulated oocytes are suitable for drawing general conclusions about developmental processes, and underscore the importance of including the proteins in a modern molecular definition of oocyte quality.

DOI: https://doi.org/10.1038/s41598-021-03054-9
Front Cell Dev Biol. 2021 ;9 777086

Human Sperm Remain Motile After a Temporary Energy Restriction but do Not Undergo Capacitation-Related Events.

Clara I Marín-Briggiler, Guillermina M Luque, María G Gervasi, Natalia Oscoz-Susino, Jessica M Sierra, Carolina Mondillo, Ana M Salicioni, Darío Krapf, Pablo E Visconti, Mariano G Buffone.

  To acquire fertilization competence, mammalian sperm must undergo several biochemical and physiological modifications known as capacitation. Despite its relevance, the metabolic pathways that regulate the capacitation-related events, including the development of hyperactivated motility, are still poorly described. Previous studies from our group have shown that temporary energy restriction in mouse sperm enhanced hyperactivation, in vitro fertilization, early embryo development and pregnancy rates after embryo transfer, and it improved intracytoplasmic sperm injection results in the bovine model. However, the effects of starvation and energy recovery protocols on human sperm function have not yet been established. In the present work, human sperm were incubated for different periods of time in medium containing glucose, pyruvate and lactate (NUTR) or devoid of nutrients for the starving condition (STRV). Sperm maintained in STRV displayed reduced percentages of motility and kinematic parameters compared to cells incubated in NUTR medium. Moreover, they did not undergo hyperactivation and showed reduced levels of ATP, cAMP and protein tyrosine phosphorylation. Similar to our results with mouse sperm, starvation induced increased intracellular Ca2+ concentrations. Starved human sperm were capable to continue moving for more than 27 h, but the incubation with a mitochondrial uncoupler or inhibitors of oxidative phosphorylation led to a complete motility loss. When exogenous nutrients were added back (sperm energy recovery (SER) treatment), hyperactivated motility was rescued and there was a rise in sperm ATP and cAMP levels in 1 min, with a decrease in intracellular Ca2+ concentration and no changes in sperm protein tyrosine phosphorylation. The finding that human sperm can remain motile for several hours under starvation due to mitochondrial use of endogenous metabolites implies that other metabolic pathways may play a role in sperm energy production. In addition, full recovery of motility and other capacitation parameters of human sperm after SER suggests that this treatment might be used to modulate human sperm fertilizing ability in vitro.

Keywords:  ATP; capacitation; glucose; glycolysis; metabolism; oxidative phosphorylation; pyruvate/lactate; sperm motility

DOI:  https://doi.org/10.3389/fcell.2021.777086
Endocr Res. 2021 Dec 04. 1-11

Oocyte Survival and Development during Follicle Formation and Folliculogenesis in Mice Lacking Aromatase.

Jessica M Toothaker, Kristen Roosa, Alexandra Voss, Suzanne M Getman, Melissa E Pepling.

  Background: Assembly of oocytes into primordial follicles is essential for establishing the ovarian reserve required for female fertility. In mice, this process begins during embryonic development. Primordial germ cells form cysts by incomplete mitosis until 13.5 days post coitum (dpc). These cysts break apart just before birth. Some oocytes undergo apoptosis while surviving oocytes are enclosed by granulosa cells to form primordial follicles. Cyst breakdown and primordial follicle formation were previously shown to be inhibited by estradiol and estrogenic compounds in vitro, suggesting that estrogen is important for regulation of this process. Methods: To determine the role of fetal estrogen in cyst breakdown and follicle formation these processes were quantified in aromatase deficient (ArKO) mice between 17.5 dpc and postnatal day (PND) 9. Ovaries of ArKO mice were also examined at 2-week intervals to determine if folliculogenesis is affected by lack of estrogen and the age at which the typical ArKO ovarian phenotype first appears. Results: Oocyte number, follicle assembly, and follicle development in ArKO mice did not differ from controls between 17.5 dpc and PND 9. At 2 weeks, ArKO ovaries still had oocytes in cysts while all oocytes were enclosed in follicles in wild type ovaries. From 2 to 8 weeks oocyte numbers were similar in all genotypes with a significant reduction at 10 weeks in ovaries from homozygous mutants. Abnormal hemorrhagic follicles were observed starting at 6 weeks, earlier than previously reported and hemosiderin deposits were found starting at 8 weeks. Conclusions: These results suggest that a lack of fetal estrogen does not affect oocyte survival or the rate of primordial follicle formation perinatally, and maternal estrogen or other signals are the chief regulators. The appearance of abnormal hemorrhagic follicles observed as early as 6 weeks suggests that the lack of estrogen becomes problematic at this time.

Keywords:  Aromatase; follicle development; oocyte survival; steroid hormone biosynthesis

DOI:  https://doi.org/10.1080/07435800.2021.2011907
Elife. 2021 Dec 08. pii: e71185. [Epub ahead of print]10

Nuclear NAD+-biosynthetic enzyme NMNAT1 facilitates development and early survival of retinal neurons.

