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Sample records for bromouracils

  1. Insights into the Deactivation of 5-Bromouracil after UV Excitation

    CERN Document Server

    Peccati, Francesca; González, Leticia

    2016-01-01

    5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after UV irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and nonadiabatic dynamics simulations. It is found that after irradiation to the bright 1pipi* state, three main relaxation pathways are in principle possible: relaxation back to the ground state, intersystem crossing, and C-Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground state relaxation should be the predominant deactivation pathway in gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS was used in surface hopping simulations to compute the ultrafast intersystem crossing dynamics, which mostly involves the 1nOpi* and 3pipi* states.

  2. Bromouracil mutagenesis in Escherichia coli evidence for involvement of mismatch repair

    Energy Technology Data Exchange (ETDEWEB)

    Rydberg, B.

    1977-01-01

    Bromouracil mutagenesis was studied in several strains of E. coli in combination with measurement of incorporation of bromouracil in DNA. For levels below 10% total replacement of bromouracil for thymine, mutagenesis was negligible compared with higher levels of incorporation. Such a nonlinear response occurred both when the bromouracil was evenly distributed over the genome and when a small proportion of the genome was highly substituted. Also, the mutation frequency could be drastically lowered by amino acid starvation following bromouracil incorporation. These observations suggest the involvement of repair phenomena. Studies of mutagenesis in recA/sup -/ and uvrA/sup -/ mutants, as well as studies of prophage induction, did not support an ''error prone'' repair pathway of mutagenesis. On the other hand, uvrD/sup -/ and uvrE/sup -/ mutants, which are deficient in DNA mismatch repair, had much increased mutation frequencies compared with wild type cells. The mutagenic action of bromouracil showed specificity under the conditions used, as demonstrated by the inability of bromouracil to revert an ochre codon that was easily revertable by ultraviolet light irradiation. The results are consistent with a mechanism of bromouracil mutagenesis involvng mispairing, but suggest that the final mutation frequencies depend on repair that removes mismatched bases.

  3. Effects of base analogues 5-bromouracil and 6-aminopurine on development of zebrafish Danio Rerio

    Institute of Scientific and Technical Information of China (English)

    SAWANT M. S.; ZHANG Shicui; WANG Qingyin

    2005-01-01

    Zebrafish (Danio rerio) genetic screens allow isolation of a wide array of problems in vertebrate biology. The effects of base analogues 5-bromouracil and 6-aminopurine on the development of zebrafish embryos are reported for the first time in this study. The early development of the zebrafish embryos was little affected by 5-bromouracil and 6-aminopurine, while the late development (organogenesis) was significantly impaired. Embryos exposed to 5-bromouracil mainly showed curled tail, wavy body, golden pigmentation and the mouth with protruding lower jaw. 6-aminopurine-treated embryos had defective anterior structures, curled tails and wavy body. RAPD analysis showed that the majority of 5-bromouracil- and 6-aminopurine-treated larvae and fish shared banding patterns in common with the control, suggesting that most mutagenesis induced by these agents are point mutations. However, some fish derived from 5-bromouracil-treated embryos had golden (gol) pigmentation; and RAPD analysis revealed that their band patterns differed from those of the control.Possibly, 5-bromouracil can occasionally cause relatively extensive changes in the fish genome. The results of this study may provide valuable help for detailed studies of mutagenesis.

  4. Effect of 5-bromouracil and 5-bromo-2-deoxyuridine in combination with 8-azaadenine on UV sensitivity of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, H.E. (Akademie der Wissenschaften der DDR, Jena. Zentralinstitut fuer Mikrobiologie und Experimentelle Therapie); Golovinsky, E. (Bylgarska Akademiya na Naukite, Sofia)

    1983-01-01

    The presence of 5-bromouracil (BU) as well as 5-bromo-2-deoxyuridine (BUdR) in the cultivation media of bacteria results in the distinct increase of UV sensitivity. With the nucleic acid base analogue 8-azaadenine (8-AA) a similar effect was confirmed, however, not so pronounced. The combined action of BU or BUdR and 8-AA on Escherichia coli, Proteus mirabilis, Bacillus subtilis and Bacillus cereus was investigated. The sensitization effect of BUdR does not increase if 8-AA is present additionally during cultivation. On the contrary, a decrease of sensibilization occurs. This may be caused by the protective effect of the adenine derivative against UV irradiation, if it is present in the cell, but not incorporated into the DNA.

