Showing papers on "Nuclear DNA published in 1968"
TL;DR: From these experiments it can be deduced that the heterogeneous nuclear RNA fraction is rapidly synthesized and degraded within the cell nucleus.
Abstract: The subcellular distribution of various types of RNA in HeLa cells is described. In addition, the relative rate of synthesis of the major classes of nuclear RNA has been determined. From these experiments it can be deduced that the heterogeneous nuclear RNA fraction is rapidly synthesized and degraded within the cell nucleus.
192 citations
TL;DR: It is revealed that widespread changes in nuclear DNA content accompanied the divergence and evolution of species within the genus Allium and provides information about the nature and the distribution of the chromosome structural changes which account for the variation innuclear DNA.
Abstract: Now that DNA is firmly established to be the carrier of genetic information much can be learned about the nature and origin of heritable variation by directly investigating qualitative and quantitative changes in the DNA itself. Qualitative differences in the base sequences and the base ratios of nucleic acids are reported for a number of species (e.g. Chargafl 1955; Reddi, 1959). A growing body of evidence also testifies to widespread variation in the quantity of nuclear DNA between species (e.g. McLeish and Sunderland, 1961; Keyl, 1964, 1965; Rees et al., 1966; Rothfels et al., 1966; Martin and Shanks, 1966; Martin, 1966; John and Hewitt, 1966). Such variation is especially common among Angiosperms and may be quite independent of change in chromosome number. The DNA differences are often large— even between species closely related. For example, Vicia faba has seven times more DNA than V. sativa (Rees et al., bc. cit.). Both are diploids, yet the variation in DNA content is equivalent to that between 2x and 1 4x. The following is an investigation of nuclear DNA variation in Allium. It reveals that widespread changes in nuclear DNA content accompanied the divergence and evolution of species within the genus. In addition it provides information about the nature and the distribution of the chromosome structural changes which account for the variation in nuclear DNA.
145 citations
TL;DR: Chromatography of total DNA from both wild-type cells and the cytoplasmic petite mutant has revealed the presence of a small nucleic acid component which is extremely rich in guanine; its origin is still unknown.
132 citations
TL;DR: The isolate of a DNA polymerase from rat liver mitochondria has been purified 22-fold by differential ultracentrifugation, ammonium sulfate precipitation, and column chromatography on DEAE-cellulose and the product was shown to be a double stranded replica of the mitochondrial DNA template.
132 citations
TL;DR: It is suggested that a high level of DNA and low rate of development restrict some frogs and salamanders to the vicinity of permanent water while a low level ofDNA and rapid rate ofDevelopment allow other frogs to invade arid environments.
Abstract: Data are presented on the amount of DNA in absorption units per nucleus for 43 species of frogs belonging to nine families. Values range from 4.5 au/nucleus in Scaphiopus holbrookii to 26 in Rana catesbeiana. Comparison of amounts of nuclear DNA and of minimum known durations of the larval stages indicates that the species that have the least amounts of nuclear DNA pass through the larval stages most rapidly. Data are also presented on the amount of nuclear DNA of two species of salamanders. It is suggested that a high level of DNA and low rate of development restrict some frogs and salamanders to the vicinity of permanent water while a low level of DNA and rapid rate of development allow other frogs to invade arid environments.
100 citations
TL;DR: Tetrahymena mitochondrial DNA had a relatively uniform sedimentation coefficient of 41S16 and was believed to represent an intact form existing in vivo, however, it was unsure whether the 41S DNA assumed a circular or linear structure.
