查看更多>>摘要：The reprogramming of parental epigenomes in human early embryos remains elusive.To what extent the characteristics of parental epigenomes are conserved between humans and mice is currently unknown.Here,we mapped parental haploid epigenomes using human parthenogenetic and androgenetic embryos.Human embryos have a larger portion of genome with parentally specific epigenetic states than mouse embryos.The allelic patterns of epigenetic states for orthologous regions are not conserved between humans and mice.Nevertheless,it is conserved that maternal DNA methylation and paternal H3K27me3 are associated with the repression of two alleles in humans and mice.In addition,for DNA-methylation-dependent imprinting,we report 19 novel imprinted genes and their associated germline differentially methylated regions.Unlike in mice,H3K27me3-dependent imprinting is not observed in human early embryos.Collectively,allele-specific epigenomic reprogramming is different in humans and mice.
查看更多>>摘要：Mitochondria undergo fission and fusion that are critical for cell survival and cancer development,while the regulatory factors for mitochondrial dynamics remain elusive.Herein we found that RNA m6A accelerated mitochondria fusion of colorectal cancer(CRC)cells.Metabolomics analysis and function studies indicated that m6A triggered the generation of glutathione(GSH)via the upregulation of RRM2B—a p53-inducible ribonucleotide reductase subunit with anti-reactive oxygen species potential.This in turn resulted in the mitochondria fusion of CRC cells.Mechanistically,m6A methylation of A1240 at 3'UTR of RRM2B increased its mRNA stability via binding with IGF2BP2.Similarly,m6A methylation of A2212 at the coding sequence(CDS)of OPA1—an essential GTPase protein for mitochondrial inner membrane fusion—also increased mRNA stability and triggered mitochondria fusion.Targeting m6A through the methyltransferase inhibitor STM2457 or the dm6ACRISPR system significantly suppressed mitochondria fusion.In vivo and clinical data confirmed the positive roles of the m6A/mitochondrial dynamics in tumor growth and CRC progression.Collectively,m6A promoted mitochondria fusion via induction of GSH synthesis and OPA1 expression,which facilitated cancer cell growth and CRC development.
查看更多>>摘要：Transformation optics(TO)provides an unprecedented technique to control electromagnetic(EM)waves by engineering the constitutive parameters of the surrounding medium through a proper spatial transformation.In general,ideal transformation optical devices require simultaneous electric and magnetic responses along all three dimensions.To ease the practical implementation,previous studies usually made use of reduced parameters or other simplified approaches,which inevitably introduce extra reflection or unwanted phase shift.Up to today,experimental realizations of full-parameter transformation optical devices in free space are still quite limited.Here,a general design strategy is proposed to solve this problem.As a specific example,a full-parameter spatial-compression TO medium with constitutive parameters taking the diagonal form diag(a,a,l/a)for the TM wave incidence was designed and realized experimentally.Such spatial-compression TO media were then applied to the implementation of an ideal omnidirectional invisibility cloak capable of concealing a large-scale object over a wide range of illumination angles.Both the simulation and experiment confirm that the cloak allows for nearly unity transmission of EM waves in the forward direction without introducing extra scattering or phase shift.This work constitutes an important stepping stone for future practical implementation of arbitrary full-parameter omnidirectional transformation optical devices.
查看更多>>摘要：The quantum anomalous Hall effect(QAHE)has unique advantages in topotronic applications,but it is still challenging to realize the QAHE with tunable magnetic and topological properties for building functional devices.Through systematic first-principles calculations,we predict that the in-plane magnetization induced QAHE with Chern numbers C=±1 and the out-of-plane magnetization induced QAHE with high Chern numbers C=±3 can be realized in a single material candidate,which is composed of van der Waals(vdW)coupled Bi and MnBi2Te4 monolayers.The switching between different phases of QAHE can be controlled in multiple ways,such as applying strain or(weak)magnetic field or twisting the vdW materials.The prediction of an experimentally available material system hosting robust,highly tunable QAHE will stimulate great research interest in the field.Our work opens a new avenue for the realization of tunable QAHE and provides a practical material platform for the development of topological electronics.
查看更多>>摘要：Two-dimensional materials represent a major frontier for research into exotic many-body quantum phenomena.In the extreme two-dimensional limit,electron-electron interaction often dominates over other electronic energy scales,leading to strongly correlated effects such as quantum spin liquid and unconventional superconductivity.The dominance is conventionally attributed to the lack of electron screening in the third dimension.Here,we discover an intriguing metal to Mott insulator transition in1T-TaSe2 that defies conventional wisdom.Specifically,we find that dimensionality crossover,instead of reduced screening,drives the transition in atomically thin 1T-TaSe2.A dispersive band crossing the Fermi level is found to be responsible for the bulk metallicity in the material.Reducing the dimensionality,however,effectively quenches the kinetic energy of these initially itinerant electrons,and drives the material into a Mott insulating state.The dimensionality-driven metal to Mott insulator transition resolves the long-standing dichotomy between metallic bulk and insulating surface of 1 T-TaSe2.Our work further reveals a new pathway for modulating two-dimensional materials that enables exploring strongly correlated systems across uncharted parameter space.
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