Induced pluripotent stem cells (iPSCs) hold great promise for regenerative medicine; however, their potential clinical application is hampered by the low efficiency of somatic cell reprogramming. ...Here, we show that the synergistic activity of synthetic modified mRNAs encoding reprogramming factors and miRNA-367/302s delivered as mature miRNA mimics greatly enhances the reprogramming of human primary fibroblasts into iPSCs. This synergistic activity is dependent upon an optimal RNA transfection regimen and culturing conditions tailored specifically to human primary fibroblasts. As a result, we can now generate up to 4,019 iPSC colonies from only 500 starting human primary neonatal fibroblasts and reprogram up to 90.7% of individually plated cells, producing multiple sister colonies. This methodology consistently generates clinically relevant, integration-free iPSCs from a variety of human patient's fibroblasts under feeder-free conditions and can be applicable for the clinical translation of iPSCs and studying the biology of reprogramming.
Spiking Neural Networks (SNNs) that require synapse weight initialization using random numbers have been widely used in the neural morphological system. However, the random numbers generated by ...traditional digital circuits have certain repeatability, and the entire computing architecture has issues such as high resource consumption and low integration. In this letter, a hardware system for true random number generation is realized through integrating a magnetic tunnel junction, a memory cell of MRAM (magnetic random access memory) chips, with an interface circuit and using the same mechanism as writing data in spin transfer torque MRAM. The generated true random numbers are evaluated using NIST SP800-22 standard and are used for synapse weight initialization in an SNN system. The recognition rate of the system initialized by the generated true random numbers is about 84% for an MNIST handwritten digit dataset, which is 2%–3% higher than that using a traditional linear feedback shift register. The reported work provides a new approach for better SNN performance.
The specification of mammalian chromosomal replication origins is incompletely understood. To analyze the assembly and activation of prereplicative complexes (pre-RCs), we tested the effects of ...tethered binding of chromatin acetyltransferases and replication proteins on chromosomal c-myc origin deletion mutants containing a GAL4-binding cassette. GAL4(DBD) (DNA binding domain) fusions with Orc2, Cdt1, E2F1 or HBO1 coordinated the recruitment of the Mcm7 helicase subunit, the DNA unwinding element (DUE)-binding protein DUE-B and the minichromosome maintenance (MCM) helicase activator Cdc45 to the replicator, and restored origin activity. In contrast, replication protein binding and origin activity were not stimulated by fusion protein binding in the absence of flanking c-myc DNA. Substitution of the GAL4-binding site for the c-myc replicator DUE allowed Orc2 and Mcm7 binding, but eliminated origin activity, indicating that the DUE is essential for pre-RC activation. Additionally, tethering of DUE-B was not sufficient to recruit Cdc45 or activate pre-RCs formed in the absence of a DUE. These results show directly in a chromosomal background that chromatin acetylation, Orc2 or Cdt1 suffice to recruit all downstream replication initiation activities to a prospective origin, and that chromosomal origin activity requires singular DNA sequences.
Rf(fa), a new restoring fertility gene in rice, was previously located to a large region on Chromosome 10. The large number of genes within the region made cloning of Rf(fa) difficult. To perform the ...cloning and further elucidate the molecular mechanism, we reconstructed a mapping segregation population (BC1F1) of 12 000 plants. Using the population and polymorphism of simple sequence repeat (SSR) molecular markers, we finally mapped Rf(fa) between the two SSR molecular markers MM2000 and RM25658, within a 78.87 kb region. By de novo sequencing of a restoring line of CMS-FA hybrid rice, we obtained the genomic sequence of the mapping region, which provided the basis for the prediction of the candidate gene(s) of the target gene and for the comparison of genomic sequence differences between wild and cultivated rice. Within the mapping region, the genomic sequence of the wild rice was significantly different from that of cultivated rice. There were ten genes in the final mapping region. A pentatricopeptide repeat (PPR) protein gene was predicted as the candidate gene of Rf(fa). Our results laid a solid foundation for the final cloning and molecular mechanism analysis of the gene. The identified molecular markers tightly linked to Rf(fa) will facilitate the marker assisted selection in breeding of CMS-FA hybrid rice.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Class switch recombination (CSR) generates isotype-switched Abs with distinct effector functions. B cells express phosphatase and tensin homolog (PTEN) and multiple isoforms of class IA PI3K ...catalytic subunits, including p110α and p110δ, whose roles in CSR remain unknown or controversial. In this article, we demonstrate a direct effect of PTEN on CSR signaling by acute deletion of Pten specifically in mature B cells, thereby excluding the developmental impact of Pten deletion. We show that mature B cell-specific PTEN overexpression enhances CSR. More importantly, we establish a critical role for p110α in CSR. Furthermore, we identify a cooperative role for p110α and p110δ in suppressing CSR. Mechanistically, dysregulation of p110α or PTEN inversely affects activation-induced deaminase expression via modulating AKT activity. Thus, our study reveals that a signaling balance between PTEN and PI3K isoforms is essential to maintain normal CSR.
