Showing papers on "Nuclear DNA published in 1969"
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TL;DR: Radioactive RNA introduced into “target” cells can be induced to form hybrids with nuclear DNA and the location of these hybrids can be detected by autoradiography.
Abstract: Radioactive RNA introduced into “target” cells can be induced to form hybrids with nuclear DNA. The location of these hybrids can be detected by autoradiography.
619 citations
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TL;DR: The apparent turnovers of mitochondrial DNA and of the phospholipids, cardiolipin, lecithin, and phosphatidyl ethanolamine, have been determined simultaneously in the mitochondria of rat liver, kidney, brain, and heart.
354 citations
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TL;DR: The DNA-intercalating dyes ethidium bromide and acriflavin strongly inhibit the enzymatic synthesis of DNA catalyzed by rat liver mitochondrial DNA polymerase, and the mitochondrial enzyme is much more sensitive to these dyes.
146 citations
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TL;DR: Nuclear satellite DNA of high specific activity labelled with [ 3 H- methyl ]- l -methionine and 32 P was isolated from newborn mice and from cultured mouse embryo cells and found to have more than twice the molar concentration of 5-methylcytosine than the main band of nuclear DNA.
97 citations
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TL;DR: The intracellular migration of polymerase from the cytoplasm to the nucleus is suggested as a mechanism to account for early development results in sea urchin embryos.
86 citations
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TL;DR: From the discrepancy between analytical and kinetic complexity it is concluded that chloroplastal DNA is extensively reiterated.
Abstract: 1. Chloroplasts and mitochondria were isolated by aqueous and non-aqueous cell-fractionation techniques. In a variety of higher plants the mitochondrial DNA bands in a caesium chloride gradient at 1.706g.cm.(-3), whereas chloroplastal DNA has a buoyant density of 1.697g.cm.(-3). 2. In total cellular DNA of moderate molecular weight, the chloroplastal DNA is found within the Gaussian distribution of the nuclear DNA and is not resolved as a satellite. 3. Both chloroplastal DNA and mitochondrial DNA from lettuce renature rapidly. 4. The kinetic complexity of mitochondrial DNA is > 10(8) daltons. 5. Chloroplastal DNA is made up from fast and slow renaturing sequences with kinetic complexities of 3x10(6) and 1.2x10(8) daltons respectively. 6. From the discrepancy between analytical and kinetic complexity it is concluded that chloroplastal DNA is extensively reiterated.
80 citations
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TL;DR: Observations indicated that both satellite DNA's were relatively homogeneous molecular species and that they had either a different association with cellular structures or a different size than the majority of chromosomal DNA's.
79 citations
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TL;DR: The molecular topology and proportions of the DNA forms isolated from mitochondria of mouse fibroblasts (L-cells) were studied after removal of contaminating nuclear DNA by DNase, and the closed circular DNA component of L-cell mitochondria (DNA I) was isolated and studied with respect to the number of tertiary turns and its resistance to denaturation by alkali and heat.
79 citations
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TL;DR: It is concluded that egg cytoplasm contains an enzyme system capable of replicating native DNA of vertebrate but not of bacterial origin, and that the components of egg or sperm nuclei other than their DNA are not essential for the initiation of the nuclear DNA synthesis that normally follows fertilization.
78 citations
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TL;DR: No major differences were found between completely derepressed cells grown aerobically on galactose up to the stationary phase and cells grown on high glucose under strict anaerobiosis or cells growing under strong aerobic glucose repression.
Abstract: The relative proportions of mitochondrial and nuclear DNA were compared between various types of cells including anaerobically grown cells, aerobically grown glucose-repressed and highly derepressed cells. The comparison was made by the use of a labelled reference yeast, which was mixed with various types of cells before extraction of DNA, so that the results could not be influenced by any unequal losses of DNA components during extraction.
Relative proportions of mitochondrial DNA and nuclear DNA were estimated from the specific radioactivities of the two DNA components which were separated by column chromatography on hydroxyapatite.
Contrary to the previous observation by other authors, no major differences were found between completely derepressed cells grown aerobically on galactose up to the stationary phase and cells grown on high glucose under strict anaerobiosis or cells growing under strong aerobic glucose repression.
By the same technique, the mitochondrial DNA content of some other strains including a δ– mutant was examined.
74 citations
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TL;DR: It is concluded that sea urchin embryo DNA polymerase, an enzyme preferentially primed by native DNA, is strongly associated with nuclei at the stage of hatching, a period of rapid DNA synthesis.
