Publications by authors named "Yali Xie"

23 Publications

  • Page 1 of 1

Recent developments on the magnetic and electrical transport properties of FeRh- and Rh-based heterostructures.

J Phys Condens Matter 2022 Jan 13. Epub 2022 Jan 13.

East China Normal University, Shanghai 200241, China, Shanghai, 200062, CHINA.

It is fascinating how the binary alloy FeRh has been the subject of a vast number of studies almost solely for a single-phase transition. This is, however, reasonable, considering how various degrees of freedom are intertwined around this phase transition. Furthermore, the tunability of this phase transition-the large response to tuning parameters, such as electric field and strain-endows FeRh huge potential in applications. Compared to the bulk counterpart, FeRh in the thin-film form is superior in many aspects: Materials in thin-film form are often more technologically relevant in the first place; in addition, the substrates add extra dimensions to the tunability, especially when the substrate itself is multiferroic. Here we review recent developments on the magnetic and transport properties of heterostructures based on FeRh and its end-member Rh, with the latter providing a new route to exploiting spin-orbit interactions in functional spintronic heterostructures other than the more often employed 5d metals. The methods utilized in the investigation of the physical properties in these systems, and the design principles employed in the engineering thereof may conceivably be extended to similar phase transitions to other magnetic materials.
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http://dx.doi.org/10.1088/1361-648X/ac4b28DOI Listing
January 2022

A Step-by-Step Refined Strategy for Highly Efficient Generation of Neural Progenitors and Motor Neurons from Human Pluripotent Stem Cells.

Cells 2021 11 9;10(11). Epub 2021 Nov 9.

Department of Geriatrics, Xiangya Hospital, Central South University, Changsha 410008, China.

Limited access to human neurons, especially motor neurons (MNs), was a major challenge for studying neurobiology and neurological diseases. Human pluripotent stem cells (hPSCs) could be induced as neural progenitor cells (NPCs) and further multiple neural subtypes, which provide excellent cellular sources for studying neural development, cell therapy, disease modeling and drug screening. It is thus important to establish robust and highly efficient methods of neural differentiation. Enormous efforts have been dedicated to dissecting key signalings during neural commitment and accordingly establishing reliable differentiation protocols. In this study, we refined a step-by-step strategy for rapid differentiation of hPSCs towards NPCs within merely 18 days, combining the adherent and neurosphere-floating methods, as well as highly efficient generation (~90%) of MNs from NPCs by introducing refined sets of transcription factors for around 21 days. This strategy made use of, and compared, retinoic acid (RA) induction and dual-SMAD pathway inhibition, respectively, for neural induction. Both methods could give rise to highly efficient and complete generation of preservable NPCs, but with different regional identities. Given that the generated NPCs can be differentiated into the majority of excitatory and inhibitory neurons, but hardly MNs, we thus further differentiate NPCs towards MNs by overexpressing refined sets of transcription factors, especially by adding human , whilst improving a series of differentiation conditions to yield mature MNs for good modeling of motor neuron diseases. We thus refined a detailed step-by-step strategy for inducing hPSCs towards long-term preservable NPCs, and further specified MNs based on the NPC platform.
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http://dx.doi.org/10.3390/cells10113087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8625124PMC
November 2021

Identification of a Novel Cleavage Site and Confirmation of the Effectiveness of NgAgo Gene Editing on RNA Targets.

Mol Biotechnol 2021 Dec 23;63(12):1183-1191. Epub 2021 Jul 23.

Laboratory Medicine Center, Huazhong University of Science and Technology Union Shenzhen Hospital (Nanshan Hospital), Shenzhen, 518000, Guangdong, People's Republic of China.

Clusters of regularly interspaced short palindromic repeats (CRISPR)/Cas systems have a powerful ability to edit DNA and RNA targets. However, the need for a specific recognition site, protospacer adjacent motif (PAM), of the CRISPR/Cas system limits its application in gene editing. Some Argonaute (Ago) proteins have endonuclease functions under the guidance of 5' phosphorylated or hydroxylated guide DNA (gDNA). The NgAgo protein might perform RNA gene editing at 37 °C, suggesting its application in mammalian cells; however, its mechanisms are unclear. In the present study, the target of NgAgo in RNA was confirmed in vitro and in vivo. Then, an in vitro RNA cleavage system was designed and the cleavage site was verified by sequencing. Furthermore, NgAgo and gDNA were transfected into cells to cleave an intracellular target sequence. We demonstrated targeted degradation of GFP, HCV, and AKR1B10 RNAs in a gDNA-dependent manner by NgAgo both in vitro and in vivo, but no effect on DNA was observed. Sequencing demonstrated that the cleavage sites are located at the 3' of the target RNA which is recognized by 5' sequence of the gDNA. These results confirmed that NgAgo-gDNA cleaves RNA not DNA. We observed that the cleavage site is located at the 3' of the target RNA, which is a new finding that has not been reported in the past.
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http://dx.doi.org/10.1007/s12033-021-00372-1DOI Listing
December 2021

