共查询到20条相似文献,搜索用时 31 毫秒
1.
W.A. Deutsch A.L. Spiering G.R. Newkome 《Biochemical and biophysical research communications》1980,97(3):1220-1226
The -isomer of the antitumor drug dichlorodiammineplatinum(II) [-Pt(II)] was tested for its abilty to introduce nicks (single-strand breaks) into supercoiled PM2 DNA. Whereas incubations up to 24 h show no indication of -Pt(II)-treated DNA having single-strand breaks, DNA interstrand cross-links were detected in the first 15 min of incubation. Furthermore, the formation of DNA interstrand cross-links was inhibited and fully reversed after incubation with 2 mM thiourea. 相似文献
2.
Robert Carey Johnson 《Biochemical and biophysical research communications》1976,70(3):791-796
Gaps in daughter-strand deoxyribonucleic acid (DNA) synthesized after exposure of wild-type to ultraviolet light are filled during reincubation. In this study the , and gene products have been examined for their role in postreplication repair. These gene products are unique in their specific control of certain types of DNA synthesis: initiation of rounds of replication and chain propagation. Initiation of rounds of replication is not essential to gap filling; however, chain propagation by short DNA piece initiation appears to be essential for gap filling. 相似文献
3.
David Scicchitano Anthony E. Pegg 《Biochemical and biophysical research communications》1982,109(3):995-1001
The demethylation of O6-methylguanine in double stranded DNA catalyzed by rat liver O6-methylguanine-DNA transmethylase was found to proceed much more rapidly when the DNA substrate was methylated to a high extent. When the content of O6-methylguanine in DNA was equal to 1 in 2000 guanines, the reaction was 90% complete within 2 min, but when the content was 1 in 500,000 it required 27 min at 37°C. These results suggest that the repair protein either moves along the DNA substrate or else has little selectivity for binding specifically to the sites containing O6-methylguanine rather than to the normal DNA. The repair of O6-methylguanine in rat liver occurred at rates comparable to those seen with the substrates alkylated to low extents and was virtually complete within 3 hours. These results provide strong evidence that this protein is the factor responsible for O6-methylguanine removal and explain the wide variation in time courses reported in the literature since substrates methylated to greatly different extents have been used for such experiments. 相似文献
4.
W. Wackernagel 《Biochemical and biophysical research communications》1973,51(2):306-311
Genetic transformation of for various chromosomal markers was accomplished by (i) using recipient cells that lack the DNase but were recombination proficient due to or mutations and (ii) treating the recipient cells with CaCl2 at a concentration that facilitates transfection by λ DNA. Cotransformation of three markers () was found to depend on the molecular weight of the transforming DNA. 相似文献
5.
Werner Goebel 《Biochemical and biophysical research communications》1973,51(4):1000-1007
The dependence of the replication of several plasmids on the chromosome-determined initiation products, A and C, has been studied. The initiation of the replication of E1 DNA requires the chromosomal A product. In contrast two de-repressed transfer factors ( and 152) seem to determine a corresponding plasmid-specific factor. The C-product is necessary for the ordered initation of all plasmids studied. The addition of low concentrations of chloramphenicol leads to a relaxed replication of E1 DNA at the restrictive temperature in A-mutants, but not in C-mutants. 相似文献
6.
Evelyn A. Devine Mary C. Moran Peter J. Jederlinic Anthony J. Mazaitis Henry J. Vogel 《Biochemical and biophysical research communications》1975,67(4):1589-1593
The transducing phage λd, carrying a portion of the chromosome including , is derived from the heat-inducible, lysis-defective strain λy199, which has the and deletions. Cleavage of λy199 DNA by RI endonuclease, followed by agarose slab gel electrophoresis, results in bands corresponding to the known C, D, E, and F segments of λ, and a segment A′ (A plus B minus minus , the cleavage site between A and B being eliminated). Cleavage of λd DNA by RI yields the expected D, E, and F segments of λ and four other segments, termed 14-1 through 14-4, whose length is 17.5, 6.2, 3.0, and 2.0 kilobases, respectively, as determined by electron microscopy and corroborated by electrophoretic mobility. Heteroduplex analysis shows that the cluster is on the 14-1 segment. 相似文献
7.
