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Nuclear DNA
About: Nuclear DNA is a research topic. Over the lifetime, 3933 publications have been published within this topic receiving 185830 citations.
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TL;DR: These two evolutionary phenomena are closely linked and result from common causes, and are likely to be related to the evolution of cell size and nuclear DNA.
Abstract: THE pronounced differences in the DNA content of cell nuclei of vertebrates have recently been discussed1–3, but these articles did not mention the possible correlations between the evolution of nuclear DNA with the evolution of cell size which was simultaneously reviewed4. I now suggest that these two evolutionary phenomena are closely linked and result from common causes.
69 citations
TL;DR: Organelle DNA synthesis in root meristem and cultured cell line BY-2, both derived from Nicotiana tabacum cv, saw large amounts of preferential synthesis of DNA of both mitochondria and plastids occurred prior to cell nuclear DNA synthesis just after stationary phase cells were transferred to fresh medium.
Abstract: Organelle DNA synthesis in root meristem and cultured cell line BY-2, both derived from Nicotiana tabacum cv. Bright Yellow 2, was examined by immunofluorescence microscopy of Technovit sections with antibody against 5- bromodeoxyuridine (BrdU) and co-fluorescent staining with 4′,6-diamidino-2-phenylindole (DAPI) and quantitative Southern hybridization. In the root meristem, the mitochondrial DNAs (mtDNAs) were synthesized in a specific region near to the quiescent center, where a low frequency of DNA synthesis of cell nuclei was observed. The mitochondrial nuclei (nucleoids) changed morphologically from long ellipsoids with a high frequency of DNA synthesis, in the region just above the quiescent center, to granules with a low frequency of DNA synthesis, as cell distance from the quiescent center increased. Similar patterns were observed in the cultured tobacco cell line (BY-2), in which large amounts of preferential synthesis of DNA of both mitochondria and plastids occurred prior to cell nuclear DNA synthesis just after stationary phase cells were transferred to fresh medium. Granular mitochondria which vigorously synthesized mtDNA were observed in both lag phase and logarithmic growth phase cells. However, long, ellipsoidal mitochondria which showed a low frequency of mtDNA synthesis were observed in stationary phase cells. Morphological changes of plastids were more conspicuous than those of mitochondria. After the medium was renewed, spherical plastids became extremely elongated and string-like, for 24 h, but were divided into small pieces after the third day. Vigorous synthesis of plastid DNA (ptDNA) occurred during this period of plastids elongation.
69 citations
TL;DR: The DNA-rich matrices were virtually identical with previously isolated DNA-depleted matrices in recovery of total nuclear protein and overall polypeptide composition on sodium dodecyl sulfate-acrylamide gels as discussed by the authors.
Abstract: Rat liver nuclear matrices isolated by a method which limits DNA degradation contain a major portion of the total nuclear DNA. A majority of the DNA sediments at greater than or equal 100 S on alkaline sucrose gradients, which represents an estimated single strand size of greater than or equal to 500 kilobases. These DNA-rich matrices were virtually identical with previously isolated DNA-depleted matrices in recovery of total nuclear protein and overall polypeptide composition on sodium dodecyl sulfate-acrylamide gels. Thin-sectioning electron microscopy revealed a structure similar to the DNA-depleted matrices with the addition of a prominent meshwork of DNA fibrils extended throughout the matrix interior. In vivo labeling of regenerating livers showed a continuous association of newly replicated DNA with DNA-rich matrices (greater than or equal to 80% of total labeled DNA) which is independent of the pulse period (1 min to 4 h). Moreover, the matrix-associated DNA is highly enriched in replicating intermediates after a 1-min in vivo pulse including a small amount of the primary Okazaki fragments. The matrix-associated replicating intermediates (4-50 S) are effectively chased into DNA of replicon size and larger (100 S) following a 1-h pulse. DNA-rich nuclear matrices may therefore provide a useful in vitro system for studying DNA replication in correlation with the higher order, intranuclear arrangement of eukaryotic DNA.
69 citations
TL;DR: This review describes DNA repair systems in mammalian mitochondria, such as base excision repair (BER) and microhomology–mediated end joining (MMEJ) and discusses a possibility of existence of mitochondrial DNA repair mechanisms otherwise typical for the nuclear DNA.
Abstract: Accumulation of mutations in mitochondrial DNA leads to the development of severe, currently untreatable diseases. The contribution of these mutations to aging and progress of neurodegenerative diseases is actively studied. Elucidation of DNA repair mechanisms in mitochondria is necessary for both developing approaches to the therapy of diseases caused by mitochondrial mutations and understanding specific features of mitochondrial genome functioning. Mitochondrial DNA repair systems have become a subject of extensive studies only in the last decade due to development of molecular biology methods. DNA repair systems of mammalian mitochondria appear to be more diverse and effective than it had been thought earlier. Even now, one may speak about the existence of mitochondrial mechanisms for the repair of single- and double-stranded DNA lesions. Homologous recombination also takes place in mammalian mitochondria, although its functional significance and molecular mechanisms remain obscure. In this review, I describe DNA repair systems in mammalian mitochondria, such as base excision repair (BER) and microhomology-mediated end joining (MMEJ) and discuss a possibility of existence of mitochondrial DNA repair mechanisms otherwise typical for the nuclear DNA, e.g., nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination, and classical non-homologous end joining (NHEJ). I also present data on the mechanisms for coordination of the nuclear and mitochondrial DNA repair systems that have been actively studied recently.
69 citations
TL;DR: The supplementary DNA fraction which distinguishes outbreeding from inbreeding species has, at most, surprisingly little effect upon the growth and development of the Lolium hybrids.
Abstract: Inbreeding species of Lolium have about 40 per cent more nuclear DNA than the outbreeding species. Even so inbreeders may be readily hybridised with outbreeders to produce viable F1's which, in many cases, are fertile, producing F2 progenies on intercrossing or backcross progenies when crossed with the parents. Recombination between and within chromosomes at meiosis in the F1 results in the quantitative segregation of DNA to the nuclei of gametes and of F2 and backcross progenies. An assay of the effects of the DNA variation among these progenies showed no influence of DNA amount upon the expression of 19 phenotypic characters, ranging from early seedling growth to flowering. There was, however, a very slight reduction from expectation in the mean DNA amount of backcross and F2 progenies. Apart from this slight effect on viability, either of gametes or of zygotes with high nuclear DNA content, our assay shows that the supplementary DNA fraction which distinguishes outbreeding from inbreeding species has, at most, surprisingly little effect upon the growth and development of the Lolium hybrids.
69 citations