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1.
本文讨论复合数论函数sφ(n)=s(φ(n))的性质。这里s(n)是因数和函数,φ(n)是欧拉函数。证明了(pi是不同的奇素数,k=1,2,3),并猜想上述不等式对任何整数k≥1都成立。如果此猜想正确,则sφ(n)≥n对任何奇数n都成立。本文还求得数论方程sφ(n)=n的5个奇数解:F0,F0F1,F0F1F2,F0F1F2F3,F0F1F2F3F4(Fi是前5个费马素数)和2个偶数解:22μ3,23μ2μ5(μ2=3,μ3=7,μ5=31是前3个默森素数)。  相似文献   

2.
牛泡沫病毒LTR的反式激活因子靶序列研究   总被引:2,自引:0,他引:2  
牛泡沫病毒(BFV)是反转录病毒科泡沫病毒属成员之一.其基因组除编码gag,pol,env三个结构基因外,在env和3'LTR之间有2个ORF(ORF-1和ORF-2),编码自身的反式激活因子Tas等调节蛋白.本研究利用我们实验室分离鉴定的BFV3026中国毒株[12]为材料,克隆Orf-1基因,构建pBFVORF-1表达质粒,通过带有luc基因的LTR系列缺失质粒与pBFVORF-1共转染,瞬时表达分析结果将BFVLTR上Tas应答元件(TRE)定位于-983/-668(TREI),-470/-140(TREI)和RU5区.其中TREI、TREII为正调控区域,RU5为负调控区域,并进一步证明RU5在异源启动子(BIVLTR)上具有抑制其下游基因表达的功能.这些结果表明BFVTas作用机理与慢病毒(Tat),致瘤病毒(Tax)等均不相同  相似文献   

3.
由HMnO4和(NH4)6Mo7O24;4H2O合成了标题化合物K0.5(NH4)5.5「MnMo9O32」.6H2O用X-射线测定了晶体结构,该化合物的晶体属三方晶系,空间群R32;a=15.846(4),C=12.396(30)A,Mr=1657.28,V=2695.6A^3,Z=3,Dc=3.82g/cm^3,μ41.5=cm^-1,F(000)=2967和3024个可观测衍射「Fp≥3σ(  相似文献   

4.
由KMnO4和(NH4)6Mo7O244H2O合成了标题化合物K0.5(NH4)5.5[MnMo9O32]6H2O,用x-射线测定了晶体结构.该化合物的晶体属三方晶系,空间群R32;a=15.846(4),C=12.396(3),Mr=1657.28,V=2695.63,Z=3,Dc=3.82g/cm3,μ=41.5cm-1,F(000)=2967.对3024个可观测衍射[F0≥3σ(F0)]最终偏离因子R=0.037,Rw=0.043.结构测定表明:Mn(Ⅳ)与6个氧配位形成键长相同的MnO6八面体,它位于[MnMo9O32]6-阴离子的中心,而Mo(Ⅵ)均与氧原子六配位,形成9个畸变的MoO6八面体.  相似文献   

5.
14种二茂铁亚胺类化合物的制备和紫外—可见光谱研究   总被引:1,自引:0,他引:1  
报道了9种取代苯胺基亚胺二茂铁类化合物R-N=CHFc[R为C6H5-nXn(X=H,4Br4SO3H,4OCH3,2,4(NO2)2和2,4(NO2)2C6H4NH]及5种取代苯亚甲基亚胺二茂铁类化的Xn(2OH)C6H4-nCH=N-Fc[X=H,5-Br,5-NO2,3NO25Br,3,5(NO2)2]的制备,测定了它们的紫外光谱,指定了谱带的归属,并对谱带的位移从理论上予以解释。  相似文献   

