Showing papers on "Nuclear DNA published in 1972"
TL;DR: It is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species, and that satellite DNA is significant in its nucleotypic effects on developmental processes.
Abstract: Many components of cell and nuclear size and mass are correlated with nuclear DNA content in plants, as also are the durations and rates of such developmental processes as mitosis and meiosis. It is suggested that the multiple effects of the mass of nuclear DNA which affect all cells and apply throughout the life of the plant can together determine the minimum generation time for each species. The durations of mitosis and of meiosis are both positively correlated with nuclear DNA content and, therefore, species with a short minimum generation time might be expected to have a shorter mean cell cycle time and mean meiotic duration, and a lower mean nuclear DNA content, than species with a long mean minimum generation time. In tests of this hypothesis, using data collated from the literature, it is shown that the mean cell cycle time and the mean meiotic duration in annual species is significantly shorter than in perennial species. Furthermore, the mean nuclear DNA content of annual species is significantly lower than for perennial species both in dicotyledons and monocotyledons. Ephemeral species have a significantly lower mean nuclear DNA content than annual species. Among perennial monocotyledons the mean nuclear DNA content of species which can complete a life cycle within one year (facultative perennials) is significantly lower than the mean nuclear DNA content of those which cannot (obligate perennials). However, the mean nuclear DNA content of facultative perennials does not differ significantly from the mean for annual species. It is suggested that the effects of nuclear DNA content on the duration of developmental processes are most obvious during its determinant stages, and that the largest effects of nuclear DNA mass are expressed at times when development is slowest, for instance, during meiosis or at low temperature. It has been suggested that DNA influences development in two ways, directly through its informational content, and indirectly by the physical-mechanical effects of its mass. The term 'nucleotype' is used to describe those conditions of the nucleus which effect the phenotype independently of the informational content of the DNA. It is suggested that cell cycle time, meiotic duration, and minimum generation time are determined by the nucleotype. In addition, it may be that satellite DNA is significant in its nucleotypic effects on developmental processes.
710 citations
TL;DR: Tryptic peptides were resolved from the small subunit of highly purified Fraction I protein obtained from Nicotiana tabacum,Nicotiana glutinosa, NicOTiana glauca and four reciprocal, F1 hybrids and were inherited in a Mendelian manner.
200 citations
TL;DR: These experiments show that mtDNA is inherited cytoplasmically and maternally in Xenopus, and concludes that the nucleus does not contain a “master copy” of the mitochondrial sequences.
193 citations
TL;DR: The maternal mode of inheritance requires chloroplast DNA to code for the sequence of amino acids in the large subunit of Fraction I proteins isolated from Nicotiana species indigenous to Australia, in contrast to a previous finding that nuclear DNA codes for the small subunit.
174 citations
TL;DR: This chapter discusses the origin of the wide species variation in nuclear DNA content, which is attributable to the amplification or reduction of DNA segments within chromosomes.
Abstract: Publisher Summary This chapter discusses the origin of the wide species variation in nuclear DNA content. Evolution depends upon the selection of phenotypes displaying adaptive changes of a heritable nature. The generation of such phenotypes depends on the alteration of genetic information embodied within the DNA of the chromosomes. As for evolutionary change in DNA amount , there is a progression from low DNA content in primitive phyla, such as bacteria to high DNA content in cells of sophisticated higher plants and animals. The causes of change in DNA amount are illustrated in the chapter. Polyploidy, common in plant groups such as the angiosperms and pteridophytes, is a special case as it involves amplification of all genes and all base sequences of the haploid complement. There is an extensive and widespread variation in DNA amount, which is independent of alteration in chromosome number. This is attributable to the amplification or reduction of DNA segments within chromosomes.
165 citations
TL;DR: The cellular DNA's of Dictyostelium discoideum have been characterized by their behavior in CsCl buoyant density-gradient centrifugation and by their renaturation kinetics and the complexity of the nuclear DNA is but 11 times that of Escherichia coli.
154 citations
TL;DR: Length measurements on heteroduplexes displaying the loop characteristic of substitutions have established that these molecules are from true sequence substitutions, and not from adjacent or overlapping deletions.
