Effects of thyroid hormone on mitochondria and metabolism of human preimplantation embryos

The Interplay between Mitochondrial Metabolism and Nasal Mucociliary Function as a Surrogate Method to Diagnose Thyroid Dysfunction: Insights from a Population-Based Study

Aim and Background. This study aims to explore alternative diagnostic methods to assess thyroid function in patients unable to undergo blood tests for thyroid-stimulating hormones (TSH) and thyroxine (T4), such as individuals with trypanophobia, severe medical conditions, or coagulopathy. Considering the impact of thyroid dysfunction on mitochondrial metabolism and the essential role of proper mitochondrial function in ciliary motility, we postulate that assessing nasal ciliary function could serve as a surrogate diagnostic approach for thyroid dysfunction. Methods. This cross-sectional study was performed on individuals with no history of thyroid diseases. The primary endpoint was the diagnostic value of the nasal mucociliary (NMC) test using Iranica Picris (Asteraceae) aqueous extract in differentiating hypo- or hyperthyroidism cases from euthyroid cases. Results. 232 individuals were recruited (71% females, 86% euthyroid). Receiver operating characteristic (ROC) analysis showed a good diagnostic value for the NMC test in differentiating overt hypothyroidism (area under the ROC curve [AUROC] = 0.82, p = 0.004) and its fair value in diagnosing subclinical hyperthyroidism (AUROC = 0.78, p = 0.01) from the euthyroid condition. The NMC test had a significant positive correlation with TSH (r = 0.47, p < 0.001) and a significant negative correlation with T4 (r = -0.32, p < 0.001). The NMC rate was significantly different in distinct thyroid function groups (p < 0.001). Compared with euthyroid cases, the post-hoc analysis showed that the NMC test is significantly higher in overt hypothyroidism (15.06 vs. 21.07 min, p = 0.003) and significantly lower in subclinical hyperthyroidism (15.05 vs. 10.9 min, p = 0.02). Conclusions. The Iranica Picris-based NMC test might serve as a diagnostic method to distinguish overt hypothyroidism and subclinical hyperthyroidism.

Mitochondrial function is enhanced by thyroid hormones during zebra finch development

An organism's response to its environment is largely determined by changes in the energy supplied by aerobic mitochondrial metabolism via adenosine triphosphate (ATP) production. ATP is especially important under energy-demanding conditions, such as during rapid growth. It is currently poorly understood how environmental factors influence energy metabolism and mitochondrial functioning, but recent studies suggest the role of thyroid hormones (TH). TH are key regulators of growth and metabolism and can be flexibly adjusted to environmental conditions, such as environmental temperature or food availability. To test whether TH enhancement is causally linked to mitochondrial function and growth, we provided TH orally at physiological concentrations during the main growth phase in zebra finch (Taeniopygia guttata) nestlings reared in a challenging environment. TH treatment accelerated maximal mitochondrial working capacity-a trait that reflects mitochondrial ATP production, without affecting growth. To our knowledge, this is the first study to characterize the regulation of mitochondria by TH during development in a semi-naturalistic context and to address implications for fitness-related traits, such as growth.

Proteomic Analysis of Domestic Cat Blastocysts and Their Secretome Produced in an In Vitro Culture System without the Presence of the Zona Pellucida

Domestic cat blastocysts cultured without the zona pellucida exhibit reduced implantation capacity. However, the protein expression profile has not been evaluated in these embryos. The objective of this study was to evaluate the protein expression profile of domestic cat blastocysts cultured without the zona pellucida. Two experimental groups were generated: (1) domestic cat embryos generated by IVF and cultured in vitro (zona intact, (ZI)) and (2) domestic cat embryos cultured in vitro without the zona pellucida (zona-free (ZF group)). The cleavage, morula, and blastocyst rates were estimated at days 2, 5 and 7, respectively. Day 7 blastocysts and their culture media were subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS). The UniProt Felis catus database was used to identify the standard proteome. No significant differences were found in the cleavage, morula, or blastocyst rates between the ZI and ZF groups (p > 0.05). Proteomic analysis revealed 22 upregulated and 20 downregulated proteins in the ZF blastocysts. Furthermore, 14 proteins involved in embryo development and implantation were present exclusively in the culture medium of the ZI blastocysts. In conclusion, embryo culture without the zona pellucida did not affect in vitro development, but altered the protein expression profile and release of domestic cat blastocysts.