6.
报道了9种取代苯胺基亚胺二茂铁类化合物R-N=CHFc[R为_6H_(5_a_x_a(x=H,4 Br,4SO_3H,4OCH_3,2,4(NO_2)_2)和2,4(NO_2)_2C_6H_4NH]及5种取代苯亚甲基亚胺二茂铁类化合物x_n(2OH)C_6H_(4-n)。CH=N—Fc[x=H,5-Br,5-NO_2,5NO:5Br3,5(NO_2)_2]的制备,测定了它们的紫外光谱,指定了谱带的归属,并对谱带的位移从理论上予以解释。  相似文献   

7.
首次合成了5′-O-对甲苯磺酰基-2′,3′-二脱氢-2′,3′-二脱氧腺苷(5′-TsO-D4A)、5′-O-对甲苯磺酰基-2′,3′-二脱氧尿苷(5′-TsO-D4U)、5′-O-对甲苯磺酰基-2′,3′-二脱氧尿苷(5′-TsO-DDU)等三个对甲苯磺酰化的脱氧核苷修饰物,并通过1HNMR、UV/Vis、MS等方法进行了表征.对脱氧核苷及其5′修饰物二维COSY谱的测定为糖环上各类氢原子正确归属提供了依据.  相似文献   

8.
四甲基环戊二烯与五羰湛铁在二甲苯中加热回流6h,即生成标题化合物1,1与碘在氯仿中反应生成Fe-Fe键断裂在铁碘化物(C5HMe4)Fe(CO)2I,2,1与氯化汞反应生成Fe-Fe键断裂的铁氯汞化物(C5HMe4)Fe(CO)2HgCl3和铁氯化物(C5HMe4)Fe(CO)2Cl4.1与氯化亚锡反应仅分离到铁氯化物4.以元素分析,IR和HNMR谱表征化合物1~4的结构。  相似文献   

9.
在乙醇溶液中合成了三种稀土与L-酪氨酸、甘氨酸的三元固态配合物RE(Tyr)1.5(Gly)4(ClO4)3(RE=Pr、Eu、Tb).并通过摩尔电导、红外光谱、热谱和荧光光谱等进行了表征。铽(Ⅲ)配合物的荧光强度(Tb:5D4→7F6、7F5、7F4)比铽(Ⅲ)水合高氯酸盐增大了一个数量级.  相似文献   

10.
四甲基环戊二烯与五羰基铁在二甲苯中加热回流6h,即生成标题化合物1,1与碘在氯仿中反应生成Fe-Fe键断裂的铁碘化物(C5HMe4)Fe(CO)2I2,1与氯化汞反应生成Fe-Fe键断裂的铁氯汞化物(C5HMe4)Fe(CO)2HgCl3和铁氯化物(C4HMe4)Fe(CO)2Cl4.1与氯化亚锡反应仅分离到铁氯化物4.以元素分析,IR和1HNMR谱表征了化合物1~4的结构.  相似文献   

11.
利用Tn5转座子构建杆状病毒AcMNPV随机突变体的初步研究   总被引:3,自引:2,他引:1  
以杆状病毒模式种AcMNPV为研究对象,应用基于Tn5转座子的随机转座的方法,构建杆状病毒突变体库将果蝇hsp70启动子后接绿色荧光蛋白基因后插入Tn5转座子,构建了可以在昆虫细胞中表达,易于跟踪的转座载体.利用体外转座系统将转座子随机插入AcMNPV基因组,并用转座反应液转染Sf21细胞,得到了表达绿色荧光蛋白的病毒突变体库进一步纯化了两株病毒B9F和Li6A,进行了转座子插入位点的分析,确定两株病毒中,转座子分别插入了94K基因和p10基因.该方法将为杆状病毒功能基因组研究提供重要的手段。  相似文献   