Gene4PD: A Comprehensive Genetic Database of Parkinson's Disease.

Front Neurosci 2021 26;15:679568. Epub 2021 Apr 26.

National Clinical Research Center for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, China.

Parkinson's disease (PD) is a complex neurodegenerative disorder with a strong genetic component. A growing number of variants and genes have been reported to be associated with PD; however, there is no database that integrate different type of genetic data, and support analyzing of PD-associated genes (PAGs). By systematic review and curation of multiple lines of public studies, we integrate multiple layers of genetic data (rare variants and copy-number variants identified from patients with PD, associated variants identified from genome-wide association studies, differentially expressed genes, and differential DNA methylation genes) and age at onset in PD. We integrated five layers of genetic data (8302 terms) with different levels of evidences from more than 3,000 studies and prioritized 124 PAGs with strong or suggestive evidences. These PAGs were identified to be significantly interacted with each other and formed an interconnected functional network enriched in several functional pathways involved in PD, suggesting these genes may contribute to the pathogenesis of PD. Furthermore, we identified 10 genes were associated with a juvenile-onset (age ≤ 30 years), 11 genes were associated with an early-onset (age of 30-50 years), whereas another 10 genes were associated with a late-onset (age > 50 years). Notably, the AAOs of patients with loss of function variants in five genes were significantly lower than that of patients with deleterious missense variants, while patients with ( = 0.01) was opposite. Finally, we developed an online database named Gene4PD (http://genemed.tech/gene4pd) which integrated published genetic data in PD, the PAGs, and 63 popular genomic data sources, as well as an online pipeline for prioritize risk variants in PD. In conclusion, Gene4PD provides researchers and clinicians comprehensive genetic knowledge and analytic platform for PD, and would also improve the understanding of pathogenesis in PD.
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http://dx.doi.org/10.3389/fnins.2021.679568DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8107430PMC
April 2021

De novo mutation of cancer-related genes associates with particular neurodevelopmental disorders.

J Mol Med (Berl) 2020 12 12;98(12):1701-1712. Epub 2020 Oct 12.

National Clinical Research Center for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, 87 #, Xiangya Road, Changsha, 410008, Hunan, China.

Epidemiological studies have shown an increased prevalence of cancer in some patients with neurodevelopmental disorder (NDD); however, the genetic mechanisms regarding how cancer-related genes (CRGs) contribute to NDD remain unclear. We performed bioinformatic analyses on 219 CRGs from OMIM and de novo mutations (DNMs) from 16,498 patients with different NDDs and 3391 controls. Our results showed that autism spectrum disorder, undiagnosed neurodevelopmental disorder, congenital heart disease and intellectual disability, but not epileptic encephalopathy and schizophrenia, harboured significantly more putative functional DNMs in CRGs, compared with controls, providing genetic evidence supporting previous epidemiological surveys. We further detected 26 CRGs with recurrent putative functional DNMs that showed high expression in the human brain during the prenatal stage and in non-brain organs in adults. The proteins coded by the 26 CRGs and known NDD candidate genes formed a functional network that is involved in brain development and tumorigenesis. Overall, we proposed 39 cancer-targeting drugs that could be investigated for treating patients with NDD, which would be potentially cost-effective. In conclusion, DNMs contribute to specific NDDs and there may be a shared genetic basis between NDDs and cancer, highlighting the importance of considering cancer-targeting drugs with potential curative effects in patients with NDDs. KEY MESSAGES: • The contribution of DNMs in NDD is consistent with epidemiological surveys. • We highlighted 26 CRGs, including nine genes with more than five functional DNMs. • Specific expression patterns underlie the genetic mechanism of CRGs in NDD. • Specific functional networks underlie the genetic mechanism of CRGs in NDD. • The shared genetic aetiology suggests potential mutual treatment strategies.
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http://dx.doi.org/10.1007/s00109-020-01991-yDOI Listing
December 2020

Overexpression of from moso bamboo promotes leaf senescence and enhances abiotic stress tolerance in .