David Sokolov, Emily R Sechrest, Yekai Wang, Connor Nevin, Jianhai Du, Saravanan Kolandaivelu.

  Despite mounting evidence that the mammalian retina is exceptionally reliant on proper NAD+ homeostasis for health and function, the specific roles of subcellular NAD+ pools in retinal development, maintenance, and disease remain obscure. Here, we show that deletion of the nuclear-localized NAD+ synthase nicotinamide mononucleotide adenylyltransferase-1 (NMNAT1) in the developing murine retina causes early and severe degeneration of photoreceptors and select inner retinal neurons via multiple distinct cell death pathways. This severe phenotype is associated with disruptions to retinal central carbon metabolism, purine nucleotide synthesis, and amino acid pathways. Furthermore, transcriptomic and immunostaining approaches reveal dysregulation of a collection of photoreceptor and synapse-specific genes in NMNAT1 knockout retinas prior to detectable morphological or metabolic alterations. Collectively, our study reveals previously unrecognized complexity in NMNAT1-associated retinal degeneration and suggests a yet-undescribed role for NMNAT1 in gene regulation during photoreceptor terminal differentiation.

Keywords:  developmental biology; mouse; neuroscience

DOI:  https://doi.org/10.7554/eLife.71185
Front Cell Dev Biol. 2021 ;9 726852

Starvation to Glucose Reprograms Development of Neurovascular Unit in Embryonic Retinal Cells.

Türküler Özgümüs, Oksana Sulaieva, Ruchi Jain, Isabella Artner, Valeriya Lyssenko.

  Perinatal exposure to starvation is a risk factor for development of severe retinopathy in adult patients with diabetes. However, the underlying mechanisms are not completely understood. In the present study, we shed light on molecular consequences of exposure to short-time glucose starvation on the transcriptome profile of mouse embryonic retinal cells. We found a profound downregulation of genes regulating development of retinal neurons, which was accompanied by reduced expression of genes encoding for glycolytic enzymes and glutamatergic signaling. At the same time, glial and vascular markers were upregulated, mimicking the diabetes-associated increase of angiogenesis-a hallmark of pathogenic features in diabetic retinopathy. Energy deprivation as a consequence of starvation to glucose seems to be compensated by upregulation of genes involved in fatty acid elongation. Results from the present study demonstrate that short-term glucose deprivation during early fetal life differentially alters expression of metabolism- and function-related genes and could have detrimental and lasting effects on gene expression in the retinal neurons, glial cells, and vascular elements and thus potentially disrupting gene regulatory networks essential for the formation of the retinal neurovascular unit. Abnormal developmental programming during retinogenesis may serve as a trigger of reactive gliosis, accelerated neurodegeneration, and increased vascularization, which may promote development of severe retinopathy in patients with diabetes later in life.

Keywords:  neurovascular unit; retinogenesis; retinopathy; starvation; transcriptomic (RNA-seq); transcriptomics

DOI:  https://doi.org/10.3389/fcell.2021.726852
Front Plant Sci. 2021 ;12 767108

Key Metabolite Differences Between Korean Pine (Pinus koraiensis) Seeds With Primary Physiological Dormancy and No-Dormancy.

Yuan Song, Xiaoye Gao, Yunjie Wu.

  Pinus Koraiensis seeds have physiological dormancy. Cold stratification releases seed dormancy. The changes in metabolite profiles of dormant seeds and cold stratified seeds during shorter incubation time in a favorable condition for seed germination have been studied. However, a more-long-term detection of the changes in metabolites in dormant seeds can identify the real metabolic pathways responsible for dormancy. Metabolite composition was investigated in embryo and megagametophyte of primary physiological dormant seeds (DS) of P. Koraiensis collected at 0, 1, 2, 4, and 6 weeks of incubation and of non-primary physiological dormant seeds (NDS) sampled at 0 and 1 week of incubation, seed coat rupture stage, and radicle protrusion stage. Embryos contained higher levels of most metabolites than megagametophyte. Strong accumulation of most metabolites in DS occurred at 1 and 4 weeks of incubation. A larger reduction in the relative levels of most phosphorylated sugars and amino acids in NDS was found between 1-week-incubation and seed coat rupture stage. The relative levels of metabolites involved in carbohydrate metabolism, especially the pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle, were higher in the embryos of 4-week-incubated DS, but the relative contents of intermediate metabolites of most amino acid metabolism were lower compared to 1-week-incubated NDS. We suggested that the disturbed carbohydrate metabolism and amino acid metabolism in the embryos of DS after 4 weeks of incubation maybe related to primary dormancy. Our study provides information for a better understanding of the mechanism of seed dormancy.

Keywords:  Korean pine; dormancy; embryo; germination; megagametophyte; metabolomics

DOI:  https://doi.org/10.3389/fpls.2021.767108
Front Physiol. 2021 ;12 777259

Non-invasive Metabolomic Profiling of Embryo Culture Medium Using Raman Spectroscopy With Deep Learning Model Predicts the Blastocyst Development Potential of Embryos.

