Prime Editing: An All-Rounder for Genome Editing

Prime editing (PE), as a “search-and-replace” genome editing technology, has shown the attractive potential of versatile genome editing ability, which is, in principle, currently superior to other well-established genome-editing technologies in the all-in-one operation scope. However, essential technological solutions of PE technology, such as the improvement of genome editing efficiency, the inhibition of potential off-targets and intended edits accounting for unexpected side-effects, and the development of effective delivery systems, are necessary to broaden its application. Since the advent of PE, many optimizations have been performed on PE systems to improve their performance, resulting in bright prospects for application in many fields. This review briefly discusses the development of PE technology, including its functional principle, noteworthy barriers restraining its application, current efforts in technical optimization, and its application directions and potential risks. This review may provide a concise and informative insight into the burgeoning field of PE, highlight the exciting prospects for this powerful tool, and provide clues for questions that may propel the field forward.     

Density Functional Theory Study of Low-Dimensional (2D, 1D, 0D) Boron Nitride Nanomaterials Catalyzing Acetylene Acetate Reaction

In this paper, density functional theory (DFT) was used to study the possibility of low-dimensional (2D, 1D, 0D) boron nitride nanomaterials to catalyze acetylene acetate reaction, and further explore the possible source of this catalytic activity. It is found that the catalytic activity of boron nitride nanomaterials for acetylene acetate reaction will change with the change of the geometric structure (dimension) and reaction site of the catalyst. From the geometric structure, the reaction components and the zero-dimensional BN catalyst can form chemical bonds and form complexes, while only physical adsorption occurs on the surface of the one-dimensional and two-dimensional BN catalysts. From the reaction site, the properties of different C sites on the B₁₂N₁₂NC-C₂H₂ complexes are different. Namely, a C atom connected with a B atom is more likely to have an electrophilic reaction with H⁺, and a C atom connected with an N atom is more likely to have a nucleophilic reaction with CH₃COO⁻. Through the study of three kinds of BN nanomaterials with low dimensions, we found that the zero-dimensional B₁₂N₁₂ nanocage broke the inherent reaction inertia of BN materials and showed good catalytic activity in an acetylene acetate reaction, which is very likely to be a non-metallic catalyst for the acetylene gas-phase preparation of vinyl acetate.     

Mapping QTL for Adult-Plant Resistance to Stripe Rust in a Chinese Wheat Landrace

Wheat stripe (yellow) rust is a worldwide disease that seriously reduces wheat grain yield and quality. Adult-plant resistance (APR) to stripe rust is generally more durable but usually controlled by multiple genes with partial resistance. In this study, a recombinant inbred line population was developed from a cross between a Chinese wheat landrace, Tutoumai, with APR to stripe rust, and a highly susceptible wheat cultivar, Siyang 936. The population was genotyped by genotyping-by-sequencing and phenotyped for APR to stripe rust in four consecutive field experiments. Three QTLs, QYr.sdau-1BL, QYr.sdau-5BL, and QYr.sdau-6BL, were identified for APR to stripe rust, and explained 8.0–21.2%, 10.1–22.7%, and 11.6–18.0% of the phenotypic variation, respectively. QYr.sdau-1BL was further mapped to a 21.6 Mb region using KASP markers derived from SNPs identified by RNA-seq of the two parents. In the QYr.sdau-1BL region, 13 disease-resistance-related genes were differently expressed between the two parents, and therefore were considered as the putative candidates of QYr.sdau-1BL. This study provides favorable gene/QTL and high-throughput markers to breeding programs for marker-assisted selection of the wheat stripe rust APR genes.     