Abstract: Mitochondrial DNA's from many vertebrates (mammals,'-7 birds,", I and amphibians') and at least one invertebrate (sea urchin9) heretofore examined exhibit a remarkable structural similarity. All of these DNA's were found in the form of closed circular duplex molecules of approximately 5 u in length, with an estimated molecular weight of 107 daltons. However, the estimates of the DNA content per mitochondrion vary in different types of mitochondria from one or two9 up to 14 molecules' 7 of 107 mol wt DNA. In fungi, Luck and Reich'? isolated a linear DNA filament of 13 million daltons from Neurospora mitochondria, and the presence in mitochondria of at least two distinct density species of DNA has been indicated." In yeast mitochondria the presence of rather heterogeneous-size linear filaments at least 5 A in length was observed by Sinclair et al.,12 but circular DNA species of varying length also present in the mitochondrial fraction were found to possess buoyant density identical to the corresponding nuclear DNA. This implies that the circular DNA might represent nuclear DNA contaminating the mitochondrial fraction. However, in separate experiments, Avers13 also observed in yeast mitochondria the presence of circular DNA molecules of up to 10.1 g in length and estimated that an equivalent of 10 A DNA molecule should be present per mitochondrion. In previous studies'4, 1 with protozoa (Tetrahymena and Paramecium) and several plants, we found DNA contents of 300 to 500 million daltons per mitochondrion. Purified Tetrahymena mitochondrial DNA had a relatively uniform sedimentation coefficient of 41S16 and was believed to represent an intact form existing in vivo. However, we were unsure whether the 41S DNA assumed a circular or linear structure. Studies were therefore made to examine Tetrahymena mitochondrial DNA by the Kleinschmidt's protein monolayer spreading technique."7 For comparison, DNA's of plants and monkey liver mitochondria were also included in these studies. Materials and Methods.-Tetrahymena mitochondria and mitochondrial DNA used in the present studies were isolated from ST strain of Tetrahymena pyriformis by the method described previously.'6 The isolated mitochondrial DNA showed a density of 1.686 gm cm-3 and less than 3% nuclear DNA contamination. Monkey (Macaca mulata) mitochondria were isolated from the liver (a courtesy of Dr. L. Mastroianni, Pennsylvania University Hospital) which was homogenized under aseptic conditions with a mortar and pestle in 0.25 M sucrose. The homogenate was centrifuged at 180 g for 6 min, and the resulting supernatant fluid was centrifuged at 5000 g for 6 min. The mitochondrial pellet was resuspended in the same sucrose medium and washed three times by repeated centrifugation at 10,000 g for 15 min. The final mitochondrial pellet was treated with DNase (16 ,g/ml at 0.05 M MgSO4), and DNA was isolated as described.4' 16 Purified DNA was prepared for electron-microscopic examinations by the method of Kleinschmidt and Zahn.17 To examine purified DNA, a DNA-cytochrome c (0.01%) mixture in 1 M ammonium acetate was layered over a water-hypophase surface. To examine DNA released by osmotic disruption, isolated mitochondria suspended in cold
90 citations
TL;DR: In this paper, the authors present evidence for similar cytoplasmic effects on DNA and RNA synthesis in isolated nuclei in, vitro, and show that these effects can stimulate RNA and/or DNA synthesis in nuclei which do not normally synthesize either.
82 citations
TL;DR: The mitochondrial DNA in the unfertilized egg of the sea urchin Lytechinus pictus is present in an amount approximately seven times that of the haploid nuclear DNA.
Abstract: The mitochondrial DNA in the unfertilized egg of the sea urchin Lytechinus pictus is present in an amount approximately seven times that of the haploid nuclear DNA.(1) The mitochondrial DNA has a higher buoyant density than the nuclear DNA and consists of circular duplex molecules of a uniform size of about 5µ. The circular DNA has been recovered(1) in both the intact (closed) and nicked (open) states characteristic of the circular duplex viral DNA's(2) and the mitochondrial DNA's from birds and mammals.(3, 4)
70 citations
TL;DR: In this paper, the sedimentation properties of the mitochondria of yeast were investigated and the results showed that the 4S RNA accepts amino acids in a manner similar to cytoplasmic tRNA; the other two RNA components were derived from mitochondrial ribosomes.
