共查询到20条相似文献，搜索用时 31 毫秒
1.
Inhibition of serum- and ras-stimulated DNA synthesis by antibodies to phospholipase C 总被引：17，自引：0，他引：17
Several immunologically distinct isozymes of inositol phospholipid-specific phospholipase C (PLC) have been purified from bovine brain. Murine NIH 3T3 fibroblasts were found to express PLC-gamma, but the expression of PLC-beta was barely detectable by radioimmunoassay or protein immunoblot. A mixture of monoclonal antibodies was identified that neutralizes the biological activity of both endogenous and injected purified PLC-gamma. When co-injected with oncogenic Ras protein or PLC-gamma, this mixture of antibodies inhibited the induction of DNA synthesis that characteristically results from the injection of these proteins into quiescent 3T3 cells. However, when oncogenic Ras protein or PLC-gamma was co-injected with a neutralizing monoclonal antibody to Ras, only the DNA synthesis induced by the Ras protein was inhibited--that induced by PLC was unaffected. These results suggest that the Ras protein is an upstream effector of PLC activity in phosphoinositide-specific signal transduction and that PLC-gamma activity is necessary for Ras-mediated induction of DNA synthesis. 相似文献
2.
5-Methylcytosine in eukaryotic DNA 总被引：125，自引：0，他引：125
3.
Malignant transformation of erythroid cells in vivo by introduction of a nonreplicating retrovirus vector 总被引：26，自引：0，他引：26
DNA from a replication-defective spleen focus-forming virus (SFFV) was reconstructed and transfected into psi-2 cells containing a packaging-defective mutant of Moloney murine leukemia virus. Replication-incompetent retrovirus particles (helper virus-free containing genomes that express the transforming envelope gene of SFFV (gp52) transformed bone marrow cells in vitro and, after direct intravenous introduction of the vector, induced malignant erythroid disease in vivo. Disease induction was dependent on prior treatment of mice with phenylhydrazine, which probably increased the availability of erythroid target cells. Since there was no evidence of virus particle expression in mice with malignant disease, this study demonstrates the acute oncogenic potential of a limited number of erythroid cells expressing SFFV gp52. Direct inoculation of animals with nonreplicating retroviral vectors containing transforming genes may be useful in study the oncogenic effects of such genes. 相似文献
4.
Three distinct genes in human DNA related to the transforming genes of mammalian sarcoma retroviruses 总被引：9，自引：0，他引：9
F Wong-Staal R Dalla-Favera G Franchini E P Gelmann R C Gallo 《Science (New York, N.Y.)》1981,213(4504):226-228
Southern blot hybridization was used to identify human and other vertebrate DNA sequences that were homologous to cloned DNA fragments containing the oncogenic nucleic acid sequences of three different type C mammalian retroviruses (simian sarcoma virus, the Snyder-Theilen strain of feline sarcoma virus, and the Harvey strain of murine sarcoma virus). Each onc gene counterpart has a single genetic locus, which probably contains non-onc intervening sequences. The human DNA sequences may represent genes important to cell growth or cell differentiation, or both. Their identification and isolation may allow elucidation of their role in these processes and in neoplasias. 相似文献
5.
Dorsal, an embryonic polarity gene in Drosophila, is homologous to the vertebrate proto-oncogene, c-rel 总被引：72，自引：0，他引：72
R Steward 《Science (New York, N.Y.)》1987,238(4827):692-694
The Drosophila gene, dorsal, is a maternal effect locus that is essential for the establishment of dorsal-ventral polarity in the developing embryo. The dorsal protein was predicted from the complementary DNA sequence; it is almost 50 percent identical, over an extensive region, to the protein encoded by the avian oncogene v-rel, its cellular homolog, c-rel, and a human c-rel fragment. The oncogene v-rel is highly oncogenic in avian lymphoid, spleen, and bone marrow cells. 相似文献
6.