A Cross-Species Analysis Reveals Dysthyroidism of the Ovaries as a Common Trait of Premature Ovarian Aging

Although the imbalance of circulating levels of Thyroid Hormones (THs) affects female fertility in vertebrates, its involvement in the promotion of Premature Ovarian Aging (POA) is debated. Therefore, altered synthesis of THs in both thyroid and ovary can be a trait of POA. We investigated the relationship between abnormal TH signaling, dysthyroidism, and POA in evolutionary distant vertebrates: from zebrafish to humans. Ovarian T3 signaling/metabolism was evaluated by measuring T3 levels, T3 responsive transcript, and protein levels along with transcripts governing T3 availability (deiodinases) and signaling (TH receptors) in distinct models of POA depending on genetic background and environmental exposures (e.g., diets, pesticides). Expression levels of well-known (Amh, Gdf9, and Inhibins) and novel (miR143/145 and Gas5) biomarkers of POA were assessed. Ovarian dysthyroidism was slightly influenced by genetics since very few differences were found between C57BL/6J and FVB/NJ females. However, diets exacerbated it in a strain-dependent manner. Similar findings were observed in zebrafish and mouse models of POA induced by developmental and long-life exposure to low-dose chlorpyrifos (CPF). Lastly, the T3 decrease in follicular fluids from women affected by diminished ovarian reserve, as well as of the transcripts modulating T3 signaling/availability in the cumulus cells, confirmed ovarian dysthyroidism as a common and evolutionary conserved trait of POA.

Role of Hormones During Gestation and Early Development: Pathways Involved in Developmental Programming

Accumulating evidence suggests that an altered maternal milieu and environmental insults during the intrauterine and perinatal periods of life affect the developing organism, leading to detrimental long-term outcomes and often to adult pathologies through programming effects. Hormones, together with growth factors, play critical roles in the regulation of maternal-fetal and maternal-neonate interfaces, and alterations in any of them may lead to programming effects on the developing organism. In this chapter, we will review the role of sex steroids, thyroid hormones, and insulin-like growth factors, as crucial factors involved in physiological processes during pregnancy and lactation, and their role in developmental programming effects during fetal and early neonatal life. Also, we will consider epidemiological evidence and data from animal models of altered maternal hormonal environments and focus on the role of different tissues in the establishment of maternal and fetus/infant interaction. Finally, we will identify unresolved questions and discuss potential future research directions.

Induction of Oxidative Stress and Alteration of Synaptic Gene Expression in Newborn Hippocampal Granule Cells after Developmental Exposure to Aroclor 1254

INTRODUCTION

Hippocampal newborn neurons integrate into functional circuits where they play an important role in learning and memory. We previously showed that perinatal exposure to Aroclor 1254, a commercial mixture of polychlorinated biphenyls (PCBs) associated with alterations of cognitive function in children, disrupted the normal maturation of excitatory synapses in the dentate gyrus. We hypothesized that hippocampal immature neurons underlie some of the cognitive effects of PCBs.

METHODS

We used newly generated neurons to examine the effects of PCBs in mice following maternal exposure. Newborn dentate granule cells were tagged with enhanced green fluorescent protein using a transgenic mouse line. The transcriptome of the newly generated granule cells was assessed using RNA sequencing.

RESULTS

Gestational and lactational exposure to 6 mg/kg/day of Aroclor 1254 disrupted the mRNA expression of 1,308 genes in newborn granule cells. Genes involved in mitochondrial functions were highly enriched with 154 genes significantly increased in exposed compared to control mice. The upregulation of genes involved in oxidative phosphorylation was accompanied by signs of endoplasmic reticulum stress and an increase in lipid peroxidation, a marker of oxidative stress, in the subgranular zone of the dentate gyrus but not in mature granule cells in the granular zone. Aroclor 1254 exposure also disrupted the expression of synaptic genes. Using laser-captured subgranular and granular zones, this effect was restricted to the subgranular zone, where newborn neurons are located.

CONCLUSION

Our data suggest that gene expression in newborn granule cells is disrupted by Aroclor 1254 and provide clues to the effects of endocrine-disrupting chemicals on the brain.