J.A. Pérez-González A. Jiménez 《Biochemical and biophysical research communications》1984,125(3):895-901
The paromomycin producing organism is resistant to this antibiotic and contains a phosphotransferase which inactivates paromomycin. The gene encoding this enzyme has been inserted in the vector pIJ702 and then cloned in , selecting for paromomycin-resistance. Three plasmids have been isolated and one of them, pMJ1, contains a 2.2 kb insert with a single HindIII restriction site. Insertion of foreign DNA in this site blocks the expression of the phosphotransferase enzyme indicating that it is within the cloned gene. These findings provide a new dominant selective marker for cloning vectors with the versatility of insertional inactivation. 相似文献
8.
Anthony E. Pegg 《Biochemical and biophysical research communications》1978,84(1):166-173
Extracts from various rat tissues were incubated with [3H]methylated DNA or chromatin in order to compare their abilities to catalyze the removal of labeled -methylguanine from acid precipitable DNA. Liver extracts had the greatest activity. Kidney extracts had about 35% of the activity in liver and extracts from lung, colon, small intestine and brain were much less active. The enzyme responsible for this reaction does not appear to be an -glycosidase because no labeled -methylguanine could be detected in the supernatant fraction even though more than 50% of this base was lost from the DNA. The released radioactivity was present as methanol which is consistent with the possibility that the reaction may involve a demethylase action on either the DNA substrate or an oligonucleotide derived from it. 相似文献
9.
George Boguslawski William S. Oetting Dean A. Stetler 《Biochemical and biophysical research communications》1977,78(2):684-689
An enzyme, ribonucleotide polymerase, isolated from the yeast phase of a fungus, has been found to stimulate the incorporation of dTMP in the reaction catalysed by DNA polymerase from and . The stimulation is dependent on the amount of ribonucleotide polymerase added. The data indicate that protein-protein interaction is responsible for the increase in DNA synthesis. It is suggested that ribonucleotide polymerase may be involved in supplying short RNA primers for DNA polymerase. 相似文献
10.
The average DNA content per cell was measured in steady-state cultures of two substrains of growing at various rates at 37°C. The DNA content of substrain F was consistently lower than that of substrain A. It is suggested that the differences in DNA contents are consequences of strain-specific differences in the relationship between chromosome replication and the division cycle of 相似文献
11.
William G. Haldenwang James R. Walker 《Biochemical and biophysical research communications》1976,70(3):932-938
A functional product, known to be essential for host DNA polymerization and for the growth of coliphages ?X174 and M13, is required for the single strand to replicative form conversions of both of these phages. 相似文献
12.
Frederick Chu Paul Caldwell Mark Samuels Herbert Weissbach Nathan Brot 《Biochemical and biophysical research communications》1977,76(2):593-601
The synthesis of ribosomal protein L10 has been demonstrated using λrifd18 DNA as template. The L10 synthesized forms a complex with ribosomal protein L12 and the L10 in this complex can be immunoprecipitated with L12 antiserum. 相似文献
13.
James B. Johnston I.C. Gunsalus 《Biochemical and biophysical research communications》1977,75(1):13-19
Metabolic plasmids conferring on the aromatic growth phenotypes naphthalene, Nah+, salicylate, Sal+, or toluate, Tol+, have been isolated as covalently closed circular DNA in 100 μg amounts. Plasmid DNA was banded in CsCl-ethidium bromide density gradients and sedimentation rates measured in sucrose gradients and by analytical centrifuge. The plasmid sizes found, in millions, were /NAH 42, /SAL 43, /TOL 55, 42. Transformation of metabolic plasmid free with the isolated DNA confirmed the respective aromatic pathway gene contents. 相似文献
14.