PeerJ 2020 31;8:e8716. Epub 2020 Mar 31.

Key Laboratory of Bamboo and Rattan Science and Technology, International Center for Bamboo and Rattan, State Forestry and Grassland Administration, Beijing, China.

The NAC family is one of the largest transcription factor families unique to plants, which regulates the growth and development, biotic and abiotic stress responses, and maturation and senescence in plants. In this study, , a gene, was isolated and characterized from moso bamboo (). PheNAC3 belong to the NAC1 subgroup and has a conserved NAC domain on the N-terminus, which with 88.74% similarity to ONAC011 protein. PheNAC3 localized in the nucleus and exhibited transactivation activity. was upregulated during the process of senescence of leaves and detected shoots. was also induced by ABA, MeJA, NaCl and darkness, but it had no remarkable response to PEG and SA treatments. Overexpression of could cause precocious senescence in . Transgenic displayed faster seed germination, better seedling growth, and a higher survival rate than the wild-type under salt or drought stress conditions. Moreover, associated with senescence and and related to ABA were upregulated by overexpression, but was inhibited. These findings show that may participate in leaf senescence and play critical roles in the salt and drought stress response.
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http://dx.doi.org/10.7717/peerj.8716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7120055PMC
March 2020

SrfABC Toxin from Induces Cytotoxicity and Apoptosis in HeLa Cells.

Toxins (Basel) 2019 11 22;11(12). Epub 2019 Nov 22.

State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory for Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, China.

Our previous study showed that the operon, which was originally identified in as an SsrB-regulated operon clustered with the flagellar class 2 operon, exhibited significant cytotoxicity against insect midgut CF-203 cells and injectable insecticidal activity against larvae. The operon was widely distributed among bacteria, which raises the question of their biological roles in different species. In this study, we investigated the cytotoxic effect of SrfABC toxin on mammalian cell lines. When simultaneously expressed in the cytoplasm, SrfABC exhibited cytotoxicity against all tested mammalian cancer cell lines (B16, 4T-1, Hep-3B, and HeLa) in a dose-dependent manner. Intracellular expression of SrfA-FLAG, SrfB-FLAG, or SrfC-FLAG also resulted in inhibition of proliferation and apoptosis on HeLa cells. When incubated with HeLa cells separately, SrfA, SrfB, and SrfC proteins alone could enter HeLa cells, then induce apoptosis and cytotoxicity. SrfC protein shifts its localization from cytoplasm to nucleus with the aid of SrfA and/or SrfB protein. Although SrfA, SrfB, and SrfC proteins alone exhibited a cytotoxic effect against HeLa cells, all three components were essential for the full cytotoxicity. Native PAGE and co-immunoprecipitation assay demonstrated that SrfA, SrfB, and SrfC proteins could interact with each other and form a heteromeric complex.
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http://dx.doi.org/10.3390/toxins11120685DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950479PMC
November 2019

Gene4Denovo: an integrated database and analytic platform for de novo mutations in humans.

Nucleic Acids Res 2020 01;48(D1):D913-D926

National Clinical Research Centre for Geriatric Disorders, Department of Geriatrics, Xiangya Hospital, Central South University, Changsha, Hunan, China.

De novo mutations (DNMs) significantly contribute to sporadic diseases, particularly in neuropsychiatric disorders. Whole-exome sequencing (WES) and whole-genome sequencing (WGS) provide effective methods for detecting DNMs and prioritizing candidate genes. However, it remains a challenge for scientists, clinicians, and biologists to conveniently access and analyse data regarding DNMs and candidate genes from scattered publications. To fill the unmet need, we integrated 580 799 DNMs, including 30 060 coding DNMs detected by WES/WGS from 23 951 individuals across 24 phenotypes and prioritized a list of candidate genes with different degrees of statistical evidence, including 346 genes with false discovery rates <0.05. We then developed a database called Gene4Denovo (http://www.genemed.tech/gene4denovo/), which allowed these genetic data to be conveniently catalogued, searched, browsed, and analysed. In addition, Gene4Denovo integrated data from >60 genomic sources to provide comprehensive variant-level and gene-level annotation and information regarding the DNMs and candidate genes. Furthermore, Gene4Denovo provides end-users with limited bioinformatics skills to analyse their own genetic data, perform comprehensive annotation, and prioritize candidate genes using custom parameters. In conclusion, Gene4Denovo conveniently allows for the accelerated interpretation of DNM pathogenicity and the clinical implication of DNMs in humans.
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http://dx.doi.org/10.1093/nar/gkz923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7145562PMC
January 2020

Screening a fosmid library of Xenorhabdus stockiae HN_xs01 reveals SrfABC toxin that exhibits both cytotoxicity and injectable insecticidal activity.