  5. 腺嘌呤-5-溴尿嘧啶复合物中的卤键%Halogen Bonds in Adenine-5-Bromouracil Complexes

    Institute of Scientific and Technical Information of China (English)

    王艳花; 李立; 卢运祥; 邹建卫

    2007-01-01

    Ab initio and density functional calculations were employed to investigate the bonding patterns in the adenine-5-bromouracil(AT+)complexes.It is shown that the Br atom in 5-bromouracil(T+)is involved in bonding both with the hydrogen atom of the amino group of adenine(A)and with N7(A)(or N1(A)).With this motif,the Br atom interacts with a nucleophile(H)in a"head-on"fashion and an electrophile(N)in a"side-on"fashion,forming both hydrogen and halogen bonds.Electrostatic attraction between the Br atom in T+and N7(or N1)of adenine was found via the electrostatic potential analysis.The existence of A bond critical point is identified for the halogen bonds and the topological parameters at the bond critical point indicate the typical closed-shellinteractions in the pairs.Natural bond orbital analysis suggests that the charge transfer from the lone pair of the nitrogen atom of adenine is mainly directed to the C-Br antibonding orbital.Finally,halogen bonds in the T+AT+A tetrads were also explored.%利用从头算和密度泛函理论研究了腺嘌呤(A)-5-溴尿嘧啶复合物中(T+)中的键合模式.研究结果表明,T+中的Br原子同时与A分子中的氨基氢和氮原子存在弱的相互作用,在这种结合模式中,Br原子与亲核基团H正面结合,同时与来电基团N侧面结合,分别形成氢键和卤键.静电势分析发现:T+中的Br原子与A中的N7(或N1)是通过静电相互吸引的.Br与N原子之间的相互作用通过分了中的原子理论得以证实.关键点的拓扑参数显示卤键是闭壳层相互作用.自然键轨道分析说明,A中N原子上孤对电子的电荷主要转移到C-Br的反键轨道.另外在T+AT+A四面体结构中也发现了卤键.

  6. Data underpinning "Stacking of the mutagenic base analogue 5-bromouracil: energy landscapes of pyrimidine dimers in gas phase and water"

    OpenAIRE

    Holroyd, Leo Frederick; van Mourik, Tanja

    2015-01-01

    The authors gratefully acknowledge EaStCHEM for computer time on the EaStCHEM Research Computing Facility. LFH is grateful to the Engineering and Physical Sciences Research Council for studentship support through the Doctoral Training Account scheme (grant code EP/K503162/1).

  7. Electron migration in oligonucleotides upon γ-irradiation in solution

    International Nuclear Information System (INIS)

    Electron migration in irradiated solutions of DNA was investigated using 5-bromouracil synthetically incorporated into oligonucleotides of defined base composition as a molecular indicator of electron interactions. Solvated electrons interact quantitatively with 5-bromouracil, leading to a highly reactive 5-yl radical which can abstract an adjacent hydrogen atom to yield uracil. Yields of uracil, or loss of 5-bromouracil, from irradiated oligonucleotide samples were measured using gas chromatography-mass spectrometric analysis of their trimethylsilylated acid hydrolysates. (author)

  8. A four-stranded DNA from Bacillus subtilis which may be an intermediate in genetic recombination

    International Nuclear Information System (INIS)

    DNA of Bacillus subtilis strain UVSS 19-8 M, of high ultraviolet sensitivity, was isolated after cultivating in medium containing bromouracil. Isopycnic banding in CsCl shows an unusual pattern with four bands, including an extra one halfway between those for hybrid and for DNA fully substituted with bromouracil. DNA of this band, amounting to 15-25% of the total DNA mass in one preparation, was isolated and investigated. The characteristics found for this DNA, namely transforming ability, electron microscopic picture, behavior during heat denaturation and gentle shear are in agreement with a fourstranded DNA unit similar to one of the structures postulated by Holliday as intermediates during genetic recombination. The amount of this DNA when the cells were given 5J/m2 of 254 nm UV. UVSS 19-8 M from which this DNA has been isolated is shown to be defective for transformation and transfection, and can be regarded as rec-. (orig./MG)

  9. Nuclear quadrupole resonance of 14N and 2H in pyrimidines, purines, and their nucleosides

    Science.gov (United States)

    Rabbani, S. R.; Edmonds, D. T.; Gosling, P.