12.
 苏云金芽孢杆菌工程菌株TnX对蚊幼虫具有高毒力,但红霉素抗性基因的存在限制了其商品化。根据转座子Tn917载体的基因序列,利用重叠延伸PCR法克隆同源重组序列到pRN5101上得到pRN15,根据pBU4载体上的四环素抗性基因序列,对pRN15进行改造,使其失去红霉素抗性,获得四环素抗性,载体命名为pRNT15。重组载体四环素抗性的获得,使之扩大了使用范围,也为工程菌株染色体中红霉素抗性基因的敲除奠定了基础。  相似文献   

13.
W L Wishart  J R Broach  E Ohtsubo 《Nature》1985,314(6011):556-558
Transposons are discrete segments of DNA which are capable of moving from one site in a genome to many different sites. Tn3 is a prokaryotic transposon which is 4,957 base pairs (bp) long and encodes a transposase protein which is essential for transposition. We report here a simple method for purifying Tn3 transposase and demonstrate that the transposase protein binds specifically to the ends of the Tn3 transposon in an ATP-dependent manner. The transposase protein binds to linear double-stranded DNA both nonspecifically and specifically; the nonspecific DNA binding activity is sensitive to challenge with heparin. Site-specific DNA binding to the ends (inverted repeats) of Tn3 is observed only when binding is performed in the presence of ATP; this ATP-dependent site-specific DNA binding activity is resistant to heparin challenge. Our results indicate that ATP qualitatively alters the DNA binding activity of the transposase protein so that the protein is able to bind specifically to the ends of the Tn3 transposon.  相似文献   

14.
耐热碱性磷酸酯酶基因的DNA序列分析   总被引:1,自引:0,他引:1  
从栖热菌中克隆到产耐热碱性磷酸酯酶(FD-TAP)基因并进行了DNA序列分析,结果表明此2.0kb的片段含有一个1056bp的开放阅读框,编码501个氨基酸的蛋白质,其N端有一26个氨基酸的信号肽.在起始密码子的上游5bp处有一个5'-GGAGGT-3'的SD序列.基因编码区的(G+C)%为68.7%,第3位密码子(G+C)%为92.7%.FD-TAP的氨基酸序列与大肠杆菌等生物的碱性磷酸酯酶氨基酸序列比较,相同性为27%,相似性为38%.中央β-折叠区及与活性中心相关的氨基酸残基高度保守.表明FD-TAP具有与大肠杆菌碱性磷酸酯酶相似的结构和作用机制.在相当于大肠杆菌碱性磷酸酯酶的His370至His412两个金属离子结合部位之间,FD-TAP有一72个氨基酸的插入片段,提示该插入片段与FD-TAP的高耐热性相关.  相似文献   

15.
从Tn5转座子介导的AcMNPV随机插入突变体库中,分离到一株复制正常的突变体AcApra41.突变定位发现Tn5转座子插入了病毒p95基因中.为了排除AcApra41中还有其他突变,利用同源重组法构建了p95基因定点插入突变的重组病毒AcGFP-P95in.PCR确认p95基因中插入了Tn5转座子;Western blot也证实AcApra41和AcGFP-P95in感染的细胞中,P95蛋白的分子量都因为插入突变而变小,由野生型的95 ku变为 55 ku.病毒复制动态曲线和荧光显微镜观察证实带有该插入突变的病毒能够在Sf9细胞中正常复制,并表达极晚期基因.这一结果表明完整的P95蛋白对病毒复制是非必须的.  相似文献   

16.
A transposon-shuttle vector Hanpvid was constructed by using wild-type genomic DNA fromHeliothis armigera nuclear polyhedrosis virus (HaNPV). It could replicate inE. coli cells as a large plasmid and remain infectious when being induced into insect cells. Hanpvid comprises HaNPV DNA and a transposon cassette which includes a miniF replicon, a kanamycin resistance gene (kan), lacZa and an attachment site for Tn7 (attTn7). Recombinant virus rHa-FaGP was obtained after transposition of a donor plasmid carrying green fluorescent protein gene (gfp) and polyhedrin gene (ocu) into attTn7. SDS-PAGE analysis shows that both gfp and ocu genes were highly expressed inHeliothis armigera cells. Green Hemolymphocytes can be seen under a fluorescent microscope 4 d after recombinant virus rHa-FaGP infected the third-instar larvae. The infected larvae show strong green fluorescence 6 d post infection.  相似文献   