J Invertebr Pathol 2019 10 12;167:107247. Epub 2019 Sep 12.

State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Provincial Key Laboratory for Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha 410081, People's Republic of China. Electronic address:

Xenorhabdus spp., entomopathogenic bacteria symbiotically associated with the nematodes of the Steinernematid family, are known to produce several toxic proteins that interfere with the cellular immune responses of insects. In order to identify novel cytotoxins from Xenorhabdus spp., a fosmid library of X. stockiae HN_xs01 strain was constructed and the cytotoxicity of fosmid clones was tested against insect midgut CF-203 cells. An FS2 clone bearing the srfABC operon, originally identified in Salmonella enterica, exhibited excellent cytotoxicity against CF-203 cells. The srfABC operon alone exhibited cytotoxic effects and all three components of SrfABC toxin were essential for full cytotoxicity. Immunofluorescence studies showed that SrfABC toxin could depolymerize microtubules and disrupt mitochrondria. Flow cytometer analysis demonstrated that SrfABC toxin significantly induced G2/M phase arrest and apoptosis in CF-203 cells. Furthermore, SrfABC toxin exhibits highly injectable insecticidal activity against Helicoverpa armigera larvae. As is often found in host-associated microorganisms, SrfABC toxin is thought to play an important role in host colonization.
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http://dx.doi.org/10.1016/j.jip.2019.107247DOI Listing
October 2019

Tyrosine kinase inhibitors show different anti-brain metastases efficacy in NSCLC: A direct comparative analysis of icotinib, gefitinib, and erlotinib in a nude mouse model.

Oncotarget 2017 Nov 19;8(58):98771-98781. Epub 2017 Oct 19.

Department of Respiratory Medicine, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.

Brain metastasis is an increasing problem in non-small cell lung cancer (NSCLC) patients. Tyrosine kinase inhibitors (TKIs), including gefitinib, erlotinib, and icotinib, are reported to be effective in patients with brain metastases. However, direct comparative studies of the pharmacokinetics and efficacy of these three drugs in treating brain metastases are lacking. In the present investigation, we found that gefitinib penetrated the blood-tumor barrier and was distributed to brain metastases more effectively than erlotinib or icotinib in a nude mouse model. The 1-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 9.82±1.03%, 4.83±0.25%, and 2.62±0.21%, respectively. The 2-h ratio of brain metastases to plasma concentration for gefitinib, erlotinib, and icotinib was 15.11±2.00%, 5.73±1.31%, and 2.69±0.31%, respectively. Gefitinib exhibited the strongest antitumor activity (=0.005; =0.002). Notably, erlotinib exhibited a better treatment efficacy than icotinib (=0.037). Consistently, immunohistochemical data showed that TKIs differentially inhibit the proliferation of metastatical tumor cells. Gefitinib and erlotinib markedly inhibited the proliferation of tumor cells, while there were more ki-67-positive tumor cells in the icotinib group. Additionally, gefitinib inhibited the phosphorylation of EGFR better than the other drugs, whereas pEGFR expression levels in erlotinib groups were lower than levels in the icotinib group (=0.995; =0.028; =0.042).Altogether, our findings suggest that gefitinib and erlotinib can inhibit the growth of PC-9-luc brain tumors. Gefitinib demonstrated better antitumor activity and penetration rate in brain metastases than erlotinib or icotinib.
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http://dx.doi.org/10.18632/oncotarget.21936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5716766PMC
November 2017

Magnetic anisotropy and high-frequency property of flexible FeCoTa films obliquely deposited on a wrinkled topography.

Sci Rep 2017 06 6;7(1):2837. Epub 2017 Jun 6.

CAS Key Laboratory of Magnetic Materials and Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, People's Republic of China.