Transcriptome profiling of blood from common bottlenose dolphins (Tursiops truncatus) in the northern Gulf of Mexico to enhance health assessment capabilities

Following the 2010 Deepwater Horizon disaster and subsequent unusual mortality event, adverse health impacts have been reported in bottlenose dolphins in Barataria Bay, LA including impaired stress response and reproductive, pulmonary, cardiac, and immune function. These conditions were primarily diagnosed through hands-on veterinary examinations and analysis of standard diagnostic panels. In human and veterinary medicine, gene expression profiling has been used to identify molecular mechanisms underlying toxic responses and disease states. Identification of molecular markers of exposure or disease may enable earlier detection of health effects or allow for health evaluation when the use of specialized methodologies is not feasible. To date this powerful tool has not been applied to augment the veterinary data collected concurrently during dolphin health assessments. This study examined transcriptomic profiles of blood from 76 dolphins sampled in health assessments during 2013–2018 in the waters near Barataria Bay, LA and Sarasota Bay, FL. Gene expression was analyzed in conjunction with the substantial suite of health data collected using principal component analysis, differential expression testing, over-representation analysis, and weighted gene co-expression network analysis. Broadly, transcript profiles of Barataria Bay dolphins indicated a shift in immune response, cytoskeletal alterations, and mitochondrial dysfunction, most pronounced in dolphins likely exposed to Deepwater Horizon oiling. While gene expression profiles in Barataria Bay dolphins were altered compared to Sarasota Bay for all years, profiles from 2013 exhibited the greatest alteration in gene expression. Differentially expressed transcripts included genes involved in immunity, inflammation, reproductive failure, and lung or cardiac dysfunction, all of which have been documented in dolphins from Barataria Bay following the Deepwater Horizon oil spill. The genes and pathways identified in this study may, with additional research and validation, prove useful as molecular markers of exposure or disease to assist wildlife veterinarians in evaluating the health of dolphins and other cetaceans.

Territory aggression and energy budget in food-restricted striped hamsters

Food resource availability is one of the most important factors affecting interindividual competition in a variety of animal species. However, the energy budget and territory aggression strategy of small mammals during periods of food restriction remain uncertain. In this study, metabolic rate, body temperature, territory aggression behavior, and fat deposit were measured in male striped hamster (Cricetulus barabensis) restricted by 20% of ad libitum food intake with or without supplementary methimazole. Serum thyroid hormone (tri-iodothyronine, T₃ and thyroxine, T₄), and cytochrome c oxidase (COX) activity in liver, brown adipose tissue, and skeletal muscle, were also measured. Attack latency, total attack times and duration, and the interval duration between attacks of resident hamsters were not significantly changed during food restriction, which was not significantly affected by supplementary methimazole. Metabolic rate and body temperature was significantly increased in food-restricted hamsters following introduction of an intruder, which was not completely blocked by supplementary methimazole. Serum T₃ and T₄ levels and BAT COX activity were not significantly changed following aggression, and were significantly decreased by supplementary methimazole. These findings suggest that striped hamsters increase energy expenditure for territory aggression during food restriction, and consequently lead to excessive energy depletion. Territory aggression behavior may decrease the capacity to cope with food shortage, which may be independent of thyroid hormone.

Effect of prenatal glucocorticoids and thyroid hormones on developmental plasticity of mitochondrial aerobic metabolism, growth and survival: an experimental test in wild great tits

Developmental plasticity is partly mediated by transgenerational effects, including those mediated by the maternal endocrine system. Glucocorticoid and thyroid hormones may play central roles in developmental programming through their action on metabolism and growth. However, the mechanisms by which they affect growth and development remain understudied. One hypothesis is that maternal hormones directly affect the production and availability of energy-carrying molecules (e.g. ATP) by their action on mitochondrial function. To test this hypothesis, we experimentally increased glucocorticoid and thyroid hormones in wild great tit eggs (Parus major) to investigate their impact on offspring mitochondrial aerobic metabolism (measured in blood cells), and subsequent growth and survival. We show that prenatal glucocorticoid supplementation affected offspring cellular aerobic metabolism by decreasing mitochondrial density, maximal mitochondrial respiration and oxidative phosphorylation, while increasing the proportion of the maximum capacity being used under endogenous conditions. Prenatal glucocorticoid supplementation only had mild effects on offspring body mass, size and condition during the rearing period, but led to a sex-specific (females only) decrease in body mass a few months after fledging. Contrary to our expectations, thyroid hormone supplementation did not affect offspring growth or mitochondrial metabolism. Recapture probability as juveniles or adults was not significantly affected by prenatal hormonal treatment. Our results demonstrate that prenatal glucocorticoids can affect post-natal mitochondrial density and aerobic metabolism. The weak effects on growth and apparent survival suggest that nestlings were mostly able to compensate for the transient decrease in mitochondrial aerobic metabolism induced by prenatal glucocorticoids.