    Using nuclear quadrupole double-resonance techniques, nitrogen-14 and deuterium nuclear quadrupole coupling constants and asymmetry parameters have been measured in uracil, 5-bromouracil, cytosine, adenine, xanthine, hypoxanthine, their nucleosides, 2-aminopyrimidine, and benzimidazole. Zeeman studies and the detection of the simultaneous transitions of neighboring nuclei allowed in many cases a complete assignment of the observed spectral lines to particular 14N and 2D sites.

  10. Enantiopurity analysis of new types of acyclic nucleoside phosphonates by capillary electrophoresis with cyclodextrins as chiral selectors.

    Science.gov (United States)

    Solínová, Veronika; Kaiser, Martin Maxmilián; Lukáč, Miloš; Janeba, Zlatko; Kašička, Václav

    2014-02-01

    CE methods have been developed for the chiral analysis of new types of six acyclic nucleoside phosphonates, nucleotide analogs bearing [(3-hydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl]phosphonic acid, 2-[(diisopropoxyphosphonyl)methoxy]propanoic acid, or 2-(phosphonomethoxy)propanoic acid moieties attached to adenine, guanine, 2,6-diaminopurine, uracil, and 5-bromouracil nucleobases, using neutral and cationic cyclodextrins as chiral selectors. With the exception of the 5-bromouracil-derived acyclic nucleoside phosphonate with a 2-(phosphonomethoxy)propanoic acid side chain, the R and S enantiomers of the other five acyclic nucleoside phosphonates were successfully separated with sufficient resolutions, 1.51-2.94, within a reasonable time, 13-28 min, by CE in alkaline BGEs (50 mM sodium tetraborate adjusted with NaOH to pH 9.60, 9.85, and 10.30, respectively) containing 20 mg/mL β-cyclodextrin as the chiral selector. A baseline separation of the R and S enantiomers of the 5-bromouracil-derived acyclic nucleoside phosphonate with 2-(phosphonomethoxy)propanoic acid side chain was achieved within a short time of 7 min by CE in an acidic BGE (20:40 mM Tris/phosphate, pH 2.20) using 60 mg/mL quaternary ammonium β-cyclodextrin chiral selector. The developed methods were applied for the assessment of the enantiomeric purity of the above acyclic nucleoside phosphonates. The preparations of all these compounds were found to be synthesized in pure enantiomeric forms. Using UV absorption detection at 206 nm, their concentration detection limits were in the low micromolar range.

  11. Radiopharmaceutical Tracers for Neural Progenitor Cells

    International Nuclear Information System (INIS)

    The Technical Report summarizes the results of the synthesis and microPET animal scanning of several compounds labeled with positron-emitting isotopes in normal, neonatal and kainic acid treated (seizure induced) rats as potential PET tracers to image the process of neurogenesis using positron emission tomography (PET). The tracers tested were 3'-deoxy-3'-[F-18]fluorothymidine ([F-18]FLT) and 5'-benzoyl-FTL, 1-(2'-deoxy-2'-[F-18]fluoro-B-D-arabinofuranosyl)-5-bromouracil (FBAU) and 3',5'-dibenzoyl-FBAU, N-[F-18]fluoroacetyl-D-glucosamine (FLAG) and tetraacetyl-FLAG, and L-[1-C-11]leucine

  12. Study of tritium labelling by solid-state catalytic reductive dehalogenation

    Energy Technology Data Exchange (ETDEWEB)

    Filikov, A.V.; Myasoedov, N.F. (AN SSSR, Moscow. Inst. Molekulyarnoj Genetiki)

    1984-04-02

    A reaction mechanism is proposed for tritium labelling by the solid-state catalytic reductive dehalogenation (SCRD) method based on hydrogen spillover. A model system (palladium membrane with a layer of the original organic compound) is used for a kinetic study of the debromination of 5-bromouracil and the isotope exchange of ..cap alpha..-alanine at pressure of 0.07-20 kPa. A kinetic model is considered for the spillover stoppage due to the contamination of penetration centres by the reaction product. Other possible causes of the spillover stoppage are discussed. 6 refs.; 3 figs.

