Safety of embryo cryopreservation: insights from mid-term placental transcriptional changes.

BACKGROUND: In recent years, with benefits from the continuous improvement of clinical technology and the advantage of fertility preservation, the application of embryo cryopreservation has been growing rapidly worldwide. However, amidst this growth, concerns about its safety persist. Numerous studies have highlighted the elevated risk of perinatal complications linked to frozen embryo transfer (FET), such as large for gestational age (LGA) and hypertensive disorders during pregnancy. Thus, it is imperative to explore the potential risk of embryo cryopreservation and its related mechanisms. METHODS: Given the strict ethical constraints on clinical samples, we employed mouse models in this study. Three experimental groups were established: the naturally conceived (NC) group, the fresh embryo transfer (Fresh-ET) group, and the FET group. Blastocyst formation rates and implantation rates were calculated post-embryo cryopreservation. The impact of FET on fetal growth was evaluated upon fetal and placental weight. Placental RNA-seq was conducted, encompassing comprehensive analyses of various comparisons (Fresh-ET vs. NC, FET vs. NC, and FET vs. Fresh-ET). RESULTS: Reduced rates of blastocyst formation and implantation were observed post-embryo cryopreservation. Fresh-ET resulted in a significant decrease in fetal weight compared to NC group, whereas FET reversed this decline. RNA-seq analysis indicated that the majority of the expression changes in FET were inherited from Fresh-ET, and alterations solely attributed to embryo cryopreservation were moderate. Unexpectedly, certain genes that showed alterations in Fresh-ET tended to be restored in FET. Further analysis suggested that this regression may underlie the improvement of fetal growth restriction in FET. The expression of imprinted genes was disrupted in both FET and Fresh-ET groups. CONCLUSION: Based on our experimental data on mouse models, the impact of embryo cryopreservation is less pronounced than other in vitro manipulations in Fresh-ET. However, the impairment of the embryonic developmental potential and the gene alterations in placenta still suggested it to be a risky operation.

Gestational diabetes mellitus suppresses fetal testis development in mice†.

The prevalence of gestational diabetes mellitus (GDM) is increasing rapidly. In addition to the metabolic disease risks, GDM might increase the risks of cryptorchidism in children. However, its mechanism involved in abnormalities of the male reproductive system is still unclear. The purpose of this study was to study the effects of GDM on the development of mouse fetal Leydig cells (FLCs) and Sertoli cells (SCs). Pregnant mice were treated on gestational days 6.5 and 12.5 with streptozotocin (100 mg/kg) or vehicle (sodium citrate buffer). Leydig cell and SC development and functions were evaluated by investigating serum testosterone levels, cell number and distribution, genes, and protein expression. GDM decreased serum testosterone levels, the anogenital distance, and the level of desert hedgehog in SCs of testes of male offspring. FLC number was also decreased in testes of GDM offspring by delaying the commitment of stem Leydig cells into the Leydig cell lineage. RNA-seq showed that FOXL2, RSPO1/ß-catenin signaling was activated and Gsk3ß signaling was inhibited in GDM offspring testis. In conclusion, GDM disrupted reproductive tract and testis development in mouse male offspring via altering genes related to development.

Preferential remineralization of phosphorus from organic matter in river-dominated coastal sediments.

In coastal sediments characterized by substantial terrestrial input, the Redfield ratio may not be adequate to determine whether phosphorus (P) is preferentially remineralized relative to carbon (C). Employing a two end-member δ13C mixing model, we observed a gradual decrease in the fraction of terrestrial organic matter as the distance from the river mouth increased. Consequently, the C/P ratio of sedimentary organic matter before early diagenetic alteration (Cu/Pu) decreased from 213 ± 26 to 126 ± 4. In contrast, the C/P ratio of sedimentary organic matter after early diagenetic alteration (Corg/Porg) increased from 208 ± 32 to 265 ± 23. The deviation of Corg/Porg ratios from Cu/Pu ratios suggests that P was preferentially remineralized from organic matter relative to C. Moreover, the degree of preferential remineralization (DPR) of P, represented by (Corg/Porg)/(Cu/Pu), increased with the distance from the river mouth, suggesting a connection to cross-shelf transport. Besides preferential P remineralization, the control mechanisms for P regeneration from sediments strongly depend on the dissolved oxygen (DO) levels of bottom water. Under oxygenated bottom water (DO >120 µM), the precipitation of Fe oxides reduced benthic DIP flux, resulting in a C/P ratio in flux well above the Cu/Pu ratio (1813 ± 725 vs. 213 ± 26). Conversely, when bottom water DO was low (DO<100 µM), the dissolution of Fe oxides and preferential P remineralization increased DIP fluxes, but the precipitation of authigenic apatite suppressed DIP fluxes, leading to C/P ratios in flux approximating Cu/Pu ratios (129 ± 35 vs. 158 ± 10 and 200 ± 82 vs. 141 ± 7). In a moderate redox state (100 < DO <120 µM), preferential P remineralization and the dissolution of Fe oxides increased DIP fluxes, resulting in C/P ratios in flux below Cu/Pu ratios (29 ± 8 vs. 131 ± 5 and 15 ± 6 vs. 126 ± 4).