Abstract: MITOCHONDRIA contain small amounts of DNA which differ in several chemical and physical properties from nuclear DNA (reviewed in ref. 1). Mitochondrial DNA (MDNA) of yeast2–6 is replicated by a mitochondrial DNA polymerase7 which is different from the nuclear enzyme. (unpublished results of U. Wintersberger and E. W.). A genetic function of MDNA is indicated because it serves as a template for a mitochondrial RNA polymerase8,9. Mitochondrial RNA (MRNA) has been isolated and characterized using highly purified yeast mitochondria. MRNA of yeast separates into three species when subjected to sucrose gradient centrifugation, one with a sedimentation coefficient of about 4S, the other two sedimenting faster. The 4S RNA accepts amino-acids in a manner similar to cytoplasmic tRNA; the other two RNA components were assumed to be derived from mitochondrial ribosomes9. The two ribosomal RNA (rRNA) components of the mitochondria differ in their sedimentation properties from 25S and 17S RNA of the cytoplasmic 80S ribosomes of yeast, and, in contrast, closely resemble the 23S and 16S RNA species of bacterial 70S ribosomes10,11. Hybridization experiments show that yeast MRNA hybridizes readily with MDNA, in sharp contrast to cytoplasmic rRNA which forms hybrids with MDNA very poorly but anneals extensively to nuclear DNA11,12.
65 citations
TL;DR: The results are not consistent with any theory of de-novo or "microbody" origin of mitochondria, but do support the hypothesis that mitochondria are produced by the growth and division of preexisting mitochondria.
Abstract: A squash technique was developed for log phase Tetrahymena pyriformis which permitted the resolution of over 100 individual mitochondria from a single cell. Mitochondria incorporated thymidine at all stages of the cell cycle, even when nuclear DNA synthesis was not occurring. During the stage of macronuclear DNA synthesis, however, there was a significant increase in the extent of mitochondrial labeling. Low radioautograph background suggests that mitochondrial DNA is synthesized at the mitochondria themselves. All mitochondria incorporated thymidine-3H within one population-doubling time. Grain counts also showed that the amount of mitochondrial label was retained for four generations and that this label remained randomly distributed among all mitochondria during this time. The results are not consistent with any theory of de-novo or "microbody" origin of mitochondria, but do support the hypothesis that mitochondria are produced by the growth and division of preexisting mitochondria. The stability of the mitochondrial DNA and its distribution among daughter mitochondria satisfy two prerequisites for a genetic material. The possibility is discussed that some of the genetic information for the mitochondrion is contained in the DNA associated with this organelle.
64 citations
TL;DR: The buoyant density of nuclear and mitochondrial deoxyribonucleic acid from 14 species of fungi was determined by CsCl density gradient equilibrium centrifugation and no simple correlation could be obtained from the comparison of the two types of DNA.
Abstract: The buoyant density of nuclear and mitochondrial deoxyribonucleic acid (DNA) from 14 species of fungi was determined by CsCl density gradient equilibrium centrifugation. The buoyant density of both types of DNA was the same for all three Mucorales analyzed. The buoyant density of mitochondrial DNA was significantly lower than that of the nuclear DNA for nine species of Ascomycetes and two species of Basidiomycetes. No simple correlation could be obtained from the comparison of the two types of DNA. Mitochondrial DNA represented a very small proportion of total DNA. Heat-denatured mitochondrial DNA renatured more readily than nuclear DNA.
TL;DR: The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads toA decrease in biosynthetic reactions and eventual cell death.
Abstract: The loss of kinetoplast DNA in Leishmania tarentolae, which occurs in the presence of low concentrations of acriflavin, was found to be a result of selective inhibition of replication of this DNA. Nuclear DNA synthesis was relatively unaffected and cell and kinetoplast division proceeded normally for several generations. An approximately equal distribution of parental kinetoplast DNA between daughter kinetoplasts resulted in a decrease in the average amount of DNA per kinetoplast. The final disappearance of the stainable kinetoplast DNA occurred at a cell division in which all the remaining visible kinetoplast DNA was retained by one of the daughter cells. The selective inhibition of kinetoplast DNA synthesis was caused by a selective localization of acriflavin in the kinetoplast. The apparent intracellular localization of dye and the extent of uptake at a low dye concentration could be manipulated, respectively, by varying the hemin (or protoporphyrin IX) concentration in the medium and by adding red blood cell extract (or hemoglobin). Hemin and protoporphyrin IX were found to form a complex with acriflavin. During growth in acriflavin, cells exhibited an increasing impairment of colony-forming ability and rate of respiration. No change in the electrophoretic pattern of total cell soluble proteins was apparent. The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads to a decrease in biosynthetic reactions and eventual cell death. A possible use of the selective localization of acriflavin in the kinetoplast to photooxidize selectively the kinetoplast DNA is suggested.