17.
Transposition of Tn554 does not generate a target duplication   总被引:2,自引:0,他引:2  
E Murphy  S L?fdahl 《Nature》1984,307(5948):292-294
Transposable elements from prokaryotic and eukaryotic organisms are discrete DNA segments bounded by inverted or directly repeated sequences that insert into non-homologous DNA in a reaction that is independent of the general recombination functions of the host. The mechanisms proposed generally involve a staggered double-stranded scission of the target DNA, ligation to the nicked ends of the transposable element, and replication of the element, resulting in the generation of a directly repeated oligonucleotide target sequence flanking the new copy of the element. Most transposons have a relatively low degree of target site specificity coupled with a low insertion frequency. Tn554, a Staphylococcus aureus transposon which specifies resistances to erythromycin and spectinomycin, displays an unusually high degree of insertion specificity. Tn554 transposes with high efficiency to a unique ('primary') site in the S. aureus chromosome and only rarely (less than 10(-6) per transductant) to other, secondary sites. We report here the nucleotide sequences surrounding the junctions of Tn554 in three independent 'primary' insertions and two 'secondary' insertions of the transposon. Two unusual features are revealed: first, the termini of Tn554 contain neither inverted nor directly repeated sequences. Second, transposition of Tn554 does not generate the short direct repeats of the target DNA that are characteristic of other transposable elements. These results suggest that the mechanism of Tn554 insertion may be significantly different from that of other transposons.  相似文献   

18.
茄假单胞菌寄主花生特异性毒性基因的定位   总被引:3,自引:0,他引:3  
通过对从茄假单胞菌中克隆的pGX1252进行亚克隆分析,发现含pGX1252右边4.5kbKpnI/EcoRI片段的亚克隆pGX1404仍象pGX1252一样能使对花生不致病菌株T2014在花生上致病.用转座子Tn5-loc对pGX1404进行了饱和插入诱变,一共分离得到6个在pGX1404上不同位置的独立插入突变,其中离pGX1404右末端约1.4kb、2.2kg的两个Tn5-loc插入使pGX1404丧失了扩大T2014寄主范围的能力,证实hsv基因位于pGX1404的右边.  相似文献   

19.
20.
To understand the antagonistic mechanism of the broad spectrum antagonistic Enterobacter cloacae B8,Tn5 transposon-mediated mutagenesis is performed using suicide plasmid pZJ25. Two mutant strains that lost antagonistic character are isolated. Tagging with kanr gene on Tn5,an antagonistic related DNA fragment, the F fragment, right of the Tn5 insertion site is cloned in a plasmid named pTLF,from one of the mutant strains B8F. The 733 bp F fragment is then sequenced after subcloning. Genomic DNA of the original B8 strain is isolated, digested with Pst I and ligated to Pst I cassette. DNA fragments left and right of the F fragment are amplified from the Pst I cassette library using cassette primer and specific primers designed according to known sequence. 1106 bp sequence left of the F fragment and 664bp sequence right of the F fragment are finally obtained. Bioinformatics analysis shows that the contig assembled from the sequences of the cloned antagonistic related DNA fragments of B8 encodes three ORFs and is homogeneous to admM,admN and admO genes of Pantoea agglomerans andrimid biosynthetic gene cluster (AY192157). The ORF, named anrF gene which encodes a polyketide synthase, knocked out by Tn5 insertion, is a homology of admM and the insertion site of Tn5 is at 214 bp upstream of the stop codon. It is concluded that the anrF gene is a gene related to the antagonistic activity of E. cloacae B8, and speculated that the antagonistic substance produced by B8 is an andrimid.  相似文献   

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