一类随机环境下随机游动的保守集和常返性

就一类平稳遍历随机环境ξ下随机游动{Xn}n∈Z 给出相应的Markov-双链{Xn}n∈Z ={(Xn,Tnξ)}n∈Z 的保守集,和在该平稳遍历环境ξ下{Xn}n∈Z 为常返链的条件。     

黄刺莓和金针花粉营养成分的研究

通过对黄刺莓和金针花粉的DNA，RNA，磷脂，葡萄糖氧化酶，氨基酸，VA，VE和VC等重要营养成分的测定，发现这两种花粉的营养成分丰富，配比良好，特别是VA，VE，VC和必需氨基酸的质量比较高，RNA和DNA的质量比也较高。黄刺莓花粉和金针花粉具有很好的应用价值。     

合成U3snRNA基因上游启动区构建ACC合成酶反义RNA-核酶嵌合基因的植物表达载体

利用反义 RNA和核酶进行基因表达调控是当今植物分子生物学的研究热点之一 .但在转基因植物中 ,利用 RNA聚合酶 型启动区表达效率不高 .番茄 U3sn RNA基因由 RNA聚合酶 来转录 ,具有较高的转录效率 ,为一般转录效率的 1 0 0～ 1 0 0 0倍 .我们人工合成了番茄 U3sn RNA基因上游启动区 ( 1 5 2 bp) ,构建到番茄 ACC合成酶的反义 RNA-核酶嵌合 DNA序列的上游 ,然后将“启动区 -反义 RNA-核酶嵌合 DNA序列”插入到植物双元表达载体p GA6 4 3中 ,并用三亲融合法导入农杆菌 LBA4 40 4中 ,为研究 U 3sn RNA上游启动区增强反义 RNA-核酶基因的表达奠定了基础     

CS_2在Ag-S键中的插入反应(Ⅲ)——[PyAg(SC_6H_2Bu_3~t-2,4,6)]_n及其CS_2插入产物[(PPh_3)_2Ag(S_2CSC_6H_2Bu_3~t-2,4,6)]·CHCl_3的合成和晶体结构

2,4,6-三特丁基硫酚银化合物在吡啶中重结晶,获得一维双链带状高聚物[PyAg(SC_6H_2Bu_3~t-2,4,6)]~n(晶体Ⅰ)。该硫酚银化合物在三苯基膦存在下与CS_2反应,得到单核银的CS_2插入产物[(PPh_3)_2Ag(S_2CSC_6H_2Bu_3~t-2,4,6)]·CHCl_3(晶体Ⅱ)。用X射线单晶衍射法测定了它们的晶体结构。     

在大肠杆菌中利用反义RNA抑制乙肝病毒（HBV）X基因的表达

将乙肝病毒（ＨＢＶ）ａｙｗ株完整的Ｘ基因正向重组到原核表达质粒ｐＢＶ－２２１的ＰＬ启动子下游，得到能表达Ｘ蛋白的重组质粒ｐＢＶ－ＨＢＶ（＋）；同时将Ｘ基因反向重组到原核表达质粒ｐＢＶ－２２０的ＰＬ启动子下游，得到能转录Ｘ基因反义ＲＮＡ的重组质粒ｐＢＶ－ＨＢＸ（－）。利用这两个质粒，构建出能同时转录Ｘ基因ｍＲＮＡ和反义ＲＮＡ的重组质粒ｐＥＸ。ＡＮ－ＨＢＸ，并在原核水平上，证实了反义ＲＮＡ对Ｘ基因的表     

反义RNA阻抑基因表达的精确模型——萤火虫荧光素酶基因-爪蟾卵母细胞系统

80年代建立的“反义基因操作技术”不仅打破了通过基因突变认识基因的局限,成为了解基因功能新的有效工具.而且,还拓宽了借助基因操作治疗疾病和改良植物品质的应用途径。虽然,至今仍未取得真核细胞能利用自身存在的反义RNA调节基因表达的证据,但是,人工构建的反义RNA或反义基因能有效地抑制细胞内源或外源基因的暂时性或稳定性表达已有越来越多的报道.只是对抑制机理,最适抑制条件等仍了解很少.本文报道含荧光素     