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TL;DR: It is estimated that 10 to 35% of the mitochondrial DNA replicates during oxygen adaptation, and a respiratory-deficient mutant showed a similar response to oxygen and glucose with respect to DNA synthesis although oxidative enzyme activity was absent.
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TL;DR: The chromosomal polymerase manifested variations in enzymic activity when templated with DNA's from different sources and showed the greatest activity in the presence of homologous rat liver nuclear DNA.
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TL;DR: It is concluded that although DNA has been found to be associated with microsomes and may be an integral component of the latter, alternate explanations based upon contamination by nuclear or mitochondrial DNA, or both, could also account for the recovery of DNA in the microsomal fraction.
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TL;DR: The result suggests that replication of mitochondrial DNA is by a semiconservative mechanism and that there is little, if any, repair of the DNA.
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TL;DR: Kinetoplastic DNA was fractionated and separated from nuclear DNA by ultracentrifugation in a CS2SO4 gradient after complexation by mercury or silver ions.
Abstract: SYNOPSIS. Data concerning the DNA and RNA content of 3 Trypanosoma species (T. equiperdum, T. gambiense and T. cruzi) are given. Kinetoplastic DNA was fractionated and separated from nuclear DNA by ultracentrifugation in a CS2SO4 gradient after complexation by mercury or silver ions. Buoyant densities in the analytic ultracentrifuge, base composition and melting point of these DNA's were studied.
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TL;DR: The results indicate that cytoplasmic DNA polymerase activity appears when oocytes are converted into eggs during the completion of meiosis and that this may be partly responsible for the induction of nuclear DNA synthesis which follows fertilization.
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TL;DR: Measurements of nuclear DNA content with quantitative cytochemical methods for determining amounts in single nuclei reveal tetraploid quantities of DNA in cerebellar Purkinje neurons of the rat, or twice the amount of rat somatic cells in general.
Abstract: — Measurements of nuclear DNA content with quantitative cytochemical methods for determining amounts in single nuclei reveal tetraploid quantities of DNA in cerebellar Purkinje neurons of the rat, or twice the amount of nuclear DNA of rat somatic cells in general. The findings suggest that tetraploidy is probably a universal phenomenon among rat Purkinje cells. Granule and basket cells have a diploid DNA content.
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TL;DR: DNA metabolism in the slime mold Physarum polycephalum was studied by centrifugation in CsCl of lysates of cultures labeled with radioactive thymidine at various times in the cell cycle to show that the heavy and the principal DNA components are located in the nucleus and that the light DNA is in the cytoplasm.
Abstract: DNA metabolism in the slime mold Physarum polycephalum was studied by centrifugation in CsCl of lysates of cultures labeled with radioactive thymidine at various times in the cell cycle. During the G2 (premitotic) phase of the cell cycle, two components of the DNA are labeled. One component is lighter (buoyant density 1.686 g/cc) than the mean of the principal DNA (1.700 g/cc), and one is heavier (approximately 1.706 g/cc). The labeled light DNA was identified chemically by its denaturability, its susceptibility to DNase, and the recovery of its radioactivity in thymine. Cell fractionation studies showed that the heavy and the principal DNA components are located in the nucleus and that the light DNA is in the cytoplasm. The light DNA comprises approximately 10% of the DNA. About ⅓–½ of the light DNA is synthesized during the S period, and the remainder is synthesized throughout G2 (there is no G1 in Physarum). The light DNA is metabolically stable. A low, variable level of incorporation of radioactive thymidine into the principal, nuclear DNA component was observed during G2.
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TL;DR: Deoxyribonucleic acid has been isolated from the microsomes of mouse liver homogenates under conditions designed to prevent or greatly reduce mitochondrial and nuclear contamination, and shows that it is not mitochondrial or typically nuclear DNA.
Abstract: Deoxyribonucleic acid has been isolated from the microsomes of mouse liver homogenates under conditions designed to prevent or greatly reduce mitochondrial and nuclear contamination. The DNA rapidly incorporates tritiated thymidine, and this, together with its reannealing characteristics after thermal denaturation, shows that it is not mitochondrial or typically nuclear DNA.
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TL;DR: A study of physical behaviour, in particular buoyant density and melting temperature, can yield useful information on base composition in mitochondria of a genetic apparatus, which is at least partially autonomous.