We investigated the magnetic anisotropy and the high-frequency property of flexible FeCoTa (FeCoTa) thin films obtained by oblique sputtering onto a wrinkled surface. The sinuously wrinkled topography is produced by growing Ta layer on a pre-strained polydimethylsiloxane (PDMS) membrane. Due to the enhanced effect of shadowing, the oblique deposition of FeCoTa layer gives rise to a shift of wrinkle peak towards the incident atomic flux. With increasing the PDMS pre-strain or increasing the oblique sputtering angle, both the uniaxial magnetic anisotropy and the ferromagnetic resonance frequency of FeCoTa films are enhanced, but the initial permeability decreases. The magnetization reversal mechanism of wrinkled FeCoTa films can be interpreted by a two-phase model composed of both coherent rotation and domain wall nucleation. With the enhancement of uniaxial magnetic anisotropy, the domain wall nucleation becomes pronounced in FeCoTa films.
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http://dx.doi.org/10.1038/s41598-017-03288-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460212PMC
June 2017

Manipulate the magnetic anisotropy of nanoparticle assemblies in arrays.

J Colloid Interface Sci 2017 07 24;497:14-22. Epub 2017 Feb 24.

State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China.

Tuning the magnetic anisotropy of nanoparticle assemblies is critical for their applications such as on-chip magnetic electronic components and electromagnetic wave absorption. In this work, we developed a facile hierarchical self-assembly method to separately control the magnetic shape and magnetocrystalline anistropy of individual nanoparticle assemblies in arrays. Since magnetic nanoparticle assemblies in the array have the same size, shape and alignment, we are able to study the magnetic properties of individual nanoparticle assembly by measuring the whole arrays. The interplay between the two magnetic anisotropies was systematically studied for disk- and bar-shaped nanoparticle assemblies. Maximum magnetic anisotropy was obtained when the easy axis of magnetic nanoparticles was aligned along the long axes of the bar-shaped nanoparticles assemblies.
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http://dx.doi.org/10.1016/j.jcis.2017.02.056DOI Listing
July 2017

"Cre/loxP plus BAC": a strategy for direct cloning of large DNA fragment and its applications in Photorhabdus luminescens and Agrobacterium tumefaciens.

Sci Rep 2016 07 1;6:29087. Epub 2016 Jul 1.

Hunan Provincial Key Laboratory of Microbial Molecular Biology-State Key Laboratory Breeding Base of Microbial Molecular Biology, College of Life Science, Hunan Normal University, Changsha, 410081, People's Republic of China.

Heterologous expression has been proven to be a valid strategy for elucidating the natural products produced by gene clusters uncovered by genome sequencing projects. Efforts have been made to efficiently clone gene clusters directly from genomic DNA and several approaches have been developed. Here, we present an alternative strategy based on the site-specific recombinase system Cre/loxP for direct cloning gene clusters. A type three secretion system (T3SS) gene cluster (~32 kb) from Photorhabdus luminescens TT01 and DNA fragment (~78 kb) containing the siderophore biosynthetic gene cluster from Agrobacterium tumefaciens C58 have been successfully cloned into pBeloBAC11 with "Cre/loxP plus BAC" strategy. Based on the fact that Cre/loxP system has successfully used for genomic engineering in a wide range of organisms, we believe that this strategy could be widely used for direct cloning of large DNA fragment.
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http://dx.doi.org/10.1038/srep29087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4929569PMC
July 2016

A rifampicin-resistant (rpoB) mutation in Pseudomonas protegens Pf-5 strain leads to improved antifungal activity and elevated production of secondary metabolites.

Res Microbiol 2016 Oct 18;167(8):625-629. Epub 2016 May 18.

College of Life Science, Hunan Normal University, Hunan Provincial Key Laboratory of Microbial Molecular Biology-State Key Laboratory Breeding Base of Microbial Molecular Biology, Changsha, China. Electronic address:

Ribosome engineering has proven to be a practical method for increasing antibiotic production, and is extensively applied to strain improvement in antibiotic production and activation of silent genes in several prokaryotes. In this study, ribosome engineering was used to improve production of bioactive secondary metabolites produced by Pseudomonas protegens Pf-5. Rifampicin-resistant mutants that bear the H531N in the β-subunit of RNA polymerase showed improved antifungal activity and morphological changes. The production of several secondary metabolites in R55 mutant was significantly improved using high-performance liquid chromatography (HPLC) analysis. Two antibiotics with antifungal activity, 2, 4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt), which may contribute to the improved antifungal activity of the R55 mutant, were identified by mass spectrometer (MS) analysis.
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http://dx.doi.org/10.1016/j.resmic.2016.05.001DOI Listing
October 2016

Efficient Construction of Large Genomic Deletion in Agrobacterium tumefaciens by Combination of Cre/loxP System and Triple Recombineering.