  13. Effects of some inhibitors of protein synthesis on the chloroplast fine structure, CO2 fixation and the Hill reaction activity

    Directory of Open Access Journals (Sweden)

    S. Więckowski

    2015-05-01

    Full Text Available A comparative study concerning the effects of chloramphenicol (100 μg ml-1, actidione (10 μg ml-1, 5-bromouracil (190 μg ml-1, actinomycin D (30 μg ml-1 and DL-ethionine (800 μg ml-1 on the chloroplast fine structure, 14CO2 incorporation and the Hill reaction activity was the subject of the experiments presented in this paper. The experiments were conducted on bean seedlings under the conditions when chlorophyll accumulation was inhibited only partially. The results obtained indicate that chloromphenicol is responsible for the reduction of the number of grana per section of plastid and for the formation of numerous vesicles in the stroma. In the presence of actidione, actinomycin D or DL-ethionine the lamellae are poorly differentiated into .stroma and granum regions and there occur disturbances in the typical orientation of lamellae within chloroplasts. Only in the presence of 5-bromouracil the development of chloroplast structure resemble that in control plants. A comparison of the results obtained with those published earlier (Więckowski et al., 1974; Ficek and Więckowski, 1974 shows that such processes as assimilatory pigment accumulation, the rate of CO2 fixation, the Hill reaction activity, and the development of lamellar system are suppressed in a different extent by the inhibitors used.

  14. Attempts to induce mutations in Haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine

    Energy Technology Data Exchange (ETDEWEB)

    Kimball, R.F.; Perdue, S.W.

    1977-01-01

    Attempts were made to induce mutations in Haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine. These attempts were unsuccessful. Incorporation studies with BrdUrd showed, in agreement with earlier studies on Escherichia coli, that BrdUrd was discriminated against when dThd was also present but was incorporated to essentially the same extent as dThd when only BrdUrd was present. In this latter case, strands fully substituted with BrdUrd were produced, but survival data suggest that bacteria deriving their DNA by replication on such fully substituted templates were inviable. However, bacteria with about 20% of the thymine substituted with bromouracil were usually viable. No mutations could be detected in the descendants of such bacteria. The reasons for this are discussed and it is concluded that in all probability the replication system in species rarely if ever treats incorporated bromouracil as anything except a thymine analogue. The alternative possibility, that the negative results are a consequence of the absence of the reclex (SOS) error-prone repair system in this species, is considered much less likely.

  15. Molecular mechanisms induced by the effects of ionizing radiation on nucleic acids: Free radicals in 5-halogenated uracil derivatives after reaction of radiolysis products of water in low-temperature glass

    International Nuclear Information System (INIS)

    This thesis deals with the molecular mechanisms induced by the effects of ionizing radiation on the DNA. The study has been made for the main purpose of clarifying the possible role of the indirect effect, namely the attack of diffusible water radicals, in the process of radiosensitivity enhancement due to the incorporation of bromouracil instead of thymine into the DNA. The results of the experiments can be summarized by the statement that among the reactions studied in the low-temperature glasses, none revealed such a clear difference between uracil and thymine on the one hand, and the halogenated uracils on the other, that this difference could suffice to explain in terms of quality and quantity the observed in-vivo enhancement of radiosensitivity by halogenated uracils. This conclusion is in agreement with the results of radiobiological measurements on phagae and bacteria which in all cases revealed no or only very slight enhancement of the radiosensitivity in the indirect effect subsequent to bromouracil incorporation. (orig./AJ)

  16. Defective repair of gamma-ray-induced DNA damage in xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    The bromouracil-photolysis technique has been used to estimate the sizes of the repaired regions in normal human and xeroderma pigmentosum (XP) cells irradiated by γ-rays aerobically or anoxically. After one and a half hours of incubation, single-strand breaks were repaired and the repaired regions were small - one to two BrUra residues -for cells irradiated aerobically or anoxically. After a 20-hour incubation, the repaired region in normal cells showed a component mimicking U.V.-repair. There were large patches (approximately 30 BrUra residues) in the approximate ratios of one per six chain breaks for aerobic irradiation and one per three chain breaks for anoxic irradiation. XP cells, however, only showed large patches at 20 hours if they had been irradiated aerobically. Such regions could not be detected in XP cells irradiated anoxically. These results indicate (1) that some part of ionizing damage mimics excision of U.V. damage in that the repair patches are large and the repair takes an appreciable time; (2) the types of such damage depend on whether the irradiation is done aerobically or anoxically; and (3) XP cells are defective in repairing a component of anoxic damage. (author)

  17. Effect of mutations in the uthetarD cistron of Escherichia coli on repair resynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kuemmerle, N.B.; Ley, R.D.; Masker, W.E. (Oak Ridge National Lab., TN (USA). Biology Div.)