从微量全血直接进行反转录-聚合酶链反应

在转录水平上研究基因表达及调控,通常要求制备纯度高、未降解的总RNA。提取总RNA的方法一般较复杂。Kawasaki描述过一个从1—2ml全血制备RNA的方法。本文报道了一个更为简便的从微量全血不经抽提RNA直接进行RT-PCR的方法。即将2—20μ1全血低渗破红细胞,离心得到白细胞沉淀,在有RNA酶抑制剂存在的条件下再低渗使白细胞破坏,释放出RNA。此液直接用于RT—PCR,并与用AGPC法抽提的总RNA为     

21世纪的RNA研究

美国<科学>周刊分别于2001年、2002年初评出上一年度的世界十大科学突破,RNA研究均位居第二:生命可能始于RNA,而非DNA;RNA干扰在使哺乳动物细胞的基因表达沉默和RNA在调控方面的很多新发现超出了科学家原先的想象.国际上,RNA研究正在受到人们前所未有的关注.     

AC2 and AC4 proteins of <Emphasis Type="Italic">Tomato yellow leaf curl China virus</Emphasis> and <Emphasis Type="Italic">Tobacco curly shoot virus</Emphasis> mediate suppression of RNA silencing

Tomato yellow leaf curl China virus Y10 isolate (TYLCCNV-Y10) alone could systemically infect host plants such as Nicotiana benthamiana without symptoms. In contrast, Tobacco curly shoot virus Y35 isolate (TbCSV-Y35) alone induces leaf curl symptoms in N. benthamiana. When inoculated into transgenic N. benthamiana plants expressing GFP gene (line 16c), TYLCCNV-Y10 neither reverses the established GFP silencing nor blocks the onset of GFP silencing. In contrast, TbCSV-Y35 can partially reverse the established GFP silencing and block the onset of GFP silencing in new leaves. In the patch co-infiltration assays, the AC2 and AC4 proteins of TYLCCNV-Y10 and TbCSV-Y35 could suppress local GFP silencing and delay systemic GFP silencing, suggesting that they are suppressors of RNA silencing. Comparison of the accumulation levels of GFP mRNA in the co-infiltration patches showed that Y10 AC2 and Y35 AC2 proteins had similar efficiency for suppression of RNA silencing. However, Y35 AC4 protein functioned as a stronger suppressor of RNA silencing than Y10 AC4 protein. There-fore, the pathogenicity difference between TbCSV-Y35 and TYLCCNV-Y10 may be related to the functional difference in their AC4 proteins.     

Lymphotactin enhances the in-vitro immune efficacy of dendritoma formed by dendritic cells and mouse hepatocellular carcinoma cells

Objective: To investigate the in-vitro antitumor immune responses of dendritoma formed by mouse hepatocellular carcinoma (HCC) cells and lymphotactin (Lptn) gene modified dendritic cells (DCs). Method: DCs prepared from mouse bone marrow were genetically modified by lymphotactin adenovirus, and fused with H22 cells by polyethylene glycol (PEG). RT-PCR and ELISA were employed to identify lymphotactin expression at mRNA and protein level. Cell phenotypes and fusion efficiency was detected by FACS. The stimulatory effect of DC on T cells was detected by mixed lymphocyte reaction. The cytotoxicity activity against H22 cells was assayed by LDH method. Results: Lymphotactin could be efficiently expressed by DCLptn/H22 hybridoma. DCLptn/H22 cells could induce potent T cell proliferation effect and generate strong cytotoxic T lymphocyte (CTL) reaction against allogenic H22 cells. Conclusion: Lymphotactin genetic modification could enhance the in vitro immune activity of the dendritoma.