基因谱系示踪揭示Tbx18+祖细胞的多分化潜能

为探讨Tbx18+祖细胞在小鼠生长发育过程中的多分化潜能及分化的组织类型,本工作建立了Tbx18：Cre/Rosa26RLacZ谱系示踪小鼠.该示踪小鼠基于Cre/LoxP系统,能够准确及有效地示踪Tbx18+祖细胞的分化命运,通过整体胚胎及组织X-gal染色,检测分析报告基因LacZ在其中的表达情况.结果显示,在Tbx18：Cre/Rosa26RLacZ双杂合小鼠胚胎发育早期,报告基因LacZ主要在脊柱、四肢及心外膜表达|而在胚胎发育晚期则分别表达于皮肤、毛囊、肾脏、输尿管、膀胱、睾丸、输精管、椎间盘、肋软骨、心耳、心肌、冠状动脉.结果阐明,Tbx18+祖细胞在小鼠生长发育过程中具有强大的多器官及组织分化潜能,包括分化形成表皮系统,泌尿生殖系统,骨骼系统,心血管系统,并在其生长发育中发挥重要作用.     

单核苷酸多态性技术在鸡遗传变异中的研究及应用

单核苷酸多态性(SNP)是继限制性片段长度多态性、微卫星标记之后的第三代分子标记,通常呈双等位基因多态。本文从SNP的特点、SNP的发现与检测、SNP数据库、SNP的频率及其与表型的关系等方面简述了SNP在鸡遗传变异中的研究及应用进展。     

谱系示踪技术揭示Tbx18+肾脏祖细胞分化为脂肪细胞

转录因子Tbx18在泌尿系发育中发挥重要作用。利用遗传谱系示踪模型，揭示了Tbx18+肾祖细胞具有向多种肾系细胞分化的潜能。但尚无文献报道其是否具有向脂肪细胞分化的潜能。本研究通过对Tbx18Cre/Rosa26LacZ双杂合小鼠泌尿系组织进行整体X-gal染色发现，肾包膜、输尿管及肾周脂肪组织能特异性表达β-gal蛋白，说明肾包膜、输尿管及肾周脂肪组织可能来源于Tbx18+祖细胞。对Tbx18Cre/Rosa26EYFP双杂合小鼠泌尿系组织进行免疫荧光染色，发现部分脂滴相关蛋白+（perilipin）脂肪细胞能表达标记蛋白EYFP，说明部分泌尿系脂肪细胞来源于Tbx18+祖细胞。本研究揭示了Tbx18+祖细胞具有分化为脂肪细胞的潜能，进一步证实了Tbx18+肾祖细胞的多分化潜能。结合本研究结果，若进一步研究肾损伤时，来源于Tbx18+祖细胞的泌尿系脂肪细胞是否进一步增多，将会为肾损伤的再生修复提供一些思路和启发。     

Component Object Based Single System Image for Dependable Implementation of Genetic Programming on Clusters

We present a distributed component-object model (DCOM) based single system image (SSI) for dependable parallel implementation of genetic programming (DPIGP). DPIGP is aimed to significantly and reliably improve the computational performance of genetic programming (GP) exploiting the inherent parallelism in GP among the evaluation of individuals. It runs on cost-effective clusters of commodity, non-dedicated, heterogeneous workstations or PCs. Developed SSI represents the pool of heterogeneous workstations as a single, unified virtual resource – a metacomputer, and addresses the issues of locating and allocating the physical resources, communicating between the entities of DPIGP, scheduling and load balancing. In addition, addressing the issue of fault tolerance, SSI allows for building a highly available metacomputer in which the cases of workstation failure result only in a corresponding partial degradation of the overall performance characteristics of DPIGP. Adopting DCOM as a communicating paradigm offers the benefits of software platform- and network protocol neutrality of proposed approach; and the generic support for the issues of locating, allocating and security of the distributed entities of DPIGP.     

Processing‐Performance Evolution of Perovskite Solar Cells: From Large Grain Polycrystalline Films to Single Crystals

Solution‐processable halide perovskites have emerged as strong contenders for next‐generation solar cells owing to their favorable optoelectronic properties. To maintain the efficiency momentum of perovskite solar cells (PSCs), development of advanced processing techniques, particularly for the perovskite layer, is imperative. There is a close correlation between the quality of the perovskite layer and its photophysical properties: Highly crystalline large grains with uniform morphology of the perovskite layer and their interface with charge transporters are crucial for achieving high performance. Significant efforts have been dedicated to achieve perovskite films with large grains reaching the millimeter‐scale for high‐efficiency PSCs. Recent work showcases a transition from large grain polycrystalline to single‐crystalline (SC) PSCs made possible by the facile growth of perovskite single crystals. In this review, the recent progress of the large grain polycrystalline PSCs and grain boundary‐free SC‐PSCs is reported, particularly focusing on the recent approach of depositing large‐grained perovskite layers and single crystal growth technique, that have been adopted for fabrication of efficient PSCs. In addition, prospects of SC‐PSCs and their further development in terms of efficiency, device design, scalability, and stability are discussed.     