Abstract: The heteroduplex molecules formed by self-annealing of denatured, singly nicked simian virus 40 (SV40) deoxyribonucleic acid (DNA) prepared from closed viral DNA were examined by formamide-protein film electron microscopy to test the DNA for sequence homogeneity. Sequence inhomogeneity appears in the heteroduplexes as single-strand loops. These result from sequence deletion or from sequence substitution, if regions greater than 50 nucleotides are involved. The undenatured DNA from viruses passaged twice at multiplicities of infection much less than 1 plaque-forming unit (PFU) per cell appeared to be homogeneous in size. The heteroduplexes formed by this DNA indicated that approximately 2% of the molecules carried deletions, but that substitutions were below the level of detection. In contrast, undenatured DNA from viruses grown by passaging undiluted lysates seven times or by infection with stock virus at a multiplicity of infection of 5 PFU per cell contained a large frequency of molecules shorter than the full length. The heteroduplex samples indicated that 12 and 7% of the undenatured material contained base substitutions, and 13 and 11% contained deletions. The deletions and substitutions appear to occur in separate molecules. Length measurements on heteroduplexes displaying the loop characteristic of substitutions have established that these molecules are from true sequence substitutions, and not from adjacent or overlapping deletions. More than 80% of the molecules carrying substitutions are shorter than the native SV40 length. On the average, the substituted sequence is about 20% of the length of SV40, but it replaces a sequence about 30% of the native length. The substituted sequences may be host cell nuclear DNA, possibly arising from integration of SV40 into the chromosome followed by excision of the SV40 DNA together with chromosomal DNA.
140 citations
TL;DR: It is concluded that the nuclear membrane is the sole nuclear location of glucose-6-phosphatase, and by three criteria this enzyme was identical with pure authentic nuclear DNA polymerase.
Abstract: 1
A rapid, mild method for isolating nuclear membranes from isolated rat liver nuclei is described. The method employs a double digestion of nuclei with a low level of DNAase I at approximately 0.1 mM Mg2+ and slightly alkaline pH, to release the membranes.
2
Electron microscopy shows excellent preservation of the nuclear membrane morphology. Large membrane fragments consisting of a double membrane with ribosomes adhering to the outer layer are produced. The layers are connected at nuclear pores, which have distinct annular subunits and occasional central granules. Contamination by other subcellular structures is minimal.
3
The recoveries of nuclear protein, DNA, RNA and phospholipid in the membrane are approximately 8%, 1–3%, 8% and 55%, respectively. The DNA associated with the membrane does not appear to result from the reassociation of released DNA. The enzymic content of the membrane is similar to that of the microsomes. It is concluded that the nuclear membrane is the sole nuclear location of glucose-6-phosphatase.
4
About 1% of the total nuclear DNA polymerase was recovered associated with the nuclear membrane. By three criteria this enzyme was identical with pure authentic nuclear DNA polymerase. This finding is discussed against the background of the suggestions that the nuclear membrane is involved in DNA replication.
138 citations
TL;DR: In all three cell lines EB treatment led to a structural alteration of covalently closed mitochondrial DNA, consisting in part of a change to an increased degree of supercoiling and in addition breakage of circular DNA without re-closing, which was reversible by subsequent growth of cells in EB-free medium.
123 citations
TL;DR: Nuclear DNA amounts of fifteen species of placental mammals were determined by Feulgen cytophotometry, finding that the largest known mammalian genome contains about twice the DNA of the smallest one.
Abstract: Nuclear DNA amounts of fifteen species of placental mammals were determined by Feulgen cytophotometry. Relative values for several widely used species have been ascertained with an error of only a few percent. Absolute values (picograms or numbers of nucleotide pairs) can be determined with an error of about ten percent. The largest known mammalian genome contains about twice the DNA of the smallest one. The modal diploid DNA amount for mammals is slightly above eight picograms.
121 citations
TL;DR: Ritonucleic acid extracted from four stages during the developmental cycle of the cellular slime mold Dictyostelium discoideum was hybridized with purified single-copy nuclear DNA, indicating that there are, during development, qualitative and quantitative changes in the portion of the single- copies of the genome transcribed.
TL;DR: Measurements of actinomycin-3H binding in synchronized HeLa cells reveal that the binding capacity of chromatin decreases progressively during the S phase despite a doubling of nuclear DNA content, reaches a minimal level during G2 and mitosis, and then increases gradually throughout the subsequent G1 interval.
Abstract: Measurements of actinomycin-3H binding in synchronized HeLa cells reveal that the binding capacity of chromatin decreases progressively during the S phase despite a doubling of nuclear DNA content, reaches a minimal level during G2 and mitosis, and then increases gradually throughout the subsequent G1 interval. Since this pattern was evident in experiments with living cells, ethanol-fixed cells, and isolated nuclei, but not with purified DNA, the actinomycin binding profile may reflect changes in the degree of association between DNA and chromosomal proteins at different stages of the cell cycle.