Regeneration of sedimentary manganese in coastal sediments deciphered by 224Ra/228Th disequilibria.

Manganese (Mn) is a vital micronutrient and participates in multiple biochemical reactions and enzyme catalytic activities. Its cycling is tightly connected with iron (Fe) and nitrogen (N). Although coastal sediments are recognized as an important source of dissolved Mn to marine waters, this contribution remains inadequately quantified. In the summer of 2019 and 2020, we investigated benthic fluxes of dissolved Mn, Fe and ammonia (NH4+) in the Changjiang Estuary and East China Sea shelf using the 224Ra/228Th disequilibrium approach. Our results showed that the availability of reactive Mn oxides (MnD) played a crucial role in sedimentary Mn regeneration, as revealed by the positive correlation (r = 0.75, P < 0.05) between Mn fluxes and MnD contents. In addition, the positive correlation (r = 0.80, P < 0.01) between the decomposition rates of sedimentary organic matter (NH4+ flux) and Mn fluxes suggested that the reduction of MnD was mainly driven by the organic carbon oxidation. Furthermore, NH4+ and Mn fluxes exhibited an exponential increase against the product of dissolved oxygen concentration (DO) and the amplification factor of sediment surface area (ξ). In this context, ξ represents the rate of bottom water DO pumped into the sediment via physical reworking and bio-irrigation. In contrast to the most efficient Fe released from sediment overlain by hypoxic waters (DO <62.5 µM), the maximum Mn flux (63.5 ± 9.4 mmol m-2 d-1) was observed at sediment with oxygenated bottom waters (DO = 158 µM). This implies that the regeneration of Mn was associated with a more permissive redox state compared to that of Fe. We further demonstrated that Mn flux was 1-2 orders of magnitude higher than those estimated through traditional methods. Therefore, coastal sediments may contribute more Mn to ocean waters than previously thought. The precise estimation of Mn release from coastal sediments holds critical significance for research on the global Mn budget.

Intrauterine hyperglycaemia during late gestation caused mitochondrial dysfunction in skeletal muscle of male offspring through CREB/PGC1A signaling.

BACKGROUND: Maternal diabetes mellitus can influence the development of offspring. Gestational diabetes mellitus (GDM) creates a short-term intrauterine hyperglycaemic environment in offspring, leading to glucose intolerance in later life, but the long-term effects and specific mechanism involved in skeletal muscle dysfunction in offspring remain to be clarified. METHODS: Pregnant mice were divided into two groups: The GDM group was intraperitoneally injected with 100 mg/kg streptozotocin on gestational days (GDs) 6.5 and 12.5, while the control (CTR) group was treated with vehicle buffer. Only pregnant mice whose random blood glucose level was higher than 16.8 mmol/L beginning on GD13.5 were regarded as the GDM group. The growth of the offspring was monitored, and the glucose tolerance test was performed at different time points. Body composition analysis and immunohistochemical methods were used to evaluate the development of lean mass at 8 weeks. The exercise capacity and grip strength of the male mouse offspring were assessed at the same period. Transmission electron microscopy was used to observe the morphology inside skeletal muscle at 8 weeks and as a foetus. The genes and proteins associated with mitochondrial biogenesis and oxidative metabolism were investigated. We also coanalyzed RNA sequencing and proteomics data to explore the underlying mechanism. Chromatin immunoprecipitation and bisulfite-converted DNA methylation detection were performed to evaluate this phenomenon. RESULTS: Short-term intrauterine hyperglycaemia inhibited the growth and reduced the lean mass of male offspring, leading to decreased endurance exercise capacity. The myofiber composition of the tibialis anterior muscle of GDM male offspring became more glycolytic and less oxidative. The morphology and function of mitochondria in the skeletal muscle of GDM male offspring were destroyed, and coanalysis of RNA sequencing and proteomics of foetal skeletal muscle showed that mitochondrial elements and lipid oxidation were consistently impaired. In vivo and in vitro myoblast experiments also demonstrated that high glucose concentrations impeded mitochondrial organisation and function. Importantly, the transcription of genes associated with mitochondrial biogenesis and oxidative metabolism decreased at 8 weeks and during the foetal period. We predicted Ppargc1α as a key upstream regulator with the help of IPA software. The proteins and mRNA levels of Ppargc1α in the skeletal muscle of GDM male offspring were decreased as a foetus (CTR vs. GDM, 1.004 vs. 0.665, p = 0.002), at 6 weeks (1.018 vs. 0.511, p = 0.023) and 8 weeks (1.006 vs. 0.596, p = 0.018). In addition, CREB phosphorylation was inhibited in GDM group, with fewer activated pCREB proteins binding to the CRE element of Ppargc1α (1.042 vs. 0.681, p = 0.037), Pck1 (1.091 vs. 0.432, p = 0.014) and G6pc (1.118 vs. 0.472, p = 0.027), resulting in their decreased transcription. Interestingly, we found that sarcopenia and mitochondrial dysfunction could even be inherited by the next generation. CONCLUSIONS: Short-term intrauterine hyperglycaemia significantly reduced lean mass in male offspring at 8 weeks, resulting in decreased exercise endurance and metabolic disorders. Disrupted organisation and function of the mitochondria in skeletal muscle were also observed among them. Foetal exposure to hyperglycaemia decreased the ratio of phosphorylated CREB and reduced the transcription of Ppargc1α, which inhibited the transcription of downstream genes involving in mitochondrial biogenesis and oxidative metabolism. Abnormal mitochondria, which might be transmitted through aberrant gametes, were also observed in the F2 generation.