Temporal Quantification of MAPK Induced Expression in Single Yeast Cells

The quantification of gene expression at the single cell level uncovers novel regulatory mechanisms obscured in measurements performed at the population level. Two methods based on microscopy and flow cytometry are presented to demonstrate how such data can be acquired. The expression of a fluorescent reporter induced upon activation of the high osmolarity glycerol MAPK pathway in yeast is used as an example. The specific advantages of each method are highlighted. Flow cytometry measures a large number of cells (10,000) and provides a direct measure of the dynamics of protein expression independent of the slow maturation kinetics of the fluorescent protein. Imaging of living cells by microscopy is by contrast limited to the measurement of the matured form of the reporter in fewer cells. However, the data sets generated by this technique can be extremely rich thanks to the combinations of multiple reporters and to the spatial and temporal information obtained from individual cells. The combination of these two measurement methods can deliver new insights on the regulation of protein expression by signaling pathways.     

基因谱系示踪技术揭示小鼠Tbx18+心脏祖细胞向心系细胞分化的潜能

心脏祖细胞(cardiac progenitor cells,CPCs)的研究对阐明先天性心脏病的机制及治疗心血管疾病具有重要意义.哺乳动物的心脏组织由多种不同CPCs分化形成.转录因子Tbx18在发育中的心外膜中表达,对心脏的发育形成起重要的调节作用.为了在组织及活体细胞水平检测和阐明Tbx18+CPC的分化潜能,应用Cre-LoxP系统建立Tbx18+CPCs基因命运谱系示踪模型:Tbx18-Cre/Rosa26R-EYFP和Tbx18-Cre/Rosa26R-LacZ双杂合基因敲入小鼠.该双杂合基因敲入小鼠通过Cre的表达能有效地示踪Tbx18+细胞在胚胎和成年小鼠中的分化命运.Tbx18-Cre/Rosa26R-EYFP双杂合小鼠心脏能非常容易地利用流式细胞分选系统(FACS)分离出YFP+细胞,也可在倒置共聚焦显微镜下观察.应用X-gal染色分析其表达模式,揭示Tbx18命运谱系参与心房肌、室间隔、心室肌、冠状动脉、瓣膜等的形成.应用免疫荧光技术初步揭示Tbx18+CPCs向心脏肌钙蛋白T(cTNT)阳性心肌细胞和平滑肌肌球蛋白重链11(MYH11)阳性血管平滑肌细胞分化的潜能.心脏是一个由多种肌肉和非肌肉组织细胞构成的复杂器官.推测Tbx18可能在心脏祖细胞向肌源性细胞分化的信号通路中起重要调节作用.在上述研究中应用基因谱系示踪技术,验证Tbx18可作为一类CPCs的标志,为更深入揭示心脏祖细胞向心系细胞的分化潜能打下基础.     

Interaction of Microwaves and a Temporally Incoherent Magnetic Field on Single and Double DNA Strand Breaks in Rat Brain Cells

The effect of a temporally incoherent magnetic field noise on microwave-induced DNA single and double strand breaks in rat brain cells was investigated. Four treatment groups of rats were studied: microwave-exposure (continuous-wave 2450-MHz microwaves, power density 1 mW/cm², average whole-body specific absorption rate of 0.6 W/kg), noise-exposure (45 mG), microwave + noise-exposure, and sham-exposure. Animals were exposed to these conditions for 2h. DNA single- and double-strand breaks in brain cells of these animals were assayed 4h later using a microgel electrophoresis assay. Results show that brain cells of microwave-exposed rats had significantly higher levels of DNA single- and double-strand breaks when compared with sham-exposed animals. Exposure to noise alone did not significantly affect the levels (i.e., they were similar to those of the sham-exposed rats). However, simultaneous noise exposure blocked microwave-induced increases in DNA strand breaks. These data indicate that simultaneous exposure to a temporally incoherent magnetic field could block microwave-induced DNA damage in brain cells of the rat.     

NBS1基因SNPs与中国汉族人群原发性肝癌的遗传易感性

为分析DNA损伤修复相关基因NBS1单核苷酸多态性(SNPs)与原发性肝癌遗传易感性的关系,并对高分辨率单链构象多态性(SSCP)检测技术在SNPs分型中的适用性进行评估,本研究对来自中国汉族人群的327例原发性肝癌以及295例阴性对照中NBS1基因常见SNPs的稀有等位基因频率进行检测和分析．此外,对NBS1基因6个常见SNPs分别选择部分样本同时进行直接序列测定,以比较2种方法的检测效果．119例原发性肝癌以及95例肝硬化/慢性肝炎组织标本的SSCP分析结果表明,6个常见NBS1基因SNPs位点(102G>A, 320+208G/A, 553G>C, 1197T>C, 2016A>G和2071-30A>T)中,SNP 1197T>C的稀有等位基因频率为68.1%,显著高于肝硬化/慢性肝炎对照的57.9% (P = 0.0298)．对该SNP位点另外采用208份肝细胞癌和200份健康人群血液标本进一步分析, 肝细胞癌SNP 1197T>C的稀有等位基因频率为66.8%,显著高于健康人群对照的58.8% (P = 0.0170)．其他5个SNPs的稀有等位基因频率在原发性肝癌与肝硬化/慢性肝炎之间均无显著性差异．高分辨率SSCP分析法与直接序列测定法对所选样本的SNPs基因分型结果完全一致,而且直接测序法对PCR扩增产物质量的要求相对高分辨率SSCP分析更高．研究表明,中国汉族人群NBS1基因SNP 1197T>C可能与原发性肝癌的发生相关,高分辨率SSCP技术准确度与直接测序法相当,且操作更加简便易行,非常适用于大量样本多个已知SNPs的基因分型．