TL;DR: Sedimentation analysis of nuclear DNA released from spheroplasts of the yeast Saccharomyces cerevisiae indicates that it has a number average molecular weight, and it is proposed that each yeast chromosome contains a single DNA duplex.
Abstract: Sedimentation analysis of nuclear DNA released from spheroplasts of the yeast Saccharomyces cerevisiae indicates that it has a number average molecular weight of 6.2 × 108. The chromosomal DNA molecules range in size from as small as 5 × 107 daltons to as large as 1.4 × 109 daltons. Based on these values and estimates of the total DNA content of the yeast nucleus, it is proposed that each yeast chromosome contains a single DNA duplex.
TL;DR: Comparison of viral DNA extracted from nuclei with that extracted from mature cytoplasmic virions in cells labeled for 120 min indicates that packaged DNA is not randomly selected from among the nuclear DNA population but rather represents DNA molecules which in alkaline gradients yield a minimal number of fragments.
Abstract: Deoxyribonucleic acid (DNA) extracted from herpes simplex virions forms multiple partially overlapping bands upon denaturation and centrifugation in alkaline sucrose density gradients. The most rapidly sedimenting DNA corresponds to an intact strand 48 x 10(6) daltons in molecular weight. In this study, we analyzed the DNA fragments generated in alkaline sucrose gradients with respect to size and uniqueness of base sequences. The distribution of sedimentation constants of the various fragments obtained in numerous gradients showed that the fragments smaller than the whole strand fall into six distinct classes ranging in molecular weight from 10 x 10(6) to 39 x 10(6) daltons. Four types of DNA strands can be reconstructed from the whole strand and six fragments on the basis of their molecular weights. DNA from each of the bands self-hybridizes to a lower extent than unfractionated viral DNA, indicating that each of the bands preferentially contains sequences from one unique strand. The data permit reconstruction of four possible types of DNA duplexes differing in the positions of the strand interruptions. Analysis of viral DNA extracted from nuclei of cells labeled with (3)H-thymidine for intervals from 3 to 120 min showed that nascent DNA is invariably attached to small fragments and that the fragments become elongated only upon prolonged incubation of cells. The experiments suggest that viral DNA replication begins at numerous initiation sites along each strand and that the elongation beyond the size of the replication unit involves repair or ligation, or both. Since newly made DNA yields more fragments than viral DNA extracted from mature virions, it is suggested that the fragmentation of mature DNA on denaturation with alkali arises from incomplete processing of specific initiation sites. Comparison of viral DNA extracted from nuclei with that extracted from mature cytoplasmic virions in cells labeled for 120 min indicates that packaged DNA is not randomly selected from among the nuclear DNA population but rather represents DNA molecules which in alkaline gradients yield a minimal number of fragments.
TL;DR: A Mendelian mode of inheritance of fingerprints of tryptic peptides produced upon digestion of this protein moiety obtained from N. tabacum, N. glauca and their reciprocal hybrids is demonstrated.
TL;DR: The results indicate that DNA template activation involves direct interactions between polyanion and nuclear constituents and suggest the possibility that naturally occurring polyanions might have a role in the control of gene activity.
Abstract: Specific polyanions release DNA template restrictions for DNA synthesis in isolated rat liver nuclei. The degree to which DNA synthesis is enhanced can be correlated with a spectrum of changes in nuclear structure Each polyanion which is effective in the release of template restriction produces a characteristic alteration in nuclear ultrastructure. Polyanions which have no effect on DNA synthesis do not appear to cause any change in nuclear organization or ultrastructure. Parallel measurements of nuclear DNA release and nuclear volume changes also indicate that template-activating polyanions cause remarkable changes in the structural organization of the treated nuclei. These results indicate that DNA template activation involves direct interactions between polyanions and nuclear constituents and suggest the possibility that naturally occurring polyanions might have a role in the control of gene activity
TL;DR: In this article, DNA from spermatids, 4-cell stages, and larvae of Ascaris lumbricoides was isolated, and the genome size before and after chromatin elimination was determined by isotope dilution.
TL;DR: The sedimentation behavior of high molecular weight nuclear and mitochondrial DNA from the yeast Saccharomyces cerevisiae has been examined and the molecular weights estimated based on a linear, double-stranded configuration are estimated.