Cytogenetic and Molecular Marker Analyses of a Novel Wheat–Psathyrostachys huashanica 7Ns Disomic Addition Line with Powdery Mildew Resistance

Powdery mildew caused by Blumeria graminis f. sp. tritici is a devastating disease that reduces wheat yield and quality worldwide. The exploration and utilization of new resistance genes from wild wheat relatives is the most effective strategy against this disease. Psathyrostachys huashanica Keng f. ex P. C. Kuo (2n = 2x = 14, NsNs) is an important tertiary gene donor with multiple valuable traits for wheat genetic improvement, especially disease resistance. In this study, we developed and identified a new wheat—P. huashanica disomic addition line, 18-1-5—derived from a cross between P. huashanica and common wheat lines Chinese Spring and CSph2b. Sequential genomic and multicolor fluorescence in situ hybridization analyses revealed that 18-1-5 harbored 21 pairs of wheat chromosomes plus a pair of alien Ns chromosomes. Non-denaturing fluorescence in situ hybridization and molecular marker analyses further demonstrated that the alien chromosomes were derived from chromosome 7Ns of P. huashanica. The assessment of powdery mildew response revealed that line 18-1-5 was highly resistant at the adult stage to powdery mildew pathogens prevalent in China. The evaluation of agronomic traits indicated that 18-1-5 had a significantly reduced plant height and an increased kernel length compared with its wheat parents. Using genotyping-by-sequencing technology, we developed 118 PCR-based markers specifically for chromosome 7Ns of P. huashanica and found that 26 of these markers could be used to distinguish the genomes of P. huashanica and other wheat-related species. Line 18-1-5 can therefore serve as a promising bridging parent for wheat disease resistance breeding. These markers should be conducive for the rapid, precise detection of P. huashanica chromosomes and chromosomal segments carrying Pm resistance gene(s) during marker-assisted breeding and for the investigation of genetic differences and phylogenetic relationships among diverse Ns genomes and other closely related ones.     

3D打印模型及BIM模型Web嵌入应用

3D打印模型源文件一般为特定格式的STL文件,现开发人员引入开源WebGL语言实现了HTML5页面无需安装插件即可实现3D打印模型的在线浏览,无需任何浏览器插件支持,同时引入二维码编译脚本能实现手机端扫描二维码进行模型预览和源文件下载。BIM模型Web嵌入应用借助3dsmax开放式插件,将revit模型导入到3dsmax,3dsmax安装开放式模型上传插件实现一键生成HTML5可直接打开的三维模型并附带渲染的纹理模型,浏览器终端支持旋转、放大、漫游及简易交互功能,可深入应用前景广阔。     

沿空掘巷卸压消突合理煤柱宽度的确定

为确保突出煤层巷道布置在卸压区,实现煤巷安全高效掘进,以盛远煤矿为例,结合采空区侧支撑应力及瓦斯压力分布规律,通过数值模拟和突出危险性现场考察,确定了沿空掘巷卸压消突合理煤柱宽度。结果表明：5 m宽煤柱内部存在弹性区,能保持一定承载能力,巷道围岩变形量较小,留设5 m宽煤柱沿空掘巷恰好处于卸压消突范围内,所测钻屑瓦斯解吸指标均低于临界值,且掘巷期间瓦斯涌出量均在1.58 m³/min以下,未出现突出动力现象,实现了安全高效掘进。     

排列短块移动排序距离的新下界

近20年来,计算生物学领域一直试图用基因组重组事件来追溯物种进化的规律,因此基因组排列的重组排序问题被广泛而深入地研究.基因组重组包含翻转、移位、转位等多种形式.Bulteau等人证明排列的转位排序问题是NP-完全的.一次转位操作也称为一次块移动,短块移动是最常见的一种块移动.一次短块移动是将一个元素从排列中某个位置移动到最多偏离原来2个位置的块移动,因此也称为3-bounded 转位.针对排列短块移动排序距离问题,给出了一类特殊排列(称之为双递增排列)的短块移动排序次数的下界.以此为依据,分析原始排列中的所有最大双递增子排列,从而给出了任意排列短块移动排序次数的下界,改进了Heath和Vergara的负面结果,并为更好的近似算法的设计打下基础.     

A simple analytical model to predict liquid unloading in the horizontal gas well

An accurate prediction of the critical gas velocity for the liquid loading is of great importance for operators to select the tubing diameter for the newly dril...