基于DNA双链电荷转移原理,利用胸腺嘧啶(thymine)与Hg2的特异性识别和计时电量法构建了一种高灵敏检测水溶液中Hg2的电化学生物传感器.该传感器将含有1个T-T碱基错配对的DNA互补双链通过Au-S键自组装在金电极表面,运用计时电量法在含有亚甲基蓝的铁氰化钾溶液中进行测定.T-T错配阻断了DNA双链内部电荷转移,而Hg2通过T-Hg2-T配位作用与双链DNA特异性结合并形成DNA双链内部电荷转移通路,引起电极表面计时电量的变化.计时电量测定结果显示:在亚甲基蓝的还原峰电位(-380mV)附近,计时电量随着溶液中的Hg2+浓度的增大而增加,Hg2+浓度在1.0 nmol/L～ 104 nmol/L范围内,计时电量的变化量与Hg2浓度的对数呈良好的线性关系,线性相关系数(R2)为0.997,检测限为0.5 nmol/L(S/N=3).干扰实验表明,该传感器对Hg2具有良好的特异性和选择性. 相似文献
7.
Viral neoplastic transformation of hamster pineal cells in vitro: retention of enzymatic function 总被引：2，自引：0，他引：2
Cultures of hamster pineal tissue infected with certain oncogenic DNA viruses undergo neoplastic transformation and produce tumors when injected into homologous hosts. Hydroxyindole-O-methyl transferase, an enzyme found exclusively in the pineal gland, is present in low concentrations in transformed pineal cells in vitro and in larger amounts in tumors produced by the injected cells. This enzyme is not present in several nonpineal tissues similarly transformed. 相似文献
8.
Chen HT Bhandoola A Difilippantonio MJ Zhu J Brown MJ Tai X Rogakou EP Brotz TM Bonner WM Ried T Nussenzweig A 《Science (New York, N.Y.)》2000,290(5498):1962-1965
Genetic disorders affecting cellular responses to DNA damage are characterized by high rates of translocations involving antigen receptor loci and increased susceptibility to lymphoid malignancies. We report that the Nijmegen breakage syndrome protein (NBS1) and histone gamma-H2AX, which associate with irradiation-induced DNA double-strand breaks (DSBs), are also found at sites of VDJ (variable, diversity, joining) recombination-induced DSBs. In developing thymocytes, NBS1 and gamma-H2AX form nuclear foci that colocalize with the T cell receptor alpha locus in response to recombination activating gene (RAG) protein-mediated VDJ cleavage. Our results suggest that surveillance of T cell receptor recombination intermediates by NBS1 and gamma-H2AX may be important for preventing oncogenic translocations. 相似文献
9.
Reverse transcriptases of primate viruses as immunological markers 总被引：20，自引：0，他引：20
10.
erbB-2 is a potent oncogene when overexpressed in NIH/3T3 cells 总被引：94，自引：0，他引：94
P P Di Fiore J H Pierce M H Kraus O Segatto C R King S A Aaronson 《Science (New York, N.Y.)》1987,237(4811):178-182
A wide variety of human tumors contain an amplified or overexpressed erbB-2 gene, which encodes a growth factor receptor-like protein. When erbB-2 complementary DNA was expressed in NIH/3T3 cells under the control of the SV40 promoter, the gene lacked transforming activity despite expression of detectable levels of the erbB-2 protein. A further five- to tenfold increase in its expression under influence of the long terminal repeat of Moloney murine leukemia virus was associated with activation of erbB-2 as a potent oncogene. The high levels of the erbB-2 product associated with malignant transformation of NIH/3T3 cells were observed in human mammary tumor cells that overexpressed this gene. These findings demonstrate a new mechanism for acquisition of oncogenic properties by genes encoding growth factor receptor-like proteins and provide a functional basis for the role of their overexpression in the development of human malignancies. 相似文献
11.
12.