TL;DR: G + C-rich “molecules” have been isolated from the bulk of mitochondrial DNA by virtue of their lower elution molarity from hydroxyapatite, thus providing the first evidence that yeast mitochondrial DNA has an “intermolecular” compositional heterogeneity at a size level of about 1.5 × 106 daltons.
TL;DR: DNA isolated from purified intact nuclei of Saccharomyces cerevisiae contains both the major band, α, and a dense satellite, γ, which gradually appears as a distinct band when the size of the nuclear DNA is reduced by controlled shearing.
TL;DR: Although it remains to be shown whether DNA methylation is related to the initiation of cancer, the data presented are consistent with the hypothesis that cytoplasmic mutations are involved in carcinogenesis.
TL;DR: RNase and alkaline digests of the mit[ 3 H]valyl-tRNA-mit-DNA hybrid yielded [ 3 H ]valyladenosine and [ 3H]valine, respectively, providing further evidence for the validity of the hybridization system.
TL;DR: It is shown here that preparations of nucleoli contain most of the nuclear satellite DNA and that contaminating main band DNA can be removed in preparative cesium chloride gradients.
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TL;DR: Nuclear DNA amounts of twenty-three species of birds from seventeen families of seven orders were determined by Feulgen cytophotometry, indicating an evolutionary control of genome size regardless of chromosome number.
Abstract: Nuclear DNA amounts of twenty-three species of birds from seventeen families of seven orders were determined by Feulgen cytophotometry. Genome size is constant in these birds, the ratio between the largest and smallest genome in the sample is 1.3 to 1. The modal diploid DNA amount for birds is about 3.6 picograms, slightly higher than previously reported. The data point towards an evolutionary control of genome size regardless of chromosome number. Birds represent an example of a group in which reduction of genome size is correlated with active speciation.
TL;DR: It is concluded that DNA replication occurs in close association with the nuclear membrane in HeLa cells.
TL;DR: Intramolecular heterogeneity of eukaryotic nuclear DNA is shown by main-band and satellite DNAs, and the function of the latter is uncertain, but they migrate more slowly in electrophoresis; this seems to be determined by base composition.
Abstract: Intramolecular heterogeneity of eukaryotic nuclear DNA is shown by main-band and satellite DNAs. The function of the latter is uncertain, but they migrate more slowly in electrophoresis; this seems to be determined by base composition.
TL;DR: The saturation and competition experiments indicate that there are separate genes for the two classes of rRNA, with the possible exception of a minor homology between 17-S and 25-S rRNA.
Abstract: DNA-RNA hybridization studies have been performed to determine the amount of rRNA genes present in purified nuclear DNA of Tetrahymena pyriformis cultured under various conditions of growth. It was found that 0.32% of the nuclear DNA isolated from exponentially growing cells hybridizes with an equimolar mixture of 17-S and 25-S rRNA. Nuclear DNA isolated from starved cells and from cells in the stationary growth phase hybridizes 30–40% less with rRNA than the nuclear DNA of the exponentially growing cells. This variation of the amount of rRNA genes to the total amount of nuclear DNA suggests that the replication of the rRNA genes and the rest of the nuclear DNA are under separate controls. With the possible exception of a minor homology between 17-S and 25-S rRNA, the saturation and competition experiments indicate that there are separate genes for the two classes of rRNA.
TL;DR: Replication of the DNA of chick embryo lethal orphan virus was semi-conservative and in CsCl density gradients a portion of pulse-labelled intracellular viral DNA was more dense than mature DNA and sometimes approached the density of denatured DNA.
TL;DR: The results obtained establish that leukemic nuclear DNA contains particle-related sequences that cannot be detected in normal leukocytes, which does not support the virogene-oncogene theory, which postulates the inclusion of at least one complete copy of oncogenic information in the genome of every normal cell.
Abstract: The central purpose of the present study was to test the proposition that the nuclear DNA of every human cell contains whatever information is necessary and sufficient for transformation to malignancy. The experiments were made possible by our earlier identification in human leukemic cells of particulate elements encapsulating 70S RNA and RNA-directed DNA polymerase. The [(3)H]DNA synthesized by these particles was used as a probe, through molecular hybridization, to normal and leukemic DNA. The results obtained establish that leukemic nuclear DNA contains particle-related sequences that cannot be detected in normal leukocytes. This outcome does not support the virogene-oncogene theory, which postulates the inclusion of at least one complete copy of oncogenic information in the genome of every normal cell. The data suggest that we may not be forced to cope with an omnipresent DNA segment coding for malignancy. Under the circumstances, we can perhaps entertain more hopeful pathways leading to the control and cure of cancer.