TL;DR: It is concluded that one cannot necessarily expect to distinguish chloroplast DNA from nuclear DNA by virtue of the buoyant density, and the absence of the base 5-methylcytosine is perhaps the most reliable criterion for establishing the purity of chloropine.
TL;DR: Evidence that intrinsically synthesized protein may be exported from mitochondria provides a basis for possible morphogenetic action of these cell organelles.
TL;DR: Quantitative studies on the ffects of B-chromosomes in rye upon variation of the nuclear phenotype showed that B's have a structural organisation different to that of the A- chromosomes and influence the structure of the interphase nucleus in respect of non-permanent chromosome material.
Abstract: Quantitative studies on the ffects of B-chromosomes in rye upon variation of the nuclear phenotype showed that B's: (i) influence the phenotype of the A-chromosomes at metaphase of mitosis, (ii) increase the amount of nuclear DNA in proportion to their number present, (iii) have a structural organisation different to that of the A-chromosomes, (iv) influence the structure of the interphase nucleus in respect of non-permanent chromosome material.
TL;DR: The amount of DNA in the nuclei of the parenchymatous region was shown to increase in direct proportion to the distance of the nucleus from the meristem, and Mechanisms which might account for the observed changes in DNA per nucleus are discussed.
Abstract: relationships of the nuclei within the embryo. An equal amount of DNA was found in all meristematic nuclei regardless of the developmental stage of the embryo and was taken as the 2C value. Most of the nuclei in the parenchymatous region fell into the discrete DNA classes, 2C, 4C, and 8C. A significant number, however, had DNA contents above 8C but could not be grouped into classes based on a whole-number multiple of 2C. Nuclear size was found to vary in direct proportion to DNA content through 8C. Above 8C, correlation between nuclear size and DNA content was poor. The amount of DNA in the nuclei of the parenchymatous region was shown to increase in direct proportion to the distance of the nucleus from the meristem. The average amount of DNA in parenchymal nuclei above 8C was found to increase with the developmental stage of the embryo. Mechanisms which might account for the observed changes in DNA per nucleus are discussed.
TL;DR: The formation of common high molecular weight complexes during joint reannealing of two DNA's with complementary sequences was used as a method to detect sequence homology in different DNA samples and results are interpreted as indicating the continuity of mitochondrial DNA during evolution.
TL;DR: The various tetrapod classes show varying degrees of reduction in DNA nuclear content, with the highest levels being retained by the more primitive amphibians and the lowest levels being found in the highly evolved birds.
Abstract: This study attempts to correlate the amounts of DNA per nucleus in the various vertebrate classes with patterns of evolutionary change proposed by Simpson and by Rendel. It is suggested that an increase in the level of DNA/nucleus occurred in the protochordate stock ancestral to the vertebrates and that this led to a major shift from the protochordate to the vertebrate pattern (Rendel's Type 3, Simpson's quantum evolution). In the actinopterygian fishes this was followed by a loss of DNA/nucleus and by the establishment of a number of phyletic lines leading to the higher teleost orders (Rendel's Type 2, Simpson's phyletic evolution). In the Choanichthyes another major increase in the level of nuclear DNA was followed, in one line, by the quantum evolutionary shift to terrestrialism. The various tetrapod classes show varying degrees of reduction in DNA nuclear content, with the highest levels being retained by the more primitive amphibians and the lowest levels being found in the highly evolved birds. The two vertebrate groups with the lowest levels of DNA/nucleus are the higher teleosts and the birds, in which the dominant pattern of evolution today appears to be Rendel's Type 1, Simpson's speciation.
TL;DR: Until the chemical nature of this nonextractable fraction is known, cytoplasmic label following thymidine-3H treatment cannot necessarily be considered DNA, nor the assumption made that thym residues exclusively labels DNA.
