Ten-eleven translocation (TET) proteins oxidize 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC). 5fC and 5caC can be excised and ...repaired by the base excision repair (BER) pathway, implicating 5mC oxidation in active DNA demethylation. Genome-wide DNA methylation is erased in the transition from metastable states to the ground state of embryonic stem cells (ESCs) and in migrating primordial germ cells (PGCs), although some resistant regions become demethylated only in gonadal PGCs. Understanding the mechanisms underlying global hypomethylation in naive ESCs and developing PGCs will be useful for realizing cellular pluripotency and totipotency. In this study, we found that PRDM14, the PR domain-containing transcriptional regulator, accelerates the TET-BER cycle, resulting in the promotion of active DNA demethylation in ESCs. Induction of Prdm14 expression transiently elevated 5hmC, followed by the reduction of 5mC at pluripotency-associated genes, germline-specific genes and imprinted loci, but not across the entire genome, which resembles the second wave of DNA demethylation observed in gonadal PGCs. PRDM14 physically interacts with TET1 and TET2 and enhances the recruitment of TET1 and TET2 at target loci. Knockdown of TET1 and TET2 impaired transcriptional regulation and DNA demethylation by PRDM14. The repression of the BER pathway by administration of pharmacological inhibitors of APE1 and PARP1 and the knockdown of thymine DNA glycosylase (TDG) also impaired DNA demethylation by PRDM14. Furthermore, DNA demethylation induced by PRDM14 takes place normally in the presence of aphidicolin, which is an inhibitor of G1/S progression. Together, our analysis provides mechanistic insight into DNA demethylation in naive pluripotent stem cells and developing PGCs.
Gene regulatory networks underlying cellular pluripotency are controlled by a core circuitry of transcription factors in mammals, including POU5F1. However, the evolutionary origin and transformation ...of pluripotency-related transcriptional networks have not been elucidated in deuterostomes. PR domain-containing protein 14 (PRDM14) is specifically expressed in pluripotent cells and germ cells, and is required for establishing embryonic stem cells (ESCs) and primordial germ cells in mice. Here, we compared the functions and expression patterns of PRDM14 orthologues within deuterostomes. Amphioxus PRDM14 and zebrafish PRDM14, but not sea urchin PRDM14, compensated for mouse PRDM14 function in maintaining mouse ESC pluripotency. Interestingly, sea urchin PRDM14 together with sea urchin CBFA2T, an essential partner of PRDM14 in mouse ESCs, complemented the self-renewal defect in mouse
KO ESCs. Contrary to the
expression pattern in mouse embryos,
was expressed in motor neurons of amphioxus embryos, as observed in zebrafish embryos. Thus,
expression in motor neurons was conserved in non-tetrapod deuterostomes and the co-option of the PRDM14-CBFA2T complex from motor neurons into pluripotent cells may have maintained the transcriptional network for pluripotency during vertebrate evolution.This article has an associated 'The people behind the papers' interview.
In a vehicle crash analysis which has a strong non-linearity, the prediction accuracy of machine learning (ML) using FE simulations data is considered to depend on the number of training data. In ...this paper, the correlation between the number of training data and prediction accuracy of machine learning was researched using a large number of parametric FE simulation data in the small overlap frontal crash with fractures in vehicle structure.
We conduct an experimental study focusing on the spreading droplet in the vicinity of the boundary line of solid-liquid-gas interface, which is called macroscopic contact line (M-CL). When the ...droplet spreads on the solid surface completely, a very thin film whose thickness is of a few nm is formed ahead of the M-CL. This thin film is so-called precursor film. We pay our attention to the spatio-temporal growth of the precursor film in terms of its thickness and length at an early stage of the droplet spreading. The target system is a tiny droplet of 2-cSt and 5-cSt silicone oil spreading on the glass substrate. We apply confocal laser displacement sensor to measure the temporal variation of the precursor film thickness at a designated point, and the Brewster angle microscope to detect the precursor film ahead of the M-CL and to evaluate its existing length. We show the effects of the liquid viscosity on the development of precursor film through the results of both its length and thickness.