Miled N Yan Y Hon WC Perisic O Zvelebil M Inbar Y Schneidman-Duhovny D Wolfson HJ Backer JM Williams RL 《Science (New York, N.Y.)》2007,317(5835):239-242
Many human cancers involve up-regulation of the phosphoinositide 3-kinase PI3Kalpha, with oncogenic mutations identified in both the p110alpha catalytic and the p85alpha regulatory subunits. We used crystallographic and biochemical approaches to gain insight into activating mutations in two noncatalytic p110alpha domains-the adaptor-binding and the helical domains. A structure of the adaptor-binding domain of p110alpha in a complex with the p85alpha inter-Src homology 2 (inter-SH2) domain shows that oncogenic mutations in the adaptor-binding domain are not at the inter-SH2 interface but in a polar surface patch that is a plausible docking site for other domains in the holo p110/p85 complex. We also examined helical domain mutations and found that the Glu545 to Lys545 (E545K) oncogenic mutant disrupts an inhibitory charge-charge interaction with the p85 N-terminal SH2 domain. These studies extend our understanding of the architecture of PI3Ks and provide insight into how two classes of mutations that cause a gain in function can lead to cancer. 相似文献
13.
Conway JF Wikoff WR Cheng N Duda RL Hendrix RW Johnson JE Steven AC 《Science (New York, N.Y.)》2001,292(5517):744-748
Large-scale conformational changes transform viral precursors into infectious virions. The structure of bacteriophage HK97 capsid, Head-II, was recently solved by crystallography, revealing a catenated cross-linked topology. We have visualized its precursor, Prohead-II, by cryoelectron microscopy and modeled the conformational change by appropriately adapting Head-II. Rigid-body rotations ( approximately 40 degrees) cause switching to an entirely different set of interactions; in addition, two motifs undergo refolding. These changes stabilize the capsid by increasing the surface area buried at interfaces and bringing the cross-link-forming residues, initially approximately 40 angstroms apart, close together. The inner surface of Prohead-II is negatively charged, suggesting that the transition is triggered electrostatically by DNA packaging. 相似文献
14.
Induction of membrane ruffling and fluid-phase pinocytosis in quiescent fibroblasts by ras proteins 总被引：69，自引：0，他引：69
Expression of the ras oncogene is thought to be one of the contributing events in the initiation of certain types of human cancer. To determine the cellular activities that are directly triggered by ras proteins, the early consequences of microinjection of the human H-ras proteins into quiescent rat embryo fibroblasts were investigated. Within 30 minutes to 1 hour after injection, cells show a marked increase in surface ruffles and fluid-phase pinocytosis. The rapid enhancement of membrane ruffling and pinocytosis is induced by both the proto-oncogenic and the oncogenic forms of the H-ras protein. The effects produced by the oncogenic protein persist for more than 15 hours after injection, whereas the effects of the proto-oncogenic protein are short-lived, being restricted to a 3-hour interval after injection. The stimulatory effect of the ras oncogene protein on ruffling and pinocytosis is dependent on the amount of injected protein and is accompanied by an apparent stimulation of phospholipase A2 activity. These rapid changes in cell membrane activities induced by ras proteins may represent primary events in the mechanism of action of ras proteins. 相似文献
15.
红景天种内遗传多样性分析AFLP方法建立 总被引：4，自引：0，他引：4
研究建立一种用于药用植物红景天种内遗传多样性分析的AFLP分子标记方法.以提取红景天(Rhodiola.rosea L)种基因组DNA为模板,25 μL酶切体系中采用两步双酶切(Mse I、EcoR I),在20 μL连接体系中采用T4连接酶,22℃连接过夜,50 μL体系预扩增,Taq Plus酶2.5 U,dNTP 160 μM,对应引物0.5 μM,10×PCR Buffer(含Mg2+) 4.5 μL,25 μL体系选择性扩增,Taq Plus酶1.5 U,dNTP 80 μM,对应引物 0.25 μM,10×PCR Buffer(含Mg2+) 2.5 μL.AFLP分子标记技术是一种快速、准确、稳定的药用植物红景天的种内遗传多样性分析手段. 相似文献
16.