Thyroid hormone enhances stem cell maintenance and promotes lineage-specific differentiation in human embryonic stem cells

Background

Thyroid hormone triiodothyronine (T3) is essential for embryogenesis and is commonly used during in vitro fertilization to ensure successful implantation. However, the regulatory mechanisms of T3 during early embryogenesis are largely unknown.

Method

To study the impact of T3 on hPSCs, cell survival and growth were evaluated by measurement of cell growth curve, cloning efficiency, survival after passaging, cell apoptosis, and cell cycle status. Pluripotency was evaluated by RT-qPCR, immunostaining and FACS analysis of pluripotency markers. Metabolic status was analyzed using LC–MS/MS and Seahorse XF Cell Mito Stress Test. Global gene expression was analyzed using RNA-seq. To study the impact of T3 on lineage-specific differentiation, cells were subjected to T3 treatment during differentiation, and the outcome was evaluated using RT-qPCR, immunostaining and FACS analysis of lineage-specific markers.

Results

In this report, we use human pluripotent stem cells (hPSCs) to show that T3 is beneficial for stem cell maintenance and promotes trophoblast differentiation. T3 enhances culture consistency by improving cell survival and passaging efficiency. It also modulates cellular metabolism and promotes energy production through oxidative phosphorylation. T3 helps maintain pluripotency by promoting ERK and SMAD2 signaling and reduces FGF2 dependence in chemically defined culture. Under BMP4 induction, T3 significantly enhances trophoblast differentiation.

Conclusion

In summary, our study reveals the impact of T3 on stem cell culture through signal transduction and metabolism and highlights its potential role in improving stem cell applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02799-y.

Effect of thyroid function on assisted reproduction outcomes in euthyroid infertile women: A single center retrospective data analysis and a systematic review and meta-analysis

BACKGROUND

The influence of thyroid-stimulating hormone (TSH) on gestational outcomes have been studied and checked whether differing TSH levels are relevant on human reproduction outcomes. International guidelines recommend TSH values <2.5 mIU/L in women trying to conceive, since values above this level are related to a higher frequency of adverse reproductive outcomes. This study aimed to evaluate whether TSH values correlate with different gestational outcomes in euthyroid infertile women without autoimmune thyroid disease.

METHODS

A retrospective cohort study was conducted involving 256 women who underwent in vitro fertilization (IVF) treatment. The participants were divided into two groups: TSH 0.5-2.49 mIU/L (n=211) and TSH 2.5-4.5 mIU/L (n=45). The clinical data, hormonal profiles and reproductive outcomes were compared between groups. Additionally, a systematic review with meta-analysis following the PRISMA protocol was carried out in PubMed/MEDLINE, EMBASE, and SciELO, with no time or language restrictions, for articles comparing TSH groups named "low TSH" (<2,5 mIU/L) and "high TSH" (≥2.5 mIU/L). A meta-analysis of proportions was performed with pooled estimates expressed as relative risk (RR) of events and a random effects model.

RESULTS

Age, BMI, free thyroxine levels (FT4) hormonal profile and IVF outcomes were not different between groups, neither gestational outcomes (p=0.982). Also, no difference was observed when the TSH and FT4 levels were compared between patients with positive or negative gestational outcomes (p=0.27 and p=0.376). Regarding the systematic review with meta-analysis, 17 studies from 2006 to 2022 were included, and added by this original retrospective research comprising 13.247 women undergoing IVF. When comparing the proportions of clinical pregnancy between the TSH groups, no significant difference was found (RR 0.93, 95% CI 0.80-1.08), with high between studies heterogeneity (I²: 87%; τ²: 0.0544; p<0.01). The number of deliveries was not significantly different between groups, despite a trend towards higher frequency in the high-TSH group (RR 0.96, 95% CI 0.90-1.02).

CONCLUSION

Variation in TSH levels within the normal range was not associated with pregnancy and delivery rates in women, without autoimmune thyroid disease, who underwent IVF treatment.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD 42022306967.