The spark discharge ignition process was investigated using simultaneous temperature measurements of the spark discharges and the initial flame kernel. We were able for the first time to measure a ...time series of emission spectra from the spark discharge and initial flame kernel inside a spark-ignition engine using a spectrometer coupled with a spark plug and optical fiber. The plasma vibrational temperature of the spark discharge can be measured using time series emission spectra from the electrically excited CN* violet band system. The gas rotational temperature of the initial flame kernel can also be measured using emission spectra from OH* radicals (P and R branches). Simultaneously, visualization of the spark discharge and a time series of emission spectra inside a spark-ignition engine were performed under homogeneous mixture conditions, to eliminate the effects of stratification of temperature and mixture concentrations around the spark plug. We discuss thermal energy transfer from the spark discharge to the combustible mixture. The main conclusions that can be drawn from this study are as follows. CN* emission can be detected from the spark discharge, visualized using a high-speed camera during the arc discharge phase. Our results confirmed that the plasma temperature of the spark discharge was nearly 6800K and that thermal energy was transferred from the spark plasma channel to the combustible mixture. The gas temperature of the initial flame kernel approached that of the adiabatic flame temperature.
We proposed capillary zone electrophoresis（CZE）for identifying metal ions（Mg2＋, Ca2＋, Mn2＋, Fe3＋, and Zn2＋）in the common ice plant（Mesembryanthemum crystallinum L.）using complexation with ...trans-cyclohexane-1,2-diaminetetraacetic acid（CyDTA）. Analytes in an extract from the common ice plant were detected simultaneously and were separated from coexisting substances. However, analytical results obtained using the proposed procedures did not agree sufficiently with those obtained using inductively coupled plasma atomic emission spectrometry（ICP-AES）. Results suggest the potential usefulness of the proposed method, but further study must be conducted to improve the method.
The fatigue endurance of TS 590 MPa grade low-alloy precipitation strengthened steel was numerically and experimentally examined. The microstructure was modeled using two-dimensional Voronoi ...polygons. Heterogeneous stress distributions were calculated using the finite element method, taking elastic anisotropy into consideration. The number of cycles before crack initiation was estimated based on the Tanaka–Mura model. By taking into account the effects of the cyclic strain of the preceding cracks, a definable macroscopic crack initiation cycle was obtained. An actual tensile and compression fatigue test was conducted on the same steel. The stress amplitude decreased as the cycle number increased. Distinct dislocation cell structure was not observed by TEM analysis. The experimental strain fatigue limit was, to some extent, lower than that of the simulation. Surface effects, specimen homogeneity, selection of slip system, and dislocation reversibility are mentioned as the probable causes for the difference.
This work clarified the effects of self-assembly of perovskite cesium lead bromide (CsPbBr
3
) nanocubes (NCs) covered with didodecyldimethyl ammonium bromide (DDAB) on photoluminescence (PL) ...properties. Although the PL intensity of isolated NCs was weakened in the solid state even under inert conditions, the quantum yield of PL (PLQY) and the photostability of DDAB-covered NCs were drastically improved by the formation of two-dimensional (2D) ordered arrays on a substrate. The PLQY of the 2D arrays increased to
ca.
60% by initial excitation illumination at 468 nm and was maintained for over 4000 h. The improved PL properties are attributable to the fixation of the surface ligand around the NCs in the specific ordered arrays.
The quantum yield of photoluminescence and the photostability of perovskite cesium lead bromide nanocubes were improved by the formation of two-dimensional ordered arrays on a substrate.
Reduced model of car deformation during frontal impact of NCAP was established from data base of one hundred of FE results. Predicted deformation of front side rail by the reduced model showed good ...correlation to FE sampled results, while the FE sampled results were clustered to four groups by referring buckling modes of front side rail. Relationships between accuracy of the reduced model and clustering of the database were discussed.
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