In vitro generation of functional gametes is a promising approach for treating infertility, although faithful replication of meiosis has proven to be a substantial obstacle to deriving haploid gamete ...cells in culture. Here we report complete in vitro meiosis from embryonic stem cell (ESC)-derived primordial germ cells (PGCLCs). Co-culture of PGCLCs with neonatal testicular somatic cells and sequential exposure to morphogens and sex hormones reproduced key hallmarks of meiosis, including erasure of genetic imprinting, chromosomal synapsis and recombination, and correct nuclear DNA and chromosomal content in the resulting haploid cells. Intracytoplasmic injection of the resulting spermatid-like cells into oocytes produced viable and fertile offspring, showing that this robust stepwise approach can functionally recapitulate male gametogenesis in vitro. These findings provide a platform for investigating meiotic mechanisms and the potential generation of human haploid spermatids in vitro.
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•Haploid spermatid-like cells (SLCs) were derived by stepwise differentiation of ESCs•This process completely recapitulated meiosis in vitro, meeting meiotic hallmarks•Intracytoplasmic injection of SLCs produced euploid and fertile offspring
In vitro production of haploid gametes could provide a treatment for infertility, but recapitulating meiosis in culture is a significant roadblock. Zhou et al. report the generation of haploid male gametes from mouse ESCs that can produce viable and fertile offspring, demonstrating functional reproduction of meiosis in vitro.
Abstract
Human gut microbiome is a promising target for managing type 2 diabetes (T2D). Measures altering gut microbiota like oral intake of probiotics or berberine (BBR), a bacteriostatic agent, ...merit metabolic homoeostasis. We hence conducted a randomized, double-blind, placebo-controlled trial with newly diagnosed T2D patients from 20 centres in China. Four-hundred-nine eligible participants were enroled, randomly assigned (1:1:1:1) and completed a 12-week treatment of either BBR-alone, probiotics+BBR, probiotics-alone, or placebo, after a one-week run-in of gentamycin pretreatment. The changes in glycated haemoglobin, as the primary outcome, in the probiotics+BBR (least-squares mean 95% CI, −1.04−1.19, −0.89%) and BBR-alone group (−0.99−1.16, −0.83%) were significantly greater than that in the placebo and probiotics-alone groups (−0.59−0.75, −0.44%, −0.53−0.68, −0.37%, P < 0.001). BBR treatment induced more gastrointestinal side effects. Further metagenomics and metabolomic studies found that the hypoglycaemic effect of BBR is mediated by the inhibition of DCA biotransformation by
Ruminococcus bromii
. Therefore, our study reports a human microbial related mechanism underlying the antidiabetic effect of BBR on T2D. (Clinicaltrial.gov Identifier: NCT02861261).
N6 -methyladenosine (m6 A) is the most common internal modification in eukaryotic mRNA. It is dynamically installed and removed, and acts as a new layer of mRNA metabolism, regulating biological ...processes including stem cell pluripotency, cell differentiation, and energy homeostasis. m6 A is recognized by selective binding proteins; YTHDF1 and YTHDF3 work in concert to affect the translation of m6 A-containing mRNAs, YTHDF2 expedites mRNA decay, and YTHDC1 affects the nuclear processing of its targets. The biological function of YTHDC2, the final member of the YTH protein family, remains unknown. We report that YTHDC2 selectively binds m6 A at its consensus motif. YTHDC2 enhances the translation efficiency of its targets and also decreases their mRNA abundance. Ythdc2 knockout mice are infertile; males have significantly smaller testes and females have significantly smaller ovaries compared to those of littermates. The germ cells of Ythdc2 knockout mice do not develop past the zygotene stage and accordingly, Ythdc2 is upregulated in the testes as meiosis begins. Thus, YTHDC2 is an m6 A-binding protein that plays critical roles during spermatogenesis.