Curr Microbiol 2016 Apr 7;72(4):465-72. Epub 2016 Jan 7.

College of Life Science, Hunan Provincial Key Laboratory of Microbial Molecular Biology-State Key Laboratory Breeding Base of Microbial Molecular Biology, Hunan Normal University, Changsha, 410081, China.

In order to develop an efficient system for deleting genomic segment in Agrobacterium tumefaciens to analyze gene functions and construct marker gene-free recombinant strains, a Cre recombinase expression plasmid was constructed by placing its encoding gene under the control of Ptet promoter and cloning into the plasmid replicable in both A. tumefaciens and E. coli. Triple recombineering was applied to efficiently construct integrative vectors which were used to introduce loxP sites and selection markers into the chromosome of A. tumefaciens. Cre recombinase could be properly induced by anhydrotetracycline in A. tumefaciens, which was revealed by the fact that kanamycin resistance gene flanked by two parallel loxP sites was excised from the genome of A. tumefaciens with virtually 100% efficiency. And what is more, an A. tumefaciens mutant carrying large-deletion (~85 kb) in genome was successfully constructed by Cre/loxP system. Here, we described the application of combination of Cre/loxP system and triple recombineering to efficiently excise genomic segment in A. tumefaciens, which also would facilitate efficient construction of multiple gene disruptions in A. tumefaciens.
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http://dx.doi.org/10.1007/s00284-015-0977-5DOI Listing
April 2016

Synthesis of magnetite/graphene oxide/chitosan composite and its application for protein adsorption.

Mater Sci Eng C Mater Biol Appl 2014 Dec 6;45:8-14. Epub 2014 Sep 6.

Department of Chemistry, Capital Normal University, Beijing 100048, PR China.

In this study, a facile and novel strategy was developed to fabricate magnetite/graphene oxide/chitosan (Fe3O4/GO/CS) composite, and the composite was used as a magnetic adsorbent for the enrichment of protein, and followed by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF MS) analysis. The phase composition, chemical structure and morphology of the composite were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), scanning electronic microscope (SEM) and vibrating sample magnetometer (VSM). Protein cytochrome c was chosen as model target to evaluate the adsorptive property of Fe3O4/GO/CS. After enrichment procedure and magnetic separation, protein bounded with the material was analyzed by MALDI-TOF MS without desorption. The results indicated that Fe3O4/GO/CS composite exhibited a good adsorptive capacity for protein, and Fe3O4/GO/CS composite had a promising potential in magnetic separation research.
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http://dx.doi.org/10.1016/j.msec.2014.08.064DOI Listing
December 2014

Thermally assisted electric field control of magnetism in flexible multiferroic heterostructures.

Sci Rep 2014 Nov 5;4:6925. Epub 2014 Nov 5.

Key Laboratory of Magnetic Materials and Devices &Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, People's Republic of China.

Thermal and electrical control of magnetic anisotropy were investigated in flexible Fe81Ga19 (FeGa)/Polyvinylidene fluoride (PVDF) multiferroic heterostructures. Due to the large anisotropic thermal deformation of PVDF (α1 = -13 × 10(-6) K(-1) and α2 = -145 × 10(-6) K(-1)), the in-plane uniaxial magnetic anisotropy (UMA) of FeGa can be reoriented 90° by changing the temperature across 295 K where the films are magnetically isotropic. Thus, the magnetization of FeGa can be reversed by the thermal cycling between 280 and 320 K under a constant magnetic field lower than coercivity. Moreover, under the assistance of thermal deformation with slightly heating the samples to the critical temperature, the electric field of ± 267 kV cm(-1) can well align the UMA along the two orthogonal directions. The new route of combining thermal and electrical control of magnetic properties realized in PVDF-based flexible multiferroic materials shows good prospects in application of flexible thermal spintronic devices and flexible microwave magnetic materials.
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http://dx.doi.org/10.1038/srep06925DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4220272PMC
November 2014

Positive temperature coefficient of magnetic anisotropy in polyvinylidene fluoride (PVDF)-based magnetic composites.

