Efficient removal of natural organo-chromium(Ⅲ)through selfcirculating decomplex and immobilization with nanoscale zerovalent iron

Organo-chromium(III)complex is one of the chromium contaminant species,which would transform to high-toxic Cr(VI)during migrating in the environment.Such natural organo-chromium(III)(NOCr)is difficult to remove by traditional degradation or precipitation methods,due to its high stability and solubility.Herein,we demonstrated a novel NOCr removing method by transforming it to certain structures similar to Cr-Fe minerals in nature,through a self-circulating decomplex and immobilization mechanism with nano zero-valent iron(nZVI).Taking chromium glycinate(Cr-Gly)as a probe,nZVI showed a high Cr removal efficiency of 99.4%under ambient conditions.The removal process included three stages of adsorption,decomplexation,and re-immobilization.Cr-Gly was first adsorbed on the surface of nZVI by chemisorption of the oxide shell.Then,the adsorbed Cr-Gly was decomplexed and oxidized to Cr(VI)by·OH and 1O_(2),which were generated from molecular oxygen activated by nZVI.Meanwhile,the released Cr(VI)could be in-situ adsorbed and re-reduced to Cr(III),which was further immobilized in form of Cr-O-Fe complex.As the Cr-O-Fe complexing structure was similar to that of Cr-Fe minerals(such as chromohercynite)in nature,this work explored a novel and efficient NOCr removing method that was potential to weaken chromium pollution in the environment.

Refinement of α′Martensite by Oxygen in Selective Laser Melted Ti-6Al-4V

Oxygen is crucial in influencing the microstructure evolution of selective laser melted(SLMed)Ti–6Al–4V,significantly impacting its applicability in various sectors.Therefore,this study investigates the influnce of oxygen on microstructure evolution,particularlyα′martensite transformation and refinement mechanisms.Four alloys,Ti–6Al–4V–xO(x=0.11,0.16,0.21,and 0.25 wt%),were fabricated by the SLM process.The martensite start temperature(M_(s))of Ti–6Al–4V,as evaluated by computation,is 656.8°C,and oxygen was found to increase the M_(s) by about 10°C per 0.1 wt%.The SLMed alloy samples exhibit[001]_(β)growth texture along the build direction.Crystallographic analysis of martensite morphology suggests internal twinning on{1011}planes as the lattice invariant strain,which becomes more predominant with increasing oxygen content.Refinement of α′martensite plates by oxygen is due to increased lattice distortion,reduced prior β grain size,and oxygen segregation toβgrain boundaries.Our findings contribute to improving the understanding of the effect of oxygen on the transformation mechanism ofα′martensite during SLM of Ti–6Al–4V.

Scutellarin prevents acute alcohol-induced liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and inhibiting inflammation by regulating the AKT,p38 MAPK/NF-κB pathways

Alcoholic liver disease(ALD)is the most frequent liver disease worldwide,resulting in severe harm to personal health and posing a serious burden to public health.Based on the reported antioxidant and anti-inflammatory capacities of scutellarin(SCU),this study investigated its protective role in male BALB/c mice with acute alcoholic liver injury after oral administration(10,25,and 50 mg/kg).The results indicated that SCU could lessen serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)levels and improve the histopathological changes in acute alcoholic liver;it reduced alcohol-induced malondialdehyde(MDA)content and increased glutathione peroxidase(GSH-Px),catalase(CAT),and superoxide dismutase(SOD)activity.Furthermore,SCU decreased tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),and IL-1βmessenger RNA(mRNA)expression levels,weakened inducible nitric oxide synthase(iNOS)activity,and inhibited nucleotide-binding oligomerization domain(NOD)-like receptor protein 3(NLRP3)inflammasome activation.Mechanistically,SCU suppressed cytochrome P450 family 2 subfamily E member 1(CYP2E1)upregulation triggered by alcohol,increased the expression of oxidative stress-related nuclear factor erythroid 2-related factor 2(Nrf2)and heme oxygenase-1(HO-1)pathways,and suppressed the inflammation-related degradation of inhibitor of nuclear factor-κB(NF-κB)-α(IκBα)as well as activation of NF-κB by mediating the protein kinase B(AKT)and p38 mitogen-activated protein kinase(MAPK)pathways.These findings demonstrate that SCU protects against acute alcoholic liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and suppressing inflammation by regulating the AKT,p38 MAPK/NF-κB pathways.