Placental gene networks at the interface between maternal PM2.5 exposure early in gestation and reduced infant birthweight

BACKGROUND

A growing body of evidence links maternal exposure to particulate matter <2.5 μM in diameter (PM2.5) and deviations in fetal growth. Several studies suggest that the placenta plays a critical role in conveying the effects of maternal PM2.5 exposure to the developing fetus. These include observed associations between air pollutants and candidate placental features, such as mitochondrial DNA content, DNA methylation and telomere length. However, gaps remain in delineating the pathways linking the placenta to air pollution-related health effects, including a comprehensive profiling of placental processes impacted by maternal PM2.5 exposure. In this study, we examined alterations in a placental transcriptome-wide network in relation to maternal PM2.5 exposure prior to and during pregnancy and infant birthweight.

METHODS

We evaluated PM2.5 exposure and placental RNA-sequencing data among study participants enrolled in the Rhode Island Child Health Study (RICHS). Daily residential PM2.5 levels were estimated using a hybrid model incorporating land-use regression and satellite remote sensing data. Distributed lag models were implemented to assess the impact on infant birthweight due to PM2.5 weekly averages ranging from 12 weeks prior to gestation until birth. Correlations were assessed between PM2.5 levels averaged across the identified window of susceptibility and a placental transcriptome-wide gene coexpression network previously generated using the WGCNA R package.

RESULTS

We identified a sensitive window spanning 12 weeks prior to and 13 weeks into gestation during which maternal PM2.5 exposure is significantly associated with reduced infant birthweight. Two placental coexpression modules enriched for genes involved in amino acid transport and cellular respiration were correlated with infant birthweight as well as maternal PM2.5 exposure levels averaged across the identified growth restriction window.

CONCLUSION

Our findings suggest that maternal PM2.5 exposure may alter placental programming of fetal growth, with potential implications for downstream health effects, including susceptibility to cardiometabolic health outcomes and viral infections.

Gene Regulation Network of Prognostic Biomarker YAP1 in Human Cancers: An Integrated Bioinformatics Study

Background: Yes-associated protein 1 (YAP1) is the main downstream effector of the Hippo signaling pathway, which is involved in tumorigenesis. This study aimed to comprehensively understand the prognostic performances of YAP1 expression and its potential mechanism in pan-cancers by mining databases.

Methods: The YAP1 expression was evaluated by the Oncomine database and GEPIA tool. The clinical significance of YAP1 expression was analyzed by the UALCAN, GEPIA, and DriverDBv3 database. Then, the co-expressed genes with YAP1 were screened by the LinkedOmics, and annotated by the Metascape and DAVID database. Additionally, by the MitoMiner 4.0 v tool, the YAP1 co-expressed genes were screened to obtain the YAP1-associated mitochondrial genes that were further enriched by DAVID and analyzed by MCODE for the hub genes.

Results: YAP1 was differentially expressed in human cancers. Higher YAP1 expression was significantly associated with poorer overall survival and disease-free survival in adrenocortical carcinoma (ACC), brain Lower Grade Glioma (LGG), and pancreatic adenocarcinoma (PAAD). The LinkedOmics analysis revealed 923 co-expressed genes with YAP1 in adrenocortical carcinoma, LGG and PAAD. The 923 genes mainly participated in mitochondrial functions including mitochondrial gene expression and mitochondrial respiratory chain complex I assembly. Of the 923 genes, 112 mitochondrial genes were identified by MitoMiner 4.0 v and significantly enriched in oxidative phosphorylation. The MCODE analysis identified three hub genes including CHCHD1, IDH3G and NDUFAF5.

Conclusion: Our findings showed that the YAP1 overexpression could be a biomarker for poor prognosis in ACC, LGG and PAAD. Specifically, the YAP1 co-expression genes were mainly involved in the regulation of mitochondrial function especially in oxidative phosphorylation. Thus, our findings provided evidence of the carcinogenesis of YAP1 in human cancers and new insights into the mechanisms underlying the role of YAP1 in mitochondrial dysregulation.