DNA sequences prone to forming noncanonical structures (hairpins, triplexes, G-quadruplexes) cause DNA replication fork stalling, activate DNA damage responses, and represent hotspots of genomic ...instability associated with human disease. The 88-bp asymmetric polypurine-polypyrimidine (Pu-Py) mirror repeat tract from the human polycystic kidney disease (PKD1) intron 21 forms non-B DNA secondary structures in vitro. We show that the PKD1 mirror repeat also causes orientation-dependent fork stalling during replication in vitro and in vivo. When integrated alongside the c-myc replicator at an ectopic chromosomal site in the HeLa genome, the Pu-Py mirror repeat tract elicits a polar replication fork barrier. Increased replication protein A (RPA), Rad9, and ataxia telangiectasia- and Rad3-related (ATR) checkpoint protein binding near the mirror repeat sequence suggests that the DNA damage response is activated upon replication fork stalling. Moreover, the proximal c-myc origin of replication was not required to cause orientation-dependent checkpoint activation. Cells expressing the replication fork barrier display constitutive Chk1 phosphorylation and continued growth, i.e. checkpoint adaptation. Excision of the Pu-Py mirror repeat tract abrogates the DNA damage response. Adaptation to Chk1 phosphorylation in cells expressing the replication fork barrier may allow the accumulation of mutations that would otherwise be remediated by the DNA damage response.
Background: Repeated sequence non-B DNA structures impede replication forks and produce replication stress.
Results: A PKD1 polypurine-polypyrimidine mirror repeat sequence stalls replication forks in an orientation-dependent manner.
Conclusion: Non-B DNA structure formation of the Pu-rich lagging strand template leads to checkpoint activation.
Significance: Deciphering how non-B DNA structures provoke replication stress, checkpoint activation, and adaptation is important for understanding genome instability diseases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Based on integrated simulation technology of both marine electric propulsion system and artificial intelligence, a design of intelligent integrated simulation system of marine electric propulsion ...based on artificial neural network, fuzzy comprehensive evaluation and fuzzy neural network is proposed in this paper. The intelligent module mainly consists of a nonlinear simulation model, simulation evaluation and model optimization. Thanks to adopting an intelligent module, the accuracy of the simulation system is improved. The software implementation of intelligent integrated simulation for marine electric propulsion system is also discussed. The intelligent integrated simulation system of the marine electric propulsion system can guide the related design of electric propulsion system. The design of intelligent integrated simulation system of marine electric propulsion system can also guide the intelligent integrated simulation design of other systems.
In this study, friction stir processing (FSP) was used to enhance the corrosion properties through local modification of the microstructure of AlSi10Mg alloy fabricated by laser-powder bed fusion ...(L-PBF) technology. The impact of traverse and rotational speeds on the mechanical and electrochemical properties of L-PBF AlSi10Mg was analyzed with different combinations of processing parameters, with rotational speeds ranging from 800 to 1600 rpm and traverse speeds from 100 to 300 mm/min. The experimental results showed that the Si content within the stir zone is dependent on the combined influence of the rotational and traverse speeds, with a lower traverse speed promoting an enhanced grain refinement and a more homogenous Si distribution, indicated by a low LAGBs with a high HAGBs, resulting in the decrease of the hardness value and improvement of the corrosion performance of the processed material. The lowest hardness was found on the samples processed with a traverse speed of 100 mm/min and the best corrosion performance was observed from the samples processed with a rotational speed of 1600 rpm and a traverse speed of 100 mm/min. The results also indicated that the rotational speed showed a major role on the process, with the influence of the traverse speed diminishing when the material is processed at higher rotational speeds.
•FSP promotes grain refinement and eliminates the porosities of the L-PBF AlSi10Mg alloy.•The corrosion properties are influenced by the percentage of Si particles in the stir zone, and decreases with the increase of the traverse speed.•A higher traverse speed in FSP increases the severity of pitting corrosion.•The rotational speed has a governing role on the properties of FSPed samples, while the influence of the traverse speed is more significant at lower rotational speeds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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