Abstract: THE presence in mitochondria of a genetic apparatus, which is at least partially autonomous, has greatly stimulated interest in the characterization of mitochondrial DNA from various organisms. A study of physical behaviour, in particular buoyant density and melting temperature, can yield useful information on base composition. Related species of mammals, birds, reptiles and plants have mitochondrial DNAs of similar densities1. This is also true for lower organisms—for example, fungi2—although not for the two related flagellates Tetrahymena and Paramecium1. The density of mitochondrial DNA may be higher (birds and plants), similar (mammals and reptiles) or lower (most unicellular organisms) than that of the corresponding nuclear DNA (ref. 1).
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TL;DR: The drug-induced defect appears to involve the DNA itself rather than the availability of precursors or their polymerization on a suitable template in animals rendered incapable of replicating their nuclear DNA by drug treatment.
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TL;DR: Intraperitoneal injections of low Zn 2+ concentrations have been found to stimulate the incorporation rate of [ 3 H]thymidine into nuclear liver DNA of zinc deficient rats, which appears to be significant since the same Zn2+ concentrations were ineffective on the DNA biosynthesis of rats restricted to a normal Zn 1+ providing stock diet.
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TL;DR: The results support the idea that the cytoplasmic hereditary factor, ϱ, resides in mitochondrial DNA and that the ϱ- mutations studied correspond to a dispersed sequence modification covering about a half of the total mitochondrial DNA genome, leaving the other half unchanged.
Abstract: In some respiratory deficient cytoplasmic mutants, the buoyant density of mitochondrial DNA is changed to detectable degrees, as compared to that of wild type strain: since this density shift suggests an important modification of polynucleotide sequence in mitochondrial DNA, we examined sequence homology between mitochondrial DNA of the respiratory mutants issued from cytoplasmic or chromosomal mutations. Mitochondrial DNA, nuclear DNA and total RNA were extracted from ϱ+ cells (wild type, respiratory sufficient) and from ϱ- cells (cytoplasmic “petite colonie” mutant, respiratory deficient), and molecular hybridization experiments were carried out between them. When ϱ+ RNA × ϱ+ mitochondrial DNA, formed roughly twice as much hybrids as the heterologous cross, ϱ+ RNA × ϱ1 mitochondrial DNA. Reciprocally, when ϱ- RNA was hybridized to ϱ+ and ϱ- mitochondrial DNA, the homologous cross produced again about twice as much hybrids as the heterologous cross. These results were confirmed by dehydridization-rehybridization experiments: the RNA separated from the hybrids “ϱ+ RNA × ϱ+ mit-DNA” as well as the RNA separated from the hybrids “ϱ+ RNA × ϱ- mit-DNA” were rehybridized either with ϱ+ or ϱ- mit-DNA. A preferential hybridization of ϱ+ RNA with ϱ+ mit-DNA, and of ϱ- RNA with ϱ- mit-DNA was clearly observed. On the contrary, ϱ+ and ϱ- nuclear DNA did not distinguish ϱ+ or ϱ- RNA. The same series of experiments were carried out using a chromosomal mutation,P
7 to p7, leading to the same respiratory deficient phenotype. We found that the p7 mutation did not introduce a detectable change in mitochondrial DNA base sequence. The results support the idea that the cytoplasmic hereditary factor, ϱ, resides in mitochondrial DNA and that the ϱ- mutations studied correspond to a dispersed sequence modification covering about a half of the total mitochondrial DNA genome, leaving the other half unchanged. Alternatively, the results can be explained by a hypothesis in which mitochondrial DNA is a heterogeneous population of the molecules having more or less related sequences and the mutation leads to a selection of certain molecular species. 4 S RNA was found to contain RNA species which hybridize with mitochondrial DNA. The degree of hybridization was very different for ϱ+ and ϱ- S RNA, when they were hybridized with either ϱ+ or ϱ- mitochondrial DNA.
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TL;DR: DNA-DNA hybridization studies showed a considerably greater interaction between the radioactive chloroplast product and chloroplasts DNA than with nuclear DNA.
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TL;DR: The increase in this rate in the tetraploid cells is closely correlated with the increase in nuclear surface area, but not with the nuclear volume; this suggests a possible control of the rate of DNA synthesis by the nuclear membrane.
Abstract: Rates of DNA synthesis in root tip cells of diploid and autotetraploid snapdragon (Antirrhinum majus) seedlings and in diploid and tetraploid (mononucleate and bidiploid-nucleate) regenerating mouse-liver cells have been studied. The increase in this rate in the tetraploid cells is closely correlated with the increase in nuclear surface area, but not with the nuclear volume; this suggests a possible control of the rate of DNA synthesis by the nuclear membrane.