High-strength hydrogels:Fabrication,reinforcement mechanisms,and applications

With the continuous appearance and expansion of high-strength hydrogels in emerging fields such as industry,medicine,and green development,the synthesis and application of high-strength hydrogels have developed dramatically and achieved remarkable results from the aspects of raw materials,preparation methods,and reinforcement mechanisms.However,there is still a lack of systematic reviews on high-strength hydrogels.Herein,we first discuss the advantages of natural and synthetic materials,and the characteristics of high-strength hydrogels prepared from different raw materials;we then expound on the influence mechanism of physical interactions or chemical bonds on the strength of the hydrogel from three aspects:physical cross-linking,chemical cross-linking,and dynamic chemical cross-linking;at last,we systematically expound the strengthening strategies,including double network/multi-network,nanocomposite,topology,supramolecular polymerization,and characteristics and strengthening mechanisms of such high-strength hydrogels.In addition,based on the development status of high-strength hydrogels,we combined the application requirements and the existing drawbacks of high-strength hydrogels to propose their possible development directions in the future.

Tn5转座酶融合蛋白在CUT&Tag实验中的优化及评价

Tn5是一种细菌转座子。经改造的Tn5能够高效地切割DNA,同时连接上特定的接头序列,因而广泛应用于高通量二代测序文库构建中。CUT&Tag(Cleavage Under Target&Tagmentation)是一种改进的研究蛋白质与DNA互作的技术,具有重复性好、信噪比高及操作简便等优点。该技术采用pA(Protein A)或pG(Protein G)与Tn5形成融合蛋白,定位于特定抗体(用于识别目标蛋白),利用Tn5的特性,在目标位点附近打断DNA的同时引入测序接头,随后提取DNA,再进行PCR扩增即可获得测序文库。但不同类型的抗体与pA或pG的亲和力不同,因此限制了部分抗体在CUT&Tag技术中的应用。为克服这一局限,该文构建了pG与Tn5的融合蛋白表达载体,通过原核表达及亲和纯化的方式获得pG-Tn5重组蛋白;并以RNA聚合酶Ⅱ(PolⅡ)特异性抗体PolⅡSer5P(小鼠IgG1型抗体和兔IgG型抗体)为例,在模式植物拟南芥(Arabidopsis thaliana)中评估pA-Tn5与pG-Tn5在不同类型抗体的CUT&Tag测序文库构建中的效果。结果表明,IgG1型抗体与p G-Tn5的亲和力更高,构建的文库质量更好,而IgG型抗体与2种酶的亲和力相当;同时,较低起始量的植物材料也能获得较好的效果,证明了CUT&Tag的应用优势。该研究优化了CUT&Tag技术,可为后续CUT&Tag实验中针对不同抗体时Tn5融合蛋白的选择提供参考。

基于DAP-Seq方法鉴定玉米胚乳特异表达转录因子O2在全基因组水平上的结合位点

Opaque2(O2)是一个调控玉米胚乳发育的重要转录因子.为了揭示O2的转录调控网络,利用DAP-Seq技术挖掘其在全基因组范围上结合位点共检测到11385个位点.通过结合已报道RNA-Seq数据,本研究DAP-Seq共检测到317个O2直接结合并调控的靶基因,其中包括97个已报道ChIP-Seq检测靶基因以及220个DAP-Seq特异检测的靶基因.而基序(motif)富集分析显示, DAP-Seq检测O2结合317靶标基因与220个特异结合靶标基因所富集的基序均与已报道O2结合motif相同.另外, GO富集分析显示,与ChIP-Seq一致的O2靶基因主要参与zein蛋白合成及氨基酸代谢途径,而特异检测的O2靶标基因,除参与上述途径外,还主要参与糖代谢途径以及多个胁迫响应相关途径.本研究利用DAP-Seq技术进一步揭示了O2在胚乳发育过程发挥调控作用,该结果是对前人研究结果的验证和补充.

A Robust CRISPR/Cas9 System for Convenient, High-Efficiency Multiplex Genome Editing in Monocot and Dicot Plants

CRISPR/Cas9 genome targeting systems have been applied to a variety of species. However, most CRISPR/Cas9 systems reported for plants can only modify one or a few target sites. Here, we report a robust CRISPR/Cas9 vector system, utilizing a plant codon optimized Cas9 gene, for convenient and high- efficiency multiplex genome editing in monocot and dicot plants. We designed PCR-based procedures to rapidly generate multiple sgRNA expression cassettes, which can be assembled into the binary CRISPR/ Cas9 vectors in one round of cloning by Golden Gate ligation or Gibson Assembly. With this system, we edi- ted 46 target sites in rice with an average 85.4% rate of mutation, mostly in biallelic and homozygous status. We reasoned that about 16% of the homozygous mutations in rice were generated through the non-homol- ogous end-joining mechanism followed by homologous recombination-based repair. We also obtained uni- form biallelic, heterozygous, homozygous, and chimeric mutations in Arabidopsis T1 plants. The targeted mutations in both rice and Arabidopsis were heritable. We provide examples of loss-of-function gene mu- tations in To rice and T1Arabidopsis plants by simultaneous targeting of multiple （up to eight） members of a gene family, multiple genes in a biosynthetic pathway, or multiple sites in a single gene. This system has provided a versatile toolbox for studying functions of multiple genes and gene families in plants for basic research and genetic improvement.