Wei Zheng, Shuoping Zhang, Yifan Gu, Fei Gong, Lingyin Kong, Guangxiu Lu, Ge Lin, Bo Liang, Liang Hu.

  Purpose: This study aimed to establish a non-invasive predicting model via Raman spectroscopy for evaluating the blastocyst development potential of day 3 high-quality cleavage stage embryos. Methods: Raman spectroscopy was used to detect the metabolic spectrum of spent day 3 (D3) embryo culture medium, and a classification model based on deep learning was established to differentiate between embryos that could develop into blastocysts (blastula) and that could not (non-blastula). The full-spectrum data for 80 blastula and 48 non-blastula samples with known blastocyst development potential from 34 patients were collected for this study. Results: The accuracy of the predicting method was 73.53% and the main different Raman shifts between blastula and non-blastula groups were 863.5, 959.5, 1,008, 1,104, 1,200, 1,360, 1,408, and 1,632 cm-1 from 80 blastula and 48 non-blastula samples by the linear discriminant method. Conclusion: This study demonstrated that the developing potential of D3 cleavage stage embryos to the blastocyst stage could be predicted with spent D3 embryo culture medium using Raman spectroscopy with deep learning classification models, and the overall accuracy reached at 73.53%. In the Raman spectroscopy, ribose vibration specific to RNA were found, indicating that the difference between the blastula and non-blastula samples could be due to materials that have similar structure with RNA. This result could be used as a guide for biomarker development of embryo quality assessment in the future.

Keywords:  Raman spectroscopy; embryo viability prediction; metabolomic profiling; multilayer perceptron; non-invasive assessment

DOI:  https://doi.org/10.3389/fphys.2021.777259
Zygote. 2021 Dec 09. 1-6

Comparison of two culture media on morphokinetics and ploidy status of sibling embryos.

Michael Urich, Muhammet Rasit Ugur, Fang Li, F Nicholas Shamma, Ahmad Hammoud, Hanh N Cottrell, Sule Dogan.

  To investigate the effects of culture media with different lactate concentrations on early embryonic development, data collected from our patients undergoing preimplantation genetic testing (PGT) were assessed using the EmbryoScope™ time-lapse culturing system. After intracytoplasmic sperm injection (ICSI), sibling oocytes were cultured in the same EmbryoScope (Vitrolife) slides including two different commercially available media. The patients with fewer than five mature oocytes were not included in the analyses. All embryos were hatched on day 3, and trophectoderm biopsies (n = 212) were performed accordingly. PGT for aneuploidy (PGT-A) on biopsied materials was carried out using next generation sequencing. Morphokinetic parameters, fertilization, irregular division, degeneration, blastulation, euploidy, and pregnancy rates of embryos cultured in LifeGlobal Global Total medium (LGGT) and Continuous Single Culture-NX Complete medium (CSCM-NXC) were compared. There were no differences observed in time to pronuclear fade, or in time spent as 2-cell (cc2) and 3-cell (s2), to 4-cell, 5-cell, morula and blastocyst stages (P > 0.05). Embryos reached the 2-cell (t2) and 3-cell (t3) stages significantly faster in LGGT (P < 0.05), whereas embryos grown in CSCM-NXC with lower lactate reached starting blastulation significantly sooner (P = 0.026). However, there were no statistical differences observed in fertilization, blastulation, degeneration, irregular division euploidy, and pregnancy rates between the two groups (P > 0.05). Even though pregnancy and fertilization rates did not indicate statistical differences, results are significant to provide better insight on potential roles of lactate in embryo development. These finding will advance the fundamental knowledge of human embryo development and assisted reproductive technologies.

Keywords:  Euploidy; Low lactate media; Morphokinetics; Preimplantation genetic testing; Time-lapse system

DOI:  https://doi.org/10.1017/S0967199421000927
Front Cell Dev Biol. 2021 ;9 780207

Mitochondria in Early Forebrain Development: From Neurulation to Mid-Corticogenesis.

Ryann M Fame, Maria K Lehtinen.

  Function of the mature central nervous system (CNS) requires a substantial proportion of the body's energy consumption. During development, the CNS anlage must maintain its structure and perform stage-specific functions as it proceeds through discrete developmental stages. While key extrinsic signals and internal transcriptional controls over these processes are well appreciated, metabolic and mitochondrial states are also critical to appropriate forebrain development. Specifically, metabolic state, mitochondrial function, and mitochondrial dynamics/localization play critical roles in neurulation and CNS progenitor specification, progenitor proliferation and survival, neurogenesis, neural migration, and neurite outgrowth and synaptogenesis. With the goal of integrating neurodevelopmental biologists and mitochondrial specialists, this review synthesizes data from disparate models and processes to compile and highlight key roles of mitochondria in the early development of the CNS with specific focus on forebrain development and corticogenesis.

Keywords:  corticogenesis; development; forebrain; metabolism; mitochondria; neural tube closure; neurulation

DOI:  https://doi.org/10.3389/fcell.2021.780207