Abstract: Tritiated thymidine routinely labels onion root cytoplasm during most of the cell cycle. One-third of this label could be cytochemically identified as DNA. The balance of the label was not RNA or a lipid, or attributable to labeled impurities in thymidine-3H. In electron microscope radioautographs one-third of the cytoplasmic silver grains was over organelles, presumably mitochondria and plastids. The other two-thirds of the silver grains in electron micrographs was distributed widely, 41% over ground cytoplasm and 10% over cell walls-cell membranes. Snake venom phosphodiesterase (SVDase) extracted a cytoplasmic fraction not degraded by DNase, and did not appear to extract nuclear DNA. The SVDase-extractable fraction may be DNA or a thymidine 5'-phosphoryl group in an ester linkage with another hydroxylic compound. The nature of the nonextractable fraction is considered. Possibilities discussed are: (1) technical problems such as the binding of an acid-labile nuclear DNA in the cytoplasm; (2) non-DNA, such as breakdown products, and thymine compounds other than DNA; (3) DNA, not extractable because of the nature of its binding to other compounds or because it is a "core" resistant to DNase. Until the chemical nature of this nonextractable fraction is known, cytoplasmic label following thymidine-3H treatment cannot necessarily be considered DNA, nor the assumption made that thymidine-3H exclusively labels DNA.
TL;DR: Evidence suggests that the amounts of DNA in individual nuclei are sometimes found to surpass 2 times the diploid value, the level at which division of the cell should occur, which explains the ultimate failure of thyroid function year3.
Abstract: Samples of tissue from human thyroids previously treated with 131I for hyperthyroidism and subsequently studied extensively for early and late radiation effects have ultimately become available for morphologic study A microspectrophotometric method has been used to measure the amount of DNA in individual nuclei Doses of 131I just sufficient to bring hyperthyroidism slowly under control but not to produce significant architectural derangement result in increased nuclear DNA and variations in amounts of DNA and nuclear volume Such changes correspond to the occasional bizarre nuclear forms previously recognized in such thyroids The amounts of DNA in individual nuclei are sometimes found to surpass 2 times the diploid value, the level at which division of the cell should occur Evidence suggests that this is thwarted cell division and probably explains the ultimate failure of thyroid function year3 after a euthyroid state had been achieved by 131I therapy Thyroid tissue from non-irradiated patie
TL;DR: In this article, the specific activity of liver nuclear and nucleolar DNA was determined on purified fractions and compared for pulses varying from 2 1 2 to 120 min, showing that the DNA isolated with the nucleolar subfraction is contained within the perinucleolar chromatin and its intranucleolar ramifications.
01 Jan 1968
TL;DR: In this paper, the authors found that the loss of kinetoplast DNA in Leishmania tarentolae, which occurs in the presence of low concentrations of acriflavin, was a result of selective inhibition of replication of this DNA.
Abstract: The loss of kinetoplast DNA in Leishmania tarentolae, which occurs in the presence of low concentrations of acriflavin, was found to be a result of selective inhibition of replication of this DNA. Nuclear DNA synthesis was relatively unaffected and cell and kinetoplast division proceeded normally for several generations. An approximately equal distribution of parental kinetoplast DNA between daughter kinetoplasts resulted in a decrease in the average amount of DNA per kinetoplast. The final disappearance of the stainable kinetoplast DNA occurred at a cell division in which all the remaining visible kinetoplast DNA was retained by one of the daughter cells. The selective inhibition of kinetoplast DNA synthesis was caused by a selective localization of acriflavin in the kinetoplast. The apparent intracellular localization of dye and the extent of uptake at a low dye concentration could be manipulated, respectively, by varying the hemin (or protoporphyrin IX) concentration in the medium and by adding red blood cell extract (or hemoglobin). Hemin and protoporphyrin IX were found to form a complex with acriflavin. During growth in acriflavin, cells exhibited an increasing impairment of colony-forming ability and rate of respiration. No change in the electrophoretic pattern of total cell soluble proteins was apparent. The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads to a decrease in biosynthetic reactions and eventual cell death. A possible use of the selective localization of acriflavin in the kinetoplast to photooxidize selectively the kinetoplast DNA is suggested.