F. Malpartida M. Zalacaín A. Jiménez J. Davies 《Biochemical and biophysical research communications》1983,117(1):6-12
The gene encoding the phosphotransferase enzyme that modifies hygromycin B in its producing organism , has been cloned in the vector pIJ41. Two plasmids, pFM4 and pFM6, containing 2.1 and 19.6 kb inserts of DNA, respectively, which express the modifying enzyme, have been isolated. A 3.1 kb PstI restriction fragment from pFM4 was inserted in the vector pIJ350 and the resulting plasmids, pMZ11.1 and pMZ11.2, express the hygromycin B-resistance phenotype. The utility of this dominant marker for cloning experiments is discussed in the text. 相似文献
15.
16.
We developed a new method for detecting DNA/RNA hybrids formed using antibodies and the Peroxidase-antiperoxidase immunohistochemical procedure. Using RNA synthesised from cloned histone genes (pDm 500H), we localized by this procedure, the histone genes to the 39 D-E region of the left arm of the second chromosome. This method has several advantages compared to conventional procedures. 相似文献
17.
Stuart L. Marcus Gregg Lipschik Generosa Trueba Cyrus J. Bacchi 《Biochemical and biophysical research communications》1980,93(4):1027-1035
A single peak of DNA polymerase activity from extracts of , obtained by DEAE-cellulose and phosphocellulose ion-exchange chromatography, was resolved into two peaks differing in KCl concentration necessary to elute them from a DNA-agarose column. Peak I (eluting at 0.2 M KCl) and Peak II (eluting at 0.4 M KCl), differed in response to increasing KCl concentrations, although both functioned optimally with Mg2+ as divalent cation when DNA synthesis was directed either by activated DNA or poly (dC)·(dG)12–18. Due to the potential significance of polyamines in the metabolism of , the effect of exogenous polyamine on rates of DNA synthesis by the peak I and II enzymes was compared with that of murine DNA polymerase alpha. Only the peak I enzyme was significantly stimulated (up to 4-fold) by the biologically active polyamines spermine and spermidine at physiological concentrations. The response of the peak I enzyme resembled that of the alpha polymerase. This result suggests a possible functional difference between peak I and II enzymes, as well as a potential target site for trypanocidal drug development. 相似文献
18.
Giorgio Mastromei Silvano Riva 《Biochemical and biophysical research communications》1975,63(2):522-528
In a Thy? strain, thymidine is rapidly converted into thymine and, at the steady state, the pool size of thymidine is very small as compared to that of thymine. Consequently when such strain is used for pulse incorporation experiments with labelled thymidine paradoxical results are obtained. A quantitative estimation of the rate of DNA synthesis can only be obtained by thymine pulses or by cumulative incorporation experiments. We also pr sent evidence that, during a short pulse, thymidine is mainly utilized for replicative DNA synthesis. 相似文献
19.
A new restriction-like endonuclease, SlaI, was found and partially purified from Streptomyces lavendulae ATCC8664. This endonuclease cleaved bacteriophage lambda DNA at only one site, and cytosine-substituted bacteriophage T4 DNA at 16 sites. The recognition sequence was determined by using SlaI fragments of cytosine-substituted bacteriophage T4 DNA. The hexanucleotide recognized by SlaI endonuclease was with the sites of cleavage as indicated by the arrows. Therefore, SlaI endonuclease was an isochizomer of XhoI endonuclease. 相似文献
20.
The 1.672 g/cm3 satellite DNA of Drosophila melanogaster was purified by successive equilibrium centrifugations in a CsCl gradient, an actinomycin gradient, and a netropsin sulfate/CsCl gradient. The resulting DNA was homogeneous by the physical criteria of thermal denaturation, renaturation kinetics and equilibrium banding in each of the gradients listed above. In addition, the complementary strands could be separated in an alkaline CsCl gradient. Despite this rigorous purification procedure, nucleotide sequence analysis indicates the presence of two different DNA species in this satellite, poly and poly. Further physical, chemical and template properties of the isolated complementary strands demonstrate that these two repeating sequences are not interspersed with each other. This result has biological significance since sequences of this particular satellite are known to be located primarily on two different chromosomes, Y and 2. These results further suggest that the sequence heterogeneity observed in satellite DNA of higher eukaryotes may result from mixtures of very closely related but molecularly homogeneous repeated sequences each restricted to a particular chromosome or chromosomal region. 相似文献