Sci Rep 2014 Oct 14;4:6615. Epub 2014 Oct 14.

Key Laboratory of Magnetic Materials and Devices &Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, People's Republic of China.

The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the strain-induced anisotropy resulting from the anisotropic thermal expansion of the β-phase PVDF. The simulation based on modified Stoner-Wohlfarth model and the ferromagnetic resonance measurements confirms our results. The positive temperature coefficient of magnetic anisotropy is estimated to be 1.1 × 10(2) J m(-3) K(-1). Preparing the composite at low temperature can enlarge the temperature range where it shows the positive temperature coefficient of magnetic anisotropy. The present results may help to design magnetic devices with improved thermal stability and enhanced performance.
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http://dx.doi.org/10.1038/srep06615DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4196102PMC
October 2014

Simultaneous determination of atropine, scopolamine, and anisodamine in Flos daturae by capillary electrophoresis using a capillary coated by graphene oxide.

J Sep Sci 2013 Aug 19;36(16):2698-702. Epub 2013 Jul 19.

Department of Chemistry, Capital Normal University, Beijing, PR China.

A novel CE method was developed for the separation and determination of three main tropane alkaloids in Flos daturae with a capillary coated by graphene oxide (GO). The GO-coated capillary was characterized by SEM, energy dispersive X-ray spectroscopy, and Raman spectroscopy, and the results indicated that the inner surface of the capillary was partially coated by GO. A phosphate solution (40 mM, pH7.0) containing 20% v/v methanol and 30% v/v acetonitrile was used as the running buffer for the analysis of the atropine, scopolamine, and anisodamine. The linear ranges of atropine, scopolamine, and anisodamine was 0.5-200 μg/mL with satisfactory correlation coefficients (R(2)) > 0.9987, and this novel method provided an efficient separation for three tropane alkaloids as well as a good reproducibility and stability. Finally, the method was successfully applied for the determination of these three tropane alkaloids in plant extracts.
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http://dx.doi.org/10.1002/jssc.201300304DOI Listing
August 2013

Graphene oxide coated capillary for chiral separation by CE.

Electrophoresis 2013 Mar 18;34(6):841-5. Epub 2013 Feb 18.

Department of Chemistry, Capital Normal University, Beijing, China.

This article describes a new application of graphene oxide (GO) in CE based on the coating of fused silica capillary for chiral separation. The coated capillary was characterized by SEM, energy dispersive X-ray spectroscopy, and Raman spectra. The results indicated that the capillary was coated with GO. Chiral separations were carried out in the GO-coated capillary for the ephedrine-pseudoephedrine (E-PE) isomers and β-methylphenethylamine (β-Me-PEA) isomers at the optimal buffer conditions without any chiral selector by CE. The precision and reproducibility of GO-coated capillary were investigated, and the RSDs of migration time (n = 6) for the E-PE isomers were 1.35-1.41%, and 0.97-3.50% for β-Me-PEA isomers, respectively. The LOD for E-PE isomers and β-Me-PEA isomers was 3 μM and 18 μM, respectively.
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http://dx.doi.org/10.1002/elps.201200516DOI Listing
March 2013

Cancer-associated variants and a common polymorphism of MUTYH exhibit reduced repair of oxidative DNA damage using a GFP-based assay in mammalian cells.

Carcinogenesis 2012 Nov 26;33(11):2301-9. Epub 2012 Aug 26.

Department of Chemistry, University of California, Davis, CA 95616, USA.

