Enzyme-free nucleic acid logic circuits

Biological organisms perform complex information processing and control tasks using sophisticated biochemical circuits, yet the engineering of such circuits remains ineffective compared with that of electronic circuits. To systematically create complex yet reliable circuits, electrical engineers use digital logic, wherein gates and subcircuits are composed modularly and signal restoration prevents signal degradation. We report the design and experimental implementation of DNA-based digital logic circuits. We demonstrate AND, OR, and NOT gates, signal restoration, amplification, feedback, and cascading. Gate design and circuit construction is modular. The gates use single-stranded nucleic acids as inputs and outputs, and the mechanism relies exclusively on sequence recognition and strand displacement. Biological nucleic acids such as microRNAs can serve as inputs, suggesting applications in biotechnology and bioengineering.     

应用逆转录套式PCR检测禽流感病毒核酸研究

选择禽流感病毒NP基因 ,设计并合成一对外引物和一对内引物 ,建立并优化了检测禽流感病毒核酸的逆转录套式PCR法 ,通过实验室检测结果证明 ,该方法具有高度的特异性和敏感性 ,能够用于检测所有的禽流感病毒核酸 ,最低能检测出 0 2pg的AIVRNA ;临床应用结果表明 ,该方法能够应用于规模化鸡场进行禽流感病毒检测 ,淘汰带毒或隐性感染鸡群     

核酸免疫制备豇豆胰蛋白酶抑制剂抗体的制备及初步应用

通过构建pcDNA3．1-CpTI真核表达载体，肌肉注射免疫Balb／c纯系小鼠，获得特异性的核酸免疫CpTI抗体，其效价达1：800，所获抗体可与纯化的CpTI蛋白发生特异性反应，检测OD406值和包被蛋白量相关系数为0．9961；间接法测定转cpti基因水稻结果表明，核酸免疫制备的抗体能与转基因水CpTI蛋白产生特异性反应，可用于转基因水稻cpti基因表达的定性测定。     

Photodynamic inactivation of infectious nucleic acid

Tobacco mosaic virus-infectious nucleic acid causes a color shift when combined with acridine orange, methylene blue, and safranine. A high concentration of acridine orange inactivates infectious nucleic acid even in darkness, while a mixture of nucleic acid with a low concentration of the dye must be exposed to visible light prior to inoculation for inactivation to occur.     

Codon recognition by enzymatically mischarged valine transfer ribonucleic acid

Direct evidence for the adaptor hypothesis has been obtained by examining the codon recognition of a purified Escherichia coli valine transfer ribonucleic acid which was enzymatically mischarged with phenylalanine labeled with carbn-14 by reaction with purified phenylalanyl-transfer ribonucleic acid synthetase from Neurospora crassa. The mischarged transfer ribonucleic acid recognized the valine codons but failed to recognize the phenylalanine codon when tested in trinucleotide-directed ribosomal binding assay.     

核酸疫苗全球专利简析

为分析核酸疫苗相关专利申请分布和保护状况,促进我国核酸疫苗的研究开发,强化核酸疫苗知识产权保护和运用,本研究基于专利数据库收录的核酸疫苗相关专利的公开信息,在Incopat数据库中通过关键词和IPC分类号检索,分析其专利申请趋势、地域分布和技术领域分布,并重点分析BioNTech和Inovio两家重点公司的核酸疫苗专利布局情况。结果表明,共获得相关专利申请12 746项,核酸疫苗专利申请量维持在较高水平,技术产出国和目标市场国主要包括美国、中国和其他欧美发达国家,主要申请机构多为欧美国家研发机构,BioNTech和Inovio等重点研发机构的专利布局呈现多层次、长周期、广地域等特点。本研究为我国疫苗研发企业提供了适配新专利法、强化布局和灵活运营等方面的知识产权策略,希望为我国核酸疫苗技术的发展提供参考。     

Potential metal-binding domains in nucleic acid binding proteins

A systematic search for sequences that potentially could form metal-binding domains in proteins has been performed. Five classes of proteins involved in nucleic acid binding or gene regulation were found to contain such sequences. These observations suggest numerous experiments aimed at determining whether metal-binding domains are present in these proteins and, if present, what roles such domains play in the processes of nucleic acid binding and gene regulation.     

Origin of life. A simpler nucleic acid

What was the genetic material of the earliest life forms on Earth if it was not RNA? As Orgel explains in his Perspective, the answer may be simpler nucleic acid polymers perhaps like the RNA analogs called (L)-a-threofuranosyl oligonucleotides or TNAs (Sch?ning et al.). These molecules have threose rather than ribose in their sugar-phosphate backbones and yet retain many of the properties of RNA including the ability to pair up in double helices.     