FT5a interferes with the Dt1-AP1 feedback loop to control flowering time and shoot determinacy in soybean

Flowering time and stem growth habit determine inflorescence architecture in soybean, which in turn influences seed yield. Dt1, a homolog of Arabidopsis TERMINAL FLOWER 1(TFL1), is a major controller of stem growth habit, but its underlying molecular mechanisms remain unclear.Here, we demonstrate that Dt1 affects node number and plant height, as well as flowering time,in soybean under long-day conditions. The b ZIP transcription factor FDc1 physically interacts with Dt1, and the FDc1-Dt1 complex directly represses the expression of APETALA1(AP1). We propose that FT5 a inhibits Dt1 activity via a competitive interaction with FDc1 and directly upregulates AP1. Moreover, AP1 represses Dt1 expression by directly binding to the Dt1 promoter, suggesting that AP1 and Dt1 form a suppressive regulatory feedback loop to determine the fate of the shoot apical meristem. These findings provide novel insights into the roles of Dt1 and FT5 a in controlling the stem growth habit and flowering time in soybean, which determine the adaptability and grain yield of this important crop.

Transfer RNA-derived small RNAs in plants

Rather than random degradation products, the 18 to 40 nucleotides(nt) transfer RNA-derived small RNAs(tsRNAs) are RNA species generated specifically from pre-RNAs or mature tRNAs in archaea, bacteria and eukaryotes. Recent studies from animal systems have shown that tsRNAs are important non-coding RNAs that regulate gene expression at the transcriptional and/or post-transcriptional levels. They are involved in various biological processes, such as cell proliferation, tumor genesis, stress response and intergenerational epigenetic inheritance. In this review, we will summarize the discovery, biogenesis, and function of tsRNAs in higher plants. In addition, analysis on tsRNAs from lower plants is shown.

Immediate transcriptional responses of Arabidopsis leaves to heat shock

Plants have evolved efficient mechanisms for adapting to temperature fluctuations,known as heat stress response and heat stress memory.Although the transcriptional regulatory network of plant heat stress response has been established,little is known about the genome-wide transcriptional changes occurring within the first several minutes after heat shock.Here,we investigated the nascent RNA and mature messenger RNA(mRNA)from plant leaf tissues exposed to 5 min of heat shock treatment using global run-on sequencing and RNA sequencing methods.Only a small group of genes were up-or downregulated at both the nascent RNA and mRNA levels.Primed plants that were already exposed to mild heat stress exhibited a more drastic alteration at multiple transcriptional steps than naive plants that had not experienced heat stress.Upon heat shock,we also observed the following:(i)engaged RNA polymerase Ⅱ accumulated downstream of transcription start sites;(ii)5′pausing release was a ratelimiting step for the induction of some heat shock protein genes;(iii)numerous genes switched transcription modes;(iv)pervasive read-through was induced at terminators;and(v)heat stress memory occurs at multiple steps of the transcription cycle,such as at Pol Ⅱ recruitment,5′pausing,elongation,and termination.

An Open-Source System for In Planta Gene Stacking by Bxbl and Cre Recombinases

The rapid development of crops with multiple transgenic traits arouses the need for an efficient system for creating stacked cultivars. Most major crops rely on classical breeding to introgress the transgene from a laboratory variety to the numerous cultivars adapted to different growing regions. Even with vegetative propagated crops, genetic crosses are conducted during varietal improvement prior to vegetative cloning. The probability to assort the ＇x＇ number of transgenic loci into a single genome may seem trivial, （~）x for a diploid species, but given the ＇y＇ number of other nontransgenic traits that breeders also need to assemble into the same genome, the （~）~＊y probability for a ＇breeding stack＇ could quickly make the line conversion process unmanageable. Adding new transgenes onto existing transgenic varieties without creating a new segregating locus would require site-specific integration of new DNA at the existing transgenic locus. Here, we tested a recombinase-mediated gene-stacking scheme in tobacco. Sequential site-specific inte- gration was mediated by the mycobacteriophage Bxbl integrase-catalyzed recombination between attP and attB sites. Transgenic DNA no longer needed after integration was excised by Cre recombinase-mediated recombination of Iox sites. Site-specific integration occurred in -10% of the integration events, with half of those events usable as substrates for a next round of gene stacking. Among the site-specific integrants, however, a third experienced gene silencing. Overall, precise structure and reproducible expression of the sequentially added triple traits were obtained at an overall rate of -3% of the transformed clones--a workable frequency for the development of commercial cultivars. Moreover, since nei- ther the Bxbl-att nor the Cre-lox system is under patent, there is freedom to operate,

Oil crops: From the classical traits to genetic improvement

Soybean, oilseed rape, peanut, and so on, are importantresources of vegetable oil for human beings. Cultivation and production of these oil crops are expected to increase due to continuous population growth, which poses a challenge to the genetic improvement of oil crops.