    1982-01-01

    The resynthesis step of the excision repair pathway has been examined in Escherichia coli K12 strains isogenic except for mutations in the uvrD cistron. Strains mutant at the uvrD3, uvrD101, uvrE156, and recLl52 loci exhibited slight but distinct differences in their response to ultraviolet radiation. The repair capacity of the uvrD101 mutant was given special attention. Repair resynthesis in this mutant was saturated at fluences greater than about 20 J/m/sup 2/. Isopycnic analysis of repaired deoxyribonucleic acid from this strain revealed a two-fold increase over its wild-type counterpart in the amount of repair replication performed after a dose of 15 J/m/sup 2/. Sedimentation velocity analysis of DNA after selective photolysis of bromouracil-containing repaired regions showed that the uvrD101 mutation exerted its primary effect on the long-patch component of excision repair. The uvrD101 mutant performed long-patch repair at a larger number of sites than the number repaired by this mode in the wild-type strain; these patches were more extensive in length than the long-patch component in wild-type.

  18. The effect of mutations in the uthetarD cistron of Escherichia coli on repair resynthesis

    International Nuclear Information System (INIS)

    The resynthesis step of the excision repair pathway has been examined in Escherichia coli K12 strains isogenic except for mutations in the uvrD cistron. Strains mutant at the uvrD3, uvrD101, uvrE156, and recLl52 loci exhibited slight but distinct differences in their response to ultraviolet radiation. The repair capacity of the uvrD101 mutant was given special attention. Repair resynthesis in this mutant was saturated at fluences greater than about 20 J/m2. Isopycnic analysis of repaired deoxyribonucleic acid from this strain revealed a two-fold increase over its wild-type counterpart in the amount of repair replication performed after a dose of 15 J/m2. Sedimentation velocity analysis of DNA after selective photolysis of bromouracil-containing repaired regions showed that the uvrD101 mutation exerted its primary effect on the long-patch component of excision repair. The uvrD101 mutant performed long-patch repair at a larger number of sites than the number repaired by this mode in the wild-type strain; these patches were more extensive in length than the long-patch component in wild-type. (orig.)

  19. Radiation-induced electron migration in nucleic acids

    International Nuclear Information System (INIS)

    Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to non-random types of damage along DNA manifested distal to the sites of the initial energy deposition. Radiation-induced electron migration in nucleic acids has been examined using oligonucleotides containing 5-bromouracil (5-BrU). Interaction of 5-BrU with solvated electrons results in release of bromide ions and formation of uracil-5-yl radicals. Monitoring either bromide ion release or uracil formation provides an opportunity to study electron migration processes in model nucleic acid systems. Using this approach we have discovered that electron migration along oligonucleotides is significantly influenced by the base sequence and strandedness. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution, which compares with mean migration distances of 6-10 bp for Escherichia coli DNA irradiated in solution and 5.5 bp for E. coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5' to 3' direction along a double-stranded oligonucleotide containing a region of purine bases adjacent to the 5-BrU moiety. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation. (Author)

  20. Determination of fluorouracil concentration in tissues by HPLC%高效液相色谱法测定氟尿嘧啶的组织浓度

    Institute of Scientific and Technical Information of China (English)

    余俊先; 蔡军; 史丽敏; 王康里; 罗晓; 温爱萍; 李任; 王汝龙

    2011-01-01

    Objective: An HPLC method was developed to determine the concentration of fluorouracil in tissues, which was a metabolite of capecitabine in tissues. Methods: Plasma contained fluorouracil with bromouracil as the internal standard was extracted with acetoacetate, then the organic layer was evaporated to dryness under nitrogen stream and the residue was reconstituted with mobile phase for HPLC assay. Gastric carcinoma tissues and perienchyma through exairesis were homogenated with blank plasma and dealt with the same as described above. The mobile phase consisted of acetointrile: water (1: 99) at a flow rate of 1.0 mL·min-1, and the detection wavelength was 254 nm. Results: The retention times of fluorouracil and bromouracil were 3.20 minutes and 7.50 minutes, respectively. The assay exhibited excellent linearity with the range of 0.02 - 1.0 μg·mL-1 (r = 0.999 6). The reproducibility, extraction recovery, the variability of intra- and inter- day assay were consistent with requirement for determining biological specimen. Fluorouracil, metabolite of capecitabine, in gastric carcinoma central tissues (1.095 μg·g-1) was significantly higher than that in normal gastric tissues (0.047 μg·g-1). Conclusion: The method is suitable for determining the concentration of fluorouracil in tissues, and applicable to the study of capecitabine metabolism in human.%目的:建立高效液相色谱法测定卡培他滨代谢物氟尿嘧啶的组织浓度.方法:取氟尿嘧啶血浆溶液,加入溴尿嘧啶为内标,经乙酸乙酯提取后氮气吹干,流动相复溶进样分析;手术切除的胃癌及其周边组织用空白血浆匀浆,匀浆液处理方法同上.流动相为乙腈-水(1:99),流速1.0mL·min-1,检测波长254nm.结果:氟尿嘧啶与内标溴尿嘧啶保留时间分别为3.20min和7.50min.氟尿嘧啶的标准曲线范围0.02~1.0μg·mL-1(r=0.9996),方法的重现性、回收率、精密度和稳定性均符合生物样品分析要求.卡培他滨代谢物