基于自适应中心对称局部二值模式的作物病害识别方法

基于局部二值模式(LBP)算子在模式识别中直方图维数高、判别能力差、具有冗余信息等缺点,针对作物病害叶片图像的特点,提出一种自适应中心对称局部二值模式(Adaptive Center-Symmetric Local Binary Patterns,ACSLBP)算法,并应用于作物病害识别。该算法能够得到光照和旋转不变性的纹理特征,利用模糊C均值聚类算法对病害叶片图像进行分割,再将分割后的病斑图像进行分块,然后采用自适应阈值提取每个子块的ACSLBP纹理直方图,结合作物病害叶片图像的颜色特征,利用最近邻分类器识别作物病害。在黄瓜4种常见病害叶片图像数据库上进行试验,平均识别率高达95%以上,表明该方法是有效可行的。     

核酸疫苗研究新进展

核酸疫苗是90年代初从基因治疗研究领域发展起来的一种全新疫苗,又称为DNA疫苗或基因疫苗,它是把编码免疫原或与免疫原相关的外源基因克隆到真核质粒表达载体上,然后将重组的质粒DNA直接注射到动物体内,使外源基因在动物体内表达,产生的抗原激活机体的免疫系统,引发免疫反应,从而达到预防和治疗疾病的目的.与传统的灭活或弱毒疫苗、亚单位疫苗相比,核酸疫苗以具有高效性、安全性和制备简单、易于贮存运输等优点,而受到全世界的普遍关注,具有广阔的发展前景.     

邻羟基苯甲酸胁迫对不同杉木无性系叶片核酸和蛋白质合成的影响

以对邻羟基苯甲酸胁迫具有不同抗性2个杉木无性系(即忍耐型和敏感型)为对象,分析胁迫对叶片遗传物质合成的影响.结果表明:邻羟基苯甲酸胁迫对忍耐型的DNA合成多表现为抑制效应,RNA合成多表现为促进效应.而对敏感型的DNA合成多表现为促进效应,RNA合成表现为抑制效应;在胁迫初期时各胁迫浓度对敏感型的蛋白质含量的促进效应大于忍耐型,但在胁迫中后期,而对敏感型的促进效应呈下降趋势,而对忍耐型的促进效应随胁迫浓度加大而不断增大,蛋白质合成能力不断提高.表明不同抗性杉木无性系基因表达调控模式存在较大差别,随着胁迫强度增大,忍耐型RNA和蛋白质的合成量增加,使更多的蛋白质参与了对此种胁迫的响应,而使其有更好的抗逆性.     

磁性微粒在核酸研究中的应用

磁性微粒作为固相载体应用于生物分子的合成、分离和检测,是一种非常有效、快速和方便的方法。在挪威、英、美、德等国已实现了商业化并得到了广泛的应用,而我国目前还处于研究阶段。对磁性微粒在mRNA的分离与纯化、DNA的分离与纯化以及核酸的杂交、扩增、检测等核酸研究领域中的应用进行了较为全面的综述。     

植物核酸营养素在葡萄生产中的应用

以8年生葡萄品种为试材,采用叶面喷施方法,研究了植物核酸营养素对葡萄生育的影响。结果表明,植物核酸营养素时葡萄黄叶转绿,叶片增厚、枝条成熟和提高果实品质等方面效果明显;平均单粒重比时照增加18．1％,可溶性固性物含量平均提高2．0％．每667m2产值平均提高24．5％;投入产出比为1：19。     

T-cell recognition of Ia molecules selectively altered by a single amino acid substitution

T lymphocytes recognize foreign antigen together with allele-specific determinants on membrane-bound class I and class II (Ia) gene products of the major histocompatibility complex. To identify amino acids of class II molecules critical to this recognition process, the genes encoding the beta chains of the I-Ak molecule were cloned from a wild-type B-cell hybridoma and from an immunoselected variant subline showing distinct serological and T-cell stimulatory properties. Nucleotide sequencing and DNA-mediated gene transfer established that a single base transition (G----A) encoding a change from glutamic acid to lysine at position 67 in the I-Ak beta molecule accounted for all the observed phenotypic changes of the variant cells. These results confirm the importance of residues 62 to 78 in the amino terminal domain of I-A beta for class II-restricted T-cell recognition of antigen and demonstrate the ability of a single substitution in this region to alter this recognition event.     

Self-assembled water-soluble nucleic acid probe tiles for label-free RNA hybridization assays

The DNA origami method, in which long, single-stranded DNA segments are folded into shapes by short staple segments, was used to create nucleic acid probe tiles that are molecular analogs of macroscopic DNA chips. One hundred trillion probe tiles were fabricated in one step and bear pairs of 20-nucleotide-long single-stranded DNA segments that act as probe sequences. These tiles can hybridize to their targets in solution and, after adsorption onto mica surfaces, can be examined by atomic force microscopy in order to quantify binding events, because the probe segments greatly increase in stiffness upon hybridization. The nucleic acid probe tiles have been used to study position-dependent hybridization on the nanoscale and have also been used for label-free detection of RNA.