Interspecific Variation in One-Carbon Metabolism within the Ovarian Follicle, Oocyte, and Preimplantation Embryo: Consequences for Epigenetic Programming of DNA Methylation

One-carbon (1C) metabolism provides methyl groups for the synthesis and/or methylation of purines and pyrimidines, biogenic amines, proteins, and phospholipids. Our understanding of how 1C pathways operate, however, pertains mostly to the (rat) liver. Here we report that transcripts for all bar two genes (i.e., BHMT, MAT1A) encoding enzymes in the linked methionine-folate cycles are expressed in all cell types within the ovarian follicle, oocyte, and blastocyst in the cow, sheep, and pig; as well as in rat granulosa cells (GCs) and human KGN cells (a granulosa-like tumor cell line). Betaine-homocysteine methyltransferase (BHMT) protein was absent in bovine theca and GCs, as was activity of this enzyme in GCs. Mathematical modeling predicted that absence of this enzyme would lead to more volatile S-adenosylmethionine-mediated transmethylation in response to 1C substrate (e.g., methionine) or cofactor provision. We tested the sensitivity of bovine GCs to reduced methionine (from 50 to 10 µM) and observed a diminished flux of 1C units through the methionine cycle. We then used reduced-representation bisulfite sequencing to demonstrate that this reduction in methionine during bovine embryo culture leads to genome-wide alterations to DNA methylation in >1600 genes, including a cohort of imprinted genes linked to an abnormal fetal-overgrowth phenotype. Bovine ovarian and embryonic cells are acutely sensitive to methionine, but further experimentation is required to determine the significance of interspecific variation in BHMT expression.

The toxic effects and possible mechanisms of decabromodiphenyl ethane on mouse oocyte

Decabromodiphenyl ethane (DBDPE), a widely used new brominated flame retardant, is added into flammable materials to achieve fire retardation. As it is continuously detected in the environment, it has become an emerging environmental pollutant. However, the effects of DBDPE exposure on oocyte maturation and its underlying mechanisms remain unknown. This study found that DBDPE exposure inhibited the rate of germinal vesicle breakdown (GVBD), first polar body extrusion (PBE) and fertilization of mouse oocytes. After 14 h of exposure to DBDPE, metaphase II (MII) oocytes showed that the hardness of zona pellucida (ZP) markedly increased and that the spindle morphology was abnormal. Moreover, DBDPE exposure induced abnormal mitochondrial distribution, mitochondrial dysfunction, and ATP deficiency. Simultaneously, DBDPE exposure down-regulated the expression of antioxidant-related genes (Sod2, Gpx1) and increased the level of reactive oxygen species (ROS) in oocytes. The results of immunofluorescence and qRT-PCR revealed that autophagy occurred in DBDPE-treated oocytes with high expression of autophagy-related protein (LC3) and genes (Lc3, Beclin1). Meanwhile, DBDPE significantly up-regulated the protein (Bax) and mRNA (Bax, Caspase3) levels of pro-apoptosis genes. However, the protein and mRNA expression of anti-apoptosis genes Bcl-2 was dramatically down-regulated in DBDPE-exposed oocytes. Collectively, DBDPE exposure impaired mitochondrial function, causing oxidative damage, autophagy and apoptosis in oocytes.

Comparative analysis of cell-free DNA content in culture medium and mitochondrial DNA copy number in porcine parthenogenetically activated embryos

We examined the effect of ploidy on mitochondrial DNA (mtDNA) copy number in embryos and the amount of cell-free mitochondrial and nucleic DNA content (cf-mtDNA and cf-nDNA) in spent culture medium (SCM). Oocytes collected from the ovaries were matured, activated, incubated in medium containing cycloheximide (CHX) or CHX and cytochalasin B (CB) for 4.5 h to produce haploid or diploid embryos (H-group and D-group embryos). These embryos were cultured for 7 days, and the blastocysts and SCM were examined. The amount of mtDNA and nDNA was determined by real-time PCR. The rate of development to the blastocyst stage was higher for the D-group than for the H-group. Moreover, D-group blastocysts had less mtDNA compared to the H-group blastocysts. After activation, the mitochondrial content was constant before the blastocyst stage in D-group embryos, but increased earlier in H-group embryos. The amount of cf-mtDNA in the SCM of D-group blastocysts was greater than that of H-group blastocysts. However, when the cf-mtDNA in the SCM of 2 cell-stage embryos (day 2 post-activation) was examined, the amount of cf-mtDNA was greater in the H-group than in the D-group embryos. When D-group embryos were cultured for 7 days, a significant correlation was observed between the total cell number of blastocysts and cf-nDNA content in the SCM. Hence, although careful consideration is needed regarding the time point for evaluating mtDNA content in the embryos and SCM, this study demonstrates that mtDNA in the embryos and SCM was affected by the ploidy of the embryos.

