In 1985 Brinster et al. [1] observed that linearized DNA injected in the cytoplasm of mouse zygotes underwent spontaneous supercoiling within 24 h. This finding suggests that DNA prefers and functions best in tertiary...In 1985 Brinster et al. [1] observed that linearized DNA injected in the cytoplasm of mouse zygotes underwent spontaneous supercoiling within 24 h. This finding suggests that DNA prefers and functions best in tertiary structure. In an effort to improve the efficiency of transgenesis by cytoplasmic injection, DNA was condensed with MgCl2to form a three dimensional rod-shaped DNA prior to injection in pronuclear stage murine zygotes. The DNA used was enhanced green fluorescent protein on a cytomegalovirus promoter (CMV-EGFP) and served as a marker for gene integration and protein expression in culture conditions. The condensed CMV-EGFP construct was injected in the cytoplasm at 3 concentrations (100, n = 816;425, n = 464;and 625 μg/ml, n = 708). For comparison linear CMV-EGFP construct was injected into the pronucleus (5 μg/ml, n = 196) and into the cytoplasm (625 μg/ml, n = 628). In all treatment groups the control and buffer injected embryos developed similarly. Among DNA treatment groups, the highest development of fluorescing embryos was observed in zygotes injected in the cytoplasm with linear CMV-EGFP (625 μg/ml);however, zygotes injected in the cytoplasm with condensed CMV-EGFP (625 μg/ml) had the highest percentage (44%) of fluorescing embryos, the highest percentage (16.7%) of fluorescing morula and blastocysts, and the lowest percentage of fluorescence mosaicism at every stage of embryo development after 4 d in culture;thereby making it the best method for generating transgenic animals.展开更多
由于人类DNA序列上单核苷酸具有多态性,DNA序列异常挖掘是后基因组时代的一个重要研究课题。文章在分析现有DNA序列数据挖掘方法的基础上,利用流形学习中不同低维嵌入向量之间向量距离不同的特点,提出了基于流形学习的DNA序列数据挖掘方...由于人类DNA序列上单核苷酸具有多态性,DNA序列异常挖掘是后基因组时代的一个重要研究课题。文章在分析现有DNA序列数据挖掘方法的基础上,利用流形学习中不同低维嵌入向量之间向量距离不同的特点,提出了基于流形学习的DNA序列数据挖掘方法(5Dlocally linear embedding,简称5DLLE)。实验结果表明,与隐马尔可夫模型(HMM)和支持向量机(SVM)相比,文中所提出的5DLLE方法在DNA序列数据挖掘方面具有一定优势,不但平均识别率高,而且计算时间相对较少。展开更多
In recent years, DNA supramolecular hydrogels have attracted much attention due to their injectability, biocompatibility, responsiveness and self-healing properties. In this work, we designed a linear DNA brick contai...In recent years, DNA supramolecular hydrogels have attracted much attention due to their injectability, biocompatibility, responsiveness and self-healing properties. In this work, we designed a linear DNA brick containing one duplex with two cytosine（C）-rich sequence on both ends. This brick can first assemble to form duplex under p H 8 condition. After adjusting the p H to 5, the C-rich sequence tends to form intermolecular i-motif structure, which joins the linear DNA molecules together to form interlocked cyclic structures and yield the DNA hydrogel. By adjusting the length and bending curvature of the duplex part of the molecule, one can change the basic unit of the hydrogel structure to tune the properties of the DNA hydrogel.展开更多
文摘In 1985 Brinster et al. [1] observed that linearized DNA injected in the cytoplasm of mouse zygotes underwent spontaneous supercoiling within 24 h. This finding suggests that DNA prefers and functions best in tertiary structure. In an effort to improve the efficiency of transgenesis by cytoplasmic injection, DNA was condensed with MgCl2to form a three dimensional rod-shaped DNA prior to injection in pronuclear stage murine zygotes. The DNA used was enhanced green fluorescent protein on a cytomegalovirus promoter (CMV-EGFP) and served as a marker for gene integration and protein expression in culture conditions. The condensed CMV-EGFP construct was injected in the cytoplasm at 3 concentrations (100, n = 816;425, n = 464;and 625 μg/ml, n = 708). For comparison linear CMV-EGFP construct was injected into the pronucleus (5 μg/ml, n = 196) and into the cytoplasm (625 μg/ml, n = 628). In all treatment groups the control and buffer injected embryos developed similarly. Among DNA treatment groups, the highest development of fluorescing embryos was observed in zygotes injected in the cytoplasm with linear CMV-EGFP (625 μg/ml);however, zygotes injected in the cytoplasm with condensed CMV-EGFP (625 μg/ml) had the highest percentage (44%) of fluorescing embryos, the highest percentage (16.7%) of fluorescing morula and blastocysts, and the lowest percentage of fluorescence mosaicism at every stage of embryo development after 4 d in culture;thereby making it the best method for generating transgenic animals.
文摘由于人类DNA序列上单核苷酸具有多态性,DNA序列异常挖掘是后基因组时代的一个重要研究课题。文章在分析现有DNA序列数据挖掘方法的基础上,利用流形学习中不同低维嵌入向量之间向量距离不同的特点,提出了基于流形学习的DNA序列数据挖掘方法(5Dlocally linear embedding,简称5DLLE)。实验结果表明,与隐马尔可夫模型(HMM)和支持向量机(SVM)相比,文中所提出的5DLLE方法在DNA序列数据挖掘方面具有一定优势,不但平均识别率高,而且计算时间相对较少。
基金financially supported by the National Basic Research Program of China(973 program,No.2013CB932803)the National Natural Science Foundation of China(No.21534007)the Beijing Municipal Science&Technology Commission
文摘In recent years, DNA supramolecular hydrogels have attracted much attention due to their injectability, biocompatibility, responsiveness and self-healing properties. In this work, we designed a linear DNA brick containing one duplex with two cytosine（C）-rich sequence on both ends. This brick can first assemble to form duplex under p H 8 condition. After adjusting the p H to 5, the C-rich sequence tends to form intermolecular i-motif structure, which joins the linear DNA molecules together to form interlocked cyclic structures and yield the DNA hydrogel. By adjusting the length and bending curvature of the duplex part of the molecule, one can change the basic unit of the hydrogel structure to tune the properties of the DNA hydrogel.
基金国家自然科学基金(the National Natural Science Foundation of China under Grant No.60403002) 浙江省自然科学基金(the NaturalScience Foundation of Zhejiang Province of China under Grant No.Y106654) 。