Modi BG Neustadter J Binda E Lewis J Filler RB Roberts SJ Kwong BY Reddy S Overton JD Galan A Tigelaar R Cai L Fu P Shlomchik M Kaplan DH Hayday A Girardi M 《Science (New York, N.Y.)》2012,335(6064):104-108
Polyaromatic hydrocarbons (PAHs) are prevalent, potent carcinogens, and 7,12-dimethylbenz[a]anthracene (DMBA) is a model PAH widely used to study tumorigenesis. Mice lacking Langerhans cells (LCs), a signatory epidermal dendritic cell (DC), are protected from cutaneous chemical carcinogenesis, independent of T cell immunity. Investigation of the underlying mechanism revealed that LC-deficient skin was relatively resistant to DMBA-induced DNA damage. LCs efficiently metabolized DMBA to DMBA-trans-3,4-diol, an intermediate proximal to oncogenic Hras mutation, and DMBA-treated LC-deficient skin contained significantly fewer Hras mutations. Moreover, DMBA-trans-3,4-diol application bypassed tumor resistance in LC-deficient mice. Additionally, the genotoxic impact of DMBA on human keratinocytes was significantly increased by prior incubation with human-derived LC. Thus, tissue-associated DC can enhance chemical carcinogenesis via PAH metabolism, highlighting the complex relation between immune cells and carcinogenesis. 相似文献
17.
Rates of DNA sequence evolution differ between taxonomic groups 总被引：63，自引：0，他引：63
R J Britten 《Science (New York, N.Y.)》1986,231(4744):1393-1398
The mutation rates of DNA sequences during evolution can be estimated from interspecies DNA sequence differences by assaying changes that have little or no effect on the phenotype (neutral mutations). Examination of available measurements shows that rates of DNA change of different phylogenetic groups differ by a factor of 5. The slowest rates are observed for higher primates and some bird lineages, while faster rates are seen in rodents, sea urchins, and drosophila. The rate of DNA sequence change has decreased markedly during primate evolution. The contrast in rates of DNA sequence change is probably due to evolutionary variation and selection of biochemical mechanisms such as DNA replication or repair. 相似文献
18.
光周期诱导菊花成花及成花逆转过程中生理代谢的变化 总被引：4，自引：0，他引：4
本试验以切花菊品种神马为试材,研究了不同光周期处理过程中菊花叶片可溶性总糖、蔗糖、可溶性蛋白、RNA和DNA等含量的变化。结果表明,长日照处理的菊花未形成花芽,始终保持营养生长,其叶片可溶性总糖、蔗糖、可溶性蛋白、RNA和DNA含量没有明显变化,一直保持较稳定水平。短日照处理的菊花叶片可溶性总糖和蔗糖比长日照处理减少,可溶性蛋白质、RNA和DNA含量都比长日照处理增加。先短日照后长日照处理的菊花在短日照期间形成的花芽在转入长日照时花芽停止发育和膨大,最终未开花,其叶片可溶性总糖含量比长日照处理减少,处理第15d以后比短日照处理增加,而蔗糖、可溶性蛋白、DNA和RNA含量比其它处理明显增加。 相似文献
19.
A genetic screen was designed in Drosophila to interrogate its genome for mutations sufficient to cause noninvasive tumors of the eye disc to invade neighboring or distant tissues. We found that cooperation between oncogenic RasV12 expression and inactivation of any one of a number of genes affecting cell polarity leads to metastatic behavior, including basement membrane degradation, loss of E-cadherin expression, migration, invasion, and secondary tumor formation. Inactivation of these cell polarity genes cannot drive metastatic behavior alone or in combination with other tumor-initiating alterations. These findings suggest that the oncogenic background of tissues makes a distinct contribution toward metastatic development. 相似文献
20.
Helical repeat and linking number of surface-wrapped DNA 总被引：6，自引：0，他引：6
The geometric properties of duplex DNA are systematically altered when the DNA is wrapped on a protein surface. The linking number of surface-wrapped closed circular DNA is the sum of two integers: the winding number, phi, a function of the helical repeat; and the surface linking number, SLk, a newly defined geometric constant that accounts for the effects of surface geometry on the twist and writhe of DNA. Changes in the helical repeat, h, and in the winding number can be deduced solely from surface geometry and superhelix density, sigma. This treatment relates the theoretically important properties twist and writhe to the more experimentally accessible quantities phi, h, SLk, and sigma. The analysis is applied to three biologically important cases: interwinding of DNA in a plectonemic superhelix, catenated DNA, and minichromosomes. 相似文献