Growing cattle embryos beyond Day 8 - An investigation of media components

The growth of viable cattle embryos in culture to stages beyond the hatching blastocyst is of interest to developmental biologists wishing to understand developmental events beyond the first lineage decision, as well as for commercial applications, because a lengthening of the culturing time allows more time for diagnostic tests on biopsies, whereas extended survival can be used as a better assay system for monitoring developmental potential. We here report on a novel extended culture medium for embryo growth until embryonic day (Day) 12. We used a non-invasive morphological characterisation system that scored viability, inner cell mass (ICM) grade, hatching and embryo and ICM diameter. The basal medium was based on published uterine fluid concentrations of amino acids, carbohydrates and electrolytes. Addition of fetal bovine serum was necessary and the additive ITSX greatly improved culture success. We tested the inclusion of a seven-growth factor cocktail consisting of Activin A, Artemin, BMP4, EGF, FGF4, GM-CSF/CSF2 and LIF, as well as omission of individual components of the cocktail. In the context of the growth factor cocktail, Artemin and BMP4 provided the greatest benefit, while FGF omission had more positive than negative effects on embryo characteristics. Lastly, replacement of ITSX by B27-additive led to the most successful culture of embryos, in all media permutations.

Thyroid Hormone Signaling in Embryonic Stem Cells: Crosstalk with the Retinoic Acid Pathway

While the role of thyroid hormones (THs) during fetal and postnatal life is well-established, their role at preimplantation and during blastocyst development remains unclear. In this study, we used an embryonic stem cell line isolated from rat (RESC) to study the effects of THs and retinoic acid (RA) on early embryonic development during the pre-implantation stage. The results showed that THs play an important role in the differentiation/maturation processes of cells obtained from embryoid bodies (EB), with thyroid hormone nuclear receptors (TR) (TRα and TRβ), metabolic enzymes (deiodinases 1, 2, 3) and membrane transporters (Monocarboxylate transporters -MCT- 8 and 10) being expressed throughout in vitro differentiation until the Embryoid body (EB) stage. Moreover, thyroid hormone receptor antagonist TR (1-850) impaired RA-induced neuroectodermal lineage specification. This effect was significantly higher when cells were treated with retinoic acid (RA) to induce neuroectodermal lineage, studied through the gene and protein expression of nestin, an undifferentiated progenitor marker from the neuroectoderm lineage, as established by nestin mRNA and protein regulation. These results demonstrate the contribution of the two nuclear receptors, TR and RA, to the process of neuroectoderm maturation of the in vitro model embryonic stem cells obtained from rat.

Effects of thyroid hormone on mitochondria and metabolism of human preimplantation embryos

Thyroid hormones are regarded as the major controllers of metabolic rate and oxygen consumption in mammals. Although it has been demonstrated that thyroid hormone supplementation improves bovine embryo development in vitro, the cellular mechanisms underlying these effects are so far unknown. In this study, we investigated the role of thyroid hormone in development of human preimplantation embryos. Embryos were cultured in the presence or absence of 10-7  M triiodothyronine (T3) till blastocyst stage. Inner cell mass (ICM) and trophectoderm (TE) were separated mechanically and subjected to RNAseq or quantification of mitochondrial DNA copy number. Analyses were performed using DESeq (v1.16.0 on R v3.1.3), MeV4.9 and MitoMiner 4.0v2018 JUN platforms. We found that the exposure of human preimplantation embryos to T3 had a profound impact on nuclear gene transcription only in the cells of ICM (1178 regulated genes-10.5% of 11 196 expressed genes) and almost no effect on cells of TE (38 regulated genes-0.3% of expressed genes). The analyses suggest that T3 induces in ICM a shift in ribosome and oxidative phosphorylation activity, as the upregulated genes are contributing to the composition and organization of the respiratory chain and associated cofactors involved in mitoribosome assembly and stability. Furthermore, a number of genes affecting the citric acid cycle energy production have reduced expression. Our findings might explain why thyroid disorders in women have been associated with reduced fertility and adverse pregnancy outcome. Our data also raise a possibility that supplementation of culture media with T3 may improve outcomes for women undergoing in vitro fertilization.