MTOR (mechanistic target of rapamycin) is a widely recognized integrator of signals and pathways key for cellular metabolism, proliferation, and differentiation. Here we show that conditional ...knockout (cKO) of Mtor in either primordial or growing oocytes caused infertility but differentially affected oocyte quality, granulosa cell fate, and follicular development. cKO of Mtor in nongrowing primordial oocytes caused defective follicular development leading to progressive degeneration of oocytes and loss of granulosa cell identity coincident with the acquisition of immature Sertoli cell-like characteristics. Although Mtor was deleted at the primordial oocyte stage, DNA damage accumulated in oocytes during their later growth, and there was a marked alteration of the transcriptome in the few oocytes that achieved the fully grown stage. Although oocyte quality and fertility were also compromised when Mtor was deleted after oocytes had begun to grow, these occurred without overtly affecting folliculogenesis or the oocyte transcriptome. Nevertheless, there was a significant change in a cohort of proteins in mature oocytes. In particular, down-regulation of PRC1 (protein regulator of cytokinesis 1) impaired completion of the first meiotic division. Therefore, MTOR-dependent pathways in primordial or growing oocytes differentially affected downstream processes including follicular development, sex-specific identity of early granulosa cells, maintenance of oocyte genome integrity, oocyte gene expression, meiosis, and preimplantation developmental competence.
This paper proposes a novel non-contact ultrasonic motor based on near field acoustic levitation (NFAL), which is composed four flexure pivot-tilting pads with high-frequency driven by piezoelectric ...actuators (PZTs). The motor adopts a flexible structure with self-adaptive capacity to generate acoustic radiation force and acoustic radiation torque acting on the rotor. A theoretical model by coupling the Reynolds equation with the consideration of the mode shape of the pads and the motion equation of the rotor was introduced. A test apparatus was designed and fabricated to measure the working characteristics of the motor. These results provide a deeper understanding of the working mechanism of the non-contact ultrasonic motor and the proposed motor may have promising potential for automatic industries.
•A self-adapting non-contact ultrasonic motor based on near field acoustic levitation (NFAL) is proposed.•A theoretical model by coupling the Reynolds equation and the motion equation of rotor was introduced.•Resonant frequencies and mode shape of the proposed motor were obtained by FEA and experiment.•Effects of driving voltage and frequency on the vibration amplitude, floating height and revolution speed were studied.•A test apparatus was designed and fabricated to measure the running performance of the proposed motor.
The electrochemical CO2 reduction reaction (CO2RR) offers an environmentally benign pathway for renewable energy conversion and further regulation of the environmental CO2 concentration to achieve ...carbon cycling. However, developing desired electrocatalysts with high CO Faradaic efficiency (FECO) at an ultralow overpotential remains a grand challenge. Herein, we report an effective CO2RR electrocatalyst that features Ag single-atom coordinated with three nitrogen atoms (Ag1–N3) anchored on porous concave N-doped carbon (Ag1–N3/PCNC), which is identified by X-ray absorption spectroscopy. Ag1–N3/PCNC shows a low CO2RR onset potential of −0.24 V, high maximum FECO of 95% at −0.37 V, and high CO partial current density of 7.6 mA cm–2 at −0.55 V, exceeding most of the previous Ag electrocatalysts. The in situ infrared absorption spectra technique proves that Ag1–N3 single-atom sites have sole linear-adsorbed CO and can easily desorb *CO species to achieve the highest CO selectivity in comparison with the corresponding counterparts. This work provides significant inspiration on boosting CO2RR by tuning the active center at an atomic level to achieve a specific absorption with an intermediate.
Urotensin II (UII), a somatostatin-like cyclic peptide, is involved in tumor progression due to its mitogenic effect. Our previous study demonstrated that UII and its receptor UT were up-regulated in ...human hepatocellular carcinoma (HCC), and exogenous UII promoted proliferation of human hepatoma cell line BEL-7402. Hepatic progenitor cell (HPCs) are considered to be one of the origins of liver cancer cells, but their relationship with UII remains unclear. In this work, we aimed to investigate the effect of UII on ROS generation in HPCs and the mechanisms of UII-induced ROS in promoting cell proliferation. Human HCC samples were used to examine ROS level and expression of NADPH oxidase. Hepatic oval cell line WB-F344 was utilized to investigate the underlying mechanisms. ROS level was detected by dihydroethidium (DHE) or 2', 7'-dichlorofluorescein diacetate (DCF-DA) fluorescent probe. For HCC samples, ROS level and expression of NADPH oxidase were significantly up-regulated. In vitro, UII also increased ROS generation and expression of NADPH oxidase in WB-F344 cells. NADPH oxidase inhibitor apocynin pretreatment partially abolished UII-increased phosphorylation of PI3K/Akt and ERK, expression of cyclin E/cyclin-dependent kinase 2. Cell cycle was then analyzed by flow cytometry and UII-elevated S phase proportion was inhibited by apocynin pretreatment. Finally, bromodeoxyuridine (Brdu) incorporation assay showed that apocynin partially abolished UII induced cell proliferation. In conclusion, this study indicates that UII-increased ROS production via the NADPH oxidase pathway is partially associated with activation of the PI3K/Akt and ERK cascades, accelerates G1/S transition, and contributes to cell proliferation. These results showed that UII plays an important role in growth of HPCs, which provides novel evidence for the involvement of HPCs in the formation and pathogenesis of HCC.