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TL;DR: Despite the variation in molecule populations derived from the three different preparative methods, there were consistent differences between mitochondrial DNA from wild-type and petite yeast in frequencies and size of circular molecules, as well as in length distribution patterns.
Abstract: Purified mitochondrial and nuclear DNA from diploid isogenic wild-type and vegetative-petite baker's yeast were analyzed by electron microscopy and by analytical ultracentrifugation in CsCl gradients. The buoyant densities in CsCl of nuclear DNA were identical for the two strains (rho = 1.700), but there was a difference between mitochondrial DNA from the wild type (rho = 1.684) and the petite (rho = 1.680). Electron microscopy revealed both circular and linear filaments for nuclear and for mitochondrial DNA of both strains. Nuclear DNA molecules included 6.5 per cent cyclic filaments principally measuring 2 mu or less in contour length, and linear filaments showing a unimodal, disperse length-distribution centered at about 2 to 3 mu, for both strains. Mitochondrial DNA for wild type varied depending upon the method used to extract and purify the molecules; showing only 7.5 per cent circular molecules from CsCl-subfractionated samples, as compared with 15 per cent circles from chloroform-extracted DNA not subjected to CsCl and up to 50 per cent circles from osmotically-lysed mitochondira, as reported in an earlier study. Modal lengths of circles occurred at about 2, 5, and 10 mu Increasing shear degradation also was evident in comparisons of the length-distribution patterns of linear molecules using the three preparative methods. Petite mitochondrial DNA contained 36-38 per cent circular molecules which measured 0.3-5.3 mu, but principally in the range of 0.3 to 2.0 mu whether from chloroform-extracted populations or from ones subfractionated in CsCl. A previous study of osmotically lysed mitochondria had shown a maximum of 8 per cent circles, which we now attribute to a failure, at that time, to detect circles measuring less than 1 mu, a substantial component encountered in the purified DNA samples in the present study. Linear filaments presented a unimodal length distribution in every case. Despite the variation in molecule populations derived from the three different preparative methods, there were consistent differences between mitochondrial DNA from wild-type and petite yeast in frequencies and size of circular molecules, as well as in length distribution patterns.
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TL;DR: The following conclusion may be reasonably drawn as far as wheat and its relatives are concerned: appreciable changes of DNA content might have resulted from chromosome aberrations accumulated in the course of genome differentiation of a common primitive genome at the diploid level.
Abstract: 1. Comparisons were made of DNA content per nucleus in common wheat, artificially synthesized 6x wheat, its parental species and three analyzers.2. DNA content per nucleus in the D genome analyzer was the lowest, B genome had a little lower DNA content than A genome, but the difference between the last two was not significant.3. Ssp. strangulata had a significantly higher DNA value than var. typica of the same species, Ae. squarrosa.4. Two strains of synthesized 6x wheat, ABD No. 1 and ABD No. 13, have nuclear DNA equal to the sum of the DNA contents of their respective parents. Nuclear DNA content of cultivated common wheat (Chinese Spring) is quite the same as that of synthesized 6x wheat, especially ABD No. 13.5. In three subspecies of T. aestivum, vulgare, spelta and macha no significant difference was found in DNA content per nucleus.6. Based on the above facts, the following conclusion may be reasonably drawn as far as wheat and its relatives are concerned:a) Appreciable changes of DNA content might have resulted from chromosome aberrations accumulated in the course of genome differentiation of a common primitive genome at the diploid level.b) The three different genomes, once established, have been appreciably stable and kept the amount of DNA constant either in diploid or polyploid condition.
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TL;DR: Relationships between nuclear volume, nuclear DNA content and radiosensitivity were studied on genera of a family, species of a genus, and strains a species to observe the radiosensitivity was more markedly correlated with the mean DNA content per chromosome than with the estimated interphase chromosome volume.
Abstract: Relationships between nuclear volume, nuclear DNA content and radiosensitivity were studied on genera of a family, species of a genus, and strains a species. Throughout the materials observed the radiosensitivity was more markedly correlated with the mean DNA content per chromosome than with the estimated interphase chromosome volume. Data involved information about an appreciable reduction in nuclear DNA cdntent in cultivated polyploid plants associated with a proportional reduction in radiosensitivity.