Biallelic germline mutations in the base excision repair enzyme gene MUTYH lead to multiple colorectal adenomas and carcinomas referred to as MUTYH-associated polyposis. MUTYH removes adenine misincorporated opposite the DNA oxidation product, 8-oxoguanine (OG), thereby preventing accumulation of G:C to T:A transversion mutations. The most common cancer-associated MUTYH variant proteins when expressed in bacteria exhibit reduced OG:A mismatch affinity and adenine removal activity. However, direct evaluation of OG:A mismatch repair efficiency in mammalian cells has not been assessed due to the lack of an appropriate assay. To address this, we developed a novel fluorescence-based assay of OG:A repair and measured the repair capacity of MUTYH-associated polyposis variants expressed in Mutyh-/- mouse embryonic fibroblasts (MEFs). The repair of a single site-specific synthetic lesion in a green fluorescent protein reporter leads to green fluorescent protein expression with co-expression of a red fluorescent protein serving as the transfection control. Cell lines that stably express the MUTYH-associated polyposis variants G382D and Y165C have significantly lower OG:A repair versus wild-type MEFs and MEFs expressing human wild-type MUTYH. The MUTYH allele that encodes the Q324H variant is found at a frequency above 40% in samples from different ethnic groups and has long been considered phenotypically silent but has recently been associated with increased cancer risk in several clinical studies. In vitro analysis of Q324H MUTYH expressed in insect cells showed that it has reduced enzyme activity similar to that of the known cancer variant G382D. Moreover, we find that OG:A repair in MEFs expressing Q324H was significantly lower than wild-type controls, establishing that Q324H is functionally impaired and providing further evidence that this common variant may lead to increased cancer risk.
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http://dx.doi.org/10.1093/carcin/bgs270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3483017PMC
November 2012

Cells deficient in oxidative DNA damage repair genes Myh and Ogg1 are sensitive to oxidants with increased G2/M arrest and multinucleation.

Carcinogenesis 2008 Apr 6;29(4):722-8. Epub 2008 Feb 6.

Department of Physiology, University of Manitoba, 730 William Avenue, Winnipeg, MB R3E 0W9, Canada.

Oxidative stress generated from endogenous and exogenous sources causes oxidative DNA damage. The most frequent mutagenic base lesion 7,8-dihydro-8-oxoguanine and the resulting mismatched adenine are removed by OGG1 and MYH in mammals. Deficiencies in human MYH or mouse MYH and OGG1 result in tumor predisposition but the underlying molecular mechanism is not fully understood. To facilitate the study of the roles of MYH and OGG1 in the protection against oxidative stress, we generated mouse embryonic fibroblast cell lines deficient in these genes. Myh and Ogg1 double knockout cells were more sensitive than wild type to oxidants (hydrogen peroxide and t-butyl hydroperoxide), but not to cis-platinum or gamma-irradiations. The low dosage oxidative stress resulted in more reduction of S phase and increase of G(2)/M phase in Myh(-/-)Ogg1(-/-) cells than in wild-type cells, but a similar level of cell death in both cells. The oxidants also induced more multinucleated cells in Myh(-/-)Ogg1(-/-) cells than in wild-type, accompanied by centrosome amplification and multipolar spindle formation. Thus, under oxidative stress, Myh and Ogg1 are likely required for normal cell-cycle progression and nuclear division, suggesting multiple roles of Myh and Ogg1 in the maintenance of genome stability and tumor prevention.
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http://dx.doi.org/10.1093/carcin/bgn033DOI Listing
April 2008

Deficiencies in mouse Myh and Ogg1 result in tumor predisposition and G to T mutations in codon 12 of the K-ras oncogene in lung tumors.

Cancer Res 2004 May;64(9):3096-102

Department of Microbiology, Immunology, and Molecular Genetics and the Molecular Biology Institute, University of California at Los Angeles, Los Angeles, California, USA.

Oxidative DNA damage is unavoidably and continuously generated by oxidant byproducts of normal cellular metabolism. The DNA damage repair genes, mutY and mutM, prevent G to T mutations caused by reactive oxygen species in Escherichia coli, but it has remained debatable whether deficiencies in their mammalian counterparts, Myh and Ogg1, are directly involved in tumorigenesis. Here, we demonstrate that deficiencies in Myh and Ogg1 predispose 65.7% of mice to tumors, predominantly lung and ovarian tumors, and lymphomas. Remarkably, subsequent analyses identified G to T mutations in 75% of the lung tumors at an activating hot spot, codon 12, of the K-ras oncogene, but none in their adjacent normal tissues. Moreover, malignant lung tumors were increased with combined heterozygosity of Msh2, a mismatch repair gene involved in oxidative DNA damage repair as well. Thus, oxidative DNA damage appears to play a causal role in tumorigenesis, and codon 12 of K-ras is likely to be an important downstream target in lung tumorigenesis. The multiple oxidative repair genes are required to prevent mutagenesis and tumor formation. The mice described here provide a valuable model for studying the mechanisms of oxidative DNA damage in tumorigenesis and investigating preventive or therapeutic approaches.
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http://dx.doi.org/10.1158/0008-5472.can-03-3834DOI Listing
May 2004
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