TL;DR: Rates of incorporation of tritium-labeled thymidine into the mitochondrial and nuclear DNA of normal rat liver, regenerating liver, and four hepatomas with different growth rates and their host livers are studied.
Abstract: Rates of incorporation of tritium-labeled thymidine into the mitochondrial and nuclear DNA of normal rat liver, regenerating liver, and four hepatomas with different growth rates and their host livers
Journal Article•
TL;DR: Differences in the relative incorporation of thymidine-5-methyl-3H and cytidine into mitochondria and nuclei synthesizing DNA emphasize the need for caution in utilizing one labeled precursor as an index for DNA synthesis.
Abstract: Summary It has been found that the specific activity of thymidine-5-methyl-3H incorporation into the mitochondrial DNA of two transplantable hepatomas (3924A and H-35tc2) and host livers is less than the specific activity of the nuclear DNA. However, the ratio of mitochondrial DNA to nuclear DNA specific activity in both hepatomas and host livers is 10–100 times greater following cytidine-5-3H administration than the ratio following thymidine-5-methyl-3H administration. This marked difference in the ratios of the specific activities of thymidine and cytidine in mitochondrial and nuclear DNA of hepatomas and host livers appears to be the result of both an increase in cytidine incorporation into mitochondrial DNA compared to thymidine, and a decrease in cytidine incorporation into nuclear DNA compared to thymidine. These differences in the relative incorporation of thymidine-5-methyl-3H and cytidine-5-3H into mitochondria and nuclei synthesizing DNA emphasize the need for caution in utilizing one labeled precursor as an index for DNA synthesis. These results also emphasize the need for the examination of differences in pool size and availability of these two labeled precursors and the need for examination of the permeability of the membranes of the two organelles.
Journal Article•
TL;DR: A significant increase in the incorporation of 3H-formate into RNA of subcellular fractions of liver and into acid-soluble free nucleotides has been found in chicks treated with orotic acid.
Abstract: Effect of Orotic Acid on Activity of Nuclear DNA-dependent RNA Polymerase and Polyribosomal Profiles in Deficient Chick Liver lacking Vitamin B12
TL;DR: The result showed no difference in DNA content per nucleus among all varieties tested, indicating that changes in the amount of nuclear DNA might, if any, have had a minor significance in the improvement of common wheat.
Abstract: The microspectrophotometrical study was carried out on the relative amount of nuclear DNA of ten Japanese and 15 U.S. varieties of common wheat. The result showed no difference in DNA content per nucleus among all varieties tested, indicating that changes in the amount of nuclear DNA might, if any, have had a minor significance in the improvement of common wheat.
01 Jan 1968
TL;DR: The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads toA decrease in biosynthetic reactions and eventual cell death.
Abstract: The loss of kinetoplast DNA in Leishmania tarentolae, which occurs in the presence of low concentrations of acriflavin, was found to be a result of selective inhibition of replication of this DNA. Nuclear DNA synthesis was relatively unafTectcd and cell and kinetoplast divi sion proceeded normally for several generations. An approximately equal distribution of parental kinetoplast DNA between daughter kinetoplasts resulted in a decreEisc in the ' average amount of DNA per kinetoplast. The final disappearance of the stainable kineto plast DNA occurred at a cell division in which all the remaining visible kinetoplast DNA was retained by one of the daughter cells. The selective inhibition of kinetoplast DNA synthesis was caused by a selective localization of acriflavin in the kinetoplzist. The ap parent intracellular localization of dye and the extent of uptake at a low dye concentration could be manipulated, respectively, by varying the hemin (or protoporphyrin IX) concen tration in the medium and by adding red blood cell extract (or hemoglobin). Hemin and protoporphyrin IX were found to form a complex with acriflavin. During growth in acri flavin, cells exhibited an increasing impairment of colony-formin g ability and rate of respiration. No change in the electrophoretic pattern of total cell soluble proteins was apparent. The data fit the working hypothesis that the loss of kinetoplast DNA leads to a respiratory defect which then leads to a decrease in biosynthetic reactions and eventual cell death. A possible use of the selective localization of acriflavin in the kinetoplast to photooxidize .selectively the kinetoplast DNA is suggested.