No causal effect of genetically determined circulating homocysteine levels on psoriasis in the European population: evidence from a Mendelian randomization study.

Background: Although numerous studies demonstrated a link between plasma homocysteine (Hcy) levels and psoriasis, there still exists a certain level of controversy. Therefore, we conducted a Mendelian randomization study to investigate whether homocysteine plays a causative role in the development or exacerbation of psoriasis. Methods: A two-sample Mendelian randomization (MR) analysis was conducted. Summary-level data for psoriasis were acquired from the latest R9 release results from the FinnGen consortium (9,267 cases and 364,071 controls). Single nucleotide polymorphisms (SNPs) robustly linked with plasma Hcy levels at the genome-wide significance threshold (p < 5 × 10-8) (18 SNPs) were recognized from the genome-wide meta-analysis on total Hcy concentrations (n = 44,147 participants) in individuals of European ancestry. MR analyses were performed utilizing the random-effect inverse variance-weighted (IVW), weighted median, and MR-Egger regression methods to estimate the associations between the ultimately filtrated SNPs and psoriasis. Sensitivity analyses were conducted to evaluate heterogeneity and pleiotropy. Results: MR analyses revealed no causal effects of plasma Hcy levels on psoriasis [IVW: odds ratio (OR) = 0.995 (0.863-1.146), p = 0.941; weighed median method: OR = 0.985 (0.834-1.164), p = 0.862; MR-Egger regression method: OR = 0.959 (0.704-1.305), p = 0.795]. The sensitivity analyses displayed no evidence of heterogeneity and directional pleiotropy, and the causal estimates of Hcy levels were not influenced by any individual SNP. Conclusion: Our study findings did not demonstrate a causal effect of genetically determined circulating Hcy levels on psoriasis.

Sexual behavior and cardiovascular diseases: univariable and multivariable Mendelian randomization.

Background: To assess the relationship of genetically predicted sexual behavior (age at first sex (AFS) and the number of sexual partners (NSP)) on cardiovascular diseases (CVDs). Methods and results: We performed two-sample Mendelian randomization (MR) with publicly available datasets from the UK Biobank and FinnGen Study, and analyzed genome-wide association results for sexual behaviors and twelve types of CVDs. The univariable MR method provided a total effect of AFS and NSP on CVDs, and showed evidence that early AFS rather than NSP was associated with CVDs, including angina pectoris (AP), atrial fibrillation and flutter (AFF), coronary atherosclerosis (CAS), deep vein thrombosis of the lower extremity (DVT-LE), heart failure (HF), hypertension (HTN), ischaemic stroke (IS), and myocardial infarction (MI). Given sex as a social determinant of CVD risk, we used gender-stratified SNPs to investigate gender differences in the development of CVDs. These results showed a stronger causal relationship of AFS on CVDs in females than in males. Further multivariable MR analyses indicated a direct effect after accounting for insomnia, number of days of vigorous physical activity 10 + minutes (VPA 10 + min), and time spent watching television (TV). Two-step MR demonstrated these three risk factors act as a mediator in AFS associated AP/HTN/HF. Conclusions: We provide evidence that early AFS increased the risk of CVDs. These associations may be partly caused by VPA 10 + min, insomnia, and the time spent on TV. The causality of AFS on CVDs in females was stronger than in males. Conversely, genetically predicted NSP was not associated with CVDs.

Cell landscape of larval and adult Xenopus laevis at single-cell resolution.

The rapid development of high-throughput single-cell RNA sequencing technology offers a good opportunity to dissect cell heterogeneity of animals. A large number of organism-wide single-cell atlases have been constructed for vertebrates such as Homo sapiens, Macaca fascicularis, Mus musculus and Danio rerio. However, an intermediate taxon that links mammals to vertebrates of more ancient origin is still lacking. Here, we construct the first Xenopus cell landscape to date, including larval and adult organs. Common cell lineage-specific transcription factors have been identified in vertebrates, including fish, amphibians and mammals. The comparison of larval and adult erythrocytes identifies stage-specific hemoglobin subtypes, as well as a common type of cluster containing both larval and adult hemoglobin, mainly at NF59. In addition, cell lineages originating from all three layers exhibits both antigen processing and presentation during metamorphosis, indicating a common regulatory mechanism during metamorphosis. Overall, our study provides a large-scale resource for research on Xenopus metamorphosis and adult organs.