The male gamete (sperm) can fertilize an egg, and pass the male genetic information to the offspring. It has long been thought that sperm had a simple protein composition. Efforts have been made to ...identify the sperm proteome in different species, and only about 1000 proteins were reported. However, with advanced mass spectrometry and an optimized proteomics platform, we successfully identified 4675 human sperm proteins, of which 227 were testis-specific. This large number of identified proteins indicates the complex composition and function of human sperm. Comparison with the sperm transcriptome reveals little overlap, which shows the importance of future studies of sperm at the protein level. Interestingly, many signaling pathways, such as the IL-6, insulin and TGF-beta receptor signaling pathways, were found to be overrepresented. In addition, we found that 500 proteins were annotated as targets of known drugs. Three of four drugs studied were found to affect sperm movement. This in-depth human sperm proteome will be a rich resource for further studies of sperm function, and will provide candidate targets for the development of male contraceptive drugs.
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► Proteomic analysis of human sperm indicates unexpected complex protein compositions. ► There is little overlap between sperm proteome and transcriptome. ► Three of four drugs targeting cilia proteins were found to affect sperm movement.
A novel flexure pivot tilting pad squeeze film air bearing (FPTP-SFAB) based on near-field acoustic levitation (NFAL) for a rotor is proposed in this article. The most important advantage of this ...structure is the suitability of the bearing for high-speed and light load conditions because the FPTP can adapt well to squeeze action during operation. The rotating orbit of the rotor can be adjusted according to the machining conditions. A theoretical model is employed to analyze the running characteristics of the rotor by using the coupled NFAL and FPTP model. Experiments were conducted to investigate the running performance of the rotor-bearing system. Moreover, the effects of input voltage, rotational speed, eccentricity ratio, radial clearance, vibration amplitude, and installation method on bearing performance were analyzed. Numerical and experimental results show that a rotor supported by the FPTP-SFAB with a reasonable input excitation magnitude can effectively adjust the rotating orbit of the rotor and inhibit the divergence of the rotor vibration amplitude, thus improving the stability of the rotor-bearing system under complicated and alternating machining conditions.
Non-fasting lipidemia (nFL), mainly contributed by postprandial lipidemia (PL), has recently been recognized as an important cardiovascular disease (CVD) risk as fasting lipidemia (FL). PL serves as ...a common feature of dyslipidemia in Type 2 Diabetes (T2D), albeit effective therapies targeting on PL were limited. In this study, we aimed to evaluate whether the therapy combining probiotics (Prob) and berberine (BBR), a proven antidiabetic and hypolipidemic regimen via altering gut microbiome, could effectively reduce PL in T2D and to explore the underlying mechanism. Blood PL (120 min after taking 100 g standard carbohydrate meal) was examined in 365 participants with T2D from the Probiotics and BBR on the Efficacy and Change of Gut Microbiota in Patients with Newly Diagnosed Type 2 Diabetes (PREMOTE study), a random, placebo-controlled, and multicenter clinical trial. Prob+BBR was superior to BBR or Prob alone in improving postprandial total cholesterol (pTC) and low-density lipoprotein cholesterol (pLDLc) levels with decrement of multiple species of postprandial lipidomic metabolites after 3 months follow-up. This effect was linked to the changes of fecal Bifidobacterium breve level responding to BBR alone or Prob+BBR treatment. Four fadD genes encoding long-chain acyl-CoA synthetase were identified in the genome of this B. breve strain, and transcriptionally activated by BBR. In vitro BBR treatment further decreased the concentration of FFA in the culture medium of B. breve compared to vehicle. Thus, the activation of fadD by BBR could enhance FFA import and mobilization in B. breve and diliminish the intraluminal lipids for absorption to mediate the effect of Prob+BBR on PL. Our study confirmed that BBR and Prob (B. breve) could exert a synergistic hypolipidemic effect on PL, acting as a gut lipid sink to achieve better lipidemia and CVD risk control in T2D.
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