  1. Enzymatic synthesis of long double-stranded DNA labeled with haloderivatives of nucleobases in a precisely pre-determined sequence

    Directory of Open Access Journals (Sweden)

    Rak Janusz

    2011-08-01

    Full Text Available Abstract Background Restriction endonucleases are widely applied in recombinant DNA technology. Among them, enzymes of class IIS, which cleave DNA beyond recognition sites, are especially useful. We use BsaI enzyme for the pinpoint introduction of halogen nucleobases into DNA. This has been done for the purpose of anticancer radio- and phototherapy that is our long-term objective. Results An enzymatic method for synthesizing long double-stranded DNA labeled with the halogen derivatives of nucleobases (Hal-NBs with 1-bp accuracy has been put forward and successfully tested on three different DNA fragments containing the 5-bromouracil (5-BrU residue. The protocol assumes enzymatic cleavage of two Polymerase-Chain-Reaction (PCR fragments containing two recognition sequences for the same or different class IIS restriction endonucleases, where each PCR fragment has a partially complementary cleavage site. These sites are introduced using synthetic DNA primers or are naturally present in the sequence used. The cleavage sites are not compatible, and therefore not susceptible to ligation until they are partially filled with a Hal-NB or original nucleobase, resulting in complementary cohesive end formation. Ligation of these fragments ultimately leads to the required Hal-NB-labeled DNA duplex. With this approach, a synthetic, extremely long DNA fragment can be obtained by means of a multiple assembly reaction (n × maximum PCR product length: n × app. 50 kb. Conclusions The long, precisely labeled DNA duplexes obtained behave in very much the same manner as natural DNA and are beyond the range of chemical synthesis. Moreover, the conditions of synthesis closely resemble the natural ones, and all the artifacts accompanying the chemical synthesis of DNA are thus eliminated. The approach proposed seems to be completely general and could be used to label DNA at multiple pre-determined sites and with halogen derivatives of any nucleobase. Access to DNAs

  2. Experimental study of inhibitory effects of tomato extraction on breast cancer growth%番茄提取物抑制乳腺癌生长的实验研究

    Institute of Scientific and Technical Information of China (English)

    马文杰; 康欣梅; 张清媛

    2009-01-01

    目的 探讨番茄提取物在乳腺癌动物模型中对肿瘤增殖、凋亡及血管生成的影响.方法 建立二甲基苯葸诱导的大鼠乳腺癌模型,给予高中低剂量番茄提取物灌胃,应用5-溴-2-脱氧尿嘧啶核苷标记法检测细胞增殖;原位末端标记法检测细胞凋亡;免疫组化法检测肿瘤微血管密度.结论 番茄组乳腺肿瘤的增殖指数和肿瘤微血管密度均低于对照组,且高剂量番茄组中乳腺肿瘤的凋亡指数较对照组升高,差异具有显著性(P<0.05).结论番茄提取物在乳腺癌中具有抗增殖、促凋亡和抗血管生成活性,具有潜在的抗肿瘤应用价值.%Objective To investigate the effects of tomato extraction on tumor proliferation, apoptosis and angiogenesis in breast cancer animal model. Methods DMBA-induced breast caner models in SD rats were set up and received low-dose, middle-dose and high-dose tomato extraction by gavage. Tumor cell proliferation was detected by bromouracil deoxyriboside labeling, cell apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling, and tumor microvascular density was detected by immunohistochemical method. Results The tumor proliferative index and microvascular density were decreased in tomato group compared with control, and the apoptotic index was increased in high-dose tomato group. The difference was statistically significant (P <0. 05). Conclusion The tomato extraction can inhibit tumor proliferation, promote apoptosis and decrease angiogenesis in breast cancer, and it has potential value for application in cancer treatment.